Wood Fiber—Resin Composite Lumber

Wood fiber - recycled plastic composite lumber is a relatively new development and is similar to PS addition to plastic lumber because the potential exists for improved mechanical propenies and dimensional stabilities. Wood fiber addition can serve as an excellent reinforcement for plastics, and wood fibers arc abundant, lightweight, nonabrasive, nonhazardous and inexpensive. An effort is being made to examine the incorporation of treated and untreated aspen fibers into recycled HOPE milk bottles (Yam et al., 1990]. The work has shown tensile strength and Izod impact strength below that of HOPE alone when aspen fiber is added. Tensile modulus and flexural modulus are increased significantly above HOPE alone with the addition of wood fiber. Dispersion of the fiber in the resin has been reported as a dominating factor in the process thus far. 

Another effort is being made to examine the recycle of wood fiber-PS composites into the same material and testing the resultant product under extreme conditions (e.g., exposure to boiling water, at room temperature, 105°C and -20 C). The composite material was reground to a number 20 mesh size and remolded three dmes in the experiment Compared with the original extruded composite, the mechanical properties and dimensional stabilities of the recycled material did not change significantly even after exposure under extreme conditions. Detailed data on the study are contained in Maldas and Kokta [ 1990]. 

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Wood Science Technology (WSTI), Corvalis, Oregon, USA—Zoltec and Dow Chemical Co. have an agreement with WSTI, who will use WSTI patents and manufacture thin sheets of composite laminate for the reinforcement of engineered lumber products using Zoltek s carbon fiber and Dow s Derakane epoxy vinyl ester resins. 

Wood composite products are conventionally manufactured from wood materials having various geometries (eg, fibers, particles, strands, flakes, veneers, and lumber) combined with a thermoset resin and bonded in a press (4). The press applies heat (if needed) and pressme to activate (cross-link) the adhesive resin and bond the wood material into a sohd panel, lumber, or beam having good mechanical (strength and stiffness) and physical (form, dimensional stabihty, etc) properties. 

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