Three-phase model and digital image correlation to assess the interphase effect on the elasticity of carbohdyrate polymer-based composites reinforced with glass–silica beads

Thermomoulding of starch-based composite shows that the elastic modulus is non-linearly dependent on the fraction of glass–silica used as a reinforcement material. In order to explain this result, a three-phase model is implemented using finite element computation to account for the role of phase arrangement and interphase properties on the effective behaviour. For this purpose, virtual generation of typical microstructures is performed taking into account the size distribution of the filler as well as the interphase properties. The numerical results well show that, depending on the interphase modulus, two opposite trends are predictable. The identification of the experimental elastic behaviour points out the weak interface adhesion between the matrix and the filler. This result is confirmed by the digital image correlation, which depicts a displacement jump across the starch–glass–silica interface.