CAP vs. PEEK

Both CAP and PEEK are thermoplastics. There are 15 material properties with values for both materials. Properties with values for just one material (21, in this case) are not shown.

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

Cellulose Acetate Propionate (CAP)Polyetheretherketone (PEEK)

Metric UnitsUS Customary Units

Mechanical Properties

Elongation at Break, %		35 to 50
Elongation at Break, %		1.6 to 43

Flexural Modulus, GPa		1.2 to 1.9
Flexural Modulus, GPa		3.8 to 19

Flexural Strength, MPa		29 to 56
Flexural Strength, MPa		150 to 330

Tensile Strength: Ultimate (UTS), MPa		28 to 45
Tensile Strength: Ultimate (UTS), MPa		97 to 200

Thermal Properties

Glass Transition Temperature, °C		190
Glass Transition Temperature, °C		240

Heat Deflection Temperature At 1.82 MPa (264 psi), °C		65 to 80
Heat Deflection Temperature At 1.82 MPa (264 psi), °C		160 to 300

Specific Heat Capacity, J/kg-K		1480
Specific Heat Capacity, J/kg-K		1390 to 1700

Thermal Conductivity, W/m-K		0.25
Thermal Conductivity, W/m-K		0.25 to 0.93

Thermal Expansion, µm/m-K		14
Thermal Expansion, µm/m-K		15 to 52

Electrical Properties

Electrical Resistivity Order of Magnitude, 10^x Ω-m		16
Electrical Resistivity Order of Magnitude, 10^x Ω-m		3.0 to 14

Otherwise Unclassified Properties

Density, g/cm³		1.2
Density, g/cm³		1.3 to 1.5

Water Absorption After 24 Hours, %		1.4 to 1.7
Water Absorption After 24 Hours, %		0.060 to 0.3

Common Calculations

Strength to Weight: Axial, points		6.5 to 10
Strength to Weight: Axial, points		20 to 41

Strength to Weight: Bending, points		17 to 23
Strength to Weight: Bending, points		36 to 55

Thermal Diffusivity, mm²/s		0.14
Thermal Diffusivity, mm²/s		0.1 to 0.51