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
120
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
2.6
Dielectric Constant (Relative Permittivity) At 1 MHz
2.4
Dielectric Strength (Breakdown Potential)
16 kV/mm 0.63 V/mil
Otherwise Unclassified Properties
Density
1.3 g/cm3 79 lb/ft3
Refractive Index
1.6
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