Porous polybutylene succinate films enabling adhesion of human embryonic stem cell-derived retinal pigment epithelial cells (hESC-RPE)

In the last decade, several studies have shown that polybutylene succinate (PBSu)has a high potential as a biomaterial enabling cell adhesion and growth. In this study, porous PBSu films have been prepared by the breath figure method (BF)and by particulate leaching (PL), and characterized in terms of thickness, surface properties, diffusion capacity and in vitro stability. Because porous films are of high interest for tissue engineering of retinal pigment epithelium (RPE), the initial viability and adhesion of human embryonic stem cell-derived RPE onto the PBSu films was then evaluated. To the best of our knowledge, this is the first study on the adhesion behavior of hESC-RPE onto porous and biodegradable polymer surfaces. The results clearly demonstrated that the two manufacturing methods produced materials with very distinct properties. Films produced by BF expressively demonstrated the highest roughness and surface area, and the lowest water contact angle. These features likely contributed to increase the biocompatibility of the surface, particularly when coated with laminin and collagen IV, as observed by the improved cell viability, cell morphology, adhesion and production of extracellular matrix proteins. Altogether, our results showed not only that PBSu holds high potential in retinal tissue engineering, but also that the physical properties and biocompatibility of the material are highly dependent on the adopted casting method.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Tampere University, Tampere University Hospital
Contributors: Calejo, M. T., Haapala, A., Skottman, H., Kellomäki, M.
Number of pages: 10
Pages: 78-87
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: European Polymer Journal
Volume: 118
ISSN (Print): 0014-3057
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Polymers and Plastics, Organic Chemistry, Materials Chemistry
Keywords: Biodegradable films, Breath figures, Cell adhesion, Polybutylene succinate, Retinal pigment epithelium
Source: Scopus
Source ID: 85066269398

Research output: Contribution to journalArticleScientificpeer-review

Influence of ions to modulate hydrazone and oxime reaction kinetics to obtain dynamically cross-linked hyaluronic acid hydrogels

Dynamic covalent chemistry forming hydrazone and oxime linkages is attractive due to its simplicity, selectivity and compatibility under aqueous conditions. However, the low reaction rate at physiological pH hampers its use in biomedical applications. Herein, we present different monovalent and bivalent aqueous salt solutions as bio-friendly, non-toxic catalysts which can drive the hydrazone and oxime reactions with excellent efficacy at physiological pH. Direct comparison of hydrazone and oxime reactions using a small molecule model, without any salt catalysis, indicated that oxime formation is 6-times faster than hydrazone formation. Addition of different salts (NaCl, NaBr, KCl, LiCl, LiClO4, Na2SO4, MgCl2 and CaCl2) accelerated the pseudo-first-order reaction kinetics by ∼1.2-4.9-fold for acylhydrazone formation and by ∼1.5-6.9-fold for oxime formation, in a concentration-dependent manner. We further explored the potential of such catalysts to develop acylhydrazone and oxime cross-linked hyaluronic acid (HA) hydrogels with different physicochemical properties without changing the degree of chemical modification. Analogous to the small molecule model system, the addition of monovalent and divalent salts as catalysts significantly reduced the gelling time. The gelling time for the acylhydrazone cross-linked HA-hydrogel (1.6 wt%) could be reduced from 300 min to 1.2 min by adding 100 mM CaCl2, while that for the oxime cross-linked HA-hydrogel (1.2 wt%) could be reduced from 68 min to 1.1 min by adding 50 mM CaCl2. This difference in the gelling time also resulted in hydrogels with differential swelling properties as measured after 24 h. Our results are the first to demonstrate the use of salts, for catalyzing hydrogel formation under physiologically relevant conditions.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Research group: Biomaterials and Tissue Engineering Group, University of Montreal, Uppsala University
Contributors: Wang, S., Nawale, G. N., Oommen, O. P., Hilborn, J., Varghese, O. P.
Number of pages: 6
Pages: 4322-4327
Publication date: 21 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Polymer Chemistry
Volume: 10
Issue number: 31
ISSN (Print): 1759-9954
Original language: English
ASJC Scopus subject areas: Bioengineering, Biochemistry, Polymers and Plastics, Organic Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85070404630

Research output: Contribution to journalArticleScientificpeer-review

Highly efficient charge separation in model Z-scheme TiO2/TiSi2/Si photoanode by micropatterned titanium silicide interlayer

Atomic layer deposited (ALD) TiO2 is an attractive material for improving the photoactivity and chemical stability of semiconductor electrodes in artificial photosynthesis. Using photoelectrochemical (PEC) measurements, we show that an interfacial, topographically microstructured TiSi2 layer inside the TiO2/Si heterojunction improves the charge carrier separation and shifts the water dissociation onset potential to more negative values. These observations are correlated with the X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) measurements, which reveal an increased band bending due to the TiSi2 interlayer. Combined with the UV–Vis absorption results, the photoelectron spectroscopy measurements allow the reconstruction of the complete energy band diagram for the TiO2/TiSi2/Si heterojunction and the calculation of the valence and conduction band offsets. The energy band alignment and improvements in PEC results reveal that the charge transfer across the heterojunction follows a Z-scheme model, where the metal-like TiSi2 islands act as recombination centers at the interface.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Surface Science, Physics
Contributors: Hannula, M., Ali-Löytty, H., Lahtonen, K., Saari, J., Tukiainen, A., Valden, M.
Number of pages: 9
Pages: 237-245
Publication date: 1 Aug 2019
Peer-reviewed: Yes

Publication information

Journal: Acta Materialia
Volume: 174
ISSN (Print): 1359-6454
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Ceramics and Composites, Polymers and Plastics, Metals and Alloys
Keywords: Electrochemical characterization, Electronic band structure, Titanium dioxide, Transition metal silicides, X-ray photoelectron spectroscopy (XPS)
Source: Scopus
Source ID: 85066305210

Research output: Contribution to journalArticleScientificpeer-review

Hydrolysis and drug release from poly(ethylene glycol)-modified lactone polymers with open porosity

The ability to release active agents from a porous scaffold structure in situ enables the simultaneous structural support for the cells proliferating and differentiating towards tissue as well as the stimulation of tissue regeneration. Due to the great potentiality of such approach, drug-releasing scaffolds were fabricated from hydrolytically degradable polymers. Three copolymers of poly(ethylene glycol), ɛ-caprolactone, L- and D,L-lactide were synthesized and blended with bone-growth inducing active agents, dexamethasone (DM) and 2-phospho-L-ascorbic acid trisodium salt (AS). Porous scaffolds were prepared by means of super-critical carbon dioxide foaming. In the final scaffold structures, the particle size, location and the water solubility of the drug affected the release kinetics. As the large and water soluble AS particles were more exposed to the buffer solution compared to small DM particles, the AS release was burst-like whereas DM showed a long-term release. The material structure had a significant effect on the release kinetics as the porous scaffolds released active agents faster compared to the solid cylinders. Furthermore, this study showed the strong effect of polymer degradation and wettability on the release, which were more determinative than the pore architecture.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Aalto University, Orton Orthopaedic Hospital
Contributors: Asikainen, S., Paakinaho, K., Kyhkynen, A. K., Hannula, M., Malin, M., Ahola, N., Kellomäki, M., Seppälä, J.
Number of pages: 11
Pages: 165-175
Publication date: 1 Apr 2019
Peer-reviewed: Yes

Publication information

Journal: European Polymer Journal
Volume: 113
ISSN (Print): 0014-3057
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Organic Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: 2-Phospho-L-ascorbic acid trisodium salt, Bulk degradation, Dexamethasone, Drug release, Hydrolytic degradation, Supercritical carbon dioxide foaming
Source: Scopus
Source ID: 85060767586

Research output: Contribution to journalArticleScientificpeer-review

Transverse deformation of a lamellar TiAl alloy at high temperature by in situ microcompression

The distribution of strain in hard mode oriented lamellar stacks of the two-phase γ-TiAl/α2-Ti3Al alloy Ti-45Al-2Nb-2Mn (at.%)-0.8 vol% TiB2 was measured at several temperatures up to 633 °C by in situ micropillar compression, complemented by electron backscatter diffraction orientation mapping and digital image correlation strain mapping of a thermally stable surface Pt speckle pattern. Post-mortem transmission electron microscopy further identified the finest scale deformation structures. It was found that slip and twinning transverse to the lamellae operates within discreet bands that zigzag across the lamellar structure. The shear strain within each band is approximately constant across the pillar width. This is inconsistent with current energetic models for transverse twin formation in γ-TiAl, which assume independent, non-interacting twins. This is explained using a mathematical formulation for the stress required to operate this transverse mechanical twinning as a function of strain. This study has elucidated how the multi-scale combination of several transverse twinning systems on different {111} planes in γ-TiAl lamellae can relieve the elastic stresses generated at a lamellar interface by the primary (highest Schmid factor) twinning system. It is thought that the facilitation of this mechanism will promote the ductilisation of lamellar γ-TiAl alloys. This is crucial for an increased damage tolerance and ease of component manufacture, leading to a more widespread use of γ-TiAl alloys.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, University of Cambridge, Swiss Federal Laboratories for Materials Science and Technology
Contributors: Edwards, T. E. J., Di Gioacchino, F., Goodfellow, A. J., Mohanty, G., Wehrs, J., Michler, J., Clegg, W. J.
Number of pages: 15
Pages: 85-99
Publication date: 1 Mar 2019
Peer-reviewed: Yes
Early online date: 27 Nov 2018

Publication information

Journal: Acta Materialia
Volume: 166
ISSN (Print): 1359-6454
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Ceramics and Composites, Polymers and Plastics, Metals and Alloys
Keywords: Deformation twinning, Digital image correlation, Electron backscattering diffraction (EBSD), Scanning transmission electron microscopy, Titanium aluminide polysynthetically twinned crystal (PST)
Source: Scopus
Source ID: 85058779138

Research output: Contribution to journalArticleScientificpeer-review

Deformation of lamellar γ-TiAl below the general yield stress

The occurrence of plasticity below the macroscopic yield stress during tensile monotonic loading of nearly lamellar Ti-45Al-2Nb-2Mn(at%)-0.8 vol% TiB2 at both 25 °C and 700 °C, and in two conditions of lamellar thickness, was measured by digital image correlation strain mapping of a remodelled Au surface speckle pattern. Such initial plasticity, not necessarily related to the presence of common stress concentrators such as hard particles or cracks, could occur at applied stresses as low as 64% of the general yield stress. For a same applied strain it was more prominent at room temperature, and located as slip and twinning parallel to, and near to or at (respect.) lamellar interfaces of all types in soft mode-oriented colonies. These stretched the full colony width and the shear strain was most intense in the centre of the colonies. Further, the most highly operative microbands of plasticity at specimen fracture were not those most active prior to yielding. The strain mapping results from polycrystalline tensile loading were further compared to those from microcompression testing of soft-mode stacks of lamellae milled from single colonies performed at the same temperatures. Combined with post-mortem transmission electron microscopy of the pillars, the initial plasticity by longitudinal dislocation glide was found to locate within 30–50 nm of the lamellar interfaces, and not at the interfaces themselves. The highly localised plasticity that precedes high cycle fatigue failure is therefore inherently related to the lamellar structure, which predetermines the locations of plastic strain accumulation, even in a single loading cycle.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Materials Characterization, University of Cambridge, Swiss Federal Laboratories for Materials Science and Technology
Contributors: Edwards, T. E. J., Di Gioacchino, F., Goodfellow, A. J., Mohanty, G., Wehrs, J., Michler, J., Clegg, W. J.
Number of pages: 18
Pages: 122-139
Publication date: 15 Jan 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Acta Materialia
Volume: 163
ISSN (Print): 1359-6454
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Ceramics and Composites, Polymers and Plastics, Metals and Alloys
Keywords: Deformation twinning, Digital image correlation, Electron backscattering diffraction (EBSD), Pre-yield plasticity, Titanium aluminide
Source: Scopus
Source ID: 85055112164

Research output: Contribution to journalArticleScientificpeer-review

Solvent Welding and Imprinting Cellulose Nanofiber Films Using Ionic Liquids

Cellulose nanofiber films (CNFF) were treated via a welding process using ionic liquids (ILs). Acid-base-conjugated ILs derived from 1,5-diazabicyclo[4.3.0]non-5-ene [DBN] and 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) were utilized. The removal efficiency of ILs from welded CNFF was assessed using liquid-state nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The mechanical and physical properties of CNFF indicated surface plasticization of CNFF, which improved transparency. Upon treatment, the average CNFF toughness increased by 27%, and the films reached a Young's modulus of ∼5.8 GPa. These first attempts for IL "welding" show promise to tune the surfaces of biobased films, expanding the scope of properties for the production of new biobased materials in a green chemistry context. The results of this work are highly relevant to the fabrication of CNFFs using ionic liquids and related solvents.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Paper Converting and Packaging, Universidad Del Bío-Bío, Aalto University
Contributors: Reyes, G., Borghei, M., King, A. W. T., Lahti, J., Rojas, O. J.
Pages: 502-514
Publication date: 14 Jan 2019
Peer-reviewed: Yes
Early online date: 12 Dec 2018

Publication information

Journal: Biomacromolecules
Volume: 20
Issue number: 1
ISSN (Print): 1525-7797
Original language: English
ASJC Scopus subject areas: Bioengineering, Biomaterials, Polymers and Plastics, Materials Chemistry
Source: Scopus
Source ID: 85059629357

Research output: Contribution to journalArticleScientificpeer-review

High-speed production of antibacterial fabrics using liquid flame spray

Healthcare associated infections (HAIs) are known as one of the major problems of the modern healthcare system, which result in additional cost and mortality. It has also been shown that pathogenic bacteria are mostly transferred via surfaces in healthcare settings. Therefore, antibacterial surfaces, which include fabrics and textiles, can be used in a healthcare environment to reduce the transfer of pathogenic bacteria, hence reducing HAIs. Silver nanoparticles have been shown to have broad spectrum antibacterial properties, and therefore they have been incorporated into fabrics to provide antibacterial functionality. Liquid flame spray (LFS) nanoparticle synthesis allows nanoparticles to be produced and deposited on surfaces at speeds up to and beyond 300 m/min. Herein, LFS is used to deposit silver nanoparticles onto two fabrics that are commonly used in the hospital environment with the aim of producing antibacterial fabrics. A thin plasma coating on top of the fabrics after silver deposition is used to improve nanoparticle adhesion. Fabrics coated with silver nanoparticles demonstrated antibacterial properties against Escherichia coli. Nanoparticle imaging and surface chemical characterization are performed using scanning electron microscopy and X-ray photoelectron spectroscopy. The highlights of this research are as follows: • high-speed synthesis and deposition of silver nanoparticles on fabrics; • plasma coating onto fabrics with silver nanoparticles; • antibacterial fabrics for potential use in healthcare environments.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Aerosol Synthesis, Physics, Abo Akad Univ, Abo Akademi University, Dept Phys, RISE Research Institutes of Sweden AB, Turun yliopisto, University of Eastern Finland
Contributors: Brobbey, K. J., Haapanen, J., Tuominen, M., Mäkelä, J., Gunell, M., Eerola, E., Saarinen, J. J., Toivakka, M.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Textile Research Journal
ISSN (Print): 0040-5175
Original language: English
ASJC Scopus subject areas: Chemical Engineering (miscellaneous), Polymers and Plastics
Keywords: antibacterial, fabrics, liquid flame spray, nanoparticles, plasma deposition, silver
Source: Scopus
Source ID: 85071117647

Research output: Contribution to journalArticleScientificpeer-review

On the limit of superhydrophobicity: Defining the minimum amount of TiO2 nanoparticle coating

Fabrication of superhydrophobic surfaces in large scale has been in high interest for several years, also titanium oxide nanostructures having been applied for the purpose. Optimizing the amount and structure of the TiO2 material in the coating will play a key role when considering upscaling. Here, we take a look at fabricating the superhydrophobic surface in a one-step roll-to-roll pilot scale process by depositing TiO2 nanoparticles from a Liquid Flame Spray onto a moving paperboard substrate. In order to find the minimum amount of nanomaterial still sufficient for creating superhydrophobicity, we varied nanoparticle production rate, flame distance from the substrate and line speed. Since the deposited amount of material sideways from the flame path was seen to decrease gradually, spatial analysis enabled us to consistently determine the minimum amount of TiO2 nanoparticles on the substrate needed to achieve superhydrophobicity. Amount as low as 20-30 mg m-2 of TiO2 nanoparticles was observed to be sufficient. The scanning electron microscopy revealed that at this amount, the surface was covered with nanoparticles only partially, but still sufficiently to create a hierarchical structure to affect wetting significantly. Based on XPS analysis, it became apparent that TiO2 gathers hydrocarbons on the surface to develop the surface chemistry towards hydrophobic, but below the critical amount of TiO2 nanoparticles, the chemistry could not enable superhydrophobicity anymore. While varying the deposited amount of TiO2, besides the local spatial variance of the coating amount, also the overall yield was studied. Within the text matrix, a yield up to 44% was achieved. In conclusion, superhydrophobicity was achieved at all tested line speeds (50 to 300 m min-1), even if the amount of TiO2 varied significantly (20 to 230 mg m-2).

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, Research group: Aerosol Synthesis, Research area: Aerosol Physics, Materials Science, Packaging Technology Research Team, Physics at Interfaces, Max Planck Institute for Polymer Research, Bioscience and Materials/Surface, RISE Research Institutes of Sweden AB, Finnish Environment Institute, Abo Akad Univ, Abo Akademi University, Dept Phys, AGH University of Science and Technology, University of Eastern Finland
Contributors: Haapanen, J., Aromaa, M., Teisala, H., Juuti, P., Tuominen, M., Sillanpää, M., Stepien, M., Saarinen, J. J., Toivakka, M., Kuusipalo, J., Mäkelä, J. M.
Publication date: 2019
Peer-reviewed: Yes
Early online date: 5 Dec 2018

Publication information

Journal: Materials Research Express
Volume: 6
Issue number: 3
Article number: 035004
ISSN (Print): 2053-1591
Original language: English
ASJC Scopus subject areas: Electronic, Optical and Magnetic Materials, Biomaterials, Surfaces, Coatings and Films, Polymers and Plastics, Metals and Alloys
Keywords: liquid flame spray, nanocoatings, nanoparticles, superhydrophobic, TiO, titanium dioxide, wetting
Source: Scopus
Source ID: 85059238010

Research output: Contribution to journalArticleScientificpeer-review

Reliability evaluation of wearable radio frequency identification tags: Design and fabrication of a two-part textile antenna

Passive radio frequency identification-based technology is a convincing approach to the achievement of versatile energy- and cost-efficient wireless platforms for future wearable applications. By using two-part antenna structures, the antenna-electronics interconnections can remain non-stressed, which can significantly improve the reliability of the textile-embedded wireless components. In this article, we describe fabrication of two-part stretchable and non-stretchable passive ultra-high frequency radio frequency identification textile tags using electro-textile and embroidered antennas, and test their reliability when immersed as well as under cyclic strain. The results are compared to tags with traditional one-part dipole antennas fabricated from electro-textiles and by embroidery. Based on the results achieved, the initial read ranges of the two-part antenna tags, around 5 m, were only slightly shorter than those of the one-part antenna tags. In addition, the tag with two-part antennas can maintain high performance in a moist environment and during continuous stretching, unlike the one-part antenna tag where the antenna-integrated circuit attachment is under stress.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Wireless Identification and Sensing Systems Research Group
Contributors: Chen, X., Ukkonen, L., Virkki, J.
Publication date: 2019
Peer-reviewed: Yes
Early online date: 1 Jan 2018

Publication information

Journal: Textile Research Journal
Volume: 89
Issue number: 4
ISSN (Print): 0040-5175
Original language: English
ASJC Scopus subject areas: Chemical Engineering (miscellaneous), Polymers and Plastics
Keywords: E-textile antenna, embroidery antenna, radio frequency identification
Source: Scopus
Source ID: 85045121603

Research output: Contribution to journalArticleScientificpeer-review

Structure and Dynamics of Thermosensitive pDNA Polyplexes Studied by Time-Resolved Fluorescence Spectroscopy

Combining multiple stimuli-responsive functionalities into the polymer design is an attractive approach to improve nucleic acid delivery. However, more in-depth fundamental understanding how the multiple functionalities in the polymer structures are influencing polyplex formation and stability is essential for the rational development of such delivery systems. Therefore, in this study the structure and dynamics of thermosensitive polyplexes were investigated by tracking the behavior of labeled plasmid DNA (pDNA) and polymer with time-resolved fluorescence spectroscopy using fluorescence resonance energy transfer (FRET). The successful synthesis of a heterofunctional poly(ethylene glycol) (PEG) macroinitiator containing both an atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) initiator is reported. The use of this novel PEG macroinitiator allows for the controlled polymerization of cationic and thermosensitive linear triblock copolymers and labeling of the chain-end with a fluorescent dye by maleimide-thiol chemistry. The polymers consisted of a thermosensitive poly(N-isopropylacrylamide) (PNIPAM, N), hydrophilic PEG (P), and cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, D) block, further referred to as NPD. Polymer block D chain-ends were labeled with Cy3, while pDNA was labeled with FITC. The thermosensitive NPD polymers were used to prepare pDNA polyplexes, and the effect of the N/P charge ratio, temperature, and composition of the triblock copolymer on the polyplex properties were investigated, taking nonthermosensitive PD polymers as the control. FRET was observed both at 4 and 37 °C, indicating that the introduction of the thermosensitive PNIPAM block did not compromise the polyplex structure even above the polymer's cloud point. Furthermore, FRET results showed that the NPD- and PD-based polyplexes have a less dense core compared to polyplexes based on cationic homopolymers (such as PEI) as reported before. The polyplexes showed to have a dynamic character meaning that the polymer chains can exchange between the polyplex core and shell. Mobility of the polymers allow their uniform redistribution within the polyplex and this feature has been reported to be favorable in the context of pDNA release and subsequent improved transfection efficiency, compared to nondynamic formulations.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Utrecht University, Helsinki University, Chemistry and Advanced Materials
Contributors: Fliervoet, L. A., Lisitsyna, E. S., Durandin, N. A., Kotsis, I., Maas-Bakker, R. F., Yliperttula, M., Hennink, W. E., Vuorimaa-Laukkanen, E., Vermonden, T.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Biomacromolecules
ISSN (Print): 1525-7797
Original language: English
ASJC Scopus subject areas: Bioengineering, Biomaterials, Polymers and Plastics, Materials Chemistry
Electronic versions: 
Source: Scopus
Source ID: 85073002500

