Abstract The development of scalable Out-of-Autoclave (OoA) in-situ thermoset curing methods are required to overcome important drawbacks related to the autoclave-based processing methods typically used in industry. The incorporation of graphene, an electrothermal carbon nanomaterial with the ability to transform electric energy into heat through Joule heating, emerges as a promising route to replace the conventional processing methods. In this work the electrical behaviour of both uncured and oven cured GNPs/epoxy composites with loadings of up to 10 wt% were evaluated and electrical percolation thresholds were established for both. Above the critical loading found for oven cured materials (∼8.5 wt%) the electrically conducting networks of GNPs formed in the matrix showed the ability to act as integrated nanoheaters when an electric current was passed through them, successfully curing the composites by Joule heating. Composites prepared by this OoA curing method (as an alternative to the traditional oven based one) at 10 wt% loading of GNPs were also prepared and compared to the oven cured ones. They showed more compact composite structures, with less microvoids and a preferred orientation of the GNPs in the matrix relative to the oven cured material at identical loading, as revealed by electron microscopy and polarized Raman spectroscopy, respectively. This microstructure and anisotropy induced by the electrically-induced (i.e. OoA) cure led to GNPs/epoxy composites with superior electrical and mechanical properties (revealed by tensile testing). The well-distributed GNP nanoparticles acting as nanoheaters integrated in a thermosetting matrix, in combination with excellent mechanical and electrical performances achieved for the overall graphene/epoxy composites and the simplicity associated to the method, should open the door to novel industrial applications.

中文翻译：

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用于通过焦耳加热进行高压釜外热固性固化的导电 GNP/环氧树脂复合材料

摘要 需要开发可扩展的非高压釜 (OoA) 原位热固性固化方法，以克服与工业中通常使用的基于高压釜的加工方法相关的重要缺点。石墨烯是一种能够通过焦耳加热将电能转化为热能的电热碳纳米材料，它的加入是替代传统加工方法的一种有前景的途径。在这项工作中，评估了负载高达 10 wt% 的未固化和烘箱固化 GNP/环氧树脂复合材料的电性能，并为两者建立了电渗透阈值。高于烘箱固化材料的临界载荷（~8. 5 wt%) 在基体中形成的 GNP 导电网络显示出当电流通过它们时充当集成纳米加热器的能力，通过焦耳加热成功固化复合材料。还制备了通过这种 OoA 固化方法（作为传统烤箱基方法的替代）以 10 wt% 的 GNP 负载量制备的复合材料，并与烤箱固化的复合材料进行了比较。电子显微镜和偏振拉曼光谱分别显示，它们显示出更紧凑的复合结构，具有更少的微孔洞和基体中 GNP 相对于相同负载的烘箱固化材料的优先取向。这种微结构和各向异性是由电感应引起的（即 OoA) 固化导致 GNP/环氧树脂复合材料具有优异的电气和机械性能（通过拉伸测试显示）。分布良好的 GNP 纳米粒子作为集成在热固性基质中的纳米加热器，结合整体石墨烯 / 环氧树脂复合材料获得的优异机械和电气性能以及与该方法相关的简单性，应该为新型工业应用打开大门。