Toughened carbon fibre reinforced polymer composites with nanoparticle modified epoxy matrices

摘要

In the current work the microstructure and fracture performance of carbon-fibre reinforced polymer (CFRP) composites based upon matrices of an anhydride-cured epoxy-resin (formulated with a reactive diluent), and containing silica nanoparticles and/or polysiloxane core-shell rubber (CSR) nanoparticles, were investigated. Double cantilever beam tests were performed in order to determine the interlaminar fracture energy of the CFRP composites, while the single edge-notched bend (SENB) specimen was employed to evaluate the fracture energy of the bulk polymers. The fracture energy of the bulk epoxy polymers increased from 173 J/m2 for the unmodified polymer to a maximum of 1,237 J/m2 with the addition of 16 wt% of CSR nanoparticles. The toughening mechanisms were identified as (a) localised plastic shear yielding and (b) cavitation of the CSR particles followed by plastic void growth of the matrix. The steadystate propagation value of the interlaminar fracture energy of the CFRP composites increased with increasing nanoparticle concentration, from 1,246 J/m2 for the unmodified epoxy matrix to a maximum of 1,851 J/m2 with 4 wt% of silica nanoparticles and 8 wt% of CSR nanoparticles. Crack growth in the CFRP composites was dominated by fibre-bridging toughening mechanisms. The efficiency of the transfer of toughness from the bulk polymers to the carbon fibre composites was considered. The measured fracture energy of both bulk and composite materials decreased at a test temperature of -80°C, compared with room temperature, i.e. 20°C. Nevertheless, the toughening effects of both the silica and CSR nanoparticles on the bulk epoxy polymers and the CFRP composites, compared with the unmodified epoxy polymers, were still evident even at the lower temperature. Indeed, the toughening effect of the silica nanoparticles was greater at -80°C than at room temperature.