The effects of interlayered carbon nanotube reinforced electrospun nanofibers on mixed mode fracture characteristics

Stability and stiffness of interface region have significant impact on mechanical properties in laminated composites; however, their performances suffer from layer separation and/or delamination. Nanofiber interlayered interface structures are promising approaches to improve resistance to failure. The goal of this study is to investigate the effect of incorporation of CNT reinforced electrospun nanofibrous mats on the interlaminar properties of laminated composites through identifying mixed mode delamination mechanism within simulating genuine loading conditions. Electrospinning method was preferred to fabricate homogeneous and adhesive polyvinyl butral (PVB)/CNTs networks to interlaminate at mid-plane of composite with no weight penalty. The effect of electrospun nanofibrous mats on interlaminar fracture toughness of carbon fiber prepreg reinforced composites were investigated by using various CNTs weight fractions (such as 0.5, 1, 2 %) in nanofibrous mats. The fractography images revealed that electrospun nanofibers were distributed homogeneously at interface while improving energy dissipation in-plane and through laminate thickness. The results also pointed out that neat laminates showed essentially linear load increase after crack propagation whereas nano-interlayered composites exhibited nonlinear and irregular load drops due to the effect of adhesive interleaving. It is evident that all nanofiber interlayers were effective in retardation of crack propagation.