石墨和炭纤维分别改性热塑性聚酰亚胺复合材料的导热行为

Thermal conduction of thermoplastic polyimide composites modified with graphite/carbon fiber

采用石墨、炭纤维填充改善热塑性聚酰亚胺(TPI)材料的导热性能,研究了填料物性对材料力学性能和导热行为的影响。在此基础上,用Nielsen理论模型和有限元方法模拟了复合材料的导热行为,进一步探讨了填料形状对材料导热系数的影响。研究表明:炭纤维、石墨填充TPI均能提高复合材料的导热性能;用Nielsen理论模型预测石墨、炭纤维填充TPI材料导热系数与实验值存在一定偏差;采用有限元法模拟二维复合材料稳态导热行为,能有效地预测复合材料的导热系数。基于材料内部热流分布模拟分析发现,填料自身导热性能对复合材料导热行为的影响不明显;与圆形填料相比,方形填料改善材料导热性能效果显著。

The thermal conductivity of graphite, carbon fiber modified thermoplastic polyimide was measured, and the effects of the filler content on the mechanical properties and thermal conductivity were investigated. The behaviors of the thermal conduction of TPI composites were simulated by the Nielsen model and finite element method （FEM）, and the shape of the filler was also considered. The results indicate that thermal conductivity of the materi- al is improved obviously by increasing the filler content. The difference between the calculated data by Nielsen model and experimental data is unacceptable. The behaviors of the thermal conduction of TPI composites at the steady state could be simulated properly by FEM. Based on an analysis of the thermal flux in unit of composites, it is found that the influence of the filler thermal conductivity on the composites thermal behavior is not obvious, and the thermal conductivity of the composite with the rectangle filler is much higher than that with rotundity filler.