Plastic is a synthetic polymer compound that can change its shape freely. Is the use of monomer raw materials to synthesis or condensation reaction polymerization of materials, by synthetic resin and filler, plasticizer, stabilizer, lubricant, color additives, its main component is synthetic resin. The term resin was originally named after the lipids secreted by animals and plants, such as rosin, shellac, etc. At present, resin refers to polymers that have not been mixed with various additives. Resin accounts for about 40% to 100% of the total weight of plastics. The basic properties of plastics are mainly determined by the nature of the resin, but additives also play an important role. Some plastics are basically composed of synthetic resins with little or no additives, such as plexiglass, polystyrene, etc. Therefore, the terms plastic and resin are also used interchangeably.