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Fujino, Shigeru, i Hiroshi Ikeda. "Room Temperature Imprint Using Crack-Free Monolithic SiO2-PVA Nanocomposite for Fabricating Microhole Array on Silica Glass". Journal of Nanomaterials 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/584320.
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This paper aims to fabricate microhole arrays onto a silica glass via a room temperature imprint and subsequent sintering by using a monolithic SiO2-poly(vinyl alcohol) (PVA) nanocomposite as the silica glass precursor. The SiO2-PVA suspension was prepared from fumed silica particles and PVA, followed by drying to obtain tailored SiO2-PVA nanocomposites. The dependence of particle size of the fumed silica particles on pore size of the nanocomposite was examined. Nanocomposites prepared from 7 nm silica particles possessed suitable mesopores, whereas the corresponding nanocomposites prepared from 30 nm silica particles hardly possessed mesopores. The pore size of the nanocomposites increased as a function of decreasing pH of the SiO2-PVA suspension. As a consequence, the crack-free monolithic SiO2-PVA nanocomposite was obtained using 7 nm silica particles via the suspension at pH 3. Micropatterns were imprinted on the monolithic SiO2-PVA nanocomposite at room temperature. The imprinted nanocomposite was sintered to a transparent silica glass at 1200°C in air. The fabricated sintered glass possessed the microhole array on their surface with aspect ratios identical to the mold.
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Purwandari, Vivi, i Malemta Tarigan. "PREPARASI FILM NANOKOMPOSIT POLIVINIL ALKOHOL (PVA)/NANOKARBON DARI CANGKANG BUAH SAWIT (NCCS) DENGAN METODE PENCAMPURAN LARUTAN". JURNAL KIMIA SAINTEK DAN PENDIDIKAN 6, nr 1 (24.07.2022): 11–16. http://dx.doi.org/10.51544/kimia.v6i1.2977.
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Polyvinyl alcohol (PVA) has good compatibility when added as filler in the form of nanocarbon so that it can produce environmentally friendly nanocomposite products. Thus, the addition of nanocomposites to PVA-based films is expected to increase and improve the mechanical properties of the resulting PVA films. This study aims to utilize palm fruit shells as raw materials for nanocarbons and as fillers for nanocomposites, as well as to determine the mechanical properties and thermal strength of nanocarbon nanofibers in the PVA matrix. Composite films were made using the solution mixing method. The research was conducted by mixing PVA solution (3.5 g) with various concentrations of nanocarbon from palm fruit shells (NCCS) and 2 ml of glycerol and 1 g of PEG 400. Film characterization includes tensile test, scanning differential calorimetry (DSC), and conductivity test. Tensile test of PVA/NCCS nanocomposite resulted in tensile strength of 0.314 MPa and an elongation of 4.21925 %. The thermal test of PVA/NCCS nanocomposite with DSC yielded a melting point of around 146.06oC. Electrical conductivity of PVA/NCCS 107.1 (1.07 x 10-3) s/cm. PVA/NCCS nanocomposite based on conductivity scale including a semiconductor material.
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Bandyopadhyay, Abhijit, Mousumi De Sarkar i Anil K. Bhowmick. "Solution Rheology of Poly(vinyl alcohol)/Silica Hybrid Nanocomposites". Polymers and Polymer Composites 13, nr 5 (lipiec 2005): 429–42. http://dx.doi.org/10.1177/096739110501300501.
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The solution behavior of polymer/silica hybrid nanocomposites was investigated using a Brookfield viscometer. The nanocomposites were prepared using the sol-gel technique with tetraethoxysilane (TEOS) as the precursor for silica. The sol-gel reaction was carried out in the pH range of 1.0-2.0, which was maintained by the addition of concentrated HCl. Poly (vinyl alcohol) (PVA)/silica nanocomposites demonstrated a bigger rise in solution viscosity after continuous measurement for five days than either- acrylic rubber (ACM)/silica or epoxidised natural rubber (ENR)/silica nanocomposites. Detailed investigation of the PVA/silica system indicated that it exhibited Newtonian behaviour when the solutions contained (5 or 7.5 wt% of PVA,) even when increasing the TEOS concentration to 50 wt%, although at one particular TEOS concentration (10 wt%), the nanocomposite was pseudoplastic when the concentration of PVA was increased to 10 wt%. The reinforcement factor [Formula: see text] for those PVA/silica hybrid nanocomposites containing 5 wt% of PVA deviated strongly from the Guth-Smallwood prediction. Instead they obeyed a relationship of the type ηmax = η0(1 + aϕb), where a = 4.45 and b = 0.38, calculated for this system. The viscosity decreased with increasing temperature for both PVA and the representative nanocomposite with 30 wt% TEOS (PVA30), although the activation energy for flow of the nanocomposite did not vary to a great extent.
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Wang, Mengqing, Yanling Xu, Haihu Tan, Lijian Xu, Changfan Zhang i Jianxiong Xu. "Multicolor Luminescent Anti-Counterfeiting Barcode Based on Transparent Lanthanide-Doped NaYF4/Poly(Vinyl Alcohol) Nanocomposite with Tunable Full-Color Upconversion Emission". Nanoscience and Nanotechnology Letters 10, nr 3 (1.03.2018): 365–72. http://dx.doi.org/10.1166/nnl.2018.2631.
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In this paper, we report the synthesis of transparent lanthanide-doped NaYF4 phosphors/poly(vinyl alcohol) (UCPs/PVA) nanocomposites with full-color upconversion emission for construction of multicolor luminescent anti-counterfeiting barcode. By deliberate design of water-dispersible lanthanidedoped NaYF4 upconversion phosphors and precise control of the doped lanthanide ions (dopant pairs and molar ratio), three-primary RGB UCPs with fine red, green and blue upconversion emission were synthesized. The as-prepared three-primary RGB UCPs were incorporated into poly(vinyl alcohol) (PVA) matrix at a fixed concentration to balance the transparence and fluorescence intensity of the UCPs/PVA nanocomposite. The combination of emissions from different types of UCPs with selected ratios in PVA matrix was used to prepare UCPs/PVA nanocomposite with various upconversion emissions. It was demonstrated that the separation distance between UCPs was large enough to suppress inter-particle energy transfer, and thus the emissions of each UCPs were well preserved. This facilitated the fabrication of UCPs/PVA nanocomposite with tunable full-color upconversion emission based on the trichromatic additive color theory. The relevance of these multicolor UCPs/PVA nanocomposites to barcode materials and application in anti-counterfeiting field were also confirmed.
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Wu, Ming-Chung, Shun-Hsiang Chan i Ting-Han Lin. "Fabrication and photocatalytic performance of electrospun PVA/silk/TiO2 nanocomposite textile". Functional Materials Letters 08, nr 03 (czerwiec 2015): 1540013. http://dx.doi.org/10.1142/s1793604715400135.
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Many organic/inorganic nanocomposites have been fabricated into fibrous materials using electrospinning techniques, because electrospinning processes have many attractive advantages and the ability to produce relatively large-scale continuous films. In this study, the polyvinyl alcohol (PVA)/silk/titanium dioxide ( TiO 2) nanocomposite self-cleaning textiles were successfully produced using electrospinning technique. After optimizing electrospinning conditions, we successfully obtained the PVA/silk/ TiO 2 nanocomposite fibers with average diameter of ∼220 nm and TiO 2 concentration can be as high as 18.0 wt.%. For the case of the PVA/silk/ TiO 2 nanocomposite textile, the color of brilliant green coated on the textile surface changed from the initial green color to colorless after ultraviolet (UV) irradiation. Because of its worthy photocatalytic performance, the developed PVA/silk/ TiO 2 nanocomposite materials in this study will be beneficial for the design and fabrication of multifunctional fibers and textiles.
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Mohaimeed, Ameen alwan. "The Study the Influence of TiO2-Nanoparticles Doped in Polyvinyl Alcohol by Measuring Optical Properties of PVA Films". Iraqi Journal of Nanotechnology, nr 3 (14.10.2022): 59–70. http://dx.doi.org/10.47758/ijn.vi3.62.
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It was investigated how titanium dioxide nanoparticles affected the optical properties of polyvinyl alcohol. Polymer nanocomposites (PVA-TiO2) are created via stirring and casting. The results demonstrate that transmittance improves from 75% to 95% while titanium dioxide concentration enhances the absorbance of nanocomposites. Nanocomposite films made of PVA and TiO2 had reflectance values of 12 and 16 percent (weight percent=0.15 and 0.85%).The refractive index and coefficient of extinction rise with increasing density, and optical absorption and photon dispersion in the nanocomposite (PVA-TiO2) also rise as the concentration of titanium dioxide nanoparticles rises. Real dielectric (r) and imaginary dielectric I constants also rise as titanium dioxide nanoparticle concentration does. The results show that when the weight % of (TiO2) nanoparticles increased, the energy gap decreased from 3.32 to 2.23. Additionally, optical conductivity increased with the concentration of (TiO2) NPs. Nanocomposites of PVA and TiO2 are essential for optical applications.
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Yilmaz Dogan, Hazal, Yasin Altin i Ayşe Çelik Bedeloğlu. "Fabrication and properties of graphene oxide and reduced graphene oxide reinforced Poly(Vinyl alcohol) nanocomposite films for packaging applications". Polymers and Polymer Composites 30 (styczeń 2022): 096739112211133. http://dx.doi.org/10.1177/09673911221113328.
