Preparation and 3D printing of high-thermal-conductivity continuous mesophase-pitch-based carbon fiber/epoxy composites

To meet the requirements of spacecraft for the thermal conductivity of resins and solve the problem of low thermal conduction efficiency when 3D printing complex parts, we propose a new type of continuous mesophase-pitch-based carbon fiber/thermoplastic polyurethane/epoxy (CMPCF/TPU/epoxy) composite filament and its preparation process in this study. The composite filament is based on the high thermal conductivity of CMPCF, the high elasticity of TPU, and the high-temperature resistance of epoxy. The tensile strength and thermal conductivity of the CMPCF/TPU/epoxy composite filament were tested. The CMPCF/TPU/epoxy composites are formed by 3D printing technology, and the composite filament is laid according to the direction of heat conduction so that the printed part can meet the needs of directional heat conduction. The experimental results show that the thermal conductivity of the printed sample is 40.549 W/(m·K), which is 160 times that of pure epoxy resin (0.254 W/(m·K)). It is also approximately 13 times better than that of polyacrylonitrile carbon fiber/epoxy (PAN-CF/epoxy) composites. This study breaks through the technical bottleneck of poor printability of CMPCF. It provides a new method for achieving directional thermal conductivity printing, which is important for the development of complex high-performance thermal conductivity products. 目的 为满足航天器对树脂导热性能的要求, 解决3D 打印复杂零件时导热效率低的问题, 本研究提出一种新型连续 中间相沥青基碳纤维/热塑性聚氨酯/环氧树脂(CMPCF/TPU/epoxy)复合长丝并介绍其制备工艺。 创新点 1. 该复合长丝的制备基于连续中间相沥青基碳纤维(CMPCF)的高导热性能、热塑性聚氨酯(TPU)的高弹 性和环氧树脂(epoxy)的耐高温性能。2. 沿导热方向打印长丝, 并提出热固性复合丝材打印件的新固化方式。 方法 1. 采用上浆剂法进行表面上浆, 选取水溶性聚氨酯作为表面上浆剂, 提升连续中间相沥青基碳纤维聚束性。2. 通过增韧预处理, 选取TPU 作为增韧基体材料, 在上浆后的碳纤维束外包裹一层具有高韧性高强度的树脂层。 3. 采用浸涂处理工艺, 选取固态环氧树脂, 成功制备出高导热CMPCF/TPU/epoxy 复合丝材。4. 沿导热方向规 划打印路径并进行打印测试, 验证复合长丝的可打印性和打印件的导热系数。 结论 1. 通过对CMPCF 进行表面上浆、增韧预处理和预浸处理, 成功制备出高导热性能的CMPCF/TPU/epoxy 复合 长丝; 在CMPCF 外包裹TPU, 解决了CMPCF 因脆性而难以打印的问题。2. 3D 打印使纤维沿导热方向铺设, 为制备具有高导热系数的复杂打印件提供了一种新方法。3. 导热系数测试表明, 当CMPCF 体积含量仅为6.6% 时, 复合材料的导热系数为40.549 W/(m·K), 是纯环氧树脂的160 倍, 是聚丙烯腈基碳纤维(PAN-CF)体积 为14.6%时复合材料的13 倍, 因此CMPCF 的加入明显提高了打印件的导热性能。