Effect of Bi-dispersing Silica Particles on Mechanical Properties of Epoxy Composites

点击翻译按钮获取中文摘要

Effect of bi-dispersing spherical silica particles on mechanical properties of epoxy composites were investigated experimentally and also analyzed using model of particle dispersion theoretically. The materials of specimens used in this study were bisphenol A-type epoxy composites reinforced by different spherical silica particles; nano-silica particle with 240 nm in diameter and micro-silica particle with 1. 56 mm in diameter. The specimens had different particle size compositions. We measured mechanical properties, namely thermo-viscoelasticity and fracture toughness, of the composites. The viscoelastic properties of the composites in glassy state were independent of particle size and governed by total volume fraction of the particles. The properties in rubbery state were found to have dependency on particle size due to increasing particle mobility. Distance between randomly-distributed particles for each composite was analyzed numerically by Bansal and Ardell's statistics method. Th … More e nearest surface distance of randomly-distributed particles is dependent on the volume fraction of the particles and proportional to its diameter. Then, based on similar particle distribution for each composite having the same volume fraction of the particles, we constructed theoretical model and considered mixture law of fracture toughness for single-particle dispersed composite. We found that the fracture toughness of the composites was approximately linear with respect to the reciprocal of the product of (i) the square root of the mean distance between the particle surfaces, and (ii) the normalized mean stress in the matrix given by the equivalent inclusion method. The theoretical result agreed well with the experimental results. However the mixture law of fracture toughness included the unknown parameter which was predicted to be related to interaction between particle and cxosslink structure of polymer matrix. Therefore, we clarified that the thermo-viscoelastic properties of particles bi-dispersed composites in glassy state are determined only by total volume fraction of the particles and the fracture toughness are done by distribution of particle size and the volume fraction. Based on this conclusion, we obtained that thermo-viscoelastic and fracture properties of the composite can be tailored independently. Less