Design and Characterization of PVA–Methacrylic Acid Based Smart Polymeric System for Controlled Release of Metoprolol

In the present work covalently crosslinked smart polymeric system of hydrogel based on poly vinyl alcohol (PVA) and methacrylic acid (MA) was designed by free radical polymerization with different compositions using glyoxal (40 % water solution) as crosslinker. It was observed that swelling of hydrogel had a pronounced enhancing effect on increasing the concentration of MA due to availability of more ionized carboxylic groups of MA but produced an opposite effect on increasing the concentration of glyoxal owing to less porous structure. As far as PVA is concerned, swelling did not show significant effect on increasing the concentration of PVA. Hydrophilic polymer PVA rich in hydroxyl group pertained to be highly interactive with water. It was examined that the release of metoprolol tartrate decreased with increased concentration of glyoxal, but increased with increase in concentration of MA. PVA/MA hydrogel was characterized by Fourier transform infrared spectroscopy and X-ray diffraction to study the structure and crystallinity of hydrogel respectively. Morphology was studied through scanning electron microscopy. Furthermore differential scanning calorimetry and thermogravimetric analysis were also performed to characterize thermal stability. It may be concluded that the mechanism of drug release was mainly non-Fickian diffusion.     

Synthesis and Properties of Biodegradable Poly(vinyl alcohol)/Organo-nanoclay Bionanocomposites

Biodegradable nanocomposites comprising of biodegradable polymers and bioactive organically modified layered silicates commonly reveal extremely enhanced mechanical and various other properties when compared to those of virgin polymers. This work was undertaken with a view to preparation of polymer bionanocomposites consisting of biodegradable poly(vinyl alcohol) (PVA) and organo-nanoclay. Cloisite Na⁺ and ammonium salt of l-isoleucine amino acid was used for the preparation of the novel chiral organo-nanoclay via an intercalation reaction in an aqueous solution. PVA/organo-nanoclay bionanocomposites of various compositions were created through the solution intercalation method by ultrasound-assisted technique. The resulting novel materials were characterized by X-ray diffraction and Fourier transform infrared spectroscopy techniques. Thermogravimetric analysis (TGA) and UV/vis spectroscopy were applied to test the properties of PVA bionanocomposites. TGA indicate that the thermal stability is enhanced distinctly, without a sacrifice in optical clarity. The improvement of thermal properties was attributed to the homogeneous and good dispersion of organo-nanoclay in polymeric matrix and the strong hydrogen bonding between O?CH groups of PVA and the oxygen atoms of silicate layers or carbonyl group as well as OH group of intercalated amino acid. The morphology of the organo-nanoclay and PVA bionanocomposites was examined by scanning electron microscopy and transmission electron microscopy techniques. Uniform distribution of clay due to intimate interaction between clay and polymer appears to be the cause for improved properties.     

Synthesis and Characterization of Chitosan-Grafted-Poly(2-Hydroxyaniline) Microstructures for Water Decontamination

Chitosan as a biopolymer, biodegradable, safe, non-toxic and widely abundant in nature was grafted with poly(2-hydroxyaniline) (P2-HA) through aqueous chemical oxidative copolymerization using ammonium persulphate in acetic acid medium. The grafting conditions were studied by varying grafting parameters. The effect of oxidant, 2-hydroxyaniline (2-HA) and acetic acid concentrations on the rate of copolymerization was studied. The synthesized graft characterized using UV–Vis, FTIR, TGA, XRD, and scanning electron microscope and compared with chitosan and P2-HA. The grafting enhances the thermal properties of chitosan. The effect of temperature on the rate of grafting copolymerization reaction was studied. The apparent activation energy (Ea) of the copolymerization reaction found to be 21.1116 kJ/mol. Also, ΔH^* and ΔS^*, were calculated and found to 22.8630 kJ/mol and ?109.4290 J/mol K respectively. The mechanism of the grafting copolymerization reaction discussed. Chitosan, P2-HA and chitosan-graft-P2-HA used for the removal of Cr, Fe, Mn, Cu and Zn divalent ions from a contaminated water samples. The adsorption isotherm parameters are given.     

