Polyurethane was grafted onto the surface of domestic poly-p-phenylene benzobisoxazole (PBO) fiber by atmospheric air dielectric barrier discharge plasma, and the effect of sizing agent on grafting reaction was invetigated. The results of XPS analysis show that the surface chemical composition of PBO fiber modified by plasma grafting polyurethane changed greatly. Compared with the simple air dielectric barrier discharge plasma treated one, the PBO fiber modified by plasma grafting polyurethane had more carboxyl groups, and of which the increment for the later one was 64%~189% (without sizing agent) and 102~184% (with sizing agent) respectively. Sizing agent cannot affect the grafting reaction, and the oxazole ring of PBO was destroyed by plasma grafting reaction. However, ATR-FTIR characterization of PBO fibers with sizing agent showed that the oxazole ring characteristic peaks did not change before and after grafting, so there was no evidence for the destruction of PBO molecules in the near surface. The damage of oxazole ring was detected on the grafted PBO fiber without sizing agent. Thus the sizing agent can prevent the damage of DBD plasma on the near surface of the fiber.

Keywords： PBO fiber ; plasma graft ; surface modified ; chemical