Properties Of Blend Membranes Research Articles

Fabrication of graphene oxide blended polyethersulfone membranes via phase inversion assisted by electric field for improved separation and antifouling performance

Novel antifouling blend polyethersulfoune (PES) membranes were prepared via phase inversion assisted by a direct current (DC) electric field with the addition of extremely low concentration of graphene oxide (GO). The GO particles were observed migrating toward the anode and better distributed in the casting solution with a DC electric field exerted. The effect of the applied DC electric field intensity on the properties of blend membranes was systematically investigated. The enrichment of GO on the membrane surface assisted by the electric field was confirmed by the enhanced hydrophilicity and negative charge density, and the XPS results. The blend PES membrane prepared under an electric field of 5000 V cm−1 exhibits not only a high water flux (289.63 Lm−2h−1), which is more than double of the pristine PES membrane (137.67 Lm−2h−1), but also an improved methyl red rejection. The membrane fouling performance was studied with bovine serum albumin (BSA) as model protein. The PES/GO membranes prepared under a 5000 V cm−1 electric field showed an obviously increased flux recovery ratio (FRR) and a decreased irreversible fouling ratio (Rir) value, compared to ones without using an electric field. The membrane fabrication assisted by an electric field opens a new way to enhance hydrophilicity, charge density, separation performance and antifouling ability of mixed matrix membranes.

Preparation of partially end-capped amino-terminated hyperbranched polymer and dyeing properties enhancement to polyurethane membrane

In this study, a series of products with different water solubility, which were named as partial end-capped amino-terminated hyperbranched polymers (HBPs) 1–6, were obtained by changing the mass ratio of raw materials. The structure was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The polyurethane was respectively mixed with partial end-capped amino-terminated HBPs to prepare different blend membranes by the drying method. The results showed that the water solubility of partial end-capped amino-terminated HBPs had obvious effects on the dyeing properties of blend membranes. When the mass ratio of amino-terminated HBP and single-blocked isophorone diisocyanate was 3:2, the performance of prepared partial end-capped amino-terminated HBP 4 was the best. The structures of blend membranes were characterized by FTIR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). When the mass fraction of partial end-capped amino-terminated HBP 4 was 2%, dye uptake improved from 12% to 85%. The dry-rub fastness and wet-rub fastness reached 4.5 and 3, respectively. The K/S values indicated that the surface chroma also deepened. The results indicated that partial end-capped amino-terminated HBP and polyurethane had hydrogen-bond interaction and certain phase separation.

The effect of sulfonated polysulfone on the compatibility and structure of polyethersulfone-based blend membranes

Polymer blend is the most common method to improve membrane hydrophilicity, in which the compatibility between the polymers is an important factor affecting the structure and properties of blend membranes. Polyethersulfone (PES)-based blend membranes were prepared from PES/polysulfone (PSf)/N, N-dimethylacetamide (DMAc) and PES/sulfonated polysulfone (SPSf)/DMAc casting solutions with water as coagulant via non-solvent-induced phase inversion, respectively. The compatibility of blend systems and membrane formation processes were investigated through thermodynamics and kinetics analyses. Ultrasonic through-transmission measurements were performed to quantify the rate of membrane formation during the phase inversion process. The effect of SPSf on the compatibility and morphologies of PES-based blend membranes was characterized by Schneier theory, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) etc. Results indicated that the PES/PSf blend system was partially compatible, leading to instantaneous demixing and the obtained membrane with finger-like structure, whereas the PES/SPSf blend system was entirely miscible, resulting in delayed demixing and the obtained membrane with sponge-like asymmetrical gradient structure. Simultaneously, the surface segregation behavior of SPSf with hydrophilic sulfonic acid groups during the mutual diffusion process resulted to the enhancement of PES/SPSf membrane hydrophilicity. Consequently, PES/SPSf blend membrane showed excellent water permeability and better antifouling ability.

Fabrication and characterization of dense Chitosan/polyvinyl-alcohol/poly-lactic-acid blend membranes

Dense membranes of Chitosan (CS)/Poly(vinyl alcohol) (PVA)/Poly(lactic acid) (PLA) blend were successfully fabricated using casting technique. The mechanical properties, moisture regain and water vapor permeability of polymer blend membranes were estimated by tensile test, moisture regain rate and dish method test respectively. The microstructures, morphology, chemical composition and thermal properties were also characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) respectively. Results indicated that there were interactions and good compatibility among CS, PLA and PVA. And the blend membranes have good breaking elongation and slightly decreased breaking strength, and show best moisture regain at the case of CS60 (the content of CS in the blends is 60 %). They also have excellent porous structure, which is beneficial to their air permeability and may also contribute to cell regeneration. With the adding of PVA content, the melting peaks of blend membranes reduce and gradually close to that of PVA, demonstrating that the regularity of CS molecular chain may be destroyed and hydrogen bonds of macromolecules in polymers were newly formed. As a result, solution blending of the three polymers could complement their disadvantages and significantly improve the membrane performance of a single polymer, thus promote the mechanical and biological properties of blend membrane.

