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High Impact Polystyrene (HIPS)

HIPS is a grade of PS. The graph bars on the material properties cards below compare HIPS 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

Elastic (Young's, Tensile) Modulus

1.9 GPa 0.28 x 106 psi

Elongation at Break

40 %

Flexural Strength

62 MPa 9.0 x 103 psi

Impact Strength: Notched Izod

45 J/m 0.85 ft-lb/in

Poisson's Ratio


Tensile Strength: Ultimate (UTS)

32 MPa 4.6 x 103 psi

Thermal Properties

Glass Transition Temperature

100 °C 210 °F

Specific Heat Capacity

1400 J/kg-K 0.33 BTU/lb-°F

Thermal Conductivity

0.22 W/m-K 0.13 BTU/h-ft-°F

Thermal Expansion

80 µm/m-K

Vicat Softening Temperature

110 °C 220 °F

Electrical Properties

Dielectric Strength (Breakdown Potential)

18 kV/mm 0.7 V/mil

Electrical Resistivity Order of Magnitude

14 10x Ω-m

Otherwise Unclassified Properties


1.0 g/cm3 65 lb/ft3

Limiting Oxygen Index (LOI)

18 %

Water Absorption After 24 Hours

0.080 %

Common Calculations

Stiffness to Weight: Axial

1.0 points

Stiffness to Weight: Bending

40 points

Strength to Weight: Axial

8.5 points

Strength to Weight: Bending

22 points

Thermal Diffusivity

0.15 m2/s

Thermal Shock Resistance

15 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