Modification of Heterocyclic Para-Aramid Fibers with Chlorine Groups and the Interfacial Properties of the Fiber/Epoxy Composites

A modified para-aramid fiber with chlorine groups based on heterocyclic aramid fibers was prepared by copolycondensation, wet-spinning and high temperature thermal treatment. The prepared fiber (named F358Cl) and other aramid fibers, including two commercial aramid fibers (K49 and F358) and one surface modified aramid fiber (F358F) by direct fluorination of F358, were characterized and analyzed in detail by infrared (IR) spectroscopy, scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), atomic force microscopy coupled with infrared spectroscopy (AFM-IR) and mechanical analysis. The experimental results indicated that the modified aramid fiber with chlorine groups showed excellent mechanical, thermal and composite properties. The interlaminar shear strength of the F358Cl/epoxy composite reached as high as 59 MPa, which was 23% higher than that of F358 (48 MPa) and 9% higher than that of F358F (54 MPa).