The thickness effect of rubbery nanofibrous mat on modes I–II fracture mechanism of composite laminates

This study investigates the effect of the interleaving nanofibers, made of NBR/PCL blend, on the interlaminar fracture toughness of carbon/epoxy laminates. Different nanomat thicknesses, ranging from 20 μm to 120 μm, were tested at Mode-I and mode-II and results were compared to the non-modified laminates. Acoustic Emission (AE) technique was used to assess the influence of interleaving nanofibers on dominant damage modes of the specimens, i.e., matrix cracking, fiber/matrix debonding, and fiber breakage. Moreover, the damage mechanism and the nanofiber toughening contribution were investigated by means of crack path and surface analysis. Results indicated that the optimum nanomat thickness for mode-I is 40 μm (GI,R = + 333 %), while for mode-II is 20 μm (GII,R = + 43 %). The study also confirmed by AE the significant impact of nanofibers on various damage modes, especially during mode-I loading.