Menu (ESC)

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


1.4 to 1.6 g/cm3 86 to 97 lb/ft3

Dielectric Constant (Relative Permittivity) At 1 Hz


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