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Petroleum-based polymers have a wide range of uses in the packaging industry, including films, food packaging, rigid containers, foamed containers, medical products, etc. This study focuses on improving the properties of polyvinyl alcohol (PVA) based material systems, one of the most popular water-soluble biopolymers, to reduce the waste of petroleum-based plastics, which are widely used. Polyvinyl alcohol (PVA) nanocomposite films containing low concentrations (0.05–1%) of graphene oxide (GO) and reduced graphene oxide (rGO) were produced via the solution casting method. When electrical properties of nanocomposite films were evaluated, the addition of 1 wt% GO and rGO resulted in a 36% and 45% decrease in the volumetric resistance of the films as well as a decrease in surface resistance of 24.5% and 34.9%, respectively. The maximum tensile strength of 1% GO and rGO-reinforced PVA nanocomposites was found to be ∼59 MPa and ∼68 MPa with an increase of 20% and 38% compared to neat PVA films, respectively. The average Young’s modulus of 1% GO and rGO-reinforced PVA nanocomposites also increased from 2561 MPa to 3515 MPa and 4219 MPa with an increase of 37% and 65%, respectively. As a result, the electrical conductivity, Young’s modulus, maximum tensile strength, thermal properties, and optical absorption of nanocomposite films increased by adding GO and rGO to PVA. The results show that the produced nanocomposite film may be a promising material for packaging applications.
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Cobos, Mónica, M. Fernández i M. Fernández. "Graphene Based Poly(Vinyl Alcohol) Nanocomposites Prepared by In Situ Green Reduction of Graphene Oxide by Ascorbic Acid: Influence of Graphene Content and Glycerol Plasticizer on Properties". Nanomaterials 8, nr 12 (6.12.2018): 1013. http://dx.doi.org/10.3390/nano8121013.
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The enhanced properties of polymer nanocomposites as compared with pure polymers are only achieved in the presence of well-dispersed nanofillers and strong interfacial adhesion. In this study, we report the preparation of nanocomposite films based on poly(vinyl alcohol) (PVA) filled with well dispersed graphene sheets (GS) by in situ reduction of graphene oxide (GO) dispersed in PVA solution using ascorbic acid (L-AA) as environmentally friendly reductant. The combined effect of GS content and glycerol as plasticizer on the structure, thermal, mechanical, water absorption, and water barrier properties of PVA/GS nanocomposite films is studied for the first time. Higher glass transition temperature, lower crystallinity, melting, and crystallization temperature, higher mechanical properties, and remarkable improvement in the thermal stability compared to neat PVA are obtained as a result of strong interfacial interactions between GS and PVA by hydrogen bonding. PVA/GS composite film prepared by ex situ process is more brittle than its in situ prepared counterpart. The presence of GS improves the water barrier and water resistance properties of nanocomposite films by decreasing water vapor permeability and water absorption of PVA. This work demonstrates that the tailoring of PVA/GS nanocomposite properties is enabled by controlling GS and glycerol content. The new developed materials, particularly those containing plasticizer, could be potential carriers for transdermal drug delivery.
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Noshirvani, Nooshin, Babak Ghanbarzadeh, Hadi Fasihi i Hadi Almasi. "Starch–PVA Nanocomposite Film Incorporated with Cellulose Nanocrystals and MMT: A Comparative Study". International Journal of Food Engineering 12, nr 1 (1.02.2016): 37–48. http://dx.doi.org/10.1515/ijfe-2015-0145.
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Abstract The goal of this work was to compare the barrier, mechanical, and thermal properties of two types of starch–polyvinyl alcohol (PVA) nanocomposites. Sodium montmorillonite (MMT) and nanocrystalline cellulose were chosen as nanoreinforcements. X-ray diffraction (XRD) test showed well-distributed MMT in the starch–PVA matrix, possibly implying that the clay nanolayers formed an exfoliated structure. The moisture sorption, solubility and water vapor permeability (WVP) studies revealed that the addition of MMT and nanocrystalline cellulose reduced the moisture affinity of starch–PVA biocomposite. At the level of 7 % MMT, the nanocomposite films showed the highest ultimate tensile strength (UTS) (4.93 MPa) and the lowest strain to break (SB) (57.65 %). The differential scanning calorimetry (DSC) results showed an improvement in thermal properties for the starch–PVA–MMT nanocomposites, but not for the starch–PVA–NCC nanocomposites. Results of this study demonstrated that the use of MMT in the fabrication of starch–PVA nanocomposites is more favorable than that of nanocrystalline cellulose to produce a desirable biodegradable film for food packaging applications.
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Cho, Beom-Gon, Shalik Ram Joshi, Seongjin Lee, Shin-Kwan Kim, Young-Bin Park i Gun-Ho Kim. "Enhanced Mechanical and Antibacterial Properties of Nanocomposites Based on Poly(vinyl Alcohol) and Biopolymer-Derived Reduced Graphene Oxide". Polymers 13, nr 4 (18.02.2021): 615. http://dx.doi.org/10.3390/polym13040615.
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Functionalized graphene–polymer nanocomposites have gained significant attention for their enhanced mechanical, thermal, and antibacterial properties, but the requirement of multi-step processes or hazardous reducing agents to functionalize graphene limits their current applications. Here, we present a single-step synthesis of thermally reduced graphene oxide (TrGO) based on shellac, which is a low-cost biopolymer that can be employed to produce poly(vinyl alcohol) (PVA)/TrGO nanocomposites (PVA–TrGO). The concentration of TrGO varied from 0.1 to 2.0 wt.%, and the critical concentration of homogeneous TrGO dispersion was observed to be 1.5 wt.%, below which strong interfacial molecular interactions between the TrGO and the PVA matrix resulted in improved thermal and mechanical properties. At 1.5 wt.% filler loading, the tensile strength and modulus of the PVA–TrGO nanocomposite were increased by 98.7% and 97.4%, respectively, while the storage modulus was increased by 69%. Furthermore, the nanocomposite was 96% more effective in preventing bacterial colonization relative to the neat PVA matrix. The present findings indicate that TrGO can be considered a promising material for potential applications in biomedical devices.
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He, Shaojian, Jiaqi Wang, Mengxia Yu, Yang Xue, Jianbin Hu i Jun Lin. "Structure and Mechanical Performance of Poly(vinyl Alcohol) Nanocomposite by Incorporating Graphitic Carbon Nitride Nanosheets". Polymers 11, nr 4 (3.04.2019): 610. http://dx.doi.org/10.3390/polym11040610.
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Owing to the high aspect ratio, the two-dimensional (2D) inorganic nanofillers have attracted extensive interest in the field of polymer reinforcement. In this work, graphitic carbon nitride (g-C3N4) nanosheets were obtained via thermal condensation of melamine and were then ultrasonically exfoliated in water, which was confirmed by atomic force microscopy (AFM) and TEM. Poly(vinyl alcohol) (PVA)/g-C3N4 nanocomposites were achieved by solution casting using water as the solvent. The structure and mechanical performance of PVA/g-C3N4 nanocomposites were studied. It was found that the g-C3N4 nanosheets were well dispersed in the PVA matrix. The introduction of g-C3N4 nanosheets increased the glass transition temperature and crystallinity of the nanocomposites, leading to the improved mechanical performance. Compared with the pure PVA, the PVA/g-C3N4 nanocomposite with 0.50 wt% g-C3N4 nanosheets showed ~70.7% enhancement in tensile strength, up from 51.2 MPa to 87.4 MPa.
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Shahin, Naglaa, i Reham Kamal Abd El Hamid. "Spectroscopy and Conductivity Studies of Polyvinyl Alcohol (PVA)/Polypyrrol (Ppy) Nanocomposite with Various Chloride Metals to Improved Properties of the Polymers". JOURNAL OF ADVANCES IN PHYSICS 16, nr 1 (8.04.2019): 55–63. http://dx.doi.org/10.24297/jap.v16i1.8192.
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Polyvinyl alcohol- polypyrrole (PVA-PPy) nanocomposites with metal chlorides (FeCl3, NiCl2, CuCl2 and ZnCl2) have been synthesized by chemical oxidative polymerization method. These synthesized nanocomposites are characterized by using FTIR, X-ray diffraction, Transition electron microscope (TEM) and Conductivity measurement. TEM exhibit that all of the composites have uniform sizes and morphologies. The diameter of PVA/PPy nanocompsite is 58nm when the metals added to the PVA/PPy the diameters becomes smaller. The variation of electrical conductivity (log ?) with 1000/T for PVA/PPy nanocomposite with metal chlorides revealed that the increase in conductivity s at temperature (393K) with added metals can be attributed to the creation of induced charge carriers in PVA/PPy matrix
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Yudhanto, Ferriawan, Jamasri i Heru Santoso Budi Rochardjo. "Physical and Mechanical Characterization of Polyvinyl Alcohol Nanocomposite Made from Cellulose Nanofibers". Materials Science Forum 988 (kwiecień 2020): 65–72. http://dx.doi.org/10.4028/www.scientific.net/msf.988.65.
