Influence Of Plasma Treatment On Surface Property Of PBO Fiber,Carbon Fiber And Interfacial Property Of Their Composites

Poly(p-phenylene benzobisoxazole)(PBO) fiber reinforced bismaleimide (BMI) resin composite possess superior mechanical property, heat resistance and good wave permeability, it is expected to find great applications as structural or structural-functional materials in aerospace and national defense; C/PBO hybrid fibers reinforced BMI resin composites have not only outstanding mechanical property but also can be used as stealth material. But the potential applications are restricted because that the PBO fiber and carbon fiber have smooth and inert surface, then lead to a poor interfacial adhesion with resin matrix. Therefore, it is necessary to modify PBO fiber and carbon fiber surface and improve the adhesion of their composites, in order to obtain composites with excellent overall performance.In this paper, atmospheric dielectric barrier discharge (DBD) plasma was applied to modify PBO fiber; air and oxygen were used, respectively. The influences of plasma treatment time and discharge power density on ILSS of PBO/BMI composites were studied, and the X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic contact angle analysis (DCA) were used to investigate the chemical components, surface morphology, surface roughness and surface free energy of PBO fibers, respectively. Furthermore, the tensile strength of PBO fibers was also studied.Air and oxygen DBD plasma both can improve the interfacial adhesion of PBO/BMI composites effectively; the ILSS reached57.1MPa and62.0MPa, increased by30.1%and41.2%than untreated sample, respectively. The reason may be that, the chemical polarity and reactivity of PBO fiber surface were enhanced, and the surface morphology was roughened, the surface roughness improved. Otherwise, proper parameters of plasma may not decrease the single fiber tensile strength of PBO fiber obviously. When the plasma-treated PBO fibers were stored in air, the ILSS of PBO/BMI composites declined with the storage time prolonged. After analysis on aging effects of oxygen DBD plasma-treated PBO fibers, the surface polarity and reactivity of fiber dropped obviously with storage time extended, but the surface morphology and roughness changed little. Otherwise, the single fiber tensile strength of PBO fibers stands constant during storage time. The SEM images of PBO/BMI composites fracture morphology suggested that the failure mode changed from interfacial failure to partly cohesive failure after plasma treatment.CF was modified by air inductively coupled plasma (ICP), the ILSS of CF/BMI composites increased by20.4%after plasma treatment at30Pa,200W,15min. The C/PBO hybrid fibers reinforced BMI composites were prepared and the CF/BMI composites were used as main parts while the PBO/BMI composites as skin. On the basis of above-mentioned research results, the carbon fiber and PBO fiber were modified by plasmas, respectively, the ILSS of hybrid fiber composites improved obviously, and the maximum value reached92.8Mpa, with an increment of42.3%.