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Sample records for electrolytes synthesis rheology

  1. Electrolytic Synthesis and Characterizations of Silver Nanopowder

    OpenAIRE

    Theivasanthi, T.; Alagar, M.

    2011-01-01

    This work reports a simple, novel, cost effective and eco-friendly electrolytic synthesis of silver nanoparticles using AgNO3 as metal precursor. The synthesis rate is much faster than other methods and this approach is suitable for large scale production. They are characterized by XRD, SEM and FT-IR techniques to analyze size, morphology and functional groups. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles. Their particle size is found to ...

  2. Electrolytic Synthesis and Characterizations of Silver Nanopowder

    CERN Document Server

    Theivasanthi, T

    2011-01-01

    This work reports a simple, novel, cost effective and eco-friendly electrolytic synthesis of silver nanoparticles using AgNO3 as metal precursor. The synthesis rate is much faster than other methods and this approach is suitable for large scale production. They are characterized by XRD, SEM and FT-IR techniques to analyze size, morphology and functional groups. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles. Their particle size is found to be 24 nm and specific surface area (SSA) is 24 m2/g. Analysis of Ag nanoparticles SSA reports that increasing their SSA improves their antibacterial actions. Microbiology assay founds that Ag nanoparticles are effective against E.coli and B.megaterium bacteria. SSA of bacteria analysis reveals that it plays a major role while reacting with antimicrobial agents.

  3. The rheology of oxide dispersions and the role of concentrated electrolyte solutions

    International Nuclear Information System (INIS)

    Stability control of particulate dispersions is critical to a wide range of industrial processes. In the UK nuclear industry, significant volumes of waste materials arising from the corrosion products of Magnox fuel rods currently require treatment and storage. The majority of this waste is present as aqueous dispersions of oxide particulates. Treatment of these dispersions will require a variety of unit operations including mobilisation, transport and solid- liquid separation. Typically these processes must operate across a narrow optimal range of pH and the dispersions are, almost without exception, found in complex electrolyte conditions of high overall concentration. Knowledge of the behaviour of oxides in various electrolyte conditions and over a large pH range is essential for the efficient design and control of any waste processing approach. The transport properties of particle dispersions are characterised by the rheological properties. It is well known that particle dispersion rheology is strongly influenced by particle-particle interaction forces, and that particle-particle interactions are strongly influenced by adsorbed ions on the particle surfaces. Here we correlate measurements of the shear yield stress and the particle zeta potentials to provide insight as to the role of ions in moderating particle interactions. The zeta potential of model TiO2 suspensions were determined (Colloidal Dynamics Zeta Probe) over a range of pH for a series of alkbe) over a range of pH for a series of alkali metal halides and quaternary ammonium halides at a range of solution concentrations (0.001 M - 1 M). The results show some surprising co-ion effects at high electrolyte concentrations (>0.5 M) and indicate that even ions generally considered to be indifferent induce a shift in iso-electric point (i.e.p.) which is inferred as being due to specific adsorption of ions. The shear yield stress values of concentrated titania dispersions were measured using a Bohlin C-VOR stress controlled rheometer. The shear yield stress of a material is defined as the minimum applied shear stress required to induce flow. The yield stress vs. pH curves obtained reflected the shifts in i.e.p. seen in the zeta potential results. Interestingly, specific ion adsorption results in an unexplained increase in the value of the yield stress over that expected for simple systems with no such interfacial ion adsorption. Possible reasons for this effect such as ion-ion correlation effects are discussed. The importance of this increased attraction for the mobilisation of settled solids in an aqueous environment and especially the likely effects on the treatment of Magnox fuel waste materials is discussed. (authors)

  4. Synthesis and characterizations of novel polymer electrolytes

    Science.gov (United States)

    Chanthad, Chalathorn

    Polymer electrolytes are an important component of many electrochemical devices. The ability to control the structures, properties, and functions of polymer electrolytes remains a key subject for the development of next generation functional polymers. Taking advantage of synthetic strategies is a promising approach to achieve the desired chemical structures, morphologies, thermal, mechanical, and electrochemical properties. Therefore, the major goal of this thesis is to develop synthetic methods for of novel proton exchange membranes and ion conductive membranes. In Chapter 2, new classes of fluorinated polymer- polysilsesquioxane nanocomposites have been designed and synthesized. The synthetic method employed includes radical polymerization using the functional benzoyl peroxide initiator for the telechelic fluorinated polymers with perfluorosulfonic acids in the side chains and a subsequent in-situ sol-gel condensation of the prepared triethoxylsilane-terminated fluorinated polymers with alkoxide precursors. The properties of the composite membranes have been studied as a function of the content and structure of the fillers. The proton conductivity of the prepared membranes increases steadily with the addition of small amounts of the polysilsesquioxane fillers. In particular, the sulfopropylated polysilsesquioxane based nanocomposites display proton conductivities greater than Nafion. This is attributed to the presence of pendant sulfonic acids in the fillers, which increases ion-exchange capacity and offers continuous proton transport channels between the fillers and the polymer matrix. The methanol permeability of the prepared membranes has also been examined. Lower methanol permeability and higher electrochemical selectivity than those of Nafion have been demonstrated in the polysilsesquioxane based nanocomposites. In Chapter 3, the synthesis of a new class of ionic liquid-containing triblock copolymers with fluoropolymer mid-block and imidazolium methacrylate end-blocks is described for the first time. The synthetic strategy involves the preparation of the telechelic fluoropolymers using a functional benzoyl peroxide initiator as the macro-chain transfer agent for subsequent RAFT polymerization of the imidazolium methacrylate monomer. As revealed in DSC, SAXS and dielectric relaxation spectroscopy (DRS) measurements, there was no microphase separation in the triblock copolymers, likely due to solubility of ionic liquid moieties in the fluoropolymer matrix. The anionic counterion has direct impact on the thermal properties, ionic conductivity and segmental dynamics of the polymers. The temperature dependence of the ionic conductivity is well described by the Vogel-Tamman-Fulcher model, suggesting that ion motion is closely coupled to segmental motion. In Chapter 4 and 5, new solid electrolytes for lithium cations have been synthesized by catalyzed hydrosilylation reaction involving hydrogen atoms of polysiloxane and polyhedral oligomeric silsesquioxane (POSS) and double bonds of vinyl tris17-bromo-3,6,9,12,15- pentaoxaheptadecan-1-ol silane. The obtained structures are based on branched or dendritic with ionic liquid-ethylene oxide oligomer. High room temperature ionic conductivities have been obtained in the range of 10-4-10-5 can be regarded as solid electrolytes. This is attributed to the high concentration of ions from ionic liquid moieties in the tripodand molecule, high segmental mobility, and high ion dissociation from ethylene oxide spacers. The influence of anion structures and lithium salts and concentration has been investigated.

  5. Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

    Directory of Open Access Journals (Sweden)

    MichaelStoukides

    2014-01-01

    Full Text Available Developed in the early 1900's, the “Haber-Bosch” synthesis is the dominant NH3 synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS, more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13×10?8 mol s?1 cm?2, obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe0.7Cu0.1Ni0.2O3, cathode. At high temperatures (>500oC the maximum rate was 9.5*10-9 mol s?1 cm?2 using Ce0.8Y0.2O2-? -[Ca3(PO42 -K3PO4] as electrolyte and Ag-Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level, are discussed.

  6. Synthesis of metal nanoparticles by electrolytical STM and electrochemical discharges

    OpenAIRE

    Lal, Ashwin

    2007-01-01

    As conventional fabrication techniques reach their limits novel techniques are needed for fabrication of structures in the nanometer range. This thesis investigates new methods to create metal nanostructures or nanoparticles with an STM tip or a sharp metal tool working inside an electrolyte. Electrochemical synthesis has the advantage that since deposition/etching are controlled by electrode potentials, it can be relatively simple to control and in addition STM allows in situ observation. Ma...

  7. Synthesis and rheological properties of an iron oxide ferrofluid

    International Nuclear Information System (INIS)

    A ferrofluid (FF) was synthesized in air using a co-precipitation method. Some rheological properties and magnetoviscous effects of this sample were studied. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used for characterization of the solid particles, and the rheological properties were investigated with a special rheometer with variable magnetic field. Magnetic particles with mean particle size of 10.6 nm were obtained. Rheological results show that the shear thinning behavior in the absence and presence of magnetic field is different from that based fluid behavior. Moreover, contrary to expectation, the magnetoviscous effect showed an initial increase at low shear rates (near 15 s-1) and decrease at higher shear rates. The rheological properties of FF depend on the rearrangement of nanoparticles. In addition, time is an effective factor in the formation and destruction of magnetically induced structures

  8. Carboxymethylation of Cassia angustifolia seed gum: synthesis and rheological study.

    Science.gov (United States)

    Rajput, Gaurav; Pandey, I P; Joshi, Gyanesh

    2015-03-01

    The seeds of Cassia angustifolia are a rich source of galactomannan gum. The seed gums possess a wide variety of industrial applications. To utilize C. angustifolia seed gum for broader industrial applications, the carboxymethyl-Cassia angustifolia seed gum (CM-CAG) was synthesized. The gum was etherified with sodium monochloroacetate (SMCA) in a methanol-water system in presence of alkali (NaOH) at different reaction conditions. The variables studied includes alkali concentration, SMCA concentration, methanol:water ratio, liquor:gum ratio, reaction temperature and time. The extent of carboxymethylation was determined as degree of substitution (DS). The optimum conditions for preparing CM-CAG (DS=0.474) comprised 0.100 mol of NaOH, 0.05 mol of SMCA, 80% of methanol:water ratio (as % methanol) and liquor:gum ratio (v/w) of 10:1 at 75 °C for 60 min using 0.03 mol (as AGU) of CAG. Rheological studies showed CM-CAG to exhibit non-Newtonian pseudoplastic behaviour, relatively high viscosity, cold water solubility and solution stability. PMID:25498663

  9. Synthesis of and characterization of lithium ceramic electrolytes

    Science.gov (United States)

    Rangasamy, Ezhiylmurugan

    The depleting fossil fuel reserves, rising oil prices and the need for reduction in CO2 emissions have created an unprecedented impetus for vehicle electrification. Lithium batteries have the highest energy density of the various available battery technologies. They are the most promising battery candidate to enable Hybrid Electric Vehicles (HEVs) and Plug-in Electric Vehicles (PEVs). However, current Li-ion current battery technology is costly and requires a significant increase in energy density to achieve range comparable to conventional gasoline-powered vehicles. Advanced lithium battery technologies such as Li-S and Li-O2 could potentially offer significant improvements in energy density to address the limitations with current Li-ion technology. The implementation of these advanced battery technologies, however, has been limited by the lack of electrolyte technology to enable the use of metallic lithium anodes. Thus, there is a clear and compelling need to develop new electrolyte materials that exhibit the unique combination of fast ion conductivity, stability against lithium, air and moisture. Lithium Lanthanum Titanium Oxide (LLTO) and Lithium Lanthanum Zirconium Oxide (LLZO) have been identified as viable candidates for the advanced battery technologies. However, issues concerning phase purity and densification warrant developing new and novel synthetic techniques. A single step procedure has been developed for the synthesis of Lithium Lanthanum Titanium Oxide (LLTO) membranes. The single step procedure combines phase formation and densification of the ceramic electrolyte in a hot pressing technique. The effect of synthetic technique on relative density, grain structure and ionic conductivity of the LLTO membranes has been explored in detail. The critical step of synthesizing cubic Lithium Lanthanum Zirconium Oxide (LLZO) has been systematically studied through the controlled doping of Al, using X-Ray Diffraction (XRD) analysis. Effects of Li and Al concentration on the crystal structure of LLZO were also studied in detail. Critical dopant concentration of Al to stabilize cubic LLZO was established during the course of this study. Systematic doping studies on the 24c site of La3+ in the primary lattice have also been explored in detail using XRD analysis to improve the ionic conductivity by maintaining the Li sub-lattice free of dopants. It is hypothesized that the supervalent substitutions create Li vacancies in the sub-lattice promoting disorder, thereby stabilizing cubic LLZO. While Ce4+ substitution for La3+ proved to be effective in synthesizing cubic LLZO, precipitation of Ce4+ observed under Backscattered electron (BSE) imaging limited its ionic conductivity. In an effort to develop flexible, solution-based synthetic techniques, two novel processes were established to prepare low dimensional, cubic LLZO powders. Hot pressing of the synthesized LLZO samples yielded high relative density (>95%) ceramic electrolyte membranes. Arrhenius studies using EIS to measure activation energy revealed and empirical relationship between the grain size and activation energy for dense LLZO membranes.

  10. Electrolytes and Electrodes for Electrochemical Synthesis of Ammonia

    DEFF Research Database (Denmark)

    Lapina, Alberto

    2013-01-01

    In order to make Denmark independent of fossil fuels by 2050 the share of renewable energy in electricity production, in particular wind energy, is expected to increase significantly. Since the power output of renewable energy sources heavily fluctuates over time there is a pressing need to find effective energy storage solutions. Production of synthetic fuels (e.g. ammonia) is a promising possibility. Ammonia (NH3) can be an interesting energy carrier, thanks to its high energy density and the existence of well developed storage and transportation technologies. However the present-day production technology is based on the Haber-Bosch process, which is energy intensive and requires large-scale plants. One possible way to produce ammonia from sustainable electricity, nitrogen and hydrogen/water is using an electrochemical cell. This thesis studies a number of electrolytes and electrocatalysts to evaluate their applicability to electrochemical synthesis of ammonia. First a number of potential electrolytes areinvestigated in the temperature range 25-400°C in order to find a proton conductor with a conductivity higher than 10-4 S/cm in dry atmosphere (pH2O < 0.001 atm). The conductivity of materials prepared from FeOOH nanoparticles is measured at 25-40°C between pH2O = 0.037 atm and pH2O < 0.001 atm. The conductivity is low in dry air (10-6-10-8 S/cm), while it can be up to 7·10-3 S/cm in wet air. The conductivity of Y-droped Ti, Si, Sn, Zr, Ce pyrophosphates, Gd-doped cerium phosphate and cerium pyrophosphate - KH2PO4 composite is measured at 100-400°C at pH2O from 0.2 atm to below 0.001 atm. The phase stability and long term conductivity of the compounds with the highest conductivities are investigated, and conductivity is found to depend heavily on pH2O and phosphorus content. High temperature solid state proton conductors are briefly reviewed and defect chemistry and partial conductivities of Y-doped BaZrO3-BaCeO3 solid solutions are studied as a function of temperature, pH2O and chemical compositions by means of defect chemistry modelling. BaCe0.2Zr0.6Y0.2O2.9 (BCZY26) is chosen as electrolyte, and used to fabricate symmetrical cells with composite metal-BCZY26 electrodes. Two metals (iron and molybdenum) are tested as electrocatalysts: the choice is based on the use of catalysts in the Haber-Bosch process and density functional theory calculations. The symmetrical cells are tested at OCV (i.e. without polarization) by impedance spectroscopy in dry H2/N2 and H2/Ar atmospheres, in the temperature range 440-650°C for Mo-BCZY electrodes and 350-500°C fir Fe-BCZY electrodes. No clear evidence of activity of Fe and Mo towards nitrogen reduction to ammonia is found. The kinetics of the electrode reaction (hydrogen oxidation/reduction) at the Mo-BCZY electrode are studied in detail by impedance spectroscopy to identify the electrode processes. Further studies carried out under polarization will be necessary in order to fully assess the potential of Fe and Mo as electrocatalysts for ammonia synthesis.

  11. Preparation and electrochemical properties of LiMn2O4 by a rheological-phase-assisted microwave synthesis method

    International Nuclear Information System (INIS)

    By using LiCO3 and MnO2, a rheological-phase-assisted microwave synthesis method has been applied in the fast preparation of spinel LiMn2O4 in order to reduce the cost of cathode materials. Comparing with the pristine LiMn2O4 obtained by the traditional solid-state reaction method, the structure and surface morphology of the samples synthesized by the rheological-phase-assisted microwave synthesis method have been investigated. The powders were used as positive materials for lithium-ion battery, whose charge/discharge properties and cycle performance have been examined in detail. As a result, the powders prepared by the rheological phase-assisted microwave synthesis method at 750 deg C are pure spinel LiMn2O4 with regular shapes and uniform distribution, which exhibit higher capacity and much better reversibility than the sample prepared by the traditional solid-state reaction

  12. Synthesis, rheology and forming of Y-Ba-Cu-O ceramics

    International Nuclear Information System (INIS)

    A chemical synthesis route is discussed which results in a low- temperature precursor to Y-Ba-Cu-O ceramics; it is based on use of molten Ba(OH)2·8H2O flux. Two different chemical systems have been examined; the first one, based on nitrate salts, has been demonstrated to be a viable precursor material for tape casting and extrusion; the second, made from acetate salts, has been used for powder synthesis and extrusion. Rheology of pastes shows that their flow may be fit to either Bingham Plastic or Hershel- Bulkley models. Yield stress is controlled in both pastes by volume fraction solids. Viscosity also follows solids loading in the paste. Shear thinning is controlled by colloidal nature of precursor. The paste has colloidal microstructure. Comparison of concentric cylinder rheometry and piston extrusion rheometry shows order of magnitude differences in yield stress, resulting from the test method and paste dilation

  13. Synthesis, rheology and forming of Y-Ba-Cu-O ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Green, T.M.

    1993-07-01

    A chemical synthesis route is discussed which results in a low- temperature precursor to Y-Ba-Cu-O ceramics; it is based on use of molten Ba(OH){sub 2}{center_dot}8H{sub 2}O flux. Two different chemical systems have been examined; the first one, based on nitrate salts, has been demonstrated to be a viable precursor material for tape casting and extrusion; the second, made from acetate salts, has been used for powder synthesis and extrusion. Rheology of pastes shows that their flow may be fit to either Bingham Plastic or Hershel- Bulkley models. Yield stress is controlled in both pastes by volume fraction solids. Viscosity also follows solids loading in the paste. Shear thinning is controlled by colloidal nature of precursor. The paste has colloidal microstructure. Comparison of concentric cylinder rheometry and piston extrusion rheometry shows order of magnitude differences in yield stress, resulting from the test method and paste dilation.

  14. Synthesis of a Magneto-Rheological vehicle suspension system built on the variable structure control approach

    Scientific Electronic Library Online (English)

    Leonardo Tavares, Stutz; Fernando Alves, Rochinha.

    2011-12-01

    Full Text Available The synthesis of a magneto-rheological vehicle suspension system built on the variable structure control approach is considered in the present work. The suspension is synthesized in order to improve the ride comfort obtained by a standard passive suspension. Although a nominal half-vehicle model wit [...] h rigid body is considered in the synthesis of the suspension, phenomenological models for the MR dampers and for the seat-driver subsystem, along with the flexibility of the vehicle body, are considered in the performance assessment. For comparison purposes, active and magneto-rheological suspensions built on the optimal control approach and an active suspension built on the variable structure control approach are also considered. The numerical results show that the proposed suspension outperforms the passive suspension and presents a performance comparable to that of the active ones when the vehicle body may be assumed as rigid. Besides, when its flexibility is an important issue, a great performance drop may be observed, depending on the road quality, the damper characteristics and the adopted control strategy.

  15. Microplasma synthesis on aluminum with additions of iron and nickel soluble complexes in electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Rogov, A.B., E-mail: alex-lab@bk.ru [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Mironov, I.V.; Terleeva, O.P.; Slonova, A.I. [Nikolaev Institute of Inorganic Chemistry. 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Alkaline homogeneous electrolyte with transition metals complexes. Black-Right-Pointing-Pointer Coatings contain metallic iron, nickel and their oxides in alumina-silica matrix. Black-Right-Pointing-Pointer Effect of Fe/Ni ratio on coatings properties and process characteristics. - Abstract: The microplasma synthesis of coatings containing iron and nickel from homogeneous electrolytes has been studied. For stabilization of transition metals in solution, it is proposed to use chelation. It was found that the synthesis of coatings using alternating current leads to the formation of metallic iron and nickel particles in addition to oxide phases. The iron and nickel complexes concentrations ratio in the electrolyte correlates with the coatings composition. Obtained coatings have been studied by scanning electron microscopy with X-ray microanalyser and by X-ray diffraction with Cu and Mo radiation. The metal content in the coating was determined spectrophotometrically from the absorption of iron thiocyanate complexes and nickel dimethylglyoxime complex.

  16. Solvothermal synthesis of gallium-indium-zinc-oxide nanoparticles for electrolyte-gated transistors.

    Science.gov (United States)

    Santos, Lídia; Nunes, Daniela; Calmeiro, Tomás; Branquinho, Rita; Salgueiro, Daniela; Barquinha, Pedro; Pereira, Luís; Martins, Rodrigo; Fortunato, Elvira

    2015-01-14

    Solution-processed field-effect transistors are strategic building blocks when considering low-cost sustainable flexible electronics. Nevertheless, some challenges (e.g., processing temperature, reliability, reproducibility in large areas, and cost effectiveness) are requirements that must be surpassed in order to achieve high-performance transistors. The present work reports electrolyte-gated transistors using as channel layer gallium-indium-zinc-oxide nanoparticles produced by solvothermal synthesis combined with a solid-state electrolyte based on aqueous dispersions of vinyl acetate stabilized with cellulose derivatives, acrylic acid ester in styrene and lithium perchlorate. The devices fabricated using this approach display a ION/IOFF up to 1 × 10(6), threshold voltage (VTh) of 0.3-1.9 V, and mobility up to 1 cm(2)/(V s), as a function of gallium-indium-zinc-oxide ink formulation and two different annealing temperatures. These results validates the usage of electrolyte-gated transistors as a viable and promising alternative for nanoparticle based semiconductor devices as the electrolyte improves the interface and promotes a more efficient step coverage of the channel layer, reducing the operating voltage when compared with conventional dielectrics gating. Moreover, it is shown that by controlling the applied gate potential, the operation mechanism of the electrolyte-gated transistors can be modified from electric double layer to electrochemical doping. PMID:25517251

  17. Synthesis and thermal behaviour of an amorphous solid polymer electrolyte

    OpenAIRE

    Barbosa, P. C.; Rodrigues, L. C.; Silva, Maria Manuela; Smith, Michael John; Costa, Marta Si?lvia Freitas Da

    2010-01-01

    In this study the synthesis of an amorphous polymer network, poly[oxymethylene-oligo(oxyethylene)], designated as aPEO, is described. This polymer has been characterized by gel permeation chromatography, thermal analysis, conductivity measurements, evaluation of electrochemical stability and nuclear magnetic resonance spectroscopy. The synthetic procedure developed permits partial fractionation of the product of the polymerization reaction. This linear macromolecule appears to be a promising ...

