PVC – a thermoplastic
Plastics, or synthetic resins, are classified into two broad categories: thermosetting resins and thermoplastic resins. PVC falls into the thermoplastic resins, which also include polyethylene (PE), polystyrene (PS) and polypropylene (PP). These hard plastics can be softened again through heating. On the other hand, thermosetting resins, that include phenolic resin and melamine resin, are thermally hardened and never become soft again.
PVC is made of 57% chlorine and 43% carbon (derived predominantly from oil or gas via ethylene). PVC production uses less unrenewable resources - oil or natural gas - than other plastics, and it can therefore be regarded as a resource-saving plastic. In contrast, the production of plastics such as PE, PP, PET and PS is completely dependent on oil or gas.
Thermoplastic resins are often supplied in the form of pelletised material (compounds) with additives (antioxidants, etc.) already blended into it. However, PVC resin can also be supplied in powder form, which it often is, as this powder form is resistant to oxidation and degradation, allowing for a long storage period. Various additives and pigments are then added to the powder during the processing stage, producing a blend that is converted into various PVC products.
PVC is predominantly known as ‘Vinyl’ in North America, and while in Europe this is sometimes the case, ‘Vinyl’ usually refers to certain specific flexible applications, such as flooring, decorative sheets, musical records and artificial leather.