Different Amounts Of Polyvinyl Alcohol Research Articles

Research and performance analysis of water-resistant phosphogypsum masonry materials

Phosphogypsum is a solid waste produced by the phosphoric acid industry. With the development of the phosphoric acid industry, the emissions of phosphogypsum are increasing year by year and its recycling rate is low. The environmental problems caused by tailings storage are becoming increasingly serious. The chemical formula of the main component of phosphogypsum is . its performance is similar to that of natural gypsum. Using phosphogypsum as a raw material to produce phosphorus building gypsum is one of the main ways to utilize phosphogypsum resources. However, phosphogypsum building materials have poor water resistance and low strength, which greatly limits their application. Based on the analysis of the poor resistance mechanism of phosphogypsum, this paper analyzed and studied the mechanical and water resistance properties of phosphorus building gypsum by separately adding different amounts of polyvinyl alcohol and silane emulsion and mixing polyvinyl alcohol and silane emulsion . The conclusion is that adding waterproofing agents and water-reducing agents can greatly improve the water resistance of phosphogypsum building materials.

Effects of polyethylene and polyvinyl alcohol on growth and protease activity of Acanthopagrus schlegelii juveniles

Many plastic products are used in aquaculture. Studying the toxicological effects of plastics differing in water solubility on marine organisms can provide valuable information. In this study, different amounts of polyvinyl alcohol (PVA) and polyethylene (PE) films were embedded in the feed and fed to Acanthopagrus schlegelii. After 1, 2, 4, and 8 weeks, the changes in percentage weight gain (PWG), feed efficiency (FE), pepsin activity (PA), and trypsin activity (TA) were observed. Either fed to PE or PVA, PWG, and FE of the experimental group were lower than those of the control group after eight weeks. Plastics level recovered from digestive tracts, feces, and water were higher in the PE groups than in the PVA groups. PA rose with increased feeding of plastics, but TA showed the opposite trend. TA activity decreased with increased feeding of plastics. Further analysis showed that TA was positively correlated with PWG.

Enhancing Polyantimonic-Based Materials’ Moisture Response with Binder Content Tuning

Humidity sensors are of huge importance in diverse domains. Several types of materials present a moisture-sensing capacity; however, frequently, their electrical response does not display time stability. Due to its high thermal stability, high ionic conductivity, and different conduction mechanism contributing to its overall conductivity, polyantimonic acid (PAA) is seen as a promising material for humidity-sensing devices. In the present work, crystalline PAA was obtained via a simple and safe hydrolysis technique using SbCl3 as a precursor. Bulky sensor samples were produced using different amounts of polyvinyl alcohol (10–20 wt.% PVA) as a binder. The obtained PAA solid sensors were tested at room temperature (RT) in order to evaluate their moisture detection/measuring ability in the relative humidity range 0–100%; the evaluation was carried out with electrical impedance spectroscopy. The sample’s structure and morphology were studied using diverse experimental techniques (porosimetry, scanning electron microscopy, X-ray diffraction analysis, and thermogravimetry analysis, etc.). The sensors’ electrical response was in line with the found structural and morphological features. The slope of the resistance variation with an RH percentage concentration between 1 kΩ and 1.5 kΩ was noted for all sensors (showing no changes with time) in the interval between 30 and 100% RH. A good repeatability and reproducibility of the evaluated sensors’ electrical response was observed: the ones that displayed a higher sensitivity were the ones with a high PVA binder content, higher than previously published results for PAA, as well as a very good time stability along the time and low hysteresis.

Fabrication and characterisation of a wound dressing composed of polyvinyl alcohol and quince seed mucilage.

Providing a suitable environment to improve the healing process is the main target of wound dressing that also protects the wound from additional harms. In the present study, fabrication and characterisation of a new kind of electrospun wound dressing composed of polyvinyl alcohol (PVA) and quince seed mucilage (QSM) is reported. QSM was extracted from quince seeds, purified, freeze-dried and used to produce aqueous solutions containing different amounts of PVA and QSM. The wound dressings were fabricated via the electrospinning method and their characteristics were investigated with scanning electron microscope (SEM) images, Fourier transform infrared (FTIR) spectra, tensile and swelling test, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cytotoxicity assay against fibroblast cells. SEM images confirmed that proper, uniform, non-oriented nanofibres with an average diameter in the range of 60-240nm, depending on the QSM content had been fabricated. The tensile test showed that with increasing QSM content, the tensile strength of fibre increased while elongation at break was decreased, which was consistent with SEM images where the diameter of samples decreased by increasing QSM content. MTT assay showed significant biocompatibility against fibroblast cells; however, it was increased by increased QSM proportion. In addition, SEM images supported the proper adhesion of fibroblast cells on the sample one day after culturing. Overall, the findings of the current study support the potential of PVA/QSM nanofibres as a proper candidate for biomedical applications, especially as a wound dressing.

