Cellulose Acetate Propionate (CAP)
CAP is a thermoplastic, further classified as a cellulosic plastic. It can have a moderately low tensile strength among the thermoplastics in the database.
The properties of CAP include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare CAP to: cellulosic 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
Elongation at Break
35 to 50 %
Flexural Modulus
1.2 to 1.9 GPa 0.17 to 0.28 x 106 psi
Flexural Strength
29 to 56 MPa 4.2 to 8.1 x 103 psi
Tensile Strength: Ultimate (UTS)
28 to 45 MPa 4.1 to 6.5 x 103 psi
Tensile Strength: Yield (Proof)
22 to 40 MPa 3.2 to 5.8 x 103 psi
Thermal Properties
Glass Transition Temperature
190 °C 370 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
65 to 80 °C 150 to 180 °F
Heat Deflection Temperature At 455 kPa (66 psi)
75 to 90 °C 170 to 190 °F
Specific Heat Capacity
1480 J/kg-K 0.35 BTU/lb-°F
Thermal Conductivity
0.25 W/m-K 0.14 BTU/h-ft-°F
Thermal Expansion
14 µm/m-K
Vicat Softening Temperature
85 to 110 °C 190 to 220 °F
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 MHz
3.6
Dielectric Strength (Breakdown Potential)
15 kV/mm 0.59 V/mil
Electrical Resistivity Order of Magnitude
16 10x Ω-m
Otherwise Unclassified Properties
Density
1.2 g/cm3 75 lb/ft3
Refractive Index
1.5
Water Absorption After 24 Hours
1.4 to 1.7 %
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
9.1 to 22 MJ/m3
Strength to Weight: Axial
6.5 to 10 points
Strength to Weight: Bending
17 to 23 points
Thermal Diffusivity
0.14 mm2/s
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