Showing 7 results for Polyvinyl Alcohol
Volume 3, Issue 1 (5-2019)
Abstract
Research Subject: Removal of industrial wastewater especially from textile and dyeing factories is always important actions to control of pollutions. Using of polymeric adsorbents is an important method for removal of dyes from industrial wastewater. In this research work, designing and fabrication of PVA-based adsorbent with proper potential for removal of green malachite from industrial wastewater has been reported.
Research Approach: For fabrication of adsorbent 4 wt.% PVA was gelled in the present of 10 wt.% glutaraldehyde as cross-linker and punched. The punched hydrogels were porous with freeze drying method. For improving the adsorption ability, graphene and TiO2 were used. The adsorption of green malachite with prepare adsorbent was measured timely to determine the optimum percentage of nanoparticles. In addition, the effect of contact time and the presence of UV on the adsorption of pollution was investigated. Finally, the adsorption isotherms and thermodynamics study were investigated in different time.
Main Results: The results of adsorption of pollution with PVA/graphene adsorbent in different times showed that 0.5 wt.% is the optimum loading of graphene in the PVA matrix. This value was 3 wt.% for TiO2. The adsorption percentage via optimum adsorbent in dark condition showed that one minute after addition of adsorbent the adsorption percent increased to 75% indicating the high capability of the adsorbent in adsorption of tested pollution. The porous structure was confirmed via SEM image. By comparing the correlation coefficient for Langmuir and Freundlich isotherms it was found that Freundlich isotherm has better agreement with the findings of the current study. In other words, adsorption of green malachite with fabricated adsorbent was done multi layered. The thermodynamics studies showed that due to negative value of Gibbs energy the adsorption reaction of green malachite with fabricated absorbent is automatically.
Volume 4, Issue 2 (10-2020)
Abstract
Research Subject: One of the important methods in the treatment of skin wounds is the use of wound dressings. Recently, the use of polymer-based wound dressings has become increasingly common. The use of natural polymers is very important in wound dressings. The aim of the present study is to design and manufacture a polyvinyl alcohol/aloe vera wound dressing with the capability of healing skin wounds.
Research Approach: The electrospinning method was applied to prepare the samples. Aloe vera gel was first extracted, purified, and powdered by freeze-drying. In all samples, the amount of polyvinyl alcohol and aloe vera powder was fixed at 8 wt.%. This value was selected empirically based on the quality of the produced fibers. Different samples including different amounts of polyvinyl alcohol and aloe vera were produced and their properties including morphology, tensile strength, swelling, degradability, and antimicrobial properties were investigated.
Main Results: The results showed that the dropless random oriented fibers with uniform diameter were produced. The diameter increased with increasing aloe vera contribution, which was attributed to an increase in viscosity due to the presence of aloe vera. With increasing aloe vera contribution in the samples, tensile strength decreased and the elongation percentage increased. The swelling behavior of the specimens was evaluated by measuring the weight of the specimens in a simulated skin environment and the results showed that the presence of aloe vera increased the hydrophilic properties of the specimens. Antimicrobial activity of the samples against two gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa was investigated using the disk diffusion method and it was found that the presence of Aloe vera in the samples brought antimicrobial activity against Pseudomonas aeruginosa. Finally, the findings of this study confirm the feasibility of using polyvinyl alcohol /aloe vera for the production of the electrospun wound dressing.
A.r. Khoshkbar Sadeghi, M. Farbodi ,
Volume 9, Issue 4 (12-2018)
Abstract
Aims: The simultaneous use of insulating polymers and nanostructures such as silver to produce triangular nanocomposites, with the reinforcement of effect of each other, can have better results in improving the mechanical properties and processability of polyaniline. The current study was conducted with the aim of preparation of Polyaniline/Polyvinyl Alcohol/Ag nanocomposite and characterization of its physicochemical and antibacterial properties.
Materials and Methods: In the present experimental research, polyaniline (PANI) was used as a conducting polymer, polyvinyl alcohol (PVA) was used as a biopolymer because of its biodegradable property. Ag nanoparticles also was considered as a reinforcing agent of thermal stability, mechanical and antibacterial property to prepare PANI-PVA-Ag nanocomposite.
The synthesis of PANI-PVA composite and PANI-PVA-Ag nanocomposite was performed through polyaniline and Ag addition in PVA solution. Different weight percent of components and Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), and scanning electron microscope connected to the X-ray Diffraction System (EDX) were used to investigate the properties.
Findings: Thermal stability of the nanocomposite in comparison with pure PVA in temperatures above 400ᵒC was promoted. The presence of PANI, PVA, and Ag in the FTIR spectroscopy showed the compatibility of the nanocomposite components. The greatest tensile strength belonged to PANI/PVA/Ag nanocomposites with 88%, 9%, and 3%w/w.
Conclusion: The components of Polyaniline/Polyvinyl Alcohol/Ag are compatible. The presence of PANI and Ag nanoparticles in the structure of the nanocomposite improves its thermal stability than pure PVA at high temperatures. Polyaniline/Polyvinyl Alcohol/Ag canocomposite has inhibitory effect on gram-positive and gram-negative pathogenic bacteria. Reducing the weight percent of PVA or increasing the weight percent of PANI decrease the tensile strength.
M. Farbodi, A.r. Khoshkbar Sadeghi ,
Volume 9, Issue 4 (12-2018)
Abstract
Aims: In medicine, nanofiber can be used in wound dressing. The aim of this study was to prepare carboxymethyl cellulose/calcium alginate/polyvinyl alcohol/silver (CMC/Alg/PVA/Ag) nanocomposite by electrospinning method and to investigate its performance as wound dressing.
