Poly Vinyl Alcohol Blend Research Articles

Super-Strong Nafion/PVA/Uhmwpe Membranes for Proton and Hydroxide Ion-Exchange Fuel Cells

Perfluorosulfonic acid (PFSA) ionomers have been used extensively in proton exchange membranes due to their high proton conductivity and strong electrochemical stability. However, proton and anion conductivity through the PFSA membranes are contingent upon water uptake, but high water content in the membrane causes loss of long-term durability of the fuel cell system because of the water swelling-induced reduction in membrane’s mechanical strengths. Large body of literatures are available to address these issues, for example, hydroscopic nanoparticulate fillers have been used for self-hydration of the membrane, and aligned polytetrafluoroethylene (PTFE) has been employed to reinforce the tensile strengths of the PFSA ionomer. Unfortunately, there is yet no report to date that can resolve pareto fronts issues, i.e., simultaneously having high proton conductivity and high tensile property. Besides, the cost of PFSA membranes, e.g., Nafion, is still prohibitively high. Here, we report a new and low-cost hierarchical membrane with high proton/anion conductivity, low moisture/methanol uptake and super-high tensile strengths. The new membrane is a hybridized composite structure consisting of biaxially oriented nanoporous ultrahigh molecular weight polyethylene (UHMWPE) film coated with Nafion and polyvinyl alcohol (PVA) blend. The tensile strength of the composite membrane is at least 10 times higher than that of the pure Nafion membrane when fully humidified, and the proton and alkaline conductivity is comparable to that of the Nafion/PVA blend. The nanoporous UHMWPE simultaneously acted to provide the high tensile strengths, ion-conductivity selectivity and nanoconfinement to limit the water and methanol uptake. Thus the new hierarchical Nafion/PVA/UHMWPE membrane is potentially an ideal ion-exchange membrane for low temperature hydrogen and direct methanol fuel cells. The work is financially supported by the theme-based research project of the university grants committee of Hong Kong, Grant No. T23-601/17-R

Controlled Release Behaviors of Tribenuron Methyl Herbicide and Potassium Nitrate Fertilizer from Natural Polymer Blended Poly(Vinyl Alcohol) Hydrogel Microspheres

Polyvinyl Alcohol (PVA) hydrogel microspheres for controlled release of fertilizer (KNO3) and Tribenuron Methyl Herbicide (TBM) were prepared by blending the naturally occurring Alginate (AL) and Pectin (PE). The cross-linking in PVA hydrogel microspheres was carried out by varying the amount of glutaraldehyde from 0.5-1.0 wt%. To control the loading and release properties of PVA hydrogel microspheres, a small amount of NaCl (0.2 wt%) was also added in formulation of microspheres. The blending of PE and AL in PVA hydrogel microspheres was confirmed with FT-IR spectra and by increased thermal stability PVA hydrogel as determined by Differential Scanning Calorimetry (DSC) and Thermogravimetric (TGA) analysis. The PVA hydrogel microspheres were characterized for degree of swelling and for loading and cumulative release of fertilizer (KNO3) and herbicide (TBM), which were carried out in solutions of different pH and at different temperatures. The Scanning Electron Micrographs (SEM) of PVA hydrogel microspheres were recorded before and after the release of loaded agrochemicals and used to confirm the shape and homogeneous blending of PE/AL in PVA hydrogels. The enhanced brittle morphology form SEM images of PVA hydrogel microspheres after the release of loaded agrochemicals has suggested the controlled release of agrochemicals through a mechanism of degradation of polymer chains. Thus natural polymer blended PVA hydrogel microspheres are found to be a potential candidate for the formulation of controlled release systems for the application of agrochemicals in soils and to overcome the environmental problem, which usually encountered on applications of fertilizers and herbicides in agricultural fields by conventional methods.

Development of high-performance polymer membranes for CO2 separation by combining functionalities of polyvinyl alcohol (PVA) and sodium polyacrylate (PAANa)

In the present study, integrated polymers having gas barrier and water sorption properties were prepared by effectively blending two types of polymers to fabricate membranes for high-performance CO2 separation. Namely, composite polymers were prepared as a new membrane material by uniformly blending polyvinyl alcohol (PVA), a gas barrier polymer, with sodium polyacrylate (PAANa), a water-absorbing polymer. The optimal PVA/PAANa blending ratio was determined by evaluating the thermal properties of the prepared polymer blend and the CO2 separation performance of the polymer blend membrane. When amine type additives such as polyamidoamine (PAMAM) dendrimer or polyallylamine (PAAm) were added to the prepared PVA/PAANa, the separation performance of the produced separation membrane increased. Applying a carbonate coating onto the PVA/PAANa membranes containing additives further increased the separation performance and selectivity of the membranes. These results demonstrated that the PVA/PAANa membranes prepared in this study, which featured both gas barrier and water absorption properties, could be used as high-performance membrane materials for CO2 separation.