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A method using a combination of acid hydrolysis and ultrasonic homogenize were developed to obtain the CNF (cellulose nanofibers) from agave cantala fibers. Acid hydrolysis method able to produce the CNF with a diameter around of 45-50 nm, which can investigated by transmission electron microscopy (TEM). The homogenize mixing method between CNF 5 wt% colloidal and 3 wt% PVA (polyvinyl alcohol) with magnetic stirrer 350 RPM, at temperature of 50 °C, for 30 minutes followed by ultrasonic homogenizer has been causing CNF well distributed in the PVA matrix. PVA/CNF nanocomposites film was prepared by solution casting technique. Physical properties test by x-ray diffraction (XRD) and fourier transform infrared (FTIR) shows highly crystalline of CNF which indicates improvements the mechanical properties of PVA/CNF nanocomposite film. The tensile stress and elongation at break of PVA/CNF nanocomposite film were increased by 55 % and 137 %.
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DURMAZ, EKREM, i SAIM ATES. "EFFECT OF NANOCELLULOSE TYPE AND MATRIX MATERIAL ON PRODUCTION OF NANOCOMPOSITE FILMS". Cellulose Chemistry and Technology 57, nr 5-6 (20.07.2023): 625–35. http://dx.doi.org/10.35812/cellulosechemtechnol.2023.57.57.
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The objective of this study has been to investigate the chemical structure, thermal and mechanical properties of nanocomposite films, which were produced by combining cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) with different ratios of boric acid (BA) and polyvinyl alcohol (PVA) as a matrix. Nanocomposites reinforced with BA had B–O–B, and B–O–C ether bonds, while the addition of PVA did not influence the chemical bonds of the films. Furthermore, the addition of BA to CNF and CNC films enhanced the thermal resistance of the films at high temperatures, but the addition of PVA declined the thermal properties of these films. Considering the mechanical properties of nanocomposite films, it was determined that adding PVA to CNF and CNC films had a positive impact, unlike BA. Consequently, it was concluded that each BA and PVA have their advantages and can be preferred for specific industrial applications.
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Pattanasiri, Busara, i Suntree Sangjan. "ZnO/g-C<sub>3</sub>N<sub>4</sub>/Fe<sub>3</sub>O<sub>4</sub> Nanocomposites Embedded Sa-PVA as Photocatalyst Hydrogel Beads for Photodegradation". Key Engineering Materials 931 (9.09.2022): 99–107. http://dx.doi.org/10.4028/p-b2812s.
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In this research, Fe3O4 NPs and g-C3N4 nanosheets were synthesized by co-precipitation and the thermal decomposition method, respectively. The ZnO/g-C3N4/Fe3O4 nanocomposites (ZGF) with the varying weight sight of Fe3O4 NPs were 0.5 (0.5ZGF), 1.25 (1.25ZGF), 2.5 (2.5ZGF), and 5.0 (5.0ZGF) wt%, which were synthesized by a facile method. Synthesized Fe3O4 NPs, g-C3N4 nanosheets, and ZGF nanocomposite were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM). Then ZGF nanocomposites were contained on sodium alginate-polyvinyl alcohol (SA-PVA) as hydrogel packing material. Kinetics of photocatalytic activity and adsorption were studied by first-order reaction, second-order reaction, the pseudo-first-order, the pseudo-second-order, Elovich, and Avrami models. Especially, the photocatalytic activity and adsorption process of ZGF-SA-PVA composite hydrogel beads have been represented via Methylene Blue removal. The photodegradation efficiency of 2.5ZGF-SA-PVA composite hydrogel beads under visible light irradiation is increased by over 2 times, to be much higher than that of SA-PVA hydrogel beads. The results show that the organic removal efficiency of the SA-PVA hydrogel bead can be effectively improved by the ZGF nanocomposite.
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Nasar, Gulfam, Hazrat Amin, Fawad Ahmad i Shahbaz Nazir. "Structural and Thermal Behavior Evaluation of Ag-PVA Nanocomposites Synthesized via Chemical Reduction Technique". Journal of Materials and Physical Sciences 1, nr 1 (30.06.2020): 19–25. http://dx.doi.org/10.52131/jmps.2020.0101.0003.
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Silver nanoparticles were prepared via process of chemical reduction using sodium borohydride as reductant. The prepared nanoparticles were then utilized for synthesizing various compositions of nanocomposites with polymeric matrix of poly (vinyl alcohol). For doing so, the nanoparticles were dispersed in the polymer solution by vigorous stirring. The solutions of the nanocomposites were cast in films. The nanocomposite films were used for various characterization techniques; out of which three are being reported in this communication; XRD, TGA/DTA and SEM. The upshot of XRD proposes a semi-crystalline nature of synthesized nanocomposite. The crystalline character of the nanocomposite enhances with an increasing doping concentration of the prepared nanoparticles. Thermal analysis suggests the degradation pattern of the polymer nanocomposite material and represents that thermal stability improves as the silver nanoparticles are added. The SEM micrograph reveals a uniform surface with a well dispersed nanoparticle in the polymer matrix.
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Radoicic, Marija, Zoran Saponjic, Milena Marinovic-Cincovic, Scott Ahrenkiel, Natasa Bibic i Jovan Nedeljkovic. "The influence of shaped TiO2 nanofillers on thermal properties of polyvinyl alcohol". Journal of the Serbian Chemical Society 77, nr 5 (2012): 699–714. http://dx.doi.org/10.2298/jsc110331161r.
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PVA-based nanocomposites consisting of shaped TiO2 nanocrystals (nanoparticles, nanotubes or nanorods) were synthesized by direct blending of polymer and titania nanocrystals solution or powder. In order to elucidate the influence of shape of titania nanocrystals on thermal stability of polymer matrix and particles interaction with PVA chain, structural and thermal characterizations of PVA/TiO2 nanocomposites were performed. Faceted nanoparticles increased the thermal stability of PVA matrix. Titania nanotubes and nanorods did not show any stabilizing effect on polymer matrix in argon atmosphere. The thermo-oxidative degradation temperature of PVA increased with addition of faceted TiO2 nanoparticles. The thermo-oxidative stability of the PVA matrix was affected more by the presence of titania nanotubes and nanorods in comparison with its thermal stability in inert atmosphere. The crystallinity degree (Xc=32 %) of PVA matrix slightly decreased in the presence of faceted TiO2 nanoparticles in nanocomposite sample.
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Nain, Aditi, Sanjay Dahiya, Rishi Pal Chahal i Ekta Dhanda. "Ultraviolet (UV) irradiated induced changes in optical properties of PVA/Ag nanocomposite films". Physica Scripta 97, nr 4 (24.03.2022): 045817. http://dx.doi.org/10.1088/1402-4896/ac5ce2.
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Abstract PVA/Ag nanocomposite with different concentrations of silver nanoparticles (Ag NPs) was successfully synthesized by the solution casting method. The effect of concentration of Ag NPs and ultraviolet (UV) irradiation on optical and structural properties of PVA/Ag nanocomposites were investigated by UV-Vis spectrophotometer and Fourier transform infrared spectroscopy. The presence of an absorption peak at around 410 nm recorded by UV-Vis spectrophotometer shows silver nanoparticles are formed. The absorption spectra for prepared nanocomposites recorded over the wavelength range of 200–700 nm shows the intensity of absorption band increases with an increase in the concentration of Ag NPs and with the increase in time of ultraviolet (UV) irradiation. Decreases in the broadness of transmission band with an increment in enfeeblement transmission intensity by UV exposure make its use suitable as a bandpass filter. Decrease in the value of the optical band gap from 4.91 eV for pure PVA to 4.32 eV for PVA doped 0.04M Ag was observed which continuously reduces further with an increase in the concentration of Ag NPs (3.67 eV for PVA doped 0.08M Ag). Additionally, as the time for UV exposure increases the value of the optical band gap decreases from 4.32 eV without UV exposure to 3.81 eV and 3.43 eV for UV exposure of 120 min and 240 min respectively for PVA doped 0.04M Ag. This reduction in values of the optical band gap corresponds to the formation of charge formation complexes inside the PVA matrix. Various optical parameters such as refractive index, single oscillator energy, lattice dielectric constant, the strength of interband optical transition, average oscillator strength, etc are calculated for nanocomposite with different concentrations of Ag NPs before and after UV exposure for different times. The refractive index values were observed to increase from 1.69 for pure PVA to 1.85 without UV exposure, which further increases to 2.30 for UV exposure of 240 min for PVA doped 0.08M Ag. FTIR spectra show the interaction between PVA and Ag NPs and show changes caused in the structure of nanocomposite as the time of UV exposure increases.
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PANDA, BHABANI SHANKAR, i MOHAMMED ANSAR AHEMAD. "Synthesis of Silver Nanoparticles from Mimusops elengi Extract of Raw Fruits and Characterization of PVA-Silver Polymer Nanocomposite Films". Asian Journal of Chemistry 33, nr 4 (20.03.2021): 762–66. http://dx.doi.org/10.14233/ajchem.2021.23074.
