Physically crosslinked poly(vinyl alcohol-hydroxyethyl starch blend hydrogel membranes: Synthesis and characterization for biomedical applications

Directory of Open Access Journals (Sweden)

El-Refaie Kenawy

2014-07-01

Full Text Available Poly(vinyl alcohol, PVA is a polymer of great importance because of its many appealing characteristics specifically for various pharmaceutical and biomedical applications. Physically crosslinked hydrogel membranes composed of different amounts of hydroxyethyl starch (HES in (PVA and ampicillin were prepared by applying freeze–thawing method. This freezing–thawing cycle was repeated for three consecutive cycles. Physicochemical properties of PVA–HES membrane gel such as gel fraction, swelling, morphology, elongation, tensile strength, and protein adsorption were investigated. Introducing HES into freeze–thawed PVA structure affected crystal size distribution of PVA; and hence physicochemical properties and morphological structure have been affected. Increased HES concentration decreased the gel fraction %, maximum strength and break elongation. Indeed it resulted into a significant incrementing of the swelling ability, amount of protein adsorption, broader pore size, and pore distribution of membrane morphological structure. Furthermore, an increase in HES concentration resulted in better and still lower thermal stability compared to virgin PVA and freeze–thawed PVA. The maximum weight loss of PVA–HES hydrogel membranes ranged between 18% and 60% according to HES content, after two days of degradation in phosphate buffer saline (PBS, which indicates they are biodegradable. Thus, PVA–HES hydrogel membranes containing ampicillin could be a novel approach for biomedical application e.g. wound dressing purposes.

Radiation-chemical preparation of poly(vinyl alcohol) hydrogels

International Nuclear Information System (INIS)

Duflot, Anastasia V.; Kitaeva, Natalia K.; Duflot, Vladimir R.

2015-01-01

This work reports the usage of method of radiation-chemical synthesis to prepare cross-linked hydrogels from poly(vinyl alcohol) modified with glycidyl methacrylate. Synthesis kinetics of modified poly(vinyl alcohol) and properties of hydrogels were studied. The gel fraction, swelling, mechanical properties, and water content of the hydrogels were measured. It was found that gel fraction increases with increasing radiation dose, concentration of modified poly(vinyl alcohol), and reaches 60%. It was established by differential scanning calorimetry that a fraction of the “bound” water in hydrogels is 50–70% and independent of gel fraction content. In addition to “bound” and “free” states, water in hydrogels is also present in the intermediate state. - Highlights: • The synthesis and the properties of poly(vinyl alcohol) hydrogels were studied. • PVA was modified by glycidyl methacrylate before gamma cross-linking. • The modification results in decreasing of PVA cross-linking dose by 3 orders lower. • The gel fraction and water content of the hydrogels were measured. • A fraction of the “bound” water in hydrogels is independent of gel fraction content

Lima Bean Starch-Based Hydrogels | Oladebeye | Nigerian Journal ...

African Journals Online (AJOL)

Hydrogels were prepared by crosslinking native lima bean starch and polyvinyl alcohol (PVA) with glutaraldehyde (GA) at varying proportions in an acidic medium. The native starch (N-LBS) and hydrogels (L-GA (low glutaraldehyde) and H-GA (high glutaraldehyde)) were examined for their water absorption capacity (WAC) ...

Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

Science.gov (United States)

Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

2016-07-01

Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

Graft copolymerization of styrene onto poly(vinyl alcohol) initiated by potassium diperiodatocuprate (III)

International Nuclear Information System (INIS)

Bai, L.; Wang, Ch.; Jin, J.; Liu, Y.

2009-01-01

The graft copolymerization of styrene onto poly(vinyl alcohol) is studied by using a novel redox system of potassium diperiodatocuprate-poly(vinyl alcohol) (Cu(III)poly(vinyl alcohol) in alkaline medium. Cu(III)-poly(vinyl alcohol) redox pair is an efficient initiator for this graft copolymerization which is proved by high graft efficiency (>97%) and high percentage of graft (>300%). Reaction conditions (monomer-to-poly(vinyl alcohol) weight ratio, initiator concentration, p H, time and temperature) affect the graft parameters which have been investigated systematically. The optimum reaction conditions are found as St/poly(vinyl alcohol) = 5.4; [Cu(III)] = 1*10 -2 M; p H = 12.7; temperature = 50 d eg C ; time = 3.5 h. Further, the equation of the overall polymerization rate can be written as follows: R p = k C 1.9 (St) C 1.7 (Cu(III)). The overall activation energy was calculated to be 42.0 kJ/mol based on the experimental data of the relations between R p and C(St); R p and C(Cu(III)); and R p and temperature. A mechanism is proposed to explain the formation of radicals and the initiation. The structure of the graft copolymers is confirmed by Fourier transfer infrared spectroscopy. Some peaks were compared with poly(vinyl alcohol) at 3080.34-3001.79 cm -1 (=C-H stretching in the phenyl ring), 1600.34-1450.95 cm -1 (C=C stretching in the phenyl ring), 755.17 cm -1 and 698.64 cm -1 (=C-H out-off-plane bending in phenyl ring) which are considered to belong to the characteristic absorption bands of phenyl group of polystyrene. Therefore it proves that the graft copolymer is composed of poly(vinyl alcohol) and polystyrene. thermal gravimetric analysis thermo grams of poly(vinyl alcohol) and poly(vinyl alcohol)-graft-polystyrene are investigated as well. As it is shown the initial decomposition temperature of poly(vinyl alcohol)-g-polystyrene(377.3 d eg C ) is much higher than that of poly(vinyl alcohol) (241.8 d eg C ), which indicates that the thermal stability of the

Utilisation of sago starch for wound dressing

International Nuclear Information System (INIS)

Kamaruddin Hashim; Khairul Zaman Mohd Dahlan; Kamarudin Bahari

2000-01-01

Sago starch is utilized in Malaysia mainly for the purpose of food production. The purpose of the research is to diversify the use of sago starch for medical application particularly in development of hydrogel wound dressing. The sago starch is blending with water-soluble polymer such as polyvinyl pyrrolidone, polyvinyl alcohol and polyethylene oxide and irradiated with electron beam accelerator to form hydrogel. The parameters such gel strength, elasticity, swelling, gel fraction and tackiness have to be consider for this type of application. We also study the effect of adding additive such as carboxymethyl cellulose and polypropylene glycol into the system to enhance the property of sago starch hydrogel. Works on the use of chitosan in the blend have been performed, in order to prevent microbiological growth such as bacteria and fungi on the hydrogel. (author)

Properties of polyvinyl alcohol/xylan composite films with citric acid.

Science.gov (United States)

Wang, Shuaiyang; Ren, Junli; Li, Weiying; Sun, Runcang; Liu, Shijie

2014-03-15

Composite films of xylan and polyvinyl alcohol were produced with citric acid as a new plasticizer or a cross-linking agent. The effects of citric acid content and polyvinyl alcohol/xylan weight ratio on the mechanical properties, thermal stability, solubility, degree of swelling and water vapor permeability of the composite films were investigated. The intermolecular interactions and morphology of composite films were characterized by FTIR spectroscopy and SEM. The results indicated that polyvinyl alcohol/xylan composite films had good compatibility. With an increase in citric acid content from 10% to 50%, the tensile strength reduced from 35.1 to 11.6 MPa. However, the elongation at break increased sharply from 15.1% to 249.5%. The values of water vapor permeability ranged from 2.35 to 2.95 × 10(-7)g/(mm(2)h). Interactions between xylan and polyvinyl alcohol in the presence of citric acid become stronger, which were caused by hydrogen bond and ester bond formation among the components during film forming. Copyright © 2013. Published by Elsevier Ltd.

Inkjet-printed Polyvinyl Alcohol Multilayers.

Science.gov (United States)

Salaoru, Iulia; Zhou, Zuoxin; Morris, Peter; Gibbons, Gregory J

2017-05-11

Inkjet printing is a modern method for polymer processing, and in this work, we demonstrate that this technology is capable of producing polyvinyl alcohol (PVOH) multilayer structures. A polyvinyl alcohol aqueous solution was formulated. The intrinsic properties of the ink, such as surface tension, viscosity, pH, and time stability, were investigated. The PVOH-based ink was a neutral solution (pH 6.7) with a surface tension of 39.3 mN/m and a viscosity of 7.5 cP. The ink displayed pseudoplastic (non-Newtonian shear thinning) behavior at low shear rates, and overall, it demonstrated good time stability. The wettability of the ink on different substrates was investigated, and glass was identified as the most suitable substrate in this particular case. A proprietary 3D inkjet printer was employed to manufacture polymer multilayer structures. The morphology, surface profile, and thickness uniformity of inkjet-printed multilayers were evaluated via optical microscopy.

Preparation and Characterization of Formalated Polyvinyl Alcohol Hydrogel Film

International Nuclear Information System (INIS)

Than Than Aye; Nyunt Win; San Myint

2011-12-01

A feasible hydrogen film was prepared from polyvinyl alcohol (PVA) sample. The effect of chemical grafting on polyvinyl alcohol film was studied. Polyvinyl alcohol sample was mixed with distilled water and autoclaved at 121C for 60 minutes. An aqueous solution of polyvinyl alcohol was casted into a steel plate and dried for a certain time at room temperature. The obtained PVA film was immersed in formalation bath containing aqueous formaldehyde, sulphuric acid, anhydrous sodium sulphate with a weight ratio of (64:95:300) and 1 liter of distilled water at 60C for various hours. Effect of formalation time was studied varying 6, 12, 24, 36 and 48 hours. Degree of formalation was also evaluated. Physical properties of the hydrogel film such as gel fraction, degree of swelling and mechanical properties such as tensile strength, elongation and hardness were determined before and after formalation of the PVA film. Fourier Transform Infrared Spectroscopic (FTIR) analysis, Thermogravimetric / Differential thermal analysis (DTA / TG) were also studied for characterization. It was found that the appropriate condition for formalation was occured at 24 hours formalation time of with the calculated degree of formalation 65.35% with the determined values (9.04 Mpa) for tensile strength, (241.92%) for elongation, (45.30 Shore D) for hardness, (280.36%) for degree of swelling and (68.32%) for gel fraction.

Polyvinyl alcohol biodegradation under denitrifying conditions

Czech Academy of Sciences Publication Activity Database

Marušincová, H.; Husárová, L.; Růžička, J.; Ingr, M.; Navrátil, Václav; Buňková, L.; Koutný, M.

2013-01-01

Roč. 84, October (2013), s. 21-28 ISSN 0964-8305 Grant - others:GA ČR(CZ) GAP108/10/0200 Institutional support: RVO:61388963 Keywords : polyvinyl alcohol * biodegradation * denitrification * waste-water treatment * anaerobic * Steroidobacter Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.235, year: 2013

Polyvinyl alcohol hydrogels for iontohporesis

Science.gov (United States)

Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali

2013-06-01

Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.

Poly(vinyl alcohol)-heparin hydrogels as sensor catheter membranes

NARCIS (Netherlands)

Brinkman, E.; van der Does, L.; Bantjes, A.

1991-01-01

Poly(vinyl alcohol)-heparin hydrogels with varying water content were synthesized for use as sensor catheter membranes. Films were cast from aqueous mixtures of poly(viny) alcohol) (PVA), a photosensitive cross-linker p-diazonium diphenyl amine polymer (PA), glutaraldehyde (GA) and heparin. After

Rheology and structure of aqueous bentonite–polyvinyl alcohol ...

Indian Academy of Sciences (India)

Keywords. Bentonite–polyvinyl alcohol dispersions; rheology; zeta potential; particle size analysis; SEM; FTIR studies. 1. .... sity and interception of the linear portion of the curve ..... applications for decolourizing or moisture absorption purpose.

Experimental investigations on potassium permanganate doped polyvinyl alcohol - polyvinyl pyrrolidone blend

Science.gov (United States)

Veena, G.; Lobo, Blaise

2018-04-01

Potassium permanganate (KMnO4) doped polyvinyl alcohol (PVA) - polyvinyl pyrrolidone (PVP) blend films were prepared by solution casting technique, in the doping range varying from 0.01 wt % up to 4.70 wt %. The microstructural changes caused by doping, and the modified properties of these films were studied using Atomic Force Microscope (AFM) and temperature dependent direct current (DC) electrical measurements. Temperature variation of electrical resistivity was found to obey Arrhenius relation, from which activation energy was determined. The study was supported by AFM scans, which showed an increase in surface roughness and the presence of spike-like structures, due to interaction of dopant with the polymeric blend. Differential Scanning Calorimetry (DSC) scans revealed two stages of degradation in KMnO4 doped PVA - PVP blend films.

Crystallisation of hydroxyapatite in phosphorylated poly(vinyl alcohol) as a synthetic route to tough mechanical hybrid materials

International Nuclear Information System (INIS)

Kusakabe, Akane; Hirota, Ken; Mizutani, Tadashi

2017-01-01

Partially phosphorylated poly(vinyl alcohol) was prepared by treating poly(vinyl alcohol) with 100% phosphoric acid, and 5, 10 and 20% of the hydroxyl groups were converted to phosphoric acid ester. Addition of Ca 2+ to an aqueous solution of phosphorylated poly(vinyl alcohol) gave a transparent gel. Five cycles of alternate soaking of the gel in aqueous CaCl 2 and aqueous (NH 4 ) 2 HPO 4 were carried out to crystallise hydroxyapatite (HAP) in the phosphorylated poly(vinyl alcohol) matrix. The X-ray diffraction peaks of HAP formed in 5% phosphorylated PVA were sharp, while those of HAP formed in 20% phosphorylated PVA were broad. The contents of inorganic phase in the hybrid powder were increased from 58 to 76 wt% as the fraction of phosphate groups in the gel was decreased from 20% to 5%. The hybrid powder was first subjected to uniaxial pressing, followed by cold isostatic pressing (CIP) and warm isostatic pressing (WIP) at 120 °C at pressures of 300–980 MPa, to obtain the specimens for three-point bending test. These hybrid specimens showed bending strengths of 15–53 MPa. The hybrid compacts prepared from 10% phosphorylated poly(vinyl alcohol) showed the smallest Young's modulus, the largest displacement at break, and the largest fracture energy, showing that it has the highest toughness among the hybrid materials prepared from poly(vinyl alcohol) with varying degrees of phosphorylation. - Graphical abstract: Densification of hydroxyapatite crystallised in 10% phosphorylated poly(vinyl alcohol) gave the toughest compact. - Highlights: • Hydroxyapatite was crystallised in phosphorylated poly(vinyl alcohol) gels. • Crystallite size of hydroxyapatite decreased as phosphate density was increased. • The hybrid specimens prepared in 10% phosphorylated gel was the toughest. • Phosphate density in organic matrix regulated the mechanical properties of the hybrid.

Crystallisation of hydroxyapatite in phosphorylated poly(vinyl alcohol) as a synthetic route to tough mechanical hybrid materials

Energy Technology Data Exchange (ETDEWEB)

Kusakabe, Akane; Hirota, Ken; Mizutani, Tadashi, E-mail: tmizutan@mail.doshisha.ac.jp

2017-01-01

Partially phosphorylated poly(vinyl alcohol) was prepared by treating poly(vinyl alcohol) with 100% phosphoric acid, and 5, 10 and 20% of the hydroxyl groups were converted to phosphoric acid ester. Addition of Ca{sup 2+} to an aqueous solution of phosphorylated poly(vinyl alcohol) gave a transparent gel. Five cycles of alternate soaking of the gel in aqueous CaCl{sub 2} and aqueous (NH{sub 4}){sub 2}HPO{sub 4} were carried out to crystallise hydroxyapatite (HAP) in the phosphorylated poly(vinyl alcohol) matrix. The X-ray diffraction peaks of HAP formed in 5% phosphorylated PVA were sharp, while those of HAP formed in 20% phosphorylated PVA were broad. The contents of inorganic phase in the hybrid powder were increased from 58 to 76 wt% as the fraction of phosphate groups in the gel was decreased from 20% to 5%. The hybrid powder was first subjected to uniaxial pressing, followed by cold isostatic pressing (CIP) and warm isostatic pressing (WIP) at 120 °C at pressures of 300–980 MPa, to obtain the specimens for three-point bending test. These hybrid specimens showed bending strengths of 15–53 MPa. The hybrid compacts prepared from 10% phosphorylated poly(vinyl alcohol) showed the smallest Young's modulus, the largest displacement at break, and the largest fracture energy, showing that it has the highest toughness among the hybrid materials prepared from poly(vinyl alcohol) with varying degrees of phosphorylation. - Graphical abstract: Densification of hydroxyapatite crystallised in 10% phosphorylated poly(vinyl alcohol) gave the toughest compact. - Highlights: • Hydroxyapatite was crystallised in phosphorylated poly(vinyl alcohol) gels. • Crystallite size of hydroxyapatite decreased as phosphate density was increased. • The hybrid specimens prepared in 10% phosphorylated gel was the toughest. • Phosphate density in organic matrix regulated the mechanical properties of the hybrid.

76 FR 13660 - Polyvinyl Alcohol From Taiwan

Science.gov (United States)

2011-03-14

... Taiwan Determination On the basis of the record \\1\\ developed in the subject investigation, the United... Act of 1930 (19 U.S.C. 1673d(b)) (the Act), that an industry in the United States is materially injured by reason of imports from Taiwan of polyvinyl alcohol, provided for under subheading 3905.30.00 of...

Ultraviolet sensing properties of polyvinyl alcohol-coated aluminium ...

Indian Academy of Sciences (India)

Undoped and aluminium (Al)-doped zinc oxide (ZnO) nanorods have been synthesized by electrochemical route. The synthesized materials have been characterized by X-ray diffraction, UV–visible spectrometer and scanning electron microscope. The Al-doped ZnO nanorods have been coated with polyvinyl alcohol.

Stability of polyvinyl alcohol-coated biochar nanoparticles in brine

Energy Technology Data Exchange (ETDEWEB)

Griffith, Christopher, E-mail: cgriffith@utexas.edu; Daigle, Hugh [University of Texas at Austin, Department of Petroleum and Geosystems Engineering (United States)

2017-01-15

This paper reports on the dispersion stability of 150 nm polyvinyl alcohol coated biochar nanoparticles in brine water. Biochar is a renewable, carbon based material that is of significant interest for enhanced oil recovery operations primarily due to its wide ranging surface properties, low cost of synthesis, and low environmental toxicity. Nanoparticles used as stabilizing agents for foams (and emulsions) or in nanofluids have emerged as potential alternatives to surfactants for subsurface applications due to their improved stability at reservoir conditions. If, however, the particles are not properly designed, they are susceptible to aggregation because of the high salinity brines typical of oil and gas reservoirs. Attachment of polymers to the nanoparticle surface, through covalent bonds, provides steric stabilization, and is a necessary step. Our results show that as the graft density of polyvinyl alcohol increases, so too does the stability of nanoparticles in brine solutions. A maximum of 34 wt% of 50,000 Da polyvinyl alcohol was grafted to the particle surface, and the size of the particles was reduced from ~3500 nm (no coating) to 350 nm in brine. After 24 h, the particles had a size of ~500 nm, and after 48 h completely aggregated. 100,000 Da PVA coated at 24 wt% on the biochar particles were stable in brine for over 1 month with no change in mean particle size of ~330 nm.

75 FR 15726 - Polyvinyl Alcohol From Taiwan; Determination

Science.gov (United States)

2010-03-30

... an industry in the United States is materially injured by reason of imports from Taiwan of polyvinyl.... industry was materially injured or threatened with material injury by reason of imports of PVA from Taiwan... Alcohol From Taiwan; Determination On the basis of the record \\1\\ developed in the subject investigation...

Chemical modification of poly(vinyl alcohol): evaluation of hydrophilic/lipophilic balance

International Nuclear Information System (INIS)

Aranha, Isabele B.; Lucas, Elizabete F.

2001-01-01

Poly(vinyl alcohol) terpolymers have been obtained by reaction of partially hydrolized poly(vinyl alcohol) with different acid chlorides. The objective is the preparation of polymers with slight differences in their hydrophilic/lipophilic balance and in the interfacial activities of their solutions. The chemical modifications were characterized by means of 1 H NMR and the polymer properties were evaluated in terms of changes in solubility and surface tension. By chemical modification, polymers with low percentage of hydrophobic group were obtained. The water-soluble polymers obtained did not have the surface tension of their solutions altered. The solubility of the modified polymers decreased markedly, even with low contents of hydrophobic groups. (author)

Process for the production of starch and alcohol from substances containing starch

Energy Technology Data Exchange (ETDEWEB)

Smith, N B; McFate, H A; Eubanks, E M

1969-01-01

Almost complete extraction of starch from wheat, rice, maize, etc., is achieved more economically then by conventional processes. Starch-containing cereal is soaked, the magma is broken and the seed removed. The magma is then drained and separated into a liquid filtrate consisting of starch, gluten and fine fibers, and a solid residue made up of coarse fibers, husks and grit. The liquid filtrate is sieved to remove the fine fibers, and then centrifuged to obtain pure, gluten-free starch. The solid residue is treated with a mineral acid in a converter to give sugar, thus forming a material which is fermented and distilled to give alcohol.

Surface Properties of a Novel Poly(vinyl alcohol Film Prepared by Heterogeneous Saponification of Poly(vinyl acetate Film

Directory of Open Access Journals (Sweden)

Seong Baek Yang

2017-10-01

Full Text Available Almost general poly(vinyl alcohol (PVA films were prepared by the processing of a PVA solution. For the first time, a novel poly(vinyl alcohol (PVA film was prepared by the saponification of a poly(vinyl acetate (PVAc film in a heterogenous medium. Under the same saponification conditions, the influence of saponification time on the degree of saponification (DS was studied for the preparation of the saponified PVA film, and it was found that the DS varied with time. Optical microscopy was used to confirm the characteristics and surface morphology of the saponified PVA film, revealing unusual black globules in the film structure. The contact angle of the films was measured to study the surface properties, and the results showed that the saponified PVA film had a higher contact angle than the general PVA film. To confirm the transformation of the PVAc film to the PVA film, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction measurements, differential scanning calorimetry, and Fourier-transform infrared spectroscopy were employed.

Polyvinyl alcohol/chitosan/montmorillonite nanocomposites preparation by freeze/thaw cycles and characterization

Directory of Open Access Journals (Sweden)

Părpăriţă Elena

2014-12-01

Full Text Available Polyvinyl alcohol (PVA and chitosan (CS based hydrogels are often chosen to obtain hydrogels as being considered non-toxic for human body. The present study aims the preparation and physical chemical characterisation of hydrogels based PVA and CS by using an environmental friendly method i.e. freeze/thaw. In this method the only parameters affecting the hydrogels’ properties is the PVA concentration in solution, time and number of cycles of freezing / thawing. Repeated freezing and thawing cycles resulted in production of a highly elastic polyvinyl alcohol hydrogel with higher degree of crystallization. Adding chitosan in polyvinyl alcohol hydrogel is giving to the newly formed material, biocompatibility and antibacterial properties due to the free amino groups of chitosan. Higher mechanical and thermal characteristics of PVA/CS based hydrogels were obtained by addition of a small amount of inorganic nanoparticles (montmorillonite clay, C30B into the matrix (i.e. 1%. Scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, near-infrared chemical imaging spectroscopy (NI-CI, X-ray diffraction (XRD, thermogravimetric analysis (TG, swelling and rheological measurements were used to characterize the polyvinyl alcohol/chitosan/montmorillonite properties. The swelling degree increased with decreasing chitosan content in hydrogels and the variation is opposite in nanocomposites, decreasing after introducing the nanoclay. The swelling behaviour was influenced by the presence of the nanoparticles. The plasticizer effect of the nanoparticles was reflected by obtaining a more compact hydrogel network with higher mechanical and thermal properties. The proposed materials can be a promising alternative in biomedical applications

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

NARCIS (Netherlands)

Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang

2011-01-01

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

NARCIS (Netherlands)

Xia, W.; Piras, D.; Heijblom, M.; Steenbergen, Wiendelt; van Leeuwen, Ton; Manohar, Srirang

2011-01-01

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F–T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where

Pervaporation of alcohol-toluene mixtures through polymer blend membranes of poly(acrylic acid) and poly(vinyl alcohol)

NARCIS (Netherlands)

Park, H.C.; Park, H.; Meertens, R.M.; Meertens, R.M.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

1994-01-01

Homogeneous membranes were prepared by blending poly(acrylic acid) with poly(vinyl alcohol). These blend membranes were evaluated for the selective separation of alcohols from toluene by pervaporation. The flux and selectivity of the membranes were determined both as a function of the blend

Rheology and structure of aqueous bentonite–polyvinyl alcohol ...

Indian Academy of Sciences (India)

Abstract. The influence of polymer on flow behaviour of Balikesir, Turkey bentonite dispersions (2%, w/w) was studied for non-ionic polymer, polyvinyl alcohol (PVA). In a range of 3⋅3 × 10–6 – 3⋅3 × 105 mol/l, PVA was added to the bentonite dispersions in different concentrations and its behaviour was observed on ...

Moisture sorption characteristics of extrusion-cooked starch protective loose-fill cushioning foams

Science.gov (United States)

Combrzyński, Maciej; Mościcki, Leszek; Kwaśniewska, Anita; Oniszczuk, Tomasz; Wójtowicz, Agnieszka; Sołowiej, Bartosz; Gładyszewska, Bożena; Muszyński, Siemowit

2017-10-01

The aim of this work was to determine the water vapour sorption properties of thermoplastic starch filling foams processed by extrusion-cooking technique from various combinations of potato starch and two foaming agents: poly(vinyl) alcohol and Plastronfoam, in amount of 1, 2 and 3% each. Foams were processed with the single screw extruder-cooker at two different screw rotational speeds 100 and 130 r.p.m. The sorption isotherms of samples were determined and described using the Guggenheim-Anderson-de Boer model. Also, the kinetics of water vapour adsorption by foams, as a function of time, was measured and fitted with Peleg model. On the basis of the analysis the influence of the applied foaming agents, as well as the technological parameters of extrusion-cooking process in relation to water vapour adsorption by thermoplastic starch foams was demonstrated. There was no difference between the shapes of the isotherms for poly(vinyl) alcohol foams while for Plastronfoam foams a notable difference among foams extruded at 100 r.p.m. was observed in the regions of low and high humidity content. The analysis of the Guggenheim-Anderson-de Boer model parameters showed that the water molecules were less strongly bound with the foam surface when extruded at a lower screw speed.

The Effects of Reaction Variables on Solution Polymerization of Vinyl Acetate and Molecular Weight of Poly(vinyl alcohol Using Taguchi Experimental Design

Directory of Open Access Journals (Sweden)

M.H. Navarchian

2009-12-01

Full Text Available Poly(vinyl acetate is synthesized via solution polymerization, and then it is converted to poly(vinyl alcohol by alkaline alcoholysis. The aim of the work study was to investigate statistically the  influence of reaction variables in vinyl acetate polymerization, the conversion of this monomer to polymer, degree of branching of acetyl group in poly(vinyl acetate, as well as the molecular weight of poly(vinyl alcohol, using Taguchi experimental design approach. The reaction variables were polymerization time, molar ratio of initiator to monomer, and volume ratio of monomer to solvent. The statistical analysis of variance of the results revealed that all factors have significantly influenced the conversion and degree of branching. Volume ratio of monomer to solvent is the only factor affecting the molecular weight of poly(vinyl alcohol, and has the greatest influence on all responses. By increasing this ratio, the conversion, degree of branching of acetyl group in poly(vinyl acetate, and molecular weight of poly(vinyl alcohol were increased.

Investigation of Electrospun Poly Vinyl Alcohol Fibers Towards the Development of Manufacturable Wound Dressings

Science.gov (United States)

Vora, Asad

Polymers such as polyvinyl alcohol, chitosan, and starch have excellent bio-compatible and bio-degradable properties. Their applications in drug delivery, wound dressings, artificial cartilage materials have increased dramatically due to their much sought-after renewable and biological properties. Hence, polyvinyl alcohol has been chosen for this study to test the feasibility of polyvinyl alcohol nanofibers towards the manufacturable wound dressings. Polyvinyl alcohol nanofibers are prepared via electrospinning technique, where different wt% polyvinyl alcohol solutions are prepared. The fibers were optimized by varying important electrospninning parameters which include voltage applied, the collector-needle distance and flow rate. Morphology and structure of the electrospun fibers are analysed using scanning electron microscopy and fourier transform infrared respectively. The diameter of fibers obtained was found to be in the range of 100 nm-160 nm. Thermal stability was examined using DSC and TGA characterization technique and fibers are found to be stable up to 220oC. Finally, each weight sample of PVA fibers are analysed by goniometer for wettability and is found to be hydrophilic.

Patterned cell arrays and patterned co-cultures on polydopamine-modified poly(vinyl alcohol) hydrogels

International Nuclear Information System (INIS)

Beckwith, Kai M; Sikorski, Pawel

2013-01-01

Live cell arrays are an emerging tool that expand traditional 2D in vitro cell culture, increasing experimental precision and throughput. A patterned cell system was developed by combining the cell-repellent properties of polyvinyl alcohol hydrogels with the cell adhesive properties of self-assembled films of dopamine (polydopamine). It was shown that polydopamine could be patterned onto spin-cast polyvinyl alcohol hydrogels by microcontact printing, which in turn effectively patterned the growth of several cell types (HeLa, human embryonic kidney, human umbilical vein endothelial cells (HUVEC) and prostate cancer). The cells could be patterned in geometries down to single-cell confinement, and it was demonstrated that cell patterns could be maintained for at least 3 weeks. Furthermore, polydopamine could be used to modify poly(vinyl alcohol) in situ using a cell-compatible deposition buffer (1 mg mL −1 dopamine in 25 mM tris with a physiological salt balance). The treatment switched the PVA hydrogel from cell repellent to cell adhesive. Finally, by combining microcontact printing and in situ deposition of polydopamine, patterned co-cultures of the same cell type (HeLa/HeLa) and dissimilar cell types (HeLa/HUVEC) were realized through simple chemistry and could be studied over time. The combination of polyvinyl alcohol and polydopamine was shown to be an attractive route to versatile, patterned cell culture experiments with minimal infrastructure requirements and low complexity. (paper)

Crosslinked poly(vinyl alcohol hydrogels for wound dressing applications: A review of remarkably blended polymers

Directory of Open Access Journals (Sweden)

Elbadawy A. Kamoun

2015-01-01

Full Text Available A series of excellent poly(vinyl alcohol (PVA/polymers blend hydrogel were reviewed using different crosslinking types to obtain proper polymeric dressing materials, which have satisfied biocompatibility and sufficient mechanical properties. The importance of biodegradable–biocompatible synthetic polymers such as PVA, natural polymers such as alginate, starch, and chitosan or their derivatives has grown significantly over the last two decades due to their renewable and desirable biological properties. The properties of these polymers for pharmaceutical and biomedical application needs have attracted much attention. Thus, a considered proportion of the population need those polymeric medical applications for drug delivery, wound dressing, artificial cartilage materials, and other medical purposes, where the pressure on alternative polymeric devices in all countries became substantial. The review explores different polymers which have been blended previously in the literature with PVA as wound dressing blended with other polymeric materials, showing the feasibility, property change, and purpose which are behind the blending process with PVA.

Characterization of nanocellulose reinforced semi-interpenetrating polymer network of poly(vinyl alcohol) & polyacrylamide composite films.

Science.gov (United States)

Mandal, Arup; Chakrabarty, Debabrata

2015-12-10

Semi-interpenetrating polymer network (semi-IPN) of poly(vinyl alcohol)/polyacrylamide was reinforced with various doses of nanocellulose. The different composite films thus prepared were characterized with respect to their mechanical, thermal, morphological and barrier properties. The composite film containing 5 wt.% of nanocellulose showed the highest tensile strength. The semi-interpenetrating polymer network of poly(vinyl alcohol)/polyacrylamide; and its various composites with nanocellulose were almost identical in their thermal stability. Each of the composites however exhibited much superior stability with respect to the linear poly(vinyl alcohol) and crosslinked polyacrylamide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited phase separated morphology where agglomerates of nanocellulose were found to be dispersed in the matrix of the semi-IPN. The moisture vapor transmission rate (MVTR) was the lowest for the film containing 5 wt.% of nanocellulose. Copyright © 2015 Elsevier Ltd. All rights reserved.

Radiation crosslinking of starch/water-soluble polymer blends for hydrogel

International Nuclear Information System (INIS)

Hashim, K.; Mohid, N.; Bahari, K.; Dahlan, K.Z.

2000-01-01

Water-soluble polymers such as PVP(polyvinyl pyrrolidone) and PVA(polyvinyl alcohol), in aqueous solution can form hydrogel easily upon gamma or electron beam irradiation. The properties of hydrogels, particularly for wound dressing application, can be further improved by adding sago starch to the blend. Results show improved gel strength and elongation properties of the hydrogel with increasing sago concentration. It was found that the PVA/sago hydrogel gives better gel strength and elongation than the PVP/sago hydrogel. The tackiness property of the PVA/sago hydrogel increased with increase amount of sago starch added. In case of PVP/sago hydrogel, the tackiness property shows significant increase with increasing amount of sago except for the 5%PVP composition. The swelling properties of PVP/sago and PVA/sago hydrogel decreased with increasing amount of sago but the crosslink density of the hydrogels also reduced. (author)

Radiation crosslinking of starch/water-soluble polymer blends for hydrogel

Energy Technology Data Exchange (ETDEWEB)

Hashim, K.; Mohid, N.; Bahari, K.; Dahlan, K.Z. [Radiation Processing Technology Division, Malaysian Institute Nuclear Technology Research Malaysia (MINT), Bangi, 43000 Kajang (Malaysia)

2000-03-01

Water-soluble polymers such as PVP(polyvinyl pyrrolidone) and PVA(polyvinyl alcohol), in aqueous solution can form hydrogel easily upon gamma or electron beam irradiation. The properties of hydrogels, particularly for wound dressing application, can be further improved by adding sago starch to the blend. Results show improved gel strength and elongation properties of the hydrogel with increasing sago concentration. It was found that the PVA/sago hydrogel gives better gel strength and elongation than the PVP/sago hydrogel. The tackiness property of the PVA/sago hydrogel increased with increase amount of sago starch added. In case of PVP/sago hydrogel, the tackiness property shows significant increase with increasing amount of sago except for the 5%PVP composition. The swelling properties of PVP/sago and PVA/sago hydrogel decreased with increasing amount of sago but the crosslink density of the hydrogels also reduced. (author)

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride).

Science.gov (United States)

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2013-01-02

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively.

Preparation of CuS nanoparticles embedded in poly(vinyl alcohol ...

Indian Academy of Sciences (India)

WINTEC

ray diffraction (XRD) analyses and electron diffraction pattern also revealed the forming of CuS crystal structure in the PVA fibres. Keywords. CuS nanoparticles; electrospinning; poly(vinyl alcohol). 1. Introduction. In the past decade, the preparation of low-dimensional semiconductor nanostructures has become a hotspot of.

Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

International Nuclear Information System (INIS)

Debiagi, Flavia; Matsuda, Daniel K.M.; Marengo, Vitor A.; Vercelheze, Ana Elisa S.; Mali, Suzana

2011-01-01

The objectives of this work were to produce biodegradable trays based on cassava starch (native or modified by acid), sugarcane fibers and nano clay (sodium montmorillonite) and also to characterize the produced trays according to their density, tensile strength, X-ray diffraction and biodegradability. The trays were obtained by thermoforming into a hydraulic press coupled to a Teflon mold (18 x 23 cm) at 130 degree C/ 20 min and 100 bars of pressure. The peak related to the nano clay (2 = 7.1 o ) were not observed in XRD patterns of the trays, suggesting the formation of an exfoliated structure in the nano composite. The addition of modified starch increased tensile strength and density of the samples, and the addition of fibers and nano clays decreased the tensile strength of native and modified starch trays. The weight loss of trays was not affected by the starch type, however the addition of fibers increased the biodegradation and the addition of nano clays decreased. (author)

Preparation of CuS nanoparticles embedded in poly(vinyl alcohol)

Indian Academy of Sciences (India)

Poly(vinyl alcohol) (PVA)/CuS composite nanofibres were successfully prepared by electrospinning technique and gas–solid reaction. Scanning electron microscopic (SEM) images showed that the average diameter of PVA/CuS fibres was about 150–200 nm. Transmission electron microscopy (TEM) proved that a majority ...

Insulating characteristics of polyvinyl alcohol for integrated electronics

International Nuclear Information System (INIS)

Van Etten, Eliana A.; Ximenes, Eder S.; Tarasconi, Lucas T.; Garcia, Irene T.S.; Forte, Maria M.C.; Boudinov, Henri

2014-01-01

The aim of this work is to evaluate the effects of molecular weight, hydrolysis degree, and cross-link on the performance of Polyvinyl Alcohol (PVA) when applied as dielectric material in organic field effect transistors. For this purpose, metal–insulator-structures and polymeric films were characterized. The polymer structure was analyzed by thermogravimetry and calorimetry, and the electrical characterization of the films was performed through current–voltage and capacitance–voltage curves; and dielectric spectrometry. Cross-linkage, followed by hydrolysis degree, presented the major impact on polymer properties, due to the strong influence on chain mobility. The chain mobility increases the dielectric response and decreases the insulation capacity, generating the need to compromise between these two properties. The largest drawback encountered was the high sensitivity of the films to ambient humidity. The best performance of the organic insulator was obtained from cross-linked films made of an incompletely hydrolyzed PVA. - Highlights: • Effect of molecular weight, hydrolysis and cross-link on polyvinyl alcohol (PVA) dielectric • Cross-linkage, followed by hydrolysis, showed the major impact on properties. • Cross-linkage followed by hydrolysis showed the strongest effect on chain mobility. • Best dielectric performance: cross-linked films made of incompletely hydrolyzed PVA • Largest drawback is the high sensitivity of the films to ambient humidity

Effect of PVA and PDE on selected structural characteristics of extrusion-cooked starch foams

Directory of Open Access Journals (Sweden)

Maciej Combrzyński

2018-03-01

Full Text Available Abstract The aim of this work was to determine selected physical properties of biodegradable thermoplastic starch (TPS filling foams manufactured by extrusion-cooking technique from different combinations of potato starch and two additives: poly(vinyl alcohol PVA and Plastronfoam PDE. Foams were processed with seven starch/additives combinations at two different extruder-cooker’s screw rotational speeds. The densities of starch foams depended significantly on the additive type and content. The linear relationship between the Young modulus and the ultimate compression force and apparent density was found. The foams processed with the addition of PVA had low density, porosity and lower values of the Young modulus than the foams prepared with PDE.

The influence of miscibility and micro - structure on the surface defects of some starch bio – hybrides

Czech Academy of Sciences Publication Activity Database

Dimonie, D.; Kelnar, Ivan; Socoteanu, R.; Darie, R. N.; Pop, F. S.; Zaharia, C.; Petrea, C.; Nemteanu, M.; Coserea, R. M.

2010-01-01

Roč. 47, č. 4 (2010), s. 486-491 ISSN 0025-5289 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyvinyl alcohol * starch * multilayered silicate Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.873, year: 2008 http://www.revmaterialeplastice.ro/pdf/DIMONIE%20D.pdf%204%2010.pdf

Cellulose-glycerol-polyvinyl alcohol composite films for food packaging: Evaluation of water adsorption, mechanical properties, light-barrier properties and transparency.

Science.gov (United States)

Cazón, Patricia; Vázquez, Manuel; Velazquez, Gonzalo

2018-09-01

Nowadays consumers are aware of environmental problems. As an alternative to petrochemical polymers for food packaging, researchers have been focused on biopolymeric materials as raw material. The aim of this study was to evaluate mechanical properties (toughness, burst strength and distance to burst), water adsorption, light-barrier properties and transparency of composite films based on cellulose, glycerol and polyvinyl alcohol. Scanning electron microscopy, spectral analysis (FT-IR and UV-VIS-NIR) and differential scanning calorimetry were performed to explain the morphology, structural and thermal properties of the films. Results showed that polyvinyl alcohol enhances the toughness of films up to 44.30 MJ/m 3 . However, toughness decreases when glycerol concentration is increased (from 23.41 to 10.55 MJ/m 3 ). Water adsorption increased with increasing polyvinyl alcohol concentration up to 222%. Polyvinyl alcohol increased the film thickness. The films showed higher burst strength (up to 12014 g) than other biodegradable films. The films obtained have optimal values of transparency like those values of synthetic polymers. Glycerol produced a UV protective effect in the films, an important effect for food packaging to prevent lipid oxidative deterioration. Results showed that it is feasible to obtain cellulose-glycerol-polyvinyl alcohol composite films with improved properties. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oxidation and Destruction of Polyvinyl Alcohol under the Combined Action of Ozone-Oxygen Mixture and Hydrogen Peroxide

Science.gov (United States)

Zimin, Yu. S.; Kutlugil'dina, G. G.; Mustafin, A. G.

2018-03-01

The oxidative transformations of a polyvinyl alcohol in aqueous solutions are studied under the simultaneous action of the two oxidizing agents, an ozone-oxygen mixture and a hydrogen peroxide. Effective parameters a and b, which characterize the first and second channels of carboxyl group accumulation, respectively, grow linearly upon an increase in the initial concentration of H2O2. After the temperature dependence of a and b parameters (331-363 K) in a PVA + O3 + O2 + H2O2 + H2O reaction system is studied, the parameters of the activation of COOH group accumulation are found (where PVA is a polyvinyl alcohol). New data on the effect process conditions (length of oxidation, temperature, and hydrogen peroxide concentration) have on the degree of destructive transformations of polyvinyl alcohol in the investigated reaction system are obtained.

Contribution of Charges in Polyvinyl Alcohol Networks to Marine Antifouling.

Science.gov (United States)

Yang, Wufang; Lin, Peng; Cheng, Daocang; Zhang, Longzhou; Wu, Yang; Liu, Yupeng; Pei, Xiaowei; Zhou, Feng

2017-05-31

Semi-interpenetrated polyvinyl alcohol polymer networks (SIPNs) were prepared by integrating various charged components into polyvinyl alcohol polymer. Contact angle measurement, attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and tensile tests were used to characterize the physicochemical properties of the prepared SIPNs. To investigate the contribution of charges to marine antifouling, the adhesion behaviors of green algae Dunaliella tertiolecta and diatoms Navicula sp. in the laboratory and of the actual marine animals in field test were studied for biofouling assays. The results suggest that less algae accumulation densities are observed for neutral-, anionic-, and zwitterionic-component-integrated SIPNs. However, for the cationic SIPNs, despite the hydration shell induced by the ion-dipole interaction, the resistance to biofouling largely depends on the amount of cationic component because of the possible favorable electrostatic attraction between the cationic groups in SIPNs and the negatively charged algae. Considering that the preparation of novel nontoxic antifouling coating is a long-standing and cosmopolitan industrial challenge, the SIPNs may provide a useful reference for marine antifouling and some other relevant fields.

The use of filter paper plasticized with polyvinyl alcohol-glutaraldehyde in ELISA

Directory of Open Access Journals (Sweden)

G.H.T.S. Barbosa

2000-07-01

Full Text Available F1-antigen purified from Yersinia pestis was covalently linked to 5-mm diameter filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde. These discs were used both for ELISA and dot-ELISA for the detection of anti-F1 IgG in rabbits. The best conditions were achieved using 1.25 µg of F1 antigen/disc, 3% w/v skim milk in PBS as blocking agent, anti-IgG peroxidase conjugate diluted 12,000 times, and serum from rabbits immunized or not against Y. pestis, diluted 6,400 times. The absorbance values obtained from the comparative study between this procedure and conventional ELISA were not significantly different but the low cost of the reagents employed in ELISA using the filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde makes this method economically attractive.

Oxidative Mineralization and Characterization of Polyvinyl Alcohol Solutions for Wastewater Treatment

Energy Technology Data Exchange (ETDEWEB)

Oji, L.N.

1999-08-31

The principal objectives of this study are to identify an appropriate polyvinyl alcohol (PVA) oxidative mineralization technique, perform compatibility and evaporation fate tests for neat and mineralized PVA, and determine potential for PVA chemical interferences which may affect ion exchange utilization for radioactive wastewater processing in the nuclear industry.

Comparison of polyvinyl alcohol- and formalin-preserved fecal specimens in the formalin-ether sedimentation technique for parasitological examination.

OpenAIRE

Carroll, M J; Cook, J; Turner, J A

1983-01-01

A total of 965 paired fecal specimens preserved in polyvinyl alcohol fixative and Formalin were processed by the Formalin-ether sedimentation technique. The effectiveness of the concentration procedures with material from each preservative was determined by comparing both diagnostic efficiency (percent identified) and quantitative egg and semiquantitative cyst counts. Of the 319 infections, 69.5% were detected in concentrates from both preservatives, 6.9% from polyvinyl alcohol only, and 23.5...

Properties and Applications of Polyvinyl Alcohol, Halloysite Nanotubes and Their Nanocomposites.

Science.gov (United States)

Gaaz, Tayser Sumer; Sulong, Abu Bakar; Akhtar, Majid Niaz; Kadhum, Abdul Amir H; Mohamad, Abu Bakar; Al-Amiery, Ahmed A

2015-12-19

The aim of this review was to analyze/investigate the synthesis, properties, and applications of polyvinyl alcohol-halloysite nanotubes (PVA-HNT), and their nanocomposites. Different polymers with versatile properties are attractive because of their introduction and potential uses in many fields. Synthetic polymers, such as PVA, natural polymers like alginate, starch, chitosan, or any material with these components have prominent status as important and degradable materials with biocompatibility properties. These materials have been developed in the 1980s and are remarkable because of their recyclability and consideration of the natural continuation of their physical and chemical properties. The fabrication of PVA-HNT nanocomposites can be a potential way to address some of PVA's limitations. Such nanocomposites have excellent mechanical properties and thermal stability. PVA-HNT nanocomposites have been reported earlier, but without proper HNT individualization and PVA modifications. The properties of PVA-HNT for medicinal and biomedical use are attracting an increasing amount of attention for medical applications, such as wound dressings, drug delivery, targeted-tissue transportation systems, and soft biomaterial implants. The demand for alternative polymeric medical devices has also increased substantially around the world. This paper reviews individualized HNT addition along with crosslinking of PVA for various biomedical applications that have been previously reported in literature, thereby showing the attainability, modification of characteristics, and goals underlying the blending process with PVA.

Synthesis of MoO 3 and its polyvinyl alcohol nanostructured film

Indian Academy of Sciences (India)

The solvent casting method is adopted for the synthesis of MoO3 dispersed polyvinyl alcohol nanostructured film (MoO3–PVA). These synthesized MoO3 and their composite samples are characterized for their structure, morphology, bonding and thermal behaviour by XRD, SEM, IR and DSC techniques, respectively.

Phase relations and physicochemical properties of the ammonium paratungstate - polyvinyl alcohol - water system

International Nuclear Information System (INIS)

Ostroushko, A.A.; Mikhalev, D.S.

2003-01-01

Phase relations were studied in the ammonium paratungstate - polyvinyl alcohol - water system, isothermal cross section of the phase diagram was obtained at room temperature. Visual and microscopic observations, as well as instrumental methods were used for the detection of lines of the homogeneous polymer-salt solutions existence. Concentration ratios of density of solutions, their dynamic viscosity and refractive index were studied. Area of polymer based solutions, area of salt crystallization, heterogeneous fields with two or three phases were separated. As compared with the ammonium heptamolybdate - polyvinyl alcohol - water system the increase of solubility of components under day lighting and ultraviolet radiation escaped detection. The studied system is provided properties indicative of the formation of mesomorphic phase, photochemical reduction of ions of d-metals for the occurrence of this phase is not requirement [ru

Studi Electrochemical Impedance Spectroscopy dari Lembaran Polyvinyl Alcohol dengan Penambahan Liclo4 sebagai Bahan Elektolit Baterai Li-ion

OpenAIRE

Gunawan, Indra; Wahyudianingsih, Wahyudianingsih; Sudaryanto, Sudaryanto

2016-01-01

ELECTROCHEMICALIMPEDANCE SPECTROSCOPY STUDY OF POLYVINYL ALCOHOL SHEETWITHADDITION OFLiClO4AS ELECTROLYTE MATERIAL OF Li-ION BATTERAY. Solid polymer electrolyte materials for Li ion battery have been prepared using polyvinyl alcohol (PVA) added by lithium perchlorate (LiClO4) salt with various concentration. Electrochemical Impedance Spectroscopy (EIS) study of the material was done by making a Nyquist plot of the measurement with a LCR meter. These electrolyte materials prepared by using PVA...

Synthesis and Characterization of Starch-based Aqueous Polymer Isocyanate Wood Adhesive

Directory of Open Access Journals (Sweden)

Shu-min Wang

2015-09-01

Full Text Available Modified starch was prepared in this work by acid-thinning and oxidizing corn starch with ammonium persulfate. Also, starch-based aqueous polymer isocyanate (API wood adhesive was prepared. The effect of the added amount of modified starch, styrene butadiene rubber (SBR, polymeric diphenylmethane diisocyanate (P-MDI, and the mass concentration of polyvinyl alcohol (PVOH on the bonding strength of starch-based API adhesives were determined by orthogonal testing. The starch-based API adhesive performance was found to be the best when the addition of modified starch (mass concentration 35% was 45 g, the amount of SBR was 3%, the PVOH mass concentration was 10%, and the amount of P-MDI was 18%. The compression shearing of glulam produced by starch-based API adhesive reached bonding performance indicators of I type adhesive. A scanning electron microscope (SEM was used to analyze the changes in micro-morphology of the starch surface during each stage. Fourier transform infrared spectroscopy (FT-IR was used to study the changes in absorption peaks and functional groups from starch to starch-based API adhesives. The results showed that during starch-based API adhesive synthesis, corn starch surface was differently changed and it gradually reacted with other materials.

Effect of Saponification Condition on the Morphology and Diameter of the Electrospun Poly(vinyl acetate) Nanofibers for the Fabrication of Poly(vinyl alcohol) Nanofiber Mats

OpenAIRE

Seong Baek Yang; Jong Won Kim; Jeong Hyun Yeum

2016-01-01

Novel poly(vinyl alcohol) (PVA) nanofiber mats were prepared for the first time through heterogeneous saponification of electrospun poly(vinyl acetate) (PVAc) nanofibers. The effect of varying the saponification conditions, including temperature, time, and concentration of the alkaline solution, on the morphology of the saponified PVA fibers were evaluated by field-emission scanning electron microscopy. At 25 °C, the saponified PVA fibers exhibited a broad diameter distribution. The average f...

Hybrid composite based on poly(vinyl alcohol) and fillers from renewable resources

Science.gov (United States)

Hybrid composite laminates consisting of polyvinyl alcohol (PVA) as continuous phase (33% by weight) and lignocellulosic fillers, derived from sugarcane bagasse, apple and orange waste (22% by weight) were molded in a carver press in the presence of water and glycerol such as platicizers agents. Cor...

Effect of the polymer concentration on the ON/OFF states of a TN-LCD: polyvinyl alcohol vs. soy lecithin

Science.gov (United States)

de Coss Martinez, Romeo; Gonzalez Murguia, Jose Luis

2011-03-01

In this work we study the response of a Twisted Nematic Liquid Crystal Display (TN-LCD) by varying both the concentration and the polymer used for the microgroove. We compare the performance of two polymers: polyvinyl alcohol and soy lecithin. In particular, the light transmission for the ON/OFF states is evaluated. The polyvinyl alcohol is a polymer widely used in LCDs while lecithin soy is a natural polymer.

Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

International Nuclear Information System (INIS)

Surry, K J M; Austin, H J B; Fenster, A; Peters, T M

2004-01-01

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s -1 , and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz) -1 . T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process

Film dosimeters based on methylene blue and methyl orange in polyvinyl alcohol

DEFF Research Database (Denmark)

Chung, W.H.; Miller, A.

1994-01-01

Polyvinyl alcohol (PVA) films containing methylene blue and methyl orange are useful as gamma and electron radiation dosimeters. Absorbed doses should not exceed 40 kGy for methylene blue and 500 kGy for methyl orange. Because PVA is water-soluble, the films may be made without toxic solvents...

Histochemical demonstration of creatine kinase activity using polyvinyl alcohol and auxiliary enzymes

NARCIS (Netherlands)

Frederiks, W. M.; Marx, F.; van Noorden, C. J.

1987-01-01

Creatine kinase activity (EC 2.7.3.2.) has been demonstrated in myocardium and skeletal muscle from rats by a method based on the incubation of cryostat sections with a polyvinyl alcohol-containing medium and the use of auxiliary enzymes. Hexokinase and glucose-6-phosphate dehydrogenase were spread

Compatibility of Polyvinyl Alcohol with the 241-F/H Tank Farm Liquid Waste

International Nuclear Information System (INIS)

Oji, L.N.

1998-01-01

This report describes results from laboratory-scale oxidative mineralization of polyvinyl alcohol (PVA), and the evaluation of the F/H Tank Farms as a storage/disposal option for PVA waste solution generated in the Canyons and B-line decontamination operations

Compatibility of Polyvinyl Alcohol with the 241-F/H Tank Farm Liquid Waste

Energy Technology Data Exchange (ETDEWEB)

Oji, L.N.

1998-11-25

This report describes results from laboratory-scale oxidative mineralization of polyvinyl alcohol (PVA), and the evaluation of the F/H Tank Farms as a storage/disposal option for PVA waste solution generated in the Canyons and B-line decontamination operations.

Elution behavior of poly(ethylene glycol) through poly(vinyl alcohol) gel column using several solvents as eluents

International Nuclear Information System (INIS)

Hirayama, Chuichi; Motozato, Yoshiaki; Matsumoto, Kazuaki.

1983-01-01

γ-Irradiated poly(vinyl alcohol) beads, which were sufficiently allowed to swell in water, were washed with methanol, and then were packed into column. Gel chromatography was performed using methanol, benzene, esters and ketones as eluents and poly(ethylene glycol) as a sample. When the elution was carried out using methanol and benzene as eluents, elution behavior of samples was ordinary. When ethyl formate, methyl acetate and ethyl propionate were used as eluents, samples were slightly adsorbed and the elution was delayed. In the case the elution was carried out using ethyl acetate, propyl acetate, butyl acetate and ethyl methyl ketone as eluents, samples were adsorbed strongly on the bed material, and the adsorption curve was analogous to the calibration curve using methanol as an eluent. Dried poly(vinyl alcohol) gel as a packing material, showed ordinary elution behaviors for the samples. The adsorption of poly(ethylene glycol) on the present bed material was attributed to the existence of hydrated water on poly(vinyl alcohol) gel matrix. (author)

Performance and diversity of polyvinyl alcohol-degrading bacteria under aerobic and anaerobic conditions.

Science.gov (United States)

Huang, Jianping; Yang, Shisu; Zhang, Siqi

2016-11-01

To compare the degradation performance and biodiversity of a polyvinyl alcohol-degrading microbial community under aerobic and anaerobic conditions. An anaerobic-aerobic bioreactor was operated to degrade polyvinyl alcohol (PVA) in simulated wastewater. The degradation performance of the bioreactor during sludge cultivation and the microbial communities in each reactor were compared. Both anaerobic and aerobic bioreactors demonstrated high chemical oxygen demand removal efficiencies of 87.5 and 83.6 %, respectively. Results of 16S rDNA sequencing indicated that Proteobacteria dominated in both reactors and that the microbial community structures varied significantly under different operating conditions. Both reactors obviously differed in bacterial diversity from the phyla Planctomycetes, Chlamydiae, Bacteroidetes, and Chloroflexi. Betaproteobacteria and Alphaproteobacteria dominated, respectively, in the anaerobic and aerobic reactors. The anaerobic-aerobic system is suitable for PVA wastewater treatment, and the microbial genetic analysis may serve as a reference for PVA biodegradation.

78 FR 20890 - Polyvinyl Alcohol From Taiwan: Preliminary Results of Antidumping Duty Administrative Review...

Science.gov (United States)

2013-04-08

... DEPARTMENT OF COMMERCE International Trade Administration [A-583-841] Polyvinyl Alcohol From... Administration, International Trade Administration, Department of Commerce. SUMMARY: The Department of Commerce..., AD/CVD Operations, Office 1, Import Administration, International Trade Administration, U.S...

Embolization therapy of uterine fibroids by using pingyangmycin lipiodol emulsion or polyvinyl alcohol particles: a clinical comparative study

International Nuclear Information System (INIS)

Zhang Dazhong; Yin Jianlin; Liu Hairi; Zhang Fuqiang; Huang Hai; Gu Youmei

2010-01-01

Objective: To evaluate the efficacy and safety of embolization of uterine fibroids by using pingyangmycin lipiodol emulsion or polyvinyl alcohol particles as embolismic materials. Methods: Seventy-three patients with uterine fibroids were divided into two groups. Patients in group A (29 cases) were treated with pingyangmycin lipiodol emulsion as embolismic materials, while patients in group B (44 cases) with polyvinyl alcohol particles (with a diameter of 300-700 μm) as embolismic materials. Embolization therapy of uterine fibroids was performed in all patients. The uterus volume, the size of uterine fibroid and sex hormone level both before and after the treatment were estimated and the results were compared between two groups. The occurrence of complications was observed. Results: The technical success of catheterization and embolization was 100% in both groups. After the therapy,both the uterus volume and the uterine fibroid size decreased significantly, but no significant difference in the size reduction existed between the two groups (P>0.05). The clinical symptoms showed a marked improvement in all patients, while the sex hormone level showed no obvious changes. No serious complications occurred. Conclusion: In treating uterine fibroids with embolization technique, both pingyangmycin lipiodol emulsion and polyvinyl alcohol particles are safe and effective embolismic materials. However, use of polyvinyl alcohol particles may be safer than pingyangmycin, as pingyangmycin is a kind of chemotherapeutic drugs, which might potentially cause some short-term or long-term complications. (authors)

Radiation processing of indigenous natural polymers. Properties of radiation modified blends from sago-starch for biodegradable composite

International Nuclear Information System (INIS)

Ghazali, Z.; Dahlan, K.Z.; Wongsuban, B.; Idris, S.; Muhammad, K.

2001-01-01

Research and development on biodegradable polymer blends and composites have gained wider interest to offer alternative eco-friendly products. Natural polysaccharide such as sago-starch offers the most promising raw material for the production of biodegradable composites. The potential of sago, which is so abundant in Malaysia, to produce blends for subsequent applications in composite material, was evaluated and explored. Blends with various formulations of sago starch and polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP) polymers were prepared and subjected to radiation modification using electron beam irradiation. The effect of irradiation on the sago and its blends was evaluated and their properties were characterized. The potential of producing composite from sago blends was explored. Foams from these blends were produced using microwave oven while films were produced through casting method. The properties such as mechanical, water absorption, expansion ratio, and biodegradability were characterized and reported in this paper. (author)

Radiation processing of indigenous natural polymers. Properties of radiation modified blends from sago-starch for biodegradable composite

Energy Technology Data Exchange (ETDEWEB)

Ghazali, Z.; Dahlan, K.Z. [Malaysian Institute for Nuclear and Technology Research (MINT), Bangi, Kajang (Malaysia); Wongsuban, B.; Idris, S.; Muhammad, K. [Universiti Putra Malaysia, Faculty of Food Science and Biotechnology, Department of Food Science, Serdang (Malaysia)

2001-03-01

Research and development on biodegradable polymer blends and composites have gained wider interest to offer alternative eco-friendly products. Natural polysaccharide such as sago-starch offers the most promising raw material for the production of biodegradable composites. The potential of sago, which is so abundant in Malaysia, to produce blends for subsequent applications in composite material, was evaluated and explored. Blends with various formulations of sago starch and polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP) polymers were prepared and subjected to radiation modification using electron beam irradiation. The effect of irradiation on the sago and its blends was evaluated and their properties were characterized. The potential of producing composite from sago blends was explored. Foams from these blends were produced using microwave oven while films were produced through casting method. The properties such as mechanical, water absorption, expansion ratio, and biodegradability were characterized and reported in this paper. (author)

Reentrant behaviour in polyvinyl alcohol-borax hydrogels

Science.gov (United States)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2018-01-01

Polyvinyl alcohol (PVA) hydrogels, cross-linked with varying concentrations of borax, were studied with small angle neutron scattering (SANS), x-ray diffraction (XRD) and differential thermal analysis (DTA). The SANS data satisfy the Ornstein-Zernike approximation. The hydrogels are modelled as PVA chains bound by borate cross-links. Water occupies the spaces within the three-dimensional hydrogel network. The mesh size ξ indicates reentrant behaviour i.e. at first, ξ increases and later decreases as a function of borax concentration. The behaviour is explained on the basis of the balance between the charged di-diol cross-links and the shielding by free ions in the solvent. XRD and DTA show the molecular size of water in the solvent and the glass transition temperature commensurate with reentrant behaviour.

Three methods for in situ cross-linking of polyvinyl alcohol films for application as ion-conducting membranes in potassium hydroxide electrolyte. [battery separators

Science.gov (United States)

Philipp, W. H.; Hsu, L. C.

1979-01-01

Three methods of in situ cross-linking polyvinyl alcohol films are presented. They are: (1) acetalization with a dialdehyde such as glutaraldehyde, (2) acetalization with aldehyde groups formed by selective oxidative cleaving of the few percent of 1,2 diol units present in polyvinyl alcohol, and (3) cross-linking by hydrogen abstraction by reaction with hydrogen atoms and hydroxyl radicals from irradiated water. For the third method, improvement in film conductivity in KOH solution at the expense of mechanical strength is obtained by the presence of polyacrylic acid in the polyvinyl alcohol films. Resistivities in 45 percent KOH are given for in situ cross-linked films prepared by each of the three methods.

Biaxial stress-strain behavior of chemical and physical gels of poly(vinyl alcohol)

Czech Academy of Sciences Publication Activity Database

Meissner, Bohumil; Matějka, Libor

2008-01-01

Roč. 49, č. 10 (2008), s. 2560-2567 ISSN 0032-3861 R&D Projects: GA AV ČR IAA400500701 Institutional research plan: CEZ:AV0Z40500505 Keywords : poly(vinyl alcohol) gels * pure shear behavior * constitutive equation Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.331, year: 2008

Templated diamond growth on porous carbon foam decorated with polyvinyl alcohol-nanodiamond composite

Czech Academy of Sciences Publication Activity Database

Varga, Marián; Stehlík, Štěpán; Kaman, Ondřej; Ižák, Tibor; Domonkos, Mária; Lee, D.S.; Kromka, Alexander

2017-01-01

Roč. 119, Aug (2017), s. 124-132 ISSN 0008-6223 R&D Projects: GA ČR GC15-22102J Institutional support: RVO:68378271 Keywords : nucleation * polyvinyl alcohol * nanodiamonds * carbon foam Subject RIV: JJ - Other Materials OBOR OECD: Nano-materials (production and properties) Impact factor: 6.337, year: 2016

Polyvinyl Alcohol-Lead Nitrate Paint for Gamma Radiation Installations

International Nuclear Information System (INIS)

EI-Ahdal, M.A.

2007-01-01

Dealing with gamma ray installations represents an important problem for radiation protection workers. Radiation shielding is used to avoid the risk resulting from these gamma sources. This study suggested the use of polyvinyl alcohol (PVA) solution that contains lend nitrate (with lead metal/PVA= 1.72) to lower the gamma radiation intensity and reduce its risk to workers. This can be achieved by painting the radiation shielding with this solution Temperature relief of the irradiated solution shows the degradation of the polymer content up to 50 degree C, which starts to crosslink increasing the protection capability of this solution

In-situ reduced graphene oxide-polyvinyl alcohol composite coatings as protective layers on magnesium substrates

Directory of Open Access Journals (Sweden)

Xingkai Zhang

2017-06-01

Full Text Available A simple and feasible method was developed to fabricate in-situ reduced graphene oxide-polyvinyl alcohol composite (GO-PVA coatings as protective layers on magnesium substrates. Polyvinyl alcohol was used as an in-situ reductant to transform GO into reduced GO. Contiguous and uniform GO-PVA coatings were prepared on magnesium substrates by dip-coating method, and were further thermally treated at 120 °C under ambient condition to obtain in-situ reduced GO-PVA coatings. Owing to the reducing effect of PVA, thermal treatment at low temperature led to effective in-situ reduction of GO as confirmed by XRD, Raman, FTIR and XPS tests. The corrosion current density of magnesium substrates in 3.5 wt% NaCl solution could be lowered to its 1/25 when using in-situ reduced GO-PVA coatings as protective layers.

Effects of electron beam irradiation on properties of corn starch undergone periodate oxidation mechanism blended with polyvinyl alcohol

Science.gov (United States)

Bee, Soo-Tueen; Sin, Lee Tin; Ratnam, C. T.; Yap, Bee-Fen; Rahmat, A. R.

