Revealing Interaction Mechanisms between Mechanical Properties and Structural Conformations–Interfacial Interactions in Materials Using Molecular Dynamics Simulations: A Natural Rubber–Lignin Composite Case

Abstract

In this paper, the natural rubber-lignin system is used as an example, and molecular dynamics simulations are employed to reveal the interaction mechanisms linking mechanical properties with structural conformation–interfacial interactions. The results indicate that when the number of lignin chains is below 20 mol, interfacial interactions dominate the reinforcement behavior of the system, and chain-segment extensibility, system packing efficiency, network confinement, and mechanical properties exhibit positive correlations with lignin chain number. When the number of lignin chains reaches 20 mol, lignin agglomeration becomes the dominant factor governing the reinforcement behavior, resulting in negative correlations between these structural characteristics and mechanical properties. Furthermore, increasing the lignin degree of polymerization enhances lignin-chain extensibility, system packing efficiency, network chain density, and mechanical properties, with interfacial interactions serving as the primary contributor to reinforcement. These findings provide a theoretical foundation for the design and enhancement of composite materials.