The effect of externally applid stresses on the structure of an ethylene‐rich EPDM terpolymer

Structural changes in an ethylene‐rich ethylene‐propylene‐diene terpolymer (EPDM) were studied as a function of applied external stress. From its initial unstretched value of 15%, the terpolymer crystallinity increased to 73% at a tensile strain of 225%. X‐ray diffraction patterns showed that, when stretched, the terpolymer assumed a hexagonal structure and an increase in the until cell a ‐dimension occurred. A fibre texture developed with the lamellae inclined to the tensile axis.