2018-02-01

This work was performed to examine the properties of pristine PVOH and PVOH-starch blends under exposure of different irradiation dosages. The periodate oxidation method was used to produce dialdehyde starch. The application of low dosages of electron beam irradiation (≤10 kGy) has improved the tensile strength by forming crosslinking networks. However, the tensile strength drastically declined when radiated at 30 kGy due to the reduction of available hydroxyl groups inside polymer matrix for intermolecular interaction. Also, the incorporation of corn starch and dialdehyde starch has significantly reduced the melting temperature and enthalpy of melting of PVOH blends due to cessation of the hydrogen bonding between PVOH and starch molecules. The crystallite size for deflection planes (1 0 1), (1 0 1) and (2 0 0) for all PVOH blends was significant reduced when irradiated. The electron beam irradiation has also weakened the hydrophilic characteristic of all PVOH blends as evidenced in infrared and microscopy analysis.

Effects of γ-rays on electrical conductivity of polyvinyl alcohol-polypyrrole composite polymer films

International Nuclear Information System (INIS)

Mohd Hamzah Harun; Elias Saion; Noorhana Yahya; Anuar Kassim; Ekramul Mahmud; Muhammad Yousuf Hussain; Iskandar Shahrim Mustafa; Azian Othman; Norazimah Mohd Yusof; Mohd Ahmad Ali Omer

2007-01-01

The composite polymer films of polyvinyl alcohol/polypyrrole/chloral hydrate (PVA-PPy-CH) had been prepared. Effects of γ-rays on the electrical conductivity of the composite polymer films had been investigated by using Inductance Resistance meter (LCR) meter at a frequency ranging from 20 Hz to 1 MHz. With the incorporation of choloral hydrate in the polymer sample, the conductivity increased indicates that it is capable to be used as dopant for polymerizing conjugated polymer. The electrical conductivity obtained increased as the dose increased, which is in the order of 10 -5 Scm -1 indicates that γ-ray is capable to enhance the electrical conductivity of the composite polymer films. The parameter of s is in the range of 0.31 ≤ S ≤ 0.49 and obeyed simple power law dispersion ω S . The Scanning Electron Microscopy (SEM) micrographs reveal the formation of polypyrrole globules in polyvinyl alcohol matrix which increased as the irradiation dose was increased. (Author)

Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite

International Nuclear Information System (INIS)

Debiagi, Flavia; Mali, Suzana

2011-01-01

The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

The Effects of Surface Mechanical Deformation and Bovine Serum Albumin on the Tribological Properties of Polyvinyl Alcohol Hydrogel as an Artificial Cartilage

Directory of Open Access Journals (Sweden)

Feng Li

2017-01-01

Full Text Available The mechanical and tribological properties of polyvinyl alcohol hydrogel as an artificial cartilage were studied under water and bovine serum albumin-lubricated sliding conditions. The frictional properties of the polyvinyl alcohol hydrogel were investigated via reciprocating frictional tests. The effect of surface mechanical deformation on the tribological properties of the polyvinyl alcohol hydrogel as an artificial cartilage was studied by concurrently recording the z-axis displacement and friction coefficient time. Three different factors were chosen including load, speed, and lubrication. The results showed that the albumin solution could reverse the trend in the coefficient of friction in tests at different loading levels. There was no improvement in the friction condition in albumin at low speeds. However, when the speed was increased to 2 Hz, the coefficient of friction was significantly reduced. Wear testing was also conducted, and wear tracks were found on the sample surface. The results also showed that even though the surface deformation could recover as the water phase of the porous structure recovered, the coefficient of friction continued to increase simultaneously. This relationship between mechanical and frictional tests indicated that biphasic lubrication effects may not be the only dominant factor underlying the excellent friction properties of polyvinyl alcohol hydrogel.

The influence of stretching on tensile strength and solubility of poly(vinyl alcohol) fibres

NARCIS (Netherlands)

Heikens, D.; Bleijenberg, A.C.A.M.; Hoppenbrouwers, J.J.M.; Barentsen, W.M.

1971-01-01

The strength of wet-spun poly(vinyl alcohol) (pva) fibres is given as function of bath-stretching, wet-stretching and hot-stretching. In the two equations derived for strength of wet-stretching and hot-stretching the complex influence of the bath-stretching and hot-stretching is demonstrated. The

The effect of poly(vinyl alcohol) type and radiation treatment on the properties of starch-poly(vinyl alcohol) films

Science.gov (United States)

Cieśla, Krystyna; Abramowska, Anna; Boguski, Jacek; Drewnik, Joanna

2017-12-01

Our present study concerns the effect of application of various PVA substrates and the influence of ionising radiation on the properties of films based on starch and PVA. Four PVAs revealing various molecular masses (in the range of 11-145 kDa) were selected for this purpose. The films characterized by starch: PVA ratios of 40:60 were prepared by solution casting and irradiated with 60Co gamma rays (under nitrogen) and with fast electrons (under air) applying the absorbed dose of 25 kGy. Mechanical properties of the films (tensile strength, elongation at break and Young Modulus) were examined, as well as the contact angle to water and swelling in water, in regard for evaluation of the hydrophilic/hydrophobic properties. Gel content in the samples was also determined. Physicochemical properties of the films and their sensitivity to irradiation strongly depend on the applied PVA substrate. This can be related to differences in the capability of particular PVAs for forming the crosslinked starch-PVA network during the films' synthesis and future treatment. In particular, the usage of the PVA characterized by the high molecular mass has appeared more rewarding as compared to those based on the low molecular mass PVAs. Additionally, properties of these films were not affected or improved after irradiation.

Memristive learning and memory functions in polyvinyl alcohol polymer memristors

Directory of Open Access Journals (Sweden)

Yan Lei

2014-07-01

Full Text Available Polymer based memristive devices can offer simplicity in fabrication and at the same time promise functionalities for artificial neural applications. In this work, inherent learning and memory functions have been achieved in polymer memristive devices employing Polyvinyl Alcohol. The change in conduction in such polymer devices strongly depends on the pulse amplitude, duration and time interval. Through repetitive stimuli training, temporary short-term memory can transfer into consolidated long-term memory. These behaviors bear remarkable similarities to certain learning and memory functions of biological systems.

Effect of Hydroxyl Concentration on Chemical Sensitivity of Polyvinyl Alcohol/Carbon-Black Composite Chemiresistors

International Nuclear Information System (INIS)

Hughes, Robert C.; Patel, Sanjay V.; Yelton, W. Graham

1999-01-01

The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage (''-OH'') of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an array to distinguish the responses to methanol-water mixtures

Disk Refining and Ultrasonication Treated Sugarcane Bagasse Residues for Poly(Vinyl Alcohol) Bio-composites

Science.gov (United States)

Qingzheng Cheng; Zhaohui Tong; Luisa Dempere; Lonnie Ingram; Letian Wang; J.Y. Zhu

2013-01-01

Disk refining and ultrasonication treated sugarcane bagasse residues reclaimed from the waste stream of a simplified bioethanol process after fermentation were used to fabricate biobased composites with poly(vinyl alcohol) (PVA) by film casting. The morphologies and the size distributions of residue particles were characterized by scanning electronic microscopy and...

Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

Energy Technology Data Exchange (ETDEWEB)

Nho, Young-Chang [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)]. E-mail: ycnho@kaeri.re.kr; Park, Sung-Eun [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of); Kim, Hyung-Il [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Hwang, Taek-Sung [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2005-07-01

The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose.

Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

International Nuclear Information System (INIS)

Nho, Young-Chang; Park, Sung-Eun; Kim, Hyung-Il; Hwang, Taek-Sung

2005-01-01

The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose

Studying the Properties of Polyvinyl Alcohol/Cellulose Nanofiber/Hydroxyapatite Hybrid Nanocomposite

Directory of Open Access Journals (Sweden)

Mostafa Yahyavi

2015-06-01

Full Text Available Nanocomposite materials have recently attracted much attention because of their desirable and unique physical and mechanical properties. Today, many studies have focused on the preparation of high performance new nanocomposites made of biobased and biodegradable materials as both the matrix and reinforcement phases. Because of biocompatibility, biofunctionality, and biological safety in the body, hydroxyapatite-polyvinyl alcohol composites are vastly used in medical applications, specially in the bone tissue regeneration. The properties of a new generation of nanocomposites consisting of hydroxyapatite nanoparticles and cellulose nanofibers, dispersed in polyvinyl alcohol matrix, were investigated. The percentage by weight of each component in the final formulation and the time of ultrasonication were studied as factors affecting the physical and mechanical properties. Tensile strength, elastic modulus and resistance to water dissolution were evaluated. The results showed that by increasing the percentage by weight of PVA and cellulose nanofibers and ultrasonication time, the tensile strength and elastic modulus increased and the resistance to water dissolution and weight loss decreased. On the other hand, with increasing the amount of hydroxyapatite nanoparticles in the final formulation, the elastic modulus and resistance to water solubility increased, while the tensile strength decreased significantly. Scanning electron microscopy (SEM micrographs were used to find exact correlations between the observed physical and mechanical properties and the structural morphology.

Ethanol-water separation by pervaporation using silicone and polyvinyl alcohol membranes

Directory of Open Access Journals (Sweden)

Chinchiw, S.

2006-09-01

Full Text Available In this research, experiments were carried out to investigate the effects of operating parameters onthe pervaporation performance for the separation of ethanol-water solutions. Composite silicone membranessupported on polysulfone prepared with varied silicone contents and commercial polyvinyl alcohol (Pervap®2211, Sulzer membranes were used. The results showed that the composite silicone/polysulfone membranescoated with 3 wt% of silicone exhibited highest permeation flux with slightly lower separation factor forethanol. Furthermore, it was found that the composite silicone/polysulfone membranes were suitable for theseparation of ethanol from a dilute ethanol solutions. Both the separation factor and permeation flux of the composite membranes increased with increasing temperature and feed concentration. A membrane coated with a 7 wt% silicone gave highest separation factor of 7.32 and permeation flux of 0.44 kg/m2h at 5 wt% ethanol feed concentration and feed temperature of 70ºC. For polyvinyl alcohol membranes, the results showed that the membranes were suitable for the dehydration of concentrated ethanol solutions. The permeation flux increased and the separation factor for water decreased with increasing water feed concentration and temperature. The membrane gave highest separation factor of 248 and permeation flux of 0.02 kg/m2h at 5 wt% water feed concentration and feed temperature of 30ºC.

Comparison of Tensile, Permeability and Color Properties of Starch-based Bionanocomposites Containing Two Types of Fillers: Sodium Montmorilonite and Cellulose Nanocrystal

Directory of Open Access Journals (Sweden)

Nooshin Noushirvani

2013-01-01

Full Text Available The objective of this research was to compare the tensile, permeability, solubility and color properties of plasticized starch-polyvinyl alcohol-Montmo-rillonite (PS-PVA-MMT and plasticized starch-polyvinyl alcohol-cellulose nanocrystal (PS-PVA-NCC bionanocomposite flms. The results showed that adding MMT (7%, increased the ultimate tensile strenght from 4.2 MPa to 4.61 MPa, however, NCC (7% did not show signifcant (p < 0.5 effect on the ultimate tensile strength. Addition of MMT decreased while NCC  increased  the  strain-to-break of  the flms. The solubility in water decreased from 23.56% to 18.77% and 11.75% for the flms containing NCC and MMT, respectively. Similarly, water vapor permeability value of 7.41 ×10-7 g/m.h.Pa was dropped to 7.05×10-7 g/m.h.Pa and 6.19×10-7 g/m.h.Pa in flms containing NCC and MMT, respectively. The results showed that the effects of MMT on tensile and permeability were higher than NCC, which can be attributed to differences in the structure and hydrophilicity of two nanoparticles.

Influence of polymer chain architecture of poly(vinyl alcohol) on the inhibition of ice recrystallization

NARCIS (Netherlands)

Olijve, L.L.C.; Hendrix, M.M.R.M.; Voets, I.K.

2016-01-01

Poly(vinyl alcohol) (PVA) is a water-soluble synthetic polymer well-known to effectively block the recrystallization of ice. The effect of polymer chain architecture on the ice recrystallization inhibition (IRI) by PVA remains unexplored. In this work, the synthesis of PVA molecular bottlebrushes is

Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

International Nuclear Information System (INIS)

Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

2013-01-01

Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

Oxidative mineralization and characterization of polyvinyl alcohol for compatibility with tank farm processing chemistry

Energy Technology Data Exchange (ETDEWEB)

Oji, L.N.

2000-01-04

Polyvinyl alcohol (PVA) material has been evaluated for use as a cost-effective substitute for conventional cellulose-based disposal materials (decontamination mops and wipes), plastic bags, and disposable personal protection clothing, that are currently used at Savannah River Site. This study also provides process design criteria for ultraviolet/ultrasonic/hydrogen peroxide PVA reactor system.

Oxidative mineralization and characterization of polyvinyl alcohol for compatibility with tank farm processing chemistry

International Nuclear Information System (INIS)

Oji, L.N.

2000-01-01

Polyvinyl alcohol (PVA) material has been evaluated for use as a cost-effective substitute for conventional cellulose-based disposal materials (decontamination mops and wipes), plastic bags, and disposable personal protection clothing, that are currently used at Savannah River Site. This study also provides process design criteria for ultraviolet/ultrasonic/hydrogen peroxide PVA reactor system

Physicochemical characteristics of gamma irradiation crosslinked poly(vinyl alcohol)/magnetite ferrogel composite

OpenAIRE

Marinović-Cincović, Milena T.; Radosavljević, Aleksandra N.; Krstić, Jelena I.; Spasojević, Jelena P.; Bibić, Nataša M.; Mitrić, Miodrag N.; Kačarević-Popović, Zorica M.

2014-01-01

Magnetic field sensitive gels, ferrogels are new promising class of hydrogels. The coupling of hydrogels and magnetic particles has potential application in soft actuators such as artificial muscles or for hyperthermia application. Here a composite of magnetite particles (Fe3O4) and poly(vinyl alcohol) (PVA) hydrogel is developed using gamma irradiation as a crosslinking agent. PVA and Fe3O4 were chosen because of their well-established biocompatibility, ra...

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure

OpenAIRE

Sun, Xiaoxia; Uyama, Hiroshi

2013-01-01

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructu...

Study on properties of poly(vinyl alcohol/polyacrylonitrile blend film

Directory of Open Access Journals (Sweden)

Guoquan Zhu

2013-01-01

Full Text Available In this work, a series of poly(vinyl alcohol (PVA/polyacrylonitrile (PAN blend films with different PAN mole contents were prepared by casting the polymer blend solution in dimethylsulfoxide (DMSO. Surface morphologies of PVA/PAN blend films were analyzed by Scanning Electronic Microscopy (SEM and Atomic Force Microscopy (AFM. Thermal, mechanical, and chemical properties of PVA/PAN blend films were investigated by Differential Scanning Calorimetry (DSC, Thermogravimetric Analysis (TGA, Tensile Tests, and Surface Contact Angle Tests. The results showed that the introduction of PAN could exert marked effects on the properties of PVA films.

Effects of Concentration of Organically Modified Nanoclay on Properties of Sulfonated Poly(vinyl alcohol Nanocomposite Membranes

Directory of Open Access Journals (Sweden)

Apiradee Sanglimsuwan

2011-01-01

Full Text Available Electrolyte nanocomposite membranes for proton exchange membrane fuel cells and direct methanol fuel cells were prepared by carrying out a sulfonation of poly(vinyl alcohol with sulfosuccinic acid and adding a type of organically modified montmorillonite (layered silicate nanoclay commercially known as Cloisite 93A. The effects of the different concentrations (0, 2, 4, 6, 8 wt. % of the organoclay in the membranes on water uptake, ion exchange capacity (IEC, proton conductivity, and methanol permeability were measured, respectively, via gravimetry, titration, impedance analysis, and gas chromatography techniques. The IEC values remained constant for all concentrations. Water uptakes and proton conductivities of the nanocomposite membranes changed with the clay content in a nonlinear fashion. While all the nanocomposite membranes had lower methanol permeability than Nafion115, the 6% concentration of Cloisite 93A in sulfonated poly(vinyl alcohol membrane displayed the greatest proton conductivity to methanol permeability ratio.

Effect of gamma radiation on the poly(vinyl alcohol)

International Nuclear Information System (INIS)

Terence, M.C.; Guedes, S.M.L.

2000-01-01

The poly(vinyl alcohol) (PVAL) is a polymer used as bio material. The PVAL was used as ocular insert and may be used as a drug delivery system (DDS) for pair PVAL/gancyclovir, where the last one is used for treatment of people with retinitis caused by cytomegalovirus. These inserts are crosslinked systems. The crosslink was induced by gamma radiation applied in polymer. The samples of PVAL was irradiated by gamma rays with doses in the range 0 to 100 kGy. On irradiated PVAL samples was observed a low yellowness, attributed to the formation of polymeric radicals that are stable in the structure of the polymer, from radiolysis of PVAL. (author)

Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets

International Nuclear Information System (INIS)

Annamalai, P.; Lee, M.C.; Crawley, R.L.; Downs, R.L.

1985-01-01

An inertial confinement fusion (ICF) target made of polystyrene is first levitated in an acoustic field. The surface of the target is then etched using an appropriate solution (e.g., cyclohexane) to enhance the wetting characteristics. A specially prepared polyvinyl alcohol solution is atomized using an acoustic atomizer and deposited on the surface of the target. The solution is air dried to form a thin coating (2 μm) on the target (outside diameter approx.350--850 μm). Thicker coatings are obtained by repeated applications of the coating solution. Preliminary results indicate that uniform coatings may be achievable on the targets with a background surface smoothness in the order of 1000 A

Effect of Poly(Vinyl Alcohol) Addition on the Properties of Hydrothermal Derived Calcium Phosphate Cement for Bone Filling Materials

Science.gov (United States)

Razali, N. N.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.; Singh, R.

2017-06-01

The effect of addition of poly(vinyl alcohol) on hydrothermal derived calcium phosphate cement has been studied. The precursors used to prepare the cement were calcium oxide (CaO) and ammonium dihydrogen phosphate (NH4H2PO4); the reaction was conducted in water at 80-100°C. To improve properties of CPC, poly(vinyl alcohol) (PVA) of 1wt% and 2wt% was added to the liquid phase of CPC and the results were compared to CPC without PVA addition. The addition of PVA was proved to bring remarkable effects on cohesion, setting time and mechanical strength of CPC which make it suitable physically for injectable bone filler applications.

Preparation and Biodegradation of Nanocellulose Reinforced Polyvinyl Alcohol Blend Films in Bioenvironmental Media

OpenAIRE

Nusaiba Islam; Sharmin Jahan Proma; Ashiqur Rahman; Ashok Kumar Chakraborty

2017-01-01

Solution casting method was used to prepare nanocellulose reinforced polyvinyl alcohol (PVOH) from Oil palm empty fruit bunches. Different environmental test were used to investigate the biodegradability of the composite in soil and compost as well as in water and acidic solution. The morphology of the composite was investigated by scanning electron microscopy. The composite film with nanocellulose and without nanocellulose were compared, nanocellulose modified PVOH film showed more highly de...

Process optimization of ultrasound-assisted alcoholic-alkaline treatment for granular cold water swelling starches.

Science.gov (United States)

Zhu, Bo; Liu, Jianli; Gao, Weidong

2017-09-01

This paper reports on the process optimization of ultrasonic assisted alcoholic-alkaline treatment to prepare granular cold water swelling (GCWS) starches. In this work, three statistical approaches such as Plackett-Burman, steepest ascent path analysis and Box-Behnken design were successfully combined to investigate the effects of major treatment process variables including starch concentration, ethanol volume fraction, sodium hydroxide dosage, ultrasonic power and treatment time, and drying operation, that is, vacuum degree and drying time on cold-water solubility. Results revealed that ethanol volume fraction, sodium hydroxide dosage, applied power and ultrasonic treatment time were significant factors that affected the cold-water solubility of GCWS starches. The maximum cold-water solubility was obtained when treated at 400W of applied power for 27.38min. Optimum volume fraction of ethanol and sodium hydroxide dosage were 66.85% and 53.76mL, respectively. The theoretical values (93.87%) and the observed values (93.87%) were in reasonably good agreement and the deviation was less than 1%. Verification and repeated trial results indicated that the ultrasound-assisted alcoholic-alkaline treatment could be successfully used for the preparation of granular cold water swelling starches at room temperatures and had excellent improvement on the cold-water solubility of GCWS starches. Copyright © 2016. Published by Elsevier B.V.

Localization of xanthine oxidoreductase activity using the tissue protectant polyvinyl alcohol and final electron acceptor Tetranitro BT

NARCIS (Netherlands)

Kooij, A.; Frederiks, W. M.; Gossrau, R.; van Noorden, C. J.

1991-01-01

We have detected xanthine oxidoreductase activity in unfixed cryostat sections of rat and chicken liver, rat duodenum, and bovine mammary gland using the tissue protectant polyvinyl alcohol, the electron carrier 1-methoxyphenazine methosulfate, the final electron acceptor Tetranitro BT, and

Preparation of polyvinyl alcohol graphene oxide phosphonate film and research of thermal stability and mechanical properties.

Science.gov (United States)

Li, Jihui; Song, Yunna; Ma, Zheng; Li, Ning; Niu, Shuai; Li, Yongshen

2018-05-01

In this article, flake graphite, nitric acid, peroxyacetic acid and phosphoric acid are used to prepare graphene oxide phosphonic and phosphinic acids (GOPAs), and GOPAs and polyvinyl alcohol (PVA) are used to synthesize polyvinyl alcohol graphene oxide phosphonate and phosphinate (PVAGOPs) in the case of faint acidity and ultrasound irradiation, and PVAGOPs are used to fabricate PVAGOPs film, and the structure and morphology of GOPAs, PVAGOPs and PVAGOPs film are characterized, and the thermal stability and mechanical properties of PVAGOPs film are investigated. Based on these, it has been proved that GOPAs consist of graphene oxide phosphonic acid and graphene oxide phosphinic acid, and there are CP covalent bonds between them, and PVAGOPs are composed of GOPAs and PVA, and there are six-member lactone rings between GOPAs and PVA, and the thermal stability and mechanical properties of PVAGOPs film are improved effectively. Copyright © 2018 Elsevier B.V. All rights reserved.

The Preparation of Graphene Reinforced Poly(vinyl alcohol Antibacterial Nanocomposite Thin Film

Directory of Open Access Journals (Sweden)

Yuan-Cheng Cao

2015-01-01

Full Text Available Methylated melamine grafted polyvinyl benzylchloride (mm-g-PvBCl was prepared which was used as additive in poly(vinyl alcohol (PVA and graphene nanosheets (GNs were used to reinforce the mechanical strength. Using casting method, antimicrobial nanocomposite films were prepared with the polymeric biocide loading lever of 1 wt%, 5 wt%, and 10 wt%. Thermogravimetric analysis (TGA characterization revealed the 2.0 wt% of graphene content in resultant nanocomposites films. XRD showed that the resultant GNs 2 theta was changed from 16.6 degree to 23.3 degree. Using Japanese Industry Standard test methods, the antimicrobial efficiency for the loading lever of 1 wt%, 5 wt%, and 10 wt% was 92.0%, 95.8%, and 97.1%, respectively, against gram negative bacteria E. coli and 92.3%, 99.6%, and 99.7%, respectively, against the gram positive S. aureus. These results indicate the prepared nanocomposite films are the promising materials for the food and drink package applications.

Sodium deoxycholate functionalized graphene and its composites with polyvinyl alcohol

International Nuclear Information System (INIS)

Wang Lanwei; Liao Ruijuan; Tang Zhenghai; Lei Yanda; Guo Baochun

2011-01-01

Sodium deoxycholate (SDC), a kind of bile derivative, is used to noncovalently functionalize graphene. Stable and high concentration (up to 20 mg ml -1 ) of graphene colloid is obtained. The stabilization mechanism is revealed to be hydrophobic interaction, electrostatic repulsion and hydrogen bonding. Single-layer and few-layer graphene are obtained in the colloid. Subsequently, the obtained graphene sheets are incorporated into a polyvinyl alcohol (PVA) matrix by solution casting to fabricate PVA/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the PVA matrix and strong interfacial adhesion between them. Significant improvements in tensile strength and modulus of the composite films are observed.

A novel reverse osmosis membrane modified by polyvinyl alcohol with maleic anhydride crosslinking

Science.gov (United States)

Samnani, Mohit; Rathod, Harshad; Raval, Hiren

2018-03-01

In the era of increasing energy crisis, it is inevitable to decrease process energy consumption to increase process viability and curtail green-house gas emission. The Reverse Osmosis plant requires significant energy to transfer water overcoming the osmotic pressure. This paper focuses on increasing the water flux for Thin Film Composite Reverse Osmosis (TFC RO) membrane without compromising salt rejection performance leading to the environmentally friendly and economically attractive process. The virgin TFC RO membrane was exposed to solution of sodium hypochlorite of concentration 2000 mg l-1 for 1 h to activate the surface of the membrane, followed by the treatment with the mixture of polyvinyl alcohol and maleic anhydride with varying concentrations for 1 h and curing in the oven at 80 °C temperature for 10 min. Out of all the treated membranes, the membrane treated with 2000 mg l-1 polyvinyl alcohol and 1000 mg l-1 maleic anhydride demonstrated the highest salt rejection of 96.83 % with 2% increase as compared to the virgin TFC RO membrane. The water flux of the membrane was around 44% higher than the virgin TFC RO membrane. The membrane samples were characterized by atomic force micrographs, ATR-FTIR, Nuclear magnetic resonance and Dynamic mechanical analysis.

Characterization and electrical properties of polyvinyl alcohol based polymer electrolyte films doped with ammonium thiocyanate

Energy Technology Data Exchange (ETDEWEB)

Kulshrestha, N., E-mail: niharikakul@gmail.com; Chatterjee, B.; Gupta, P.N., E-mail: guptapn07@yahoo.co.in

2014-05-01

Highlights: • Polyvinyl alcohol (PVA). • Ammonium thiocyanate (NH{sub 4}SCN). • Electrical conductivity. • Fractals. - Abstract: In this communication, films of polyvinyl alcohol (PVA) polymer complexed with ammonium thiocyanate (NH{sub 4}SCN) salt were studied. XRD (X-ray diffraction) was used to study the complexation of salt with the polymer matrix and amorphicity in the films. DSC (differential scanning calorimetry) studies showed that the glass transition temperatures (T{sub g}) of the PVA:NH{sub 4}SCN complexed films were less than pristine PVA. Raman analysis was analyzed in order to study the change in the vibrational bands due to the complexation of salt with PVA. Optical micrographs confirm the fractal formation in 75:25 and 70:30 PVA:NH{sub 4}SCN films. Ionic transference number was estimated by Wagner's polarization method and its large value indicates that conduction takes place mainly due to mobile ionic species. Maximum conductivity ∼10{sup −3} S/cm at room temperature was obtained for 70:30 ratio of PVA: NH{sub 4}SCN polymer electrolyte films.

Enzyme cytochemistry of unfixed leukocytes and bone marrow cells using polyvinyl alcohol for the diagnosis of leukemia

NARCIS (Netherlands)

van Noorden, C. J.; Vogels, I. M.; van Wering, E. R.

1989-01-01

Cytochemical methods for the demonstration of enzyme activities in blood and bone marrow cells were systematically improved by the addition of an inert polymer, polyvinyl alcohol (PVA), to the incubation medium and by using optimized reaction media. The methods investigated were tetrazolium salt

Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels

Science.gov (United States)

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2012-06-01

Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

Ultrasonic-assisted preparation of graphene oxide carboxylic acid polyvinyl alcohol polymer film and studies of thermal stability and surface resistivity.

Science.gov (United States)

Li, Yongshen; Li, Jihui; Li, Yuehai; Li, Yali; Song, Yunan; Niu, Shuai; Li, Ning

2018-01-01

In this paper, flake graphite, nitric acid and acetic anhydride are used to prepare graphene oxide carboxylic acid (GO-COOH) via an ultrasonic-assisted method, and GO-COOH and polyvinyl alcohol polymer (PVA) are used to synthesize graphene oxide carboxylic acid polyvinyl alcohol polymer (GO-COOPVA) via the ultrasonic-assisted method, and GO-COOPVA is used to manufacture graphene oxide carboxylic acid polyvinyl alcohol polymer film (GO-COOPVA film) via a solidification method, and the structure and morphology of GO-COOH, GO-COOPVA and GO-COOPVA film are characterized, and the thermal stability and surface resistivity are measured in the case of the different amount of GO-COOH. Based on the characterization and measurement, it has been successively confirmed and attested that carboxyl groups implant on 2D lattice of GO to form GO-COOH, and GO-COOH and PVA have the esterification reaction to produce GO-COOPVA, and GO-COOPVA consists of 2D lattice of GO-COOH and the chain of PVA connected in the form of carboxylic ester, and GO-COOPVA film is composed of GO-COOPVA, and the thermal stability of GO-COOPVA film obviously improves in comparison with PVA film, and the surface resistivity of GO-COOPVA film clearly decreases. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroscopic, thermal, and electrical properties of MgO/ polyvinyl pyrrolidone/ polyvinyl alcohol nanocomposites

Science.gov (United States)

Mohammed, Gh.; El Sayed, Adel M.; Morsi, W. M.

2018-04-01

In this study, we aimed to control the optical and electrical properties of polyvinyl alcohol (PVA) in order to broaden its industrial and technological applications, which we achieved by blending PVA with polyvinyl pyrrolidone (PVP) and adding sol-gel prepared MgO nanopowder. The blended film and nanocomposite films were prepared using the solution casting technique. X-ray diffraction analyses showed that the crystallite size was ∼18.4 nm for MgO and the highest degree of crystallinity (XC) in the films was about 24.34% at 1.0 wt% MgO. High resolution transmission electron microscopy determined the nanoribbon morphology of MgO. Scanning electron microscopy (SEM) indicated the uniform distribution of the MgO nanoribbons on the surfaces of the PVA/PVP films. SEM and Fourier transform infrared spectroscopy also confirmed the interaction between the blend and MgO fillers. The effects of the additives on the glass transition (Tg) and melting (Tm) temperatures were evaluated by differential thermal analysis and differential scanning calorimetry. The appearance of one melting point confirmed the miscibility of the two polymers. According to ultraviolet-visible-near infrared spectroscopy measurements, the optical properties and optical constants of PVA could be adjusted by the addition of PVP and MgO, where the optical band gap (Eg) determined for PVA increased with the PVP content, whereas it decreased to 4.8 eV as the MgO content increased. The DC conductivity (σdc) of the films increased whereas the activation energy (Ea) decreased after the addition of MgO, possibly because the nanoribbon shape fixed the preferred conducting pathways. In addition, MgO could break the H-bond in sbnd OH groups of the blends to allow the free movement of the molecular chains.

Biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel for knee meniscus applications, including comparison with human donor samples.

Science.gov (United States)

Hayes, Jennifer C; Curley, Colin; Tierney, Paul; Kennedy, James E

2016-03-01

The primary objective of this research was the biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol (PVA) was treated with a sodium sulphate (Na2SO4) solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Development of a meniscal shaped mould and sample housing unit allowed the production of meniscal shaped hydrogels for direct comparison to human meniscal tissue. Results obtained show that compressive responses were slightly higher in PVA/Na2SO4 menisci, displaying maximum compressive loads of 2472N, 2482N and 2476N for samples having undergone 1, 3 and 5 freeze-thaw cycles respectively. When compared to the human meniscal tissue tested under the same conditions, an average maximum load of 2467.5N was observed. This suggests that the PVA/Na2SO4 menisci are mechanically comparable to the human meniscus. Biocompatibility analysis of PVA/Na2SO4 hydrogels revealed no acute cytotoxicity. The work described herein has innovative potential in load bearing applications, specifically as an alternative to meniscectomy as replacement of critically damaged meniscal tissue in the knee joint where repair is not viable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Mahdieh, Zahra [Polymeric Materials Research Group (PMRG), Department of Materials Science and Engineering, Sharif University of Technology, Tehran, P.O. Box 11155-9466 (Iran, Islamic Republic of); Bagheri, Reza, E-mail: rezabagh@sharif.edu [Polymeric Materials Research Group (PMRG), Department of Materials Science and Engineering, Sharif University of Technology, Tehran, P.O. Box 11155-9466 (Iran, Islamic Republic of); Eslami, Masoud; Amiri, Mohammad [Polymeric Materials Research Group (PMRG), Department of Materials Science and Engineering, Sharif University of Technology, Tehran, P.O. Box 11155-9466 (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali; Mehrjoo, Morteza [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of)

2016-12-01

Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples, respectively. With blending thermoplastic starch and ethylene vinyl alcohol, some properties of thermoplastic starch such as degradation rate and water absorption were modified. In addition, using nanoforsterite as the ceramic reinforcing phase resulted in the improvement of mechanical and biological traits. The addition of nanoforsterite decreased the weight loss of the thermoplastic starch and ethylene vinyl alcohol blend in simulated body fluid. Moreover, this addition modified the pH in the MTT (methyl thiazolyl tetrazolium) assay and stimulated the cell proliferation. Cell adhesion assays indicated a favorable interaction between cells and the biomaterial. The proposed nanocomposite has appropriate biocompatibility, as well as mechanical properties in order to be used in bone tissue engineering. - Highlights: • A biodegradable nanocomposite is proposed for orthopedic applications. • Vitamin E is used as an antioxidant to prevent the thermomechanical degradations. • Nanoforsterite reduced the composite degradation rate in the simulated body fluid. • Nanoforsterite modified pH in MTT assay and stimulated cell proliferation.

Thermoplastic starch/ethylene vinyl alcohol/forsterite nanocomposite as a candidate material for bone tissue engineering

International Nuclear Information System (INIS)

Mahdieh, Zahra; Bagheri, Reza; Eslami, Masoud; Amiri, Mohammad; Shokrgozar, Mohammad Ali; Mehrjoo, Morteza

2016-01-01

Recently, biodegradable polymers such as starch based blends have been well renowned in the biomedical field. Studies have considered them suitable for bone scaffolds, bone cements, tissue engineering scaffolds, drug delivery systems and hydrogels. The aim of this study was to synthesize nanocomposite biomaterial consisting a blend of thermoplastic starch and ethylene vinyl alcohol as the polymer matrix, and nano-structured forsterite as the ceramic reinforcing phase for bone tissue engineering applications. Furthermore, vitamin E was applied as a thermal stabilizer during melt compounding. Extrusion and injection molding were incorporated for melt blending and shaping of samples, respectively. With blending thermoplastic starch and ethylene vinyl alcohol, some properties of thermoplastic starch such as degradation rate and water absorption were modified. In addition, using nanoforsterite as the ceramic reinforcing phase resulted in the improvement of mechanical and biological traits. The addition of nanoforsterite decreased the weight loss of the thermoplastic starch and ethylene vinyl alcohol blend in simulated body fluid. Moreover, this addition modified the pH in the MTT (methyl thiazolyl tetrazolium) assay and stimulated the cell proliferation. Cell adhesion assays indicated a favorable interaction between cells and the biomaterial. The proposed nanocomposite has appropriate biocompatibility, as well as mechanical properties in order to be used in bone tissue engineering. - Highlights: • A biodegradable nanocomposite is proposed for orthopedic applications. • Vitamin E is used as an antioxidant to prevent the thermomechanical degradations. • Nanoforsterite reduced the composite degradation rate in the simulated body fluid. • Nanoforsterite modified pH in MTT assay and stimulated cell proliferation.

Simulation of the kinetics of enzymic hydrolysis of starch in standard apparatus used in alcohol production

Energy Technology Data Exchange (ETDEWEB)

Rovinskii, L A; Yarovenko, V L

1977-01-01

A mathematical model is described for kinetics of enzymic hydrolysis of starch in standard apparatus used in alcohol fermentation. The apparatus with uniform mixing and displacement was highly superior compared with other apparatuses. Differences of temperature with the apparatus significantly affects the rate of starch hydrolysis compared with constant temperature.

Study of Biodegradability and Mechanical Properties of Polyvinyl Alcohol (PVA Reinforced Celloluse Nanofiber (CNF

Directory of Open Access Journals (Sweden)

shobo salehpour

2018-02-01

Full Text Available The aim of this study was to improve the properties of polyvinyl alcohol (PVA by using cellulose nanofibers (CNF as a reinforcement. In order to improve the compatibility and miscibility with PVA matrix, freeze drying method was applied. The nanocomposites based on PVA with values 5, 10, 20 and 30wt% of CNF were prepared by freeze-drying and the effect of CNF addition on the mechanical and dynamical mechanical properties, moisture sorption, barrier and biodegradability of the nanocomposites was studied. The tensile strength and elastic modulus of PVA films were improved by the addition of CNF. The nanocomposite with 10wt% nano-fibers had the highest tensile strength and lowest modulus of elasticity and the elongation at break. The results indicated that the storage modulus (E′ of PVA was considerably improved with the introduction of CNF into - polymer matrix. The water vapor permeability decreased from 7.31 to 2.1×10-7 g/m. h. Pa as the CNF percentage increased from 0 to 30%. Also the presence of cellulose nanofibers improved moisture sorption of polyvinyl alcohol. The weight loss of PVA films increased 60% with addition of 30wt% CNF after 90 days of exposure in soil

Poly(vinyl alcohol)/cellulose nanofibril hybrid aerogels with an aligned microtubular porous structure and their composites with polydimethylsiloxane

Science.gov (United States)

Tianliang Zhai; Qifeng Zheng; Zhiyong Cai; Lih-Sheng Turng; Hesheng Xia; Shaoqin Gong

2015-01-01

Superhydrophobic poly(vinyl alcohol) (PVA)/ cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning...

Graft Copolymerization of Styrene from Poly(vinyl alcohol via RAFT Process

Directory of Open Access Journals (Sweden)

Gholam Ali Koohmareh

2011-01-01

Full Text Available Polystyrene, PS, was grafted from poly(vinyl alcohol, PVA, backbone by reversible addition-fragmentation chain transfer (RAFT polymerization. The hydroxyl groups of the PVA were converted into aromatic dithioester RAFT agent and polymerization began in the presence of this agent. The structure of compounds was confirmed by FT-IR and 1HNMR spectroscopy. The graft copolymer was characterized by thermogravimetric analysis (TGA, X-ray diffraction (XRD, and scanning electron microscopy (SEM. Grafted polystyrene chains were cleaved from the PVA backbone by acidic hydrolysis of the PVA-g-PS, and its polydispersity index, PDI, was determined by gel permeation chromatography (GPC showing narrow molecular weight distribution.

Preparation and characterization of bioglass/polyvinyl alcohol composite hydrogel

International Nuclear Information System (INIS)

Xu Hong; Wang Yingjun; Zheng Yudong; Chen Xiaofeng; Ren Li; Wu Gang; Huang Xiaoshan

2007-01-01

In order to form firm active fixation with the adjacent bone, a new kind of bioactive composite hydrogel was prepared with polyvinyl alcohol (PVA) and bioglass (BG) through ultrasonic dispersion, heat-high-pressure and freeze/thawed technique. A digital speckle correlation method (DSCM) was utilized to characterize the mechanical properties of the series of BG/PVA composites. Results showed that at different load pressures, the composite hydrogel displayed different displacement and deformation in the V field. Results also showed that an increase of PVA percentage (15-30 wt%) or of bioglass percentage (2-10 wt%) in composite hydrogel could lead to an increase in the elastic compression modulus. Scanning electron microscope results indicated that bioglass was uniformly dispersed in the BG/PVA composite hydrogel. The BG/PVA composite hydrogel shows a promising prospect as a new bionic cartilage implantation material

Immobilization in polyvinyl alcohol hydrogel enhances yeast storage stability and reusability of recombinant laccase-producing S-cerevisiae

Czech Academy of Sciences Publication Activity Database

Herkommerová, Klára; Zemančíková, Jana; Sychrová, Hana; Antošová, Zuzana

2018-01-01

Roč. 40, č. 2 (2018), s. 405-411 ISSN 0141-5492 R&D Projects: GA TA ČR(CZ) TA01011461 Institutional support: RVO:67985823 Keywords : immobilization * laccase * LentiKats * polyvinyl alcohol hydrogel * reusability * storage stability * yeasts Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Industrial biotechnology Impact factor: 1.730, year: 2016

Ortho-positronium annihilation parameters in polyvinyl alcohol films with various degrees of polymerization, saponification and crystallinity

International Nuclear Information System (INIS)

Muramatsu, Hisakazu; Matsumoto, Kuniyuki; Minekawa, Sachiko; Yagi, Yukiko; Sasai, Shigenori

2001-01-01

Positron annihilation lifetime (PAL) spectroscopy has been applied to polyvinyl alcohol (PVA) films prepared with commercially available PVA or from polyvinyl acetate (PVac). The variation of lifetimes of ortho-positronium (o-Ps) formed in the films was investigated as a function of the degrees of polymerization, saponification, or crystallinity. For the fully saponificated samples, no dependence was found to exist on the degrees of polymerization or of crystallinity. For the partially saponificated samples, however, the dependence of the o-Ps lifetime on the degree of saponification was clearly observed, and this is explained by both the formation of hydrogen bonds among the polymer chains and the existence of acetyl group strongly inhibiting the hydrogen-bond formation due to steric hindrance. (orig.)

Optical and electronic properties of polyvinyl alcohol doped with pairs of mixed valence metal ions

International Nuclear Information System (INIS)

Bulinski, Mircea; Kuncser, Victor; Plapcianu, Carmen; Krautwald, Stefan; Franke, Hilmar; Rotaru, P; Filoti, George

2004-01-01

The electronic mechanisms induced by the UV exposure of thin films of polyvinyl alcohol doped with pairs of mixed valence metal ions were studied in relation to their optical behaviour by Moessbauer spectroscopy and optical absorption. The results obtained definitely point to the role of each element from the pair in the electronic mechanism involved, with influence on the optical properties regarding applications in real-time holography and integrated optics

Sorption of water vapor in partially hydrolyzed poly(vinyl acetate)

International Nuclear Information System (INIS)

Spencer, H.G.; Honeycutt, S.C.

1973-01-01

The sorption kinetics of H 2 O and D 2 O in copolymers of partially hydrolyzed poly(vinyl acetate) were studied and compared with the sorption kinetics of vinyl acetate--vinyl alcohol copolymers, and poly(vinyl alcohol). The special measurement problems presented by transient-state sorption studies in water vapor--polymer systems and their effects on the results are discussed

Voltage Effect in Holograms of Polyvinyl Alcohol with FeCl3

Directory of Open Access Journals (Sweden)

Arturo Olivares-Pérez

2014-03-01

Full Text Available We show experimentally that the metallic salt, FeCl3, at different concentrations, provides photosensitivity and conductivity characteristics with poly(vinyl alcohol material. The holographic recording in this photosensitive material was made in real time. The effect of applied voltage on holographic diffraction gratings in the recording process and the changes in their diffraction efficiency, depending on their composition, are shown. In addition, we describe the photo-mechanism, physicochemical processes, and water condensations involved in changes of the formation of images due to applied voltage. The results suggest that polymers doped with metallic salts may have potential as inexpensive photosensitive materials that are easy to work under normal laboratory condition.

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

International Nuclear Information System (INIS)

Jia Xin; Li Yanfeng; Zhang Bo; Cheng Qiong; Zhang Shujiang

2008-01-01

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement

Dancing on coke: smuggling cocaine dispersed in polyvinyl alcohol.

Science.gov (United States)

van Nuijs, Alexander L N; Maudens, Kristof E; Lambert, Willy E; Van Calenbergh, Serge; Risseeuw, Martijn D P; Van hee, Paul; Covaci, Adrian; Neels, Hugo

2012-01-01

Recent trends suggest that cocaine smugglers have become more and more inventive to avoid seizures of large amounts of cocaine transported between countries. We report a case of a mail parcel containing a dance pad which was seized at the Customs Department of Brussels Airport, Belgium. After investigation, the inside of the dance pad was found to contain a thick polymer, which tested positive for cocaine. Analysis was performed using a routine colorimetric swipe test, gas chromatography coupled with mass spectrometry and nuclear magnetic resonance spectroscopy. The polymer was identified as polyvinyl alcohol (PVA) and contained 18% cocaine, corresponding to a street value of € 20,000. Laboratory experiments showed that cocaine could be easily extracted from the PVA matrix. This case report reveals a new smuggling technique for the transportation of large amounts of cocaine from one country to another. © 2011 American Academy of Forensic Sciences.

Microwave Absorbent Packaging Material from Composites Chitosan-Polyvinyl Alcohol Polymer

Directory of Open Access Journals (Sweden)

Bambang - Riyanto

2014-11-01

Full Text Available Microwave absorbent packaging materials currently tend to biomaterial. Chitosan is a dielectric biomaterial with polycationic properties. The aim of this study was to analyze characteristics of microwave absorbing packaging material made from composite chitosan-polyvinyl alcohol (PVA polymer. The ability of the packaging material to absorb microwave was determined by reflection loss measurement. Formed packaging prototype resembles as a thin transparent yellowish plastic with thickness (0.11-0.22 mm and the tensile strength (106.33±2.82-143.00±2.59 kPa. SEM analysis showed homogenous structure characterized by interaction between chitosan and PVA. Optimum absorption value was obtained from chitosan concentration of 1%, with average value of reflection loss was (-31.9289±4.0094 dB.Keywords: chitosan, material packaging, microwave, reflection loss

Microwave Absorbent Packaging Material from Composites Chitosan-Polyvinyl Alcohol Polymer

Directory of Open Access Journals (Sweden)

Bambang - Riyanto

2015-07-01

Full Text Available Microwave absorbent packaging materials currently tend to biomaterial. Chitosan is a dielectric biomaterial with polycationic properties. The aim of this study was to analyze characteristics of microwave absorbing packaging material made from composite chitosan-polyvinyl alcohol (PVA polymer. The ability of the packaging material to absorb microwave was determined by reflection loss measurement. Formed packaging prototype resembles as a thin transparent yellowish plastic with thickness (0.11-0.22 mm and the tensile strength (106.33±2.82-143.00±2.59 kPa. SEM analysis showed homogenous structure characterized by interaction between chitosan and PVA. Optimum absorption value was obtained from chitosan concentration of 1%, with average value of reflection loss was (-31.9289±4.0094 dB.Keywords: chitosan, material packaging, microwave, reflection loss

Influence of kaolin addition on the dynamics of oxygen mass transport in polyvinyl alcohol dispersion coatings

OpenAIRE

Nyflött, Åsa; Axrup, Lars; Gunilla, Carlsson; Järnström, Lars; Lestelius, Magnus; Moons, Ellen; Wahlström, Torbjörn

2015-01-01

The permeability of dispersion barriers produced from polyvinyl alcohol (PVOH) and kaolin clay blends coated onto polymeric supports has been studied by employing two different measurement methods: the oxygen transmission rate (OTR) and the ambient oxygen ingress rate (AOIR). Coatings with different thicknesses and kaolin contents were studied. Structural information of the dispersion-barrier coatings was obtained by Fourier transform infrared spectroscopy (FTIR) spectroscopy and scanning ele...

A photo-crosslinked poly(vinyl alcohol) hydrogel growth factor release vehicle for wound healing applications

OpenAIRE

Bourke, Sharon L.; Al-Khalili, Mohammad; Briggs, Tonye; Michniak, Bozena B.; Kohn, Joachim; Poole-Warren, Laura A.

2003-01-01

The objective of this study was to develop and evaluate a hydrogel vehicle for sustained release of growth factors for wound healing applications. Hydrogels were fabricated using ultraviolet photo-crosslinking of acrylamide-functionalized nondegradable poly(vinyl alcohol) (PVA). Protein permeability was initially assessed using trypsin inhibitor (TI), a 21 000 MW model protein drug. TI permeability was altered by changing the solids content of the gel and by adding hydrophilic PVA fillers. As...

Polyvinyl alcohol composite nanofibres containing conjugated levofloxacin-chitosan for controlled drug release

International Nuclear Information System (INIS)

Jalvandi, Javid; White, Max; Gao, Yuan; Truong, Yen Bach; Padhye, Rajiv; Kyratzis, Ilias Louis

2017-01-01

A range of biodegradable drug-nanofibres composite mats have been reported as drug delivery systems. However, their main disadvantage is the rapid release of the drug immediately after application. This paper reports an improved system based on the incorporation of drug conjugated-chitosan into polyvinyl alcohol (PVA) nanofibers. The results showed that controlled release of levofloxacin (LVF) could be achieved by covalently binding LVF to low molecular weight chitosan (CS) via a cleavable amide bond and then blending the conjugated CS with polyvinyl alcohol (PVA) nanofibres prior to electrospinning. PVA/LVF and PVA-CS/LVF nanofibres were fabricated as controls. The conjugated CS-LVF was characterized by FTIR, DSC, TGA and 1 H NMR. Scanning electron microscopy (SEM) showed that the blended CS-PVA nanofibres had a reduced fibre diameter compared to the controls. Drug release profiles showed that burst release was decreased from 90% in the control PVA/LVF electrospun mats to 27% in the PVA/conjugated CS-LVF mats after 8 h in phosphate buffer at 37 °C. This slower release is due to the cleavable bond between LVF and CS that slowly hydrolysed over time at neutral pH. The results indicate that conjugation of the drug to the polymer backbone is an effective way of minimizing burst release behaviour and achieving sustained release of the drug, LVF. - Highlights: • A novel drug delivery system for controlled release of drug was designed. • Composite PVA/conjugated CS-LVF nanofibres was fabricated by electrospinning. • Conjugated chitosan and composite nanofibres were characterized by various techniques. • Release profiles of drug were significantly improved in composite nanofibres containing drug conjugated chitosan.

Polyvinyl alcohol composite nanofibres containing conjugated levofloxacin-chitosan for controlled drug release

Energy Technology Data Exchange (ETDEWEB)

Jalvandi, Javid, E-mail: Javid.jlv@gmail.com [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); White, Max, E-mail: tamrak@bigpond.com [School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); Gao, Yuan, E-mail: Yuan.Gao@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); Truong, Yen Bach, E-mail: Yen.truong@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia); Padhye, Rajiv, E-mail: rajiv.padhye@rmit.edu.au [School of Fashion and Textiles, College of Design and Social Context, RMIT University, 25 Dawson Street, Brunswick, Victoria 3056 (Australia); Kyratzis, Ilias Louis, E-mail: Louis.kyratzis@csiro.au [CSIRO, Manufacturing Flagship, Bayview Ave, Clayton, Victoria 3168 (Australia)

2017-04-01

A range of biodegradable drug-nanofibres composite mats have been reported as drug delivery systems. However, their main disadvantage is the rapid release of the drug immediately after application. This paper reports an improved system based on the incorporation of drug conjugated-chitosan into polyvinyl alcohol (PVA) nanofibers. The results showed that controlled release of levofloxacin (LVF) could be achieved by covalently binding LVF to low molecular weight chitosan (CS) via a cleavable amide bond and then blending the conjugated CS with polyvinyl alcohol (PVA) nanofibres prior to electrospinning. PVA/LVF and PVA-CS/LVF nanofibres were fabricated as controls. The conjugated CS-LVF was characterized by FTIR, DSC, TGA and {sup 1}H NMR. Scanning electron microscopy (SEM) showed that the blended CS-PVA nanofibres had a reduced fibre diameter compared to the controls. Drug release profiles showed that burst release was decreased from 90% in the control PVA/LVF electrospun mats to 27% in the PVA/conjugated CS-LVF mats after 8 h in phosphate buffer at 37 °C. This slower release is due to the cleavable bond between LVF and CS that slowly hydrolysed over time at neutral pH. The results indicate that conjugation of the drug to the polymer backbone is an effective way of minimizing burst release behaviour and achieving sustained release of the drug, LVF. - Highlights: • A novel drug delivery system for controlled release of drug was designed. • Composite PVA/conjugated CS-LVF nanofibres was fabricated by electrospinning. • Conjugated chitosan and composite nanofibres were characterized by various techniques. • Release profiles of drug were significantly improved in composite nanofibres containing drug conjugated chitosan.

Application of extrusion-cooking technique for foamed starch-based materials

Directory of Open Access Journals (Sweden)

Combrzyński Maciej

2018-01-01

Full Text Available Foamed materials are widely used, mainly as a protection objects during transport of various products. Traditionally foams are produced from plastics so they are very difficult for waste management. It is the challenge for many scientific centres to develop a technology for the production of bio-based materials which can be rapidly decomposed. The task for the researcher is to obtain a relatively cheap, easy to use and completely biodegradable materials. The aim of this work was the selection of the main raw materials, functional additives and process parameters to obtain the most effective parameters of extrusion-cooking process for foamed starch-based materials. Properties of the products and processing costs were taken into account. During the study, the extrusion-cooking process was performed under various conditions: temperature, humidity, type of the die, screw rotational speed, various raw materials and additives blends. The best results were obtained for mixtures based on potato starch and with addition the foaming agent Plastron foam PDE and poly(vinyl alcohol PVA.

Thermal stability of polyvinyl alcohol/nanocrystalline cellulose composites.

Science.gov (United States)

Voronova, Marina I; Surov, Oleg V; Guseinov, Sabir S; Barannikov, Vladimir P; Zakharov, Anatoly G

2015-10-05

Thermal stability of polyvinyl alcohol/cellulose nanocrystals (PVA/CNCs) composites prepared with solution casting technique was studied. The PVA/CNCs composites were characterized by Fourier transform infrared spectrometry, X-ray diffraction, differential scanning calorimeter (DSC) and thermogravimetric (TG) analysis. Due to the presence of CNCs nanoparticles, thermal degradation of the composites occurs at much higher temperatures compared to that of the neat PVA. Thermal stability of the PVA/CNCs composites is maximally enhanced with CNCs content of 8-12 wt%. Some thermal degradation products of the PVA/CNCs composites were identified by mass spectrometric analysis. TG measurements with synchronous recording of mass spectra revealed that the thermal degradation of both CNCs and PVA in the composites with CNCs content of 8-12 wt% occurs simultaneously at a much higher temperature than that of CNCs or the neat PVA. However, with increasing CNCs content more than 12 wt% the thermal stability of the composites decreases. In this case, the degradation of CNCs comes first followed by the degradation of PVA. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical and chemical properties of polyvinyl alcohol modified cement mortar with silica fume used as matrix including radioactive waste

International Nuclear Information System (INIS)

Dakroury, A. M.

2007-01-01

This paper discussed the mechanical and chemical properties of polyvinyl alcohol - modified cement mortar with silica fume to assess the safety for disposal of radioactive waste. The modified cement mortars containing polyvinyl alcohol (PVA) in the presence of 10 % silica fume (SF) .The chemical reaction between polymer and cement - hydrated product were investigated by the Infrared Spectral Technology, Differential Thermal Analysis and X-ray diffraction. The leaching of 137Cs from a waste composite into a surrounding fluid has been studied .The results shown that PVA increases the strength and decreases the porosity. The increase in strength duo to the interaction of PVA with cement , may be forming some new compound that fill the pores or improve the bond between the cement . The pozzolanic reaction of the SF increases the calcium silicate hydrates in the hardening matrix composites. There is distinct change in the refinement of the pore structure in cement composites giving fewer capillary pores and more of the finer gel pores

Polyvinyl alcohol (PVA)-cellulose nanofibril (CNF)-multiwalled carbon nanotube (MWCNT) hybrid organic aerogels with superior mechanical properties

Science.gov (United States)

Qifeng Zheng; Alireza Javadi; Ronald Sabo; Zhiyong Cai; Shaoqin Gong

2013-01-01

Polyvinyl alcohol (PVA)–cellulose nanofibril (CNF)–multiwalled carbon nanotube (MWCNT) hybrid organic aerogels were prepared using an environmentally friendly freeze-drying process with renewable materials. The material properties of these “green” hybrid aerogels were characterized extensively using various techniques. It was found that adding a small amount of CNFs...

Polyvinyl-alcohol-based magnetic beads for rapid and efficient separation of specific or unspecific nucleic acid sequences

International Nuclear Information System (INIS)

Oster, J.; Parker, Jeffrey; Brassard, Lothar

2001-01-01

The versatile application of polyvinyl-alcohol-based magnetic M-PVA beads is demonstrated in the separation of genomic DNA, sequence specific nucleic acid purification, and binding of bacteria for subsequent DNA extraction and detection. It is shown that nucleic acids can be obtained in high yield and purity using M-PVA beads, making sample preparation efficient, fast and highly adaptable for automation processes

Preparation and characterization of jackfruit seed starch/poly (vinyl alcohol) (PVA) blend film

Science.gov (United States)

Sarifuddin, N.; Shahrim, N. A.; Rani, N. N. S. A.; Zaki, H. H. M.; Azhar, A. Z. A.

2018-01-01

From the environmental point of view, biodegradable materials have been rapidly developed in the past years. PVA is one of the biodegradable synthetic polymers commonly used, but its degradation rate is slow. As an alternative to reduce plastic waste and accelerate the degradation process, PVA frequently blended with other natural polymers to improve its biodegradability. The natural polymer such as starch has high potential in enhancing PVA biodegradability by blending both components. The usage of starch extracted from agriculture wastes such as jackfruit seed is quite promising. In this study, jackfruit seed starch (JFSS)/poly (vinyl alcohol) (PVA) blend films were prepared using the solution casting method. The effect of starch content on the mechanical (tensile strength and elongation to break %) and physical properties of the tested films were investigated. The optimum tensile strength was obtained at 10.45 MPa when 4 wt. % of starch added to the blend. But, decreasing trend of tensile strength was found upon increasing the amount of starch beyond 4 wt. % in starch/PVA blend films. Nevertheless, elongation at break decreases with the increase in starch content. The mechanical properties of the blend films are supported by the Field Emission Scanning Electron Microscopy (FESEM), in which the native JFSS granules are wetted by PVA continuous phase with good dispersion and less agglomeration. The incorporation of JFSS in PVA has also resulted in the appearance of hydrogen bond peak, which evidenced by Fourier Transform Infrared (FTIR). Additionally, the biodegradation rate of JFSS/PVA was evaluated through soil burial test.

Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles

Science.gov (United States)

Hejri, Zahra; Seifkordi, Ali Akbar; Ahmadpour, Ali; Zebarjad, Seyed Mojtaba; Maskooki, Abdolmajid

2013-10-01

Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO2) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO2 nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO2 nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO2 films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films.

In vitro and ex vivo hemocompatibility of off-the-shelf modified poly(vinyl alcohol) vascular grafts

OpenAIRE

Cutiongco, Marie Francene A.; Anderson, Deirdre E. J.; Hinds, Monica T.; Yim, Evelyn K. F.

2015-01-01

Synthetic small diameter vascular grafts with mechanical properties of native arteries, resistance to thrombosis and capacity to stimulate in situ endothelialization are an unmet clinical need. Poly(vinyl alcohol) hydrogel (PVA) is an excellent candidate as a vascular graft due to its tunable mechanical properties. However, the hydrophilicity and bio-inertness of PVA prevents endothelialization in vivo. We hypothesize that the modification of PVA with biomolecules and topographies creates a h...

Method of cross-linking polyvinyl alcohol and other water soluble resins

Science.gov (United States)

Phillipp, W. H.; May, C. E.; Hsu, L. C.; Sheibley, D. W. (Inventor)

1980-01-01

A self supporting sheet structure comprising a water soluble, noncrosslinked polymer such as polyvinyl alcohol which is capable of being crosslinked by reaction with hydrogen atom radicals and hydroxyl molecule radicals is contacted with an aqueous solution having a pH of less than 8 and containing a dissolved salt in an amount sufficient to prevent substantial dissolution of the noncrosslinked polymer in the aqueous solution. The aqueous solution is then irradiated with ionizing radiation to form hydrogen atom radicals and hydroxyl molecule radicals and the irradiation is continued for a time sufficient to effect crosslinking of the water soluble polymer to produce a water insoluble polymer sheet structure. The method has particular application in the production of battery separators and electrode envelopes for alkaline batteries.

Utilization of Cellulose from Pineapple Leaf Fibers as Nanofiller in Polyvinyl Alcohol-Based Film

Directory of Open Access Journals (Sweden)

Kendri Wahyuningsih

2016-08-01

Full Text Available Cellulose from pineapple leaf fibers as one of the natural polymer which has biodegradable property in a nanometer’s scale, can be formed as a filler in composite of Poly(vinyl Alcohol/PVA is expected to increase the physical, thermal, and barrier properties of composite films similar to conventional plastic. The aim of this study was to examine the effect of fibrillation of cellulose fibers from pineapple leaf fibers using a combined technique of chemical-mechanical treatments, to investigate the reinforcing effect of concentration of nanocellulose fibrils in the polyvinyl alcohol (PVA matrix on physical properties, thermal properties, water vapor transmission rate, light transmittance and morphological with and without addition of glycerol. Nanocellulose was made from cellulose of pineapple leaf fiber using wet milling (Ultra Fine Grinder. The composite film production was carried out by using casting solution method by mixing PVA solution with nanocellulose (10-50% and glycerol (0-1%. The characterization of film covered physical properties (thickness, moisture content and density, thermal properties, permeability (WVTR, light transmittance, morphology, and crystallinity. Nanocellulose from pineapple leaf fibers was produced by Ultra Fine Grinder shows that the size reduction process was accurate. Nanocellulose addition on PVA composite film was affected to increasing the physical, thermal, and barrier properties. Meanwhile, decreasing the percentage of composite film transmittance, thus the transparency decrease (opaque. Water vapor transmission rate (WVTR the film was increased with increasing glycerol concentration, but the physical and thermal properties was decreased.

Preparation and properties of polyvinyl alcohol microspheres

International Nuclear Information System (INIS)

Campbell, J.H.; Grens, J.Z.; Poco, J.F.; Ives, B.H.

1986-06-01

Polyvinyl alcohol (PVA) microspheres, having a size range of ∼150- to 250-μm diameter with 1- to 5-μm wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report

The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

Science.gov (United States)

Pirahmadi, Pegah; Kokabi, Mehrdad

2018-01-01

Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

Preparation of poly(vinyl alcohol) membranes grafted with N-vinyl imidazole/acrylic acid binary monomers

International Nuclear Information System (INIS)

Ajji, Zaki; Ali, Ali

2006-01-01

Poly(vinyl alcohol) films were grafted with two monomers using gamma radiation, acrylic acid and N-vinyl imidazole. The influence of different parameters on the grafting yield was investigated as: type of solvent and solvent composition, comonomer concentration and composition, addition of mineral acids, and irradiation dose. Water uptake in respect to the grafting yield was also evaluated. The ability of the grafted films to adsorb copper ions was elaborated and discussed for different grafting yields and ph values of the solution. (authors)

Synthesis and characterization of CdxMn1-xS nanoparticles stabilized with poly(vinyl alcohol)

International Nuclear Information System (INIS)

Schatkoski, Vanessa M.; Mansur, Alexandra A.P.; Mansur, Herman S.; Gonzalez, Juan C.

2011-01-01

Colloidal luminescent semiconductor nanocrystals, also known as quantum dots, have attracted considerable attention due to their significant potential application. The doping of nanocrystalline semiconductors with divalent manganese ions results in new optical properties of these semimagnetic semiconductor quantum dots. In this work we report the synthesis and characterization Cd x Mn 1-x S nanoparticles using poly(vinyl alcohol) as stabilizing agent. Different fractions of Cd 2+ /Mn 2+ ions were investigated aiming the production of stable nanoparticles with different photoluminescence properties. (author)

Properties of poly(vinyl alcohol)-borax gel doped with neodymium and praseodymium

International Nuclear Information System (INIS)

Lawrence, Mathias B.; Desa, J.A.E.; Rai, Renu; Aswal, V.K.

2014-01-01

Neodymium and praseodymium ions, singly and in combination, have been doped into a poly(vinyl alcohol)-borax matrix. X-ray diffraction shows structural correlations from 2 to 6 Å and 15 Å, while small angle neutron scattering indicates that the rare-earth ions do not affect the nanoscale structures of the gels. Differential scanning calorimetry shows the glass transition temperature to increase with concentration of Pr in the gel. Excitation in the ultraviolet region leads to luminescent emission in the visible region. Simultaneous absorption in the visible region then leads to luminescent emission in the near infra-red region. The spectral qualities of the emission bands can be varied by choosing appropriate relative ratios of rare-earth species. (author)

Photo-triggered release from liposomes without membrane solubilization, based on binding to poly(vinyl alcohol) carrying a malachite green moiety.

