Cure‐Promoting Strategies for Phenol‐Resorcinol‐Formaldehyde Resins: High‐Ortho Catalysis, Hydrogen Bond Activation, and Their Impact on Curing Kinetics

ABSTRACT The curing energy consumption of traditional phenolic resin (PF) is high, and rapid curing modification is required. The curing mechanism of phenolic resin also requires further investigation. In this work, the reaction process and functional application of curing‐accelerated modified phenolic resins are studied. Phenol‐resorcinol‐formaldehyde (PRF) resin, sodium bicarbonate‐accelerated curing PRF (PRF‐SB) resin, and zinc oxide‐catalyzed high‐ortho‐phenol‐resorcinol‐formaldehyde (HOPRF) resin are synthesized via in situ polymerization. The addition of resorcinol and zinc oxide increases the number of active sites in the resin molecules and reduces the activation energy required for curing. Compared with PF, the activation energy of HOPRF is reduced by 9.78%. Sodium bicarbonate increases the crosslinking density of the resin. The curing kinetics are analyzed using the Starink and Málek methods. The results show that the curing mechanism involves a combination of nth‐order and autocatalytic reactions. The competition and synergy of these reactions enhance the curing rate of the resin. In addition, under the same curing conditions, the tensile shear strength of PRF‐SB is 2.88 times that of PF. The lower curing temperature and stronger mechanical properties make modified phenolic resin have application potential in wood, casting, and other industries.