(1) According to the heating behavior of synthetic resins, plastics can be divided into thermoplastics and thermosetting plastics. Thermoplastics can plasticize and soften when heated, solidify when cooled, and deform repeatedly when the temperature changes. Such as polyethylene (PE). Polyvinyl (PVC). Polystyrene (PS). Plexiglass (PMMA). Polycarbonate (PC), etc. Thermosetting plastics are plasticized and softened when heated, chemical changes occur, and crystallize into shape. After cooling, such as reheating, plasticizing deformation no longer occurs, and decomposition will occur if the temperature continues to rise. Such as phenolic plastic, urea formaldehyde plastic and so on.

(2) According to the use of plastics, it can be divided into three categories: general plastics, engineering plastics and functional plastics. Universal plastics are rich in source, large in output, widely used, cheap in price and easy in molding. Such as polyethylene (PE). Polygas ethylene (PVC). Polybenzene zene (PS). Polypropylene (PP). Engineering plastics have excellent comprehensive properties (such as electrical properties, mechanical properties, high and low temperature resistance, etc.), which can replace metal as engineering structural materials. Such as polyethylene terephthalate (PET). Polybutylene terephthalate (PBT). Polyamide (PA). Polycarbonate (PC). Polyformaldehyde (POM), etc. Functional plastics have some outstanding physical functions, such as high temperature resistance, corrosion resistance, radiation resistance, electrical conductivity, magnetic conductivity and so on. Such as polyimide, polyphenylene sulfide, polysulfone (PSU) and so on.