Materials and Methods: In the present experimental study, CMC biofilm was prepared by solution method. Then, calcium alginate/polyvinyl alcohol/silver (Alg/PVA/Ag) nanofiber was prepared by electrospining method in the optimal conditions and deposited on CMC film. Finally, the possibleof application of the product as wound dressing and its antibacterial and morphological properties, as well as permeability to water vapor were investigated.
Findings: CMC/Alg/PVA/Ag film had more permeability in comparison to Alg/PVA/Ag nanofibers and less water vapor permeability value in comparison to CMC film. The most sensivity belonged to Escherichia coli and Klebsiella pneumoniae gram-negative bacteria with inhibition zone diameter of 23mm and 24mm, respectively, and Staphylococcus aureus and Staphylococcus saprophyticus gram-positive bacteria with inhibition zone diameter of 21mm and 17mm, respectively, for CMC/Alg/PVA/Ag film. Also, the wound with CMC/Alg/PVA/Ag dressing significantly showed more healing speed in comparison to CMC dressings and CMC/Ag.
Conclusion: The use of CMC/Alg/PVA/Ag nanocomposite as wound dressing is possible. This dressing, with pores, allows the vapors to flow through the wound secretions, is impermeable to liquids and bacteria, but is permeable to oxygen and vapor; it is not allergenic and does not cause toxicity and chemical stimulation, transparent dressing and the possibility of seeing the wound is easily possible, it provides the moisture level needed for wound healing, it does not stick to the wound and as a result, its replacement is without pain and cheap.
Volume 15, Issue 4 (7-2013)
Abstract
In production of tissue paper, the adhesion of a liquid adhesive creping aid, compound polymer, as creping aids on the Yankee dryer surface was investigated. A compound polymer was prepared based on mixing ratio of poly (amideamine)-epichlorohydrin resin (PAE) as an adhesive agent, polyvinyl alcohol (PVA) as a modifier agent, and cationic fatty acid (CFA) and ethylene glycol (EG) as release agents. In order to simulate the Yankee dryer cylinder, the adherence of paper to the substrate that was coated by the compound polymer solution was measured using a peel strength test. Results indicated that increasing the percent of total solid content of compound polymer would increase peel strength of paper. Peel strength of paper increases if EG as a release agent is used. The amount of PVA/PAE resin in the formulation of creping aid was critical for building a flexible and tough coating layer on to the substrate and to provide adequate adhesion of paper in peel strength test.
Volume 16, Issue 96 (1-2020)
Abstract
Chitosan is a natural polymer that is typically extracted from the marine crustacean chitin shell and capable of film forming. Polyvinyl alcohol is a synthetic and biodegradable polymer that can be used in combination with natural polymers to improve structural properties. Chitosan nanoparticles were produced by ion gelation method and the nanoparticles with an average size of 69.92 nm and a zeta potential of + 30.3 mV were used for application in the composite films. After mixing different ratios of polyvinyl alcohol (P) with chitosan (C) (1: 3, 1: 1 and 3: 1), the resulting solutions with different ratios of nanoparticles (np) (0, 2, 4, 6) ml of chitosan gel In 100 ml of film forming solutions were mixed and glycerol was added to 25% w / w dry film powder and then poured into mold and dried in oven at 40 ° C. The results showed that increasing the ratio of polyvinyl alcohol and application of nanoparticles in polymer structure improved the physico-mechanical properties of the films. Fourier transform infrared spectroscopy results showed that some interactions have taken place between the polymer network and the nanoparticles. Thermogravimetric analysis results showed that the addition of nanoparticles slightly increased thermal stability of the polymers compared control samples without nanoparticles. Release results in the high-fat and low-fat food simulant showed that the release rate decreased with increasing polyvinyl alcohol ratio. Also, increasing the nanoparticle to np4 ratio decreased the release rate. The aim of this study was to determine the optimum ratio of two polymers and the amount of chitosan nanoparticles containing natural antioxidant catechin for use in food packaging.
Volume 21, Issue 153 (9-2024)
Abstract
Eggs are one of the low-cost sources of protein and are also perishable, so maintaining their internal quality during storage is particularly important. The current research was carried out with the aim of the effect of nanocomposite coating on the physicochemical changes of eggs during storage for 4 weeks. Uncoated eggs (control) and eggs treated with a two-component coating of polyvinyl alcohol/chitosan (PC), a three-component film of polyvinyl alcohol/chitosan/montmorillonite (PCM) ), and PCM films incorporating concentrations of 2 and 4% garlic extract were evaluated in a total of 5 treatments and 3 replicates in a completely randomized design. The results showed that the concentration-dependent antimicrobial effect of garlic extract was higher against Staphylococcus aureus than Escherichia coli. The prepared films of active three-component PCM nanocomposite had greater thickness, higher tensile strength, and elasticity, lower solubility, less elongation at break, and lower water vapor permeability (p<0.05). At the end of 4 weeks of storage, the eggs coated with active three-component PCM nanocomposites had a thicker shell (0.400 mm) and a stronger shell (0.310 kg), causing less weight loss (About 4 %), Haugh unit (70.00) and yolk index (0.43) were higher and the lowest of total viable count bacteria (4.1 log cfu/ml). Therefore, using the three-component PCM nano-coating containing 4% garlic extract as a biodegradable packaging is possible to maintain the internal quality and eggshell and increase its storage time at ambient temperature.
