# 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). The length of each bar shows the given value as a % of the largest value in the relevant set.

## Mechanical Properties

Elastic (Young's, Tensile) Modulus

1.9 *GPa* 0.28 *x 10 ^{6} psi*

Elongation at Break

40 *%*

Flexural Strength

62 *MPa* 9.0 *x 10 ^{3} psi*

Impact Strength: Notched Izod

45 *J/m* 0.85 *ft-lb/in*

Poisson's Ratio

0.41

Tensile Strength: Ultimate (UTS)

32 *MPa* 4.6 *x 10 ^{3} 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 *10 ^{x} Ω-m*

## Otherwise Unclassified Properties

Density

1.0 *g/cm ^{3}* 65

*lb/ft*

^{3}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 *m ^{2}/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