Polyethylene terephtalate

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PET
Density 1370 kg/m3
Young modulus(E) 2800–3100 MPa
Tensile strengtht) 55–75 MPa
Elongation @ break 50–150%
notch test 3.6 kJ/m2
Glass temperature 75 °C
melting point 260 °C
Vicat B 170 °C
Thermal conductivity 0.24 W/m.K
linear expansion coefficient (α) 7×10−5/K
Specific heat (c) 1.0 kJ/kg.K
Water absorption (ASTM) 0.16
Price 0.5–1.25 €/kg
source: A.K. van der Vegt & L.E. Govaert, Polymeren, van keten tot kunstof, ISBN 90-407-2388-5

Polyethylene terephthalate (aka PET, PETE or the obsolete PETP or PET-P) is a thermoplastic polymer resin of the polyester family. The chemical industry makes it. It is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination with glass fiber. It is one of the most important raw materials used in man-made fibers. It is also used as the dielectric in multi-purpose capacitors (K73-16 series).

Depending on its processing and thermal history, it may exist both as an amorphous (transparent) and as a semi-crystalline (opaque and white) material. Its monomer can be synthesized by the esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct or the transesterification reaction between ethylene glycol and dimethyl terephthalate with methanol as a byproduct. Polymerization is through a polycondensation reaction of the monomers (done immediately after esterification/transesterification) with ethylene glycol as the byproduct (the ethylene glycol is recycled in production).

The majority of the world's PET production is for man-made fibers (in excess of 60%) with bottle-making accounting for around 30% of global demand. In discussing cloth uses, PET is generally referred to as simply "polyester" while "PET" is used most often to refer to packaging applications.

Chemical structure of polyethylene terephthalate