Effects of Polymer Modification on Properties and Microstructure of Model Asphalt Systems

Physical properties and microstructures of computational model asphalts were investigated using molecular dynamics simulations in an all-atom framework. A new model asphalt is proposed that is targeted toward core asphalt AAA-1 of the Strategic Highway Research Program (SHRP) based on elemental composition and speciation. Individual compounds were chosen from the literature to represent asphaltene, polar aromatic, naphthene aromatic, and saturate, with interactions ranked using Hansen solubility parameters. The density and thermal expansion coefficient agreed better with experimental data than had predictions using earlier model asphalts. In addition, one polystyrene molecule with 50 repeat units was added into a ternary model asphalt from earlier work and the new six-component AAA-1 model system to analyze polymer modification effects. The expansion coefficient, isothermal compressibility, and their temperature dependence decreased with one polymer chain present, while density increased. Self-diffusion c...