Blending and oxygen permeation properties of the blown films of blends of modified polyamide and ethylene vinyl alcohol copolymer with varying vinyl alcohol contents

The oxygen permeation and blending properties of the MPAEVOH blends of modified polyamide (MPA) and ethylene vinyl alcohol copolymer (EVOH) with varying vinyl alcohol contents were systematically investigated in this study. The oxygen permeation rates of EVOH film specimens are dramatically slower than that of the PE specimen and reduce significantly as their vinyl alcohol contents increase. After blending EVOH in MPA resin, the oxygen permeation rates of each MPAEVOH series film specimens reduce significantly as their EVOH and/or vinyl alcohol contents increase, respectively. At some optimum compositions, the oxygen permeation rates of the MPAEVOH film specimens are even lower than that of the pure EVOH film specimen with a vinyl alcohol content of 52 wt%. On the other hand, the average radius (R-f), volume (V-f) of the free-volume-cavities and fractional free-volume (F-v) values of each MPAEVOH series specimens reduce significantly as their EVOH and/or vinyl alcohol contents increase. These interesting barrier and free-volume properties of the EVOH and MPAEVOH specimens with varying vinyl alcohol contents were investigated in terms of the intermolecular interaction and/or free-volume properties in the amorphous phases of the EVOH and MPAEVOH specimens obtained in this study.