Potassium Release Kinetics and Water Retention of Controlled-Release Fertilizers Based on Chitosan Hydrogels

Controlled release fertilizer (CRF) hydrogels were prepared from poly(vinyl alcohol), poly(vinyl alcohol)/chitosan and chitosan using glutaraldehyde as a crosslinker. Intermolecular interactions of the CRF hydrogels were elucidated using FTIR. Water absorbency characteristics of the CRF hydrogels were also studied. It was found that the CRF hydrogels exhibited the equilibrium swelling ratio (SR) in the range 70–300%. The water retention of soil containing the CRF hydrogels was also examined. It was found that the CRF hydrogels increased the water retention of the soil. After 30 days, soil containing the PVA-, PVA/CS- and CS-hydrogels showed the water retention capacities of 25%, 10% and 4%, respectively. While the soil without the CRF hydrogel had already given off most of the water. The release behavior of potassium from the CRF hydrogels, both in deionized water and in soil, was investigated. In soil, the potassium release mechanism from the PVA- and PVA/CS-hydrogels were non-Fickian diffusion. On the other hand, the CS hydrogel showed, n value that was close to 1.0 corresponding to case II transport. In deionized water, all the CRF hydrogels showed small values of release exponent (n < 0.5) indicating a quasi-Fickian diffusion mechanism.     

Influence of pH and C/N Ratio on Poly(Vinyl Alcohol) Biodegradation in Mixed Bacterial Culture

Cultivation conditions affecting poly(vinyl alcohol) (PVA) degradation by a mixed bacterial culture of Bacillus sp. and Curtobacterium sp. were investigated. Bacterial strains used in this study were isolated from the watercourse and the sewage sludge of vinylonfibre mill by enrichments on PVA as the sole carbon source. The results showed that PVA was greatly degraded under the following conditions: 0.5% PVA as a substrate at the initial medium pH of 8 with 0.15% glucose and urea at C/U ratio 1.5:1 and 1% bacterial inoculum, at a temperature of 35 °C and a shaking speed of 110 rpm. The analysis of FTIR and ¹H NMR spectra before and after biodegradation indicate fission of the PVA molecular chain during the incubation.     

Effect of Ionizing Radiation on the Morphological,Thermal and Mechanical Properties of Polyvinyl Alcohol/Polyethylene Glycol Blends

Blends of water—soluble polymers based on Poly vinyl alcohol (PVA) and Polyethylene glycol (PEG) have been prepared by the solution casting technique. The effect of various doses of γ-radiation on the structural properties of PVA/PEG polymer blends with all its compositions has been investigated. From the visual observation of all the blend compositions, it was found that, the best compatibility of the blend is up to 40% PVA/60%PEG. The structure–Property behavior of all the prepared blends before and after γ-irradiation was investigated by IR Spectroscopy, thermogravimetric analysis (TGA), mechanical properties and Scanning electron microscope (SEM). The gel content and the swelling behavior of the PVA/PEG blends were investigated. It was found that the gel content increases with increasing irradiation dose and PVA concentration in the blend. Swelling percent increased as the composition of PEG increased in the blend. The results obtained by FTIR analysis and SEM confirm the existence of possible interaction between PVA and PEG homopolymers. TGA of PVA/PEG blend, before and after γ-irradiation, showed that the unirradiated and irradiated PVA/PEG blends are more stable against thermal decomposition than pure PVA. Improvement in tensile mechanical properties of PVA/PEG blends was occurred.     

Characterization of Biodegradable Composite Films Prepared from Blends of Poly(Vinyl Alcohol), Cornstarch,and Lignocellulosic Fiber

Several composite blends of poly(vinyl alcohol) (PVA) and lignocellulosic fibers were prepared and characterized. Cohesive and flexible cast films were obtained by blending lignocellulosic fibers derived from orange waste and PVA with or without cornstarch. Films were evaluated for their thermal stability, water permeability and biodegradation properties. Thermogravimetric analysis (TGA) indicated the suitability of formulations for melt processing, and for application as mulch films in fields at much higher temperatures. Composite films were permeable to water, but at the same time able to maintain consistency and composition upon drying. Chemical crosslinking of starch, fiber and PVA, all hydroxyl functionalized polymers, by hexamethoxymethylmelamine (HMMM) improved water resistance in films. Films generally biodegraded within 30 days in soil, achieving between 50–80% mineralization. Both starch and lignocellulosic fiber degraded much more rapidly than PVA. Interestingly, addition of fiber to formulations enhanced the PVA degradation.     