Research output: Contribution to journalArticleScientificpeer-review

Temperature scanning stress relaxation behavior of water responsive and mechanically adaptive elastomer nanocomposites

The decrease of stress at constant strain, that is, the stress relaxation process as a function of temperature, is a central mechanical characteristics of elastomer nanocomposites for their potential applications. However, in the conventional stress relaxation test, the relaxation behavior is usually determined as a function of time at constant temperature. The present work reports the temperature scanning stress relaxation (TSSR) characteristics of a new kind of mechanically adaptive elastomer nanocomposite by monitoring the nonisothermal relaxation behavior as a function of temperature. This kind of adaptive elastomer nanocomposite was prepared by introducing calcium sulfate (CaSO4), as the water-responsive phase into the hydrophilic elastomer matrix. The influence of water-induced structural changes on TSSR behavior was investigated. Water treatment had a strong effect on the shape of the relaxation spectrum of the nanocomposite. It was revealed that the in situ development of hydrated nano-rod crystal structures of CaSO4 in the elastomer matrix was responsible for the changes in the mechanical relaxation behavior of the composites. Atomic force microscopy was used to verify this nano-rod crystal morphology in the elastomer matrix. The mechanism of water-induced mechanical reinforcement of the composite was explored from dynamic mechanical analysis of the material and correlated with its stress relaxation behavior.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science and Environmental Engineering, Leibniz-Institut für Polymerforschung Dresden E.V., University of Massachusetts Lowell, Vodafone Department of Mobile Communications Systems
Contributors: Banerjee, S. S., Natarajan, T. S., Subramani B., E., Wießner, S., Janke, A., Heinrich, G., Das, A.
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Article number: 48344
ISSN (Print): 0021-8995
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: adaptive elastomer nanocomposite, calcium sulphate, mechanical reinforcement, morphology, temperature scanning stress relaxation
Source: Scopus
Source ID: 85070677934

Research output: Contribution to journalArticleScientificpeer-review

Textile-integrated three-dimensional printed and embroidered structures for wearable wireless platforms

In this paper, we present fabrication and performance evaluation of three-dimensional (3D) printed and embroidered textile-integrated passive ultra high frequency radio frequency identification (RFID) platforms. The antennas were manufactured by 3D printing a stretchable silver conductor directly on an elastic band. The electric and mechanical joint between the 3D printed antennas and microchips was formed by gluing with conductive epoxy glue, by printing the antenna directly on top of the microchip structure, and by embroidering with conductive yarn. Initially, all types of fabricated RFID tags achieved read ranges of 8–9 meters. Next, the components were tested for wetting as well as for harsh cyclic strain and bending. The immersing and cyclic bending slightly affected the performance of the tags. However, they did not stop the tags from working in an acceptable way, nor did they have any permanent effect. The epoxy-glued or 3D printed antenna–microchip interconnections were not able to endure harsh stretching. On the other hand, the tags with the embroidered antenna–microchip interconnections showed excellent wireless performance, both during and after a 100 strong stretching cycles. Thus, the novel approach of combining 3D printing and embroidery seems to be a promising way to fabricate textile-integrated wireless platforms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Wireless Identification and Sensing Systems Research Group
Contributors: He, H., Chen, X., Ukkonen, L., Virkki, J.
Publication date: 2019
Peer-reviewed: Yes
Early online date: 1 Jan 2018

Publication information

Journal: Textile Research Journal
Volume: 89
Issue number: 4
ISSN (Print): 0040-5175
Original language: English
ASJC Scopus subject areas: Chemical Engineering (miscellaneous), Polymers and Plastics
Keywords: antennas, embroidery, interconnections, passive ultra high frequency radio frequency identification, stretchable electronics, textile-integrated electronics, three-dimensional printing, wearable platforms
Source: Scopus
Source ID: 85045101109

Research output: Contribution to journalArticleScientificpeer-review

Mechanical, thermal, and burning properties of viscose fabric composites: Influence of epoxy resin modification

The influence of epoxy resin modification by 3-aminopropyltriethoxysilane (APTES) on various properties of warp knitted viscose fabric is reported in this study. Dynamic mechanical, impact resistance, flexural, thermal properties, and burning behavior of the epoxy/viscose fabric composites are studied with respect to varying content of silane coupling agent. The results obtained for APTES-modified epoxy resin based composites reinforced with unmodified viscose fabric composites are compared to unmodified epoxy resin based composites reinforced with APTES-modified viscose fabric. The dynamic mechanical behavior of the APTES-modified resin based composites indicates improved interfacial adhesion. The composites prepared from modified epoxy resin exhibited a twofold increase in impact resistance. The improved adhesion between the fiber and modified resin was also visible from the scanning electron microscope analysis of the impact fracture surface. There was less influence of resin modification on the flexural properties of the composites. The 5% APTES modification induced early degradation of composites compared to all other composites. The burning rate of all the composites under study is rated to be satisfactory for use in automotive interior applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Centria University of Applied Sciences, University of Borås, Yanbu Industrial College, Jozef Stefan Institute, Swedish Centre for Resource Recovery
Contributors: Rajan, R., Rainosalo, E., Ramamoorthy, S. K., Thomas, S. P., Zavašnik, J., Vuorinen, J., Skrifvars, M.
Publication date: 20 Sep 2018
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 135
Issue number: 36
Article number: 46673
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2018): CiteScore 2.25 SJR 0.554 SNIP 0.814
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: cellulose and other wood products, functionalization of polymers, mechanical properties, thermal properties, thermosets

Bibliographical note

EXT="Skrifvars, Mikael"

Source: Scopus
Source ID: 85049105961

Research output: Contribution to journalArticleScientificpeer-review

Thermal Isomerization of Hydroxyazobenzenes as a Platform for Vapor Sensing

Photoisomerization of azobenzene derivatives is a versatile tool for devising light-responsive materials for a broad range of applications in photonics, robotics, microfabrication, and biomaterials science. Some applications rely on fast isomerization kinetics, while for others, bistable azobenzenes are preferred. However, solid-state materials where the isomerization kinetics depends on the environmental conditions have been largely overlooked. Herein, an approach to utilize the environmental sensitivity of isomerization kinetics is developed. It is demonstrated that thin polymer films containing hydroxyazobenzenes offer a conceptually novel platform for sensing hydrogen-bonding vapors in the environment. The concept is based on accelerating the thermal cis-trans isomerization rate through hydrogen-bond-catalyzed changes in the thermal isomerization pathway, which allows for devising a relative humidity sensor with high sensitivity and quick response to relative humidity changes. The approach is also applicable for detecting other hydrogen-bonding vapors such as methanol and ethanol. Employing isomerization kinetics of azobenzenes for vapor sensing opens new intriguing possibilities for using azobenzene molecules in the future.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Chemistry and Bioengineering, Aalto University
Contributors: Poutanen, M., Ahmed, Z., Rautkari, L., Ikkala, O., Priimägi, A.
Number of pages: 6
Pages: 381-386
Publication date: 20 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 7
Issue number: 3
ISSN (Print): 2161-1653
Ratings: 
  • Scopus rating (2018): CiteScore 5.82 SJR 2.201 SNIP 1.255
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics, Inorganic Chemistry, Materials Chemistry
Source: Scopus
Source ID: 85044222959

Research output: Contribution to journalArticleScientificpeer-review

Soft hydrazone crosslinked hyaluronan- and alginate-based hydrogels as 3D supportive matrices for human pluripotent stem cell-derived neuronal cells

Regenerative medicine, especially cell therapy combined with a supportive biomaterial scaffold, is considered to be a potential treatment for various deficits in humans. Here, we have produced and investigated the detailed properties of injectable hydrazone crosslinked hyaluronan-polyvinyl alcohol (HA-PVA) and alginate-polyvinyl alcohol (AL-PVA) hydrogels to be used as a supportive biomaterial for 3D neural cell cultures. To the best of our knowledge, this is the first time the polymerization and properties of hydrazone crosslinked AL-PVA hydrogel have been reported. The effect of the degree of substitution and molecular weight of the polymer components as well as the polymer concentration of the hydrogel on the swelling, degradation and mechanical properties of the hydrogels is reported. Furthermore, we studied the effect of the above parameters on the growth of human pluripotent stem cell-derived neuronal cells. The most neural cell supportive HA-PVA hydrogel was composed of high molecular weight HA component with brain-mimicking mechanical properties and decreased polymer concentration. AL-PVA hydrogel, with stiffness quite similar to brain tissue, was also shown to be similarly supportive. Neuronal spreading and 3D network formation was enhanced inside the softest hydrogels.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Biomaterials and Tissue Engineering Group, BioMediTech Institute and Faculty of Medicine and Life Sciences
Contributors: Karvinen, J., Joki, T., Ylä-Outinen, L., Koivisto, J. T., Narkilahti, S., Kellomäki, M.
Number of pages: 11
Pages: 29-39
Publication date: 1 Mar 2018
Peer-reviewed: Yes

Publication information

Journal: Reactive and Functional Polymers
Volume: 124
ISSN (Print): 1381-5148
Ratings: 
  • Scopus rating (2018): CiteScore 3.21 SJR 0.712 SNIP 0.901
Original language: English
ASJC Scopus subject areas: Chemistry(all), Environmental Chemistry, Biochemistry, Chemical Engineering(all), Polymers and Plastics, Materials Chemistry
Keywords: 3D neuronal culture, Alginate, Hyaluronan, Hydrazone, Hydrogel
Source: Scopus
Source ID: 85040229275

Research output: Contribution to journalArticleScientificpeer-review

Temperature scanning stress relaxation of an autonomous self-healing elastomer containing non-covalent reversible network junctions

In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Vodafone Department of Mobile Communications Systems, University of Applied Sciences Osnabrück, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Das, A., Sallat, A., Böhme, F., Sarlin, E., Vuorinen, J., Vennemann, N., Heinrich, G., Stöckelhuber, K. W.
Publication date: 19 Jan 2018
Peer-reviewed: Yes

Publication information

Journal: Polymers
Volume: 10
Issue number: 1
Article number: 94
ISSN (Print): 2073-4360
Ratings: 
  • Scopus rating (2018): CiteScore 3.25 SJR 0.724 SNIP 1.057
Original language: English
ASJC Scopus subject areas: Chemistry(all), Polymers and Plastics
Keywords: Bromo-butyl rubber, Ionic modification, Reversible polymer network, Self-healing, Stress-relaxation
Electronic versions: 
Source: Scopus
Source ID: 85040774453

Research output: Contribution to journalArticleScientificpeer-review

Fabrication and characterization of magnetic cotton yarns for textile applications

Cotton yarns covered with hard (barium hexaferrite – BaFe), and soft (Black Toner 6745 CP-313) magnetic particles are investigated for their application in the field of functional textile. Our results reveal a rather consistent dependence of the magnetic yarn properties on the fabrication parameters (nature of the magnetic powder, composition of the coating solution, etc.). The magnetic properties (residual magnetism and coercive field intensity) of the yarns are increasing with the magnetic powder content in the coating solution. However, this is at some point leading to the degradation of some yarn properties, e.g. elasticity. Bending tests revealed that several factors improve the bending behavior of the yarns and reduce cracks. For example, a higher number of cracks were exhibited by the hard magnetic yarns compared to the soft ones. The presence of polyurethane in the coating solution leads to no cracks on the surface of hard magnetic yarns or a small number in case of soft magnetic yarns. The tensile properties of the magnetic yarns are increasing with increasing magnetic powder content. Over a certain mass percentage (45% for BaFe and 30% for CP-313), the magnetic yarns tensile strength and elongation become lower than those of the support yarn.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Physics, National Institute for Textile and Leather, Universitatea Tehnica Gh. Asachi din IasI, IT Center for Science and Technology, 25 Av. Radu Beller, Bucharest, Romania
Contributors: Grosu, M. C., Lupu, I. G., Cramariuc, O., Hogas, H. I.
Number of pages: 12
Pages: 1348-1359
Publication date: 2018
Peer-reviewed: Yes
Early online date: 20 Jan 2018

Publication information

Journal: Journal of the Textile Institute
Volume: 109
Issue number: 10
ISSN (Print): 0040-5000
Ratings: 
  • Scopus rating (2018): CiteScore 1.32 SJR 0.389 SNIP 0.837
Original language: English
ASJC Scopus subject areas: Materials Science (miscellaneous), Agricultural and Biological Sciences(all), Polymers and Plastics, Industrial and Manufacturing Engineering
Keywords: bending test, Cotton yarns, hysteresis, magnetic layers, microscopic analysis, wash test
Source: Scopus
Source ID: 85041119144

Research output: Contribution to journalArticleScientificpeer-review

Improved electromechanical response in acrylic rubber by different carbon-based fillers

Dielectric elastomers are materials often utilized for the fabrication of electroactive actuators. Acrylic rubber (ACM) is very widely used in dielectric elastomer actuators (DEAs). However, its overall good performance is limited by the high operating electric field required. In the present work, we compare the effect of different types of conventionally used carbon black (CB) as well as other carbon-based fillers on the dielectric and actuation properties of ACM in order to show that performance of DEAs can be improved by the development of ACM composites. Indeed, addition of CB, carbon nanotubes (CNTs), and synthetic graphite leads to an increase in the relative dielectric permittivity of elastomeric material. Moreover, incorporation of nanodiamonds results in reduction of dielectric losses. Finally, actuation stress is remarkably improved by CNTs and different grades of CB.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Plastics and Elastomer Technology, Leibniz Institute of Polymer ResearchDresdenD
Contributors: Shakun, A., Poikelispää, M., Das, A., Vuorinen, J.
Pages: 395-404
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: Polymer Engineering and Science
Volume: 58
Issue number: 3
ISSN (Print): 0032-3888
Ratings: 
  • Scopus rating (2018): CiteScore 1.96 SJR 0.491 SNIP 1.016
Original language: English
ASJC Scopus subject areas: Chemistry(all), Polymers and Plastics, Materials Chemistry
Source: Scopus
Source ID: 85017528518

Research output: Contribution to journalArticleScientificpeer-review

Modification of epoxy resin by silane-coupling agent to improve tensile properties of viscose fabric composites

The modification of epoxy resin by 3-aminopropyltriethoxysilane (APTES) to improve the tensile properties of warp knitted viscose fabric composites is reported in this study. The study evaluates the efficiency of modification methods adopted to modify the epoxy resin and the influence of the resin modification on various properties of the cured castings. The influence of matrix resin modification on the tensile properties of viscose fabric composite is compared to those prepared from chemically modified fibre. The efficiency of the modification was determined through titration method to determine the epoxide content of epoxy resin, viscosity measurement and FTIR. The effect of APTES modification on various properties of cured castings is studied through differential scanning calorimeter, contact angle measurement and tensile testing. The addition of APTES into the epoxy resin decreased the epoxide content in the resin as evident from the titration method. The tensile strength of cured castings decreased after the resin modification. The tensile strength and elongation at break of the viscose fabric composites prepared from modified resin, increased up to 14 and 41%, respectively. The improved adhesion of APTES-modified epoxy resin to the viscose fibre is confirmed from SEM analysis of tensile fracture surface.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Plastics and Elastomer Technology, Centria University of Applied Sciences, Royal Commission Yanbu Colleges and Institutes, Swerea IVF AB, Jozef Stefan Institute, Swedish Centre for Resource Recovery, University of Borås
Contributors: Rajan, R., Rainosalo, E., Thomas, S. P., Ramamoorthy, S. K., Zavašnik, J., Vuorinen, J., Skrifvars, M.
Number of pages: 29
Pages: 167–195
Publication date: 2018
Peer-reviewed: Yes

Publication information

Journal: Polymer Bulletin
Volume: 75
Issue number: 1
ISSN (Print): 0170-0839
Ratings: 
  • Scopus rating (2018): CiteScore 1.71 SJR 0.414 SNIP 0.718
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Polymers and Plastics, Materials Chemistry
Keywords: APTES, Composites, Epoxy, Modification, Regenerated cellulose, Silane coupling agent, Tensile, Viscose
Electronic versions: 
URLs: 

Bibliographical note

EXT="Skrifvars, Mikael"

Source: Scopus
Source ID: 85018515485

Research output: Contribution to journalArticleScientificpeer-review

Development of dust test method for motor drives

Motor drives are used in various industrial processes. Some of the operational environments of the drives may contain contaminations like dust, salts and gases. Dust combined with humidity may cause electrical shorts, decreased insulation resistance, and corrosion on the electronics of the device. Therefore, it is essential to study the behavior of the devices under such conditions. In this study, a product level dust test method for low voltage motor drives was developed. Method was successfully used to study the accumulation of the dust inside devices and the behavior of the devices under dusty and humid conditions.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Energy Engineering
Contributors: Pippola, J., Marttila, T., Frisk, L.
Number of pages: 4
Pages: 43-46
Publication date: 26 Jul 2017

Host publication information

Title of host publication: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017
Publisher: IEEE
ISBN (Electronic): 9781538630556
ASJC Scopus subject areas: Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials, Polymers and Plastics
Keywords: dust test, motor drive, reliability
Source: Scopus
Source ID: 85028615574

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Vegetable fillers for electric stimuli responsive elastomers

Dielectric elastomer actuators (DEAs) have been studied widely in recent years for artificial muscle applications, but their implementation into production is limited due to high operating voltages required. The actuation behavior of dielectric elastomer under an applied electric field is predicted by Maxwell's pressure and thickness strain equations. According to these equations, the best electromechanical response is achieved when the relative permittivity is high and elastic modulus is low. The potential source for additives increasing the relative permittivity of rubbers can be vegetable powders that have much higher dielectric constant than common elastomers. In the present research, the dielectric and actuation properties of polyacrylate rubber (ACM) were studied after the addition of different vegetable-based fillers such as potato starch, corn starch, garlic, and paprika. The results were compared to ACM filled with barium titanate. The compounds containing vegetable fillers showed higher relative dielectric permittivity at 1 Hz frequency than the compounds containing barium titanate due to higher interfacial polarization. The actuation studies showed that lower electric fields are required to generate certain actuation forces when the starches and garlic are used in the rubber instead of barium titanate. Therefore, the vegetable-based fillers can be used to improve actuation performance of DEAs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Plastics and Elastomer Technology, Department of Elastomers, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Poikelispää, M., Shakun, A., Sarlin, E., Das, A., Vuorinen, J.
Publication date: 20 Jul 2017
Peer-reviewed: Yes
Early online date: 2017

Publication information

Journal: Journal of Applied Polymer Science
Volume: 134
Issue number: 28
Article number: 45081
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2017): CiteScore 1.87 SJR 0.543 SNIP 0.773
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: biomaterials, dielectric properties, elastomers, mechanical properties, sensors and actuators

Bibliographical note

INT=mol,"Poikelispää, Minna"

Source: Scopus
Source ID: 85016434216

Research output: Contribution to journalArticleScientificpeer-review

Application Oriented Wear Testing of Wear Resistant Steels in Mining Industry

Demanding industrial wear problems cannot be properly simulated in the laboratory with standard methods using, for example, diamond indenters or fine quartz abrasives, as many standard or conventional wear testing methods do. The main reason is that most of the commonly available testing methods are based on low-stress wear conditions, while in mining high-stress wear conditions dominate. For this reason, several wear testers that can also utilize large sized abrasive particles to produce high-stress wear have been developed at Tampere Wear Center. In this work, one of such testers, a high speed slurry-pot, was developed with a possibility to conduct tests in both slurry and dry conditions. One of the main tasks of this thesis was to study how to set up the test method and the test device for simulating real mining related applications, and how the obtained results finally correlate with real-life material behavior in the applications. Another part of the work was to study and compare the wear mechanisms created by the low and high-stress testing methods, as well as the role of the microstructure and chemical composition of steels in the industrial wear processes.

In the comparison of the wear performance of steels and elastomers with each other, abrasive embedment was also observed to have a great influence on the comparison outcome, which needs to be taken into account when assessing the relative performance of these different types of materials in different wear conditions. For elastomers, especially, the effect of abrasive embedment is important in both low-stress and high-stress conditions, while steels show a particle size effect that limits the embedment in the low-stress conditions.

The wear resistance of steels in low-stress wear conditions does not essentially increase in the course of the process due to the lack of plastic deformation and, consequently, due to the lack of work hardening. On the other hand, in high-stress wear conditions work hardening can almost double the hardness of the wear surfaces, thus in general also increasing the material’s wear resistance. Yet, it is also shown that the hardness, neither the initial nor the hardened one, of the steel is not the only factor determining the material’s wear performance. Elastomers perform quite differently, i.e., they tolerate quite well the low-stress conditions but suffer from increasing wear when the stresses become higher. With the pot tester, the transition from the low-stress to the high-stress condition was observed to occur around the particle size of 1-2 mm.

To be able to simulate mining wear with a laboratory wear tester, proper material response during the test is crucial. To achieve that, the correct stress state in the wear process is required. For steels, the deformation, tribolayer formation and work hardening are important phenomena, which strongly influence the wear performance in high-stress wear conditions. In low-stress conditions, these phenomena are mostly absent or have a minimal effect at best. For the above reasons, good (if any) correlation between low-stress laboratory wear tests and high-stress industrial applications is not usually observed. On the other hand, with a wear tester that can sufficiently reproduce the wear environment of a mining application, good correlation between laboratory and field test s is possible to achieve.

