Kinetics and characterization of the process‐zone evolution in polycarbonate

The process‐zone evolution strongly influences the crack growth of polycarbonate. A methodology for determination of the kinetics of the process‐zone evolution by decoupling these two processes was developed. This was achieved using constant displacement (stress‐re‐laxation) conditions under which the crack length remained constant. The morphology of the process zone was characterized using optical microscopy of cross sections and fracture surfaces produced with liquid nitrogen. The kinetics of process‐zone evolution and stress relaxation were monitored and analyzed. The kinetics vary significantly with the level of displacement imposed. Thus, the challenge remains to construct a master curve for the kinetics. © 1993 John Wiley & Sons, Inc.