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

通过实验研究了双分散球形二氧化硅粒子对环氧树脂复合材料力学性能的影响，并利用粒子分散模型进行了理论分析。本研究使用的材料为不同球形二氧化硅颗粒增强的双酚A型环氧复合材料、直径240 nm的纳米二氧化硅颗粒和直径1.56 mm的微米二氧化硅颗粒。样品具有不同的粒度组成。测试了复合材料的力学性能，即热粘弹性和断裂韧性。玻璃态复合材料的粘弹性能与颗粒大小无关，由颗粒的总体积分数决定。由于颗粒迁移率的增加，橡胶状态下的性能与颗粒大小有关。用Bansal和Ardell的统计方法对每种复合材料的随机分布的颗粒间距进行了数值分析。TH…随机分布颗粒的最近表面距离取决于颗粒的体积分数，并与颗粒直径成正比。然后，基于相同颗粒体积分数的每个复合材料的相似颗粒分布，建立了单颗粒分散复合材料断裂韧性的理论模型，并考虑了混合律。我们发现，复合材料的断裂韧性与(I)颗粒表面平均距离的平方根和(Ii)由等效夹杂方法给出的基质中的归一化平均应力的乘积的倒数近似成线性关系。理论计算结果与实验结果吻合较好。然而，断裂韧性的混合定律包含了未知参数，该未知参数被预测为与聚合物基质的cxosslink结构与颗粒之间的相互作用有关。因此，我们阐明了玻璃态颗粒双分散复合材料的热粘弹性性质仅由颗粒的总体积分数决定，而断裂韧性则由颗粒的尺寸分布和体积分数决定。基于这一结论，我们得出了复合材料的热粘弹性和断裂性能可以独立定制的结论。较少

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