Mechanical performance analysis of polyurethane‐modified asphalt using molecular dynamics method

Abstract

In this study, the mechanical performance of polyurethane (PU)‐modified asphalt was investigated. To this end, the molecular dynamics method was adopted to study the influence of the PU modifier on the compatibility, mechanical properties, and structure of asphalt. Using the Materials Studio software, a four‐component molecular model of asphalt, a PU molecular model, and an asphalt–PU mixed system model were constructed, and the molecular density and glass transition temperature (Tg) were used to verify the performance of the aforementioned models. Molecular dynamics simulations of the three molecular models were conducted under different temperatures, and the solubility parameter (δ), interaction energy, mechanical properties, and radial distribution functions (RDFs) were obtained. The results showed that at 413.15 K (140°C), the difference between the solubility parameters of the asphalt and PU molecules (∆δ) is the smallest, and their interaction reaches the most optimal phase state. The effects of the PU modifier on the Young's modulus, bulk modulus, and shear modulus of asphalt were studied. Finally, the RDF analysis showed that the PU modifier has a direct effect on the degree of swelling and dispersion between the aromatic–aromatic and saturate–saturate components in the asphalt, reducing the aggregation of both molecules. This verifies the PU modification effect.

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