Polyvinyl chloride (PVC) is the initiator of vinyl chloride monomer in peroxides, azo compounds and so on. Or a polymer polymerized under the action of light and heat according to a free radical polymerization mechanism. Vinyl chloride homopolymer and vinyl chloride polymer are collectively referred to as vinyl chloride resin.
PVC is a white powder with amorphous structure, and its branching degree is small, and its relative density is about 1.4. It begins to decompose at the glass transition temperature of 77~90℃ and around 170℃, and has poor stability to light and heat. When it is higher than 100℃ or exposed to sunlight for a long time, it will decompose to produce hydrogen chloride, which will further decompose automatically and cause discoloration.
The molecular weight of industrial PVC is generally in the range of 50000 ~ 1 10000, which has great polydispersity, and the molecular weight increases with the decrease of polymerization temperature. Without a fixed melting point, it begins to soften at 80 ~ 85℃, becomes viscoelastic at 130℃, and becomes viscous at 160 ~ 180℃. It has good mechanical properties, the tensile strength is about 60MPa, and the impact strength is 5 ~ 10 kJ/m2. Has excellent dielectric properties.
PVC used to be the largest general-purpose plastic in the world, and it was widely used. Widely used in building materials, industrial products, daily necessities, floor leather, floor tiles, artificial leather, pipes, wires and cables, packaging films, bottles, foaming materials, sealing materials, fibers and so on.