• Title/Summary/Keyword: PVdF membrane

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Study on the PVdF Nanofibers and Graphene Oxide Hybrid Membrane (PVdF 나노섬유와 Graphene Oxide 하이브리드막에 관한 연구)

  • Jung, Hyemin;Chen, Weidong;Yang, Woo Seok;Byun, Hongsik
    • Membrane Journal
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    • v.23 no.3
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    • pp.204-210
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    • 2013
  • Recently, many applications with grapheneoxide (GO) have been reported. But GO membrane for water treatment has not been developed. In this study we prepared polyvinylidene difluoride (PVdF) nanofiber/GO hybrid membrane (FG) for the microfiltration application. The PVdF substrate membrane was prepared by using the electrospinning method with a solution of PVdF in N,N-dimethylacetamide (DMAc) and acetone. GO sheets used in this study were prepared by modified Hummer's method. The PVdF/GO hybrid membrane was finally prepared by spraying the GO solution dispersed in ethanol on the PVdF nanofiber. The successfully prepared FG was thoroughly examined by SEM, Raman, contact angle, porometer and UTM, and water-flux was measured with designed cell (Dead-End Cell). From the contact angle results, it was found that the surface of FG membrane was reformed by hydrophilic property and the water permeability was increased about 2.5 times than that of the nascent PVdF membrane, indicating the possible alternative of the commercial MF membrane.

Enhancement of Cycle Performance of Lithium Secondary Batteries Based on Nano-Composite Coated PVdF Membrane

  • Ryou, Myung-Hyun;Han, Young-Dal;Lee, Je-Nam;Lee, Dong-Jin;Park, Jung-Ki
    • Journal of the Korean Electrochemical Society
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    • v.11 no.3
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    • pp.190-196
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    • 2008
  • The multilayered membrane for lithium rechargeable batteries based on poly (vinylidene fluoride) (PVdF) is prepared with the coated layer containing nano-sized filler. The prepared membranes were subjected to studies of mechanical strength, morphology, interfacial stability, impedance spectroscopy, ionic conductivity, and cycle performance. The localized inorganic filler in the PVdF composite membrane rendered mechanical strength much reduced because of its low stretching ratio and it results in around half value of the mechanical strength of highly stretched PVdF membrane. In order to achieve high ionic conductivity and interfacial stability without sacrificing high mechanical strength, coating layer with nano-filler was newly introduced to PVdF membrane. The ionic conductivity of the coated membrane was 1.03 mS/cm, and the interface between the coating layer and PVdF membrane was stable when the membrane was immersed into liquid electrolyte. The discharge capacity of the cell based on nano-filler coated PVdF membrane was around 91% of the initial discharge capacity after 250 cycles, which is an improvement in cycle performance compared to the case for the non-coated PVdF membrane.

Characterization of PVdF/Laponite Reinforced Composite Membranes for PEMFC Surpport (PEMFC 지지체용 PVdF/Laponite 강화 복합막의 특성평가)

  • Oh, Seul-Gi;Hwang, Hae-Young;Kim, Hyoung-Juhn;Nam, Sang-Yong
    • Membrane Journal
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    • v.20 no.2
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    • pp.159-168
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    • 2010
  • In this study, high porous PVdF flat sheet membranes were prepared to obtain reinforced membrane support for polymer electrolyte membrane fuel cell. Nano-size laponite was randomly dispersed in the membranes to improve mechanical property which lowered by the high porosity. The morphology and porosity of prepared PVdF/Laponite composite membranes were examined using the SEM analysis and the weight method and all membranes showed over 60% porosity. The membrane thermal stability depending on the laponite contents in the composite membranes was evaluated by membrane heat shrinkage at $105^{\circ}C$ and $135^{\circ}C$. MD and TD heat shrinkage of the PVdF composite membrane containing 5 wt% laponite was 2~3% and 2~3.5% at $135^{\circ}C$, respectively. The mechanical strength was enhanced after incorporating laponite particles and 30% increase in the modulus compared to pure PVdF membrane was obtained.

