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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 8. |
- 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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| 9. |
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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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| 12. |
- Huuhilo, Tiina, et al.
(författare)
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Impact of mineral fillers to the moisture resistance of wood-plastic composites
- 2010
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Ingår i: Baltic Forestry. - 1392-1355 .- 2029-9230. ; 16:1, s. 126-131
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Tidskriftsartikel (refereegranskat)abstract
- The impact of mineral fillers to the moisture resistance of the wood-plastic composites (WPC) is studied. Five inorganic fillers were tested for the wood-plastic composites calcium carbonate, two different types of wollastonite, soapstone and talc. The amount of polypropylene, wood and mineral was held constant, only the mineral type was changed during the tests. The studied composites were also compared with a reference sample, which was manufactured without any mineral addition. All added minerals decreased the swelling and moisture absorption of the wood-plastic composite considerably. Also the density of the wood-plastic composites increased when minerals were added. Without any added mineral, clear openings could be seen in the composite structure in scanning electron microscope (SEM) pictures. These openings could work as pathways for water into the inner parts of the WPC and increase swelling. It could also be seen in the SEM pictures that when mineral was added, these pathways for moisture were closed. After three weeks soak/freeze/dry cycles, the bending strength of the reference sample decreased considerably more than the bending strength of the samples with added minerals. Of the studied minerals, talc was the most effective.
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| 13. |
- Huuhilo, Tiina, et al.
(författare)
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Mineral fillers for wood-plastic composites
- 2010
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 5:1, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- Five mineral fillers were tested for wood-plastic composites (WPCs): calcium carbonate, two different types of wollastonite, soapstone and talc. The impact of the fillers on the mechanical properties of the composites was studied. The experiments included bending tests, tensile tests, Brinell hardness and scanning electron microscopy experiments. The amount of wood, mineral and plastic (polypropylene) was kept steady. Only the mineral type was changed during the tests. A control sample without any mineral added was also manufactured. The mineral addition improved the tensile strength of the WPCs. The hardness of the composite was also improved when the minerals were added, and along with the increasing mineral hardness, the hardness of the composite increased. The wollastonite acicular shape was crushed during the manufacturing process, so the phase of the process in which the minerals are added requires careful consideration.
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| 14. |
- Hyvärinen, Marko, et al.
(författare)
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Ultraviolet light protection of wood-plastic composites a review of the current situation
- 2013
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Ingår i: Advanced Science Letters. - : American Scientific Publishers. - 1936-6612 .- 1936-7317. ; , s. 320-324
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Tidskriftsartikel (refereegranskat)abstract
- Wood-plastic composites (WPCs) have several exterior applications where they are easily exposed to ultraviolet (UV) radiation. The paper presents the current situation in a field of UV protection of WPCs, including the most commonly used protective agents and methods, such as UV absorbers and hindered amine light stabilizers (HALS). Surface dressing methods, such as painting, coating and film coating are not included. The focus of the paper is on the ways of how to integrate UV protection comprehensively over the material. The work is a literature review and practical experiments are not included.
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| 15. |
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| 16. |
- Martikka, Ossi, et al.
(författare)
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The effect of mineral fillers on the thermal properties of wood-plastic composites
- 2012
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Ingår i: Wood Material Science & Engineering. - : Taylor & Francis. - 1748-0272 .- 1748-0280. ; 7:2, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- The thermal properties of wood-plastic composites with five different mineral fillers were studied. The tested mineral fillers were calcite (CaCO 3), two different qualities of wollastonite, soapstone, and talc. The amount of wood, mineral, and plastic (polypropylene) was kept constant. Only the mineral type has been changed during the tests. The thermal behavior of the samples was studied by using a differential scanning calorimeter, a thermogravimetric analyzer and by determining the heat build-up. The analyzed properties were compared with a reference sample made without adding any minerals. The results show that the addition of mineral fillers does not remarkably change the thermal stability of composites. All the studied mineral fillers except soapstone had a small effect on the heat build-up.
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| 17. |
- Stenudd, Stefan
(författare)
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Colour Response in Drying of Nordic Hardwoods
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Colour and appearance of hardwood are of great importance for the interiorand furniture industry. The widespread use of transparent surface treatmentand a fashion that prescribe light colour on many species, means that deviationfrom the ideal have considerable impact on the industrial operations. Kilndrying is generally regarded as the process that has the greatest impact on thecolour of Nordic hardwood species. The lack of satisfactory explanation modelsfor many types of discoloration, however, complicates the control of the dryingprocess.This thesis is an attempt to increase the knowledge of which factors thatcontrol the appearance of some commonly found discolorations associated withdrying of beech, birch and oak. The main focus is on convection drying but alsothe influence of timber storage, pre-steaming and press drying has beeninvestigated for individual species. The studies have been conducted ascomparative studies based on design of experiments in which the colour wasdetermined using a colorimeter.Results show that reddish and dark discoloration of beech and birch duringconvective drying is mainly dependent on the temperature and time of exposurewhen the local moisture content exceeds the fibre saturation point. Theconversion of naturally occurring substances in birch into coloured compoundsis not due to active precursors created at high moisture content levels duringthe subsequent drying at low moisture content levels. Interior grey stain inbeech is caused by slow initial drying at low temperatures. Log storage in coldwinter and spring climate does not cause discoloration in beech. Birch becomeslighter when press-dried at high temperatures, resulting in a colour comparableto that of traditionally kiln dried wood. Steaming of oak before kiln dryingreduce the presence of brown discoloration, a general darkening of the woodoccurs at temperatures above 50°C.
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