Effects of Cross-Linking Degree and Characteristic Components on Mechanical Properties of Highly Cross-Linked Phenolic Resins: A Molecular Dynamics Simulation Study

Phenolic resins (PF), naphthol modified phenolic resins (NPF), and cyanate ester modified phenolic resins (CEPF) were constructed where naphthols and triazine rings act as chain reinforcing and chain-to-chain bridging roles, respectively. Then, molecular dynamics simulations were performed to predict the Young’s modulus. The results show that methylene bridges and branched phenolic rings are key factors affecting the stiffness of resin. Introducing naphthols does not provide a clear benefit in stiffness due to a counterbalance between the rise in nonbonded energies and the drop in methylene bridges. For CEPF, the chain-to-chain bridges of triazine rings increase the Young’s modulus up to 2.93 GPa and contribute significantly to stiffness compared to reinforcing chains by rigid naphthols. The trend of the three systems from plastic to the cured state can be seen in the mean squared displacement and Young’s modulus. These findings can support the study of the molecular design of PF to optimize stiffness.