Technical Report #19 - Chelsea Center for Recycling and Economic ...
I. ABSTRACTThe market for wood-thermoplastic composite products is growing rapidly. Estimatessuggest current production is about 300 million pounds per year, a three-fold increase over twoyears ago. Major markets are decking materials, pallets, and automobile and window components.Fueled by the decreasing availability of solid wood relative to projected demands, bothrecycled wood and plastic materials are being investigated as substitutes. The combination ofplastics and wood has been limited to polymers with lower melting point to avoid degradation ofthe wood materials. These include polypropylene, low and high density polyethylene, polystyrene,and polyvinyl chloride. The wood is in flour form, which is produced from planer shavingsand kiln dried mill residues. Construction and demolition wood can also be used to producecomposites. Many producers of wood-plastic lumber are seeking ways to improve the performancecharacteristics of their products. The use of wood fiber rather than wood flour in combinationwith the plastic materials may enhance the structural properties of composites. Although thewood-thermoplastic products industry has a significant history, technology is still being developed.Recommended products for Massachusetts manufacturers include composite decking, specialtywood-plastic compounds to be supplied to manufacturers of finished products, and fiberbasedproducts using technology developed by Dr. Alan Marra. Additional research and developmentefforts are warranted.II.INTRODUCTIONIn July 1998, the Forest and Wood Products Institute at Mount Wachusett CommunityCollege was contracted by the Chelsea Center for Recycling and Economic Development to researchthe potential for new or expanded uses for wood-plastic composite products in Massachusetts.The industry partner for the project was the Massachusetts Natural Resources Center Co-opof Greenfield, Massachusetts.1. BackgroundGlobal demand for timber products is increasing rapidly as a direct result of the growingworld population, which is projected to double within the next 35 to 70 years. According to theU.S. Forest Service, domestic demand for wood fiber in the United States will increase by 50%by the year 2020. However, during the period from 1989 to 1995, total softwood lumber productionin the United States decreased from 38.1 to 32.2 billion board feet, even though sawmills inthe southern United States were operating at record levels. Allowable levels of timber harvestingin U.S. national forests in the Pacific Northwest, long considered the breadbasket of softwoodlumber production, have been reduced, resulting in less wood production nationwide. Accordingto Evergreen Magazine of Medford, Oregon (2), of the nation's softwood standing inventory,47% is located in publicly owned national forests. Pacific coast national forests hold about twiceas much timber as all other national forests combined, so reductions in allowable harvests by theU.S. Forest Service have a significant effect on timber supplies.A decreasing supply of solid wood materials from public lands is expected to result ingrowing market opportunities for substitute materials, including composite materials producedfrom combinations of recycled wood fiber and plastic. Trade journals repeatedly cite the developmentof new composite materials ranging from improved fire-retardant roof panels made from1
i. CompetitionAll composite decking
Table 22: Effect of Variable Additi
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