Hollow fiber membranes for dialysis were manufactured by dry-wet spinning of cuprammonium cellulose solution.
The composition of the dope was copper 5.87%, ammonia 11.63%, cellulose 9.19%.
The spinning was through a single hole needle-in-orifice hollow filament spinnerette. Aqueous sulfuric acid was used as the external coalgulant and aqueous acetic acid was used as the internal coagulant.
The effect of the internal coagulant, the coagulation bath composition, the coagulation bath temperature, the air drying time, the draw ratio, and the annealing temperature on the structure and properties of the hollow fiber membranes were studied.
The hollow fiber membranes had homogeneous porous structure with no skin layer formation. It had inside diameter and thickness of 240 ㎛ and 37 ㎛, respectively.
The optimum spinning conditions were as follows;
internal coagualnt : 7.5% acetic acid
coagulation bath composition : 5% sulfuric acid
coagulation bath temperature : 30℃
air drying time : 0.5-1.0 sec
annealing temperature : 65℃ for 5 min. in water bath
Hollow fiber membranes obtained at the optimum spinning conditions showed solute rejection properties of urea; 0%, PEG 300; 3%, PEG 1,000; 10%, PEG 4,000; 20%, PEG 20,000; 85%, when tested with 5% solution at an operating pressure of 4 atm.
At that time, the permeate flux was 758 ml/hrㆍ㎡.