Reactive compatibilization of polymer blends of poly(butylene terephthalate) (PBT) and polyamide-6,6 (PA66) .1. Rheological and thermal properties

Epoxy resin (EEW = 2060) has been demonstrated to be an efficient reactive compatibilizer for the incompatible polymer blends of polyamide-6,6 (PA66) and poly(butylene terephthalate) (PET). Processability improvement has been achieved by reducing die swell and melt fracture during blending extrusion. Reactions involved in this three-component system are very complex but only the coupling reactions between epoxy and PBT and PA66 endgroups are considered essential. This epoxy resin is more compatible with PET than with PA66 but the reactivity of the former is slower than that of the latter. Additionally, PET has a lower melting temperature than that of PA66; this epoxy resin therefore has the first chance to react with PBT, then with PA66, at the interface. Certain mixed copolymers, epoxy-co-PBT-co-PA66, are expected to be formed and to anchor at the interface. These mixed copolymers are believed to be the major contributor in improving the compatibility of incompatible PA66/PBT blends. (C) 1997 Elsevier Science Ltd.