Polysulfone (abbreviation PSU) is an amorphous plastic which, as polysulfone, is counted among the high-temperature-resistant high-performance thermoplastics. It is an amorphous, transparent and pale yellow high-performance thermoplastic, similar to PES. PSU is characterised by very good radiation resistance, good chemical and hydrolysis resistance and a low content of ionic impurities. Temperature resistance, on the other hand, is slightly lower than PES, but offers lower moisture absorption than PES, although drying is still necessary before thermoforming. It has poor fatigue properties and is susceptible to environmental stress cracking, but has good long-term heat ageing resistance. Chemical resistance is also very similar to PES.
The ignition temperature with extraneous flame of polysulfone is 475 °C. During combustion, mainly CO2, SO2 and H2O are formed and, with a low oxygen supply, other gases. Flame propagation speed and smoke development are low. For building materials, PSU has been classified in building material class B2. The oxygen index according to ISO 4589 is 32 %. Unreinforced PSU has been classified as V1 according to UL94, reinforced PSU with a thickness of 3.2 mm achieves V0.
Application of PSU film
Polysulfone is used in electrical engineering, electronics, automotive and mechanical engineering, for household appliances and in medical technology when high heat resistance combined with transparency is required. It is also used dyed and/or reinforced with up to 30 % glass fibres. With glass fibres, elasticity moduli of up to 10,000 MPa are achieved.