Structural, thermal and ion transport studies of different particle size nanocomposite fillers incorporated PVdF-HFP hybrid membranes (original) (raw)
Related papers
Materials Chemistry and Physics
Proton exchange membranes designed via reactive extrusion from the in situ generation of functional silica-like particles in a new poly(vinylidene fluoride-co-hexafluoropropylene (poly(VDF-co-HFP)) copolymer are presented. These sulfonic acid-functionalized polysiloxane-based fillers were synthesized via sol-gel chemistry from 3mercaptopropyltri(ethoxy)silane and polydimethoxysiloxane in the molten PVDF-co-HFP polymer. To process such nanocomposites materials, the reactive extrusion parameters were selected to (i) reach silanol condensation extents in the processing conditions of a conventional poly(VDF-co-HFP) copolymer and (ii) obtain a surface functionalization high enough with respect to reach a suitable protonic conductivity value of the nanocomposites films. Nevertheless, the enhancement of the proton conductivity being deeply associated with the morphologies of the nanocomposites materials (i.e. the dispersed functional silica phase need to display the larger interface area with the polymer matrix), an interfacial agent was synthesized. This compatibilizer was either poly(VDF-co-α-trifluoromethacrylic acid) or poly(VDF-co-MAF) copolymers or a poly(VDF-co-HFP) copolymer grafted with maleic anhydride, denoted poly(VDF-co-HFP)-g-MA. In a second step, to obtain the required sulfonic acid-functionalized silica dispersed phase from the presence of the mercaptan functions, the resulting films were oxidized. Electrochemical properties were evaluated: for a theoretical ionic exchange capacity (IEC) of 2 meq.g-1 , while experimental IEC ranged between 1.0 and 1.3 meq.g-1. The proton conductivity was found to reach 78 mS.cm-1 at room temperature for 100% of relative humidity. Interestingly, these values are higher than those of the same membranes processed without any compatibilizer (54 mS.cm-1) and to that of Nafion ® NR112 (52 mS.cm-1). This approach also allows limiting the swelling (or water uptake) of proton conductive membranes below 15wt% while it reachs 30 wt% for Nafion ® NR112 in similar conditions.
Ionics, 2012
Poly(vinylidene fluoride-co-hexafluoropropene)hexafluoropropylene (PVdF-HFP; M n , 130,000)-based membranes were prepared by means of phase inversion technique by coagulating with water and MeOH and then doping with H 3 PO 4 and H 2 SO 4. In order to improve the electrochemical properties of the PVdF-HFP membranes, coagulated membranes were also coated with polystyreneblock-poly(ethylene-ran-butylene)-block-polystyrene (PSEBS) and sulfonated with chlorosulfonic acid in the second stage. The effects of the type of coagulant, coagulation time, doping agents, coating, and sulfonation on the membrane properties were investigated. Membranes were thermally stable up to 400°C. The conductivity values were measured to be between 1.10E−01 and 6.00E−03 mS/cm for uncoated samples. The proton conductivity value of the PSEBS-coated and sulfonated membrane was increased from 6.00E−03 to 92.1 mS/cm. Water uptake values varied from 0 to 38 % for uncoated samples and from 11.5 to 65.2 % for coated samples. Chemical degradation of PVdF-HFP membranes was investigated via Fenton test. All membranes were found to be chemically stable. Morphology of the membranes was examined by scanning electron microscopy. Different membrane morphologies were observed, depending on different membrane preparation procedures.
Synthesis and Characterization of Partial Sulfonated PVDF-co-HFP Ion Exchange Membranes
Macromolecular Symposia, 2015
Membranes of Poly (vinylidenedifluoride-co-hexafluoropropylene) (PVDF-co-HFP) are prepared successfully and investigated for thermal, mechanical and electrochemical properties. A considerable influence in ionic conductivity by varying the time of sulfonation has been achieved. Membranes with higher degree of sulfonation exhibit higher proton transport at room temperature. Herein we prepared a series of PVDF-co-HFP membrane by varying sulfonation time (6, 8, 10, 13 & 15 hrs). Mechanical properties have been investigated by UTM (Universal Testing Machine) and thermal study has been done by TGA (Thermogravimeteric Analysis). The electro chemical properties of the membranes are found to be increase without compromising the thermal and mechanical characterises.
