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Relevant bibliographies by topics / (poly)vinyl Alcohol(PVA) Nanocomposite

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Academic literature on the topic '(poly)vinyl Alcohol(PVA) Nanocomposite'

Author: Grafiati

Published: 7 September 2023

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Journal articles on the topic "(poly)vinyl Alcohol(PVA) Nanocomposite"

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PANDA, BHABANI SHANKAR, and 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, no. 4 (March 20, 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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Bandyopadhyay, Abhijit, Mousumi De Sarkar, and Anil K. Bhowmick. "Solution Rheology of Poly(vinyl alcohol)/Silica Hybrid Nanocomposites." Polymers and Polymer Composites 13, no. 5 (July 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, and 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, no. 3 (March 1, 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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Patil, Mallikarjunagouda, Shridhar N. Mathad, Arun Y. Patil, Muhammad Nadeem Arshad, Hajar Saeed Alorfi, Madhu Puttegowda, Abdullah M. Asiri, Anish Khan, and Naved Azum. "Synthesis and Characterization of Microwave-Assisted Copolymer Membranes of Poly(vinyl alcohol)-g-starch-methacrylate and Their Evaluation for Gas Transport Properties." Polymers 14, no. 2 (January 17, 2022): 350. http://dx.doi.org/10.3390/polym14020350.

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Poly(vinyl alcohol) (PVA) is an excellent membrane-forming polymer and can be modified with potato starch and methyl acrylate monomers to obtain copolymers with improved physical and chemical properties. The study presents the synthesis of poly(vinyl alcohol)-g-starch-poly(methyl acrylate) PVA-g-St-g-PMA copolymers using microwave irradiation technique and potassium persulfate initiator. Solution casting and solvent evaporation methods were adopted for the fabrication of polyvinyl alcohol-g-starch-acrylamide composite membranes. The synthesized graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal analysis. The modified nanocomposite membranes were showed very promising results with the parameters permeability and selectivity. The nanocomposite membranes exhibited the advantages of easy handling and reuse.

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Lee, Min Eui, and Hyoung-Joon Jin. "Nanocomposite Films of Poly(vinyl alcohol)-Grafted Graphene Oxide/Poly(vinyl alcohol) for Gas Barrier Film Applications." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 8348–52. http://dx.doi.org/10.1166/jnn.2015.11257.

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Poly(vinyl alcohol) (PVA) composites containing graphene oxide (GO) functionalized with PVA were synthesized via the esterification of the carboxylic groups of GO. The presence of PVA-grafted GO (PVA-g-GO) in the PVA matrix induced strong interactions between the chains of the PVA matrix and allowed the PVA-g-GO to be uniformly dispersed throughout the matrix. The grafting of PVA to GO increased the gas barrier properties of the GO/PVA composites because of the increased compatibility between GO and PVA. The PVA-g-GO/PVA composites were used to coat the surface of poly(ethylene terephthalate) films. These coated films exhibited excellent gas barrier properties; the film containing 0.3 wt% of PVA-g-GO had an oxygen transmission rate (OTR) of 0.025 cc/(m2 · day) and an optical transmittance of 83.8%. As a result, PVA-g-GO/PVA composites that exhibited enhanced gas barrier properties were prepared with a solution mixing method.

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Diken, Mehmet Emin, Berna Koçer Kizilduman, Begümhan Yilmaz Kardaş, Enes Emre Doğan, Mehmet Doğan, Yasemin Turhan, and Serap Doğan. "Synthesis, characterization, and their some chemical and biological properties of PVA/PAA/nPS hydrogel nanocomposites: Hydrogel and wound dressing." Journal of Bioactive and Compatible Polymers 35, no. 3 (May 2020): 203–15. http://dx.doi.org/10.1177/0883911520921474.

