满意会加分
It would be difficult to visualise想象 our modern world without plastics. Today they are an integral必备的 part of everyone’s lifestyle生活方式 with applications varying from commonplace普通的 articles to sophisticated复杂的,尖端的scientific and medical instruments医疗器械. Nowadays designers设计师 and engineers工程师 readily turn to plastics because they offer combinations制品 of properties not available可用的 in any other materials原料. Plastics offer advantages such as lightness轻盈,灵活, resilience有弹性, resistance to corrosion耐腐性, colour fastness色牢度, transparency透明性,透光度, ease of processing, etc. , and although they also have their limitations限制, their exploitation开发 is limited only by the ingenuity创造力,机敏 of the designer.
It is usual to think that plastics are a relatively recent development but in fact, as part of the larger family called “polymers”高分子材料 they are a basic ingredient组成部分,要素 of plant and animal life. Polymers are materials原料 which consist of very long chain-like连锁 molecules分子学. Natural materials such as silk丝,绸, shellac虫胶漆, bitumen沥青, rubber橡胶 and cellulose纤维素 have this type of structure型式. However, it was not until the 19th century that attempts were made to develop a synthetic polymeric material人造聚合材料 and the first success was based on cellulose纤维素. This was a material called “parkesine”硝化纤维素熟料, after its inventor Alexander Parkes亚历山大, and although it was not a commercial商务的 success it was a start and eventually终于,最后 led to the development of “Celluloid”赛璐璐. This, material was an important break-though突破,重要技术成就 because it because established已制定的,确定的 as a good replacement for natural materials天然材料 which were in short supply.