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Usage

Uses

Used in Packaging Industry:
Poly(ethylene terephthalate) is used as a packaging material for food and beverages, as well as for pharmaceuticals and cosmetics. It is favored for its lightweight, durability, and recyclability, making it an environmentally friendly choice.
Used in Textile Industry:
PET is used as a textile material for the production of fibers, such as polyester. The process involves extruding the molten polymer through spinnerets into air at normal temperature, followed by drawing the filaments at a temperature above the glass-transition temperature to induce molecular orientation and crystallinity. The filaments are then heated at about 200°C under tension to give a dimensionally-stable material of maximum crystallinity.
Used in Plastics Industry:
Poly(ethylene terephthalate) is used as an engineering material in the production of various plastic items, such as automotive parts, electrical components, and domestic appliance assemblies. Its excellent resistance to acids and alkalis, as well as its ability to soften at high temperatures, make it a suitable choice for these applications.
Used in Film Production:
The manufacture of poly(ethylene terephthalate) film closely resembles that of fiber production, involving extrusion, orientation, and stabilization. PET films are used in a variety of applications, including photographic film, magnetic recording tape, and architectural and automotive applications due to their excellent properties.

Preparation

It is prepared from 1,4-butanediol and terephthalic acid or dimethylterephthalate by processes which are essentially the same as those used for poly(ethylene terephthalate) and described in the preceding section. Due to the longer sequence of methylene groups, the polymer chains are more flexible and less polar than in poly(ethylene terephthalate). This results in a lower crystalline melting point (225°C) and glass-transition point (22-43°C). The low glass-transition temperature facilitates rapid crystallization in the mould and most poly(butylene terephthalate) is processed by injection moulding.