Partially miscible EVOH/copolyamide-6/6.9 blends: Thermal, dynamic-mechanical and shear rheology behavior

Binary blends of two random copolymers, ethylene-vinyl-alcohol (EVOH) consisting of different ethylene contents, and copolyamide-6/6.9 with an approximate 1:1 comonomer ratio, have been prepared via blown film extrusion as films, 20 mu m thick. Thermal, dynamic-mechanical, and rheological properties were determined. It was found that these blends are partially miscible. The-EVOH-rich blends exhibit much lower miscibility than the copolyamide-rich blends. The ethylene content in the EVOH affects the miscibility of the blends: a higher ethylene content results in a lower miscibility. This is due to fewer intermolecular hydrogen bonds between the OH group of the EVOH and the amide group of the copolyamide. The interactions between the blends' components affect their thermal, dynamic-mechanical and their rheological behavior.