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The nanocomposite hydrogels were prepared by dispersing of the nanopomegranate seed particles into poly(vinyl alcohol)/poly(acrylic acid) blend matrix in an aqueous medium by the solvent casting method. These hydrogels were characterized using scanning electron microscopy, Fourier transform infrared spectra, differential scanning calorimetry, and optical contact angle instruments. The nanopomegranate seed, blend, and hydrogel nanocomposites were tested for microbial activity. In addition, cytocompatibilities of these blend and hydrogel nanocomposites/composites were tested on human lymphocyte with in vitro MTS cell viability assays. Fourier transform infrared spectra revealed that esterification reaction took place among functional groups in the structure of poly(vinyl alcohol) and poly(acrylic acid). The hydrophilic properties of all hydrogels decreased with increasing nanopomegranate seed content. The mean diameters of the nanopomegranate seed particles were about 88 nm. Nanopomegranate seed particles demonstrated antibacterial properties against gram-positive bacteria, Staphylococcus aureus, and gram-negative bacteria, Escherichia coli. The lymphocyte viabilities increased after addition of nanopomegranate seeds into the polymer blend. The swelling behavior of blend and hydrogels was dependent on the cross-linking density created by the reaction between poly(vinyl alcohol)/poly(acrylic acid) blend and nanopomegranate seed. Scanning electron microscopy images were highly consistent with Fourier transform infrared spectra, differential scanning calorimetry, and antibacterial activity results.

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Asa'di, Sima, Masoud Frounchi, and Susan Dadbin. "Nanomagnetic Poly(vinyl alcohol) Hydrogels." Advanced Materials Research 829 (November 2013): 539–43. http://dx.doi.org/10.4028/www.scientific.net/amr.829.539.

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Surface modified magnetic nanoparticles (M-NPs) were synthetized and stabilized in poly (vinyl-alcohol) solution. The solutions with various magnetic nanoparticles contents were gamma-irradiated and magnetic poly (vinyl-alcohol) (M-PVA) hydrogels were synthesized. The magnetic hydrogels and also the un-irradiated magnetic poly (vinyl alcohol) nanocomposite films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and mechanical measurement. The M-NPs were uniformly dispersed in the polymer matrix due to a strong interaction between the surface-modified M-NPs and polymer matrix. Physical properties of the M-PVA hydrogels, including gel fraction and equilibrium water content were measured to evaluate the applicability of these hydrogels for biomedical applications. XRD, FTIR and VSM results indicated that there are important changes in crystalline, chemical and magnetic properties of hydrogels, arising from irradiation.

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Fujino, Shigeru, and 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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Bai, Lu, Yuan Gao, Shuai Li, and Li Ping Zhang. "Preparation and Characterization of Pol(vinyl Alcohol）/ Cellulose Nanocomposites." Advanced Materials Research 233-235 (May 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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Saleh, Hoda H., Rehab Sokary, and Zakaria I. Ali. "Radiation – induced preparation of polyaniline/poly vinyl alcohol nanocomposites and their properties." Radiochimica Acta 107, no. 8 (July 26, 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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Dissertations / Theses on the topic "(poly)vinyl Alcohol(PVA) Nanocomposite"

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Croot, Robert Arthur. "The characterisation and adsorption of vinyl alcohol vinyl acetate copolymers." Thesis, University of Bristol, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303767.

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Cheng, Zhihan. "MECHANICALLY STRONG/ LOW FLAMMABILITY POLY (VINYL ALCOHOL) AEROGELS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case155266644473611.

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Bernhard, Kathleen C. "Methods to create and characteristics of porous poly(vinyl) alcohol for the purpose of facial implants." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53112.

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Facial implants are becoming more common in America and across the world. In the United States last year, over 260,000 augmentation and reconstruction surgeries were performed on facial cartilage areas, while over two million soft tissue fillers were administered. The current implants on the market, though, are deficient in three major areas: they are too rigid, susceptible to migration, and require a large incision. Alternatively, dermal fillers lack shape and biodegrade too quickly. Poly(vinyl) alcohol (PVA) cryogel is a promising hydrogel alternative due to its softness, durable nature and ease of cast molding. While biocompatible, it does not elicit a fibrous response with firm adhesion and could migrate. The goal of this study is to develop a biodurable implant material that has soft-tissue elasticity, pores for adhesion, and swelling for small incisions. In this research, multiple porosity inducing methods are applied to PVA cryogel. These include a casting PVA cryogel over a porogen then leaching it in a solvent, a gaseous exothermic reaction, creating composites with biodegradable components, as well as using molds to alter the surface texture. Once created, the samples then underwent a series of tests to determine their mechanical properties which include elasticity, tensile strength, elongation, tear strength, pore size, and porosity. Swelling ratio of nonporous PVA cryogel was also considered. Porous PVA cryogel made with a high PVA weight percentage (30%) showed equivalent mechanical properties to that of cartilage. Porous PVA cryogel manufactured with a lower weight percent (10% and 20%) were shown to have similar elastic properties to that of adipose tissue. The surface texture methods, gas method, casting and leaching method, and composites made with CaPO4 and chitosan were all shown to create pores large enough for ingrowth. Samples created with a porosity large enough to encourage ingrowth include the gas method, casting and leaching method, and the CaPO4 composites. The swelling ratio was shown to increase as the weight percentage of PVA in the samples decreased. These quantified characteristics can be used to select the appropriate porous PVA cryogel required for a range of applications including facial implants.