A novel ternary mixed matrix membrane comprising polyvinyl alcohol (PVA)-modified poly (ether-block-amide)(Pebax®1657)/graphene oxide nanoparticles for CO2 separation

A novel ternary mixed matrix membrane (MMM) with different amounts of filler loading (2, 4 and 6 wt.%) was fabricated, in which the synthesized Graphene Oxide (GO) nanoparticles incorporated into a polyvinyl alcohol (PVA) modified poly (ether-block-amide) (Pebax®1657). PVA as an affordable additive provides a suitable affinity to separate CO2. Moreover, the presence of GO within the Pebax matrix causes an extra intermolecular space which enhances the CO2 permeability through the MMMs. In this study, pure Pebax membrane was modified via adding different amounts of PVA (0–20 wt. %). The results showed that the CO2 permeability increased from 79.42 barrer (for neat Pebax) to 81.24 barrer (for Pebax/PVA (10 wt.%)) and 90.7 barrer (for Pebax/PVA(15 wt.%)) and also the CO2/CH4 selectivity increased from 12.37 (for neat Pebax) to 16.41 (for Pebax/PVA (10 wt%). Furthermore, the CO2/N2 selectivity dramatically increased (from 36.93 for neat Pebax to 74.34 for Pebax/PVA(15 wt.%) at the pressure of 2 bar and temperature of 30 °C. The synthesized GO nanoparticles were incorporated (2, 4 and 6 wt. %) into the both Pebax/PVA(10 wt.%) and Pebax/PVA(15 wt.%) matrix to fabricate the Pebax/PVA/GO MMMs. The results showed that the Pebax/PVA (10 wt.%)/GO (6 wt.%) with the CO2 permeability of 236.48 barrer and CO2/CH4 selectivity of 33.63 and also Pebax/PVA(15 wt.%)/GO (6 wt.%) with CO2 permeability of 228.34 barrer and CO2/N2 selectivity of 124.09 implied the best performance among all the prepared membranes for CO2/CH4 and CO2/N2 separation, respectively. The Pebax/PVA/GO MMM indicates promising applications in CO2 separation processes.

Fabrication and properties of keratoses/polyvinyl alcohol blend films

Blend films of polyvinyl alcohol (PVA) and keratoses (KOx) were prepared using water as a common solvent. Aqueous solution of KOx from wool was extracted via oxidation using peracetic acid, and different amounts of PVA were added and blended to obtain films by solution casting method. Blend films were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry and tensile measurement. The scanning electron microscopy investigation showed that with decreasing PVA amount, film surface becomes rough and uneven. Thermal behavior and Fourier transform infrared analysis pointed that the two polymers have no covalent interaction each other. Also, it is to be noted that increasing the amount of PVA in the blend from 70 to 100% improved the tensile strength of blend films, and the elongation at break increases dramatically in films containing 70–100% of PVA. Moreover, blends containing 90 and 100% of KOx were too brittle for films production.

Recycling chicken feathers to produce adsorbent porous keratin-based sponge

Feathers are likely the most plentiful protein materials in the natural world. However, a significant amount of this resource has been wasted by burning or entombing. Recycling and developing a method for extracting keratin from such wastes have been the objective of many researches. In this research, keratin was extracted from chicken feather waste by enzymatic hydrolysis using an alkaline protease. The effects of three factors such as enzyme concentration, amount of reducing agent and hydrolysis time were evaluated to find the optimum enzymatic hydrolysis condition. Porous sponge of extracted keratin was then prepared by freeze-drying method. To improve the integrity of sponge structure, different amounts of polyvinyl alcohol were added to keratin solution and the obtained sponges were characterized. The physiochemical properties of the produced regenerated keratin sponge were evaluated by scanning electron microscopy, Fourier transform infrared spectrophotometer, Brunauer–Emmett–Teller surface area analyzer and oil absorption tests. The obtained results showed that the fabricated porous sponge has a high potential to be applied as a promising adsorbent.

