Hsu-Hsien Chang1,2, Sheng-Chang Chen1,2 and Liao-Ping Cheng This email address is being protected from spambots. You need JavaScript enabled to view it.1,3

1Department of Chemical and Materials Engineering, Tamkang University, Tamsui, Taiwan 251, R.O.C.
2Bright Sheland International Co., New Taipei City, Taiwan 221, R.O.C.
3Energy and Opto-Electronic Materials Research Center, Tamkang University, Tamsui, Taiwan 251, R.O.C.


Received: March 9, 2017
Accepted: July 30, 2017
Publication Date: March 1, 2018

Download Citation: ||https://doi.org/10.6180/jase.201803_21(1).0011  


Hollow fiber membranes of PVDF were prepared by isothermal wet spinning process from the water/DMF/PVDF system at 25 C. The dope solution comprised 21 wt% PVDF in DMF, and pure water was employed both as the inner and outer coagulants. SEM imaging of the membrane indicated an unexpected interesting morphology: columnar macrovoids extended from the outer surface to the central region, while cellular pores constituted the inner half of the membrane. As water was a harsh nonsolvent, one tended to think that macrovoids shall form towards the inner surface of the hollow fiber. Absence of macrovoids in this region was explained based on the fact that DMF would accumulate rapidly in the inner extruding stream as it underwent mass-exchange with water in the inner bath. Such activity rendered effectively the coagulant became effectively a soft one. As a result, macrovoids was eliminated and the inner surface became porous.

Keywords: PVDF, Hollow Fiber, Membrane, Morphology, NIPS


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