Construction of Interpenetrating Networks Structure in Epoxy Resin With Both High Modulus and High Toughness and Research on Properties of Polymers

ABSTRACT The high‐performance development of advanced resin‐based composite materials imposes higher demands on the modulus and toughness of epoxy resins. Enhancing the mechanical strength of epoxy resin materials and maintaining their comprehensive performance remain challenging. In recent years, hyperbranched epoxy resins have emerged as an outstanding material for enhancing epoxy resin systems' modulus, toughness, and thermal performance. This study utilizes bisphenol A and trimellitic anhydride as precursors to synthesize a multi‐epoxy‐terminated hyperbranched epoxy resin through esterification reactions and the incorporation of functional groups. The intermediate terminal carboxylic hyperbranched‐modified polyester (TCMP) and the final product high‐performance hyperbranched‐modified epoxy resin (HP‐HMEP) were characterized using FT‐IR and 1 H NMR spectroscopy, followed by curing with curing agent JH‐45. The mechanical and thermal properties of the cured products were subsequently investigated. For the samples cured with JH‐45, whose tensile strength, elongation at break, compressive strength, impact strength, and tensile modulus of the E51/HP‐HMEP (20 wt%) sample exhibited increases of 51.5%, 44%, 25.5%, 111.6%, and 51.5% compared to those of the E51 samples. Furthermore, the glass transition temperature increases from 67.5°C to 79.3°C, while the initial thermal decomposition temperature rises from 306.9°C to 355.8°C. In summary, the new hyperbranched epoxy resin combines high modulus and high toughness, and the comprehensive performance is significantly improved, which is expected to become an excellent material in the fields of carbon fiber composites, concrete repairation, and so on.