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The present work concerns on the synthesis of silver nanoparticles at 25 ºC using raw fruits extract of Bakul (Mimusops elengi) tree via chemical reduction route development of poly(vinyl alcohol) PVA-silver polymer nanocomposite films. The nanocomposite films were subjected to characterization by UV-visible, FTIR, X-ray diffraction, field emission scanning electron microscope (FESEM) and thermal studies. The UV-visible spectrum shows a characteristic broad absorption band observed near 465 nm suggesting presence of silver nanoparticles in polymer nanocomposites (PNCs) film. The vibrational band shift of –OH group of poly(vinyl alcohol) in the presence of nanoparticle designated the chemical interaction between –OH group of poly(vinyl alcohol) and silver nanoparticles. The FESEM study confirmed that PVA is not only acted as a capping agent, but also a cross-linking agent. X-ray diffraction study shows that the existence of AgNPs in the poly nanocomposite film and nanoaparticles are crystalline in nature. Thermal studies suggest that the enhanced thermal stability is because of the good packing of the polar crystallites in β-PVA composites as compared to the non-polar α-phase of neat poly(vinyl alcohol) (PVA).
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Lani, N. S., N. Ngadi, A. Johari i M. Jusoh. "Isolation, Characterization, and Application of Nanocellulose from Oil Palm Empty Fruit Bunch Fiber as Nanocomposites". Journal of Nanomaterials 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/702538.
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Nanocomposites, consisting of a polymeric matrix and nanosized elements as reinforcement, have attracted significant scientific attention because of their high mechanical performance. A large variety of nanocomposites have been prepared using bio-based materials as a matrix and nanoreinforcement, so that it can reduce the dependence on nondegradable products and move to a sustainable materials basis. The objective of this study was to isolate nanocellulose from empty fruit bunch (EFB) fiber and their reinforcing effect on polyvinyl alcohol (PVA)/starch blend films. A series of PVA/starch films with different content of nanocellulose were prepared by solution casting method. Nanocellulose fiber with diameters ranging from 4 to 15 nm has been successfully prepared. On the other hand, PVA/starch films reinforced with nanocellulose fiber possess significantly improved properties compared to unreinforced film. From the results, PVA/starch films with the addition of 5% (v/v) of nanocellulose exhibited best combination of properties. This nanocomposite was found to have tensile strength at about 5.694 MPa and elongation at break was 481.85%. In addition to good mechanical properties, this nanocomposite has good water resistance and biodegradability.
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Gupta, Piyush Kumar, Senthilkumar Palanisamy, Tamilarasi Gopal, Ranjithkumar Rajamani, Soumya Pandit, Somya Sinha i Vijay Kumar Thakur. "Synthesis and Characterization of Novel Fe3O4/PVA/Eggshell Hybrid Nanocomposite for Photodegradation and Antibacterial Activity". Journal of Composites Science 5, nr 10 (12.10.2021): 267. http://dx.doi.org/10.3390/jcs5100267.
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In the 21st century, hybrid nanocomposites were widely used in bioelectronic, biosensing, photocatalytic, and biomedical applications. In the present study, we fabricated a novel Fe3O4/PVA/Eggshell hybrid nanocomposite and physicochemically characterized it using powder XRD, EDS, FTIR, VSM, and HR-TEM analysis. The XRD spectrum revealed the crystalline and FCC configuration of Fe3O4 NPs with average crystal size of 16.28 nm, and the HRTEM image indicates the prepared hybrid nanocomposite is of spherical shape with less agglomeration. This hybrid nanocomposite showed a significant photodegradation property in degrading organic pollutants such as congo red and crystal violet dyes under the sunlight irradiation. In addition, the hybrid nanocomposite also displayed a potent antibacterial property against different Gram +ve and Gram −ve bacterial pathogens. This study provides a significant example in the overview of fabrication of cost effectively, eco-friendly, and multiple-application hybrid nanocomposites through eggshell membrane fibers.
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AlFannakh, Huda, S. S. Arafat i S. S. Ibrahim. "Synthesis, electrical properties, and kinetic thermal analysis of polyaniline/ polyvinyl alcohol - magnetite nanocomposites film". Science and Engineering of Composite Materials 26, nr 1 (28.01.2019): 347–59. http://dx.doi.org/10.1515/secm-2019-0020.
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AbstractPolyaniline-poly vinyl alcohol (PANI-PVA) conducting blends containing 15 wt% aniline were synthesized by in situ polymerization of aniline. Three-phase polymer blended nanocomposites with different contents of magnetite (5, 10 and 15 wt.%) were also synthesized. We measured the current-voltage (I-V) curves for the conducting blend and its magnetite nanocomposite. We also measured their thermal stability, and performed kinetic analysis through thermogravimetric analysis. We observed that the three phase nanocomposites showed enhanced electrical conductivity compared with that of the conductive blend, and no electrical hysteresis. The PVA/PANi blend was more stable above 350∘C and the addition of Fe3O4 enhanced the thermal stability of the conductive blend. The apparent activation energy of the three phase nanocomposites was greater than those of both the pure PVA and PVA/PANi samples. These results suggest that such three phase nanocomposites could be used in a range of applications.
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Kannan, K., S. Agilan, P. Peulakumari i G. Saveetha. "Exploration of third order nonlinear optical features of CuO/PVA-PEG polymer nanocomposites". Digest Journal of Nanomaterials and Biostructures 18, nr 1 (marzec 2023): 367–75. http://dx.doi.org/10.15251/djnb.2023.181.367.
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CuO/PVA-PEG nanocomposites were prepared by solvent casting method. In XRD spectra, the shifting of peak position and the absence of remaining characteristics peaks of CuO nanoparticles in CuO/PVA-PEG indicates the formation exfoliated nanocomposites. The SEM image reveals the complete dispersion of the nanofillers in polymer matrix. FTIR spectra revealed the formation of strong H-bonds between PVA and PEG during mixing. The absorption and transmission properties of the sample were studied by UV-Vis studies. Z-scan analysis confirms the presence of two-photon absorption in the sample. The synthesized polymer nanocomposite exhibits optical nonlinearity due to the excitonexciton interaction.
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Abidin, Akhmad Zainal, i Hafis Pratama Rendra Graha. "Thermal Characterization of Bacterial Cellulose/Polyvinyl Alcohol Nanocomposite". Advanced Materials Research 1123 (sierpień 2015): 303–7. http://dx.doi.org/10.4028/www.scientific.net/amr.1123.303.
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Bacterial cellulose (BC) is a natural polymer which can be produced from various substrates easily found in Indonesia. Bacterial cellulose is believed to be a promising and cost effective bone scaffold in which a bone regeneration rate enhanced so the healing process is faster. In this experiment, Bacterial Cellulose (BC)/ Polyvin y l Alcohol (PVA) nanocomposite was made to give a further improvement in the properties. This nanocomposite was made thorough BC biosynthesis in Gluconacetobacter xylinus fermentation medium that was modified by addition of PVA. The PVA concentrations were varied as 0, 3, 6, 9, and 12 % w of fermentation medium. The culture had been agitated by magnetic stirrer for 28 days before freeze drying method was conducted to obtain dry BC/PVA nanocomposite. The product of BC/PVA nanocomposite was then studied for thermal characteristics using Differential Scanning Calorimetry (DSC) and Thermogravimetry Analysis (TGA). Pure BC has melting temperature (Tm) at 350 . 3oC and pure PVA at 181 . 3oC. Experimental results showed that the higher PVA content in fermentation medium decreased the melting temperature of BC/PVA nanocomposite produced.
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Joshi, Aruna, G. S. Mukherjee, Mukul Gupta i M. Banerjee. "Thickness dependent microstructural and magnetic studies of iron embedded PVA nanocomposite films". AIP Advances 13, nr 3 (1.03.2023): 035339. http://dx.doi.org/10.1063/5.0125613.
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This paper presents the structural and magnetic properties of polyvinyl alcohol/iron (PVA/Fe) nanocomposite films. Iron (Fe) films of different thicknesses were deposited on a PVA substrate using ion beam sputtering. The Fe nanoparticle layer thickness ranges from 3 to 50 nm on the PVA substrate. Grazing incidence x-ray diffraction has been carried out to study the structural behavior of the prepared films. An atomic force microscope records the indicated remarkable change in the roughness of the nanocomposite film as a result of initiation of vertical growth of sputtered Fe nanoparticles.Magneto-optic Kerr effect (MOKE) magnetometry and MOKE spectroscopy have been employed to evaluate the magnetic property and simultaneously study the real time growth of the magnetic domain structure for both 0° and 90° azimuthal angles. MOKE microscopic images indicated the magnetization reversal commensurate with the hysteresis loop of the nanocomposites. All the films show soft ferromagnetic behavior. Gradual development of the domain structure is observed in the MOKE micrograph with the increase in the thickness of Fe nanoparticle deposition. Ex situ magnetic force micrographs of the magnetic domain structures supported the observation of MOKE microscopic studies, which indicated switching of in-plane magnetization to out-of-plane magnetization near an Fe nanoparticle deposition thickness of 40 nm. The PVA matrix appears to be an effective material to support the growth of magnetic properties in the PVA/Fe nanocomposite system. The evolution of Fe nanostructures on PVA and the resulting magnetic behavior have been discussed.
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Abidin, Akhmad Zainal, i Hafis Pratama Rendra Graha. "Morphological Study of Bacterial Cellulose (BC)/Polyvinil Alcohol (PVA) Nanocomposite as Bone Scaffold". Advanced Materials Research 950 (czerwiec 2014): 24–28. http://dx.doi.org/10.4028/www.scientific.net/amr.950.24.
