Introduction

In 1956, Allan S. Hay of the General Electric Company discovered a convenient catalytic oxidative route to poly(2,6-dimethylphenylene ether), or PPE. This amorphous polymer exhibited excellent hydrolytic stability, an extremely high glass transition temperature [ T _g = 419 F (215 C)], outstanding electrical properties over a wide temperature range, low density relative to other engineering thermoplastics, and a high melt viscosity. The polymer was introduced commercially in 1964 under the PPO ^[*] trademark ^{[1] , [2]}.

It was soon realized that because of the high glass transition temperature, high melt viscosity, and the resulting elevated temperatures that were required for processing, it would be difficult to avoid oxidative degradation reactions during melt processing. The commercial solution to this problem was blends of PPE with polystyrene (PS).

PPE may never have achieved commercial success if PPE's novel compatibility with styrenic polymers had not been discovered at an early stage of development. This fortuitous and rather rare miscible, single-phase blend provided the basis for the family of PPE/PS alloys, which were commercialized in 1966 under the Noryl* trademark ^[3]. Modified PPE resins combined the best features of PPE resins and styrene polymers. The Noryl family of resins has become the world's most successful and best-known polymer blends or alloys.