Hybrid silane-treated glass fabric/epoxy composites: tensile properties by micromechanical approach

The effect of interface modification on the interfacial adhesion and tensile properties of glass fabric/epoxy composites was evaluated in two directions of 0 degrees and +45 degrees. Herein, the glass fabric surface was modified by colloidal nanosilica particles and by a new blend of silane-coupling agents including both reactive and non-reactive silanes. Composite samples with high strength and toughness were obtained. A simultaneous improvement of tensile strength and toughness was observed for an epoxy composite reinforced with a hybrid-sized glass fabric including silane mixture and nanosilica. In fact, the incorporation of colloidal silica into the hybrid sizing dramatically modified the fiber surface texture and created mechanical interlocking between the glass fabric and resin. The results were analyzed by the rule of mixtures (ROM), Halpin-Tsai (H-T), and Chamis equations. It was found that the ROM equations provided approximate upper bound values for all investigated composite samples. In the samples containing nanosilica, the shear and elastic moduli values calculated by the Chamis and ROM equations showed good agreement with those obtained from experiments. However, in other samples, the values calculated by the H-T equation showed a better agreement with the experimental data. The analysis of fracture surfaces indicated that both silane and nanosilica particles had influence on the mode of failures at the interface.