Electrophoretic co-deposition of polyvinyl alcohol (PVA) reinforced alginate–Bioglass® composite coating on stainless steel: Mechanical properties and in-vitro bioactivity assessment

PVA reinforced alginate–bioactive glass (BG) composite coatings were produced on stainless steel by a single step electrophoretic deposition (EPD) process. The present paper discusses the co-deposition mechanism of the three components and presents a summary of the relevant properties of the composite coatings deposited from suspensions with different PVA concentrations. Homogeneous composite coatings with compact microstructure and increased thickness, i.e. as high as 10μm, were observed by scanning electron microscopy (SEM). The surface roughness of coatings with different PVA contents was slightly increased, while a significant increase of water contact angles due to PVA addition was detected and discussed. Improved adhesion strength of coatings containing different amounts of PVA was quantitatively and qualitatively confirmed by pull-off adhesion and cycled bending tests, respectively. In-vitro bioactivity tests were performed in simulated body fluid (SBF) for 0.5, 1, 2, 4, 7, and 14days, respectively. The decomposition rate of the coatings was reduced with PVA content, and rapid hydroxyapatite forming ability of the composite coatings in SBF was confirmed by FTIR and XRD analyses. According to the results of this study, composite alginate–Bioglass® bioactive coatings combined with PVA are proposed as promising candidates for dental and orthopedic applications.

Effect of viscosity of polyvinyl alcohol solution on morphology of the electrospun mullite nanofibres

Mullite nanofibres with diameters of 85–110nm were obtained by electrospinning of solutions containing different amounts of polyvinyl alcohol (PVA, as the template) ranging from 0wt% to 10wt%, which were added to the sol, and sintered at different temperatures. The sol was prepared by the sol–gel method, using aluminium isopropoxide (AIP), hydrated aluminium nitrate (AN) and tetraethylorthosilicate (TEOS) as the precursors. The details of crystal development, microstructure and thermal decomposition behaviour of the electrospun nanofibres were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and simultaneous thermal analysis (STA). The optimal content of 6wt% of PVA in the electrospinning polymeric solutions was found to be the suitable viscosity for the electrospinning and ultimately resulted in the formation of the most pure and uniform mullite nanofibres.

Eccentric Loading of Fluorogen with Aggregation‐Induced Emission in PLGA Matrix Increases Nanoparticle Fluorescence Quantum Yield for Targeted Cellular Imaging

A simple strategy is developed to prepare eccentrically or homogeneously loaded nanoparticles (NPs) using poly (DL-lactide-co-glycolide) (PLGA) as the encapsulation matrix in the presence of different amounts of polyvinyl alcohol (PVA) as the emulsifier. Using 2,3-bis(4-(phenyl(4-(1,2,2-triphenylvinyl)-phenyl)amino)-phenyl)-fumaronitrile (TPETPAFN), a fluorogen with aggregation-induced emission (AIE) characteristics, as an example, the eccentrically loaded PLGA NPs show increased fluorescence quantum yields (QYs) as compared to the homogeneously loaded ones. Field emission transmission electron microscopy and fluorescence lifetime measurements reveal that the higher QY of the eccentrically loaded NPs is due to the more compact aggregation of AIE fluorogens that restricts intramolecular rotations of phenyl rings, which is able to more effectively block the non-radiative decay pathways. The eccentrically loaded NPs show far red/near infrared emission with a high fluorescence QY of 34% in aqueous media. In addition, by using poly([lactide-co-glycolide]-b-folate [ethylene glycol]) (PLGA-PEG-folate) as the co-encapsulation matrix, the obtained NPs are born with surface folic acid groups, which are successfully applied for targeted cellular imaging with good photostability and low cytotoxicity. Moreover, the developed strategy is also demonstrated for inorganic-component eccentrically or homogeneously loaded PLGA NPs, which facilitates the synthesis of polymer NPs with controlled internal architectures.

Taste masked lipid pellets with enhanced release of hydrophobic active ingredient

Solid lipid extrusion is a suitable technique to produce oral dosage forms with improved taste properties. The design of a lipid formulation for poorly water soluble drugs is a challenge because of the poor dissolution and potential bioavailability problems. In this study, solid lipid extrusion at room temperature was applied for the formulation development of the BCS Class II drug NXP 1210. Powdered hard fat (Witocan® 42/44 mikrofein), glycerol distearate (Precirol® ato 5) and glycerol trimyristate (Dynasan® 114) were investigated as lipid binders. Different amounts of polyvinylalcohol (PVA)–polyethyleneglycol (PEG)-graft copolymer (Kollicoat® IR) and crospovidone (Polyplasdone® Xl-10) were scrutinized as solubilizers. The dissolution profiles depicted a short lag time (about 2min) and then fast and complete dissolution of NXP 1210 by increasing the amount of crospovidone. The initial release was more delayed with an increased amount of PVA–PEG-graft copolymer. Dissolution rate could also be influenced by changing the lipid binder from pure hard fat into a mixture of hard fat, glycerol distearate and glycerol trimyristate. The formulations are feasible for taste-masked granules or pellets containing poorly soluble drugs.