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This research describes morphological aspect of BC-PVA nanocomposite asscaffold for bone tissue that was synthesized by adding PVA to Gluconacetobacterxylinus fermentation medium. PVA concentrationswere varied as 0,3,6,9, and 12 % (w/v) of the medium. The culture was agitated with magnetic stirrer for 28 days. Freeze drying was then conducted to obtain dry BC/PVA nanocomposite. Some nanocomposite samples subjected to sonication treatments. The morphology of BC-PVA nanocomposite was examined by Scanning Electron Microscope (SEM) whileits surface area and pore characteristic were determined by nitrogen adsorption of BJH method (BET device). SEM images showed the smallest fiber diameter of approximately 35 nm andnanocomposite surface that was smoother with higher PVA content in the fermentation medium. The sonicationtreatmentcould enhance nanocomposite surface area from 17,2 m2/g to 72,7 m2/g for pure BC sample and from 9,9 m2/g to 14,3 m2/g for 12% PVA sample. BC/PVA nanocompisite had smaller pore diameter than pure BC and its size increased with more PVA content in the fermentation medium.PVA could modify BC morphology bymakinga hindrance on cellulose nanofiber sothat fiber agglomeration could be avoided andthe sonicationtreatmentshowedto enhance this phenomena.
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Kumar, S. Vasantha, V. A. Sajeevkumar, Johnsy George i Sunny Kumar. "Enhancing properties of polyvinyl alcohol film using sorghum starch nanocrystals – A cost effective filler from natural source". Defence Life Science Journal 2, nr 2 (31.05.2017): 169. http://dx.doi.org/10.14429/dlsj.2.11380.
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<p>Poly Vinyl Alcohol (PVA) nanocomposite films with Sorghum Starch Nanocrystals (SSN) were prepared by incorporating various concentrations of SSN in PVA. SSN was isolated using acid hydrolysis of sorghum starch. The morphological studies of SSN using Atomic Force Microscopy (AFM) revealed that the particle size varied from 65 to 68 nm. The mechanical properties of PVA-SSN nanocomposite films indicated an improvement in tensile strength and percentage elongation at break when compared to that of PVA films. This can be attributed to the stronger interaction of PVA with SSN due to hydrogen bonding. Besides this, PVA-SSN nanocomposite films also exhibited good thermal properties. Thus, the use of SSN (a cost effective filler from natural source) imparted superior properties to the PVA nanocomposite films, which will be beneficial for applications such as food packaging. </p>
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Li, Yong-Ping, Hitoshi Takagi, Antonio N. Nakagaito i Takumi Watanabe. "Effect of mixing ratio on mechanical properties of mixture of chitin nanofibers and microfibrillated cellulose reinforced PVA hybrid nanocomposites". Materials Express 11, nr 9 (1.09.2021): 1523–33. http://dx.doi.org/10.1166/mex.2021.2038.
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In order to explore the possibility of polyvinyl alcohol (PVA) reinforced by mixture of chitin nanofibers (ChNFs) and microfibrillated cellulose (MFC) instead of a single reinforcing phase, mechanical properties of PVA based hybrid nanocomposites reinforced with combination of ChNFs and MFC in various mixing ratios were investigated. For comparison, two different experiments were conducted to prepare nanocomposite films by casting technical processing, where ratios of ChNFs to MFC were mixed varying from 1:0, 4:1, 3:2, 1:1, 2:3, 1:4, and 0:1 in both projects, while in Project 1 the weights of PVA and ChNFs were always kept constant and the weight of PVA only was kept constant in Project 2. The results were as follows: (1) The hybrid ternary nanocomposites acquired the highest Young’s modulus and tensile strength when ratio of ChNFs to MFC was 1:1, which exhibited higher Young’s modulus and higher tensile strength than PVA/ChNFs composites, but delivered higher Young’s modulus and similar tensile strength comparing to PVA/MFC composites; (2) Aggregations and voids inside nanocomposites were detrimental to mechanical properties of PVA based hybrid nanocomposites. In some industries such as food packing, PVA based hybrid nanocomposites at mixing ratio 1:1 of ChNFs to MFC are applied presumably with ChNFs partly instead of MFC in the future.
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Poyraz, Bayram, Ayhan Tozluoğlu, Zeki Candan i Ahmet Demir. "Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites". Journal of Polymer Engineering 37, nr 9 (27.11.2017): 921–31. http://dx.doi.org/10.1515/polyeng-2017-0022.
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Abstract This study reports on the effect of organic polyvinyl alcohol (PVA) and silica matrix on the properties of cellulose-based nanocomposites. Nanofibrillated cellulose was isolated from kraft pulp and treated with Pulpzyme HC 2500 enzyme prior to high-pressure homogenization in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose, nanocellulose-PVA (NC-PVA) and nanocellulose-silica (NC-Si). Chemical characterization and crystallization were determined with FTIR. Thermal stability was investigated with thermogravimetric analysis. Morphological alterations were monitored with scanning electron microscopy. A universal testing machine and dynamic mechanical thermal analysis were used for determination of Young’s and storage moduli. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. Considerable alterations were seen under FTIR. Thermal stability was lower in NC-Si than in NC-PVA due to lower crystallinity. Higher Young’s modulus and storage moduli were observed in NC-PVA than in NC-Si. NC-PVA exhibited a singular relaxation process, while a double relaxation process was seen in NC-Si. Consequently, the nanocomposite film prepared from the organic matrix (NC-PVA) had a mechanical advantage for industrial applications. However, neat NC composite revealed the highest storage modulus and thermal stability.
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Amaregouda, Yamanappagouda, Tilak Gasti i Kantharaju Kamanna. "Optoelectronic, microstructural, ecofriendly and photo-catalytic evaluation of Aspartic acid cross-linked Poly (vinyl alcohol)/Copper Oxidenanotubescomposite films". IOP Conference Series: Materials Science and Engineering 1221, nr 1 (1.03.2022): 012008. http://dx.doi.org/10.1088/1757-899x/1221/1/012008.
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Abstract The present work describes design and preparation of aspartic acid (Asp) cross-linked Poly (vinyl alcohol) (PVA)/Copper oxide nanotubes (CuO NTs) composite filmsvia solution casting method.The CuO NTswere prepared by novel biogenic method using RobiniaPseudoacaciaLeaf Extract.Theprepared CuO NTs and PVA/CuO/Asp nanocomposite filmsarecharacterized by various techniques.The adsorption and photo-catalytic efficiencies of PVA/CuO/Asp nanocomposite films were compared with pristine CuO NTs. The adsorption capacity of PVA/CuO/Asp nanocomposite films showed higher due to presence of active sites, high surface activity and semiconducting nature of CuO NTs and Asp embedded in PVA matrix. The comparative photocatalytic activities of the CuO NTsand PVA/CuO NTs/Asp nanocomposite filmsare examinedagainst methylene blue (MB) as a substrate degradation, and film PVA/CuO NTs/Asp showed highest (up to 77%) degradation compared to other films. The improved photocatalytic behavior of PVA nanocomposite film attributed to its narrower band gapreduces the recombination rate of exited electron-hole, enhanced UV-Vis absorption intensity, extinction coefficient and refractive index, improved utilization of sunlight and enhanced adsorption of dye due to functional groups, biodegradable, surface wettability, hydrophilic surface and self-cleaning nature.
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Naser, Ali Kadhim, Dhafer Manea H. Al-Shamkhee i Qahtan Adnan Abed. "Enhanced Electrical Properties of Crystalline Silicon Solar Cells via Nano-Composite Polyvinyl-Alcohol/Titanium Dioxide". International Journal of Design & Nature and Ecodynamics 16, nr 5 (29.10.2021): 557–64. http://dx.doi.org/10.18280/ijdne.160510.
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Reflection loss and solar cell temperature both have a significant impact on solar cell efficiency and, consequently, on power generation. Herein, the aim is to investigate into the impact of Nanocomposite Titanium Dioxide (TiO2)/Polyvinyl Alcohol (PVA) on polycrystalline silicon solar cells. The solvent casting method is employed to prepare nanocomposite TiO2/PVA for deposition on the front side of the solar cell. The Tauc plot is used to investigate the influence of TiO2 nanoparticle concentration (10-20nm) on the energy bandgap of a nanocomposite. To test the optical properties of the solar cell after depositing the Nanocomposite coating film and to confirm the suspension of TiO2 in PVA and construct a Nanocomposite, an ultraviolet-visible spectrometer and a Fourier transform infrared spectrometer are provided. The results show that increasing the TiO2 in the TiO2/PVA Nanocomposite increases the energy bandgap. The Ultraviolet-Visible spectrometer observes that the Nanocomposite films absorb the Ultraviolet wavelength and transmittance at the visible wavelength. Finally, it found the lowest reflection obtained was 3.9% for 0.2wt% TiO2 in TiO2/PVA nanocomposite and the enhancement of the solar cell efficiency was (+2.3%).
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Chou, Chun-Tu, Shih-Chen Shi i Chih-Kuang Chen. "Sandwich-Structured, Hydrophobic, Nanocellulose-Reinforced Polyvinyl Alcohol as an Alternative Straw Material". Polymers 13, nr 24 (18.12.2021): 4447. http://dx.doi.org/10.3390/polym13244447.
