PET, a unique plastic belonging to the family of polyesters

PET is a short name for a unique plastic belonging to the family of polyesters, the word is made up from ‘poly-‘ , the Greek word for many and ‘-esters’ which are compounds formed by reaction of alcohols with acids via a chemical bonding known as an ester linkage. PET polyester is formed from the alcohol – ethylene glycol [EG] – and the acid – terephthalic acid [TPA],] – and its chemical name is – Polyethylene terephthalate or PET.

The raw materials for PET are derived from crude oil. After refining and separating the ‘crude’ into a variety of petroleum products, the two PET feedstocks or monomers are eventually obtained, purified, and mixed together in a large sealed, ‘cooking pot’ type of vessel and heated up to 300°C in the presence of a catalyst. Each intermediate has two identical points for reaction and is therefore capable of forming chains by linking several single molecules together and forming a polymer where the monomers are bonded by ester linkages.

Benefits of PET

Because PET is easily processed by or injection and blow moulding as well as extrusion when in the molten state, it can be tailored to almost any packaging requirement. Typical applications of PET include:

  • Bottles for beverages such as soft drinks, fruit juices, mineral waters. It is especially suitable for carbonated drinks, cooking and salad oils, sauces and dressings and detergents.
  • Wide mouth jars and tubs for jams, preserves, fruits & dried foods.
  • Trays for pre-cooked meals that can be re-heated in either microwave or conventional ovens. Pasta dishes, meats and vegetables.
  • Foils for ‘boil-in-the-bag’ pre-cooked meals, snack foods, nuts, sweets, long life confectionery.
  • Other PET products with an extra oxygen barrier are ideal for containing beer, vacuum packed dairy products e.g., cheese, processed meats, ‘Bag in Box’ wines, condiments, coffee, cakes, syrups.

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