Optimization of polyurethane-based hollow fiber membranes morphology and performance by post-treatment methods Original Research Article

Polyurethane-based (PU-based) hollow fiber membranes were fabricated by melt-spinning method and then treated under different conditions to investigate the effects of post-treatment on their morphology and performance. The post-treatment included two processes, a water bath post-treatment for 48 h at various temperatures and a dry air oven heat-treatment at 20 °C for 48 h. During the treatment process, membranes were treated at different draw ratios and their deformations were studied. Elastic deformation-recovery was associated with the treatment temperature and was affected slightly by draw ratio. For membranes treated in stress free conditions, pore size on the inner surface shrunk with increasing treatment temperature. Stretching could enlarge the mean and maximum pore size of membrane. The best water flux was obtained when the hollow fiber membranes were treated at 50 °C, and the least treatment duration was 50 min. Meanwhile, the extension ratio 3 was adopted as the optimal draw ratio.