The mechanical properties of rubber compounds containing soft fillers

A detailed examination of failure of properties of polybutadiene containing soft elastomeric fillers has previously been described [1]. Here the effect of filler modulus and filler-matrix adhesion on tear strength is measured. Tear behaviour depends upon the level of interfacial adhesion; when high, tear strength increases with increasing filler hardness, but if interfacial adhesion is low, incorporation of fillers may result in low tear strengths. An estimate of the edge flaw size is made from the tear strength and strain energy densities at break. It was found that compounds with low interfacial adhesion generally had edge flaw sizes of the same order as the maximum filler particle size. A correlation between tear strength and tear surface morphology is made.