Science.gov (United States)

Uda, Ryoko M; Kato, Yutaka; Takei, Michiko

2016-10-01

When working with liposomes analogous to cell membranes, it is important to develop substrates that can regulate interactions with the liposome surface in response to light. We achieved a photo-triggered release from liposomes by using a copolymer of poly(vinyl alcohol) carrying a malachite green moiety (PVAMG). Although PVAMG is a neutral polymer under dark conditions, it is photoionized upon exposure to UV light, resulting in the formation of a cationic site for binding to liposomes with a negatively charged surface. Under UV irradiation, PVAMG showed effective interaction with liposomes, releasing the encapsulated compound; however, this release was negligible under dark conditions. The poly(vinyl alcohol) moiety of PVAMG played an important role in the photo-triggered release. This release was caused by membrane destabilization without lipid solubilization. We also investigated different aspects of liposome/PVAMG interactions, including PVAMG-induced fusion between the liposomes and the change in the liposome morphologies. Copyright © 2016 Elsevier B.V. All rights reserved.

Tailoring the properties of thermoplastic starch by blending with cinnamyl alcohol and radiation processing: An insight into the competitive grafting and scission reactions

International Nuclear Information System (INIS)

Khandal, Dhriti; Mikus, Pierre-Yves; Dole, Patrice; Bliard, Christophe; Soulestin, Jérémie; Lacrampe, Marie-France; Baumberger, Stéphanie; Coqueret, Xavier

2012-01-01

The present paper focuses on the effects of electron beam (EB) irradiation on thermoplastic materials based on destructurized starch including glycerol and water as plasticizers to assess the potentiality of cinnamyl alcohol as reactive additive capable of counterbalancing the degradation of the polysaccharide by inducing interchain covalent linkages. The tensile properties at break of test specimens of controlled composition submitted to EB irradiation at doses ranging from 50 to 200 kGy revealed the presence of competitive chain scission and bridging in samples containing cinnamyl alcohol at a relative concentration of 2.5% with regard to dry starch. The occurrence of crosslinking under particular conditions was evidenced by gel fraction measurements. The treatment under radiation was also applied to model blends including maltodextrin as a model for starch and the other ingredients to gain an insight into the radiation induced mechanisms at the molecular level. The presence of cinnamyl alcohol is found to limit degradation. Size exclusion chromatography and gel fraction allowed to monitor the effects and confirmed unambiguously the attachment of UV-absorbing chromophores onto the maltodextrin main chain. The combination of the obtained results demonstrates the possibility of altering in a favorable way the tensile properties of plasticized starch by applying high energy radiation to properly formulated blends including aromatic compounds like cinnamyl alcohol. - Highlights: ► Assessment of the potentiality of cinnamyl alcohol as an additive capable of counterbalancing the degradation of the polysaccharide. ► Tensile properties of test specimens of controlled composition submitted to EB irradiation revealed the presence of competitive chain scission and bridging in samples containing 2.5 wt% cinnamyl alcohol. ► Gel fraction measurements confirmed that grafting was overcoming chain scission. ► Possibility of altering in a favorable way the tensile

Sliding friction at poly(vinyl alcohol)-modified carbon nanotube interfaces

Science.gov (United States)

Zhang, Xiaohua

2018-01-01

The sliding friction between adjacent carbon nanotubes (CNTs) determines greatly the mechanical property of CNT assembly materials. In order to enhance the intertube friction, polymer molecules are often introduced between CNTs. This paper reveals a new energy dissipation mechanism for the deformed CNT contacts by poly(vinyl alcohol) (PVA). When PVA is introduced into a CNT bundle, most segments of the polymer chain lay on the grooves of adjacent CNTs, while several short segments span over the contact CNTs by inducing a structural deformation on the tubular structure. During the tube sliding, the deformation is recovered and a new one is formed at the next position, contributing to new energy dissipation to prevent the tube sliding. As a result, the friction force can be enhanced by up to eight-fold. This study indicates that a network of transverse polymer chains and longitudinal CNTs is important towards high mechanical properties.

Formation of inorganic nanofibers by heat-treatment of poly(vinyl alcohol-zirconium compound hybrid nanofibers

Directory of Open Access Journals (Sweden)

Nakane K.

2013-01-01

Full Text Available Poly(vinyl alcohol-zirconium compound hybrid nanofibers (precursors were formed by electrospinning employing water as a solvent for the spinning solution. The precursors were converted into oxide (ZrO2, carbide (ZrC or nitride (ZrN nanofibers by heating them in air, Ar or N2 atmospheres. Monoclinic ZrO2 nanofibers with high-specific surface area were obtained by heat-treatment of the precursors in air. ZrC and ZrN nanofibers could be obtained below theoretical temperatures calculated from thermodynamics data.

Studies on nonlocal optical nonlinearity of Sr–CuO–polyvinyl alcohol nanocomposite thin films

International Nuclear Information System (INIS)

Tamgadge, Y.S.; Talwatkar, S.S.; Sunatkari, A.L.; Pahurkar, V.G.; Muley, G.G.

2015-01-01

Thermally induced nonlocal nonlinear optical properties of strontium (Sr) doped CuO-polyvinyl alcohol (PVA) nanocomposite thin films under continuous wave Helium–Neon laser illumination are investigated by single beam Z-scan method. Undoped and Sr doped CuO nanoparticles (NPs) using L-arginine as surface modifying agent have been synthesized by wet chemical method and their thin films with PVA as host matrix have been obtained by spin coating technique. Structure, morphology and purity of prepared CuO NPs and thin films have been studied by X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscopy and energy dispersive X-ray absorption spectroscopy. Fourier transform infra-red spectrum attests the role of L-arginine as surface modifier and ultraviolet–visible absorption studies reveal that the excitonic absorption wavelengths are blue shifted for strontium doped CuO NPs. Sr doped CuO NPs with average particle size of 7 nm and calculated optical band gap up to 2.54 eV have been reported. All Sr doped CuO–PVA nanocomposite thin films show enhanced nonlinear refraction and absorption best suited for optical limiting applications. Observed effects have been attributed to thermal lensing effect. - Highlights: • Pure and strontium doped CuO–polyvinyl alcohol nanocomposite thin films are prepared. • Z-scan studies of thin films are performed under continuous wave helium–neon laser. • Enhanced values of third order nonlinear optical coefficients are obtained for all films. • Thermally induced self-defocusing and reverse saturable absorption have been discussed.

Studies on nonlocal optical nonlinearity of Sr–CuO–polyvinyl alcohol nanocomposite thin films

Energy Technology Data Exchange (ETDEWEB)

Tamgadge, Y.S. [Department of Physics, Mahatma Fule Arts, Commerce and S C Science Mahavidyalaya, Warud, Dist. Amravati (MS), 444906 (India); Talwatkar, S.S. [Department of Physics, D K Marathe and N G Acharya College, Chembur, Mumbai (MS) 440071 (India); Sunatkari, A.L. [Department of Physics, Siddharth College of Arts, Science and Commerce, Fort, Mumbai (MS) 440001 (India); Pahurkar, V.G. [Department of Physics, Sant Gadge Baba Amravati University, Amravati (MS), 444602 (India); Muley, G.G., E-mail: gajananggm@yahoo.co.in [Department of Physics, Sant Gadge Baba Amravati University, Amravati (MS), 444602 (India)

2015-11-30

Thermally induced nonlocal nonlinear optical properties of strontium (Sr) doped CuO-polyvinyl alcohol (PVA) nanocomposite thin films under continuous wave Helium–Neon laser illumination are investigated by single beam Z-scan method. Undoped and Sr doped CuO nanoparticles (NPs) using L-arginine as surface modifying agent have been synthesized by wet chemical method and their thin films with PVA as host matrix have been obtained by spin coating technique. Structure, morphology and purity of prepared CuO NPs and thin films have been studied by X-ray diffraction, high-resolution transmission electron microscopy, field emission scanning electron microscopy and energy dispersive X-ray absorption spectroscopy. Fourier transform infra-red spectrum attests the role of L-arginine as surface modifier and ultraviolet–visible absorption studies reveal that the excitonic absorption wavelengths are blue shifted for strontium doped CuO NPs. Sr doped CuO NPs with average particle size of 7 nm and calculated optical band gap up to 2.54 eV have been reported. All Sr doped CuO–PVA nanocomposite thin films show enhanced nonlinear refraction and absorption best suited for optical limiting applications. Observed effects have been attributed to thermal lensing effect. - Highlights: • Pure and strontium doped CuO–polyvinyl alcohol nanocomposite thin films are prepared. • Z-scan studies of thin films are performed under continuous wave helium–neon laser. • Enhanced values of third order nonlinear optical coefficients are obtained for all films. • Thermally induced self-defocusing and reverse saturable absorption have been discussed.

Incorporation of a Cationic Conjugated Polyelectrolyte CPE within an Aqueous Poly(vinyl alcohol) Sol

DEFF Research Database (Denmark)

Knaapila, Matti; Stewart, Beverly; Costa, Telma

2016-01-01

We report on a multiscale polymer-within-polymer structure of the cationic conjugated polyelectrolyte poly{[9,9-bis(6-N,N,N-trimethylammonium)hexyl]fluorene phenylene} (HTMAPFP) in aqueous poly(vinyl alcohol).(PVA) sol. Molecular dynamics simulations and small-angle neutron scattering (SANS) data...... show that HTMA-PFP forms aggregates in water but becomes entangled by PVA (with a 1:1 molar ratio of HTMA-PFP to PVA) and eventually immersed in PVA clusters (with the ratio 1:4). This is attributed to the hydrophobic hydrophilic balance. Contrast variation data with regular and deuterated PVA support...

Modification of polyvinyl alcohol surface properties by ion implantation

Energy Technology Data Exchange (ETDEWEB)

Pukhova, I.V., E-mail: ivpuhova@mail.ru [National Research Tomsk State University, 36 Lenin Ave, Tomsk 634050 (Russian Federation); Institute of High Current Electronics, 2/3 Akademichesky Ave, Tomsk 634055 (Russian Federation); Kurzina, I.A. [National Research Tomsk State University, 36 Lenin Ave, Tomsk 634050 (Russian Federation); Savkin, K.P. [Institute of High Current Electronics, 2/3 Akademichesky Ave, Tomsk 634055 (Russian Federation); Laput, O.A. [National Research Tomsk Polytechnic University, 30 Lenin Ave, Tomsk 634050 (Russian Federation); Oks, E.M. [Institute of High Current Electronics, 2/3 Akademichesky Ave, Tomsk 634055 (Russian Federation)

2017-05-15

We describe our investigations of the surface physicochemical properties of polyvinyl alcohol modified by silver, argon and carbon ion implantation to doses of 1 × 10{sup 14}, 1 × 10{sup 15} and 1 × 10{sup 16} ion/cm{sup 2} and energies of 20 keV (for C and Ar) and 40 keV (for Ag). Infrared spectroscopy (IRS) indicates that destructive processes accompanied by chemical bond (−C=O) generation are induced by implantation, and X-ray photoelectron spectroscopy (XPS) analysis indicates that the implanted silver is in a metallic Ag3d state without stable chemical bond formation with polymer chains. Ion implantation is found to affect the surface energy: the polar component increases while the dispersion part decreases with increasing implantation dose. Surface roughness is greater after ion implantation and the hydrophobicity increases with increasing dose, for all ion species. We find that ion implantation of Ag, Ar and C leads to a reduction in the polymer microhardness by a factor of five, while the surface electrical resistivity declines modestly.

Time domain NMR evaluation of poly(vinyl alcohol) xerogels

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Elton Jorge da Rocha; Cavalcante, Maxwell de Paula; Tavares, Maria Ines Bruno, E-mail: mibt@ima.ufrj.br [Universidade Federal do Rio de Janeiro (IMA/UFRJ), Rio de Janeiro, RJ (Brazil). Centro de Tecnologia. Instituto de Macromoleculas Professora Eloisa Mano

2016-05-15

Poly(vinyl alcohol) (PVA)-based chemically cross-linked xerogels, both neat and loaded with nanoparticulate hydrophilic silica (SiO{sub 2}), were obtained and characterized mainly through time domain NMR experiments (TD-NMR). Fourier-transform infrared (FT-IR) and wide angle X-ray diffraction (WAXD) analyses were employed as secondary methods. TD-NMR, through the interpretation of the spin-lattice relaxation constant values and related information, showed both cross-linking and nanoparticle influences on PVA matrix. SiO{sub 2} does not interact chemically with the PVA chains, but has effect on its molecular mobility, as investigated via TD-NMR. Apparent energy of activation, spin-lattice time constant and size of spin domains in the sample have almost linear dependence with the degree of cross-linking of the PVA and are affected by the addition of SiO{sub 2}. These three parameters were derived from a single set of TD-NMR experiments, which demonstrates the versatility of the technique for characterization of inorganic-organic hybrid xerogels, an important class of materials. (author)

Efficient etching-free transfer of high quality, large-area CVD grown graphene onto polyvinyl alcohol films

International Nuclear Information System (INIS)

Marta, Bogdan; Leordean, Cosmin; Istvan, Todor; Botiz, Ioan; Astilean, Simion

2016-01-01

Graphical abstract: - Highlights: • One-step dry transfer method of CVD grown graphene onto PVA films. • Investigation of graphene quality and number of layers of the synthesized and transferred graphene. • Promising scalability and good quality of transferred graphene onto flexible transparent polymers. - Abstract: Graphene transfer is a procedure of paramount importance for the production of graphene-based electronic devices. The transfer procedure can affect the electronic properties of the transferred graphene and can be detrimental for possible applications both due to procedure induced defects which can appear and due to scalability of the method. Hence, it is important to investigate new transfer methods for graphene that are less time consuming and show great promise. In the present study we propose an efficient, etching-free transfer method that consists in applying a thin polyvinyl alcohol layer on top of the CVD grown graphene on Cu and then peeling-off the graphene onto the polyvinyl alcohol film. We investigate the quality of the transferred graphene before and after the transfer, using Raman spectroscopy and imaging as well as optical and atomic force microscopy techniques. This simple transfer method is scalable and can lead to complete transfer of graphene onto flexible and transparent polymer support films without affecting the quality of the graphene during the transfer procedure.

Efficient etching-free transfer of high quality, large-area CVD grown graphene onto polyvinyl alcohol films

Energy Technology Data Exchange (ETDEWEB)

Marta, Bogdan; Leordean, Cosmin [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Istvan, Todor [Babes-Bolyai University, Faculty of Physics, Biomolecular Physics Department, M Kogalniceanu Str. 1, Cluj-Napoca 400084 (Romania); Botiz, Ioan [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Astilean, Simion, E-mail: simion.astilean@phys.ubbcluj.ro [Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Treboniu Laurian Str. 42, Cluj-Napoca 400271 (Romania); Babes-Bolyai University, Faculty of Physics, Biomolecular Physics Department, M Kogalniceanu Str. 1, Cluj-Napoca 400084 (Romania)

2016-02-15

Graphical abstract: - Highlights: • One-step dry transfer method of CVD grown graphene onto PVA films. • Investigation of graphene quality and number of layers of the synthesized and transferred graphene. • Promising scalability and good quality of transferred graphene onto flexible transparent polymers. - Abstract: Graphene transfer is a procedure of paramount importance for the production of graphene-based electronic devices. The transfer procedure can affect the electronic properties of the transferred graphene and can be detrimental for possible applications both due to procedure induced defects which can appear and due to scalability of the method. Hence, it is important to investigate new transfer methods for graphene that are less time consuming and show great promise. In the present study we propose an efficient, etching-free transfer method that consists in applying a thin polyvinyl alcohol layer on top of the CVD grown graphene on Cu and then peeling-off the graphene onto the polyvinyl alcohol film. We investigate the quality of the transferred graphene before and after the transfer, using Raman spectroscopy and imaging as well as optical and atomic force microscopy techniques. This simple transfer method is scalable and can lead to complete transfer of graphene onto flexible and transparent polymer support films without affecting the quality of the graphene during the transfer procedure.

Investigations on electrostatic dissipative materials derived from Poly(vinyl alcohol/ferrofluid composites

Directory of Open Access Journals (Sweden)

Winatthakan Phuchaduek

2013-10-01

Full Text Available Biodegradable polymer composites based on polyvinyl alcohol (PVA and ferrofluid (FF were prepared by solutioncasting method. Such composites were characterized by various methods in order to evaluate their potential for use as elec-trostatic dissipative (ESD materials. Effects of ferrofluid content on mechanical, thermal, and electrical properties of thecomposites were investigated. The morphology of the composites was examined by SEM and the water contact angle on thecomposite surface was also measured. Experimental results showed that surface resistivity of the composites can be reducedby the addition of FF. The abrupt transition of such resistivity occurred in the concentration range 20-30 wt.% FF. Theconductive mechanism of the proposed composites is a complex manner, including contact conduction and tunnelingconduction.

High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism.

Science.gov (United States)

Han, Jingquan; Lei, Tingzhou; Wu, Qinglin

2014-02-15

Cellulose nanoparticle (CNP) reinforced polyvinyl alcohol-borax (PB) hydrogels were produced via a facile approach in an aqueous system. The effects of particle size, aspect ratio, crystal structure, and surface charge of CNPs on the rheological properties of the composite hydrogels were investigated. The rheological measurements confirmed the incorporation of well-dispersed CNPs to PB system significantly enhanced the viscoelasticity and stiffness of hydrogels. The obtained free-standing, high elasticity and mouldable hydrogels exhibited self-recovery under continuous step strain and thermo-reversibility under temperature sweep. With the addition of cellulose I nanofibers, a 19-fold increase in the high-frequency plateau of storage modulus was obtained compared with that of the pure PB. CNPs acted as multifunctional crosslinking agents and nanofillers to physically and chemically bridge the 3D network hydrogel. The plausible mechanism for the multi-complexation between CNPs, polyvinyl alcohol and borax was proposed to understand the relationship between the 3D network and hydrogel properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of PVA(Polyvinyl Alcohol) on Supercooling Phenomena of Water

Science.gov (United States)

Kumano, Hiroyuki; Saito, Akio; Okawa, Seiji; Takizawa, Hiroshi

In this paper, effects of polymer additive on supercooling of water were investigated experimentally. Poly-vinyl alcohol (PVA) were used as the polymer, and the samples were prepared by dissolving PVA in ultra pure water. Concentration, degree of polymerization and saponification of PVA were varied as the experimental parameters. The sample was cooled, and the temperature at the instant when ice appears was measured. Since freezing of supercooled water is statistical phenomenon, many experiments were carried out and average degrees of supercooling were obtained for each experimental condition. As the result, it was found that PVA affects nucleation of supercooling and the degree of supercooling increases by adding the PVA. Especially, it is found that the average degree of supercooling increases and the standard deviation of average degree of supercooling decreases with increase of degree of saponification of PVA. However, the average degree of supercooling are independent of the degree of polymerization of PVA in the range of this study.

Effects of poly-vinyl alcohol on supercooling phenomena of water

Energy Technology Data Exchange (ETDEWEB)

Kumano, Hiroyuki; Hirata, Tetsuo; Kudoh, Tomoya [Department of Mechanical Systems Engineering, Shinshu University, 4-17-1, Wakasato, Nagano City, 380-8553 (Japan)

2009-05-15

The effects of a polymer additive on the supercooling of water were investigated experimentally. Poly-vinyl alcohols (PVAs) were used as the additives, and samples were prepared by dissolving the PVA in water. Since the characteristics of PVA are decided by its degrees of polymerization and saponification, these were varied along with the concentration as the experimental parameters. Moreover, the effect of purity of the water was also considered. Each sample was cooled and the temperature at the instant when ice appeared was measured. Since the freezing of supercooled water is a statistical phenomenon, many experiments were carried out and the average degree of supercooling was obtained. It was found that PVA affects the nucleation of ice in supercooled water and the degree of supercooling increases with the addition of PVA even for water with low purity. The average degree of supercooling increases with an increase in the degree of saponification of PVA. (author)

Mechanical, Thermal, and Microstructural Analysis of Polyvinyl Alcohol/Montmorillonite Nanocomposites

Directory of Open Access Journals (Sweden)

P. G. Allison

2015-01-01

Full Text Available Structural biomaterials such as nacre, bone, and fish scales possess unique structures that have hierarchical spatial configurations, which provide excellent mechanical properties when compared to their individual constituents. These observations have been the motivation for designing and characterizing bioinspired materials with high strength, high stiffness, and corrosion-resistant properties while at the same time being environmentally friendly. It has been demonstrated that polymer-clay nanocomposites can simulate the behavior of nacreous biomaterials such as abalone shell. Mechanical, thermal, and microstructural analyses characterized solution-cast polyvinyl alcohol (PVA/montmorillonite (MMT nanocomposite properties over compositions ranging from the neat polymer to 25% volume fraction of MMT nanoclay. Uniaxial tensile experiments were performed at displacement rates of 1 mm/min and 50 mm/min. Strength values are similar to those shown by nacre and represent a homogeneous dispersion of the MMT in the polymer matrix. Strength-to-weight ratios are similar to many structural metals.

Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol)-acrylate monomer blends

International Nuclear Information System (INIS)

Koshiba, M.; Yamaoka, T.; Tsunoda, T.

1983-01-01

Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol) (PVA)-monoacrylate blends were investigated by measuring dynamic shear modulus G' and loss tangent, tan delta. The dynamic mechanical properties of the blends before being exposed to UV irradiation were governed by the weight percent of the monomers which act as plasticizers. On the other hand, the UV-irradiated blends seemed to be typical two-phase materials since they revealed two tan delta maxima whose positions were independent of the monomer content. Those two maxima were assigned to PVA and photopolymerized acrylates with reference to the dynamic mechanical data of PVA and a PVA-polyacrylamide polyblend. Those dynamic mechanical data suggested that insolubilization of the blend type photopolymers should be caused by a decrease in solubility due to graft polymerization of acrylate monomers onto PVA. 9 figures, 3 tables

Polymer and Water Dynamics in Poly(vinyl alcohol/Poly(methacrylate Networks. A Molecular Dynamics Simulation and Incoherent Neutron Scattering Investigation

Directory of Open Access Journals (Sweden)

Ester Chiessi

2011-10-01

Full Text Available Chemically cross-linked polymer networks of poly(vinyl alcohol/poly(methacrylate form monolitic hydrogels and microgels suitable for biomedical applications, such as in situ tissue replacement and drug delivery. In this work, molecular dynamics (MD simulation and incoherent neutron scattering methods are used to study the local polymer dynamics and the polymer induced modification of water properties in poly(vinyl alcohol/poly(methacrylate hydrogels. This information is particularly relevant when the diffusion of metabolites and drugs is a requirement for the polymer microgel functionality. MD simulations of an atomic detailed model of the junction domain at the experimental hydration degree were carried out at 283, 293 and 313 K. The polymer-water interaction, the polymer connectivity and the water dynamics were investigated as a function of temperature. Simulation results are compared with findings of elastic and quasi-elastic incoherent neutron scattering measurements, experimental approaches which sample the same space-time window of MD simulations. This combined analysis shows a supercooled water component and an increase of hydrophilicity and mobility with temperature of these amphiphilic polymer networks.

Gamma irradiation Effect on the Non-Crosslinked and Crosslinked Poly(vinyl alcohol) Films

International Nuclear Information System (INIS)

El-Sawy, N.M.; El-Arnaouty, M.B.; Abdel Ghaffar, A.M.

2008-01-01

The non-crosslinked and crosslinked poly(vinyl alcohol) (PVA) films were prepared by the cast method then irradiated with gamma rays for various doses up to 300 kGy. The structure and characterization of PVA were determined by using Infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV). Swelling behaviour was also investigated. Mechanical properties have been examined with respect to the absorbed dose. The color of the films changed to yellowish-white after irradiation. Additional changes were observed using FTIR analysis on the degradation products demonstrated that the radiolysis of PVA was initiated by liberation of H and OH groups leading to scission of the main chains and formation of carbonyl and double bond groups. Thermogravimetric analysis (TGA) was performed

Potential Application of Gamma Irradiated Polyvinyl Pyrrolidone (PVP) - Starch Hydrogel As Fever Cooling Plaster

International Nuclear Information System (INIS)

Darmawan Darwis; Lely Hardiningsih

2010-01-01

Research on the development of hydrogel for cooling fever by using gamma irradiation technique has been done. The hydrogel was prepared by irradiating the mixture of PVP with concentration of 7% (w/v) and starch with various concentrations using gamma ray at irradiation dose of 20 to 40 kGy. The results showed that optimum starch concentration to make solid constituent of PVP-starch prior to irradiation were 10-15%. Gel fraction of PVP-starch hydrogel showed an increase by increasing of irradiation dose up to 35 kGy, and acceleration of irradiation dose did not have any effect on gel fraction. At the same irradiation dose, there was no influence of starch concentration on gel fraction. Maximum gel fraction was achieved at 35 kGy irradiation dose. Water content of PVP-Starch hydrogel with starch concentration of 10 to 15% was in the range of 73 - 76%. Water content of hydrogel depends on starch concentration, while irradiation dose does not give any effect on water content of hydrogel. Hydrogel with high water content is potential to be used for fever cooling. Hydrogel PVP-Starch with starch concentration of 10% irradiated by gamma irradiation at the dose of 35 kGy had the ability to reduce water temperature from 40°C to 36°C in 21 minutes, while it took 24 minutes for the hydrogel with starch concentration of 12.5 and 15%. Commercial cooling pad hydrogel need 24 minutes to reduce temperature of water from 40°C to 36°C. Based on these results, it can be concluded that PVP hydrogel with 10% starch content showed faster cooling effect compared to hydrogel with 12.5 and 15 % starch content as well as the commercial hydrogel. Beside these advantages, the hydrogel obtained has some disadvantages such as low stickiness, brittle and opaque. (author)

Synthesis of Monodispersed Gold Nanoparticles with Exceptional Colloidal Stability with Grafted Polyethylene Glycol-g-polyvinyl Alcohol

Directory of Open Access Journals (Sweden)

Alaaldin M. Alkilany

2015-01-01

Full Text Available Herein, we report the synthesis of spherical gold nanoparticles with tunable core size (23–79 nm in the presence of polyethylene glycol-g-polyvinyl alcohol (PEG-g-PVA grafted copolymer as a reducing, capping, and stabilizing agent in a one-step protocol. The resulted PEG-g-PVA-capped gold nanoparticles are monodispersed with an exceptional colloidal stability against salt addition, repeated centrifugation, and extensive dialysis. The effect of various synthesis parameters and the kinetic/mechanism of the nanoparticle formation are discussed.

Nanofibre Electrospinning Poly(vinyl alcohol and Cellulose Composite Mats Obtained by Use of a Cylindrical Electrode

Directory of Open Access Journals (Sweden)

Anna Sutka

2013-01-01

Full Text Available A study of nanofibre composites obtained by electrospinning from poly(vinyl alcohol (PVA solutions of steam exploded hemp fibres and shives is reported. A combined treatment of steam explosion (SE, ball milling, and high-intensity ultrasound (HIUS is applied to prepare cellulose nanofibres (CNF from hemp fibres (CNF-F and shives (CNF-S. The reflectance Fourier transform infrared (FTIR ATR spectroscopy is used to analyze the obtained PVA/CNF composite mats. Morphology of the PVA/CNF composites was studied by scanning electron microscopy (SEM.

Microwave-Assisted Synthesis of Chitosan/Polyvinyl Alcohol Silver Nanoparticles Gel for Wound Dressing Applications

Directory of Open Access Journals (Sweden)

Nguyen Thi Hiep

2016-01-01

Full Text Available The purpose of this study was to fabricate chitosan/poly(vinyl alcohol/Ag nanoparticles (CPA gels with microwave-assistance for skin applications. Microwave irradiation was employed to reduce silver ions to silver nanoparticles and to crosslink chitosan (CS with polyvinyl alcohol (PVA. The presence of silver nanoparticles in CPA gels matrix was examined using UV-Vis spectroscopy, transmission electron microscopy, and X-ray diffraction. The interaction of CS and PVA was analysed by Fourier transform infrared spectroscopy. The release of silver ions was determined by atomic absorption spectrometry. The antimicrobial properties of CPA gels against P. aeruginosa and S. aureus were investigated using agar diffusion method. Finally, the biocompatibility and wound-healing ability of the gels were studied using fibroblast cells (in vitro and mice models (in vivo. In conclusion, the results showed that CPA gels were successfully fabricated using microwave irradiation method. These gels can be applied to heal an open wound thanks to their antibacterial activity and biocompatibility.

Electrical study on Carboxymethyl Cellulose-Polyvinyl alcohol based bio-polymer blend electrolytes

Science.gov (United States)

Saadiah, M. A.; Samsudin, A. S.

2018-04-01

The present work deals with the formulation of bio-materials namely carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA) for bio-polymer blend electrolytes (BBEs) system which was successfully carried out with different ratio of polymer blend. The biopolymer blend was prepared via economical & classical technique that is solution casting technique and was characterized by using impedance spectroscopy (EIS). The ionic conductivity was achieved to optimum value 9.12 x 10-6 S/cm at room temperature for sample containing ratio 80:20 of CMC:PVA. The highest conducting sample was found to obey the Arrhenius behaviour with a function of temperature. The electrical properties were analyzed using complex permittivity ε* and complex electrical modulus M* for BBEs system and it shows the non-Debye characteristics where no single relaxation time has observed.

Study of polyvinyl alcohol nanofibrous membrane by electrospinning as a magnetic nanoparticle delivery approach

International Nuclear Information System (INIS)

Ger, Tzong-Rong; Huang, Hao-Ting; Hu, Keng-Shiang; Huang, Chen-Yu; Lai, Jun-Yang; Chen, Jiann-Yeu; Lai, Mei-Feng

2014-01-01

Electrospinning technique was used to fabricate polyvinyl alcohol (PVA)-based magnetic biodegradable nanofibers. PVA solution was mixed with ferrofluid or magnetic nanoparticles (MNPs) powder and formed two individual nanofibrous membranes (PVA/ferrofluid and PVA/MNPs powder) by electrospinning. The surface morphology of the nanofibrous membrane was characterized by scanning electron microscopy and the magnetic properties were measured by vibrating sample magnetometer. Macrophages (RAW 264.7) were co-cultured with the nanofibrous membranes for 12, 24, and 48 h and exhibited good cell viability (>95%). Results showed that the PVA fibers would be degraded and the embedded Fe 3 O 4 nanoparticles would be released and delivered to cells

Study of polyvinyl alcohol nanofibrous membrane by electrospinning as a magnetic nanoparticle delivery approach

Energy Technology Data Exchange (ETDEWEB)

Ger, Tzong-Rong; Huang, Hao-Ting; Hu, Keng-Shiang [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu, Taiwan (China); Huang, Chen-Yu [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Lai, Jun-Yang [Department of Applied Physics, National Ping Tung University of Education, Pingtung, Taiwan (China); Chen, Jiann-Yeu [Center of Nanoscience and Nanotechnology, National Chung Hsing University, Taichung, Taiwan (China); Lai, Mei-Feng, E-mail: mflai@mx.nthu.edu.tw [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu, Taiwan (China); Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China)

2014-05-07

Electrospinning technique was used to fabricate polyvinyl alcohol (PVA)-based magnetic biodegradable nanofibers. PVA solution was mixed with ferrofluid or magnetic nanoparticles (MNPs) powder and formed two individual nanofibrous membranes (PVA/ferrofluid and PVA/MNPs powder) by electrospinning. The surface morphology of the nanofibrous membrane was characterized by scanning electron microscopy and the magnetic properties were measured by vibrating sample magnetometer. Macrophages (RAW 264.7) were co-cultured with the nanofibrous membranes for 12, 24, and 48 h and exhibited good cell viability (>95%). Results showed that the PVA fibers would be degraded and the embedded Fe{sub 3}O{sub 4} nanoparticles would be released and delivered to cells.

Gamma-irradiation effect on dielectric properties of vanadate doped polyvinyl alcohol

International Nuclear Information System (INIS)

Abo-Ellil, M.S.; Ahmed, M.A.; El-Ahdal, M.A.

1997-01-01

The real part of the dielectric constant (ε) for different concentrations (1%, 2% and 3% by wt.) of the ammonium meta vanadate doped polyvinyl alcohol was measured as a function of temperature and frequency. Different γ-ray doses (2.0, 5.0 and 10kGy) were used for samples irradiation. The dielectric constant of the samples reveals more than one peak depending on the vanadate concentration as well as the applied frequency. The main relaxation peak was discussed with reference degradation and crosslinking that vary drastically with the γ-dose. The hump that appeared at high temperature was found to be due to order-disorder transition. The variation of the internal dynamic viscosity of the sample by irradiation was found to play a role in the polarization process as well as (ε) values. Gradual increase in (ε) was obtained by increasing the γ-dose. (author)

Aroma interactions with starch

DEFF Research Database (Denmark)

Jørgensen, Anders Dysted

Starches are used to enhance aroma perception in low-fat foods. Aroma compounds can bind physically to the starch in grooves on the surface or they can form complexes inside amylose helices. This study has been divided into two parts: one part regarding binding of aromas to starches and their aroma......-release, and another part regarding stimulation of a fungal secretome using different carbohydrates. In the first part, nine aromas and one aroma-mixture were mixed with nine different starches, including genetically modified starches. The objective of this sub-project was to bind aromas to the starches to 15 weight......-percent. Aroma binding was tested on both amorphous starches and on native starch granules. A series of aldehydes and alcohols were also tested for binding to the starches. The aromas with the highest volatility were positively retained by starch, whereas for aromas with a lower volatility the starch had...

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited.

Science.gov (United States)

Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G; Manohar, Srirang

2011-07-01

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

Development of hydroxyapatite/polyvinyl alcohol bionanocomposite for prosthesis implants

Science.gov (United States)

Karthik, V.; Pabi, S. K.; Chowdhury, S. K. Roy

2018-02-01

Hydroxyapatite (Ca10(PO4)6(OH)2) has similar structural and chemical properties of natural bone mineral and hence widely used as a bone replacement substitute. Natural bone consists of hydroxyapatite and collagen. For mimicking the natural, in the present work, a sintered porous hydroxyapatite component has been vacuum impregnated with Polyvinyl alcohol (PVA), which has better properties like biocompatibility, biodegradability and water- solubility. Hydroxyapatite powders have been made into nanosize to reduce the melting point and hence the sintering temperature. In the present investigation high energy ball mill is used to produce nano-hydroxyapatite powders in bulk quantity by optimizing the milling parameters using stainless steel grinding media. Pellets of 10 mm diameter have been produced from nano- hydroxyapatite powders under different uniaxial compaction pressures. The pellets have been sintered to form porous compacts. The vacuum impregnation of sintered pallets with PVA solution of different strength has been done to find the optimum impregnation condition. Microhardness, compressive strength, wear loss and haemocompatibility of hydroxyapatite ceramics have been studied before and after impregnation of PVA. The nano- hydroxyapatite/PVA composites have superior mechanical properties and reduced wear loss than the non-impregnated porous nano-hydroxyapatite ceramics.

Morphology and dispersion of FeCo alloy nanoparticles dispersed in a matrix of IR pyrolized polyvinyl alcohol

Science.gov (United States)

Vasilev, A. A.; Dzidziguri, E. L.; Muratov, D. G.; Zhilyaeva, N. A.; Efimov, M. N.; Karpacheva, G. P.

2018-04-01

Metal-carbon nanocomposites consisting of FeCo alloy nanoparticles dispersed in a carbon matrix were synthesized by the thermal decomposition method of a precursor based on polyvinyl alcohol and metals salts. The synthesized powders were investigated by X-ray diffraction (XRD), X-ray fluorescent spectrometry (XRFS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Surface characteristics of materials were measured by BET-method. The morphology and dispersity of metal nanoparticles were studied depending on the metals ratio in the composite.

Chemically imaging the effects of the addition of nanofibrillated cellulose on the distribution of poly(acrylic acid) in poly(vinyl alcohol)

Science.gov (United States)

Craig Clemons; Julia Sedlmair; Barbara Illman; Rebecca Ibach; Carol Hirschmugl

2013-01-01

The distribution of poly(acrylic acid) (PAA) in model laminates of nanocellulose and poly(vinyl alcohol) (PVOH) was investigated by FTIR chemical imaging. The method was effective in spatially discerning the three components of the composite. PAA can potentially improve the performance of nanocellulose reinforced PVOH by not only crosslinking the PVOH matrix but also...

PIXE investigation of in vitro release of chloramphenicol across polyvinyl alcohol/acrylamide hydrogel

International Nuclear Information System (INIS)

Rihawy, M.S.; Alzier, A.; Allaf, A.W.

2011-01-01

Hydrogels based on polyvinyl alcohol and different amounts of acrylamide monomer were prepared by thermal cross-linking in the solid state. The hydrogels were investigated for drug delivery system applications. Chloramphenicol was adopted as a model drug to study its release behavior. Particle induced X-ray emission was utilized to study the drug release behavior across the hydrogels and a comparison study with ultraviolet measurements was performed. Fourier Transform Infrared measurements were carried out for molecular characterization. The releasing behavior of the drug exhibits a decrease and a subsequent increase in the release rate, as the acrylamide monomer increases. Characterization of the hydrogels has shown a competitive behavior between crosslinking with AAm acrylamide monomer or oligomerized version, depending on the amount added to prepare the hydrogels.

An evaluation of the thermal and mechanical properties of a salt-modified polyvinyl alcohol hydrogel for a knee meniscus application.

Science.gov (United States)

Curley, Colin; Hayes, Jennifer C; Rowan, Neil J; Kennedy, James E

2014-12-01

The treatment of irreparable knee meniscus tears remains a major challenge for the orthopaedic community. The main purpose of this research was to analyse the mechanical properties and thermal behaviour of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous poly vinyl alcohol was treated with a sodium sulphate solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Physical crosslinks in the form of crystalline regions were induced within the hydrogel structure which resulted in a large increase in mechanical resistance. Results showed that the optimal sodium sulphate addition of 6.6% (w/v) Na2SO4 in 8.33% (w/v) PVA causes the PVA to precipitate out of its solution. The effect of multiple freeze thaw cycles was also investigated. Investigation comprised of a variety of well-established characterisation techniques such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), mechanical analysis, rheometry and swelling studies. DSC analysis showed that samples cross-linked using the freeze thaw process display a thermal shift due to increased crosslink density. FTIR analysis confirmed crystallisation is present at 1142cm(-1) and also showed that no chemical alteration occurs when PVA is treated with sodium sulphate. Swelling studies indicated that that PVA/sodium sulphate hydrogels absorb less water than untreated hydrogels due to increased amounts of PVA present. Compressive strength analysis of PVA/sodium sulphate hydrogels prepared at -80°C displayed average maximum loads of 2472N, 2482.4N and 2476N of over 1, 3 and 5 freeze thaw cycles respectively. Mechanical analysis of the hydrogel indicated that the material is thermally stable and resistant to breakdown by compressive force. These properties are crucial for

Permanent hydrophilic modification of polypropylene and poly(vinyl alcohol) films by vacuum ultraviolet radiation

Energy Technology Data Exchange (ETDEWEB)

Belmonte, Guilherme Kretzmann [Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil); Charles, German [Centro de Química Aplicada (CEQUIMAP), Facultad de Ciencias Químicas, Unversidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba 5000 (Argentina); Strumia, Miriam Cristina [Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, IPQA-Conicet, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba 5000 (Argentina); Weibel, Daniel Eduardo, E-mail: danielw@iq.ufrgs.br [Instituto de Química, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Gonçalves 9500, 91501-970 Porto Alegre, RS (Brazil)

2016-09-30

Highlights: • Polypropylene and Poly(vinyl alcohol) were surface modified by vacuum ultraviolet (VUV) irradiation. • The hydrophilicity of the treated films was permanent and resisted aging for several months. • Grafting of styrene monomer was only observed in the VUV irradiated regions. • The obtained results showed the potential in the use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region. - Abstract: Polypropylene (PP) and Poly(vinyl alcohol) (PVA) both synthetics polymers but one of them biodegradable, were surface modified by vacuum ultraviolet (VUV) irradiation. After VUV irradiation in an inert nitrogen atmosphere, the films were exposed to oxygen gas. The treated films were characterized by water contact angle measurements (WCA), optical profilometry, FTIR-ATR, XPS, UPS and NEXAFS techniques. PP and PVA VUV-treated films reached superhydrophilic conditions (WCAs <10°) in about 30 min of irradiation under our experimental conditions. It was observed that when the WCAs reached about 35–40° the hydrophilicity was permanent in both polymers. These results contrasted with typical plasma treatments were a rapid hydrophobic recovery with aging time is usually observed. UPS and XPS data showed the presence of new functionalities on the PP and PVA surfaces that were assigned to COO, C=O, C−O and C=C functional groups. Finally, grafting of styrene (ST) as a typical monomer was tested on PP films. It was confirmed that only in the VUV irradiated region an efficient grafting of ST or polymerized ST was found. Outside the irradiated regions no ST grafted was observed. Our results showed the potential use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region.

Optical and structural behaviors of crosslinked polyvinyl alcohol thin films

Science.gov (United States)

Pandit, Subhankar; Kundu, Sarathi

2018-04-01

Polyvinyl Alcohol (PVA) has excellent properties like uniaxial tensile stress, chemical resistance, biocompatibility, etc. The properties of PVA further can be tuned by crosslinking process. In this work, a simple heat treatment method is used to find out the optimum crosslinking of PVA and the corresponding structural and optical responses are explored. The PVA crosslinking is done by exposing the films at different temperatures and time intervals. The optical property of pure and heat treated PVA films are investigated by UV-Vis absorption and photoluminescence emission spectroscopy and structural modifications are studied by Fourier Transform Infrared Spectroscopy (FTIR). The absorption peaks of pure PVA are observed at ≈ 280 and 335 nm and the corresponding emission is observed at ≈ 424 nm. The pure PVA showed modified optical behaviors after the heat treatment. In addition, dipping the PVA films in hot water (85°C) for nearly 20 minutes also show impact on both structural and optical properties. From FTIR spectroscopy, the changes in vibrational band positions confirm the structural modifications of PVA films.

Physical, chemical and mechanical properties of pehuen cellulosic husk and its pehuen-starch based composites.

Science.gov (United States)

Castaño, J; Rodríguez-Llamazares, S; Carrasco, C; Bouza, R

2012-11-06

Pehuen cellulosic husk was characterized and employed as reinforcement for composite materials. In this research, thermoplastic pehuen starch (TPS) and TPS/poly(lactic acid) (PLA)/polyvinyl alcohol (PVA) composites, reinforced with 5 and 10% of pehuen husk, were prepared by melt-blending. Comparative samples of pehuen TPS and TPS/PLA/PVA blend were also studied. Physical, thermal, structural and mechanical properties of composites were evaluated. Pehuen husk mainly consists of cellulose (50 wt%), hemicellulose (30 wt%) and lignin (14 wt%). In respect to lipids, this husk has only a 0.6 wt%. Its surface is smooth and damage-free and it is decomposed above 325 °C. The incorporation of pehuen husk improved considerably the thermal stability and mechanical properties of the studied composites, mainly in TPS composites. Their thermal stability enhances since biofiber hinders the "out-diffusion" of volatile molecules from the polymer matrix, while mechanical properties could raise due to the natural affinity between husk and starch in the pehuen seed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

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Jyoti R. Mohanty

2014-01-01

Full Text Available Solid particle erosion behavior of short date palm leaf (DPL fiber reinforced polyvinyl alcohol (PVA composite has been studied using silica sand particles (200 ± 50 μm as an erodent at different impingement angles (15–90° and impact velocities (48–109 m/s. The influence of fiber content (wt% of DPL fiber on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM to understand the erosion mechanism.

Optimization of Microencapsulation Composition of Menthol, Vanillin, and Benzyl Acetate inside Polyvinyl Alcohol with Coacervation Method for Application in Perfumery

Science.gov (United States)

Sahlan, Muhamad; Raihani Rahman, Mohammad

2017-07-01

One of many applications of essential oils is as fragrance in perfumery. Menthol, benzyl acetate, and vanillin, each represents olfactive characteristic of peppermint leaves, jasmine flowers, and vanilla beans, are commonly used in perfumery. These components are highly volatile, hence the fragrance components will quickly evaporate resulting in short-lasting scent and low shelf life. In this research, said components have been successfully encapsulated simultaneously inside Polyvinyl Alcohol (PVA) using simple coacervation method to increase its shelf life. Optimization has been done using Central Composite Diagram with 4 independent variables, i.e. composition of menthol, benzyl acetate, vanillin, and tergitol 15-S-9 (as emulsifier). Encapsulation efficiency, loading capacity, and microcapsule size have been measured. In optimized composition of menthol (13.98 %w/w), benzyl acetate (14.75 %w/w), vanillin (17.84 %w/w), and tergitol 15-S-9 (13.4 %w/w) encapsulation efficiency of 97,34% and loading capacity of 46,46% have been achieved. Mean diameter of microcapsule is 20,24 μm and within range of 2,011-36,24 μm. Final product was achieved in the form of cross linked polyvinyl alcohol with hydrogel consistency and orange to yellow in color.

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Science.gov (United States)

Zhang, Shengchang; Liu, Pengqing; Zhao, Xiangsen; Xu, Jianjun

2017-02-01

An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young's modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler-matrix interface, in-situ polymerization combined with chemical grafting modification was a good choice to prepare graphene/PVA nanocomposite with excellent mechanical properties.

Properties and Applications of Polyvinyl Alcohol, Halloysite Nanotubes and Their Nanocomposites

Directory of Open Access Journals (Sweden)

Tayser Sumer Gaaz

2015-12-01

Full Text Available The aim of this review was to analyze/investigate the synthesis, properties, and applications of polyvinyl alcohol–halloysite nanotubes (PVA–HNT, and their nanocomposites. Different polymers with versatile properties are attractive because of their introduction and potential uses in many fields. Synthetic polymers, such as PVA, natural polymers like alginate, starch, chitosan, or any material with these components have prominent status as important and degradable materials with biocompatibility properties. These materials have been developed in the 1980s and are remarkable because of their recyclability and consideration of the natural continuation of their physical and chemical properties. The fabrication of PVA–HNT nanocomposites can be a potential way to address some of PVA’s limitations. Such nanocomposites have excellent mechanical properties and thermal stability. PVA–HNT nanocomposites have been reported earlier, but without proper HNT individualization and PVA modifications. The properties of PVA–HNT for medicinal and biomedical use are attracting an increasing amount of attention for medical applications, such as wound dressings, drug delivery, targeted-tissue transportation systems, and soft biomaterial implants. The demand for alternative polymeric medical devices has also increased substantially around the world. This paper reviews individualized HNT addition along with crosslinking of PVA for various biomedical applications that have been previously reported in literature, thereby showing the attainability, modification of characteristics, and goals underlying the blending process with PVA.

Immobilization of ammonia-oxidizing bacteria by polyvinyl alcohol and sodium alginate.

Science.gov (United States)

Dong, Yuwei; Zhang, Yanqiu; Tu, Baojun

Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30°C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability. Copyright © 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

UV-responsive polyvinyl alcohol nanofibers prepared by electrospinning

Energy Technology Data Exchange (ETDEWEB)

Khatri, Zeeshan, E-mail: zeeshan.khatri@faculty.muet.edu.pk [Department of Textile Engineering, Mehran University of Engineering and Technology, Jamshoro 76062 (Pakistan); Nano Fusion Technology Research Lab, Division of Frontier Fibers, Institute for Fiber Engineering (IFES), Interdisciplinary Cluster for Cutting Edge Research (ICCER), Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567 (Japan); Ali, Shamshad [Department of Textile Engineering, Mehran University of Engineering and Technology, Jamshoro 76062 (Pakistan); Department of Organic and Nano Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Khatri, Imran [Department of Entomology, Sindh Agriculture University, Tandojam (Pakistan); Mayakrishnan, Gopiraman [Nano Fusion Technology Research Lab, Division of Frontier Fibers, Institute for Fiber Engineering (IFES), Interdisciplinary Cluster for Cutting Edge Research (ICCER), Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567 (Japan); Kim, Seong Hun [Department of Organic and Nano Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Ick-Soo, E-mail: kim@shinshu-u.ac.jp [Nano Fusion Technology Research Lab, Division of Frontier Fibers, Institute for Fiber Engineering (IFES), Interdisciplinary Cluster for Cutting Edge Research (ICCER), Shinshu University, 3-15-1, Tokida, Ueda, Nagano 386-8567 (Japan)

2015-07-01

Graphical abstract: - Highlights: • UV responsive PVA nanofibers were prepared via electrospinning. • Quick response codes were recorded multiple times on UV responsive nanofibers. • The rate of photo-coloration was found faster than the rate of photo-reversibility. - Abstract: We report UV-responsive polyvinyl alcohol (PVA) nanofibers for potential application for recording and erasing quick response (QR) codes. We incorporate 1′-3′-dihydro-8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro [2H-1-benzopyran-2,2′-(2H)-indole] (indole) and,3-dihydro-1,3,3-trimethylspiro [2H-indole-2,3′-[3H] phenanthr [9,10-b] (1,4) oxazine] (oxazine) into PVA polymer matrix via electrospinning technique. The resultant nanofibers were measured for recording–erasing, photo-coloration and thermal reversibility. The rate of photo-coloration of PVA–indole nanofibers was five times higher than the PVA–oxazine nanofibers, whereas the thermal reversibility found to be more than twice as fast as PVA–oxazine nanofibers. Results showed that the resultant nanofibers have very good capability of recording QR codes multiple times. The FTIR spectroscopy and SEM were employed to characterize the electrospun nanofibers. The UV-responsive PVA nanofibers have great potentials as a light-driven nanomaterials incorporated within sensors, sensitive displays and in optical devices such as erasable and rewritable optical storage.

UV-responsive polyvinyl alcohol nanofibers prepared by electrospinning

International Nuclear Information System (INIS)

Khatri, Zeeshan; Ali, Shamshad; Khatri, Imran; Mayakrishnan, Gopiraman; Kim, Seong Hun; Kim, Ick-Soo

2015-01-01

Graphical abstract: - Highlights: • UV responsive PVA nanofibers were prepared via electrospinning. • Quick response codes were recorded multiple times on UV responsive nanofibers. • The rate of photo-coloration was found faster than the rate of photo-reversibility. - Abstract: We report UV-responsive polyvinyl alcohol (PVA) nanofibers for potential application for recording and erasing quick response (QR) codes. We incorporate 1′-3′-dihydro-8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro [2H-1-benzopyran-2,2′-(2H)-indole] (indole) and,3-dihydro-1,3,3-trimethylspiro [2H-indole-2,3′-[3H] phenanthr [9,10-b] (1,4) oxazine] (oxazine) into PVA polymer matrix via electrospinning technique. The resultant nanofibers were measured for recording–erasing, photo-coloration and thermal reversibility. The rate of photo-coloration of PVA–indole nanofibers was five times higher than the PVA–oxazine nanofibers, whereas the thermal reversibility found to be more than twice as fast as PVA–oxazine nanofibers. Results showed that the resultant nanofibers have very good capability of recording QR codes multiple times. The FTIR spectroscopy and SEM were employed to characterize the electrospun nanofibers. The UV-responsive PVA nanofibers have great potentials as a light-driven nanomaterials incorporated within sensors, sensitive displays and in optical devices such as erasable and rewritable optical storage

Fabrication and EMI shielding effectiveness of Ag-decorated highly porous poly(vinyl alcohol)/Fe2O3 nanofibrous composites

International Nuclear Information System (INIS)

Kim, Hae-Rim; Kim, Byoung-Suhk; Kim, Ick-Soo

2012-01-01

The Ag-decorated poly(vinyl alcohol) (PVA) composite nanofibrous webs incorporating Fe 2 O 3 nanoparticles were fabricated by electrospinning and metal-deposition methods for electromagnetic interference (EMI) shielding applications. The Ag-decorated PVA/Fe 2 O 3 composite nanofiber webs with various Ag thicknesses and different amounts of Fe 2 O 3 nanoparticles were prepared and used for EMI shielding measurement. For the EMI SE measurement, a near-field antenna measurement system was used. The measurement of EMI SE was carried out at the frequency range from 0.5 to 18 GHz, and the electromagnetic parameters were measured. The morphologies and microstructures of the resultant PVA/Fe 2 O 3 composite nanofiber webs were characterized using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. The effects of surface morphologies and Fe 2 O 3 nanoparticles on the EMI shielding effectiveness of Ag-decorated PVA/Fe 2 O 3 composite nanofiber webs were investigated. -- Highlights: ► We prepare Ag-decorated poly(vinyl alcohol) nanowebs incorporating Fe 2 O 3 nanoparticles. ► Solvents will affect the fiber morphologies and Fe 2 O 3 nanoparticles dispersion. ► EMI shielding effectiveness depends on the metal thickness and Fe 2 O 3 nanoparticles dispersion.

Study of poly(vinyl alcohol)/titanium oxide composite polymer membranes and their application on alkaline direct alcohol fuel cell

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lee, Kuo-Tong; Chien, Wen-Chen; Lin, Che-Tseng; Huang, Ching-An

The novel poly(vinyl alcohol)/titanium oxide (PVA/TiO 2) composite polymer membrane was prepared using a solution casting method. The characteristic properties of the PVA/TiO 2 composite polymer membrane were investigated by thermal gravimetric analysis (TGA), a scanning electron microscopy (SEM), a micro-Raman spectroscopy, a methanol permeability measurement and the AC impedance method. An alkaline direct alcohol (methanol, ethanol and isopropanol) fuel cell (DAFC), consisting of an air cathode based on MnO 2/C inks, an anode based on PtRu (1:1) black and a PVA/TiO 2 composite polymer membrane, was assembled and examined for the first time. The results indicate that the alkaline DAFC comprised of a cheap, non-perfluorinated PVA/TiO 2 composite polymer membrane shows an improved electrochemical performances. The maximum power densities of alkaline DAFCs with 4 M KOH + 2 M CH 3OH, 2 M C 2H 5OH and 2 M isopropanol (IPA) solutions at room temperature and ambient air are 9.25, 8.00, and 5.45 mW cm -2, respectively. As a result, methanol shows the highest maximum power density among three alcohols. The PVA/TiO 2 composite polymer membrane with the permeability values in the order of 10 -7 to 10 -8 cm 2 s -1 is a potential candidate for use on alkaline DAFCs.

Monitoring of temperature fatigue failure mechanism for polyvinyl alcohol fiber concrete using acoustic emission sensors.

Science.gov (United States)

Li, Dongsheng; Cao, Hai

2012-01-01

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed.

Clinical Long-Term Outcome and Reinterventional Rate After Uterine Fibroid Embolization with Nonspherical Versus Spherical Polyvinyl Alcohol Particles

Energy Technology Data Exchange (ETDEWEB)

Duvnjak, Stevo, E-mail: stevo.duvnjak@rsyd.dk [Odense University Hospital, Department of Radiology (Denmark); Ravn, Pernille [Odense University Hospital, Department of Gynecology (Denmark); Green, Anders [Odense University Hospital, Odense Patient Data Explorative Network (Denmark); Andersen, Poul Erik [Odense University Hospital, Department of Radiology (Denmark)

2016-02-15

PurposeThis study was designed to evaluate the long-term clinical outcome and frequency of reinterventions in patients with uterine fibroids treated with embolization at a single center using polyvinyl alcohol microparticles.MethodsThe study included all patients with symptomatic uterine fibroids treated with uterine fibroid embolization (UFE) with spherical (s-PVA) and nonspherical (ns-PVA) polyvinyl alcohol microparticles during the period January 2001 to January 2011. Clinical success and secondary interventions were examined. Hospital records were reviewed during follow-up, and symptom-specific questionnaires were sent to all patients.ResultsIn total, 515 patients were treated with UFE and 350 patients (67 %) were available for long-term clinical follow-up. Median time of follow-up was 93 (range 76–120.2) months. Eighty-five patients (72 %) had no reinterventions during follow-up in the group embolized with ns-PVA compared with 134 patients (58 %) treated with s-PVA. Thirty-three patients (28 %) underwent secondary interventions in the ns-PVA group compared with 98 patients (42 %) in s-PVA group (χ{sup 2} test, p < 0.01).ConclusionsSpherical PVA particles 500–700 µm showed high reintervention rate at long-term follow-up, and almost one quarter of the patients underwent secondary interventions, suggesting that this type of particle is inappropriate for UFE.

Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

International Nuclear Information System (INIS)

Afshari, Esmail; Mazinani, Saeedeh; Ranaei-Siadat, Seyed-Omid; Ghomi, Hamid

2016-01-01

Highlights: • We fabricated polyvinyl alcohol/malonic acid nanofibers using electrospinning. • The surface nanofibers were modified by gaseous (air, nitrogen, CO_2 and argon) dielectric barrier discharge. • Among them, air plasma had the most significant effect on glucose oxidase immobilization. • Chemical analysis showed that after modification of nanofibers by air plasma, the carboxyl group increased. • After air plasma treatment, reusability and storage stability of glucose oxidase immobilized on nanofibers improved. - Abstract: Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO_2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

Energy Technology Data Exchange (ETDEWEB)

Afshari, Esmail, E-mail: e.afshari@mail.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Mazinani, Saeedeh [Amirkabir Nanotechnology Research Institute (ANTRI), Amirkabir University of Technology, 15875-4413, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin, 1983963113 Tehran (Iran, Islamic Republic of)

2016-11-01

Highlights: • We fabricated polyvinyl alcohol/malonic acid nanofibers using electrospinning. • The surface nanofibers were modified by gaseous (air, nitrogen, CO{sub 2} and argon) dielectric barrier discharge. • Among them, air plasma had the most significant effect on glucose oxidase immobilization. • Chemical analysis showed that after modification of nanofibers by air plasma, the carboxyl group increased. • After air plasma treatment, reusability and storage stability of glucose oxidase immobilized on nanofibers improved. - Abstract: Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO{sub 2}, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

Fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) nanocomposite nanofibres by electrospinning

International Nuclear Information System (INIS)

Junkasem, Jirawut; Rujiravanit, Ratana; Supaphol, Pitt

2006-01-01

The present contribution reports, for the first time, the successful fabrication of α-chitin whisker-reinforced poly(vinyl alcohol) (PVA) nanocomposite nanofibres by electrospinning. The α-chitin whiskers were prepared from α-chitin flakes from shrimp shells by acid hydrolysis. The as-prepared chitin whiskers exhibited lengths in the range 231-969 nm and widths in the range 12-65 nm, with the average length and width being about 549 and 31 nm, respectively. Successful incorporation of the chitin whiskers within the as-spun PVA/chitin whisker nanocomposite nanofibres was verified by infrared spectroscopic and thermogravimetric methods. The incorporation of chitin whiskers within the as-spun nanocomposite fibre mats increased the Young's modulus by about 4-8 times over that of the neat as-spun PVA fibre mat

A study of poly(vinyl alcohol thermal degradation by thermogravimetry and differential thermogravimetry

Directory of Open Access Journals (Sweden)

Julián Esteban Barrera

2007-05-01

Full Text Available The thermal degradation of poly(vinyl alcohol (PVA having different degrees of hydrolysis and molecular weights was studied by thermogravimetry (TGA and differential thermogravimetry (DTGA. Four degradation events were identified whose intensity was related to the degree of hydrolysis. It was verified that the solid-state degradation mechanism for high hydrolysis degrees corresponded to eliminating water-forming side groups in stoichiometric amounts. The presence of acetate groups and lower melting points delayed the polymer’s thermal decomposition at lower hydrolysis degrees. There was no direct correlation in these samples between weight-loss during the first degradation event and the stoichiometric quantities which would be produced by eliminating the side groups. Reaction order and energy activation value qualitative coincidence was found by evaluating experimental data by using Freeman-Carroll and Friedman kinetic models.

Piezoresistive Pressure Sensor Based on Synergistical Innerconnect Polyvinyl Alcohol Nanowires/Wrinkled Graphene Film.

Science.gov (United States)

Liu, Weijie; Liu, Nishuang; Yue, Yang; Rao, Jiangyu; Cheng, Feng; Su, Jun; Liu, Zhitian; Gao, Yihua

2018-04-01

Piezoresistive sensor is a promising pressure sensor due to its attractive advantages including uncomplicated signal collection, simple manufacture, economical and practical characteristics. Here, a flexible and highly sensitive pressure sensor based on wrinkled graphene film (WGF)/innerconnected polyvinyl alcohol (PVA) nanowires/interdigital electrodes is fabricated. Due to the synergistic effect between WGF and innerconnected PVA nanowires, the as-prepared pressure sensor realizes a high sensitivity of 28.34 kPa -1 . In addition, the device is able to discern lightweight rice about 22.4 mg (≈2.24 Pa) and shows excellent durability and reliability after 6000 repeated loading and unloading cycles. What is more, the device can detect subtle pulse beat and monitor various human movement behaviors in real-time. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polyvinyl alcohol-immobilized Phanerochaete chrysosporium and its application in the bioremediation of composite-polluted wastewater

Energy Technology Data Exchange (ETDEWEB)

Huang, Zhenzhen [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen, Guiqiu, E-mail: gqchen@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen, Anwei [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Zuo, Yanan; Guo, Zhi; Tan, Qiong [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Song, Zhongxian [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Niu, Qiuya [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2015-05-30

Graphical abstract: Schematic diagram of polyvinyl alcohol-immobilized Phanerochaete chrysosporium beads (PPBs) for Cd(II) removal and 2,4-DCP degradation. - Highlights: • PVA-immobilized P. chrysosporium beads (PPBs) were fit for wastewater treatment. • Removal rates of Cd(II) and 2,4-DCP at optimum conditions were up to 78% and 95.4%. • 2,4-DCP removal rates were beyond 90% with varying initial 2,4-DCP concentrations. • PVA was vital to Cd(II) removal besides the function groups in P. chrysosporium. • Maximum recovery of the Cd(II)-laden PPBs after reuse three times was 98.9%. - Abstract: A novel biosorbent, polyvinyl alcohol (PVA)-immobilized Phanerochaete chrysosporium, was applied to the bioremediation of composite-polluted wastewater, containing both cadmium and 2,4-dichlorophenol (2,4-DCP). The optimum removal efficiency achieved was 78% for Cd(II) and 95.4% for 2,4-DCP at initial concentrations of 20 mg/L Cd(II) and 40 mg/L 2,4-DCP. PPBs had significantly enhanced the resistance of P. chrysosporium to 2,4-DCP, leading to the degradation rates of 2,4-DCP beyond 90% with varying initial 2,4-DCP concentrations. This research demonstrated that 2,4-DCP and secreted proteins might be used as carbon and nitrogen sources by PVA-immobilized P. chrysosporium beads (PPBs) for Cd(II) removal. Fourier transform infrared spectroscopy analysis showed that hydroxyl and carboxyl groups on the surface of PPBs were dominant in Cd(II) binding. The mechanism underlying the degradation of 2,4-DCP into fumaric acid and 1-hexanol was investigated. The adsorption–desorption studies indicated that PPBs kept up to 98.9% of desorption efficiency over three cycles.

Polyvinyl alcohol-immobilized Phanerochaete chrysosporium and its application in the bioremediation of composite-polluted wastewater

International Nuclear Information System (INIS)

Huang, Zhenzhen; Chen, Guiqiu; Zeng, Guangming; Chen, Anwei; Zuo, Yanan; Guo, Zhi; Tan, Qiong; Song, Zhongxian; Niu, Qiuya

2015-01-01

Graphical abstract: Schematic diagram of polyvinyl alcohol-immobilized Phanerochaete chrysosporium beads (PPBs) for Cd(II) removal and 2,4-DCP degradation. - Highlights: • PVA-immobilized P. chrysosporium beads (PPBs) were fit for wastewater treatment. • Removal rates of Cd(II) and 2,4-DCP at optimum conditions were up to 78% and 95.4%. • 2,4-DCP removal rates were beyond 90% with varying initial 2,4-DCP concentrations. • PVA was vital to Cd(II) removal besides the function groups in P. chrysosporium. • Maximum recovery of the Cd(II)-laden PPBs after reuse three times was 98.9%. - Abstract: A novel biosorbent, polyvinyl alcohol (PVA)-immobilized Phanerochaete chrysosporium, was applied to the bioremediation of composite-polluted wastewater, containing both cadmium and 2,4-dichlorophenol (2,4-DCP). The optimum removal efficiency achieved was 78% for Cd(II) and 95.4% for 2,4-DCP at initial concentrations of 20 mg/L Cd(II) and 40 mg/L 2,4-DCP. PPBs had significantly enhanced the resistance of P. chrysosporium to 2,4-DCP, leading to the degradation rates of 2,4-DCP beyond 90% with varying initial 2,4-DCP concentrations. This research demonstrated that 2,4-DCP and secreted proteins might be used as carbon and nitrogen sources by PVA-immobilized P. chrysosporium beads (PPBs) for Cd(II) removal. Fourier transform infrared spectroscopy analysis showed that hydroxyl and carboxyl groups on the surface of PPBs were dominant in Cd(II) binding. The mechanism underlying the degradation of 2,4-DCP into fumaric acid and 1-hexanol was investigated. The adsorption–desorption studies indicated that PPBs kept up to 98.9% of desorption efficiency over three cycles

Adsorption Characteristics of Polyvinyl Alcohols in Solution on Expanded Graphite

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Xiu-Yan Pang

2012-01-01

Full Text Available Expanded graphite (EG adsorbent was prepared with 50 mesh graphite as raw materials, potassium permanganate as oxidant, and vitriol as intercalation compound. Three kinds of polyvinyl alcohol (PVA with different degree of polymerization (DP in aqueous solution were used as adsorbates. We have studied the influence of initial PVA concentration, temperature and ionic strength on adsorption capacity. Langmuir constants and Gibbs free energy change (⊿G° were calculated according to experimental data respectively. Thermodynamic analysis indicates the equilibrium adsorbance of PVA on EG increase with the rise of SO42– concentration. Adsorption isotherms of PVA with different degree of polymerization are all types and we deduce PVA molecules lie flat on EG surface. Adsorption processes are all spontaneous. Kinetic studies show that the kinetic data can be described by pseudo second-order kinetic model. Second-order rate constants and the initial adsorption rate rise with the increasing of temperature and half-adsorption time decreases with the increasing of temperature. The adsorption activation energy of each PVA is less than 20 kJ•mol−1, physical adsorption is the major mode of the overall adsorption process.

