Advantage and Disadvantage of Plastic

There is a wide variation in properties among the over 35,0000 commercially available materials classified as plastics. They now represent an important, highly versatile group of commodity and engineering plastics. Like steel, wood, and other materials, specific groups of plastics can be characterized as having certain properties. As with other materi- 

Become aware that tor any gain there could be a loss not originally included in the design performance. 

When you gain something there will be a loss.does 

Many plastics are typically not as strong or as stiff as metals, and they are prone to dimensional changes, especially under load and/or heat. Successful designs take these conditions into account when they influence design requirements. As will be seen, there are plastics that meet dimensional tight requirements, dimensional stabilities, and are 

As an example, for room-temperature applications most metals can be considered to be truly elastic. When stresses beyond the yield point are permitted in the design, permanent deformation is considered to be a function only of applied load and can be determined directly from the stress-strain diagram. The behavior of most plastics is much more dependent on the time of application of the load, the past history of loading, the current and past temperature cycles, and the environmental conditions. Ignorance of these conditions has resulted in the appearance on the market of plastic products that were improperly designed. Fortunately, product performance has been greatly improved as the amount of technical information on the mechanical properties of plastics has increased in the past half century. More importantly, designers have become more familiar with the behavior of plastics rather than 

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