Investigation into stress-strain behaviour of organoclay SBR composite using different constitutive models

In this work, four different material models were used, namely the Mooney-Rivlin, 5-term polynomial, Ogden and Arruda-Boyce models, for various compounds and processing conditions. The applicability of these models to nanocomposites and the best fit of these mathematical models were investigated against experimentally measured data. By applying different mixing times (4, 8, 12 min) and nanoclay contents (3, 6, 9 Phr) on the SBR nanocomposites, the different morphologies were monitored by XRD. The effects of mixing time and concentration of nanofiller were studied on the morphology obtained. The stress-strain behaviours of different morphologies (intercalated and exfoliated) were determined and then compared to the predicted data from the models. It was found that the Ogden model could be used for all rubber/filler nanocomposite structures at various filler loadings and mixing times while the Arruda-Boyce equation should be used with care since it cannot predict the true behaviour of all structures and morphologies. It can be concluded that an intercalated and/or exfoliated structure changes the dynamics of the macromolecular motions in compounds resulting in the requirement for some new theoretical study to be done to develop new models for the description of the mechanical behaviour of rubber nanocomposites.