Polyvinyl chloride , abbreviated as PVC in English, is a polymer of vinyl chloride monomer (VCM) polymerized by peroxides, azo compounds and other initiators or under the action of light and heat according to the free radical polymerization reaction mechanism. . Vinyl chloride homopolymer and vinyl chloride copolymer are collectively referred to as vinyl chloride resin.
PVC is a white powder with an amorphous structure with a small degree of branching. The glass transition temperature is 77~90℃, and it starts to decompose around 170℃. It has poor stability to light and heat. Decomposition produces hydrogen chloride, which is further autocatalyzed and decomposed, causing discoloration, and the physical and mechanical properties also decline rapidly. In practical applications, stabilizers must be added to improve the stability to heat and light.
The molecular weight of industrially produced PVC is generally in the range of 50,000 to 110,000. It has a large polydispersity. The molecular weight increases with the decrease of polymerization temperature. It has no fixed melting point. It starts to soften at 80-85°C and becomes viscoelastic at 130°C. , 160～180℃ begin to transform into viscous fluid state; it has good mechanical properties, the tensile strength is about 60MPa, the impact strength is 5-10kJ/m2, and it has excellent dielectric properties.