General information

Publication status: Published
MoE publication type: G5 Doctoral dissertation (article)
Organisations: Materials Science, Research group: Materials Characterization
Contributors: Ojala, N.
Number of pages: 60
Publication date: 28 Apr 2017

Publication information

Publisher: Tampere University of Technology
ISBN (Print): 978-952-15-3936-7
ISBN (Electronic): 978-952-15-3941-1
Original language: English

Publication series

Name: Tampere University of Technology. Publication
Volume: 1469
ISSN (Print): 1459-2045
ASJC Scopus subject areas: Metals and Alloys, Polymers and Plastics, Mechanics of Materials, Industrial and Manufacturing Engineering
Electronic versions: 

Research output: Book/ReportDoctoral thesisCollection of Articles

High actuation performance offered by simple diene rubbers

Dielectric elastomers are materials well known for their superior actuation behavior under applied electric field. The simplicity of material fabrication and clear working principle of dielectric elastomer actuators (DEAs) can offer various applications of dielectric elastomers. In this work, we have compared a number of different types of commercially available elastomers in terms of actuation performance. It was found that well-known commercial rubbers like acrylonitrile-butadiene rubbers (NBR) can offer higher actuation performance in DEAs than the frequently used dielectric elastomers, such as acrylic rubber and silicone. The acrylonitrile content of the NBR was found to play an important role in the dielectric and consequently actuation properties. More interestingly, we observed that addition of organic oil, such as dioctyl adipate, can greatly enhance the actuation performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology
Contributors: Poikelispää, M., Shakun, A., Das, A., Vuorinen, J.
Number of pages: 7
Pages: 130-136
Publication date: Jan 2017
Peer-reviewed: Yes
Early online date: 2016

Publication information

Journal: Polymers for Advanced Technologies
Volume: 28
Issue number: 1
ISSN (Print): 1042-7147
Ratings: 
  • Scopus rating (2017): CiteScore 2.05 SJR 0.595 SNIP 0.758
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Actuator, Dielectric properties, Elastomers, High performance polymers, Nitrile rubber
Electronic versions: 
Source: Scopus
Source ID: 84978864233

Research output: Contribution to journalArticleScientificpeer-review

Aligned Poly(ε-caprolactone) Nanofibers Guide the Orientation and Migration of Human Pluripotent Stem Cell-Derived Neurons, Astrocytes, and Oligodendrocyte Precursor Cells In Vitro

Stem cell transplantations for spinal cord injury (SCI) have been studied extensively for the past decade in order to replace the damaged tissue with human pluripotent stem cell (hPSC)-derived neural cells. Transplanted cells may, however, benefit from supporting and guiding structures or scaffolds in order to remain viable and integrate into the host tissue. Biomaterials can be used as supporting scaffolds, as they mimic the characteristics of the natural cellular environment. In this study, hPSC-derived neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) are cultured on aligned poly(ε-caprolactone) nanofiber platforms, which guide cell orientation to resemble that of spinal cord in vivo. All cell types are shown to efficiently spread over the nanofiber platform and orient according to the fiber alignment. Human neurons and astrocytes require extracellular matrix molecule coating for the nanofibers, but OPCs grow on nanofibers without additional treatment. Furthermore, the nanofiber platform is combined with a 3D hydrogel scaffold with controlled thickness, and nanofiber-mediated orientation of hPSC-derived neurons is also demonstrated in a 3D environment. In this work, clinically relevant materials and substrates for nanofibers, fiber coatings, and hydrogel scaffolds are used and combined with cells suitable for developing functional cell grafts for SCI repair.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Materials Characterization
Contributors: Hyysalo, A., Ristola, M., Joki, T., Honkanen, M., Vippola, M., Narkilahti, S.
Publication date: 2017
Peer-reviewed: Yes
Early online date: 2017

Publication information

Journal: MACROMOLECULAR BIOSCIENCE
Volume: 17
Issue number: 7
Article number: 1600517
ISSN (Print): 1616-5187
Ratings: 
  • Scopus rating (2017): CiteScore 3.24 SJR 1.017 SNIP 0.776
Original language: English
ASJC Scopus subject areas: Biotechnology, Bioengineering, Biomaterials, Polymers and Plastics, Materials Chemistry
Keywords: 3D environment, Differentiated neural cell, Human pluripotent stem cell, Nanofiber, Orientation
Source: Scopus
Source ID: 85017192272

Research output: Contribution to journalArticleScientificpeer-review

Design-driven integrated development of technical and perceptual qualities in foam-formed cellulose fibre materials

Design-driven process entailing iterative prototyping was used to develop foam-formed monomaterial structure made of renewable and recyclable biomaterials suitable e.g. for sound insulation in interior spaces. Interactions between wood-pulp fibres, the perforated mould and the forming process opened opportunities for multi-scale material design, which re-defined the direction of the research. This finding entailed the simultaneous formation of macroscopic 3D forms, surface textures, and micro-porous material structures. These multi-scale properties affected the material’s technical and perceptual qualities. The dyed pulp together with the multi-scale forms provided interesting variations in visual quality. Moreover, the surface texture enhanced the material’s tactile properties and gave a higher quality feel and enhanced rigidity.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Plastics and Elastomer Technology, Aalto University, VTT Technical Research Centre of Finland
Contributors: Härkäsalmi, T., Lehmonen, J., Itälä, J., Peralta, C., Siljander, S., Ketoja, J. A.
Number of pages: 16
Pages: 5053–5068
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 24
Issue number: 11
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2017): CiteScore 4.12 SJR 1.047 SNIP 1.322
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Cellulose, Design-driven research, Fibre, Foam forming, Material-based design, Prototyping
Source: Scopus
Source ID: 85029010254

Research output: Contribution to journalArticleScientificpeer-review

Edge and particle embedment effects in low- and high-stress slurry erosion wear of steels and elastomers

Slurry transportation via pumping is an increasingly viable alternative for the conventional fine particle pumping, but there are also many applications involving larger particles. However, most of the published studies on slurry erosion have been conducted with fine particle sizes. In this work, also large particle slurry erosion of commercial wear resistant materials is studied. A high speed slurry-pot wear tester was used with edge protected samples to simulate the wear conditions in industrial slurry applications where edge wear is minimal. Two wear resistant steels together with natural rubber and polyurethane lining materials were tested, and the results were compared with the results of the same materials tested without sample edge protection. The tests were performed using 15 m/s speed, two sample angles, and slurry concentrations with particle size ranging from large 8/10 mm granite to fine 0.1/0.6 mm quartz. In all conditions, the steel samples showed stable wear behavior, whereas the elastomers gave notably inconsistent results in different test conditions. In general, steels exhibited better wear performance with large particles and elastomers with fine particles, and the wear losses were 40-95 % lower when edge wear was inhibited. With increasing abrasive size, the edge wear becomes more dominant and the particle embedment decreases.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Materials Science, Research group: Materials Characterization, SSAB
Contributors: Ojala, N., Valtonen, K., Minkkinen, J., Kuokkala, V.
Number of pages: 10
Pages: 126-135
Publication date: 2017
Peer-reviewed: Yes
Early online date: 15 Jun 2017

Publication information

Journal: Wear
Volume: 388-389
ISSN (Print): 0043-1648
Ratings: 
  • Scopus rating (2017): CiteScore 3.31 SJR 1.386 SNIP 2.199
Original language: English
ASJC Scopus subject areas: Metals and Alloys, Materials Science(all), Polymers and Plastics
Keywords: Wear testing, Steel, Elastomers, Edge effect, Particle embedment, Mining, Mineral processing
URLs: 
URLs: 

Research output: Contribution to journalArticleScientificpeer-review

Characterization of endoglucanase rich Trichoderma reesei cellulase mixtures and their effect on alkaline solubility of dissolving pulp

Dissolving grade pulps are used to manufacture regenerated cellulosic fibres. One promising process for the production of regenerated fibres utilises endoglucanse rich cellulases in the modification of dissolving pulp into alkaline soluble form. The aim of this paper was to characterise cellulases produced by Trichoderma reesei that are available in large quantities and study their effect on the dissolving grade softwood pulp, especially on its alkaline solubility. All the studied cellulases had endoglucanse activity and they decreased the intrinsic viscosity of the pulp. The degradation of cellulose into solubilised sugars increased with the cellulases containing also cellobiohydrolases. The monocomponent endoglucanases enhanced alkaline solubility of the pulp more than the multicomponent cellulases and produced alkaline solutions with higher fluidity. The studies showed that the type of the cellulases in the enzyme mixture has significant effect on the amount of solubilised sugars during the enzyme treatment and on the alkaline solubility of the pulp.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Biomass Processing Technologies, VTT Technical Research Centre of Finland, Lappeenranta University of Technology, Stora Enso
Contributors: Kamppuri, T., Vehviläinen, M., Backfolk, K., Heiskanen, I.
Number of pages: 11
Pages: 3901–3911
Publication date: Dec 2016
Peer-reviewed: Yes
Early online date: 30 Aug 2016

Publication information

Journal: Cellulose
Volume: 23
Issue number: 6
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2016): CiteScore 3.68 SJR 1.146 SNIP 1.196
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Alkaline solubility, Cellulase, Cellulose, Endoglucanase, Trichoderma reesei
Source: Scopus
Source ID: 84984846328

Research output: Contribution to journalArticleScientificpeer-review

Improvement of actuation performance of dielectric elastomers by barium titanate and carbon black fillers

Dielectric elastomers are promising materials for actuators resembling human muscle. Among elastomers, acrylic rubbers (ACM) have shown good actuation performance but its use is limited by the high operating voltages required. The present work demonstrates that simultaneous incorporation of nanostructured carbon black and dielectric fillers offers an increase in a dielectric permittivity and a suitable modulus of the elastomers matrix, enabling an improved electro-mechanical actuation performance at low voltages. By the use of reinforcing carbon black and barium titanate in an acrylic elastomer matrix a sixfold increase in the dielectric permittivity was realized. A fine tuning of the actuation stress and, consequently, actuation strain can be done by a judicial selection of the different filler concentrations in the soft rubber matrix. Finally, a synergistic effect of the fillers was observed in the improved actuation performance of the developed materials. This work may pave the way to design dielectric elastomers for actuator fabrication.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Poikelispää, M., Shakun, A., Das, A., Vuorinen, J.
Publication date: 10 Nov 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 133
Issue number: 42
Article number: 44116
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2016): CiteScore 1.73 SJR 0.588 SNIP 0.815
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: actuators, dielectric properties, elastomers
Source: Scopus
Source ID: 84982792344

Research output: Contribution to journalArticleScientificpeer-review

Application oriented wear testing of wear resistant steels in mining industry

Tampere Wear Center have developed several high-stress wear testers that utilize large sized abrasive particles of natural origin and thus are able to
simulate demanding applications of the mining industry. In this work, a versatile high speed slurry-pot wear tester was developed. Research questions
studied are: 1) How to set up a wear test method for simulating the real applications?, 2) What are the wear mechanisms in high-stress wear?, and
3) What is the role of microstructure and chemical composition on wear performance of wear resistant steels?

The high speed slurry-pot tester was developed for application oriented erosion wear testing of materials used in mineral handling and processing. It
enables tests in demanding high-stress abrasive and erosive environments simulating wear, for example, in slurry pumps, tanks and pipes, dredging,
mineral crushing and grinding, screening, loader buckets, and rock drilling. The key design features of the test method are the possibility to use up to
10 millimeter sized large abrasives and sample speeds up to 20 m/s in conditions ranging from wet slurry environments to dry sand or gravel.

The work has been done in FIMECC DEMAPP and DIMECC BSA projects, the focus is in the application oriented wear testing of materials intended for
demanding wear related applications.

General information

Publication status: Published
Organisations: Department of Materials Science, Research group: Materials Characterization
Contributors: Ojala, N.
Publication date: Nov 2016
Peer-reviewed: Unknown
Event: Paper presented at DIMECC 9th Annual Seminar, Helsinki, Finland.
ASJC Scopus subject areas: Mechanics of Materials, Metals and Alloys, Polymers and Plastics, Industrial and Manufacturing Engineering
Keywords: Wear testing, Application oriented, Steels, Polymer, Mining, mineral processing, Field test

Research output: Other conference contributionPaper, poster or abstractScientific

Atomistic molecular dynamics simulations on the interaction of TEMPO-oxidized cellulose nanofibrils in water

Atomistic molecular dynamics simulations were carried out to obtain information on the rheological, aggregation and disintegration properties of carboxylated (TEMPO-oxidized) cellulose nanofibrils with different functionalization levels. The magnitude of the inter-fibril interaction was quantified for parallel nanofibrils using the umbrella sampling method. The obtained potential of mean force was found highly sensitive to the charge configuration for intermediate functionalization levels. This feature was further studied with an electrostatic model for similar charge configurations and system periodicity as in the case of the molecular dynamics simulations. The electrostatic contribution of the charged surfaces varied from repulsive to attractive depending on the distribution of the carboxylate groups and nearby counter-ions, as well as the distance between the fibrils. The simulated deviations from average behavior for single fibrils in both models suggest heterogeneity in their aggregation and disintegration behavior. This was seen in disintegration experiments, where the differences in disintegration energy and in the structural variation qualitatively agreed with the model predictions. As to aggregation behavior, the studied case with parallel fibrils reflects the upper boundary of the repulsive interaction.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research area: Computational Physics, VTT Technical Research Centre of Finland, Aalto University
Contributors: Paajanen, A., Sonavane, Y., Ignasiak, D., Ketoja, J. A., Maloney, T., Paavilainen, S.
Number of pages: 14
Pages: 3449–3462
Publication date: 28 Sep 2016
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 23
Issue number: 6
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2016): CiteScore 3.68 SJR 1.146 SNIP 1.196
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Cellulose nanofibril, Electrostatic interaction, Functionalization, Molecular dynamics, TEMPO-oxidation

Bibliographical note

INT=fys,"Ignasiak, Dominika"

Source: Scopus
Source ID: 84988910143

Research output: Contribution to journalArticleScientificpeer-review

Designing of Elastomer Nanocomposites: From Theory to Application


General information

Publication status: Published
MoE publication type: C2 Edited books
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Leibniz-Institut für Polymerforschung Dresden E.V., Dt. Inst. für Kautschuktechnologie e.V.
Contributors: Stöckelhuber, K. W. (ed.), Das, A. (ed.), Klüppel, M. (ed.)
Publication date: 17 Aug 2016

Publication information

Publisher: Springer International Publishing
ISBN (Print): 9783319476957
ISBN (Electronic): 9783319476964
Original language: English

Publication series

Name: Advances in Polymer Science
Volume: 275
ISSN (Print): 0065-3195
ASJC Scopus subject areas: Chemical Engineering(all), Polymers and Plastics, Organic Chemistry
Keywords: Elastomers, Ionic crosslinking, Self healing rubber

Bibliographical note

JUFOID=50551

Research output: Book/ReportAnthologyScientificpeer-review

Nanostructured Ionomeric Elastomers

Driven by the desire to find an alternative way of vulcanizing elastomers without sulfur, researchers have widely explored ionic crosslinking techniques. The opportunity was taken to play with the functionality of the host polymer and its modification process to develop nanostructured ionic elastomers. Neutralization of polar elastomers by various divalent metal cations has been the route most employed for fabrication of this class of material. Ionic association or aggregation on the molecular level results in microphase separation of certain regions and, hence, enables easier processing. Thermally labile ionic domains introduced into the network make the entire material thermoresponsive and, therefore, it is possible to obtain reversible transition of dynamic mechanical properties. The unique network structure of these materials has led to outstanding physical properties that have not been achieved so far for conventional sulfidic networks. Consequently, many multifunctional and smart materials have been envisaged and designed using these systems. A detailed overview is provided on the various nanostructured ionic elastomers developed over the years. It would not be exaggerating to mention in the context of the discussion that nanostructured ionic elastomers will definitely open up new horizons in materials research.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Apollo Tyres Limited, Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Basu, D., Das, A., Stöckelhuber, K. W., Wießner, S.
Number of pages: 32
Pages: 235-266
Publication date: 17 Aug 2016

Host publication information

Title of host publication: Designing of Elastomer Nanocomposites: From Theory to Applications
Publisher: Springer International Publishing
Editors: Stöckelhuber, K. W., Das, A., Klüppel, M.
ISBN (Print): 9783319476957
ISBN (Electronic): 9783319476964

Publication series

Name: Advances in Polymer Science
Volume: 275
ISSN (Print): 0065-3195
ASJC Scopus subject areas: Chemical Engineering(all), Polymers and Plastics, Organic Chemistry
Keywords: Elastomers, Ionic crosslinking, Self healing rubber

Bibliographical note

JUFOID=50551

Source: Scopus
Source ID: 84994670333

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Detergent impurity effect on recycled HDPE: Properties after repetitive processing

High density polyethylene (rHDPE) is extruded 1 to 8 times, with and without detergent, to simulate the effects of impurities on the material and on the artificial ageing process. The mechanical properties, thermal stability, rheology, Fourier transform infrared spectroscopy (FTIR), and volatile organic compound (VOC) emissions are measured. According to the results, ageing of rHDPE increases tensile strength, reduces elongation, and enhances side chain branching of the material and thus causes rheological changes. The addition of detergent reduces changes in mechanical properties and rheological behavior but accelerates thermal degradation. VOC and FTIR measurements of the samples with detergent addition show generation of harmful 1,4-dioxane. The amount of total emission, as well as emissions of important perfumes limonene and 1R-α-pinene, decreases during multiple extrusion cycles. Heating of the plastics is found to be a major factor in the VOC emission reduction. Impurities have a notable effect on the artificial ageing results.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, University of Helsinki, Ekokem
Contributors: Mylläri, V., Hartikainen, S., Poliakova, V., Anderson, R., Jönkkäri, I., Pasanen, P., Andersson, M., Vuorinen, J.
Publication date: 15 Aug 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 133
Issue number: 31
Article number: 43766
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2016): CiteScore 1.73 SJR 0.588 SNIP 0.815
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: Ageing, Degradation, Polyolefins, Recycling
Source: Scopus
Source ID: 84992303578

Research output: Contribution to journalArticleScientificpeer-review

Reinforced chloroprene rubber by in situ generated silica particles: Evidence of bound rubber on the silica surface

Nano silica is generated in situ inside the uncrosslinked chloroprene rubber (CR) by the sol-gel reaction of tetraethoxysilane (TEOS). This results in appreciable improvement in mechanical properties of the CR composites at relatively low filler content. Furthermore, exploitation of reactive organosilanes, γ-aminopropyltrimethoxysilane (γ-APS) in particular, in the silica synthesis process facilitates growing of spherical silica particles with a size distribution in the range of 20-50 nm. The silica particles are found to be uniformly dispersed and they do not suffer from filler-filler interaction. Additionally, it is observed that the silica particles are coated by silane and rubber chains together which are popularly known as bound rubber. The existence of the bound rubber on silica surface has been supported by the detailed investigations with transmission electron microscopy (TEM), energy filtered transmission electron microscopy (EFTEM) and energy dispersive X-ray spectroscopy (EDAX). The interaction between rubber and silica, via bi-functionality of the γ-APS, has been explored by detailed FTIR studies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Visvesvaraya National Institute of Technology, Leibniz-Institut für Polymerforschung Dresden E.V., Institut für Werkstoffwissenschaft
Contributors: Kapgate, B. P., Das, C., Das, A., Basu, D., Wiessner, S., Reuter, U., Heinrich, G.
Publication date: 10 Aug 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 133
Issue number: 30
Article number: 43717
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2016): CiteScore 1.73 SJR 0.588 SNIP 0.815
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: bound rubber, in situ silica and silane treatment, transmission electron microscopy
Source: Scopus
Source ID: 84964925986

Research output: Contribution to journalArticleScientificpeer-review

The influence of high-temperature sulfuric acid solution ageing on the properties of laminated vinyl-ester joints

A carbon fiber powder doped corrosion layer is used as an inner layer in large composite tanks to improve their chemical and wear resistance. In joints fabricated on site, this layer is embedded into the structure. This study evaluates the lap shear strength of specimens, simulating a laminated joint in between the corrosion layer and the inner joint laminate. Lap-shear tests were carried out for as-fabricated and aged laminates at room temperature and at elevated temperature. Ageing was carried out for half a year in a 95 °C pressurized sulfuric acid solution. The tests showed that, after ageing, the room temperature shear strength remained unaltered but high-temperature shear strength was lowered. When the temperature increased, the failure location shifted from the interface between the doped layer and the joint laminate to the doped layer. Thermal analysis and microscopy were employed to clarify the reasons for the observed behavior.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Outotec Research Center, Aalto University
Contributors: Lindgren, M., Wallin, M., Kakkonen, M., Saarela, O., Vuorinen, J.
Number of pages: 7
Pages: 298-304
Publication date: 1 Jul 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of Adhesion and Adhesives
Volume: 68
ISSN (Print): 0143-7496
Ratings: 
  • Scopus rating (2016): CiteScore 2.47 SJR 0.919 SNIP 1.504
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Biomaterials, Polymers and Plastics
Keywords: Aging, Lap-shear, Sulfuric acid, Vinyl ester

Bibliographical note

EXT="Lindgren, M."

