The material. The name polyester derives from a combination of Polymerization and esterification. Saturated polyesters are thermoplastic; examples are PET and PBT, which have good mechanical properties to temperatures as high as 175°C. PET is crystal clear and impervious to water and CO2, but a little oxygen does get through. It is tough, strong, and easy to shape, join, and sterilize, allowing reuse. Unsaturated polyesters are thermosets; they are used as the matrix material in glass fiber/polyester composites.
Composition
(CO-(C6H4)-CO-O-(CH2)2-O)n
|
General properties |
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|
Density |
1290 |
– 1400 |
kg/m3 |
|
Price |
*1.63 |
– 1.79 |
USD/kg |
|
Mechanical properties Young’s modulus |
2.76 |
– 4.14 |
GPa |
|
Yield strength (elastic limit) |
56.5 |
– 62.3 |
MPa |
|
Tensile strength |
48.3 |
– 72.4 |
MPa |
|
Compressive strength |
62.2 |
– 68.5 |
MPa |
|
Elongation |
30 |
– 300 |
% |
|
Hardness—Vickers |
17 |
– 18.7 |
HV |
|
Fatigue strength at 107 cycles |
*19.3 |
– 29 |
MPa |
|
Fracture toughness |
4.5 |
– 5.5 |
MPa. m1/2 |
|
Thermal properties Melting point |
212 |
– 265 |
°C |
|
Glass temperature |
67.9 |
– 79.9 |
°C |
|
Maximum service temperature |
66.9 |
– 86.9 |
°C |
|
Thermal conductor or insulator? |
Good insulator |
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|
Thermal conductivity |
0.138 |
– 0.151 |
W/m. K |
|
Specific heat capacity |
*1420 |
– 1470 |
J/kg. K |
|
Thermal expansion coefficient |
115 |
– 119 |
p, strain/°C |
|
Electrical properties Electrical conductor or insulator? |
Good insulator |
|
|
Electrical resistivity |
3.3 X 1020 – |
3.0 X 1021 pohm. cm |
|
Dielectric constant |
3.5 – |
3.7 |
|
Dissipation factor |
*0.003 – |
0.007 |
|
Dielectric strength |
16.5 – |
21.7 106 V/m |
PET drinks containers, pressurized and unpressurized.
|
Ecoproperties: material |
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|
Annual world production |
9 X 106 |
– 9.2 X 106 |
tonne/yr |
|
Reserves |
*2.5 X 108 |
– 2.6 X 108 |
tonne |
|
Embodied energy, primary production |
79.6 |
– 88 |
MJ/kg |
|
CO2 footprint, primary production |
2.21 |
– 2.45 |
kg/kg |
|
Water usage |
*14.7 |
– 44.2 |
l/kg |
|
Eco-indicator |
360 |
– 400 |
millipoints/kg |
|
Ecoproperties: processing |
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|
Polymer molding energy |
*9.36 |
– 10.3 |
MJ/kg |
|
Polymer molding CO2 |
*0.749 |
– 0.826 |
kg/kg |
|
Polymer extrusion energy |
*3.63 |
– 4 |
MJ/kg |
|
Polymer extrusion CO2 |
*0.29 |
– 0.32 |
kg/kg |
|
Recycling |
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|
Embodied energy, recycling |
33.4 |
– 37 |
MJ/kg |
|
CO2 footprint, recycling |
0.928 |
– 1.03 |
kg/kg |
|
Recycle fraction in current supply Recycle mark |
20 A, .ъ PET |
– 22 |
% |
Typical uses. Electrical fittings and connectors; blow molded bottles; packaging film; film; photographic and X-ray film; audio/visual tapes; industrial strapping; capacitor film; drawing office transparencies; fibers. Decorative film, metallized balloons, photography tape, videotape, carbonated drink containers, ovenproof cookware, windsurfing sails, credit cards.
