The Structure And Properties Of Electronspun PSU Fibrous Membranes

In this dissertation, PSU fibers were prepared by electrospinning technique, and the electrospinning parameters were discussed systematically. This article studied the effects of heat treatment on the structure and performances of the PSU electrospun fibrous membrane, and its chemical stability and wet-heat stability were anylized. The filtration properties of the membrane were tested by slef-made deviceInvestigation on the technique of the electrospinning process: Solvent(S), concentration(C), voltage(V), tip-tocollector distance(C-SD), and solution flow rate(FR) of the electrospinning process were investigated. Initial optimized spinning parameters were: S DMF/acetone=9;1, C 20wt%, V 12kv, FR 4ml/h, and C-SD for long period electrospinning 20cm.Effects of heat treatment on structure and performances of the membrane: The effects of tension, temperature, and time on the structure and performances of PSU electrospun fibrous membrane. The results showed that: when the PSU membrane was heat-treated with relaxation heating, the fibers tended to curve and shrink, the membrane size reduced, and the membrane thickness increased with the raising heating temperature; loaded with tension, the heat treatment resulted in the increase of compactness and the smoother surface for the PSU membrane, but did not affect the membrane size. The heat treatment improved the mechanical properties of the membrane, but had no obvious influences on the crystal structure, wettability, and thermal properties. The best mechanical property was achieved as the heating temperature was 190℃and heating time 3h with the existence of tension, which can be regarded as the optimum process conditions.Chemical and wet-heat stability of the membrane: The tension heat treatment granted excellent chemical stability to the PSU membrane. Besides rapid shrinkage in the acetone, the membrane remained smooth surface and excellent dimensional stability, stable micro-morphology, and as well as its good mechanical properties after chemical treatment with pure alcohol solution, acid and alkaline solution, and H2O2 solution. The effect of hot water on the macro-mophology and dimension of the membrane was related to the temperature of the hot water. The mechanical properties and micro-structure were unaffected after treatment in 40℃and 60℃hot water, while the water temperature raised to 80℃, the fiber appearance and structure damaged badly, and its mechanical properties decreased greatly.Filtration test for the membrane: The retention of both orange and blue dye were low when filtrated by the PSU electrospun fibrous membrane. While the retention of 20μm PS micro-particles reached more than 98%, and the thickness of the membrane did not affect the retention.