Evolution of dielectric properties of Kevlar/epoxy laminated composites after hybridization by naturally woven Coco Nucifera sheaths

The present work was undertaken to examine the evolution of interfacial properties of Kevlar/epoxy laminated composites hybridized by naturally woven Coco Nucifera sheath (CNS). Hand lay-up method followed by hot pressing was performed to fabricate our laminated composites. Broadband Dielectric Spectroscopy (BDS) was adopted to investigate the effect of varying CNS fractions (0%, 25%, 50%, 75% and 100%) on the molecular dynamics and the interfacial adhesion between Kevlar/epoxy and CNS/epoxy. The surface and cross-section morphology of the samples were studied in order to analyze the weaving structures of Kevlar and CNS and the interfaces between epoxy matrix and reinforcements. Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) were carried out to control the characteristic temperatures and the interactions between the two kinds of fibers (Kevlar and CNS) and the epoxy resin. The BDS results revealed different relaxations: the conduction phenomenon, the primary α -process and the interfacial polarization, called also MWS polarization, whose dielectric strength ∆ ε M W S was calculated using the WinFit software. Hence, Kevlar fibers can be successfully replaced by 25% of CNS natural fibers for advanced structural applications where interfacial adhesion is prime requirement. Graphical Abstract