Molecular Dynamics Simulation Insight into the Aggregate Structure–Mechanical Property Relationship of Double-Crosslinked Epoxidized Natural Rubber/Polylactic Acid Composites

In this work, coarse-grained molecular dynamics simulations were employed to investigate PLA/ENR blends with different ENR chain lengths and dual crosslinking networks, including PLA–ENR interfacial crosslinks and ENR–ENR self-crosslinks. The results reveal a nonmonotonic dependence of mechanical reinforcement on ENR chain length. Short ENR chains mainly act as isolated local junctions, whereas excessively long chains undergo severe phase aggregation and form self-crosslinked domains.

In contrast, intermediate ENR chains construct an effective interwoven bridging network, leading to enhanced chain orientation, stable interfacial coupling, and superior strain-hardening behavior. Bonded-stress analysis further demonstrates that intra-ENR self-crosslinking bonds sustain substantially higher stress than PLA–ENR interfacial bonds, identifying the internal elastomer network as the dominant load-bearing element.

This work provides molecular-level insights into the role of elastomer network architecture in PLA/ENR composites and offers theoretical guidance for designing high-performance bio-based polymer blends.