| thermoplastic composites as degradation-resistant material systems | |
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| Tweet Topic Started: Apr 10 2015, 03:19 AM (5 Views) | |
| qizhenkim | Apr 10 2015, 03:19 AM Post #1 |
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The plastic lumber industry originated in Japan and Europe during the early to mid- 1970’s where new equipment was being developed to make large cross-section thermoplastic polymer products.1,2,3 A lower abundance of wood than the United States and the possibility of these products as wood lumber substitutes drove development of the industry.<a href="http://woodfloormanufacturer.com/wood-floor-project/3337.html">wooden door designs for home</a> The early plastic lumber products were made mainly from post-industrial plastic waste that was the only resin material available at a reasonable price at that time. In the United States, a few small entrepreneurs were entering the field by the mid- 1980′s. Their efforts and those of others worldwide were hindered by: 1) the limited and uncertain supply of raw materials, 2) a lack of certifiable performance, 3) a significantly lower modulus as compared to wood along the growth axis, and 4) a plentiful supply of wood. The two main advantages of plastic lumber that are most apparent when compared to chemically treated wood are that the material is benign to the environment and that it will not degrade readily when used outdoors.4 As recycling efforts started to gain momentum, experts in the United States were considering plastic lumber processes as a possible alternative to landfilling the abundance of available post-consumer waste plastic containers.5 More than 8 billion pounds of plastic containers are produced each year in the United States with the majority being landfilled due to the lack of demand for their resins.6 The commercial viability of the plastic lumber industry in the United States is now being driven by the economic and logistical need to reduce disposal quantities of waste plastics and the development of more cost-effective designs and construction methods. The first applications of plastic lumber as a substitute for treated wood were in noncritical, outdoor applications. The substitution of any traditional material with a new material must take into account the required performance for the product and particular application in mind. At first, plastic lumber was considered for relatively low stress applications. Picnic tables and park benches have been successfully produced from plastic lumber, and are performing satisfactorily.<a href="http://woodfloormanufacturer.com/wood-floor-project/3921.html">composite auto parts</a> Some of the earliest designs had the product performing well when new but sagging over time. Since then, manufacturers have learned to design these structures with lower stress on the elements to reduce the time dependent properties affect on the overall shape. Many manufacturers found that they could produce decking boards to be fitted atop chemically treated wooden frames. This application typically has fairly low values of dead load stress, and the time-dependent properties do not play a very important role in most cases. The biggest problem in these applications seems to be the much larger thermal expansion coefficient of plastic lumber as compared to wood. Since just the decking boards are plastic lumber, one cannot claim that the whole structure will not biologically decay, or that it is not treated with hazardous materials. To make these claims, the entire structure must be made from plastic and/or polymer composites. Various types of treated woods are used in outdoor applications. Chemically treated yellow pine is typically used in the Eastern United States for decks and creosote-treated oak is used for railroad ties.cheapest composite decking material Despite the use of chemical treatments or protective coatings, wood eventually rots and must be replaced. The fact that wood has properties that cause it to deteriorate when left outside unprotected as well as imperfections such as knots, complicate its performance. The resources come from:http://woodfloormanufacturer.com |
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