Nanoscale fast relaxation events in polyethylene

Discrete relaxation events on the submicron scale were observed during nanoindentation on polyethylene. The frequency with which these events occur increases as the crystallinity of the polyethylene increases, but the effect saturates at high crystallization levels. At a given crystallinity, the occurrence frequency decreases as temperature increases, due possibly to the enhancement of viscous flow as a competing stress relaxation process. The emission rate of the discrete relaxation events also increases with temperature, exhibiting an activation energy of about 0.22 eV.