Synthesis and Characterization of Nanocomposite Sulfonated PVDF Membrane
2018
As a commercial fuel cell membrane, Nafion has disadvantages such as low stability at high temperature and low conductivity at low humidity. Sulfonated Polyvinylidene fluoride (PVDF) is known for good mechanical and thermal properties as a membrane. The purpose of this research is to synthesis a nanocomposite PVDF-TiSiO4 membrane as a potential replacement of Nafion. PVDF sulfonation was performed using concentrated sulfuric acid. The nanocomposites TiSiO4 were synthesized from TiCl4 and TEOS. Ultrasonification was used to insert the nanomaterial to the sulfonated membrane. The infrared spectra analysis shows the peak for the Ti-O-Si angel. SEM-EDX analysis shows that the nanocomposite PVDF-TiSiO4 membrane contents titanium oxide. The conductivity analysis shows the increasing of conductivity on addition of nanomaterials.
Chinese Journal of Polymer Science, 2014
New siloxane and sulfone containing poly(benzimidazole/sulfone/siloxane/amide) (PBSSA) has been prepared for the formation of hybrid membranes (PBSSA/PS-S/SiNPs) with sulfonated polystyrene (PS-S) and 0.1 wt%−2 wt% silica nanoparticles (SiNPs). Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSA/PS-S/SiNPs nanocomposites increased from 207 °C to 215 °C. The membranes also had higher ion exchange capacity (IEC) around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10−2.34 S/cm in a wide range of humidity values at 80 °C which was higher than that of perfluorinated Nafion ® 117 membrane (1.1 × 10 −1 S/cm) at 80 °C (94% RH). A H 2 /O 2 fuel cell using the PBSSA/PS-S/SiNP 2 (IEC 3.01 mmol/g) showed better performance than that of Nafion ® 117 at 40 °C and 30% RH.
Silicate-based polymer-nanocomposite membranes for polymer electrolyte membrane fuel cells
Progress in Polymer Science, 2012
Proton-exchange membrane fuel cells have emerged as a promising emission free technology to fulfill the existing power requirements of the 21st century. Nafion ® is the most widely accepted and commercialized membrane to date and possesses excellent electrochemical properties below 80 • C, under highly humidified conditions. However, a decrease in the proton conductivity of Nafion ® above 80 • C and lower humidity along with high membrane cost has prompted the development of new membranes and techniques. Addition of inorganic fillers, especially silicate-based nanomaterials, to the polymer membrane was utilized to partially overcome the aforementioned limitations. This is because of the lower cost, easy availability, high hydrophilicity and higher thermal stability of the inorganic silicates. Addition of silicates to the polymer membrane has also improved the mechanical, thermal and barrier properties, along with water uptake of the composite membranes, resulting in superior performance at higher temperature compared to that of the virgin membrane. on the techniques of silicate-based nanocomposite fabrication and the resulting impact on the membrane properties.
Nafion/Poly Vinylidene Fluoride (PVDF) Blends for Polymer Electrolyte Membranes Application
760: 761: 762: 763: The IASTED 2012 African Conferences, 2012
The proton exchange membrane fuel cells have attracted tremendous attention recent years because of their highest efficiency compared to other types of fuel cells. Nafion , a perfluorinated polymer substituted by sulfonic acid groups, is the most commonly used polymer for the fabrication in proton exchange fuel cell membrane. A large variety of nanoparticles of different nature and size can be blended with Nafion matrix, therefore, generating a new class of nanostructured electrolyte membrane with interesting physical properties. These membranes have attracted both academic and industrial attention because they exhibit significant improvement in thermomechanical and thermal stability as well as proton conductivity at a very low filler contents.
