Wood-polymer composites properties

Fibres reacted with pre-heated MAPP always exhibited larger contact angles compared with fibres reacted with as-received MAPP. FTIR studies showed that there was a higher level of ester linkages when the fibres were reacted with the pre-heated MAPP. Wood polymer composites were made by shear mixing in a twin screw extmder, and the mechanical properties of these composites were found to be superior when pre-heated MAPP was used as the coupling agent. 

Some research has been done on the addition of polar solvents to the nonpolar monomer in an attempt to swell the cell wall structure and anchor it in a swollen state (9). This can be done and the antishrink efficiency (ASE) does increase, but after the solvent evaporates, the wood is only partially loaded which in turn decreases the physical properties. Wood-polymer composites normally have about 10-15% ASE, which means that there is some penetration of the cell wall structure to reduce the swelling over that of untreated wood. 

Fifteen years ago, when wood-plastic composites were first introduced many people predicted that this process would solve the problem of wood dimensional stability and great claims were made for its future use. Now that the physical properties of wood-polymer composites are better understood, specific commercial products are being produced which take advantage of the desirable aesthetic appearance, the high compression strength, increased hardness and abrasion resistance and improved dimensional stability. Future use of wood-polymer composites will depend upon the imagination of the producer and the market place. 

Figure 15 illustrates the load-deflection curves that were obtained from the experimental data. The Heilman-Gulf epoxy and the f rf-butylstyrene monomers were an improvement over the MMA. When the t rf-butylstyrene was diluted with 50% methanol the wood-polymer composite contained half of the maximum polymer loading, and the load-deflection data were the same as the untreated basswood. To obtain the maximum improvement in physical properties the wood must be fully loaded with polymer. In another study... 

Table VII. Properties of Various Wood-Polymer Composites...

JL HE POLYMERIZATION OF VINYL MONOMERS in the void spaces of bulk wood results in wood—polymer composites of increased strength properties and dimensional stability see Chapter 6). Because the different environmental conditions expose in-service timber to attack by numerous wood-deteriorating microorganisms, it is desirable to enhance the biodegradation resistance of wood, with simultaneous improvements in mechanical behavior. This chapter summarizes the formation of bioactive wood-polymer composites (1-4). The basic approach is still in situ polymerization of vinyl monomers in wood, with the appropriate choice of a bioactive, toxic, functional group incorporated in the monomer, and with other modifications based on wood-polymer reactions. 

The impregnation of wood by polymers with TBT functional groups offers a viable route to the preparation of bioactive wood— polymer composites with a number of advantages. Polymer impregnation may be expected to improve the strength properties and dimensional stability of wood in water. The controlled release of the toxic TBT moiety, chemically linked to the polymer located within the wood, can increase the service life of wood while ensuring min-... 

D. Dean. Influence of ethylene-anhydride copolymer coupling agents on the mechanical properties of HDPE based wood polymer composites. In Progress in Wood Fibre Plastic Composites 2006 International Conference, Toronto, Canada, May 1-2, 2006. 

Diene N. Fanton E. Morlat-Therias S. Vidal L. Tidjani A Gardette J.L. Durability of wood polymer composites Part 1. Influence of wood on the photochemical properties. Composites Science and Technology, vol. 68, (2008), pp. 2779-2784. 

Yap MG, ChiaSLHL, Teoh SH (1990) Wood-Polymer composites from tropical hardwoods I. WPC properties. J Wood Chem Technol 10 1-19... 

Islam et al. (2012) reported that the mechanical and morphological properties of wood polymer composites (WPCs) were improved significantly after pretreatment with alkali solution. For his study, methyl methacrylate (MMA) and styrene (ST)... 

M.S. Islam, S. Hamdan, M.R. Rahman, I. Jusoh, and A.S. Ahmed, The effect of alkali pretreatment on mechanical and morphological properties of tropical wood polymer composites. Mater. Des. 33,419-424 (2012). 

U.C. Yildiz, S. Yildiz, and E.D. Gezer, Mechanical properties and decay resistance of wood-polymer composites prepared from fast growing species in Turkey. Bioresour. Technol. 96, 1003-1011 (2005). 

I. Poke, P.J. Hine, M.J. Bonner, I.M. Ward, and D.C.Barton, Die drawn wood polymer composites. I. mechanical properties. Compos. Sci. Technol. 70(1), 45-52 (2010). ISSN... 

Mei C. Surface characteristics of modified poplar wood-flour and its effect on the mechanical properties of wood polymer composites. Rev Adv Mater Sci 2013 33 203-210. 

Even though there are several literatures on wood polymer composites, yet little information are available on the topic of the chemical resistance properties of these composites. The strength properties and esthetic appearance are deteriorated by chemicals. The hemicelluloses present in wood have low resistance to acid (Sjostrom 1993). Thus, wood polymer composites in which wood contains higher percentage of hemicellulose show substantially lower chemical resistance. 

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