Low‐Temperature Cured and High‐Toughness Epoxy Resin Modified by Triblock Liquid Rubber

ABSTRACT Low‐temperature cured epoxy resin (EP) is a suitable resin system for bonding thermal and temperature‐sensitive devices, which can also reduce energy consumption and production costs. In order to further broaden the application range of low‐temperature curing EP systems in amine‐sensitive environments, in addition to selecting a well‐compatible curing agent, an effective rubber to form a three‐dimensional network structure with the resin matrix, so as to significantly improve the toughness of the EP. In this work, two kinds of triblock liquid rubber hydroxy‐terminated polypropylene glycol‐polybutadiene‐polypropylene glycol (HTPO‐PB‐PO) and hydroxy‐terminated polyphenylethylene oxide‐polybutadiene‐polyphenylethylene oxide (HTSO‐PB‐SO) with controlled molecular weight are synthesized and adopted to improve the mechanical properties of cured EP with methyl hexahydro phthalic anhydride (MEHHPA). It is found that all triblock liquid rubber‐modified epoxy systems can be cured below 100°C, and the curing mechanism is similar to that of the pure EP system. Compared with the original pure EP, the impact resistance of modified samples is significantly improved, and the glass transition temperature ( T g ) is similar, among which the best impact strength of modified EP can reach 16.22 kJ/m 2 , 62.7% higher than that of the pure sample with only slightly reduced thermal decomposition temperature. These results can provide a low‐temperature curing resin material with excellent mechanical properties, high dimensional accuracy, and high heat resistance for amine‐sensitive environments while reducing costs due to high‐temperature components and energy consumption.