Study on epoxy/thermoplastic blends based on the addition of a novel aromatic block copolymer

In this article we present a study of the properties of some epoxy/thermoplastic blends based on the addition of a novel block copolymer of an ABA type. The block A was a commercial poly(2,6‐dimethyl‐1,4‐phenylene ether or oxide) (PPE or PPO) while block B was a random copolyethersulphone synthesized in our laboratory. The comparison with the epoxy blends modified only with the homopolymers A or B is also reported. The homopolymers were also mixed via solution blending and the resulting physical mixture was used as modifier for comparison purposes. The blends have been thoroughly characterized by parallel plate rheometry, dynamic mechanical thermal analysis (DMTA), and scanning electron microscopy. Upon curing, the epoxy blends containing the physical mixture underwent phase separation showing a morphology which resembled the combination of those found for the blends modified with each of the homopolymers. On the contrary, the addition of the block copolymer resulted in a unique morphology. The viscoelastic properties of the blends both in the unreacted and cured state varied significantly when the block copolymer was added rather than the homopolymers or their physical mixture. POLYM. ENG. SCI., 47:2027–2033, 2007. © 2007 Society of Plastics Engineers