Double Effects of Oxidative Aging on Carbon Nanotube–Asphalt Nanocomposite Interfaces: Enhancement and Deterioration

Abstract

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.

Titanium Dioxide and Calcium Sulfate Whiskers Are Used for the Preparation of High Performance Polypropylene and Reduce White Pollution

“…Additionally, exposure to oxygen leads to the creation of new radicals that react with other hydrogen atoms in the chain, causing PP to lose its original properties. This can result in a decrease in mechanical properties, yellowing, and a reduction in viscosity. − This phenomenon not only confines the range of application of PP products but also considerably reduces their lifespan, resulting in unnecessary waste and environmental pollution, and significantly disturbs the ecological balance. − When white pollution originating from waste is disposed of at landfill sites and in general environments, it typically undergoes a series of aging processes when exposed to solar UV radiation, − such as physical wear and erosion, − thermal oxidation degradation, and biodegradation, − all of which trigger crack propagation and fragmentation of polymers, known as “microplastics”, which exist in freshwater, sediment, marine environments, and biota, − posing an ecotoxicological threat to aquatic environments and organisms. , In addition, high-performance PP, which is required for specific engineering fields, is a costly material. Therefore, it is necessary to utilize low-cost raw materials and simple processing technologies to produce high-performance PP.…”