| Both PBO fiber and Twaron fiber are high-performance fibers which are wildly used in fiber-reinforced resin matrix composites, due to their superior high strength, modulus and resistance to high temperature and chemicals. But the interfacial adhesion of their reinforced resin matrix composites was poor, owing to the smooth and inert fiber surface. Thus oxygen-plasma-induced epoxy resin coating was chosen to modify the surfaces of the fibers in order to improve the interfacial adhesion of fiber-reinforced PPESK matrix composites.In this work, the influences of the conditions of oxygen-plasma-induced epoxy resin coating process on the interlaminar shear strength (ILSS) of the composites were systema-tically investigated. The fiber surface chemical structure, surface roughness and surface free energy before and after coated were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), dynamic contact angle analysis (DCAA) system, respectively. The interfacial adhesion property and the morphology of the interlaminar shear rupture modes were investigated by ILSS, water absorption measurements and scanning electron microscopy (SEM).The effect of oxygen-plasma-induced epoxy resin coating process on PBO/PPESK com-posites interfacial properties was investigated. The optimal treating condition was determined by the orthogonal experiment, which can be stated as:the concentration of epoxy resin solution is3wt%, the plasma power is50W, the treatment time is10min and the discharge pressure is30Pa. The results showed that both the chemical linkage and physical adhesion were existed between PBO fibers and epoxy resin at the fiber surface. Due to the modification of surface chemical structure, surface roughness and surface free energy, the ILSS of PBO/PPESK composites run up to51.1MPa, increased by56%comparing with the untreated sample, meanwhile the water absorption reduced to0.32%. The failure mode of PBO/PPESK composites varied from interface shear destruction to matrix and fiber destruction.The method of oxygen-plasma-induccd epoxy resin coating was further used to improve the interfacial adhesion of Twaron/PPESK composites. The effects of the concentration of epoxy resin solution, plasma treatment time and plasma power on the surface properties of Twaron fibers and the interfacial properties of Twaron/PPESK composites were investigated. The optimal treating condition was stated as:the concentration of epoxy resin solution is1wt%, the plasma treatment time is10min, the plasma power is100W and the discharge pressure is10Pa. The results indicated that the ILSS of Twaron/PPESK composites attained65.1MPa with an increment of66%, while the water absorption was decreased to0.38%. |
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