WHAT IS PET?

PET is an acronym for polyethylene terephthalate, which is a long-chain polymer belonging to the generic family of polyesters [1]. PET is formed from the intermediates, terephthalic acid (TPA) and ethylene glycol (EG), which are both derived from oil feedstock. There are other polyesters based on different intermediates but all are formed by a polymerization reaction between an acid and an alcohol.

PET, in its purest form, is an amorphous glass-like material. Under the influence of direct modifying additives it develops crystallinity. Also, crystallinity can be developed by heat treatment of the polymer melt.

Originally patented and exploited by DuPont during the search for new fibre-forming polymers [2,3], polyester fiber applications have developed to such an extent that PET represents over 50% of world synthetic fiber manufacture [4]. PET is used alone or blended with cotton or wool to impart better wash/wear and crease resistant properties to textiles.

In the late 1950s PET was developed as a film. It was first used for video, photographic and X-ray films in addition to uses in flexible packaging. Later PET was modified for use in injection moulded and extruded articles, primarily reinforced with glass fiber. In the early 1970s PET was stretched by blow moulding techniques which produced the first oriented three dimensional structures initiating the rapid exploitation of PET as lightweight, tough, unbreakable bottles .