Wood-plastic composites chemical modifications

New developments give options in the form of hybrid materials combining wood with conventional plastics (e.g. Wood Plastic Composites, WPC) (Section 9.4.4) or as solid wood improved by heat treatment or chemical modification, e.g. acetylation, oil treatment etc. (Section 9.4.5). 

Farsi, M. Wood-plastic composites influence of wood flour chemical modification on the mechanical performance. J. Reinf. Plast. Compos. 29(24), 3587-3592 (2010). ISSN... 

When used as substitutes for asbestos fibers, plant fibers and manmade cellulose fibers show comparable characteristic values in a cement matrix, but at lower costs. As with plastic composites, these values are essentially dependent on the properties of the fiber and the adhesion between fiber and matrix. Distinctly higher values for strength and. stiffness of the composites can be achieved by a chemical modification of the fiber surface (acrylic and polystyrene treatment [74]), usually produced by the Hatschek-process 75-77J. Tests by Coutts et al. [76] and Coutts [77,78] on wood fiber cement (soft-, and hardwood fibers) show that already at a fiber content of 8-10 wt%, a maximum of strengthening is achieved (Fig. 22). 

Timar, M.C., Maher, K., Me, M. and Mihai, M.D. (1999b). High performance wood-fibre/plastic composites by chemical modification. In Proceedings of the Third European Panel Products Symposium, Hague, 1., Griffiths, S., Loxton, C., McLauchlin, A., Mayhead, G. and Tomkinson, J. (Eds.), pp. 352-358. 

The interface between plastic and wood fibres strongly influences the mechanical properties of a plastic/wood fibre composite. A means for evaluating the effectiveness of surface treatment on the wood fibres in the PVC/wood fibre composites is presented that investigated the adhesion between PVC and laminated wood veneers. Wood veneers were first treated with gamma-aminopropyltriethoxysilane, dichlorodiethylsilane, phthalic anhydride, and maleated PP for surface modification. The chemical modification made on the wood surfaces was then characterised by different complementary surface analytical techniques X-ray photoelectron spectroscopy and surface tension measurements. 63 refs. 

Moreover, wood has limited thermoplasticity. Although it can be bent under steam and chemical treatment, wood normally bums before it melts or becomes sufficiently plastic for heat molding or extrusion. These two techniques are important ways of shaping materials in high-speed composite production and are therefore keys to the cost-efficient penetration of lignocellulosic materials into the composites market. Chemical modification of wood offers a means of improving its thermoplasticity. 

POs are widely used as a matrix in wood fiber-plastic composites [205-207]. MA graft copolymers, such as maleated PPs, are applied as coupling agents, for the preparation of composites useful in the automobile and packaging industries [208,209], and for outdoor application because when maleated PP is used, the fiber surface becomes hydrophobic and the water uptake decreases significantly [209]. In situ chemical modification-interfacial interaction was observed by several researchers [82,210,211] in the maleated... 

Ramires EC, Megiatto JD Jr, Gardrat C, Castellan A, Erollini E (2010) Biobased composites from glyoxal-phenolic resins and sisal fibers. Bioresour Technol 101 1998-2006 Reddy MM, Vivekanandhan S, Misra M, Bhatia SK, Mohanty AK (2013) Biobased plastics and bionanocomposites current status and future opportunities. Prog Polym Sci 38 1653-1689 Rojas OJ, Montero GA, Habibi Y (2009) Electrospun nanocomposites from polystyrene loaded with cellulose nanowhiskers. J Appl Polym Sci 113 927-935 Rowell RM (2012a) Chemical modification of wood to produce stable and durable composites. Cell Chem Technol 46 443 148... 

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