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What is pvc and what is the development history of PVC?

Update:25 Jun 2021
Summary:

Polyvinyl chloride (Polyvinyl chloride), abbreviated as […]

Polyvinyl chloride (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 at about 170℃[1]. It has poor stability to light and heat. It is above 100℃ or exposed to long-term sunlight. , It will decompose to produce hydrogen chloride, and further autocatalytic decomposition will cause discoloration, and the physical and mechanical properties will 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℃ and becomes viscoelastic at 130℃. , 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.
PVC used to be the world's largest production of general-purpose plastics, and it is widely used. It is 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, etc.
PVC was industrialized in the early 1930s. Since the 1930s, for a long period of time, the output of Customized Bathroom Blue PVC Hose 3415 has been ranked first in the world's plastic consumption. In the late 1960s, polyethylene replaced polyvinyl chloride. Although PVC plastics ranks second, but the output still accounts for more than a quarter of the total output of plastics.
Before the 1960s, the production of monomer vinyl chloride was basically based on calcium carbide and acetylene. The production of calcium carbide required a lot of electricity and coke, and the cost was high. After the industrialization of ethylene oxychlorination to produce vinyl chloride in the early 1960s, countries turned to cheaper petroleum as raw materials. In addition, because a large part of the raw material of polyvinyl chloride (about 57% by weight) is the by-product of the soda industry, it is not only a rich source of raw materials, but also one of the most important products for the development of the chlor-alkali industry and the balance of chlorine. Therefore, although the proportion of PVC in plastics has declined, it still maintains a relatively high growth rate.

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