  18. Synthesis of novel acid electrolytes for phosphoric acid fuel cells

    Science.gov (United States)

    Adcock, James L.

    1988-11-01

    A 40 millimole per hour scale aerosol direct fluorination reactor was constructed. F-Methyl F-4-methoxybutanoate and F-4-methoxybutanoyl fluoride were synthesized by aerosol direct fluorination of methyl 4-methoxybutanoate. Basic hydrolysis of the perfluorinated derivatives produce sodium F-4 methoxybutanoate which was pyrolyzed to F-3-methoxy-1-propene. Purification and shipment of 33 grams of F-3-methoxy-1-propene followed. Syntheses by analogous methods allowed production and shipment of 5 grams of F-3-ethoxy 1-propene, 18 grams of F-3-(2-methoxy.ethoxy) 1-propene, and 37 grams of F-3,3-dimethyl 1-butene. Eighteen grams of F-2,2-dimethyl 1-chloropropane was produced directly and shipped. As suggested by other contractors, 5 grams of F-3-methoxy 1-iodopropane, and 5 grams of F-3-(2-methoxy.ethoxy) 1-iodopropane were produced by converting the respective precursor acid sodium salts produced for olefin synthesis to the silver salts and pyrolyzing them with iodine. Each of these compounds was prepared for the first time by the aerosol fluorination process during the course of the contract. These samples were provided to other Gas Research Institute (GRI) contractors for synthesis of perfluorinated sulfur (VI) and phosphorous (V) acids.

  19. Synthesis and investigation of electric conductivity of solid electrolytes in the LaF3-La2O3 system

    International Nuclear Information System (INIS)

    Synthesis and investigation of electroconductivity of solid electrolytes in the system LaF3-La2O3 have been carried out. Electronic conductivity has been estimated. The conclusion about pure ionic character of electroconductivity in the investigated solid electrolytes LaF3-La2O3 has been made. The range existence and temperatures of polymorphous phase transition of LaOnF3-2n have been found. 11 refs., 2 figs., 1 tab

  20. Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process

    CERN Document Server

    Shivagan, D D; Ekal, L A; Pawar, S H

    2003-01-01

    We report the multistep electrolytic process for the synthesis of high Tc single phase HgBa2Ca2Cu3O8+? (Hg-1223) superconducting films. The process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO films to convert into Hg1Ba2Ca2Cu3O8+? (Hg-1223). Films were characterized by thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrolytic intercalation of Hg in BaCaCuO precursor is proved to be a novel alternative to high temperature-high pressure mercuration process. The films are single phase Hg-1223 with Tc = 121.5 K and Jc = 4.3 x 104 A/cm2.

  1. Design and synthesis of new electrolyte systems for lithium-ion batteries

    Science.gov (United States)

    Chakrabarti, Amartya

    Rechargeable lithium-ion batteries are extensively used in consumer electronic products, including laptop computers, cellular phones, cameras, camcorders, and medical devices. They have great potential for application in electric and hybrid electric vehicles by virtue of their high energy and power density. Research and development in this direction have been focused all around the globe. The major challenges include the higher cost, safety issues related to the solvents, and conductivities at lower ambient temperature of the solvent-free solid polymer electrolyte (SPE) systems. In this dissertation, three different approaches are presented to achieve an improved electrolyte system for lithium-ion batteries. A plasticizer was synthesized and incorporated into a conventional poly(ethylene oxide) (PEO)-based solid polymer electrolyte system. The ambient temperature ionic conductivity observed at room temperature was noteworthy, due to the decrease of the glass transition temperature of the polymer. Secondly, a branched polymer was synthesized and used as the base matrix in SPEs. Polymers with a higher order of branching remained undissolved in common organic solvents, thereby limiting the scope of their use for making films for the study. The ones with a lower order of branching exhibited ionic conductivities comparable to regular PEO-based electrolytes. The third and most successful approach involved the strategic design and synthesis of a series of low lattice energy lithium salts and their chemical, thermal and electrochemical characterization. In this methodology, the two-to-three step synthetic strategy involved chlorosulfonation of an activated aromatic ring, reaction of the corresponding sulfonyl chloride with trifluoromethanesulfonamide in the presence of triethylamine as a base, followed by lithiation of the resulting triethylammonium salt to generate monolithium, dilithium and scaffolded polylithium salts. The mono- and dilithium salts were tested in electrolyte systems for SPEs, whereas the polylithium salts were characterized as potential candidates for liquid electrolyte systems. The tri-lithium salt based on triptycene proved to be the best of the lot. While all of them showed excellent thermal and electrochemical stability, the salt based on triptycene also demonstrated very good ambient temperature conductivity at low concentrations. The cycling characteristics observed, as well as lithium ion transference number measured with this salt, were impressive and equal to or exceed those for the currently best salt, lithium trifluromethanesulfonimide (LiTFSI).

  2. Towards the synthesis of hydroxyapatite/protein scaffolds with controlled porosities: bulk and interfacial shear rheology of a hydroxyapatite suspension with protein additives.

    Science.gov (United States)

    Maas, Michael; Bodnar, Pedro Marcus; Hess, Ulrike; Treccani, Laura; Rezwan, Kurosch

    2013-10-01

    The synthesis of porous hydroxyapatite scaffolds is essential for biomedical applications such as bone tissue engineering and replacement. One way to induce macroporosity, which is needed to support bone in-growth, is to use protein additives as foaming agents. Another reason to use protein additives is the potential to introduce a specific biofunctionality to the synthesized scaffolds. In this work, we study the rheological properties of a hydroxyapatite suspension system with additions of the proteins bovine serum albumin (BSA), lysozyme (LSZ) and fibrinogen (FIB). Both the rheology of the bulk phase as well as the interfacial shear rheology are studied. The bulk rheological data provides important information on the setting behavior of the thixotropic suspension, which we find to be faster with the addition of FIB and LSZ and much slower with BSA. Foam bubble stabilization mechanisms can be rationalized via interfacial shear rheology and we show that it depends on the growth of interfacial films at the suspension/air interface. These interfacial films support the stabilization of bubbles within the ceramic matrix and thereby introduce macropores. Due to the weak interaction of the protein molecules with the hydroxyapatite particles of the suspension, we find that BSA forms the most stable interfacial films, followed by FIB. LSZ strongly interacts with the hydroxyapatite particles and thus only forms thin films with very low elastic moduli. In summary, our study provides fundamental rheological insights which are essential for tailoring hydroxyapatite/protein suspensions in order to synthesize scaffolds with controlled porosities. PMID:23859812

  3. Synthesis of yttria-doped zirconia anodes and calcium-doped ceria electrolyte to fuel cell

    International Nuclear Information System (INIS)

    From the pursuit of lower operating temperature of fuel cells solid oxide was used polymeric precursor for the synthesis of reactive powder compositions Zr0,92Y0,08O2 for the anode and Ce0,88Ca0,12O2 for the electrolyte. The solutions were prepared using the metal in much of the composition and citric acid molar ratio of 1:3, under stirring at 60 deg C/1 h. The mixture of metallic citrates was subjected to agitation at a temperature of 80 deg C which was added ethylene glycol in the ratio 60:40 by weight citric acid / ethylene glycol, to form a resin that was pre-calcined at 300 deg C/3 h for to form the expanded resin. The powders were disaggregated in a mortar, screened and calcined at 400, 600 and 800 deg C/2 h. The powders were characterized by standard X-ray diffraction. (author)

  4. RHEOLOGICAL PHASE SYNTHESIS AND CHARACTERIZATION OF MICRO-SIZED Li4Ti5O12

    Scientific Electronic Library Online (English)

    LINGLING, XIE; XIAOYU, CAO; CHANGWEI, LIU; CHIWEI, WANG.

    Full Text Available SciELO Chile | Language: English Abstract in english Zero-strain anode material of Li4Ti5O12 for lithium ion battery was successfully synthesized via the rheological phase reaction (RPR) method. The as-prepared powders were characterized by means of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and particle size distribution analy [...] sis (PSD), and the electrochemical properties of the powders were evaluated by the galvanostatic discharge test and cyclic voltammetry (CV). The results revealed that well-crystallized uniform micro-sized Li4Ti5O12 powders were obtained at 800°C for different calcination times via the simple template-free rheological phase route. Among these RPR-derived Li4Ti5O12 powders, one synthesized at 800°C for 22 h displays the initial discharge capacity of 184.3 mAh/g and excellent characteristic of cyclic voltammetry.

  5. Synthesis and characterization of polyphosphazenes as polymer electrolytes for secondary lithium battery applications

    Science.gov (United States)

    Olmeijer, David L.

    This thesis describes the synthesis and characterization of polyphosphazenes as polymer electrolytes for secondary lithium battery applications. The polyphosphazenes that were synthesized include (a) species with linear and branched oligo(oxyethylene) side groups, (b) examples which incorporate crown ethers of various sizes, and (c) polymers which include sulfone or sulfoxide functional groups. Additional work involved the investigation of the factors that limit the cycle life of lithium-polymer secondary batteries. New polymers that contain either linear or branched oligo(oxyethylene) side-chains were synthesized. The polymers that bear linear side-chains have low glass transition temperatures and poor physical properties. The polymers with branched side-chains have similar glass transition temperatures, but have significantly improved bulk dimensional stabilities. The two systems have comparable ionic conductivities. Phosphazene polymers, bearing either 12-crown-4, 15-crown-5, or 18-crown-6 groups, either as single-substituent polymers or with 2-(2sp'-methoxyethoxy)ethoxy cosubstituents, were synthesized. The polymers in which all the side groups are crown ether units generate relatively low ionic conductivities at ambient temperatures. The ambient temperature ionic conductivity of the cosubstituent polyphosphazenes, as well as of MEEP, when complexed with MClOsb4 (M = Li, Na, K, Rb, Cs), was measured. The ionic conductivity is reduced when a favorable 1:1 or 2:1 crown ether-cation complex is formed. There is an increased glass transition temperature when a favorable 2:1 complex is formed. A synthetic method for the introduction of sulfone or sulfoxide functional groups into polyphosphazenes has been developed. This procedure involves the prior introduction of thioether groups followed by oxidation by Hsb2Osb2 or m-chloroperbenzoic acid. Oxidation of the sulfur atom results in polymers with relatively high glass transition temperatures. The potential of these materials as polymer electrolytes, both in the solid state or in systems with added propylene carbonate, was explored. The compatibility of polyphosphazene electrolytes with manganese (IV) oxide-based cathodes was investigated. Laminates of a solid polymer electrolyte (SMEP) between two MnOsb2-based intercalation cathodes were constructed. The cathodes were fabricated by solvent-casting and compression techniques. Both lambda-MnOsb2 and gamma-MnOsb2 were used. MEEP was the cathode binder material. Charge cycling was carried out and cell performance monitored by electrochemical impedance spectroscopy.

  6. Synthesis and electrochemical properties of tin oxide-based composite by rheological technique

    International Nuclear Information System (INIS)

    Novel rheological technique was developed to synthesize tin oxide-based composites. The microstructure, morphology, and electrochemical performance of the materials were investigated by X-ray diffraction, scanning electron microscopy and electrochemical methods. The particles of tin oxide-based materials form an inactive matrix. The average size of the particles is about 150 nm. The material delivers a charge capacity of more than 570 mAh g-1. The capacity loss per cycle is about 0.15% after being cycled 30 times. The good electrochemical performance indicates that this kind of tin oxide-based material is promising anode for lithium-ion battery

  7. Synthesis and electrolytic properties of phases based on calcium thiogadolinate as a function of method of the precursor synthesis

    International Nuclear Information System (INIS)

    Differently treated phases based on CaGd2S4 are studied by electrochemical methods. The range of solid solutions, electrolytic temperature interval, and averaged transport numbers for ions and electrons are determined. Compositions with best electrolytic properties are established. The origin of conduction in a CaGd2S4-based solid electrolyte is investigated. The obtained data show the phases to be sulfide-conducting solid electrolytes with a small share of cationic conduction

  8. Synthesis and ceramic processing of zirconia alumina composites for application as solid oxide fuel cell electrolytes

    International Nuclear Information System (INIS)

    The global warmness and the necessity to obtain clean energy from alternative methods than petroleum raises the importance of developing cleaner and more efficient systems of energy generation, among then, the solid oxide fuel cell (SOFC). Cubic stabilized zirconia (CSZ) has been the most studied material as electrolyte in SOFC, due to its ionic conductivity and great stability at operation conditions. However, its low fracture toughness difficulties its application as a thin layer, what could lead to an improvement of cell efficiency. In this sense, the alumina addition in CSZ forms a composite, which can shift its mechanical properties, without compromising its electrical properties. In this work, coprecipitation synthesis route and ceramic processing of zirconia-alumina composites were studied, in order to establish optimum conditions to attain high density, homogeneous microstructure, and better mechanical properties than CSZ, without compromising ionic conductivity. For this purpose, composites containing up to 40 wt % of alumina, in a 9 mol % yttria-stabilized zirconia (9Y-CSZ) matrix were evaluated. In order to optimize the synthesis of the composites, a preliminary study of powder obtaining and processing were carried out, at compositions containing 20 wt % of alumina, in 9Y-CSZ. The ceramic powders were characterized by helium picnometry, X-ray diffraction, scanning electronic microscopy, transmission electronic microscopy, thermogravimetry, differential scanning calorimetry, granulometry by laser diffraction and gas adsorption (BET). The characterization of sinterized compacts were performed by X-ray diffraction, scanning electron microscopy, optical microscopy, density measurements, Vickers indentation and impedance spectroscopy. The obtained results show that the alumina addition, in the 9Y-CSZ matrix powders, raises the specific surface area, promotes deagglomeration of powders and elevates the oxides crystallization temperature, requiring higher energetic thermal treatments to attain high densities. In relation to the sintered products, it was confirmed the excellent homogeneity and crystallinity of microstructure provided by the chosen route, the restriction of grain growth by alumina addition, raise of hardness and fracture toughness, and higher ionic conductivity, even tough a lower bulk conductivity. These results indicate that the addition of 5 wt % alumina in CSZ matrix allows the application of this material as solid oxide fuel cell electrolytes, due to its better fracture toughness and ionic conductivity, compared to yttria-stabilized cubic zirconia ceramics. (author)

  9. Some observations on synthesis and electrolytic properties of nonstoichiometric calcium zirconate

    International Nuclear Information System (INIS)

    Stoichiometric CaZrO3 (CZ-50) and CaZrO3 doped with excess CaO (CZ-51) powders, whose formula (CaO)1-x(ZrO2)x, where x = 50 or 51 mol.% CaO was successfully synthesised by the co-precipitation calcination method with a saturated solution of (NH4)2C2O4 in concentrated NH3 solution as a precipitation agent. The thermal evolution of CaZrO3 dried precursor during heating them up to 1200 deg. C was monitored by thermal (DTA, TG) and X-ray diffraction analysis methods. The highest temperature (1200 deg. C) for CaZrO3 synthesis was found for stoichiometric CaZrO3, whereas introduction of excess CaO into CaZrO3 led to a decrease in the synthesis temperature to 1000 deg. C. The crystallite size d(hkl) of grounded CaZrO3 powders ranged from ?43 to ?90 nm, respectively. BET measurements indicated that in both the investigated powders, particles were agglomerated. Sintering CaZrO3-based samples at 1500 deg. C/2 h or hot-pressing process (1250 deg. C/1 h, 25 MPa) was applied to obtain gas-tight CaZrO3-based ceramics. To examine the thermochemical stability of materials obtained at high temperatures, the CaZrO3-based samples were additionally heated at 1200 deg. C for 120 h or in the temperature range 1400-1600 deg. C for 24 h in air or purified argon. There were also perfr purified argon. There were also performed and then discussed, some tests on thermal resistance of CaZrO3 against molten metals-nickel and copper. Investigations into chemical reactivity of CaZrO3 electrolyte with electrode materials involving LaCrO3 or MCr2O4 (M = Mg, Ca) in the temperature range 1000-1200 deg. C were conducted using XRD with Rietveld analysis. Electrical conductivity measurements performed by both dc and ac impedance spectroscopy method in the temperature range 200-1000 deg. C. The best oxygen ion conductivity was found for CaZrO3-doped excess CaO (CZ-51) samples sintered in air, starting from powders synthesized by co-precipitation or citrate method. The CZ-51 samples obtained via solid state reaction or hot-pressed exhibited lower values of electrical conductivity. Test results for this compound used as an electrolyte in solid oxide cells involving electrode materials MCr2O4 (M = Mg, Ca) are also reported. In this way the Gibbs free energy of formation of MgCr2O4 at 1000 deg. C was determined. The nonstoichiometric CaZrO3 seems to be a promising solid electrolyte for electrochemical oxygen probes in control of metal processing.

  10. Some observations on synthesis and electrolytic properties of nonstoichiometric calcium zirconate

    Energy Technology Data Exchange (ETDEWEB)

    Dudek, Magdalena [AGH-University of Science and Technology, Faculty of Materials Science and Ceramics, 30-059 Cracow (Poland)], E-mail: potoczek@uci.agh.edu.pl; Drozdz-Ciesla, Ewa [AGH-University of Science and Technology, Faculty of Materials Science and Ceramics, 30-059 Cracow (Poland)

    2009-05-05

    Stoichiometric CaZrO{sub 3} (CZ-50) and CaZrO{sub 3} doped with excess CaO (CZ-51) powders, whose formula (CaO){sub 1-x}(ZrO{sub 2}){sub x}, where x = 50 or 51 mol.% CaO was successfully synthesised by the co-precipitation calcination method with a saturated solution of (NH{sub 4}){sub 2}C{sub 2}O{sub 4} in concentrated NH{sub 3} solution as a precipitation agent. The thermal evolution of CaZrO{sub 3} dried precursor during heating them up to 1200 deg. C was monitored by thermal (DTA, TG) and X-ray diffraction analysis methods. The highest temperature (1200 deg. C) for CaZrO{sub 3} synthesis was found for stoichiometric CaZrO{sub 3}, whereas introduction of excess CaO into CaZrO{sub 3} led to a decrease in the synthesis temperature to 1000 deg. C. The crystallite size d{sub (hkl)} of grounded CaZrO{sub 3} powders ranged from {approx}43 to {approx}90 nm, respectively. BET measurements indicated that in both the investigated powders, particles were agglomerated. Sintering CaZrO{sub 3}-based samples at 1500 deg. C/2 h or hot-pressing process (1250 deg. C/1 h, 25 MPa) was applied to obtain gas-tight CaZrO{sub 3}-based ceramics. To examine the thermochemical stability of materials obtained at high temperatures, the CaZrO{sub 3}-based samples were additionally heated at 1200 deg. C for 120 h or in the temperature range 1400-1600 deg. C for 24 h in air or purified argon. There were also performed and then discussed, some tests on thermal resistance of CaZrO{sub 3} against molten metals-nickel and copper. Investigations into chemical reactivity of CaZrO{sub 3} electrolyte with electrode materials involving LaCrO{sub 3} or MCr{sub 2}O{sub 4} (M = Mg, Ca) in the temperature range 1000-1200 deg. C were conducted using XRD with Rietveld analysis. Electrical conductivity measurements performed by both dc and ac impedance spectroscopy method in the temperature range 200-1000 deg. C. The best oxygen ion conductivity was found for CaZrO{sub 3}-doped excess CaO (CZ-51) samples sintered in air, starting from powders synthesized by co-precipitation or citrate method. The CZ-51 samples obtained via solid state reaction or hot-pressed exhibited lower values of electrical conductivity. Test results for this compound used as an electrolyte in solid oxide cells involving electrode materials MCr{sub 2}O{sub 4} (M = Mg, Ca) are also reported. In this way the Gibbs free energy of formation of MgCr{sub 2}O{sub 4} at 1000 deg. C was determined. The nonstoichiometric CaZrO{sub 3} seems to be a promising solid electrolyte for electrochemical oxygen probes in control of metal processing.

  11. Synthesis and Characterization of Cross-linked Polymer Electrolyte Membranes for Supercapacitor

    Science.gov (United States)

    Rosi, Memoria; Ekaputra, Muhamad Prama; Abdullah, Mikrajuddin; Khairurrijal

    2010-10-01

    Cross-linked polyvinyl alcohol (PVA) electrolyte membranes have been synthesized by using a solution casting method. In this study, PVA was blended with oxidative cross-linked agent (zinc acetate) and nano-sized silica as filler to stabilize PVA matrix and enhance conductivity. The cross-linked membranes were immersed into lithium hydroxide (LiOH) aqueous solution to increase their ionic conductivity. Two techniques were used to characterize the resulted membranes including Fourier transform infra red (FTIR) and AC impedance spectroscopies. The results showed that absorption peaks of C-O-C group and Si-O-Si are presence in the FTIR spectra attributed to the cross-linking process. Impedance spectra indicated that the contribution of ionic dopant (LiOH) to enhance conductivity is insignificant. The highest conductivity of the studied cross-linked PVA membrane is 1.34×10-3 S cm-1 corresponding to 5% LiOH dopant concentration of cross-linked PVA-zinc acetate-nano silica membrane. The present study also suggested that the solution casting is appropriate for cross-linked membrane synthesis.

