Interfacial enhancement for carbon fibre reinforced electron beam cured polymer composite by microwave irradiation

In this study, the transverse electric microwave (MW) mode TE₁₀ was applied on a single layer of unidirectional prepreg before stepwise electron beam (E-Beam) curing, and the interfacial adhesion enhancement mechanism was investigated. The interaction between MW with carbon fiber (CF) and polymer was simulated by the Floquet unit cell method for periodic structures at a 2450 MHz frequency. For absorbing the most MW energy, the CF must be oriented perpendicular to electric field. On this condition, the fibre/matrix interface was improved owing to increased fibre surface roughness, decreased resin viscosity and the electrically driven polymer intermolecular interaction. The MW irradiation is considered to have a “co-irradiation grafting” effect on the fibres in the prepreg, increasing their surface roughness and energy with further increase in wettability. This enhanced fibre/matrix interfacial bonding during the E-Beam curing process. Experimental data showed that the interfacial shear strength (IFSS) increased by more than 31% after 180 s of MW exposure, while the interlaminar shear strength (ILSS) improved by 22% after 90 s; excessive irradiation reduces the beneficial effect and might damage the actual fibre strength.