Source: Scopus
Source ID: 84973340146

Research output: Contribution to journalArticleScientificpeer-review

Structurally Controlled Dynamics in Azobenzene-Based Supramolecular Self-Assemblies in Solid State

Light-responsive supramolecular self-assemblies exhibit interplay between order and dynamics of the self-assembling motifs, through which the thermal isomerization rate of azobenzene chromophores can be tuned by orders of magnitude. By using supramolecular complexes of 4-(4-alkylphenylazo)phenols hydrogen-bonded to poly(4-vinylpyridine) as model systems, we demonstrate that the thermal isomerization rate of the hydroxyazobenzene derivatives increases 5700-fold when the material undergoes a transformation from a disordered, low-azobenzene-concentration state to a high-concentration state exhibiting lamellar, smectic-like self-assembly. Drastically smaller thermal isomerization rates are observed in disordered structures. This allows us to attribute the change to a combination of increased number density of the hydroxyazobenzenes inducing plasticization, and cooperativity created by the chromophore-chromophore interactions through self-assembled molecular order and alignment. Our results pinpoint the importance of molecular self-assembly and intermolecular interactions in modifying the dynamics in supramolecular complexes in a controlled manner. We foresee this to be important in light-controlled dynamic materials.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Aalto University
Contributors: Poutanen, M., Ikkala, O., Priimägi, A.
Number of pages: 7
Pages: 4095-4101
Publication date: 14 Jun 2016
Peer-reviewed: Yes

Publication information

Journal: Macromolecules
Volume: 49
Issue number: 11
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2016): CiteScore 5.76 SJR 2.564 SNIP 1.483
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source ID: 84975044511

Research output: Contribution to journalArticleScientificpeer-review

Edge effect in high speed slurry erosion wear tests of steels and elastomers

While the slurry transportation via pumping is an increasingly viable alternative for the conventional fine particle pumping, there are also many applications involving larger particles. However, the published studies on slurry erosion have mainly been conducted with fine particle sizes. In this work, both fine and large particle high speed slurry erosion of commercial wear resistant materials is studied.
The high speed slurry-pot wear tester was used with edge protected samples to simulate the wear conditions in industrial slurry applications, such as tanks and pipelines. Two quenched wear resistant steels together with natural rubber and polyurethane lining materials were tested, and the results were compared with the results of the same materials tested without sample edge protection. The tests were performed using 15 m/s speed, 45° and 90° sample angles, and 9 wt% and 33 wt% slurry concentrations with particle size ranging from large 8/10 mm granite to fine 0.1/0.6 mm quartz.
With or without edge protection, the steel samples showed stable wear behavior, whereas the elastomers gave notably inconsistent results in different test conditions. Steels exhibited better wear performance with large particles and elastomers with fine particles. In general, the wear losses were 40 – 95 % lower without edge wear, except for elastomers tested with fine quartz at the 45° sample angle, which yielded 25 – 75 % higher weight losses when the sample edges were protected. With increasing abrasive size, the edge wear becomes more dominant.

General information

Publication status: Published
MoE publication type: D3 Professional conference proceedings
Organisations: Materials Science, Research group: Materials Characterization, SSAB
Contributors: Ojala, N., Valtonen, K., Minkkinen, J., Kuokkala, V.
Number of pages: 13
Publication date: Jun 2016

Host publication information

Title of host publication: The 17th Nordic Symposium on Tribology - NORDTRIB 2016 14th - 17th June 2016 Aulanko, Hämeenlinna, Finland
ASJC Scopus subject areas: Metals and Alloys, Polymers and Plastics
Keywords: Slurry erosion, Wear testing, Steel, Elastomers, Edge effect

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

Magnetic cotton yarns: optimization of magnetic properties

In this paper, we present the effect of ferrite percentage content and electric current intensity passing through the electromagnet coil on magnetic properties (saturation induction, residual induction, and coercive field) of magnetic staple yarns. Also, we present a method for obtaining magnetic yarns by direct coating with magnetic powder (barium ferrite). The aim of the study is to determine the optimal processing factors that can affect the performance of magnetic characteristics using an experimental design for second-order model. The results show that an increase in ferrite percentage content is influencing the saturation and residual induction more than an increase in applied current intensity. The increase in saturation and residual induction is due to the higher content of ferrite powder from the magnetic solution that adheres on the yarn surface. The higher is the value of coercive field, the larger is the force needed to completely demagnetize the magnetic yarn.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, IT Center for Science and Technology, 25 Av. Radu Beller, Bucharest, Romania , National Institute for Textile and Leather, Universitatea Tehnica Gh. Asachi din IasI
Contributors: Grosu, M. C., Lupu, I. G., Cramariuc, O., Hristian, L.
Pages: 757-765
Publication date: 2016
Peer-reviewed: Yes
Early online date: 6 Jul 2015

Publication information

Journal: Journal of the Textile Institute
Volume: 107
Issue number: 6
ISSN (Print): 0040-5000
Ratings: 
  • Scopus rating (2016): CiteScore 0.98 SJR 0.454 SNIP 0.927
Original language: English
ASJC Scopus subject areas: Materials Science (miscellaneous), Polymers and Plastics, Industrial and Manufacturing Engineering, Agricultural and Biological Sciences(all)
Keywords: coercive field, experimental design, ferrite powder, magnetic staple cotton yarns, residual induction, saturation induction
Source: Scopus
Source ID: 84935512779

Research output: Contribution to journalArticleScientificpeer-review

Photoresponsive liquid-crystalline polymer films bilayered with an inverse opal structure

An inverse opal film was layered to a photodeformable film, and its photoresponsive behavior was investigated. This bilayer films composed of colorless photonic crystal using inverse opal structures and colored photoresponsive layers with azobenzene-containing CLCP.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Tokyo Institute of Technology, Japan Science and Technology Agency
Contributors: Akamatsu, N., Aizawa, M., Tatsumi, R., Hisano, K., Priimägi, A., Shishido, A.
Number of pages: 4
Pages: 145-148
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF PHOTOPOLYMER SCIENCE AND TECHNOLOGY
Volume: 29
Issue number: 1
ISSN (Print): 0914-9244
Ratings: 
  • Scopus rating (2016): CiteScore 0.88 SJR 0.3 SNIP 0.558
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: Bragg diffraction, Inverse opal structure, Photoresponsive film
Source: Scopus
Source ID: 84981200985

Research output: Contribution to journalArticleScientificpeer-review

Wear performance of quenched wear resistant steels in abrasive slurry erosion

Three commercially available quenched wear resistant steel grades were compared with a structural steel and four elastomer materials to reveal the differences in their behavior in slurry erosion conditions and to find the best solutions for demanding applications. A slurry-pot tester, allowing simulation of various wear conditions with different minerals, particle sizes (up to 10 mm), abrasive concentrations, and sample angles were used to simulate different industrial slurry applications. In this study, granite and quartz with concentrations of 9 and 33 wt% were used as abrasives in tests conducted at 45° and 90° sample angles. The performance of the studied steels was evaluated with respect to their material properties such as hardness and microstructure. Furthermore, the cross-sections and wear surfaces of the test samples were analyzed to reveal the possible differences in the mechanical behavior of the materials during slurry erosion. The wear surface analyses show that abrasion is the dominating wear mechanism already for the smallest particle size of 0.1/0.6 mm. In low-stress abrasive slurry erosion with the smallest particles, the elastomers showed better wear resistance than the steels, whereas in demanding high-stress abrasive slurry erosion conditions the quenched wear resistant steels can well compete with elastomers in wear resistance. The relative wear performance of the steels increased with increasing abrasive size, while for the elastomers it decreased.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Materials Characterization, SSAB
Contributors: Ojala, N., Valtonen, K., Antikainen, A., Kemppainen, A., Minkkinen, J., Oja, O., Kuokkala, V.
Number of pages: 11
Pages: 21-31
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Wear
Volume: 354-355
ISSN (Print): 0043-1648
Ratings: 
  • Scopus rating (2016): CiteScore 3 SJR 1.588 SNIP 2.105
Original language: English
ASJC Scopus subject areas: Metals and Alloys, Polymers and Plastics
Keywords: Slurry erosion, Wear testing, steel, elastomers, Mining, mineral processing, polymers
Electronic versions: 

Bibliographical note

INT=mol,”Antikainen, Atte"
EXT="Oja, Olli"

Research output: Contribution to journalArticleScientificpeer-review

Preparation and antimicrobial characterization of silver-containing packaging materials for meat

In food technology, antimicrobial packaging materials could inhibit or limit the growth of spoilage bacteria and thus improve the shelf life of packaged products. The present study provides new insights into the preparation and antimicrobial characterization of silver-containing packaging materials and their efficacy against typical meat spoilage bacteria. Antimicrobial efficacy of packaging films produced by coextrusion or liquid flame spray process was determined by bioluminescence imaging and conventional antimicrobial assay. Fresh pork sirloin was packaged in selected films and composition of meat microbiota was analyzed by 16S rRNA amplicon sequencing. Shelf life of meat was not affected by any of the silver-containing packaging films, even though meat microbiota mostly consisted of bacteria that were inhibited or retarded in vitro by nanoscale silver coating. This may be due to different release dynamics of silver ions on meat surfaces compared to the circumstances in the antimicrobial assay or interactions between silver and amino acids.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Paper Converting and Packaging, Department of Chemistry and Bioengineering, Engineering materials science and solutions (EMASS), Urban circular bioeconomy (UrCirBio), University of Helsinki, Department of Food Hygiene and Environmental Health
Contributors: Kuuliala, L., Pippuri, T., Hultman, J., Auvinen, S., Kolppo, K., Nieminen, T., Karp, M., Björkroth, J., Kuusipalo, J., Jääskeläinen, E.
Number of pages: 8
Pages: 53-60
Publication date: 1 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Food Packaging and Shelf Life
Volume: 6
Article number: 67
ISSN (Print): 2214-2894
Ratings: 
  • Scopus rating (2015): CiteScore 2.21 SJR 0.695 SNIP 0.947
Original language: English
ASJC Scopus subject areas: Food Science, Safety, Risk, Reliability and Quality, Biomaterials, Polymers and Plastics, Microbiology (medical)
Keywords: Active packaging, Antimicrobial film, Bioluminescence, Lactic acid bacteria, Liquid flame spray, Silver nanoparticle

Bibliographical note

ORG=mol,0.5
ORG=keb,0.5

Source: Scopus
Source ID: 84945244937

Research output: Contribution to journalArticleScientificpeer-review

Enhanced pre-treatment of cellulose pulp prior to dissolution into NaOH/ZnO

As a result of the constantly growing demand for textile fibres interest in utilising cellulose pulps for manufacturing regenerated cellulose fibres is growing. One promising water-based process for the manufacture of regenerated cellulosic products is the Biocelsol process based on an NaOH/ZnO solvent system. The drawback of the Biocelsol process is the need for pre-treatment of the pulp, i.e. long mechanical pre-treatment (up to 5 h) followed by a 2–3-h enzymatic hydrolysis utilising a rather high amount of cellulolytic enzymes. In this work more efficient conditions to carry out the pre-treatment of cellulose pulp prior to dissolution into NaOH/ZnO are presented. Based on the results, cellulase treatment, when carried out in an extruder, can be used to effectively open up and fibrillate the fibres without completely destroying the fibre structure. The molar mass of the pulp treated enzymatically in an extruder was 14 % lower as compared to the state-of-the-art-treated cellulose. As a consequence, the alkaline solutions prepared from the pulp treated enzymatically in an extruder had clearly lower dope viscosities regarding the cellulose content than the solutions prepared from the state-of-the-art-treated pulp. This enabled increasing the cellulose content in the dope up to 7 % (w/w) without increasing the dope viscosity.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Fibre Materials, Department of Forest Products Technology, VTT Technical Research Centre of Finland, Aalto University
Contributors: Grönqvist, S., Kamppuri, T., Maloney, T., Vehviläinen, M., Liitiä, T., Suurnäkki, A.
Number of pages: 10
Pages: 3981-3990
Publication date: Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 22
Issue number: 6
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2015): CiteScore 3.55 SJR 1.122 SNIP 1.202
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Biocelsol, Cellulose dissolution, Dissolving pulp, Enzymatic hydrolysis, Porosity, Pre-treatment, Solute exclusion
Source: Scopus
Source ID: 84946493808

Research output: Contribution to journalArticleScientificpeer-review

Effect of rubber polarity on selective wetting of carbon nanotubes in ternary blends

Based on atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) analysis of the rubber-filler gel (wetting concept) the kinetics of selective wetting of carbon nanotubes (CNTs) in ternary styrene butadiene rubber (SBR)/butadiene rubber (BR)/natural rubber (NR) blends was qualitatively and quantitatively characterized. Almost all CNTs are found to be wetted by the non-polar NR but not by the other non-polar rubber like BR or weakly polar SBR. It was proposed that phospholipids, which are linked to the α-terminal of NR can interact with the CNT surface through cation-π interactions forming strong bonding between NR and CNTs. Using the corrected surface tension value of NR, which involves the effect of phospholipids found in our previous work the selective wetting of CNTs in ternary rubber blends can be well predicted using the Z-model for a thermodynamic equilibrium state. By replacing the non-polar BR by a polar rubber like nitrile butadiene rubber (NBR) as a blend component CNTs are wetted by NBR slightly more than by NR thanks to the strong interaction between CNTs and nitrile groups of NBR. SBR remains unbound to CNTs in both blends.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Institut für Polymerwerkstoffe E.V., Martin-Luther-University Halle-Wittenberg, Fraunhofer IWM, Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V., Vietnamese Academy of Science and Technology Institute of Chemistry, Polymer Service GmbH Merseburg
Contributors: Le, H. H., Parsaker, M., Sriharish, M. N., Henning, S., Menzel, M., Wießner, S., Das, A., Do, Q. K., Heinrich, G., Radusch, H. J.
Number of pages: 12
Pages: 960-971
Publication date: 1 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Express Polymer Letters
Volume: 9
Issue number: 11
ISSN (Print): 1788-618X
Ratings: 
  • Scopus rating (2015): CiteScore 2.88 SJR 0.929 SNIP 1.553
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Physical and Theoretical Chemistry, Polymers and Plastics, Organic Chemistry, Materials Chemistry
Keywords: Carbon nanotubes, Manocomposites, Rubber blends, Selective filler wetting
Source: Scopus
Source ID: 84940868023

Research output: Contribution to journalArticleScientificpeer-review

Photomechanical Energy Transfer to Photopassive Polymers through Hydrogen and Halogen Bonds

The supramolecular assembly of photoactive azobenzenes with passive polymers via halogen or hydrogen bonding is a cost-effective way to design materials for various photomechanical applications that convert light energy directly into macroscopic motion, for instance, in all-optical surface patterning and photochemical imaging of plasmonic structures. To elucidate the molecular-level origins of this motion, we show, by coupling dynamic infrared spectroscopy to a photo-orientation setup, that supramolecular bonds above a certain interaction strength threshold are photostable under vigorous photoisomerization cycling and capable of translating the photo-orientation of azobenzenes into the orientation of nonabsorbing host polymer side chains. A correlation is found between azobenzene photoinduced molecular orientation and macroscopic all-optical surface patterning efficiency. The improved performance of halogen-bonded systems in photopatterning applications can be related to the absence of a plasticizing effect on the polymer matrix, which may enable the material to retain an optimal glass transition temperature, in contrast to hydrogen-bonded and nonbonded references. Thus, our results provide design guidelines in terms of the nature and strength of the supramolecular interaction and of the degree of azo functionalization needed to optimize the motion transfer to passive polymers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Frontier Photonics, Département de Chimie, Succ. Centre-Ville, Aalto University, Politecnico di Milano, Royal Military College of Canada
Contributors: Vapaavuori, J., Heikkinen, I. T. S., Dichiarante, V., Resnati, G., Metrangolo, P., Sabat, R. G., Bazuin, C. G., Priimagi, A., Pellerin, C.
Number of pages: 8
Pages: 7535-7542
Publication date: 27 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: Macromolecules
Volume: 48
Issue number: 20
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2015): CiteScore 5.82 SJR 2.357 SNIP 1.58
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry

Bibliographical note

EXT="Vapaavuori, Jaana"

Source: Scopus
Source ID: 84945400553

Research output: Contribution to journalArticleScientificpeer-review

In Situ Photocontrol of Block Copolymer Morphology during Dip-Coating of Thin Films

We demonstrate a unique combination of simultaneous top-down and bottom-up control of the morphology of block copolymer films by application of in situ optical irradiation during dip-coating. A light-addressable and block-selective small molecule, 4-butyl-4′-hydroxyazobenzene (BHAB), is introduced into a diblock copolymer of polystyrene and poly(4-vinylpyridine) (PS-P4VP) of 28.4 wt % P4VP via supramolecular chemistry, notably by hydrogen bonding to P4VP. We show that the spherical morphology of thin films dip-coated from a THF solution at slow withdrawal rates in the dark convert to cylindrical morphology when dip-coated under illumination. This is attributed to volume expansion of the P4VP/BHAB phase due to trans-cis photoisomerization combined with a light-induced increase in BHAB uptake in the film. The demonstrated photocontrol highlights the potential of dip-coating as a scalable film preparation method that can be easily coupled with external stimuli to direct nanostructured self-assembly in the films as solvent evaporates.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Département de Chimie, Succ. Centre-Ville
Contributors: Vapaavuori, J., Grosrenaud, J., Pellerin, C., Bazuin, C. G.
Number of pages: 5
Pages: 1158-1162
Publication date: 20 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 4
Issue number: 10
ISSN (Print): 2161-1653
Ratings: 
  • Scopus rating (2015): CiteScore 5.91 SJR 2.392 SNIP 1.403
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source ID: 84946032702

Research output: Contribution to journalArticleScientificpeer-review

Characterization of thermally aged polyetheretherketone fibres: Mechanical, thermal, rheological and chemical property changes

This paper investigates the effects of thermal degradation on polyetheretherketone (PEEK) fibres. PEEK samples were aged at a constant temperature of 250 °C for 1-128 days and characterized with mechanical tests, FTIR (Fourier Transform Infrared Spectroscopy), DSC (Differential Scanning Calorimetry), rheology, TGA (Thermogravimetric Analysis), SEM (Scanning Electron Microscopy), and UV-Vis diffuse reflectance spectroscopy. The short-term thermal annealing had a positive effect on the mechanical properties, due to the formation and growth of secondary crystals. Crosslinking in the material was verified by rheological inspections. The crosslinking increased the mechanical strength and modulus but reduced the elongation at break of the fibres. FTIR tests showed that carbonyl and hydroxyl groups were slowly formed on the surface of the fibres while ring opening reactions took place. The thermal ageing reduced the thermal stability of PEEK. The decreased stability was observed in the decomposition onset temperature after 8 d and in the melting point and the glass transition temperature after 32 d. The first signs of degradation, crosslinking, embrittlement, and reduced thermal stability, were visible roughly after 8 d of ageing, whereas the deterioration in general usability occurred after 64 d.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Engineering materials science and solutions (EMASS)
Contributors: Mylläri, V., Ruoko, T., Vuorinen, J., Lemmetyinen, H.
Number of pages: 8
Pages: 419-426
Publication date: 1 Oct 2015
Peer-reviewed: Yes
Early online date: 6 Aug 2015

Publication information

Journal: Polymer Degradation and Stability
Volume: 120
ISSN (Print): 0141-3910
Ratings: 
  • Scopus rating (2015): CiteScore 3.48 SJR 1.209 SNIP 1.61
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry, Mechanics of Materials, Condensed Matter Physics
Keywords: Fibre, PEEK, Thermal degradation

Bibliographical note

ORG=mol,0.75
ORG=keb,0.25
24 kk embargo (post-print)

Source: Scopus
Source ID: 84942433318

Research output: Contribution to journalArticleScientificpeer-review

Production of sulfonated polyetheretherketone/polypropylene fibers for photoactive textiles

New photocatalytic fibers made of sulfonated polyetheretherketone (SPEEK)/polypropylene (PP) are melt compounded and melt spun, first on laboratory scale and then on a semi-industrial scale. Fiber spinnability is optimized and the fibers are characterized using mechanical testing, electron paramagnetic resonance (EPR) spectroscopy, and scanning electron microscopy (SEM). According to the results, the fiber spinnability remains at a good level up to 10 wt % SPEEK concentration. Optimal processing temperature is 200C due to the thermal degradation at higher temperatures. EPR measurements show good and long-lasting photoactivity after the initial irradiation but also decay in the radical intensity during several irradiation cycles. Mechanical tenacity of the SPEEK/PP 5:95 fiber is approximately 20% lower than for otherwise similar PP fiber. The fiber is a potential alternative to compete against TiO2-based products but more research needs to be done to verify the real-life performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Department of Mechanical Engineering and Industrial Systems, Research area: Sustainable Machine Systems, University College of Borås, Högskolan i Borås, Next Technology Tecnotessile Società Nazionale di Ricerca S.r.l., Department of Biotechnology, Chemistry and Pharmacy, University of Siena
Contributors: Mylläri, V., Fatarella, E., Ruzzante, M., Pogni, R., Baratto, M. C., Skrifvars, M., Syrjälä, S., Järvelä, P.
Publication date: 1 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 39
Article number: 42595
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: blends, fibers, functionalization of polymers, photochemistry, textiles

Bibliographical note

ORG=mol,0.5
ORG=mei,0.5
EXT="Skrifvars, Mikael"

Source: Scopus
Source ID: 84937636904

Research output: Contribution to journalArticleScientificpeer-review

Formation and stability of carbon nanotube network in natural rubber: Effect of non-rubber components

Abstract The formation and stability of carbon nanotube (CNT) network in natural rubber (NR), deproteinized NR (DPNR) and polyisoprene (IR) compound were investigated by means of the method of the online measured electrical conductance in a whole process from processing and rolling over pressing/cross-linking to post-stretching. The kinetics of CNT flocculation was described and explained by taking into consideration the depletion force considered as driving force and the thickness of the bound rubber layer considered as hindering factor. The presence of linked phospholipids in NR and DPNR improves the rubber-filler interaction of CNTs through the cation-π bonding that hinders the filler flocculation. The absence of the cation-π bonding in CNT/IR compound and the related thin layer of bound rubber are the reason for the strong tendency of flocculation of CNTs in IR even at room temperature. The effect of pressing time, temperature and cross-linking reaction as well as mechanical deformation on the formation and stability of CNT network in NR compounds was also investigated and discussed by taking into consideration the role of the linked phospholipids.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), An-Institut der Hochschule Merseburg, Hochschule Albstadt-Sigmaringen, Fraunhofer IWM, Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V., University of Technology - National University, Vietnamese Academy of Science and Technology Institute of Chemistry, University of Applied Sciences Osnabrück, Polymer Service Merseburg
Contributors: Le, H. H., Pham, T., Henning, S., Klehm, J., Wießner, S., Stöckelhuber, K. W., Das, A., Hoang, X. T., Do, Q. K., Wu, M., Vennemann, N., Heinrich, G., Radusch, H. J.
Number of pages: 11
Pages: 111-121
Publication date: 5 Aug 2015
Peer-reviewed: Yes

