Unique 'micelle-like' macrovoids have been observed for the first time in the polyvinylidene fluoride-polytetrafluoroethylene (PVDF-PTFE) hollow fiber membranes. FESEM results show that the incorporation of 30 and 40 wt% PTFE particles (<1 μm) reduces the number of finger-like macrovoids in the membrane matrix, while micelle-like marcovoids (about 10 μm in size) are formed when PTFE loading is increased to 50 wt% or higher. 50 wt% PTFE is the critical particle concentration for micelle-like macrovoid formation. The origins of micelle formation may be attributed to the adhesion and cohesion forces between air bubbles and particles in the supersaturated PTFE solution. A more rigorous degassing of the PVDF-T50 polymer dope solution may enhance the suspension homogeneity and eliminate the micelle-like macrovoid formation. It is therefore concluded that the micelle-like macrovoid formation arises from the agglomeration of gas bubbles upon PTFE particles with the aid of water diffusion and convection during the phase inversion of membrane formation.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Membrane Science|
|State||Published - Aug 10 2009|
Bibliographical noteFunding Information:
The authors would like to thank NUS and A* Star for funding this research with grant number R-279-000-218-305 as well as Kureha Corporation for the provision of copolymer polyvinylidene fluoride (PVDF) T #2300. Thanks are also due to Dr. P.S. Tin, Miss N. Widjojo, Miss. N. Peng, Dr. Y.C. Xiao, and Dr. K.Y. Wang who have contributed useful comments and suggestions to this study.
- Hollow fibers
- Micelle-like macrovoids
- Mixed matrix membranes
ASJC Scopus subject areas
- Materials Science(all)
- Physical and Theoretical Chemistry
- Filtration and Separation