Microstructure effects on mechanical properties of network-forming polymer systems: An atomistic simulation study

The coupling mechanism of chain entanglement and crosslinking remains unelucidated at the atomic scale. The network-forming dynamics and mechanical properties of pure-entangled matrix (PEM) and crosslinked & entangled matrix (CEM) were explored using all-atomic molecular dynamics simulations. The generation of side chains and local networks significantly affects the mechanical properties. For the PEM, as the reaction degree (r) increased, the dominant factor affecting the mechanical properties of materials changed from the movement of the main chain to entanglement. For the CEM, as r increased, the system first produced a local cross-linked structure and then formed a complete matrix. At extremely large strain, the CEM directly ruptured; the PEM showed a strain-hardening behavior before the final rupture because of the re-distribution of chain entangle-ments. The PEM and CEM exhibited almost the same elasticity but demonstrated a large difference in viscosity owing to the presence of long side chains in the CEM.