Measuring the Durability Benefit of Strain Crystallization Via Crack Arrest Experiments

Strain crystallization in an elastomer can impart strong beneficial effects on durability. An experimental procedure has been developed to characterize the strain crystallization effect on fatigue crack growth behavior. The procedure utilizes an edge-cracked planar tension geometry that is solicited under both fully relaxing and non-relaxing conditions. The scheduled conditions result in a high initial rate of crack growth and minimum crystallinity, followed by a period of increasing crystallinity and decreasing crack growth rate. The kinetics of the decrease of crack growth rate (i.e. the kinetics of crack arrest) provides information useful in simulating damage development in a strain crystallizing elastomer.