Biodegradable Green Glove Containing Ascorbic Acid from Maleated Epoxidized Natural Rubber/Poly(vinyl alcohol) Blend: Preparation and Physical Properties

Journal of Polymers and the Environment - The objective of this work was to prepare a maleate epoxidized natural rubber (MENR) and poly(vinyl alcohol) (PVA) (MENR/PVA) blend in the presence of...     

Biodegradation Behavior of Composite Films with Poly (Vinyl Alcohol) Matrix

The main objective of this study was to develop biodegradable, composite materials, based on poly (vinyl alcohol), bacterial cellulose and chitosan for possible application in packaging industry. Two composite materials were prepared, one containing poly (vinyl alcohol) (PVA) and bacterial cellulose (BC), named PVA/BC, and the other containing PVA, BC but also chitosan (CTS), named PVA/BC/CTS. The biodegradation behavior was studied in a fed-batch bioreactor, in aerobic and anaerobic conditions, using activated sludge. Biodegradation tests were based on weight loss measurements. Structural changes were confirmed by Fourier transform infrared spectroscopy (FTIR) and the morphological ones by scanning electron microscopy (SEM). After 4?weeks, the biodegradation experiments have shown a relative high degradation of the PVA/BC/CTS film compared with the PVA/BC one. These results were confirmed by spectral analysis and also by SEM images. Besides, the SEM images revealed that biodegradation occurs also inside the composite materials, not only on the surface.     

Biodegradable Films Based on Blends of Gelatin and Poly (Vinyl Alcohol): Effect of PVA Type or Concentration on Some Physical Properties of Films

The aim of this work was to develop biodegradable films based on blends of gelatin and poly (vinyl alcohol) (PVA), without a plasticizer. Firstly, the effect of five types of PVA with different degree of hydrolysis (DH) on the physical properties of films elaborated with blends containing 23.1% PVA was studied. One PVA type was then chosen for the study of the effect of the PVA concentration on the mechanical properties, color, opacity, gloss, and water solubility of the films. The five types of PVA studied allowed for films with different characteristics, but with no direct relationship with the DH of the PVA. Therefore, the PVA Celvol^®418 with a DH = 91.8% was chosen for the second part, because they produced films with greater tensile strength. The PVA concentration affected all studied properties of films. These results could be explained by the results of the DSC and FTIR analyses, which showed that some interactions between the gelatin and the PVA occurred depending on the PVA concentration, affecting the crystallinity of the films.     

Fabrication and Study of Poly (vinyl alcohol) Film Functionalized with Basella alba Stem Extract

Journal of Polymers and the Environment - In this study eco-friendly composite films were prepared based on poly(vinyl alcohol) (PVA) containing different content of Basella alba stem extract (BA)...     

Novel Silica Functionalized Monosodium Glutamate/PVA Cross-Linked Membranes for Alkali Recovery by Diffusion Dialysis

Journal of Polymers and the Environment - In this work, two types of silica functionalized monosodium glutamate (GMSG and VMSG)/poly(vinyl alcohol) (PVA) were cross-linked by sol–gel process...     

Novel malonate-type copolymers containing vinyl alcohol blocks as biodegradable segments and their builder performance in detergent formulations