  12. Synthesis and Rheological Properties of an Associative Star Polymer in Aqueous Solutions

    DEFF Research Database (Denmark)

    Hietala, Sami; Mononen, Pekka

    2007-01-01

    Rheological properties of aqueous solutions and hydrogels fonned by an amphiphiIic star block copolymer poly(acrylic acid)-blockpolystyrene (PAAS4-b-PS6)4. were investigated as a function of the polymer concentration (Cp), temperature, and added saIt concentration. The water-soluble polymer synthesised by atom transfer radical. polymerization (ATRP) was found to fonn hydrogels at room temperature at polymer concentrations. Cp, over 22 gIL due to the interpolymer drophobic association of the PS blocks. Increasing Cp leads to stronger elastic networks at room temperature that show a gel-to-solution transition with increasing temperature. Increase of ionic strength decreases the moduli compared with the pure hydrogel but did not affect the gel-sol transition temperature significantly. Small-angle X-ray experiments showed two distinct scattering correlation peaks for samples above the gelling Cp, which indicates the aggregates fonmed due to hydrophobic association. Upon heating the intensity of the scattering correlation peaks was found to decrease indicating the loss of the network structure due to thermal motion.

  13. Magnetic properties of La-substituted Ni-Zn-Cr ferrites via rheological phase synthesis

    International Nuclear Information System (INIS)

    Nanocrystalline ferrites Ni0.6Zn0.4Cr0.5LaxFe1.5-xO4 (x = 0-0.10) were prepared by a rheological phase-reaction process. The influence of the La content on microstructure and magnetic properties of samples were investigated. The structure, morphology and magnetic properties of the obtained products were characterized by X-ray diffractometer (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and network analyzer (NA). XRD results showed that the substituting La3+ ions had a solubility limit in the spinel lattice. The present work showed that the crystallite size and magnetic properties could be tuned over by introducing La3+ ions into the Ni-Zn-Cr ferrites. The crystallite size, saturation magnetization of samples decreased with the increase of La content, whereas the variation of coercivity was reverse. Moreover, the microwave absorption ability of the samples can be improved by changing the components of the ferrites

  14. Synthesis and characterization of hot pressed ion conducting solid polymer electrolytes: (1 - x) PEO: x NaClO4

    Science.gov (United States)

    Chandra, Angesh; Chandra, Archana; Thakur, Kiran

    2015-02-01

    Synthesis and ion transport characterization of hot-pressed poly(ethylene oxide) PEO-based solid polymer electrolytes (SPEs): (1 - x) PEO: x NaClO4, where 0 PEO: 30NaClO4) with ionic conductivity (?) ~ 7.07 × 10-7 S cm-1 shows the highest conducting composition and this have been referred to as optimum conducting composition (OCC). Materials characterization and thermal behavior of the present SPEs have been done with the help of XRD, FTIR, SEM, DSC and TG analysis. To determine the activation energy, temperature dependent ionic conductivity (?) of different compositions has been measured. Ionic nature of the SPEs has been explained with the help of ionic transference number (tion) measurements. Finally, the thin film polymer battery is also fabricated using the SPE OCC as electrolyte and calculated their cell parameters at room temperature.

  15. Synthesis and characterization of nanocrystalline dysprosia stabilized zirconia based electrolyte for intermediate-temperature solid oxide fuel cell

    International Nuclear Information System (INIS)

    The present work concerns studies on synthesis (by chemical co-precipitation) and characterization (microstructural and electrical) of 8 and 10 mol% dysprosia stabilized nanocrystalline cubic-zirconia (DySZ) for use as electrolyte materials in solid oxide fuel cell in the intermediate temperature range. Identity and crystallite size of the calcined powders were determined by X-ray diffraction. Microstructural studies of calcined/sintered product by transmission and scanning electron microscopes allowed verification of crystallite/particle size and analysis of morphology/density/distribution of the defects, respectively. Impedance spectroscopy revealed that the contribution of grain boundary resistance is higher than that of the bulk. Furthermore, conductivity analysis evidenced an Arrhenius type thermally activated ionic conduction above 300 deg. C. Thus, DySZ appears a possible alternative to yttria stabilized zirconia (YSZ) as electrolyte for solid oxide fuel cells due to its lower thermal and comparable ionic conductivity as YSZ.

  16. Synthesis and Characterization of Triazolium Iodide Ionic Liquid Electrolyte for Dye Sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kokil, Akshay; Renna, A.; Kumar, Jayant; Granados-Focil, S.

    2011-01-01

    Imidazolium iodide compounds have been utilized in the electrolytes for dye sensitized solar cells (DSSC). Most of the investigations with these compounds focus on the formulation of eutectic mixtures that promote efficient dissociation and diffusion of the iodide and triiodide species. Facile alternative synthetic approaches such as click chemistry (Huisgen 3+2 dipolar cycloaddition reaction) can be utilized to broaden the scope of electrochemically stable promising materials for novel electrolyte systems. Here, we report the first example of a triazolium functionalized cyclic siloxane that can be used as an electrolyte component in solvent-based DSSCs. The devices fabricated with this new triazolium salt in the electrolyte yielded short circuit current densities (26 mA/cm{sup 2}), as well as power conversion efficiencies of 8%, these values are comparable to those obtained for imidazolium salt analogues.

  17. Synthesis and characterization of amorphous poly(ethylene oxide)/poly(trimethylene carbonate) polymer blend electrolytes

    OpenAIRE

    Rodrigues, Lui?sa; Silva, Maria Manuela; Smith, Michael John

    2012-01-01

    Solid Polymer Electrolytes (SPEs) have been proposed as substitutes for conventional non-aqueous electrolytes in various electrochemical devices. These promising materials may be of interest in various practical devices including batteries, sensors and electrochromic displays as they can offer high performance in terms of specific energy and specific power (batteries), safe operation, form flexibility in device arquitecture and low manufacturing costs. Many different host polymers have bee...

  18. Synthesis of a novel imidazolium-based electrolytes and application for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Dong-Wan [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Sarker, Subrata; Nath, Narayan Chandra Deb [Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Choi, Seung-Woo [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Ahammad, A.J. Saleh [Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Lee, Jae-Joon, E-mail: jjlee@kku.ac.k [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of); Department of Advanced Technology Fusion, Konkuk University, Seoul (Korea, Republic of); Kim, Whan-Gi, E-mail: wgkim@kku.ac.k [Department of Applied Chemistry, Konkuk University, 322 Danwol-dong, 380-701 Chungju (Korea, Republic of)

    2010-01-25

    A series of new imidazolium-based oligomers with different length of a poly(ethylene glycol) moiety as a linker were synthesized and studied as electrolytes for dye-sensitized solar cell (DSSC). These oligomeric molecules are expected to have an intra- or inter-molecular hydrogen bonding interaction through its urethane and urea bonds. They can be used to prepare the liquid-type electrolytes for DSSC by dissolving them into conventional solvent system or to develop solvent-free electrolytes by incorporating an extra redox mediator and other functional materials together as additives. It was found that these oligomers could replace the cationic component of the conventional electrolytes and became the source of redox species when iodine is added. The photocurrent-voltage characteristics of DSSCs with the electrolytes containing these oligomers demonstrated that they can successfully replace the conventional ionic liquid-type electrolytes such as 1-methyl-3-propyl imidazolium iodide (PMII) in 3-methoxypropionitrile (MPN) if the length of the linker is optimized.

  19. Synthesis and electrochemical properties of lithium methacrylate-based self-doped gel polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Wan-Chul; Park, Hyoun-Gyu; Kim, Kyung-Chan [Department of Industrial Engineering Chemistry, College of Engineering, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Ryu, Sang-Woog [Department of Industrial Engineering Chemistry, College of Engineering, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of)], E-mail: swryu@chungbuk.ac.kr

    2009-07-30

    In this study, a strategy for synthesizing lithium methacrylate (LiMA)-based self-doped gel polymer electrolytes was described and the electrochemical properties were investigated by impedance spectroscopy and linear sweep voltammetry. LiMA was found to dissolve in ethylene carbonate (EC)/diethyl carbonate (DEC) (3/7, v/v) solvent after complexing with boron trifluoride (BF{sub 3}). This was achieved by lowering the ionic interactions between the methacrylic anion and lithium cation. As a result, gel polymer electrolytes consisting of BF{sub 3}-LiMA complexes and poly(ethylene glycol) diacrylate were successfully synthesized by radical polymerization in an EC/DEC liquid electrolyte. The FT-IR and AC impedance measurements revealed that the incorporation of BF{sub 3} into the gel polymer electrolytes increases the solubility of LiMA and the ionic conductivity by enhancing the ion disassociations. Despite the self-doped nature of the LiMA salt, an ionic conductivity value of 3.0 x 10{sup -5} S cm{sup -1} was achieved at 25 deg. C in the gel polymer electrolyte with 49 wt% of polymer content. Furthermore, linear sweep voltammetry measurements showed that the electrochemical stability of the gel polymer electrolyte was around 5.0 V at 25 deg. C.

  20. Synthesis of a novel imidazolium-based electrolytes and application for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    A series of new imidazolium-based oligomers with different length of a poly(ethylene glycol) moiety as a linker were synthesized and studied as electrolytes for dye-sensitized solar cell (DSSC). These oligomeric molecules are expected to have an intra- or inter-molecular hydrogen bonding interaction through its urethane and urea bonds. They can be used to prepare the liquid-type electrolytes for DSSC by dissolving them into conventional solvent system or to develop solvent-free electrolytes by incorporating an extra redox mediator and other functional materials together as additives. It was found that these oligomers could replace the cationic component of the conventional electrolytes and became the source of redox species when iodine is added. The photocurrent-voltage characteristics of DSSCs with the electrolytes containing these oligomers demonstrated that they can successfully replace the conventional ionic liquid-type electrolytes such as 1-methyl-3-propyl imidazolium iodide (PMII) in 3-methoxypropionitrile (MPN) if the length of the linker is optimized.

  1. Synthesis and electrochemical properties of lithium methacrylate-based self-doped gel polymer electrolytes

    International Nuclear Information System (INIS)

    In this study, a strategy for synthesizing lithium methacrylate (LiMA)-based self-doped gel polymer electrolytes was described and the electrochemical properties were investigated by impedance spectroscopy and linear sweep voltammetry. LiMA was found to dissolve in ethylene carbonate (EC)/diethyl carbonate (DEC) (3/7, v/v) solvent after complexing with boron trifluoride (BF3). This was achieved by lowering the ionic interactions between the methacrylic anion and lithium cation. As a result, gel polymer electrolytes consisting of BF3-LiMA complexes and poly(ethylene glycol) diacrylate were successfully synthesized by radical polymerization in an EC/DEC liquid electrolyte. The FT-IR and AC impedance measurements revealed that the incorporation of BF3 into the gel polymer electrolytes increases the solubility of LiMA and the ionic conductivity by enhancing the ion disassociations. Despite the self-doped nature of the LiMA salt, an ionic conductivity value of 3.0 x 10-5 S cm-1 was achieved at 25 deg. C in the gel polymer electrolyte with 49 wt% of polymer content. Furthermore, linear sweep voltammetry measurements showed that the electrochemical stability of the gel polymer electrolyte was around 5.0 V at 25 deg. C.

  2. From molecular models to system analysis for lithium battery electrolytes

    Science.gov (United States)

    Kerr, John B.; Sloop, Steven E.; Liu, Gao; Han, Yong Bong; Hou, Jun; Wang, Shanger

    The behavior of polymer electrolytes in lithium batteries is reviewed in the context of molecular scale models as well as on the system scale. It is shown how the molecular structure of the electrolyte strongly influences ion transport through the polymer as well as across the interfaces and determines the values of a number of parameters needed for system models that can predict the performance of the battery (e.g. ?, D, t0+ and i0). The interaction of the electrolyte with the electrodes not only leads to transfer of the lithium ion across the interface but also to side reactions that profoundly influence the calendar and life cycle of the battery. Typically these electrochemically induced side reactions generate the SEI layer, but inherent instability of the bulk electrolyte may also play a role in the formation of surface layers. These various reactions can lead to changes in the mechanical properties of the separator and electrode structure that promote life-limiting phenomena such as dendrite growth, passivation and morphology changes. The rheological model of Eisenberg is drawn upon to show how the interactions of the electrolyte with surfaces can lead to distinct changes in mechanical and transport properties that may limit the battery performance and lead to diminished performance with time. The molecular level models may be combined with the rheological models to provide workable models of the interfaces and bulk electrolyte dynamics that in turn can be used to provide a more accurate level of performance prediction from the system models. This connects molecular structure with battery performance and guides the design and synthesis of new and better materials.

  3. Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

    International Nuclear Information System (INIS)

    Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO4, heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10-4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a erfacial resistance over time, which is a key factor for use in electrochemical applications

  4. Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Meneghetti, Paulo; Qutubuddin, Syed [Case Western Reserve Univ., Dept. of Chemical Engineering, Cleveland, OH (United States); Webber, Andrew [Eveready Battery Co., Westlake, OH (United States)

    2004-10-30

    Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO{sub 4} electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO{sub 4}, heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA--clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10{sup -4} S/cm at clay content of 1.5 wt. %. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO{sub 4} electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications. (Author)

  5. Synthesis and characterization of amorphous poly(ethylene oxide)/poly(trimethylene carbonate) polymer blend electrolytes

    International Nuclear Information System (INIS)

    Solid polymer electrolytes (SPEs) have been proposed as substitutes for conventional non-aqueous electrolytes in various electrochemical devices. These promising materials may be of interest in various practical devices including batteries, sensors and electrochromic displays as they can offer high performance in terms of specific energy and specific power (batteries), safe operation, form flexibility in device arquitecture and low manufacturing costs. Many different host polymers have been characterized over the last 30 years, however a relatively un-explored strategy involves the use of interpenetrating blends incorporating two or more polymers. Electrolyte systems based on interpenetrating blends of known host polymers, poly(ethylene oxide) and poly(trimethylene carbonate), doped with lithium perchlorate, were prepared by co-dissolution in acetonitrile. This combination of polymer components results in the formation of a material that may be applicable in batteries and electrochromic devices. The results of characterization of polymer electrolyte systems based on interpenetrating blends of amorphous poly(ethylene oxide) and poly(trimethylene carbonate) host matrices, with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as guest salt, are described in this study. Electrolytes with compositions of n between 5 and 15 (where n represents the total number of cation-coordinating units per lithium ion) were obtained as flexible, transparent and free-standing films thae, transparent and free-standing films that were characterized by measurements of conductivity, cyclic voltammetry, differential scanning calorimetry and thermogravimetry.

  6. In vitro evaluation of cell proliferation and collagen synthesis on titanium following plasma electrolytic oxidation.

    Science.gov (United States)

    Whiteside, Paul; Matykina, Endzhe; Gough, Julie E; Skeldon, Peter; Thompson, George E

    2010-07-01

    Titania-based coatings produced by plasma electrolytic oxidation are being investigated as bioactive surfaces for titanium implants. In this study, plasma electrolytic oxidation was performed in calcium- and phosphorus-based electrolytes under DC conditions, resulting in coatings of thickness of approximately 8-15 mum. Coating morphologies, microstructures, and compositions were examined by scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction, and electron probe microanalysis. The coatings revealed a cratered morphology, with incorporated calcium and phosphorus species. Proliferation rates of primary human osteoblasts cells on the coatings were up to approximately 37% faster than those for uncoated titanium and 316L stainless steel reference materials. Further, the coatings assisted cell adhesion and generation and anchorage of collagen. The amount of collagen was upto approximately 2.4 times greater than for the reference substrates. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID:20091708

  7. Synthesis of Bi2WO6 nanoparticles and its electrochemical properties in different electrolytes for pseudocapacitor electrodes

    International Nuclear Information System (INIS)

    Highlights: • A simple, economical and environmentally benign sonochemical technique was utilized for the synthesis of homogeneous Bi2WO6 nanoparticles. • This is the first attempt to employ Bi2WO6 as a supercapacitor electrode material. • Effect of electrolyte on the capacitive behaviour of the material is studied. • Bi2WO6 displays good capacitive behaviour in 1 M KOH compared with 1 M NaOH and 1 M LiOH and possess sufficient capacity retention. • It presented an energy density of 67 Wh/kg in the potential range from ?0.9 V to 0.1 V and it would be a promising negative electrode for supercapacitor. -- Abstract: Nanosized Bi2WO6 particles were successfully synthesized by sonochemical method with an objective to develop an inexpensive and eco-friendly electrode material for supercapacitors. The prepared material was subjected to various thermal, structural, morphological, compositional, electrical and electrochemical studies. Bi2WO6 nanoparticle with homogeneous distribution was achieved through sonochemical process. The lattice parameter and atomic positions of Bi2WO6 structure were refined through Reitveld analysis. The electrochemical performance of Bi2WO6 nanoparticles was investigated in various aqueous electrolytes such as 1 M NaOH, 1 M LiOH, 1 M Na2SO4, 1 M KOH and 6 M KOH solutions. Among these, the material exhibited an enhanced electrochemical performance in KOH electrolyte due to its smaller hydration sphere radius, high ionic mobility and lower equivalent series resistance. The charge–discharge studies rendered a specific capacitance of 608 F/g in 1 M KOH at a current density of 0.5 mA/cm2. Bi2WO6 exhibited an excellent coulombic efficiency and specific capacitance of around 304 F/g at 3 mA/cm2 in the potential range from ?0.9 to 0.1 V vs Hg/HgO in 1 M KOH electrolyte. The above results assured that Bi2WO6 could be utilized as suitable negative electrode material for supercapacitor applications and 1 M KOH could be its desirable electrolyte

  8. Spray pyrolytic synthesis and electrolytic properties of BiCuVOx films for fuel cell applications

    International Nuclear Information System (INIS)

    The fuel cell material of bismuth copper vanadium oxide (BICUVOX) were deposited in thin film form on glass substrates using spray pyrolysis technique. The substrate temperature, quantity of sprayed solution and annealing temperature were charged to study the structural and electrolytic properties of BICUVOX thin films for fuel cell applications. It has been observed that the changes in spray parameters can be used to monitor the electrical properties of BICUVOX thin films suitable for their potential application as electrolyte for solid oxide fuel cell. It is found that the onset of the ionic conductivity region shifts to low temperature region of the fuel cell operating temperature with increase in substrate temperature of the films. (author)

  9. Iodide-conducting polymer electrolytes based on poly-ethylene glycol and MgI2: Synthesis and structural characterization

    International Nuclear Information System (INIS)

    A major obstacle for a viable technological development of dye sensitized solar cells (DSSCs) is still the synthesis of a high performance iodide-conducting polymer electrolyte. Here we present a series of eight electrolytic complexes with formula PEG1000/(MgI2)x(I2)y (0.0038 ? x ? 0.5801, 0 ? y ? 0.0636). The synthesis involves the preparation of a disordered form of MgI2 by a metallorganic route, which enables us to dissolve high amounts of salt in the chosen polymer host. The thermal analysis of the resulting polymer electrolytes was performed using modulated differential scanning calorimetry measurements. Vibrational studies were carried out using medium FT-IR, far FT-IR and FT-Raman. The variation of the CO and OH stretching modes in the medium infrared, as a function of the mole-to-mole ratio nMg/nO, was investigated by Gaussian decomposition to provide insight into the polymer–polymer and salt–polymer interactions in these materials. The FT-Raman spectra confirmed and complemented the vibrational assignment. The conductivity study of these systems was performed by electrical spectroscopy in the frequency interval 10 mHz–10 MHz. The direct current conductivity (?DC) profiles versus the reciprocal temperature exhibited a Vögel-Tamman-Fülcher (VTF) behavior. The best ?DC at 50 °C was 5 × 10?5 S cm?1. The overall results i overall results indicate the presence of bivalent, monovalent and neutral species, Mg2+, [MgI]+ and MgI2, respectively, which participate in the conduction process. These results are consistent with what was previously observed in PEG400-based systems doped with ?-MgCl2. The presence of at least one Mg site containing a distribution in parameters was observed using 25Mg solid state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The site has been assigned to a Mg complex involving the coordination by oxygen atoms of the polymer backbone.

  10. The Synthesis and Evaluation of Proton Conducting Electrolytes for High Temperature Steam Electrolysers

    OpenAIRE

    Stuart, Paul Anthony

    2011-01-01

    Proton conducting ceramics based on acceptor doped perovskites are the subject of investigation as candidate electrolyte materials for Solid Oxide Electrolyser Cells (SOECs). Specifically, BaCe0.9Y0.1O3-[delta](BCY10) and BaZr0.9Y0.1O3-[delta](BZY10) were investigated. Samples with greater than 95% of the maximum theoretical density were successfully prepared using a BCY10 commercial powder. It was found that when small additions of ZnO were added to a BZY10 commercial powder, ...

  11. Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes

    OpenAIRE

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 ...

  12. Low temperature electrochemical synthesis and dielectric characterization of barium titanate films using nonalkali electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Venigalla, S.; Bendale, P.; Adair, J.H. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering

    1995-06-01

    Polycrystalline BaTiO{sub 3} thin films of approximately 1 {mu}m thickness have been synthesized on Ti substrates by an electrochemical process using nonalkali electrolytes, at temperatures as low as 55 C. The effect of various processing parameters, such as solution chemistry, atmosphere, quality of substrate surface, applied voltage, temperature, and reaction time have been discussed. Film thickness and uniformity increase with reaction time up to 24 h. The quantity of total electric charge passed through the electrolytic cell is found to govern the film thickness and uniformity. Dielectric characteristics of the as-prepared and heat-treated films have also been reported. Use of tetraethylammonium hydroxide, a nonalkali base reagent to adjust solution pH, has resulted in films having improved dielectric properties as opposed to the films prepared with alkali metal bases such as NAOH. Heat-treatment further improves the dielectric properties through a phase transition to the thermodynamically stable tetragonal phase from the as-prepared pseudo-cubic phase as confirmed by the X-ray diffraction data.

