PERMEATION THROUGH STRONGLY INTERACTING POLYMER BLENDS - EVOH COPOLYAMIDE-6/6.9/

This research focuses on polymer blends of two random copolymers: Ethy lene-vinyl-alcohol, EVOH, consisting of different ethylene contents, a nd copolyamide-6/6.9 with an approximate 1:1 comonomer ratio. Films, 2 0 microns thick, of the EVOH/COPA blends were prepared via blown film extrusion. Gas permeabilities were measured to provide information abo ut the nature of the blends. It was found that these blends are partia lly miscible. The rich-EVOH blends exhibit a much lower miscibility th an those of the copolyamide-rich blends. The ethylene content in the E VOH affects the miscibility of the blends: a higher ethylene content r esults in a lower miscibility. This is due to less intermolecular hydr ogen bonds between the OH group of the EVOH and the amide group of the copolyamide. EVOH-38/copolyamide-6/6.9 and EVOH-38/EVA-9% blends were compared. Oxygen transmission of the EVA-containing blends exhibited percolation behavior (typical of immiscible blends), while the copolya mide-containing blends depicted a behavior similar to the predicted on e for miscible blends.