We developed an ethylene vinyl alcohol copolymer with 1,2 diol side chains (hereinafter new EVOH) that can be melt-molded even though the ethylene content is about 16 mol%, and the properties of polymer alloy that consists of nylon 6-66 (hereinafter PA) and new EVOH were studied. The polymer alloy showed compatibility on the PA rich side ,but the crystallinity of each component decreased at the same time. Especially when the PA content is 85wt.% for polymer alloy, PA crystals were not confirmed. The free volume of the composite increased linearly with the PA blend ratio,but the specific volume deviated from the linear relationship ,which increased on the PA rich side. The normalized free volume was calculated using the amorphous ratio calculated from solid state NMR(T1C: 13C spin-lattice relaxation time) and I 3 (the relative intensity of the long time component) from PALS. It was confirmed that high pressure hydrogen resistance of PA blended with new EVOH was improved by using normalized free volume even on the PA rich side. This result is thought to be due to the amorphous part of PA reinforced by interaction with new EVOH.
