Polyvinyl Chloride Resins (PVC)
Polyvinyl Chloride (PVC) is one of the most widely produced thermoplastic polymers in the world after polyethylene and polypropylene. Without the additions of plasticizers, PVC is a naturally white, brittle plastic. Its most common use is in the construction industry, but it is also used to manufacture signs, in healthcare applications, and as a fiber for clothing.
PVC is primarily produced as a rigid or unplasticized polymer (RPVC) or as a flexible plastic (uPVC). Flexible, plasticized or regular PVC is softer and more amenable to bending than uPVC due to the addition of plasticizers like phthalates such as diisononyl phthalate or DINP. Flexible PVC is commonly used in construction as insulation on electrical wires or in flooring for homes, hospitals, schools, and other areas where a sterile environment is necessary. Rigid PVC is also used in construction as pipe for plumbing and siding that is commonly called vinyl in the United States. It is also used for bottles, other non-food packaging, and cards (such as credit or membership cards). It is also used imitation leather, signage, phonograph records, inflatable products, and many applications where it is used as a replacement for rubber.
Pure polyvinyl chloride is a white, brittle solid generally delivered as powder or pellets. It is insoluble in alcohol but slightly soluble in tetrahydrofuran.
PVC is manufactured from petroleum. The production process also uses sodium chloride. Recycled PVC is broken down into powder or small chips with the impurities removed. The resulting product is refined to make pure white PVC. It can be recycled approximately seven times. Its lifespan is about 140 years
The essential raw materials for PVC are derived from salt and oil. The electrolysis of salt water produces chlorine, which is combined with ethylene (obtained from oil) to form vinyl chloride monomer (VCM). Molecules of VCM are polymerised to form PVC resin, to which appropriate additives are incorporated to make a customised PVC compound .
- The extraction of salt and hydrocarbon resources
- The production of ethylene and chlorine from these resources
- The combination of chlorine and ethylene to make the vinyl chloride monomer (VCM)
- The polymerisation of VCM to make poly-vinyl-chloride (PVC)
- The blending of PVC polymer with other materials to produce different formulations providing a wide range of physical properties.
- 57% of the molecular weight derived from common salt
- 43% derived from hyrdocarbon feedstocks (increasingly ethylene from sugar crops is also being used for PVC production as an alternative to ethylene from oil or natural gas)
- There are over 50 quadrillion tonnes of salt exist dissolved in the sea, with over 200billion tonnes of salt available underground – reserves of this material are clearly abundant
- Ethylene from oil equates to 0.3% of annual oil usage, but increasingly etheylene from sugar crops is also being used for PVC production
Products and bi-products of PVC manufacture include Chlorine and Caustic Soda, two of perhaps the most important manufacturing “ingredients” not only for PVC manufacture, but many other applications. Chlorine is used in the manufacture of life-saving medication, indeed 85% of all pharmaceuticals. Caustic Soda too has many key, everyday applications, including the following applications: pulp and paper manufacture, soap and surfactant manufacture, detergents and cleaners, aluminia extraction, textiles and in the food industry
Benefits of PVC
PVC has excellent electrical insulation properties, making it ideal for cabling applications. Its good impact strength and weatherproof attributes make it ideal for construction products.
- PVC has extensive European food contact and medical approvals
- PVC is easy to process, long lasting, tough and light
- PVC consumes less primary energy during production than any of the other commodity plastics
- With high clarity and excellent organoleptic properties (no transfer of taint to food) it is equally suited for use in short term applications such as specialised packaging.
- PVC has a relatively small carbon footrpint, the below infographic indicates the CO2 impact PVC compared to other products
- PVC windows help to cut energy bills and PVC-based windows account for most BFRC ‘A’ Rated Energy Efficient Windows
- PVC is fully recyclable. Due to its properties it reprocesses well and can be recycled into second (or third life) applications with ease.