Removal of Copper (II) Ion: Effect of Polysulfone Support Thickness

This study was conducted to characterize the industrial wastewater containing Copper (II) ion and to evaluate the effect of different thickness of polysulfone as the support membrane in the fabrication of thin film composite membrane (TFC), on the removal of Copper (II) ion. From the wastewater analysis, it showed that the concentration of copper (II) ion are out of the acceptable range of Environmental Quality (Industrial Effluent) Regulations 2009. For the TFC, the polysulfone support membrane was prepared at two thicknesses, 60μm and 90μm. For each thickness, two formulations of thin layer were coated on it; i) A polymer blend of Polyvinyl Alcohol and Chitosan, and ii) Hybrid membrane as thin layer. Before undergo the treatment process, the pH of the wastewater sample was altered to 7 as the pre-treatment. The final result shows that composite membrane with hybrid membrane as thin layer with 90μm thickness of polysulfone membrane was the best membrane because it could remove 99.67% of copper (II) ion. Finally, the treated water can be discharged to the groundwater because the concentration of copper ion is less than 1 ppm, which it has fulfilled the Environmental Quality regulations. Keywords— Chitosan, Copper ion, composite membrane, hybrid membrane, industrial wastewater

Adsorption of Lead(II) from Aqueous Solution Using Chitosan and Polyvinyl Alcohol Blends

The goal of the present paper is to explore the properties of medium molecular-weight chitosan/polyvinyl alcohol blends mixed in volume ratios of 75:25, 50:50, and 25:75 obtained by solution casting. Cross-linked chitosan/poly(vinyl alcohol) nanostructures were obtained by treating these blends with 5% (v/v) glutaraldehyde. The prepared chitosan/polyvinyl alcohol films were characterized by attenuated total reflectance – Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering, and cytotoxicity, while the nanostructured materials were examined by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Also, the removal of lead(II) ions from aqueous solution by adsorbents nanostructures was studied in the batch adsorption mode. The effects of adsorbent dosages, initial metal concentration, and contact time on the adsorption capacity were investigated. The FT-IR spectra indicated the interactions of polyvinyl alcohol with chitosan. DSC and TGA analyses revealed the loss of water up to 100 °C. The zeta potential and mobility of the prepared nanostructures were enhanced with the increasing ratio of the cationic polymer. The results showed that the 100% chitosan adsorbent provided the highest removal of Pb(II) during the first 15 min (̴94%). The chitosan100/polyvinyl alcohol0 and chitosan75/polyvinyl alcohol25 nanostructures fitted well with the Langmuir isotherm model. The maximum adsorption capacities for Pb(II) ions reached maxima of 7.36 and 7.67 mg/g, respectively. The Freundlich isotherm model best described the Pb(II) adsorption on the 50% chitosan/50% polyvinyl alcohol and 25% chitosan/75% polyvinyl alcohol adsorbents. Furthermore, (3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay results demonstrated that chitosan/polyvinyl alcohol films are biocompatible with more than 90% cell viability.

Composite hydrogels based on gelatin, chitosan and polyvinyl alcohol to biomedical applications: a review

Hydrogels produced from a single polymer show several disadvantages to biomedical applications. Binary and ternary blends of chitosan, gelatin, and polyvinyl alcohol can lead to hydrogels with better and desirable properties than those hydrogels made from a single polymer, which may be modulated on purpose. This article provides a brief overview of the advances in the fabrication of composite hydrogels using binary and ternary blends of gelatin, chitosan, and polyvinyl alcohol for biomedical applications, as well as different crosslinkers agents and crosslinking methods used to produce them. The availability of these materials will contribute to future biomaterials to biomedical applications.

PVA and PVP Hydrogel Blends for Wound Dressing: Synthesis and Characterisation

The purpose of this study is the development and characterizations of novel polyvinyl alcohol (PVA)/polyvinyl pyrolidone (PVP) hydrogel blends. Different mixtures of the two polymeric solutions leaded to several hydrogels that were further characterized using X-ray difraction (XRD), differential thermal and thermogravimetric analysis (DTA/TGA) and Fourier transform infrared spectroscopy (FTIR). The influence of the polymer type on hydrogel hydration was also studied, by observing and comparing the samples after drying and rehydration in bidistilled water. The results revealed the maintenance of the amorphous character of the hydrogels after rehydration as well as a higher softening and decomposition temperature in direct relation with the increase of PVA content. The best wetting and swelling results were also given by the hydrogel with the highest PVA content prepared at pH 6.

