Microstructure and ultimate properties of injection molded amorphous engineering plastics: Poly(ether imide) and poly(2,6‐dimethyl‐1,4‐phenylene ether)

Specimens of two engineerig plastics i.e., poly(ether imide), PEI, and poly(2,6‐dimethyl‐ 1,4‐phenylene ether), PPE, were injection molded employing a 40t Van Dorn injection molding machine and industrial practices. The mold and melt temperatures and the injection speed were varied in a limited range which furnished acceptable samples. The density, birefringence, residual stress distributions, flexure and tensile properties, and crack development of the injection molded specimens were studied. Vacuum compression molded samples were also prepared to investigate the role played by the cooling rate in shaping microstructural distributions. The results revealed significant differences in the development of microstructure of the molded specimens of the two resins, which was related to rheology and molding conditions on one hand and to development of cracks and ultimate properties on the other hand.