  13. Synthesis and characterization of novel electrolyte materials for intermediate temperature solid oxide fuel cells

    International Nuclear Information System (INIS)

    The high operating temperature of SOFCs using zirconia based electrolyte have several restrictions on materials used as interconnect and sealing and also requires use of expensive ceramics. Lowering the operating temperature of SOFCs to 600-800 deg C will enable to use cheaper materials and reduce the cost of fabrication while keeping the high power density. Lanthanide gallates are considered to be very promising solid electrolytes for intermediate temperature (600-800 deg C) solid oxide fuel cells (IT-SOFCs) due to their high ionic conductivity at lower temperatures. Phase purity of this material is a concern for the researchers for a long time. These materials are prepared at very high temperature (?1400 deg C), since it is known that at around 1100 deg C, solubilities of Sr and Mg in LaGaO3 were close to zero. Hence in the present work perovskite oxides of Ln1-xSrxGa1-yMgyO3-? (Ln= Sm, Gd and x = 0.10, y=0.20) have been prepared by different methods i.e. solid state reaction, gel combustion and co-precipitation methods

  14. Synthesis and Physical Behavior of Model Polymer Electrolyte Membranes for Alkaline Fuel Cells

    Science.gov (United States)

    Beyer, Rick; Price, Samuel; Jackson, Aaron; Gold, Christopher; Ye, Yuesheng; Elabd, Yossef

    2012-02-01

    Alkaline fuel cell (AFC) technology holds significant promise for portable power supplies because AFCs are very efficient at temperatures under 200 C, but also because AFCs can use relatively inexpensive, non-noble metals (Ni, Fe, Co) as the catalyst material. Wide-spread use of the AFC has been prevented by the use of aqueous KOH liquid as the electrolyte, which is easily poisoned by the formation of K2CO3. Development of an semipermeable polymeric alkali anion exchange membrane (AEM) would significantly improve the usefulness of AFCs by eliminating carbonate poisoning and the engineering problems associate with a liquid electrolyte. We have been exploring model copolymers containing phosphonium cations as candidate materials for AEMs. Recent findings on the transport properties and stability of random copolymers of styrene and p-vinylbenzyl-trimethylphosphonium chloride will be presented, as well as ongoing efforts to study the effect of polymer morphology on transport and stability in ionomers based on both phosphonium and ammonium cations.

  15. Pilot-scale synthesis and rheological assessment of poly(methyl methacrylate) polymers: Perspectives for medical application.

    Science.gov (United States)

    Linan, Lamia Zuniga; Nascimento Lima, Nádson M; Filho, Rubens Maciel; Sabino, Marcos A; Kozlowski, Mark T; Manenti, Flavio

    2015-06-01

    This work presents the rheological assessment of poly(methyl methacrylate) (PMMA) polymers synthesized in a dedicated pilot-scale plant. This material is to be used for the construction of scaffolds via Rapid Prototyping (RP). The polymers were prepared to match the physical and biological properties required for medical applications. Differential Scanning Calorimetry (DSC) and Size Exclusion Chromatography (SEC) measurements verified that the synthesized polymers were atactic, amorphous and linear in chains. Rheological properties such as viscosity, storage and loss modulus, beyond the loss factor, and creep and recovery were measured in a plate-plate sensor within the viscoelastic linear region. The results showed the relevant influence of the molecular weight on the viscosity and elasticity of the material, and how, as the molecular weight increases, the viscoelastic properties are getting closer to those of human bone. This article demonstrates that by using the implemented methodology it is possible to synthesize a polymer, with properties comparable to commercially-available PMMA. PMID:25842114

  16. Design, synthesis, and testing of potential antisickling agents. 6. Rheologic studies with active phenoxy and benzyloxy acids.

    Science.gov (United States)

    Patwa, D C; Abraham, D J; Hung, T C

    1987-01-01

    In vitro rheologic studies have been performed with homozygous sickle erythrocytes in the presence of phenoxy and benzyloxy antigelling agents. The results correlate with those obtained previously from a standard hemoglobin S solubility assay (C-sat) that monitors the inhibition of hemoglobin S polymerization in solution. The order of activity of compounds in both studies was found to be about the same. The rheologic assay monitors the reduction in pressure (130 mm Hg sickled vs 9 mm Hg nonsickled) needed to push erythrocytes through a 5 micron filter. Among the drugs studied, the antilipidemic drug Clofibrate reduced the filtration pressure by as little as 9%, and a derivative of the diuretic agent ethacrynic acid (Merck-595, 595) reduced it by as much as 94%. Human Serum Albumin (HSA) (0.1% wt/vol) drastically reduced the activity of the noncovalently-acting aromatic acids by requiring at least three times the concentration of drug to obtain similar reductions in pressure. Two covalently-acting compounds, ethacrynic acid and Merck-595, 595, strongly increased the filterability of homozygous S erythrocytes at 1 and 3 mM drug concentrations even in the presence of HSA. No reason is given for the strong inhibitory effect of HSA at such high drug to HSA concentrations. PMID:3651614

  17. Synthesis and characterization of zirconia electrolytes for potential use in energy conversion systems

    Energy Technology Data Exchange (ETDEWEB)

    Wheat, T.A.

    1978-11-15

    Using a wet-chemical procedure, a series of compositions having between 0 and 22.2 mol % CaO was prepared and subsequently formed into sintered samples having a relative density from 95 to 98%. Sintered samples were prepared of each composition with a geometry appropriate for determining the thermal, electrical or microstructural characteristics. The microstructural aspects of powder synthesis and the development of sintered materials are covered.

  18. Synthesis and modeling of polysiloxane-based salt-in-polymer electrolytes with various additives.

    Science.gov (United States)

    Karatas, Y; Banhatti, Radha D; Kaskhedikar, N; Burjanadze, M; Funke, K; Wiemhöfer, Hans-D

    2009-11-26

    The effect of both nanoparticles and low molecular weight borate esters on the ionic conductivity of cross-linked polysiloxanes was systematically investigated by means of measuring conductivity spectra in the impedance regime at temperatures between -30 and 90 degrees C. Salt-in-polymer electrolytes were prepared by dissolving lithium triflate (LiSO(3)CF(3)) in comblike polysiloxanes bearing one methyl and one oligoether side group per silicon. An amount of 10 mol % of the oligoether side groups exhibited a terminal allytrimethoxysilane serving as a cross-linker moiety (T(0.1)OPS). Thus prepared polymer electrolyte membranes were completely amorphous and mechanically stable with an optimum conductivity value of 5.7 x 10(-5) S x cm(-1) at 15 wt % of lithium triflate (LiSO(3)CF(3)) at room temperature (T(0.1)OPS + 15 wt % LiSO(3)CF(3)). Further investigations concerned the influence of additives, i.e., nanosized ceramic fillers (alpha-Al(2)O(3) and SiO(2), up to 10 wt %) as well as two low molecular weight borate esters (tris(2-(2-methoxyethoxy)ethyl) borate (B2) and tris(2-(2-(2-methoxyethoxy)ethoxy)ethyl) borate (B3)) with maximum concentrations of 40 wt % as referred to polysiloxane T(0.1)OPS. The addition of borate esters resulted in a considerable increase of the conductivity, while still maintaining the mechanical stability. Optimum conductivities of 3.7 x 10(-5) and 1.6 x 10(-4) S x cm(-1) were measured for B2 and B3, respectively, at room temperature. A fit of the temperature-dependent DC conductivity by the empirical Vogel-Tammann-Fulcher (VTF) equation showed that there was an increased number density of mobile charge carriers in the case of borate esters as additives. However, the shape of the conductivity spectra in the dispersive regime changed considerably in going from nanoparticles as additives to borate esters. A careful and consistent modeling of the conductivity spectra and of the temperature dependence of the DC conductivity was done within the framework of the MIGRATION concept. The result was that the addition of borate esters to the polymer host most probably increased both number density of mobile charge carriers as well as their mobility. PMID:19845380

  19. Synthesis, spectroscopic and electrochemical performance of pasted ?-nickel hydroxide electrode in alkaline electrolyte

    Science.gov (United States)

    Shruthi, B.; Bheema Raju, V.; Madhu, B. J.

    2015-01-01

    ?-Nickel hydroxide (?-Ni(OH)2) was successfully synthesized using precipitation method. The structure and property of the ?-Ni(OH)2 were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman spectra and thermal gravimetric-differential thermal analysis (TG-DTA). The results of the FTIR spectroscopy and TG-DTA studies indicate that the ?-Ni(OH)2 contains water molecules and anions. The microstructural and composition studies have been performed using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. A pasted-type electrode is prepared using ?-Ni(OH)2 powder as the active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were performed to evaluate the electrochemical performance of the ?-Ni(OH)2 electrode in 6 M KOH electrolyte. CV curves showed a pair of strong redox peaks as a result of the Faradaic redox reactions of ?-Ni(OH)2. The proton diffusion coefficient (D) for the present ?-Ni(OH)2 electrode material is found to be 1.44 × 10-12 cm2 s-1. Further, electrochemical impedance studies confirmed that the ?-Ni(OH)2 electrode reaction processes are diffusion controlled.

  20. Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes.

    Science.gov (United States)

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two-electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%. PMID:23799106

  1. Self-propagating high-temperature synthesis of La(Sr)Ga(Mg)O3-? for electrolyte of solid oxide fuel cells

    International Nuclear Information System (INIS)

    This paper describes self-propagating high-temperature synthesis (SHS) of an electrolyte for solid oxide fuel (SOFC), in comparison to a conventional solid-state reaction method (SRM). Doped-lanthanum gallate: La0.9Sr0.1Ga0.8Mg0.2O3-? (LSGM9182) and LSGM9173 as the SOFC electrolyte, was prepared by the SHS and sintered at different temperatures, for measuring the electrical conductivity of the sintered LSGM and the power generating performance at 1073 K, in comparison to the SRM. In the SHS, the LSGM powders with smaller size were obtained and easily sintered at the 100 K-lower temperature, 1673 K, than in the SRM. Most significantly, the electrical conductivity of the sintered LSGM9182 was as high as 0.11 S cm-1 and its maximum power density was a value of 245 mW cm-2 in the cell configuration of Ni/LSGM9182 (0.501 mm in thickness)/Sm0.5Sr0.5CoO3. The conclusion was that the proposed SHS-sintering method with many benefits of minimizing the energy requirement and the processing time in the production, easing temperature restriction for the sintering, and improving the electrolyte performance up to a conventional level is practicable for producing the LSGM-electrolyte of SOFC at an intermediate-temperature application

  2. Synthesis, rheological behavior and swelling properties of copolymer hydrogels based on poly(N-isopropylacrylamide with hydrophilic monomers

    Directory of Open Access Journals (Sweden)

    D. Aliouche

    2013-09-01

    Full Text Available In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide and poly(N-isopropylacrylamide-co-acrylic acid having a thermoresponsive character were prepared by aqueous free-radical co-polymerization using the ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TEMED redox-pair initiator system in the presence of N,N'-methylenebisacrylamide (MBAAm crosslinker. (NIPAAm-co-AAm and (NIPAAm-co-AAc hydrogels with different thermoresponsive properties were obtained by fixing the initial NIPAAm/AAm mole ratio and and (NIPAAm-co-AAc mole ratio to 80/20 and changing the crosslinker concentration. The copolymers were characterized with infrared spectroscopy (IR and differential scanning calorimetry (DSC techniques. The swelling response of the copolymers networks as a function of time, temperature and swelling environment has been observed to be dependent on both structural aspects of the polymers and swelling environment. The swelling has been observed to be decrease with increase in MBAAm in the copolypolymers networks. Rheological behavior was studies in oscillatory module. All copolymers have a viscoelastic behaviour. We note that the elastic modulus G' increases with increasing hydrophilic monomers.DOI: http://dx.doi.org/10.4314/bcse.v27i3.14

  3. Synthesis of Solid Electrolyte Based on Lithium Glass (Ag2S)x(LiPO3)1-x

    International Nuclear Information System (INIS)

    Synthesis of solid electrolyte based on lithium glass (Ag2S)x(LiPO3)1-x has been developed. Melt quenching method was used to synthesize the superionic conducting glasses (Ag2S)x(LiPO3)1-x with x 0; 0.3; and 0.5 by using LiPO3 and Ag2S. X-ray diffraction showed that LiPO3 (x =0, LSX 00) (Ag2S)0.3(LiPO3)0.7, (LSX 03) and (Ag2S)0.5(LiPO3)0.5 (LSX 05) have amorphous structure. Thermal data measured by DSC showed that the glass transition temperature decreases from 149 oC for x = 0 (LSX 00) to 147 oC for x = 0.5 (LSX 05). SEM photo of LiPO3 showed smooth surface without grain, while for (Ag2S)0.3(LiPO3)0.7-C (LSX 03 C) and (Ag2S)0.5-C(LiPO3)0.5-C(LSX 05 C), the Ag2S grain that dissolved in LiPO3 matrix is shown. Increasing of Ag2S in LiPO3 glass consistently increased the conductivity of (Ag2S)x(LiPO3)1-x superionic. The milling of Ag2S could also increase the conductivity of (Ag2S)x(LiPO3)1-x superionic, in which the conductivity of (Ag2S)0.5(LiPO3)0.5 superionic iPO3)0.5 superionic increased from 2.5 x 10-3 S/cm to 1.143 S/cm. (author)

  4. Synthesis and electrochemical characterization of hybrid membrane Nafion-SiO2 for application as polymer electrolyte in PEM fuel cell

    International Nuclear Information System (INIS)

    In this work, the effect of sol-gel synthesis parameters on the preparation and polarization response of Nafion-SiO2 hybrids as electrolytes for proton exchange membrane fuel cells (PEMFC) operating at high temperatures (130 degree C) was evaluated. The inorganic phase was incorporated in a Nafion matrix with the following purposes: to improve the Nafion water uptake at high temperatures (> 100 degree C); to increase the mechanical strength of Nafion and; to accelerate the electrode reactions. The hybrids were prepared by an in-situ incorporation of silica into commercial Nafion membranes using an acid-catalyzed sol-gel route. The effects of synthesis parameters, such as catalyst concentration, sol-gel solvent, temperature and time of both hydrolysis and condensation reactions, and silicon precursor concentration (Tetraethyl orthosilicate - TEOS), were evaluated as a function on the incorporation degree and polarization response. Nafion-SiO2 hybrids were characterized by gravimetry, thermogravimetric analysis (TGA), scanning electron microscopy and X-ray dispersive energy (SEM-EDS), electrochemical impedance spectroscopy (EIS), and X-ray small angle scattering (SAXS). The hybrids were tested as electrolyte in single H2/O2 fuel cells in the temperature range of 80 - 130 degree C and at 130 degree C and reduced relative humidity (75% and 50%). Summarily, the hybrid performance showed to be strongly dependent on the synthesis parameters, mainly, the type of alcohol and the TEOS concentration. (author)

  5. Synthesis and characterization of zirconia electrolytes for potential use in energy conversion

    International Nuclear Information System (INIS)

    The present work is part of a program to develop ionically conducting materials for potential use in energy storage and conversion systems. With applications in high energy-density batteries, magneto-hydrodynamic (MHD) generators, fuel cells and sensors, they ae playing an increasinly important role in developing more efficient energy storage and conversion devices. Using a wet-chemical procedure, a series of compostions having between 0 and 22.2 mol percent CaO in zirconia, was prepared and subsequently formed into sintered samples having a relative density from 95 to 98 percent. Sintered samples were prepared of each composition with a geometry appropriate for determining the thermal, electrical or microstructural characteristics. This report covers only the microstructural aspects of powder synthesis and the development of sintered materials. Using the reactive, homogeneous, chemically prepared powders, it has been shown that cubic and monoclinic zirconia can coexist in compositions containing up to 10 mol percent CaO. From 10 to 20 mol percent CaO, only the cubic phase is formed, whereas at higher CaO concentrations the cubic phase coexits with CaZro3. The change from a two-phase to single-phase system as the CaO concentration is increased above 10 mol percent, increases the grain size nearly an order of magnitude. It has been found that 5 and 7.6 mol percent CaO materials develop considerable stress during the cooling stage of the firing cycle. As a result, they undergo a progressive and irreversible expansion with each thermal shock cycle: the magnitude of the expansion is proportional to the severity of the thermal shock. The microstructural texture of these partially stablilized materials was also shown to be dependent on the thermal history and hence a strong dependence of the electrical and thermal properties can be anticipated. (auth)

  6. Synthesis of spinel Li4Ti5O12 anode material by a modified rheological phase reaction

    International Nuclear Information System (INIS)

    Using lithium acetate dihydrate and tetra-n-butyl titanate as the raw materials, spinel Li4Ti5O12 was successfully synthesized by a modified rheological phase method. Thermogravimetric analysis and differential scanning calorimetry (TG-DSC) of the thermal decomposition process of the precursor and X-ray diffraction (XRD) data indicate the crystallization of lithium titanates has occurred at 580 deg. C, and main phase Li4Ti5O12 has obtained at 600 deg. C. Laser granulometer and scanning electron microscope (SEM) have been employed to estimate the particle size distribution, morphology and microstructure of the products. It reveals the prepared Li4Ti5O12 powder had a small particle size (about 140 nm) and narrow size distribution (d0.1 = 0.07, d0.5 = 0.139, d0.9 = 2.813 ?m). Galvanostatic charge and discharge tests were carried out to characterize the electrochemical performances of Li4Ti5O12. The result indicates that the Li4Ti5O12 electrode material obtained from the precursor that had been experienced heat treatment at 110 deg. C exhibited discharge capacities of 161.6, 156.5 and 112.3 mAh g-1 after 50 cycles at current rates 1, 2.5 and 10 C, respectively, demonstrating excellent high rate performance, due to the pure and well crystallized Li4Tid well crystallized Li4Ti5O12 with ultrafine particles and narrow size distribution.

  7. Synthesis and characterization of novel electrocatalysts and supports for use in polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Rock, Nicolaus L.

    The direct methanol fuel cell (DMFC) is a very promising power source for low power applications. High power and energy density, low emissions, operation at or near ambient conditions, fast and convenient refueling and a potentially renewable fuel source are some of the features that make the fuel cell very promising. However, there are a few problems that have to be overcome if we are to see DMFCs in our everyday life. Two drawbacks that cause problems with the DMFC are expensive anode catalysts and poor cathode catalyst supports. For the anode catalyst, the currently used PtRu bimetallic catalyst is simply too expensive and the loading required for adequate methanol reaction kinetics is simply too high. For the cathode support, the currently used high surface area carbon has the tendency to corrode and dissolve under high voltage corrosive conditions seen at the cathode. Novel, alternative anode catalysts and cathode supports must be developed to overcome the cost and limitations of each. The aim of this thesis is develop alternative anode catalysts and cathode support materials that will show some insight of how these problems may be begun to be solved. In order to achieve these aims, several synthesis methods were utilized in order to create the best possible materials. A fully alloyed quaternary alloy system with a high surface area is desired for the anode catalyst with reduce noble metal loading. The materials investigated for this purpose centered on PtRu based systems that incorporated materials that have shown promise in literature, namely, Ni, Ti, Sn, Co, Os. A high surface area, corrosion resistance, electronically conducting support materials is desired for the cathode support material. The materials chosen for this investigation centered on mixed metal oxides of SnTa and SnNb, based upon theoretical calculations done in our group. The results in this thesis have shown that a SnNb2O6 foordite structure exhibits promising specific surface areas (71.5 m2/g) with an excellent corrosion resistance and a trend toward the lowest resistivity of all the support materials synthesized. A Pt 40Ru40Ni10Sn10 quaternary alloy system exhibits promising current response with an onset voltage nearly comparable to that of PtRu at 20 at% less noble metal in the alloy system. Keywords: direct methanol fuel cell, pyrochlore, DMFC, anode, support, cathode, quaternary alloy, mixed metal oxide.

  8. Synthesis of calcium-deficient by hydroxyapatite-collage composite by the electrolytic deposition method; Denkai sekishutsu ho ni yoru karushiumu kesson hidorokishiapataito-coragen fukugotai no gosei

    Energy Technology Data Exchange (ETDEWEB)

    Okamura, H. [Niigata University, Niigata (Japan). Graduate School Of Science and Technology; Yasuda, M.; Oota, M. [Niigata University, Niigata (Japan)

    1997-07-05

    Hydroxyapatite is known as that it has a good joining property with teeth and bone, and a study on the application to the living body was conducted by using this property. Its application examples were given as the cement used in dentistry, the artificial tooth root, the artificial bone, the bone cement and the artificial joint. However, they were a sinter heated at more than 1000degC, and were put into use by means of reinforcement using a titanium alloy since their mechanical strength was low. In this study, synthesis of calcium-deficient hydroxyapatite (DAp) and collagen composite by the electrolytic deposition method was attempted in order to develop bionic materials, and the correlation of various physical properties of the obtained composite and the electrolytic deposition conditions were investigated. When the electrolytic voltage is more than 22.0V, a single phase of DAp could be obtained. It was clarified that a DAp and collagen composite was synthesized from results of IR and ESR. 16 refs., 5 figs.

  9. Self-propagating high-temperature synthesis of La(Sr)Ga(Mg)O{sub 3-{delta}} for electrolyte of solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Hiroyuki [Center for Advanced Research of Energy Conversion Materials, Hokkaido University, Sapporo 060-8628 (Japan); Enoki, Makiko [Department of Applied Chemistry, Faculty of Engineering, Kyusyu University, Fukuoka 812-8581 (Japan); Ishihara, Tatsumi [Department of Applied Chemistry, Faculty of Engineering, Kyusyu University, Fukuoka 812-8581 (Japan); Akiyama, Tomohiro [Center for Advanced Research of Energy Conversion Materials, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: takiyama@eng.hokudai.ac.jp

    2007-03-14

    This paper describes self-propagating high-temperature synthesis (SHS) of an electrolyte for solid oxide fuel (SOFC), in comparison to a conventional solid-state reaction method (SRM). Doped-lanthanum gallate: La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM9182) and LSGM9173 as the SOFC electrolyte, was prepared by the SHS and sintered at different temperatures, for measuring the electrical conductivity of the sintered LSGM and the power generating performance at 1073 K, in comparison to the SRM. In the SHS, the LSGM powders with smaller size were obtained and easily sintered at the 100 K-lower temperature, 1673 K, than in the SRM. Most significantly, the electrical conductivity of the sintered LSGM9182 was as high as 0.11 S cm{sup -1} and its maximum power density was a value of 245 mW cm{sup -2} in the cell configuration of Ni/LSGM9182 (0.501 mm in thickness)/Sm{sub 0.5}Sr{sub 0.5}CoO{sub 3}. The conclusion was that the proposed SHS-sintering method with many benefits of minimizing the energy requirement and the processing time in the production, easing temperature restriction for the sintering, and improving the electrolyte performance up to a conventional level is practicable for producing the LSGM-electrolyte of SOFC at an intermediate-temperature application.

