Preparation and characterization of triangular hollow porous polyacrylonitrile fiber made by coaxial wet spinning

Hollow porous fiber with both hollow and mesoporous structural characteristics can play an important role in storage, adsorption, and other fields. Triangular hollow porous fiber was prepared by coaxial wet spinning in this paper. Polyacrylonitrile (PAN) and N-N dimethylformamide (DMF) were blended to get cortical solution. Polyvinylpyrrolidone (PVP) and DMF were blended to get core solution. Subsequently, coaxial triangular spinneret was adopted to inject solution into coagulation bath for double diffusion and obtain primary fiber. Then PAN-based triangular fiber with high porosity was prepared after washing and drying. Scanning electron microscopy, nitrogen physical adsorption instrument, thermogravimetric analyzer, and other instruments were used to test and characterize. The results show that the cross-section of the fiber is triangular and has a sense of luster. The hollow degree of the fiber is as high as 84.17%, and the sheath has three-level structure with multi-scale pore diameters, including micropores (200 μm), submicron pores (200 nm), and nanopores (20 nm). Through the range analysis of orthogonal experiment, it is found that the concentration of cortical solution is the main factor affecting the fiber tensile strength. When the concentration of cortical solution is 17%, the concentration of core solution is 10%, the flow rate ratio of cortical solution to core solution is 10:1, and the concentration of coagulation bath is 10%, the fiber tensile strength reaches 1.43 N/mm². The thermal insulation performance of fiber is better than that of silk, cotton and polyester. The results in this paper will provide an experimental foundation for the design and application of hollow porous profiled fibers.