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An environmentally friendly, hydrophobic polyvinyl alcohol (PVA) film was developed as an alternative to commercial straws for mitigating the issue of plastic waste. Nontoxic and biodegradable cellulose nanocrystals (CNCs) and nanofibers (CNFs) were used to prepare PVA nanocomposite films by blade coating and solution casting. Double-sided solution casting of polyethylene-glycol–poly(lactic acid) (PEG–PLA) + neat PLA hydrophobic films was performed, which was followed by heat treatment at different temperatures and durations to hydrophobize the PVA composite films. The hydrophobic characteristics of the prepared composite films and a commercial straw were compared. The PVA nanocomposite films exhibited enhanced water vapor barrier and thermal properties owing to the hydrogen bonds and van der Waals forces between the substrate and the fillers. In the sandwich-structured PVA-based hydrophobic composite films, the crystallinity of PLA was increased by adjusting the temperature and duration of heat treatment, which significantly improved their contact angle and water vapor barrier. Finally, the initial contact angle and contact duration (at the contact angle of 20°) increased by 35% and 40%, respectively, which was a significant increase in the service life of the biodegradable material-based straw.
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Le, Thu Dieu, Luyen Thi Tran, Hue Thi Minh Dang, Thi Thu Huyen Tran i Hoang Vinh Tran. "Graphene Oxide/Polyvinyl Alcohol/Fe3O4 Nanocomposite: An Efficient Adsorbent for Co(II) Ion Removal". Journal of Analytical Methods in Chemistry 2021 (9.03.2021): 1–10. http://dx.doi.org/10.1155/2021/6670913.
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In this work, an effective nanocomposite-based adsorbent directed to adsorb cobalt (Co2+) ion was successfully synthesized from graphene oxide (GO), polyvinyl alcohol (PVA), and magnetite (Fe3O4) nanoparticles via a coprecipitation technique. The synthesized GO/PVA/Fe3O4 nanocomposite was applied for Co2+ ion removal with the optimized working conditions including 100 min of contact time, 0.01 g of adsorbent dosage, pH of 5.2, and 50°C of temperature. The investigation of adsorption kinetics showed that the adsorption of Co2+ ion onto the GO/PVA/Fe3O4 nanocomposite followed the pseudo-second-order kinetic model with the rate constant k2 being 0.0026 (g mg−1·min−1). The Langmuir model is suitable to describe the adsorption of Co2+ ion onto the GO/PVA/Fe3O4 nanocomposite with the maximum sorption capacity (qmax) reaching 373.37 mg·g−1. The obtained results also indicated that the GO/PVA/Fe3O4 nanocomposite can adsorb/regenerate for at least 5 cycles with a little reduction in removal efficiency. Therefore, we believe that the GO/PVA/Fe3O4 nanocomposite could be used as a potential adsorbent for heavy metal treatment in terms of high adsorption capacity, fast adsorption rate, and recyclability.
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Li, Bao Guang, Yong Zi Xu, Lu Bai, Huan Dai, Cai Cai Xie i Hai Bin Li. "Ultrasonic Effect on Fabrication of Intercalated MgAl-LDH/PVA Nanocomposites via Exfoliation-Adsorption Route". Key Engineering Materials 727 (styczeń 2017): 532–36. http://dx.doi.org/10.4028/www.scientific.net/kem.727.532.
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Glycine intercalated Mg/Al-layered double hydroxides (LDH-G)/PVA nanocomposites were prepared via exfoliation-adsorption route based on exfoliation of LDH-G in formamide. The effect of ultrasonic treatment on the fabrication of LDH-G/PVA nanocomposites was investigated. The results of XRD suggest that chains of PVA with double layer arrange into the galleries of restacking LDH platelets with the formation of intercalated-type nanocomposite. Experiments present that ultrasonic treatment on the colloid of LDH-G/PVA increases the amount of platelet which forms the intercalated phase, and improves the regularity of LDH-G arrays in the c direction. It is demonstrated the exfoliated LDH platelets orient in its normal paralleling the flow direction at the high shear rate induced by ultrasound. Simultaneously, under the enhanced temperature caused by long term of ultrasonic treatment, PVA chains extend more and the interaction between PVA chains and LDH layers is reinforced. A model was proposed for various stages of LDH platelets and PVA chains in their mixed colloid during ultrasonic treatment which describes the fabrication of improved hybrid structure.
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Handoko, Fauzi, i Yusril Yusuf. "Synthesis and Physicochemical Properties of Poly(vinyl) Alcohol Nanocomposites Reinforced with Nanocrystalline Cellulose from Tea (Camellia sinensis) Waste". Materials 14, nr 23 (24.11.2021): 7154. http://dx.doi.org/10.3390/ma14237154.
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The purpose of this study was to utilize cellulose from tea waste as nanocrystalline cellulose (NCC), which is used as a filler in poly(vinyl) alcohol (PVA) nanocomposites. To obtain the NCC, a chemical process was conducted in the form of alkali treatment, followed by bleaching and hydrolysis. Nanocomposites were formed by mixing PVA with various NCC suspensions. With chemical treatment, lignin and hemicellulose can be removed from the tea waste to obtain NCC. This can be seen in the functional groups of cellulose and the increase in crystallinity. The NCC had a mean diameter of 6.99 ± 0.50 nm. Furthermore, the addition of NCC to the PVA nanocomposite influenced the properties of the nanocomposites. This can be seen in the general increase in opacity value, thermal and mechanical properties, and crystallinity, as well as the decrease in the value of the swelling ratio after adding NCC. This study has revealed that NCC from tea waste can be used to improve the physicochemical properties of PVA film.
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Kadhim, Mohammed Abdul, i Ehssan Al-Bermany. "New fabricated PMMA-PVA/graphene oxide nanocomposites: Structure, optical properties and application". Journal of Composite Materials 55, nr 20 (3.03.2021): 2793–806. http://dx.doi.org/10.1177/0021998321995912.
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Graphene oxide nanosheets (GO) bring more interest in the tunable bandgap and enhanced the optical properties of nanocomposites. The developed method successfully mixed the PMMA- dissolved in dimethylformamide (DMF) with PVA dissolved in distilled water (DW) and DMF. New (PMMA-DMF)-(PVA-DW-DMF)/GO nanocomposite was successfully fabricated with various loading ratios of GO nanosheets for the first time. Several factors were applied to get fine desperation and homogeneous using the acoustic-solution casting method. Optical Microscope (OM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV–visible spectrophotometer were applied to investigate the structure and optical properties of the PMMA-PVA-GO nanocomposite. The OM images confirmed the fine homogenous matrix and GO distribution in the nanocomposites. FTIR spectra exhibited the most functional group of polymers and GO in the nanocomposites and strong interfacial interaction between the GO and matrix as confirmed by the shifting in the XRD patterns of the PMMA. The optical properties results of the PMMA-PVA/GO nanocomposites revealed an improvement up to 400% of the absorbance, 337% of the absorption coefficient, 51% of the refractive index, 210% of the real and 125% of the imaginary dielectric constants in terms to increase the GO concentrations, whereas the reduction in the transmittance and energy bandgap results of allowed and forbidden indirect transition were exhibited up to 9 and 16.4%, respectively. These results could grow for better and wide applications such as radiation shielding, specific optoelectronic applications, and filters ultraviolet also could use in landfilling the chemical, nuclear, and radioactive waste.
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Saleh, Hoda H., Rehab Sokary i Zakaria I. Ali. "Radiation – induced preparation of polyaniline/poly vinyl alcohol nanocomposites and their properties". Radiochimica Acta 107, nr 8 (26.07.2019): 725–35. http://dx.doi.org/10.1515/ract-2018-3003.
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Abstract Polyaniline (PANI) nanoparticles and PANI/poly vinyl alcohol (PVA) nanocomposite films were synthesized by the oxidative polymerization of aniline and ammonium peroxodisulfate (APS), as an oxidizing agent in aqueous medium. The PANI/PVA nanocomposite films were exposed to γ-irradiation after oxidative polymerization. Synthesized polyaniline (PANI) nanoparticles and PANI/PVA nanocomposite films were characterized by attenuated total reflectance infrared spectroscopy (FTIR-ATR), X-ray diffraction, high resolution scanning electron microscopy, (HRSEM) high resolution transmission electron microscopy, (HRTEM) and UV-VIS absorption spectroscopy. Energy band gap of PANI nanofibers was determined from Tauc’s plots which equal 4.2 eV. Scanning electron microscopy images show that chemically synthesized of polyaniline has nanofibers structure and irradiated PANI/PVA nanocomposite have a mixture of nanorod and nanosphere structures. The transmission electron microscopy show that chemically synthesized of polyaniline has average length in the range 34 ± 10 nm with less wide distribution, where as the irradiated PANI/PVA nanocomposite has coreshell structure.
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Cobos, Mónica, Iker De-La-Pinta, Guillermo Quindós, María Jesús Fernández i María Dolores Fernández. "Synthesis, Physical, Mechanical and Antibacterial Properties of Nanocomposites Based on Poly(vinyl alcohol)/Graphene Oxide–Silver Nanoparticles". Polymers 12, nr 3 (24.03.2020): 723. http://dx.doi.org/10.3390/polym12030723.
