The tensile deformation behavior of polyvinylidenedifluoride (PVDF) symmetrical microfiltration hollow-fiber (HF) membranes was studied. The membranes had submicron pores with a three-dimensional open-cell structure. The surface and cross section of the porous membranes were observed by FESEM (field emission scanning electron microscope) to investigate the microstructure of the cell, namely, its size and ligament geometry. During uniaxial tensile tests, the membranes underwent elastic deformation and plastic deformation. Large deformation induced pore growth along the tensile direction, resulting in an increase in water permeability. In order to establish a mechanical model for tensile deformation, the finite element method (FEM) was employed. In this model, the Kelvin polyhedron (truncated octahedron structure) was used to mimic a three-dimensional open-cell structure. A one-unit cell based on this structure was created, and a periodical boundary condition was employed for the FEM computation. The FEM model could reproduce the overall elastoplastic deformation behavior of the porous membrane and provide useful insight into the fabrication of porous membranes and reliable operation of water purification. © 2015 Elsevier B.V.
Bibliographical noteThe authors are grateful to Mr. Masumi Anazwa at Chuo University for his important contributions to the experiments. This work was supported by the “Nanotechnology Platform” (Project no. 12024046) of the Ministry of Education, Culture, Sports, Science and Technology, Japan. The work of A.Y. is supported by JSPS KAKENHI (Grant no. 26420025) from the Japan Society for the Promotion of Science, by a research grant from JGC-S Scholarship Foundation (No. 1425), and by The Sumitomo Foundation (Environmental Research Projects, No. 143127). The work of X.C. is supported by the National Natural Science Foundation of China (11302163, 11172231 and 11372241), ARPA-E (DE-AR0000396), and AFOSR (FA9550-12-1-0159).
- Finite-element method
- Symmetrical microfiltration hollow-fiber membranes
- Tensile deformation
- Three-dimensional porous structure
- Water permeability