  10. Synthesis and electrical properties of scheelite Ca1-xSmxMoO4+? solid electrolyte ceramics

    International Nuclear Information System (INIS)

    Graphical abstract: Scheelite-type Ca1-xSmxMoO4+? electrolyte ceramics can be considered as one of the best candidates to replace the YSZ electrolyte materials for SOFCs because of their high oxide ion conduction. Research highlights: ? SmxCa1-xMoO4+? solid electrolyte with a tetragonal scheelite structure. ? SmxCa1-xMoO4+? electrolyte is one of the best candidates to replace the YSZ electrolyte for SOFCs because of their high oxide ion conduction. ? The sintering temperature is greatly lower than traditional YSZ electrolyte. -- Abstract: Scheelite-type Ca1-xSmxMoO4+? electrolyte powders were prepared by the sol-gel auto-combustion process. The crystal structure of the samples was determined by employing the techniques of X-ray diffraction (XRD). According to the XRD analysis, the formed continuous series of Ca1-xSmxMoO4+? (0 ? x ? 0.3) solid solutions had the structure of tetragonal scheelite, and the lattice parameters increased with increasing x in the Sm-substituted system. Results of sinterability and electrochemical testing revealed that the performances of Sm-doped calcium molybdate were superior to that of pure CaMoO4. Ca1-xSmxMoO4+? ceramics show higher sinterability, and the Ca0.8Sm0.2MoO4+? sample with 98.7% of the theoretical density were obtained after being sintered at 1250 oC for 4 h. The conductivity increased with increasing samarium content, and a total conductivity 9.54 x 10-3 S cm-1 at 800 oC could be obtained in Ca0.8Sm0.2MoO4+? sintered at 1250 oC for 4 h.

  11. Synthesis of graphene nanosheets by the electrolytic exfoliation of graphite and their direct assembly for lithium ion battery anodes

    International Nuclear Information System (INIS)

    Graphene nanosheets were produced through electrolytic exfoliation of graphite foils in an aqueous solution containing an electrolyte, poly(sodium-4-styrenesulfonate). We confirmed the formation of graphene nanosheets by X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy. The electrochemical performance of the graphene nanosheets was evaluated using cyclic voltammetry, galvanostatic charge–discharge cycling, and electrochemical impedance spectroscopy. In order to address the feasibility of their use as lightweight anodes for a Li ion battery, we also present the direct assembly of graphene nanosheets onto metal current collectors and the fabrication of freestanding graphene nanosheets paper electrodes. Highlights: ? Graphene nanosheets were electrolytically synthesized from graphite foils. ? The direct electrophoretic deposition of the graphenes onto current collectors is described. ? Promising Li storage capabilities of graphene anode were found.

  12. Synthesis of graphene nanosheets by the electrolytic exfoliation of graphite and their direct assembly for lithium ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Hun; Seo, Seung-Deok; Park, Kyung-Soo; Shim, Hyun-Woo [Department of Materials Science and Engineering, Ajou University, San 5, Woncheon-dong, Yeongtong-gu, Suwon 443-749 (Korea, Republic of); Kim, Dong-Wan, E-mail: dwkim@ajou.ac.kr [Department of Materials Science and Engineering, Ajou University, San 5, Woncheon-dong, Yeongtong-gu, Suwon 443-749 (Korea, Republic of)

    2012-08-15

    Graphene nanosheets were produced through electrolytic exfoliation of graphite foils in an aqueous solution containing an electrolyte, poly(sodium-4-styrenesulfonate). We confirmed the formation of graphene nanosheets by X-ray diffraction, Raman spectroscopy, and high-resolution transmission electron microscopy. The electrochemical performance of the graphene nanosheets was evaluated using cyclic voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. In order to address the feasibility of their use as lightweight anodes for a Li ion battery, we also present the direct assembly of graphene nanosheets onto metal current collectors and the fabrication of freestanding graphene nanosheets paper electrodes. Highlights: Black-Right-Pointing-Pointer Graphene nanosheets were electrolytically synthesized from graphite foils. Black-Right-Pointing-Pointer The direct electrophoretic deposition of the graphenes onto current collectors is described. Black-Right-Pointing-Pointer Promising Li storage capabilities of graphene anode were found.

  13. Electrochemical formation of initial composition for superconductor synthesis in system Bi-Pb-Sr-Ca-Cu-O. 1.A search for electrolytes for electrodeposition of Bi-Pb-Sr-Ca-Cu and Bi-Pb-Cu alloys

    International Nuclear Information System (INIS)

    An electrolyte composition is worked out for deposition of basic initial componens used for high temperature superconductor synthesis in the Bi-Pb-Sr-Ca-Cu-O system with the atomic ratio of Bi:Pb:Cu-1.8:2:3

  14. Synthesis and surface modified hard magnetic properties in Co0.5Pt0.5 nanocrystallites from a rheological liquid precursor

    International Nuclear Information System (INIS)

    Small crystallites of a metastable phase Co0.5Pt0.5 are precipitated by heating a rheological liquid precursor of cobalt–hydrazine complex and platinum chloride H2PtCl6·xH2O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co2+ and Pt4+ that recombine and grow as Co0.5Pt0.5. The PVP molecules cap a growing Co0.5Pt0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co0.5Pt0.5 phase (average crystallite size D?8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ?=14.09 g/cm3). A more ordered L10 phase (?=15.91 g/cm3) transforms (D?25 nm) upon annealing the powder at temperature lesser than 700 °C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization Ms=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D?31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L10 phase at 800 °C for 60 min, showing a surface modified coercivity Hc=7.781 kOe with remnant ratio Mr/Ms=0.5564, and Ms=0.5564, and Ms=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large Hc from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L10 phase. - Highlights: ? A modified polyol process is reported for the synthesis of Co–Pt nanoparticles. ? Different particle sizes were obtained by varying the order of addition. ? Effect of particle size on fcc to fct phase transformation is discussed. ? Effect of heat treatments on evolution of magnetic properties is reported. ? Fully transformed Co–Pt nanoparticles resulted in a coercivity of 11.310 kOe.

  15. Synthesis and characterization of a new hyperbranched organic-inorganic solid polymer electrolyte with cyanuric chloride as a core element

    International Nuclear Information System (INIS)

    Highlights: ? The electrolyte exhibits an ionic conductivity value of 4.4 x 10-5 S cm-1 at 30 deg. C. ? Solid-state NMR confirms the hybrid structure of hybrid electrolytes. ? Li line width reveals that the mobility of Li ion is coupled with the polymer motion. ? PGSE NMR indicates that polymer segmental mobility affects Li diffusion. - Abstract: A new hyperbranched organic-inorganic hybrid electrolyte based on the use of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, CC) as the coupling core to couple with oligo(oxyalkylene)-amines, followed by condensation with (3-glycidoxypropyl)-trimethoxysilane (GLYMO) and complexed with LiClO4, has been prepared and characterized. The Vogel-Tamman-Fulcher (VTF) like conductivity behavior is observed in the present organic-inorganic hybrid electrolytes with a maximum ionic conductivity value of 4.4 x 10-5 S cm-1 at 30 deg. C. Multinuclear NMR techniques are used to provide a microscopic view for the specific interaction between the polymer chains and Li+ cations and their dynamic behaviors. The results of 2D 1H-13C wide-line separation (WISE) and 7Li static line NMR width measurements divulge that the mobility of the 7Li cations is strongly related to a dynamic environment created by the polymer motion in the amorphous phase. The combined results of conductivity and 7Li pulse-gradient spin-echo (PGSp>Li pulse-gradient spin-echo (PGSE) NMR self-diffusion coefficient measurements reveal that the conductivity enhancement at low salt concentrations is mainly caused by the high mobility of the lithium cations.

  16. Synthesis and characterization of a new hyperbranched organic-inorganic solid polymer electrolyte with cyanuric chloride as a core element

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yu-Chi; Saikia, Diganta [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China); Fang, Jason; Tsai, Li-Duan [Department of Fuel Cell Materials and Advanced Capacitors, Division of Energy Storage Materials and Technology, Material and Chemical Laboratories, Industrial Technology Research Institute, Hsin-Chu 300, Taiwan (China); Fey, George T.K. [Department of Chemical and Materials Engineering, National Central University, Chung-Li 32054, Taiwan (China); Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.t [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)

    2011-10-01

    Highlights: > The electrolyte exhibits an ionic conductivity value of 4.4 x 10{sup -5} S cm{sup -1} at 30 deg. C. > Solid-state NMR confirms the hybrid structure of hybrid electrolytes. > Li line width reveals that the mobility of Li ion is coupled with the polymer motion. > PGSE NMR indicates that polymer segmental mobility affects Li diffusion. - Abstract: A new hyperbranched organic-inorganic hybrid electrolyte based on the use of 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, CC) as the coupling core to couple with oligo(oxyalkylene)-amines, followed by condensation with (3-glycidoxypropyl)-trimethoxysilane (GLYMO) and complexed with LiClO{sub 4}, has been prepared and characterized. The Vogel-Tamman-Fulcher (VTF) like conductivity behavior is observed in the present organic-inorganic hybrid electrolytes with a maximum ionic conductivity value of 4.4 x 10{sup -5} S cm{sup -1} at 30 deg. C. Multinuclear NMR techniques are used to provide a microscopic view for the specific interaction between the polymer chains and Li{sup +} cations and their dynamic behaviors. The results of 2D {sup 1}H-{sup 13}C wide-line separation (WISE) and {sup 7}Li static line NMR width measurements divulge that the mobility of the {sup 7}Li cations is strongly related to a dynamic environment created by the polymer motion in the amorphous phase. The combined results of conductivity and {sup 7}Li pulse-gradient spin-echo (PGSE) NMR self-diffusion coefficient measurements reveal that the conductivity enhancement at low salt concentrations is mainly caused by the high mobility of the lithium cations.

  17. Solid electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ballard, D.G.H.; Cheshire, P.; Przeworski, J.E.

    1992-09-29

    A specific type of solid electrolyte is disclosed which contains a liquid yet which is dry in handling, dimensionally stable and flexible, and has good elastically resilient compression properties and good conductivity. The electrolyte is suitable for high energy density batteries and capacitors. The electrolyte of the invention comprises a matrix of cross-linked polymer main chains, to which side chains comprising polar groups free from active hydrogen atoms are linked; a polar aprotic liquid dispersed in the matrix; and an ionized ammonium, alkali metal or alkaline earth metal salt dissolved in the matrix and/or liquid. The solid electrolyte chains are cross-linked for good mechanical properties and to ensure that at a chosen loading of polar liquid, the solid electrolyte remains solid at ambient temperatures. The invention also provides a process for making the solid electrolyte. Electrochemical cells made with the electrolyte of the invention are capable of current densities of more than 0.5 A/m[sup 2] and energy densities in excess of 150 Wh/kg. Experiments are described to illustrate the preparation and properties of matrix precursors for the solid electrolyte of the invention. 3 figs., 1 tab.

  18. Linear and nonlinear rheology of wormlike micelles

    CERN Document Server

    Sood, A K; Basappa, G; Basappa, Geetha

    1999-01-01

    Several surfactant molecules self-assemble in solution to form long, cylindrical, flexible wormlike micelles. These micelles can be entangled with each other leading to viscoelastic phases. The rheological properties of such phases are very interesting and have been the subject of a large number of experimental and theoretical studies in recent years. We shall report on our recent work on the macrorheology, microrheology and nonlinear flow behaviour of dilute aqueous solutions of a surfactant CTAT (Cetyltrimethylammonium Tosilate). This system forms elongated micelles and exhibits strong viscoelasticity at low concentrations ($\\sim$ 0.9 wt%) without the addition of electrolytes. Microrheology measurements of $G(\\omega)$ have been done using diffusing wave spectroscopy which will be compared with the conventional frequency sweep measurements done using a cone and plate rheometer. The second part of the paper deals with the nonlinear rheology where the measured shear stress $\\sigma$ is a nonmonotonic function o...

  19. Synthesis and Compatibility of Ionic Liquid Containing Rod-Coil Polyimide Gel Electrolytes with Lithium Metal Electrodes

    Science.gov (United States)

    Tigelaar, Dean M.; Palker, Allyson E.; Meador, Mary Ann B.; Bennett, William R.

    2008-01-01

    A highly cross-linked polyimide-polyethylene oxide copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid RTIL or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide LiTFSi, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from less than 3 to greater than 1000 h at 60 C and 0.25 mA/cm2 current density.

  20. Rheology and deep tectonics

    Directory of Open Access Journals (Sweden)

    G. Ranalli

    1997-06-01

    Full Text Available The distribution of the rheological properties of the lithosphere in space, and their variations in time, have a profound effect on the resulting tectonic deformation. A classical way of estimating these properties makes use of rheological profiles (strength envelopes. Although rheological profiles are based on assumptions and approximations which limit their resolving power, they are an efficient first-order tool for the study of lithosphere rheology, and their application clarifies the dynamics of tectonic processes. Two examples of the interaction of rheology and tectonics are discussed, namely, the post-orogenic relaxation of Moho topography (which is an additional factor to be considered in tectonic inversion, and the strength control on the level of necking in extension (which may lead to apparent local isostasy at passive continental margins and in sedimentary basins.

  1. Propriedades reológicas e microestruturais de eletrólito de ZrO2/Y2O3 / Microstructural and rheological properties of ZrO2/Y2O3 electrolyte

    Scientific Electronic Library Online (English)

    H.A., Taroco; R. M. F., Basaglia; R. Z., Domingues; M., Brant; T., Matencio.

    2008-09-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Para reduzir a temperatura de operação das pilhas a combustível de óxido sólido (PaCOS), estruturas com filmes finos de eletrólito depositados, por aerografia, sobre suportes de anodo porosos foram desenvolvidas. As barbotinas, empregadas para fabricação dos filmes, foram preparadas a partir de susp [...] ensões com pós de zircônia estabilizada com ítria (ZEI), solventes, dispersantes, ligantes e plastificantes apropriados. Neste trabalho, foi feito o estudo da influência dos ligantes sobre a estabilidade das suspensões e as propriedades microestruturais dos filmes de ZEI. Três barbotinas foram elaboradas com composições diferentes de ligantes (0,5; 1,0 e 2,0 % p/p). Todas apresentaram comportamento de fluidos pseudoplásticos e tixotrópicos, de acordo com medidas de viscosidade e taxa de cisalhamento. Os filmes foram sinterizados a 1500 ºC/6h. As micrografias eletrônicas de varredura (MEV) foram tratadas através do programa Quantikov para determinar a porosidade do filme e o tamanho médio de grão da ZEI. Os filmes apresentaram porosidade adequada para serem empregados como eletrólito das PaCOS (entre 0,2 e 0,4 % ) e tamanho médio de grão entre 2,0 e 6,0 µm. A técnica de aerografia é adequada para fabricar eletrólito de ZEI para PaCOS. Abstract in english To reduce the operating temperature of solid oxide fuel cells, structures with thin films electrolytes, deposited by spray coating on porous anode were developed. The slurries used for the fabrication of the films were prepared using appropriates suspensions with ytria-stabilized zirconia (YSZ) powe [...] rs, solvents, dispersants, binders and plasticizers appropriates. In this work the study of the influence of the binders in the stability of the suspensions and the microstructures properties of the YSZ films were done. Three slurries were made with different composition of binders (0.5; 1.0 and 2.0 % in weight). All of them showed pseudo-plastics and thixotropics flow behavior, according to viscosities measurements and shear rate. The films were sintered to 1500 ºC /6 hours. The images of scanning electron micrographs (SEM) were treated by Quantikov program to determine the porosity of the film and average grain size of YSZ. The films showed adequate porosity for being used as SOFC electrolyte (between 0.2 and 0.4%) and average grain size between 2.0 and 6.0 µ m. The spray coating is a suitable technique to fabricate the YSZ electrolytes for SOFC.

  2. The Synthesis and Characterization of Ionic Liquids for Alkali-Metal Batteries and a Novel Electrolyte for Non-Humidified Fuel Cells

    Science.gov (United States)

    Tucker, Telpriore G.

    This thesis focused on physicochemical and electrochemical projects directed towards two electrolyte types: 1) class of ionic liquids serving as electrolytes in the catholyte for alkali-metal ion conduction in batteries and 2) gel membrane for proton conduction in fuel cells; where overall aims were encouraged by the U.S. Department of Energy. Large-scale, sodium-ion batteries are seen as global solutions to providing undisrupted electricity from sustainable, but power-fluctuating, energy production in the near future. Foreseen ideal advantages are lower cost without sacrifice of desired high-energy densities relative to present lithium-ion and lead-acid battery systems. Na/NiCl2 (ZEBRA) and Na/S battery chemistries, suffer from high operation temperature (>300ºC) and safety concerns following major fires consequent of fuel mixing after cell-separator rupturing. Initial interest was utilizing low-melting organic ionic liquid, [EMI+][AlCl 4-], with well-known molten salt, NaAlCl4, to create a low-to-moderate operating temperature version of ZEBRA batteries; which have been subject of prior sodium battery research spanning decades. Isothermal conductivities of these electrolytes revealed a fundamental kinetic problem arisen from "alkali cation-trapping effect" yet relived by heat-ramping >140ºC. Battery testing based on [EMI+][FeCl4 -] with NaAlCl4 functioned exceptional (range 150-180ºC) at an impressive energy efficiency >96%. Newly prepared inorganic ionic liquid, [PBr4+][Al2Br7-]:NaAl2Br 7, melted at 94ºC. NaAl2Br7 exhibited super-ionic conductivity 10-1.75 Scm-1 at 62ºC ensued by solid-state rotator phase transition. Also improved thermal stability when tested to 265ºC and less expensive chemical synthesis. [PBr4 +][Al2Br7-] demonstrated remarkable, ionic decoupling in the liquid-state due to incomplete bromide-ion transfer depicted in NMR measurements. Fuel cells are electrochemical devices generating electrical energy reacting hydrogen/oxygen gases producing water vapor. Principle advantage is high-energy efficiency of up to 70% in contrast to an internal combustion engine fuel cells are prone to carbon monoxide catalytic poisoning and polymer membrane degradation unless heavily hydrated under cell-pressurization. This novel "SiPOH" solid-electrolytic gel (originally liquid-state) operated in the fuel cell at 121ºC yielding current and power densities high as 731mAcm-2 and 345mWcm-2, respectively. Enhanced proton conduction significantly increased H2 fuel efficiency to 89.7% utilizing only 3.1mlmin-1 under dry, unpressurized testing conditions. All these energy devices aforementioned evidently have future promise; therefore in early developmental stages.

  3. Influence of arc duration time on the synthesis of carbon nanohorns by a gas-injected arc-in-water system: application to polymer electrolyte fuel cell electrodes

    International Nuclear Information System (INIS)

    Single-walled carbon nanohorns (SWCNH) can be synthesized by a gas-injected arc-in-water (GI-AIW) method at low cost. This study revealed the influence of arc discharge duration time on the yield of SWCNH in the synthesis using this method. As a result, the yield of SWCNH increased with the arc discharge duration time, while an increase in arc plasma temperature was observed. This result can be explained by considering that the increased temperature of the reaction zone can lead to an increase in carbon radical density, which can positively affect the production yield. Here, two arc discharge modes, continuous and discrete, were generated so that modes having different temperatures with the same discharge current could be compared. From this investigation, it was suggested that an excessive ion density may cause a decrease in SWCNH production. The as-grown SWCNH possessed a high specific surface area when the arc discharge current was optimized with continuous arc mode using the GI-AIW method. Such a product can support Pt catalyst with high dispersivity, leading to high performance in polymer electrolyte fuel cells as catalyst layers.

  4. Synthesis of Na-?''-Al2O3 electrolytes by microwave sintering precursors derived from the sol-gel method

    International Nuclear Information System (INIS)

    Na-?''-Al2O3 electrolytes were synthesized by the microwave sintering assisted sol-gel technique in this study. The precursor powders and microwave-sintered pellets were systematically investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM), differential scanning calorimetry (TG-DSC) and Fourier transform infrared (FT-IR) spectroscopy. The ionic conductivity of the microwave-sintered pellets was also measured based on AC impedance spectroscopy. It was found that the calcining temperature of the precursor powders derived from the sol-gel method was the key factor to affect the purity of Na-?''-Al2O3 in the pellets. The sintered pellets prepared from the powders calcined at 850 oC exhibited a purity of 94.4% Na-?''-Al2O3 and the density of the sintered pellets was 98.91% of the theoretical density of Na-?''-Al2O3. In addition, the sample showed an ionic conductivity of 0.01085 S cm-1 at 300 oC by AC impedance measurement.

