Polyvinyl chloride, abbreviated as PVC, is a polymer made by polymerizing vinyl chloride monomers in peroxide, azo compounds, and other initiators; or under the action of light, heat, and according to the mechanism of free radical polymerization reaction. Vinyl chloride homopolymer and vinyl chloride **** polymer collectively called vinyl chloride resin.
PVC is an amorphous structure of white powder, small degree of branching, relative density of 1.4 or so, the glass transition temperature of 77 ~ 90 ° C, 170 ° C or so began to decompose, the stability of light and heat is poor, above 100 ° C or after a long period of exposure to sunlight, will decompose and produce hydrogen chloride, and further autocatalytic decomposition, resulting in discoloration, the physical and mechanical properties have also declined rapidly in the practical application must be added to stabilizers to improve the stability of the material. In practice, stabilizers must be added to improve the stability of heat and light.
Industrially produced PVC molecular weight is generally in the range of 50,000 to 110,000, with a large polydispersity, molecular weight with the decrease in polymerization temperature and increase; no fixed melting point, 80 ~ 85 ℃ began to soften, 130 ℃ into a viscoelastic state, 160 ~ 180 ℃ began to change into a viscous flow state; have good mechanical properties, tensile strength of 60MPa or so, impact strength of 5 ~ 10kJ/m2; have good mechanical properties, tensile strength of 60MPa or so, impact strength of 5 to 10kJ/m2; excellent dielectric properties.
PVC was once the world's largest production of general-purpose plastics, very widely used. In construction materials, industrial products, daily necessities, floor leather, floor tiles, artificial leather, pipes, wires and cables, packaging film, bottles, foaming materials, sealing materials, fibers and other aspects are widely used.