General Purpose Polystyrene (GPPS)
GPPS is a grade of PS. The graph bars on the material properties cards below compare GPPS to: styrenic 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
90 MPa 13 x 103 psi
Elastic (Young's, Tensile) Modulus
2.9 GPa 0.42 x 106 psi
Elongation at Break
1.8 %
Flexural Modulus
3.2 GPa 0.46 x 106 psi
Flexural Strength
80 MPa 12 x 103 psi
Impact Strength: Notched Izod
19 J/m 0.35 ft-lb/in
Poisson's Ratio
0.4
Rockwell M Hardness
65
Tensile Strength: Ultimate (UTS)
44 MPa 6.3 x 103 psi
Thermal Properties
Glass Transition Temperature
100 °C 210 °F
Heat Deflection Temperature At 1.82 MPa (264 psi)
90 °C 190 °F
Maximum Temperature: Autoignition
360 °C 670 °F
Maximum Temperature: Decomposition
320 °C 610 °F
Maximum Temperature: Mechanical
70 °C 160 °F
Specific Heat Capacity
1250 J/kg-K 0.3 BTU/lb-°F
Thermal Conductivity
0.14 W/m-K 0.081 BTU/h-ft-°F
Thermal Expansion
98 µm/m-K
Vicat Softening Temperature
100 °C 210 °F
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
2.5
Dielectric Strength (Breakdown Potential)
20 kV/mm 0.78 V/mil
Electrical Resistivity Order of Magnitude
15 10x Ω-m
Otherwise Unclassified Properties
Density
1.0 g/cm3 65 lb/ft3
Limiting Oxygen Index (LOI)
18 %
Refractive Index
1.6
Water Absorption After 24 Hours
0.040 %
Common Calculations
Stiffness to Weight: Axial
1.5 points
Stiffness to Weight: Bending
45 points
Strength to Weight: Axial
12 points
Strength to Weight: Bending
26 points
Thermal Diffusivity
0.11 mm2/s
Thermal Shock Resistance
11 points
Followup Questions
Further Reading
ASTM D883: Standard Terminology Relating to Plastics
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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015