Polyethylene Terephthalate (PET, PETE)
PET is a thermoplastic, further classified as a polyester plastic. It can have the lowest heat capacity among the polyester plastics in the database.
The properties of PET include three common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare PET to: polyester plastics (top), all thermoplastics (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
3.5 to 11 GPa 0.51 to 1.6 x 106 psi
Elongation at Break
2.5 to 70 %
Flexural Modulus
8.3 to 14 GPa 1.2 to 2.0 x 106 psi
Impact Strength: Notched Izod
43 to 85 J/m 0.8 to 1.6 ft-lb/in
Tensile Strength: Ultimate (UTS)
60 to 140 MPa 8.7 to 20 x 103 psi
Thermal Properties
Glass Transition Temperature
70 °C 160 °F
Maximum Temperature: Autoignition
410 °C 760 °F
Maximum Temperature: Decomposition
390 °C 730 °F
Maximum Temperature: Mechanical
80 °C 180 °F
Melting Onset (Solidus)
260 °C 490 °F
Specific Heat Capacity
1000 to 1150 J/kg-K 0.24 to 0.27 BTU/lb-°F
Other Material Properties
Density
1.4 to 1.6 g/cm3 86 to 97 lb/ft3
Dielectric Constant (Relative Permittivity) At 1 Hz
3.7
Limiting Oxygen Index (LOI)
21 %
Water Absorption At Saturation
0.24 to 0.5 %
Common Calculations
Stiffness to Weight: Axial
1.2 to 4.4 points
Stiffness to Weight: Bending
32 to 54 points
Strength to Weight: Axial
12 to 27 points
Strength to Weight: Bending
25 to 41 points
Followup Questions
Further Reading
Reinforced Plastics Durability, Geoffrey Pritchard (editor), 1999
SPI Plastics Engineering Handbook of the Society of the Plastics Industry, Inc., 5th ed., Michael L. Berins (editor), 2000
Modern Plastics Handbook, Charles A. Harper (editor), 1999
Plastics Materials, 7th ed., J. A. Brydson, 1999