Study on the diffusion behaviour of styrene-butadiene rubber modifier and asphalt components based on molecular dynamics simulation

To reveal the mechanism of interaction between styrene−butadiene rubber (SBR) modifier and asphalt components, the molecular dynamics (MD) method was used to study the diffusion behaviour at different temperatures. The diffusion behaviour was discussed using radial distribution function (RDF), mean square displacement (MSD), and relative concentration (RC). Interaction energy was used to verify the accuracy of the simulations. The simulated results indicate that the order of the four asphalt components prone to aggregation with SBR is as follows: saturated >aromatics >asphaltene >resins. The interaction between SBR modifier and asphalt components affects the diffusion of asphalt components. At 160°C, the distribution of components is the most uniform. When the temperature is too low or too high, the components dissociate from each other. The results of interaction energy are consistent with the conclusion. This study reveals the mechanism of component interaction of SBR modified asphalt.