Crystallization and Planar Orientation of Crystallites in Ethylene-Vinyl Alcohol Copolymer

Ethylene-vinyl acetate copolymer was saponified and examined by using X-ray and other techniques. The copolymer was crystallizable over a wide range of its composition and double orientation of the crystallites was effected by rolling. In the copolymers containing less than 40 mole% of ethylene, crystals were monoclinic, and were orthorhombic in those more than 88% of ethylene. Chains were extended and packed pseudo hexagonally in those consisting of 60 to 80% of ethylene. The copolymer having about 85% of ethylene showed the lowest melting point. It was pointed out that ethylene and vinyl alcohol units were cocrystallized with almost the same composition as that of the copolymer.