Papers by Author: Xiao Hui Cao

Abstract: Poly (vinylidene fluoride) membranes were prepared from the ternary mixture of PVDF/ 1, 2 - propylene glycol/dimethylacetamidevianon-solvent induced phase separation (NIPS). The effect of the addition of the 1, 2 - propylene glycol content, the Coagulation Bath Temperature and the concentration of PVDF on the performance and structure of the PVDF membranes was studied in the present investigation.The results showed that with increasing polymer concentration, the mechanical strength increased,and the structure of membrane changed from finger-like macro-voids structureto sponge-like structure.It was found that water flux, breaking elongation and tensile strength of the membrane increased with increasing 1, 2 - propylene glycol content, when the content reached 41wt.%, the water flux reaches a maximum.The morphology of PVDF can be improved by the addition of 1, 2 - propylene glycol, which was changed from finger-like structure to sponge-like structure. And the dense skin layer of PVDF membranes became thicker with increasing 1, 2 – propyleneglycol. The tensile strength decreasedfrom 3.3 to 2.1MPa, breaking elongation decreased from 315% to 280% andthe pure water flux increased from 91 to 909 L·m^-2·h^-1. as the coagulation bath temperature (CBT) decreased from 30°C to 5°C.With this condition, the sponge-like hollow fiber membrane hassuccessfully spun.

Abstract: Polyethersulfone (PES) flat sheet membranes were prepared via phase inversion induced by immersion precipitation from a novel lower critical solution temperature (LCST) system containing PES, 1-butanol and N, N-dimethylacetamide. And the effect of coagulation bath temperature on the properties and structure of PES membranes were investigated. The results show that the pure water flux increases and the tensile strength decreases as the coagulation temperature increases form 20°C to 50°C. Besides, the SEM images shows that all of the membranes prepared from a LCST system at different CBT own sponge-like structures.