Polyvinyl chloride (PVC) is actually a versatile and resource efficient thermoplastic together with the widest range of applications of any of the plastics family making it beneficial in virtually all areas of human activity.
Without additives pvc compound would stop being a particularly useful substance, but its compatibility with a wide array of additives – to soften it, colour it, ensure it is more processable or longer lasting, results in a broad range of potential applications from car underbody seals and versatile roof membranes to pipes and window profiles. PVC products can be rigid or flexible, opaque or transparent, coloured and insulating or conducting. There is not just one PVC but a whole family of products tailor-created to suit the needs of each application. Unlike many other thermoplastics, nearly all PVC applications use a lifetime which is between 10 and 100 years. This calls for proven durability and stabilisers play a crucial part in achieving such performance. All polymers require stabilisers of just one sort or other; PVC is not any different in this respect.
Before PVC can be done into products, it has to be combined with a range of special additives. The essential additives for all those PVC materials are stabilisers and lubricants; in the case of soft pvc granule, plasticisers can also be incorporated. Other additives which is often used include fillers, processing aids, impact modifiers and pigments. Additives pvcppellet influence or determine the mechanical properties, light and thermal stability, colour, clarity and electrical properties from the product. After the additives are already selected, they can be combined with the polymer in a process called compounding. One method uses an intensive high-speed mixer that intimately blends each of the ingredients. The end result is actually a powder, known as the ‘dry blend’, which happens to be then fed in to the processing equipment.
The second way is to blend the components in either a minimal or high-speed mixer and after that transfer the powder into a melt compounder. This could be either a compounding extruder, or another special equipment to make transparent pvc compound. These develop a melt which, when cool, is cut into granules ready for processing. In the specialised process, liquid compounds called plastisols, are designed as dispersions of very fine PVC polymer particles in liquid organic media. PVC compounds are manufactured into products using a variety of processing methods including extrusion, injection moulding, blow moulding, calendering, spreading and coating.