Preparation of annular hollow fibre membranes

Preparation of an annular hollow fibre membrane using a triple-orifice spinneret was studied. Various annular hollow fibre membranes were prepared from different membrane forming systems. The polymers used in spinning the annular hollow fibres include polysulfone (PSf), polyethersulfone (PESf), polyetherimide (PEI) and cellulose acetate butyrate (CAB). The solvents are N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAC). The additives are water and ethanol. The spinning conditions to form annular hollow fibres were investigated experimentally. Structures of the annular hollow fibres were examined by scanning electron microscopy. Through the proper selection of polymers, solvent and additives, and polymer dope composition, the annular hollow fibres can be formed with controlled width of the hollow fibre annulus.