Viscoelastic behaviour and modelling of nano and micro TiO2 powder-epoxy resin composites

Epoxy resin composites reinforced with different weight fractions of TiO₂ micro-particles 0.2 μm in size (1%, 5%, 10%, 15%wt) and of TiO₂ nano-particles 21 nm in size (0.5%, 1%, 3%wt) were manufactured. The quasi-static mechanical properties of both nano-composites and micro-composites were investigated and compared through tensile testing. The experimental results were predicted and the degree of matrix-particle adhesion and particle dispersion were evaluated, by the Property Prediction Model (PPM) developed by the first author. The composites were also subjected to creep-recovery tests as well as to relaxation tests in order to investigate their viscoelastic behaviour. The experiments were carried out at different filler-weight fractions and loading conditions. Non-linear viscoelastic behaviour was observed in all cases and appropriate models were applied in order to describe, and/or predict the viscoelastic behaviour of all materials tested. A fair agreement between experimental results and theoretical predictions was observed for both viscoelastic and static results.