Atmospheric air plasma treated PBO fibers: Wettability,adhesion and aging behaviors

Poly (p–phenylene-2, 6-benzobisoxazole) (or PBO) fibers were modified by air dielectric barrier discharge plasma (air-DBD) with different treatment time. The wettability of the PBO fibers were enhanced evidently, which was proved by dynamic contact angle analysis (DCAA), the contact angle in water of the fibers treated by air-DBD plasma decreased from 77.52° to 34.05°, while the surface free energy increased from 44.73 mJ/m² to 64.04 mJ/m². The surface morphology changes and variations of chemical components of PBO fibers were detected by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the fiber surface morphology became rougher and some newly polar groups were introduced onto the fiber surfaces. They contributed to the enhancement of the wettability. Furthermore, the interfacial adhesion between PBO fibers and bismaleimide (BMI) resin was improved obviously, which revealed by the increased ILSS of the PBO/BMI composites. Nevertheless, the ILSS of PBO/BMI composites decreased to 47.0 MPa after PBO fibers were stored in air for 7 days and there were little changes for 7–30 days.