Viscosity Property of Methylene Diphenyl Diisocyanate Modified Asphalt Based on Molecular Dynamics Simulation

Methylene diphenyl diisocyanate (MDI), a common chemical raw material, can greatly improve the high-temperature performance of asphalt. The viscosity of MDI-modified asphalt needs further study. MDI-modified asphalt models were constructed and confined through a molecular dynamic simulation to investigate the effect of the macromolecules of the nucleophilic addition reaction on the modification. It was found that the viscosity of matrix asphalt changes little with the increase of temperature. MDI-modified asphalt with double pyrrole behaves similarly except that the shear viscosity of the latter was larger with increasing temperature. However, the two models containing asphaltene-phenol both showed higher viscosity-temperature sensitivity at temperatures of 368K-383K. Double phenol or phenol-pyrrole may play a role in increasing viscosity in MDI-modified asphalt.