Publication information

Journal: Polymer
Volume: 73
Article number: 18004
ISSN (Print): 0032-3861
Ratings: 
  • Scopus rating (2015): CiteScore 3.72 SJR 1.144 SNIP 1.257
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics
Keywords: Carbon nanotubes, Electrical conductivity, Filler network, Nanocomposites, Rubber
Source: Scopus
Source ID: 84938566176

Research output: Contribution to journalArticleScientificpeer-review

A comparison of rheology and FTIR in the study of polypropylene and polystyrene photodegradation

Rheology and FTIR spectroscopy are compared as methods to study the degree of photodegradation in polypropylene (PP) and polystyrene (PS) sheets. The materials are hot pressed, artificially photo-aged with fluorescent lights for 4-2048 h and then measured with a rotational rheometer and FTIR. Both materials show a tendency for chain scission which can be seen as a reduction in viscosity. Changes in PP can be observed with both methods after 256 h of irradiation. Changes in PS become significant in rheology after 64 h but in FTIR only after 1024 h of irradiation. Due to the different chemical nature of the materials, the degradation of PS is rather linear with exposure, whereas the degradation of PP is more exponential. Using the zero shear viscosities obtained through extrapolations of the Cole-Cole and Carreau-Yasuda models, relative molecular weights are estimated with the aid of the power-law relationship between these two. These results are compared with the carbonyl indices determined from the FTIR spectra. Rheology is found to be a viable alternative for FTIR in certain situations.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Plastics and Elastomer Technology, Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Research area: Sustainable Machine Systems, Department of Mechanical Engineering and Industrial Systems, Tampere Univ Technol, Tampere University of Technology, Dept Chem & Bioengn
Contributors: Mylläri, V., Ruoko, T., Syrjälä, S.
Number of pages: 6
Publication date: 1 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 28
Article number: 42246
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: aging, degradation, rheology, thermoplastics, PHOTOOXIDATION, FILMS, PHOTOLYSIS

Bibliographical note

ORG=mol,0.7
ORG=keb,0.2
ORG=mei,0.1

Source: Scopus
Source ID: 84928363110

Research output: Contribution to journalArticleScientificpeer-review

Equipment for obtaining polimeric nanofibres by electrospinning technology: II. The obtaining of polimeric nanofibers

The computerized technologies and equipment for obtaining nanofibers impose high training, a large interdisciplinary substantiation, capacity for data storage, memorizing, easy usage, selectivity, fiability, stability, reduced time for analizing/processing of the technological parameters. That is why the computerized electrospinning equipment and technologies for obtaining nanofibers are possible candidates to carry out these requirements owing to the fact that they present both the proper selectivity/sensibility and the increased processing/determining/intervening speed by using the computerized control. This paper aims to present the operation and aplication of equipment for obtaining polimeric nanofibers by electrospinning technology. The designing and accomplishing of the suggested electrospinning equipment has been aimed to obtain a modular system which should allow the control of the technological parameters by means of the computer. Thus, the multitude of the parameters which influence the process of electrospinning, can be independently and automatically varied. The obtained nanofibers were studied by scanning electron microscope.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Computational Science X (CompX), Gheorghe Asachi Technical University Iasi, Faculty of Textile and Leather Engineering and Industrial Management, Centre of Competence in Electrostatics and Electrotechnologies, Alexandru Ioan Cuza University of Iasi, ARHEOINVEST Interdisciplinary Platform, Romanian Inventors Forum, IT Center for Science and Technology, 25 Av. Radu Beller, Bucharest, Romania
Contributors: Manea, L. R., Cramariuc, B., Popescu, V., Cramariuc, R., Sandu, I., Cramariuc, O.
Number of pages: 6
Pages: 180-185
Publication date: 1 Jun 2015
Peer-reviewed: Yes

Publication information

Journal: Materiale Plastice
Volume: 52
Issue number: 2
ISSN (Print): 0025-5289
Ratings: 
  • Scopus rating (2015): CiteScore 0.82 SJR 0.28 SNIP 0.778
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Chemistry(all), Mechanics of Materials
Keywords: Electrospinning, Equipment, Modular conception, Nanofibers, Technology

Bibliographical note

EXT="Cramariuc, Bogdan"

Source: Scopus
Source ID: 84931827044

Research output: Contribution to journalArticleScientificpeer-review

Regeneration of fibres from alkaline solution containing enzyme-treated 3-allyloxy-2-hydroxypropyl substituted cellulose

The aim of this study was to regenerate fibres from the alkaline cellulose solution containing 3-allyloxy-2-hydroxypropyl substituents. Enzyme-treated cellulose was modified in alkaline aqueous tert-butanol (tBuOH) using allyl glycidyl ether (AGE) as the modification reagent. 3-allyloxy-2-hydroxypropyl substituted (AHP) enzyme-treated cellulose with DS<inf>A</inf> 0.05 was obtained. Enzyme-treated cellulose without (reference) and with substituents were dissolved in sodium zincate using the freezing-thawing cycle. The reference solution alone and the mixture solutions containing 10 or 25 % of the AHP cellulose were regenerated into cellulosic fibres using the wet spinning technique. The solutions containing 100 or 50 % of the AHP cellulose did not form fibres in acidic bath. The 10 % share of AHP cellulose did not affect the mechanical properties of the fibres (1.5 cN dtex<sup>−1</sup>), while the 25 % share decreased the tenacity slightly (1.3 cN dtex<sup>−1</sup>). Elongation of the fibres ranged from 18 to 22 %. The 10 and 25 % shares of AHP cellulose increased the water holding ability of fibres by 12 and 33 %, respectively. According to FESEM the fibre structures are composed of nanosized fibrils.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Fibre Materials, Research group: Materials Characterization, Engineering materials science and solutions (EMASS), VTT Technical Research Centre of Finland
Contributors: Vehviläinen, M., Kamppuri, T., Setälä, H., Grönqvist, S., Rissanen, M., Honkanen, M., Nousiainen, P.
Number of pages: 12
Pages: 2271-2282
Publication date: 10 May 2015
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 22
Issue number: 4
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2015): CiteScore 3.55 SJR 1.122 SNIP 1.202
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: 3-Allyloxy-2-hydroxypropyl cellulose, AHP cellulose, Biocelsol, Enzyme-treated cellulose, Fibril structure, Regenerated fibres, Wet spinning
Source: Scopus
Source ID: 84937975871

Research output: Contribution to journalArticleScientificpeer-review

Effect of rheological properties of dissolved cellulose/microfibrillated cellulose blend suspensions on film forming

Enzymatically treated cellulose was dissolved in a NaOH/ZnO solvent system and mixed together with microfibrillated cellulose (MFC) in order to find the threshold in which MFC fibers form a percolation network within the dissolved cellulose solution and in order to improve the properties of regenerated cellulose films. In the aqueous state, correlations between the rheological properties of dissolved cellulose/MFC blend suspensions and MFC fiber concentrations were investigated and rationalized. In addition, rheological properties of diluted MFC suspensions were characterized and a correlation with NaOH concentration was found, thus partly explaining the flow properties of dissolved cellulose/MFC blend suspensions. Finally, based on results from Dynamic Mechanical Analysis (DMA), MFC addition had strengthening/plasticizing effect on regenerated cellulose films if low concentrations of MFC, below the percolation threshold (5.5-6 wt%, corresponding to 0.16-0.18 wt% of MFC in the blend suspensions), were used.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Fibre Materials, PolymerTechnology, Department of Biotechnology and Chemical Technology, Aalto University
Contributors: Saarikoski, E., Rissanen, M., Seppälä, J.
Number of pages: 9
Pages: 62-70
Publication date: 30 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Carbohydrate Polymers
Volume: 119
ISSN (Print): 0144-8617
Ratings: 
  • Scopus rating (2015): CiteScore 4.86 SJR 1.44 SNIP 1.808
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics
Keywords: Blend, Dissolved cellulose, Microfibrillated cellulose, Rheology, Suspension
Source: Scopus
Source ID: 84916613635

Research output: Contribution to journalArticleScientificpeer-review

Exploring the role of stearic acid in modified zinc aluminum layered double hydroxides and their acrylonitrile butadiene rubber nanocomposites

The proposed study attempted to explore the role of stearic acid modification on the properties of zinc-aluminum based layered double hydroxides (LDH) and their composites with acrylonitrile butadiene rubber (NBR). Three distinctive LDH systems were adapted for such comparison; an unmodified LDH and two stearic acid modified LDH. The use of zinc oxide and stearic acid in the rubber formulation was avoided as the modified LDH would be able to deliver the necessary activators for the vulcanization process. Emphasis was predominantly given to reconnoiter the merits of stearic acid modification on the increase in interlayer distance of the LDH. X-ray diffraction studies and transmission electron microscope morphological investigations of LDH powders indicated that modification with stearic acid increased the interlayer spacing which would favor the intercalation of NBR polymer chains into the layered space. However, stress-strain studies indicated better mechanical properties for composites with unmodified LDH. Composites with LDH showed higher crosslinking densities than conventionally sulfur cured control compounds using zinc oxide/stearic acid as activators. This was evident from equilibrium swelling method as well as statistical theory of rubber elasticity.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V., Technische Universität Dresden, Rubber Technology Centre, Indian Institute of Technology Kharagpur
Contributors: Eshwaran, S. B., Basu, D., Vaikuntam, S. R., Kutlu, B., Wiessner, S., Das, A., Naskar, K., Heinrich, G.
Publication date: 1 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 9
Article number: 41539
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Chemistry(all), Surfaces, Coatings and Films, Polymers and Plastics, Materials Chemistry
Keywords: crosslinking, elastomers, mechanical properties, properties and characterization, rubber
Source: Scopus
Source ID: 84913616731

Research output: Contribution to journalArticleScientificpeer-review

Polymer looping is controlled by macromolecular crowding, spatial confinement, and chain stiffness

We study by extensive computer simulations the looping characteristics of linear polymers with varying persistence length inside a spherical cavity in the presence of macromolecular crowding. For stiff chains, the looping probability and looping time reveal wildly oscillating patterns as functions of the chain length. The effects of crowding differ dramatically for flexible versus stiff polymers. While for flexible chains the looping kinetics is slowed down by the crowders, for stiffer chains the kinetics turns out to be either decreased or facilitated, depending on the polymer length. For severe confinement, the looping kinetics may become strongly facilitated by crowding. Our findings are of broad impact for DNA looping in the crowded and compartmentalized interior of living biological cells.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Institute for Physics and Astronomy, University of Potsdam, Max-Planck Institute for the Physics of Complex Systems
Contributors: Shin, J., Cherstvy, A. G., Metzler, R.
Number of pages: 5
Pages: 202-206
Publication date: 17 Feb 2015
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 4
Issue number: 2
ISSN (Print): 2161-1653
Ratings: 
  • Scopus rating (2015): CiteScore 5.91 SJR 2.392 SNIP 1.403
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source ID: 84923204435

Research output: Contribution to journalArticleScientificpeer-review

Sulfonated polyetheretherketone/polypropylene polymer blends for the production of photoactive materials

Sulfonated polyetheretherketone (SPEEK) was synthesized via a mono-substitution reaction of PEEK in concentrated sulphuric acid and was blended with polypropylene (PP) in 2-10%w/w concentration to be used for the production of photoactive thermoplastic products. SPEEK and SPEEK/PP blends were characterized using FTIR, DSC, TGA, NMR, rheology, SEM, and EPR. Under UV-Vis irradiation, stable benzophenone ketyl (BPK) radicals were generated by hydrogen extraction from PP. By increasing the amount of SPEEK in the polymer blend a linear increase in the BPK radicals was achieved according to the EPR data. DSC and TGA tests indicated weaknesses in the thermal stability of SPEEK but according to the rheological tests this should not have a major effect on processabililty. The optimal amount of SPEEK in the blend was obtained at 5%w/w. This concentration provided a good compromise between radical concentration, material processability, and cost.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science
Contributors: Fatarelle, E., Mylläri, V., Ruzzante, M., Pogni, R., Baratto, M. C., Skrifvars, M., Syrjälä, S., Järvelä, P.
Publication date: 1 Feb 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 132
Issue number: 8
Article number: 41509
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2015): CiteScore 1.74 SJR 0.587 SNIP 0.846
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: Blends, Photochemistry, Polyolefins

Bibliographical note

Article first published online: 1 OCT 2014 ;(Volume 132, Issue 8, February 20, 2015)<br/>Contribution: organisation=mol,FACT1=1<br/>Portfolio EDEND: 2014-12-30<br/>Publisher name: JohnWiley & Sons, Inc.

Source: researchoutputwizard
Source ID: 296

Research output: Contribution to journalArticleScientificpeer-review

Ballistic and numerical simulation of impacting goods on conveyor belt rubber

Impact loading is an important process in the transport industry as it causes wear and failure of critical components. Conveyor belts are of particular importance as they are used in practically every industry where large quantities of goods are moved over short (<10 m) or long distances (>1 km). To investigate stress levels inside the material during impact loading, a gas gun was utilized to shoot 9 mm spherical steel balls onto the surface of a rubber conveyor belt. A high speed video recording system was employed in order to determine penetration depth and dissipated energy of the steel ball. Maximal penetration depths of up to 3.9 mm and maximal dissipated energies of up to 86.8 % were measured. Additionally, a numerical simulation using smooth particle applied mechanics was conducted and compared to the experimental results obtained with the gas gun. The calculated von Mises stresses affected the conveyor belts up to a maximum depth of 8.8 mm with at least 20 MPa. Maximum von Mises stresses were calculated to reach 60 MPa.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Materials Characterization, Computational Science X (CompX), Engineering materials science and solutions (EMASS), AC2T Research GmbH
Contributors: Molnar, W., Nugent, S., Lindroos, M., Apostol, M., Varga, M.
Number of pages: 7
Pages: 1-7
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Polymer Testing
Volume: 42
ISSN (Print): 0142-9418
Ratings: 
  • Scopus rating (2015): CiteScore 2.58 SJR 0.898 SNIP 1.622
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics
Keywords: Ballistic impact, Conveyor belt, Rubber, Simulation, Tribology
Source: Scopus
Source ID: 84920749567

Research output: Contribution to journalArticleScientificpeer-review

Block co-polymers for nanolithography: Rapid microwave annealing for pattern formation on substrates

The integration of block copolymer (BCP) self-assembled nanopattern formation as an alternative lithographic tool for nanoelectronic device fabrication faces a number of challenges such as defect densities, feature size, pattern transfer, etc. Key barriers are the nanopattern process times and pattern formation on current substrate stack layers such as hard masks (e.g., silicon nitride, Si3N4). We report a rapid microwave assisted solvothermal (in toluene environments) self-assembly and directed self-assembly of a polystyrene-blockpolydimethylsiloxane (PS-b-PDMS) BCP thin films on planar and topographically patterned Si3N4 substrates. Hexagonally arranged, cylindrical structures were obtained and good pattern ordering was achieved. Factors affecting BCP self-assembly, notably anneal time and temperature, were studied and seen to have significant effects. Graphoepitaxy within the topographical structures provided long range, translational alignment of the patterns. The effect of surface topography feature size and spacing was investigated. The solvothermal microwave based technique used to provide periodic order in the BCP patterns showed significant promise and ordering was achieved in much shorter periods than more conventional thermal and solvent annealing methods. The implications of the work in terms of manufacturing technologies are discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Trinity College Dublin, Materials Chemistry and Analysis Group, University College Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Tyndall National Institute at National University of Ireland, Cork
Contributors: Borah, D., Rasappa, S., Senthamaraikannan, R., Holmes, J. D., Morris, M. A.
Number of pages: 18
Pages: 592-609
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Polymers
Volume: 7
Issue number: 4
ISSN (Print): 2073-4360
Ratings: 
  • Scopus rating (2015): CiteScore 3.37 SJR 0.888 SNIP 1.325
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Chemistry(all)
Keywords: Block copolymer, Graphoepitaxy, Microwave anneal, Nanoscale patterns, Plasma etching, Polymer brush, Self-assembly, Silicon nitride substrate, Solvothermal process
Source: Scopus
Source ID: 84930638018

Research output: Contribution to journalArticleScientificpeer-review

Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites

Cellulose fibres have significant importance and potential for polymer reinforcement. It is essential to modify the surface of the fibre to obtain good fibre-matrix interface. Surface treatments can increase surface roughness of the fibre, change its chemical composition and introduce new moieties that can effectively interlock with the matrix, resulting in good mechanical properties in the composites. This is mainly due to improved fibre-matrix adhesion. The treatments may also reduce the water absorption rate by converting part of the hydroxyl groups on the fibre surface into other functional groups. Chemical modification of the surface of a regenerated cellulose fibre of the Lyocell type was carried out by alkali and silane treatments, which significantly changed the properties of the Lyocell fibres. Three parameters were considered when the fibre surface treatment was done: concentration (2–15 wt%), temperature (25 and 50 °C) and time (30 min–72 h). Fourier transform infrared spectroscopy and Raman spectroscopy were used for chemical analysis and qualitative analysis of the cellulose crystallinity due to the surface treatments; subsequently, mechanical strength of the fibres was tested by tensile testing. Weight loss, moisture regain and swelling measurements were taken before and after treatments, which showed the obvious changes in fibre properties on treatment. Heat capacity of the fibres was measured for untreated and treated fibres, and thermal degradation of fibres was examined to see the stability of fibres at elevated temperatures. Wettability and surface energies were measured using dynamic contact angle method in three wetting mediums. Scanning electron microscopy was used to study the morphological properties of the fibres.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Fibre Materials, University College of Borås, Högskolan i Borås, Swedish Centre for Resource Recovery
Contributors: Ramamoorthy, S. K., Skrifvars, M., Rissanen, M.
Number of pages: 18
Pages: 637-654
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 22
Issue number: 1
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2015): CiteScore 3.55 SJR 1.122 SNIP 1.202
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Alkali, Cellulose, Fibre, Lyocell, Silane, Surface modification

Bibliographical note

EXT="Skrifvars, Mikael"

Source: Scopus
Source ID: 84921943065

Research output: Contribution to journalArticleScientificpeer-review

How endoglucanase enzymes act on cellulose nanofibrils: role of amorphous regions revealed by atomistic simulations

Transformation of cellulose into monosaccharides can be achieved in a chemical process performed by a special group of enzymes known as cellulases. We have used atomistic molecular dynamics simulations to study endoglucanase II (Cel5A) that is one of the proteins in this group. Based on the atomistic simulation results, we discuss how the Cel5A enzyme interacts with cellulose fibrils comprised of both crystalline and amorphous regions. We show that the enzyme’s carbohydrate-binding domain prefers to interact with crystalline regions of cellulose, while the catalytic domain has a high affinity to the amorphous regions of fibrils. In particular, through electrostatic interactions the catalytic domain attracts loose glucose chains to its catalytic cleft. The atomistic details of the enzyme–cellulose interaction are presented and the implications for practical applications are briefly discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics, Research group: Biological Physics and Soft Matter, Computational Science X (CompX), Lappeenranta University of Technology, University of Jyväskylä, Stora Enso, Department of Physics and Nanoscience Center
Contributors: Orłowski, A., Róg, T., Paavilainen, S., Manna, M., Heiskanen, I., Backfolk, K., Timonen, J., Vattulainen, I.
Number of pages: 15
Pages: 2911-2925
Publication date: 2015
Peer-reviewed: Yes
Early online date: 17 Jul 2015

Publication information

Journal: Cellulose
Volume: 22
Issue number: 5
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2015): CiteScore 3.55 SJR 1.122 SNIP 1.202
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Cellulose, Enzyme, Molecular dynamics simulation

Bibliographical note

AUX=fys,"Orłowski, Adam"

Source: Scopus
Source ID: 84941415582

Research output: Contribution to journalArticleScientificpeer-review

The effect of the outermost fibre layers on solubility of dissolving grade pulp

Dissolving pulps are used to manufacture various cellulose derived products through cellulose dissolution. Solubility of cellulose pulp has been claimed to be strongly dependent on the porosity development, the degree of polymerisation and the pulp viscosity. The removal of external cell walls has been proposed to have a key role in the pulp solubility. In this paper, the effect of the outermost surface layers on the solubility of a dissolving grade pulp was studied. Furthermore the effect of mechanical peeling and combined mechanical and enzymatic treatment on pulp solubility was compared. Based on the results combined mechanical and enzymatic treatment efficiently opens up the fibre structure and has a clear positive effect on the solubility of dissolving pulp. It seems that long fibre fraction is less accessible to solvent chemicals than the other pulp fractions. Mechanical peeling of outer fibre layers does not improve fibre dissolution to NaOH/ZnO. Thus, it seems that peeling alone is not a sufficient pre-treatment prior to dissolution. The results also revealed that the peeling treatment does not enhance the effects of enzymes as the studied mechanical treatment does.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Materials Science, Research group: Fibre Materials, Department of Forest Products Technology, VTT Technical Research Centre of Finland, Latvian State Institute of Wood Chemistry, Aalto University
Contributors: Grönqvist, S., Treimanis, A., Kamppuri, T., Maloney, T., Skute, M., Grinfelds, U., Vehviläinen, M., Suurnäkki, A.
Number of pages: 11
Pages: 3955-3965
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Cellulose
Volume: 22
Issue number: 6
ISSN (Print): 0969-0239
Ratings: 
  • Scopus rating (2015): CiteScore 3.55 SJR 1.122 SNIP 1.202
Original language: English
ASJC Scopus subject areas: Polymers and Plastics
Keywords: Cellulose dissolution, Dissolving pulp, Enzymatic hydrolysis, Hydromechanical peeling, Porosity, Solute exclusion
Source: Scopus
Source ID: 84946490244

Research output: Contribution to journalArticleScientificpeer-review

Unmodified LDH as reinforcing filler for XNBR and the development of flame-retardant elastomer composites

