基于分子动力学模拟的生物油改性沥青自愈合机理研究OA

[Purposes]This paper aims to elucidate the mechanism by which biomass-derived oil(hereafter referred to as bio-oil)influences the self-healing performance of asphalt at the molecular level.[Methods]Molecular models of base asphalt,waste cooking oil-modified asphalt,and coconut oil-modified asphalt were constructed using Materials Studio software based on a four-component model.The rationality of these models was validated through parameters including density,cohesive energy density,and solubility parameter.Subsequently,self-healing models for the three types of asphalt were established,and molecular dynamics simulations were performed for 200 ps under four temperature conditions at one standard atmosphere within the NPT ensemble.Based on the simulation results,the healing performance of the asphalt was evaluated using density and diffusion coefficient,while the activation energy and frequency factor of the healing reaction were calculated according to the Arrhenius equation.[Results]The results indicate that waste cooking oil exhibits a stronger enhancing effect on the diffusion coefficient of asphalt,with an increase ranging from 32.79%to 77.03%,whereas coconut oil leads to an increase ranging from 15.22%to 44.59%on the diffusion coefficient of asphalt.The addition of bio-oil slightly increases the activation energy of the asphalt condensation reaction,with waste edible oil and coconut oil raising the activation energy by 10.36%and 13.52%respectively.Meanwhile,both waste cooking oil and coconut oil significantly increased the frequency factor of the self-healing reaction,with corresponding increases of 219.44%and 150.25%,respectively.This demonstrates that the core effect of bio-oil is a substantial increase in the self-healing reaction rate.[Conclusions]This study clarifies,at the molecular level,the key mechanism by which bio-oil improves the self-healing performance of asphalt:The incorporation of bio-oil molecules effectively disrupts the aggregation state of asphaltenes,providing diffusion pathways for other components.This,in turn,significantly enhances the overall molecular diffusion capacity and self-healing rate of the asphalt system.