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Polysulfone (PSU) forms, together with polyethersulfone (PES) and polyetherimide (PEI), a trio of amorphous, aromatic high-temperature polymers. They are difficult to deform when cold, they are excellently resistant to numerous chemicals and they are inherently flame-extinguishing.

PSU is non-toxic and resistant to hydrolysis, which explains why it is used frequently in warm water pumps and meters and products frequently sterilised using steam (as in hospitals). PSU is also a usable in a variety of applications in temperature-loaded electronic and electrical products.

PSU’s moisture absorption is low, i.e. 0.3% at 23°C/50% RH and 0.8% when saturated. The glass transition temperature is 190°C, enabling continuous usage temperatures up to 170°C. Exposure to UV radiation causes rapid yellowing, but this is avoidable by adding special carbon black particles or by applying a top coating. To a high degree PSU is resistant to watery mineral acids and alkaline and saline solutions, detergents and machine oils. The material swells, dissolves or exhibits hairline fractures after contact with polar organic solvents like ketones, esters and halogenated or aromatic hydrocarbons.

PSU possesses excellent cold deformation properties, even up to temperatures of 170°C, and these can be improved still further by using glass fibre or carbon fibre. PSU is largely insensitive to microwave radiation, enabling its wide application in the electronic industry and in appliances like microwave ovens.