Coarse-Grained Molecular Dynamics Simulation for Detailed Characterization of Interfacial Interactions within Natural Rubber–Lignin Composites and the Effects of Key Affecting Factors

To reduce the computational cost of molecular dynamics (MD) for modeling natural rubber–lignin (NR-L) complex systems and study the effects of key affecting factors, a reliable coarse-grained MD (CGMD) model for NR-L is established. Using the validated CGMD model, the spatiotemporal evolution of the NR-L interface and features is characterized. It is discovered that deformation energy induces structural rearrangement within the system, with potential energy exhibiting transient fluctuations before stabilizing, generating mechanical responses during this process. Then, the effects of key affecting factors for the mechanical properties of NR-L composites are studied, and the results show that temperature exhibits a negative correlation with mechanical performance, entanglement density (ρ e ), and potential energy, whereas the deformation rate negatively correlates with potential energy but positively with mechanical strength and is independent of ρ e . Overall, increasing the syringyl/guaiacyl ratio decreases mechanical properties, ρ e, and potential energy. These insights provide a valuable theoretical foundation for enhancing the mechanical performance of NR-L composites.