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Spindura, Jillian. "The response of poly (vinyl alcohol) to humidity." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365748.

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Liang, Chun Ying. "Poly(vinyl alcohol) PVA hydrogel characterization as a potential nucleus pulposus replacement candidate." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19277.

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Chronic lower back pain is a clinical manifestation of vertebral disc degeneration. An emerging technique, nucleoplasty, aims to target early stages of disc degeneration. It is envisioned to inject a liquid-state polymer, poly(vinyl alcohol) hydrogels, into the nuclear cavity and allowed to cure in-situ. Two formulations of poly(vinyl alcohol) hydrogels were investigated for its suitability as an injectable polymer. Therefore, its swelling ability, stiffness, required extrusion pressures and temperature dependent curing rates were characterized. Comparable to native nucleus pulposus tissue, the hydrogels swell approximately 10–20 wt% and maintained 1–2.5 MPa stiffness over eight weeks in immersed in phosphate buffer saline. Extrusion pressures highly varied for different hydrogel temperatures and lapsed time. Curing rates for the first hydrogel formulation were slow whereas the second formulation reached within 72 hrs about 70 % of its final cured stiffness. The second hydrogel formulation is a more promising candidate for clinical use.
La lombalgie chronique est la manifestation clinique de la dégénération des disques intervertébraux. La nucleoplastie est une nouvelle technique destinée à traiter la dégénération du disque dans ses premières phases. Le principe consiste à injecter un polymère sous forme liquide, l'hydrogel poly(vinyl alcool), dans le nucléus pulposus, et de le laisser durcir in situ. Deux types d'hydrogels poly(vinyl alcool) ont été étudiés ici pour cette application. La capacité à s'étendre, la rigidité, la pression requise pour l'extrusion et la vitesse de durcissement en fonction de la température ont ainsi été caractérisés pour chacun des deux polymères. Les hydrogels ont des caractéristiques semblables au nucléus pulposus naturel : ils s'étendent de 10 à 20 % en poids et, immergés dans du tampon phosphate salin, maintiennent une rigidité de 1-2.5 MPa pendant 8 semaines. La pression d'extrusion varie significativement avec la température de l'hydrogel et le temps écoulé. La vitesse de durcissement du premier hydrogel était lente, alors que le second atteignait 70 % de sa rigidité finale en moins de 72 heurs. Cette seconde formulation semble plus prometteuse pour des applications cliniques.

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Hsu, Hsingching. "Ultrasonic wave propagation in poly(vinyl alcohol) and articular cartilage." Thesis, Available online, Georgia Institute of Technology, 2005:, 2004. http://etd.gatech.edu/theses/available/etd-06292004-151052/unrestricted/hsu%5Fhsingching%5Fc%5F200407%5Fms.pdf.

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Thesis (M.S.)--School of Mechanical Engineering, Georgia Institute of Technology, 2005. Directed by Marc Levenston.
Marc Levenston, Committee Co-Chair ; Yves Berthelot, Committee Co-Chair ; Robert Guldberg, Committee Member. Includes bibliographical references.

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Chirowodza, Helen. "Synthesis and characterization of cationically and anionically modified poly(vinyl alcohol) microfibrils." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2184.

