DEFECT DIFFUSION MODELS FOR INTERNAL FRICTION PROCESSES IN POLYETHYLENE

Defect loops that encircle one chain in a polyethyene crystal are characterized in terms that are used to describe dislocation loops in metals. In a polyethylene crystal the defect loop which requires the least energy for creation belongs to the relatively unknown class of defects called dispirations. Dispirations can be thought of as defects in the helical symmetry of the polyethylene molecule in the crystal. The processes by which the diffusion of dispiration loops can contribute to relaxation processes in polyethylene are described.