Micromechanical modelling of the viscoelastic behaviour of an amorphous poly(ethylene)terephthalate (PET) reinforced by spherical glass beads

Homogenization micromechanical models are applied to predict the linear viscoelastic properties of an amorphous poly(ethylene)terephthalate (PET) composite in the range of glass transition by using the elastic-viscoelastic superposition principle defined by Hashin [1]. An amorphous PET is reinforced by glass beads and is submitted to dynamic mechanical tests at temperatures surrounding its quasi-static glass transition temperature. The viscoelastic properties of the matrix and the elastic properties of the beads are measured experimentally. The micromechanical models predictions of the linear viscoelastic behaviour in the glassy state are acceptable. In the rubbery state, the beads seem to reduce the molecular mobility of the matrix driving to a large change in the viscoelastic properties of the materials. Thus, this paper aims to emphasize that classical homogenization micromechanical models, which depend only on the constituent behaviour, shape and distribution, cannot predict this change in the linear viscoelastic behaviour of the beads/PET composites.