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Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009.
In papermaking, the addition of filler can be detrimental to the properties of the resulting paper hence the use of additives that enhance paper properties are of paramount importance. Syndiotacticity rich poly(vinyl alcohol) (PVA) microfibrils were prepared for use as filler retention aids. They were prepared via in situ fibrillation during the saponification of high molecular weight poly(vinyl pivalate). The resulting fibers had high thermal stability and crystalline melting temperature. They were not fully soluble in water even at 100 oC. In order to make them less water resistant the syndiotacticity of the PVA microfibrils was varied by copolymerizing vinyl pivalate with vinyl acetate and saponifying the resultant copolymer. It was observed that changes in syndiotacticity had a significant effect on the crystallinity, morphology and thermal properties of the resultant PVA. The surfaces of the fibers were modified by first crosslinking using glyoxal (a dialdehyde), and then attaching cationic and anionic groups by grafting and by carboxymethylation. Crosslinking prior to modification was beneficial in minimizing the solubility of the fibers in the aqueous media in which they were modified. Heterogeneous modification techniques were employed so that fiber properties could be preserved. Carboxymethylation was carried out using the two step Williamson’s ether synthesis. The first step involves the formation of a highly reactive alkoxide by the reaction of PVA with a strong base and the second its etherification using a functional alkyl halide. Poly(methacryloyloxy ethyl trimethyl ammonium chloride) and poly(acrylic acid) were grafted from the PVA microfibrils using the KPS/Na2S2O3 redox initiation system. Grafting was confirmed by FTIR and NMR spectroscopy. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were carried out on both modified and unmodified PVA microfibrils. The results showed that crosslinking resulted in an enhancement of the thermal properties of the microfibrils. A decline in the onset temperature for thermal degradation and crystalline melting temperature were observed, and were attributed to the modification of the PVA microfibrils.

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Rashid, Mohammed R. A. "Image Contrast Enhancement using Poly Vinyl Alcohol Microbubble Response to High MI Ultrasound." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232976.

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The induced rupturing of Poly Vinyl Alcohol (PVA) microbubbles with high mechanical index (MI)ultrasound beam is used in multiple medical application such as drug delivery, image contrastenhancement and perfusion imaging.In this work, Triggered imaging technique with subtraction algorithm is used to enhance themicrobubble’s (MB) contrast over tissue (CTR). The technique is performed by rupturing MBwith one destruction wave sequence followed by 100 B-mode imaging pulse sequences. Theimages obtained are then subtracted by a base image that is selected after the destruction pulse[1].The result of this technique depends mainly on the effectiveness of destruction pulse inrupturing highest number of MB. This has been tested through tissue mimicking phantomwithout replenishing the MB. The evaluation of the methods is done through the CTR and CNRcalculation for each of the 100 frames.The contrast enhancement technique used has also been tested with similar setup but withcontinuous replenishment of MB. The evaluation is done by comparing CNR and CTR results forthe 100 frames obtained by B-mode imaging with the ones resulted from the subtractionalgorithm.The contrast values obtained from both experiments are used in driving the characterization ofPVA response to high MI.The result for the destruction pulse effectiveness shows that the pulse indeed managed toreduce number of MB, but not to the lowest. This is because of leaked gas from cracked shell,the shell acoustic enhancement effect, and large bubbles which managed to survive.The Triggered imaging has shown large improvement in CTR value with use of the subtractionalgorithm when compared to B-mode results. In addition, it has provided an experimental wayfor perfusion imaging and quantification by monitoring CTR value after the destructive pulse[2]. This sets the bases for experimental research relevant to tissue perfusion at ultrasound labof KTH.

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Simões, Maira Martins de Souza Godoy. "Revestimento de stents com filmes de PVA eluidores de S-nitrosoglutationa." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248516.

