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Glycol-Modified Polyethylene Terephthalate (PETG, PET-G)

PETG is a thermoplastic, further classified as a polyester plastic. The graph bars on the material properties cards below compare PETG 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

Compressive (Crushing) Strength

55 MPa 8.0 x 103 psi

Elastic (Young's, Tensile) Modulus

2.2 GPa 0.32 x 106 psi

Flexural Modulus

2.1 GPa 0.31 x 106 psi

Flexural Strength

77 MPa 11 x 103 psi

Impact Strength: Notched Izod

77 J/m 1.5 ft-lb/in

Rockwell R Hardness


Shear Strength

62 MPa 9.0 x 103 psi

Tensile Strength: Ultimate (UTS)

53 MPa 7.7 x 103 psi

Thermal Properties

Glass Transition Temperature

81 °C 180 °F

Heat Deflection Temperature At 1.82 MPa (264 psi)

69 °C 160 °F

Heat Deflection Temperature At 455 kPa (66 psi)

73 °C 160 °F

Melting Onset (Solidus)

140 °C 280 °F

Specific Heat Capacity

1200 J/kg-K 0.29 BTU/lb-°F

Thermal Conductivity

0.29 W/m-K 0.17 BTU/h-ft-°F

Thermal Expansion

68 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 Hz


Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

16 kV/mm 0.63 V/mil

Otherwise Unclassified Properties


1.3 g/cm3 79 lb/ft3

Refractive Index


Water Absorption After 24 Hours

0.2 %

Common Calculations

Stiffness to Weight: Axial

1.0 points

Stiffness to Weight: Bending

34 points

Strength to Weight: Axial

12 points

Strength to Weight: Bending

25 points

Thermal Diffusivity

0.19 mm2/s

Thermal Shock Resistance

25 points

Followup Questions

Further Reading

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