Aligning multilayer graphene flakes with an external electric field to improve multifunctional properties of epoxy nanocomposites
Aligning multilayer graphene flakes with an external electric field to improve multifunctional properties of epoxy nanocomposites
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DOI：
10.1016/j.carbon.2015.07.026
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发表时间：
2015-11-01
期刊：
影响因子：
10.9
通讯作者：
Wang, Chun H.
中科院分区：
文献类型：
--
作者：
Wu, Shuying;Ladani, Raj B.;Wang, Chun H.
对多功能聚合物纳米复合材料的需求日益增长，要求同时提高机械、电气和热性能的新技术。本文介绍了使用交流电场在环氧聚合物中排列石墨烯纳米片（GnPs）。对准过程的理论建模确定了控制GnPs旋转和成链的关键参数。实验结果表明，制备的纳米复合材料具有各向异性，取向方向上的电导率和导热系数显著提高，断裂韧性显著提高。特别是，与未改性的环氧聚合物相比，GnPs的排列使导电性提高了约7-8个数量级，导热性提高了约60%，I型断裂韧性提高了近900%。断裂韧性的显著提高归因于多种内在和外在的增韧机制，包括微裂纹、钉住、裂纹的挠曲和分支，以及GnPs的断裂和拔出。这种韧性的主要改善是由于GnPs与裂纹扩展方向横向排列，显示出与裂纹尖端推进的相互作用增加。(C) 2015年作者。Elsevier Ltd.出版。
The increasing demand for multifunctional polymer nanocomposites calls for new technologies to simultaneously enhance mechanical, electrical, and thermal properties. This paper presents the use of an alternating-current electric field to align graphene nanoplatelets (GnPs) in an epoxy polymer. Theoretical modeling of the alignment process has identified the key parameters that control the rotation and chain-formation of the GnPs. Experimental results reveal that the resulting nanocomposites exhibit anisotropic properties with significantly improved electrical and thermal conductivities in the alignment direction, and dramatically increased fracture toughness when the GnPs are aligned transverse to the crack growth direction. In particular, compared to the unmodified epoxy polymer, the alignment of the GnPs yields up to about 7-8 orders of magnitude improvement in the electrical conductivity, up to approximately 60% increase in the thermal conductivity, and up to a nearly 900% increase in the mode I fracture toughness. The dramatic improvement in the fracture toughness is attributed to multiple intrinsic and extrinsic toughening mechanisms including microcracking, pinning, deflection and branching of the crack, and rupture and pull-out of the GnPs. Such major improvement in the toughness arises from GnPs being transversely aligned to the crack growth direction exhibiting increased interactions with the advancing crack tip. (C) 2015 The Authors. Published by Elsevier Ltd.