PVC – Polyvinylchlorid

(C2H3Cl)n

Polyvinyl chloride (PVC) is the third-most widely produced plastic, after polyethylene and polypropylene. PVC is used in the building and construction industry,consumer goods and packaging. At global level, demand for PVC exceeds 35 million tons per year and it is in constant growth.

PVC is produced by polymerization of vinyl chloride monomer (VCM). The main polymerization methods include suspension, emulsion, and bulk (mass) methods. About 80% of production involves suspension polymerization. First, the raw material VCM is pressurized and liquefied, and then fed into the polymerization reactor, which contains water and suspending agents in advance. Next, the initiator is fed into the reactor, and PVC is produced under a few bars at 40 – 60°C. The role of water is to remove and control the heat given off in the polymerization process. PVC forms as tiny particles which grow and when they reach a desired size the reaction is stopped and any unreacted vinyl chloride is distilled off and re-used. The PVC is separated off and dried to form a white powder also known as PVC resin (see flow diagram).
Emulsion polymerization produces finer resin grades having much smaller particles, which are required by certain applications.