Molecular Dynamics Simulation on Effect of Temperature and Pressure on Viscoelasticity of Polyurethane Elastomers

In this work, the effect of temperature and pressure on the viscoelasticity of the polyurethane elastomers is investigated via a coarse-grained molecular dynamics simulation. It is found that the storage modulus and loss modulus of polyurethane gradually decrease with the increase of temperature while the loss factor rises. The effect of pressure on the viscoelastic properties of polyurethane is opposite to that of temperature. Moreover, the loss factor of polyurethane is nearly independent of pressure. Then, the interaction energy, the order parameter and size of phases, the reduced interaction energy and heat exchange energy are calculated to understand the microscopic mechanism of the polyurethane viscoelasticity. The results show that the phase structures are mainly deformed during the shearing process, which produces more interfaces. In addition, the slippage between hard phase and soft phase beads becomes easier at a higher temperature or a lower pressure, which gradually reduces the dissipated energy. [GRAPHICAL ABSTRACT]