Preparation of PVdF/GO Composite Nanofibrous Flat Membrane and its Permeation Characteristics in Activated Sludge (PVdF/GO 복합 나노섬유 평막의 제조 및 활성슬러지 내 투과특성)

  • Won, In Hye;Jang, Wongi;Chung, Kun Yong;Byun, Hongsik
    • Membrane Journal
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    • v.25 no.1
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    • pp.67-74
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    • 2015
  • In this study the nanofiber was prepared by electrospinning method with polyvinylidene fluoride (PVdF) and a completely dispersed solution of graphene oxide (GO) in the mixed solvent of dimethylformamide (DMF) and acetone. The $0.4{\mu}m$ pore size microfiltration flat membrane was made by increasing layers of the PVdF/GO composite nanofiber. Also, transmembrane pressure (TMP) was measured in order to evaluate fouling of the PVdF/GO composite membrane which was introduced GO reducing biological fouling with the intrinsic antibacterial characteristics. The permeate experiments were carried out simultaneously for the PVdF/GO and commercialized CPVC (chlorinated polyvinyl chloride) flat membranes with $0.01m^2$ effective area in the activated sludge solution of MLSS 4,500 mg/L. TMP of PVdF/GO membrane decreased up to 79% lower than that of CPVC for $10L/m^2{\cdot}h$ permeate flux without air supply. Also, for the case of run/stop operational mode, TMP of PVdF/GO membrane decreased up to 69% lower than that of CPVC for $10L/m^2{\cdot}h$.

Study of surface modification and contact angle by electrospun PVdF-HFP membrane with DLC coating (DLC 코팅에 의한 PVdF-HFP 막의 표면변화 및 접촉각 연구)

  • Lee, Tae Dong;Cho, Hyun;Yoon, Su Jong;Kim, Tae Gyu
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.1
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    • pp.33-40
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    • 2014
  • Poly vinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) membrane were prepared by the electrospinning technique. We had applied a DLC coating process and then the surface of the membrane and the contact angle change was investigated. Electrospun fibrous PVdF-HFP membrane surface became to wrinkled shape by Ar plasma treatment and treatment conditions. The wrinkled surface of PVdF-HFP membrane became super-hydrophilic. However, after DLC coating process, it became super-hydrophobic. The resulting surfaces were characterized by water contact angle measurement, X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FE-SEM). Resultantly it was recognized that the wettability characteristics of the membrane surfaces depended on the chemical composition and surface morphology.

Convenient Preparation of Ion-Exchange PVdF Membranes by a Radiation-Induced Graft Polymerization for a Battery Separator (배터리 분리막을 위한 이온교환형 PVdF 맴브레인의 방사선 그래프트법에 의한 간편한 제조법)

  • Kim, Sang-Kyum;Ryu, Jung-Ho;Kwen, Hai-Doo;Chang, Choo-Hwan;Cho, Seong-Ho
    • Polymer(Korea)
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    • v.34 no.2
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    • pp.126-132
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    • 2010
  • A cation-exchange nanofiber poly(vinylidene fluoride) (PVdF) membrane was prepared by a radiation-induced graft polymerization (RIGP) of sodium styrene sulfonate (NaSS) in the presence of the polymerizable access agents in methanol solution. The used polymerizable access agents include styrene, acrylic acid, and vinyl pyrrolidone. The anion-exchange nanofiber PVdF membrane was also prepared by RIGP of glycidyl methacrylate (GMA) and its subsequent chemical modification. The successful preparations of cation- and anion-exchange PVdF membranes were confirmed via SEM, XPS and thermal analysis. The content of the grafting yield, ion-exchange group, and water uptake was in the range of 30.0~32.3%, 2.81~3.01 mmol/g and 66.6~147%, respectively. The proton conductivity at 20$^{\circ}C$ was in the range of 0.020~0.053 S/cm. From the result, the prepared ionexchange PVdF membrane can be used as a separator in battery cells.

Preparation and Characterization of Microporous PVdF Membrane for Li-ion Rechargeable Battery (이차전지용 미세다공성 PVdF 분리막의 제조와 물성)

  • Nam, Sang-Yong;Yu, Dae-Hyun;Jeong, Mi-Ae;Rhim, Ji-Won;Byun, Hong-Sik;Jeong, Chul-Ho;Lee, Young-Moo;Seo, Myung-Su
    • Membrane Journal
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    • v.17 no.3
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    • pp.233-243
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    • 2007
  • In this study, a separate. which is a microporous membrane based on poly(vinylidene fluoride)(PVdF) was prepared by phase inversion method. Being prepared by dissolving the PVdF in the N,N'-dimethylformamide(DMF) with mechanical stirring, the homogenous casting solution was cast onto a clean glass plate. Pore size and porosity of the membranes were controlled by changing preparation condition. The highest porosity of the membrane was 78.6%. The mechanical property of the membrane was determined by using an universal testing machine(UTM). The morphology of the membrane was investigated by scanning electron microscopy(SEM). The cross-section of the membrane shows sponge-like small micro-pores.

