Abstract Graphene holds promise to provide polymers with multifunctionality such as electrical conductivity. However, pristine graphene is not processable in solvent and graphene oxide even after reduction lacks sufficient electrical conductivity and compatibility with polymers. This work reported an epoxy/graphene nanocomposite film that was synthesized by a facile approach, taking advantage of unique solution-processable graphene platelets (GnPs) that had high structural integrity as reflected by electrical conductivity of 1460 S/cm. A percolation threshold of electrical conductivity was found to be 0.63 vol% for the film. GnPs at 2 vol% improved the thermal conductivity and Young's modulus of epoxy by 117% and 101%, respectively. The film was then investigated as a multifunctional sensor. It can real-time monitor its lifecycle structure health, i.e. the measurement of not only curing parameters but the initiation, localization and evolution of damages spanning from curing to the end of service life. Being sensitive to ambient environmental temperature, the film was investigated as a thermal sensor. Its performance as a strain sensor proved satisfactory through a 20,000-cyclic fatigue test. The film not only self-sensed damage such as cracks but mapped out the corresponding locations. This methodology could lead to the development of cost-effective, high-performance sensors for life-cycle, self-sensing health monitoring for various bonding structures.

中文翻译：

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用于生命周期自感应和多功能应用的环氧树脂/石墨烯薄膜

摘要 石墨烯有望为聚合物提供多功能性，例如导电性。然而，即使在还原后，原始石墨烯也不能在溶剂和氧化石墨烯中加工，缺乏足够的导电性和与聚合物的相容性。这项工作报告了一种环氧树脂/石墨烯纳米复合薄膜，该薄膜利用独特的可溶液加工石墨烯薄片 (GnPs) 的简单方法合成，该薄片具有高结构完整性，如电导率 1460 S/cm 所反映。发现薄膜的导电性渗透阈值为 0.63 体积％。2 vol% 的 GnP 将环氧树脂的热导率和杨氏模量分别提高了 117% 和 101%。然后将该膜作为多功能传感器进行研究。它可以实时监控其生命周期结构健康状况，即不仅测量固化参数，还测量从固化到使用寿命结束的损坏的发生、定位和演变。由于对周围环境温度敏感，因此该薄膜被用作热传感器。通过 20,000 次循环疲劳试验证明其作为应变传感器的性能令人满意。这部电影不仅可以自我感知裂缝等损坏，而且还绘制了相应的位置。这种方法可以导致开发具有成本效益的高性能传感器，用于各种粘合结构的生命周期、自感应健康监测。由于对周围环境温度敏感，因此该薄膜被用作热传感器。通过 20,000 次循环疲劳试验证明其作为应变传感器的性能令人满意。这部电影不仅可以自我感知裂缝等损坏，而且还绘制了相应的位置。这种方法可以导致开发具有成本效益的高性能传感器，用于各种粘合结构的生命周期、自感应健康监测。由于对周围环境温度敏感，因此该薄膜被用作热传感器。通过 20,000 次循环疲劳试验证明其作为应变传感器的性能令人满意。这部电影不仅可以自我感知裂缝等损坏，而且还绘制了相应的位置。这种方法可以导致开发具有成本效益的高性能传感器，用于各种粘合结构的生命周期、自感应健康监测。