Polyphenylene Oxide (PPO) - A thermoplastic, linear, noncrystalline polyether obtained by the oxidative polycondensation of 2,6-dimethylphenol in the presence of a copper-amine-complex catalyst. Polyphenylene oxide, also called polyphenylene ether, is usually blended with polystyrene to improve its toughness and processability. Polyphenylene oxide has excellent electrical properties, unusual resistance to acids and bases, and is processable on conventional extrusion and injection molding equipment. PPO is easily attacked by some hydrocarbons, although it resists many chemicals. Polyphenylene oxide possesses excellent dimensional stability, low moisture absorption, and high mechanical and dielectric strength.