Artificial Auricular Cartilage Using Silk Fibroin and Polyvinyl Alcohol Hydrogel

Science.gov (United States)

Lee, Jung Min; Sultan, Md. Tipu; Kim, Soon Hee; Kumar, Vijay; Yeon, Yeung Kyu; Lee, Ok Joo; Park, Chan Hum

2017-01-01

Several methods for auricular cartilage engineering use tissue engineering techniques. However, an ideal method for engineering auricular cartilage has not been reported. To address this issue, we developed a strategy to engineer auricular cartilage using silk fibroin (SF) and polyvinyl alcohol (PVA) hydrogel. We constructed different hydrogels with various ratios of SF and PVA by using salt leaching, silicone mold casting, and freeze-thawing methods. We characterized each of the hydrogels in terms of the swelling ratio, tensile strength, pore size, thermal properties, morphologies, and chemical properties. Based on the cell viability results, we found a blended hydrogel composed of 50% PVA and 50% SF (P50/S50) to be the best hydrogel among the fabricated hydrogels. An intact 3D ear-shaped auricular cartilage formed six weeks after the subcutaneous implantation of a chondrocyte-seeded 3D ear-shaped P50/S50 hydrogel in rats. We observed mature cartilage with a typical lacunar structure both in vitro and in vivo via histological analysis. This study may have potential applications in auricular tissue engineering with a human ear-shaped hydrogel. PMID:28777314

Research progress of fabricating polyvinyl alcohol coating on plastic microsphere

International Nuclear Information System (INIS)

Su Lin; Chen Sufen; Liu Meifang; Zhang Zhanwen; Yao Hong; Li Bo; Liu Yiyang

2012-01-01

In the procedures of designing polystyrene-polyvinyl alcohol-CH (carbon and hydrogen elements) (PS-PVA-CH) triple-layer microspheres, there are many methods such as drop-tower technique, emulsion micro-encapsulation, dip (spin) coating, interfacial polycondensation, and spraying technique to prepare the PVA coating. Drop-tower technique, emulsion micro-encapsulation and dip (spin) coating are most-commonly used. The advantages, disadvantages and the research progress of the three methods are summarized in this paper. Emulsion micro-encapsulation is suitable for preparing double-layer microspheres of sizes smaller then 500 μm, with high survival ratio and good quality. However, the preparation process is easily influenced by artificial factors. Small-sized double-layer microspheres can also be prepared by the drop-tower technique, and the preparation period is short. But there are still some problems such as the difficulty in designing the droplet generator, uneven PVA coating and the difficulty in preparing large-sized microspheres. Dip (spin) coating technique can be used to prepare PS-PVA microspheres with sizes larger than 1000 μm, but the spread of PVA coating is affected by many factors in this method, and the prepared PVA coating is too thin and not uniform. (authors)

Tailoring of poly(vinyl alcohol cryogels properties by salts addition

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2009-05-01

Full Text Available The present paper aims to study the possibility to modify the properties of poly(vinyl alcohol (PVA hydrogels prepared in the presence of different salt types (Na2SO4, NaCl and NaNO3 in order to extend the nature of the salts already used in obtaining films or gels, to expand their concentration domains and to explain the increase of film strain, concomitantly with the increase of their crystallinity. The morphology of the PVA based hydrogels has been studied by Scanning Electronic Microscopy (SEM, the interaction between the PVA macromolecular chains and salts has been determined by Fourier Transform Infrared Spectroscopy (FTIR, while the mechanical properties of the cryogels have been investigated by oscillatory dynamic mechanical measurements. The gels swelling in water have been monitored by gravimetric method in order to evidence the alteration of the PVA cryogel properties such as crystallinity and porosity determined by the salt addition to the initial PVA aqueous solution. The data reported show that the ions present in the PVA solution influence the interaction between PVA-water and PVA-PVA chains; their influence on the salt-based PVA hydrogels follow the Hofmeister lyotropic series.

Development and Evaluation of Polyvinyl Alcohol-Hydrogels as an Artificial Atrticular Cartilage for Orthopedic Implants

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Masanori Kobayashi

2010-04-01

Full Text Available Due to its excellent biocompatibility and mechanical properties, various different applications of polyvinyl alcohol-hydrogels (PVA-H has been attempted in many fields. In the field of orthopedic surgery, we have been engaged for long time in research on the clinical applications of PVA-H as a artificial cartilage, and have performed many basic experiments on the mechanical properties, synthesis of PVA-H, and developed orthopedic implants using PVA-H. From these studies, many applications of artificial articular cartilage, intervertbral disc and artificial meniscus etc. have been developed. This review will present the overview of the applications and recent advances of PVA-H cartilages, and discuss clinical potential of PVA-H for orthopedics implant.

Development and Evaluation of Polyvinyl Alcohol-Hydrogels as an Artificial Atrticular Cartilage for Orthopedic Implants

Science.gov (United States)

Kobayashi, Masanori; Hyu, Hyon Suong

2010-01-01

Due to its excellent biocompatibility and mechanical properties, various different applications of polyvinyl alcohol-hydrogels (PVA-H) has been attempted in many fields. In the field of orthopedic surgery, we have been engaged for long time in research on the clinical applications of PVA-H as a artificial cartilage, and have performed many basic experiments on the mechanical properties, synthesis of PVA-H, and developed orthopedic implants using PVA-H. From these studies, many applications of artificial articular cartilage, intervertbral disc and artificial meniscus etc. have been developed. This review will present the overview of the applications and recent advances of PVA-H cartilages, and discuss clinical potential of PVA-H for orthopedics implant.

The use of polyvinyl alcohol glutaraldehyde as solid-phase in ELISA for plague

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Aureci Maria Araujo

1996-04-01

Full Text Available Discs of polyvinyl alcohol cross-linked with glutaraldehyde were synthesized under acid catalysis (H2SO4. Then, the antigen F1 purified from Yersinia pestis was covalently linked to this modified polymer. Afterwards, an enzyme-linked immunosorbent assay (ELISA was established for the diagnosis of plague in rabbit and human. The best conditions for the method were achieved by using 1.3 ¼g of F1 prepared in 0.067 M phosphate buffer, pH 7.2, containing 1 M NaCl (PBS; anti-IgG peroxidase conjugate diluted 6,000 times and as a blocking agent 3% w/v skim milk in PBS. The titration of positive rabbit serum according to this procedure detected antibody concentrations up to 1:12,800 times. The present method, the conventional ELISA and passive haemagglutination assay are compared.

Investigation of Electrical and Optical Characteristics of Nanohybride Composite (Polyvinyl Alcohol / Nickel Oxide

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A. Hayati

2014-01-01

Full Text Available Some issues; leakage, tunneling currents, boron diffusion are threatening SiO2 to be used as a good gate dielectric for the future of the CMOS (complementary metal- oxide- semiconductor transistors. For finding an alternative and novel gate dielectric, the NiO (Nickel oxide and PVA (polyvinyl alcohol nano powders were synthesized with the sol-gel method and their nano structural properties were studied using the X-ray diffraction (XRD, Atomic force microscopy (AFM, Scanning electron microscopy (SEM, UV-Vis spectrophotometer and GPS 132 techniques. The obtained results indicated that the sample (5 g NiO and 0.02g PVA prepared at 30˚C, annealed in an oven at a temperature of 80˚C can fill this gap due to its higher dielectric constant, better morphology, less rough surface and less leakage current.

Electrospun single-walled carbon nanotube/polyvinyl alcohol composite nanofibers: structure-property relationships

International Nuclear Information System (INIS)

Naebe, Minoo; Lin Tong; Wang Xungai; Staiger, Mark P; Dai Liming

2008-01-01

Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both the pure PVA and SWNT/PVA composite nanofibers were subjected to the following post-electrospinning treatments: (i) soaking in methanol to increase the PVA crystallinity, and (ii) cross-linking with glutaric dialdehyde to control the PVA morphology. Effects of the PVA morphology on the tensile properties of the resultant electrospun nanofibers were examined. Dynamic mechanical thermal analyses of both pure PVA and SWNT/PVA composite electrospun nanofibers indicated that SWNT-polymer interaction facilitated the formation of crystalline domains, which can be further enhanced by soaking the nanofiber in methanol and/or cross-linking the polymer with glutaric dialdehyde

Thermal, mechanical and dielectric properties of poly(vinyl alcohol)/graphene oxide composites

Science.gov (United States)

Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.; Naik, Jagadish

2014-04-01

In this work the composite films of poly(vinyl alcohol) (PVA) doped with functionalized Graphene Oxide (GO) were prepared by solution casting method. The films were characterized using FT-IR, DSC, XRD, mechanical properties and dielectric studies at room temperature. FTIR spectra shows the formation of hydrogen bonds between hydroxyl groups of PVA and the hydroxy groups of GO. The DSC thermograms shows the addition of GO to PVA greatly improves the thermal stability of the composites. XRD patterns shows that the GO exfoliated and uniformly dispersed in PVA matrix. Mechanical properties are significantly improved in PVA/GO composites. The tensile strength increased from 8.2 to 13.7 MPa and the Young's modulus increased from 7.5 to 24.8 MPa for 5 wt% GO doped sample. Dielectric spectroscopy showed a highest dielectric constant for the 5 wt% GO doped PVA films. This work provides a potential design strategy on PVA/GO composite, which would lead to higher-performance, flexible dielectric materials, high charge-storage devices.

Low-temperature-cured highly conductive composite of Ag nanowires and polyvinyl alcohol

International Nuclear Information System (INIS)

He Song; Zhang Xiang; Yang Bingchu; Xu Xiaomei; Chen Hui; Zhou Conghua

2017-01-01

Flexible conductive films were fabricated from a low-temperature-cured, highly conductive composite of silver nanowires (as conducting filler) and polyvinyl alcohol (PVA, as binder). Sheet resistance of 0.12 Ω/sq, conductivity of 2.63×10 4 S/cm, and contact resistance of 1.0 Ω/cm 2 were measured in the films, along with excellent resistance to scratching and good flexibility, making them suitable electrical contact materials for flexible optoelectronic devices. Effects of curing temperature, curing duration, film thickness, and nanowire length on the film’s electrical properties were studied. Due to the abundance of hydroxyl groups on its molecular chains, the addition of PVA improves the film’s flexibility and resistance to scratching. Increased nanowire density and nanowire length benefit film conductance. Monte Carlo simulation was used to further explore the impact of these two parameters on the conductivity. It was observed that longer nanowires produce a higher length-ratio of conducting routes in the networks, giving better film conductivity. (paper)

Nanofibers obtained by electrospinning of BaTiO3 particles dispersed in polyvinyl alcohol and ethylcellulose

Energy Technology Data Exchange (ETDEWEB)

Avila, Humar A.; Reboredo, Maria M.; Castro, Miriam; Parra, Rodrigo, E-mail: havila@fi.mdp.edu.ar [Instituto de Investigaciones en Ciencia y Tecnologia de Materiales - INTEMA, Consejo Nacional de Investigaciones Cientificas y Tecnicas - CONICET, Universidad Nacional de Mar del Plata - UNMdP, Mar del Plata (Argentina)

2013-11-01

Barium titanate particles (100-300 nm) synthesized by hydrothermal method were dispersed in both polyvinyl alcohol (PVA) and ethylcellulose (EC) solutions. These suspensions were processed by electrospinning. When no particles were added, homogeneous polymeric nanofibers were obtained. Under certain conditions, polymeric suspensions of barium titanate particles were electrospun generating polymeric fibers with BT particles. The effect of a surfactant was also assessed over the formation of nanofibers. The BaTiO{sub 3} particles synthesized by hydrothermal method were characterized by X-Ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Fibers were characterized by scanning electron microscopy (SEM). (author)

Time-dependent micro-Raman scattering studies of polyvinyl ...

Indian Academy of Sciences (India)

2014-02-15

Feb 15, 2014 ... Micro-Raman scattering; surface plasmons; silver nanoparticles; polyvinyl alcohol. PACS Nos 74.25.nd; ... as well as their characterization. Added .... 3.2 Surface plasmon absorption of thin films of PVA + AgNO3. The surface ...

Controlled synthesis of novel 3D dendritic Bi2S3 /cross-linked poly(vinyl alcohol) nanocomposites

International Nuclear Information System (INIS)

Wu, W-T; Shi Lei; Pang Wenmin; Wang Yusong; Zhu Qingren; Xu Guoyong

2006-01-01

Novel spherical three-dimensional (3D) dendritic Bi 2 S 3 /cross-linked poly(vinyl alcohol) (PVA) nanocomposites were successfully synthesized in aqueous solution of amphiphilic polyvinylacetone (PVKA) (ketalization degree D H = 0.549), via one-step in situ decomposition of the complex [Bi(Tu) x ] 3+ under γ-ray irradiation, utilizing the controllable hydrolysis property of PVKA in acidic solution. Herein, PVA chains are obtained from the hydrolysed PVKA. These uniform 3D spherical nanocomposites have a structure similar to that found in the natural lotus leaf, where every microscale papilla on the leaf surface is covered by nanoscale papillae

FT-IR study of gamma-radiation induced degradation of polyvinyl alcohol (PVA) and PVA/humic acids blends

International Nuclear Information System (INIS)

Ilcin, M.; Hola, O.; Bakajova, B.; Kucerik, J.

2010-01-01

Samples of pure polyvinyl alcohol (PVA) and PVA doped with humic acids were exposed to gamma radiation. Gamma rays induced the degradation of the pure polymer. Degradation changes were observed using ATR FT-IR equipment. Dehydration, double bond creation, and their subsequent oxidation (surrounding atmosphere was air) were found out. Also, other degradation reactions (e.g. chain scission, cyclization) occur simultaneously. Formation of C=C and C=O bonds is apparent from FT-IR spectra. In contrast the presence of humic acids in the PVA sample showed stabilizing effect on PVA structure within the concentration range 0.5-10%. (author)

AC-conductance and capacitance measurements for ethanol vapor detection using carbon nanotube-polyvinyl alcohol composite based devices.

Science.gov (United States)

Greenshields, Márcia W C C; Meruvia, Michelle S; Hümmelgen, Ivo A; Coville, Neil J; Mhlanga, Sabelo D; Ceragioli, Helder J; Quispe, Jose C Rojas; Baranauskas, Vitor

2011-03-01

We report the preparation of inexpensive ethanol sensor devices using multiwalled carbon nanotube-polyvinyl alcohol composite films deposited onto interdigitated electrodes patterned on phenolite substrates. We investigate the frequency dependent response of the device conductance and capacitance showing that higher sensitivity is obtained at higher frequency if the conductance is used as sensing parameter. In the case of capacitance measurements, higher sensitivity is obtained at low frequency. Ethanol detection at a concentration of 300 ppm in air is demonstrated. More than 80% of the sensor conductance and capacitance variation response occurs in less than 20 s.

Effects of Saponification Rate on Electrooptical Properties and Morphology of Poly(vinyl alcohol)/Liquid Crystal Composite Films

Science.gov (United States)

Ono, Hiroshi; Kawatsuki, Nobuhiro

1995-03-01

The relationship between the saponification rate of poly(vinyl alcohol) (PVA), and the electrooptical properties and morphology of the PVA/liquid crystal (LC) composite films was investigated. Light transmission clazing and the LC droplet size were varied by changing the saponification rate or the blend ratio of two kinds of PVA with different saponification rates because the refractive index and surface tension could be controlled by the saponification rate of PVA. The threshold voltage decreased with increasing saponification rate though the extrapolation length was decreased. It was suggested that the electrooptical properties were strongly dependent on the droplet size.

Semicontinuous saccharification of starch in alcohol production

Energy Technology Data Exchange (ETDEWEB)

Danilyak, N.I.; Kaminskil, R.S.; Shvedov, A.D.

1959-05-21

The saccharification is accomplished with an enzyme preparation of Aspergillus oryzae. In the first stage, the starch is treated at 57 to 59/sup 0/ with a fermenting solution containing 1% enzyme based on the starch content. The second step is carried out in the fermenting solution containing 2.5% enzyme.

Yeast Extract Promotes Cell Growth and Induces Production of Polyvinyl Alcohol-Degrading Enzymes

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Min Li

2011-01-01

Full Text Available Polyvinyl alcohol-degrading enzymes (PVAases have a great potential in bio-desizing processes for its low environmental impact and low energy consumption. In this study, the effect of yeast extract on PVAases production was investigated. A strategy of four-point yeast extract addition was developed and applied to maximize cell growth and PVAases production. As a result, the maximum dry cell weight achieved was 1.48 g/L and the corresponding PVAases activity was 2.99 U/mL, which are 46.5% and 176.8% higher than the control, respectively. Applying this strategy in a 7 L fermentor increased PVAases activity to 3.41 U/mL. Three amino acids (glycine, serine, and tyrosine in yeast extract play a central role in the production of PVAases. These results suggest that the new strategy of four-point yeast extract addition could benefit PVAases production.

PIXE investigation of in-vitro release of chloramphenicol across polyvinyl alcohol/ acrylamide hydrogel

International Nuclear Information System (INIS)

Rihawi, M.; Al-Zeer, A.; Allaf, A.

2012-01-01

Hydrogels based on polyvinyl alcohol (PVA) and different amounts of acrylamide monomer (AAm) were prepared by thermal crosslinking process in solid state. The PVA/AAm hydrogels were investigated for drug delivery system applications. Chloramphenicol was adopted as a model drug to study its release behaviour across the prepared hydrogels. Particle induced X-ray emission (PIXE) analytical technique was utilized to study the drug release behaviour across the hydrogels. A comparison study between PIXE and UV measurements was performed. FTIR measurements were carried out to perform the molecular characterization. The releasing behaviour of the drug across the hydrogels demonstrates a decrease and a subsequent increase in the drug release rate, as the AAm amount increases. The FTIR characterization of the prepared hydrogels has shown a competitive behaviour between the crosslinking of PVA with AAm monomer or oligomerized AAm, depending on the amount of AAm added to prepare the PVA/AAm hydrogels. (author)

Tuning optical and three photon absorption properties in graphene oxide-polyvinyl alcohol free standing films

Energy Technology Data Exchange (ETDEWEB)

Karthikeyan, B., E-mail: bkarthik@nitt.edu; Hariharan, S. [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India); Udayabhaskar, R. [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India); Advanced Ceramics and Nanotechnology Laboratory, Department of Materials Engineering, University of Concepcion, Concepcion 4070386 (Chile)

2016-07-11

We report the optical and nonlinear optical properties of graphene oxide (GO)-polyvinyl alcohol (PVA) free standing films. The composite polymer films were prepared in ex-situ method. The variation in optical absorption spectra and optical constants with the amount of GO loading was noteworthy from the optical absorption spectroscopic studies. Nonlinear optical studies done at 532 nm using 5 ns laser pulses show three photon absorption like behaviour. Both steady state and time resolved fluorescence studies reveal that the GO was functioning as a pathway for the decay of fluorescence from PVA. This is attributed to the energy level modifications of GO through hydroxyl groups with PVA. Raman spectroscopy also supports the interaction between GO and PVA ions through OH radicals.

Tuning optical and three photon absorption properties in graphene oxide-polyvinyl alcohol free standing films

International Nuclear Information System (INIS)

Karthikeyan, B.; Hariharan, S.; Udayabhaskar, R.

2016-01-01

We report the optical and nonlinear optical properties of graphene oxide (GO)-polyvinyl alcohol (PVA) free standing films. The composite polymer films were prepared in ex-situ method. The variation in optical absorption spectra and optical constants with the amount of GO loading was noteworthy from the optical absorption spectroscopic studies. Nonlinear optical studies done at 532 nm using 5 ns laser pulses show three photon absorption like behaviour. Both steady state and time resolved fluorescence studies reveal that the GO was functioning as a pathway for the decay of fluorescence from PVA. This is attributed to the energy level modifications of GO through hydroxyl groups with PVA. Raman spectroscopy also supports the interaction between GO and PVA ions through OH radicals.

Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

Science.gov (United States)

Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

2015-04-01

We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.

Effects of Modified Iron Oxide Nanoparticles on the Thermal and Dynamic Mechanical Properties of Cellulose Poly(vinyl alcohol Blend Films

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Mehdi Roohani

2015-11-01

Full Text Available This study was designed to investigate the effect of modified iron oxide nanoparticles (MINP and cellulose nanocrystals (NCC on magnetic, thermal and dynamic-mechanical properties of poly(vinyl alcohol based nanocomposites. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Nanocomposite films were developed by solvent casting method and their properties were characterized by vibrating sample magnetometer (VSM, differential scanning calorimetry (DSC and dynamic mechanical analysis (DMA. DSC results found that with incorporation of nanoparticles, the glass transition temperature increase slightly to higher temperatures; however, the degree of crystallinity and the values of the melting temperature are found to decrease. Dynamic mechanical analysis revealed that, at the elevated temperatures, improvement of mechanical properties due to the presence of nanoparticles was even more noticeable. Addition of nanoparticles resulted in increased thermal stability of PVA due to the reduction in mobility of matrix molecules by strong hydrogen bonds between nanocomposite components. Results indicated that, MINP and NCC have synergistic effect on improving of poly(vinyl alcohol properties. The VSM findings showed that the saturation magnetization of iron oxide nanoparticles reduced after modification. This can be attributed to formation of hydroxyapatite on nanoparticles surface. The saturation magnetization (Ms of PVA- MINP films was higher than PVA-MINP- NCC film. This result probably is related to more amount of magnetic nanoparticles in PVA-MINP films.

Fabrication and application of coaxial polyvinyl alcohol/chitosan nanofiber membranes

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Kuo Ting-Yun

2017-12-01

Full Text Available It is difficult to fabricate chitosan-wrapped coaxial nanofibers, because highly viscous chitosan solutions might hinder the manufacturing process. To overcome this difficulty, our newly developed method, which included the addition of a small amount of gum arabic, was utilized to prepare much less viscous chitosan solutions. In this way, coaxial polyvinyl alcohol (PVA/chitosan (as core/shell nanofiber membranes were fabricated successfully by coaxial electrospinning. The core/shell structures were confirmed by TEM, and the existence of PVA and chitosan was also verified using FT-IR and TGA. The tensile strength of the nanofiber membranes was increased from 0.6-0.7 MPa to 0.8-0.9 MPa after being crosslinked with glutaraldehyde. The application potential of the PVA/chitosan nanofiber membranes was tested in drug release experiments by loading the core (PVA with theophylline as a model drug. The use of the coaxial PVA/chitosan nanofiber membranes in drug release extended the release time of theophylline from 5 minutes to 24 hours. Further, the release mechanisms could be described by the Korsmeyer-Peppas model. In summary, by combining the advantages of PVA and chitosan (good mechanical strength and good biocompatibility respectively, the coaxial PVA/chitosan nanofiber membranes are potential biomaterials for various biomedical applications.

Quantitative comparison between the gel-film and polyvinyl alcohol methods for dehydrogenase histochemistry reveals different intercellular distribution patterns of glucose-6-phosphate and lactate dehydrogenases in mouse liver

NARCIS (Netherlands)

Griffini, P.; Vigorelli, E.; Bertone, V.; Freitas, I.; van Noorden, C. J.

1994-01-01

The precise histochemical localization and quantification of the activity of soluble dehydrogenases in unfixed cryostat sections requires the use of tissue protectants. In this study, two protectants, polyvinyl alcohol (PVA) and agarose gel, were compared for assaying the activity of lactate

Fabrication of Antibacterial Poly(Vinyl Alcohol Nanocomposite Films Containing Dendritic Polymer Functionalized Multi-Walled Carbon Nanotubes

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Andreas Sapalidis

2018-03-01

Full Text Available A series of poly(vinyl alcohol (PVA nanocomposite films containing quaternized hyperbranched polyethyleneimine (PEI functionalized multi-walled carbon nanotubes (ox-CNTs@QPEI are prepared by solvent casting technique. The modified carbon-based material exhibits high aqueous solubility, due to the hydrophilic character of the functionalized hyperbranched dendritic polymer. The quaternized PEI successfully wraps around nanotube walls as polycations provide electrostatic repulsion. Various contents of ox-CNTs@QPEI ranging from 0.05 to 1.0% w/w were employed to prepare functionalized PVA nanocomposites. The developed films exhibit adequate optical transparency, improved mechanical properties and extremely high antibacterial behavior due to the excellent dispersion of the functionalized CNTs into the PVA matrix.

Influence of Polyvinyl Alcohol (PVA) Addition on Silica Membrane Performance Prepared from Rice Straw

Science.gov (United States)

Wahyuningsih, S.; Ramelan, A. H.; Wardoyo, D. T.; Ichsan, S.; Kristiawan, Y. R.

2018-03-01

The utilization and modification of silica from rice straw as the main ingredient of adsorbent has been studied. The aim of this study was to determine the optimum composition of PVA (polyvinyl alcohol): silica to produce adsorbents with excellent pore characteristics, optimum adsorption efficiency and optimum pH for methyl yellow adsorptions. X-Ray Fluorescence (XRF) analysis results showed that straw ash contains 82.12 % of silica (SiO2). SAA (Surface Area Analyzer) analysis showed optimum composition ratio 5:5 of PVA: silica with surface area of 1.503 m2/g. Besides, based on the pore size distribution of PVA: silica (5:5) showed the narrow pore size distribution with the largest pore cumulative volume of 2.8 x 10-3 cc/g. The optimum pH for Methanyl Yellow adsorption is pH 2 with adsorption capacity = 72.1346%.

The influence of ionizing radiation on the properties of starch-PVA films

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Abramowska Anna

2015-09-01

Full Text Available The cornstarch: poly(vinyl alcohol (PVA films characterized by the alternating ratio of starch:PVA (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 and containing 30% of glycerol were prepared by solution casting. The films were irradiated with an absorbed dose of 25 kGy with gamma rays in a vacuum and with fast electrons in the air. The films characterized by a high content of starch appeared stiff, while the films characterized by a high content of PVA were highly flexible. The tensile strength and flexibility, as well as swelling and hydrophilicity, increased with the increase in the PVA content in the films. However, the tensile strength and wetting angle values achieved a minimum at an intermediate composition. It was found that irradiation enables to reduce hydrophilicity of the films accompanied by a decrease in their flexibility. No general conclusion concerning the effect of irradiation on tensile strength and swelling behavior can be derived. An increase in the homogeneity of the films and an increase in the compatibility of their components was found by scanning electron microscopy (SEM. Strong interactions of the starch and the PVA components were discovered by diffuse reflectance spectroscopy. Degradation was found to be the prevailing process occurring in the films under the influence of irradiation. The possible accompanying crosslinking is discussed in terms of the gel content in the samples. Creation of various oxidation products in the films characterized by the modified composition was observed under the influence of irradiation carried out in the air. Basing on the obtained results it can be supposed that the selected starch-PVA compositions might appear useful as packagings of the products predicted for radiation decontamination.

Biodegradable Mulches Based on Poly(vinyl Alcohol, Kenaf Fiber, and Urea

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Boon Khoon Tan

2015-07-01

Full Text Available This paper describes the preparation of poly(vinyl alcohol/kenaf fiber (PVOH/KF composites with entrapped urea. The major FTIR peaks of these composites could be identified. These composites are intended for agricultural applications as biodegradable mulches and could be potential carrier materials for fertilizer. The water solubility, release behavior, chemical properties, and thermal stability of the composites were evaluated. The composites lost 25% of their weight after 7 days in water. In a wet environment, urea was released from the composites through its dissolution in water, and around 57% of the urea was released from the composites in 24 h; Thermagravimetric analysis showed that these composites were stable up 150 C. These composites would be able to withstand rain and protect seedlings from the sun when applied in the field as mulches. For around three to four weeks, these biobased mulches could slowly disintegrate as the PVOH binder was gradually dissolved by moisture, releasing the kenaf fibers to serve as soil fertilizer without leaving any undegradable waste for disposal. Hence, they would not pose any risks to the land or biological systems.

ESR Study of the polyvinyl alcohol gamma-ray induced free-radicals

International Nuclear Information System (INIS)

Rosas S, E.

1994-01-01

This work reports the findings of the molecular weight effect on the electron spin resonance saturation curve of the gamma-ray irradiated polyvinyl alcohol, G-RIPVA. It has been noted that Pva of a lower molecular weight, between 13,000-23,000, show some noticeable differences in the electron spin resonance, ESR, response as a function of the gamma-ray dose in the 1-100 k Gy range than the one reported in the literature with molecular weight of 108,000. Results show a linear response in the log-log plot of the dose vs ESR signal intensity for samples based on G-RIPVA of the lower molecular weight as contrasted with the non-linear ESR response of G-RIPVA of higher molecular weight in the above named dose range. Such a result has been assumed to arise from the shorter molecular chains for the case of the lower molecular weight samples making this to increase the production of Pva free radicals with respect to the absorbed studied doses. Also, a discussion on the nature and stability of the Pva free radicals will be given. (Author)

Physical changes on the radiation and heat induced poly(Vinyl alcohol) fibers

Energy Technology Data Exchange (ETDEWEB)

Nho, Young Chang; Park, Kyung Ran; Park, Jong Seok; Lim, Youn Mook; Kang, Phil Hyun [Research Division for Industry and Environment, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-11-15

Poly(vinyl alcohol) (PVA) has high tensile strength and flexibility as well as oxygen barrier properties. The water, which acts as a plasticizer, reduces the tensile strength of PVA and swells PVA as well. It needs to have high water-resistant depending on its applications, especially for the use as tire cords. The aim of this work was to investigate the effect of the annealing temperature and radiation on the Gel content and tensile strength of PVA fbers. For this purpose, gel fraction and tensile strength were determined and analyzed. Annealing was performed in the temperature range of 120-180℃ for 10 min. PVA fbers were irradiated by using a conventional electron beam irradiation at a radiation dose of 50⁓200 kGy, at a dose of 10 kGy/pass at room temperature (acceleration voltage of 1 MeV). Annealing markedly increased the Gel content and the tensile strength of PVA fbers. However irradiation lowered the Gel content and the tensile strength of PVA fbers because they were degraded easily by radiation.

In vitro release of metformin hydrochloride from sodium alginate/polyvinyl alcohol hydrogels.

Science.gov (United States)

Martínez-Gómez, Fabián; Guerrero, Juan; Matsuhiro, Betty; Pavez, Jorge

2017-01-02

Hydrogels, based on polysaccharides have found a number of applications as drug delivery carriers. In this work, hydrogels of full characterized sodium alginate (Mn 87,400g/mol) and commercial poly(vinyl alcohol) (PVA) sensitive to pH and temperature stimuli were obtained using a simple, controlled, green, low cost method based on freeze-thaw cycles. Stable hydrogels of sodium alginate/PVA with 0.5:1.5 and 1.0:1.0w/v concentrations showed very good swelling ratio values in distilled water (14 and 20g/g, respectively). Encapsulation and release of metformin hydrochloride in hydrogels of 1.0:1.0w/v sodium alginate/PVA was followed by UV spectroscopy. The hydrogel released a very low amount of metformin hydrochloride at pH 1.2; the highest release value (55%) was obtained after 6h at pH 8.0. Also, the release of metformin hydrochloride was studied by 1 H NMR spectroscopy, the temporal evolution of methyl group signals of metformin showed 30% of drug release after 3h. Copyright © 2016 Elsevier Ltd. All rights reserved.

DEVELOPMENT OF ADHESIVE TO THE BASIS OF CORN AND CASSAVA STARCH

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Rosane Furtado Fabrício

2014-05-01

Full Text Available Corn and native cassava starch were modified by oxidation and acid hydrolysis, aiming to develop paper and paperboard stickers. The oxidation was made with Sodium hypochlorite (NaOCl in two distinct concentrations of active chloride which is present on oxidizing agent solution. The synthesis resulting products were used to make stickers and they were compared to corn and cassava starch based stickers without any modification, as well as commercial stickers based on polyvinyl acetate (PVA. Two different methodologies were tested using acid hydrolysis to modify corn and cassava starch, both using phosphoric acid (H3PO4 in order to obtain dextrin and subsequently use it in the production of stickers and also comparing them to petrochemical-based commercial stickers. Considering the different starch modifications methods (oxidation and acid hydrolysis, stickers based on renewable raw material were obtained, which combine biodegradability, low costs and availability.

Combination of the production of starch and of alcohol in alcohol plants

Energy Technology Data Exchange (ETDEWEB)

Burman, M E; Yurchenko, E I

1958-01-01

A flow sheet is presented to show how, when cheap potatoes are available, some can be side-tracked from ethanol fermentation and be used fo the production of starch. The additional equipment needed, like centrifuges, is listed. The starch can be saccharified and made available for ethanol production again if required.

Synthesis and Characterization of Fe3O4 Nanoparticles using Polyvinyl Alcohol (PVA) as Capping Agent and Glutaraldehyde (GA) as Crosslinker

Science.gov (United States)

Budi Hutami Rahayu, Lale; Oktavia Wulandari, Ika; Herry Santjojo, Djoko; Sabarudin, Akhmad

2018-01-01

The use of polyvinyl alcohol (PVA) as a capping agent and glutaraldehyde (GA) as a crosslinker for a synthesis of magnetite (Fe3O4) nanoparticles is able to reduce agglomeration of produced Fe3O4. Additionally, oxidation of Fe3O4 by air could be avoided. The synthesis is carried out in two steps: first step, magnetite (Fe3O4) nanoparticles were prepared by dissolving the FeCl3.6H2O and FeCl2.4H2O in alkaline media (NH3.H2O). The second step, magnetite nanoparticles were coated with polyvinyl alcohol (PVA) and glutaraldehyde (GA) to obtain Fe3O4-PVA-GA. The latter material was then characterized by FTIR to determine the typical functional groups of magnetite coated with PVA-GA. X-ray Diffraction analysis was used to determine structure and size of crystal as well as the percentage of magnetite produced. It was found that the produced nanoparticles have crystal sizes around 4-9 nm with the cubic crystal structure. The percentage of magnetite phase increases when the amount of glutaraldehyde increased. SEM-EDX was employed to assess the surface morphology and elemental composition of the resulted nanoparticles. The magnetic character of the magnetite and Fe3O4- PVA-GA were studied using Electron Spin Resonance.

Growth and characteristics of PbS/polyvinyl alcohol nanocomposites for flexible high dielectric thin film applications

International Nuclear Information System (INIS)

Hmar, J.J.L.; Majumder, T.; Mondal, S.P.

2016-01-01

PbS/polyvinyl alcohol (PbS/PVA) nanocomposites have been grown by a chemical bath deposition process at various growth temperatures (60–100 °C). Transmission electron microscopy (TEM) study revealed the formation of PbS nanoparticles of diameter 6–20 nm encapsulated in PVA matrix. Optical band gap of the nanocomposite films have been found to decrease (1.45 eV–0.67 eV) with increase in growth temperature from 60 °C to 100 °C. The impedance measurements have been carried out by depositing the PbS/PVA films on indium tin oxide (ITO) coated flexible polyethylene terephthalate (PET) substrates. The room temperature dielectric permittivity and ac conductivity measurements have been carried out for ITO/PbS/PVA/Al devices deposited at various growth temperatures. The nanocomposite films demonstrate superior dielectric permittivity compare to pure PVA polymer. The flexibility studies of ITO/PbS/PVA/Al devices have been performed at different bending angles. - Highlights: • PbS nanoparticles of diameter 6–20 nm were grown in polyvinyl (PVA) matrix. • Optical band gap of nanocomposite films was varied from 1.45–0.67 eV. • The nanocomposite thin films demonstrated superior dielectric permittivity. • Flexibility study of thin film devices was performed at various bending angles.

Tensile and Water Absorption Properties of Biodegradable Composites Derived from Cassava Skin/ Polyvinyl Alcohol with Glycerol as Plasticizer

International Nuclear Information System (INIS)

Dayangku Intan Munthoub; Wan Aizan Wan Abdul Rahman

2011-01-01

Natural organic and abundant resources biopolymers received more attention due to their low cost, availability and degradability after usage. Cassava skin was used as natural fillers to the polyvinyl alcohol (PVA). Cassava skin/ poly vinyl alcohol blends were compounded using melt extrusion twin screw extruder and test samples were prepared using the compression method. Various ratios of cassava skin and glycerol were investigated to identify suitable composition based on the water absorption and tensile properties. The water absorption of the cassava skins/ PVA samples increased at higher composition of cassava skin due to their hydrophilic properties but decrease with glycerol content. The strength of the cassava skins/ PVA samples increased with the higher composition of cassava skin up to 70 wt % while gradually decreased with the increasing composition of glycerol. The Young modulus increased with glycerol content but decreased with fibre loading up to 70 wt %. Elongation at break decreased with fibre loading and glycerol up to 70 wt % and 30 phr, respectively. (author)

Mechanical and electromagnetic interference shielding Properties of poly(vinyl alcohol)/graphene and poly(vinyl alcohol)/multi-walled carbon nanotube composite nanofiber mats and the effect of Cu top-layer coating.

Science.gov (United States)

Fujimori, Kazushige; Gopiraman, Mayakrishnan; Kim, Han-Ki; Kim, Byoung-Suhk; Kim, Ick-Soo

2013-03-01

We report the mechanical property and electromagnetic interference shielding effectiveness (EMI SE) of poly(vinyl alcohol) (PVA)/graphene and PVA/multi-walled carbon nanotube (MWCNT) composite nanofibers prepared by electrospinning. The metal (Cu) was deposited on the resultant PVA composite nanofibers using metal deposition technique in order to improve the mechanical properties and EMI shielding properties. The resulting PVA composite nanofibers and Cu-deposited corresponding nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Tensile tests were performed on the PVA/graphene and PVA/MWCNT composite nanofibers. The tensile strength of the PVA/graphene and PVA/MWCNT composite nanofibers was found to be 19.2 +/- 0.3 MPa at graphene content - 6.0 wt% and 12.2 +/- 0.2 MPa at MWCNT content - 3.0 wt%, respectively. The EMI SE of the Cu-deposited PVA/graphene composite nanofibers was significantly improved compared to pure PVA/graphene composite nanofibers, and also depended on the thickness of Cu metal layer deposited on the PVA composite nanofibers.

Fumed Silica Nanoparticles Incorporated in Quaternized Poly(Vinyl Alcohol Nanocomposite Membrane for Enhanced Power Densities in Direct Alcohol Alkaline Fuel Cells

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Selvaraj Rajesh Kumar

2015-12-01

Full Text Available A nanocomposite polymer membrane based on quaternized poly(vinyl alcohol/fumed silica (QPVA/FS was prepared via a quaternization process and solution casting method. The physico-chemical properties of the QPVA/FS membrane were investigated. Its high ionic conductivity was found to depend greatly on the concentration of fumed silica in the QPVA matrix. A maximum conductivity of 3.50 × 10−2 S/cm was obtained for QPVA/5%FS at 60 °C when it was doped with 6 M KOH. The permeabilities of methanol and ethanol were reduced with increasing fumed silica content. Cell voltage and peak power density were analyzed as functions of fumed silica concentration, temperature, methanol and ethanol concentrations. A maximum power density of 96.8 mW/cm2 was achieved with QPVA/5%FS electrolyte using 2 M methanol + 6 M KOH as fuel at 80 °C. A peak power density of 79 mW/cm2 was obtained using the QPVA/5%FS electrolyte with 3 M ethanol + 5 M KOH as fuel. The resulting peak power densities are higher than the majority of published reports. The results confirm that QPVA/FS exhibits promise as a future polymeric electrolyte for use in direct alkaline alcoholic fuel cells.

Characterization and application of zeolitic imidazolate framework-8@polyvinyl alcohol nanofibers mats prepared by electrospinning

Science.gov (United States)

Fan, Xiaoxiao; Yu, Linling; Li, Lianghao; Yang, Cao; Wen, Junjie; Ye, Xiaokun; Cheng, Jianhua; Hu, Yongyou

2017-02-01

In this study, Zeolitic imidazolate framework-8@polyvinyl alcohol (ZIF-8@PVA) nanofibers were creatively fabricated by electrospinning technique, and the nanofibers membranes were characterized by SEM, TEM, XRD, FTIR, TG, DSC, DTA, BET. Its thermal stability, mechanical property, water stability and adsorption nature were also performed. The optimized fabrication parameter of the ZIF-8@PVA was 10 wt% and the uniform diameters of the nanofibers has been obtained. In addition, the ZIF-8@PVA nanofibers displayed unique properties such as a water stable and flexible structure. The adsorption test for Congo red treatment revealed that the nanofibers had a great adsorption performance. The results indicated that the nonwoven fiber mats had a great potential as a new type of membrane adsorbents in wastewater purification. The possible mechanism of CR adsorption onto ZIF-8@PVA was researched.

Enzymic hydrolysis of starch in continuous alcoholic fermentation

Energy Technology Data Exchange (ETDEWEB)

Yarovenko, V.L.; Pykhova, S.V.; Ustinnikov, B.A.; Lazareva, A.N.; Makeev, D.M.

1965-01-01

Fermentations were conducted on a plant scale, using starch of various origins, e.g., potatoes, wheat, and other cereals, and as enzyme source a number of strains of Aspergillus oryzae, A. awamori, A. usamii, A. niger, A. batatae, and Bacillus mesentericus. The starches were broken down to a molecular weight between 900 and 1600; time requirements differed from those commonly known. Comparison of these enzymic actions to that of standard malt discloses that in breaking down a potato starch from a molecular weight of 268,000 to one of 1353 to 1556, the malt and A. Oryzae require 1 hour, whereas A. awamori and B. mesentericus require 18, and a different strain of A. awamori requires 24 hours.

Structure-sensitive film materials based on polyvinyl alcohol compositions with polyacids

Science.gov (United States)

Lazareva, Tatjana G.; Iljushenko, Irina A.

1995-05-01

The influence of polyacidic additives (silicotungstic acid -- STA, carboxymethylcellulose -- Na-CMC, polymethacrylic acid -- PMA, polyacrylic acid -- PAA) on the molecular mobility of film composition based on polyvinyl alcohol (PVA) in the temperature range 20 - 200 degree(s)C has been evaluated. It has been concluded that interpolymer complexes are formed due to hydrogen bonding of the PVA and polyacidic additive molecules, which results in the change of the PVA stereoregularity. The formation of the complexes depends on the type and concentration of the polyacidic additive, the process of (alpha) -relaxation and, in a certain concentration range of the additive, increases the molecular mobility of the kinetic segments surrounding the complex. The influence of short-term UV-irradiation on the structure and properties of such materials has been investigated. A possibility of the reversible change of molecular mobility and stereoregularity of the examined compositions as a result of short-term UV-irradiation has been established. Introduction of polyacids into the PVA structure gives rise to the electrosensitivity, i.e., the ability to change structure under the action of an electric field. In this case the distinguishing feature is the relation between the molecular mobility and electrosensitivity in the range of parameters where the (alpha) - relaxation occurs.

Preparation and properties of poly(vinyl alcohol)-g-octadecanol copolymers based solid–solid phase change materials

International Nuclear Information System (INIS)

Shi Haifeng; Li Jianhua; Jin Yanmei; Yin Yiping; Zhang Xingxiang

2011-01-01

Highlights: ► In this paper, our objective is just focused on the preparation and characterization of such SSPCMs aiming at providing one suitable material for improving the thermal stability and preventing the liquid leakage from the matrix. Here, the SSPCMs can be fabricated by grafting to method between poly(vinyl alcohol) and octadecanol, which the grafting ratio can be controlled by adjusting the feeding components. ► The thermal properties, crystalline structure and morphology were detailed studies by WAXD, FT-IR, TGA and DSC, proving that the PVA-g-octadecanol process the better thermal storage ability and thermal stability. Compared with pure octadecanol, the heat fusion of PVA-g-octadecanol decreased due to the mobility confinement and the lower rearrangements of C18 alkyl side chains. ► This result is for the first time reported, and is a meaningful result for the investigation of the solid–solid phase change materials, and the preparation process provides one template-directed approach to obtain the high-performance materials with the better heat storage and thermal stability. - Abstract: The heat storage and phase transition behavior of a series of poly(vinyl alcohol)-g-octadecanol copolymers (PVA-g-C18OH) with apparent grafting ratios ranging from 283 to 503%, synthesized through “grafting to” method, has been investigated by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). PVA-g-C18OH copolymers exhibit the better thermal stability against C18OH, and the thermal energy storage ability (ΔH m ) is of dependence on the apparent grafting ratios. Compared with C18OH, the lower thermal storage efficiency possible is attributed to the less CH 2 groups entered into the crystalline domains and the frustrated mobility of the grafted C18 alkyl side chains between PVA backbones. The results show that

Modification of Foamed Articles Based on Cassava Starch

International Nuclear Information System (INIS)

Ponce, P.

2006-01-01

This work reports the influence of radiation, plasticizers and poly vinyl alcohol (PVA) on the barrier properties [water vapour permeability (WVP)) and mechanical properties (tensile strength and elongation; compression resistance and flexibility) of foamed articles based on cassava starch. The starch foam was obtained by thermopressing process. Poly ethylene glycol (PEG, 300) was selected as plasticizer and water was necessary for the preparation of the foams. The foamed articles based on cassava starch were irradiated at low doses of 2 and 5 kGy, commonly used in food irradiation. The mechanical properties of starch foams are influenced by the plasticizer concentration and by irradiation dose. An increase in PEG content showed a considerable increase in elongation percentage and a decrease in the tensile strength of the foams; also increase the permeability of the foams in water. After irradiation, the barrier properties and mechanical properties of the foams were improved due to chemical reactions among polymer molecules. Irradiated starch cassava foams with poly vinyl alcohol (PVA) have good flexibility and low water permeability. WVP can be reduced by low doses of gamma radiation

In vitro mechanical fatigue behavior of poly-ɛ-caprolactone macroporous scaffolds for cartilage tissue engineering: Influence of pore filling by a poly(vinyl alcohol) gel.

Science.gov (United States)

Panadero, J A; Vikingsson, L; Gomez Ribelles, J L; Lanceros-Mendez, S; Sencadas, V

2015-07-01

Polymeric scaffolds used in regenerative therapies are implanted in the damaged tissue and submitted to repeated loading cycles. In the case of articular cartilage engineering, an implanted scaffold is typically subjected to long-term dynamic compression. The evolution of the mechanical properties of the scaffold during bioresorption has been deeply studied in the past, but the possibility of failure due to mechanical fatigue has not been properly addressed. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading-unloading cycles. In this work fatigue studies of polycaprolactone scaffolds were carried by subjecting the scaffold to repeated compression cycles in conditions simulating the scaffold implanted in the articular cartilage. The behavior of the polycaprolactone sponge with the pores filled with a poly(vinyl alcohol) gel simulating the new formed tissue within the pores was compared with that of the material immersed in water. Results were analyzed with Morrow's criteria for failure and accurate fittings are obtained just up to 200 loading cycles. It is also shown that the presence of poly(vinyl alcohol) increases the elastic modulus of the scaffolds, the effect being more pronounced with increasing the number of freeze/thawing cycles. © 2014 Wiley Periodicals, Inc.

Precursor concentration and temperature controlled formation of polyvinyl alcohol-capped CdSe-quantum dots

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Chetan P. Shah

2010-12-01

Full Text Available Polyvinyl alcohol-capped CdSe quantum dots, with a size within their quantum confinement limit, were prepared in aqueous solution at room temperature, by a simple and environmentally friendly chemical method. The size of the CdSe quantum dots was found to be dependent on the concentrations of the precursors of cadmium and selenium ions, as well as on the aging time and the reaction temperature; all of which could be used conveniently for tuning the size of the particles, as well as their optical properties. The synthesized quantum dots were characterized by optical absorption spectroscopy, fluorescence spectroscopy, X-ray diffraction, atomic force microscopy and transmission electron microscopy. The samples were fluorescent at room temperature; the green fluorescence was assigned to band edge emission, and the near-infrared fluorescence peaks at about 665 and 865 nm were assigned to shallow and deep trap states emissions, respectively. The quantum dots were fairly stable up to several days.

Therapeutic-Ultrasound-Triggered Shape Memory of a Melamine-Enhanced Poly(vinyl alcohol) Physical Hydrogel.

Science.gov (United States)

Li, Guo; Yan, Qiang; Xia, Hesheng; Zhao, Yue

2015-06-10

Therapeutic-ultrasound-triggered shape memory was demonstrated for the first time with a melamine-enhanced poly(vinyl alcohol) (PVA) physical hydrogel. The addition of a small amount of melamine (up to 1.5 wt %) in PVA results in a strong hydrogel due to the multiple H-bonding between the two constituents. A temporary shape of the hydrogel can be obtained by deformation of the hydrogel (∼65 wt % water) at room temperature, followed by fixation of the deformation by freezing/thawing the hydrogel under strain, which induces crystallization of PVA. We show that the ultrasound delivered by a commercially available device designed for the patient's pain relief could trigger the shape recovery process as a result of ultrasound-induced local heating in the hydrogel that melts the crystallized PVA cross-linking. This hydrogel is thus interesting for potential applications because it combines many desirable properties, being mechanically strong, biocompatible, and self-healable and displaying the shape memory capability triggered by a physiological stimulus.

Drying Shrinkage Behaviour of Fibre Reinforced Concrete Incorporating Polyvinyl Alcohol Fibres and Fly Ash

Directory of Open Access Journals (Sweden)

Amin Noushini

2014-01-01

Full Text Available The current study assesses the drying shrinkage behaviour of polyvinyl alcohol fibre reinforced concrete (PVA-FRC containing short-length (6 mm and long-length (12 mm uncoated monofilament PVA fibres at 0.125%, 0.25%, 0.375%, and 0.5% volumetric fractions. Fly ash is also used as a partial replacement of Portland cement in all mixes. PVA-FRC mixes have been compared to length change of control concrete (devoid of fibres at 3 storage intervals: early-age (0–7 days, short-term (0–28 days, and long-term (28–112 days intervals. The shrinkage results of FRC and control concrete up to 112 days indicated that all PVA-FRC mixes exhibited higher drying shrinkage than control. The shrinkage exhibited by PVA-FRC mixes ranged from 449 to 480 microstrain, where this value was only 427 microstrain in the case of control. In addition, the longer fibres exhibited higher mass loss, thus potentially contributing to higher shrinkage.

Water vapor permeation and dehumidification performance of poly(vinyl alcohol)/lithium chloride composite membranes

KAUST Repository

Bui, Duc Thuan

2015-10-09

Thin and robust composite membranes comprising stainless steel scaffold, fine and porous TiO2 and polyvinyl alcohol/lithium chloride were fabricated and studied for air dehumidification application. Higher hydrophilicity, sorption and permeation were observed for membranes with increased lithium chloride content up to 50%. The permeation and sorption properties of the membranes were investigated under different temperatures. The results provided a deeper insight into the membrane water vapor permeation process. It was specifically noted that lithium chloride significantly reduces water diffusion energy barrier, resulting in the change of permeation energy from positive to negative values. Higher water vapor permeance was observed for the membrane with higher LiCl content at lower temperature. The isothermal air dehumidification tests show that the membrane is suitable for dehumidifying air in high humid condition. Additionally, results also indicate a trade-off between the humidity ratio drop with the water vapor removal rate when varying air flowrate.

In vitro cytotoxicity of iron oxide nanoparticles: effects of chitosan and polyvinyl alcohol as stabilizing agents

Science.gov (United States)

Tran, Phong A.; Nguyen, Hiep T.; Fox, Kate; Tran, Nhiem

2018-03-01

Iron oxide magnetic nanoparticles have significant potential in biomedical applications such as in diagnosis, imaging and therapeutic agent delivery. The choice of stabilizers and surface functionalization is important as it is known to strongly influence the cytotoxicity of the nanoparticles. The present study aimed at investigating the effects of surface charges on the cytotoxicity of iron oxide nanoparticles. We used a co-precipitation method to synthesize iron oxide nanoparticles which were then stabilized with either chitosan (CS) or polyvinyl alcohol (PVA) which have net positive charge and zero charge at physiological pH, respectively. The nanoparticles were characterized in terms of size, charges and chemical oxidation state. Cytotoxicity of the nanoparticles was assessed using mouse fibroblast cells and was correlated with surface charges of the nanoparticles and their aggregation.

Influence of UV and Gamma radiations on the induced birefringence of stretched poly(vinyl) alcohol foils

Science.gov (United States)

Nechifor, Cristina-Delia; Zelinschi, Carmen Beatrice; Dorohoi, Dana-Ortansa

2014-03-01

The aim of our paper is to evidence the influence of Gamma and UV radiations on the induced birefringence of poly(vinyl alcohol) stretched foils. Thin foils of PVA were prepared and dried without modifying their surfaces. The polymeric foils were irradiated from 15 min to 6 h using UV and Gamma radiations. The induced by stretching under heating birefringence of PVA films was measured at λ = 589.3 nm with a Babinet Compensator. Physico-chemical processes (photo stabilization, photo degradation, oxidation) induced by irradiation of polymer matrix influence both the stretching degree and the anisotropy of etired foils. An increase of birefringence versus the stretching ratio of the PVA foils was evidenced for all studied samples. The dependence of the birefringence on the exposure time, stretching ratio and nature of radiation was also confirmed.

Self-assembled amphiphilic polyhedral oligosilsesquioxane (POSS) grafted poly(vinyl alcohol) (PVA) nanoparticles

International Nuclear Information System (INIS)

Sheikh, Faheem A.; Barakat, Nasser A.M.; Kim, Byoung-Suhk; Aryal, Santosh; Khil, Myung-Seob; Kim, Hak-Yong

2009-01-01

In the present study, spherical nanoparticles (NPs) containing polyhedral oligosilsesquioxane (POSS) as an inner hydrophobic core and poly(vinyl alcohol) PVA as a hydrophilic outer shell were prepared by dialysis approach. Preparation of amphiphilic POSS-grafted-PVA co-polymer was characterized by 1 H NMR and FT-IR. The results indicated urethane linkage between monoisocyanate group of POSS macromer and the hydroxyl groups of PVA. The dynamic light scattering (DLS) and electrophoretic light scattering (ELS) of the NPs revealed that they have an average hydrodynamic diameter and negative zeta (ζ)-potential of 215 nm and - 161 mV, respectively. Atomic force microscopy (AFM) and bio-transmission electron microscope (BIO-TEM) have shown unagglomerated NPs within a diameter range of 60-90 nm. The prepared NPs were investigated to improve the control release of anticancer drug; paclitaxel as a model drug. Due to drug loading, the hydrodynamic diameter and negative zeta (ζ)-potential have changed to 325 nm and - 14 mV, respectively. In addition, in-vitro drug release experiments were conducted; the obtained results explicated continuous release for over 40 days. However, in case of using pure drug only, the drug completely released within 1 h.

Raman vibrational spectra of thymol blue dyed polyvinyl alcohol (PVA) film dosimeters

International Nuclear Information System (INIS)

Lepit, A.; Saion, E.B.; Susilawati; Doyan, A.; Wan Yusoff, W.M.D.

2002-01-01

Radiation-sensitive dyed polyvinyl alcohol (PVA) film indicators containing chloral hydrate and acid-sensitive thymol blue dye have been studied for routine food irradiation dosimeters. The free standing dyed film dosimeters of different chloral hydrate concentrations (0.1, 0.5, 1.0, 2.0 and 2.5 g) were irradiated with the absorbed dose ranges from 1 kGy to 12 kGy using gamma rays from Co-60 teletherapy. Upon exposure the dosimeters undergo chemical change and become more acidic, resulting in colour change from yellow to red at the critical doses depending on the chloral hydrate concentrations. The radiation-induced change in colour was analysed using UV-Vis spectrometer that the absorption spectra produced two maximal of the visible bands peaking at 445 nm for low doses and 554 nm for high doses. Spectra of inelastic Raman scattering photons corresponding to Raman shift frequency of unirradiated and irradiated films were measured using a dispersive Raman spectrometer. The spectral intensity of C=C, C-0 and S-H molecular vibration peaks for their respective Raman shifts were studied which provide the dose response to the change of dye molecular structure of the dosimeters. (Author)

Preparation and characterization of oriented poly(vinyl alcohol)/carbon nanotube composite nanofibers

Science.gov (United States)

Shimizu, Akikazu; Kato, Hayato; Sato, Taiga; Kushida, Masahito

2017-07-01

Oriented nanofiber mats blended with carbon nanotubes (CNTs) are expected to be applied as cell seeding scaffolds. Biomaterials that are often used for cell seeding scaffolds generally have low mechanical strength and low electrical conductivity; thus, it has been difficult to apply them to tissues such as heart and nerve. In this study, we prepared oriented poly(vinyl alcohol) (PVA) nanofiber mats blended with various CNT concentrations (up to 10 wt %) by electrospinning using the parallel plate electrodes as collectors with applied voltage. The morphology, mechanical properties, and electrical properties of the prepared oriented nanofiber mats were measured by using various techniques such as scanning electron microscopy (SEM). The tensile strength of the oriented nanofiber mats in the applied voltage direction increased from 2.5 to 9.7 MPa with CNT concentration. Furthermore, the electrical conductivity of the oriented nanofiber mats in the applied voltage direction increased from 0.67 × 10-7 to 4.3 × 10-7 S·m-1. Also, the mechanical strength and electrical conductivity of the oriented nanofiber mats in the applied voltage direction were 3-4 and 2-3 times higher than those in the perpendicular direction, respectively.

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure.

Science.gov (United States)

Sun, Xiaoxia; Uyama, Hiroshi

2013-10-04

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields.

In vitro characterization of polyvinyl alcohol assisted hydroxyapatite derived by sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Kaygili, Omer, E-mail: okaygili@firat.edu.tr [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Keser, Serhat [Department of Chemistry, Faculty of Science, Firat University, 23119 Elazig (Turkey); Al Orainy, R.H. [Physics Department, Sciences of Faculty for Girls, King Abdulaziz University, Jeddah (Saudi Arabia); Ates, Tankut [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Yakuphanoglu, Fahrettin [Department of Physics, Faculty of Science, Firat University, 23119 Elazig (Turkey); Physics Department, Sciences of Faculty for Girls, King Abdulaziz University, Jeddah (Saudi Arabia)

2014-02-01

The synthesis and characterization of sol–gel derived hydroxyapatite (HAp) were investigated with the effects of the addition of polyvinyl alcohol (PVA) to the structural and material in vitro behavior. All samples were soaked in simulated body fluid (SBF) for 14 and 28 days. The characterization of bioceramics before and after immersing in SBF was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. After the simulated body fluid period, the crystal structure and phase of HAp samples did not change significantly. The characteristic bands of hydroxyl, phosphate and carbonate groups were detected. HAp exhibited a thermal stability of room temperature to 1000 °C. The surface morphologies of the samples show an evident change with the soaking period in SBF. - Highlights: • The soaking period in SBF affects the surface morphology. • The Ca/P molar ratios change with the immersion time. • The as-prepared samples thermally stable from ∼ 25 to 1000 °C.

In vitro characterization of polyvinyl alcohol assisted hydroxyapatite derived by sol–gel method

International Nuclear Information System (INIS)

Kaygili, Omer; Keser, Serhat; Al Orainy, R.H.; Ates, Tankut; Yakuphanoglu, Fahrettin

2014-01-01

The synthesis and characterization of sol–gel derived hydroxyapatite (HAp) were investigated with the effects of the addition of polyvinyl alcohol (PVA) to the structural and material in vitro behavior. All samples were soaked in simulated body fluid (SBF) for 14 and 28 days. The characterization of bioceramics before and after immersing in SBF was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. After the simulated body fluid period, the crystal structure and phase of HAp samples did not change significantly. The characteristic bands of hydroxyl, phosphate and carbonate groups were detected. HAp exhibited a thermal stability of room temperature to 1000 °C. The surface morphologies of the samples show an evident change with the soaking period in SBF. - Highlights: • The soaking period in SBF affects the surface morphology. • The Ca/P molar ratios change with the immersion time. • The as-prepared samples thermally stable from ∼ 25 to 1000 °C

Effects of Partial Replacement of Eggshell Powder by Halloysite Nanotubes on the Properties of Polyvinyl Alcohol Composites

Science.gov (United States)

Alias, N. F.; Ismail, H.

2018-06-01

Polyvinyl alcohol (PVA)/eggshell powder (ESP) were prepared via solution casting method. The effects of gradual replacement of ESP by halloysite nanotubes (HNTs) were investigated based on tensile properties, physical properties and biodegradability. The main objective is to study the effect of hybrid fillers and also to compare the properties of PVA/ESP composite with conventional filler, HNT. The tensile properties decreased with increasing HNT loading. Scanning electron microscopy (SEM) studies showed that agglomeration of filler were present throughout the composites. Due to the presence of hydroxyl group on the outer and inner surface of HNT, the water absorption and water vapor transmisibility were found to increase with increasing HNTs loading. The biodegradability of film filled with HNT is lower compared to the film filled with ESP.

Mechanical and electro-rheological properties of electrospun poly(vinyl alcohol) nanofibre mats filled with carbon black nanoparticles

International Nuclear Information System (INIS)

Chuangchote, Surawut; Sirivat, Anuvat; Supaphol, Pitt

2007-01-01

The present contribution reports, for the first time, the mechanical and electro-rheological properties of electrospun poly(vinyl alcohol) (PVA) nanofibre mats with or without the incorporation of carbon black (CB) nanoparticles. The effects of sonication and the addition of CB on morphological appearance, average diameter of the as-spun fibre mats, and that of the individual fibres, were thoroughly investigated. Incorporation of CB (1-10% based on the weight of PVA) in 10% w/v PVA solution did not affect the morphology and average diameter of the obtained fibres (∼160 nm), but it affected both the mechanical and the electro-rheological properties of the as-spun PVA/CB fibre mats, in which the mats became more rigid with the addition and increasing amount of CB

Poly(aniline-co-m-aminobenzoic acid) deposited on poly(vinyl ...

Indian Academy of Sciences (India)

Abstract. In this work, we have deposited poly(aniline-co-m-aminobenzoic acid) on poly(vinyl alcohol) (PVA) by in situ ... along the polyaniline (PANI) chain results in self dop- ing of PANI and ..... The value of electrical conductivity is found to be ...

Structural analysis of poly(vinyl alcohol hydrogels) produced by freezing and thawing process Positron annihilation lifetime spectroscopy (PALS)

International Nuclear Information System (INIS)

Paranhos, Caio M.; Oliveira, Renata N.; Soares, Bluma G.

2005-01-01

In this work, poly(vinyl alcohol) hydrogels with a entrapped polyelectrolyte were characterized through Positron Annihilation Lifetime Spectroscopy (PALS). PALS was used to determine the average pore radii (R), average free volume (V f ) and the intensity of ortho-positronium (I 3 ). The free volume estimated for the hydrogels increases with increasing polyelectrolyte content, while the intensity of o-Ps decreases with the increasing polyelectrolyte content. Degree of crystallinity of the samples decreases with the presence of polyelectrolyte. The structural changes observed can be discussed in terms of the changes in hydrogels structure due to a hindrance capacity of the polyelectrolyte on the crystalline behavior and the different polymer-polymer interactions. (author)

Repeated courses of transarterial embolization with polyvinyl alcohol particles: 'long life elixir' in a cirrhotic patient with unresectable hepatocellular carcinoma.

