Annealing effect of tree propagation from a simulated tree channel - examination on tree propagation of early/random failure type

摘要

I have been investigating tree growth from tip of a simulated tree channel in PP block on the basis of shape-parameter m in Weibull distribution of total number of PD pulses to its initiation. I have suspect that structural weak points around tip of a simulated tree channel play important roles in tree propagation of early/random failure type (m≤1), especially channel diameter is large. In this paper, influence of bulk structure on tree propagation from a simulated tree channel will be discussed with annealed specimen. Inception voltage and total number of PD pulses required for tree propagation in annealed specimen is higher than that in virgin specimen. They increase with annealing temperature but are regardless of annealing time, which is longer than 1 hour. Furthermore, tree propagation of early/random failure type (m≤1) disappears in annealed specimen and only that of fatigue failure type (m> 1) appears. From results of FT-IR and XRD analyses, it is predicted that these phenomena are caused by recrystallization of amorphous part between lamellas and relaxation of internal stress.