Polystyrene Cross - Linked - Properties and Applications - Supplier Data by Goodfellow

Polystyrene homopolymer is an amorphous thermoplastic that is rigid, brittle and relatively hard. It has excellent gamma radiation resistance, good electrical properties, and can be radiation sterilized but has poor chemical and UV resistance.

When modified by incorporating elastomers, polystyrene homopolymer becomes (high) impact polystyrene (HIPS), which is generally opaque. Therefore, a large number of polystyrene grades are available on the market.

Background

A cross-linked polystyrene copolymer which is rigid, transparent and colourless with outstanding electrical properties, including low dielectric losses up to very high frequencies, and very high radiation resistance. Cross-linked polystyrene copolymer has good dimensional stability, is easily machined and can be polished to a high optical quality.

Compared to normal polystyrene, it is harder and somewhat more temperature resistant.

Applications

Applications of polystyrene include light diffusers, glazing, packaging, containers, and housewares and for HIPs, cassette cases, take-out containers, cups, and casings. It is also extensively used as structural foam and expanded into beads for cushioning and packaging.

Cross-linked polystyrene copolymer is used primarily as a dielectric material in a wide range of components together with lenses, observation windows, x-ray equipment and radiation detectors.

Key Properties

The key properties of cross-linked polystyrene copolymer are tabulated below.

Table 1. Key properties

Chemical Resistance
Acids - concentrated Fair
Acids - dilute Good
Alcohols Good
Alkalis Fair
Aromatic hydrocarbons Poor
Greases and Oils Fair
Halogens Poor
Ketones Poor
Electrical Properties
Dielectric constant @ 1 MHz 2.5
Dielectric strength ( kV.mm-1 ) 27-47
Dissipation factor @ 1 MHz 0.0002
Surface resistivity ( Ohm/sq ) >1015
Volume resistivity ( Ohm.cm ) >1015
Mechanical Properties
Abrasive resistance - ASTM D1044 ( mg/1000 cycles ) 60-100
Elongation at break ( % ) 3-5
Hardness - Rockwell R110-120
Tensile modulus ( GPa ) 1.65
Tensile strength ( MPa ) 55-70
Physical Properties
Density ( g.cm-3 ) 1.05
Flammability Combustible
Radiation resistance - Alpha Good
Radiation resistance - Beta Good
Radiation resistance - Gamma Good
Radiation resistance - X-ray Good
Refractive index 1.59
Resistance to Ultra-violet Good
Water absorption - over 24 hours ( % ) 0.02-0.03
Thermal Properties
Coefficient of thermal expansion ( x10-6 K-1 ) 90
Thermal conductivity ( W.m-1.K-1 ) 0.17 @ 23
Upper working temperature ( °C ) 93

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