  5. Synthesis of amorphous silica and sulfonic acid functionalized silica used as reinforced phase for polymer electrolyte membrane

    Science.gov (United States)

    Nhan Tran, Thanh; Pham, Thi Van Anh; Loan Phung Le, My; Phuong Thoa Nguyen, Thi; Tran, Van Man

    2013-12-01

    In this work silica (SiO2) and sulfonic acid-functionalized silica (sul-SiO2) were synthesized by sol–gel method from tetraethoxysilane (TEOS) and 3-mercatopropyltrimethoxysilane (MPTMS) with various ratios between them. The synthesized materials were characterized by x-ray diffraction (XRD) for crystalline structure, Brunauer–Emmet–Teller (BET) specific surface area analysis, transmission electronic microscopy (TEM) and dynamic light scattering (DLS) for particle size analysis, and ion exchange capacity (IEC) for determining sulfur content in Sul-SiO2 materials. The initial results showed that the average particle size of amorphous SiO2 and Sul-SiO2 at different TEOS: MPTMS ratios are in narrow distribution with average diameter about 20–30 nm. The particle size of Sul-SiO2 is almost unaffected by the content of MPTMS while IEC depends strongly on it. Composite membranes of 60 ?m thickness were successfully prepared from blending of poly(vinylidene fluoride) (PVDF) and synthesized amorphous SiO2. It was shown that the latter may be used as a reinforced phase for composite membrane electrolytes based on PVDF.

  6. Synthesis and properties of phenylindane-containing polybenzimidazole (PBI) for high-temperature polymer electrolyte membrane fuel cells (PEMFCs)

    Science.gov (United States)

    Li, Xin; Chen, Xiaoming; Benicewicz, Brian C.

    2013-12-01

    A thermally stable and organo-soluble phenylindane-containing polybenzimidazole (phenylindane-PBI) was synthesized from 3,3?,4,4?-tetraaminobiphenyl and 1,1,3-trimethyl-3-phenylindan-4?,5-dicarboxylic acid using polyphosphoric acid (PPA) as both solvent and dehydrating agent. Polymerization conditions were carefully investigated to achieve high molecular weight polymers (IV = 1.00 dL g-1). To study the effects of backbone structure on properties, meta-PBI was also synthesized in PPA. It was found the introduction of rigid bent phenylindane moiety into the polymer backbone greatly improved the polymer solubility in polar aprotic solvents. The fabrication of acid-doped phenylindane-PBI membranes was attempted by both sol-gel and acid imbibing processes. The membranes prepared by the latter method showed a maximum proton conductivity of 0.061 S cm-1 at 180 °C with a phosphoric acid doping level of 10.0 PA/RU. Both phenylindane-PBI and meta-PBI membranes were fabricated into membrane electrode assemblies (MEAs) and tested to evaluate their fuel cell performance. The phosphoric acid doped phenylindane-PBI membrane exhibited comparable fuel cell performance as meta-PBI under similar testing conditions, demonstrating that it is a promising polymer electrolyte membrane candidate for high-temperature fuel cell applications.

  7. Rheology of aqueous foams

    OpenAIRE

    Dollet, Benjamin; Raufaste, Christophe

    2014-01-01

    Aqueous foams are suspensions of bubbles inside aqueous phases. Their multiphasic compo-sition leads to a complex rheological behavior that is useful in numerous applications, from oil recovery to food/cosmetic processing. Their structure is very similar to the one of emulsions so that both materials share common mechanical properties. Meanwhile the gas-liquid interfaces and the presence of surfactants lead to peculiar interfacial and dissipative properties. Foam rheology has been an active r...

  8. A Pt-Fe carbon nitride nano-electrocatalyst for polymer electrolyte membrane fuel cells and Direct-Methanol fuel cells: synthesis, characterization, and electrochemical studies

    Energy Technology Data Exchange (ETDEWEB)

    Negro, E.; Gliubizzi, R.; Lavina, S.; Maccato, C. [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, 35131 Padova (Italy); Pace, G. [Istituto di Scienze e Tecnologie Molecolari, ISTM-CNR c/o Dipartimento di Processi Chimici dell' Ingegneria, Via Marzolo 9, 35131 Padova (Italy); Gross, S. [Istituto di Scienze e Tecnologie Molecolari, ISTM-CNR and INSTM, Via Marzolo 1, 35131 Padova (Italy); Di Noto, V.

    2007-11-23

    This report describes the preparation of a new nano-electrocatalyst for applications in polymer electrolyte fuel cells operating with H{sub 2} and methanol. The nano-electrocatalyst, having the composition K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}], consists of a distribution of Pt and Fe bimetallic clusters supported on carbon nitride nanoparticles. This material was synthesized by thermal treatment of a zeolitic inorganic-organic polymer electrolyte-like (Z-IOPE) precursor, prepared by reacting H{sub 2}PtCl{sub 6} and K{sub 3}Fe(CN){sub 6} in the presence of sucrose, as organic binder, in a water solution. This reaction allows the desired material to be prepared by means of a sol{yields}gel process followed by a gel{yields}plastic transition. The morphology and surface properties of K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}] were studied via scanning and high-resolution transmission electron microscopies and X-ray photoelectron spectroscopy. Far-infrared, mid-infrared, and micro-Raman-laser spectroscopies, as well as X-ray diffraction studies, together with detailed compositional data reveal the structural information and describe the interactions characterizing the mass activity of the K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}] system. This material has structural and morphological features that are very different to those usually found in commercially available electrocatalysts for application in H{sub 2} polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}] consists of active bimetallic catalytic sites supported on a mixture of {alpha} and graphitic carbon nitride-like nanoparticles. The studies performed by cyclic voltammetry with the thin-film rotating-disk electrode indicate that the performance of K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}] and of the EC-20 reference material is a) equal to -255 and -216 A g{sup -1} Pt, respectively, in the oxygen-reduction reaction at 0.75 V; and b) equal to 967 and 533 A g{sup -1} Pt, respectively, in the hydrogen-oxidation reaction at potentials lower than 0.2 V. The activation potential of K{sub 0.12}[Pt{sub 1}Fe{sub 1.6}C{sub 55}N{sub 0.12}] is about 15 mV higher than that of the EC-20 reference. In conclusion, the proposed synthesis route is general and promising for the development of new, improved nano-electrocatalysts for low-temperature fuel cells such as PEMFCs and DMFCs. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  9. Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

    Directory of Open Access Journals (Sweden)

    Hyuk Chang

    2013-01-01

    Full Text Available Elevated-temperature (100~200 °C polymer electrolyte membrane (PEM fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements.

  10. Cryogenic electrolytes

    International Nuclear Information System (INIS)

    The emphasis is made on experimentally observed indications of the presence of metastable ion dipoles in solid helium. Similar quasiparticles possessing positive scattering length for injected electrons are assumed to exist in liquid phases of cryogenic liquids. The observed phenomena allowing to detect and monitor the behavior of dipole gas in superfluid helium (referred to as cryogenic electrolyte) are discussed. Most interesting among these phenomena are: special features of the dielectric behavior of ion dipole gas, details of the temperature dependence of the ion dipole gas osmotic pressure at the boundary of the liquid 3He-4He solution stratification, relaxation phenomena of collective origin in cryogenic electrolytes, and liquid helium phonon spectrum transformation due to strong interaction between phonons and heavy dipole quasiparticles.

  11. Solid electrolytes

    Science.gov (United States)

    Abraham, Kuzhikalail M. (Needham, MA); Alamgir, Mohamed (Dedham, MA)

    1993-06-15

    This invention pertains to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized (encapsulated) in a solid organic polymer matrix. In particular, this invention relates to solid polymer electrolytes derived by immobilizing complexes (solvates) formed between a Li salt such as LiAsF.sub.6, LiCF.sub.3 SO.sub.3 or LiClO.sub.4 and a mixture of aprotic organic solvents having high dielectric constants such as ethylene carbonate (EC) (dielectric constant=89.6) and propylene carbonate (PC) (dielectric constant=64.4) in a polymer matrix such as polyacrylonitrile, poly(tetraethylene glycol diacrylate), or poly(vinyl pyrrolidinone).

  12. Rheology of giant micelles

    CERN Document Server

    Cates, M E; Cates, Michael E.; Fielding, Suzanne M.

    2006-01-01

    Giant micelles are elongated, polymer-like objects created by the self-assembly of amphiphilic molecules (such as detergents) in solution. Giant micelles are typically flexible, and can become highly entangled even at modest concentrations. The resulting viscoelastic solutions show fascinating flow behaviour (rheology) which we address theoretically in this article at two levels. First, we summarise advances in understanding linear viscoelastic spectra and steady-state nonlinear flows, based on microscopic constitutive models that combine the physics of polymer entanglement with the reversible kinetics of self-assembly. Such models were first introduced two decades ago, and since then have been shown to explain robustly several distinctive features of the rheology in the strongly entangled regime, including extreme shear-thinning. We then turn to more complex rheological phenomena, particularly involving spatial heterogeneity, spontaneous oscillation, instability, and chaos. Recent understanding of these comp...

  13. Rheological behavior of oxide nanopowder suspensions

    Science.gov (United States)

    Cinar, Simge

    Ceramic nanopowders offer great potential in advanced ceramic materials and many other technologically important applications. Because a material's rheological properties are crucial for most processing routes, control of the rheological behavior has drawn significant attention in the recent past. The control of rheological behavior relies on an understanding of how different parameters affect the suspension viscosities. Even though the suspension stabilization mechanisms are relatively well understood for sub-micron and micron size particle systems, this knowledge cannot be directly transferred to nanopowder suspensions. Nanopowder suspensions exhibit unexpectedly high viscosities that cannot be explained with conventional mechanisms and are still a topic of investigation. This dissertation aims to establish the critical parameters governing the rheological behavior of concentrated oxide nanopowder suspensions, and to elucidate the mechanisms by which these parameters control the rheology of these suspensions. Aqueous alumina nanopowders were chosen as a model system, and the findings were extrapolated to other oxide nanopowder systems such as zirconia, yttria stabilized zirconia, and titania. Processing additives such as fructose, NaCl, HCl, NaOH, and ascorbic acid were used in this study. The effect of solids content and addition of fructose on the viscosity of alumina nanopowder suspensions was investigated by low temperature differential scanning calorimetry (LT-DSC), rheological, and zeta potential measurements. The analysis of bound water events observed in LT-DSC revealed useful information regarding the rheological behavior of nanopowder suspensions. Because of the significance of interparticle interactions in nanopowder suspensions, the electrostatic stabilization was investigated using indifferent and potential determining ions. Different mechanisms, e.g., the effect of the change in effective volume fraction caused by fructose addition and electrostatic stabilization, were combined to optimize the viscosities and the ability to control the suspension viscosity. The intrinsic viscosities of nanopowder systems were estimated using the Krieger-Dougherty relation. Both the individual and the combined effects were evaluated using slip casting of green bodies. Also, ascorbic acid was used to disperse the alumina nanopowders (described here for the first time in the open literature). The mechanism of viscosity reduction was investigated by in situ Attenuated Total Reflectance Fourier Infrared Spectroscopy (ATR-FTIR), rheological, suspension pH, and zeta potential measurements. Lastly, the findings were extrapolated to several other oxide systems. The rheological behavior of zirconia, yttria stabilized zirconia, and titania nanopowder systems was investigated as a function of solids content, bound water, and intrinsic viscosity. The results indicated that nanopowder suspensions differ from sub-micron powder suspensions because of the higher bound water content and the short separation distances between particles causing increased interparticle interactions. The bound water event was associated with the powder surface. This layer differed from the electrostatic double layer in that it was modified by fructose molecules as well as by specifically adsorbed ions such as H+ and OH but not by indifferent electrolytes, such as NaCl. Because of the large surface area of nanopowders, this additional layer increased the effective solids content and led to higher viscosities. While the alumina suspensions were studied in detail, it was also shown that the bound water was not unique to the alumina nanopowder suspensions, but also present in other oxide systems. However, the bound water content was unique for each system and provided information about its origin. The presence of bound water resulted in lower the maximum achievable solids fractions for nanopowder systems. In order to achieve higher solids contents, the bound water layer had to be modified. Because of the limited separation distances and large surface areas of nano

  14. Synthesis and electrochemical properties of LiAl0.05Mn1.95O4 by the ultrasonic assisted rheological phase method

    International Nuclear Information System (INIS)

    Pure-phase and well-crystallized spinel LiAl0.05Mn1.95O4 powders were successfully synthesized by a simple ultrasonic assisted rheological phase (UARP) method. The structure and morphology properties of this as-prepared powder compared with the pristine LiMn2O4 and LiAl0.05Mn1.95O4 obtained from the solid-state reaction (SSR) method were investigated by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties focused on the LiAl0.05Mn1.95O4 by this new method have also been investigated in detail. According to these tests results, it is obviously to see that the newly prepared sample delivers a relatively high initial discharge capacity of 111.6 mAh g-1, presents excellent rate capability and reversibility, and shows good cycling stability with capacity retention of 90.6% after 70 cycles. Meanwhile, the electrochemical impedance spectroscopy (EIS) investigations were employed to study the electrochemical process of Li+ ions with the synthesized LiAl0.05Mn1.95O4 electrode in detail

  15. Electrolyte salts for nonaqueous electrolytes

    Science.gov (United States)

    Amine, Khalil; Zhang, Zhengcheng; Chen, Zonghai

    2012-10-09

    Metal complex salts may be used in lithium ion batteries. Such metal complex salts not only perform as an electrolyte salt in a lithium ion batteries with high solubility and conductivity, but also can act as redox shuttles that provide overcharge protection of individual cells in a battery pack and/or as electrolyte additives to provide other mechanisms to provide overcharge protection to lithium ion batteries. The metal complex salts have at least one aromatic ring. The aromatic moiety may be reversibly oxidized/reduced at a potential slightly higher than the working potential of the positive electrode in the lithium ion battery. The metal complex salts may also be known as overcharge protection salts.

  16. Synthesis of spinel Li{sub 4}Ti{sub 5}O{sub 12} anode material by a modified rheological phase reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yin, S.Y. [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Song, L. [College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000 (China); Wang, X.Y.; Zhang, M.F. [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Zhang, K.L. [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Centre of Nanoscience and Nanotechnology Research, Wuhan University, Wuhan 430072 (China)], E-mail: klzhang@whu.edu.cn; Zhang, Y.X. [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China)

    2009-10-01

    Using lithium acetate dihydrate and tetra-n-butyl titanate as the raw materials, spinel Li{sub 4}Ti{sub 5}O{sub 12} was successfully synthesized by a modified rheological phase method. Thermogravimetric analysis and differential scanning calorimetry (TG-DSC) of the thermal decomposition process of the precursor and X-ray diffraction (XRD) data indicate the crystallization of lithium titanates has occurred at 580 deg. C, and main phase Li{sub 4}Ti{sub 5}O{sub 12} has obtained at 600 deg. C. Laser granulometer and scanning electron microscope (SEM) have been employed to estimate the particle size distribution, morphology and microstructure of the products. It reveals the prepared Li{sub 4}Ti{sub 5}O{sub 12} powder had a small particle size (about 140 nm) and narrow size distribution (d{sub 0.1} = 0.07, d{sub 0.5} = 0.139, d{sub 0.9} = 2.813 {mu}m). Galvanostatic charge and discharge tests were carried out to characterize the electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}. The result indicates that the Li{sub 4}Ti{sub 5}O{sub 12} electrode material obtained from the precursor that had been experienced heat treatment at 110 deg. C exhibited discharge capacities of 161.6, 156.5 and 112.3 mAh g{sup -1} after 50 cycles at current rates 1, 2.5 and 10 C, respectively, demonstrating excellent high rate performance, due to the pure and well crystallized Li{sub 4}Ti{sub 5}O{sub 12} with ultrafine particles and narrow size distribution.

  17. Aerosol synthesis and electrochemical analysis of niobium mixed-metal oxides for the ethanol oxidation reaction in acid and alkaline electrolyte

    Science.gov (United States)

    Konopka, Daniel A.

    Direct ethanol fuel cells are especially important among emerging electrochemical power systems with the potential to offset a great deal of the energy demand currently met through the use of fossil fuels. Ethanol can be refined from petroleum sources or attained from renewable biomass, and is more easily and safely stored and transported than hydrogen, methanol or gasoline. The full energy potential of ethanol in fuel cells can only be realized if the reaction follows a total oxidation pathway to produce CO2. This must be achieved by the development of advanced catalysts that are electrically conductive, stable in corrosive environments, contain a high surface area on which the reaction can occur, and exhibit a bi-functional effect for the ethanol oxidation reaction (EOR). The latter criterion is achievable in mixed-metal systems. Platinum is an effective metal for catalyzing surface reactions of many adsorbates and is usually implemented in the form of Pt nanoparticles supported on inexpensive carbon. This carbon is believed to be neutral in the catalysis of Pt. Instead, carbon can be replaced with carefully designed metals and metal oxides as co-catalysis or support structures that favorably alter the electronic structure of Pt slightly through a strong metal support interaction, while also acting as an oxygen source near adsorbates to facilitate the total oxidation pathway. Niobium mixed-metal-oxides were explored in this study as bi-functional catalyst supports to Pt nanoparticles. We developed a thermal aerosol synthesis process by which mesoporous powders of mixed-metal-oxides decorated with Pt nanoparticles could be obtained from liquid precursors within ˜5 seconds or less, followed by carefully refined chemical and thermal post-treatments. Exceptionally high surface areas of 170--180m2/g were achieved via a surfactant-templated 3D wormhole-type porosity, comparable on a per volume basis to commercial carbon blacks and high surface area silica supports. For the first time, in situ FTIR measurements in acid electrolyte showed that highly dispersed Pt nanoparticles (2--5nm) on NbRuyO z (at% 8Nb:1Ru) catalyze the formation of CO2 from ethanol in greater yield, and 0.35--0.4V lower, than Pt(111). Compared to conventional Pt/carbon, this indicates that, (1) Pt supported on NbRuyO z can be more effective at splitting the C---C bond in ethanol and, (2) the scission occurs at potentials more ideal for a higher efficiency fuel cell anode. Ex situ-microscopy revealed the polarization-induced two- and three-dimensional formation of Pt-NbOx interfacial adsorption sites responsible for the facilitation of the total oxidation pathway of ethanol. The results show that synthesis and post-treatment of niobia supports can bias the utility of Pt/niobia systems towards the ethanol oxidation reaction at the anode or the oxygen reduction reaction at the cathode. Experimental and computational-theoretical analyses indicate that the mechanism of interfacial site formation is dependent upon the local oxygen concentration, as well as the availability of multiple, energetically accessible oxidation states like those inherent to niobia. Future directions for the development of highly active, niobium-based materials tailored for efficient catalysis of the total oxidation pathway of ethanol are discussed.

  18. Solid state electrolyte systems

    Energy Technology Data Exchange (ETDEWEB)

    Pederson, L.R.; Armstrong, B.L.; Armstrong, T.R. [Pacific Northwest Lab., Richland, WA (United States)] [and others

    1997-12-01

    Lanthanum gallates are a new family of solid electrolytes that exhibit high ionic conductivity and are stable to high temperatures. Compositions have been developed that are as much as a factor of two more conductive than yttria-stabilized zirconia at a given temperature, through partial replacement of lanthanum by calcium, strontium, and/or barium and through partial replacement of gallium by magnesium. Oxide powders were prepared using combustion synthesis techniques developed in this laboratory; these were sintered to >95% of theoretical density and consisted of a single crystalline phase. Electrical conductivities, electron and ion transference numbers, thermal expansion, and phase behavior were evaluated as a function of temperature and oxygen partial pressure. A key advantage of the use of lanthanum gallate electrolytes in solid oxide fuel cells is that the temperature of operation may be lowered to perhaps 800 C, yet provide approximately the same power density as zirconia-based cells operating at 1000 C. Ceramic electrolytes that conduct both oxygen ions and electrons are potentially useful to passively separate pure oxygen from an air source at low cost. In such materials, an oxygen ion flux in one direction is charge-compensated by an opposing electron flux. The authors have examined a wide range of mixed ion and electron conducting perovskite ceramics in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, where M = Sr, Ca, and Ba, and N = Pr, Mn, Ni, Cu, Ti, and Al, as well as mixed conducting brownmillerite ceramics, and have characterized oxygen permeation behavior, defect chemistry, structural and phase stability, and performance as cathodes.

  19. Rock and soil rheology

    International Nuclear Information System (INIS)

    The aim of the Euromech Colloquium 196 devoted to Rock and Soil Rheology is to review some of the main results obtained in the last years in this field of research and also to formulate some of the major not yet solved problems which are now under consideration. Exchange of opinions and scientific discussions are quite helpful mainly in those areas where some approaches are controversial and the progress made is quite fast. That is especially true for the rheology of geomaterials, domain of great interest for mining and petroleum engineers, engineering geology, seismology, geophysics, civil engineering, nuclear and industrial waste storage, geothermal energy storage, caverns for sports, culture, telecommunications, storage of goods and foodstuffs (cold, hot and refrigerated storages), underground oil and natural gas reservoirs etc. Some of the last obtained results are mentioned in the present volume. (orig./HP)

  20. Rheology of Aqueous Nanosuspensions.

    Czech Academy of Sciences Publication Activity Database

    Ve?e?, Marek; Tihon, Jaroslav; P?nkavová, V?ra

    Ostrava : Repronis, 2008 - (Holešová, S.; Martynková, G.), PP-37 ISBN 978-80-7329-190-7. [1st Nanomaterials and Nanotechnology Meeting Nano Ostrava 2008. Ostrava (CZ), 01.09.2008-04.09.2008] R&D Projects: GA ?R GP104/06/P287; GA ?R GA104/08/0428 Institutional research plan: CEZ:AV0Z40720504 Keywords : rheology * nanomaterials Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  1. Study of an industrial process for the synthesis of high molar mass ethylene oxide-propylene oxide copolymers usable as extrusible electrolyte; Etude d`un procede industriel de synthese de copolymeres oxyde d`ethylene-oxyde de propylene de hautes masses molaires utilisables comme electrolyte extrudable

    Energy Technology Data Exchange (ETDEWEB)

    Gramain, Ph. [Ecole Nationale Superieure de Chimie de Montpellier, 34 (France); Caselles, E. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France)

    1996-12-31

    The aim of this work is to develop an industrial process for the synthesis of an extrusible electrolyte polymer for lithium batteries. From literature data and precise specifications the high molar mass EO/OP copolymers synthesis by coordinative catalysis has been studied in order to reach a high productivity and to minimize the treatment steps. Two catalytic systems have been studied: the aluminium alkoxide-based Vandenberg-type catalysis and the calcium alcoholate amides catalysis. The first catalysis performed in solution gives excellent results. Its adaptation to silicon supported catalysis leads to a directly usable polymer in suspension but the productivity falls down and remains to be optimized. The calcium amide catalysis in heptane suspension generates acceptable productivities but also a too high proportion of low molar masses. Various approaches have been studied to minimize this proportion due to the presence of secondary sites that generate a cationic mechanism. The two synthesis ways explored are promising but remain to be optimized in order to increase the productivity of the efficient catalytic site and to reduce the formation of low molar masses generated by parasite catalytic sites. (J.S.) 9 refs.

