Alloys, or blends of PPE and polystyrene in various proportions, are marketed under the tradenames of Noryl and Prevex (General Electric). The resins are processed by conventional injection molding,extruding, and thermoforming methods. Structural foam parts are processed in standard foam molding systems, using either direct induction of nitrogen gas or conventional chemical-blowing agents.
Polyphenylene ether is produced by a process based on oxidative coupling of phenolic monomers. The result, a resin that has good mechanical stability, is then blended with polystyrene to improve processibility. Available grades of molding resins, including glass-reinforced and platabie compounds and heat-resistant grades (containing nylon), in addition to extrusion and foarnable grades. All resins can be furnished in a wide range of colors.
Properties: Polyphenylene ether blends are characterized by outstanding dimensional stability, the lowest water absorption of the engineering thermoplastics, broad temperature ranges, excellent mechanical and thermal properties, and excellent dielectric properties over a wide range of frequencies and temperatures. Several injection-molding and extrusion grades are rated UL 94V-1, or V-0, including glass-reinforced versions. Foarnable grades have service-temperature ratings of up to 205°F in 1/4-in. sections.
Because of their excellent hydrolytic stability, both at room and elevated temperatures, PPE blend parts can be repeatedly steam-sterilized with no significant change in properties. In exposure to aqueous environments, dimensional changes are low and predictable. Resistance to acids, bases, and detergents is excellent. The material is attacked, however, by many halogenated or aromatic hydrocarbons. Prototype testing of components requiring exposure to such environments is recommended.