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The design of new materials with antimicrobial properties has emerged in response to the need for preventing and controlling the growth of pathogenic microorganisms without the use of antibiotics. In this study, partially reduced graphene oxide decorated with silver nanoparticles (GO–AgNPs) was incorporated as a reinforcing filler with antibacterial properties to poly(vinyl alcohol) (PVA) for preparation of poly(vinyl alcohol)/graphene oxide-silver nanoparticles nanocomposites (PVA/GO–AgNPs). AgNPs, spherical in shape and with an average size of 3.1 nm, were uniformly anchored on the partially reduced GO surface. PVA/GO–AgNPs nanocomposites showed exfoliated structures with improved thermal stability, tensile properties and water resistance compared to neat PVA. The glass transition and crystallization temperatures of the polymer matrix increased with the incorporation of the hybrid. The nanocomposites displayed antibacterial activity against Staphylococcus aureus and Escherichia coli in a filler content- and time-dependent manner. S. aureus showed higher susceptibility to PVA/GO–AgNPs films than E. coli. Inhibitory activity was higher when bacterial cells were in contact with nanocomposite films than when in contact with leachates coming out of the films. GO–AgNPs based PVA nanocomposites could find application as wound dressings for wound healing and infection prevention.
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Rahim, A., K. Liaqat, S. Fazil, Z. Liaqat, S. A. H. Shah, W. Rehman, M. Farooq, S. Haq i M. Nawaz. "Synthesis and characterization of covalently grafted graphene oxide – poly (vinyl alcohol)/ carbon nanotubes nanocomposites". Digest Journal of Nanomaterials and Biostructures 16, nr 3 (lipiec 2021): 1147–55. http://dx.doi.org/10.15251/djnb.2021.163.1147.
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Herein we have reported a simple procedure for the synthesis of covalently grafted graphene oxide poly (vinyl alcohol) (PVA-g-GO). Later on, multiwalled carbon nanotubes (MWCNTs) were dispersed in this PVA-g-GO matrix by sequential stirring and sonication. Nanocomposites with varying weight percent of graphene oxide (GO) and multiwalled carbon nanotubes (MWCNTs) were synthesized. These nanocomposites have shown excellent thermal and mechanical stability. It also appears that presence of graphene oxide has assisted in dispersing the MWCNTs. Combine effect of GO and MWCNTs has resulted in the nanocomposite with electrical conductivity of 2.02E-09 S/cm.
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Dejen, Kindnew Demssie, Enyew Amare Zereffa, H. C. Ananda Murthy i Andualem Merga. "Synthesis of ZnO and ZnO/PVA nanocomposite using aqueous Moringa Oleifeira leaf extract template: antibacterial and electrochemical activities". REVIEWS ON ADVANCED MATERIALS SCIENCE 59, nr 1 (27.10.2020): 464–76. http://dx.doi.org/10.1515/rams-2020-0021.
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AbstractThe application of flexible polymer nanocomposites for food packaging to inactivate microorganisms associated with foods is the demand of the present-day food industry to assure quality throughout the packaging operation. The utilization of polyvinyl alcohol (PVA) assisted zinc oxide nanocomposite for food stuff packaging has been very attractive in the recent past. Nanostructured ZnO was synthesized at optimized pH (10.5) from different ratios of zinc acetate and Moringa oleifeira leaf extract (1:7, 1:3, 1:1 and 3:1). ZnO coated polyvinyl alcohol (ZnO/PVA) nanocomposites were prepared from 5, 9, 13 and 16% by wt of ZnO and PVA using solution casting method. The thermal stability of ZnO synthesized with 1:1 ratio at pH 10.5 was investigated with TGA/DTA. The analytical techniques such as X-ray diffraction (XRD), ultra-violate visible analysis (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) were used for the characterization of the synthesized ZnO and ZnO/PVA nanocomposites (NCs). The antibacterial activity of the synthesized ZnO and ZnO/PVA NCs were evaluated against gram negative E. coli and gram positive S. aureus bacteria. The electrochemical stability of ZnO/PVA NCs was also investigated by cyclic voltammetric (CV) method. The thermogram of ZnO indicated that the oxide was found to be stable even beyond 500°C. The SEM analysis revealed rod shaped morphology for synthesized ZnO from 1:1 ratio at pH 10.5. But the nanocomposite prepared with 5% of ZnO of (1:1) at the same pH exhibited uniformly dispersed rod-shaped particle on the surface as well as in matrix of polyvinyl alcohol film. According to XRD result, ZnO synthesized with more percentage of plant extract resulted in the small size crystallites while that with low percentage of plant extract resulted in the larger crystallite size. The antibacterial inhibition efficiency of ZnO/PVA NCs was better and found to increase with increase in the amount of ZnO.
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Bekhit, Mohamad, Asmaa Sobhy, Zakaria I. Ali i Sameh M. Gafar. "Efficient monitoring of dosimetric behaviour for copper nanoparticles through studying its optical properties". Radiochimica Acta 107, nr 6 (26.06.2019): 523–29. http://dx.doi.org/10.1515/ract-2018-3010.
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Abstract A novel high-dose dosimeter based on γ radiation reduction of copper ions and formation of copper metal inside polymer matrix were investigated. γ radiation induced synthesis of copper nanoparticles (CuNPs) in poly vinyl alcohol films were studied by UV-Visible Spectrophotometer, X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The optical absorption spectra showed that the Cu/PVA nanocomposite films have surface plasmon resonance (SPR) of copper nanoparticles which depending on irradiation doses. Upon γ irradiation these films turns its color from faint blue to deep reddish brown depending on metal ion concentration. The XRD pattern and FTIR spectrum confirm the formation of the CuNPs. The response of Cu/PVA nanocomposite dosimeters depends on both the irradiation doses and concentration of copper precursor. The dose range for these films was from 50 to 650 kGy, revealing its important applications for high dose dosimetry. Cu/PVA nanocomposites films exhibit good post-irradiation stability in dark and light.
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Bai, Lu, Yuan Gao, Shuai Li i Li Ping Zhang. "Preparation and Characterization of Pol(vinyl Alcohol）/ Cellulose Nanocomposites". Advanced Materials Research 233-235 (maj 2011): 2383–86. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2383.
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In this study, nanocomposite membranes were prepared from poly (vinyl alcohol) (PVA) with different amounts of cellulose nanocrystals as filler and characterized by thermogravimetry (TG). Swelling sorption behavior of various feed alcohol mixtures was investigated at 80°C, and found that NCC in PVA matrix could help to reduce the overall membrane swelling. Mechanical properties of the nanocomposite membranes were examined in relation to NCC content in the composite. Optimal NCC content in the composite was found to be 3 wt% in terms of its overall properties as compared to neat PVA film. With the addition of 3 wt% NCC to PVOH the ultimate tensile strength showed improvement compared to pure PVA. The PVA/ NCC nanocomposite membrane had shown increases in elongation at low filler loadings. The TG analysis demonstrated that the nanocomposite membranes exhibited higher thermal resistance.
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Tsou, Chi-Hui, Yu-Jie Shui, Juan Du, Wei-Hua Yao, Chin-San Wu, Maw-Cherng Suen i Shuang Chen. "Characterization and Morphology of Nanocomposite Hydrogels with a 3D Network Structure Prepared Using Attapulgite-Enhanced Polyvinyl Alcohol". Polymers 15, nr 11 (31.05.2023): 2535. http://dx.doi.org/10.3390/polym15112535.
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In this investigation, purified attapulgite (ATT) and polyvinyl alcohol (PVA) were utilized to fabricate nanocomposite hydrogels and a xerogel, with a focus on studying the impact of minor additions of ATT on the properties of the PVA nanocomposite hydrogels and xerogel. The findings demonstrated that at a concentration of 0.75% ATT, the water content and gel fraction of the PVA nanocomposite hydrogel reached their peak. Conversely, the nanocomposite xerogel with 0.75% ATT reduced its swelling and porosity to the minimum. SEM and EDS analyses revealed that when the ATT concentration was at or below 0.5%, nano-sized ATT could be evenly distributed in the PVA nanocomposite xerogel. However, when the concentration of ATT rose to 0.75% or higher, the ATT began to aggregate, resulting in a decrease in porous structure and the disruption of certain 3D porous continuous structures. The XRD analysis further affirmed that at an ATT concentration of 0.75% or higher, a distinct ATT peak emerged in the PVA nanocomposite xerogel. It was observed that as the content of ATT increased, the concavity and convexity of the xerogel surface, as well as the surface roughness, decreased. The results also confirmed that the ATT was evenly distributed in the PVA, and a combination of hydrogen bonds and ether bonds resulted in a more stable gel structure. The tensile properties exhibited that when compared with pure PVA hydrogel, the maximum tensile strength and elongation at break were achieved at an ATT concentration of 0.5%, indicating increases of 23.0% and 11.8%, respectively. The FTIR analysis results showed that the ATT and PVA could generate an ether bond, further confirming that ATT could enhance the PVA properties. The TGA analysis showed that the thermal degradation temperature peaked when the ATT concentration was at 0.5%, providing further evidence that the compactness of the nanocomposite hydrogel and the dispersion of the nanofiller was superior, contributing to a substantial increase in the mechanical properties of the nanocomposite hydrogel. Finally, the dye adsorption results displayed a significant rise in dye removal efficiency for methylene blue with the increase in the ATT concentration. At an ATT concentration of 1%, the removal efficiency rose by 103% compared with that of the pure PVA xerogel.
