Polyphenylene sulphide
If high temperatures, excellent chemical resistance, good mechanical properties, dimensional stability and costefficiency are required, then polyphenylene sulphide (PPS) is often the best technical and economical solution.
Abbreviation
PPS
Molecular formula
C6H4S
CAS no.
25212-74-2
General description
The excellent properties of the high-temperature resistant polymer PPS enable use in numerous industrial and commercial applications. Its dimensional stability, excellent flow properties during processing, low moisture absorption and high chemical resistance make polyphenylene sulphide the material of choice for many applications.
Selected PPS compounds are flame retardant without additives, which extends the range of use of this high-quality material to applications where fire protection is relevant.
Polyphenylene sulphide is widely used in the automotive and electrical and electronic industries, for industrial applications, in aerospace and medical technology as well as the consumer goods industry.
Definition
Linear polyphenylene sulphide is a high-temperature resistant plastic and belongs to the group of thermoplastics. PPS is usually produced by polycondensation of 1,4-dichlorobenzene with sodium sulphide.
The partially crystalline high-temperature polymer features very high thermal stability, strength, stiffness, creep resistance and excellent chemical resistance. PPS compounds reinforced with glass fibres or glass fibre/mineral mixtures are among the high-performance plastics suitable for continuous use at temperatures of up to 240 °C.
The material is highly stable against both conventional and modern fuels. PPS is also inherently flame-retardant. Polyphenylene sulphide conforms to the UL94 V-0 standard. Modified grades achieve category 5VA. The moisture absorption of the partially crystalline polymer is extremely low.
Polyphenylene sulphide has excellent suitability for demanding technical applications and is widely used in the automotive and electronics industries as well as in industrial and chemical processing plants.
Production
Polyphenylene sulphide is produced by polymerisation of specific monomers using a catalyst. In the production of monomers, a distinction is made between the sulphide and oxide processes. Polymerisation involves the combination of aromatic monomer units via sulphur atoms. The polymer produced is then isolated, washed and dried. Depending on the desired processing technique, the PPS polymer is further processed into pellets, powder or fibres.
Properties
PPS compounds are available non-reinforced or reinforced with glass fibre or glass fibre/mineral mixtures. Selected PPS grades have approvals for food and drinking water applications.
Chemical resistance
The chemical resistance of PPS to most solvents and many acids and alkalis is excellent, even at high temperatures. The material is highly resistant to lubricating greases, fuels, methanol, alkalis and water up to 100 °C.
The material is resistant to hydrolysis. However, the material is susceptible to hydrochloric and nitric acid and has limited resistance to non-oxidising acids.
The material exhibits very little moisture absorption and is generally highly impermeable to most liquids and gases.
Processing techniques
Common processing techniques are injection moulding, blow moulding and extrusion.
The material has very good flow properties during processing and is therefore also suitable for complex tool geometries and long, narrow moulded parts. The material can be mechanically processed without any problems.
Due to the low viscosity, it is essential to ensure that the injection mould is tight during injection moulding.
PPS grades for extrusion are mainly used for the production of fibres and monofilaments as well as pipes, rods and sheets.