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- Hollman, P, et al.
(author)
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Tensile testing as a method for determining the Young's modulus of thin hard coatings
- 1997
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In: SURFACE & COATINGS TECHNOLOGY. - : ELSEVIER SCIENCE SA LAUSANNE. - 0257-8972. ; 90:3, s. 234-238
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Journal article (other academic/artistic)abstract
- The present paper describes and evaluates a tensile testing method for determination of the Young's modulus of thin hard coatings. When applied to PVD TiN and NbN coatings on stainless steel foils, the elastic modulus obtained through force-strain plots r
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- Hollman, P, et al.
(author)
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Tribological evaluation of thermally activated CVD diamond-like carbon (DLC) coatings
- 1997
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In: SURFACE & COATINGS TECHNOLOGY. - 0257-8972. ; 96:2-3, s. 230-235
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Journal article (other academic/artistic)abstract
- Diamond-lie carbon coatings have been the subject of expanding technological interest for wear resistance and low friction applications during recent years. In this study diamond-like carbon coatings were deposited by thermally activated chemical vapour
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- Kainulainen, Tuomo P., et al.
(author)
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Utilizing Furfural-Based Bifuran Diester as Monomer and Comonomer for High-Performance Bioplastics: Properties of Poly(butylene furanoate), Poly(butylene bifuranoate), and Their Copolyesters
- 2020
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 21, s. 743-752
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Journal article (peer-reviewed)abstract
- Two homopolyesters and a series of novel random copolyesters were synthesized from two bio-based diacid esters, dimethyl 2,5-furandicarboxylate, a well-known renewable monomer, and dimethyl 2,2′-bifuran-5,5′-dicarboxylate, a more uncommon diacid based on biochemical furfural. Compared to homopolyesters poly(butylene furanoate) (PBF) and poly(butylene bifuranoate) (PBBf), their random copolyesters differed dramatically in that their melting temperatures were either lowered significantly or they showed no crystallinity at all. However, the thermal stabilities of the homopolyesters and the copolyesters were comparable. Based on tensile tests from amorphous film specimens, it was concluded that the elastic moduli, tensile strengths, and elongation at break values for all copolyesters were similar as well, irrespective of the furan:bifuran molar ratio. Tensile moduli of approximately 2 GPa and tensile strengths up to 66 MPa were observed for amorphous film specimens prepared from the copolyesters. However, copolymerizing bifuran units into PBF allowed the glass transition temperature to be increased by increasing the amount of bifuran units. Besides enhancing the glass transition temperatures, the bifuran units also conferred the copolyesters with significant UV absorbance. This combined with the highly amorphous nature of the copolyesters allowed them to be melt-pressed into highly transparent films with very low ultraviolet light transmission. It was also found that furan–bifuran copolyesters could be as effective, or better, oxygen barrier materials as neat PBF or PBBf, which themselves were found superior to common barrier polyesters such as PET.
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- Waldemarson, AH, et al.
(author)
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Mycotoxins in laboratory rodent feed
- 2005
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In: Laboratory animals. - : SAGE Publications. - 0023-6772 .- 1758-1117. ; 39:2, s. 230-235
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Journal article (peer-reviewed)abstract
- Twenty-one batches of fixed-formula rodent diets from three feed manufacturers were tested for the presence of five mycotoxins: deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin, T-2 toxin and ochratoxin A (OTA). Five batches were also tested for the presence of zearalenone (ZEN) and six batches for aflatoxins. Detectable levels of DON (up to 298 μg/kg), NIV (up to 118 μg/kg), OTA (up to 3.1 μg/kg) or ZEN (up to 26.7 μg/kg) were found in samples from all manufacturers. Three batches contained two (DON or NIV and OTA or ZEN) and one batch contained three (DON, OTA and ZEN) different mycotoxins. Aflatoxins, T-2 and HT-2 were not detected in any of the batches. The concentrations of mycotoxins detected in the feed were low, but indicated that feed ingredients, probably the cereal ingredients, were contaminated by mycotoxins. Since mycotoxins are known to have toxic and/or immunosuppressive effects, non-contaminated ingredients should be used for production of laboratory animal feed. The results imply that an improved quality control of ingredients used for laboratory rodent feed should be implemented.