Science.gov (United States)

Marelli, Laura; Shusang, Vibhakorn; Senzolo, Marco; Cholongitas, Evangelos; Goode, Antony; Yu, Dominic; Patch, David W; Burroughs, Andrew K

2007-04-01

Chemoembolization improves survival in selected cirrhotic patients with hepatocellular carcinoma, but prolonged survival is unusual. In this study, a 70-year-old cirrhotic patient, who had a histologically proven hepatocellular carcinoma of 5 cm diameter, embolization with polyvinyl alcohol particles alone, without chemotherapeutic agent, has resulted in continued survival, of 5 years to date, with virtual elimination of residual hypervascularity following 10 sessions of embolization, and with continued patency of the injected branch of the hepatic artery. Provided liver function is maintained, embolization alone appears a feasible long term and effective therapy for unresectable hepatocellular carcinoma.

Plasticized Starch Based Bionanocomposites Containing Cellulose Nanowhiskers and Titanium Dioxide Nanoparticles: Study of Structure and Water Vapor Permeability

Directory of Open Access Journals (Sweden)

Nasrin Jamshidi Kaljahi

2014-08-01

Full Text Available The starch-based films have some disadvantages such as weak mechanical and poor water barrier properties that restrict their applications in food packaging. In the present research, to improve the properties of the starch films, a constant level of citric acid and polyvinyl alcohol (PVA (10% with different amounts of glycerol (GLY as a lubricating agent, crystal nanowhiskers (CNW and titanium dioxide (TiO2 nanoparticles were used together. Finally, the effects of these compounds on permeability properties of the obtained starch-based bionanocomposites were studied and their optimum values were determined by central composite design of response surface methodology (RSM. The results of X-Ray diffraction (XRD test showed that at low levels of TiO2 and CNW there was no diffractogram peak obtained. However, at high levels of TiO2 and CNW there emerged distinct and sharp peak which was attributed to greater crystalline region and probably non-homogeneity in particle distribution. The Fourier transmission infrared (FTIR data showed that addition of CNW and TiO2 increased hydrogen binding between the nanofillers and biopolymer matrix. The effects of TiO2 and CNW concentrations as quadratic and glycerol concentration as linear and quadratic were significant on water vapor permeability (WVP. The optimum levels of TiO2, CNW and GLY for obtaining minimum WVP corresponded to 0.118, 0.3 g and 1.06 mL, respectively.

Biodegradable starch-based polymeric materials

Science.gov (United States)

Suvorova, Anna I.; Tyukova, Irina S.; Trufanova, Elena I.

2000-05-01

The effects of low-molecular-weight additives, temperature and mechanical action on the structure and properties of starch are discussed. Special attention is given to mixtures of starch with synthetic polymers, e.g., co-polymers of ethylene with vinyl acetate, vinyl alcohol, acrylic acid, cellulose derivatives and other natural polymers. These mixtures can be used in the development of novel environmentally safe materials (films, coatings, packaging materials) and various articles for short-term use. The bibliography includes 105 references.

Functionalized SiC nanocrystals for tuning of optical, thermal, mechanical and electrical properties of polyvinyl alcohol

DEFF Research Database (Denmark)

Saini, Isha; Sharma, Annu; Dhiman, Rajnish

2017-01-01

 MPa for PVA to 45 MPa for PVA-SiC nanocomposite film containing 0.023 wt% f-SiC nanocrystals at an applied load of 9.8 mN indicating improved interfacial interaction. Current-voltage analysis indicated an increase in conductivity of PVA with the introduction of f-SiC nanocrystals. The conduction......Polyvinyl alcohol (PVA)-SiC nanocomposite films were prepared by incorporating functionalized Silicon Carbide (f-SiC) nanocrystals in PVA matrix. Structural characterization of SiC nanocrystals before and after the functionalization was carried out using Fourier transform infrared spectroscopy...... (FTIR), X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). Transmission electron microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to study the morphology and size distribution of f-SiC nanocrystals in PVA-SiC nanocomposite films. TEM and SEM images depict an improved...

Radiation preparation of graphene/carbon nanotubes hybrid fillers for mechanical reinforcement of poly(vinyl alcohol) films

Science.gov (United States)

Ma, Hui-Ling; Zhang, Long; Zhang, Youwei; Wang, Shuojue; Sun, Chao; Yu, Hongyan; Zeng, Xinmiao; Zhai, Maolin

2016-01-01

Graphene/carbon nanotubes (G/CNTs) hybrid fillers were synthesized by γ-ray radiation reduction of graphene oxide (GO) in presence of CNTs. The obtained hybrid fillers with three-dimensional (3D) interconnected network structure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Poly(vinyl alcohol) (PVA) composite films with enhanced mechanical properties and thermal stability were subsequently prepared by solution blending of G/CNTs with PVA matrix. The tensile strength and Young's modulus of PVA composite films containing 1 wt% G/CNTs were measured to be 81.9 MPa and 3.9 GPa respectively, which were 56% and 33.6% higher than those of pure PVA. These substantial improvements could be attributed to the interconnected 3D structure of G/CNTs, homogeneous dispersion as well as the strong hydrogen-bonding interaction between G/CNTs and PVA macromolecular chains.

Effect of hygroscopic materials on water vapor permeation and dehumidification performance of poly(vinyl alcohol) membranes

KAUST Repository

Bui, T. D.

2017-01-16

In this study, two hygroscopic materials, inorganic lithium chloride (LiCl) and organic triethylene glycol (TEG) were separately added to poly(vinyl alcohol) (PVA) to form blend membranes for air dehumidification. Water vapor permeation, dehumidification performance and long-term durability of the membranes were studied systematically. Membrane hydrophilicity and water vapor sorbability increased significantly with higher the hygroscopic material contents. Water vapor permeance of the membranes increased with both added hygroscopic material and absorbed water. Water permeation energy varied from positive to negative with higher hygroscopic content. This observation is attributed to a lower diffusion energy and a relatively constant sorption energy when hygroscopic content increases. Comparatively, PVA/TEG has less corrosive problems and is more environmentally friendly than PVA/LiCl. A membrane with PVA/TEG is observed to be highly durable and is suitable for dehumidification applications.

Preparation and properties of poly(vinyl alcohol/chitosan blend bionanocomposites reinforced with cellulose nanocrystals/ZnO-Ag multifunctional nanosized filler

Directory of Open Access Journals (Sweden)

Azizi S

2014-04-01

Full Text Available Susan Azizi,1 Mansor Bin Ahmad,1 Mohd Zobir Hussein,1 Nor Azowa Ibrahim,1 Farideh Namvar2,31Department of Chemistry, Faculty of Science, 2Institute of Tropical Forestry and Forest Products, University Putra Malaysia, Selangor, Malaysia; 3Mashhad Branch, Islamic Azad University, Mashhad, IranAbstract: A series of novel bionanocomposites were cast using different contents of zinc oxide-silver nanoparticles (ZnO-AgNPs stabilized by cellulose nanocrystals (CNC as multifunctional nanosized fillers in poly(vinyl alcohol/chitosan (PVA/Cs matrices. The morphological structure, mechanical properties, ultraviolet-visible absorption, and antimicrobial properties of the prepared films were investigated as a function of their CNC/ZnO-AgNP content and compared with PVA/chitosan/CNC bionanocomposite films. X-ray diffraction and field emission scanning electron microscopic analyses showed that the CNC/ZnO-AgNPs were homogeneously dispersed in the PVA/Cs matrix and the crystallinity increased with increasing nanosized filler content. Compared with pure PVA/Cs, the tensile strength and modulus in the films increased from 0.055 to 0.205 GPa and from 0.395 to 1.20 GPa, respectively. Ultraviolet and visible light can be efficiently absorbed by incorporating ZnO-AgNPs into a PVA/Cs matrix, suggesting that these bionanocomposite films show good visibility and ultraviolet-shielding effects. The bionanocomposite films had excellent antimicrobial properties, killing both Gram-negative Salmonella choleraesuis and Gram-positive Staphylococcus aureus. The enhanced physical properties achieved by incorporating CNC/ZnO-AgNPs could be beneficial in various applications.Keywords: multifunctional nanofiller, bionanocomposite, cellulose nanocrystals, antimicrobial properties, poly(vinyl alcohol/chitosan blend

Removal and adsorption characteristics of polyvinyl alcohol from aqueous solutions using electrocoagulation

Energy Technology Data Exchange (ETDEWEB)

Chou, Wei-Lung, E-mail: wlchou@sunrise.hk.edu.tw [Department of Safety, Health and Environmental Engineering, Hungkuang University, Sha-Lu, Taichung 433, Taiwan (China)

2010-05-15

The study was to investigate the performance of electrocoagulation (EC) for the efficient removal of polyvinyl alcohol (PVA) from aqueous solutions. Several parameters were evaluated to characterize the PVA removal efficiency, such as various electrode pairs, current densities, supporting electrolytes, temperatures, and initial electrolyte concentrations. The effects of the current density, supporting electrolyte, and temperature on the electrical energy consumption were also investigated. The experimental results indicate that a Fe/Al electrode pair is the optimum choice out of four different electrode pair combinations. The optimum current density, supporting electrolyte concentration, and temperature were found to be 5 mA cm{sup -2}, 0.008N NaCl, and 298 K, respectively. The PVA removal efficiency decreased with increasing in the initial concentrations. The kinetic studies indicated that the EC process was best described using pseudo-second-order kinetics. The experimental data were also compared to different adsorption isotherm models in order to describe the EC process. The adsorption of PVA was best fitted by the Langmuir adsorption isotherm model. Thermodynamic parameters such as the Gibbs free energy, enthalpy, and entropy indicated that the adsorption of PVA on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288-318 K.

Removal and adsorption characteristics of polyvinyl alcohol from aqueous solutions using electrocoagulation

International Nuclear Information System (INIS)

Chou, Wei-Lung

2010-01-01

The study was to investigate the performance of electrocoagulation (EC) for the efficient removal of polyvinyl alcohol (PVA) from aqueous solutions. Several parameters were evaluated to characterize the PVA removal efficiency, such as various electrode pairs, current densities, supporting electrolytes, temperatures, and initial electrolyte concentrations. The effects of the current density, supporting electrolyte, and temperature on the electrical energy consumption were also investigated. The experimental results indicate that a Fe/Al electrode pair is the optimum choice out of four different electrode pair combinations. The optimum current density, supporting electrolyte concentration, and temperature were found to be 5 mA cm -2 , 0.008N NaCl, and 298 K, respectively. The PVA removal efficiency decreased with increasing in the initial concentrations. The kinetic studies indicated that the EC process was best described using pseudo-second-order kinetics. The experimental data were also compared to different adsorption isotherm models in order to describe the EC process. The adsorption of PVA was best fitted by the Langmuir adsorption isotherm model. Thermodynamic parameters such as the Gibbs free energy, enthalpy, and entropy indicated that the adsorption of PVA on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288-318 K.

Effect of trap states and microstructure on charge carrier conduction mechanism through semicrystalline poly(vinyl alcohol) granular film

Science.gov (United States)

Das, A. K.; Bhowmik, R. N.; Meikap, A. K.

2018-05-01

We report a comprehensive study on hysteresis behaviour of current-voltage characteristic and impedance spectroscopy of granular semicrystalline poly(vinyl alcohol) (PVA) film. The charge carrier conduction mechanism and charge traps of granular PVA film by measuring and analyzing the temperature dependent current-voltage characteristic indicate a bi-stable electronic state in the film. A sharp transformation of charge carrier conduction mechanism from Poole-Frenkel emission to space charge limited current mechanism has been observed. An anomalous oscillatory behaviour of current has been observed due to electric pulse effect on the molecular chain of the polymer. Effect of microstructure on charge transport mechanism has been investigated from impedance spectroscopy analysis. An equivalent circuit model has been proposed to explain the result.

Sorption of Different Dye Wastes By Poly(vinyl alcohol) /Poly (Carboxymethyl Cellulose) Blend Grafted Through A Radiation Method

International Nuclear Information System (INIS)

El-Salmawi Kariman, M.; Abu Zaid Magda, M.; Ibraheim Sayeda, M.; El-Naggar Abdel Wahab, M.; Zahran Abdel Hamid, H.

1999-01-01

The sorption of different dye wastes normaly released from industrial textile factories by a graft copolymer of poly(vinyl alcohol)/poly(carboxymethyl cellulose) blend with polystyrene has been investigated. The dye sorption was evaluated at different conditions. The amount of sorbed dye was determined by using a spectroscopic method. The blend graft copolymer showed a relatively high sorption for basic dye than other dyestuffs such as acid, reactive and direct. Moreover, it was found that the dye sorption did not depend on the weight of the blend graft copolymer or the volume of the waste solution. The treatment of the dye waste by using the prepared blend graft copolymer may be considered a practical one from the point of view of environmental methods

Alanine/epr pellet dosimeter using poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) copolymer as a binder for radiation dosimetry

International Nuclear Information System (INIS)

Beshir, W.B.; Ezz El-Din, H.M.; Abdel-fatth, A.A.; Ebraheem, S.

2005-01-01

A new alanine pellet dosimeter was developed for gamma and electron beam radiation dosimetry. Alanine powder was mixed with a new binding material, poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) copolymer. Pellets were prepared by pressing fine powder alanine with 60% copolymer binder by using hydraulic press and a specially designed pressing die. The radiation-formed stable free radicals were analysed by using electron paramagnetic resonance (EPR) spectroscopy. The useful dose range of these pellets was found to ranges from 1 to 80 kGy. The stability of the radiation- induced response was also studied

Quaternized poly(vinyl alcohol)/alumina composite polymer membranes for alkaline direct methanol fuel cells

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Chien, Wen-Chen; Chiu, Sheng-Shin

The quaternized poly(vinyl alcohol)/alumina (designated as QPVA/Al 2O 3) nanocomposite polymer membrane was prepared by a solution casting method. The characteristic properties of the QPVA/Al 2O 3 nanocomposite polymer membranes were investigated using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), micro-Raman spectroscopy, and AC impedance method. Alkaline direct methanol fuel cell (ADMFC) comprised of the QPVA/Al 2O 3 nanocomposite polymer membrane were assembled and examined. Experimental results indicate that the DMFC employing a cheap non-perfluorinated (QPVA/Al 2O 3) nanocomposite polymer membrane shows excellent electrochemical performances. The peak power densities of the DMFC with 4 M KOH + 1 M CH 3OH, 2 M CH 3OH, and 4 M CH 3OH solutions are 28.33, 32.40, and 36.15 mW cm -2, respectively, at room temperature and in ambient air. The QPVA/Al 2O 3 nanocomposite polymer membranes constitute a viable candidate for applications on alkaline DMFC.

Study on Chitosan-Polyvinyl Alcohol Inter polymeric ph-Responsive Hydrogels for Controlled Drug Delivery

International Nuclear Information System (INIS)

Abdel-Bary, E.M.; El-Sherbiny, I.M.; Abdelaal, M.Y.; Abdel-Razik, E.A.

2005-01-01

Two series of ph-responsive biodegradable interpenetrating polymeric (IPN) hydrogels composed of chitosan and poly(vinyl alcohol) (PVA) were prepared for controlled drug release investigations. The first series was chemically crosslinked with different concentrations of glutaraldehyde as a crosslinked and the second series was crosslinked by gamma-radiation. Degree of crosslinking has been controlled by the concentration of crosslinked as well as by gamma irradiation dose. The equilibrium swelling -reflecting the degree of crosslinks - were carried out for the gels at 37 degree C in buffer solutions of ph 2.1 and 7.4 (simulated gastric and intestinal fluids respectively). 5-fluorouracil (5- FU) was entrapped, as a model therapeutic agent, in the hydrogels and equilibrium-swelling studies were carried out for the drug-entrapped gels at 37 degree C. The in-vitro release profiles of the drug were established at 37 degree C in ph 2.1 and 7.4. FT-IR was employed to investigate the structural changes of the gels with different degrees of crosslinking

Tm-doped fiber laser mode-locking with MoS2-polyvinyl alcohol saturable absorber

Science.gov (United States)

Cao, Liming; Li, Xing; Zhang, Rui; Wu, Duanduan; Dai, Shixun; Peng, Jian; Weng, Jian; Nie, Qiuhua

2018-03-01

We have designed an all-fiber passive mode-locking thulium-doped fiber laser that uses molybdenum disulfide (MoS2) as a saturable absorber (SA) material. A free-standing few-layer MoS2-polyvinyl alcohol (PVA) film is fabricated by liquid phase exfoliation (LPE) and is then transferred onto the end face of a fiber connector. The excellent saturable absorption of the fabricated MoS2-based SA allows the laser to output soliton pulses at a pump power of 500 mW. Fundamental frequency mode-locking is realized at a repetition frequency of 13.9 MHz. The central wavelength is 1926 nm, the 3 dB spectral bandwidth is 2.86 nm and the pulse duration is 1.51 ps. Additionally, third-order harmonic mode-locking of the laser is also achieved. The pulse duration is 1.33 ps, which is slightly narrower than the fundamental frequency mode-locking bandwidth. The experimental results demonstrate that the few-layer MoS2-PVA SA is promising for use in 2 μm laser systems.

Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds

International Nuclear Information System (INIS)

Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B.; Srinivasan, A.

2016-01-01

Composite nanofibrous membranes based on sol-gel derived 45SiO 2 24.5CaO 24.5 Na 2 O 6 P 2 O 5 (bioglass, BG) and 43SiO 2 24.5CaO 24.5 Na 2 O 6 P 2 O 5 2Fe 2 O 3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application. - Highlights: • Electrospun low-cost PVA-45S5 bioglass (BG) nanofibrous membranes • PVA-BG membranes containing 2 wt.% Fe 2 O 3 exhibit spontaneous magnetization. • BG fillers strongly enhanced mechanical strength and bioresponse of membranes. • Membranes show promise for bone scaffold and hyperthermia applications.

A Review of Natural Fiber Reinforced Poly(Vinyl Alcohol Based Composites: Application and Opportunity

Directory of Open Access Journals (Sweden)

Boon Khoon Tan

2015-11-01

Full Text Available Natural fibers are fine examples of renewable resources that play an important role in the composites industry, which produces superior strength comparable to synthetic fibers. Poly(vinyl alcohol (PVA composites in particular have attracted enormous interest in view of their satisfactory performance, properties and biodegradability. Their performance in many applications such as consumer, biomedical, and agriculture is well defined and promising. This paper reviews the utilization of natural fibers from macro to nanoscale as reinforcement in PVA composites. An overview on the properties, processing methods, biodegradability, and applications of these composites is presented. The advantages arising from chemical and physical modifications of fibers or composites are discussed in terms of improved properties and performance. In addition, proper arrangement of nanocellulose in composites helps to prevent agglomeration and results in a better dispersion. The limitations and challenges of the composites and future works of these bio-composites are also discussed. This review concludes that PVA composites have potential for use in numerous applications. However, issues on technological feasibility, environmental effectiveness, and economic affordability should be considered.

Properties of poly(vinyl alcohol)–borax gel doped with neodymium ...

Indian Academy of Sciences (India)

visible region then leads to luminescent emission in the near infra-red region. The spectral qualities of the ... molecular hydrogen bonding between the hydroxyl groups on poly(vinyl ..... mately results in near IR emissions. The maximum of the.

Polyvinyl chloride resin

International Nuclear Information System (INIS)

Kim, Hong Jae

1976-06-01

This book contains polyvinyl chloride resin industry with present condition such as plastic industry and polyvinyl chloride in the world and Japan, manufacture of polyvinyl chloride resin ; suspension polymerization and solution polymerization, extruding, injection process, hollow molding vinyl record, vacuum forming, polymer powders process, vinyl chloride varnish, vinyl chloride latex, safety and construction on vinyl chloride. Each chapter has descriptions on of process and kinds of polyvinyl chloride resin.

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shengchang; Liu, Pengqing, E-mail: liupq@scu.edu.cn; Zhao, Xiangsen; Xu, Jianjun, E-mail: xujj@scu.edu.cn

2017-02-28

Highlights: • In-situ emulsion polymerization and alcoholysis reaction is a good method to prepare GO/PVA nanocomposites. • Surface chemical grafting modification of GO with PVA chains was also carried out during the in-situ emulsion polymerization and alcoholysis reaction. • The surface chemical grafting modification of GO by in-situ polymerization and alcoholysis reaction could not only improve the dispersion of fillers in matrix, but also the interfacial interactions between fillers and matrix. • The thermal and mechanical properties of PVA-g-GO/PVA nanocompistes were also studied. - Abstract: An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young’s modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler

Preparation of poly(vinyl alcohol)-grafted graphene oxide/poly(vinyl alcohol) nanocomposites via in-situ low-temperature emulsion polymerization and their thermal and mechanical characterization

International Nuclear Information System (INIS)

Zhang, Shengchang; Liu, Pengqing; Zhao, Xiangsen; Xu, Jianjun

2017-01-01

Highlights: • In-situ emulsion polymerization and alcoholysis reaction is a good method to prepare GO/PVA nanocomposites. • Surface chemical grafting modification of GO with PVA chains was also carried out during the in-situ emulsion polymerization and alcoholysis reaction. • The surface chemical grafting modification of GO by in-situ polymerization and alcoholysis reaction could not only improve the dispersion of fillers in matrix, but also the interfacial interactions between fillers and matrix. • The thermal and mechanical properties of PVA-g-GO/PVA nanocompistes were also studied. - Abstract: An in-situ polymerization combined with chemical grafting modification method for preparing Poly(vinyl alcohol)-grafted graphene oxide/Poly(vinyl alcohol) (PVA-g-GO/PVA) nanocomposites was reported. Firstly, Poly(vinyl acetate)-grafted graphene oxide/Poly(vinyl acetate) nanocomposites were prepared, and then the PVA-g-GO/PVA nanocomposites could be obtained through alcoholysis reaction. X-ray photoelectron spectrometer and fourier-transform infrared spectrometer confirmed that the PVAc or PVA chains were successfully grafted to GO sheets during in-situ polymerization and alcoholysis. And the results from transmission electron microscopy, scanning electron microscopy and X-ray diffraction showed that the well compatibility and homogenous dispersion of PVA-g-GO in PVA matrix could be achieved. Differential scanning calorimetric, thermogravimetry analysis and tensile test were employed to study the thermal and mechanical properties of the PVA-g-GO/PVA nanocomposites. The results indicated that a 53% improvement of tensile strength and a 36% improvement of Young’s modulus were achieved by addition of 0.5 wt% of GO sheets. And the glass transition temperature of PVA-g-GO/PVA nanocomposites was increased, and their thermal stability and crystallization degree were both decreased. Due to well dispersion of fillers and strong interfacial interactions at the filler

Combination of maghemite and titanium oxide nanoparticles in polyvinyl alcohol-alginate encapsulated beads for cadmium ions removal

Energy Technology Data Exchange (ETDEWEB)

Majidnia, Zohreh; Idris, Ani [Universiti Teknologi Malaysia, johor bahru (Malaysia)

2015-06-15

Both maghemite (γ-Fe{sub 2}O{sub 3}) and titanium oxide (TiO{sub 2}) nanoparticles were mixed at various ratios and embedded in polyvinyl alcohol (PVA)-alginate beads. These beads were tested for photocatalytic behavior in eliminating toxic Cd(Ⅱ) from the aqueous solution. The photocatalytic experiments were performed under sunlight irradiation at various pH, initial feed concentrations and γ-Fe{sub 2}O{sub 3}: TiO{sub 2} ratios. The recycling attribute of these beads was also investigated. The results revealed that 100% of the Cd(Ⅱ) was eliminated in 150 minutes at pH 7 under sunlight. It shows that maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the photocatalyst process and reused for at least six times without losing their initial properties.

Synthesis and characterization of particles derived of poly(vinyl alcohol) (PVA) for treatment of embolization and chemoembolization

International Nuclear Information System (INIS)

Semenzim, Vinicius L.; Basso, Glaucia G.; Passos, Rodrigo A.; Nery, Jose G.; Agreli, Guilherme; Oliveira, Ana P.M.L.; Kawasaki-Oyama, Rosa S.; Braile, Domingo M.

2009-01-01

The most effective way to treat cancerous tumors is by surgically removing them. However in some types of cancer, such as liver and uterine cancer, more than two-thirds of patients have no indication for surgery due to the size and location of the tumor, such as into the blood vessels. Doctors and researchers have invested in alternative and less invasive methods such as chemoembolization. The objectives of this research project are the synthesis and characterization of poly(vinyl alcohol) (PVA) particles for use in cancer treatment. PVA particles will be combined with chemotherapeutic agent Doxorubicin, drug commonly used in the treatment of cancers and carcinomas. The particles, obtained by controlled polymerization reaction followed by saponification, were characterized by SEM, XRD and NMR-CP/MAS. The functionalization of the particles with the drug is the next step of this study. (author)

Investigation on the thermal properties of new thermo-reversible networks based on poly(vinyl furfural and multifunctional maleimide compounds

Directory of Open Access Journals (Sweden)

C. Gaina

2012-02-01

Full Text Available New thermo-reversible networks were obtained from poly(vinyl furfural and multifunctional maleimide monomers by Diels-Alder (DA and retro-DA reactions. The poly(vinyl furfural having acetalization degree of 15 and 25% were obtained by the acid-catalyzed homogenous acetalization of poly(vinyl alcohol with 2-furfural in a nonaqueous media. The thermal and viscoelastic behaviour of the cross-linked materials have been studied via differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis. The networks exhibit considerable swelling in those organic solvents that dissolve both poly(vinyl furfural and bismaleimides; by heating in aprotic dipolar solvents at 150°C, they become soluble.

Preparation of donut-shaped starch microparticles by aqueous-alcoholic treatment.

Science.gov (United States)

Farrag, Yousof; Sabando, Constanza; Rodríguez-Llamazares, Saddys; Bouza, Rebeca; Rojas, Claudio; Barral, Luís

2018-04-25

A simple method for producing donut-shaped starch microparticles by adding ethanol to a heated aqueous slurry of corn starch is presented. The obtained microparticles were analysed by SEM, XRD and DSC. The average size of microparticles was 14.1 ± 0.3 μm with holes of an average size of 4.6 ± 0.2 μm. The crystalline arrangement of the microparticles was of a V-type single helix. The change in crystallinity from A-type of the starch granules to a more open structure, where water molecules could penetrate easier within the microparticles, substantially increased their solubility and swelling power. The microparticles exhibited a higher gelatinization temperature and a lower gelatinization enthalpy than did the starch granules. The donut-shaped microparticles were stable for more than 18 months and can be used as a carrier of an active compound or as a filler in bioplastics. Copyright © 2017 Elsevier Ltd. All rights reserved.

In-Vitro Release of Ketoprofen Behavior Loaded in Polyvinyl Alcohol / Acrylamide Hydrogels Prepared by Gamma Irradiation

International Nuclear Information System (INIS)

Mahmoud, Gh.A.; Hegazy, D.E.; Kamal, H.

2014-01-01

Hydrogels based on various ratios of polyvinyl alcohol (PVA) and acrylamide (AAm) were prepared by gamma radiation. The formed hydrogels were characterized by spectroscopic analysis (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and swelling studied. It was found that the thermal stability of the hydrogel decreases as the AAm content increases in the hydrogel. The higher the AAm content in the hydrogel, the lower the values of Tm and ΔH m . Ketoprofen was adopted as a model drug to study the adsorption and release behavior of (PVA/AAm) hydrogel. The drug adsorption was decreased by increasing AAm ratio in the hydrogel. From the in vitro drug release study in ph progressive media, the basic medium was showed comparatively the highest release and the (PVA/AAm) hydrogel of composition (70/30) was found to be the highest release one. The mechanism of Ketoprofen release from the (PVA/AAm) matrix was found to be non-Fickian mechanism for all investigated hydrogels at ph 7.

Bond Performance and Structural Characterization of Polysaccharide Wood Adhesive Made from Konjac Glucomannan/Chitosan/Polyvinyl Alcohol

Directory of Open Access Journals (Sweden)

Rong Gu

2016-08-01

Full Text Available The bond performance and bonding mechanism were evaluated for a Konjac glucomannan (KGM, Chitosan (CS, and polyvinyl alcohol (PVOH blended wood adhesive. An optimized experimental strategy was used to investigate the effects of the formula parameters of adhesives on the bonding strength of plywood using a Box-Behnken design and response surface methodology (RSM. The microstructure of the blended adhesives was analyzed by Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. An optimum bonding strength (3.42 ± 0.31 MPa was achieved with concentrations of KGM, CS, and 10% PVOH of 2.3%, 2.3%, and 5.0%, respectively. There was strong hydrogen bonding between the KGM, CS, and 10% PVOH adhesives and the interface. SEM observations indicated that the blended adhesive exhibited a net-like structure that increased the overall bonding strength. These results provided the scientific basis for the continual development of environmentally friendly wood adhesives and the improvement of processing conditions.

Molecular modeling studies of structural properties of polyvinyl alcohol: a comparative study using INTERFACE force field.

Science.gov (United States)

Radosinski, Lukasz; Labus, Karolina

2017-10-05

Polyvinyl alcohol (PVA) is a material with a variety of applications in separation, biotechnology, and biomedicine. Using combined Monte Carlo and molecular dynamics techniques, we present an extensive comparative study of second- and third-generation force fields Universal, COMPASS, COMPASS II, PCFF, and the newly developed INTERFACE, as applied to this system. In particular, we show that an INTERFACE force field provides a possibility of composing a reliable atomistic model to reproduce density change of PVA matrix in a narrow temperature range (298-348 K) and calculate a thermal expansion coefficient with reasonable accuracy. Thus, the INTERFACE force field may be used to predict mechanical properties of the PVA system, being a scaffold for hydrogels, with much greater accuracy than latter approaches. Graphical abstract Molecular Dynamics and Monte Carlo studies indicate that it is possible to predict properties of the PVA in narrow temperature range by using the INTERFACE force field.

Mucoadhesive polymers: Synthesis and in vitro characterization of thiolated poly(vinyl alcohol).

Science.gov (United States)

Suchaoin, Wongsakorn; Pereira de Sousa, Irene; Netsomboon, Kesinee; Rohrer, Julia; Hoffmann Abad, Patricia; Laffleur, Flavia; Matuszczak, Barbara; Bernkop-Schnürch, Andreas

2016-04-30

The aim of this study was to synthesize thiolated poly(vinyl alcohol) (PVA) and to evaluate its mucoadhesive properties. Thiourea and 3-mercaptopropionic acid were utilized in order to obtain thiolated PVAs, namely, TPVA1 and TPVA2, respectively. TPVA1 and TPVA2 displayed 130.44 ± 14.99 and 958.35 ± 155.27 μmol immobilized thiol groups per gram polymer, respectively, which were then evaluated regarding reactivity of thiol groups, swelling behavior and mucoadhesive properties. Both thiolated PVAs exhibited the highest reactivity at pH 8.0 whereas more than 95% of free thiol groups were preserved at pH 5.0. Thiolation of PVA decelerated water uptake and prolonged disintegration time of test discs compared to unmodified PVA. Contact time of TPVA1- and TPVA2-based test discs on porcine intestinal mucosa was 3.2- and 15.8-fold prolonged, respectively, in comparison to non-thiolated PVA as measured by rotating cylinder method. According to tensile studies on mucosa, the total work of adhesion (TWA) and the maximum detachment force (MDF) were increased when compared to PVA. Furthermore, thiolated PVAs preserved higher percentage of viable cells compared to unmodified PVA within 24h as evaluated by MTT assay. Accordingly, thiolated PVA represents a novel excipient that can likely improve the mucoadhesive properties of various pharmaceutical formulations. Copyright © 2016 Elsevier B.V. All rights reserved.

Conductive, tough, hydrophilic poly(vinyl alcohol)/graphene hybrid fibers for wearable supercapacitors

Science.gov (United States)

Chen, Shaohua; Ma, Wujun; Xiang, Hengxue; Cheng, Yanhua; Yang, Shengyuan; Weng, Wei; Zhu, Meifang

2016-07-01

Graphene fibers based flexible supercapacitors have great potential as wearable power sources for textile electronics. However, their electrochemical performance is limited by the serious stacking of graphene sheets and their hydrophobicity in aqueous electrolytes. Meanwhile, their brittleness is unfavorable for practical application. Incorporation of nanofillers into graphene fibers has been proved effective for enhancing their capacitance, whereas often leading to deteriorated mechanical strength. Herein we demonstrate that the strength, toughness and capacitive performance of graphene-based fibers can be significantly enhanced simultaneously, simply by incorporating hydrophilic poly(vinyl alcohol) (PVA) into a non-liquid-crystalline graphene oxide (GO) dispersion before wet spinning and chemical reduction. The structure and properties of the resulted PVA/graphene hybrid fibers are systematically investigated, and the mechanism behind these enhancements is discussed in detail. The hybrid fiber with a PVA/GO weight ratio of 10/90 possesses a strength of 186 MPa, a toughness of 11.3 J cm-3, and a capacitance of 241 F cm-3 in 1 M H2SO4. A solid-state yarn supercapacitor assembled from these fibers exhibits a device energy of 5.97 mW h cm-3, and features excellent flexibility and bending stability. This device is robust enough to be integrated into textile and thus promising as wearable power supply for smart textiles.

Plasmon-enhanced luminescence of Sm complex using silver nanoparticles in Polyvinyl Alcohol

Energy Technology Data Exchange (ETDEWEB)

Kaur, Gagandeep; Verma, R.K.; Rai, D.K. [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, India 221005 (India); Rai, S.B., E-mail: sbrai49@yahoo.co.in [Laser and Spectroscopy Laboratory, Department of Physics, Banaras Hindu University, India 221005 (India)

2012-07-15

Silver (Ag) nanoparticles (NPs) were prepared by laser ablation in water with an aim to enhance the luminescence of rare earth coordinated complex in polymer host. A fixed concentration of the complex containing Samarium (Sm), Salicylic acid (Sal) and 1, 10-phenanthroline (Phen) were combined with different concentrations of silver NPs in PolyVinyl Alcohol at room temperature. Absorption spectrum and XRD patterns of the sample show that the Sm(Sal){sub 3}Phen complex is accompanied by Ag NPs. The luminescence from the complex was recorded in the presence and absence of Ag NPs using two different excitation wavelengths viz. 400 and 355 nm. Of these, 400 nm radiation falls in the surface plasmon resonance of Ag NPs. It was found that the Ag NPs led to a significant enhancement in luminescence of the complex. Surprisingly, a high concentration of Ag NPs tends to quench the luminescence. - Highlights: Black-Right-Pointing-Pointer Sm complex with Ag nanoparticles in PVA was prepared at room temperature. Black-Right-Pointing-Pointer UV-vis absorption and XRD confirms the presence of Sm complex and Ag NPs. Black-Right-Pointing-Pointer Enhancement in luminescence of complex was observed with Ag NPs. Black-Right-Pointing-Pointer Coupling between radiative transitions of Sm and SPR of NPs enhances the emission. Black-Right-Pointing-Pointer The higher concentration of Ag NPs quenches the luminescence of the complex.

Highly Zeolite-Loaded Polyvinyl Alcohol Composite Membranes for Alkaline Fuel-Cell Electrolytes

Directory of Open Access Journals (Sweden)

Po-Ya Hsu

2018-01-01

Full Text Available Having a secure and stable energy supply is a top priority for the global community. Fuel-cell technology is recognized as a promising electrical energy generation system for the twenty-first century. Polyvinyl alcohol/zeolitic imidazolate framework-8 (PVA/ZIF-8 composite membranes were successfully prepared in this work from direct ZIF-8 suspension solution (0–45.4 wt % and PVA mixing to prevent filler aggregation for direct methanol alkaline fuel cells (DMAFCs. The ZIF-8 fillers were chosen for the appropriate cavity size as a screening aid to allow water and suppress methanol transport. Increased ionic conductivities and suppressed methanol permeabilities were achieved for the PVA/40.5% ZIF-8 composites, compared to other samples. A high power density of 173.2 mW cm−2 was achieved using a KOH-doped PVA/40.5% ZIF-8 membrane in a DMAFC at 60 °C with 1–2 mg cm−2 catalyst loads. As the filler content was raised beyond 45.4 wt %, adverse effects resulted and the DMAFC performance (144.9 mW cm−2 was not improved further. Therefore, the optimal ZIF-8 content was approximately 40.5 wt % in the polymeric matrix. The specific power output was higher (58 mW mg−1 than most membranes reported in the literature (3–18 mW mg−1.

Preparation and characterization of poly(vinyl alcohol) hydrogel contain metronidazole by irradiation

Energy Technology Data Exchange (ETDEWEB)

Baik, Jae; Park, Jong Seok; Jeong, Jin Oh; Jeong, Sung In; Gwon, Hui Jeong; Ahn, Sung Jun; Lim, Youn Mook [Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2016-11-15

Periodontitis is disease of damaged gum tissue that is not removed the plaque onto teeth. In case that the symptoms of disease get pain worse, it will have to extract tooth because of tumefy or bleeding at gums so treatment of drug was required to periodontitis. In this study, the hydrogel was prepared by including superior viscous, excellent elastic, and biocompatibility of Poly(vinyl alcohol, PVA) and antimicrobial drug of Metronidazole (MD). The 15 wt% PVA was dissolved in deionized water and then prepared PVA solution was irradiated using gamma-ray at 25 kGy (10 kGy hr{sup -1}). In addition, PVA hydrogel was immersed in each 0.1, 0.25 and 0.5 wt% MD solution using stirrer for 24 hr. The result of the gelation, 0.5 wt% MD loaded PVA hydrogel (76%) was lower than PVA hydrogel (88.2%). The swelling ration of 0.5 wt% MD loaded PVA hydrogel (294.8%) was higher than PVA hydrogel (105.2%). The compressive strength and thermal properties of MD loaded PVA hydrogel was gradually lower. The drug release test of 0.5 wt% MD loaded PVA hydrogel (61%) was higher than 0.1 wt% MD loaded PVA hydrogel (12%). Therefore, MD loaded PVA hygrogel may be a promising tool for periodontitis medicine by gamma-ray.

Preparation and characterization of poly(vinyl alcohol) hydrogel contain metronidazole by irradiation

International Nuclear Information System (INIS)

Baik, Jae; Park, Jong Seok; Jeong, Jin Oh; Jeong, Sung In; Gwon, Hui Jeong; Ahn, Sung Jun; Lim, Youn Mook

2016-01-01

Periodontitis is disease of damaged gum tissue that is not removed the plaque onto teeth. In case that the symptoms of disease get pain worse, it will have to extract tooth because of tumefy or bleeding at gums so treatment of drug was required to periodontitis. In this study, the hydrogel was prepared by including superior viscous, excellent elastic, and biocompatibility of Poly(vinyl alcohol, PVA) and antimicrobial drug of Metronidazole (MD). The 15 wt% PVA was dissolved in deionized water and then prepared PVA solution was irradiated using gamma-ray at 25 kGy (10 kGy hr"-"1). In addition, PVA hydrogel was immersed in each 0.1, 0.25 and 0.5 wt% MD solution using stirrer for 24 hr. The result of the gelation, 0.5 wt% MD loaded PVA hydrogel (76%) was lower than PVA hydrogel (88.2%). The swelling ration of 0.5 wt% MD loaded PVA hydrogel (294.8%) was higher than PVA hydrogel (105.2%). The compressive strength and thermal properties of MD loaded PVA hydrogel was gradually lower. The drug release test of 0.5 wt% MD loaded PVA hydrogel (61%) was higher than 0.1 wt% MD loaded PVA hydrogel (12%). Therefore, MD loaded PVA hygrogel may be a promising tool for periodontitis medicine by gamma-ray

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

In the present study starch has been blended with poly(vinyl alcohol) to design macroporous architectures following a repeated freeze-thaw method. These macroporous cryogels were loaded with an antibiotic drug, ciprofloxacin hydrochloride (Cfx), and evaluated for its in vitro delivery in a completely controlled manner ...

Short Oligonucleotides Aligned in Stretched Humid Matrix: Secondary DNA Structure in Poly(vinyl alcohol) Environment

KAUST Repository

Hanczyc, Piotr

2012-04-24

We report that short, synthetic, double- as well as single-stranded DNA can be aligned in stretched humid poly(vinyl alcohol) (PVA) matrix, and the secondary structure (nucleobase orientation) can be characterized with linear dichroism (LD) spectroscopy. Oligonucleotides of lengths varying between 10 (3.4 nm) and 60 bases (20.4 nm) were investigated with respect to structural properties in the gel-like polymer environment. The DNA conformation as a function of relative humidity reveals a strong dependence of helical structure of DNA on PVA hydration level, results of relevance for nanotechnical studies of DNA-based supramolecular systems. Also, the PVA gel could provide possibilities to test models for nucleic acid interactions and distribution in cell contexts, including structural stability of genetic material in the cell and PVA-packaging for gene delivery. A method by which duplex oligonucleotides, with sequences designed to provide specific binding sites, become amenable to polarized-light spectroscopy opens up new possibilities for studying structure in DNA complexes with small adduct molecules as well as proteins. © 2012 American Chemical Society.

Flame-retardant polyvinyl alcohol membrane with high transparency based on a reactive phosphorus-containing compound

Science.gov (United States)

Peng, Sha; Zhou, Ming; Liu, Feiyan; Zhang, Chang; Liu, Xueqing; Liu, Jiyan; Zou, Liyong; Chen, Jia

2017-08-01

Flame-retardant polyvinyl alcohol (PVA) membranes with high transparency and flexibility were prepared by mixing an aqueous solution of a phosphorus-containing acrylic acid (AOPA) with PVA. The reaction between AOPA and PVA, the transparency, the crystallinity and the flexibility of the membrane were investigated with Fourier transform infrared spectrometry (FTIR), UV-vis light transmittance, X-ray diffraction and tensile tests, respectively. The limited oxygen index (LOI) and vertical flame (UL 94 VTM), microscale combustion calorimetry, thermogravimetric analysis (TGA) and TGA-FTIR were employed to evaluate the flame retardancy as well as to reveal the corresponding mechanisms. Results showed that PVA containing 30 wt% of AOPA can reach the UL 94 VTM V0 rating with an LOI of 27.3% and retain 95% of the original transparency of pure PVA. Adding AOPA reduces crystallinity of PVA, while the flexibility is increased. AOPA depresses the thermal degradation of PVA and promotes char formation during combustion. The proposed decomposition mechanism indicates that AOPA acts mainly in the condensed phase.

Evaluation of polyvinyl alcohols as mucoadhesive polymers for mucoadhesive buccal tablets prepared by direct compression.

Science.gov (United States)

Ikeuchi-Takahashi, Yuri; Ishihara, Chizuko; Onishi, Hiraku

2017-09-01

The purpose of the present work was to evaluate polyvinyl alcohols (PVAs) as a mucoadhesive polymer for mucoadhesive buccal tablets prepared by direct compression. Various polymerization degree and particle diameter PVAs were investigated for their usability. The tensile strength, in vitro adhesive force, and water absorption properties of the tablets were determined to compare the various PVAs. The highest values of the tensile strength and the in vitro adhesive force were observed for PVAs with a medium viscosity and small particle size. The optimal PVA was identified by a factorial design analysis. Mucoadhesive tablets containing the optimal PVA were compared with carboxyvinyl polymer and hydroxypropyl cellulose formulations. The optimal PVA gives a high adhesive force, has a low viscosity, and resulted in relatively rapid drug release. Formulations containing carboxyvinyl polymer had high tensile strengths but short disintegration times. Higher hydroxypropyl cellulose concentration formulations had good adhesion forces and very long disintegration times. We identified the optimal characteristics of PVA, and the usefulness of mucoadhesive buccal tablets containing this PVA was suggested from their formulation properties.

Fabrication and mechanical characterization of a polyvinyl alcohol sponge for tissue engineering applications.

Science.gov (United States)

Karimi, A; Navidbakhsh, M; Faghihi, S

2014-05-01

Polyvinyl alcohol (PVA) sponges are widely used for clinical applications, including ophthalmic surgical treatments, wound healing and tissue engineering. There is, however, a lack of sufficient data on the mechanical properties of PVA sponges. In this study, a biomechanical method is used to characterize the elastic modulus, maximum stress and strain as well as the swelling ratio of a fabricated PVA sponge (P-sponge) and it is compared with two commercially available PVA sponges (CENEFOM and EYETEC). The results indicate that the elastic modulus of the P-sponge is 5.32% and 13.45% lower than that of the CENEFOM and EYETEC sponges, while it bears 4.11% more and 10.37% less stress compared to the CENEFOM and EYETEC sponges, respectively. The P-sponge shows a maximum strain of 32% more than the EYETEC sponge as well as a 26.78% higher swelling ratio, which is a significantly higher absorbency compared to the CENEFOM. It is believed that the results of this study would help for a better understanding of the extension, rupture and swelling mechanism of PVA sponges, which could lead to crucial improvement in the design and application of PVA-based materials in ophthalmic and plastic surgeries as well as wound healing and tissue engineering.

Influence of Uranium and Polivinyl Alcohol Concentration in the Feed of Sol Gel Process on the Gel Spherical Product

International Nuclear Information System (INIS)

Indra Suryawan; Endang Susiantini

2007-01-01

The gel particles have been made at various uranium and polyvinyl alcohol concentration in the sol gel process. The variables of uranium concentration were 0.3; 0.5; 0.7; 0.9; 1.1; 1.3; 1.5; 1.7; 1.9 and 2.1 M The variables of polyvinyl alcohol concentration were 0.3; 0.6; 0.9; 1.2; 1.5; 1.8; 2.1 and 2.4 M After drying the sol gel process products were heated at 300, 500 and 750°C during 4 hours. The gel particles were characterized using an optic microscope to know the shape and condition morphology of gel. From experimental result using uranium concentration of 0.3 until 2.1 M and polyvinyl alcohol of 1.8 until 2.4 M spherical and gel was formed elastic, after heating at 750°C it was unbreakable. At the concentration of polyvinyl alcohol from 0.3 to 0.5 M, the gel product was soft and broken after being dried. At the concentration of polyvinyl alcohol from 0.6 to 0.8 M, the dried gel product was not perfect. At the concentration of polyvinyl alcohol from 0.9 to 1.7 M, the gel product of gelation process was spherical and it was broken after being heated up to 300°C. (author)

Biodegradable Composites Based on Starch/EVOH/Glycerol Blends and Coconut Fibers

Science.gov (United States)

Unripe coconut fibers were used as fillers in a biodegradable polymer matrix of starch/Ethylene vinyl alcohol (EVOH)/glycerol. The effects of fiber content on the mechanical, thermal and structural properties were evaluated. The addition of coconut fiber into starch/EVOH/glycerol blends reduced the ...

Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

International Nuclear Information System (INIS)

Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeda, T.

2005-01-01

We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does include only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed

Poly(vinyl alcohol)-Tannic Acid Hydrogels with Excellent Mechanical Properties and Shape Memory Behaviors.

Science.gov (United States)

Chen, Ya-Nan; Peng, Lufang; Liu, Tianqi; Wang, Yaxin; Shi, Shengjie; Wang, Huiliang

2016-10-12

Shape memory hydrogels have promising applications in a wide variety of fields. Here we report the facile fabrication of a novel type of shape memory hydrogels physically cross-linked with both stronger and weaker hydrogen bonding (H-bonding). Strong multiple H-bonding formed between poly(vinyl alcohol) (PVA) and tannic acid (TA) leads to their coagulation when they are physically mixed at an elevated temperature and easy gelation at room temperature. The amorphous structure and strong H-bonding endow the PVA-TA hydrogels with excellent mechanical properties, as indicated by their high tensile strengths (up to 2.88 MPa) and high elongations (up to 1100%). The stronger H-bonding between PVA and TA functions as the "permanent" cross-link and the weaker H-bonding between PVA chains as the "temporary" cross-link. The reversible breakage and formation of the weaker H-bonding imparts the PVA-TA hydrogels with excellent temperature-responsive shape memory. Wet and dried hydrogel samples with a deformed or elongated shape can recover to their original shapes when immersed in 60 °C water in a few seconds or at 125 °C in about 2.5 min, respectively.

Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds

Energy Technology Data Exchange (ETDEWEB)

Shankhwar, Nisha [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Kumar, Manishekhar; Mandal, Biman B. [Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Srinivasan, A., E-mail: asrini@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

2016-12-01

Composite nanofibrous membranes based on sol-gel derived 45SiO{sub 2} 24.5CaO 24.5 Na{sub 2}O 6 P{sub 2}O{sub 5} (bioglass, BG) and 43SiO{sub 2} 24.5CaO 24.5 Na{sub 2}O 6 P{sub 2}O{sub 5} 2Fe{sub 2}O{sub 3} (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application. - Highlights: • Electrospun low-cost PVA-45S5 bioglass (BG) nanofibrous membranes • PVA-BG membranes containing 2 wt.% Fe{sub 2}O{sub 3} exhibit spontaneous magnetization. • BG fillers strongly enhanced mechanical strength and bioresponse of membranes. • Membranes show promise for bone scaffold and hyperthermia applications.

Borax mediated layer-by-layer self-assembly of neutral poly(vinyl alcohol) and chitosan.

Science.gov (United States)

Manna, Uttam; Patil, Satish

2009-07-09

We report a multilayer film of poly(vinyl alcohol) (PVA)-borate complex and chitosan by using a layer-by-layer approach. PVA is an uncharged polymer, but hydroxyl functional groups of PVA can be cross-linked by using borax as a cross-linking agent. As a result electrostatic charges and intra- and interchain cross-links are introduced in the PVA chain and provide physically cross-linked networks. The PVA-borate was then deposited on a flat substrate as well as on colloidal particles with chitosan as an oppositely charged polyelectrolyte. Quartz crystal microbalance, scanning electron microscopy, and atomic force microscopy were used to follow the growth of thin film on flat substrate. Analogous experiments were performed on melamine formaldehyde colloidal particles (3-3.5 microm) to quantify the process for the preparation of hollow microcapsules. Removal of the core in 0.1 N HCl results in hollow microcapsules. Characterization of microcapsules by transmission electron microscopy revealed formation of stable microcapsules. Further, self-assembly of PVA-borate/chitosan was loaded with the anticancer drug doxorubicin, and release rates were determined at different pH values to highlight the drug delivery potential of this system.

Analytical studies into radiation-induced starch damage in black and white peppers

International Nuclear Information System (INIS)

Farkas, J.; Sharif, M.M.; Barabassy, S.

1990-01-01

In order to develop detection methods of radiation treatment, ground black pepper samples equilibrated to water activity levels of 0.25, 0.50 and 0.75 a w , respectively, were irradiated with gamma radiation doses of 0, 4, 8, 16 or 32 kGy, and their damaged starch content, reduced sugar content and alcohol induced turbidity of their aqueous extracts were investigated. The colorimetric method and the alcohol-induced turbidity showed statistically significant increase of starch damage at 4 kGy or higher dose levels. However, all investigated analytical indices of starch radio-depolymerization were changed less dramatically by irradiation than the apparent viscosity of the gelatinized suspensions of spices reported previously. (author) 15 refs.; 4 tabs

Synthesis of MoO3 and its polyvinyl alcohol nanostructured film

Indian Academy of Sciences (India)

Unknown

†Appa Institute of Engineering and Technology, Gulbarga 585 101, India. MS received 9 December ... The solvent casting method is adopted for the synthesis of MoO3 dispersed polyvinyl ... one dimension, are dispersed in an organic polymer matrix in order to .... applied for the synthesis of other layered ceramic materi- als.

Influence of Compounding Methods on Poly(vinyl) Alcohol/ Sago Pith Waste Bio composites: Mechanical and Water Absorption Properties

International Nuclear Information System (INIS)

Toh, W.Y.; Lai, J.C.; Aizan, W.A.R.W.

2011-01-01

Several methods of incorporating sago pith waste (SPW) into poly(vinyl alcohol) (PVA) had been conducted: (i) dry blending (PVA/SPW/G), (ii) blending of SPW and pre-plasticised PVA (pPVA/SPW/G) and (iii) blending of pre-plasticised of both PVA and SPW (pPVA/pSPW). The effect of the compounding method on the mechanical and water absorption properties were investigated. The addition of SPW into PVA greatly reduced the tensile strength and elongation at break. The tensile strength and elongation at break of PVA/SPW composites with identical geometry during compounding stage (powder/powder and pellet/pellet), which were PVA/SPW/G and pPVA/pSPW yielded the highest value. The percentage of water absorbed by PVA/SPW/G (without pre-plasticization) was the highest, followed by pPVA/pSPW and pPVA/SPW/G. (author)

Relative humidity sensor based on surface plasmon resonance of D-shaped fiber with polyvinyl alcohol embedding Au grating

Science.gov (United States)

Yan, Haitao; Han, Daofu; Li, Ming; Lin, Bo

2017-01-01

This paper presents the design, fabrication, and characterization of a D-shaped fiber coated with polyvinyl alcohol (PVA) embedding an Au grating-based relative humidity (RH) sensor. The Au grating is fabricated on a D-shaped fiber to match the wave-vector and excite the surface plasmon, and the PVA is embedded in the Au grating as a sensitive cladding film. The refractive index of PVA changes with the ambient humidity. Measurements in a controlled environment show that the RH sensor can achieve a sensitivity of 5.4 nm per relative humidity unit in the RH range from 0% to 70% RH. Moreover, the surface plasmon resonance can be realized and used for RH sensing at the C band of optical fiber communication instead of the visible light band due to the metallic grating microstructure on the D-shaped fiber.

Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite

Science.gov (United States)

Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

2014-01-01

Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments. PMID:25482413

Poly(vinyl alcohol)-based film potentially suitable for antimicrobial packaging applications.

Science.gov (United States)

Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia

2014-04-01

This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 μm in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances. © 2014 Institute of Food Technologists®

Radiation sensitive indicator based on tetrabromophenol blue dyed poly(vinyl alcohol)

International Nuclear Information System (INIS)

Beshir, W.B.

2013-01-01

Radiation sensitive indicators based on dyed polyvinyl alcohol (PVA) containing acid- sensitive dye (tetrabromophenol blue, TBPB) and chloral hydrate (CCl 3 ·CH·(OH) 2 , 2,2,2-trichloroethane-1,1-diol) have been developed. These plastic film dosimeters undergo color change from blue (the alkaline form of TBPB) to yellow (the acidic form of TBPB), indicating acid formation. The concentration of radiation formed acids in the films containing different concentrations of chloral hydrate was calculated at different doses. These films can be used as dosimeters for food irradiation applications where the maximum of the useful dose ranges are between 1 and 8 kGy depending on chloral hydrate concentration in the film. The films have the advantage of negligible humidity effects on response in the intermediate range of relative humidity from 0 to 70% as good post irradiation stability when stored in the dark at room temperature. The overall combined uncertainty (at 2σ) associated with measurement of response (ΔA mm −1 ) at 623 nm for dose range 1–8 kGy is 4.53%. - Highlights: ► On irradiating TBPB/PVA films the color change from blue to green and yellow. ► The amount of acid formed depends on dose and concentration of chloral hydrate. ► The dose range 1–8 kGy the film can be used for food irradiation applications. ► The response of these films has negligible humidity effects from 0 to 70%. ► The combined uncertainty at 2σ using TBPB/PVA films was found to be 4.53%

Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

Science.gov (United States)

Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

2014-01-01

Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments.

Elastic properties of thin poly(vinyl alcohol)–cellulose nanocrystal membranes

International Nuclear Information System (INIS)

Pakzad, A; Yassar, R S; Simonsen, J

2012-01-01

In spite of extensive studies on the preparation and characterization of nanocomposite materials, the correlation of their properties at the nanoscale with those in bulk is a relatively unexplored area. This is of great importance, especially for materials with potential biomedical applications, where surface properties are as important in determining their applicability as bulk characteristics. In this study, the nanomechanical characteristics of thin poly(vinyl alcohol) (PVOH)–poly(acrylic acid) (PAA)–cellulose nanocrystal (CNC) membranes were studied using the nanoindentation module in an atomic force microscope (AFM) and the properties were compared with the macro-scale properties obtained by tensile tests. In general, the elastic properties measured by nanoindentation followed the same trend as macro-scale tensile tests except for the PVOH 85-PAA 0-CNC 15 sample. In comparison to the macro-scale elastic properties, the measured elastic moduli with AFM were higher. Macro-scale tensile test results indicated that, in the presence of PAA, incorporation of CNCs up to 20 wt% improved the elastic modulus of PVOH, but when no PAA was added, increasing the CNC content above 10 wt% resulted in their agglomeration and degradation in mechanical properties of PVOH. The discrepancy between macro-scale tensile tests and nanoindentation in the PVOH 85-PAA 0-CNC 15 sample was correlated to the high degree of inhomogeneity of CNC dispersion in the matrix. It was found that the composites reinforced with cellulose nanocrystals had smaller indentation imprints and the pile-up effect increased with the increase of cellulose nanocrystal content. (paper)

The effect of the silver nanoparticles on the dynamics of singlet-singlet energy transfer of luminophores in thin films of polyvinyl alcohol

International Nuclear Information System (INIS)

Bryukhanov, V.V.; Samusev, I.G.; Slezhkin, V.A.; Tsibul'nikova, A.V.

2014-01-01

The effect of ablated silver nanoparticles (ANP) on the dynamics of non-radiative inductance-resonance energy transfer and phosphorescence in the donor-acceptor pair of molecules of eosin and methylene blue (MB) luminophores embedded in thin films of polyvinyl alcohol have been investigated. Increased fluorescence intensity of donor (eosin) and acceptor (MB) molecules, as well as a growth of the dipole-dipole transfer efficiency have been obtained under the resonant excitation of the silver ANP surface plasmons in the absorption band of the donor energy. The luminescence quantum yields and the fluorescence lifetimes have been measured. The energy transfer constants, degree of polarization and fluorescence anisotropy have been determined. (authors)

Preparation of Polyvinyl Pyrrolidone-Based Hydrogels by Radiation Induced Crosslinking with Potential Application as Wound Dressing

International Nuclear Information System (INIS)

Abd EI-Mohdy, H.L.; Hegazy, E.A.

2009-01-01

Polyvinyl pyrrolidone l polyethylene glycol hydrogels (PVP/ PEG) and PVP/ PEG/ Starch were prepared by irradiating the mixtures of aqueous solutions of PVP, PEG and starch with electron beam at different doses. Its properties were evaluated to identify their usability in wound dressing applications. Hydrogel dressing can protect injured skin and keep it appropriately moist to speed the healing process. The physical properties of the prepared hydrogels, such as gel content, swelling, water content and degree of water evaporation with varying composition and irradiation dose were examined to evaluate the usefulness of the hydrogels for wound dressing. The gel content increases with increasing PVP concentration due to increased crosslink density, and decreases with increasing the PEG concentration. PEG seems to act not only as plasticizer but also to modify the gel properties as gelation% and maximum swelling. Mechanical experiments were conducted for both of PVP/PEG and PVP/PEG/ Starch. The adding of PEG and starch to PVP significantly improve elongation and tensile strength of prepared hydrogels. The crystallinity of prepared hydrogels was investigated with varying their components. XRD studies indicated that the crystallinity in the gel was mainly due to PVP and decreased with enhanced starch content. The prepared hydrogels had sufficient strength to be used as wound dressing and could be considered as a good barrier against microbes

Effect of polyvinyl alcohol (PVA) on Ag-Cu nanopaste performance

Science.gov (United States)

Noordin, Norasiah Mohammad; Razak, Khairunisak Abd; Cheong, Kuan Yew

2017-07-01

Electronic devices used for extreme high temperature continue to be in demand, for instance in aviation, aerospace and automotive industry. The reliability of these devices strongly depends on electronic packaging. Die attach materials is vital in electronic packaging as it provides an interface in between a die and a substrate, and its quality will determine the performance of the devices. Nanopaste is one of categories classified in the die attach systems. It is a mixture of nano sized metal particles and organic additives (binder, surfactant, solvent). In this study, Ag and Cu nanoparticles was mixed into an organic binder system, polyvinyl alcohol (PVA) serves as binder and ethylene glycol functions as surfactant while deionized water used to dissolve PVA. The mixture was inserted in vacuum oven at 70°C and then proceeds for sintering in horizontal tube furnace with various sintering temperature, a dwell time of 30 min and ramp rate of 5°C/min. The samples were then characterized using field emission scanning electron microscope (FE-SEM) to examine the morphology, X-ray diffraction (XRD) for phase identification, Four Point Probe to measure sheet resistance, and thermogravimetric and differential scanning calorimetry analysis (TGA/DSC) to study the thermal response with respect to temperature. These parameter were studied, the effect of PVA amount (0.10, 0.15, 0.20, 0.30, 0.40, 0.50 g) in Ag-Cu nanopaste formulation was visual inspected, the variation of drying time (20, 30, 40, 60, 80, 100, 120 min) in vacuum oven and sintering temperature (280, 300, 320, 340, 360, 380, 400°C) was recorded. The optimum condition for producing Ag-Cu nanopaste is by using 0.15 g of PVA in the Ag-Cu formulation, 30 min drying time and 340°C sintering temperature.

Macroporous poly(vinyl alcohol) microspheres bearing phosphate groups as a new adsorbent for low-density lipoprotein apheresis

Energy Technology Data Exchange (ETDEWEB)

Wang Weichao; Xie Hui; Ou Lailiang; Wang Lianyong; Yu Yaoting; Kong Deling [Key Laboratory of Bioactive Materials, Ministry of Education, College of Life Science, Nankai University, Tianjin 300071 (China); Sun Lisha, E-mail: wly@nankai.edu.c, E-mail: kongdeling@nankai.edu.c [General Hospital, Tianjin Medical University, Tianjin 300052 (China)

2009-12-15

A new low-density lipoprotein (LDL) adsorbent with phosphate groups as the ligand was prepared in this study. Macroporous poly(vinyl acetate-co-triallyl isocyanurate) microspheres were prepared using a free-radical suspension polymerization method. A hydrolysis reaction in sodium hydroxide/methanol changed the materials into poly(vinyl alcohol) (PVA) microspheres. Further reaction with phosphorus oxychloride in anhydrous DMF led to the LDL adsorbent PVA-phosphate microspheres. The preparation conditions such as reaction time, temperature and the amount of phosphorus oxychloride were optimized. The adsorption of plasma lipoproteins was examined by in vitro adsorption assays. The influence of adsorption time, plasma volume and ionic strength on the adsorption capacity was investigated. The circulation adsorption showed that the pathogenic lipoproteins in the plasma such as total cholesterol (TC), LDL and triglyceride (TG) could be removed markedly, in which the removal percentages were 42.9%, 45.0% and 44.74%, respectively. However, the reduction of high-density lipoprotein (HDL) and other normal plasma components was very slight. For in vivo experiment, rabbits were fed with high-cholesterol food to develop a hyperlipidemia model and treated by extracorporeal blood perfusion using the PVA-phosphate columns. Eight hyperlipidemia rabbits were treated with the PVA-phosphate adsorbent, and the removal of TC, LDL and TG was 45.03 +- 6.64%, 48.97 +- 9.92% and 35.42 +- 14.17%, respectively. The sterilization and storage tests showed that the adsorbent was chemically and functionally stable. It could be easily sterilized by a common method and stored for months without loss of adsorption capacity. Therefore, this new PVA-phosphate-based LDL adsorbent may have potential for application in LDL apheresis.

Macroporous poly(vinyl alcohol) microspheres bearing phosphate groups as a new adsorbent for low-density lipoprotein apheresis

International Nuclear Information System (INIS)

Wang Weichao; Xie Hui; Ou Lailiang; Wang Lianyong; Yu Yaoting; Kong Deling; Sun Lisha

2009-01-01

A new low-density lipoprotein (LDL) adsorbent with phosphate groups as the ligand was prepared in this study. Macroporous poly(vinyl acetate-co-triallyl isocyanurate) microspheres were prepared using a free-radical suspension polymerization method. A hydrolysis reaction in sodium hydroxide/methanol changed the materials into poly(vinyl alcohol) (PVA) microspheres. Further reaction with phosphorus oxychloride in anhydrous DMF led to the LDL adsorbent PVA-phosphate microspheres. The preparation conditions such as reaction time, temperature and the amount of phosphorus oxychloride were optimized. The adsorption of plasma lipoproteins was examined by in vitro adsorption assays. The influence of adsorption time, plasma volume and ionic strength on the adsorption capacity was investigated. The circulation adsorption showed that the pathogenic lipoproteins in the plasma such as total cholesterol (TC), LDL and triglyceride (TG) could be removed markedly, in which the removal percentages were 42.9%, 45.0% and 44.74%, respectively. However, the reduction of high-density lipoprotein (HDL) and other normal plasma components was very slight. For in vivo experiment, rabbits were fed with high-cholesterol food to develop a hyperlipidemia model and treated by extracorporeal blood perfusion using the PVA-phosphate columns. Eight hyperlipidemia rabbits were treated with the PVA-phosphate adsorbent, and the removal of TC, LDL and TG was 45.03 ± 6.64%, 48.97 ± 9.92% and 35.42 ± 14.17%, respectively. The sterilization and storage tests showed that the adsorbent was chemically and functionally stable. It could be easily sterilized by a common method and stored for months without loss of adsorption capacity. Therefore, this new PVA-phosphate-based LDL adsorbent may have potential for application in LDL apheresis.