Advances in Science, Technology and Engineering Systems Journal
Novel ionic polymers were synthesized by crosslinking of poly (vinylalcohol) (PVA) with sulfosuccinic acid (SSA) and silicotungstic acid (SiWA) with or without silica. The polymer electrolyte membrane fuel cell (PEMFC) was developed using solution casting method. Infrared (IR) spectra revealed that the Keggin structure was insered in the PVA films. The thermal decomposition of the PVA/SSA/SiWA/SiO2 membranes showed good thermal stability up to 200°C. Water uptake ranged between 31% and 88%. The maximum conductivity has been found to be 6,72.10-3 S.cm-1 at room temperature for PVA/SSA/SiWA containing 10% of silica weight. The ion exchange capacity of this membrane was 1,75 mmol.g-1. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells.
Journal of Nanostructure in Chemistry, 2014
Organic-inorganic nanocomposite membranes of poly(vinyl alcohol) (PVA) and nanoporous silica containing sulfonic acid groups are synthesized in order to increase the proton conductivity, water retention and thermal stability of membrane. The cross-linked PVA/ SBA-15-propyl-SO 3 H nanocomposite membrane was prepared by solution casting method. Infrared spectroscopy and scanning electron microscopy are used to characterize and confirm the structure of PVA and the cross-linked membranes. The impedance spectroscopy, water uptake and thermal stability of membranes are investigated to confirm their applicability in fuel cells. It was found that the cross-linked PVA/SBA-15-propyl-SO 3 H nanocomposite membrane appears to be a good candidate for using in PEM fuel cell.
International Journal of Hydrogen Energy, 2010
This work clearly demonstrates the effect of the type and molecular weight of the fluorinated polymer of SPEEK/Fluorinated polymer blends for low temperature (<80 C) Fuel Cell Applications. Comparisons with trademarks (e.g., Nafion Ò) suggests that the membranes we have prepared in this study have good compatibility in all application respects. Membranes were prepared by solution casting method from four different fluorinated polymers; poly (vinylidene fluoride) with three different molecular weights (PVDF, M w : 180.000, M w : 275.000, M w : 530.000); Poli(vinylidene fluoride-co-Hexafluoro propylen) (PVDF-HFP M n :130.000) and sulfonated poly(ether ether ketone) (SPEEK) with sulfonation degree (SD) of 70. The sulfonation degree (SD) of SPEEK was determined by FTIR, 1 H NMR and ion exchange capacity (IEC) measurements. Thermo-oxidative stability and proton conductivity of the membranes were determined by using thermal gravimetric analysis (TGA) and BT-512 BekkTech membrane test systems, respectively. Chemical degradation of SPEEK membranes was investigated via Fenton test. The morphology of the membranes were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Water uptake and proton conductivity values decreased with the addition of fluorinated polymers (PVDF, PVDF-HFP) as expected, but proton conductivity values were still comparable to that of Nafion 117 Ò membrane. Addition of fluorinated polymers improved chemical degradation of the blend membranes in all ratios while addition of PVDF-HFP to the SPEEK70 caused phase separations in all ratios. Methanol permeability value of SPEEK70/PVDF(M w ¼ 275.000) blend membrane (3.13E-07 (cm 2 /s)) was much lower than Nafion 117 Ò (1.21E-06 (cm 2 /s). PVDF addition to the SPEEK polymers caused increase in elongation of the membranes. Increase in the molecular weight of the PVDF did not show any effect on the Young modulus, but resulted in high elongation values. On the other hand, increasing PVDF content of the blend membranes caused lower elongation values at break and didn't have any effect on the Young modulus. The gas permeability values of SPEEK70/PVDF type blend membranes were lower than that of the Nafion Ò. Hydrogen and oxygen permeability values were one-tenth and one-fifth of the NafionÒ, respectively.