基于比等效热阻法的片状填料填充聚合物复合材料的导热性的预测

Thermal Conductivity Property of Flake Fillers Reinforced Polymer Composites Based on Equivalent Thermal Resistance

基于比等效热阻法建立了简化了的片状填料填充聚合物基复合材料的导热模型并推导出了相应的等效导热系数公式。以云母片填充聚乳酸为例,应用有限元软件ANSYS建立了云母体积分数在11%下的聚乳酸/云母复合材料的三维稳态热传导单元模型,并模拟了热流沿云母片厚度方向和径向传递的过程。结果表明,当热流沿云母片轴向方向上流动时,经ANSYS模拟求得的复合材料的等效导热系数和文中推导的公式的所给出的预测值更为接近;当热流沿云母片的径向流动时,随着云母体积分数的增加,复合材料的等效导热系数的预测值呈指数性增长,并且高于ANSYS的计算结果。有限元结果和本文的公式均表明,片状填料填充聚合物复合材料的等效导热系数可分解为是沿热流不同正方向上的贡献,更长的等效导热路径使片状颗粒在填充聚合物后能提供更为出色的导热性能。

In this paper ,a simplified thermal equivalent model of the flake filler reinforced composite was established based on equivalent thermal resistance and corresponding equivalent thermal conductivity coefficient formula is derived .Take the mica plate used to fill polylactic acid for example .A three-dimen-sion steady-state thermal conduction unit model for polylactic acid/mica composite is made through ANSYS software with mica volume fraction of 11% .The process of thermal flux transferring to thickness direction and radial direction of the mica plate is simulated .The results show that when thermal flux flowed along the axial direction of the mica plate ,equivalent thermal conductivity coefficient of the composite gained through ANSYS simulation more approached the predicted value gained through the formula ;when ther-mal flux flowed along the radial direction of the mica plate ,as mica volume fraction rose ,the predicted val-ue of equivalent thermal conductivity coefficient of the composite presented exponential grow th and is high-er than the result of ANSYS .The finite element result and the formula in this paper showed equivalent thermal conductivity coefficient of flake filler polymer composite could be decomposed to contributions at different directions along the thermal flux ;longer equivalent thermal conductivity path made flake particles provide more outstanding thermal conduction property after filling the polymer .