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- Butylina, Svetlana, et al.
(författare)
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Comparison of water absorption and mechanical properties of wood-plastic composites made from polypropylene and polylactic acid
- 2010
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 5:3-4, s. 220-228
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Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the water absorption and mechanical properties of composites made from softwood sawdust and plastics, such as virgin and recycled polypropylene and polylactic acid (PLA). The composites were processed by extrusion, and their properties were investigated by a water immersion test, mechanical tests and a cyclic test for moisture resistance. Scanning electron microscopy was used to study the morphology of the fracture surfaces of the composites. The composites made with recycled polypropylene had the lowest water absorption and thickness swelling of the studied composites. The PLA composites made with heat-treated sawdust showed the highest flexural strength. Of the polypropylene based composites, virgin polypropylene resulted in composites with higher flexural strength. The Charpy impact strength of the composites was found to have an inverse trend compared to flexural strength. Cyclic treatment of the studied composites resulted in 20-60% loss of flexural strength, depending on type of composite.
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- Butylina, Svetlana, et al.
(författare)
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Effects of water immersion-freeze-thaw cycling on the properties of wood-polypropylene composites containing pigments
- 2011
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Ingår i: Pigment & Resin Technology. - : Emerald Group Publishing Limited. - 0369-9420 .- 1758-6941. ; 40:6, s. 386-392
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to study the effects of water immersion-freeze-thaw treatment on the physical properties, flexural strength (FS) and morphology of wood-polypropylene composites containing pigments. Design/methodology/approach - Wood-polypropylene composites containing brown, green and grey pigments were compounded in a conical twinscrew extruder. A composite manufactured without any pigment addition was used as a reference. The amount of pelletized wood, polypropylene and coupling agent (MAPP) was kept constant. The moisture content, thickness swelling (TS), FS and surface colour of the composites were measured before and after water immersion-freeze-thaw cycling. Scanning electron microscopy (SEM) was used to study the morphology of the composites. Findings - FS and dimensional stability were reduced after exposure to water immersion-freeze-thaw cycling for all composites. The surface properties (colour and roughness) of the composites also changed after exposure to water immersion-freeze-thaw cycling. The degree of change depended on the presence of pigment and the type of polypropylene (neat or recycled), however. Research limitations/implications - This study is a part of an ongoing study on weathering of wood-polymer composites (WPC) containing different additives. The results of this study were obtained from accelerated laboratory experiments. Practical implications - Inorganic pigments are widely used as additives in plastics, because they have an excellent UV absorption, good IR-reflective properties and heat stability. The research revealed that metal-containing pigments had an effect on degradation in quality of wood-polypropylene composites exposed to water immersion-freeze-thaw cyclic treatment. The addition of metal-containing pigments to composite formulation resulted in a higher susceptibility of wood-polypropylene composites to water absorption, and as a consequence to a higher drop of FS compared to composites made without pigment. The polymer matrix plays an important role in the protection of WPC against weathering. Originality/value - This paper will help in understanding possible problems in the durability of wood-polypropylene composites compounded with metal-based pigments when they are exposed to water immersion-freeze-thaw cyclic treatment.
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- Butylina, Svetlana, et al.
(författare)
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Physical and mechanical properties of wood-polypropylene composites made with virgin and/or recycled polypropylene
- 2011
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Ingår i: Polymer-plastics technology and engineering (Softcover ed.). - : Taylor & Francis. - 0360-2559 .- 1525-6111. ; 50:10, s. 1040-1046
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Tidskriftsartikel (refereegranskat)abstract
- The physical and mechanical properties of wood-polymer composites made with virgin or recycled polypropylene, or a mixture of these were studied. The composites made with recycled polypropylene had higher density, lower porosity, and higher dimensional stability compared to the composites made with virgin polypropylene. Although the composites made with recycled polypropylene exhibited lower tensile strength than those made with virgin polypropylene, they had higher Charpy impact strength. Scanning electron microscopy analysis of the fractured surfaces of the composites showed no significant differences in the fracture mechanisms of the studied composites. The degree of crystallinity was estimated to be higher for the virgin polypropylene than for the recycled one.
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- Butylina, Svetlana, et al.
(författare)
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Properties of wood fibre-polypropylene composites : Effect of wood fibre source
- 2011
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Ingår i: Applied Composite Materials. - : Springer. - 0929-189X .- 1573-4897.
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Tidskriftsartikel (refereegranskat)abstract
- This study examined the effect of type of wood fibre source on the physical and mechanical properties of wood fibre-polypropylene composites. Wood flour, fibres of heattreated wood and pellets were used as sources of wood fibres in the manufacturing process. All studied wood fibre-polypropylene composites were made from 75% wood, 22% recycled polypropylene (PP) and 3% maleated polypropylene (MAPP). Wood fibrepolypropylene composites were compounded in a conical twin-screw extruder. Water absorption and thickness swelling were studied. Mechanical properties of the composites were characterised by tensile, flexural, and impact testing. Micromechanical deformation processes were investigated using scanning electron microscopy done on the fractured surfaces of broken samples. The durability of composites exposed to three accelerated cycles of water immersion, freezing and thawing was examined. The results showed that the density of the composites was a key factor governing water absorption and thickness swelling. A significant improvement in tensile strength, flexural strength, and Charpy impact strength was observed for composites reinforced with heat-treated fibre compared to composites reinforced with pellets and especially to wood flour reinforced composites. The flexural strength and dimensional stability performance reduced after exposure to freezethaw cycling for all composites, but the degree of these changes was dependent on the wood fibre source.
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- Butylina, Svetlana, et al.
(författare)
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Thermal performance and optical properties of wood-polymer composites
- 2013
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Ingår i: Journal of Thermoplastic Composite Materials. - : SAGE Publications. - 0892-7057 .- 1530-7980. ; 26:1, s. 60-73
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Tidskriftsartikel (refereegranskat)abstract
- The thermal performance and optical properties of wood–polypropylene composites made from untreated wood material with and without metal-containing pigments, and composites made from heat-treated wood material were studied. The thermal heat buildup and linear shrinkage were determined. The impact of the optical properties of the surface of the composites on the heat buildup was analysed. The wood–polypropylene composites made from untreated wood without pigment were found to have the lowest heat buildup; a similar composite containing grey pigment had the highest heat buildup. The linear shrinkage of the studied wood–polypropylene composites was in the range 0.05–0.16%.
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| 10. |
- Butylina, Svetlana, et al.
(författare)
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Weathering of wood-polypropylene composites containing pigments
- 2012
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Ingår i: European Journal of Wood and Wood Products. - : Springer. - 0018-3768 .- 1436-736X. ; 70:5, s. 719-726
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Tidskriftsartikel (refereegranskat)abstract
- Outdoor applications of composites have raised questions about their durability. In this study, the effects of outdoor weathering on the properties of wood-polypropylene composites with and without pigments were examined. The composites were placed outdoors for one year, and their colour changes were evaluated after 1, 3, 6, 9 and 12 months of weathering. The durability of the composites was assessed by testing flexural strength and density. Scanning electron microscopy was applied to evaluate the surface degradation of the composites. The weathering resulted in considerable colour fading of the composites. The composites containing darker colour pigments had better colour stability. After weathering, the general trend was a decrease of the flexural strength and density of the composites. The decrease in flexural strength was found to be lower for the composites having higher density.
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