Evaluation of Relationship between Molecular Structure and Viscosity Development of Thermoset Resin by Employing All-Atom Molecular Dynamics Simulation

In thermoset-based carbon-fiber-reinforced plastics, the viscosity of the matrix resin governs their formability. The present study analyzes the relationship between the molecular structure and viscosity of the thermoset resin during curing by employing two types of all-atom molecular dynamics (MD) simulations. One is a crosslinking simulation that considers the reaction dynamics for determining the resultant curing structures. The other is a non-equilibrium MD simulation utilizing the Lees–Edwards boundary condition for viscosity evaluation. The results of this study clarified that the viscosity of the thermoset resin is changed by its composition, and can be described by the Doolittle equation, which presents the relationship with the free volume ratio. Furthermore, the increasing rate of viscosity during curing can be correlated with the increasing weight-averaged molecular weight.