CAP vs. Thermoset PI

CAP 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 (12, in this case) are not shown.

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

Cellulose Acetate Propionate (CAP)Thermoset Polyimide (PI)

Metric UnitsUS Customary Units

Mechanical Properties

Elongation at Break, %		35 to 50
Elongation at Break, %		2.0 to 5.9

Flexural Modulus, GPa		1.2 to 1.9
Flexural Modulus, GPa		3.1 to 4.8

Flexural Strength, MPa		29 to 56
Flexural Strength, MPa		60 to 100

Tensile Strength: Ultimate (UTS), MPa		28 to 45
Tensile Strength: Ultimate (UTS), MPa		37 to 81

Thermal Properties

Glass Transition Temperature, °C		190
Glass Transition Temperature, °C		360

Heat Deflection Temperature At 1.82 MPa (264 psi), °C		65 to 80
Heat Deflection Temperature At 1.82 MPa (264 psi), °C		370

Specific Heat Capacity, J/kg-K		1480
Specific Heat Capacity, J/kg-K		1130

Thermal Conductivity, W/m-K		0.25
Thermal Conductivity, W/m-K		0.29 to 1.7

Thermal Expansion, µm/m-K		14
Thermal Expansion, µm/m-K		38 to 54

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz		3.6
Dielectric Constant (Relative Permittivity) At 1 MHz		3.1

Dielectric Strength (Breakdown Potential), kV/mm		15
Dielectric Strength (Breakdown Potential), kV/mm		20

Electrical Resistivity Order of Magnitude, 10^x Ω-m		16
Electrical Resistivity Order of Magnitude, 10^x Ω-m		15

Otherwise Unclassified Properties

Density, g/cm³		1.2
Density, g/cm³		1.4 to 1.6

Water Absorption After 24 Hours, %		1.4 to 1.7
Water Absorption After 24 Hours, %		0.14 to 0.24

Common Calculations

Strength to Weight: Axial, points		6.5 to 10
Strength to Weight: Axial, points		6.5 to 16

Strength to Weight: Bending, points		17 to 23
Strength to Weight: Bending, points		16 to 30

Thermal Diffusivity, mm²/s		0.14
Thermal Diffusivity, mm²/s		0.18 to 0.95