Computational and Experimental Study of Phenolic Resins: Thermal–Mechanical Properties and the Role of Hydrogen Bonding

Molecular dynamics simulations and experimental measurements were used to investigate the thermal and mechanical properties of cross-linked phenolic resins as a function of the degree of cross-linking, the chain motif (<i>ortho–ortho</i> versus <i>ortho–para</i>), and the chain length. The chain motif influenced the type (interchain or intrachain) as well as the amount of hydrogen bonding. <i>Ortho–ortho</i> chains favored internal hydrogen bonding whereas <i>ortho–para</i> favored hydrogen bonding between chains. Un-cross-linked <i>ortho–para</i> systems formed percolating 3D networks of hydrogen bonds, behaving effectively as “hydrogen gels”. This resulted in differing thermal and mechanical properties for these systems. As cross-linking increased, the chain motif, chain length, and hydrogen bonding networks became less important. Elastic moduli, thermal conductivity, and glass transition temperatures were characterized as a function of cross-linking and temperature. Both our own experimental data and literature values were used to validate our simulation results