A Study on the Preparation and Characterization of Sulfonated PS/PVdF Composite Membranes (술폰화 폴리스틸렌/폴리비닐리덴플로라이드 복합막의 제조 및 특성에 관한 연구)

  • Hong, Young-Taik;Jung, Yeon-Gu;Park, Hyung-Su;Byun, Hong-Sik
    • Membrane Journal
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    • v.16 no.4
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    • pp.286-293
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    • 2006
  • Porous asymmetric membranes based on PVdF as a nascent membrane were prepared by using a phase inversion method. PVdF ion conductive composite membranes were finally made by introducing $SO_3{^-}$ from sulfuric acid after cross-linked PS with various DVB contents in the pores of PVdF. Final PVdF composite membranes were characterized by FTIR, SEM, EDS to verify $SO_3{^-}$. It was revealed that the solvent contents and ion exchange capacity (IEC) decreased with increase of the degree of cross-linking. As the degree of crosslink increases both the electric conductivity and methanol permeability decreased, which was showing the better values than Nafion 117. When DVB content was 8%, its electric conductivity ($5.58{\times}10^{-5}S/cm$) was similar to Nafion 117 ($6.03{\times}10^{-5}S/cm$). But the lower methanol permeability ($1.0{\times}10^{-6}cm^2/sec$) than that of Nafion 117 was obtained.

Preparation and Characterization of PVdF-HFP Microporous Membranes for Li-ion Rechargeable Battery (Poly(vinylidene fluoride-hexafluoropropylene)를 이용한 이차전지용 미세다공성 분리막의 제조와 물성)

  • Nam, Sang-Yong;Yu, Dae-Hyun;Jeong, Mi-Ae;Rhim, Ji-Won;Byun, Hong-Sik;Yoo, Hyun-Oh;Kim, Jong-Man;Seo, Myung-Su
    • Membrane Journal
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    • v.17 no.4
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    • pp.359-368
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    • 2007
  • The copolymer membranes, poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) were prepared by phase inversion method using as an additive with N,N-dimethylformamid as a solvent. The pores are generated during the solvent and non-solvent exchange process in the coagulation bath filled with non-solvent (distilled water). The highest porosity of the membrane was 60%. The surface and cross-section of the membranes was observed with a scanning electron microscopy (SEM). The mechanical property of the membrane was determined by using an universal testing machine (UTM). Tensile strength of measured membranes is presented the maximum 6.57 MPa at 30 wt% of PVdF-HFP.

Preparation of PVdF/Fe3O4-GO (MGO) Composite Membrane by Using Electrospinning Technology and its Arsenic Removal Characteristics (전기방사법을 이용한 PVdF/Fe3O4-GO(MGO) 복합 분리막 제조 및 비소 제거 특성평가)

  • Jang, Wongi;Hou, Jian;Byun, Hongsik;Lee, Jae Yong
    • Membrane Journal
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    • v.26 no.6
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    • pp.480-489
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    • 2016
  • In this study, the PVdF/MGO composite nanofiber membranes (PMGs) introducing Iron oxide-Graphene oxide ($Fe_3O_4/GO$, Metallic graphene oxide; MGO) was prepared via electrospinng method and its arsenic removal characteristics were investigated. The thermal treatment was carried out to improve the mechanical strength of nanofiber membranes and then the results showed that of outstanding improvement effect. However, in case of PMGs, the decreasing tendency of mechanical strength was indicated as increasing MGO contents. From the results of pore-size analysis, it was confirmed that the porous structured membranes with 0.3 to $0.45{\mu}m$ were prepared. For the water treatment application, the water flux measurement was carried out. In particular, PMG2.0 sample showed about 70% improved water flux results ($153kg/m^2h$) compared to that of pure PVdF nanofiber membrane ($91kg/m^2h$) under the 0.3 bar condition. In addition, the PMGs have indicated the high removal rates of both As(III) and As(V) (up to 81% and 68%, respectively). Based on the adsorption isotherm analysis, the adsorption of As(III) and As(V) ions were both more suitable for the Freundlich. From all of results, it was concluded that PVdF/MGO composite nanofiber membranes could be utilized as a water treatment membrane and for the Arsenic removal applications.