Polyvinylchloride (PVC) - Essay Example

Polyvinylchloride (PVC) Polyvinylchloride (PVC) was discovered accidentally in the 19th C and has since been modified to have many industrial applications. It is synthetic resin which is prepared through vinyl chloride polymerization. In terms of usage in the plastic arena, it is only exceeded by polyethylene both in domestic and industrial applications. Basically, PVC is classified into broad categories which are thermoplastic and thermosetting resins. PVC is linear in structure which comes about through head to tail addition of molecules to a polymer chain.

These monomer molecules are basically -CH2 molecules which alternate with -CHCl2 units. PVC is highly unstable and therefore it requires stabilization which can be done in several ways. One of the common ways is prevention of dehydrochlorination. This process involves the addition of other compounds like metal oxides in order to stop or slow dehydroclorination. Most of the commercially available PVC is understood to be anamorphous glass like polymer that has crystalline structure. These crystallites are made up of few monomers that are arranged syndiotactically.

As such, the appearance appears to be flowing grains that has primary aggregates embedded in them. It is often claimed that there are sub-primary particles embedded in the flowing grains but this has remained controversial. The PVC’s phase structure combines with several compounds such as chlorinated polyethylene (CPE), ethylene-vinylacetate copolymer (EVA) and acrylo-nitrile-butadiene rubber (NBR). This phase is predicated upon compatibility as well as process temperature and blending during mechanical blending.

An increase of the temperature during mechanical processing of PVC to levels higher than the critical levels recommended for first degree particle fusion leads to shift. The shift leads to an inversion whereby there is a higher rubber content with 30% being non convertible. BibliographyWilkes CE, Summers JW, Daniels, CA and Berard, MT 2005, Pvc Handbook, Hanser Verlag, London.