Radiation modified sago-blends and its potential for biodegradable packaging materials

Energy Technology Data Exchange (ETDEWEB)

Ghazali, Z.; Idris, S.; Dahlan, K.Z. [Malaysian Institute for Nuclear Technology Research, Bangi, Kajang (Malaysia); Wongsuban, B.; Adzahan, N.M.; Ithnin, L. [Universiti Putra Malaysia, Faculty of Food Science and Biotechnology, Serdang (Malaysia)

2002-03-01

This paper describes work at MINT on the characterisation and development of sago blends as alternative biodegradable packaging materials. A study was undertaken to investigate the effect of formulation, mixing temperature and irradiation dosage on expansion of sago starch-polyvinyl alcohol (PVA) and sago-polyvinyl pyrrolidone (PVP) blends based foam. The foams were produced by microwaving irradiated hydrogels prepared by mixing sago starch with aqueous PVA or PVP. In the development of starch-based plastic, the effect of different composition and different irradiation dosage were studied to evaluate films with good tensile properties, elongation, gas permeability and water vapor transmission rate and also the biodegradability of the film using soil burial test. In another development, irradiation i.e. microwave, electron beam and gamma, has been investigated as a means of degrading the starch granules, which leads to an increase in the amount soluble materials leached. Results showed that irradiation caused an increase in leaching, and a concomitant drastic reduction in swelling volumes of starch granules. It is also showed that the strength of starch gels and viscosity decreased as the levels of irradiation was increased. The degraded starches will be incorporated as an ingredient in the fish cracker and characterized its properties. (author)

Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

Science.gov (United States)

Afshari, Esmail; Mazinani, Saeedeh; Ranaei-Siadat, Seyed-Omid; Ghomi, Hamid

2016-11-01

Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

Gum tragacanth-polyvinyl alcohol cryogel and xerogel blends for oral delivery of silymarin: Structural characterization and mucoadhesive property.

Science.gov (United States)

Niknia, Nushin; Kadkhodaee, Rassoul

2017-12-01

In this study silymarin (SM) loaded cryo- and xerogels of gum tragacanth-polyvinyl alcohol (GT-PVA) were prepared and their physico-mechanical, microstructural and release properties were investigated. The results showed that unlike cryogels, which were highly porous, xerogels exhibited a densely packed agglomerated microstructure with a continuous network of cracks. The bulk density, mechanical strength and SM retention of xerogels were also much higher than those of cryogels. Furthermore, it was revealed that increasing the ratio of GT adversely influenced both physico-mechanical and structural features of the dried gels, but improved the release profile of SM. Incorporation of SM into the gels led to a distinct enhancement in their porosity, microstructure and physical properties. Rheological measurements indicated that rising the ratio of GT and inclusion of SM increased the viscosity of mucin-polymers blend and improved mucoadhesive property of the gels. Copyright © 2017. Published by Elsevier Ltd.

Flame-retardant polyvinyl alcohol membrane with high transparency based on a reactive phosphorus-containing compound.

Science.gov (United States)

Peng, Sha; Zhou, Ming; Liu, Feiyan; Zhang, Chang; Liu, Xueqing; Liu, Jiyan; Zou, Liyong; Chen, Jia

2017-08-01

Flame-retardant polyvinyl alcohol (PVA) membranes with high transparency and flexibility were prepared by mixing an aqueous solution of a phosphorus-containing acrylic acid (AOPA) with PVA. The reaction between AOPA and PVA, the transparency, the crystallinity and the flexibility of the membrane were investigated with Fourier transform infrared spectrometry (FTIR), UV-vis light transmittance, X-ray diffraction and tensile tests, respectively. The limited oxygen index (LOI) and vertical flame (UL 94 VTM), microscale combustion calorimetry, thermogravimetric analysis (TGA) and TGA-FTIR were employed to evaluate the flame retardancy as well as to reveal the corresponding mechanisms. Results showed that PVA containing 30 wt% of AOPA can reach the UL 94 VTM V0 rating with an LOI of 27.3% and retain 95% of the original transparency of pure PVA. Adding AOPA reduces crystallinity of PVA, while the flexibility is increased. AOPA depresses the thermal degradation of PVA and promotes char formation during combustion. The proposed decomposition mechanism indicates that AOPA acts mainly in the condensed phase.

Poly(vinyl alcohol) separators improve the coulombic efficiency of activated carbon cathodes in microbial fuel cells

KAUST Repository

Chen, Guang

2013-09-01

High-performance microbial fuel cell (MFC) air cathodes were constructed using a combination of inexpensive materials for the oxygen reduction cathode catalyst and the electrode separator. A poly(vinyl alcohol) (PVA)-based electrode separator enabled high coulombic efficiencies (CEs) in MFCs with activated carbon (AC) cathodes without significantly decreasing power output. MFCs with AC cathodes and PVA separators had CEs (43%-89%) about twice those of AC cathodes lacking a separator (17%-55%) or cathodes made with platinum supported on carbon catalyst (Pt/C) and carbon cloth (CE of 20%-50%). Similar maximum power densities were observed for AC-cathode MFCs with (840 ± 42 mW/m2) or without (860 ± 10 mW/m2) the PVA separator after 18 cycles (36 days). Compared to MFCs with Pt-based cathodes, the cost of the AC-based cathodes with PVA separators was substantially reduced. These results demonstrated that AC-based cathodes with PVA separators are an inexpensive alternative to expensive Pt-based cathodes for construction of larger-scale MFC reactors. © 2013 Elsevier B.V. All rights reserved.

Surface modification of polyamide reverse osmosis membrane with sulfonated polyvinyl alcohol for antifouling

Science.gov (United States)

Zhang, Yang; Wan, Ying; Pan, Guoyuan; Shi, Hongwei; Yan, Hao; Xu, Jian; Guo, Min; Wang, Zhe; Liu, Yiqun

2017-10-01

Sulfonated polyvinyl alcohol (SPVA) was synthesized by esterification reaction of PVA and sulfuric acid, and the structure was characterized by FTIR spectrum. Then a series of TFC membranes modified with cross-linked SPVA layer were fabricated by coating method, with glutaraldehyde as the cross-linker. The resulting TFC membranes were characterized by SEM, AFM, ATR-FTIR, XPS, streaming potential as well as static contact angle. The TFC membranes modified with SPVA exhibit decreased water flux and increased NaCl rejection with SPVA content increasing in the coating aqueous solution. The optimal PA-SPVA-0.5 sample exhibits a NaCl rejection of 99.18%, which is higher than the 98.32% of the virgin PA membrane. More importantly, the PA-SPVA-0.5 membrane shows much more improved fouling resistance to BSA and CTAB than virgin PA membrane and the TFC sample modified with PVA (PA-PVA-0.5). PA-SPVA-0.5 membrane loses about 8% of the initial flux after BSA fouling for 12 h, which is much lower than those of virgin PA and PA-PVA-0.5 membranes (28% and 15%, respectively). Furthermore, the flux recovery of the PA-SPVA-0.5 membrane reaches above 95% after cleaning. Thus, the PA-SPVA-0.5 membrane shows potential applications as antifouling RO membrane for desalination and purification.

Novel carboxymethyl cellulose-polyvinyl alcohol blend films stabilized by Pickering emulsion incorporation method.

Science.gov (United States)

Fasihi, Hadi; Fazilati, Mohammad; Hashemi, Mahdi; Noshirvani, Nooshin

2017-07-01

The aim of this study was to investigate the possibility of increasing the antimicrobial and antioxidant properties of biodegradable active films stabilized via Pickering emulsions. The blend films were prepared from carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVA), emulsified with oleic acid (OL) and incorporated with rosemary essential oil (REO). Formation of Pickering emulsion was confirmed by scanning electron microscopy (SEM), optical microscopy, mean droplet size and emulsion stability. Morphological, optical, physical, mechanical, thermal, antifungal and antioxidant properties of the films incorporated with different concentrations of REO (0.5, 1.5 and 3%) were determined. The results showed an increase in UV absorbance and elongation at break but, a decrease in tensile strength and thermal stability of the films. Interestingly, films containing REO exhibited considerable antioxidant and antimicrobial properties. In vitro microbial tests exhibited 100% fungal inhibition against Penicillium digitatum in the films containing 3% REO. In addition, no fungal growth were observed after 60days of storage at 25°C in bread slices were stored with active films incorporated with 3% REO, could attributed to the slow and regular release of REO caused by Pickering emulsions. The results of this study suggest that Pickering emulsion is a very promising method, which significantly affects antioxidant and antimicrobial activities of the films. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of the alcohol-yielding capacity of cereals. A method for the determination of the alcohol-yielding capacity

Energy Technology Data Exchange (ETDEWEB)

Frey, A; Hoppe, W

1957-01-01

A laboratory method is reported for the determination of the alcohol yielding capacity of starch-containing distillery raw materials. The starch is inverted with dilute HCl under pressure, after which the material is fermented with yeast at pH 5.4. After distillation, the alcohol is determined pyknometrically. The influence of such factors as amount of yeast was determined experimentally. Analysis of the time curves for the hydrolysis of starch (by paper-chromatographic techniques) in relation to pH showed glucose to be the principal reaction product, with only slight amounts of maltose and higher sugars being formed.

Starch nanoparticle as a vitamin E-TPGS carrier loaded in silk fibroin-poly(vinyl alcohol)-Aloe vera nanofibrous dressing.

Science.gov (United States)

Kheradvar, Shadi Alsadat; Nourmohammadi, Jhamak; Tabesh, Hadi; Bagheri, Behnam

2018-06-01

Core-sheath nanofibrous mat as a new vitamin E (VE) delivery system based on silk fibroin (SF)/poly(vinyl alcohol) (PVA)/aloe vera (AV) was successfully prepared by the electrospinning method. Initially, VE-loaded starch nanoparticles were produced and then incorporated into the best beadless SF-PVA-AV nanofibers. The successful loading of VE in starch nanoparticles was proved by Fourier-transform infrared spectroscopy. The scanning electron microscopy and transmission electron microscopy indicated that spherical nanoparticles were successfully embedded within the nanofibers. In vitro release studies demonstrated that the release of VE was controlled by Fickian diffusion and was faster in samples containing more nanoparticles. Fibroblast attachment, proliferation, and collagen secretion were enhanced after adding AV and VE to the SF-PVA nanomatrix. Moreover, the incorporation of VE into the nanocomposite dressing enhanced antioxidant activity, which can have a positive effect on wound healing process by protecting the cells from toxic oxidation products. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of Chain Conformation of Poly(vinyl alcohol) in Solutions and Melts from Quantum Chemistry Based Molecular Dynamics Simulations

Science.gov (United States)

Jaffe, Richard; Han, Jie; Matsuda, Tsunetoshi; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)

1997-01-01

Confirmations of 2,4-dihydroxypentane (DHP), a model molecule for poly(vinyl alcohol), have been studied by quantum chemistry (QC) calculations and molecular dynamics (MD) simulations. QC calculations at the 6-311G MP2 level show the meso tt conformer to be lowest in energy followed by the racemic tg, due to intramolecular hydrogen bond between the hydroxy groups. The Dreiding force field has been modified to reproduce the QC conformer energies for DHP. MD simulations using this force field have been carried out for DHP molecules in the gas phase, melt, and CHCl3 and water solutions. Extensive intramolecular hydrogen bonding is observed for the gas phase and CHCl3 solution, but not for the melt or aqueous solution, Such a condensed phase effect due to intermolecular interactions results in a drastic change in chain conformations, in agreement with experiments.

Three-Dimensional Printed Poly(vinyl alcohol) Substrate with Controlled On-Demand Degradation for Transient Electronics.

Science.gov (United States)

Yoon, Jinsu; Han, Jungmin; Choi, Bongsik; Lee, Yongwoo; Kim, Yeamin; Park, Jinhee; Lim, Meehyun; Kang, Min-Ho; Kim, Dae Hwan; Kim, Dong Myong; Kim, Sungho; Choi, Sung-Jin

2018-05-25

Electronics that degrade after stable operation for a desired operating time, called transient electronics, are of great interest in many fields, including biomedical implants, secure memory devices, and environmental sensors. Thus, the development of transient materials is critical for the advancement of transient electronics and their applications. However, previous reports have mostly relied on achieving transience in aqueous solutions, where the transience time is largely predetermined based on the materials initially selected at the beginning of the fabrication. Therefore, accurate control of the transience time is difficult, thereby limiting their application. In this work, we demonstrate transient electronics based on a water-soluble poly(vinyl alcohol) (PVA) substrate on which carbon nanotube (CNT)-based field-effect transistors were fabricated. We regulated the structural parameters of the PVA substrate using a three-dimensional (3D) printer to accurately control and program the transience time of the PVA substrate in water. The 3D printing technology can produce complex objects directly, thus enabling the efficient fabrication of a transient substrate with a prescribed and controlled transience time. In addition, the 3D printer was used to develop a facile method for the selective and partial destruction of electronics.

Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

Energy Technology Data Exchange (ETDEWEB)

Lenhart, Markus; Schneider, Hans [Sozialstiftung Bamberg, Department of Diagnostic and Interventional Radiology, Bamberg (Germany); Paetzel, Christian [Klinikum Weiden, Department of Radiology, Weiden (Germany); Sackmann, Michael [Sozialstiftung Bamberg, Department of Gastroenterology, Bamberg (Germany); Jung, Ernst Michael; Schreyer, Andreas G.; Feuerbach, Stefan; Zorger, Niels [University of Regensburg, Department of Radiology, Regensburg (Germany)

2010-08-15

To evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl alcohol copolymer from two centres. We retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone. Cause of haemorrhage and technical and clinical success were documented. Arterial embolotherapy was successful in all 16 cases. The technical success rate was 100%. The cause of bleeding was pancreatitis in four, graft-versus-host disease (GVHD) of the colon in three, malignancy in three, angiodysplasia in two, ulcer in two and panarteritis no dosa and trauma in one each. There were no procedure-related complications. No bowel necrosis occurred because of embolisation. In 13 cases, the patients were discharged in good condition (81%); the three patients with GVHD died because of the underlying disease. The copolymer seems to have great potential in embolotherapy of acute arterial gastrointestinal bleeding. In our series none of the patients had rebleeding at the site of embolisation and no clinically obvious bowel necrosis occurred. (orig.)

Synthesis, characterization and antibacterial properties of a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag

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Mansour Ghaffari-Moghaddam

2014-11-01

Full Text Available In this study, a novel nanocomposite based on polyaniline/polyvinyl alcohol/Ag (PANI/PVA/Ag has been successfully synthesized. The chemical reduction method was used to produce Ag nanoparticle colloidal solution from Ag+ ions. The polymerization of aniline occurred in situ for the preparation of polyaniline (PANI in the presence of ammonium persulfate. With exposure to Ag nanoparticles on the PANI/PVA composite, a new nanocomposite was obtained. The morphology and particle size of the novel nanocomposite was studied by scanning electron microscopy (SEM, X-ray diffraction (XRD, and Fourier transform infrared (FT-IR analyses. According to XRD analysis, the size of nanoparticles was found to be in the range of 10–17 nm. SEM images showed the favored shape of nanoparticles as triangle which is a benign shape for antibacterial analysis. The antibacterial activity of the obtained nanocomposite was also evaluated against Gram positive bacteria Staphylococcus aureus (Staph. aureus and Gram negative Escherichia coli (E. coli using the paper disk diffusion method. The antibacterial study showed that the PANI/PVA composite did not have a very good antibacterial activity but PANI/PVA/Ag nanocomposites were found to be effective against two bacteria.

Influence of polyvinyl alcohol amount on producing in situ photo-crosslinked thioamide functionalized nanofiber membranes

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Zeytuncu Bihter

2015-01-01

Full Text Available Poly(vinyl alcohol/maleic anhydride/acryloyl thioamide monomer (PVA/MA/ATM photo-cured nanofiber membranes and pure PVA nanofiber membranes were produced by electrospinning technique. In situ UV radiation was applied during the electrospinning in order to provide polymerization during the jet flight and promote crosslinking of ATM and MA with PVA. The cross-linking was examined by Fourier-transform infrared spectroscopy (FTIR. The morphology and thermal behavior of electrospun nanofiber were characterized by scanning electron microscope (SEM and thermogravimetric analysis (TGA, respectively. The surface area of nanofiber membranes was measured by Brunauer-Emmert-Teller (BET analysis. Furthermore, water durability test was examined. Water durability test demonstrated that in situ photo-cured PVA/MA/ATM nanofiber membrane had the least average mass loss. The surface areas of PVA/MA/ATM nanofiber membranes were 160-280 m2/g. The surface area and diameter of PVA/MA/ATM nanofibers decreased as the PVA content increased. The diameter of nanofibers was obtained less than 100 nm. The results showed that the water-insoluble nanofiber membranes with better chemical and thermal resistance were obtained. These nanofiber membranes may be a promising candidate for the usage of water treatment.

Mechanism and Characteristics of Humidity Sensing with Polyvinyl Alcohol-Coated Fiber Surface Plasmon Resonance Sensor.

Science.gov (United States)

Shao, Yu; Wang, Ying; Cao, Shaoqing; Huang, Yijian; Zhang, Longfei; Zhang, Feng; Liao, Changrui; Wang, Yiping

2018-06-25

A surface plasmon resonance (SPR) sensor based on a side-polished single mode fiber coated with polyvinyl alcohol (PVA) is demonstrated for relative humidity (RH) sensing. The SPR sensor exhibits a resonant dip in the transmission spectrum in ambient air after PVA film coating, and the resonant wavelength shifts to longer wavelengths as the thickness of the PVA film increases. When RH changes, the resonant dip of the sensor with different film-thicknesses exhibits interesting characteristics for optical spectrum evolution. For sensors with initial wavelengths between 550 nm and 750 nm, the resonant dip shifts to longer wavelengths with increasing RH. The averaged sensitivity increases firstly and then drops, and shows a maximal sensitivity of 1.01 nm/RH%. Once the initial wavelength of the SPR sensor exceeds 850 nm, an inflection point of the resonant wavelength shift can be observed with RH increasing, and the resonant dip shifts to shorter wavelengths for RH values exceeding this point, and sensitivity as high as −4.97 nm/RH% can be obtained in the experiment. The sensor is expected to have potential applications in highly sensitive and cost effective humidity sensing.

Mechanism and Characteristics of Humidity Sensing with Polyvinyl Alcohol-Coated Fiber Surface Plasmon Resonance Sensor

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Yu Shao

2018-06-01

Full Text Available A surface plasmon resonance (SPR sensor based on a side-polished single mode fiber coated with polyvinyl alcohol (PVA is demonstrated for relative humidity (RH sensing. The SPR sensor exhibits a resonant dip in the transmission spectrum in ambient air after PVA film coating, and the resonant wavelength shifts to longer wavelengths as the thickness of the PVA film increases. When RH changes, the resonant dip of the sensor with different film-thicknesses exhibits interesting characteristics for optical spectrum evolution. For sensors with initial wavelengths between 550 nm and 750 nm, the resonant dip shifts to longer wavelengths with increasing RH. The averaged sensitivity increases firstly and then drops, and shows a maximal sensitivity of 1.01 nm/RH%. Once the initial wavelength of the SPR sensor exceeds 850 nm, an inflection point of the resonant wavelength shift can be observed with RH increasing, and the resonant dip shifts to shorter wavelengths for RH values exceeding this point, and sensitivity as high as −4.97 nm/RH% can be obtained in the experiment. The sensor is expected to have potential applications in highly sensitive and cost effective humidity sensing.

Effects of aniline concentrations on the electrical and mechanical properties of polyaniline polyvinyl alcohol blends

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J. Bhadra

2017-07-01

Full Text Available In this work, we present an exclusive study on the effect of the feeding ratio of the monomer (aniline on the structural, thermal, mechanical and electrical properties of polyaniline (PANI polyvinyl alcohol (PVA blends. The films obtained from the blends are characterised to determine their surface properties and structural morphology (elemental analysis, SEM and FTIR, thermal properties (TGA and DSC and optical properties (UV–Vis spectroscopy. We study the effects of aniline on the mechanical and electrical properties of the composites by performing tensile, four probe and A.C. conductivity measurements, respectively. The SEM images reveal a heterogeneous distribution of conductive PANI particles in the continuous PVA matrix. During this experiment, the tensile strength of the blend films is maintained with an increase in the amount of aniline (up to 25 wt%, and this behaviour is attributed to intermolecular hydrogen bonding between PANI and PVA in the presence of the surfactant DBSA. The potential attraction of the experiment lies in the nature of the conductivity (of the blend films, which is found to increase from 10−8 to 10−3 S/cm with a percolation threshold of 0.78 wt%.

Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

International Nuclear Information System (INIS)

Lenhart, Markus; Schneider, Hans; Paetzel, Christian; Sackmann, Michael; Jung, Ernst Michael; Schreyer, Andreas G.; Feuerbach, Stefan; Zorger, Niels

2010-01-01

To evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl alcohol copolymer from two centres. We retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone. Cause of haemorrhage and technical and clinical success were documented. Arterial embolotherapy was successful in all 16 cases. The technical success rate was 100%. The cause of bleeding was pancreatitis in four, graft-versus-host disease (GVHD) of the colon in three, malignancy in three, angiodysplasia in two, ulcer in two and panarteritis no dosa and trauma in one each. There were no procedure-related complications. No bowel necrosis occurred because of embolisation. In 13 cases, the patients were discharged in good condition (81%); the three patients with GVHD died because of the underlying disease. The copolymer seems to have great potential in embolotherapy of acute arterial gastrointestinal bleeding. In our series none of the patients had rebleeding at the site of embolisation and no clinically obvious bowel necrosis occurred. (orig.)

Synthesis and characterization of poly(vinyl alcohol) membranes with quaternary ammonium groups for wound dressing.

Science.gov (United States)

Chen, Kuo-Yu; Lin, Yu-Sheng; Yao, Chun-Hsu; Li, Ming-Hsien; Lin, Jui-Che

2010-01-01

2-[(acryloyloxy)ethyl]Trimethylammonium chloride (AETMAC) was grafted onto poly(vinyl alcohol) (PVA) using ceric ammonium nitrate (CAN) as a redox initiator. A series of graft co-polymer (PVA-g-PAETMAC) membranes with different contents of AETMAC were prepared with a casting method. The incorporation of AETMAC into PVA chains was confirmed by element analysis and Fourier transform infrared spectroscopy. The effects of grafting on the thermal properties, water take, water vapor transmission rate (WVTR), contact angle, antibacterial activity and cytotoxicity of PVA-g-PAETMAC membranes were investigated. The experiment results showed that PVA-g-PAETMAC membrane has a higher equilibrium swelling ratio, surface hydrophilicity and WVTR than pure PVA membrane. Moreover, the higher the content of AETMAC, the higher were equilibrium swelling ratio, surface hydrophilicity and WVTR. In vitro bacterial adhesion study demonstrated a significantly reduced number of Staphylococcus aureus and Escherichia coli on PVA-g-PAETMAC surfaces when compared to PVA surface. In addition, no significant difference in the in vitro cytotoxicity was observed between PVA and PVA-g-PAETMAC membranes. The presence of quaternary ammonium groups did not reduce L929 cell growth. Therefore, the PVA-g-PAETMAC membranes have the potential for wound-dressing application.

Fabrication of multicolor fluorescent polyvinyl alcohol through surface modification with conjugated polymers by oxidative polymerization

Science.gov (United States)

Hai, Thien An Phung; Sugimoto, Ryuichi

2018-06-01

A simple method for the preparation of multicolor polyvinyl alcohol (PVA) by chemical oxidative polymerization is introduced. The PVA surface was successfully modified with conjugated polymers composed of 3-hexylthiophene (3HT) and fluorene (F). The incorporation of the 3HT/F copolymer onto the PVA surface was confirmed by Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-vis), and fluorescence spectroscopies, X-ray diffraction (XRD), as well as thermogravimetric analysis (TGA), contact angle, and field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX) analysis. Different 3HT/F ratios on the PVA surface result in optical properties that include multicolor-emission and absorption behavior. The color of the resultant (3HT/F)-g-PVA shifted from red to blue, and the quantum yield increased with increasing F content. The surface hydrophobicity of the modified PVA increased significantly through grafting with the conjugated polymers, with the water contact angle increasing by 30° compared to pristine PVA. The PVA XRD peaks were less intense following surface modification. Thermogravimetric analyses reveal that the thermal stability of the PVA decreases as a result of grafting with the 3HT/F copolymers.

Biomimetically Reinforced Polyvinyl Alcohol-Based Hybrid Scaffolds for Cartilage Tissue Engineering

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Hwan D. Kim

2017-11-01

Full Text Available Articular cartilage has a very limited regeneration capacity. Therefore, injury or degeneration of articular cartilage results in an inferior mechanical stability, load-bearing capacity, and lubrication capability. Here, we developed a biomimetic scaffold consisting of macroporous polyvinyl alcohol (PVA sponges as a platform material for the incorporation of cell-embedded photocrosslinkable poly(ethylene glycol diacrylate (PEGDA, PEGDA-methacrylated chondroitin sulfate (PEGDA-MeCS; PCS, or PEGDA-methacrylated hyaluronic acid (PEGDA-MeHA; PHA within its pores to improve in vitro chondrocyte functions and subsequent in vivo ectopic cartilage tissue formation. Our findings demonstrated that chondrocytes encapsulated in PCS or PHA and loaded into macroporous PVA hybrid scaffolds maintained their physiological phenotypes during in vitro culture, as shown by the upregulation of various chondrogenic genes. Further, the cell-secreted extracellular matrix (ECM improved the mechanical properties of the PVA-PCS and PVA-PHA hybrid scaffolds by 83.30% and 73.76%, respectively, compared to their acellular counterparts. After subcutaneous transplantation in vivo, chondrocytes on both PVA-PCS and PVA-PHA hybrid scaffolds significantly promoted ectopic cartilage tissue formation, which was confirmed by detecting cells positively stained with Safranin-O and for type II collagen. Consequently, the mechanical properties of the hybrid scaffolds were biomimetically reinforced by 80.53% and 210.74%, respectively, compared to their acellular counterparts. By enabling the recapitulation of biomimetically relevant structural and functional properties of articular cartilage and the regulation of in vivo mechanical reinforcement mediated by cell–matrix interactions, this biomimetic material offers an opportunity to control the desired mechanical properties of cell-laden scaffolds for cartilage tissue regeneration.

Submillimeter Diameter Poly(Vinyl Alcohol) Vascular Graft Patency in Rabbit Model

Science.gov (United States)

Cutiongco, Marie F. A.; Kukumberg, Marek; Peneyra, Jonnathan L.; Yeo, Matthew S.; Yao, Jia Y.; Rufaihah, Abdul Jalil; Le Visage, Catherine; Ho, Jackie Pei; Yim, Evelyn K. F.

2016-01-01

Microvascular surgery is becoming a prevalent surgical practice. Replantation, hand reconstruction, orthopedic, and free tissue transfer procedures all rely on microvascular surgery for the repair of venous and arterial defects at the millimeter and submillimeter levels. Often, a vascular graft is required for the procedure as a means to bridge the gap between native arteries. While autologous vessels are desired for their bioactivity and non-thrombogenicity, the tedious harvest process, lack of availability, and caliber or mechanical mismatch contribute to graft failure. Thus, there is a need for an off-the-shelf artificial vascular graft that has low thrombogenic properties and mechanical properties matching those of submillimeter vessels. Poly(vinyl alcohol) hydrogel (PVA) has excellent prospects as a vascular graft due to its bioinertness, low thrombogenicity, high water content, and tunable mechanical properties. Here, we fabricated PVA grafts with submillimeter diameter and mechanical properties that closely approximated those of the rabbit femoral artery. In vitro platelet adhesion and microparticle release assay verified the low thrombogenicity of PVA. A stringent proof-of-concept in vivo test was performed by implanting PVA grafts in rabbit femoral artery with multilevel arterial occlusion. Laser Doppler measurements indicated the improved perfusion of the distal limb after implantation with PVA grafts. Moreover, ultrasound Doppler and angiography verified that the submillimeter diameter PVA vascular grafts remained patent for 2 weeks without the aid of anticoagulant or antithrombotics. Endothelial cells were observed in the luminal surface of one patent PVA graft. The advantageous non-thrombogenic and tunable mechanical properties of PVA that are retained even in the submillimeter diameter dimensions support the application of this biomaterial for vascular replacement in microvascular surgery. PMID:27376059

Effect of annealing temperature on electrical properties of Au/polyvinyl alcohol/n-InP Schottky barrier structure

International Nuclear Information System (INIS)

Reddy, V. Rajagopal; Reddy, M. Siva Pratap; Kumar, A. Ashok; Choi, Chel-Jong

2012-01-01

In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100–300 °C by current–voltage (I-V) and capacitance–voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200 °C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300 °C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 10 12 and 0.59 × 10 12 cm −2 eV −1 for the as-deposited and 200 °C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature. - Highlights: ► Electrical properties of Au/polyvinyl alcohol (PVA)/n-InP structure have been studied. ► The Au/PVA/n-InP Schottky structure showed a good rectifying behavior. ► A maximum barrier height is obtained when the contact is annealed at 200 °C. ► Interface state density found to be 0.59 × 10 12 cm −2 eV −1 for 200 °C annealed contact. ► Significant effect of interface state density and series resistance on electrical

Study on the performance of eosin-doped poly(vinyl alcohol)/acrylamide photopolymer films for holographic recording using 488-nm wavelength

Science.gov (United States)

Rajesh, Chelakkal Sukumaran; Sreeroop, Sasidharan Savithrydevi; Pramitha, Vayalamkuzhi; Joseph, Rani; Sreekumar, Krishnapillai; Kartha, Cheranellore Sudha

2011-12-01

This article reports a study done on eosin-doped poly(vinyl alcohol)/acrylamide films for holographic recording using 488 nm Ar+ laser. Films were fabricated using gravity settling method at room temperature and were stored under normal laboratory conditions. Ar+ laser (488 nm) was used for fringe recording. Characterization was done by real time transmittance measurement, optical absorption studies, and diffraction efficiency measurements. Various holographic parameters such as exposure energy, recording power, spatial frequency, etc., were optimized so as to ensure maximum performance. More than 85% diffraction efficiency was obtained at an exposure energy of 50 mJ/cm2 in the optimized film. Efforts were taken to study the environmental stability of this self-developing polymeric material by looking at its shelf life and storage life. Compatibility for recording transmission hologram was also checked.

Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ

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Marlon Osorio

2017-01-01

Full Text Available We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC grown by fermentation in the presence of polyvinyl alcohol (PVA followed by physical crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment.

Biodegradable films of starch/PVOH/alginate in packaging systems for minimally processed lettuce (Lactuca sativa L.

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Renata Paula Herrera Brandelero

Full Text Available ABSTRACT Biodegradable packaging may replace non-biodegradable materials when the shelf life of the packaged product is relatively short, as in minimally processed foods. The objective of this work was to evaluate the efficiency of biodegradable films comprising starch/polyvinyl alcohol (PVOH/alginate with the addition of 0 or 0.5% of essential oil of copaiba (EOCP or lemongrass (EOLM compared to poly-vinyl chloride (PVC films in the storage of minimally processed lettuce. Lettuce samples cut into 1-cm strips were placed in polypropylene trays wrapped with biodegradable films and stored at 6 ± 2 °C for 8 days. PVC films were used as controls. The biofilms presented 11.43-8.11 MPa resistance and 11.3-13.22% elongation, with water vapor permeability (WVP of 0.5-4.04 x 10-12 g. s-1.Pa-1.m-1; thus, the films' properties were considered suitable for the application. The lettuce stored in PVC presented minor total soluble solids (TSS, less luminosity (L, higher intensity of yellow color (b, and eight times less mass loss than that stored in biodegradable films. Multivariate analysis showed that the lettuce lost quality after 2 days of storage in PVC films, representing a different result from the other treatments. Lettuce stored in biodegradable films for 2 and 4 days showed a greater similarity with newly harvested lettuce (time zero. The films with or without the addition of essential oil showed similar characteristics. Biodegradable films were considered viable for the storage of minimally processed lettuce.

Supply of avocado starch (Persea americana mill) as bioplastic material

Science.gov (United States)

Ginting, M. H. S.; Hasibuan, R.; Lubis, M.; Alanjani, F.; Winoto, F. A.; Siregar, R. C.

2018-02-01

The purpose of this study was to determine the effect of time precipitation of avocado slurry seed to yield of starch. Starch analysis included starch content, moisture content, amylose content, amylopectin content, ash content, protein content, fat content, Fourier transform infra red analysis and rapid visco analyzer. Supply of starch from avocado seeds was used by extraction method. Every one hundred grams of avocado slurry was precipitated by gravity with variations for 4 hours, 8 hours, 12 hours, 16 hours, 20 hours and 24 hours. The Starch yield was washed, and dried using oven at 70°C for 30 minutes. Starch yield was the highest as 24.20 gram at 24 hours. The result of starch characterization was 73.62%, water content 16.6%, amylose 0.07%, amylopectin 73.55%, ash content 0.23%, protein content 2.16%, fat content 1.09%. Rapid visco analyzer obtained at 91.33°C of gelatinization temperature. Scanning electron microscopy analyzes obtained 20 μm oval-shaped starch granules. Fourier Transform Infra Red analysis of starch obtained the peak spectrum of O-H group of alcohols, C-H alkanes and C-O ether.

Molecular mechanisms in compatibility and mechanical properties of Polyacrylamide/Polyvinyl alcohol blends.

Science.gov (United States)

Wei, Qinghua; Wang, Yanen; Che, Yu; Yang, Mingming; Li, Xinpei; Zhang, Yingfeng

2017-01-01

The objectives of this study were to develop a computational model based on molecular dynamics technique to investigate the compatibility and mechanical properties of Polyacrylamide (PAM)/Polyvinyl alcohol (PVA) blends. Five simulation models of PAM/PVA with different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using molecular dynamics (MD) simulation. The interaction mechanisms of molecular chains in PAM/PVA blend system were elaborated from the aspects of the compatibility, mechanical properties, binding energy and pair correlation function, respectively. The computed values of solubility parameters for PAM and PVA indicate PAM has a good miscibility with PVA. The results of the static mechanical analysis, based on the equilibrium structures of blends with differing component ratios, shows us that the elastic coefficient, engineering modulus, and ductility are increased with the addition of PVA content, which is 4/0 PAM/PVAPVAPVAPVAPVA. Moreover, binding energy results indicate that a stronger interaction exists among PVA molecular chains comparing with PAM molecular chains, which is why the mechanical properties of blend system increasing with the addition of PVA content. Finally, the results of pair correlation functions (PCFs) between polar functional groups and its surrounding hydrogen atoms, indicated they interact with each other mainly by hydrogen bonds, and the strength of three types of polar functional groups has the order of O(-OH)>O(-C=O)>N(-NH 2 ). This further elaborates the root reason why the mechanical properties of blend system increase with the addition of PVA content. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

Science.gov (United States)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO 2/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH 3OH solution is about 11.48 mW cm -2. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications.

Photochromic and thermal properties of poly(vinyl alcohol)/H6P2W18O62 hybrid membranes

International Nuclear Information System (INIS)

Gong Jian; Li Xiangdan; Shao Changlu; Ding Bin; Lee, Douk-Rae; Kim, Hak-Yong

2003-01-01

Poly(vinyl alcohol) (PVA) films, which contained different content of heteropolyacid (HPA) with Dawson-Wells structure, were prepared. The photochromic behavior was investigated by using ultraviolet-visible (UV-Vis) absorption spectroscopy. The result indicated that the film was reduced photochemically to yield a blue species under UV irradiation, and the color of the film changed to deep blue with increasing irradiation time and HPA content. The photochromic sensibility of different UV wavelength was investigated. In the UV-Vis spectra of the irradiated films, an isobestic point was observed at about 352 nm. The reduction mechanism of the heteropolyanion (W 6+ →W 5+ ) was suggested. The thermal property and the conductivity of the film were also studied. The thermal degradation step and the melting point of the film were influenced by different content of the HPA. Notably, the conductivity of 8.33x10 -6 S cm -1 was observed when the HPA content was 80 wt.%

Hydrogels based on chemically modified poly(vinyl alcohol (PVA-GMA and PVA-GMA/chondroitin sulfate: Preparation and characterization

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E. C. Muniz

2012-05-01

Full Text Available This work reports the preparation of hydrogels based on PVA-GMA, PVA-GMA is poly(vinyl alcohol (PVA functionalized with vinyl groups from glycidyl methacrylate (GMA, and on PVA-GMA with different content of chondroitin sulfate (CS. The degrees of swelling of PVA-GMA and PVA-GMA/CS hydrogels were evaluated in distilled water and the swelling kinetics was performed in simulated gastric and intestinal fluids (SGF and SIF. PVA-GMA and PVAGMA/CS hydrogels demonstrated to be resistant on SGF and SIF fluids. The elastic modulus, E, of swollen-hydrogels were determined through compressive tests and, according to the obtained results, the hydrogels presented good mechanical properties. At last, the presence of CS enhances the hydrogel cell compatibility as gathered by cytotoxicity assays. It was concluded that the hydrogels prepared through this work presented characteristics that allow them to be used as biomaterial, as a carrier in drug delivery system or to act as scaffolds in tissue engineering as well.

Removal of Reactive-dyes from Textile Plant Effluents Using Polyvinyl Alcohol-coated Active Carbon obtained from Sesame Seeds

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Sheida Moradi- Nasab

2016-09-01

Full Text Available In this study, the adsorption of active carbon derived from waste sesame seeds coated with polyvinyl alcohol (AC/PVA was investigated for removing red 198 and blue 19 reactive dyes from textile effluents. The batch process was carried out to identify such parameters as pH, adsorbent dose, contact time, and initial dye concentration involved in the dye removal adsorption capacity of AC/PVA. Also, batch kinetic and isotherm experiments were conducted. Results indicated that the maximum dye removal was obtained in an acidic pH over 90 min of contact time and that adsorption rates followed the pseudo-second-order kinetics. Blue and red dye concentrations were determined using the spectrophotometric method at 590 and 517 nm, respectively. It may be concluded that AC/PVA is capable of removing blue and red reactive dyes and can be used as an efficient, cheap, and accessible adsorbent for treating textile effluents.

Electrochemical performance of an air-breathing direct methanol fuel cell using poly(vinyl alcohol)/hydroxyapatite composite polymer membrane

Energy Technology Data Exchange (ETDEWEB)

Yang, Chun-Chen; Chiu, Shwu-Jer; Lin, Che-Tseng [Department of Chemical Engineering, Mingchi University of Technology, Taipei Hsien 243 (China)

2008-02-15

A novel composite polymer membrane based on poly(vinyl alcohol)/hydroxyapatite (PVA/HAP) was successfully prepared by a solution casting method. The characteristic properties of the PVA/HAP composite polymer membranes were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), micro-Raman spectroscopy and AC impedance method. An air-breathing DMFC, comprised of an air cathode electrode with MnO{sub 2}/BP2000 carbon inks on Ni-foam, an anode electrode with PtRu black on Ti-mesh, and the PVA/HAP composite polymer membrane, was assembled and studied. It was found that this alkaline DMFC showed an improved electrochemical performance at ambient temperature and pressure; the maximum peak power density of an air-breathing DMFC in 8 M KOH + 2 M CH{sub 3}OH solution is about 11.48 mW cm{sup -2}. From the application point of view, these composite polymer membranes show a high potential for the DMFC applications. (author)

Chemical changes of starch during boiling, in alcohol production

Energy Technology Data Exchange (ETDEWEB)

Sotskaya, B P; Smirnova, V A

1961-01-01

The chemical conversion of potato starch during heating was dependent upon the pH and the heat regime. Under mild conditions, at pH 6.5 the molecular weight remained similar to that of the native starch and the reducing value increased only 0.0007%; at pH 3.5 the molecular weight dropped to about 3900 and the reducing value increased to 3.83%, and at pH 2.4 a mixture of glucose and oligosaccharides was formed. Under a more rigorous regime, at pH 6.5, the molecular weight decreased 6 to 7 times and the reducing value was 0.45%. At pH 2.4 glucose was the conversion product formed.

Poly(furfuryl alcohol)

Indian Academy of Sciences (India)

This paper describes a facile hydrothermal approach to the large-scale synthesis of well-dispersed poly(furfuryl alcohol) (PFA) nanospheres with an average diameter of 350 nm in the presence of poly(vinyl pyrrolidone) (PVP). Scanning electron microscopy and transmission electron microscopy studies showed that ...

Poly(vinyl alcohol Nanocomposites Reinforced with Bamboo Charcoal Nanoparticles: Mineralization Behavior and Characterization

Directory of Open Access Journals (Sweden)

Cheng-Ming Tang

2015-07-01

Full Text Available Polyvinyl alcohol (PVA demonstrates chemical stability and biocompatibility and is widely used in biomedical applications. The porous bamboo charcoal has excellent toxin absorptivity and has been used in blood purification. In this study, bamboo charcoal nanoparticles (BCNPs were acquired with nano-grinding technology. The PVA and PVA/BCNP nanocomposite membranes were prepared and characterized by the tensile test, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR and X-ray diffraction (XRD. Results showed that the tensile strength and elongation of the swollen PVA membranes containing 1% BCNPs (PB1 were significantly greater than those of PVA and other PVA/BCNP composite membranes. In addition, the major absorption band of OH stretching in the IR spectra shifted from 3262 cm−1 for PVA membrane containing 1% BCNP to 3244 cm−1 for PVA membrane containing 20% BCNP. This blue shift might be attributed to the interaction between the PVA molecules and BCNPs. Moreover, the intensity of the XRD peaks in PVA was decreased with the increased BCNP content. The bioactivity of the nanocomposites was evaluated by immersion in the simulated body fluid (SBF for seven days. The mineral deposition on PB5 was significantly more than that on the other samples. The mineral was identified as hydroxyapatite (HA by XRD. These data suggest that the bioactivity of the composite hydrogel membranes was associated with the surface distribution of hydrophilic/hydrophobic components. The PVA/BCNP composite hydrogels may have potential applications in alveolar bone regeneration.

Preparation and Characterization of Polyvinyl Alcohol-Chitosan Composite Films Reinforced with Cellulose Nanofiber

Science.gov (United States)

Choo, Kaiwen; Ching, Yern Chee; Chuah, Cheng Hock; Julai, Sabariah; Liou, Nai-Shang

2016-01-01

In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3–4 nm. Bio-nanocomposite films were then prepared from a polyvinyl alcohol (PVA)-chitosan (CS) polymeric blend with different TEMPO-oxidized cellulose nanofiber (TOCN) contents (0, 0.5, 1.0 and 1.5 wt %) via the solution casting method. The characterizations of pure PVA/CS and PVA/CS/TOCN films were performed in terms of field emission scanning electron microscopy (FESEM), tensile tests, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results from FESEM analysis justified that low loading levels of TOCNs were dispersed uniformly and homogeneously in the PVA-CS blend matrix. The tensile strength and thermal stability of the films were increased with the increased loading levels of TOCNs to a maximum level. The thermal study indicated a slight improvement of the thermal stability upon the reinforcement of TOCNs. As evidenced by the FTIR and XRD, PVA and CS were considered miscible and compatible owing to hydrogen bonding interaction. These analyses also revealed the good dispersion of TOCNs within the PVA/CS polymer matrix. The improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications. PMID:28773763

Poly(vinyl alcohol) films reinforced with nanofibrillated cellulose (NFC) isolated from corn husk by high intensity ultrasonication.

Science.gov (United States)

Xiao, Shaoliang; Gao, Runan; Gao, LiKun; Li, Jian

2016-01-20

This work was aimed at fabricating and characterizing poly(vinyl alcohol) films that were reinforced by nanofibrillated corn husk celluloses using a combination of chemical pretreatments and ultrasonication. The obtained nanofibrillated celluloses (NFCs) possessed a narrow width ranging from 50 to 250 nm and a high aspect ratio (394). The crystalline type of NFC was cellulose I type. Compared with the original corn husks, the NCF crystallinity and thermal stability increased due to the removal of the hemicelluloses and lignin. PVA films containing different NFC concentrations (0.5%, 1%, 3%, 5%, 7% and 9%, w/w, dry basis) were examined. The 1% PVA/NFC reinforced films exhibited a highly visible light transmittance of 80%, and its tensile strength and the tensile strain at break were increased by 1.47 and 1.80 times compared to that of the pure PVA film, respectively. The NFC with high aspect ratio and high crystallinity is beneficial to the improvement of the mechanical strength and thermal stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improved thermostable polyvinyl alcohol electrospun nanofibers with entangled naringinase used in a novel mini-packed bed reactor.

Science.gov (United States)

Nunes, Mário A P; Martins, Samuel; Rosa, M Emilia; Gois, Pedro M P; Fernandes, Pedro C B; Ribeiro, Maria H L

2016-08-01

Polyvinyl alcohol (PVA) electrospun nanofibers were produced using an electrospinning technique. Key parameters (e.g. collectors, distance from needle tip to collector, among others) that influence the structure and morphology of fibers were optimized. The naringinase entrapped in PVA nanofibers retained over 100% of its initial activity after 212h of operation, at 25°C. Chemical crosslinking with several boronic acids further increased the hydrolysis temperature (up to 85°C) and yielded nanofibers with thermal stability up to 121°C. A mini packed bed reactor (PBR) developed to establish the feasibility for continuous enzymatic operation, ran for 16days at 45°C. Highest naringenin biosynthesis was attained at a flow rate of 10mLh(-1). Highest volumetric (78molL(-1)h(-1)) and specific (26molh(-1)genzyme(-1)) productivities were attained at 30mLh(-1). The activity of NGase in electrospun nanofibers remained constant for almost 16days of operation at 10mLh(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

Functional properties of extruded nano composites based on cassava starch, polyvinyl alcohol and montmorillonite; Propriedades funcionais de nanocompositos extrusados de amido de mandioca, alcool polivinilico e montmorilonita

Energy Technology Data Exchange (ETDEWEB)

Debiagi, Flavia; Mali, Suzana [Departamento de Bioquimica e Biotecnologia, Universidade Estadual de Londrina, PR (Brazil)

2011-07-01

The objectives of this work were to produce expanded nano composites (foams) based on starch, PVA and sodium montmorillonite and characterize them according to their expansion index (EI), density, water absorption capacity (WSC), mechanical properties and X-ray diffraction. The nano composites were prepared in a single-screw extruder using different starch contents (97.6 - 55.2 g/100 g formulation), PVA (0 - 40 g/100 g formulation), unmodified nano clay - Closite - Na (0 - 4. 8 g/100 g formulation) and glycerol (20 g/100 g formulation) as plasticizer. The addition of montmorillonite and PVA resulted in an increase of EI and a decrease of density of the samples, and reduced WSC and increased the mechanical strength of the foams. Through the analysis of X-ray diffraction can be observed that the addition of montmorillonite led to production of intercalated nano composites in all samples. (author)

Metalworking and machining fluids

Science.gov (United States)

Erdemir, Ali; Sykora, Frank; Dorbeck, Mark

2010-10-12

Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.

Electron beam irradiation and addition of poly(vinyl alcohol) affect gelatin based-films properties

International Nuclear Information System (INIS)

Inamura, Patricia Y.; Mastro, Nelida L. del

2015-01-01

Gelatin is a mixture of high molecular weight polypeptides, product of denaturation, and partial structural degradation of collagen, and one of the first materials employed as biomaterials. Aqueous solutions of gelatin (10%), glycerin as plasticizer and poly(vinyl alcohol) (PVA) up to 10% were prepared in a water bath at 70 deg C under constant stirring. Films were irradiated with 10 and 20 kGy using an electron beam accelerator, dose rate of 22.4 kGy s -1 , energy 1.407 MeV, at room temperature, in the presence of air. After irradiation, mechanical properties, color measurements, water absorption, moisture and film solubility were analyzed. The films showed an improvement in maximum force to rupture the film with increase of the irradiation dose. The higher the puncture force to rupture the lower the elongation at break. Colorimetric tests showed significant differences between samples, and also differences depending of the applied radiation dose, and analyzed color parameter. In water absorption tests a decrease of absorption percentage was found with the increase of the dose for PVA free and 5% PVA samples. The addition of PVA increased the water absorption for all applied doses. The modifications in gelatin colloids can be appointed to radiation-induced crosslinking. Also, the PVA concentration in the samples influenced the resultant material properties. (author)

Gold nanorods contained polyvinyl alcohol/chitosan nanofiber matrix for cell imaging and drug delivery

Energy Technology Data Exchange (ETDEWEB)

Yan, Eryun, E-mail: yaney359@126.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Cao, Minglu [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); Wang, Yuwei; Hao, Xiaoyuan [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Pei, Shichun; Gao, Jianwei; Wang, Yan [College of Food and Biological Engineering, Qiqihar University, Qiqihar 161006 (China); Zhang, Zhuanfang [College of Chemistry and Chemical Engineering, Qiqihar University, Qiqihar 161006 (China); Zhang, Deqing, E-mail: zhdqing@163.com [College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China)

2016-01-01

Gold nanorods (AuNRs) that contained polyvinyl alcohol/chitosan (PVA/CS) hybrid nanofibers with dual functions are successfully fabricated by a simple electrospinning method. The results of transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) spectroscopy indicate that AuNRs are indeed encapsulated into the PVA/CS hybrid nanofibers. FTIR spectra results demonstrate that the chemical structures of PVA and CS are not affected when the AuNRs are introduced into the fibers. In vitro cytotoxicity test reveals that the hybrid fibers involving AuNRs are completely biocompatible. The as-prepared fibers can be used as a carrier for anticancer agent doxorubicin (DOX), and the drug is delivered into the cell nucleus. The AuNRs and DOX incorporated fibers are effective for inhibiting the growth and proliferation of ovary cancer cells and they can also be used as the cell imaging agent due to the unique optical properties of AuNRs. The nanofiber matrix combining two functions of cell imaging and drug delivery may be of great application potential in biomedical-related areas. - Highlights: • The AuNRs contained PVA/CS nanofibers are fabricated by electrospinning. • The hybrid fibers involving AuNRs are completely biocompatible. • The DOX loaded fibers are effective for inhibiting the proliferation of cancer cells. • The nanofibers combined two functions of cell imaging and drug delivery.

Electron beam irradiation and addition of poly(vinyl alcohol) affect gelatin based-films properties

Energy Technology Data Exchange (ETDEWEB)

Inamura, Patricia Y.; Mastro, Nelida L. del, E-mail: pinamura@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Gelatin is a mixture of high molecular weight polypeptides, product of denaturation, and partial structural degradation of collagen, and one of the first materials employed as biomaterials. Aqueous solutions of gelatin (10%), glycerin as plasticizer and poly(vinyl alcohol) (PVA) up to 10% were prepared in a water bath at 70 deg C under constant stirring. Films were irradiated with 10 and 20 kGy using an electron beam accelerator, dose rate of 22.4 kGy s{sup -1}, energy 1.407 MeV, at room temperature, in the presence of air. After irradiation, mechanical properties, color measurements, water absorption, moisture and film solubility were analyzed. The films showed an improvement in maximum force to rupture the film with increase of the irradiation dose. The higher the puncture force to rupture the lower the elongation at break. Colorimetric tests showed significant differences between samples, and also differences depending of the applied radiation dose, and analyzed color parameter. In water absorption tests a decrease of absorption percentage was found with the increase of the dose for PVA free and 5% PVA samples. The addition of PVA increased the water absorption for all applied doses. The modifications in gelatin colloids can be appointed to radiation-induced crosslinking. Also, the PVA concentration in the samples influenced the resultant material properties. (author)

Mechanical properties and in vitro characterization of polyvinyl alcohol-nano-silver hydrogel wound dressings.

Science.gov (United States)

Oliveira, R N; Rouzé, R; Quilty, B; Alves, G G; Soares, G D A; Thiré, R M S M; McGuinness, G B

2014-02-06

Polyvinyl alcohol (PVA) hydrogels are materials for potential use in burn healing. Silver nanoparticles can be synthesized within PVA hydrogels giving antimicrobial hydrogels. Hydrogels have to be swollen prior to their application, and the common medium available for that in hospitals is saline solution, but the hydrogel could also take up some of the wound's fluid. This work developed gamma-irradiated PVA/nano-Ag hydrogels for potential use in burn dressing applications. Silver nitrate (AgNO3) was used as nano-Ag precursor agent. Saline solution, phosphate-buffered solution (PBS) pH 7.4 and solution pH 4.0 were used as swelling media. Microstructural evaluation revealed an effect of the nanoparticles on PVA crystallization. The swelling of the PVA-Ag samples in solution pH 4.0 was low, as was their silver delivery, compared with the equivalent samples swollen in the other media. The highest swelling and silver delivery were related to samples prepared with 0.50% AgNO3, and they also presented lower strength in PBS pH 7.4 and solution pH 4.0. Both PVA-Ag samples were also non-toxic and presented antimicrobial activity, confirming that 0.25% AgNO3 concentration is sufficient to establish an antimicrobial effect. Both PVA-Ag samples presented suitable mechanical and swelling properties in all media, representative of potential burn site conditions.

Evaluation of hemocompatibility and endothelialization of hybrid poly(vinyl alcohol) (PVA)/gelatin polymer films.

Science.gov (United States)

Ino, Julia M; Sju, Ervi; Ollivier, Véronique; Yim, Evelyn K F; Letourneur, Didier; Le Visage, Catherine

2013-11-01

Engineered grafts are still needed for small diameter blood vessels reconstruction. Ideal materials would prevent thrombosis and intimal hyperplasia by displaying hemocompatibility and mechanical properties close to those of native vessels. In this study, poly(vinyl alcohol) (PVA)/gelatin blends were investigated as a potential vascular support scaffold. We modified a chemically crosslinked PVA hydrogel by incorporation of gelatin to improve endothelial cell attachment with a single-step method. A series of crosslinked PVA/gelatin films with specific ratios set at 100:0, 99:1, 95:5, and 90:10 (w/w) were prepared and their mechanical properties were examined by uniaxial tensile testing. Tubes, obtained from sutured films, were found highly compliant (3.1-4.6%) and exhibited sufficient mechanical strength to sustain hemodynamic strains. PVA-based hydrogels maintained low level of platelet adhesion and low thrombogenic potential. Endothelial cell adhesion and proliferation were drastically improved on PVA/gelatin films with a feed gelatin content as low as 1% (w/w), leading to the formation of a confluent endothelium. Hydrogels with higher gelatin content did not sustain complete endothelialization because of modifications of the film surface, including phase segregation and formation of microdomains. Thus, PVA/gelatin (99:1, w/w) hydrogels appear as promising materials for the design of endothelialized vascular materials with long-term patency. Copyright © 2013 Wiley Periodicals, Inc.

Synthesis of Highly Effective Novel Graphene Oxide-Polyethylene Glycol-Polyvinyl Alcohol Nanocomposite Hydrogel For Copper Removal

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Eman Serag

2017-10-01

Full Text Available A novel Graphene oxide-polyethylene glycol and polyvinyl alcohol (GO-PEG-PVA triple network hydrogel were prepared to remove Copper(II ion from its aqueous solution. The structures, morphologies, and properties of graphene oxide (GO, the composite GO-PEG-PVA and PEG-PVA were characterized using FTIR, X-ray diffraction, Scanning Electronic Microscope and Thermal Gravimetric analysis. A series of systematic batch adsorption experiments were conducted to study the adsorption property of GO, GO-PEG-PVA hydrogel and PEG-PVA hydrogel under different conditions (e.g. pH, contact time and Cu2+ ions concentration. The high adsorption capacity, easy regeneration, and effective adsorption–desorption results proved that the prepared GO-PEG-PVA composite hydrogel could be an effective adsorbent in removing Cu2+ ion from its aqueous solution. The maximum adsorption capacities were found to be 917, 900 and 423 mg g–1 for GO-PEG-PVA hydrogel, GO and PEG-PVA hydrogel, respectively at pH 5, 25 °C and Cu2+ ions’ concentration 500 mg l–1. The removal efficiency of the recycled GO-PEG-PVA hydrogel were 83, 81, 80 and 79% for the first four times, which proved efficient reusability.

Sugar-Responsive Layer-by-Layer Film Composed of Phenylboronic Acid-Appended Insulin and Poly(vinyl alcohol).

Science.gov (United States)

Takei, Chihiro; Ohno, Yui; Seki, Tomohiro; Miki, Ryotaro; Seki, Toshinobu; Egawa, Yuya

2018-01-01

Previous studies have shown that reversible chemical bond formation between phenylboronic acid (PBA) and 1,3-diol can be utilized as the driving force for the preparation of layer-by-layer (LbL) films. The LbL films composed of a PBA-appended polymer and poly(vinyl alcohol) (PVA) disintegrated in the presence of sugar. This type of LbL films has been recognized as a promising approach for sugar-responsive drug release systems, but an issue preventing the practical application of LbL films is combining them with insulin. In this report, we have proposed a solution for this issue by using PBA-appended insulin as a component of the LbL film. We prepared two kinds of PBA-appended insulin derivatives and confirmed that they retained their hypoglycemic activity. The LbL films composed of PBA-appended insulin and PVA were successfully prepared through reversible chemical bond formation between the boronic acid moiety and the 1,3-diol of PVA. The LbL film disintegrated upon treatment with sugars. Based on the results presented herein, we discuss the suitability of the PBA moiety with respect to hypoglycemic activity, binding ability, and selectivity for D-glucose.

Analysis of physical and magnetic properties of composite NdFeB bind with polyvinyl alcohol

Science.gov (United States)

Ramlan; Sardjono, P.; Muljadi; Setiabudidaya, D.; Gulo, F.

2018-03-01

The composite magnet NdFeB has been made using magnetic powder MQP-B and polyvinyl alcohol (PVA) as the binder. The mixing compositions of raw materials used are: 95 wt% NdFeB - 5 wt% PVA, 92.5 wt% NdFeB - 7.5 wt% PVA, 90 wt.% NdFeB - 10 wt% PVA, and 87.5 wt% NdFeB - 12.5 wt% PVA. Both raw materials are weighed according to the composition, and then mixed until homogeneous. Furthermore, pellet forming was made using dry pressing at 50 kgf/cm2 pressures and continued with drying at 100 °C and 10 mmbar for 4 hours. The characterization includes bulk density, hardness, compressive strength measurements, and magnetic properties testing. The characterization results show that the optimal composition of binder PVA is achieved at 5–7.5 wt% NdFeB composite magnet with following properties: bulk density = 5.21–5.25 g/cm3, hardness = 302.17 - 304.32 Hv, compressive strength = 25.17–3.17 kgf/cm2, magnetic flux = 1150-1170 Gauss, remanence = 70.90–74.97 emu/g or 4.7–5.0 kGauss, coercivity = 8.68–8.76 kOe, and energy product = 2.89–3.04 MgOe.

Novel Polyvinyl Alcohol/Styrene Butadiene Rubber Latex/Carboxymethyl Cellulose Nanocomposites Reinforced with Modified Halloysite Nanotubes

Directory of Open Access Journals (Sweden)

Yanjun Tang

2013-01-01

Full Text Available Novel polyvinyl alcohol (PVA/styrene butadiene rubber (SBR latex/carboxymethyl cellulose (CMC/halloysite nanotubes (HNTs nanocomposites were successfully prepared through physical blending. The as-obtained PVA/SBR/CMC/HNTs nanocomposites were coated on the surface of old corrugated container (OCC-based paper in an effort to improve the mechanical properties of paper. To improve the dispersion of HNTs and enhance the compatibility between HNTs and polymer matrix, HNTs were modified with titanate coupling agent (TCA. FT-IR, together with TGA, confirmed that TCA was grafted onto the surface of HNTs successfully. XRD demonstrated that the crystal structures of HNTs remained almost unchanged. TEM showed that modified HNTs exhibited good dispersion and possessed nanotubular structures with an outer diameter of around 50 nm and an inner diameter of about 20 nm. SEM gave an indication that modified HNTs were dispersed more uniformly than unmodified HNTs within PVA/SBR/CMC matrix. Rheological measurement exhibited that surface modification process enhanced the compatibility between HNTs and polymer matrix, thus resulting in the decreased viscosity of nanocomposites. In comparison with unmodified HNTs, modified HNTs were found to contribute more to the enhancement in mechanical properties, which might be attributed to the better dispersion and compatibility of modified HNTs evidenced by TEM, SEM, and rheological measurement.

Strain monitoring of cement-based materials with embedded polyvinyl alcohol - carbon nanotube (PVA-CNT fibers

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Zoi S. Metaxa

2017-04-01

Full Text Available This article investigates the possibility of exploiting innovative polyvinyl alcohol fibers reinforced with carbon nanotubes (PVA-CNT fiber as a strain sensor in cement mortars used in the restoration of Cultural Heritage Monuments. Two types of PVA-CNT fibers were embedded in the matrix at a short distance from the bottom of the beam and their readings were correlated with traditional sensors, e.g. strain gauges and Fiber Optic Bragg Gratings. The Electrical Resistance Change (ERC of the embedded PVA-CNT fiber was in-situ monitored during four-point bending mechanical tests. For the case of coated PVA-CNT fiber, a linear correlation of the applied strain at the bottom surface of the specimen along with ERC values of the fiber was noticed for the low strain regime. For the case of incremental increasing loading – unloading loops, the coated and annealed PVA-CNT fiber gave the best results either as embedded or as ‘surface attached’ sensor that exhibited linear correlation of ERC with applied strain for the low applied strain regime as well as hysteresis loops during unloading. The article discusses their high potential to be exploited as strain/damage sensor in applications of civil engineering as well as in restoration of Monuments of Cultural Heritage.

Post-Heat Treatment and Mechanical Assessment of Polyvinyl Alcohol Nanofiber Sheet Fabricated by Electrospinning Technique

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Mahir Es-saheb

2014-01-01

Full Text Available Polyvinyl alcohol (PVA sheets based nanofibers were produced by electrospinning technique. Postheat treatment of the produced PVA sheets with temperatures both below and above Tg to improve the mechanical properties of this material is conducted. The morphology, microstructures, and thermal degradation of the nanofibers sheets produced were investigated using scanning electron microscopy (SEM, transmission electron microscope (TEM, and thermal gravimetric analysis (TGA. Produced nanofibers are compact, and entangled with each other, with diameters from around 150 to 210. Some mechanical characteristics of the successfully produced PVA sheets, and heat-treated, are then conducted and assessed employing uniaxial tensile tests at different speeds ranging from 1 mm/min to 100 mm/min. The tensile test results obtained show that the PVA sheets are strain rate sensitive with increasing strength as the speed (i.e., strain rate increases. The yield tensile stress ranges from 2.411 to 6.981 MPa, the ductility (i.e., elongation percent from ∼21 to 60%, and Young modulus ranges from 103 to 0.137 KPa. However, for heat-treated samples, it is found that the yield strength increases almost by ∼35–40% more than the values of untreated cases with values reaching up to about 3.627–9.63 MPa.

Preparation and properties of polyvinyl alcohol (PVA) and hydroxylapatite (HA) hydrogels for cartilage tissue engineering.

Science.gov (United States)

Yuan, F; Ma, M; Lu, L; Pan, Z; Zhou, W; Cai, J; Luo, S; Zeng, W; Yin, F

2017-05-20

A novel bioactive hydrogel for cartilage tissue based on polyvinyl alcohol (PVA) and hydroxylapatite (HA) were prepared, the effects of its component contents on the mechanical properties and microstructure of the hydrogel were investigated. The important properties of the scaffold composites, such as density, porosity, compressive modulus and microstructure were studied and analyzed through various measurements and methods. The biodegradability of hydrogel was evaluated by soaking the samples into artificial degradation solution at body temperature (36 - 37 oC) in vitro. Experimental results showed that the PVA/HA hydrogels had a density of 0.572 - 0.683 g/cm3, a porosity of 63.25 - 96.14% and a compressive modulus of 5.62 - 8.24 MP. The HA compound in the hydrogels enhanced the biodegradation significantly and linearly increased the rate of biodegradation by 2.3 - 8.5 %. The compressive modulus of PVA/HA exhibited a linear reduce to 0.86 - 1.53 MP with the time of degradation. The scaffold composites PVA/HA possess a high porosity, decent compressive modulus and good biodegradability. After further optimizing the structure and properties, this composite might be considered as novel hydrogel biomaterials to be applied in the field of cartilage tissue engineering.