Influence of polyvinyl alcohol on the surface morphology, separation and anti-fouling performance of the composite polyamide nanofiltration membranes

Polyvinyl alcohol (PVA) was incorporated into composite nanofiltration membranes in situ by adding different amounts of PVA into piperazine (PIP) during its interfacial polymerization with trimesoyl chloride (TMC). Effect of PVA on membrane structures, nanofiltration performances and anti-fouling properties was studied by X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and cross-flow membrane module. It was found that the flux was increased without sacrificing rejection after adding PVA. XPS results show that the active layer contains PVA and polyamide components. AFM and SEM show that the roughness of these membranes decreases proportionally with increasing the mass fraction of PVA to PIP (the root mean square roughness value (RMS) decreases from 110.7 nm to 41.6 nm after adding 16% PVA). The hydrophilicity and flux of the composite NF membranes also increase with increasing the mass fraction of PVA to PIP. Moreover, the anti-fouling performance of composite polyamide NF membranes is improved with introducing the PVA into membranes. Therefore, PVA as an additive reagent has the potential to improve the nanofiltration performance of polyamide composite membranes.

Investigation of the Effect of Various Shellac Coating Compositions Containing Different Water-Soluble Polymers on In Vitro Drug Release

In this study drug pellets were coated with aqueous shellac coating formulations containing different amounts of polyvinyl alcohol (PVA), hydroxypropyl methylcellulose (HPMC), and carbomer 940. The coating level needed for enteric coating was determined. The influence of different amounts of PVA, HPMC, and carbomer on drug release and mechanism; the porosity, and the stability of shellac coatings was investigated. The results show that the incorporation of different concentrations of HPMC into shellac coatings, due to the increasing of pores, could considerably increase the drug release from the pellets in purified water. Moreover, the swelling effect of carbomer 940 leads to much more diffusivity through shellac coatings in water. In addition, PVA results in small cracking in the films and much more diffusion of drug in water. Furthermore, all coating systems containing different hydrophilic polymers that were used in the present work could prevent the dissolution of drug in simulated gastric juice for 2 hours. On the other hand, a rapid and complete release of drug within 45 minutes was observed in simulated intestinal fluid. Drug release from shellac coated pellets and ones containing different amounts of carbomer was affected between 3–6 months, whereas shellac coatings containing different amounts of PVA or HPMC show the same dissolution profiles with small deviation after 12 months.

Water–based synthesis of La0,5Sr0,5CoO3 (LSCO) electrodes for ferroelectric thin films

La0,5Sr0,5CoO3 (LSCO) thin films were prepared from water solutions of lanthanum nitrate La(NO3)3x6H2O, strontium nitrate Sr(NO3)2 and cobalt nitrate Co(NO3)2x6H2O with different amounts of polyvinylalcohol (PVA). Thin films were deposited on platinum coated and thermally oxidized silicon substrates. The influence of the amount of PVA on the thermal decomposition of LSCO precursors, the surface wetting and the microstructure of LSCO thin films were investigated. The effort was also focused on the optimization of the thermal treatment to obtain dense LSCO thin films.

Evaluation of Permeability and Mechanical Properties of Composite Polyvinyl Alcohol Films.

Among six grades of polyvinyl alcohol (PVA), PVA V (degree of hydrolysation 99.45%, molecular weight 140000-150000) and PVA VI (degree of hydrolysation 98-99%, molecular weight 85000-146000) were selected for combination with PVA I (degree of hydrolysation 99%, molecular weight 17300) to prepare composite films with different amounts of PVA I and film thickness. The permeability coefficients of diclofenac sodium through these films were determined and the elastic moduli measured. The permeability coefficients increased with the amount of PVA I in the PVA V-I films. Conversely, the presence of PVA I in the PVA VI-I films decreased the permeability of the composite films to diclofenac sodium. PVA VI-I films showed significantly higher permeability than PVA V-I films. These results indicated that PVA I content in the composite films was a critical factor, affecting the apparent solubility and/or swelling properties, and thereby permeability of the composite films. For PVA V-I films, the effect of PVA I on increasing solubility played a dominant role, but for PVA VI-I films, the effect of PVA I on decreasing swelling properties was a more important factor. Film thickness also influenced the permeability coefficients of diclofenac sodium through the composite films; film permeability decreasing with increasing film thickness. The addition of PVA I raised the elastic moduli of PVA VI-I film but showed minimal effect on PVA V-I films. Proper selection of PVA grades and weight ratio was the key element to successful preparation of PVA composite films with the desired characteristics.