Plastic is a lighter material with a relative density of 0.90-2.2. Obviously, can plastic float to the water? In particular, foamed plastics have lighter texture due to micropores, and the relative density is only 0.01. This characteristic makes plastics available for the production of products requiring reduced self weight.

   Most plastics have good corrosion resistance to acids, alkalis and other chemicals. In particular, polytetrafluoroethylene (F4), commonly known as the king of plastics, has even better chemical stability than gold and will not deteriorate after boiling in "aqua regia" for more than ten hours. F4 is an ideal corrosion-resistant material because of its excellent chemical stability. For example, F4 can be used as a material for conveying corrosive and viscous liquid pipelines.

   Due to the non natural degradability of plastics, it has become the first enemy of mankind and has led to the tragedy of many animal deaths. For example, monkeys, pelicans, dolphins and other animals in the zoo will swallow the No. 1 plastic bottle thrown by tourists by mistake, and finally die painfully due to indigestion.

   Looking at the beautiful and pure sea surface, I came closer. In fact, it was filled with all kinds of plastic garbage that could not be accommodated by the sea. In the intestines of many dead seabird samples, I found all kinds of plastic that could not be digested.



   Some plastics are pure resins, such as polyethylene and polystyrene, which are called single component plastics. In addition to synthetic resins, some plastics also contain other auxiliary materials, such as plasticizers, stabilizers, colorants, various fillers, etc.

   Some plastics are as hard as stone and steel, while others are as soft as paper and leather; From the mechanical properties of plastics such as hardness, tensile strength, elongation and impact strength, it has a wide distribution range and has a great choice of use.

   Because of its small specific gravity and high strength, plastics have high specific strength. Compared with other materials, plastics also have obvious disadvantages, such as easy combustion, lower stiffness than metal, poor aging resistance, heat resistance and so on.