Plastic is a common item in our life, it is an organic synthetic polymer material, which is very widely used. In the past many years, with the great convenience that plastics have brought to our production and life, the "white pollution" caused by waste plastics has become increasingly serious. If we can understand the composition and classification of plastics in detail, it can not only help us use plastic products scientifically, but also facilitate the sorting and recycling of plastics, and e