Layered double hydroxides (LDHs), inorganic clay materials with mixed metals present in the structure along with some interlayer cations, have immense potential for use as a filler in rubbers.Wereport the preparation and properties of a set of novel nanocomposites consisting of aLDHdispersed in carboxylic-acrylonitrile-butadiene rubber (XNBR).Wesucceed in obtaining significantly improved physical properties by altering the chemical structure of a LDH with Zn and Al ions (Zn-Al LDH). In particular, we discover a significant reinforcing effect. This occurs despite the size difference between the LDH and traditional reinforcing fillers such as precipitated silica and carbon black. Both the elastic modulus and tensile strength increase. This increase is a function of the LDH concentration and, reaches a maximum value when the LDH concentration is at 100 phr. Experimental evidence suggests that this reinforcing effect is due to direct ion-to-ion interaction between the filler and the matrix. In addition, we report that the presence of the nanofiller positively affects the flame retardence and thermal decomposition of the nanocomposites. We attribute this effect to the presence of a layer formed by the nanofiller.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V., Technical University of Tampere, Rubber Research Institute of, IMDEA Materials Institute
Contributors: Basu, D., Das, A., Jacobgeorge, J., Wang, D. Y., Stöckelhuber, K., Wagenknecht, U., Leuteritz, A., Kutlu, B., Reuter, U., Heinrich, G.
Number of pages: 11
Pages: 606-616
Publication date: 1 Dec 2014
Peer-reviewed: Yes

Publication information

Journal: Rubber Chemistry and Technology
Volume: 87
Issue number: 4
ISSN (Print): 0035-9475
Ratings: 
  • Scopus rating (2014): CiteScore 0.98 SJR 0.577 SNIP 1.632
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry
Source: Scopus
Source ID: 84907840430

Research output: Contribution to journalArticleScientificpeer-review

Processable aromatic polyesters based on bisphenol derived from cashew nut shell liquid: synthesis and characterization

A new bisphenol viz., 4-(4-hydroxyphenoxy)-3-pentadecylphenol (HPPDP) was synthesized starting from cashew nut shell liquid (CNSL). Aromatic (co)polyesters containing ether linkages in the main chain and pendent pentadecyl chains were synthesized by the interfacial polycondensation of HPPDP with terephthalic acid chloride (TPC), isophthalic acid chloride (IPC) and a mixture of TPC and IPC (50:50 mol %) and by polycondenation of varying composition of HPPDP and bisphenol-A (BPA) with TPC. The resultant (co)polyesters exhibited inherent viscosities in the range 0.70–1.21 dL g−1 and number-average molecular weights in the range 16,000–48,200 (GPC, polystyrene standard). Polyesters were soluble in common organic solvents such as chloroform and dichloromethane and could be cast into films from chloroform solution. Polyesters exhibited T10 values in the range 430–455 °C and Tg values were in the range 29–202 °C. Dynamic mechanical storage modulus and maximum on transition of tan δ curve decreased with increased content of HPPDP in copolyesters. Importantly, the large difference between Tg and T10 values offers the possibility to process these polyesters in the melt.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: CSIR-National Chemical Laboratory, Polymer Science and Engineering Division
Contributors: Tawade, B. V., Salunke, J. K., Sane, P. S., Wadgaonkar, P. P.
Publication date: 18 Nov 2014
Peer-reviewed: Yes

Publication information

Journal: JOURNAL OF POLYMER RESEARCH
Volume: 21
Issue number: 12
ISSN (Print): 1022-9760
Ratings: 
  • Scopus rating (2014): CiteScore 1.84 SJR 0.666 SNIP 0.911
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Organic Chemistry
Keywords: Aromatic polyesters, Cashew nut shell liquid, Pentadecyl, Polycondensation, Processability, Thermal properties

Bibliographical note

EXT=”Salunke, Jagadish”

Source: Scopus
Source ID: 84911385848

Research output: Contribution to journalArticleScientificpeer-review

Electromagnetic interference shielding effectiveness of MWCNT filled poly(ether sulfone) and poly(ether imide) nanocomposites

Multiwalled carbon nanotube (MWCNT) filled poly(ether sulfone) (PES) and poly(ether imide) (PEI) composites were prepared with different MWCNT weight fractions (0.5-5wt%) by a solution mixing technique. Their electrical conductivities, electromagnetic interference (EMI), shielding effectiveness (SE), return loss (RL), and absorption loss (AL) were investigated. Morphologies of the fracture surfaces of nanocomposites studied by scanning electron and transmission electron microscopy showed relatively good MWCNT dispersion and distribution. The electrical conductivity of compression molded samples measured at room temperature indicated that the electrical percolation network was achieved already at 0.5% loading. The measurements of shielding effectiveness (SE) carried out in the frequency range of 8 to 12 GHz (X-band range) showed that SE increases with measurement frequency and with filler loading, whereby no significant differences could be observed between PES and PEI as matrices. The nanocomposites based on both matrices with 5 wt% loading of MWCNT exhibited shielding levels at 8 GHz between 42 and 45 dB in comparison with the pure polymers which showed value in the range of 1 to 2 dB. RL and AL showed significantly lower values for the composites as compared to unfilled polymers, but no systematic trends were observed on frequency.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Materials Science Centre, Indian Institute of Technology, Department of Applied Science, Symbiosis International University, Leibniz Institute of Polymer Research Dresden (IPF)
Contributors: Mohanty, A. K., Ghosh, A., Sawai, P., Pareek, K., Banerjee, S., Das, A., Pötschke, P., Heinrich, G., Voit, B.
Number of pages: 11
Pages: 2560-2570
Publication date: 1 Nov 2014
Peer-reviewed: Yes

Publication information

Journal: Polymer Engineering and Science
Volume: 54
Issue number: 11
ISSN (Print): 0032-3888
Ratings: 
  • Scopus rating (2014): CiteScore 1.4 SJR 0.556 SNIP 1.085
Original language: English
ASJC Scopus subject areas: Chemistry(all), Polymers and Plastics, Materials Chemistry
Source: Scopus
Source ID: 84907865840

Research output: Contribution to journalArticleScientificpeer-review

A supramolecular approach to photoresponsive thermo/solvoplastic block copolymer elastomers

With the aim of preparing supramolecular photoresponsive block copolymer elastomers, a series of ABA triblock copolymers with a poly(n-butyl acrylate) (PnBA) middle block and poly(dimethylaminoethyl methacrylate) (PDMAEMA or PDM) outer blocks were synthesized by atom transfer radical polymerization (ATRP), followed by PDM quaternization (giving PDMQ-PnBA-PDMQ) and then by ionic complexation with methyl orange (MO), an azo-containing and sulfonate-functionalized commercially available compound (giving PDMQ/MO-PnBA-PDMQ/MO). The PnBA block, which has a subambient glass transition, and the quaternized and complexed blocks, which have high glass transitions, form phase-separated soft and hard blocks, respectively. Simple elasticity tests of solvent-cast films show that the PDMQ/MO-PnBA-PDMQ/MO with hard block content between 18 and 29 wt % (as well as PDMQ-PnBA-PDMQ with 18 wt % hard block content) have significant elastomeric character. AFM and TEM (atomic force and transmission electron microscopies) of spin-coated films show a correlation between the elastomeric character and morphologies where the hard block forms a dispersed minority phase (spherical and/or short cylindrical domains). A continuous hard phase is observed for a hard block content of around 37 wt %; these materials show no significant elasticity. Reversible photoisomerization, with relatively high cis isomer content in the photostationary state, was also demonstrated.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Computer Systems, Frontier Photonics, Département de Chimie, Succ. Centre-Ville, Université de Sherbrooke
Contributors: Wang, X., Vapaavuori, J., Zhao, Y., Bazuin, C. G.
Number of pages: 10
Pages: 7099-7108
Publication date: 28 Oct 2014
Peer-reviewed: Yes

Publication information

Journal: Macromolecules
Volume: 47
Issue number: 20
ISSN (Print): 0024-9297
Ratings: 
  • Scopus rating (2014): CiteScore 5.83 SJR 2.524 SNIP 1.685
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source ID: 84908299127

Research output: Contribution to journalArticleScientificpeer-review

The role of linked phospholipids in the rubber-filler interaction in carbon nanotube (CNT) filled natural rubber (NR) composites

The aim of the present work is to evidence the role of the linked phospholipids of natural rubber (NR) in the rubber-carbon nanotube (CNT) interactions in rubber composites. Three rubbers namely NR, deproteinized NR (DPNR) and a synthetic rubber isoprene (IR) were used as matrix for CNTs. The selective wetting of CNTs in miscible NR/IR and DPNR/IR blends was investigated by means of the modified wetting concept based on Fourier transformed infrared (FTIR) analysis of the rubber-filler gel of blends. It revealed that the surface of CNTs is entirely wetted by NR or DPNR molecules, respectively, but not by IR. This result emphasizes that proteins do not influence the affinity between NR and CNTs, while the linked phospholipids interact with CNT surface through cation-π linkage. This linkage acts as anchor point supporting NR molecules to wet CNT surface effectively. The modified wetting concept can be used for characterization of selective wetting of different fillers in blends consisting of miscible rubber components.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Polymer Service GmbH Merseburg, Martin-Luther-University Halle-Wittenberg, Styron Deutschland GmbH, Fraunhofer IWM, Malaysian Rubber Board, Elastomer Technology and Engineering, University of Twente, Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems, Tribhuvan University, Borealis Polyolefine GmbH
Contributors: Le, H. H., Abhijeet, S., Ilisch, S., Klehm, J., Henning, S., Beiner, M., Sarkawi, S. S., Dierkes, W., Das, A., Fischer, D., Stöckelhuber, K. W., Wiessner, S., Khatiwada, S. P., Adhikari, R., Pham, T., Heinrich, G., Radusch, H. J.
Number of pages: 10
Pages: 4738-4747
Publication date: 2 Sep 2014
Peer-reviewed: Yes

Publication information

Journal: Polymer
Volume: 55
Issue number: 18
ISSN (Print): 0032-3861
Ratings: 
  • Scopus rating (2014): CiteScore 3.85 SJR 1.326 SNIP 1.602
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Polymers and Plastics
Keywords: Carbon nanotubes, Filler wetting, Non-rubber components
Source: Scopus
Source ID: 84906787813

Research output: Contribution to journalArticleScientificpeer-review

Effect of silane integrated sol-gel derived in situ silica on the properties of nitrile rubber

Nitrile rubber/silica composites are prepared by a sol-gel process using tetraethoxysilane as precursor in the presence of γ- mercaptopropyltrimethoxysilane as a silane coupling agent. Here, we follow a novel processing route where the silica particles are generated inside the rubber matrix before compounding with vulcanizing ingredients. The effect of in situ generated silanized silica on the properties of the rubber composite has been evaluated by studying curing characteristics, morphology, mechanical and dynamic mechanical properties. Enhanced rubber-filler interaction of these composites is revealed from stress-strain studies and dynamic mechanical analysis. Excessive use of silane shows an adverse effect on mechanical properties of the composites. Due to finer dispersed state of the in situ silica and enhanced rubber-filler interaction, the mechanical properties and thermal stability of the composites are improved compared to corresponding ex situ processed composite.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Visvesvaraya National Institute of Technology, Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Kapgate, B. P., Das, C., Basu, D., Das, A., Heinrich, G., Reuter, U.
Publication date: 5 Aug 2014
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 131
Issue number: 15
Article number: 40531
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2014): CiteScore 1.76 SJR 0.664 SNIP 0.98
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: elastomers, mechanical properties, morphology, rheology, structure-property relations
Source: Scopus
Source ID: 84900485659

Research output: Contribution to journalArticleScientificpeer-review

Carbon nanotubes-filled thermoplastic polyurethane-urea and carboxylated acrylonitrile butadiene rubber blend nanocomposites

This article reports the preparation and characterization of multiwalled carbon nanotubes (MWCNTs)-filled thermoplastic polyurethane-urea (TPUU) and carboxylated acrylonitrile butadiene rubber (XNBR) blend nanocomposites. The dispersion of the MWCNTs was carried out using a laboratory two roll mill. Three different loadings, that is, 1, 3, and 5 wt % of the MWCNTs were used. The electron microscopy image analysis proves that the MWCNTs are evenly dispersed along the shear flow direction. Through incorporation of the nanotubes in the blend, the tensile modulus was increased from 9.90 ± 0.5 to 45.30 ± 0.3 MPa, and the tensile strength at break was increased from 25.4 ± 2.5 to 33.0 ± 1.5 MPa. The wide angle X-ray scattering result showed that the TPUU:XNBR blends were arranged in layered structures. These structures are formed through chemical reactions of -NH group from urethane and urea with the carboxylic group on XNBR. Furthermore, even at a very low loading, the high degree of nanotubes dispersion results in a significant increase in the electrical percolation threshold. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40341.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), COMSATS Institute of Information Technology Lahore, Leibniz-Institut für Polymerforschung Dresden E.V., Institut für Polymerwerkstoffe, Vodafone Department of Mobile Communications Systems
Contributors: Mahmood, N., Khan, A. U., Stöckelhuber, K. W., Das, A., Jehnichen, D., Heinrich, G.
Publication date: 5 Jun 2014
Peer-reviewed: Yes

Publication information

Journal: Journal of Applied Polymer Science
Volume: 131
Issue number: 11
ISSN (Print): 0021-8995
Ratings: 
  • Scopus rating (2014): CiteScore 1.76 SJR 0.664 SNIP 0.98
Original language: English
ASJC Scopus subject areas: Materials Chemistry, Polymers and Plastics, Surfaces, Coatings and Films, Chemistry(all)
Keywords: blends, elastomers, graphene and fullerenes, nanotubes, polyurethanes, rubber
Source: Scopus
Source ID: 84897664169

Research output: Contribution to journalArticleScientificpeer-review

Azopolymer-based micro- and nanopatterning for photonic applications

Azopolymers comprise a unique materials platform, in which the photoisomerization reaction of azobenzene molecules can induce substantial material motions at molecular, mesoscopic, and even macroscopic length scales. In particular, amorphous azopolymer films can form stable surface relief patterns upon exposure to interfering light. This allows obtaining large-area periodic micro- and nanostructures in a remarkably simple way. Herein, recent progress in the development of azopolymer-based surface-patterning techniques for photonic applications is reviewed. Starting with a thin azopolymer layer, one can create a variety of photonic elements, such as diffraction gratings, microlens arrays, plasmonic sensors, antireflection coatings, and nanostructured light-polarization converters, either by using the azopolymer surface patterns themselves as optical elements or by utilizing them to microstructure or nanostructure other materials. Both of these domains are covered, with the aim of triggering further research in this fascinating field of science and technology that is far from being harnessed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 163-182 The aim of this review is to cover the existing research and trigger future research on the development of azopolymer-based micro- and nanopatterning techniques for applications in photonics. These techniques exploit a remarkably simple inscription of large-area surface relief gratings on azopolymer films. Starting with such an azopolymer pattern, one can create a variety of photonic elements, including diffraction gratings, distributed Bragg reflectors, microlens arrays, plasmonic sensors, antireflection coatings, and nanostructured converters of light polarization.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Aalto University
Contributors: Priimagi, A., Shevchenko, A.
Number of pages: 20
Pages: 163-182
Publication date: 1 Feb 2014
Peer-reviewed: Yes

Publication information

Journal: Journal of Polymer Science. Part B, Polymer Physics
Volume: 52
Issue number: 3
ISSN (Print): 0887-6266
Ratings: 
  • Scopus rating (2014): CiteScore 3.91 SJR 1.503 SNIP 1.412
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Physical and Theoretical Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: azo polymers, isomer/isomerization, lithography, nanotechnology, periodic arrays, photonics; surface-relief grating
Source: Scopus
Source ID: 84890653328

Research output: Contribution to journalArticleScientificpeer-review

Stearate Modified Zinc-Aluminum Layered Double Hydroxides and Acrylonitrile Butadiene Rubber Nanocomposites

The aim of this investigation is to highlight the potentials of layered double hydroxides (LDH) and to serve as a replacement for zinc oxide and stearic acid from the basic rubber formulation. This will eventually result in about a 10× significant reduction of Zn2+ ion concentration in the final compound. The unique advantage of stearate ion-modified LDH is the delivery of zinc ions to accelerate and stearate ions to activate the vulcanization process. Furthermore, it can also reinforce the rubber matrix by virtue of its layered structure as nanofiller.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V., Rubber Technology Centre, Indian Institute of Technology Kharagpur
Contributors: Eshwaran, S. B., Basu, D., Kutlu, B., Leuteritz, A., Wagenknecht, U., Stöckelhuber, K. W., Naskar, K., Das, A., Heinrich, G.
Number of pages: 9
Pages: 65-73
Publication date: Jan 2014
Peer-reviewed: Yes

Publication information

Journal: Polymer-Plastics Technology and Engineering
Volume: 53
Issue number: 1
ISSN (Print): 0360-2559
Ratings: 
  • Scopus rating (2014): CiteScore 2.52 SJR 0.664 SNIP 1.117
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Science (miscellaneous), Chemical Engineering(all), Materials Chemistry
Keywords: Layered double hydroxide, Nitrile rubber, Sulfur vulcanization, Zinc oxide
Source: Scopus
Source ID: 84891541802

Research output: Contribution to journalArticleScientificpeer-review

Effect of non-rubber components of NR on the carbon nanotube (CNT) localization in SBR/NR blends

Carbon nanotubes (CNTs) are mixed into SBR/NR and SBR/IR blends using a wet mixing process. The phase specific localization of CNTs in rubber blends is predicted theoretically using surface energy data of blend components and determined experimentally by means of the wetting concept. Almost all CNTs are found to be localized in the SBR matrix of SBR/IR blends due to the better affinity of CNTs to SBR than to IR. In contrast, a high CNT loading localized in the NR phase of SBR/NR blends results from the presence of phospholipids in NR. Electrical and mechanical properties of the rubber blends depend strongly on CNT localization. A lower CNT loading in SBR matrix of SBR/NR blends imparts a better wet grip and lower rolling resistance to tire tread compounds.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Martin-Luther-University Halle-Wittenberg, Styron Deutschland GmbH, Fraunhofer IWM, Leibniz-Institut für Polymerforschung Dresden E.V., Dau Mot University, Tribhuvan University, Vodafone Department of Mobile Communications Systems
Contributors: Le, H. H., Parsekar, M., Ilisch, S., Henning, S., Das, A., Stöckelhuber, K. W., Beiner, M., Ho, C. A., Adhikari, R., Wießner, S., Heinrich, G., Radusch, H. J.
Number of pages: 14
Pages: 569-582
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Macromolecular Materials and Engineering
Volume: 299
Issue number: 5
ISSN (Print): 1438-7492
Ratings: 
  • Scopus rating (2014): CiteScore 2.81 SJR 1.009 SNIP 1.294
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Chemical Engineering(all)
Keywords: carbon nanotubes, filler localization, nanocomposites, rubber blends
Source: Scopus
Source ID: 84899990693

Research output: Contribution to journalArticleScientificpeer-review

The effects of UV irradiation to polyetheretherketone fibres: Characterization by different techniques

The effects of UV irradiation on polyetheretherketone (PEEK) fibres were investigated in this study. PEEK fibres were manufactured with a melt spinning system and then artificially aged with simulated solar UV light. Fibres were then characterized by mechanical tests, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), rheology, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). PEEK, best known for its excellent thermal stability, suffered greatly from the effects of UV irradiation. The low UV stability manifested as embrittlement of the fibres in the mechanical tests, increased crosslinking rate in the rheological tests, formation of carbonyl and hydroxyl groups and changes in the nature of the carbon-hydrogen bonds in the FTIR, diminished thermal properties in TGA, and transverse cracks in the SEM photos. DSC was found to be an inaccurate technique for estimating the degradation level of PEEK fibres, whereas the carbonyl index measured by FTIR was found to be the most convenient technique. © 2014 Elsevier Ltd. All rights reserved.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Supramolecular photochemistry, Tampere University of Technology
Contributors: Mylläri, V., Ruoko, T. P., Järvelä, P.
Number of pages: 7
Pages: 278-284
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Polymer Degradation and Stability
Volume: 109
ISSN (Print): 0141-3910
Ratings: 
  • Scopus rating (2014): CiteScore 3.37 SJR 1.282 SNIP 1.879
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry, Mechanics of Materials, Condensed Matter Physics
Keywords: PEEK, Fibre, Ultraviolet, Rheology, POLY(ETHER ETHER KETONE), STRUCTURE/DEGRADABILITY RELATIONSHIPS, SCANNING CALORIMETRY, THERMAL-DEGRADATION, POLYPROPYLENE, PHOTODEGRADATION, POLYMERS, PHOTOOXIDATION, CRYSTALLINITY

Bibliographical note

Contribution: organisation=mol,FACT1=0.8<br/>Contribution: organisation=keb,FACT2=0.2<br/>Portfolio EDEND: 2014-09-10<br/>Publisher name: Elsevier Ltd

Source: researchoutputwizard
Source ID: 1117

Research output: Contribution to journalArticleScientificpeer-review

Location of dispersing agent in rubber nanocomposites during mixing process

In the present work, the development of morphology and selective wetting of nanoclay and carbon nanotubes (CNTs) in rubber nanocomposites were characterized qualitatively by means of the optical microscopy, TEM and AFM and quantitatively by means of the wetting concept. Carboxylated hydrogenated nitrile butadiene rubber (XHNBR), ionic liquid and ethanol were used as dispersing agent and they show very good effect on the macro- and microdispersion of nanofillers in different rubbers. It was found that the selective wetting of filler surface by the dispersing agent and rubber matrix is controlled by thermodynamic and kinetic factors. A model basing on surface energy data of polymer components (rubber and dispersing agent) and filler was introduced in order to determine the thermodynamic equilibrium state of filler wetting, which is found to be simultaneously determined by the filler-polymer affinity and the rubber/dispersing agent mass ratio. During the mixing process a replacement process of bound polymer components takes place on the filler surface until the predicted state is reached.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., University of Applied Sciences Merseburg, Martin-Luther-University Halle-Wittenberg, Vodafone Department of Mobile Communications Systems, Polymer Service Merseburg
Contributors: Le, H. H., Oßwald, K., Wießner, S., Das, A., Stöckelhuber, K. W., Boldt, R., Gupta, G., Heinrich, G., Radusch, H. J.
Number of pages: 13
Pages: 7009-7021
Publication date: 13 Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Polymer
Volume: 54
Issue number: 26
ISSN (Print): 0032-3861
Ratings: 
  • Scopus rating (2013): CiteScore 4.07 SJR 1.414 SNIP 1.635
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Organic Chemistry
Keywords: Carbon nanotubes, Dispersing agent, Localization
Source: Scopus
Source ID: 84889099442

