A high ductility RTM epoxy resin with relatively high modulus and Tg

It is hard to obtain a high ductility resin transfer moulding (RTM) epoxy resin while maintaining relatively high modulus and Tg due to the requirement of low viscosity. In the paper, a high breaking elongation (6.1–8.3 %) RTM epoxy system with relatively high modulus (≥3.0 GPa) and Tg (84–115 °C) has been achieved by a novel toughening approach. The simultaneous control of chain segment structural flexibility and crosslink density through the flexible/rigid hardener ratio (D-230/DETDA) and the reaction temperature was proposed for the simultaneous toughening and stiffening of the epoxy resin. Control experiments revealed that epoxy 830 played an important part in the acquirement of high ductility for all these RTM epoxy resin formulas due to the formation of low crosslink density and relatively flexile structure. The fracture surfaces of the epoxy samples examined by scanning electron microscopy (SEM) confirmed the toughening results.