Polyvinyl chloride (PVC) is a thermoplastic resin made by polymerization of vinyl chloride under the action of initiator. It is a homopolymer of vinyl chloride. Vinyl chloride homopolymer and vinyl chloride copolymer are collectively referred to as vinyl chloride resins. PVC is an amorphous white powder with low branching. The PVC molecular weight produced by industry is generally in the range of 50,000-120,000, which has a large multi-dispersion. The molecular weight increases with the decrease of polymerization temperature. No fixed melting point, 80 ~ 85 ℃ began to soften, 130 ℃ is a viscoelastic state, 160 ~ 180 ℃ began to change for the viscous flow; Good mechanical properties, tensile strength of about 60MPa, impact strength of 5 ~ 10kJ/m squared; Excellent dielectric properties. But poor stability to heat and light, in more than 100 ℃ or the sun for a long time, will decompose and produce hydrogen chloride, and further automatic catalytic decomposition, cause discoloration, physical and mechanical properties also fell rapidly, must be added in the practical application of stabilizers in order to improve the stability of heat and light. PVC is very hard and dissolute. It can only be dissolved in a few solvents such as cyclohexanone, dichloroethane and tetrahydrofuran. It is stable to organic and inorganic acids, bases and salts, and its chemical stability decreases with the increase of temperature. PVC dissolved in a mixture of acetone - carbon disulfide or acetone - benzene, used for dry spinning or wet spinning into fibers, known as polychloroprene. It has flame resistance, acid and alkali resistance, microorganism resistance, wear resistance and good heat preservation and elasticity.
1.Development trend of PVC resin industry
The consumption of PVC resin in China is mainly concentrated in south China and east China, and the consumption in guangdong, zhejiang, fujian, shandong and jiangsu accounts for about 70%of the total consumption in China. Among them, guangdong and fujian have the largest market demand, but the production capacity is insufficient, and the proportion of imported PVC resin is relatively high. The polyvinyl chloride resin processing industry in jiangsu, shandong and zhejiang is relatively developed, with the consumption of the three provinces accounting for approximately 34.0% of the total domestic consumption. Production and sales in north China are basically balanced. The consumption of polyvinyl chloride resin in the central and western regions will gradually increase with the development of the central and western regions and the construction of large-scale infrastructure.
The polyvinyl chloride resin industry is a basic and energy intensive industry, which is greatly influenced by demand and energy price and is also a basic chemical raw material, so it is also closely related to economic development. In recent years, due to domestic PVC resin capacity continues to decrease, while the downstream demand growth is relatively slow, and export, import, domestic PVC resin enterprises overall capacity utilization is not high, therefore, idled capacity number is larger, the market price also remain low, price fluctuation range is reduced, in addition, PVC resin futures listed in a certain extent, increased the fluctuations in the price of PVC resin market uncertainty. China's PVC resin industry will still be in a difficult period of integration, there will be a number of factors affecting the development of China's future PVC resin.