Modified polyphenylene oxide materials are actually blends of PPO and polystyrene. Different combinations of each, along with possible additive packages, make it possible to produce materials with a wide range of physical and mechanical properties, heat resistance, and flame retardancy. Compounds are available with heat distortion temperatures from 170 to 460 degrees F (77 to 238 degrees C) and with a flammability ranges from UL94HB to V-0.
Because of the water-resistant nature of the two major resin components, most polyphenylene oxide alloys have low moisture absorption levels, giving them good electrical properties over a wide range of humidity and temperature ranges. The materials sport good chemical resistance, though softening and cracking can occur with exposure to some organic chemicals.
PPO blends show increased stiffness with the addition of glass and carbon fibers. Improved strength and flame retardancy, along with reduced mold shrinkage, can be gained with the addition of other additives. Uses of these blends include thermal housing, bases for household appliances and electronics, as well as high temperature piping for fluid contact areas.