Influence of strain rate on nanoparticle debonding in polymer nanocomposites

This paper attempts to evaluate the influence of strain rate on the debonding stress of the spherical nanoparticles using a closed form solution. A coherent model to correlate a relationship between the debonding stress of polymer-based nanocomposites and the strain rate was developed. A representative volume element (RVE) containing a spherical nanoparticle, an interphase material, and a pure polymer phase was regarded. A relationship between the debonding stress and the applied strain rate, the material, and geometrical properties of the RVE's constituents was correlated. In addition to the strain rate, the role of some effective variables such as nanoparticles size, interphase thickness, and interphase stiffness on the debonding stress were investigated. To evaluate the model, three case studies based on the experimental studies performed on silica nanoparticles/epoxy, CaCO3 nanoparticles/high-density polyethylene (HDPE), silica nanoparticles/photopolymer nanocomposites were conducted. For the nano-silica/epoxy system, the results revealed that by enhancing the strain rate, the normalized debonding stress decreases. Additionally, under a certain strain rate, the normalized debonding stress enhances as much as the stiffness of interphase material increases and the nanoparticle size decreases. In the case of CaCO3/HDPE nanocomposites, it was observed that by increasing the size of nanoparticles, the normalized debonding stress was reduced significantly. For the nano-silica/photopolymer nanocomposites, it was found that the dependence of the normalized debonding stress on the strain rate is more remarkable for the thicker interphase region. The proposed model can be used to predict the mechanical properties of nanoparticles/polymer systems under high strain rate conditions.