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Orientador: Marcelo Ganzarolli de Oliveira
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-08T04:10:36Z (GMT). No. of bitstreams: 1 Simoes_MairaMartinsdeSouzaGodoy_M.pdf: 3432819 bytes, checksum: d31e48f8632d109b7dba6dbd370c37f6 (MD5) Previous issue date: 2006
Resumo: Stents são malhas metálicas expansíveis usadas em procedimentos de angioplastia, para a desobstrução das artérias coronárias. Atualmente há um grande interesse na obtenção de stents revestidos com matrizes poliméricas eluidoras de drogas que impeçam a reoclusão da artéria (reestenose). S-nitrosotióis doadores de óxido nítrico (NO) como a S-nitrosoglutationa (GSNO) possuem potencial para a inibição da reestenose. Neste trabalho, placas metálicas e stents foram revestidos com filmes de PVA contendo GSNO (107 µmol/g) através da imersão em soluções de PVA/GSNO com concentrações de PVA de 0,5 a 10,0% m/v. Filmes de PVA/GSNO foram submetidos a ciclos de congelamento/descongelamento (C/D), e analisados em relação ao seu grau de cristalinidade, dissolução, intumescimento, morfologia e propriedades de difusão e eluição da GSNO. Análises por DSC e difração de raios X, mostraram que o grau de cristalinidade do PVA aumenta com o número de ciclos de C/D, e com a secagem por sublimação do filme congelado. O aumento da cristalinidade se reflete em uma diminuição da velocidade de eluição da GSNO para a fase aquosa e da velocidade de dissolução e grau de intumecimento da matriz. Os coeficientes de difusão (D) da GSNO através de filmes de PVA foram medidos utilizando-se uma cela tipo Franz com monitoramento espectrofotométrico. Verificou-se que os valores de D são menores nos filmes secos por sublimação e submetidos a um ciclo de C/D. Este resultado foi atribuído ao aumento da densificação da fase amorfa, obtido na secagem por sublimação. Os filmes secos por esta técnica, apresentaram uma estrutura tridimensional esponjosa constituída por filamentos interligados, revelada por microscopia eletrônica de varredura (MEV). Estimou-se que stents revestidos com PVA/GSNO, a partir de soluções de PVA 0,5 % (m/v) esterilizados com óxido de etileno a 45-55°C podem liberar cerca de 30 µmoles/g de PVA para a parede arterial e levaram à obtenção de revestimentos sem filmes entre as hastes metálicas
Abstract: Stents are expansible wire mesh tubes used in angioplasty procedures in order to widening the luminal diameter of the coronary arteries. There is currently a great interest in the development of stents coated with drug-eluting polymeric matrices, which are able to prevent future closure of artery (restenosis). S-nitrosothiols which are nitric oxide (NO) donors, like S-nitrosoglutathione (GSNO) have potential to inhibit restenosis. In the present work, metallic plates and stents were coated with GSNO (107 µmol/g)- containing PVA films through their immersion in PVA/GSNO solutions with PVA concentration ranging from 0.5 to 10.0% wt/v. PVA/GSNO films were submitted to freezing/thawing cycles (F/T) and analyzed concerning their crystallinity dissolution, swelling, morphology and GSNO diffusion and elution properties. DSC and X Ray diffraction analysis have shown that the PVA crystallinity degree increases with the increase in the number of F/T cycles, and with the drying of the frozen film by sublimation. The increase in cristallinity was reflected in a decrease of the rate of GSNO elution to the aqueous phase, dissolution rate and swelling degree of the matrix. The diffusion coefficients of GSNO through PVA films were measured using a Franz-like cell with spectrophotometric monitoring. It was verified that D values are lower in the films dried by sublimation and submitted to one FT cycle. This result was attributed to the increase in the densification of the amorphous phase obtained in the drying by sublimation. The films dried by this technique, displayed a spongelike three-dimensional structure made by interconnecting filaments, revealed by scanning electron microscopy (SEM). Stents coated with PVA/GSNO, from solution of PVA 0.5 % (wt/v) have avoided the formation of films between the wires of the stent mesh. It was estimated that these stents are able to release ca. 30 µmols/g of PVA to the arterial wall after sterilization with ethylene oxide at 45-55 °C
Mestrado
Físico-Química
Mestre em Química

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Lange, Hanna. "Emulsion polymerization of vinyl acetate with renewable raw materials as protective colloids." Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-41019.

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Emulsion polymerizations of vinyl acetate (VAc) were performed by fully or partially replacing poly(vinyl alcohol) (PVA) with renewable materials as protective colloids or by adding renewable materials, as additives or fillers, to the emulsions during or after polymerization. The purpose of the study was to increase the amount of renewable materials in the emulsion. A total of 19 emulsions were synthesized. Different recipes were used for the synthesis. The following renewable materials were studied; hydroxyethyl cellulose (HEC) with different molecular weights, starch and proteins. HEC and starch were used as protective colloids. Proteins were used as additives or fillers. Cross-linking agent A and Cross-linking agent B were used as cross-linking agents. A total of 26 formulations were pressed, either cold or hot. The synthesized emulsions were evaluated with respect to pH, solids content, viscosity, minimum film formation temperature (MFFT), glass transition temperature (Tg), particle size and molecular weight (Mw). The tensile shear strengths of the emulsions were evaluated according to EN 204 and WATT 91. It was possible to fully, or partially, replace PVA as protective colloid with renewable materials. It was also possible to use renewable materials as additives or fillers in the emulsions. The emulsions obtained properties that differed from the reference. Generally, emulsions with HEC as protective colloid showed lower viscosity and slightly higher MFFT, Tg and molecular weight than emulsions with PVA as protective colloid. Larger particle sizes than the reference were obtained for emulsions containing PVA combined with renewable materials. The emulsion with starch as protective colloid exhibited the largest particle size. 10 formulations passed the criteria for D2. The emulsions where PVA was fully or partially replaced with HEC or starch showed a water resistance similar to the reference (around D2). The addition of protein did not decrease the water and heat resistance compared to the reference. Addition of protein after polymerization increased the water resistance (D2) compared to addition during polymerization. Addition of cross-linking agents did not increase the water resistance further. Two formulations passed the criteria for D3. The emulsion in the first formulation had PVA as protective colloid and protein B was added during polymerization. The emulsion in the second formulation had HEC as protective colloid. To both of these emulsions, protein A was added after polymerization, as a filler, combined with Cross-linking agent B as cross-linking agent before hot pressing. The first formulation also showed a good heat resistance (passed the criteria for WATT 91).

