Wood-polymer composites applications

Wood-Polymer Composites and Their Industrial Applications... 

Treatment of solid wood over the years for increased utility included many chemical systems that affected the cell wall and filled the void spaces in the wood. Some of these treatments found commercial applications, while some remain laboratory curiosities. A brief description of the earlier treatments is given for heat-stabilized wood, phenol-formaldehyde-treated veneers, bulking of the cell wall with polyethylene glycol, ozone gas-phase treatment, ammonia liquid- and gas-phase treatment, and p- and y-radiation. Many of these treatments led to commercial products, such as Staybwood, Staypak, Im-preg, and Compreg. This chapter is concerned primarily with wood-polymer composites using vinyl monomers. Generally, wood-polymers imply bulk polymerization of a vinyl-type monomer in the void spaces of solid wood. 

Applications blow molded bottles, calendered sheet, exterior trim, fence, film, foam, pipe, profile, rigid containers, siding, windows, wood-polymer composites... 

The enthusiasm in this field is explained by the number of potential applications. For example wood-polymer composites (WPC), mostly manufactured through extmsion and injection moulding processes are used in automotive (dashboards or screen-doors of the vehicles) and construction applications (interior floor coverings, profiles for doors and windows, ornamental panels, external shutters, pavements, garage, or entrance doors). Replacement of wood products for building applications such as particleboard and fiberboard materials or injection mouldable wood is another area where natural fibers are generating increased interest. 

Major polymer applications aircraft interiors, automotive (pump housings, transmission reactors, timing pulleys), marine, construction, coatings, adliesives. carbonless copy paper, abrasives, friction materials, laminates, foimdry resins, battery separators, wood bonding, composites, foam, hollow spheres... 

In a similar manner, as it was discussed in the preceding section, we can ask— how stiff a WPC deck board can possibly be, if not filled with mineral fillers We know that wood is very stiff, at least in applications WPCs are intended for. As it is shown in Chapter 7, flexural modulus of wood is about 1,500,000 psi. Polymers are much more flexible, and flexural modulus for HDPE is at best at 150,000 psi (Chapter 2). Again, in a very simplified case, for 50% HDPE - 50% wood fiber composites, in which both principal ingredients are ideally mixed and wood fiber is oriented along the flow, that is, longitudinally, the flexural modulus would be equal to a symmetrical superposition of the flexular moduli of the matrix and the fiber, which is about 825,000 psi. 

J.-R. Schauder. Exxelor coupling agents for wood fibers reinforced composites. In Wood fibre Polymer Composites Symposium. Application and Trends, Bordeaux, France, March 27-28, 2003. 

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