Microstructure evolution in short fibre reinforced elastomers

Nanofillers are normally employed to increase mechanical and thermal properties of elastomeric compounds. Nanoclays, Carbon Nanotubes or Graphene have large specific surface areas and excellent physical properties that give them the potential to provide significant mechanical improvements (see, e.g., [1]). With respect to the isotropic reinforcement provided by carbon black, short fibre reinforcement have an highly oriented structure which makes the overall response of the elastomer anisotropic. The constitutive behaviour of the compound is analysed and an analytical/numerical model is formulated to describe the microstructure evolution during the deformation. Following the analysis in [2], a sensitivity study is carried out in terms of filler content, filler orientation and heterogeneity contrast. When the matrix is viscoelastic, it is shown that the alignment of the filler fibres along the direction of stress could produce the strain hardening behaviour which is commonly observed during tensile tests. The modelling results are compared with the experiments (tension/relaxation) carried out by the authors on natural rubber reinforced with Graphene Oxide.