Characterization Of Chitosan-chondroitin Sulfate Blended Membranes And Effects On The Growth Of Corneal Cells

In order to construct a suitable scaffold for corneal cell culture and transplantation in vitro, different chitosan-chondroitin sulfate blended membranes were prepared and the properties of blended membranes were studied. Corneal stroma cells and corneal endothelial cells were seeded onto the blended membrane surface and the effects of the blended membranes on corneal cell attachment and metabolism were investigated. The results showed that chitosan and chondroitin sulfate had good compatibility in blended membranes. Chondroitin sulfate improved the homogeneousness, crystallization, transparency, and tensile strength and decreased the water content of the blended membrane. Within the blending ratio of 1:0.1, chondroitin sulfate reduced the damage of chitosan membranes to cells and improved the biocompatibility between cells and membranes. Corneal cells grew and formed a confluent monolayer on chitosan-chondroitin sulfate blended membranes (CH-CS3). All results indicated that the blended membranes of chitosan and chondroitin sulfate could be used as a scaffold for corneal cell culture in vitro and have potential to be used as carriers for corneal endothelial cell transplantation. Copyright © 2010 VBRI press.

POLYETHERSULFONE/CELLULOSE CRYSTAL BLEND MEMBRANES AND THEIR ULTRAFILTRATION PERFORMANCE

The casting solution was obtained by blending polyethersulfone ( PES) and cellulose crystal in dimethylacetamide ( DMAC ). PES /cellulose crystal blend membranes were prepared by the immersion precipitation phase inversion process. The effects of cellulose crystal content on the properties of blend membranes were discussed. The pure water flux,rejection ratio,porosity,mean pore size and anti-fouling property were tested in the ultrafiltration equipments. Also,the mechanical properties,thermal stability and morphology were characterized by tensile testing,thermogravimetric analysis ( TGA ) and atomic force microscopy ( AFM). The results showed that at first,the pure water flux of blend membranes was greatly improved with the increasing of cellulose crystal content,but then it decreased to some extent. All the rejection ratios remained at 91% ～ 95% . The tendencies of tensile strength and elongation curses were the same as the one of pure water flux curve. The anti-fouling property of blend membrane had been improved. When the mass fraction of cellulose crystal was 1% ,the pure water flux got to a maximum,813. 3 L·m -2·h -1; porosity was 88. 8% and mean pore size was 70. 9 nm. At the same condition,tensile strength was 7. 25 MPa and elongation was 11. 6% . In addition,fouling degree (FR value) and attenuation coefficient of fouling (m value) were 22. 0% and 35. 8% ,respectively. There were two weight loss stages in the blend membrane,due to thermal degradation of PES and cellulose crystal,respectively. The typical asymmetric membrane structure was displayed in the blend membrane. The surface layer of the blend membrane was dense,and the support layer had larger size pores. Both of them composed the typical asymmetric membrane structure.

Maleic Anhydride Crosslinked Alginate-Chitosan Blend Membranes for Pervaporation of Ethylene Glycol-Water Mixtures

Calcium alginate-chitosan (CA/CS) blended membranes were prepared and crosslinked with maleic anhydride (MA) for the pervaporation (PV) separation of ethylene glycol (EG)/water mixtures at 30°C. The structure and properties of blend membranes were studied with the aid of FTIR, XRD, TGA, and SEM. The effect of experimental parameters such as feed composition, membrane thickness, and permeate pressure on separation performance of the MA crosslinked membranes were determined in terms of flux, selectivity, and pervaporation separation index. Sorption studies were carried out to evaluate the extent of interaction and degree of swelling of the blend membranes in pure, as well as in binary mixtures. The experimental results suggested that the crosslinked membrane (M-CA/CS) exhibited a good selectivity of 302 at a normalized flux of 0.38 kg.m− 2.h− 1.10 μ m at 30°C for 96.88 wt% EG aqueous solution.

Polymer blend membranes of sulfonated poly(arylene ether ketone) for direct methanol fuel cell

The blend membranes of sulfonated poly(arylene ether ketone) (sPAEK) (IEC = 1.0 mequiv./g)/Nafion ® and the blend membranes of sPAEK (IEC = 1.0 mequiv./g)/sPAEK (IEC = 1.7 mequiv./g) were prepared. sPAEK with low IEC was introduced to reduce the methanol permeability through the membrane. Morphology, water uptake, proton conductivity and methanol permeability of the blend membranes were investigated by SEM, AFM, AC impedance spectroscopy and permeability measuring instrument. The cross-sections of blend membranes showed phase-separated morphologies. The effect of phase-separated morphology on the properties of blend membranes was investigated. The properties like water uptake, proton conductivity, and methanol permeability of sPAEK/Nafion ® blend membranes showed similar values with sPAEK and properties of sPAEK/sPAEK blend membranes showed intermediate values of two polymers due to the difference in morphology of the blend membranes. sPAEK/sPAEK blend membranes showed relatively high proton conductivity and lowered methanol permeability compared to Nafion ®. sPAEK/sPAEK blend membranes could be a competent substitution for Nafion ®.