Fabrication and modeling of catalytic membrane for removing water in esterification

In this study, homogeneous catalyst “poly(styrenesulfonic acid)” and crosslinking agent “3-amino propyl methyl diethoxy silane” were added into the Polyvinyl alcohol to prepare the catalytic composite membrane (CCM). And the separation layer was prepared by blending polyvinyl alcohol and sodium alginate. Poly(styrenesulfonic acid) (PSSA) loaded CCM have been used to synthesize ethyl propionate in a pervaporation catalytic membrane reactor. The CCM was characterized by the SEM, FTIR and XRD. The pervaporation and catalytic performance of CCM were investigated under varying conditions (mass ratio of PSSA to PVA, 3-amino propyl methyl diethoxy silane content, heat treatment time). When the mass ratio of PSSA to PVA was 5:5, content of SCA-A10F was 20.0% to PSSA, the esterification conversion reached 91.6% after 12 h. The permeation flux and separation factor were 260 g m−2 h−1 and 91 respectively. Then the reaction kinetic model and separation kinetic model were established by Python least square method for the first time. Meanwhile, the theoretical maximum conversion curve and the PV coupling model conversion curve were proposed by combining the two models. It was found that the conversion of the actual coupling reaction was between the two model curves.

Nanoclay incorporation into soy protein/polyvinyl alcohol blends to enhance the mechanical and barrier properties

To enhance the mechanical and water barrier properties of soy protein isolate (SPI/)/polyvinyl alcohol (PVA) blends, montmorillonite (MMT), as a layered silicate clay was incorporated and SPI/PVA/MMT composite films were successfully prepared by melt processing in this work. The results showed that the structure of the composites was highly dependent on the MMT content. MMT nanofillers could act as the heterogeneous nucleating agent for PVA, which accelerated the crystallization and increased the size distribution of the crystalline. With the increase of MMT content, the tensile strength and Young's modulus of the composites increased, exhibiting the fine reinforcing effect. Due to the effective restriction of the highly disordered MMT lamellae on the matrix segment, the water sensitivity of the composites decreased and at the same time, the thermal stability improved. The resulting nanocomposite films exhibited wide applications as biodegradable materials, green packaging films, etc. POLYM. COMPOS., 40:3768–3776, 2019. © 2019 Society of Plastics Engineers

Polyvinyl alcohol-sodium alginate blend, composited with 3D-graphene oxide as a controlled release system for curcumin

A curcumin drug carrier was prepared by a polymer blend of polyvinyl alcohol (PVA) and sodium alginate (SA). Few layer graphene oxide (FL-GO) was synthesized and the PVA-SA blend was composited with 0, 1, 5, and 10 wt% of FL-GO. The effect of GO percentage on the swelling ratio and drug release was investigated. In addition, the kinetics of the drug release was studied to estimate the drug release mechanism for each case. SEM micrographs showed a 3D structure for GO (3D-GO) in the polymer composite after cross-linking. Curcumin was loaded in PVA-SA/3D-GO hydrogels for studying in vitro drug delivery systems. The 3D-GO effect on the hydrogels water uptake was also investigated. The 3D-GO generally could increase the swelling ratio up to 5 times and decrease drug release to 59%. Increasing in GO content caused a decreasing in swelling capacity and an increasing in drug release rate. Kinetic studies revealed that the Korsmeyer-Peppas model has a good fitting for PVA-SA/3D-GO 10 wt% and PVA-SA hydrogels as well as the zero order model for PVA-SA/3D-GO 1 wt% and 5 wt%.

Electrically Triggered Transdermal Drug Delivery Utilizing Poly(Acrylamide)-graft-Guar Gum: Synthesis, Characterization and Formulation Development

Objective: The study aimed to prepare electrically-triggered transdermal drug delivery systems (ETDS) using electrically responsive polyacrylamide-graft-gaur gum (PAAm-g-GaG) copolymer. Methods: The PAAm-g-GaG copolymer was synthesized by adopting free radical polymerization grafting method. This PAAm-g-GaG copolymer hydrogel acts as a drug reservoir and blend films of Guar Gum (GaG) and Polyvinyl Alcohol (PVA) were included as Rate Controlling Membranes (RCM) in the system. The PAAm-g-GaG copolymer was characterized by FTIR, neutralization equivalent values, thermogravimetric analysis and elemental analysis. Results: On the basis of results obtained, it is implicit that the drug permeation decreased with an increase in the concentration of glutaraldehyde and RCM thickness; while drug permeation rate was increased with increasing applied electric current strength from 2 to 8 mA. A two fold increase in flux values was observed with the application of DC electric current. An increase in drug permeation was witnessed under on condition of electric stimulus and permeation was decreased when electric stimulus was "off". The skin histopathology study confirmed the changes in skin structure when electrical stimulus was applied. Conclusion: The electrically-sensitive PAAm-g-GaG copolymer is a useful biomaterial for transdermal drug delivery application.

