The phase field method coupled with molecular dynamics parameter for simulating phase separation behavior of SBS modified asphalt

Polymer-modified asphalt is a thermodynamically unstable system, in which the polymer and asphalt are prone to phase separation. Due to the inadequacy of characterization methods for phase separation, this field has not been thoroughly understood or explored. This paper introduces an innovative methodology by employing a simulation approach that couples phase-field theory with molecular dynamics parameters. Using SBS polymer-modified asphalt as an example, validate the method's applicability and establish a more precise parameter library for the phase separation field model of SBS-modified asphalt. The phase separation process of SBS-modified asphalt was simulated. In combination with fluorescence microscopy experiments, the evolution of the micro and meso-phase states of the modified asphalt over time was established and tracked. Results indicate that higher light component content and lower heavy component content in asphalt improve its compatibility. Migration coefficients and interaction parameters for the phase field model were determined, and a more accurate correction factor for the entropy contribution of SBS-modified asphalt was estimated. The phase-field model shows that higher light component content and lower heavy component content result in slower and smaller phase separation, leading to better compatibility. The combined phase field and molecular dynamics simulations accurately reproduce experimental findings from fluorescence microscopy, providing theoretical references for studying phase separation in polymers.