Yu Caihua, Yang Qilin
Tongji University, College of Civil Engineering, Department of Structural Engineering, Shanghai 200092, P. R. China.
Harbin Institute of Technology, School of Transportation Science & Engineering, Harbin 150090, P. R. China.
Langmuir. 2023 Oct 3;39(39):14102-14118. doi: 10.1021/acs.langmuir.3c01926. Epub 2023 Sep 18.
Understanding the mechanisms of oxidative aging effects on the carbon nanotube (CNT)-asphalt nanocomposite interface has long been a challenge, as there are two opposing effects: enhancement and deterioration. In this study, a multiscale coupling method is proposed to analyze the dual effect of oxidative aging on the CNT-asphalt nanocomposite. The method is based on density functional theory (DFT) and molecular dynamics (MD) simulations, supported by microscopic interface observation and macroscopic property testing with a focus on the composite interface. The results show that oxidative aging has a resetting effect on benzene ring stacking at the interface and enhances the binding energy of CNT-asphalt. Meanwhile, oxidative aging enhanced the interfacial charge transfer, but no chemical reaction occurred between CNT-aged asphalt. This is also verified by Fourier Transform Infrared Spectroscopy (FTIR). Enhancement and degeneration effects of oxidative aging occur via distinct mechanisms. Oxidative aging enhanced the interfacial shear barrier by approximately 5% and the energy barrier by 44.87%, which increased the high-temperature deformation resistance of the CNT-asphalt nanocomposites. However, molecular oxidation was not responsible for the decline in the fatigue resistance. According to scanning electron microscopy (SEM) and atomic force microscopy (AFM) results, oxidative aging elevates the content of polar molecules, leading to an increase in the solid properties of asphalt and a 39.6% decrease in surface adhesion. This disrupts the three-dimensional network of the CNT and ultimately leads to a reduction in crack resistance. This study clarifies the mechanism underlying the dual effect of oxidative aging and provides fundamental support for understanding asphalt aging behavior and the interfacial behavior of composites.
长期以来，理解氧化老化对碳纳米管（CNT）-沥青纳米复合材料界面的影响机制一直是一项挑战，因为存在两种相反的效应：增强和劣化。在本研究中，提出了一种多尺度耦合方法来分析氧化老化对CNT-沥青纳米复合材料的双重效应。该方法基于密度泛函理论（DFT）和分子动力学（MD）模拟，并辅以微观界面观察和宏观性能测试，重点关注复合材料界面。结果表明，氧化老化对界面处的苯环堆积具有重置作用，并增强了CNT-沥青的结合能。同时，氧化老化增强了界面电荷转移，但CNT与老化沥青之间未发生化学反应。这也通过傅里叶变换红外光谱（FTIR）得到了验证。氧化老化的增强和退化效应通过不同的机制发生。氧化老化使界面剪切屏障提高了约5%，能量屏障提高了44.87%，这增加了CNT-沥青纳米复合材料的高温抗变形能力。然而，分子氧化并非导致疲劳抗性下降的原因。根据扫描电子显微镜（SEM）和原子力显微镜（AFM）的结果，氧化老化提高了极性分子的含量，导致沥青的固体性能增加，表面粘附力下降39.6%。这破坏了CNT的三维网络，最终导致抗裂性降低。本研究阐明了氧化老化双重效应的潜在机制，并为理解沥青老化行为和复合材料的界面行为提供了基础支持。
