Mechanism of Kinking in Oriented Polyethylene

Abstract

The kink band formed by compression in oriented high density polyethylene in a temperature range around room temperature was studied to ascertain the possibility of a pseudo-twinning with a twin plane intersecting the c-axis. Dependence of the formation of the kink band and its direction on temperature and compression direction was studied. Structure change by the kinking was observed by X-ray diffraction and electron microscopy. Formation of the kink band was possible almost between 85°C and -120°C. The temperature range was divided into two parts in which kinking behavior was different. In the high temperature range, the kink band inclined in the same direction as lamellae, and the shear component along the c-axis of the compressive force was unnecessary for the kinking. Moreover, the lamellae were sheared as much as 200% by the kinking, and the kink boundary was microscopically sharp. These facts show that the pseudo-twinning really occurred.