Matrix formulation and interfacial enhancement of an aeronautical carbon fabric/epoxy composites fabricated via resin transfer molding (RTM) technique

Flexural strength and interlaminar shear strength of fiber-reinforced composites are among the most concerned properties in the aeronautical sector, which are ameliorated in combination through matrix formulation and interfacial enhancement in this study. A thermosetting matrix resin consisting of diglycidyl ether of bisphenol A and diglycidyl ester of aliphatic cyclo was formulated to cater to the requirements of carbon fabric/epoxy composites fabricated by resin transfer molding (RTM) technique. The toughness and thermal stability of the formulated epoxy resin were studied in consideration of the compromise among processability, thermal and mechanical properties for potential aeronautical applications. The processability of the matrix resin suitable for RTM technique was evaluated with respect to temperature-dependent and time-dependent viscosity. A regime for the curing and post-curing cycles was established according to the differential scanning calorimeter data. Air plasma is introduced herein as a technique to enhance the interfacial adhesion of carbon fabric/epoxy composites. Composites based on the epoxy system and plasma-treated carbon fabric were fabricated using the RTM technique. The reactive groups introduced by plasma treatment are responsible for the significant improvements of mechanical properties of the resulting composites. The microscopy pictures of the fracture surfaces confirm that the failure mode of carbon fabric/epoxy composites has changed initially from primarily adhesive failure to cohesive failure.