Effect of glutaraldehyde on thermal and mechanical properties of starch and polyvinyl alcohol blends

ABSTRACTThe aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch (S) blends. The blends have been cross-linked with glutaraldehyde to enhance its properties. The hydroxyl groups of PVA and starch react with glutaraldehyde via formation of acetal bonds hence crosslinking could take place. The cross-linking of glutaraldehyde is observed with the help of various analytical methods such as differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The presence of two highly reactive alpha protons makes glutaraldehyde more reactive and acidic in nature. The higher reactivity of glutaraldehyde, at higher dosages leads to reduction in H-bonding of PVA and starch. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile strength, pencil hardness, and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the mechanical properties are directly proportional to the amount of starch as the starch hydroxyl groups are easily accessible for the cross-linking reaction. The cross-linked blend showed better cohesion between its chains, thereby increasing the glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.

Effect of vinyl silane modification on thermal and mechanical properties of starch-polyvinyl alcohol blend

ABSTRACTThis study aims to observe the effect of addition of silane coupling agent on polyvinyl alcohol and starch-PVA blend. Starch and PVA blend with citric acid addition was prepared. Silane-modified polymer was obtained by treating polyvinyl alcohol and starch-PVA blend with Trimethoxyvinylsilane. The blend has been tested against the canarium wood substrate for tensile strength. A further property like viscosity has also been evaluated. Analytical tests such as DSC and DMA proved the phenomenon of cross-linking, having shown an increase in glass transition temperature and area under the curve of tan delta. The efficient and novel method for polymerization of vinyl groups present in the PVA and PVA-starch blends has contributed to better adhesion on the wood substrate and also better cohesion between the chains.

Green Nanocomposites Made With Polyvinyl Alcohol And Cellulose Nanofibers Isolated From Recycled Paper

This paper reports green nanocomposites made by blending polyvinyl alcohol (PVA) with cellulose nanofiber (CNF) isolated from recycled deinked copy/printing paper (DIP). The reinforcement effect of DIPCNF in the nanocomposites is compared with other CNFs isolated from native cotton and hardwood by means of TEMPO-oxidation. The prepared PVA-CNF nanocomposites are characterized in terms of morphology, chemical interaction, structural, thermal and mechanical properties. X-ray diffraction and Fourier transform infrared spectroscopy confirm the reinforcing ability of cellulose nanofibers into PVA. By blending CNFs into PVA matrix, the thermal stability of the nanocomposites is improved and DIPCNF shows similar enhancement effect with COCNF and HWCNF. The prepared nanocomposites exhibit 50% Young’s modulus improvement by adding 6% of CNF and DIPCNF exhibits similar enhancement of the mechanical properties to COCNF and HWCNF in the nanocomposites. This indicates that the use of DIPCNF is beneficial for environment protection, resource retaining and save energy in comparison with COCNF and HWCNF.

Electrospinning of natural rubber latex-blended polyvinyl alcohol

Abstract In this study, elastomeric fibers of natural rubber latex (NRL)/polyvinyl alcohol (PVA) blends were successfully fabricated via electrospinning technique. Polymer blend solutions at various proportions of NRL (i.e., high ammonia latex concentrate) and PVA with the addition of Triton X-100 surfactant were prepared and electrospun. The results revealed that the addition of Triton X-100 surfactant in polymer blend solutions could facilitate electrospinning process. Fiber morphologies and the production of micrometer-sized fibers were observed by scanning electron microscope (SEM). The presence of NRL in fibers was confirmed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, mechanical properties, swelling, and weight loss behaviors of elastomeric fibers were also investigated.

Study on Various Compositions of Polyvinyl Alcohol and Starch Blends by Cross-Linking with Glyoxal

The aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch blends. The blends have been cross-linked with glyoxal to enhance its properties. The hydroxyl groups of PVA and starch react with glyoxal via formation of acetal bonds; hence crosslinking could take place. The cross-linking of glyoxal is observed in various analytical methods such as DSC and FTIR. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile shear strength, pencil hardness and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the cross-linking is directly proportional to starch, since the starch hydroxyl groups are easily accessible for reacting. The cross-linked blend showed better cohesion between its chains, thereby increasing glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.

