The nanoscale tensile behavior of polyaspartate polyurea: A coarse-grained molecular dynamics simulation study

Polyaspartate polyurea can be applied in concrete enhancement, where its mechanical properties in different tension states are key to achieving the desirable enhancing effect. In this study, the coarse-grained (CG) model of amorphous polyaspartate polyurea and equivalent interactions were developed, and its nanoscaled mechanical behaviors under tensile, succssive cyclic tensile, and stress relaxation were simulated. The CG model, with significantly reduced freedom degrees, has almost the same glass transition temperature and density as the full- atomic one. The unixial tension mechanical properties of the CG model varies with the strain rate. With the increasing strain rate, the yield strength increases, whereas the yield strain declines. The deformation of the model is primarily caused by slippage of beads and bending of bond angles. Under successive loading-reloading cyclic tension, the model performs with stress memory behavior, and the viscous strain happens when the strain of unloading is equal to or exceeds 0.5. Under stress relaxation, the axial stress declines with the increasing time, and its evolution is primarily caused by the varied van der Waals interactions.