Wang Xinyu, Guo Yandong, Su Junfeng, Zhang Xiaolong, Wang Yingyuan, Tan Yiqiu
School of Mechanical Engineering, Tianjin University of Commerce, Tianjin 300134, China.
Department of Polymer Material, School of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, China.
Nanomaterials (Basel). 2018 Jun 9;8(6):419. doi: 10.3390/nano8060419.
Self-healing bituminous material has been a hot research topic in self-healing materials, and this smart self-healing approach is a promising a revolution in pavement material technology. Bitumen has a self-healing naturality relating to temperature, healing time, and aging degree. To date, heat induction and microencapsulation rejuvenator are two feasible approaches, which have been put into real applications. However, both methods have disadvantages limiting their practical results and efficiency. It will be an ideal method combining the advantages and avoiding the disadvantages of the above two methods at the same time. The aim of this work was to synthesize and characterize electrothermal self-healing microcapsules containing bituminous rejuvenator with graphene/organic nanohybrid structure shells. The microcapsules owned electric conductivity capability because of the advent of graphene, and realized the self-healing through the two approaches of heat induction and rejuvenation. The microcapsule shells were fabricated using a strength hexamethoxymethylmelamine (HMMM) resin and graphene by two-step hybrid polymerization. Experimental tests were carried out to character the morphology, integrity, and shell structure. It was found that the electric charge balance determined the graphene/HMMM microstructure. The graphene content in shells could not be greatly increased under an electrostatic balance in emulsion. X-ray photoelectron spectroscopy (XPS), Energy dispersive spectrometer (EDS), Transmission electron microscope (TEM) and Atomic force microscopy (AFM) results indicated that the graphene had deposited on shells. TGA/DTG tests implied that the thermal decomposition temperature of microcapsules with graphene had increased to about 350 °C. The thermal conductivity of microcapsules had been sharply increased to about 8.0 W/m²·K with 2.0 wt % graphene in shells. At the same time, electrical resistivity of microcapsules/bitumen samples had a decrease with more graphene in bitumen.
自愈合沥青材料一直是自愈合材料领域的研究热点，这种智能自愈合方法有望给路面材料技术带来一场变革。沥青具有与温度、愈合时间和老化程度相关的自愈合特性。迄今为止，热诱导和微胶囊再生剂是两种可行的方法，并且已经投入实际应用。然而，这两种方法都存在缺点，限制了它们的实际效果和效率。将上述两种方法的优点结合起来，同时避免其缺点，将是一种理想的方法。这项工作的目的是合成并表征具有石墨烯/有机纳米杂化结构壳层、含有沥青再生剂的电热自愈合微胶囊。由于石墨烯的存在，这些微胶囊具有导电能力，并通过热诱导和再生这两种方法实现自愈合。微胶囊壳层采用六甲氧基甲基三聚氰胺（HMMM）树脂和石墨烯通过两步杂化聚合制备而成。进行了实验测试以表征其形态、完整性和壳层结构。研究发现，电荷平衡决定了石墨烯/HMMM的微观结构。在乳液的静电平衡下，壳层中的石墨烯含量无法大幅增加。X射线光电子能谱（XPS）、能量色散谱仪（EDS）、透射电子显微镜（TEM）和原子力显微镜（AFM）结果表明，石墨烯已沉积在壳层上。热重分析/微商热重分析（TGA/DTG）测试表明，含有石墨烯的微胶囊的热分解温度已提高到约350℃。当壳层中石墨烯含量为2.0 wt%时，微胶囊的热导率急剧增加到约8.0 W/m²·K。同时，微胶囊/沥青样品的电阻率随着沥青中石墨烯含量的增加而降低。
