Polyvinyl chloride, abbreviated as PVC, is an initiator of vinyl chloride monomer (VCM) in peroxides, azo compounds, and other compounds; Or polymers formed by free radical polymerization reaction mechanism under the action of light and heat. Vinyl chloride homopolymers and vinyl chloride copolymers are collectively referred to as vinyl chloride resins.
PVC is an amorphous white powder with a low degree of branching, a relative density of about 1.4, a glass transition temperature of 77-90 ℃, and begins to decompose at around 170 ℃ [1]. It has poor stability to light and heat, and will decompose to produce hydrogen chloride above 100 ℃ or after prolonged exposure to sunlight, which will further catalyze decomposition, causing discoloration and rapid decline in physical and mechanical properties. In practical applications, stabilizers must be added to improve their stability to heat and light.
The molecular weight of PVC produced in industry is generally in the range of 50000 to 110000, with high 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 transforms into a viscous flow state at 160-180 ℃; Has good mechanical properties, with a tensile strength of about 60MPa and an impact strength of 5-10kJ/m2; Has excellent dielectric properties.
PVC was once the world's largest general-purpose plastic in terms of production, with a wide range of applications. It is widely used in building materials, industrial products, daily necessities, floor leather, floor tiles, artificial leather, pipes, wires and cables, packaging films, bottles, foam materials, sealing materials, fibers, and other fields.