Guo Haichang, Niu Hongyu, Zhao Haoyuan, Kang Lei, Ren Yanjuan, Lv Ruicong, Ren Liucheng, Maqbool Muhammad, Bashir Akbar, Bai Shulin
School of Materials Science and Engineering, HEDPS, Center for Applied Physics and Technology, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Peking University, Beijing 100871, China.
National Synchrotron Radiation Laboratory, Anhui Provincial Engineering Laboratory of Advanced Functional Polymer Film, CAS Key Laboratory of Soft Matter Chemistry, University of Science and Technology of China, Hefei 230026, China.
ACS Appl Mater Interfaces. 2022 Mar 30;14(12):14568-14578. doi: 10.1021/acsami.1c23944. Epub 2022 Mar 18.
Extrusion-based three-dimensional (3D) printing techniques usually exhibit anisotropic thermal, mechanical, and electric properties due to the shearing-induced alignment during extrusion. However, the transformation from the extrusion to stacking process is always neglected and its influence on the final properties remains ambiguous. In this work, we adopt two different sized boron nitride (BN) sheets, namely, small-sized BN (S-BN) and large-sized BN (L-BN), to explore their impact on the orientation degree, morphology, and final anisotropic thermal conductivity (TC) of thermoplastic polyurethane (TPU) composites by fused deposition modeling. The transformation from one-dimensional axial alignment in the extruded filament to two-dimensional alignment (horizontal and vertical alignment) in the stacking filament of BN sheets is observed, and its impact on anisotropic TC in three directions is clarified. It is found that L-BN/TPU composites show a high TC of 6.45 W m K at 60 wt % BN content along the printing direction, while at a lower content (<40 wt %), S-BN/TPU composites exhibit a higher TC than L-BN/TPU composites. Effects of orientation, viscosity, and voids are comprehensively considered to elucidate such differences. Finally, heat dissipation tests demonstrate the great potential of 3D printed BN/TPU composites to be used in thermal management applications.
基于挤出的三维（3D）打印技术由于挤出过程中剪切诱导的取向，通常表现出各向异性的热、机械和电学性能。然而，从挤出到堆叠过程的转变一直被忽视，其对最终性能的影响仍不明确。在这项工作中，我们采用两种不同尺寸的氮化硼（BN）片材，即小尺寸BN（S-BN）和大尺寸BN（L-BN），通过熔融沉积建模来探索它们对热塑性聚氨酯（TPU）复合材料的取向度、形态和最终各向异性热导率（TC）的影响。观察到从挤出长丝中的一维轴向取向到BN片材堆叠长丝中的二维取向（水平和垂直取向）的转变，并阐明了其对三个方向上各向异性TC的影响。结果发现，在60 wt%的BN含量下，L-BN/TPU复合材料沿打印方向显示出6.45 W m K的高热导率，而在较低含量（<40 wt%）时，S-BN/TPU复合材料表现出比L-BN/TPU复合材料更高的热导率。综合考虑取向、粘度和孔隙率的影响来解释这种差异。最后，散热测试证明了3D打印的BN/TPU复合材料在热管理应用中的巨大潜力。
