Tengbo Ma, Kunpeng Ruan, Yongqiang Guo*, Yixin Han and Junwei Gu*. Controlled length and number of thermally conductive pathways for copper wire/poly(lactic acid) composites via 3D printing. SCIENCE CHINA Materials, 2023, doi.org/10.1007/s40843-023-2540-9. 2022IF=8.1.

https://www.sciengine.com/SCMs/doi/10.1007/s40843-023-2540-9

Abstract

Thermal conduction pathways play a crucial role in understanding the thermal behavior of thermally conductive polymer composites, yet there is a lack of in-depth research on the mechanism of how the properties of thermal conduction pathways (length, number) affect the thermal conductivity of polymer composites. In this study, one-dimensional copper wire/poly(lactic acid) (1D Cw/PLA) thermally conductive composites with controllable length and quantity of copper wire (Cw) thermal conduction pathways were fabricated using 3D printing technology. A thermal conduction model for polymer composites with one-dimensional thermal conduction pathways was established, elucidating the quantitative relationship between the properties of thermal conduction pathways and their thermal performance. With the same Cw content, the in-plane thermal conductivity (λ//) of 1D Cw/PLA thermally conductive composites is positively correlated with the number and length of thermal conduction pathways. When the Cw volume fraction is 25.1 vol%, the λ// of the 1D Cw/PLA thermally conductive composites containing 20 Cw intact thermal conduction pathways can reach up to 4.23 W/(m·K), which is 87.2% higher than the λ// of the 1D Cw/PLA thermally conductive composites without Cw intact thermal conduction pathways (2.26 W/(m·K)), 72.0% higher than the λ// of the 1D Cw/PLA thermally conductive composites containing short Cw (2 intact Cw, 18 broken at 1/2 point Cw) (2.46 W/(m·K)), and 1527% higher than the λ// of the pure PLA matrix (0.26 W/(m·K)). Using the thermal conduction model and empirical equations constructed in this study, the thermal conductivity of 1D Cw/PLA composites was predicted, and it was found that there was no significant difference between the predicted values and the measured values at a 95% confidence level.

导热通路对理解导热高分子复合材料的导热行为至关重要，但目前有关导热通路属性（长度、数量）对高分子复合材料导热系数的影响机制缺乏深入的研究。本文采用3D打印技术制备了铜线（Cw）导热通路长度和数量可控的一维铜线/聚乳酸（1D Cw/PLA）导热复合材料，建立了针对一维导热通路的高分子复合材料的导热模型，明晰了其导热通路属性与其导热性能的定量关系。相同Cw用量下，1D Cw/PLA导热复合材料的面内导热系数（λ//）与导热通路的数量和长度成正相关。当Cw体积分数为25.1 vol%时，含20根Cw贯穿导热通路的1D Cw/PLA导热复合材料的λ//最高可达4.23 W/(m·K)，比相同Cw用量下不含Cw贯穿导热通路的1D Cw/PLA导热复合材料λ//（2.26 W/(m·K)）高87.2%，比相同Cw用量下含短Cw（2根贯穿的Cw，18根在1/2处被打断的Cw）的1D Cw/PLA导热复合材料的λ//（2.46 W/(m·K)）高72.0%，较纯PLA基体的λ//（0.26 W/(m·K)）提高了1527%。采用本文构建的导热模型和经验方程对1D Cw/PLA复合材料的导热系数进行预测，95%的置信度认为预测值与实测值无显著差异。

论文亮点

1. 采用3D打印技术制备了导热通路长度和数量可控的一维铜线/聚乳酸（1D Cw/PLA）导热复合材料，明晰了导热通路长度和数量与导热系数的定量关系。

2. 相同Cw用量下，1D Cw/PLA导热复合材料的λ//与导热通路的数量和长度成正相关。当Cw体积分数为25.1 vol%时，含贯穿导热通路的1D Cw/PLA导热复合材料的λ//最高可达4.23 W/(m·K)，较纯PLA基体的λ//（0.26 W/(m·K)）提高了1527%。

3. 95%的置信度认为采用本文建立的导热模型和经验方程预测的导热系数与实测值无显著差异。

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