Polyphenylene sulphide (PPS) is a high-temperature semi-crystalline thermoplastic offering outstanding chemical resistance, inherent flame retardance, very low moisture absorption, and excellent dimensional stability under load. Continuous service runs to roughly 425°F (218°C), and no known solvent dissolves it below about 390°F (200°C). Moss Seal machines PPS in glass-filled and carbon-filled grades for back-up rings, anti-extrusion components, valve seats, pump components, and electrical insulating parts in chemically aggressive service. It sits between PTFE and PEEK in both capability and cost, offering higher strength and creep resistance than PTFE with better chemical resistance than most other engineering polymers at a lower price than PEEK.