原版英语论文.doc

Wood-posites in the United States The interfacing of two industries. The term wood-posites refers to posites that contain wood (of any form) and thermosets or thermoplastics. Thermosets are plastics that, once cured, cannot be melted by reheating. These include resins such as epoxies and phenolics, plastics with which the forest products industry is most familiar. Thermoplastics are plastics that can be repeatedly melted, such as polyethylene and polyvinyl chloride (PVC). Thermoplastics are used to make many mercial products such as milk jugs, grocery bags, and siding for homes. Wood-posites date to the early 1900s. An posite marketed under the trade name Bakelite posed of phenol-formaldehyde and wood flour. Its mercial use was reportedly asa gearshift knob for Rolls Royce in 1916 (Gordon 1988). Wood-posites have been manufactured in the United States for several decades, and the industry has experienced tremendous growth in recent years. This article focuses on wood-posites, which are most often simply referred to as wood-posites ( WPC s) with the understanding that the plastic isa thermoplastic The birth of the WPC industry involved the interfacing of two industries that have historically known little about each other and have very different knowledge, expertise, and perspectives. The plastics industry has knowledge of plastics processing, and the forest products industry has more experience and resources in the building products market. Not surprisingly, some of the panies to produce WPCs were window manufacturers that had experience with both wood and plastics. The plastics industry has traditionally used talc, calcium carbonate, mica, and glass or carbon fibers to modify the performance of plastic; about billion kg ( billion lb.) of fillers and reinforcements are used annually (Eckert 2000). The industry was reluctant to use wood or other natural fibers, such as kenaf or flax, even though these fibers are from a renewable resource and are less expensive,