Morphology, mechanical and thermodynamic properties of epoxy resins toughened with liquid acrylate oligomers containing carboxyl groups

Abstract

Purpose

The purpose of this paper is to obtain liquid acrylate oligomers containing carboxyl groups as excellent toughening agents for epoxy resins.

Design/methodology/approach

Liquid acrylate oligomers containing carboxyl groups were synthesised by the solution polymerisation of butyl acrylate (BA), acrylic acid (AA) and acrylonitrile (AN) as monomers. The liquid acrylate oligomers were used as the toughening agents for epoxy resins. The chemical structure of the oligomers was characterised by ¹³C nuclear magnetic resonance (NMR) spectroscope. The morphology of modified epoxy networks was analysed by scanning electron microscope (SEM). The mechanical and thermodynamic properties were measured by universal testing machine and dynamic mechanical analyser (DMA).

Findings

The results show that AA and oligomer concentrations have great influence on the morphology, mechanical and thermodynamic properties of the modified epoxy networks. When the 10 wt percent oligomer containing BA and AN and AA in the ratio of 75/20/5 is used to modify the epoxy resin, the increase in impact strength of the modified epoxy network is 291.5 percent over the unmodified epoxy network due to addition of the oligomers without a sacrifice in heat‐resistance properties. Fracture surface analysis by SEM indicates the presence of a two‐phase microstructure.

Practical implications

The modified epoxy networks can be used as high performance materials such as adhesives, sealants and matrices of composites.

Originality/value

The liquid acrylate oligomers containing carboxyl and nitrile groups which were synthesised with BA, AA and AN as monomers by the solution polymerisation are novel and can greatly increase the toughness of epoxy resins without loss of thermal resistance.

Citation

Zhang, X., Zhang, B., Sun, M., Li, J., Wang, L. and Qin, C. (2012), "Morphology, mechanical and thermodynamic properties of epoxy resins toughened with liquid acrylate oligomers containing carboxyl groups", Pigment & Resin Technology, Vol. 41 No. 2, pp. 104-111. https://doi.org/10.1108/03699421211210766