General properties of polysulphones

The differences between the main types of polysulphone are quite small. The polyethersulphones (Type III in Table 21.3) have markedly better creep resistance at elevated temperatures, e.g. 150°C, significantly higher heat distortion temperatures and marginally superior room temperature meehanical properties than the Type II materials. They also exhibit higher water absotption, dielectric constant and specific gravity. 

This difference should be borne in mind when comparing relative costs of the polymers. 

Glass-fibre-filled polysulphones are also available. These show significantly increased creep resistance and lower coefficients of thermal expansion (Table 21.4). 

When processing polysulphones there are four main points to bear in mind  

For extrusion and blow moulding the polysulphones used are of higher molecular weight. Melt temperatures for blow moulding are of the order of 300-360°C with mould temperatures about 70—95°C. 

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The range of blends now available comprises a broad spectrum of materials superior in many respects, particularly heat deformation resistance, to the general purpose thermoplastics but at a lower price than the more heat-resistant materials such as the polycarbonates, polyphenylene sulphides and polysulphones. At the present time the materials that come closest to them in properties are the ABS/ polycarbonate blends. Some typical properties are given in Table 21.1. 

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