PVC is a white powder with amorphous structure. Its branching degree is small, its relative density is about 1.4, its glass transition temperature is 77-90 C, and its decomposition begins at 170 C. It has poor stability to light and heat. When it is above 100 C or exposed to sunlight for a long time, it will decompose into hydrogen chloride, which will be further decomposed by autocatalysis, causing discoloration and rapid decline in physical and mechanical properties. Stabilizers must be added to improve the thermal and light stability.