Research output: Contribution to journalArticleScientificpeer-review

Effect of surface morphology of poly(ïμ-caprolactone) scaffolds on adipose stem cell adhesion and proliferation

Summary The effect of the surface morphology of flat poly(Ïμ- caprolactone) (PCL) scaffolds on human adipose stem cell (hASC) adherence and proliferation was studied. During fabrication of the scaffolds by phase inversion, the employment of different non-solvents (water (W), ethanol (EtOH) or isopropanol (IPA)) led to distinct surface morphologies. It was found that PCL scaffolds fabricated using IPA as a non-solvent had a higher roughness and porosity compared to the other groups. Moreover, during culturing of hASCs under static conditions, best cell attachment, spreading and growth were observed on the PCL scaffold. Our results show the potential of PCL scaffolds prepared using IPA as a non-solvent for especially soft tissue engineering applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), University of Twente, University of Groningen
Contributors: Diban, N., Haimi, S. P., Bolhuis-Versteeg, L., Teixeira, S., Miettinen, S., Poot, A. A., Grijpma, D. W., Stamatialis, D.
Number of pages: 7
Pages: 126-132
Publication date: Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Macromolecular symposia
Volume: 334
Issue number: 1
ISSN (Print): 1022-1360
Ratings: 
  • Scopus rating (2013): CiteScore 0.71 SJR 0.326 SNIP 0.388
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Condensed Matter Physics
Keywords: morphology, phase inversion, poly(Ïμ-caprolactone), roughness, scaffold porosity
Source: Scopus
Source ID: 84890745371

Research output: Contribution to journalArticleScientificpeer-review

Human adipose stem cells in chondrogenic differentiation medium without growth factors differentiate towards annulus fibrosus phenotype in vitro

Summary Intervertebral disc degeneration is the main cause of chronic back pain. Disc degeneration mainly leads to tearing of annulus fibrosus (AF), which is with current methods difficult to restore and impossible to regenerate. Stem cell technology offers a potential technique to repair the ruptured AF by enabling new matrix synthesis at the defect site. Previous studies have shown that human adipose stem cells (hASCs) are able to differentiate towards AF phenotype when treated with suitable growth factors. There are concerns about the use of growth factors in clinical applications because of their short half-lives, high costs and low effectiveness. The main aim of this research project was to regenerate AF tissue in vitro using hASCs and serum free chondrogenic medium without supplementation of growth factors. Differentiation of hASCs was induced by using the micromass culture technique. Human annulus fibrosus cell (hAFCs) cultured in commercial AF growth medium were used as positive control. Assessment of AF phenotype of hASCs and hAFCs was done at 14 and 21 days of culture. Quantification of sulphated glycosaminoglycan (GAG) content showed that hASCs cultured in chondrogenic medium expressed similar levels of sulphated GAGs as hAFCs. qRT-PCR confirmed the similarity of the differentiated hASCs with AF phenotype. Several markers for AF phenotype (aggrecan, collagen type I and glypican-3) were expressed in both hAFCs and differentiated hASCs. This is the first study that demonstrated that hASCs can be differentiated towards AF phenotype using serum free chondrogenic medium without growth factors. In a next step, scaffolds manufactured from biodegradable polymers will be used in combination with ASCs to find an optimal construct to repair AF defects.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), University of Twente, University of Groningen
Contributors: Gebraad, A. W. H., Miettinen, S., Grijpma, D. W., Haimi, S. P.
Number of pages: 8
Pages: 49-56
Publication date: Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Macromolecular symposia
Volume: 334
Issue number: 1
ISSN (Print): 1022-1360
Ratings: 
  • Scopus rating (2013): CiteScore 0.71 SJR 0.326 SNIP 0.388
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Condensed Matter Physics
Keywords: adipose stem cells, annulus fibrosus, intervertebral disc, tissue engineering
Source: Scopus
Source ID: 84890722713

Research output: Contribution to journalArticleScientificpeer-review

Proliferation and differentiation of adipose stem cells towards smooth muscle cells on poly(trimethylene carbonate) membranes

Summary Multipotent human adipose stem cells (hASCs) are an abundant and potential source of cells for vascular tissue engineering when combined with a suitable biomaterial scaffold. Poly(trimethylene carbonate) (PTMC) has been shown to be a useful biodegradable material for tissue engineered vascular grafts due to its flexibility, excellent biocompatibility and enzymatic degradation by surface erosion in vivo. The purpose of the current study was to evaluate the proliferation and differentiation of hASCs towards smooth muscle cells (SMCs) on gamma-crosslinked and photo-crosslinked PTMC membranes. PTMC macromers were functionalized with methacrylate end groups and crosslinked by UV initiated radical polymerization. High molecular weight linear PTMC was crosslinked by gamma irradiation. Cell viability, cell numbers and SMC differentiation of hASCs were evaluated on the differently crosslinked PTMC films at 7 and 14 days (d). On the photo-crosslinked membranes, homogenous monolayers of hASC were detected by live/dead assay. Consistently, cells on the photo-crosslinked membranes had significantly higher cell numbers compared to cells on the gamma-crosslinked membranes after 14 d of culture. SMC specific genes were expressed on both membranes at 14 d. Photo-crosslinked membranes showed higher expression of SMC specific proteins at 14 d compared to gamma-crosslinked membranes. These results suggest that especially the photo-crosslinked PTMC membranes are suitable for vascular tissue engineering applications when combined with hASCs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Aachen University of Applied Sciences, University of Groningen
Contributors: German, S. J., Behbahani, M., Miettinen, S., Grijpma, D. W., Haimi, S. P.
Number of pages: 10
Pages: 133-142
Publication date: Dec 2013
Peer-reviewed: Yes

Publication information

Journal: Macromolecular symposia
Volume: 334
Issue number: 1
ISSN (Print): 1022-1360
Ratings: 
  • Scopus rating (2013): CiteScore 0.71 SJR 0.326 SNIP 0.388
Original language: English
ASJC Scopus subject areas: Condensed Matter Physics, Polymers and Plastics, Organic Chemistry, Materials Chemistry
Keywords: adipose stem cell differentiation, poly (trimethylene carbonate), smooth muscle cells, tissue engineering
Source: Scopus
Source ID: 84890729494

Research output: Contribution to journalArticleScientificpeer-review

Soft-graphoepitaxy using nanoimprinted polyhedral oligomeric silsesquioxane substrates for the directed self-Assembly of PS-b-PDMS

We report here the fabrication of periodic sub-25 nm diameter size cylinder structures using block copolymer (BCP) directed self-Assembly on nanoimprinted topographically patterned substrates. Tailored polyhedral oligomeric silsesquioxanes (POSSs) films were spin coated onto silicon substrates and were patterned by nanoimprint lithography to produce topographies commensurable with the BCP domain spacing. The chemistry of the POSS was tuned to control the alignment and orientation of the BCP films. The substrates were used to direct the microphase separation (following toluene solvent annealing) of a hexagonal structure forming polystyrene-block-polydimethylsiloxane (PS-b-PDMS) having a domain spacing of 42.6 nm and PDMS cylinder widths of 23.7 nm. On more hydrophilic POSS substrates the cylinders were obtained parallel to the substrate plane and aligned with the topography. In contrast, in more hydrophobic POSS patterns, the cylinders align perpendicular to the substrate plane. The use of these methods for the nanofabrication of vias, nanofluidic devices or interconnect structures of sub-25 nm feature size is discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Chemistry and Bioengineering, Research group: Nanophotonics, Frontier Photonics, Trinity College Dublin, Edifici CM3, University College Cork, Tyndall National Institute at National University of Ireland, Cork, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Profactor GmbH, CNRS/UJF-Grenoble1/CEA LTM, Catalan Institute for Research and Advanced Studies (ICREA)
Contributors: Borah, D., Simao, C. D., Senthamaraikannan, R., Rasappa, S., Francone, A., Lorret, O., Salaun, M., Kosmala, B., Kehagias, N., Zelsmann, M., Sotomayor-Torres, C. M., Morris, M. A.
Number of pages: 10
Pages: 3512-3521
Publication date: Nov 2013
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 49
Issue number: 11
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2013): CiteScore 3.43 SJR 1.087 SNIP 1.66
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Physics and Astronomy(all), Organic Chemistry
Keywords: Block copolymer-Polyhedral oligomeric silsesquioxanes, Directed self-Assembly, Graphoepitaxy, Nanoimprint lithography, Surface chemistry
Source: Scopus
Source ID: 84885020807

Research output: Contribution to journalArticleScientificpeer-review

Residual stress development in cold sprayed Al, Cu and Ti coatings

Residual stresses play an important role in the formation and performance of thermal spray coatings. A curvature-based approach where the substrate-coating system deflection and temperature are monitored throughout the coating deposition process was used to determine residual stress formation during cold spray deposition of Al, Cu and Ti coatings. The effect of substrate material (carbon steel, stainless steel and aluminium) and substrate pre-treatment (normal grit blasting, grit blasting with the cold spray system and grinding for carbon steel substrate) were studied for all coating materials with optimized deposition parameters. Mainly compressive stresses were expected because of the nature of cold spraying, but also neutral as well as tensile stresses were formed for studied coatings. The magnitudes of the residual stresses were mainly dependent on the substrate/coating material combination, but the surface preparation was also found to have an effect on the final stress stage of the coating.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), VTT Technical Research Centre of Finland, Universitat Autonoma de Barcelona, Spain
Contributors: Suhonen, T., Varis, T., Dosta, S., Torrell, M., Guilemany, J. M.
Number of pages: 9
Pages: 6329-6337
Publication date: Oct 2013
Peer-reviewed: Yes

Publication information

Journal: Acta Materialia
Volume: 61
Issue number: 17
ISSN (Print): 1359-6454
Ratings: 
  • Scopus rating (2013): CiteScore 4.37 SJR 3.238 SNIP 2.654
Original language: English
ASJC Scopus subject areas: Ceramics and Composites, Metals and Alloys, Polymers and Plastics, Electronic, Optical and Magnetic Materials
Keywords: Aluminium, Cold spraying, Copper, Residual stresses, Titanium
Source: Scopus
Source ID: 84883740617

Research output: Contribution to journalArticleScientificpeer-review

Immobilized bioactive agents onto polyurethane surface with heparin and phosphorylcholine group

Heparin (HEP) and phosphorylcholine groups (PC) were grafted onto the polyurethane (PU) surface in order to improve biocompatibility and anticoagulant activity. After the surface grafting sites of PU were amplified with the primary amine groups of polyethylenimine (PEI), heparin was covalently linked onto the surface by the reaction between the amino group and the carboxyl group. PC groups were covalently immobilized on the PU-PEI surface through the reaction between the amino group and the aldehyde group of phosphorylcholine glyceraldehyde (PCGA). The surface density of primary amine groups was determined by a ninhydrin assay. The amino group density reached a maximum of 0.88 μmol/cm2 upon incorporation of 10 wt% PEI. The amount of heparin covalently immobilized on the PU-PEI surface was determined by the toluidine blue method. The grafting chemistry resulted in the comparatively dense immobilization of HEP (2.6 μg/cm2) and PC to the PU-PEI surfaces. The HEP and PC modified surfaces were characterized by water uptake (PU 0.15 mg/cm2, PU-PEI 3.54 mg/cm2, PU-HEP 2.04 mg/cm2, PU-PC 2.38 mg/cm2), water contact angle (PU 95.3, PU-PEI 34.0, PU-HEP 39.5, PU-PC 37.2), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscope (SEM). The results demonstrated that the PUPEI surface was successfully grafted with HEP and PC. The hydrophilicity and hemocompatibility of these grafted surfaces were significantly improved. These results suggested that the PU-HEP and PU-PC composite films are promising candidates for blood contacting tissue engineering.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Tianjin University, Shihezi University, School of Chemical Engineering and Technology, Tianjin Chest Hospital
Contributors: Tan, M., Feng, Y., Wang, H., Zhang, L., Khan, M., Guo, J., Chen, Q., Liu, J.
Number of pages: 9
Pages: 541-549
Publication date: May 2013
Peer-reviewed: Yes

Publication information

Journal: Macromolecular Research
Volume: 21
Issue number: 5
ISSN (Print): 1598-5032
Ratings: 
  • Scopus rating (2013): CiteScore 1.66 SJR 0.553 SNIP 0.769
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Chemical Engineering(all)
Keywords: hemocompatibility, heparin, phosphorylcholine group, polyethylenimine, polyurethane
Source: Scopus
Source ID: 84877763417

Research output: Contribution to journalArticleScientificpeer-review

The effect of test parameters on large particle slurryerosion testing

Understanding the effect of testing parameters is important for getting the test environment as close as possible to real applications and for understanding the processes that are involved in the testing itself. A pin mill type slurry-pot wear tester was developed for heavy-duty testing with high speed and large abrasive size [1]. This study focuses on the effect of different testing parameters on large particle slurry testing. Parameters such as rotation speed of the samples, particle size and slurry concentration were varied.
Round steel samples and slurry with water and granite gravel were used for testing. The test parameter variations were 4 to 10 mm for granite particle size, up to 23 wt% for slurry concentration and up to 20 m/s for sample tip speed. The relationship between the particle size, slurry concentration, and the amount of particles are discussed. Also the role of the kinetic energy of the abrasive particles is considered for large particle sizes.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Department of Materials Science, Research group: Materials Characterization, Metso Minerals, Inc.
Contributors: Ojala, N., Valtonen, K., Siitonen, P., Kuokkala, V.
Number of pages: 8
Publication date: 19 Mar 2013

Host publication information

Title of host publication: 3rd International Tribology Symposium of IFToMM
Place of publication: Luleå, Sweden

Publication series

Name: Tribology - Materials, Surfaces & Interfaces
Volume: 8
No.: 2
ISSN (Print): 1751-5831
ASJC Scopus subject areas: Metals and Alloys, Polymers and Plastics
Keywords: Slurry erosion, high speed slurry-pot, pin mill, particle size
Electronic versions: 

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Networking of ionic liquid modified CNTs in SSBR

Carbon nanotubes (CNTs) were modified using an ionic liquid (IL) and were admixed with a non-polar solution styrene butadiene rubber (SSBR). A local re-agglomeration of ionic liquid modified CNTs (m-CNTs) was found to occur in the SSBR composites, which was confirmed from transmission electron micrographs, as IL cannot couple CNTs and elastomer in order to maintain the disentangled state of the tubes. The conducting networks were established as a consequence of agglomerate-tube percolation and the maximum electrical conductivity of the investigated samples was found to be ∼0.01 S/cm. The reinforcing effect of m-CNTs was not profound in the composites due to the plasticizing nature of IL in non-polar SSBR.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Subramaniam, K., Das, A., Simon, F., Heinrich, G.
Number of pages: 8
Pages: 345-352
Publication date: Feb 2013
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 49
Issue number: 2
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2013): CiteScore 3.43 SJR 1.087 SNIP 1.66
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Organic Chemistry, Polymers and Plastics
Keywords: Carbon nanotubes, Electrical properties, Ionic liquids, Mechanical properties, Nanocomposites
Source: Scopus
Source ID: 84873192692

Research output: Contribution to journalArticleScientificpeer-review

Naturally occurring amino acids: A suitable substitute of N-N/-di-phenyl guanidine (DPG) in silica tyre formulation?

N-N/-di-phenyl guanidine (DPG) in combination with cyclohexyl benzothiazole sulfenamide (CBS) is widely used as an accelerator for the vulcanization of silica filled solution styrene butadiene rubber (S-SBR). The vulcanizates thus obtained exhibit excellent mechanical properties, good dynamic properties and also good aging resistance property. However, the use of DPG is a bit restricted of late being reported to be a potent carcinogenic compound and, hence, the effective substitution for DPG by safe alternative has been extensively explored. In this study, we systematically study the effects of naturally occurring amino acid L-cystine (L-cys) and its derivative L-cystine dimethyl ester dihydrochloride (ELCH) as environmental friendly co-accelerators for the vulcanization of silicafilled S-SBR.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Debnath, S. C., Das, A., Basu, D., Heinrich, G.
Number of pages: 7
Pages: 25-31
Publication date: Jan 2013
Peer-reviewed: Yes

Publication information

Journal: KGK: KAUTSCHUK GUMMI KUNSTSTOFFE
Volume: 66
Issue number: 1-2
ISSN (Print): 0948-3276
Ratings: 
  • Scopus rating (2013): CiteScore 0.29 SJR 0.207 SNIP 0.487
Original language: English
ASJC Scopus subject areas: Mechanical Engineering, Industrial and Manufacturing Engineering, Materials Chemistry, Polymers and Plastics
Keywords: L-cystine, N-N/-di-phenyl guanidine, Silica, Solution styrene butadiene rubber, Vulcanization
Source: Scopus
Source ID: 84874674495

Research output: Contribution to journalArticleScientificpeer-review

Elastomer composites based on carbon nanotubes and ionic liquid

Carbon nanotubes (CNTs) are known for excellent electrical conductivity and high elastic modulus. But difficulties arise in realizing their potential in matrices due to their existence in the form of aggregates or agglomerates. A simplified mixing technique using ionic liquid (IL) was developed to improve the dispersion of CNTs in elastomers. At first, CNTswere modified using an IL, 1-butyl-3-methyl-imidazolium-bis-(trifluoromethylsulfonyl)-imide in a mortar and pestle, and later, the modified tubes were incorporated into elastomers using a two-roll mill. The effect of modified tubes and IL on polar polychloroprene and nonpolar solution styrene butadiene rubber is studied. Enhanced dispersion and networking of CNTs can be achieved using this technique, based on which highly conducting composites were developed. Moreover, the composites with modified CNTs exhibited higher mechanical properties (tensile modulus, hardness) and thermal stability than the composites with unmodified CNTs. ILs are also found to have multifunctional roles (as antioxidants, as coupling agents) in the composites. The applications of composites with a particular focus on actuators and sensors are also discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Vodafone Department of Mobile Communications Systems, Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Subramaniam, K., Das, A., Stöckelhuber, K. W., Heinrich, G.
Number of pages: 34
Pages: 367-400
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Rubber Chemistry and Technology
Volume: 86
Issue number: 3
ISSN (Print): 0035-9475
Ratings: 
  • Scopus rating (2013): CiteScore 1.08 SJR 0.442 SNIP 1.266
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry
Source: Scopus
Source ID: 84904014953

Research output: Contribution to journalArticleScientificpeer-review

Azobenzene photomechanics: Prospects and potential applications

The change in shape inducible in some photo-reversible molecules using light can effect powerful changes to a variety of properties of a host material. This class of reversible light-switchable molecules includes molecules that photodimerize, such as coumarins and anthracenes; those that allow intra-molecular photo-induced bond formation, such as fulgides, spiro-pyrans, and diarylethenes; and those that exhibit photo-isomerization, such as stilbenes, crowded alkenes, and azobenzenes. The most ubiquitous natural molecule for reversible shape change, however, and perhaps the inspiration for all artificial bio-mimics, is the rhodopsin/retinal protein system that enables vision, and this is the quintessential reversible photo-switch for performance and robustness. Here, the small retinal molecule embedded in a cage of rhodopsin helices isomerizes from a cis geometry to a trans geometry around a C=C double bond with the absorption of just a single photon. The modest shape change of just a few angstroms is quickly amplified and sets off a cascade of larger shape and chemical changes, eventually culminating in an electrical signal to the brain of a vision event, the energy of the input photon amplified many thousands of times in the process. Complicated biochemical pathways then revert the trans isomer back to cis, and set the system back up for another cascade upon subsequent absorption. The reversibility is complete, and many subsequent cycles are possible. The reversion mechanism back to the initial cis state is complex and enzymatic, hence direct application of the retinal/rhodopsin photo-switch to engineering systems is difficult. Perhaps the best artificial mimic of this strong photo-switching effect however in terms of reversibility, speed, and simplicity of incorporation, is azobenzene. Trans and cis states can be switched in microseconds with low-power light, reversibility of 10 5 and 10 6 cycles is routine before chemical fatigue, and a wide variety of molecular architectures is available to the synthetic materials chemist, permitting facile anchoring and compatibility, as well as chemical and physical amplification of the simple geometric change. This review article focuses on photo-mechanical effect taking place in various material systems incorporating azobenzene. The photo-mechanical effect can be defined as reversible change in shape by absorption of light, which results in a significant macroscopic mechanical deformation, and reversible mechanical actuation, of the host material. Thus, we exclude simple thermal expansion effects, reversible but non-mechanical photo-switching or photo-chemistry, as well as the wide range of optical and electro-optical switching effects for which good reviews exist elsewhere. Azobenzene-based material systems are also of great interest for light energy harvesting applications across much of the solar spectrum, yet this emerging field is still in an early enough stage of research output as to not yet warrant review, but we hope that some of the ideas put forward here toward promising future directions of research, will help guide the field.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, McGill University, Brookhaven National Laboratory, Tokyo Institute of Technology, Aalto University
Contributors: Mahimwalla, Z., Yager, K. G., Mamiya, J. I., Shishido, A., Priimagi, A., Barrett, C. J.
Number of pages: 40
Pages: 967-1006
Publication date: Nov 2012
Peer-reviewed: Yes

