PETG vs. Thermoset PI

PETG belongs to the thermoplastics classification, while thermoset PI belongs to the thermoset plastics. There are 17 material properties with values for both materials. Properties with values for just one material (17, in this case) are not shown.

For each property being compared, the top bar is PETG and the bottom bar is thermoset PI.

Glycol-Modified Polyethylene Terephthalate (PETG, PET-G)Thermoset Polyimide (PI)

Metric UnitsUS Customary Units

Mechanical Properties

Compressive (Crushing) Strength, MPa		55
Compressive (Crushing) Strength, MPa		120 to 210

Flexural Modulus, GPa		2.1
Flexural Modulus, GPa		3.1 to 4.8

Flexural Strength, MPa		77
Flexural Strength, MPa		60 to 100

Impact Strength: Notched Izod, J/m		77
Impact Strength: Notched Izod, J/m		21 to 43

Tensile Strength: Ultimate (UTS), MPa		53
Tensile Strength: Ultimate (UTS), MPa		37 to 81

Thermal Properties

Glass Transition Temperature, °C		81
Glass Transition Temperature, °C		360

Heat Deflection Temperature At 1.82 MPa (264 psi), °C		69
Heat Deflection Temperature At 1.82 MPa (264 psi), °C		370

Specific Heat Capacity, J/kg-K		1200
Specific Heat Capacity, J/kg-K		1130

Thermal Conductivity, W/m-K		0.29
Thermal Conductivity, W/m-K		0.29 to 1.7

Thermal Expansion, µm/m-K		68
Thermal Expansion, µm/m-K		38 to 54

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz		2.4
Dielectric Constant (Relative Permittivity) At 1 MHz		3.1

Dielectric Strength (Breakdown Potential), kV/mm		16
Dielectric Strength (Breakdown Potential), kV/mm		20

Otherwise Unclassified Properties

Density, g/cm³		1.3
Density, g/cm³		1.4 to 1.6

Water Absorption After 24 Hours, %		0.2
Water Absorption After 24 Hours, %		0.14 to 0.24

Common Calculations

Strength to Weight: Axial, points		12
Strength to Weight: Axial, points		6.5 to 16

Strength to Weight: Bending, points		25
Strength to Weight: Bending, points		16 to 30

Thermal Diffusivity, mm²/s		0.19
Thermal Diffusivity, mm²/s		0.18 to 0.95