Innovations in rubber compounds crack growth testing

Polymers exposed to high stress or at harsh environmental conditions, are subject to crack propagation, which limits quickly their lifespan. In order to quantify this phenomenon, Metravib Material Testing developed a method to quantify the cracks growth, by combining the mechanical solicitation capability of DMA and a mobil camera. This paper describes this new method and how it can be used to determine the effect of the temperature and of frequency of the solicitation on the cracks growth. Tests were performed on Styrene-Butadiene Rubber (SBR) and elastomeric silicone. The results showed that for a fixed number of excitation cycles, the crack propagation was increasing at low frequency. This phenomenon at low frequency has been attributed to a temporal mechanical contribution in addition to the cyclic mechanical contribution. This presentation also depicts that crack propagation rate increases with increasing temperature. This effect is more pronounced for SBR material than for silicone material, due to their high thermal stability.