Effect of nanocellulose isolation techniques on the formation of reinforced poly(vinyl alcohol nanocomposite films

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H. Y. Zhan

2012-10-01

Full Text Available Three techniques including acid hydrolysis (AH, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO-mediated oxidation (TMO and ultrasonication (US were introduced to isolate nanocellulose from microcrystalline cellulose, in order to reinforce poly(vinyl alcohol (PVA films. Important differences were noticed in fiber quality of nanocellulose and film properties of PVA nanocomposite films. The TMO treatment was more efficient in nanocellulose isolation with higher aspect ratio, surface charge (–47 mV and yields (37%. While AH treatment resulted in higher crystallinity index (88.1% and better size dispersion. The fracture surface, thermal behavior and mechanical properties of the PVA nanocomposite films were investigated by means of scanning electron microscopy (SEM, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and tensile testing. The results showed that both the TMO-derived and AH-derived nanocellulose could be dispersed homogeneously in the PVA matrices. AH/PVA films had higher elongation at break (51.59% at 6 wt% nanocellulose loading as compared with TMO/PVA, while TMO/PVA films shown superior tensile modulus and strength with increments of 21.5% and 10.2% at 6wt% nanocellulose loading. The thermal behavior of the PVA nanocomposite films was higher improved with TMO-derived nanofibrils addition.

Effects of Two Different Cellulose Nanofiber Types on Properties of Poly(vinyl alcohol Composite Films

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Kitti Yuwawech

2015-01-01

Full Text Available This work concerns a study on the effects of fiber types and content of cellulose nanofiber on mechanical, thermal, and optical properties polyvinyl alcohol (PVA composites. Two different types of cellulose nanofibers, which are nanofibrillated cellulose (NFC and bacterial cellulose (BC, were prepared under various mechanical treatment times and then incorporated into the PVA prior to the fabrication of composite films. It was found that tensile modulus of the PVA film increased with nanofibers content at the expense of its percentage elongation value. DSC thermograms indicate that percentage crystallinity of PVA increased after adding 2–4 wt% of the fibers. This contributed to the better mechanical properties of the composites. Tensile toughness values of the PVA/BC nanocomposite films were also superior to those of the PVA/NFC system containing the same fiber loading. SEM images of the composite films reveal that tensile fractured surface of PVA/BC experienced more ductile deformation than the PVA/NFC analogue. The above discrepancies were discussed in the light of differences between the two types of fibers in terms of diameter and their intrinsic properties. Lastly, percentage total visible light transmittance values of the PVA composite films were greater than 90%, regardless of the fiber type and content.

Colorful and transparent poly(vinyl alcohol) composite films filled with layered zinc hydroxide salts, intercalated with anionic orange azo dyes (methyl orange and orange II)

International Nuclear Information System (INIS)

Neves da Silva, Marlon Luiz; Marangoni, Rafael; Cursino, Ana Cristina Trindade; Schreiner, Wido Herwig; Wypych, Fernando

2012-01-01

Highlights: ► Zinc hydroxide salts were successfully intercalated with anionic orange azo dyes. ► The anionic dye was co-intercalated with hydrated chloride anions. ► The orange materials were used as fillers for poly(vinyl alcohol). ► Transparent, homogeneous, colorful PVA films were obtained by wet casting. ► Some composites stored at lower humidity exhibited improved mechanical properties. - Abstract: Layered zinc hydroxide salts (zinc LHS) were intercalated with anionic orange azo dyes, namely methyl orange (MO) and orange II (OII), and co-intercalated with hydrated chloride anions. After characterization by X-ray diffraction (XRD), thermal analysis (TGA/DTA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), the materials were used as fillers for poly(vinyl alcohol) (PVA). Colorful transparent films were obtained by wet casting, revealing good dispersion of the material into the polymer. In the case of zinc LHS/OII, PVA was intercalated between the zinc LHS layers. Evaluation of the mechanical properties of the PVA composite films revealed that the layered colorful materials were able to increase the mechanical properties of the PVA films only when the films were stored under lower relative humidity. As expected, films with higher water content displayed reduced tensile strength and modulus because of the plasticizing effect of water. As for the films stored at 43% relative humidity, more pronounced improvement of modulus was observed for 1 and 4% zinc LHS/OII, and enhanced tensile strength was achieved for 0.5 and 1% zinc LHS/OII. This effect can be attributed to better dispersion of the layered filler and its better adhesion to the PVA matrix.

Composite poly(vinyl alcohol/poly(vinyl acetate electrospun nanofibrous mats as a novel wound dressing matrix for controlled release of drugs

Directory of Open Access Journals (Sweden)

Jannesari M

2011-05-01

Full Text Available Marziyeh Jannesari1, Jaleh Varshosaz2, Mohammad Morshed1, Maedeh Zamani11Department of Textile Engineering, Isfahan University of Technology, Isfahan, Iran; 2Department of Pharmaceutics, School of Pharmacy and Pharmaceutical Sciences Research Center, Isfahan University of Medical Sciences, Isfahan, IranAbstract: The aim of this study was to develop novel biomedicated nanofiber electrospun mats for controlled drug release, especially drug release directly to an injury site to accelerate wound healing. Nanofibers of poly(vinyl alcohol (PVA, poly(vinyl acetate (PVAc, and a 50:50 composite blend, loaded with ciprofloxacin HCl (CipHCl, were successfully prepared by an electrospinning technique for the first time. The morphology and average diameter of the electrospun nanofibers were investigated by scanning electron microscopy. X-ray diffraction studies indicated an amorphous distribution of the drug inside the nanofiber blend. Introducing the drug into polymeric solutions significantly decreased solution viscosities as well as nanofiber diameter. In vitro drug release evaluations showed that both the kind of polymer and the amount of drug loaded greatly affected the degree of swelling, weight loss, and initial burst and rate of drug release. Blending PVA and PVAc exhibited a useful and convenient method for electrospinning in order to control the rate and period of drug release in wound healing applications. Also, the thickness of the blend nanofiber mats strongly influenced the initial release and rate of drug release.Keywords: biodegradable polymers, drug delivery, controlled release, electrospun nanofibers, wound dressing

Osteochondral defect repair using a polyvinyl alcohol-polyacrylic acid (PVA-PAAc) hydrogel.

Science.gov (United States)

Bichara, David A; Bodugoz-Sentruk, Hatice; Ling, Doris; Malchau, Erik; Bragdon, Charles R; Muratoglu, Orhun K

2014-08-01

Poly(vinyl alcohol) (PVA) hydrogels can be candidates for articular cartilage repair due to their high water content. We synthesized a PVA-poly(acrylic acid) (PAAc) hydrogel formulation and determined its ability to function as a treatment option for condylar osteochondral (OC) defects in a New Zealand white rabbit (NZWR) model for 12 weeks and 24 weeks. In addition to hydrogel OC implants, tensile bar-shaped hydrogels were also implanted subcutaneously to evaluate changes in mechanical properties as a function of in vivo duration. There were no statistically significant differences (p > 0.05) in the water content measured in the OC hydrogel implant that was harvested after 12 weeks and 24 weeks, and non-implanted controls. There were no statistically significant differences (p > 0.05) in the break stress, strain at break or modulus of the tensile bars either between groups. Histological analysis of the OC defect, synovial capsule and fibrous tissue around the tensile bars determined hydrogel biocompatibility. Twelve-week hydrogels were found to be in situ flush with the articular cartilage; meniscal tissue demonstrated an intact surface. Twenty-four week hydrogels protruded from the defect site due to lack of integration with subchondral tissue, causing fibrillation to the meniscal surface. Condylar micro-CT scans ruled out osteolysis and bone cysts of the subchondral bone, and no PVA-PAAc hydrogel contents were found in the synovial fluid. The PVA-PAAc hydrogel was determined to be fully biocompatible, maintained its properties over time, and performed well at the 12 week time point. Physical fixation of the PVA-PAAc hydrogel to the subchondral bone is required to ensure long-term performance of hydrogel plugs for OC defect repair.

Physicochemical properties of manganese oxides obtained via the sol-gel method: The reduction of potassium permanganate by polyvinyl alcohol

Science.gov (United States)

Ivanets, A. I.; Prozorovich, V. G.; Krivoshapkina, E. F.; Kuznetsova, T. F.; Krivoshapkin, P. V.; Katsoshvili, L. L.

2017-08-01

Experimental data on the sol-gel synthesis of manganese oxides formed during the reduction of potassium permanganate by polyvinyl alcohol in an aqueous medium are presented. The physicochemical properties of the obtained manganese oxide systems that depend on the conditions of the synthesis are studied by means of DTA, XRD, SEM, and the low temperature adsorption-desorption of nitrogen. It is found that the obtained samples have a mesoporous structure and predominantly consist of double potassium-manganese oxide K2Mn4O8 with a tunnel structure and impurities of oxides such as α-MnO2, MnO, α-Mn2O3, and Mn5O8. It is shown that the proposed method of synthesis allows us to regulate the size and volume of mesopores and, to a lesser extent, the texture of the obtained oxides, which can be considered promising sorbents for the selective extraction of strontium and cesium ions from multicomponent aqueous solutions.

Influence of absorbed moisture on desizing of poly(vinyl alcohol) on cotton fabrics during atmospheric pressure plasma jet treatment

International Nuclear Information System (INIS)

Peng Shujing; Liu Xiulan; Sun Jie; Gao Zhiqiang; Yao Lan; Qiu Yiping

2010-01-01

This paper studies the influence of moisture absorption of cotton fabrics on the effectiveness of atmospheric pressure plasma jet (APPJ) on desizing of polyvinyl alcohol (PVA). Cotton fabrics with three different moisture regains (MR), namely 1.8%, 7.3%, and 28.4% corresponding to 10%, 65%, and 98% of relative humidity respectively, are treated for 16 s, 32 s, 48 s, and 64 s. X-ray photoelectron spectroscopy analysis indicates that the plasma treated PVA has higher oxygen concentration than the control. Mass loss results show that the fabric with the highest MR has the largest mass loss after 64 s plasma exposure. Solubility measurement reveals that the sample with the lowest MR has the highest desizing efficacy and the percent desizing ratio reaches 96% after 64 s exposure plus a 20 min hot wash, which is shown as clean as the unsized sample through scanning electron microscopy analysis. The yarn tensile strength test results show that APPJ has no negative effect on fabric tensile strength.

Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

Energy Technology Data Exchange (ETDEWEB)

Junaidi, E-mail: junaidi.1982@fmipa.unila.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Department of Physics, Lampung University, Bandar Lampung (Indonesia); Yunus, Muhammad, E-mail: muhammad.yunus@mail.ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Triyana, Kuwat, E-mail: triyana@ugm.ac.id; Harsojo,, E-mail: harsojougm@ugm.ac.id; Suharyadi, Edi, E-mail: esuharyadi@ugm.ac.id [Department of Physics, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia); Nanomaterials Research Group, Universitas Gadjah Mada, Yogyakarta, 55281 (Indonesia)

2016-04-19

We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

2D Ti3C2Tx (MXene)-reinforced polyvinyl alcohol (PVA) nanofibers with enhanced mechanical and electrical properties.

Science.gov (United States)

Sobolčiak, Patrik; Ali, Adnan; Hassan, Mohammad K; Helal, Mohamed I; Tanvir, Aisha; Popelka, Anton; Al-Maadeed, Mariam A; Krupa, Igor; Mahmoud, Khaled A

2017-01-01

Novel 2D Ti3C2Tx (MXene)-reinforced polyvinyl alcohol (PVA) nanofibers have been successfully fabricated by an electrospinning technique. The high aspect ratio, hydrophilic surfaces, and metallic conductivity of delaminated MXene nanosheet render it promising nanofiller for high performance nanocomposites. Cellulose nanocrystals (CNC) were used to improve the mechanical properties of the nanofibers. The obtained electrospun nanofibers had diameter from 174 to 194 nm depending on ratio between PVA, CNC and MXene. Dynamic mechanical analysis demonstrated an increase in the elastic modulus from 392 MPa for neat PVA fibers to 855 MPa for fibers containing CNC and MXene at 25°C. Moreover, PVA nanofibers containing 0.14 wt. % Ti3C2Tx exhibited dc conductivity of 0.8 mS/cm conductivity which is superior compared to similar composites prepared using methods other than electrospinning. Improved mechanical and electrical characteristics of the Ti3C2Tx /CNC/PVA composites make them viable materials for high performance energy applications.

Interpenetrating network hydrogel membranes of sodium alginate and poly(vinyl alcohol) for controlled release of prazosin hydrochloride through skin.

Science.gov (United States)

Kulkarni, Raghavendra V; Sreedhar, V; Mutalik, Srinivas; Setty, C Mallikarjun; Sa, Biswanath

2010-11-01

Interpenetrating network (IPN) hydrogel membranes of sodium alginate (SA) and poly(vinyl alcohol) (PVA) were prepared by solvent casting method for transdermal delivery of an anti-hypertensive drug, prazosin hydrochloride. The prepared membranes were thin, flexible and smooth. The X-ray diffraction studies indicated the amorphous dispersion of drug in the membranes. Differential scanning calorimetric analysis confirmed the IPN formation and suggests that the membrane stiffness increases with increased concentration of glutaraldehyde (GA) in the membranes. All the membranes were permeable to water vapors depending upon the extent of cross-linking. The in vitro drug release study was performed through excised rat abdominal skin; drug release depends on the concentrations of GA in membranes. The IPN membranes extended drug release up to 24 h, while SA and PVA membranes discharged the drug quickly. The primary skin irritation and skin histopathology study indicated that the prepared IPN membranes were less irritant and safe for skin application. Copyright © 2010 Elsevier B.V. All rights reserved.

Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized by polyol method

International Nuclear Information System (INIS)

Junaidi; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

2016-01-01

We report our investigation on the effect of chloride ions oncontrolling the shapes and properties of silver nanorods(AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as asalt precursor and performed at the oilbath temperature of 140 °C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorodswere characterized using UV-VIS, XRD, SEM and TEM. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorodsdecreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

Chloride ion addition for controlling shapes and properties of silver nanorods capped by polyvinyl alcohol synthesized using polyol method

International Nuclear Information System (INIS)

Junaidi; Yunus, Muhammad; Triyana, Kuwat; Harsojo,; Suharyadi, Edi

2016-01-01

We report our investigation on the effect of chloride ions on controlling the shapes and properties of silver nanorods (AgNRs) synthesized using a polyol method. In this study, we used polyvinyl alcohol (PVA) as a capping agent and sodium chloride (NaCl) as a salt precursor and performed at the oil bath temperature of 140°C. The chloride ions originating from the NaCl serve to control the growth of the silver nanorods. Furthermore, the synthesized silver nanorods were characterized using SEM and XRD. The results showed that besides being able to control the growth of AgCl atoms, the chloride ions were also able to control the growth of multi-twinned-particles into the single crystalline of silver nanorods by micrometer-length. At an appropriate concentration of NaCl, the diameter of silver nanorods decreased significantly compared to that of without chloride ion addition. This technique may be useful since a particular diameter of silver nanorods affects a particular application in the future.

2016 Survey of Non-Starch Alcohol and Renewable Hydrocarbon Biofuels Producers

Energy Technology Data Exchange (ETDEWEB)

Warner, Ethan [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schwab, Amy [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bacovsky, Dina [Bioenergy 2020+ GmbH (Germany)

2017-02-01

In order to understand the anticipated status of the industry for non-starch ethanol and renewable hydrocarbon biofuels as of the end of calendar year 2015, the National Renewable Energy Laboratory (NREL) updated its annual survey of U.S. non-starch ethanol and renewable hydrocarbon biofuels producers. This report presents the results of this survey update, describes the survey methodology, and documents important changes since the 2015 survey published at the end of 2015 (Schwab et al. 2015).

Preparation of Poly(Vinyl Alcohol) Grafted With Acrylic Acid/Styrene Binary Monomers For Selective Permeation of Heavy Metals

International Nuclear Information System (INIS)

Hegazy El-Sayed, A.; Abd El-Rehim, H.A.; Ali, A.M.; Aly, H.F.

1999-01-01

A study has been made to modify water-soluble poly(vinyl alcohol) (PVA), by grafting acrylic acid and styrene (AAc/Sty) binary monomers using gamma rays as initiator. The factors that affect the preparation process and grafting yield were studied and more economical grafts under the most favorable reaction conditions were obtained. It was found that the high degree of grafting of such system was obtained in presence of ethanol-water mixture in which water plays a significant role in enhancing the graft copolymerization. The critical amount of water to afford maximum grafting yield has been evaluated. The effect of comonomer composition on the grafting yield was also investigated and it was observed that using a mixture of AAc/Sty monomers influence the extent of grafting of each monomer onto the PVA substrate and the phenomenon of synergism occurs during such reaction. Also, degree of grafting increases as the content of the solvent decreases in the reaction medium. The permeation of heavy metals such as Ni and Co through the grafted membranes was investigated and efficiency of separation process is also determined

Resistance of polyvinyl alcohol blends stabilized by sodium and ammonium salts of lignite humic acids against γ-irradiation

International Nuclear Information System (INIS)

Barbora Bakajova; Jiri Kucerik; Michal Ilcin; Oga Hola

2011-01-01

The dried blends containing sodium and ammonium salts of lignite humic acids (humates, 0.5-10% w/w) in polyvinyl alcohol (PVA) were exposed to high dosage of γ-irradiation in the range of doses 127-806 kGy. Resulted products were then tested for their stability using thermogravimetrical analysis. As a reference the non-treated blends were used since the pure PVA exposed to γ-irradiation very quickly lost its stability and resulting consistence did not allow the stability tests. Stabilities showed a strong concentration and counterion dependency. While sodium counterion caused mostly destabilization with increasing dose, the ammonium counterion acted in an opposite way. The tests carried out in a moisturizing container revealed the changes in water absorbing capacity of irradiated samples and allowed partial explanation of humate stabilizing effect. Generally, at lower concentration of a humate the increase was observed with an increase in the γ-irradiation dose and vice versa. The results confirmed the antioxidant and stabilizing effect of humic acids added to some synthetic polymers and their applicability in materials exposed to γ-irradiation. (author)

Investigation of Zinc Oxide-Loaded Poly(Vinyl Alcohol) Nanocomposite Films in Tailoring Their Structural, Optical and Mechanical Properties

Science.gov (United States)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2018-04-01

Wurtzite ZnO nanoparticles, as a nanofiller, were incorporated in a poly(vinyl alcohol) (PVA) matrix to prepare multipurpose nanocomposite films using a solution casting approach. Some advanced analytical techniques were used to investigate the properties of prepared nanocomposite films. The mediation of ZnO nanofillers resulted in modification of structural, optical and mechanical properties of nanocomposite films. A comprehensive band structure investigation might be useful for designing technological applications like in optoelectronic devices. The experimental results were found to be closely dependent on the nanofiller contents. Some theoretical models like Tauc's and Wemple-DiDomenico, were employed to investigate the band structure parameters. The imaginary part of the dielectric constant was used to investigate the band gap. Then, the Helpin-Tsai model was employed to predict Young's moduli of the prepared nanocomposite films. On 3 wt.% ZnO nanofiller loading, the optical band gap of the PVA-based nanocomposite film was decreased from 5.26 eV to 3 eV, the tensile strength increased from 25.3 MPa to 48 MPa and Young's modulus increased from 144 MPa to 544 MPa.

Preparation and Evaluation of Alcohol-Alkaline-Treated Rice Starch ...

African Journals Online (AJOL)

lower in the presence of large particles (3.55 ± 0.56 min); high content of MRS ... Conclusion: MRS exhibits improved water solubility and swelling capacity compared with RS, and is ..... excipient: Modification of the permeability of starch by.

A new nanocomposite polymer electrolyte based on poly(vinyl alcohol) incorporating hypergrafted nano-silica

KAUST Repository

Hu, Xian-Lei

2012-01-01

Solid-state nanocomposite polymer electrolytes based on poly(vinyl alcohol)(PVA) incorporating hyperbranched poly(amine-ester) (HBPAE) grafted nano-silica (denoted as SiO2-g-HBPAE) have been prepared and investigated. Through surface pretreatment of nanoparticles, followed by Michael-addition and a self-condensation process, hyperbranched poly(amine-ester) was directly polymerized from the surface of nano-silica. Then the hypergrafted nanoparticles were added to PVA matrix, and blended with lithium perchlorate via mold casting method to fabricate nanocomposite polymer electrolytes. By introducing hypergrafted nanoparticles, ionic conductivity of solid composite is improved significantly at the testing temperature. Hypergrafted nano-silica may act as solid plasticizer, promoting lithium salt dissociation in the matrix as well as improving segmental motion of matrix. In addition, tensile testing shows that such materials are soft and tough even at room temperature. From the dielectric spectra of nanocomposite polymer electrolyte as the function of temperature, it can be deduced that Arrhenius behavior appears depending on the content of hypergrafted nano-silica and concentration of lithium perchlorate. At a loading of 15 wt% hypergrafted nano-silica and 54 wt% lithium perchlorate, promising ionic conductivities of PVA nanocomposite polymer electrolyte are achieved, about 1.51 × 10 ^-4 S cm^-1 at 25 °C and 1.36 × 10^-3 S cm^-1 at 100 °C. © The Royal Society of Chemistry.

Shape Memory Composites Based on Electrospun Poly(vinyl alcohol) Fibers and a Thermoplastic Polyether Block Amide Elastomer.

Science.gov (United States)

Shirole, Anuja; Sapkota, Janak; Foster, E Johan; Weder, Christoph

2016-03-01

The present study aimed at developing new thermally responsive shape-memory composites, that were fabricated by compacting mats of electrospun poly(vinyl alcohol) (PVA) fibers and sheets of a thermoplastic polyether block amide elastomer (PEBA). This design was based on the expectation that the combination of the rubber elasticity of the PEBA matrix and the mechanical switching exploitable through the reversible glass transition temperature (Tg) of the PVA filler could be combined to create materials that display shape memory characteristics as an emergent effect. Dynamic mechanical analyses (DMA) show that, upon introduction of 10-20% w/w PVA fibers, the room-temperature storage modulus (E') increased by a factor of 4-5 in comparison to the neat PEBA, and they reveal a stepwise reduction of E' around the Tg of PVA (85 °C). This transition could indeed be utilized to fix a temporary shape and recover the permanent shape. At low strain, the fixity was 66 ± 14% and the recovery was 98 ± 2%. Overall, the data validate a simple and practical strategy for the fabrication of shape memory composites that involves a melt compaction process and employs two commercially available polymers.

Negative pressure wound therapy using polyvinyl alcohol foam to bolster full-thickness mesh skin grafts in dogs.

Science.gov (United States)

Or, Matan; Van Goethem, Bart; Kitshoff, Adriaan; Koenraadt, Annika; Schwarzkopf, Ilona; Bosmans, Tim; de Rooster, Hilde

2017-04-01

To report the use of negative pressure wound therapy (NPWT) with polyvinyl alcohol (PVA) foam to bolster full-thickness mesh skin grafts in dogs. Retrospective case series. Client-owned dogs (n = 8). Full-thickness mesh skin graft was directly covered with PVA foam. NPWT was maintained for 5 days (in 1 or 2 cycles). Grafts were evaluated on days 2, 5, 10, 15, and 30 for graft appearance and graft take, granulation tissue formation, and complications. Firm attachment of the graft to the recipient bed was accomplished in 7 dogs with granulation tissue quickly filling the mesh holes, and graft take considered excellent. One dog had bandage complications after cessation of the NPWT, causing partial graft loss. The PVA foam did not adhere to the graft or damage the surrounding skin. The application of NPWT with a PVA foam after full-thickness mesh skin grafting in dogs provides an effective method for securing skin grafts, with good graft acceptance. PVA foam can be used as a primary dressing for skin grafts, obviating the need for other interposing materials to protect the graft and the surrounding skin. © 2017 The American College of Veterinary Surgeons.

Effect of Single and Double Stage Chemically Treated Kenaf Fibers on Mechanical Properties of Polyvinyl Alcohol Film

Directory of Open Access Journals (Sweden)

Md Ershad Ali

2014-12-01

Full Text Available The physico-mechanical properties of lignocellulosic kenaf fiber reinforced polyvinyl alcohol (PVA biocomposite films were investigated. To improve the properties of the biocomposite, kenaf fibers were chemically treated separately in a single stage (with Cr2(SO4312(H2O and double stages (with CrSO4 and NaHCO3 to improve the adhesion and compatibility between the kenaf fiber and PVA matrix. PVA was reinforced with various compositions of chemically treated kenaf fiber by using a solution casting technique. Microstructural analyses and mechanical tests were subsequently conducted. Scanning electron microscopic analysis indicated that chemical treatment improved the uniformity distribution of kenaf fiber within the PVA matrix. FTIR and XRD analyses confirmed the presence of chromium on the fiber surface. The tensile strength of PVA reinforced with chemical treated kenaf fiber was found to be higher than those reinforced with untreated kenaf. The Young’s modulus, flexural strength, and flexural modulus increased with fiber loading for both untreated and treated kenaf fiber reinforced PVA films. The double stage treated kenaf fiber showed better mechanical properties and lower moisture uptake than the single stage treated kenaf fiber.

Enantioselective resolution of (R,S)-1-phenylethanol catalyzed by lipases immobilized in starch films

International Nuclear Information System (INIS)

Hoffmann, Isabel; Silva, Vanessa D.; Nascimento, Maria da G.

2011-01-01

Lipases from different sources and two mycelium-bound lipases, in a free or immobilized form, in ginger starch film were screened as biocatalysts in the reaction of (R,S)-1-phenylethanol (1) with vinyl acetate and other acylating agents. The effect of various reaction parameters in the resolution of (1) catalyzed by lipase from Burkholderia cepacia (BCL) immobilized in ginger starch film was evaluated (acyl donor type, alcohol:acyl donor molar ratio, temperature and organic solvent). The catalytic efficiency of BCL immobilized in polymeric blends of ginger starch and polyethylene oxide (PEO), in different compositions, was also studied. Vinyl acetate and iso-propenyl acetate furnished the highest conversion (9%) and enantiomeric excess (> 99%) of the (R)-ester. The alcohol:acyl donor molar ratio and temperature optimum were 1:1 and 28 deg respectively. The mixture of n-hexane/glycerol (9:1 v:v) was the most adequate for this reaction (conversion 23%, E > 200). The ginger starch/PEO (7:3 m/m) blend was successfully reused six times consecutively. (author)

Enantioselective resolution of (R,S)-1-phenylethanol catalyzed by lipases immobilized in starch films

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, Isabel; Silva, Vanessa D.; Nascimento, Maria da G., E-mail: graca@qmc.ufsc.b [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Quimica

2011-07-01

Lipases from different sources and two mycelium-bound lipases, in a free or immobilized form, in ginger starch film were screened as biocatalysts in the reaction of (R,S)-1-phenylethanol (1) with vinyl acetate and other acylating agents. The effect of various reaction parameters in the resolution of (1) catalyzed by lipase from Burkholderia cepacia (BCL) immobilized in ginger starch film was evaluated (acyl donor type, alcohol:acyl donor molar ratio, temperature and organic solvent). The catalytic efficiency of BCL immobilized in polymeric blends of ginger starch and polyethylene oxide (PEO), in different compositions, was also studied. Vinyl acetate and iso-propenyl acetate furnished the highest conversion (9%) and enantiomeric excess (> 99%) of the (R)-ester. The alcohol:acyl donor molar ratio and temperature optimum were 1:1 and 28 deg respectively. The mixture of n-hexane/glycerol (9:1 v:v) was the most adequate for this reaction (conversion 23%, E > 200). The ginger starch/PEO (7:3 m/m) blend was successfully reused six times consecutively. (author)

Comparative performance of microbial lipases immobilized on magnetic polysiloxane polyvinyl alcohol particles

Directory of Open Access Journals (Sweden)

Laura Maria Bruno

2008-10-01

Full Text Available Microbial lipase from Mucor miehei and Candida rugosa were immobilized by covalent binding onto magnetized polysiloxane polyvinyl alcohol particles (POS-PVA. The resulting immobilized derivatives were evaluated in aqueous solution (olive oil hydrolysis and organic solvent (butyl butyrate synthesis. Higher catalytic activities were found when the coupling procedure was made with M. miehei lipase. Immobilized M. miehei lipase also showed a better operational stability and a higher half-life than C. rugosa lipase after the successive batches of esterification. The performance of C. rugosa immobilized derivative was constrained by the low lipase loading used in the immobilizing step. Further information regarding the both immobilized derivatives was also obtained through chemical composition (FTIR.Lipases microbianas de Mucor miehei e Candida rugosa foram imobilizadas por ligação covalente em partículas magnetizadas de polisiloxano-álcool polivinílico (POS-PVA. Os derivados imobilizados resultantes foram avaliados em solução aquosa (hidrólise de azeite de oliva e em solvente orgânico (síntese de butirato de butila. As maiores atividades catalíticas foram encontradas quando o procedimento de ligação foi realizado com lipase de M. miehei. O derivado imobilizado de lipase de M. miehei também apresentou melhores resultados de estabilidade operacional e tempo de meia-vida do que o de lipase de C. rugosa, após sucessivas bateladas de esterificação. O desempenho do derivado imobilizado de C. rugosa foi restringido pelo baixo carregamento de lipase usado na etapa de imobilização. Informações adicionais a respeito de ambos derivados imobilizados também foram obtidas através da composição química (FTIR.

Porous poly(vinyl alcohol)/sepiolite bone scaffolds: Preparation, structure and mechanical properties

International Nuclear Information System (INIS)

Killeen, Derek; Frydrych, Martin; Chen Biqiong

2012-01-01

Porous poly(vinyl alcohol) (PVA)/sepiolite nanocomposite scaffolds containing 0–10 wt.% sepiolite were prepared by freeze-drying and thermally crosslinked with poly(arylic acid). The microstructure of the obtained scaffolds was characterised by scanning electron microscopy and micro-computed tomography, which showed a ribbon and ladder like interconnected structure. The incorporation of sepiolite increased the mean pore size and porosity of the PVA scaffold as well as the degree of anisotropy due to its fibrous structure. The tensile strength, modulus and energy at break of the PVA solid material that constructed the scaffold were found to improve with additions of sepiolite by up to 104%, 331% and 22% for 6 wt.% clay. Such enhancements were attributed to the strong interactions between the PVA and sepiolite, the good dispersion of sepiolite nanofibres in the matrix and the intrinsic properties of the nanofibres. However, the tensile properties of the PVA scaffold deteriorated in the presence of sepiolite because of the higher porosity, pore size and degree of anisotropy. The PVA/sepiolite nanocomposite scaffold containing 6 wt.% sepiolite was characterised by an interconnected structure, a porosity of 89.5% and a mean pore size of 79 μm and exhibited a tensile strength of 0.44 MPa and modulus of 14.9 MPa, which demonstrates potential for this type of materials to be further developed as bone scaffolds. - Highlights: ► Novel PAA-crosslinked PVA/sepiolite nanocomposite scaffolds were prepared. ► They were highly porous with interconnected structures and exhibited good mechanical properties. ► The effects of sepiolite nanofibres on structure and properties of the scaffolds were investigated. ► Sepiolite nanofibres improved the mechanical properties of the solid material significantly.

Improving surface wettability and lubrication of polyetheretherketone (PEEK) by combining with polyvinyl alcohol (PVA) hydrogel.

Science.gov (United States)

Zhao, Xiaoduo; Xiong, Dangsheng; Liu, Yuntong

2018-06-01

Poor surface wettability and relative high friction coefficients of pristine polyetheretherketone (PEEK) have limited its application in orthopedic implants. In this study, inspired by the structure of natural articular cartilage, we presented a novel method to fabricate a "soft-on-hard" structure on the surface of pristine PEEK specimens, which combined a soft polyvinyl alcohol (PVA) hydrogel layer and a three-dimensional porous layer with PEEK substrates. A variety of analytical methods were used to evaluate their properties, our results demonstrated that the hydrogel layer could be seamlessly connected with substrate, and the hydrogel-covered PEEK owned a highly hydrophilic surface, a very low water contact angle of 7° could be obtained. The friction coefficients of untreated and hydrogel-covered PEEK surfaces were measured using a tribometer under water lubrication, due to the presence of the top hydrogel layer and the hard substrate could provide excellent aqueous lubrication and bearing capacity, respectively, the friction coefficient could be reduced from 0.292 to 0.021. In addition, the porous layer under PVA hydrogel layer could work as gel reservoirs, the reserved hydrogel would be released after the surface layer was sheared off, and a regenerable lubrication status was obtained. This work provides a new route for the design of improving the surface wettability and tribological properties of PEEK. Copyright © 2018 Elsevier Ltd. All rights reserved.

Enhancement of the photoluminescence in CdSe quantum dot–polyvinyl alcohol composite by light irradiation

Energy Technology Data Exchange (ETDEWEB)

Borkovska, L., E-mail: bork@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, pr. Nauky 41, 03028 Kyiv (Ukraine); Korsunska, N.; Stara, T.; Gudymenko, O.; Venger, Ye. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, pr. Nauky 41, 03028 Kyiv (Ukraine); Stroyuk, O.; Raevska, O. [L. Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, pr. Nauky 31, 03028 Kyiv (Ukraine); Kryshtab, T., E-mail: kryshtab@gmail.com [Instituto Politécnico Nacional – ESFM, Av. IPN, Ed.9 U.P.A.L.M., 07738 Mexico D.F. (Mexico)

2013-09-15

The effect of photo-induced enhancement (more than a tenfold) of room temperature deep-trap photoluminescence (PL) in CdSe quantum dots (QDs) embedded in polyvinyl alcohol (PVA) film has been found and investigated by the PL and X-ray diffraction methods. The effect is observed under illumination of the QD/PVA composite with LED's light of 409 or 470 nm at elevated temperatures and is shown to be caused by an increase of the activation energy of thermal quenching of defect-related PL. It is shown that thermal annealing of the composite by itself stimulates polymer crystallization and produces a small increase in the intensity of both the band-edge and defect-related PL bands of CdSe QDs. It is found that the effect of illumination decreases when the annealing temperature increases from 90 °C to 120 °C because thermal annealing at 120 °C per se results in strong enhancement of room temperature deep-trap PL. The effect of photo-induced enhancement of defect-related PL is found to be irreversible and is assumed to be related to the change of QD surface defect passivation or surface defect rearrangement. This is ascribed to partial destruction of PVA matrix as a result of interaction of QD/PVA interface with photocarriers generated in the QDs due to LED's light absorption.

Vitamin C and Poly(ethylene glycol) Protect Concentrated Poly(vinyl alcohol) Solutions against Radiation Cross-linking

International Nuclear Information System (INIS)

Oral, E.

2006-01-01

There is a need for an injectable material to augment damaged cartilage. We propose to make such self-associating poly(vinyl alcohol) (PVA) hydrogels. Physical associations can be formed in PVA using a gellant such as polyethylene glycol (PEG). The injectability of PVA solutions is compromised when sterilized due to chemical cross-linking. We hypothesized that an anticross-linking agent could prevent cross-linking of irradiated PVA solutions. PVA (17.5 wt/v %, MW= 115,000 g/mol) was prepared in water at 90 degree. PEG (MW=400 g/mol) was added at a ratio of PEG unit to PVA unit of 17, 86, 290, and 639 mol/mol. PVA solutions (17.5 wt/v %, MW= 16,000, 61,000, 81,000 and 115,000 g/mol) were also prepared. Vitamin C was added at a molar ratio of vitamin C to PVA unit of 0.75-10.4. Solutions were poured into syringes and γ-irradiated. The viscosity of injectable solutions was determined by using the bubble tube. Gel content of cross-linked samples was measured by boiling gels in water for 6 hours, drying at 90 degree and calculating the ratio of dry weight to 'as is' weight

A novel crosslinking strategy for preparing poly(vinyl alcohol)-based proton-conducting membranes with high sulfonation

Energy Technology Data Exchange (ETDEWEB)

Tsai, Chun-En [Nanoelectrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106 (China); Lin, Chi-Wen [Department of Chemical Engineering, National Yunlin University of Science and Technology, Yunlin (China); Hwang, Bing-Joe [Nanoelectrochemistry Laboratory, Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106 (China); National Synchrotron Radiation Research Center, Hsinchu 300 (China)

2010-04-15

This study synthesizes poly(vinyl alcohol) (PVA)-based polymer electrolyte membranes by a two-step crosslinking process involving esterization and acetal ring formation reactions. This work also uses sulfosuccinic acid (SSA) as the first crosslinking agent to form an inter-crosslinked structure and a promoting sulfonating agent. Glutaraldehyde (GA) as the second crosslinking agent, reacts with the spare OH group of PVA and forms, not only a dense structure at the outer membrane surface, but also a hydrophobic protective layer. Compared with membranes prepared by a traditional one-step crosslinking process, membranes prepared by the two-step crosslinking process exhibit excellent dissolution resistance in water. The membranes become water-insoluble even at a molar ratio of SO{sub 3}H/PVA-OH as high as 0.45. Moreover, the synthesized membranes also exhibit high proton conductivities and high methanol permeability resistance. The current study measures highest proton conductivity of 5.3 x 10{sup -2} S cm{sup -1} at room temperature from one of the synthesized membranes, higher than that of the Nafion {sup registered} membrane. Methanol permeability of the synthesized membranes measures about 1 x 10{sup -7} cm{sup 2} S{sup -1}, about one order of magnitude lower than that of the Nafion {sup registered} membrane. (author)

Interaction of aluminum oxide nanoparticles with flow of polyvinyl alcohol solutions base nanofluids over a wedge

Science.gov (United States)

Hassan, Mohsan; Faisal, Abrar; Bhatti, Muhammad Mubashir

2018-02-01

Polyvinyl alcohol (PVA) is an important industrial chemical, which is used in numerous chemical engineering applications. It is important to study and predict the flow behavior of PVA solutions and the role of nanoparticles in heat transfer applications to be used in chemical processes on industrial scale. Therefore, the present study deals with the PVA solution-based non-Newtonian Al2O3-nanofluid flow along with heat transfer over wedge. The power-law model is used for this non-Newtonian nanofluid which exhibited shear-thinning behavior. The influences of PVA and nanoparticles concentrations on the characteristics of velocity and temperature profiles are examined graphically. The impacts of these parameters on wall shear stress and convective heat transfer coefficient are also studied through tabular form. During the numerical computations, the impacts of these parameters on flow index and consistency index along with other physical properties of nanofluid are also considered. In this study, we found an improvement in heat transfer and temperature profile of fluid by distribution of Al2O3 nanoparticles. It is also noticed that resistance between adjacent layers of moving fluid is enhanced due to these nanoparticles which leads to decline in velocity profile and increases in shear stress at wall.

Influence of the covalent immobilization of graphene oxide in poly(vinyl alcohol) on human osteoblast response.

Science.gov (United States)

Linares, Javier; Matesanz, María Concepción; Feito, María José; Salavagione, Horacio Javier; Martínez, Gerardo; Gómez-Fatou, Marián; Portolés, María Teresa

2016-02-01

The differences in the response of human Saos-2 osteoblasts to nanocomposites of poly(vinyl alcohol) (PVA) and 1.5wt.% graphene oxide (GO) prepared by covalent linking (PVA/GO-c) and simple blending (PVA/GO-m) have been evaluated through different biocompatibility parameters. The effects produced on osteoblasts by these two nanocomposites were analysed in parallel and compared with the direct action of GO and with the effect of PVA films without GO. The intracellular content of reactive oxygen species (ROS) and the levels of interleukin-6 (IL-6) were measured to evaluate oxidative stress induction and protective response, respectively. The results demonstrate that the combination of GO with PVA reduces both the proliferation delay and the internal cell complexity alterations induced by GO on human osteoblasts. Moreover, the covalent attachment of GO to the PVA chains increases both cell viability and IL-6 levels, reducing both apoptosis and intracellular ROS content when compared to simple blending of both materials. The use of this strategy to modulate the biointerface reduces the toxic effects of graphene while preserving the reinforcement characteristics for application in tissue engineering scaffolds, and has enormous interest for polymer/graphene biomaterials development. Copyright © 2015 Elsevier B.V. All rights reserved.

Thrombospondin 2-null mice display an altered brain foreign body response to polyvinyl alcohol sponge implants

International Nuclear Information System (INIS)

Tian Weiming; Kyriakides, Themis R

2009-01-01

Thrombospondin (TSP)-2 is a matricellular protein that participates in the processes of tissue repair and the foreign body response. In addition, TSP2 has been shown to influence synaptogenesis and recovery of the brain following stroke. In the present study we investigated the response following the implantation of polyvinyl alcohol (PVA) sponges in the brain. PVA sponges were implanted into the brain cortex of wild type and TSP2-null mice for a period of 4 and 8 weeks and the response was analyzed by histochemistry and quantitative immunohistochemistry. TSP2 expression was detected in the interstices of the sponge and co-localized with the extracellular matrix and astrocytes. PVA sponge invasion in TSP2-null mice was characterized by dense deposition of extracellular matrix and increased invasion of reactive astrocytes and macrophages/microglia. Furthermore, the angiogenic response was elevated and the detection of mouse serum albumin (MSA) in the brain cortex indicated excessive vessel leakage, suggesting that TSP2 plays a role in the repair/maintenance of the blood brain barrier. Finally, immunostaining demonstrated an increase in the levels of matrix metalloproteinase (MMP)-2 and MMP-9. Taken together, our observations support a role for TSP2 as critical determinant of the brain response to biomaterials.

Preparation, characterization, and application of poly(vinyl alcohol)-graft-poly(ethylene glycol) resins: novel polymer matrices for solid-phase synthesis.

Science.gov (United States)

Luo, Juntao; Pardin, Christophe; Zhu, X X; Lubell, William D

2007-01-01

Spherical crosslinked poly(vinyl alcohol) (PVA) beads with good mechanical stability were prepared by reverse-suspension polymerization, using dimethyl sulfoxide (DMSO) as a cosolvent in an aqueous phase. Poly(ethylene glycol)s with varying chain lengths were grafted onto the PVA beads by anionic polymerization of ethylene oxide. The thermal behavior, morphology, and swelling were evaluated for each of the new polymer matrices. High loading and good swelling in water and organic solvents were characteristic of the PEG-grafted PVA beads. The polymer beads also exhibited good mechanical and chemical stability and were unaffected by treatment with 6 N HCl and with 6 N NaOH. The hydroxyl groups of the PVA-PEG beads were converted into aldehyde, carboxylic acid, and isocyanate functions to provide scavenger resins and were extended by way of a benzyl alcohol in a Wang linker. The transglutaminase substrates dipeptides (Z-Gln-Gly) and heptapeptides (Pro-Asn-Pro-Gln-Leu-Pro-Phe) were synthesized on PVA-PEG_5, PVA-PEG_20, and the Wang linker-derivatized PVA-PEG resins. The cleavage of the peptides from the resins using MeOH/NH3 mixture at different temperatures (0 degrees C and room temp) and 50% TFA/DCM provided, respectively, peptide methyl esters, amides, and acids in good yields and purity as assessed by LC-MS analysis.

Rubber-like poly(vinyl alcohol) gel

Energy Technology Data Exchange (ETDEWEB)

Nambu, Masao (Nippon Oil Co. Ltd., Yokohama (Japan). Central Technical Research Lab.)

1990-09-01

Anomalous poly (vinyl alcohol) gel has been found in our laboratory since 1980. The gel is prepared by repeated freezing (or freeze-dehydration) of aqueous poly (vinyl alcohol). Experiments establish the fact that anomalous gel is never produced in the course of freezing, but during sustained thawing the gelation does occur. Moreover, it was found that the softening point of the gel increases at 37degC. It is assumed that crystal nuclei are generated on freezing, then on thawing, some of them grow to very fine crystals which act as polymer network-knots (cross-linking). Additional freezing provide other seeds, which grow similarly, and these are accumulated until rubber-like gel is produced. The gel was always water-resistant at 37degC, and the potassium permanganate consumption of the extracted water layer remained far below the official restricted value for medical materials. The gel can be sterilized with gamma-rays or chlorhexidine. Moreover, it satisfies the official standards of acute toxicity, pyrogen, intracutaneous reaction, hemolyzation, and intracorporeal implantation, respectively. Applications to adhesion-preventing membrane (for joint or pericardium), tamponade (for jaw defects), electrode (for electroretinogram or artificial inner ear), artificial denture base and phantoms for magnetic resonance imaging were examined. (author) 54 refs.

Effect of electron beam irradiation on the structural properties of poly(vinyl alcohol) formulations with triphenyl tetrazolium chloride dye (TTC)

Science.gov (United States)

Ali, Z. I.; Said, Hossam M.; Ali, H. E.

2006-01-01

Films of poly(vinyl alcohol) (PVA) composites with triphenyl tetrazolium chloride (TTC) dye were prepared and exposed to various radiation doses delivered by accelerated electrons. The results showed that at a low dose of 50 kGy, the colour difference (Δ E*) of PVA/TTC films was increased by ˜10 times of the initial value. However, the change in colour differences did not go systematically with increasing the TTC content, in which the composite with 1.5 wt% displayed higher value than that with 3.5 wt%. The differential scanning calorimetry (DSC) showed that the presence of the TTC dye caused a depression in the melting point ( Tm) and heat of fusion (Δ Hf) of the PVA bulk polymer. However, the thermogravimetric analysis (TGA) showed that the presence of the TTC dye improved the thermal stability of PVA. Also, the tensile strength at break of PVA/TTC composites was improved after electron beam irradiation.

Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities

KAUST Repository

Hoskins, Daniel L.

2014-11-01

© 2014 Elsevier Ltd. Separators are used to protect cathodes from biofouling and to avoid electrode short-circuiting, but they can adversely affect microbial fuel cell (MFC) performance. A spray method was used to apply a polyvinyl alcohol (PVA) separator to the cathode. Power densities were unaffected by the PVA separator (339 ± 29 mW/m2), compared to a control lacking a separator in a low conductivity solution (1mS/cm) similar to wastewater. Power was reduced with separators in solutions typical of laboratory tests (7-13 mS/cm), compared to separatorless controls. The PVA separator produced more power in a separator assembly (SEA) configuration (444 ± 8 mW/m2) in the 1mS/cm solution, but power was reduced if a PVA or wipe separator was used in higher conductivity solutions with either Pt or activated carbon catalysts. Spray and cast PVA separators performed similarly, but the spray method is preferred as it was easier to apply and use.

Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

Energy Technology Data Exchange (ETDEWEB)

Lisnevskaya, I.V.; Bobrova, I.A.; Lupeiko, T.G.

2016-01-01

This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ}), yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}), lanthanum-containing manganites (M{sub x}La{sub 1−x}MnO{sub 3} (M=Pb, Ba or Sr; x=0.3−0.35)), and multiferroics (BiFeO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures (100 and 250 °C, respectively) which are 200–300 °C lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y{sub 3}Fe{sub 5}O{sub 12}, M{sub x}La{sub 1−x}MnO{sub 3} and BiFe{sub 0.5}Mn{sub 0.5}O{sub 3}, the presence of NH{sub 4}NO{sub 3} favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20–50 nm. - Highlights: • This review summarizes results on the synthesis of the magnetic materials and multiferroics. • Ammonium nitrate accelerates destruction of organic components of xerogels. • Ni{sub 0.9}Co{sub 0.1}Cu{sub 0.1}Fe{sub 1.9}O{sub 4−δ} and BiFeO{sub 3} can be prepared at record low temperatures. • Developed methods provide nanoscale magnetic and multiferroic materials.

Topological insulator: Bi{sub 2}Se{sub 3}/polyvinyl alcohol film-assisted multi-wavelength ultrafast erbium-doped fiber laser

Energy Technology Data Exchange (ETDEWEB)

Guo, Bo; Yao, Yong, E-mail: yaoyong@hit.edu.cn; Yang, Yan-Fu; Yuan, Yi-Jun; Wang, Rui-Lai [Department of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Wang, Shu-Guang; Ren, Zhong-Hua [Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Yan, Bo [College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052 (China)

2015-02-14

We experimentally demonstrate a multi-wavelength ultrafast erbium-doped fiber laser incorporating a μm-scale topological insulator: Bi{sub 2}Se{sub 3}/Polyvinyl Alcohol film as both an excellent saturable absorber for mode-locking and a high-nonlinear medium to induce a giant third order optical nonlinear effect for mitigating the mode competition of erbium-doped fiber laser and stabilizing the multi-wavelength oscillation. By properly adjusting the pump power and the polarization state, the single-, dual-, triple-, four-wavelength mode-locking pulse could be stably initiated. For the four-wavelength operation, we obtain its pulse width of ∼22 ps and a fundamental repetition rate of 8.83 MHz. The fiber laser exhibits the maximum output power of 9.7 mW with the pulse energy of 1.1 nJ and peak power of 50 W at the pump power of 155 mW. Our study shows that the simple, stable, low-cost multi-wavelength ultrafast fiber laser could be applied in various potential fields, such as optical communication, biomedical research, and radar system.

Luminescence properties of Sm, Tb(Sal){sub 3}Phen complex in polyvinyl alcohol: an approach for white-light emission

Energy Technology Data Exchange (ETDEWEB)

Kaur, Gagandeep; Rai, S B, E-mail: sbrai49@yahoo.co.in [Laser and Spectroscopy Laboratory, Department of Physics Banaras Hindu University, Varanasi, 221005 (India)

2011-10-26

Polyvinyl alcohol polymer films doped with Sm,Tb(Sal){sub 3}Phen complexes have been synthesized using solution casting technique. An enhancement in absorption intensity is observed revealing the encapsulation of rare earth ions by salicylic acid (Sal)/1,10 phenanthroline (Phen) complex. Photoluminescence spectra of the co-doped samples were examined by varying the concentration of Tb{sup 3+} keeping concentration of Sm{sup 3+} ions fixed and vice-versa. It is found that the polymer samples emit a combination of blue, green and orange-red wavelengths tunable to white light when excited with 355 nm radiation. The emission spectra also show a self-quenching effect at higher concentration of Sm{sup 3+} ions. An efficient energy transfer was observed from Tb{sup 3+} : {sup 5}D{sub 4} {yields} Sm{sup 3+} : {sup 4}G{sub 9/2}. The reason for the enhancement in fluorescence intensities of Sm{sup 3+} in the co-doped polymer sample is the intermolecular as well as the intramolecular energy transfer.

Effects of Low Volume Fraction of Polyvinyl Alcohol Fibers on the Mechanical Properties of Oil Palm Shell Lightweight Concrete

Directory of Open Access Journals (Sweden)

Ming Kun Yew

2015-01-01

Full Text Available This paper presents the effects of low volume fraction (Vf of polyvinyl alcohol (PVA fibers on the mechanical properties of oil palm shell (OPS high strength lightweight concrete mixtures. The slump, density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity under various curing conditions have been measured and evaluated. The results indicate that an increase in PVA fibers decreases the workability of the concrete and decreases the density slightly. The 28-day compressive strength of oil palm shell fiber-reinforced concrete (OPSFRC high strength lightweight concrete (HSLWC subject to continuous moist curing was within the range of 43–49 MPa. The average modulus of elasticity (E value is found to be 16.1 GPa for all mixes, which is higher than that reported in previous studies and is within the range of normal weight concrete. Hence, the findings of this study revealed that the PVA fibers can be used as an alternative material to enhance the properties of OPS HSLWC for building and construction applications.

In situ synthesis of bilayered gradient poly(vinyl alcohol)/hydroxyapatite composite hydrogel by directional freezing-thawing and electrophoresis method.

Science.gov (United States)

Su, Cui; Su, Yunlan; Li, Zhiyong; Haq, Muhammad Abdul; Zhou, Yong; Wang, Dujin

2017-08-01

Bilayered poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogels with anisotropic and gradient mechanical properties were prepared by the combination of directional freezing-thawing (DFT) and electrophoresis method. Firstly, PVA hydrogels with aligned channel structure were prepared by the DFT method. Then, HA nanoparticles were in situ synthesized within the PVA hydrogels via electrophoresis. By controlling the time of the electrophoresis process, a bilayered gradient hydrogel containing HA particles in only half of the gel region was obtained. The PVA/HA composite hydrogel exhibited gradient mechanical strength depending on the distance to the cathode. The gradient initial tensile modulus ranging from 0.18MPa to 0.27MPa and the gradient initial compressive modulus from 0.33MPa to 0.51MPa were achieved. The binding strength of the two regions was relatively high and no apparent internal stress or defect was observed at the boundary. The two regions of the bilayered hydrogel also showed different osteoblast cell adhesion properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Electron beam chemistry in solid films of poly(vinyl alcohol): Exposures under vacuum and under N2 at atmospheric pressure; irradiation monitored by using infrared spectroscopy

International Nuclear Information System (INIS)

Pacansky, J.; Schneider, S.

1990-01-01

Thin films of poly(vinyl alcohol) (PVA) were exposed to a 25-kV electron beam under high vacuum conditions and to a 175-kV electron beam at atmospheric pressures of N 2 . The decomposition of PVA by the electron beam sequentially formed materials that had polyketone- and polyethylene-like structures, respectively. Contrary to previous reports we show that the ketone groups formed as a result of the electron beam exposure are not due to an oxidation step by molecular oxygen. Damage cross sections for the electron beam decomposition (at 25 kV) were determined for PVA and the polyketone, and G values were determined for decomposition of -OH groups and formation of ketone functional groups

Inhibition of nucleation and growth of ice by poly(vinyl alcohol) in vitrification solution.

Science.gov (United States)

Wang, Hai-Yan; Inada, Takaaki; Funakoshi, Kunio; Lu, Shu-Shen

2009-08-01

Control of ice formation is crucial in cryopreservation of biological substances. Successful vitrification using several additives that inhibit ice nucleation in vitrification solutions has previously been reported. Among these additives, here we focused on a synthetic polymer, poly(vinyl alcohol) (PVA), and investigated the effects of PVA on nucleation and growth of ice in 35% (w/w) aqueous 1,2-propanediol solution by using a differential scanning calorimetry (DSC) system equipped with a cryomicroscope. First, the freezing temperature of the solution was measured using the DSC system, and then the change in ice fraction in the solution during cooling was evaluated based on images obtained using the cryomicroscope, at different concentrations of PVA between 0% and 3% (w/w). Based on the ice fraction, the change in residual solution concentration during cooling was also evaluated and then plotted on the state diagram of aqueous 1,2-propanediol solution. Results indicated that, when the partially glassy and partially frozen state was intentionally allowed, the addition of PVA effectively inhibited not only ice nucleation but also ice growth in the vitrification solution. The effect of PVA on ice growth in the vitrification solution was explained based on kinetic limitations mainly due to mass transport. The interfacial kinetics also might limit ice growth in the vitrification solution only when the ice growth rate decreased below a critical value. This coincides with the fact that PVA exhibits a unique antifreeze activity in the same manner as antifreeze proteins when ice growth rate is lower than a critical value.

Mechanical, Thermal, and Morphological Properties of Nanocomposites Based on Polyvinyl Alcohol and Cellulose Nanofiber from Aloe vera Rind

Directory of Open Access Journals (Sweden)

Adel Ramezani Kakroodi

2014-01-01

Full Text Available This work was devoted to reinforcement of polyvinyl alcohol (PVA using cellulose nanofibers from Aloe vera rind. Nanofibers were isolated from Aloe vera rind in the form of an aqueous suspension using chemimechanical technique. Mechanical characterizations showed that incorporation of even small amounts of nanofibers (as low as 2% by weight had significant effects on both the modulus and strength of PVA. Tensile modulus and strength of PVA increased, 32 and 63%, respectively, after adding 2% of cellulose nanofiber from Aloe vera rind. Samples with higher concentrations of nanofibers also showed improved mechanical properties due to a high level of interfacial adhesion and also dispersion of fibers. The results showed that inclusion of nanofibers decreased deformability of PVA significantly. Dynamic mechanical analysis revealed that, at elevated temperatures, improvement of mechanical properties due to the presence of nanofibers was even more noticeable. Addition of nanofibers resulted in increased thermal stability of PVA in thermogravimetric analysis due to the reduction in mobility of matrix molecules. Morphological observations showed no signs of agglomeration of fibers even in composites with high cellulose nanofiber contents. Inclusion of nanofibers was shown to increase the density of composites.

Polyaniline - Carrageenan - Polyvinyl Alcohol Composite Material Synthesized Via Interfacial Polymerization, its Morphological Characteristics and Enhanced Solubility in Water

Science.gov (United States)

Montalbo, R. C. K.; Marquez, M. C.

2017-09-01

In recent years, conducting polyaniline (PAni) has been a popular interest of research in the field of conducting polymers due to its relatively low cost, ease of production, good conductivity, and environmental stability. Many studies however, have focused on improving its short-comings such as its limited processability and solubility in common solvents. In this study, PAni, soluble in water was produced via interfacial polymerization with chloroform as the organic solvent. Poly(vinyl alcohol) (PVA) and kappa(κ), iota(ι) and lambda(λ) - carrageenan (κCGN, ιCGN, λCGN) were added to the aqueous layer to stabilize PAni in the medium. FTIR and UV-Vis absorption spectra of the solutions as well as the fabricated film confirmed the existence of PAni emeraldine salt (PAni-ES). FTIR spectrum also confirmed the peaks corresponding to the interaction of PAni with the CGNs. Moreover, PVA-CGN played a very large role on the stability of the PAni nanofibers integrated on the PVA-CGN matrix. The morphologies of the products were further investigated using SEM and TEM. Polymer electrolyte for supercapacitor or an interfacial layer for organic solar cell is being targeted as potential application of the synthesized water soluble PAni.

One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications

Directory of Open Access Journals (Sweden)

Rui Cai

2017-04-01

Full Text Available Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs modified on polydopamine-coated sericin/polyvinyl alcohol (PVA composite films was developed. Polydopamine (PDA acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine.

Crosslinked poly(vinyl alcohol)/sulfonated poly(ether ether ketone) blend membranes for fuel cell applications - Surface energy characteristics and proton conductivity

Energy Technology Data Exchange (ETDEWEB)

Kanakasabai, P.; Vijay, P.; Deshpande, Abhijit P.; Varughese, Susy [Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India)

2011-02-01

Ionic polymers, their blends and composites are considered potential candidates for application as electrolytes in fuel cells. While developing new materials for membranes, it is important to understand the interactions of these electrolytic materials with electrodes/catalysts and with reactants/products. Some of these interactions can be understood by estimating the surface energy and wettability of the membrane materials. In this work, polyvinyl alcohol with varying degrees of sulfonation and its blend with sulfonated poly(ether ether ketone) are prepared and studied for their wettability characteristics using goniometry. The surface energy and its components are estimated using different approaches and compared. Properties such as the ion-exchange capacity, the proton conductivity and the water sorption/desorption behaviour are also investigated to understand the relationship with wettability and surface energy and its components. Among the different methods, the van Oss acid-base and the modified Berthelot approaches yield comparable estimates for the total surface energy. (author)

Properties of iopamidol-incorporated poly(vinyl alcohol) microparticle as an X-ray imaging flow tracer.

Science.gov (United States)

Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Lee, Sang Joon

2011-02-10

We have recently reported on poly(vinyl alcohol) microparticles containing X-ray contrast agent, iopamidol, designed as a flow tracer working in synchrotron X-ray imaging ( Biosens. Bioelectron. 2010 , 25 , 1571 ). Although iopamidol is physically encapsulated in the microparticles, it displays a great contrast enhancement and stable feasibility in in vitro human blood pool. Nonetheless, a direct relation between the absolute amount of incorporated iopamidol and the enhancement in imaging efficiency was not observed. In this study, physical properties of the designed microparticle are systematically investigated experimentally with theoretical interpretation to correlate an enhancement in X-ray imaging efficiency. The compositional ratio of X-ray contrast agent in polymeric microparticle is controlled as 1/1 and 10/1 [contrast agent/polymer microparticle (w/w)] with changed degree of cross-linkings. Flory-Huggins interaction parameter (χ), retractive force (τ) and degree of swelling of the designed polymeric microparticles are investigated. In addition, the hydrodynamic size (D(H)) and ζ-potential are evaluated in terms of environment responsiveness. The physical properties of the designed flow tracer microparticles under a given condition are observed to be strongly related with the X-ray absorption efficiency, which are also supported by the Beer-Lambert-Bouguer law. The designed microparticles are almost nontoxic with a reasonable concentration and time period, enough to be utilized as a flow tracer in various biomedical applications. This study would contribute to the basic understanding on the physical property connected with the imaging efficiency of contrast agents.

Effect of gamma irradiation on biopolymer composite films of poly(vinyl alcohol) and bacterial cellulose

Energy Technology Data Exchange (ETDEWEB)

Jipa, Iuliana Mihaela; Stroescu, Marta [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Stoica-Guzun, Anicuta, E-mail: stoica.anicuta@gmail.com [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Dobre, Tanase; Jinga, Sorin [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Zaharescu, Traian [Advanced Research Institute for Electrical Engineering, 313 Splaiul Unirii, 030138 Bucharest (Romania)

2012-05-01

Highlights: Black-Right-Pointing-Pointer The paper reports the obtaining of composite materials between PVA and BC. Black-Right-Pointing-Pointer The composite films were {gamma}-irradiated at doses up to 50 kGy. Black-Right-Pointing-Pointer The films have a good resistance, being suitable as food packaging materials. - Abstract: Composite materials containing in different ratios poly(vinyl alcohol) (PVA), bacterial cellulose (BC) and glycerol (G) as plasticizer were obtained and exposed to different {gamma} radiation doses using an irradiator GAMMATOR provided with {sup 137}Cs source. These films successively received up to 50 kGy absorbed doses at a dose rate of 0.4 kGy/h at room temperature. In order to study the chemical and structural changes during {gamma} irradiation, Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and UV-Vis spectroscopy were used. Water vapour permeability (WVP), Hunter colour parameters and hardness were also measured for the irradiated samples. Investigation revealed that WVP was not significantly affected by the irradiation. Colour measurements indicated a slight decrease of pure PVA films transparency and it made clear that all samples became more reddish and yellowish after irradiation. The samples hardness was not affected by the irradiation doses used. However, the results showed no drastic structural or chemical changes of the irradiated samples, which prove, in consequence, a good durability. These composite materials could be used as packaging materials for {gamma} irradiated products.

Extraction of microcrystalline cellulose from rice straw and its effect on polyvinyl alcohol biocomposites film

Science.gov (United States)

Chin, Kwok-Mern; Ting, Sam Sung; Lin, Ong Hui; Owi, Wei Tieng

2017-07-01

The poor management and underutilization of agricultural wastes had proliferated interest of researchers around the world to find alternatives to utilize them as potential value-added products. One of the green alternatives is by extracting cellulose from these waste materials and incorporating them in polymer as reinforcement fillers. The surging amount of plastic waste also posed major issues to the environment due to its recalcitrance to degrade. Microcrystalline cellulose (MCC-RS) was extracted from rice straw through cyclic alkaline and bleaching treatment to remove hemicellulose and lignin respectively. Polyvinyl alcohol (PVOH) was chosen as the matrix and different ratios of PVOH / MCC-RS films were prepared (2.5, 5.0, 7.5 and 10.0wt% of MCC) through solution casting method and its tensile, thermal and morphological properties were studied. X-ray powder diffraction (XRD) results showed increased crystallinity of MCC-RS after chemical treatment (from 44.5% to 60.8%) due to the successful removal of lignin and hemicellulose, which was then confirmed with Fourier transform infrared spectroscopy (FTIR) results. For the biocomposites, both tensile strength and Young's modulus of the films increased with increasing MCC-RS content up until 7.5wt%, supported with scanning electron microscopy (SEM) results which depicted improvement in the interfacial adhesion between MCC-RS and PVOH. From the overall results, the improvement in properties of biocomposite from cellulose-based microfiller had shown promising future in application of the water soluble plastic packaging industry.

PMMA-Etching-Free Transfer of Wafer-scale Chemical Vapor Deposition Two-dimensional Atomic Crystal by a Water Soluble Polyvinyl Alcohol Polymer Method

Science.gov (United States)

van Ngoc, Huynh; Qian, Yongteng; Han, Suk Kil; Kang, Dae Joon

2016-09-01

We have explored a facile technique to transfer large area 2-Dimensional (2D) materials grown by chemical vapor deposition method onto various substrates by adding a water-soluble Polyvinyl Alcohol (PVA) layer between the polymethyl-methacrylate (PMMA) and the 2D material film. This technique not only allows the effective transfer to an arbitrary target substrate with a high degree of freedom, but also avoids PMMA etching thereby maintaining the high quality of the transferred 2D materials with minimum contamination. We applied this method to transfer various 2D materials grown on different rigid substrates of general interest, such as graphene on copper foil, h-BN on platinum and MoS2 on SiO2/Si. This facile transfer technique has great potential for future research towards the application of 2D materials in high performance optical, mechanical and electronic devices.

