粒子填充聚合物基复合材料导热性能的数值模拟

Numerical investigation of the thermal property of particle filled polymer matrix composite

根据电镜照片中观察的微观结构信息,基于两套新设计的算法建立了代表体积元(RVE)模型,基于此模型研究了粒子填充聚合物基复合材料的导热性能与微观结构的关系。通过对电镜照片的处理得到两个参数即稀疏区比重和稀疏区半径,建立了与实际体系相符的具有非均匀粒子分布结构的RVE模型。制备了氧化铝/高温硫化硅橡胶导热复合材料,并测试了不同填充量下体系的热导率,用以验证模型的有效性。采用有限元方法求解RVE模型得到的热导率预测值与实验值进行对比,结果表明:填料用量在宽范围内预测结果与实验值均吻合很好;与均匀分布或随机分布相比,存在稀疏区和富集区的非均匀分布的体系具有更高的热导率,这种差异在高填充量下当颗粒间形成导热网链时更为显著;在相同填充量下,不同的粒子空间分布结构可使体系热导率差别很大,是影响体系热导率的关键因素。

A representative volume element （RVE） model was developed to investigate the relation between thermal property and microstructure of the particle filled composite. The model was based on two novel algorithms, and was constructed with the same particle spatial distribution structure of the real heterogeneous composite by the introduction of two parameters, i.e. the ratio and the radius of particlepoor region, which both were estimated from SEM micrographs. The model was verified by comparing the predicted and the practical thermal conductivity. It has been found that the simulation results are accurate in the large scale of filler content. The system with nonuniform particle spatial distribution shows higher thermal conductivity than that with random or uniform particle spatial distribution, especially at the high filler volume fraction when conductive pathways or networks form. And at the same filler volume fraction, the thermal conductivity of the composites can be significantly different due to the different particle spatial distributions.