Publication information

Journal: Polymer Bulletin
Volume: 69
Issue number: 8
ISSN (Print): 0170-0839
Ratings: 
  • Scopus rating (2012): CiteScore 1.49 SJR 0.559 SNIP 1.027
Original language: English
ASJC Scopus subject areas: Chemistry(all), Condensed Matter Physics, Polymers and Plastics, Materials Chemistry
Keywords: Azobenzene, Light harvesting, Liquid crystals, Photochemistry, Photomechanics, Thin films
Source: Scopus
Source ID: 84868637316

Research output: Contribution to journalArticleScientificpeer-review

Influence of ionic liquids on the dielectric relaxation behavior of CNT based elastomer nanocomposites

The influence of an imidazolium type ionic liquid (IL) on the relaxation behavior of carbon-nanotube (CNT) based polychloroprene nanocomposites prepared by melt mixing has been investigated by broadband dielectric spectroscopy. It is demonstrated that the presence of the ionic liquid modifies the relaxation behavior of the pure rubber matrix and leads to a significant increase of the conductivity for the CNT/rubber composites. For the unfilled rubber, a distinct glass transition of the IL is observed for high concentrations demonstrating that the IL forms a separate phase. The increased conductivity of the CNT-filled rubber composites is related to a physical coupling between CNTs and rubber matrix mediated by IL leading to a better dispersion of the CNTs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Deutsches Institut für Kautschuktechnologie e.V., Leibniz-Institut für Polymerforschung Dresden E.V., Technische Universität Dresden, Vodafone Department of Mobile Communications Systems
Contributors: Steinhauser, D., Subramaniam, K., Das, A., Heinrich, G., Klüppel, M.
Number of pages: 10
Pages: 927-936
Publication date: Nov 2012
Peer-reviewed: Yes

Publication information

Journal: Express Polymer Letters
Volume: 6
Issue number: 11
ISSN (Print): 1788-618X
Ratings: 
  • Scopus rating (2012): CiteScore 2.1 SJR 0.915 SNIP 1.597
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry, Chemical Engineering(all), Organic Chemistry, Physical and Theoretical Chemistry
Keywords: Dielectric spectroscopy, Ionic liquid, Nanocomposites, Relaxation dynamics, Rubber
Source: Scopus
Source ID: 84866131281

Research output: Contribution to journalArticleScientificpeer-review

Biomimetic surface modification of polycarbonateurethane film via phosphorylcholine-graft for resisting platelet adhesion

Phosphorylcholine groups were covalently introduced onto a polycarbonateurethane (PCU) surface in order to create a biomimetic structure on the polymer surfaces. After introducing primary amine groups onto the polymer surface by 1,6-hexanediamine, phosphorylcholine groups were covalently linked onto the surface by the reductive amination between the amino group and the aldehyde group of phosphorylcholine glyceraldehyde (PCGA). The results of water contact angle test, X-ray photoelectron spectroscopy (XPS), and X-ray fluorescence spectrometer (XRF) analysis of the modified films indicated that PCGA had already been covalently linked to the PCU surface. The topographies and surface roughnesses were both imaged and measured by atomic force microscopy (AFM). Scanning electron microscopy (SEM) observation of the PCU films after treatment with platelet-rich plasma demonstrated that platelets had rarely adhered to the surface of the PCGA-grafted PCU films but had mainly adhered to the surface of the blank PCU films. The platelet adhesion result indicated that the PC modified PCU films could resist platelet adhesion after grafting with PCGA, and that these PCGA-grafted PCU materials, potentially, might be applied as blood-contacting materials.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), Tianjin University, School of Chemical Engineering and Technology
Contributors: Gao, W., Feng, Y., Lu, J., Khan, M., Guo, J.
Number of pages: 7
Pages: 1063-1069
Publication date: Oct 2012
Peer-reviewed: Yes

Publication information

Journal: Macromolecular Research
Volume: 20
Issue number: 10
ISSN (Print): 1598-5032
Ratings: 
  • Scopus rating (2012): CiteScore 1.44 SJR 0.569 SNIP 0.801
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Chemical Engineering(all)
Keywords: Biomimetic, Phosphorylcholine glyceraldehydes, Platelet adhesion, Polycarbonateurethane, Surface modification
Source: Scopus
Source ID: 84867230066

Research output: Contribution to journalArticleScientificpeer-review

Highly conducting polychloroprene composites based on multi-walled carbon nanotubes and 1-butyl 3-methyl imidazolium bis(trifluoromethylsulphonyl)imide

Highly conducting flexible polychloroprene composites are prepared based on a novel mixing technique using ionic liquid (IL) modified multi-walled carbon nanotubes (MWCNTs). A conductivity of 0.1 S/cm is achieved for composites even at a low concentration of the tubes (5 phr). Extremely fine dispersion and a strong tube-tube networking of modified carbon nanotubes (M-CNTs), which are responsible for such high conductivity of the composites, are understood from transmission electron microscopy and amplitude sweep measurements. Several interesting applications can be visualised using these conducting composites: as a substrate for electronic circuits, and as an excellent construction material.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V.
Contributors: Subramaniam, K., Das, A., Heinrich, G.
Number of pages: 3
Pages: 44-46
Publication date: Jul 2012
Peer-reviewed: Yes

Publication information

Journal: KGK: KAUTSCHUK GUMMI KUNSTSTOFFE
Volume: 65
Issue number: 7-8
ISSN (Print): 0948-3276
Ratings: 
  • Scopus rating (2012): CiteScore 0.35 SJR 0.235 SNIP 0.559
Original language: English
ASJC Scopus subject areas: Mechanical Engineering, Polymers and Plastics, Industrial and Manufacturing Engineering, Materials Chemistry
Source: Scopus
Source ID: 84865498333

Research output: Contribution to journalArticleScientificpeer-review

Enhanced thermal stability of polychloroprene rubber composites with ionic liquid modified MWCNTs

Thermal degradation of polychloroprene rubber (CR) composites based on unmodified and ionic liquid modified multi-walled carbon nanotubes (MWCNTs) is studied using thermogravimetric analysis (TGA) in aerobic and anaerobic (nitrogen) conditions. The CR and its composites exhibit three stage and four stage degradation in nitrogen and air respectively. The presence of unmodified CNTs alone does not improve the thermal stability of composites to a great extent whereas a reasonable enhancement is observed in case of modified CNTs/CR composites which can be attributed to the interfacial interactions of ionic liquid/modified tubes with CR and to the fine dispersion of modified tubes in CR. The degradation products of CR and its composites were analysed using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and the mechanism of degradation is discussed. Non-isothermal degradation kinetics were studied using Kissinger and Flynn-Wall-Ozawa methods and the activation energy of thermal decomposition is found to be high for modified CNTs/CR composites. Isothermal degradation of modified CNTs/CR composites at 290°C for 30 min in nitrogen reveals decreased weight loss (14%) as opposed to CR (31%) and unmodified CNTs/CR composites (30%). The combustion behaviour of the composites was dealt using microscale combustion calorimeter (MCC) and the flame retardancy of the composites is discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Subramaniam, K., Das, A., Häußler, L., Harnisch, C., Stöckelhuber, K. W., Heinrich, G.
Number of pages: 10
Pages: 776-785
Publication date: May 2012
Peer-reviewed: Yes

Publication information

Journal: Polymer Degradation and Stability
Volume: 97
Issue number: 5
ISSN (Print): 0141-3910
Ratings: 
  • Scopus rating (2012): CiteScore 3.25 SJR 1.411 SNIP 2.079
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry, Mechanics of Materials, Condensed Matter Physics
Keywords: Carbon nanotubes, Elastomeric composites, Ionic liquids, Polychloroprene rubber, Thermal degradation, Thermal stability
Source: Scopus
Source ID: 84859216596

Research output: Contribution to journalArticleScientificpeer-review

Highly exfoliated natural rubber/Clay composites by "propping-open procedure": The influence of fatty-acid chain length on exfoliation

A high degree of exfoliation of MMT in NR is achieved by using the so-called "propping-open approach" in which a stepwise expansion of the interlayer spacing of MMT takes place. The nanostructure is characterized by WAXD and TEM which indicate different extents of clay dispersion depending on the fatty-acid chain length. Curing kinetics of different nanocomposites is studied and interestingly low activation energies of the vulcanization process are observed in the case of NR/EMMT nanocomposites. The incorporation of EMMT dramatically affects composite properties whereas DMA indicates significant reduction of tan δ peak height and the tensile strength approximately doubles from 14 to 30 MPa with only 5 phr EMMT.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Rooj, S., Das, A., Stöckelhuber, K. W., Reuter, U., Heinrich, G.
Number of pages: 15
Pages: 369-383
Publication date: Apr 2012
Peer-reviewed: Yes

Publication information

Journal: Macromolecular Materials and Engineering
Volume: 297
Issue number: 4
ISSN (Print): 1438-7492
Ratings: 
  • Scopus rating (2012): CiteScore 2.34 SJR 0.963 SNIP 1.187
Original language: English
ASJC Scopus subject areas: Chemical Engineering(all), Organic Chemistry, Polymers and Plastics, Materials Chemistry
Keywords: curing kinetics, exfoliation, Mooney-Rivlin equation, nanocomposites, propping-open approach
Source: Scopus
Source ID: 84859811037

Research output: Contribution to journalArticleScientificpeer-review

A novel thermotropic elastomer based on highly-filled LDH-SSB composites

Elastomeric composites are prepared based on solution styrene butadiene elastomer and zinc-aluminium layered double hydroxides (LDH), using a conventional sulphur cure system. Up to 100 parts per hundred rubber of LDH are incorporated into the elastomer matrix. The composites exhibit an interesting phenomenon of thermoreversible transparency, i.e. the transparent sample becomes opaque at warm condition and restores the transparency at room temperature. The transparency is found to be increased as the amount of LDH was increased. The addition of LDH gradually improved the mechanical, dynamic mechanical performance and thermal stability of the base elastomer. These developped elastomers could be utilised as smart materials in different applications

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Das, A., George, J. J., Kutlu, B., Leuteritz, A., Wang, D. Y., Rooj, S., Jurk, R., Rajeshbabu, R., Stöckelhuber, K. W., Galiatsatos, V., Heinrich, G.
Number of pages: 6
Pages: 337-342
Publication date: 27 Feb 2012
Peer-reviewed: Yes

Publication information

Journal: Macromolecular Rapid Communications
Volume: 33
Issue number: 4
ISSN (Print): 1022-1336
Ratings: 
  • Scopus rating (2012): CiteScore 4.7 SJR 2.096 SNIP 1.251
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics
Source: Scopus
Source ID: 84863149624

Research output: Contribution to journalArticleScientificpeer-review

Location of the Azobenzene moieties within the cross-linked liquid-crystalline polymers can dictate the direction of photoinduced bending

We present a simple way to control the photoinduced bending direction of azobenzene-containing cross-linked liquidcrystalline polymers. By changing the location of the photoactive azobenzene moieties from cross-links to side-chains, the bending direction of the sample is reversed under identical irradiation conditions. In addition to providing a versatile route toward directionality control of the photoinduced macroscopic motions, this observation highlights the complicated nature of the photomechanical response of azobenzene-containing cross-linked liquidcrystalline polymers, showing that the photomobile behavior can be determined by seemingly small details on the materials design.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Aalto University, Tokyo Institute of Technology, University of Hyogo, Kobe, Tohoku University, Chuo University
Contributors: Priimagi, A., Shimamura, A., Kondo, M., Hiraoka, T., Kubo, S., Mamiya, J. I., Kinoshita, M., Ikeda, T., Shishido, A.
Number of pages: 4
Pages: 96-99
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: ACS Macro Letters
Volume: 1
Issue number: 1
ISSN (Print): 2161-1653
Original language: English
ASJC Scopus subject areas: Organic Chemistry, Materials Chemistry, Polymers and Plastics, Inorganic Chemistry
Source: Scopus
Source ID: 84861898337

Research output: Contribution to journalArticleScientificpeer-review

Effect of ionic liquid on dielectric, mechanical and dynamic mechanical properties of multi-walled carbon nanotubes/polychloroprene rubber composites

This paper focuses on the influence of ionic liquid on carbon nanotube based elastomeric composites. Multi-walled carbon nanotubes (MWCNTs) are modified using an ionic liquid at room temperature, 1-butyl 3-methyl imidazolium bis (trifluoromethylsulphonyl) imide (BMI) and modified MWCNTs exhibit physical (cation-π/π-π) interaction with BMI. The polychloroprene rubber (CR) composites are prepared using unmodified and BMI modified MWCNTs. The presence of BMI not only increases the alternating current (AC) electrical conductivity and polarisability of the composites but also improves the state of dispersion of the tubes as observed from dielectric spectroscopy and transmission electron microscopy respectively. In addition to the hydrodynamic reinforcement, the formation of improved filler-filler networks is reflected in the dynamic storage modulus (E′) for modified MWCNTs/CR composites in amplitude sweep measurement upon increasing the proportion of BMI. Hardness and mechanical properties are also studied for the composites as a function of BMI.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Deutsches Institut für Kautschuktechnologie e.V., Vodafone Department of Mobile Communications Systems
Contributors: Subramaniam, K., Das, A., Steinhauser, D., Klüppel, M., Heinrich, G.
Number of pages: 10
Pages: 2234-2243
Publication date: Dec 2011
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 47
Issue number: 12
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2011): CiteScore 3.03 SJR 1.109 SNIP 1.822
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Physics and Astronomy(all), Organic Chemistry
Keywords: Carbon nanotubes, Electrical conductivity, Ionic liquids, Polychloroprene rubber
Source: Scopus
Source ID: 81155135001

Research output: Contribution to journalArticleScientificpeer-review

Tube-like natural halloysite/fluoroelastomer nanocomposites with simultaneous enhanced mechanical, dynamic mechanical and thermal properties

A novel kind of fluoroelastomer nanocomposites based on tube-like halloysite clay mineral were successfully prepared using a bis-phenol curing system, which resulted in prominent improvements in mechanical and dynamic mechanical properties and in the elevation as high as 30 K of the thermal decomposition temperature. Wide-angle X-ray scattering and transmission electron microscopy techniques were employed to assess the morphology developed in the nanocomposites, while stress strain diagrams were used to evaluate the mechanical properties. These nanocomposites were further characterized by moving die rheometer, dynamic mechanical properties and thermo-gravimetric analysis. Structure-properties relationship and the improvement of the mechanical, dynamic mechanical and thermal properties of fluoroelastomers are reported in the present study. Increasing amount of the filler reduced the curing efficiency of the bis-phenol curing system, which was evident from the rheometric and physical properties of the resulting composites. A sort of filler-filler interaction was perceived during the strain sweep analysis of the composites. The polymer-filler interaction was reflected in the improved mechanical and thermal properties which were the consequence of proper dispersion of the nanotubes in the polymer matrix; whereas the intercalation of macromolecular chains into the nanotubes was not reflected in the X-ray diffraction analysis.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Rooj, S., Das, A., Heinrich, G.
Number of pages: 10
Pages: 1746-1755
Publication date: Sep 2011
Peer-reviewed: Yes

Publication information

Journal: European Polymer Jounal
Volume: 47
Issue number: 9
ISSN (Print): 0014-3057
Ratings: 
  • Scopus rating (2011): CiteScore 3.03 SJR 1.109 SNIP 1.822
Original language: English
ASJC Scopus subject areas: Physics and Astronomy(all), Polymers and Plastics, Organic Chemistry
Keywords: Curing chemistry, Fluoroelastomers, Halloysite nanotube, Nanocomposites, Thermal stability
Source: Scopus
Source ID: 80052038140

Research output: Contribution to journalArticleScientificpeer-review

Hybrid nanoparticle design based on cationized gelatin and the polyanions dextran sulfate and chondroitin sulfate for ocular gene therapy

We describe the development of hybrid nanoparticles composed of cationized gelatin and the polyanions CS and DS for gene therapy in the ocular surface. The physicochemical properties of the nanoparticles that impact their bioperformance, such as average size and zeta potential, can be conveniently modulated by changing the ratio of polymers and the crosslinker. These systems associate plasmid DNA and are able to protect it from DNase I degradation. We corroborate that the introduction of CS or DS in the formulation decreases the in vitro toxicity of the nanoparticles to human corneal cells without compromising the transfection efficiency. These nanoparticles are potential candidates for the development of safer and more effective nanomedicines for ocular therapy. New hybrid nanoparticles composed of cationized gelatin and natural polyanions are developed and characterized. The incorporation of chondroitin sulfate or dextran sulfate in cationized gelatin nanoparticles decreases their toxicity while preserving their transfection efficiency in human corneal cells. These nanoparticles are potential candidates for the development of safer and more effective nanomedicines for ocular therapy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Integrated Technologies for Tissue Engineering Research (ITTE), University of Santiago de Compostela (USC)
Contributors: Zorzi, G. K., Párraga, J. E., Seijo, B., Sánchez, A.
Number of pages: 9
Pages: 905-913
Publication date: 7 Jul 2011
Peer-reviewed: Yes

Publication information

Journal: MACROMOLECULAR BIOSCIENCE
Volume: 11
Issue number: 7
ISSN (Print): 1616-5187
Ratings: 
  • Scopus rating (2011): CiteScore 3.69 SJR 1.408 SNIP 1.105
Original language: English
ASJC Scopus subject areas: Biotechnology, Bioengineering, Biomaterials, Polymers and Plastics, Materials Chemistry
Keywords: Drug delivery systems, Gelation, Nanoparticles, Nanotechnology
Source: Scopus
Source ID: 79959848036

Research output: Contribution to journalArticleScientificpeer-review

Comparison of the optical, thermal and structural properties of Ge-Sb-S thin films deposited using thermal evaporation and pulsed laser deposition techniques

Thin films of Ge 23Sb 7S 70 glass were prepared by thermal evaporation (TE) and pulsed laser deposition (PLD) techniques. We measured their thermal, optical and structural properties and compared with those of the parent bulk. The probe penetration temperature (T p) of the bulk glass, measured using a micro-thermal analyzer, was found to be 412 ± 10 °C, while those of the TE and PLD films were 468 and 470 ± 10 °C, respectively. The refractive index of the bulk and thin films was measured by ellipsometry and ultraviolet-visible-near infrared transmission spectroscopy, and we show that the films have similar refractive indices, which are lower than those of the parent bulk glass. Using micro-Raman spectroscopy, the structure of the film was investigated. The films contain homopolar Ge-Ge bonds and a lower number of homopolar S-S bonds compared to bulk material, which leads to an increase in the proportion of corner shared GeS 4/2 units in the films as compared to the bulk glass. Comparison of structural entities associated with each deposition process showed that the TE film possesses a lower number of S-S bonds and a slightly higher number of SbS 3/2 units compared to the PLD film. These structural changes lead to a more interconnected glass network, and therefore to a higher viscosity at elevated temperatures, as well as a higher refractive index, presumably through increased density. Post-deposition of annealing of these films causes their thermal and optical properties to revert to a more bulk-like state, suggesting that these property differences are due to a difference in the thermal histories of the bulk and film glass networks. For the first time to our knowledge, the refractive index of the bulk glass in the 0.6-10.6 μm range, measured using the prism coupling technique, is also presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Frontier Photonics, Clemson University, Massachusetts Institute of Technology, School of Materials Science and Engineering/COMSET
Contributors: Musgraves, J. D., Carlie, N., Hu, J., Petit, L., Agarwal, A., Kimerling, L. C., Richardson, K. A.
Number of pages: 8
Pages: 5032-5039
Publication date: Jul 2011
Peer-reviewed: Yes

Publication information

Journal: Acta Materialia
Volume: 59
Issue number: 12
ISSN (Print): 1359-6454
Ratings: 
  • Scopus rating (2011): CiteScore 4.27 SJR 3.215 SNIP 2.757
Original language: English
ASJC Scopus subject areas: Ceramics and Composites, Metals and Alloys, Polymers and Plastics, Electronic, Optical and Magnetic Materials
Keywords: Chalcogenide glass, Micro-thermal analysis, Pulsed laser deposition, Thermal evaporation, Thin films
Source: Scopus
Source ID: 79958132088

Research output: Contribution to journalArticleScientificpeer-review

Preintercalation of an organic accelerator into nanogalleries and preparation of ethylene propylene diene terpolymer rubber-clay nanocomposites

A multifunctional additive, bis(diisopropyl) thiophosphoryl diisopropyl disulfide (DIPDIS), was melted in the presence of quaternary ammonium-modified montmorillonite clay and incorporated into an ethylene propylene diene terpolymer (EPDM) rubber matrix as a nanofiller to prepare EPDM rubber nanocomposites. The finer dispersion of the organoclay (OC) in the rubber matrix was observed when the OC was preintercalated by DIPDIS using the propping-open procedure. X-ray diffraction (XRD) results showed that the silicate layers of the OC were successfully preintercalated by the DIPDIS; that is, the basal spacing of clay galleries was expanded from 2.98 to 3.76 nm. Because of the larger interlayer distance, as evidenced by XRD studies, the delamination process was facilitated through the easy intercalation of macromolecular rubber chains, which was reflected in various properties, such as the stress-strain behavior, thermal stability, dynamic mechanical properties and swelling properties. XRD studies and transmission electron microscopy directly supported the effective filler dispersion in the non-polar EPDM rubber matrix.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Engineering materials science and solutions (EMASS), Leibniz-Institut für Polymerforschung Dresden E.V., Vodafone Department of Mobile Communications Systems
Contributors: Rooj, S., Das, A., Heinrich, G.
Number of pages: 8
Pages: 285-292
Publication date: Mar 2011
Peer-reviewed: Yes

Publication information

Journal: POLYMER JOURNAL
Volume: 43
Issue number: 3
ISSN (Print): 0032-3896
Ratings: 
  • Scopus rating (2011): CiteScore 1.17 SJR 0.52 SNIP 0.598
Original language: English
ASJC Scopus subject areas: Polymers and Plastics, Materials Chemistry
Keywords: DIPDIS, montmorillonite, multifunctional additive, propping-open procedure
Source: Scopus
Source ID: 79952375182

Research output: Contribution to journalArticleScientificpeer-review