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Blend Membranes (blend + membrane)
Selected AbstractsEvaluation of Modified CMC and CMC-PVA as Miscible Polymer Blend Membranes for HepatocytesMACROMOLECULAR BIOSCIENCE, Issue 5 2007Aysel Koç Abstract CMC and CMC-PVA were blended either with type I collagen, BSA or CS to obtain biocompatible membranes for evaluation as potential hepatocyte culture substrates. Pure and modified forms of CMC showed distinct surface, mechanical, and cell attachment properties. While the hydrophilicity decreased, the mechanical stability and the porosity of CMC membranes increased after blending. Serum proteins were adsorbed by all types of membranes. Among eight membranes tested, collagen-modified CMC was found to be a suitable membrane material for hepatocyte culture, in terms of mechanical and cell interaction properties. [source] Partially Sulfonated Polystyrene and Poly(2,6-dimethyl-1,4-phenylene oxide) Blend Membranes for Fuel CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2004Bokyung Kim Abstract Summary: Based on Flory,Huggins parameters (,), the miscibility and the effect of morphological change on proton conductivity and methanol permeability of partially sulfonated polystyrene (SPS) and partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), having an identical ion exchange capacity, were investigated. When 50 wt.-% of SPPO was blended, both the proton conductivity and methanol permeability had the highest values, which resulted from the change of amorphous domains and the hydrogen bonding between the two ionomers. The proton conductivities, water uptake and methanol permeability for the SPPO/SPS blend membranes studied here. The membranes with 50 wt.-% SPPO clearly showed the greatest increase in these properties. [source] Sulfonated polybenzimidazoles: Proton conduction and acid,base crosslinkingJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2010Owen D. Thomas Abstract A series of soluble, benzimidazole-based polymers containing sulfonic acid groups (SuPBI) has been synthesized. SuPBI membranes resist extensive swelling in water but are poor proton conductors. When blended with high ion exchange capacity (IEC) sulfonated poly(ether ether ketone) (SPEEK), a polymer that has high proton conductivity but poor mechanical integrity, ionic crosslinks form reducing the extent of swelling. The effect of sulfonation of PBI on crosslinking in these blends was gauged through comparison with nonsulfonated analogs. Sulfonic acid groups present in SuPBI compensate for acid groups involved in crosslinking, thereby increasing IEC and proton conductivity of the membrane. When water uptake and proton conductivity were compared to the IEC of blends containing either sulfonated or nonsulfonated PBI, no noticeable distinction between PBI types could be made. Comparisons were also made between these blends and pure SPEEK membranes of similar IEC. Blend membranes exhibit slightly lower maximum proton conductivity than pure SPEEK membranes (60 vs. 75 mS cm,1) but had significantly enhanced dimensional stability upon immersion in water, especially at elevated temperature (80 °C). Elevated temperature measurements in humid environments show increased proton conductivity of the SuPBI membranes when compared with SPEEK-only membranes of similar IEC (c.f. 55 for the blend vs. 42 mS cm,1 for SPEEK at 80 °C, 90% relative humidity). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3640,3650, 2010 [source] Metal ion permeation properties of silk fibroin/chitosan blend membranesPOLYMER INTERNATIONAL, Issue 4 2006Chun-Hui Du Abstract Silk fibroin/chitosan (SF/CS) blend membranes were prepared and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy. It was found that SF and CS were compatible in the blend membranes and that the membranes were dense without microscopic phase separation. Swelling experiments showed that the swelling ratio of the blend membranes increased with CS content and reached the highest value when CS content was 70 wt%. Experiments indicated that the permeability coefficient of K+ through the blend membrane was 2,4 times higher than that of pure CS membrane, and 10 times higher than that of pure SF membrane. The permeation rate of K+ increased linearly with CS content in the blend membrane for the lower concentration feeding solution. For different metal ions, the permeability through SF/CS blend membranes was in the sequence K+ > Ca2+ > Cd2+ > Pb2+ > Cu2+ > Ni2+. Copyright © 2006 Society of Chemical Industry [source] Covalent-Ionically Cross-linked Poly(Etheretherketone)-Basic Polysulfone Blend Ionomer MembranesFUEL CELLS, Issue 3-4 2006J. Kerres Abstract Sulfinated-sulfonated PEEK was synthesized via partial reduction of sulfochlorinated PEEK with aqueous Na2SO3. From these polymers, covalent-ionically cross-linked ionomer blend membranes were prepared by mixing the sulfinated-sulfonated PEEK with different base-modified polysulfones (PSU-base), followed by cross-linking with 1,4-diiodobutane. These membranes have been compared with covalently cross-linked membranes which were obtained by the cross-linking of sulfinated-sulfonated PEEK and with ionically cross-linked membranes obtained by mixing sulfonated PEEK with different PSU bases. The membranes have been characterized in terms of thermal stability by means of thermogravimetry (TGA) and coupled TGA-FTIR, in terms of cross-linking extent by extraction experiments, in terms of proton conductivity by impedance spectroscopy, and finally, in terms of water uptake by gravimetric analysis. [source] Theoretical studies on structural and electrical properties of PES/SPEEK blend nanofiltration membraneAICHE JOURNAL, Issue 8 2009A. F. Ismail Abstract Polyethersulfone (PES) nanofiltration membranes were prepared using a simple dry-jet wet spinning technique with different contents of sulfonated poly(ether ether ketone) (SPEEK) ranging from 0 to 4 wt %. The structural parameters (rp and Ak/,x) and electrostatic properties (, and X) of the blend membranes were deduced by employing the combination of irreversible thermodynamic model, steric hindrance pore (SHP) model, and Teorell-Meyer-Sievers (TMS) model. The modeling results obtained have been analyzed and discussed. The mean pore radius and pore size distribution of the blends were also determined based on the theoretical models. The results showed that pore radius increased with increasing the concentration of SPEEK from 0 to 2 wt % but decreased with a further increase in SPEEK content. The water flux, however, showed a systematically increase with increasing SPEEK content. The SPEEK also showed significant effect on membrane electrical properties. Both effective charge density and ratio of effective charge density to electrolyte solution increased with increasing concentration of SPEEK in the dope solution, reaching a value of ,21.02 and ,2.29, respectively. The pore radius which was determined by using different transport models has also been analyzed and discussed. It is found that the addition of SPEEK into dope solution is one of the paramount parameters in developing the negatively charged nanofiltration membrane with enhanced water flux while retaining the pore radius in the nanometer range. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis and properties of new fluorinated polymers bearing pendant imidazole groups for fuel cell membranes operating over a broad relative humidity rangeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Guillaume Frutsaert Abstract New alternating copolymers comprising a chlorotrifluorinated backbone and imidazole-terminated pendant ethylene oxide groups have been prepared with a view to their use as a component of proton-conducting membranes in polymer electrolyte fuel cells. A vinyl ether containing an imidazole (Imi) function protected by a benzyl group (BVI) was first synthesized in a three-step reaction. It was then copolymerized in solution with chlorotrifluoroethylene (CTFE) by conventional radical copolymerization leading to alternating poly(BVI-alt-CTFE) copolymers in good yields. Deprotection of the benzyl group under hydrogen produced a chlorotrifluorinated poly(Imi-alt-CTFE) copolymer. The polymer was subsequently used to form blend membranes with sulfonated poly(ether ether ketone) (sPEEK). The conductivity of blend membranes of poly (Imi-alt-CTFE) with sPEEK lies in the range of 4,10 mS cm,1 at 40,70 °C and, for blend membranes rich in poly(Imi-alt-CTFE), is little dependent on relative humidity between 30 and 100%. It is surmised that the polymer and membrane composition favor microstructural phase separation into chlorotrifluorinated polymer backbone domains and regions in which imidazole groups are clustered. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 223,231, 2010 [source] Partially Sulfonated Polystyrene and Poly(2,6-dimethyl-1,4-phenylene oxide) Blend Membranes for Fuel CellsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2004Bokyung Kim Abstract Summary: Based on Flory,Huggins parameters (,), the miscibility and the effect of morphological change on proton conductivity and methanol permeability of partially sulfonated polystyrene (SPS) and partially sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), having an identical ion exchange capacity, were investigated. When 50 wt.