Characterizing mechanical properties of particulate nanocomposites using micromechanical approach

This research aims to propose a continuous micromechanical model for characterizing the mechanical properties of the nanocomposites containing silica nanoparticles embedded in polyimide matrix. The molecular structures of the nanocomposites were established through molecular dynamic ( MD) simulation, from which the non-bonded gap as well as the non-bonded energy between the nano-sized inclusion and the surrounding matrix were evaluated. It was postulated that the normalized non-bonded energy (non-bonded energy divided by surface area of the inclusion) is correlated with the degree of interfacial interaction. Subsequently, an effective interphase micromechanical model including inclusion, matrix and effective interphase was developed, in which the dimension of the effective interphase was assumed equal to the non-bonded gap and the corresponding elastic stiffness was calculated from the normalized non-bonded energy. Comparison of the results calculated from the micromechanical model and the MD simulation indicates that the effective interphase model is capable of describing Young's modulus of particulate nanocomposites with accuracy. In addition, it was revealed that when the particulate size decreases, the corresponding modulus of the nanocomposites increases.