Diffusion coefficient, porosity measurement, dynamic and equilibrium swelling studies of Acrylic acid/Polyvinyl alcohol (AA/PVA hydrogels

Directory of Open Access Journals (Sweden)

Nazar Mohammad Ranjha

2015-06-01

Full Text Available Objective of the present work was to synthesize hydrogels of acrylic acid/polyvinyl alcohol (AA/PVA by free radical polymerization by using glutaradehyde (GA as crosslinkers. The hydrogels were evaluated for swelling, diffusion coefficient and network parameters like the average molecular weight between crosslink’s, polymer volume fraction in swollen state, number of repeating units between crosslinks and crosslinking density by using Flory-Huggins theory. It was found that the degree of swelling of AA/PVA hydrogels increases greatly within the pH range 5-7. The gel fraction and porosity increased by increasing the concentration of AA or PVA. Increase in degree of crosslinking, decreased the porosity and inverse was observed in gel fraction. Selected samples were loaded with metoprolol tartrate. Drug release was studied in USP hydrochloric acid solution of pH 1.2 and phosphate buffer solutions of pH 5.5 and 7.5. Various kinetics models like zero order, first order, Higuchi and Peppas model were used for in vitro kinetic studies. The results showed that the drug release followed concentration dependent effect (First order kinetics with non-Fickian diffusion. FTIR and SEM used to study the structure, crystallinity, compatibility, thermal stability and morphology of prepared and drug loaded hydrogels respectively.

Studies on soy protein isolate/polyvinyl alcohol hybrid nanofiber membranes as multi-functional eco-friendly filtration materials

International Nuclear Information System (INIS)

Fang, Qun; Zhu, Ming; Yu, Siruo; Sui, Gang; Yang, Xiaoping

2016-01-01

Highlights: • Biodegradable filtration membranes were prepared. • Polar groups in the membrane surface helped capture fine particles. • Loading filtration efficiency can reach 99.99% in the case of small pressure drop. • Filtration membrane showed antimicrobial activity to Escherichia coli. - Abstract: A biodegradable and multifunctional air filtration membrane was prepared by electrospinning of soy protein isolate (SPI)/polyvinyl alcohol (PVA) system in this paper. The optimized SPI/PVA proportion in the spinning solution was determined according to the analyses of microstructure, surface chemical characteristic and mechanical property of the hybrid nanofiber membranes. Under the preferred preparation condition, two kinds of polymer materials displayed a good compatibility in the hybrid nanofibers, and a large number of polar groups existed in the membrane surface. The loading filtration efficiency of the nanofiber membrane with optimal material ratio and areal density can reach 99.99% after test of 30 min for fine particles smaller than 2.5 μm in the case of small pressure drop. Besides, this kind of filtration membrane showed an antimicrobial activity to Escherichia coli in the study. The SPI/PVA hybrid nanofiber membrane with proper material composition and microstructure can be used as a new type of high performance eco-friendly filtration materials.

Studies on soy protein isolate/polyvinyl alcohol hybrid nanofiber membranes as multi-functional eco-friendly filtration materials

Energy Technology Data Exchange (ETDEWEB)

Fang, Qun; Zhu, Ming; Yu, Siruo; Sui, Gang, E-mail: suigang@mail.buct.edu.cn; Yang, Xiaoping

2016-12-15

Highlights: • Biodegradable filtration membranes were prepared. • Polar groups in the membrane surface helped capture fine particles. • Loading filtration efficiency can reach 99.99% in the case of small pressure drop. • Filtration membrane showed antimicrobial activity to Escherichia coli. - Abstract: A biodegradable and multifunctional air filtration membrane was prepared by electrospinning of soy protein isolate (SPI)/polyvinyl alcohol (PVA) system in this paper. The optimized SPI/PVA proportion in the spinning solution was determined according to the analyses of microstructure, surface chemical characteristic and mechanical property of the hybrid nanofiber membranes. Under the preferred preparation condition, two kinds of polymer materials displayed a good compatibility in the hybrid nanofibers, and a large number of polar groups existed in the membrane surface. The loading filtration efficiency of the nanofiber membrane with optimal material ratio and areal density can reach 99.99% after test of 30 min for fine particles smaller than 2.5 μm in the case of small pressure drop. Besides, this kind of filtration membrane showed an antimicrobial activity to Escherichia coli in the study. The SPI/PVA hybrid nanofiber membrane with proper material composition and microstructure can be used as a new type of high performance eco-friendly filtration materials.

Alkaline direct ethanol fuel cell performance using alkali-impregnated polyvinyl alcohol/functionalized carbon nano-tube solid electrolytes

Science.gov (United States)

Huang, Chien-Yi; Lin, Jia-Shiun; Pan, Wen-Han; Shih, Chao-Ming; Liu, Ying-Ling; Lue, Shingjiang Jessie

2016-01-01

This study investigates the application of a polyvinyl alcohol (PVA)/functionalized carbon nano-tubes (m-CNTs) composite in alkaline direct ethanol fuel cells (ADEFC). The m-CNTs are functionalized with PVA using the ozone mediation method, and the PVA composite containing the modified CNTs is prepared. Adding m-CNT into the PVA matrix enhances the alkaline uptake and the ionic conductivity of the KOH-doped electrolyte. Meanwhile, the m-CNT-containing membrane exhibited a lower swelling ratio and suppressed ethanol permeability compared to the pristine PVA film. The optimal condition for the ADEFC is determined to be under operation at an anode feed of 3 M ethanol in a 5 M KOH solution (at a flow rate of 5 cm3 min-1) with a cathode feed of moisturized oxygen (with a flow rate of 100 cm3 min-1) and the KOH-doped PVA/m-CNT electrolyte. We achieved a peak power density value of 65 mW cm-2 at 60 °C, which is the highest among the ADEFC literature data and several times higher than the proton-exchange direct ethanol fuel cells using sulfonated membrane electrolytes. Therefore, the KOH-doped PVA/m-CNT electrolyte is a suitable solid electrolyte for ADEFCs and has potential for commercialization in alkaline fuel cell applications.

Near-Infrared Light-Sensitive Polyvinyl Alcohol Hydrogel Photoresist for Spatiotemporal Control of Cell-Instructive 3D Microenvironments.

Science.gov (United States)

Qin, Xiao-Hua; Wang, Xiaopu; Rottmar, Markus; Nelson, Bradley J; Maniura-Weber, Katharina

2018-03-01

Advanced hydrogel systems that allow precise control of cells and their 3D microenvironments are needed in tissue engineering, disease modeling, and drug screening. Multiphoton lithography (MPL) allows true 3D microfabrication of complex objects, but its biological application requires a cell-compatible hydrogel resist that is sufficiently photosensitive, cell-degradable, and permissive to support 3D cell growth. Here, an extremely photosensitive cell-responsive hydrogel composed of peptide-crosslinked polyvinyl alcohol (PVA) is designed to expand the biological applications of MPL. PVA hydrogels are formed rapidly by ultraviolet light within 1 min in the presence of cells, providing fully synthetic matrices that are instructive for cell-matrix remodeling, multicellular morphogenesis, and protease-mediated cell invasion. By focusing a multiphoton laser into a cell-laden PVA hydrogel, cell-instructive extracellular cues are site-specifically attached to the PVA matrix. Cell invasion is thus precisely guided in 3D with micrometer-scale spatial resolution. This robust hydrogel enables, for the first time, ultrafast MPL of cell-responsive synthetic matrices at writing speeds up to 50 mm s -1 . This approach should enable facile photochemical construction and manipulation of 3D cellular microenvironments with unprecedented flexibility and precision. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Poly(vinyl Alcohol) Borate Gel Polymer Electrolytes Prepared by Electrodeposition and Their Application in Electrochemical Supercapacitors.

Science.gov (United States)

Jiang, Mengjin; Zhu, Jiadeng; Chen, Chen; Lu, Yao; Ge, Yeqian; Zhang, Xiangwu

2016-02-10

Gel polymer electrolytes (GPEs) have been studied for preparing flexible and compact electrochemical energy storage devices. However, the preparation and use of GPEs are complex, and most GPEs prepared through traditional methods do not have good wettability with the electrodes, which retard them from achieving their performance potential. In this study, these problems are addressed by conceiving and implementing a simple, but effective, method of electrodepositing poly(vinyl alcohol) potassium borate (PVAPB) GPEs directly onto the surfaces of active carbon electrodes for electrochemical supercapacitors. PVAPB GPEs serve as both the electrolyte and the separator in the assembled supercapacitors, and their scale and shape are determined solely by the geometry of the electrodes. PVAPB GPEs have good bonding to the active electrode materials, leading to excellent and stable electrochemical performance of the supercapacitors. The electrochemical performance of PVAPB GPEs and supercapacitors can be manipulated simply by adjusting the concentration of KCl salt used during the electrodeposition process. With a 0.9 M KCl concentration, the as-prepared supercapacitors deliver a specific capacitance of 65.9 F g(-1) at a current density of 0.1 A g(-1) and retain more than 95% capacitance after 2000 charge/discharge cycles at a current density of 1 A g(-1). These supercapacitors also exhibit intelligent high voltage self-protection function due to the electrolysis-induced cross-linking effect of PVAPB GPEs.

Dual functions of polyvinyl alcohol (PVA): fabricating particles and electrospinning nanofibers applied in controlled drug release

Science.gov (United States)

Qin, Xiao-Hong; Wu, De-Qun; Chu, Chih-Chang

2013-01-01

The fabrication of submicron size microsphere from 8-Phe-4 poly(ester amide) (PEA) using polyvinyl alcohol (PVA) as the emulsion was reported. The biodegradable microspheres were prepared by an oil-in-water emulsion/solvent evaporation technique, and PVA was used as the emulsion. Furthermore, the emulsion PVA was electrospun into nanofibrous mats, and 8-Phe-4 PEA microspheres were entrapped in the resultant mats. The dual functions of PVA to fabricate ideal nanofibrous mats which can entrap microspheres in them and to obtain 8-Phe-4 microspheres as emulsion in their potential application were demonstrated. The anti-cancer drug doxorubicin (DOX) was encapsulated in the 8-Phe-4 amino acid-based PEA microspheres and the entrapment efficiency is almost 100 %. At the same time, the DOX can be controlled released in PBS solution and in α-chymotrypsin solution. The cytotoxicity of PVA, PVA mats-entrapped 8-Phe-4 microspheres and PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres, was investigated. Hela cells were used to test the cytotoxicity of the DOX that released from the PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres for 2 days, and the cell viability is below 30 % when the 8-Phe-4 microspheres concentration is 1 mg/mL. It demonstrated that the PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres have a potential biomedical application.

Tailoring the structure and properties of amorphous starch blending and EB-radiation processing

International Nuclear Information System (INIS)

Khandal, D.; Bliard, C.; Coqueret, X.; Mikus, P.Y.; Dole, P.; Baumberger, S.

2011-01-01

Complete text of publication follows. Starch can be used alone and in combination with other compounds to make biodegradable articles from renewable resources. Lignins and their derivatives are good candidates for limiting the water sensitivity of starch-based materials, but they exhibit poor compatibility in blends with polysaccharides. Electron beam (EB) processing is proposed as an efficient method for inducing covalent linkages between the two constituents. Compared to unirradiated starting materials, the surface and bulk properties of EB-irradiated starch - lignin blends submitted to EB irradiation showed an interesting reduction in hydrophilicity. Radiation induced grafting of lignin models onto starch was shown to impede long-term retrogradation, with limited loss of mechanical properties. The reactivity under radiation of model blends was examined by several analytical methods. Maldi-T of mass spectrometry allowed us to propose reasonable free radical mechanisms that account for the grafting of various benzyl and cinnamyl alcohols onto maltodextrins. The presence of cinnamyl derivatives was found not only to limit degradation, but also modify the properties of the formulations (improved hydrophobicity, mechanical properties). Size exclusion chromatography and gel fraction measurements confirmed unambiguously the attachment of UV-absorbing chromophores onto the maltodextrin main chain. The combination of the obtained results demonstrates the possibility of altering in a favourable way the tensile properties of plasticized starch by applying high energy radiation to properly formulated blends including aromatic compounds like cinnamyl alcohol.

Fermentation of starches and sugars to alcohol

Energy Technology Data Exchange (ETDEWEB)

Fertman, G I; Berenshtein, A F; Gulyaev, J P

1958-02-25

To prevent the growth of acid-forming bacteria in the started wort, the ester-aldehyde fraction or the amino alcohol obtained in the rectification process is returned to the wort in amounts sufficient to give an alcohol concentration of approximately 1.5% by volume. The fermenting wort is also acidified to 0.5 to 0.6.

MECHANICAL PROPERTIES OF BLENDS OF PAMAM DENDRIMERS WITH POLY(VINYL CHLORIDE) AND POLY(VINYL ACETATE)

Science.gov (United States)

Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonacne ...

Bioinspired design and macroscopic assembly of poly(vinyl alcohol)-coated graphene into kilometers-long fibers

Science.gov (United States)

Kou, Liang; Gao, Chao

2013-05-01

Nacre is characterized by its excellent mechanical performance due to the well-recognized ``brick and mortar'' structure. Many efforts have been applied to make nacre-mimicking materials, but it is still a big challenge to realize their continuous production. Here, we prepared sandwich-like building blocks of poly(vinyl alcohol) (PVA)-coated graphene, and achieved high-nanofiller-content kilometers-long fibers by continuous wet-spinning assembly technology. The fibers have a strict ``brick and mortar'' layered structure, with graphene sheet as rigid brick and PVA as soft mortar. The mortar thickness can be precisely tuned from 2.01 to 3.31 nm by the weight feed ratio of PVA to graphene, as demonstrated by both atomic force microscopy and X-ray diffraction measurements. The mechanical strength of the nacre-mimicking fibers increases with increasing the content of PVA, and it rises gradually from 81 MPa for the fiber with 53.1 wt% PVA to 161 MPa for the fiber with 65.8 wt% PVA. The mechanical performance of our fibers was independent of the molecular weight (MW) of PVA in the wide range of 2-100 kDa, indicating that low MW polymers can also be used to make strong nanocomposites. The tensile stress of fibers immersed in PVA 5 wt% solution reached ca. 200 MPa, surpassing the values of nacre and most of other nacre-mimicking materials. The nacre-mimicking fibers are highly electrically conductive (~350 S m-1) after immersing in hydroiodic acid, enabling them to connect a circuit to illuminate an LED lamp.Nacre is characterized by its excellent mechanical performance due to the well-recognized ``brick and mortar'' structure. Many efforts have been applied to make nacre-mimicking materials, but it is still a big challenge to realize their continuous production. Here, we prepared sandwich-like building blocks of poly(vinyl alcohol) (PVA)-coated graphene, and achieved high-nanofiller-content kilometers-long fibers by continuous wet-spinning assembly technology. The fibers

Starch bioengineering

DEFF Research Database (Denmark)

Blennow, Andreas

2018-01-01

Application of starch in industry frequently requires extensive modification. This is usually achieved by chemical and/or physical modification that is time-consuming and often expensive and polluting. To impart functionality as early as possible in the starch production chain, modification can...... be achieved directly as part of the developing starch storage roots, tubers, and seeds and grains of the crop. Starch has been a strong driver for human development and is now the most important energy provider in the diet forcing the development of novel and valuable starch qualities for specific...... applications. Among the most important structures that can be targeted include starch phosphorylation chain transfer/branching generating chemically substituted and chain length-modified starches such as resistant and health-promoting high-amylose starch. Starch bioengineering has been employed for more than...

Photoinduced transformations of optical properties of CdSe and Ag-In-S nanocrystals embedded in the films of polyvinyl alcohol

Directory of Open Access Journals (Sweden)

Tetyana Kryshtab

2016-06-01

Full Text Available The results of investigation of photostability of the composites of CdSe and Ag-In-S nanocrystals (NCs embedded in the films of polyvinyl alcohol (PVA are presented. The films were studied by photoluminescence (PL, optical absorption, micro-Raman and X-ray diffraction methods. It is found that heating of the films to 100 °C promotes PVA crystallization and stimulates an increase of the PL intensity for the NCs of both types. The latter effect is ascribed mainly to the improvement of NC surface passivation by functional groups of PVA. The illumination with the 409-nm LED’s light enhances PL intensity for CdSe NCs and decreases it for Ag-In-S NCs as well as results in the darkening of the films. The color of the Ag-In-S-PVA film restores with time, while the change of the optical properties of the CdSe-PVA composite is irreversible. The possible mechanisms of the revealed effects, such as structural transformations at NC/PVA interface as well as the formation of new light-absorbing species are discussed.

Determination of expected alcohol yield from molasses by laboratory fermentation

Energy Technology Data Exchange (ETDEWEB)

Medintseva, L L

1960-01-01

Molasses (750 g, 18 to 19% dry weight) in 31 media, supplemented with nutrients was fermented with the industrial yeast strain. The expected alcohol yield was calculated for 1 kg conventional starch as B = V/P..pi.. 0.95, where V is the amount of alcohol distilled from the fermented medium in ml, P is the weight of molasses in g, is the fermentable sugar content of the molasses in percent, and 0.95 is the conversion factor from sucrose to starch.

Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications

Energy Technology Data Exchange (ETDEWEB)

Pon-On, Weeraphat, E-mail: fsciwpp@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Krishnamra, Nateetip [Center of Calcium and Bone Research (COCAB), Faculty of Science, Mahidol University (Thailand); Department of Physiology, Faculty of Science, Mahidol University (Thailand); Tang, I-Ming [ThEP Center, Commission of Higher Education, 328 Si Ayutthaya Rd. (Thailand); Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand)

2014-05-01

In the present study, composite scaffolds made with different weight ratios (0.5:1, 1:1 and 2:1) of bioactive glass (15Ca:80Si:5P) (BG)/polyvinyl alcohol (PVA) (PVABG) and chitosan (Chi)/collagen (Col) (ChiCol) were prepared by three mechanical freeze–thaw followed by freeze-drying to obtain the porous scaffolds. The mechanical properties and the in vitro biocompatibility of the composite scaffolds to simulated body fluid (SBF) and to rat osteoblast-like UMR-106 cells were investigated. The results from the studies indicated that the porosity and compressive strength were controlled by the weight ratio of PVABG:ChiCol. The highest compressive modulus of the composites made was 214.64 MPa which was for the 1:1 weight ratio PVABG:ChiCol. Mineralization study in SBF showed the formation of apatite crystals on the PVABG:ChiCol surface after 7 days of incubation. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the PVABG:ChiCol surface. MTT and ALP tests on the 1:1 weight ratio PVABG:ChiCol composite indicated that the UMR-106 cells were viable. Alkaline phosphatase activity was found to increase with increasing culturing time. In addition, we showed the potential of PVABG:ChiCol drug delivery through PBS solution studies. 81.14% of BSA loading had been achieved and controlled release for over four weeks was observed. Our results indicated that the PVABG:ChiCol composites, especially the 1:1 weight ratio composite exhibited significantly improved mechanical, mineral deposition, biological properties and controlled release. This made them potential candidates for bone tissue engineering applications. - Graphical abstract: Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications. - Highlights: • Preparation of PVABG:ChiCol hybrid composites and their bioactivities • Mechanical

Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications

International Nuclear Information System (INIS)

Pon-On, Weeraphat; Charoenphandhu, Narattaphol; Teerapornpuntakit, Jarinthorn; Thongbunchoo, Jirawan; Krishnamra, Nateetip; Tang, I-Ming

2014-01-01

In the present study, composite scaffolds made with different weight ratios (0.5:1, 1:1 and 2:1) of bioactive glass (15Ca:80Si:5P) (BG)/polyvinyl alcohol (PVA) (PVABG) and chitosan (Chi)/collagen (Col) (ChiCol) were prepared by three mechanical freeze–thaw followed by freeze-drying to obtain the porous scaffolds. The mechanical properties and the in vitro biocompatibility of the composite scaffolds to simulated body fluid (SBF) and to rat osteoblast-like UMR-106 cells were investigated. The results from the studies indicated that the porosity and compressive strength were controlled by the weight ratio of PVABG:ChiCol. The highest compressive modulus of the composites made was 214.64 MPa which was for the 1:1 weight ratio PVABG:ChiCol. Mineralization study in SBF showed the formation of apatite crystals on the PVABG:ChiCol surface after 7 days of incubation. In vitro cell availability and proliferation tests confirmed the osteoblast attachment and growth on the PVABG:ChiCol surface. MTT and ALP tests on the 1:1 weight ratio PVABG:ChiCol composite indicated that the UMR-106 cells were viable. Alkaline phosphatase activity was found to increase with increasing culturing time. In addition, we showed the potential of PVABG:ChiCol drug delivery through PBS solution studies. 81.14% of BSA loading had been achieved and controlled release for over four weeks was observed. Our results indicated that the PVABG:ChiCol composites, especially the 1:1 weight ratio composite exhibited significantly improved mechanical, mineral deposition, biological properties and controlled release. This made them potential candidates for bone tissue engineering applications. - Graphical abstract: Mechanical properties, biological activity and protein controlled release by poly(vinyl alcohol)–bioglass/chitosan–collagen composite scaffolds: A bone tissue engineering applications. - Highlights: • Preparation of PVABG:ChiCol hybrid composites and their bioactivities • Mechanical

Oxidation of the Primary Alcoholic Moiety Selectively in the Presence of the Secondary Alcoholic Moieties

International Nuclear Information System (INIS)

Tin Myint Htwe

2011-12-01

Both primary and secondary alcoholic moieties are very sensitive to oxidation reactions. But sometimes it is necessary to oxidized only the primary alcoholic moiety. Such cases are usually found in Food Industries. In this situation, TEMPO (1, 1, 6, 6-Tetramethyl-1-Piperidine Oxoammonium) was used as an oxidizing agent. In this paper, Alpha starch was successfully oxidized using TEMPO as the oxidizing agent in combination with sodium hypochlorite with and without sodium bromide. The oxidation of primary alcoholic moiety only and the remaining untouched secondary alcoholic moiety were proved by infrared spectroscopy method.

Rat model hindlimb ischemia induced via embolization with polyvinyl alcohol and N butyl cyanoacrylate

Energy Technology Data Exchange (ETDEWEB)

Shin, Cheong Il; Kim, Hyo Cheol; Song, Yong Sub; Cho, Hye Rim; Lee, Kyoung Bun; Jae, Hwan June; Chung, Jin Wook [Seoul National University Hospital, Seoul (Korea, Republic of)

2013-12-15

To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model.

Preparation of Polyvinyl Alcohol/Xylan Blending Films with 1,2,3,4-Butane Tetracarboxylic Acid as a New Plasticizer

Directory of Open Access Journals (Sweden)

Cun-dian Gao

2014-01-01

Full Text Available Miscible, biodegradable polyvinyl alcohol (PVA/xylan blending films were firstly prepared in the range of the PVA/xylan weight ratio from 1 : 2 to 3 : 1 by casting method using 1,2,3,4-butane tetracarboxylic acid (BTCA as a new plasticizer. The properties of blending films as functions of PVA/xylan weight ratio and BTCA amount were discussed. XRD and FT-IR were applied to characterize the blending films. Experimental results indicated that tensile strength (TS and elongation at break (EAB of blending films decreased along with the decrease of the PVA/xylan weight ratio. Both of TS and EAB firstly increased and then decreased as the amount of BTCA was increased. More importantly, blending films were biodegraded almost by 41% with an addition of 10% BTCA in blending films within 30 days in soil. For all hydroxyl functionalized polymers (xylan and PVA, their molecular interactions and miscibility with BTCA endowed blending films with the biocompatibility and biodegradability. Therefore, these blending films are environmentally friendly materials which could be applied as biodegradable plastics for food packaging and agricultural applications.

Studies on the Electrical Properties of Graphene Oxide-Reinforced Poly (4-Styrene Sulfonic Acid) and Polyvinyl Alcohol Blend Composites

Science.gov (United States)

Deshmukh, Kalim; Sankaran, Sowmya; Basheer Ahamed, M.; Khadheer Pasha, S. K.; Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Al-Ali Almaadeed, Mariam; Chidambaram, K.

In the present study, graphene oxide (GO)-reinforced poly (4-styrenesulfonic acid) (PSSA)/polyvinyl alcohol (PVA) blend composite films were prepared using colloidal blending technique at various concentrations of GO (0-3wt.%). The morphological investigations of the prepared composites were carried out using polarized optical microscopy and scanning electron microscopy. The electrical properties of composites were evaluated using an impedance analyzer in the frequency range 50Hz to 20MHz and temperature in the range 40-150∘C. Morphological studies infer that GO was homogeneously dispersed in the PSSA/PVA blend matrix. Investigations of electrical property indicate that the incorporation of GO into PSSA/PVA blend matrix resulted in the enhancement of the impedance (Z) and the quality factor (Q-factor) values. A maximum impedance of about 4.32×106Ω was observed at 50Hz and 90∘C for PSSA/PVA/GO composites with 3wt.% GO loading. The Q-factor also increased from 8.37 for PSSA/PVA blend to 59.8 for PSSA/PVA/GO composites with 3wt.% GO loading. These results indicate that PSSA/PVA/GO composites can be used for high-Q capacitor applications.

Poly(furfuryl alcohol) nanospheres: a facile synthesis approach ...

Indian Academy of Sciences (India)

poly(furfuryl alcohol) (PFA) nanospheres with an average diameter of 350 nm in the presence of poly(vinyl pyrroli- done) (PVP) ... with metal cations and subsequent conversion to metal oxide ... 2.2 Preparation of α-Fe2O3 hollow nanospheres.

Bioinspired design and macroscopic assembly of poly(vinyl alcohol)-coated graphene into kilometers-long fibers.

Science.gov (United States)

Kou, Liang; Gao, Chao

2013-05-21

Nacre is characterized by its excellent mechanical performance due to the well-recognized "brick and mortar" structure. Many efforts have been applied to make nacre-mimicking materials, but it is still a big challenge to realize their continuous production. Here, we prepared sandwich-like building blocks of poly(vinyl alcohol) (PVA)-coated graphene, and achieved high-nanofiller-content kilometers-long fibers by continuous wet-spinning assembly technology. The fibers have a strict "brick and mortar" layered structure, with graphene sheet as rigid brick and PVA as soft mortar. The mortar thickness can be precisely tuned from 2.01 to 3.31 nm by the weight feed ratio of PVA to graphene, as demonstrated by both atomic force microscopy and X-ray diffraction measurements. The mechanical strength of the nacre-mimicking fibers increases with increasing the content of PVA, and it rises gradually from 81 MPa for the fiber with 53.1 wt% PVA to 161 MPa for the fiber with 65.8 wt% PVA. The mechanical performance of our fibers was independent of the molecular weight (MW) of PVA in the wide range of 2-100 kDa, indicating that low MW polymers can also be used to make strong nanocomposites. The tensile stress of fibers immersed in PVA 5 wt% solution reached ca. 200 MPa, surpassing the values of nacre and most of other nacre-mimicking materials. The nacre-mimicking fibers are highly electrically conductive (∼350 S m(-1)) after immersing in hydroiodic acid, enabling them to connect a circuit to illuminate an LED lamp.

Effect of phytase application during high gravity (HG) maize mashes preparation on the availability of starch and yield of the ethanol fermentation process.

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Mikulski, D; Kłosowski, G; Rolbiecka, A

2014-10-01

Phytic acid present in raw materials used in distilling industry can form complexes with starch and divalent cations and thus limit their biological availability. The influence of the enzymatic hydrolysis of phytate complexes on starch availability during the alcoholic fermentation process using high gravity (HG) maize mashes was analyzed. Indicators of the alcoholic fermentation as well as the fermentation activity of Saccharomyces cerevisiae D-2 strain were statistically evaluated. Phytate hydrolysis improved the course of the alcoholic fermentation of HG maize mashes. The final ethanol concentration in the media supplemented with phytase applied either before or after the starch hydrolysis increased by 1.0 and 0.6 % v/v, respectively, as compared to the control experiments. This increase was correlated with an elevated fermentation yield that was higher by 5.5 and 2.0 L EtOH/100 kg of starch, respectively. Phytate hydrolysis resulted also in a statistically significant increase in the initial concentration of fermenting sugars by 14.9 mg/mL of mash, on average, which was a consequence of a better availability of starch for enzymatic hydrolysis. The application of phytase increased the attenuation of HG media fermentation thus improving the economical aspect of the ethanol fermentation process.

Enhanced mechanical and thermal properties of poly (vinyl alcohol)/corn starch blends by nanoclay intercalation.

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Tian, Huafeng; Wang, Kai; Liu, Di; Yan, Jiaan; Xiang, Aimin; Rajulu, A Varada

2017-08-01

Poly (vinyl alcohol) (PVA)/corn starch blend films with enhanced properties were fabricated by melt processing and montmorillonite (MMT) reinforcing. It was revealed that strong hydrogen bonding occurred between the abundant OH groups of the matrix and polar SiOSi and OH groups of MMT. The highly exfoliated MMT nanolayers were randomly dispersed in the matrix containing MMT lower than 10wt%, whereas the intercalated structure was predominant with MMT content higher than 10wt%. With the increase of MMT, the glass transition temperature as well as equilibrium torque increased. The water sorption decreased and water resistant properties were improved with the incorporation of MMT due to the restricted swelling of the matrix by MMT nanolayers. Significant improvement in strength and flexibility were observed due to the fine dispersion of the MMT layers and the strong interaction between MMT and the matrix. The thermal stability was also improved. The MMT nanolayers could act as the heat and mass transport barriers and retard the thermal decomposition of the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea.

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Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao

2014-03-01

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

Improvement of Raw-Starch Digestibility of Amylase from Aspergillus awamori by Gamma Radiation Mutation for Alcohol Production

International Nuclear Information System (INIS)

Kanlayakrit, Werasit; Piadang, Nattayana; Maweang, Metinee

2006-09-01

Aspergillus awamori was induced to mutation by gamma ray to improve raw-starch digestibility of amylase enzyme. Twenty fungal colonies were selected base on and amylase and glucoamylase activities including raw starch digestibility. The result showed that isolate A a(i)-2(16) was the best isolate for raw-starch digestion (65.64 %). It produced extracellular amylase enzyme which showed highest raw-starch digestibility more than wild type about 2 folds. Based on enzymes from solid culture showed activities higher from liquid medium. Therefore solid culture is suitable for fungal enzyme production.

Effect of Pyrite on Thiosulfate Leaching of Gold and the Role of Ammonium Alcohol Polyvinyl Phosphate (AAPP

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Xiaoliang Liu

2017-07-01

Full Text Available The effect of pyrite and the role of ammonium alcohol polyvinyl phosphate (AAPP during gold leaching in ammoniacal thiosulfate solutions were investigated using pure gold foils. The results showed that pyrite catalyzed the decomposition and also significantly increased the consumption of thiosulfate. This detrimental effect became more severe with increasing pyrite content. Further, the presence of pyrite also substantially slowed the gold leaching kinetics and reduced the overall gold dissolution. The reduction in gold dissolution was found to be caused primarily by the surface passivation of the gold. The negative effects of pyrite, however, can be alleviated by the addition of AAPP. Comparison of zeta potentials of pyrite with and without AAPP suggests that AAPP had adsorbed on the surface of the pyrite and weakened the catalytic effect of pyrite on the thiosulfate decomposition by blocking the contact between the pyrite and thiosulfate anions. AAPP also competed with thiosulfate anions to complex with the cupric ion at the axial coordinate sites, and thus abated the oxidation of thiosulfate by cupric ions. Moreover, the indiscriminate adsorption of AAPP on the surfaces of gold and passivation species prevented the passivation of the gold surface by surface charge and electrostatic repulsion. Therefore, AAPP effectively stabilized the thiosulfate in the solution and facilitated the gold leaching in the presence of pyrite.

Effect of phosphorous-containing modified poly(vinyl alcohol on the mechanical and flame retardant properties of polypropylene

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S. Sauca

2015-04-01

Full Text Available Blends of polypropylene (PP and different phosphorous-modified poly(vinyl alcohol (PVA derivatives synthesized on purpose, were prepared by both solvent and melt mixing, and fully characterized. Thermogravimetric analysis showed that the addition of the phosphorous-modified PVAs significantly increased thermal stability and charring of PP, probably due to their dehydration and the subsequent formation of a protective layer onto PP. SEM analysis demonstrated poor phase compatibility between PP and the polymeric additives, however acceptable dispersion of the polymeric additives was obtained. It was also observed that grafting of the modified PVA on PP occurred due to radical reactions arising during melt processing. Mechanical characterization showed that the elastic behavior of the blends was not altered with respect to neat PP, while ductility was reduced; on the other hand, impact resistance was considerably improved by blending. Slightly higher LOI values were obtained for the blends even with phosphorous content as small as 1 wt%; reduced dripping was also observed during the burning tests for the blend samples. Moreover, cone calorimeter test results showed that heat release rate, total heat release, and fire growth rate decreased compared with PP, in particular for the blends containing residual –OH groups on the PVA backbone. Therefore, these blends can find application where the combination of toughness and fire retardancy is required, such as in the automotive industry.

Structure, corrosion behavior and mechanical property of a novel poly(vinyl alcohol) composite in simulated body fluid.

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Li, Juan; Suo, Jinping; Zou, Peng; Jia, Lintao; Wang, Shifang

2010-01-01

The data for long-term drug-delivery systems are scarce compared to the short-term systems because the required research efforts are more time-consuming. In this study, we report a novel cross-linked composite based on poly(vinyl alcohol) (PVA) containing cupric ions for long-term delivery, which is helpful for contraception and trace element balance in the human body. The composition, corrosion products, crystal structure, chemical structure and mechanical stability of the composite, after being immersed in simulated body fluid (SBF) for one year, were studied by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR) and mechanical testing. The results show that no other new elements, such as P, Cl and Ca, appear on the surface of the composite and no Cu(2)O was formed after immersion in SBF for one year. The effectiveness of copper can be greatly improved and the side-effects caused by these compounds might also be eliminated. Furthermore, this novel composite exhibits long-term mechanical stability in SBF. The present in vitro long-term data suggest that this novel copper-containing composite may serve as a substitute for conventional materials of copper-containing intrauterine devices (Cu-IUDs) and as a carrier for controlled-release material in a variety of other applications.

Synthesis and characterization of polyvinyl alcohol/cellulose cryogels and their testing as carriers for a bioactive component

Energy Technology Data Exchange (ETDEWEB)

Paduraru, Oana Maria; Ciolacu, Diana; Darie, Raluca Nicoleta; Vasile, Cornelia, E-mail: cvasile@icmpp.ro

2012-12-01

Novel physically cross-linked cryogels containing polyvinyl alcohol (PVA) and various amounts of microcrystalline cellulose were obtained by freezing/thawing technique. The main goal of this study was to improve the properties and the performances of the pure PVA cryogels. The morphological aspects of the cryogels were studied by scanning electron microscopy (SEM). The Fourier transform infrared spectroscopy (FT-IR) was used to reveal the presence of the interactions between the two polymers. Changes in crystallinity of the samples were confirmed by X-ray diffraction (XRD) and by FT-IR spectroscopy. The modification of the thermal behavior induced by cellulose was studied by thermogravimetry. Rheological analysis revealed higher values of storage modulus (G Prime ) for the cryogels containing higher amounts of cellulose. The degree and rate of swelling were controlled by the presence of the natural polymer in the network. The potential application as bioactive compound carriers was tested, using vanillin as an active agent. Highlights: Black-Right-Pointing-Pointer Novel PVA/microcrystalline cellulose cryogels were obtained by freezing/thawing. Black-Right-Pointing-Pointer The main advantage of this technique is that no chemical crosslinker is being used. Black-Right-Pointing-Pointer The presence of cellulose improves the swelling properties and the cryogels' strength. Black-Right-Pointing-Pointer The potential application as carriers for bioactive components was tested.

The Effects of Montmorillonite and Cellulose Nanocrystals on Physical Properties of Carboxymethyl Cellulose/Polyvinyl Alcohol Blend Films

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Leila Abolghasemi Fakhri

2013-01-01

Full Text Available Cellulose nanocrystal  CNC is a type of nanomaterial which is produced by  partial hydrolysis of cellulose and elimination of its amorphous regions. CNC has several advantages such as biodegradability and safety toward human health. In this study, CNC was produced from cotton linters and methods such as transmission electron microscopy and atomic force microscopy were used for confrmation of nanoscale  size production of cellulose crystals. Carboxymethyl cellulose  CMC/polyvinyl alcohol  PVA-nanoclay  MMT and CMC-PVA-CNC flms, containing 3-10% (wt/wt CMC nanofllers, were prepared by casting method and their physical properties were compared in order to approve the use of CNC instead of MMT for its contribution in improving the physical properties of carboxymethyl cellulose-based  flms.  The  X-ray  diffraction  results  indicated  the  formation  of  an exfoliated nanostructure at all nanoparticle concentrations. The results showed that there was no signifcant difference (p < 0.5 between the moisture absorption properties of flms containing the two types of nanofller. The flms containing nanoclay showed higher mechanical strength compared to those containing CNC. The ultimate tensile strengths of the flms containing 10% nanoclay and CNC were higher than the control flm (69.72% and 47.05%, respectively.

Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

International Nuclear Information System (INIS)

Chatelin, Simon; Bernal, Miguel; Deffieux, Thomas; Papadacci, Clément; Nahas, Amir; Boccara, Claude; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu; Flaud, Patrice

2014-01-01

Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305–11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original multimodality imaging characterization of this new transverse isotropic (TI) PVA hydrogel. Multiple properties were investigated using a large variety of techniques at different scales compared with an isotropic PVA hydrogel undergoing similar imaging and rheology protocols. The anisotropic mechanical (dynamic and static) properties were studied using supersonic shear wave imaging technique, full-field optical coherence tomography (FFOCT) strain imaging and classical linear rheometry using dynamic mechanical analysis. The anisotropic optical and ultrasonic spatial coherence properties were measured by FFOCT volumetric imaging and backscatter tensor imaging, respectively. Correlation of mechanical and optical properties demonstrates the complementarity of these techniques for the study of anisotropy on a multi-scale range as well as the potential of this TI phantom as fibrous tissue-mimicking phantom for shear wave elastographic applications. (paper)

Anisotropic polyvinyl alcohol hydrogel phantom for shear wave elastography in fibrous biological soft tissue: a multimodality characterization

Science.gov (United States)

Chatelin, Simon; Bernal, Miguel; Deffieux, Thomas; Papadacci, Clément; Flaud, Patrice; Nahas, Amir; Boccara, Claude; Gennisson, Jean-Luc; Tanter, Mickael; Pernot, Mathieu

2014-11-01

Shear wave elastography imaging techniques provide quantitative measurement of soft tissues elastic properties. Tendons, muscles and cerebral tissues are composed of fibers, which induce a strong anisotropic effect on the mechanical behavior. Currently, these tissues cannot be accurately represented by existing elastography phantoms. Recently, a novel approach for orthotropic hydrogel mimicking soft tissues has been developed (Millon et al 2006 J. Biomed. Mater. Res. B 305-11). The mechanical anisotropy is induced in a polyvinyl alcohol (PVA) cryogel by stretching the physical crosslinks of the polymeric chains while undergoing freeze/thaw cycles. In the present study we propose an original multimodality imaging characterization of this new transverse isotropic (TI) PVA hydrogel. Multiple properties were investigated using a large variety of techniques at different scales compared with an isotropic PVA hydrogel undergoing similar imaging and rheology protocols. The anisotropic mechanical (dynamic and static) properties were studied using supersonic shear wave imaging technique, full-field optical coherence tomography (FFOCT) strain imaging and classical linear rheometry using dynamic mechanical analysis. The anisotropic optical and ultrasonic spatial coherence properties were measured by FFOCT volumetric imaging and backscatter tensor imaging, respectively. Correlation of mechanical and optical properties demonstrates the complementarity of these techniques for the study of anisotropy on a multi-scale range as well as the potential of this TI phantom as fibrous tissue-mimicking phantom for shear wave elastographic applications.

Composite films based on biorelated agro-industrial waste and poly(vinyl alcohol). Preparation and mechanical properties characterization.

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Chiellini, E; Cinelli, P; Imam, S H; Mao, L

2001-01-01

As a part of an ongoing project on the production of composite materials based on poly(vinyl alcohol) (PVA) and polymeric materials from renewable resources, the present paper reports on the incorporation of agricultural waste materials as organic fillers in a film matrix based on PVA as continuous phase. In this study lignocellulosic fibers byproducts, derived from sugar cane (SC) and apple (AP) and orange (OR) fruit juice extraction, were cast from PVA aqueous solutions. The effect of fiber type and composition on the relative properties of cast films was evaluated and compared. OR resulted to be suitable for blending in higher amounts by weight than SC and AP. Glycerol and urea were added as plasticizing agents and were observed to be effective in giving flexible films. Additionally, cornstarch was added to further increase the composition of polymers from renewable resources in cost-effective and ecoefficient composite film formulations. The prepared films resulted sensitive to moisture and water. To reduce water sensitivity, hexamethoxymethylmelamine (HMMM) was tested as a cross-linking agent for the present composite formulations. Cross-linked films exhibited significant improvement in water-resistance that can be taken as a tuneable structural feature for customized applications. The mechanical properties of the prepared composite films (elongation at break, tensile strength, Young modulus) were found to be dependent upon the nature and content of the filler and on environmental conditions.

Electrospinning of poly(vinyl alcohol) nanofibers loaded with hexadecane nanodroplets.

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Arecchi, A; Mannino, S; Weiss, J

2010-08-01

The feasibility of producing poly(vinyl alcohol) (PVA) nanofibers containing fine-disperse hexadecane droplets by electrospinning a blend of hexadecane-in-water emulsions and PVA was investigated. Hexadecane oil-in-water nanoemulsions (d(10)= 181.2 +/- 0.1 nm) were mixed with PVA at pH 4.5 to yield polymer-emulsion blends containing 0.5 to 1.5 wt% oil droplets and 8-wt% PVA. The solution properties of emulsions and emulsion-PVA blends (viscosity, conductivity, surface tension) were determined. Solutions were electrospun and the morphology and thermal properties of deposited fiber mats characterized by scanning electron microscopy and differential scanning calorimetry. Fiber mats were dissolved in buffer to liberate incorporated hexadecane droplets and the buffer solutions analyzed by optical microscopy, UV-spectroscopy, and light scattering. Analysis of dry fiber mats and their solutions showed that emulsion droplets were indeed part of the electrospun fiber structures. Depending on the concentration of hexadecane in the initial emulsion-polymer blends, droplets were dispersed in the fibers as individual droplets or in form of aggregated flocs of hexadecane droplets. Nanofibers with spindle-like perturbations or nanofibers containing bead-like structures with approximately 5 times larger than the size of droplets in the original nanoemulsion were obtained. Remarkably, incorporation of hexadecane droplets in fibers did not alter size of individual droplets, that is, no coalescence occurred. The manufacture of solid matrix containing nanodroplets could be of substantial interest for manufacturers wishing to develop encapsulation system for lipophilic functional compounds such as lipid-soluble flavors, antimicrobials, antioxidants, and bioactives with tailored release kinetics. Practical Applications: The paper describes the formation of electrospun nanofibers from hydrophilic polymers that contain fine-disperse emulsion droplets. By incorporating emulsion droplets, a

New multifunctional materials obtained by the intercalation of anionic dyes into layered zinc hydroxide nitrate followed by dispersion into poly(vinyl alcohol) (PVA).

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Marangoni, Rafael; Ramos, Luiz Pereira; Wypych, Fernando

2009-02-15

Different anionic blue and orange dyes have been immobilized on a zinc hydroxide nitrate (Zn(5)(OH)(8)(NO(3))(2)nH(2)O--Zn-OH-NO(3)) by anion exchange with interlayer and/or outer surface nitrate ions of the layered matrix. Orange G (OG) was totally intercalated, orange II (OII) was partially intercalated, while Niagara blue 3B (NB) and Evans blue (EV) were only adsorbed at the outer surface. Several composite films of poly(vinyl alcohol)--PVA were prepared by casting through the dispersion of the hybrid material (Zn-OH-OG) into a PVA aqueous solution and evaporation of water in a vacuum oven. The obtained composite films were transparent, colored, and capable of absorbing UV radiation. Improved mechanical properties were also obtained in relation to the nonfilled PVA films. These results demonstrate the onset of a new range of potential applications for layered hydroxide salts in the preparation of polymer composite multifunctional materials.

Modifying the MRI, elastic stiffness and electrical properties of polyvinyl alcohol cryogel using irradiation

International Nuclear Information System (INIS)

Goharian, Mehran; Moran, Gerald R.; Wilson, Kyle; Seymour, Colin; Jegatheesan, Aravinthan; Hill, Michael; Thompson, R. Terry; Campbell, Gordon

2007-01-01

The aim of this work was to study the effect of radiation on the elastic stiffness, electrical and MRI properties of polyvinyl alcohol (PVA)-based cryogel (PVA-C). The PVA-C samples were irradiated with a 60 C0 γ-source, at 2.18 x 10 6 Rads. The indentation measurements (an indication of elastic stiffness) reduced by about 14.6% for PVA-3C and 5.7% PVA-6C after irradiation, indicating that the material became harder/stiffer. It was found that MRI relaxation times provide an alternative and non-destructive method to evaluate the radiation effect on PVA-C. The T 1 of PVA-C that had undergone three freeze thaw cycles decreased with irradiation by 10%, 25% and 35% at 1 T, 1.89 T and 3 T respectively. The T 1 of PVA-C that had undergone six freeze thaw cycles decreased with irradiation by 18%, 15% and 11% at 1 T, 1.89 T and 3 T respectively. The T 2 of PVA-C decreased with irradiation only at 1T, however this change is hypothesized to be due to the interaction of two spin pools in the gel. The electrical conductivity (σ) and permittivity constant (ε) of the unirradiated and γ-irradiated PVA-C samples were measured at different frequencies in the range 40 Hz to 1 MHz. The results demonstrated that the conductivity increased with irradiation by 50% for PVA-3C (three freeze thaw cycles) and 75% for PVA-6C (six freeze thaw cycles) at frequencies greater than 1 KHz.The permittivity decreased with irradiation up to 25% for 3C and 35% for 6C at frequencies less than 1 KHz

Trisacryl Gelatin Microspheres Versus Polyvinyl Alcohol Particles in the Preoperative Embolization of Bone Neoplasms

International Nuclear Information System (INIS)

Basile, Antonio; Rand, Thomas; Lomoschitz, Fritz; Toma, Cyril; Lupattelli, Tommaso; Kettenbach, Joachim; Lammer, Johannes

2004-01-01

The aim of this study was to compare the efficacy of trisacryl gelatin microspheres versus polyvinyl alcohol particles (PVA) in the preoperative embolization of bone neoplasms, on the basis of intraoperative blood loss quantified by the differences in preoperative and postoperative hematic levels of hemoglobin, hematocrit and erythrocytes count. From January 1997 to December 2002, preoperative embolization of bone tumors (either primary or secondary) was carried out in 49 patients (age range 12/78), 20 of whom were treated with trysacril gelatin microspheres (group A) and 29 with PVA particles (group B). The delay between embolization and surgery ranged from 1 to 13 days in group A and 1 to 4 days in group B. As used in international protocols, we considered hematic levels of hemoglobin, hematocrit and erythrocytes count for the measurement of intraoperative blood loss then the differences in pre- and postoperative levels were used as statistical comparative parameters. We compared the values of patients treated with embospheres (n = 10) and PVA (n = 18) alone, and patients treated with (group A = 10; group B = 11) versus patients treated without other additional embolic materials in each group (group A = 10; group B = 18). According to the Student's t-test (p < 0.05), the difference of hematic parameters between patients treated by embospheres and PVA alone were significant; otherwise there was no significant difference between patients treated with only one embolic material (embospheres and PVA) versus those treated with other additional embolic agents in each group. The patients treated with microspheres had a minor quantification of intraoperative blood loss compared to those who received PVA particles. Furthermore, they had a minor increase of bleeding related to the delay time between embolization and surgery. The use of additional embolic material did not improve the efficacy of the procedure in either group of patients

The effects of addition of poly(vinyl) alcohol (PVA) as a green corrosion inhibitor to the phosphate conversion coating on the anticorrosion and adhesion properties of the epoxy coating on the steel substrate

Energy Technology Data Exchange (ETDEWEB)

Ramezanzadeh, B., E-mail: ramezanzadeh-bh@icrc.ac.ir; Vakili, H.; Amini, R.

2015-02-01

Highlights: • Room temperature zinc phosphate coating was applied on the surface of steel sample. • Poly(vinyl) alcohol was added to the phosphating bath as a green corrosion inhibitor. • The adhesion and anticorrosion properties of the epoxy coating were investigated. • PVA decreased the phosphate crystal size and porosity. • PVA enhanced the corrosion protection and adhesion properties of the epoxy coating. - Abstract: Steel substrates were chemically treated by room temperature zinc phosphate conversion coating. Poly(vinyl) alcohol (PVA) was added to the phosphate solution as a green corrosion inhibitor. Finally, the epoxy/polyamide coating was applied on the untreated and surface treated steel samples. The effects of PVA on the morphological properties of the phosphate coating were studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measuring device. The adhesion properties of the epoxy coatings applied on the surface treated samples were investigated by pull-off and cathodic delamination tests. Also, the anticorrosion properties of the epoxy coatings were studied by electrochemical impedance spectroscopy (EIS). Results showed that addition of PVA to the phosphate coating increased the population density of the phosphate crystals and decreased the phosphate grain size. The contact angle of the steel surface treated by Zn-PVA was lower than Zn treated one. The corrosion resistance of the epoxy coating was considerably increased on the steel substrate treated by zinc phosphate conversion coating containing PVA. PVA also enhanced the adhesion properties of the epoxy coating to the steel surface and decreased the cathodic delamination significantly.

Effect of starch isolation method on properties of sweet potato starch

Directory of Open Access Journals (Sweden)

A. SURENDRA BABU

2014-08-01

Full Text Available Isolation method of starch with different agents influences starch properties, which provide attention for studying the most appropriate method for isolation of starch. In the present study sweet potato starch was isolated by Sodium metabisulphate (M1, Sodium chloride (M2, and Distilled water (M3 methods and these were assessed for functional, chemical, pasting and structural properties. M3 yielded the greatest recovery of starch (10.20%. Isolation methods significantly changed swelling power and pasting properties but starches exhibited similar chemical properties. Sweet potato starches possessed C-type diffraction pattern. Small size granules of 2.90 μm were noticed in SEM of M3 starch. A high degree positive correlation was found between ash, amylose, and total starch content. The study concluded that isolation methods brought changes in yield, pasting and structural properties of sweet potato starch.

An intensive study on the optical, rheological, and electrokinetic properties of polyvinyl alcohol-capped nanogold

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Behera, Manoranjan

2015-05-01

Low-temperature-assisted wet chemical synthesis of nanogold (NG) using gold hydroxide, a new precursor salt in the presence of a macroscopic ligand poly(vinyl alcohol) PVA in water in the form of nanofluid, is reported for the first time in this article. In the absorption spectra, the surface Plasmon resonance absorption band in the range of 520-545 nm signifies the formation of NG via a controlled Au3+ + 3e → Au reaction grafted in small assemblies with polymer. Absorption maximum increases nonlinearly with Au-contents up to 100 µM Au in Au-PVA charge-transfer complex. Marked enhancement in the peak intensity of some of the vibration bands of PVA polymer such as C-H stretching, C=O stretching, CH2 bending, and C-C in-plane bending in the presence of NG reveals an interfacial interaction between NG and oxidized PVA via C=O group. Execution of shear thinning behavior regardless of the Au-content strongly suggests that crosslinking exists between NG and PVA in Au-PVA rheo-optical nanofluids. Hydrodynamic diameter and polydispersity index draw a nonlinear path with the Au doping with 30.0 g/L PVA in water over a wide region of 5-100 μM Au covered in this study. Enhancement in the zetapotential of Au-PVA nanofluid over bare PVA in water is ascribed to buildup of nonbonding electrons of "-C=O" moieties from the oxidized PVA on the NG surface. Displaying of lattice fringes in the microscopic image of core-shell Au-PVA nanostructure confirms that crystalline nature of NG core with inter planar spacing 0.235 nm corresponds to Au (111) plane.

Composite Scaffold of Poly(Vinyl Alcohol) and Interfacial Polyelectrolyte Complexation Fibers for Controlled Biomolecule Delivery

Science.gov (United States)

Cutiongco, Marie Francene A.; Choo, Royden K. T.; Shen, Nathaniel J. X.; Chua, Bryan M. X.; Sju, Ervi; Choo, Amanda W. L.; Le Visage, Catherine; Yim, Evelyn K. F.

2015-01-01

Controlled delivery of hydrophilic proteins is an important therapeutic strategy. However, widely used methods for protein delivery suffer from low incorporation efficiency and loss of bioactivity. The versatile interfacial polyelectrolyte complexation (IPC) fibers have the capacity for precise spatiotemporal release and protection of protein, growth factor, and cell bioactivity. Yet its weak mechanical properties limit its application and translation into a viable clinical solution. To overcome this limitation, IPC fibers can be incorporated into polymeric scaffolds such as the biocompatible poly(vinyl alcohol) hydrogel (PVA). Therefore, we explored the use of a composite scaffold of PVA and IPC fibers for controlled biomolecule release. We first observed that the permeability of biomolecules through PVA films were dependent on molecular weight. Next, IPC fibers were incorporated in between layers of PVA to produce PVA–IPC composite scaffolds with different IPC fiber orientation. The composite scaffold demonstrated excellent mechanical properties and efficient biomolecule incorporation. The rate of biomolecule release from PVA–IPC composite grafts exhibited dependence on molecular weight, with lysozyme showing near-linear release for 1 month. Angiogenic factors were also incorporated into the PVA–IPC grafts, as a potential biomedical application of the composite graft. While vascular endothelial growth factor only showed a maximum cumulative release of 3%, the smaller PEGylated-QK peptide showed maximum release of 33%. Notably, the released angiogenic biomolecules induced endothelial cell activity thus indicating retention of bioactivity. We also observed lack of significant macrophage response against PVA–IPC grafts in a rabbit model. Showing permeability, mechanical strength, precise temporal growth factor release, and bioinertness, PVA–IPC fibers composite scaffolds are excellent scaffolds for controlled biomolecule delivery in soft tissue

Composite scaffold of poly(vinyl alcohol) and interfacial polyelectrolyte complexation fibers for controlled biomolecule delivery.

Science.gov (United States)

Cutiongco, Marie Francene A; Choo, Royden K T; Shen, Nathaniel J X; Chua, Bryan M X; Sju, Ervi; Choo, Amanda W L; Le Visage, Catherine; Yim, Evelyn K F

2015-01-01

Controlled delivery of hydrophilic proteins is an important therapeutic strategy. However, widely used methods for protein delivery suffer from low incorporation efficiency and loss of bioactivity. The versatile interfacial polyelectrolyte complexation (IPC) fibers have the capacity for precise spatiotemporal release and protection of protein, growth factor, and cell bioactivity. Yet its weak mechanical properties limit its application and translation into a viable clinical solution. To overcome this limitation, IPC fibers can be incorporated into polymeric scaffolds such as the biocompatible poly(vinyl alcohol) hydrogel (PVA). Therefore, we explored the use of a composite scaffold of PVA and IPC fibers for controlled biomolecule release. We first observed that the permeability of biomolecules through PVA films were dependent on molecular weight. Next, IPC fibers were incorporated in between layers of PVA to produce PVA-IPC composite scaffolds with different IPC fiber orientation. The composite scaffold demonstrated excellent mechanical properties and efficient biomolecule incorporation. The rate of biomolecule release from PVA-IPC composite grafts exhibited dependence on molecular weight, with lysozyme showing near-linear release for 1 month. Angiogenic factors were also incorporated into the PVA-IPC grafts, as a potential biomedical application of the composite graft. While vascular endothelial growth factor only showed a maximum cumulative release of 3%, the smaller PEGylated-QK peptide showed maximum release of 33%. Notably, the released angiogenic biomolecules induced endothelial cell activity thus indicating retention of bioactivity. We also observed lack of significant macrophage response against PVA-IPC grafts in a rabbit model. Showing permeability, mechanical strength, precise temporal growth factor release, and bioinertness, PVA-IPC fibers composite scaffolds are excellent scaffolds for controlled biomolecule delivery in soft tissue engineering.

Preparation of starch nanoparticles in water in oil microemulsion system and their drug delivery properties.

Science.gov (United States)

Wang, Xinge; Chen, Haiming; Luo, Zhigang; Fu, Xiong

2016-03-15

In this research, 1-hexadecyl-3-methylimidazolium bromide C16mimBr/butan-1-ol/cyclohexane/water ionic liquid microemulsion was prepared. The effects of n-alkyl alcohols, alkanes, water content and temperature on the properties of microemulsion were studied by dilution experiment. The microregion of microemulsion was identified by pseudo-ternary phase diagram and conductivity measurement. Then starch nanoparticles were prepared by water in oil (W/O) microemulsion-cross-linking methods with C16mimBr as surfactant. Starch nanoparticles with a mean diameter of 94.3nm and narrow size distribution (SD=3.3) were confirmed by dynamic light scattering (DLS). Scanning electron microscope (SEM) data revealed that starch nanoparticles were spherical granules with the size about 60nm. Moreover the results of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) demonstrated the formation of cross-linking bonds in starch molecules. Finally, the drug loading and releasing properties of starch nanoparticles were investigated with methylene blue (MB) as drug model. This work may provide an efficient pathway to synthesis starch nanoparticles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Eco-friendly polyvinyl alcohol/carboxymethyl cellulose hydrogels reinforced with graphene oxide and bentonite for enhanced adsorption of methylene blue.

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Dai, Hongjie; Huang, Yue; Huang, Huihua

2018-04-01

Eco-friendly polyvinyl alcohol/carboxymethyl cellulose (isolated from pineapple peel) hydrogels reinforced with graphene oxide and bentonite were prepared as efficient adsorbents for methylene blue (MB). The structure and morphology of the prepared hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and differential scanning calorimetry (DSC). Introducing graphene oxide and bentonite into the hydrogels evidently enhanced the thermal stability, swelling ability and MB adsorption capacity. The effects of initial concentration of MB, pH, contact time and temperature on MB adsorption capacity of the prepared hydrogels were investigated. Adsorption kinetics and equilibrium adsorption isotherm fitted pseudo-second-order kinetic model and Langmuir isotherm model well, respectively. After introducing graphene oxide and bentonite into the hydrogels, the maximum adsorption capacity calculated from the Langmuir isotherm model reached 172.14 mg/g at 30 °C, obviously higher than the hydrogels prepared without these additions (83.33 mg/g). Furthermore, all the prepared hydrogels also displayed good reusability for the efficient removal of MB. Consequently, the prepared hydrogels could be served as eco-friendly, stable, efficient and reusable adsorbents for anionic dyes in wastewater treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrasonic-assisted synthesis of polyvinyl alcohol/phytic acid polymer film and its thermal stability, mechanical properties and surface resistivity.

Science.gov (United States)

Li, Jihui; Li, Yongshen; Song, Yunna; Niu, Shuai; Li, Ning

2017-11-01

In this paper, polyvinyl alcohol/phytic acid polymer (PVA/PA polymer) was synthesized through esterification reaction of PVA and PA in the case of acidity and ultrasound irradiation and characterized, and PVA/PA polymer film was prepared by PVA/PA polymer and characterized, and the influence of dosage of PA on the thermal stability, mechanical properties and surface resistivity of PVA/PA polymer film were researched, and the influence of sonication time on the mechanical properties of PVA/PA polymer film was investigated. Based on those, it was concluded that the hydroxyl group on the chain of PVA and the phosphonic group on PA were connected together in the form of phosphonate bond, and the hydroxyl group on the chain of PVA were connected together in the form of ether bond after the intermolecular dehydration; in the meantime, it was also confirmed that PVA/PA polymer film prepared from 1.20mL of PA not only had the high thermal stability and favorable ductility but also the low surface resistivity in comparison with PVA/PA polymer film with 0.00mL of PA, and the ductility of PVA/PA polymer film was very sensitive to the sonication time. Copyright © 2017. Published by Elsevier B.V.

Formulation of Polyherbal Patches Based on Polyvinyl Alcohol and Hydroxypropylmethyl Cellulose: Characterization and In Vitro Evaluation.

Science.gov (United States)

Suksaeree, Jirapornchai; Nawathong, Noramon; Anakkawee, Rinrada; Pichayakorn, Wiwat

2017-10-01

The purpose of this research was to prepare and characterize polyherbal patches made from polyvinyl alcohol (PVA) and hydroxypropylmethyl cellulose (HPMC) with glycerine as a plasticizer. Polyherbal extracts were Luk-Pra-Kob recipes extracted with 95% ethanol. They were prepared by mixing the polymer solutions and glycerine in a beaker; subsequently, the polyherbal extracts were homogeneously mixed. Then, they were transferred into a Petri dish and dried in a hot-air oven at 70 ± 2°C for 5 h. The dry polyherbal patches were evaluated for physicochemical properties by Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and a scanning electron microscope. They were studied for in vitro release and skin permeation of the marker active compound (E)-4-(3',4'-dimethoxyphenyl)but-3-en-l-ol (compound D) using a modified Franz-type diffusion cell. The polyherbal patches made from PVA as a matrix layer were homogeneous, smooth, and compact relative to HPMC-containing polyherbal patches. The selected polyherbal patches made from PVA produced a release profile with an initial burst effect in which compound D release was 74.21 ± 6.13% within 8 h, but compound D could permeate the pig skin only 37.28 ± 5.52% and was highly accumulated in newborn pig skin at 35.90 ± 6.72%. The in vitro release and skin permeation kinetics of compound D were fitted to the Higuchi model. The polyherbal patches made from PVA could be suitably used for herbal medicine application.

Radiation Synthesis and Characterization of Polyvinyl alcohol/Acrylic acid Hydrogel and its Amoxicillin drug Delivery application

International Nuclear Information System (INIS)

El kelesh, N.A.; Ismail, S.A.; Abd El Wahab, S.Y.

2012-01-01

Polyvinyl alcohol /Acrylic acid based hydrogels can be synthesized by Gamma radiation technique using 60 Co irradiation cell at irradiation dose rate 1.8 Gray/second. The optimum conditions of hydrogel preparation takes place at different factors such as composition ratios of PVA/AAc, different comonomer concentration and different irradiation doses resulting in hydrogel with maximum gel percent as it obtained 98%. The structures of hydrogels were characterized by FTIR analysis. The results can be confirmed the expected structures as well as free radical copolymerization. According to the swelling studies, hydrogels with high content of AAc gave relatively high swelling percent. The hydrogel showed a super adsorbent with swelling capacity 10320 %. Water diffusion into such prepared hydrogel showed a non-Fickian type where a Fickian number was 0.77. This hydrogel was used for the adsorption of amoxicillin drug from their aqueous solutions. The factors affected on the uptake conditions such as ph, time and initial feed concentration on the amoxicillin adsorption capacity of hydrogel was studied depending on Freundlish model of adsorption isotherm.. It was observed that the interaction between drug and ionic comonomers was enhanced in alkaline medium and high initial feed concentration of the drug. The ability of the hydrogel and the affinity of the drug to be adsorbed can be cleared by determining the empirical constants n and k respectively from the logarithmic form of Freundlish equation. The recovery of drug was also investigated in different ph values to study the suitable condition of drug release as drug delivery system.

Preparation and antibacterial activities of chitosan-gallic acid/polyvinyl alcohol blend film by LED-UV irradiation.

Science.gov (United States)

Yoon, Soon-Do; Kim, Young-Mog; Kim, Boo Il; Je, Jae-Young

2017-11-01

Active blend films from chitosan-gallic acid (CGA) and polyvinyl alcohol (PVA) were prepared via a simple mixing and casting method through the addition of citric acid as a plasticizer. The CGA/PVA blend films were characterized using Fourier transform infrared spectroscopy (FT-IR). The mechanical properties including tensile strength (TS) and elongation at break (%E), degree of solubility (S) and swelling behavior (DS), water vapor adsorption, and antimicrobial activities of the CGA/PVA blend films with and without LED (light emitting diode)-UV irradiation were also investigated. The CGA/PVA blend films exposed to UV irradiation exerted a higher TS (43.5MPa) and lower %E (50.40), S (0.38) and DS (2.73) compared to the CGA/PVA blend films (TS=41.7MPa, %E=55.40, S=0.42, and DS=3.16) not exposed LED-UV irradiation, indicating that the cross-linkage between CGA and PVA had been strengthened by LED-UV irradiation. However, the water vapor adsorption in the CGA/PVA blend films increased due to the changes of surface roughness and pore volume after LED-UV irradiation, and all values increased by increasing the CGA concentrations in the CGA/PVA blend films. The antimicrobial activities of the CGA/PVA blend films showed that the efficient concentration of CGA in the CGA/PVA blend films was over 1.0%. Taken together, the CGA/PVA blend films have potential for use as food packing materials. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of hydroxyapatite addition on the mechanical properties of polyvinyl alcohol/chitosan biomaterials for bone scaffolds application