The dependence of rapid crack propagation in polyethylene pipes on the plane stress fracture energy of the resin

The critical temperature [CT] for rapid crack propagation [RCP] was measure d in 11 polyethylene [PE] 200 mm diameter gas pipes each with different res ins. The plane stress fracture energy [PSFE] in thin Charpy impact specimen s of the resin was found to correlate with the CT. The higher the PSFE, the lower the CT. This result was related to the observation that the PSFE dec reases as the temperature decreases. It was found that the impact energy of specimens from compression molded pipe that was remelted at 180 degreesC g ave a better correlation with the CT than specimens that were machined from the inner wall of the pipe. Consequently, it is now possible to predict th e CT of a pipe by measuring the PSFE of the resin without making the pipe.