氮化硼填充聚丙烯复合材料导热性能的数值模拟

Numerical simulation of the thermal conductivity of polypropylene composite filled with boron nitride

基于有限元分析技术,模拟氮化硼(BN)填充量、径厚之比、晶粒取向以及粒径对BN填充聚丙烯(PP)复合材料(BN/PP)导热性能的影响。通过对比数值模拟结果、用理论模型计算的结果和实验结果,验证了数值模拟的可行性。结果表明:随着BN填充量的增加,BN/PP的导热系数不断增大;当BN质量分数低于15%时,提高径厚之比可以改善BN/PP的导热性能,但随着BN填充量的不断增加,径厚之比过大反而会减小BN/PP的导热系数;在固定填充量下,BN/PP的导热系数随着BN晶粒取向角在0~180°内变化而呈现先减小再增大的趋势,且在声子沿BN径向传播热量时为最高;随着BN粒径的增大,在低填充且随机分布的情况下,BN/PP的导热性能有所提高,但对于定向填充来说,增大BN粒径对提升BN/PP导热系数更加有效。

Based on the finite element analysis technology,the effect of boron nitride(BN)filling amount,radial to thickness ratio,orientation and particle size on the thermal conductivity of polypropylene(PP)composites(BN/PP)is simulated.Through mutual comparison with theoretical models and experimental data,the feasibility of numerical simulation is verified.The simulation results show that the thermal conductivity of BN/PP continues to increase with the increase of the BN filling content;when the mass fraction of BN is less than 15%,increasing the radial to thickness ratio can improve the thermal conductivity of BN/PP,however as the filling volume continues to increase,the ratio of the radial direction to the thickness is too large,while the thermal conductivity of BN/PP is reduced.At a fixed filling amount,the thermal conductivity of the composite material will first decrease and then increase as the BN orientation angle from 0 to 180°,the thermal conductivity of BN/PP is the highest when the phonons transmit heat in the radial direction of the BN.With the increase of the BN particle size,the thermal conductivity of BN/PP is improved under the condition of low filling and random distribution,but compared with the directional filling,the increase of BN the particle size increases the thermal conductivity of BN/PP more significantly.