Role of carbon nanotubes in enhancing the mechanical behavior and microstructural characteristics of Kevlar fiber reinforced epoxy composites

Carbon nanotubes (CNTs) are effective nanoscale reinforcements for controlling the mechanical performance of fiber reinforced polymer composites (FRPCs). In this study, a multiscale reinforcement strategy was adopted by incorporating varying concentrations of multi-walled carbon nanotubes (MWCNTs) into an epoxy matrix to fabricate Kevlar/CNT/epoxy laminates. The laminates were developed through hand lay-up technique. The developed laminates were systematically evaluated for tensile performance, and the experimental findings were validated through numerical modelling. Results revealed a concentration dependent mechanical response, with an optimal improvement observed at 0.4 wt% CNT loading. At this concentration, the tensile strength increased from 333 ± 16.6 MPa for the baseline laminate to 357 ± 17.9 MPa, while numerical simulation predicted 362 MPa, showing excellent correlation with less than 2% deviation. Beyond the optimal CNT content, a gradual decline in strength was observed due to agglomeration induced stress concentration effects. Post failure analysis confirmed improved fiber/matrix adhesion, reduced fiber pull-out, and evidence of crack deflection and nano-bridging mechanisms in optimally reinforced laminates, whereas higher CNT loadings exhibited localized clustering and microvoid formation.