PPS, as another of the crystalline, high temperature resistant polymers, exhibits very good chemical and flame resistance along with high strength and good electrical insulation properties both of which are maintained at high temperatures. However, PPS is a brittle material and is often filled with a variety of materials; glass fibres to improve strength and toughness, carbon fibres to improve toughness and tribiological properties, PTFE and/or silicone oil to reduce friction and wear for bearing applications, carbon fibres to improve toughness, strength, tribiological properties and to reduce the wear factor and galling associated with glass fibre reinforcement. Some PPS composite grades meet severe FAA Fire Safety Regulations due to their flame resistance, high flash and self-ignition temperatures, low smoke density and low toxicity of smoke gases. Unfilled PPS meeting FDA regulations has no known solvents at temperatures below 400°F and is slowly affected by concentrated oxidizing acids and amines and halogens above 400°F. PPS machines well due to its hardness, stiffness, thermal resistance and dimensional stability with any machining lubricant being suitable. Polar adhesives must be used for bonding.