Effect of interlayer hybridization of carbon,Kevlar,and glass fibers with oxidized polyacrylonitrile fibers on the mechanical behaviors of hybrid composites

This study focuses on tensile and flexural behaviors of epoxy composites, which have been reinforced by oxidized polyacrylonitrile fibers and high-performance fibers (carbon, glass, and Kevlar). In hybrid composites, the parameters of hybridization show positive or negative hybrid effects on its mechanical properties. The results of energy absorption achieved from the tensile test depicted that reinforced hybrid composites by two plies of oxidized polyacrylonitrile fiber and two plies of carbon, Kevlar, and glass fibers with energy absorption of 916, 700, and 899 kJ m^–3 had the maximum hybridization parameter, which were 1.1, 0.64, and 1.54, respectively. Also, the mentioned hybrid composites with flexural stresses of 279.4, 198.5, and 167.3 MPa had the maximum hybridization parameter in a flexural test, which were 3.01, 2.68, and 1.80, respectively. Hybrid composites, which were reinforced by three plies of oxidized polyacrylonitrile fiber/one ply carbon fibers, three plies of oxidized polyacrylonitrile fiber/one ply of glass fibers, and two plies of oxidized polyacrylonitrile fiber/two plies of Kevlar fibers, had the maximum pseudo strain in their group, which were 0.12%, 0.65%, and 0.17%, respectively. The microstructure investigations depicted crossing cracks among oxidized polyacrylonitrile fiber and cutting the oxidized polyacrylonitrile fiber, which were caused to increase the hybridization parameters in mechanical tests. Also, it was found that as compared with carbon, glass, and Kevlar fibers, oxidized polyacrylonitrile fiber had a ductile fracture, which was the reason for the pseudo-ductility behavior in hybrid composites.