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Books on the topic "(poly)vinyl Alcohol(PVA) Nanocomposite"

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Silvia, Patachia, ed. Poly (vinyl alcohol)(pva)-based polymer membranes. New York: Nova Science Publishers, 2009.

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Silvia, Patachia, ed. Poly (vinyl alcohol)(pva)-based polymer membranes. New York: Nova Science Publishers, 2009.

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Book chapters on the topic "(poly)vinyl Alcohol(PVA) Nanocomposite"

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Satoh, Kotaro. "Poly(vinyl alcohol) (PVA)." In Encyclopedia of Polymeric Nanomaterials, 1–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-36199-9_246-1.

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Satoh, Kotaro. "Poly(vinyl alcohol) (PVA)." In Encyclopedia of Polymeric Nanomaterials, 1734–39. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-642-29648-2_246.

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Xu, Yi, Gang Zhou, Lei Liu, Hongru Liu, Haifeng Liu, Xufeng Niu, and Yubo Fan. "Synthesis and characterization of high-transparent poly (vinyl alcohol) / poly(vinyl pyrrolidone) (PVA/PVP) hydrogels." In IFMBE Proceedings, 67–70. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-29305-4_19.

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Zeeshan, Muhammad Hamad, Umm E. Ruman, Gaohong He, Aneela Sabir, Muhammad Shafiq, and Muhammad Zubair. "“Environmental Issues Concerned with Poly (Vinyl Alcohol) (PVA) in Textile Wastewater”." In Polymer Technology in Dye-containing Wastewater, 225–36. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1516-1_9.

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Mushtaq, Farwa, Muhammad Anwaar Nazeer, Asim Mansha, Muhammad Zahid, Haq Nawaz Bhatti, Zulfiqar Ali Raza, Waleed Yaseen, Ammara Rafique, and Rubab Irshad. "Poly(Vinyl Alcohol) (PVA)-Based Treatment Technologies in the Remediation of Dye-Containing Textile Wastewater." In Polymer Technology in Dye-containing Wastewater, 1–21. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0886-6_1.

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Lee, Heon, Ki Yeon Yang, Sung Hoon Hong, C. D. Schaper, and Gun Young Jung. "Nano-Imprint Lithography of 100nm Sized Patterns Using Water Soluble PVA, Poly(Vinyl Alcohol), Template." In Solid State Phenomena, 661–64. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-30-2.661.

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Sahu, Ganeswar, Bibhu Prasad Sahoo, and Jasaswini Tripathy. "Effect of Graphene Oxide and Temperature on Dielectric Relaxation Behavior of Poly(Vinyl Alcohol)-Based Nanocomposite." In Lecture Notes in Mechanical Engineering, 469–78. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7779-6_41.

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A.H. Alzahrani, Hassan. "CuO and MWCNTs Nanoparticles Filled PVA-PVP Nanocomposites: Morphological, Optical, Dielectric, and Electrical Characteristics." In Carbon Nanotubes - Recent Advances, New Perspectives and Potential Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.105810.

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Copper dioxide (CuO) nanoparticles and multiwall carbon nanotubes (MWCNTs)-filled poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) blend matrix (50/50 wt%)-based polymer nanocomposites (PNCs) have been prepared employing the solution-cast method. The X-ray diffraction explores the semicrystalline morphologies of these PNCs. The FTIR, SEM, and AFM measurements of PNCs expose the development of the miscible mix, polymer-polymer and polymer-nanoparticle interactions, and the influence of CuO and MWCNTs nanofillers on the morphology aspects on the main chain of PVA/PVP blend. The nanofiller loading for x = 14 wt% in the PVA–PVP blend matrix significantly enhances the crystalline phase, diminishing the optical energy gap to 2.31 eV. The DC conductivity is found to be maximum for x = 14 wt% loading concentration. The dielectric and electrical characteristics of these PNCs are investigated for an applied frequency range from 1 kHz to 1 MHz. The dielectric permittivity values increase substantially, owing to the decrease in the nano-confinement phenomenon at low frequency. The rise in applied frequency reduces dielectric permittivity and impedance values and enhances AC electrical conductivity. These PNCs having good dielectric and electrical characteristics can be used as frequency tunable nano-dielectric material in electronic devices.

