Poly (vinyl chloride)

Poly(vinyl chloride) (PVC) is a widely used synthetic plastic polymer. After polyethylene and polypropylene, PVC is the third most widely produced synthetic plastic polymer. It comes in two basic forms: rigid and flexible. The rigid form of PVC is used in construction for pipe and in profile applications such as doors and windows. It is also used in making bottles, non-food packaging, and cards (such as bank or membership cards). The flexible PVC, also known as plasticized PVC, is softer and more flexible due to the addition of plasticizers, making it suitable for applications in plumbing, electrical cable insulation, imitation leather, signage, inflatable products, and many applications where it replaces rubber.

Production

PVC is produced by polymerization of the vinyl chloride monomer (VCM). The majority of the production involves suspension polymerization. Emulsion and bulk (mass) polymerization methods are also used but to a lesser extent. The process starts with the production of the monomer, which is then converted into PVC by polymerization. The polymerization process involves the use of initiators and other additives to control the molecular weight of the PVC and the conversion rate of the monomer to polymer.

Properties

PVC has several desirable properties that make it a versatile material. It is resistant to oxidation and degradation, making it suitable for long-term applications in harsh environments. PVC is also resistant to chemicals, water, and fire. Its electrical insulation properties make it valuable in the electrical and electronics industry. However, PVC is also known for being hard and not very flexible, although this can be adjusted by adding plasticizers, which make it softer and more flexible but can also affect its physical properties and durability.

Applications

The versatility of PVC allows it to be used in a wide range of applications. In construction, it is used for pipes, window frames, and doors. In healthcare, it is used for blood bags and tubing. PVC's chemical resistance makes it suitable for use in chemical processing industries. It is also used in everyday items like clothing, footwear, packaging, and toys.

Environmental and Health Concerns

The production and disposal of PVC have raised environmental and health concerns. The manufacture of PVC releases toxic chlorine gas and dioxins, which pose risks to the environment and human health. The disposal of PVC products can also be problematic, as they are not easily biodegradable. Incineration of PVC waste can release toxic fumes, and landfilling can lead to chemical leaching. Efforts are being made to recycle PVC, but the process is complex and not widely implemented.

Regulation and Alternatives

Due to the environmental and health concerns associated with PVC, there has been a push towards finding and using alternative materials. Regulations have been put in place in some countries to limit the use of PVC in certain applications, especially in contact with food and in children's toys. Alternatives to PVC include other plastics like polyethylene (PE) and polypropylene (PP), which do not contain chlorine and have a lower environmental impact during production and disposal.