Effects Of Atmospheric Pressure Oxygen DBD Plasma On Surface Properties Of The PBO Fiber And Interfacial Properties Of PBO/BMI Composites

PBO was called Poly(p-phenylene-2,6-benzoxazole) for short.PBO fiber was popular in fiber-reinforced composites as reinforcement,which was due to its outstanding properties such as low density,high tensile,high strength modulus and so on,regarded as super fiber in the21st century.BMI resin is a new type of high temperature resistant thermosetting resin,which was widely used in aerospace and other fields. The interfacial adhesion of PBO fiber reinforced composites is poor because of few polar functional groups and the relatively smooth and chemically inactive surfaces,which has a great influence on the comprehensive performance of PBO/BMI composite material. Therefore,it is necessary to modified the surface of PBO fiber.In this paper, we use the atmospheric pressure oxygen DBD plasma to modified PBO fiber surface.The PBO/BMI composite was prepared through solution impregnating process and high temperature molding technique.We can use X-ray photoelectron spectroscopy(XPS) to test the elemental composition and chemical structure of PBO fiber surface;calculated the roughness of the surface of the PBO fiber by Atomic force microscope(AFM);observe the surface morphology of PBO fiber by scanning electron microscope(SEM);test the interlaminar shear strength(ILSS) on PBO/BMI composite materials by universal material testing machine;test water absorption to reflect the interface bonding.In this paper,the influence of oxy-DBD plasma treatment condition such as time and discharge power density on PBO fiber surface and PBO/BMI composite were studied.After treatment by oxy-DBD plasma,oxygen content of PBO fiber surface increased,but carbon content decreased.PBO fiber surface introduced a new functional group-O-C=O.At the same time,the fiber surface was etched obviously.The content of-O-C=O,-C-O-,-C-O-respectively reach to5.04%,14.61%,22.02%;Roughness increased from192.4nm to291.7nm;Interlaminar shear strength increased from43.9MPa to62MPa;Water absorption decreased from1.96%to1.53%for oxy-DBD plasma treated24s under the discharge power density at30W/cm3. We can draw a conclusion:24s is the optimum processing time and30W/cm3is the optimum processing discharge power density.Secondly,the influence of the aging behaviour of oxy-DBD plasma-treated fiber surface and PBO/BMI composite were studied.After storing in air as long as10days after oxygen plasma treatment,oxygen content and polar functional groups of PBO fiber surface increased.Interlaminar shear strength decreased from62MPa to52MPa;Water absorption increased from1.53%to1.90%.But after ten days,the aging behaviour is not obvious with the extension of time.Throughout the entire process,the surface morphology and roughness remained nearly stable.