Journal Papers Published by the Rubber Research Group

"Cavitation in granulate filled rubber materials"

Author(s): P. Kumar, A.G. Thomas, Y. Fukahori and J.J.C. Busfield

Journal: Constitutive Models for Rubber V’ edited by A. Boukamel, L. Laiarinandrasana, S. Meo & E. Verron, pp. 157-164

All elastomers contain flaws within them and these intrinsic flaws affect the strength of the material. The incorporation of rubber granulates into virgin rubber results in premature failure of the resulting material and this has been attributed to an increase in the Intrinsic Flaw Size (IFS). The question remains, is it just an increase in the flaw size or do these flaws open up when the matrix-granulate composite is strained and is the failure associated to the poor bond between the matrix and granulate? Our experiments on volume change show that for carbon black filled rubber with no granulates incorporated, no significant volume change under tensile strain due to cavitation is observed. In contrast, for granulate filled materials, volume changes are measured experimentally and have also been modelled using Finite Element Analysis (FEA). This has al-lowed us to deduce how the flaw size changes as a function of strain. This work shows that flaw size increases similarly with strain for all the composite materials where the matrix and granulates have same modulus whereas a modulus mismatch between the matrix and the recycled granulate results in much larger volume changes and hence greater flaw size which also appears to increase with strain. This work emphasises the importance of matching the modulus of recycled granulate materials to that of the new matrix.

Related site: http://www.materials.qmul.ac.uk/rubber