Elastic moduli of the crystalline regions in the direction perpendicular to the chain axis of ethylene‐vinyl alcohol copolymers

In order to clarify the crystal structure and intermolecular cohesion forces of ethylene‐vinyl alcohol copolymers (EVA), the elastic modulus ( E t ) of EVA copolymers was measured. We proposed that EVA copolymers are crystallizable over the entire range of copolymer composition and can produce, an isomorphous crystallite. On the basis of these crystal structures, the value of E t was expected to be dependent on the copolymer composition. E t values are indeed closely dependent on composition and decrease with decreasing VA segment. From the anisotropy of E t for (100) and (002) planes, which means the anisotropy of the intermolecular interaction, the direction of hydrogen bonding seems to be in the a ‐axis direction.