Poly[(disodium methylene malonate)-co-(vinyl alcohol)] [P(DSMM-VA)] and poly[(disodium ethoxymethylene malonate)-co-(vinyl alcohol)] [P(DSEMM-VA)] containing a poly(vinyl alcohol) (PVA) block as a biodegradable segment were prepared and their biodegradability and functionality were evaluated and compared with those of the corresponding fumarate and maleate copolymers. It was found that the 1,1-dicarboxylate-type copolymers, P(DSMM-VA) and P(DSEMM-VA), showed better biodegradability than the corresponding 1,2-dicarboxylate-type copolymers, P(DSF-VA) and P(DSM-VA). This improved biodegradability of P(DSMM-VA) and P(DSEMM-VA) is probably attributable to their more expanded polymer chain in aqueous solution, which will be more accessible to the degrading enzymes. The minimum chain length of the PVA-block, which acts as a biodegradable segment in the polymer chain, is estimated to be 2–3 and 3–4 monomer units for P(DSMM-VA) and P(DSEMM-VA), respectively. On the other hand, the minimum PVA block is about 5 and 7 monomer units for the fumarate and maleate copolymers, respectively. It was confirmed that P(DSMM-VA) showed excellent builder performance compared to the corresponding fumarate copolymer.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.     

An Effect of Salt Concentration and Inoculum Size on Poly(Vinyl Alcohol) Utilization by Two <Emphasis Type="Italic">Sphingomonas</Emphasis> Strains

Due to its widespread use and water solubility, poly(vinyl alcohol) (PVA) has the potential to find its way into various water or soil ecosystems. Despite the fact that many bacterial species with the capacity of utilizing PVA have been found and described, the influences of some environmental factors on their capabilities to biodegrade PVA have not been adequately studied. Therefore, study was made of the effects of two environmental factors on PVA degradation exhibited by two Sphingomonas strains. Both strains originated from common wastewater treatment plants, and proved to be considerably sensitive to increased inorganic salt concentrations; in brief, 13.3 mmol/l either of phosphate or chloride ions significantly delayed the degradation process or inhibited it entirely. In contrast to such halosensitivity, both strains were able to rapidly utilize PVA under suitable conditions, even when low inoculum sizes were applied. Initial cell densities, ranging from 10⁰ to 10⁷ cells/ml, were used in two series of degradation trials and PVA degradation occurred in all cases; merely delays extending over several days in the degradation process were noted when inoculum sizes of 10⁰–10³ cells/ml were applied.     

Application of ameliorated wood pulp to recover Cd(II), Pb(II), and Ni(II) from e-waste

In this study, dl-malic acid and hydrogen peroxide were used as leaching agents to remove metals from e-waste (printed-circuit boards) and itaconic acid-grafted poly(vinyl alcohol)-encapsulated wood pulp (IA-g-PVA-en-WP) to uptake metals from leachate with high proficiency [11.63 mg g^?1; 93.03 % for Cd(II), 11.90 mg g^?1; 95.18 % for Pb(II), and 12.14 mg g^?1; 97.08 % for Ni(II)]. Metals were recovered from the loaded biosorbent by desorption studies. The standard analytical techniques, such as elemental analysis, Fourier-transform-infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and thermogravimetric analysis, were used to characterize the recovering agent (biosorbent). At equilibrium, the metal uptake data were fitted to Langmuir and D–R isotherms (R ² > 0.99) significantly, revealing, the homogeneous distribution of active sites on biosorbent’s backbone. The possible mechanism appeared to be ion exchanges of metal ions with H⁺ together with binding over functionalities (COO^?). Dimensionless equilibrium parameter (R _L) showed the favourability of metal uptake at lower concentration, while mean adsorption energy (E) certified the physical binding of metal on functionalities which was further confirmed by sticking probability and activation energy parameters. Reusability studies were also conducted to state the performance of biosorbent.     

Preparation and Optimization of Starch/Poly Vinyl Alcohol/ZnO Nanocomposite Films Applicable for Food Packaging

Pollution and destruction of the environment due to the accumulation of non-degradable plastics are some of the most important concerns in the world. A significant amount of this waste is related to the polymers used in food packaging. Therefore, experts in the food industry have been looking for suitable biodegradable alternatives to synthetic polymers. Preparing biocompatible and biodegradable films based on starch is a good choice. In this study, various factors affecting films of starch/polyvinyl alcohol (PVA)/containing ZnO nanoparticles such as the amount of starch, PVA, glycerol, and ZnO were evaluated by response surface methodology (RSM). Film formation by solvent casting method, mechanical properties, swelling, solubility, and water vapor permeability (WVP) were selected as responses of RSM. The results showed that hydrogen bonding interactions between polyvinyl alcohol and starch improved the film formation. The effect of glycerol and PVA content on the mechanical strength was contrary to each other. As the amount of PVA increased, the tensile strength first decreased and then increased. The value of WVP was for all Runs from 0 to 6.77?×?10^??8 g m^??1 s^??1 Pa^??1. Finally, films with high film formation, maximum tensile strength, and high elongation at break, minimum solubility, permeability, and swelling were optimized.

