Toughened carbon fibre-reinforced polymer composites with nanoparticle-modified epoxy matrices

Abstract

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 specimen was employed to evaluate the fracture energy of the bulk polymers. The fracture energy of the bulk epoxy polymers increased from 173 J/m 2 for the unmodified polymer to a maximum of 1237 J/ m 2 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 steady-state propagation value of the interlaminar fracture energy of the CFRP composites increased with increasing nanoparticle concentration, from 1246 J/m 2 for the unmodified epoxy matrix to a maximum of 1851 J/m 2 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.

Simultaneous improvements in flammability and mechanical toughening of epoxy resins through nano-silica addition

“…The nano-silica was obtained pre-dispersed at 40% in DGEBA (Nanopox F400, Evonik Hanse) or HDE (Nanopox F640, Evonik Hanse) to achieve the desired concentrations. Surface functionalisation with amine and the spherical shape of the particles ensure good dispersion as has been shown in samples prepared in the same fashion [33]. Table 1 summarises the compositions of the samples used.…”

On the extent of fracture toughness transfer from 1D/2D nanomodified epoxy matrices to glass fibre composites

“…giving a CTT \ 0.5. However, values of the CTT of 1.0 have also been reported [23] for 4 wt% of nanosilica filler particles in an anhydride-cured epoxy polymer with respect to a CFRP composite. Also, values of CTT of 5.5 were found for 10 wt% of nanosilica filler particles in a similar anhydride-cured epoxy polymer employed as the matrix for an unidirectional (UD) GFRP composite [24].…”

Thermal and mechanical properties study of boron nitride nanosheets decorated by silver/epoxy nanocomposites

“…Many polymer nanocomposites consist of polymers and thermally conductive nanomaterial were reported to obtain polymers with high thermal conductivity [10][11][12]. The commonly used nanomaterial include carbon(carbon nanotubes [13], carbon nanofibers [14], graphene [15], etc. ), oxides (aluminum oxide (Al 2 O 3 ) [16], beryllium (BeO) [17], (titanium oxide(TiO 2 ) [18], etc.…”