Molecular dynamics simulation study on the performance of aged SBS modified asphalt rejuvenated from colza oil and dodecenyl succinic anhydride

Through molecular dynamics simulation and experimental verification, this study systematically explored the recovery mechanism of colza oil (CO) and dodecenyl succinic anhydride (DDSA) on the performance of aging SBS modified asphalt (ASBSMA). The molecular model including SBSMA, ASBSMA and their rejuvenation system and the asphalt–asphalt bilayer interface model were constructed. The key parameters such as density, cohesive energy density (CED), diffusion coefficient, free volume fraction (FFV), relative concentration and interaction energy were analysed. The results show that CO enhances the diffusivity and compatibility of aged asphalt by supplementing light components and weakening the aggregation effect of the aged asphalt. DDSA repaired the broken SBS molecular chain through esterification reaction and restored its network structure. The combined use of CO and DDSA produced a combined effect, resulting in recovery of FFV and diffusion coefficient. Fourier transform infrared spectroscopy (FTIR) further confirmed that CO enhanced the flexibility of asphalt and DDSA was involved in chemical reaction to repair SBS chain structure. This study provides molecular-level insights into the combined rejuvenation mechanism of ASBSMA by CO and DDSA, offering a theoretical basis for the rational design of rejuvenator systems from a molecular perspective.