Plastics are comparatively new materials made from chemicals in contrast to the materials found in nature such as wood and stone, metals mined from the earth or glass which is produced from naturally occurring materials. The first plastic was celluloid and it was made in 1862 and 35 years later casein from milk was the starting point for the second plastic. This was followed at intervals by a few others but the big expansion did not occur until after World War II, when a rapid advance in thermoplastic materials took place. Originally, several plastics were made from coal tar but nowadays they are derived from crude oil.
KeywordsWelding Polyethylene Hydrocarbon Sponge Nylon
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