Before PVC can be made into finished products, it always requires conversion into a compound by the incorporation of additives (but not necessarily all of the following) such as heat stabilizers, UV stabilizers, plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants, biocides, blowing agents and smoke suppressors, and, optionally, pigments. The product of the polymerization process is unmodified PVC. The largest single producer of PVC as of 2018 is Shin-Etsu Chemical of Japan, with a global share of around 30%. Producers Ībout half of the world's PVC production capacity is in China, despite the closure of many Chinese PVC plants due to issues complying with environmental regulations and poor capacities of scale. The density is also higher than for these structurally related plastics. The presence of chloride groups gives the polymer very different properties from the structurally related material polyethylene. About 57% of the mass of PVC is chlorine. Some degree of syndiotacticity of the chain gives a few percent crystallinity that is influential on the properties of the material. PVC has mainly an atactic stereochemistry, which means that the relative stereochemistry of the chloride centres are random. The monomers are mainly arranged head-to-tail, meaning that there are chlorides on alternating carbon centres. PVC may be manufactured from either naphtha or ethylene feedstock. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain the suspension. The reaction is exothermic and thus requires cooling. The contents of the reaction vessel are pressurized and continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. VCM and water are introduced into the reactor along with a polymerization initiator and other additives.
Suspension polymerization affords particles with average diameters of 100–180 μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2 μm.
Emulsion polymerization accounts for about 12%, and bulk polymerization accounts for 8%. Ībout 80% of production involves suspension polymerization. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), as shown. Goodrich Company developed a method in 1926 to plasticize PVC by blending it with various additives, including the use of dibutyl phthalate by 1933. In the early 20th century, the Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC in commercial products, but difficulties in processing the rigid, sometimes brittle polymer thwarted their efforts. The polymer appeared as a white solid inside a flask of vinyl chloride that had been left on a shelf sheltered from sunlight for four weeks. PVC was synthesized in 1872 by German chemist Eugen Baumann after extended investigation and experimentation. It is insoluble in alcohol but slightly soluble in tetrahydrofuran. Pure polyvinyl chloride is a white, brittle solid. With cotton or linen, it is used in the production of canvas. In this form, it is also used in plumbing, electrical cable insulation, imitation leather, flooring, signage, phonograph records, inflatable products, and many applications where it replaces rubber.
It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. It is also used in making plastic bottles, non-food packaging, food-covering sheets and plastic cards (such as bank or membership cards). The rigid form of PVC is used in construction for pipe and in profile applications such as doors and windows. PVC comes in two basic forms: rigid (sometimes abbreviated as RPVC) and flexible. About 40 million tons of PVC are produced each year. Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: polyvinyl, or simply vinyl abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene).
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