Polydicyclopentadiene toughened epoxy resin and its carbon fiber composites via sequential polymerization

In this work, a dicyclopentadiene monomer/Grubbs 2 catalyst was added to a mixture of epoxy oligomers and methyl nadic anhydride to obtain a poly-dicyclopentadiene (DCPD) modified epoxy cross-linked network via sequential curing. The hybrid resin was used as a matrix for preparing carbon fiber composites. The results indicated that the addition of DCPD monomers significantly reduced the viscosity of the epoxy resin. The toughness and heat resistance of the co-cured resin was improved without significant loss of strength, which was attributed to the high compatibility between epoxy and the modifier polymer. Regarding the composites, the flexural strength of the hybrid resin-derived composite first increased and then diminished slightly. Meanwhile, the mode-I interlaminar fracture toughness continued to increase with the increase of PDCPD content compared to the non-modified composites. Generally, the change trend of the above properties in the composites was consistent with the change trend of the strength and toughness exhibited in the bulk resin with increasing PDCPD contents, while the change extent was inconsistent due to factors such as fiber volume content and interfacial bonding.