| 1. |
- Terada, Nobuki, et al.
(författare)
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Bioartificial nerve grafts based on absorbable guiding filament structures--early observations
- 1997
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Informa UK Limited. - 1651-2073 .- 0284-4311. ; 31:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Gaps 10 mm wide in the sciatic nerves of 64 rats were bridged by bioartificial nerve grafts consisting of a silicone tube containing seven longitudinally placed filaments made of non-absorbable, (polyamide [Ethilon]) or absorbable, material (polydioxanone [PDS], polyglactin [Vicryl], and catgut). The purpose was to study the organisation of axonal growth inside the tube along such filaments. After two and four weeks histological techniques were used to study the contents of the tube and at four weeks immunohistological techniques were used to confirm the presence of axons distal to the tube. In all experimental groups axons had traversed the tube and reached the distal segment after four weeks. Inside the tube axons were organised in multiple minifascicles in all groups, but there were no axons growing in direct contact with the filaments. We conclude that resorbable filaments placed inside a silicone tube do not disturb axonal growth across the tube.
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| 2. |
- Mathew, Aji P., et al.
(författare)
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Transport of styrene monomer through natural rubber
- 1995
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861 .- 1873-2291. ; 36:26, s. 4935-4942
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Tidskriftsartikel (refereegranskat)abstract
- The diffusion and transport of inhibitor-free styrene through crosslinked natural rubber (NR) have been studied at various temperatures. NR has been vulcanized by conventional, efficient, peroxide and mixed vulcanization techniques. The dependence of diffusion coefficient on the crosslinking system has been studied for all the systems. The influence of temperature on the sorption and the activation energies of sorption have been calculated. The interaction parameter, permeability, sorption coefficient and molecular weight between crosslinks have been evaluated using the diffusion data. The effect of degree of crosslinking on the sorption characteristics of styrene through NR has also been investigated for the different crosslinking systems. The peroxide system showed lowest uptake and the conventional system showed highest uptake.
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| 3. |
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| 4. |
- Oksman, Kristiina
(författare)
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Improved interaction between wood and synthetic polymers in wood/polymer composites
- 1996
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Ingår i: Wood Science and Technology. - 0043-7719 .- 1432-5225. ; 30:3, s. 197-205
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the properties of wood polymer composites consisting of linear low density polyethylene (LLDPE) and wood flour (WF). In an attempt to improve the interfacial adhesion between the matrix and the filler, different compatibilizers were used. The interaction between polymer and wood were studied by comparing LLDPE/WF composites with composites when compatibilizer was added. The experimental measurements were conducted by impact and tensile strength testing and Scanning Electron Microscopy (SEM). The mechanical properties of the composites were improved with SEBS triblock copolymer modified with maleic anhydride and with the ionomer polymer, Surlyn, as compatibilizers. SEM fractography confirmed better adhesion between wood particles and LLDPE matrix when SEBS was present
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| 5. |
- Oksman, Kristiina
(författare)
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Improved properties of thermoplastic wood flour composites
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this study the properties of composites made of wood flour and thermoplastics have been investigated. In order to improve the interfacial adhesion between hydrophobic and nonpolar thermoplastics and hydrophilic and polar wood flour different additives have been used as compatibilizers in composites systems. The interaction between a wood filler and thermoplastic matrix, with and without compatibilizers, has been studied using conventional mechanical testing, impact testing, dynamic mechanical thermal analysis (DMTA), electron microscopes and infrared spectroscopy. Tests of mechanical properties, such as maximum tensile strength, tensile modulus and impact strength have shown that maleic anhydride grafted styrene-ethylene/butylene-styrene triblock copolymer (SEBS-MA) acts as a compatibilizer in the composite system. The SEBS-MA improves the stress transfer from the matrix to the wood particles and forming an flexible interphase around the wood particle and therefore improves the impact properties. The DMTA measurements indicated that there is an interaction between the wood surfaces and the maleic anhydride part of the SEBS-MA copolymer, and also between PS and wood. Morphological studies with SEM and TEM showed that the addition of SEBS-MA improved the adhesion between the wood particles and polymer matrix and that the compatibilizer is located at the interphase region between them. An infrared spectroscopy study indicated that the MA in the SEBS may react with the wood by forming hydrogen- and esterbonds and also possibly interaction between PS and wood.
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| 6. |
- Oksman, Kristiina, et al.
(författare)
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Influence of thermoplastic elastomers on adhesion in polyethylene-wood flour composites
- 1998
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Ingår i: Journal of Applied Polymer Science. - 0021-8995 .- 1097-4628. ; 68:11, s. 1845-1855
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical properties of recycled low-density polyethylene/wood flour (LDPE/WF) composites are improved when a maleated triblock copolymer styrene-ethylene/butylene-styrene (SEBS-MA) is added as a compatibilizer. The composites' tensile strength reached a maximum level with 4 wt % SEBS-MA content. The compatibilizer had a positive effect on the impact strength and elongation at break but decreased the composites' stiffness. Dynamic mechanical thermal analysis (DMTA), a lap shear adhesion test, and a scanning electron microscope (SEM) were used to investigate the nature of the interfacial adhesion between the WF/SEBS and between the WF/ SEBS-MA. Tan δ peak temperatures for the various combinations showed interaction between the ethylene/butylene (EB) part of the copolymer and the wood flour in the maleated system. The shear lap test showed that adhesion between the wood and SEBS-MA is better than between the wood and SEBS. The electron microscopy study of the fracture surfaces confirmed good adhesion between the wood particles and the LDPE/SEBS-MA matrix. © 1998 John Wiley & Sons, Inc.
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| 7. |
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| 8. |
- Oksman, Kristiina, et al.
(författare)
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Interaction between wood and synthetic polymers
- 1995
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Ingår i: Holzforschung. - : Walter de Gruyter GmbH. - 0018-3830 .- 1437-434X. ; 49:3, s. 249-254
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Tidskriftsartikel (refereegranskat)abstract
- The properties of wood composites consisting of low density polyethylene (LDPE) and wood flour (WF) were studied. In an attempt to improve the interfacial adhesion between hydrophobic LDPE matrix and the hydrophilic WF filler, a styrene-butadiene-styrene (SBS) copolymer was added as a compatibilizer. The interaction between LDPE and wood was investigated for PE/WF- and PE/WF/SBS-composites. The experimental measurements were conducted by conventional mechanical testing and Scanning Electron Microscopy (SEM). The interaction between polystyrene and wood in PS/WF composites was also studied by SEM and by Dynamic Mechanical Thermal Analysis (DMTA). PE/WF/SBS composites showed higher maximum tensile stress and strain at failure than the composites without SBS. SEM fractography confirmed better adhesion between the PE matrix and wood particles when SBS was present. DMTA measurements confirmed molecular interaction between PS and wood, the glass transition (Tg) peak of PS moved towards the Tg peak of cellulose
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| 10. |
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