  2. THE ANALYSIS OF CONCRETE RHEOLOGICAL CHARACTERISTICS BEHAVIOUR

    Directory of Open Access Journals (Sweden)

    Ramona PIN?OI

    2013-05-01

    Full Text Available In the rheological models used in the mathematical description of the rheological behavior ofconcrete. Plays stiffness modulus variation, tangential effort, apparent viscosity, friction angle.

  3. Synthesis and electrical properties of scheelite Ca{sub 1-x}Sm{sub x}MoO{sub 4+{delta}} solid electrolyte ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jihai, E-mail: cjh@hfuu.edu.cn [Department of Chemistry and Materials Engineering, Hefei University, Hefei 230022 (China); Key Lab of Powder and Energy Sources Materials, Hefei University, Hefei 230022 (China); Liu, Chenfei; Cao, Wenbing; Qi, Mingxing; Shao, Guoquan [Department of Chemistry and Materials Engineering, Hefei University, Hefei 230022 (China)

    2011-02-15

    Graphical abstract: Scheelite-type Ca{sub 1-x}Sm{sub x}MoO{sub 4+{delta}} electrolyte ceramics can be considered as one of the best candidates to replace the YSZ electrolyte materials for SOFCs because of their high oxide ion conduction. Research highlights: {yields} Sm{sub x}Ca{sub 1-x}MoO{sub 4+{delta}} solid electrolyte with a tetragonal scheelite structure. {yields} Sm{sub x}Ca{sub 1-x}MoO{sub 4+{delta}} electrolyte is one of the best candidates to replace the YSZ electrolyte for SOFCs because of their high oxide ion conduction. {yields} The sintering temperature is greatly lower than traditional YSZ electrolyte. -- Abstract: Scheelite-type Ca{sub 1-x}Sm{sub x}MoO{sub 4+{delta}} electrolyte powders were prepared by the sol-gel auto-combustion process. The crystal structure of the samples was determined by employing the techniques of X-ray diffraction (XRD). According to the XRD analysis, the formed continuous series of Ca{sub 1-x}Sm{sub x}MoO{sub 4+{delta}} (0 {<=} x {<=} 0.3) solid solutions had the structure of tetragonal scheelite, and the lattice parameters increased with increasing x in the Sm-substituted system. Results of sinterability and electrochemical testing revealed that the performances of Sm-doped calcium molybdate were superior to that of pure CaMoO{sub 4}. Ca{sub 1-x}Sm{sub x}MoO{sub 4+{delta}} ceramics show higher sinterability, and the Ca{sub 0.8}Sm{sub 0.2}MoO{sub 4+{delta}} sample with 98.7% of the theoretical density were obtained after being sintered at 1250 {sup o}C for 4 h. The conductivity increased with increasing samarium content, and a total conductivity 9.54 x 10{sup -3} S cm{sup -1} at 800 {sup o}C could be obtained in Ca{sub 0.8}Sm{sub 0.2}MoO{sub 4+{delta}} sintered at 1250 {sup o}C for 4 h.

  4. Rheology of Soft Materials

    Science.gov (United States)

    Chen, Daniel T. N.; Wen, Qi; Janmey, Paul A.; Crocker, John C.; Yodh, Arjun G.

    2010-04-01

    Research on soft materials, including colloidal suspensions, glasses, pastes, emulsions, foams, polymer networks, liquid crystals, granular materials, and cells, has captured the interest of scientists and engineers in fields ranging from physics and chemical engineering to materials science and cell biology. Recent advances in rheological methods to probe mechanical responses of these complex media have been instrumental for producing new understanding of soft matter and for generating novel technological applications. This review surveys these technical developments and current work in the field, with partial aim to illustrate open questions for future research.

  5. Charge relaxation dynamics of an electrolytic nanocapacitor

    OpenAIRE

    Thakore, Vaibhav; Hickman, James J.

    2013-01-01

    Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology based electrochemical energy storage, electrochemomechanical energy conversion and bioelectrochemical sensing devices as well as controlled synthesis of nanostructured materials. Here, a Lattice Boltzmann (LB) method is employed to simulate an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL...

  6. Molten salt electrolyte separator

    Science.gov (United States)

    Kaun, Thomas D. (New Lenox, IL)

    1996-01-01

    A molten salt electrolyte/separator for battery and related electrochemical systems including a molten electrolyte composition and an electrically insulating solid salt dispersed therein, to provide improved performance at higher current densities and alternate designs through ease of fabrication.

  7. Rheology for chemists an introduction

    CERN Document Server

    Goodwin, J W

    2008-01-01

    Rheology is primarily concerned with materials: scientific, engineering and everyday products whose mechanical behaviour cannot be described using classical theories. From biological to geological systems, the key to understanding the viscous and elastic behaviour firmly rests in the relationship between the interactions between atoms and molecules and how this controls the structure, and ultimately the physical and mechanical properties. Rheology for Chemists An Introduction takes the reader through the range of rheological ideas without the use of the complex mathematics. The book gives part

  8. Rheological properties of magnetic suspensions

    Science.gov (United States)

    Zubarev, A.; Iskakova, L.

    2008-05-01

    We present results of a theoretical study of the magnetorheological viscosity ? of a suspension versus the applied magnetic field H and shear rate \\dot {\\gamma } . It is supposed that the macroscopic rheological effects are provided by linear chain-like aggregates. Unlike in traditional models, the natural statistical distribution of the chains over the number of particles in them is taken into account. The results obtained explain important features of the rheological ? versus H,\\dot {\\gamma } law, which has been detected in experiments but qualitatively contradicts known theories of rheological properties of magnetic suspensions.

  9. Rheological properties of magnetic suspensions

    International Nuclear Information System (INIS)

    We present results of a theoretical study of the magnetorheological viscosity ? of a suspension versus the applied magnetic field H and shear rate ?. It is supposed that the macroscopic rheological effects are provided by linear chain-like aggregates. Unlike in traditional models, the natural statistical distribution of the chains over the number of particles in them is taken into account. The results obtained explain important features of the rheological ? versus H,? law, which has been detected in experiments but qualitatively contradicts known theories of rheological properties of magnetic suspensions

  10. Rheological properties of magnetic suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Zubarev, A; Iskakova, L [Department of Mathematical Physics, Ural State University, Lenin Avenue 51, Ekaterinburg (Russian Federation)], E-mail: andrey.zubarev@usu.ru

    2008-05-21

    We present results of a theoretical study of the magnetorheological viscosity {eta} of a suspension versus the applied magnetic field H and shear rate {gamma}. It is supposed that the macroscopic rheological effects are provided by linear chain-like aggregates. Unlike in traditional models, the natural statistical distribution of the chains over the number of particles in them is taken into account. The results obtained explain important features of the rheological {eta} versus H,{gamma} law, which has been detected in experiments but qualitatively contradicts known theories of rheological properties of magnetic suspensions.

  11. Rheology of Confined Liquids

    Science.gov (United States)

    Demirel, Adem Levent; Granick, Steve

    1996-03-01

    The shear rheology of molecularly thin nonpolar hydrocarbon liquid films has been studied as a function of oscillation frequency (linear response) and applied stress (non-linear response). Experiments were done by confining OMCTS (octamethylcyclotetrasiloxane) or squalane molecules between atomically smooth mica surfaces and applying an oscillatory shear. The film thickness dependence of the linear viscoelasticity of OMCTS showed that the transition from bulk viscous behavior to the confinement induced elastic state happened through a viscoelastic region where the relaxation time increased two orders of magnitude in a narrow region corresponding to 5 molecular layers. When the squalane film in the elastic state was driven with an applied stress larger than the critical value to yield, low frequency stress fluctuations with durations much larger than the oscillation period were observed. Such fluctuations were analyzed and correlated with the yield stress of the liquid film within each period.

  12. Synthesis and Characterization of Nafion-SiO2 Composite Membranes as an Electrolyte for Medium Temperature and Low Relative Humidity

    OpenAIRE

    Endang Sulistyowati; Harso Pawignyo; Purwo Subagyo; Eniya Listiani Dewi; Tjukup Marnoto; Mahreni Mahreni

    2011-01-01

    The weakness of the Nafion membrane as electrolyte of PEMFC associated with physical properties that is easy to shrink at temperatures above 80°C due to dehydration. Shrinkage will decrease the conductivity and membrane damage. Nafion-SiO2 composite membranes can improve membrane stability. The role of SiO2 in the Nafion clusters is as water absorbent cause the membrane remains wet at high temperatures and low humidity and conductivity remains high. The results showed the content of 2.8 w...

  13. Rheological properties of polypropylene nanocomposites

    International Nuclear Information System (INIS)

    In this work, composites of polypropylene with a master batch to obtain clay containing nano composites were obtained. The materials were characterized by X ray diffraction, small angle X-ray scattering and by rheological analysis. (author)

  14. Nanoporous polymer electrolyte

    Science.gov (United States)

    Elliott, Brian (Wheat Ridge, CO); Nguyen, Vinh (Wheat Ridge, CO)

    2012-04-24

    A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

  15. Electrolyte vapor condenser

    Science.gov (United States)

    Sederquist, Richard A. (Newington, CT); Szydlowski, Donald F. (East Hartford, CT); Sawyer, Richard D. (Canton, CT)

    1983-01-01

    A system is disclosed for removing electrolyte from a fuel cell gas stream. The gas stream containing electrolyte vapor is supercooled utilizing conventional heat exchangers and the thus supercooled gas stream is passed over high surface area passive condensers. The condensed electrolyte is then drained from the condenser and the remainder of the gas stream passed on. The system is particularly useful for electrolytes such as phosphoric acid and molten carbonate, but can be used for other electrolyte cells and simple vapor separation as well.

  16. Rheological measurements on cement grouts

    International Nuclear Information System (INIS)

    This report describes the techniques which have been developed at Winfrith for assessing the rheological properties of cement grouts. A discussion of the theory of rheology and its application to cement is given and the methodology for calibrating a special paddle measuring system for a commercial viscometer is described. The use of the system for determining flow curves, equilibrium viscosity, viscosity as a function of shearing time and structure changes is also discussed. (author)

  17. Rheological Modifiers and Wetting Agents

    International Nuclear Information System (INIS)

    DOE tank waste treatment plants, the Waste Treatment Plant (WTP) at Hanford and Defense Waste Processing Facility (DWPF) at Savannah River, are designed to vitrify radioactive waste slurries for long-term storage. Plant throughput is currently limited by the waste solids loading. To increase waste throughput rates in the plant, an increase in the slurry solids concentration (or conversely, a reduction in the mass fraction of water in the waste) is being considered. However, the present mechanical designs used to mix and transport theses slurries are limited by the rheological properties. This reduction of water results in an increase in rheological properties that challenge plant design and performance. To support this increase in throughput, there is a need to reduce the rheological properties of these waste slurries. The objective of this project is to determine a small set of well-performing and commercially available rheological modifiers that allow control rheological properties of various simulated and actual waste slurries and to understand the physical mechanisms that govern modification of waste rheology. It is estimated that processing at a higher solids concentration will reduce the operating life of these plants by one year for both facilities, representing roughly $1B in lifecycle cost savings. In addition, this research is potentially important to sustainable operations of both WTP and DWPF

  18. New polysaccharide-based polymer electrolytes; Nouveaux electrolytes polymeres a base de polysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Velasquez-Morales, P.; Le Nest, J.F.; Gandini, A. [Ecole Francaise de Papeterie et des Industries Graphique, 38 - Saint Martin d`Heres (France)

    1996-12-31

    Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer electrolytes has the same performances as ethylene poly-oxide based amorphous lattices plus the advantage of having good filmic properties. Abstract only. (J.S.)

  19. Synthesis and Characterization of Nafion-SiO2 Composite Membranes as an Electrolyte for Medium Temperature and Low Relative Humidity

    Directory of Open Access Journals (Sweden)

    Endang Sulistyowati

    2011-12-01

    Full Text Available The weakness of the Nafion membrane as electrolyte of PEMFC associated with physical properties that is easy to shrink at temperatures above 80°C due to dehydration. Shrinkage will decrease the conductivity and membrane damage. Nafion-SiO2 composite membranes can improve membrane stability. The role of SiO2 in the Nafion clusters is as water absorbent cause the membrane remains wet at high temperatures and low humidity and conductivity remains high. The results showed the content of 2.8 wt% of SiO2 in the Nafion membrane, the conductivity of composite membrane is higher than the pure Nafion membrane that are 0.127 S cm-1 in dry conditions and 0.778 S cm-1 in wet conditions at room temperature. Compared with the pure Nafion membrane conductivity are 0.0661 S cm-1 and 0.448 S cm-1 respectively in dry and wet conditions.

  20. Surface rheology and interface stability.

    Energy Technology Data Exchange (ETDEWEB)

    Yaklin, Melissa A.; Cote, Raymond O.; Moffat, Harry K.; Grillet, Anne Mary; Walker, Lynn; Koehler, Timothy P.; Reichert, Matthew D. (Carnegie Mellon University, Pittsburgh, PA); Castaneda, Jaime N.; Mondy, Lisa Ann; Brooks, Carlton, F.

    2010-11-01

    We have developed a mature laboratory at Sandia to measure interfacial rheology, using a combination of home-built, commercially available, and customized commercial tools. An Interfacial Shear Rheometer (KSV ISR-400) was modified and the software improved to increase sensitivity and reliability. Another shear rheometer, a TA Instruments AR-G2, was equipped with a du Nouey ring, bicone geometry, and a double wall ring. These interfacial attachments were compared to each other and to the ISR. The best results with the AR-G2 were obtained with the du Nouey ring. A Micro-Interfacial Rheometer (MIR) was developed in house to obtain the much higher sensitivity given by a smaller probe. However, it was found to be difficult to apply this technique for highly elastic surfaces. Interfaces also exhibit dilatational rheology when the interface changes area, such as occurs when bubbles grow or shrink. To measure this rheological response we developed a Surface Dilatational Rheometer (SDR), in which changes in surface tension with surface area are measured during the oscillation of the volume of a pendant drop or bubble. All instruments were tested with various surfactant solutions to determine the limitations of each. In addition, foaming capability and foam stability were tested and compared with the rheology data. It was found that there was no clear correlation of surface rheology with foaming/defoaming with different types of surfactants, but, within a family of surfactants, rheology could predict the foam stability. Diffusion of surfactants to the interface and the behavior of polyelectrolytes were two subjects studied with the new equipment. Finally, surface rheological terms were added to a finite element Navier-Stokes solver and preliminary testing of the code completed. Recommendations for improved implementation were given. When completed we plan to use the computations to better interpret the experimental data and account for the effects of the underlying bulk fluid.

  1. Polyelectrolyte Solution Rheology

    Science.gov (United States)

    Dou, Shichen; Colby, Ralph H.

    2008-07-01

    The viscosity and relaxation time of polyelectrolyte solutions in high dielectric constant solvents are reported. The effects of polyelectrolyte concentration, polyelectrolyte charge density, solvent dielectric constant, solvent quality and salt concentration are well described by scaling theory. New data are presented for partially quaternized poly(2-vinylpyridine) in ethylene glycol (EG) and N-methyl formamide (NMF). EG and NMF are good solvents for the neutral polymer before quaternization, enabling the effects of polyelectrolyte charge density to be studied over an unusually wide range. EG also can be purified to have an unusually low concentration of salt ion contaminants, allowing dilute solutions of high molecular weight polyelectrolytes to be studied in the low salt limit (whereas this is impossible for all aqueous solutions and solutions in NMF). Hence, the scaling model can be fully tested in EG solutions. After multiple distillations, NMF has even larger quantities of residual salt than distilled water. However, just like aqueous solutions, the rheology of polyelectrolyte solutions in NMF can be understood by identifying the concentration at which the number density of free counterions equals the number density of salt ions. At higher concentrations, the NMF solution viscosity obeys the low-salt scaling predictions and at lower concentrations the viscosity obeys the high-salt predictions.

  2. Dry granular flows: rheological measurements of the I-Rheology

    CERN Document Server

    Fall, Abdoulaye; Hautemayou, David; Mézière, Cédric; Roux, Jean-Noël; Chevoir, François

    2014-01-01

    Granular materials do not flow homogeneously like fluids when submitted to external stress,but often form rigid regions that are separated by narrow shear bands where the material yields and flows. This shear localization impacts their apparent rheology, which makes it difficult to infer a constitutive behaviour from conventional rheometric measurements. Moreover, they present a dilatant behaviour, which makes their study in classical fixedvolume geometries difficult. These features led to perform extensive studies with inclined plane flows, which were of crucial importance for the development and the validation of the $\\mu(I)$ rheology. Our aim is to develop a method to characterize granular materials with rheometrical tools. Using unusual rheometry measurements in an annular shear cell adapted from Boyer et al. (2011), dense granular flows are studied. A focus is placed on the comparison between the present results and the I-rheology.

  3. Rheological behavior of magneto-rheological grease (MRG)

    Science.gov (United States)

    Sahin, Huseyin; Gordaninejad, Faramarz; Wang, Xiaoije; Fuchs, Alan

    2007-04-01

    This paper presents an experimental study on the rheological properties of a magneto-rheological (MR) grease. MR fluids and MR greases are materials which consist of micron-size ferrous particles suspended in a carrier fluid. Their material properties such as apparent viscosity and shear stress can be altered dramatically and reversibly when stimulated by a magnetic field. The main difference between a MRG and a MR fluid is the viscosity of the carrier fluid. Unlike MR fluids, MRGs do not have the particle settling issue. The steady-shear magneto-rheological response of MRGs with at different temperatures is investigated. The results of apparent viscosity and yield stress under different applied magnetic fields are reported. In addition, the wall surface effect on the flow behavior of MRGs under different applied magnetic fields is examined using a slit channel flow device.

  4. Initial rheological description of high performance concretes

    OpenAIRE

    Alessandra Lorenzetti de Castro; Jefferson Benedicto Libardi Liborio

    2006-01-01

    Concrete is defined as a composite material and, in rheological terms, it can be understood as a concentrated suspension of solid particles (aggregates) in a viscous liquid (cement paste). On a macroscopic scale, concrete flows as a liquid. It is known that the rheological behavior of the concrete is close to that of a Bingham fluid and two rheological parameters regarding its description are needed: yield stress and plastic viscosity. The aim of this paper is to present the initial rheologic...

  5. Rheological Behaviour of Raw Cement

    Directory of Open Access Journals (Sweden)

    A. Lachemet

    2008-01-01

    Full Text Available A series of rheometric tests was conducted on raw cement at different concentrations and particle finesses as well. The paste of raw cement, formed by a set of particles suspensions in water, presents rheological properties that make it different from the fluids commonly used. The obtained results have showed that the rheological behaviour is the shear-thinning type and can be described satisfactorily by a model of Herschel-Bulkley, characterized by three parameters ?0, K and n which connect the shear stress to the shear rate. In addition, the parameter ?0 was correlated by an exponential function of the volume concentration of particles, this correlation is valid for both the raw cement and limestone. This latter is the main component of raw cement, for that reason its rheology has been studied.

  6. Rheological approaches to food systems

    Science.gov (United States)

    Fischer, Peter; Pollard, Michael; Erni, Philipp; Marti, Irene; Padar, Stefan

    2009-11-01

    Foods, consumer products and cosmetics belong to a wide range of colloidal and non-colloidal materials. Often, they are composite materials comprising several classes of fluid and solid constituents, including biopolymer gels, particulate suspensions, emulsions and foams. Length scales relevant for such materials may be anywhere between those associated with the molecular conformation of the ingredients up to long-scale dimensions of processing flows. The corresponding time scales may be in the sub-millisecond regime during aggregation of the ingredients or up to years during the shelf life of the final product. Rheological research of food material focuses on both the interaction between its ingredients, which might exhibit a complex rheological response function themselves and the influence of processing on the food structure and its properties. This brief overview summarizes suitable food rheology approaches and is grouped by the degree of abstraction of length scales and interactions. To cite this article: P. Fischer et al., C. R. Physique 10 (2009).

  7. Stabilized ?-BIMNVOX solid electrolyte: Ethylene glycol–citrate sol–gel synthesis, microwave-assisted calcination, and structural and electrical characterization

    International Nuclear Information System (INIS)

    Highlights: •?-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •?-BIMNVOX crystallizes by 25-min microwave-assisted calcination. •Smaller particle sizes for microwave calcined BIMNVOX samples. •Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of ?-BIMNVOX (Bi2V1?xMnxO5.5?x/2; 0.13 ? x ? 0.20) system were synthesized by an ethylene glycol–citrate sol–gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric–differential thermal analysis (TG–DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized ?-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined ?-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications

  8. Stabilized ?-BIMNVOX solid electrolyte: Ethylene glycol–citrate sol–gel synthesis, microwave-assisted calcination, and structural and electrical characterization

    Energy Technology Data Exchange (ETDEWEB)

    Al-Areqi, Niyazi A.S., E-mail: niyazi.alareqi@gmail.com [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Beg, Saba [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Al-Alas, Ahlam [Department of Chemistry, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen (Yemen); Hafeez, Shehla [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India)

    2013-12-25

    Highlights: •?-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •?-BIMNVOX crystallizes by 25-min microwave-assisted calcination. •Smaller particle sizes for microwave calcined BIMNVOX samples. •Best oxide-ion performance for microwave calcined BIMNVOX samples. -- Abstract: Samples of ?-BIMNVOX (Bi{sub 2}V{sub 1?x}Mn{sub x}O{sub 5.5?x/2}; 0.13 ? x ? 0.20) system were synthesized by an ethylene glycol–citrate sol–gel route. The resulting xerogels were then calcined by the microwave heating using a modified domestic microwave oven operated at 2.45 GHz. Microwave-assisted calcination samples in comparison with other conventionally calcined samples were characterized in terms of phase crystallization, stabilization and particle size using simultaneous thermogravimetric–differential thermal analysis (TG–DTA), X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). The AC impedance spectroscopy was employed for electrical characterization. It was found that the microwave-assisted calcination route successfully produces better crystalline stabilized ?-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined ?-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications.

