Advanced polymer/wood composite structural member

Abstract

A polymer and wood composite structural members can be manufactured by extruding and injection molding a composition comprising polyvinyl chloride, wood fiber and optionally a concentration of an intentionally added waste stream. Such structural members have strength, workability, fastener retention, resistance to rot and insect attack, and thermal properties sufficient to constitute an advanced composite wood replacement material. The advanced structural member can be used as a component in construction of any structure requiring sized lumber or specifically shaped wood products. In such an application, the structural members can be extruded in the shape of commonly available lumber. The structural members of the invention can also be extruded in complex shapes adapted to the assembly of windows and doors used in both residential and commercial structures. The structural members have a modulus, a coefficient of thermal expansion, a coefficient of elasticity, a compressive strength and other related properties ideal for use as a replacement for either metal or wood, window or door structural components. The preferred structural member is manufactured from a polyvinyl chloride and wood fiber composite that optionally contains an intentionally recycled impurity component. Such components comprise waste materials common in the manufacture of wood doors and windows. We have found that the cooperation between the amount of polymer material, the amount of an oriented wood fiber, and control over water content results in the improved structural properties of the composite structural members of the invention.