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"Recent Achievements in the Synthesis of Biosafe Poly(Vinyl Alcohol) Nanocomposite." In Green Polymer Composites Technology, 283–300. Boca Raton : Taylor & Francis Group, CRC Press, 2017.: CRC Press, 2016. http://dx.doi.org/10.1201/9781315371184-24.

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Mousa, Mohanad, and Yu Dong. "A critical role of interphase properties and features on mechanical properties of poly(vinyl alcohol) (PVA) bionanocomposites." In Interfaces in Particle and Fibre Reinforced Composites, 115–36. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-08-102665-6.00005-4.

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Conference papers on the topic "(poly)vinyl Alcohol(PVA) Nanocomposite"

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Choudhary, Shobhna, and R. J. Sengwa. "Anomalous dielectric behaviour of poly(vinyl alcohol)-silicon dioxide (PVA-SiO2) nanocomposites." In INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2015): Proceeding of International Conference on Condensed Matter and Applied Physics. Author(s), 2016. http://dx.doi.org/10.1063/1.4946471.

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Aji, Mahardika Prasetya, Rahmawati, Silvia, Satria Bijaksana, Khairurrijal, Mikrajuddin Abdullah, Mikrajuddin Abdullah, and Khairurrijal. "Electrical Conductivity Study of Polymer Electrolyte Magnetic Nanocomposite Based Poly(Vinyl) Alcohol (PVA) Doping Lithium and Nickel Salt." In THE THIRD NANOSCIENCE AND NANOTECHNOLOGY SYMPOSIUM 2010 (NNSB2010). AIP, 2010. http://dx.doi.org/10.1063/1.3515560.

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Loyola, Bryan R., Valeria La Saponara, and Kenneth J. Loh. "Embedded Piezoresistive Thin Films for Monitoring GFRP Composites." In ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3621.

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The trend towards higher reliance on fiber-reinforced composites for structural components has led to the need to rethink current nondestructive evaluation (NDE) strategies. In principle, embeddable sensor schemes are desired for green-light/red-light structural health monitoring systems that do not negatively affect the properties and performance of the host structure. However, there are still numerous challenges that need to be overcome before these embedded sensing technologies can be realized for real-world structural systems. For example, some of these issues and challenges include the damage detection sensitivity/threshold, reliability of the system, transportability of the system to multiple configurations and different types of structural components, and signal processing/interpretation. The objective of this study is to develop a novel, embedded sensing system that can accurately quantify damage to composites without interfering with structural performance and functionality. In particular, this study will utilize multi-walled carbon nanotube (MWNT)-polyelectrolyte (PE) thin films deposited on a glass fiber substrate for in situ composite structural monitoring. A layer-by-layer (LbL) film fabrication methodology is employed for depositing piezoresistive nanocomposites directly onto glass fiber fabrics, and the resulting film exhibits excellent strain sensing performance, homogeneity, and exhibits no phase segregation. Specifically, the LbL fabrication process will employ polycationic poly(vinyl alcohol) (PVA) and polyanionic poly(sodium 4-styrene sulfonate) (PSS) doped with MWNTs for fabricating the electrically-conductive and piezoresistive thin films. Upon film deposition, the glass fiber substrates are infused with an epoxy matrix via wet-layup to fabricate self-sensing glass fiber-reinforced polymer (GFRP) composite specimens for testing. A frequency-domain approach, based on electrical impedance spectroscopy, is used to characterize the electromechanical response of the GFRP-MWNT-based thin film samples when subjected to complex uni-axial tensile load patterns. A resistor connected to a parallel resistor-capacitor circuit model is proposed for fitting experimental impedance spectroscopic measurements. It has been found that the series resistor models the bulk thin film piezoresistive performance accurately. In addition, these impedance measurements shed light on the glass fiber-thin film interaction electromechanical behavior. Bi-functional strain sensitivity is observed for all GFRP specimens, and the transition point of bilinear strain sensitivity is utilized as a possible metric for GFRP damage detection.