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Sirousazar, M., M. Kokabi, A. R. Bahramian i Z. M. Hassan. "PVA/Kaolinite Nanocomposite Hydrogels: Preparation Method and Characterization". Advanced Materials Research 383-390 (listopad 2011): 3854–57. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.3854.
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In this work, nanocomposite hydrogels on the basis of Polyvinyl alcohol (PVA) and kaolinite nanoclay were prepared by the repeatedly freezing-thawing method. The structure and morphology of nanocomposite hydrogels were studied by the XRD, TEM and SEM techniques. The function of nanoclay in the nanocomposite hydrogels was investigated using the FTIR and DSC tests. It was found that the prepared nanocomposite hydrogels have the intercalated morphology with good dispersion of nanoclay layers in hydrogel matrix. DSC results showed some shifting in the glass transition temperature of PVA hydrogel in presence of nanoclay. The FTIR results also showed that some interactions have been developed between the hydroxyl groups of PVA chains and kaolinite layers in nanocomposite hydrogels.
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Mohammed, Nadheer J., Zahraa S. Rasheed i Ashraf S. Hassan. "Improvement Optical Properties of PVA/ TiO2 and PVA/ ZnO Nanocomposites". Al-Mustansiriyah Journal of Science 29, nr 3 (10.03.2019): 118. http://dx.doi.org/10.23851/mjs.v29i3.629.
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The optical properties of polyvinyl alcohol (PVA) doped TiO2 and ZnO nanoparticles respectively, were studied. PVA/TiO2 and PVA/ZnO nanoparticles were prepared by the pulsed laser ablation technique (PLA).The optical properties of PVA/ TiO2 and PVA/ ZnO nanocomposite solution have been investigated by transmittance data and absorption spectra. The optical band gap (Eg) was determined and the optical absorption spectra showed that a direct transition. The energy gap of PVA/ ZnO nanoparticles have been observed the decreases its value and increasing in the optical conductivity as compared to PVA/ TiO2.The refractive index (n), extinction coefficient (k) and dielectric constant have been also investigated; it was found that all the above parameters affects by doping.
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Sharma, S. K., J. Prakash i P. K. Pujari. "Effects of the molecular level dispersion of graphene oxide on the free volume characteristics of poly(vinyl alcohol) and its impact on the thermal and mechanical properties of their nanocomposites". Physical Chemistry Chemical Physics 17, nr 43 (2015): 29201–9. http://dx.doi.org/10.1039/c5cp05278e.
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The effects of the molecular dispersion of graphene oxide on (A) the crystallinity of PVA–GO nanocomposite films and (B) nanohole size distribution in the amorphous region of PVA–GO nanocomposite films.
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Ramrakhiani, Meera, i Sakshi Sahare. "Photo-and Electro-Luminescence in Copper Doped Zinc Sulphide Nanoparticles and Nanocomposites". Solid State Phenomena 201 (maj 2013): 181–96. http://dx.doi.org/10.4028/www.scientific.net/ssp.201.181.
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Copper doped Zinc Sulfide (ZnS:Cu)) is a known green light emitter. Present paper reports luminescence of ZnS:Cu nanoparticles and nanocomposites. Three different nanostructures: mercaptoethanol capped ZnS:Cu nanoparticles, polyvinyl alcohol (PVA) capped ZnS:Cu nanoparticles and ZnS:Cu/PVA nanocomposites have been prepared by chemical route. X-ray diffraction (XRD) revealed cubic zinc blende structure of ZnS:Cu nanocrystals of size below 20 nm. The particle size is found to decrease with increasing capping agent concentration or ZnS loading in PVA matrix. Optical absorption spectra show blue shift in the absorption edge indicating quantum size effect. Photoluminescence (PL) of all the samples was studied by exciting with 212 nm light. The PL spectra of ZnS:Cu/ PVA nanocomposite films show quite broad emission peak at 415 nm where as the PL spectra of mercaptoethanol capped and PVA capped nanoparticles show a very narrow peak at 426 nm and 403 nm respectively. It seems that the nature of passivation of surface states affects the position of surface states. Electroluminescence (EL) studies have shown that light emission starts at a threshold and then increases with voltage. Higher EL intensity and lower threshold voltage is obtained in case of smaller particles. The EL spectra of all the samples are found to be broad with peak at about 420 nm. The EL intensity of ZnS:Cu/PVA nanocomposites is much larger than the ZnS:Cu nanoparticles. The high efficiency EL devices for display and lighting can be fabricated using ZnS:Cu nanocomposites with PVA matrix giving violet emission.
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Li, Juan, Guantao Zhang i Dongjie Zhang. "Structural Optimization of Sorghum Straw Powder/ZnO/PVA Nanocomposite Films". Coatings 12, nr 8 (22.08.2022): 1226. http://dx.doi.org/10.3390/coatings12081226.
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This study sought to improve the utilization of sorghum straw resources and promote the industrial production of new biomass materials. Herein, we fabricated SSP/ZnO/PVA nanocomposite films from sorghum straw powder (SSP), corn starch, polyvinyl alcohol (PVA), and nanostructured ZnO via the casting method. Then, we used response surface methodology to examine the effects of the mass concentrations of SSP, glycerol (Gly), and nanostructured ZnO, as well as the starch–PVA mass ratio on the tensile strength (TS) and water vapor permeability (WVP) of the SSP/ZnO/PVA nanocomposite films. The optimum preparation conditions were as follows: SSP mass concentration of 2.0 g/150 mL, Gly mass concentration of 2.5 g/150 mL, starch–PVA mass ratio of 6:4.5, and nanostructured ZnO mass concentration of 0.7 g/150 mL. The TS and WVP of the prepared films were 47.57% higher and 27.07% lower, respectively, than those of ZnO/PVA composite films without SSP. Scanning electron microscopy and atomic force microscopy showed that the SSP/ZnO/PVA nanocomposite films had smooth surfaces and dense cross-sections, without obvious delamination or phase separation. Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analyses revealed that SSP was highly compatible with the ZnO/PVA matrix. Thus, SSP addition could improve the crystallinity, thermal stability, and matrix interactions of SSP/ZnO/PVA nanocomposite films.
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Jassim, Hanan H., i Fouad Sh Hashim. "Synthesis of (PVA/PEG: ZnO and Co3O4) Nanocomposites: Characterization and Gamma Ray Studies". NeuroQuantology 19, nr 4 (18.05.2021): 47–56. http://dx.doi.org/10.14704/nq.2021.19.4.nq21036.
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Polymer blend (PVA/PEG) and its nanocomposites with constant ZnO and different ratios of Co3O4 NPs films synthesized using solution cast technique. The obtained products were identified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Optical characteristics have been studied by UV-visible spectroscopy. FT-IR spectra confirmed of the produce the functional groups present in polymer nanocomposite systems. XRD analysis confirmed the formation nanocomposite films more crystalline from the polymeric matrix. SEM showed a powerful dispersion of ZnO and Co3O4 NPs on the surface of the polymeric matrix. The D.C electrical conductivity of the polymeric system (PVA/PEG) increases after addition of and Co3O4 NPs for all temperatures under test. D.C measurements indicate that all films having one activation energy, and that its value increases with the increase in the percentage of addition. The A.C electrical properties showed that the dielectric constant and dielectric loss for all films decreases with the increase of the electric field frequency, and that its values increase with the increasing of the wt.% of Co3O4 NPs. The (PVA/PEG) and its nanocomposite with ZnO and different wt.% of Co3O4 films have good linear attenuation coefficients for gamma ray radiation.
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Fakoori, Elham, Hassan Karami i Azizollah Nezhadali. "Synthesis and characterization of binary and ternary nanocomposites based on TiO2, SiO2 and ZnO with PVA based template-free gel combustion method". Materials Science-Poland 37, nr 3 (1.09.2019): 426–36. http://dx.doi.org/10.2478/msp-2019-0051.
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AbstractBinary and ternary nanocomposites based on TiO2, SiO2 and ZnO were synthesized by PVA-based template-free gel combustion method. The morphology and the particles sizes of the synthesized samples depended on some parameters including the initial concentrations of metal salts and PVA amount in the sol, solvent composition and solution pH. Effects of these parameters were investigated and optimized by using the Taguchi method. In the experimental design, the Taguchi L25 array was used to investigate six factors at five levels. The samples were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) specific surface areas, scanning electron microscopy (SEM). The obtained results showed that the present method can be used to synthesize TiO2/SiO2/ZnO ternary nanocomposite with an effective surface area of 0.3 m2 · g−1 and ZnO/TiO2, TiO2/SiO2, ZnO/SiO2 binary nanocomposites with an effective surface area of 234 m2 · g−1, 6 m2 · g−1 and 0.5 m2 · g−1, respectively. The ZnO/TiO2 nanocomposite which was synthesized under the following experimental conditions: 2.5 wt.% Zn salt, 2.5 wt.% Ti salt, 2.0 wt.% PVA, pH = 1 and ethanol:water ratio 30:70 was selected by the Taguchi method as an optimum sample with the smallest particles (average diameter = 50 nm).