Polystyrene - PS

Polystyrene homopolymer, known as “crystal" polystyrene in the trade, is an amorphous, colorless, and transparent commodity thermoplastic. It is rigid, brittle, relatively hard and has excellent gamma radiation resistance, good electrical properties but has poor chemical and UV resistance. It can also be radiation sterilized.

When modified by incorporating elastomers, polystyrene homopolymer turns into (high) impact polystyrene or HIPS, which is usually opaque. As a result, a wide variety of commercial polystyrene grades are available.

Polymer Type



Advantages of Polystyrene include:

  • Cheap, rigid, transparent, easy to mould and good dimensional stability. 
  • Good electrical properties, low dielectric loss. 
  • Excellent resistance to gamma radiation.


Disadvantages of Polystyrene include:

  • Brittle, poor chemical resistance especially to organics. 
  • Susceptible to UV degradation. 
  • Flammable.


Applications include toys, light diffusers, beakers, cutlery, general household appliances, video/audio cassette cases, electronic housings, refrigerator liners, housewares, containers, glazing, packaging and for HIPS.

Structural foam polystyrene moldings are used for business machine housings, tools, cases and boxes. Expanded polystyrene beads are used for packaging and cushioning. Foamed polystyrene is used for food trays, dishes, and egg boxes.

Typical Properties

Property Value
Density (g/cm3) 1.07
Surface Hardness RM80
Tensile Strength (MPa) 34
Flexural Modulus (GPa) 3
Notched Izod (kJ/m) 0.02
Linear Expansion (/°C x 10-5) 7
Elongation at Break (%) 1.6
Strain at Yield (%) 1.4
Max. Operating Temp. (°C) 50
Water Absorption (%) 0.05
Oxygen Index (%) 18
Flammability UL94 HB
Volume Resistivity (log ohm.cm) 16
Dielectric Strength (MV/m) 20
Dissipation Factor 1 kHz 0.0002
Dielectric Constant 1 kHz 2.6
HDT @ 0.45 MPa (°C) 90
HDT @ 1.80 MPa (°C) 80
Material. Drying hrs @ (°C) 2 @ 70
Melting Temp. Range (°C) 200 - 250
Mould Shrinkage (%) 0.5
Mould Temp. Range (°C) 20 - 50

Source : Abstracted from Plascams

For more information on Plascams please visit RAPRA Technology Ltd.



  1. Baqir Hakeem Baqir Hakeem Iraq says:

    Polystyrene is transparent.why?

  2. Malik Muhammad Asif Malik Muhammad Asif Australia says:

    what is the Youngs modulus of PS used in making "big red cups" ?

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Your comment type