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Cadena-Nogales, Ana, Samara Mishelle Ona, Jose Alvarez Barreto, Marco Leon Dunia, Miguel Angel Mendez, and Daniela Viteri. "Poly(vinyl alcohol) (PVA) in hydrogels, a molecular perspective." In 2019 IEEE Fourth Ecuador Technical Chapters Meeting (ETCM). IEEE, 2019. http://dx.doi.org/10.1109/etcm48019.2019.9014900.

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Avrithi, Kleio, Marlo J. Mecredy, and Leila N. Kelly. "Hydraulic Conductivity of Soil with Poly-Vinyl Alcohol (PVA)." In Geo-Congress 2023. Reston, VA: American Society of Civil Engineers, 2023. http://dx.doi.org/10.1061/9780784484661.035.

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Prabhudesai, S. A., Mathias B. Lawrence, S. Mitra, J. A. E. Desa, and R. Mukhopadhyay. "Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study." In NANOFORUM 2014. AIP Publishing LLC, 2015. http://dx.doi.org/10.1063/1.4917633.

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Jeeju, P. P., S. Jayalekshmi, and K. Chandrasekharan. "Nonlinear optical properties of ZnO/poly (vinyl alcohol) nanocomposite films." In OPTOELECTRONIC MATERIALS AND THIN FILMS: OMTAT 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4862010.

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Nakashima, K., Y. Sawae, and T. Murakami. "Wear Reduction by Functional Protein Boundary Film on Poly(Vinyl Alcohol) Hydrogel." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63623.

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Poly(vinyl alcohol) (PVA) hydrogel is a candidate material for artificial cartilage of joint prostheses. From previous researches [1–4] it is shown that the wear of PVA hydrogel depends on the concentration of proteins in lubricants. Therefore it is considered that the adsorbed film formation by protein of albumin or γ-globulin influences upon the wear grade of PVA hydrogel. The remaining film of proteins on the glass plate was observed in fluorescence microscope. The adsorption condition of albumin and γ-globulin was different. The adsorbed film with effective reduction of the wear showed cooperative stratification of albumin and γ-globulin, but the condition of increased the wear showed separation of albumin and γ-globulin. Consequently, to reduce the wear of PVA hydrogel, cooperative stratification layers are effective.

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Qi, X. Y., C. B. Ma, S. M. L. Nai, C. K. Cheng, H. Zhang, and J. Wei. "Enhanced Mechanical Properties of Poly(Vinyl Alcohol) Nanofibers With Molecular Level Dispersed Graphene." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87246.

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Graphene oxide (GO) was incorporated to poly(vinyl alcohol) (PVA) to form GO/PVA composite nanofiber membranes with reinforced mechanical properties via electrospinning technology. The effect of exfoliated degree of GO and dispersion sate in the PVA polymer matrix on the morphology and mechanical properties of composites is studied, revealing that the functional side groups of GO can improve the dispersion and interfacial bonding between the GO and PVA matrix. In addition, it also demonstrates the GO/PVA nanofiber membranes with the significant enhanced mechanical properties (2.28-fold increase in tensile stress) are obtained at a low GO loading (0.3 wt%). Our strategy provides new opportunities for the PVA composite to be involved in other potential applications.

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Sato, Hideki, Ruri Hidema, Hiroshi Suzuki, and Yoshiyuki Komoda. "A Study on Particle Sedimentation Depression With Poly Vinyl Alcohol and Surfactant." In ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ajkfluids2015-23586.

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The combination structure size in water of poly(vinyl alcohol) (PVA) and drag reducing surfactants has been performed in order to investigate the sedimentation depression effects on latent heat transportation systems found in the previous study. As surfactants, behenyltrimethylammonium chloride with 1.5 molar ratio of counter-ion suppliers, sodium salicylate, was used at the constant surfactant concentration of 2,000 ppm in water, while the concentration of PVA was changed from 0 to 2,000 ppm. The structure size of the combination was measured by a dynamic light scattering (DLS) system. From the results, DLS analysis indicated a large structure is formed by the interaction between PVA and surfactants. It was found that this structure becomes large with PVA concentration and the occupation volume of the structures expands widely in fluid. Thus, it was concluded that this large structure formation causes effective sedimentation depress on particles in latent heat systems.

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