Deformation modeling of polyvinylidenedifluoride symmetrical microfiltration hollow-fiber membrane

Significance Statement

Computational modeling of tensile deformation of polymeric hollow fiber membrane used for water purification

Microfiltration of polymeric hollow fiber membrane has been promising technology for water purification owing to a cost-effective way. For the long-term operation with repeated cleanings, the deformation mechanics is now becoming important. We investigated the tensile deformation behavior of polyvinylidenedifluoride (PVDF) symmetrical microfiltration hollow-fiber (HF) membranes, having submicron pores with a three-dimensional open-cell structure. The computational modeling of macroscopic and microscopic deformation is our challenge.

During uniaxial tensile tests, the membranes underwent elastic deformation and plastic deformation. Large deformation induced pore growth along the tensile direction due to plastically stretched ligament of PVDF matrix, resulting in an increase in water permeability. In order to establish a mechanical model for tensile deformation, the computation with 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. Our FEM model could reproduce the overall elastoplastic deformation behavior of the porous membrane, and also capture the microscopic pore deformation behavior.

Therefore, our computational framework may be useful for various purification materials with pore structure and may provide insight into the material fabrication and operation; for instance, optimization of a physical cleaning process with minimal mechanical deformation, new fabrication method to improve the mechanical property (deformation resistance), and prediction of membrane operation lifetime, from the viewpoint of long-time use and recycling efficiency.

Deformation modeling of polyvinylidenedifluoride (PVDF) symmetrical microfiltration hollow-fiber (HF) membrane. Advances in Engineering

About The Author

Shouichi Iio: He is a Graduate Student of Chuo University in Tokyo, Japan. He received his B.S. in Precision Mechanics from Chuo University in 2014. His research is experiment and computational mechanical modeling of nano-cellular materials including water purification and separation. He has co-authored three related peer-reviewed papers published in Journal of Membrane Science and Water Science and Technology. He received awards from Japan Society of Mechanical Engineer (JSME) and Japan Society for Design Engineering (JSDE) as Young Investigator. 

About The Author

Akio Yonezu:  Dr. Akio Yonezu is an Associate Professor at Chuo University (Department of Precision Mechanics). He received his B.S. and M.S. in Mechanical Engineering from Aoyama Gakuin University (AGU) of Japan in 1999 and 2001, respectively. He served on Canon Inc. between 2001 and 2002. He received Ph.D (Doctor of Engineering) from AGU in 2006. He served on the faculty of Osaka University as an Assistant Professor for five years, and joined Chuo University as an Associate Professor. He has a strong background in materials science and mechanics, and more than 10 years of research experience with 80+ publications, and Best Paper Awards from Japanese Society of Non-Destructive Inspection (JSNDI) and Japanese Society of Materials Science (JSMS).

About The Author

Hiroshi Yamamura: Dr. Hiroshi Yamamura is an Associate Professor at Chuo University (Department of Integrated Science and Engineering for Sustainable Society). He has been studying about fouling of porous membranes used in drinking water treatment for more than 10 years. He initially identified the key fraction of natural organic matter which contributes to the membrane fouling and then suggests the mechanisms why the carbohydrate or polysaccharides was mainly found on the surface of membrane based on the affinity measurement by the use of AFM force curve method. These works is now sited in more than 100 papers and lead the fouling researches. In addition to the fouling research, he has a working experience in R&D section in Membrane Company for three years. He has developed a polymeric UF membrane and charged from the selection of polymer to the manufacturing process. From 2011, he enrolled in Chuo University as an assistant Professor and launched a new department. Now, he is now especially focusing on (1) the development of innovative membrane materials, (2) the design of sustainable water and solid management system in depopulating society, (3) the development of biodiesel production system by the use of microalgae. He won the 2014 prize in young researcher award from Japan Society on Water Environment (JSWE). 

About The Author

Xi Chen:  Dr. Xi Chen received his B.S. in Engineering Mechanics from Xi’an Jiaotong University in 1994 (at the age of 18), M.S. in Solid Mechanics from Tsinghua University in 1997, and Ph.D. in Solid Mechanics from Harvard University in 2001 (under the supervision of Prof. John W. Hutchinson). He was a postdoctoral fellow at Harvard University from 2001-2003. He joined Columbia University in 2003 as an Assistant Professor and was promoted to an Associate Professor in 2007. He uses multiscale theoretical, experimental, and numerical approaches to investigate various research frontiers in materials addressing challenges in energy and environment, nanomechanics, and mechanobiology. He has published over 250 journal papers with a h-index over 38. He received the NSF CAREER Award in 2007, the Presidential Early Career Award for Scientists and Engineers (PECASE) in 2008, ASME Sia Nemat-Nasser Early Career Award in 2010, SES Young Investigator Medal in 2011, ASME Thomas J. R. Hughes Young Investigator Award in 2012, and a number of international recognitions from Japan, Korea and China. He is a Fellow of ASME. 

Journal Reference

Journal of Membrane Science, Volume 497, 1 January 2016, Pages 421–429.

Shouichi Iio1,Akio Yonezu1,, , Hiroshi Yamamura2,, , Xi Chen3,4

Show Affiliations
  1. Department of Precision Mechanics, Chuo University, 1-13-27 Kasuga, Bunkyo, Tokyo 112-8551, Japan
  2. Department of Integrated Science and Engineering for Sustainable Society, Chuo University, 1-13-27 Kasuga, Bunkyo, Tokyo 112-8551, Japan
  3. Department of Earth and Environmental Engineering, Columbia University, 500W 120th Street, New York, NY 10027, USA
  4. International Center for Applied Mechanics, SV Lab, School of Aerospace, Xi’an Jiaotong University, Xi’an 710049, China

Abstract

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.

Go To Journal of Membrane Science