Synergistic effects of a triphenyl phenolic curing agent and organic montmorillonite on the properties of bis(aminopropyl) polydimethylsiloxane–grafted multifunctional epoxy resin

Abstract

Epoxy adhesives with excellent overall performance are in high demand for critical engineering applications. In this paper, a multifunctional epoxy resin N,N-diglycidyl-4-glycidyloxyaniline (AFG-90H) with high heat resistance but inherent brittleness was selected as the matrix, and a triphenyl phenolic curing agent based on diphenyl ether was synthesized from p-tert-butylcatechol, formaldehyde, and diphenyl ether to improve toughness. To further enhance material performance, bis(aminopropyl) polydimethylsiloxane modified by acid anhydride and organic montmorillonite were incorporated into the epoxy system. The results indicate that the curing temperature of the triphenyl phenolic curing agent–cured AFG-90H epoxy resin is below 100 °C. When AFG-90H epoxy resin grafted with 10 parts per hundred resin of bis(aminopropyl) polydimethylsiloxane is combined with 10 parts per hundred resin of organic montmorillonite, the cured material exhibits a thermal degradation temperature at 5% weight loss of 359 °C, along with tensile strength, flexural strength, impact strength, and tensile shear strength of 73.29 MPa, 75.00 MPa, 11.31 kJ m⁻², and 14.09 MPa, respectively. These results demonstrate that the synergistic interaction among the triphenyl phenolic curing agent, organic montmorillonite, and bis(aminopropyl) polydimethylsiloxane increases significantly the thermal stability and mechanical properties of the cured multifunctional epoxy resin, thus providing an effective approach for the development of high-performance epoxy adhesives.