-% of SPPO was blended, both the proton conductivity and methanol permeability had the highest values, which resulted from the change of amorphous domains and the hydrogen bonding between the two ionomers. The proton conductivities, water uptake and methanol permeability for the SPPO/SPS blend membranes studied here. The membranes with 50 wt.-% SPPO clearly showed the greatest increase in these properties. [source] Transport of aromatic solvents through nitrile rubber/epoxidized natural rubber blend membranesPOLYMER ENGINEERING & SCIENCE, Issue 3 2003Asha Elizabeth Mathai The sorption and diffusion behavior of a series of aromatic solvents through blends of nitrile rubber (NBR) and epoxidized natural rubber (ENR) have been studied in the temperature range of 28,70°C. The effect of blend ratio, penetrant size and temperature on the transport properties was investigated. The relationship between the diffusion behavior and the morphology of the system was examined. Different transport parameters such as diffusion coefficient, permeability coefficient and swelling ratio have been calculated. Experimental permeability coefficients were compared with various theoretical models. The van't Hoff relation was used to compute the thermodynamic parameters. [source] Metal ion permeation properties of silk fibroin/chitosan blend membranesPOLYMER INTERNATIONAL, Issue 4 2006Chun-Hui Du Abstract Silk fibroin/chitosan (SF/CS) blend membranes were prepared and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy. It was found that SF and CS were compatible in the blend membranes and that the membranes were dense without microscopic phase separation. Swelling experiments showed that the swelling ratio of the blend membranes increased with CS content and reached the highest value when CS content was 70 wt%. Experiments indicated that the permeability coefficient of K+ through the blend membrane was 2,4 times higher than that of pure CS membrane, and 10 times higher than that of pure SF membrane. The permeation rate of K+ increased linearly with CS content in the blend membrane for the lower concentration feeding solution. For different metal ions, the permeability through SF/CS blend membranes was in the sequence K+ > Ca2+ > Cd2+ > Pb2+ > Cu2+ > Ni2+. Copyright © 2006 Society of Chemical Industry [source] Polyurethane and sulfonated polysulfone blend ultrafiltration membranes: II.POLYMER INTERNATIONAL, Issue 3 2003Application studies Abstract Ultrafiltration membranes are largely being applied for macromolecular and heavy metal ion separations from aqueous streams. Polyurethane- and sulfonated- polysulfone-based membranes prepared in the absence and presence of the polymeric additive, poly(ethylene glycol) 600, in various compositions, were subjected to the rejection of macromolecular proteins, such as bovine serum albumin, egg albumin, pepsin and trypsin. Toxic heavy metal ions such as Cu2+, Ni2+, Cd2+ and Zn2+ were subjected to rejection by the blend membranes by complexing them with a polymeric ligand, polyethyleneimine. The effects of polymer blend compositions and additive concentrations on the rejection and permeate flux of both proteins and metal ions are discussed. The rejection and permeate flux efficiencies of the blend membranes are compared with pure sulfonated polysulfone membranes. © 2003 Society of Chemical Industry [source] Studies on cellulose acetate,carboxylated polysulfone blend ultrafiltration membranes,Part IIPOLYMER INTERNATIONAL, Issue 1 2003J Sajitha Abstract Hydrophilic polysulfone ultrafiltration membranes were prepared from blends of cellulose acetate and carboxylated polysulfones of 0.43 and 0.75 degrees of carboxylation. The effects of degree of carboxylation on membrane characteristics such as compaction, pure water flux, water content and membrane hydraulic resistance, have been investigated to evaluate the performance of the membranes. The influence of the degree of carboxylation on the performance of the blend membranes of various blend polymer compositions has been investigated and also compared with earlier reports on blend membranes prepared from cellulose acetate and polysulfone or carboxylated polysulfone of 0.14 degree of carboxylation. © 2003 Society of Chemical Industry [source] | |||||||||||||