     

Synthesis of CS/PVA Biodegradable Composite Nanofibers as a Microporous Material with Well Controllable Procedure Through Electrospinning

In this study, we have showed a facile route for fabrication of a novel microporous material based on chitosan (CS) and poly(vinyl alcohol) (PVA) biodegradable nanofibers that have high specific surface area, considerable porosity, and small diameter. Scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area analysis, and CHNS/O elemental analyser were applied to characterize the fabricated CS/PVA composite nanofibers. Moreover, the influences of spinning conditions including concentration, voltage, electrospinning distance, and flow rate, on size distribution and pore diameter of the final product were systematically studied using 2^k?1 factorial design experiments, and the response surface optimization was used for determining the best synthesis parameter. The results obtained from 2^K?1 factorial design experiments showed that electrospinning parameters influenced the size distribution and pore diameter of the CS/PVA microporous material. Based on the response surface methodology, the CS/PVA product could be obtained with a high microporous diameter of 1.8 nm and a small diameter distribution of 15.0 nm under optimized conditions. The obtained results showed that the fabricated samples could be utilized in different applications.     

Photocatalytic Degradation of Poly(Vinyl Alcohol) on Pt/TiO<Subscript>2</Subscript> with Fenton Reagent

In this research Fenton reagent (Fe²⁺/H₂O₂) was investigated as oxidants to degrade poly (vinyl alcohol) (PVA). The role of nano-TiO₂ photocatalyst was discussed as an additive in Fenton reagent (Fe²⁺/H₂O₂). Pt/TiO₂ composites were also synthesized by photo-reaction to be used as additive in Fenton reagent. The rapid degradation of PVA was obtained when Pt/TiO₂ composites served as photocatalyst. The different photocatalytic efficiency of Pt/TiO₂- Fenton reagent (Fe²⁺/H₂O₂) was studied compared with TiO₂- Fenton reagent (Fe²⁺/H₂O₂) during the degradation of PVA.     

Preparation and Characterization of Gamma Irradiated Sugar Containing Starch/Poly (Vinyl Alcohol)-Based Blend Films

Blends based on different ratios of starch (35–20%) and plasticizer (sugar; 0–15%) keeping the amount of poly(vinyl alcohol) (PVA) constant, were prepared in the form of thin films by casting solutions. The effects of gamma-irradiation on thermal, mechanical, and morphological properties were investigated. The studies of mechanical properties showed improved tensile strength (TS) (9.61 MPa) and elongation at break (EB) (409%) of the starch-PVA-sugar blend film containing 10% sugar. The mechanical testing of the irradiated film (irradiated at 200 Krad radiation dose) showed higher TS but lower EB than that of the non-radiated film. FTIR spectroscopy studies supported the molecular interactions among starch, PVA, and sugar in the blend films, that was improved by irradiation. Thermal properties of the film were also improved due to irradiation and confirmed by thermo-mechanical analysis (TMA), differential thermo-gravimetric analysis (DTG), differential thermal analysis (DTA), and thermo-gravimetric analysis (TGA). Surface of the films were examined by scanning electron microscope (SEM) image that supported the evidence of crosslinking obtained after gamma irradiation on the film. The water up-take and degradation test in soil of the film were also evaluated. In this study, sugar acted as a good plasticizing agent in starch/PVA blend films, which was significantly improved by gamma radiation and the prepared starch-PVA-sugar blend film could be used as biodegradable packaging materials.     

Physicochemical and Antibacterial Evaluation of Poly (Vinyl Alcohol)/Guar Gum/Silver Nanocomposite Films for Food Packaging Applications

Journal of Polymers and the Environment - In this study, we prepared Poly (vinyl alcohol) (PVA)/Guar gum (GG) based nanocomposite films with a different weight ratio of silver nanoparticles (AgNPs)...