Compounding Optimization of SBS-SBR High-Viscosity Modifier and Rejuvenation of Aged SBS-SBR Modified Asphalt

Abstract In this paper, the modification effects of the styrene-butadiene rubber (SBR) high-viscosity modifier (HVM) with different monomer compositions and the HVMs with different styrene-butadiene-styrene block copolymer (SBS)-SBR compound ratios were explored. On this basis, the rejuvenation effects of representative rejuvenator components on slightly and severely aged high-viscosity asphalt (HVA) were studied through molecular dynamics simulations. The results show that when the proportion of 1,4-polybutadiene in the SBR molecule remains unchanged, increasing the proportion of cis-1,4-polybutadiene is slightly disadvantageous to its compatibility with the matrix asphalt, while the mechanical properties of the prepared HVA are less affected. Increasing the content of 1,2-polybutadiene and polystyrene monomer in the SBR molecule is not conducive to its compatibility with the matrix asphalt, but it increases the mechanical properties of the prepared HVA. When the compound ratio is between 4 % SBS + 8 % SBR and 8 % SBS + 4 % SBR, both the diffusion state of the modifier in the matrix asphalt and the compatibility of the compound HVM with the matrix asphalt are the best, and it is most conducive to the cross-linked structure formation between the HVM and matrix asphalt. Among the representative rejuvenator molecules, p-xylene has the strongest interaction with aged HVA and it has the strongest permeability in aged HVA. Nonanal is most conducive to improve the self-aggregation of asphaltenes in aged HVA. During the miscibility stage, n-hexane molecules are more likely to appear around the aged HVA molecules, which is beneficial to the rejuvenator to repair and improve the performance of the aged HVA and form a stable structure. The research results provide references for the monomer optimization of SBR HVM, the determination of the optimal compound ratio of SBS-SBR modifier, and the rejuvenation of HVA.