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COMPOSITES FROM RECYCLED WOOD AND PLASTICS
Youngquist, J. A., G. E. Myers, J. H. Muehl, A. M. Kryzsik, C. M. Clemons, AND L. M. Brown*. COMPOSITES FROM RECYCLED WOOD AND PLASTICS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-95/003 (NTIS PB95-160008), 1995.
The ultimate goal of this research was to develop technology to convert recycled wood fiber and plastics into durable products that are recyclable and otherwise environmentally friendly. Two processing technologies were used to prepare wood-plastic composites: air-laying and melt-blending. Research was conducted in (1) developing laboratory methods for converting waste wood, wastepaper, and waste plastics Into forms suitable for processing into composites; (2) optimizing laboratory methods for making composite panels from the waste materials; (3) establishing a database on the effects of formulation and bonding agent on physical and mechanical properties of composites; (4) establishing the extent to which the composites can be recycled without unacceptable loss in properties; and (5) reaching out to industry to provide education, to develop applications, and to extend the database. Overall, the program demonstrated that both air-laid and melt-blended composites can be made from a variety of waste wood, wastepaper, and waste plastics. The composites exhibit a broad range of properties that should make them useful in a wide variety of commercial applications. For air-laid composites, the waste materials were demolition wood waste and waste plastics from milk bottles (polyethylene) and beverage bottles (polyethylene terephthalate). Results showed that air-laid composites made from these waste ingredients possessed properties very similar to those of composites made from the virgin ingredients. In addition, air-laid composites containing 20% reground panels possessed some properties that were superior to those of the original composites. For melt-blended composites, waste materials were wastepaper, polyethylene from milk bottles, and polypropylene from automobile battery cases or ketchup bottles. Waste magazines were slightly inferior to waste newspapers as a reinforcing filler; the properties of composites made from waste newspaper were better than those of composites made from wood flour, which is currently used in come commercial composites. Properties of wood-plastic composites were generally parallel to those of the plastics; thus, different balances in composite properties are possible from using waste plastic. Outreach activities included the organization of two international conferences on wood fiber-plastic composites, conference presentations, publication of several papers, and several spin-off cooperative studies with industry. One major study with industry demonstrated the commercial feasibility of making melt-blended composites from old newspapers and polypropylene.