Viscoelastic behavior of Silica nanoparticle/polyimide nanocomposites using finite element approach

A three-dimensional micromechanical finite element model is developed to study the viscoelastic behavior of the silica nanoparticle/polyimide nanocomposites. The representative volume element (RVE) of the model consists of three phases including silica nanoparticle, polyimide matrix and interphase which surrounds the nanoparticle. The interphase region is created due to the interaction between the silica nanoparticle and the polymer matrix. The effects of different important parameters such as interphase material properties and thickness, silica nanoparticle volume fraction and geometry as well as type of nanoparticles distribution are investigated. It is found that the interphase significantly affects the viscoelastic behavior of the nanocomposites. Also, the results reveal that with decreasing the nanoparticle diameter or increasing volume fraction, the creep strain of the nanocomposite reduces. Moreover, the creep strain of the nanocomposites decreases with the uniform distribution of the nanoparticles inside the polymer matrix. It is shown that for the elastic properties of the nanocomposites, while the predictions without interphase are far from the reality, the predicted mechanical properties with interphase demonstrate very good agreement with experimental data.