The preparation and morphology of PPO–epoxy blends

Poly(phenylene oxide) (PPO) was found to be miscible in diglycidyl ether of bisphenol A (DGEBA) based epoxy. The PPO–DGEBA system exhibited upper critical solution temperature (UCST) behavior. The cloud point temperatures were measured and found to be sensitive to the mol wt of the epoxy resin. A series of PPO-modified epoxies were cured with piperidine at 160°C, which is above the cloud point temperature. Upon cure, two phase solids were formed, which contained discrete PPO particles. However, the two-phase particulate morphology was not uniform and numerous large, occluded PPO particles were observed. In order to improve the uniformity, several styrene-maleic anhydride copolymers were evaluated as potential surfactants for PPO-DGEBA bends. The formation of a uniform, particulate morphology was facilitated by the addition of a styrene–maleic anhydride copolymer, containing a 10:1 ratio of styrene to maleic anhydride. To our knowledge, this is the first time that an emulsifying agent has been added to improve the morphology of thermoplastic modified epoxies. © 1993 John Wiley & Sons, Inc.