Thin film composite membranes: Preparation, characterization, and application towards copper ion removal

A novel thin film composite (TFC) membrane was fabricated from a thin layer of hybrid membrane formulated from a blend of polyvinyl alcohol (PVA)/chitosan and cross linked with tetraethylorthosilicate (TEOS), which was layered on the polysulfone (PSF) membrane. Besides producing membrane from polymer blend of PVA/chitosan only, concentrations of TEOS as cross linker was varied at 1 wt%, 3 wt% and 5 wt% with fixed concentration of PVA solution (10 wt.%) and chitosan (2 wt.%) respectively during the formulation of hybrid membranes. The thermal properties, mechanical strength, water contact angle, swelling measurement and anti-fouling behaviour of these membranes were investigated. The performance of the thin film composite was evaluated through filtration of the pure copper ion solution and the industrial wastewater containing copper respectively. The fabricated TFC with 3 wt.% TEOS was found to possess better tensile strength and strain, and thermal stability as compared with other concentration of TEOS. The membrane also exhibit good rejection of copper ion (> 90%) from pure copper solution especially at pH 7 of feed solution. A further treatment conducted on the wastewater reveals that TFC with 3 wt.% TEOS could remove the copper ion, where the filtered water could be directly discharged to the river. Furthermore, the TFC portrayed good anti fouling behaviour, where it have 3% of relative flux decay and 76% of relative flux recovery even with the presence of humic acid as NOM (natural organic matter).

Morphological, mechanical and physical properties of new whey protein isolate/ polyvinyl alcohol blends for food flexible packaging

Abstract Attempting to make whey protein isolate (WPI)-based films more suitable for application as food packaging, it is necessary to improve its brittleness, water barrier and solubility in water, for example, by adding another polymer to its matrix. This work objectives to understand the interactional phenomena between WPI and polyvinyl alcohol (PVOH) and to evaluate the effect of the addition of up to 30% of PVOH on flexibility, water vapor barrier and solubility in water of WPI films. FT-IR analysis of the blends showed the formation of new interactions and structures, while morphology analysis indicated a possible compatibility between the polymers. The addition of 30% of PVOH provided a more ductile material, increasing nine times the WPI elongation capability, leading to tensile properties close to that from commercial LPDE. PVOH addition did not act reducing puncture resistance or water barrier, but decreased solubility of WPI film in water. It is indicated the addition of 30% of PVOH in WPI matrix in order to improve its flexibility and reduce solubility in water.

Fabrication of Nanofibrous PVA/Alginate-Sulfate Substrates for Growth Factor Delivery.

Providing affinity sites on alginate (ALG) matrix enables specific binding of growth factors to the polymer backbone and allows their release in a controlled fashion. In this study, we used a blend of alginate sulfate (ALG-S) and polyvinyl alcohol (PVA) to fabricate electrospun scaffolds capable of delivering a heparin-like growth factor, transforming growth factor-beta1 (TGF-β1). The alginate was sulfated with different degrees of sulfation (DS, from 0.8, 3.4 to 12.4%) by a simple process. The success of sulfation was determined by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), elemental analysis, ultraviolet (UV) spectroscopy and staining with dimethylmethylene blue. The physical-mechanical properties of nanofibrous mats were characterized by scanning electron microscopy (SEM), FTIR, energy-dispersive X-ray spectroscopy (EDX), tensile strength and mass loss analysis. Additionally, the release kinetics of transforming growth factor-β1 (TGF-β1) from PVA/ALG-S and PVA/ALG scaffolds were compared. The results showed that the binding and entrapment of TGF-β1 to the nanofibrous scaffolds are improved by the addition of sulfate group to alginate. In conclusion, our results support that nanofibrous scaffold based on PVA/ALG-S can deliver growth factors in tissue engineering application. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 403-413, 2019.

To study the effect of boric acid modification on starch–polyvinyl alcohol blend wood adhesive

Starch–polyvinyl alcohol blends with enhanced properties are achieved with cross-linking it with boric acid. These blends are characterized by FTIR and DSC. A film of starch and PVA blends were prepared by casting on glass plate. The effects of various factors such as increasing starch content, increasing amount of boric acid, on the performance properties like tensile strength, pencil hardness and thermal properties like glass transition temperature were studied. The results showed that the starch–polyvinyl alcohol films prepared by boric acid cross-linking had excellent mechanical, thermal properties and hardness of the film.