Effect of temperature on membrane structure

• Main Authors: Lin- Yean-chyi, 林衍琦
• Other Authors: Juin-Yin Lai
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/81159473073987821363

碩士 === 中原大學 === 化學工程研究所 === 86 === In this work, the effect of membrane formation temperature on thestructure of polymeric membrane was systematically investigated.Membranes are prepared by a wet phase inversion process from polycarbonate (PC) and polysulfone (PSf). Morphologies are qualitatively correlated with the phase diagram and the liquid-liquid demixing rate during membrane formation. For the PSf-DGDE-water membrane formation system, a lower critical solution temperature (LCST) phenomenon was observed. The liquid-liquid demixing rate increases with the casting solution temperature increases. Additionally, for the upper critical solution temperature (UCST) system,i.e. PC-NMP-water and PSf-NMP-water, the effect of thermodynamic is higher than that of the kinetic during the membrane formation process. Thus, the size of nodule structure increases with increasing the casting solution of temperature . Moreover, the addition of nonsolvent (PA) to the polymer solution (PC-NMP) results the membrane surface structure transfer from the nodule to the lacy. The macrovoids can be obtained in the following system : PC-NMP-water, PSf-NMP-water and PC-NMP+PA-water. However, the size of macrovoids can be suppressed by increasing the polymer casting solution temperature. The addition of solvent to the coagulation bath for the PC-NMP-water system results in a delayed onset of liquid-liquid dmixing . As the addition solvent increases, the resultant membrane surface structure change from nodule to dense.