Cyclic crack propagation and molecular kinetics of polymers

Cyclic tests in tension were performed on PMMA and PC center-notched plate specimens. Frequencies between 0.1 and 100 Hz at temperatures from ?78 to +55°C were investigated. Correlations between crack growth rates, described in the terms of stress intensity K, and the appropriate values of the loss factor tan δ were studied. It was concluded that, in the investigated conditions, a direct correspondence exists between the crack growth rate and tan δ.