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- Andersson, Richard L., et al.
(author)
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Micromechanical Tensile Testing of Cellulose-Reinforced Electrospun Fibers Using a Template Transfer Method (TTM)
- 2012
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In: Journal of Polymers and the Environment. - : Springer Science and Business Media LLC. - 1566-2543 .- 1572-8919 .- 1572-8900. ; 20:4, s. 967-975
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Journal article (peer-reviewed)abstract
- A template transfer method (TTM) and a fiber fixation technique were established for fiber handling and micro tensile stage mounting of aligned and non-aligned electrospun fiber mats. The custom-made template had been precut to be mounted on a variety of collectors, including a rapidly rotating collector used to align the fibers. The method eliminated need for direct physical interaction with the fiber mats before or during the tensile testing since the fiber mats were never directly clamped or removed from the original substrate. By using the TTM it was possible to measure the tensile properties of aligned poly(methyl methacrylate) (PMMA) fiber mats, which showed a 250 % increase in strength and 450 % increase in modulus as compared to a non-aligned system. The method was further evaluated for aligned PMMA fibers reinforced with cellulose (4 wt%) prepared as enzymatically derived nanofibrillated cellulose (NFC). These fibers showed an additional increase of 30 % in both tensile strength and modulus, resulting in a toughness increase of 25 %. The fracture interfaces of the PMMA-NFC fibers showed a low amount of NFC pull-outs, indicating favorable phase compatibility. The presented fiber handling technique is universal and may be applied where conservative estimates of mechanical properties need to be assessed for very thin fibers.
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8. |
- Bayley, G. M., et al.
(author)
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Large strain and toughness enhancement of poly(dimethyl siloxane) composite films filled with electrospun polyacrylonitrile-graft-poly(dimethyl siloxane) fibres and multi-walled carbon nanotubes
- 2011
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In: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 52:18, s. 4061-4072
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Journal article (peer-reviewed)abstract
- Unfilled cross-linked poly(dimethyl siloxane) (PDMS) is a weak material and is generally filled with high levels of particulate fillers such as silica, calcium carbonate and carbon black to improve its mechanical properties. The use of fibrous fillers such as electrospun nanofibres and multi-walled carbon nanotubes as fillers for PDMS has not been widely studied. In this study anew copolymer, polyacrylonitrile-graft-poly(dimethyl siloxane) (PAN-g-PDMS), is used as fibrous filler for PDMS. The graft copolymer is electrospun to produce the fibre filler material. It is shown how the PDMS content of the graft copolymer provides increased compatibility with silicone matrices and excellent dispersion of the fibre fillers throughout a silicone matrix. It is also shown that it is possible to include multi-walled carbon nanotubes in the electrospun fibres which are subsequently dispersed in the PDMS matrix. Fibre mats were used in the non-woven and the aligned forms. The differently prepared fibre composites have significantly different mechanical properties. Conventional composites using fibrous fillers usually show increased strength and stiffness but usually with a resultant loss of strain. In the case of the composites produced in this study there is a dramatic improvement in the extensibility of the non-woven PAN-g-PDMS fibre mat filled silicone films of up to 470%.
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- Bjork, T, et al.
(author)
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Physical vapour deposition duplex coatings for aluminium extrusion dies
- 1999
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In: WEAR. - : ELSEVIER SCIENCE SA. - 0043-1648. ; 229:2, s. 1123-1130
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Journal article (other academic/artistic)abstract
- Duplex coatings [plasma nitriding followed by physical vapour deposition (PVD) coating] have been given a lot of interest as surface treatment for forming and cutting tools in recent years. The advantage, as compared to conventional PVD coating, is a high
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