  9. Synthesis of 8YSZ-LSGM Composite Thick Film Ceramics for Solid Electrolyte From Nanopowder Utilizing Local Zircon Prepared Using Sol Gel Process

    Science.gov (United States)

    Syarif, Dani Gustaman; Soepriyanto, Syoni; Ismunandar, Korda, Akhmad

    2010-10-01

    Thick film ceramics of 8% mol Y2O3 doped-ZrO2 (8YSZ)-La0.8Sr0.2Ga0.2Mg0.8O3 (LSGM) composite for solid electrolyte have been synthesized from nanopowder. Concentration of LSGM was 0 and 10% weight. A paste for the thick films was made from 8YSZ nanopowder prepared using sol gel method and LSGM powder prepared by solid state reaction. Precursors for the 8YSZ nanopowder preparation were ZrOCl2?8H2O derived from local zircon as byproduct of Tin processing at Bangka Island using caustic fussion method, and Y(NO3)3. The thick films were produced by screen printing technique on alumina substrates. The films were sintered at 1500° C for 2 hours in air. X-ray diffraction (XRD) data showed that the nanopowder of 8YSZ was well produced with broad peaks. The particle size of the 8YSZ powder was about 12 nm as calculated using Debye Scherrer method. The thick films of 8YSZ and 8YSZ-LSGM (90:10 in weight %) composite could be produced, however, the films still contain voids. The ionic conductance of the YSZ-10LSGM films was smaller than that of the YSZ films.

  10. Synthesis of 8YSZ-LSGM Composite Thick Film Ceramics for Solid Electrolyte From Nanopowder Utilizing Local Zircon Prepared Using Sol Gel Process

    International Nuclear Information System (INIS)

    Thick film ceramics of 8% mol Y2O3 doped-ZrO2(8YSZ)-La0.8Sr0.2Ga0.2Mg0.8O3(LSGM) composite for solid electrolyte have been synthesized from nanopowder. Concentration of LSGM was 0 and 10% weight. A paste for the thick films was made from 8YSZ nanopowder prepared using sol gel method and LSGM powder prepared by solid state reaction. Precursors for the 8YSZ nanopowder preparation were ZrOCl2·8H2O derived from local zircon as byproduct of Tin processing at Bangka Island using caustic fusion method, and Y(NO3)3. The thick films were produced by screen printing technique on alumina substrates. The films were sintered at 1500 deg. C for 2 hours in air. X-ray diffraction (XRD) data showed that the nanopowder of 8YSZ was well produced with broad peaks. The particle size of the 8YSZ powder was about 12 nm as calculated using Debye Scherrer method. The thick films of 8YSZ and 8YSZ-LSGM (90:10 in weight %) composite could be produced, however, the films still contain voids. The ionic conductance of the YSZ-10LSGM films was smaller than that of the YSZ films.

  11. Molecular Rheology of Complex Fluids

    DEFF Research Database (Denmark)

    Huang, Qian

    2013-01-01

    The processing of polymer materials is highly governed by its rheology, and influences the properties of the final product. For example, a recurring problem is instability in extrusion that leads to imperfect plastic parts. The ability to predict and control the rheological behavior of polymer fluids as a function of molecular chemistry has attracted a long history of collaboration between industry and academia. In industrial polymer processes, there is usually a combination of both shear and extensional flows. In some processing operations such as blow molding and fiber spinning, extensional flow is the dominant type of deformation. The polymer molecules experience a significant amount of chain orientation and stretching during these processes. Shear rheology measured by conventional shear rheometers is good at describing chain orientation, whereas extensional rheology gives a good way of inducing chain stretching. Accurate and reliable stress–strain measurements of extensional flow play a crucial role in the understanding of non–linear rheological properties of polymers. However, the non–linear extensional rheology has not been extensively studied. It is known that the rheology of polymer melts is highly sensitive to molecular architecture, but the precise connection between architecture and non–linear rheology is still not fully understood. For example, linear polymer melts have the simplest architecture, but the possible existence of a qualitative difference on extensional steady–state viscosity between melts and solutions is still an open question. Branched polymer melts have more complex molecular structures. A stress maximum during the start–up of uniaxial extensional flow was reported in 1979 for a low–density polyethylene (LDPE) melt. Subsequently observations of a steady stress following a stress maximum were reported for two LDPE melts. However the rheological significance of the stress maximum as well as the existence of steady flow conditions following the maximum is still a matter of some debate. This thesis focuses on the experimental study of extensional rheology of linear and branched polymer melts. We report the stress–strain measurements in extensional flows using a unique Filament Stretching Rheometer (FSR) in controlled strain rate mode and controlled stress mode. Extensional flow is difficult to measure reliably in Laboratory circumstances. In this thesis we first present an updated control scheme that allows us to control the kinematics of polymer melts in an FSR, which is the foundation of our experimental work. Next we investigate four categories of polymer melts from the simplest system to the most complicated system, including 1) the narrow molar mass distribution (NMMD) linear polystyrene melts and solutions; 2) the bidisperse and polydisperse linear polystyrene melts; 3) the NMMD branched polystyrene melts; and 4) the polydisperse branched polyethylene melts. The experimental results are also compared with some developing theoretical models. Finally, to ensure the experimental data is accurate, the measurements from the FSR are compared with the data from some other extensional rheometers as well.

  12. Sol-Gel Synthesis and Conductivity Properties of Sodium Ion Solid State Electrolytes Na3Zr2Si2PO12

    Directory of Open Access Journals (Sweden)

    ZHANG Zhi-Zhen, SHI Si-Qi, HU Yong-Sheng, CHEN Li-Quan

    2013-11-01

    Full Text Available NASICON-structured Na3Zr2Si2PO12 was synthesized by a Sol-Gel approach. Phase-pure samples were successfully sintered at 1050? when adding 10% excessive Na and P in the precursors, while a small amount of ZrO2 impurity was detected without adding excessive phosphorus. Electrochemical impedance spectrum tests indicate that the ionic conductivity of the former is as high as 5.4×10-4 S/cm at room temperature, which is higher than that of samples prepared from the precursors without adding excessive phosphorus (3.7×10-4 S/cm. Further analysis reveals that the evaporation of phosphorus at high temperature would cause the formation of ZrO2 impurity in the samples, leading to a lower ionic conductivity. Compared with solid state reaction approach, samples with enhanced ionic conductivity can be obtained at a rather lower temperature by Sol-Gel synthesis.

  13. Facile synthesis of porous metal oxide nanotubes and modified nafion composite membranes for polymer electrolyte fuel cells operated under low relative humidity.

    Science.gov (United States)

    Ketpang, Kriangsak; Lee, Kibong; Shanmugam, Sangaraju

    2014-10-01

    We describe a facile route to fabricate mesoporous metal oxide (TiO2, CeO2 and ZrO1.95) nanotubes for efficient water retention and migration in a Nafion membrane operated in polymer electrolyte fuel cell under low relative humidity (RH). Porous TiO2 nanotubes (TNT), CeO2 nanotubes (CeNT), and ZrO1.95 (ZrNT) were synthesized by calcining electrospun polyacrylonitrile nanofibers embedded with metal precursors. The nanofibers were prepared using a conventional single spinneret electrospinning technique under an ambient atmosphere. Their porous tubular morphology was observed by SEM and TEM analyses. HR-TEM results revealed a porous metal oxide wall composed of small particles joined together. The mesoporous structure of the samples was analyzed using BET. The tubular morphology and outstanding water absorption ability of the TNT, CeNT, and ZrNT fillers resulted in the effective enhancement of proton conductivity of Nafion composite membranes under both fully humid and dry conditions. Compared to a commercial membrane (Nafion, NRE-212) operated under 100% RH at 80 °C, the Nafion-TNT composite membrane delivered approximately 1.29 times higher current density at 0.6 V. Compared to the Nafion-TiO2 nanoparticles membrane, the Nafion-TNT membrane also generated higher current density at 0.6 V. Additionally, compared to a NRE-212 membrane operated under 50% RH at 80 °C, the Nafion-TNT composite membrane exhibited 3.48 times higher current density at 0.6 V. Under dry conditions (18% RH at 80 °C), the Nafion-TNT, Nafion-CeNT, and Nafion-ZrNT composite membranes exhibited 3.4, 2.4, and 2.9 times higher maximum power density, respectively, than the NRE-212 membrane. The remarkably high performance of the Nafion composite membrane was mainly attributed to the reduction of ohmic resistance by the mesoporous hygroscopic metal oxide nanotubes, which can retain water and effectively enhance water diffusion through the membrane. PMID:25203667

  14. Hybrid inorganic-organic polymer electrolytes: synthesis, FT-Raman studies and conductivity of {Zr[(CH2CH2O)8.7]?/(LiClO4)z}n network complexes

    International Nuclear Information System (INIS)

    This paper describes the synthesis and characterization of three-dimensional hybrid inorganic-organic networks prepared by a polycondensation reaction between Zr(O(CH2)3CH3)4 and polyethylene glycol 400 (PEG400). Eleven hybrid networks doped with varying concentrations of LiClO4 salt were prepared. On the basis of analytical data and FT-Raman studies it was concluded that these polymer electrolytes consist of inorganic-organic networks with zirconium atoms bonded together by PEG400 bridges. These polymers are transparent with a solid rubber consistency and are very stable under inert atmosphere. Scanning electron microscopy revealed a smooth glassy surface. X-ray fluorescence microanalysis with energy dispersive spectroscopy demonstrated that all the constituent elements are homogeneously distributed in the materials. Thermogravimetric measurements revealed that these materials are thermally stable up to 262 deg. C. Differential Scanning Calorimetry measurements indicated that the glass transition temperature Tg of these inorganic-organic hybrids varies from -43 to -15 deg. C with increasing LiClO4 concentration. FT-Raman investigations revealed the TGT (T=trans, G=gauche) conformation of polyether chains and allowed characterization of the types of ion-ion and ion-polymer host interactions in the bulk materials. The conductivity of the materials at different temperatures was determined by imifferent temperatures was determined by impedance spectroscopy over the 20 Hz-1 MHz frequency range. Results indicated that the materials conduct ionically and that their ionic conductivity is strongly influenced by the segmental motion of the polymer network and the type of ionic species distributed in the bulk material. Finally, it is to be highlighted that the hybrid network with a nLi/nO molar ratio of 0.0223 shows a conductivity of ca. 1x10-5 S cm-1 at 40 deg. C

  15. Summary Of 2009 Rheology Modifier Program

    International Nuclear Information System (INIS)

    The overall objective of the EM-31 Rheological Modifiers and Wetting Agents program is to utilize commercially available rheology modifiers to increase the solids fraction of radioactive sludge based waste streams, resulting in an increase in throughput and decreasing the overall processing time. The program first investigates the impact of rheology modifiers on slurry simulants and then utilizes the most effective rheology modifiers on radioactive slurries. The work presented in this document covers the initial investigation of rheology modifier testing with simulants. This task is supported by both the Savannah River National Laboratory (SRNL) and Pacific Northwest National Laboratory (PNNL). The SRNL EM-31 task, for this year, was to investigate the use of rheology modifiers on simulant Defense Waste Processing Facility (DWPF) melter feeds. The task is to determine, based on the impact of the rheology modifier, if there are rheology modifiers that could reduce the water content of the slurry going to the DWPF melter, hence increasing the melt rate by decreasing the water loading. The rheology modifier in essence would allow a higher solids content slurry to have the same type of rheology or pumpability of a lower solids slurry. The modifiers selected in this report were determined based on previous modifiers used in high level waste melter feed simulants, on-going testing performed by counterparts at PNNL, and experiences gain through use of modifiers in other Depaain through use of modifiers in other Department of Energy (DOE) processes such as grout processing. There were 12 rheology modifiers selected for testing, covering both organic and inorganic types and they were tested at four different concentrations for a given melter feed. Five different DWPF melter feeds were available and there was adequate material in one of the melter feeds to increase the solids concentration, resulting in a total of six simulants for testing. The mass of melter feed available in each simulant was not adequate for testing each rheology modifier, hence based on the changes in rheology for a given rheology modifier, rheology modifiers were either dropped or added between simulants. Three rheology modifiers were used on all simulants. The results from this testing indicate that citric acid or polycarboxylate based rheology modifiers are the most effective in reducing the yield stress, by as much as 70% at the higher rheology modifier additions and were effective on most of the tested simulants. These rheology modifiers are organic, hence the can also be used as reductants in melter operations. The most effective non-organic rheology modifiers, sodium metasilicate reduced the yield stress by 10%. It is recommended that both citric acid and commercially available polycarboxylate rheology modifiers be further investigated. Different molecular weight polycarboxylates and different types of polycarboxylates used in other industries must be considered. These polycarboxylates are extensively utilized in the cement, ceramic, and water treatment processes, hence readily available. Future work on DWPF melter feeds involving rheology modifiers should include, assuming the present method of processing sludge through DPWF does not change, is: (1) Investigate the use of polycarboxylate in various processes and procure polycarboxylates for testing. Limit rheology modifier selection and future testing between four and eight different types. (2) Test rheology modifiers on at least two different chemical types or bounding DWPF SME product simulants. Test to include the impact of boiling and the effectiveness in reducing water content via rheology versus weight percent curves. (3) Based on selected modifiers, perform testing on actual radioactive melter feed based on results from simulant testing.

  16. SUMMARY OF 2009 RHEOLOGY MODIFIER PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, E.

    2009-12-08

    The overall objective of the EM-31 Rheological Modifiers and Wetting Agents program is to utilize commercially available rheology modifiers to increase the solids fraction of radioactive sludge based waste streams, resulting in an increase in throughput and decreasing the overall processing time. The program first investigates the impact of rheology modifiers on slurry simulants and then utilizes the most effective rheology modifiers on radioactive slurries. The work presented in this document covers the initial investigation of rheology modifier testing with simulants. This task is supported by both the Savannah River National Laboratory (SRNL) and Pacific Northwest National Laboratory (PNNL). The SRNL EM-31 task, for this year, was to investigate the use of rheology modifiers on simulant Defense Waste Processing Facility (DWPF) melter feeds. The task is to determine, based on the impact of the rheology modifier, if there are rheology modifiers that could reduce the water content of the slurry going to the DWPF melter, hence increasing the melt rate by decreasing the water loading. The rheology modifier in essence would allow a higher solids content slurry to have the same type of rheology or pumpability of a lower solids slurry. The modifiers selected in this report were determined based on previous modifiers used in high level waste melter feed simulants, on-going testing performed by counterparts at PNNL, and experiences gain through use of modifiers in other Department of Energy (DOE) processes such as grout processing. There were 12 rheology modifiers selected for testing, covering both organic and inorganic types and they were tested at four different concentrations for a given melter feed. Five different DWPF melter feeds were available and there was adequate material in one of the melter feeds to increase the solids concentration, resulting in a total of six simulants for testing. The mass of melter feed available in each simulant was not adequate for testing each rheology modifier, hence based on the changes in rheology for a given rheology modifier, rheology modifiers were either dropped or added between simulants. Three rheology modifiers were used on all simulants. The results from this testing indicate that citric acid or polycarboxylate based rheology modifiers are the most effective in reducing the yield stress, by as much as 70% at the higher rheology modifier additions and were effective on most of the tested simulants. These rheology modifiers are organic, hence the can also be used as reductants in melter operations. The most effective non-organic rheology modifiers, sodium metasilicate reduced the yield stress by 10%. It is recommended that both citric acid and commercially available polycarboxylate rheology modifiers be further investigated. Different molecular weight polycarboxylates and different types of polycarboxylates used in other industries must be considered. These polycarboxylates are extensively utilized in the cement, ceramic, and water treatment processes, hence readily available. Future work on DWPF melter feeds involving rheology modifiers should include, assuming the present method of processing sludge through DPWF does not change, is: (1) Investigate the use of polycarboxylate in various processes and procure polycarboxylates for testing. Limit rheology modifier selection and future testing between four and eight different types. (2) Test rheology modifiers on at least two different chemical types or bounding DWPF SME product simulants. Test to include the impact of boiling and the effectiveness in reducing water content via rheology versus weight percent curves. (3) Based on selected modifiers, perform testing on actual radioactive melter feed based on results from simulant testing.

  17. Solid electrolyte cell

    Science.gov (United States)

    Richter, R. (inventor)

    1982-01-01

    A solid electrolyte cell including a body of solid ionized gas-conductive electrolyte having mutually spaced surfaces and on which is deposited a multiplicity of mutually spaced electrodes is described. Strips and of bare substances are interposed between electrodes, so that currents of ionic gas may be established between the electrodes via the bare strips, whereby electrical resistance for the cells is lowered and the gas conductivity is enhanced.

  18. Nuclear electrolytic hydrogen

    International Nuclear Information System (INIS)

    An extensive study of hydrogen supply has recently been carried out by Ontario Hydro which indicates that electrolytic hydrogen produced from nuclear electricity could offer the lowest cost option for any future large scale hydrogen supply in the Province of Ontario, Canada. This paper provides a synopsis of the Ontario Hydro study, a brief overview of the economic factors supporting the study conclusion and discussion of a number of issues concerning the supply of electrolytic hydrogen by electric power utilities

  19. Rheology and stability of water-in-oil-in-water multiple emulsions containing Span 83 and Tween 80

    OpenAIRE

    Jiao, Jim; Burgess, Diane J.

    2003-01-01

    Multiple emulsions are often stabilized using a combination of hydrophilic and hydrophobic surfactants. The ratio of these surfactants is important in achieving stable multiple emulsions. The objective of this study was to evaluate the long-term stability of water-in-oil-in-water (W/O/W) multiple emulsions with respect to the concentrations of Span 83 and Tween 80. In addition, the effect of surfactant and electrolyte concentration on emulsion bulk rheological properties was investigated. Lig...

  20. Toughness of membranes applied in polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kiefer, J.; Brack, H.P.; Scherer, G.G. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Since several years we apply the radiation-grafting technique to prepare polymeric membranes for application in polymer electrolyte fuel cells (PEFCs). Our investigations presented here focus on changes in toughness of these materials after the various synthesis steps and the importance of membrane toughness for their application in PEFCs. (author) 2 figs., 4 refs.

  1. Design of Hybrid Solid Polymer Electrolytes: Structure and Properties

    Science.gov (United States)

    Bronstein, Lyudmila M.; Karlinsey, Robert L.; Ritter, Kyle; Joo, Chan Gyu; Stein, Barry; Zwanziger, Josef W.

    2003-01-01

    This paper reports synthesis, structure, and properties of novel hybrid solid polymer electrolytes (SPE's) consisting of organically modified aluminosilica (OM-ALSi), formed within a poly(ethylene oxide)-in-salt (Li triflate) phase. To alter the structure and properties we fused functionalized silanes containing poly(ethylene oxide) (PEO) tails or CN groups.

  2. Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine) and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

    OpenAIRE

    Hyuk Chang; Jong-Chan Lee; Kyoung Hwan Choi; Chanho Pak; Seong-Woo Choi; Jung Ock Park

    2013-01-01

    Elevated-temperature (100~200 °C) polymer electrolyte membrane (PEM) fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked poly...

  3. Chocolate rheology / Reologia de chocolate

    Scientific Electronic Library Online (English)

    Estela Vidal, Gonçalves; Suzana Caetano da Silva, Lannes.

    2010-12-01

    Full Text Available Reologia é a ciência que estuda a deformação e fluxo de sólidos e fluidos sob a influência de forças mecânicas. As determinações reológicas de um produto no estágio de produção podem ser úteis no controle de qualidade. A microestrutura de um produto pode ser correlacionada com o comportamento reológ [...] ico, permitindo desenvolver novos materiais. A reometria permite a aplicação de equações reológicas em processos de engenharia, particularmente nas operações unitárias que envolvem aquecimento e transferência de massa. A demanda dos consumidores torna possível obter um produto que esteja de acordo com as necessidades. As indústrias de chocolates trabalham com o produto na fase líquida na concha, na temperadeira e também durante o bombeamento. O desenho de cada tipo de equipamento é essencial para o ótimo processamento. No desenho de cada processo é necessário conhecer as características físicas do produto. O comportamento reológico do chocolate pode auxiliar no conhecimento das características de aplicação e dos consumidores do produto. Alimentos estão geralmente em estado metaestável. Sua textura depende das trocas estruturais que ocorrem com seu processamento. Chocolate líquido é uma suspensão com propriedades que são fortemente afetadas pelas características das partículas, incluindo não somente partículas dispersas mas também cristais de gordura formados durante o resfriamento e solidificação. A reologia de chocolates é extensivamente estudada, a textura do chocolate e sua estabilidade são fortemente afetadas pela presença de cristais específicos Abstract in english Rheology is the science that studies the deformation and flow of solids and fluids under the influence of mechanical forces. The rheological measures of a product in the stage of manufacture can be useful in quality control. The microstructure of a product can also be correlated with its rheological [...] behavior allowing for the development of new materials. Rheometry permits attainment of rheological equations applied in process engineering, particularly unit operations that involve heat and mass transfer. Consumer demands make it possible to obtain a product that complies with these requirements. Chocolate industries work with products in a liquid phase in conching, tempering, and also during pumping operations. A good design of each type of equipment is essential for optimum processing. In the design of every process, it is necessary to know the physical characteristics of the product. The rheological behavior of chocolate can help to know the characteristics of application of the product and its consumers. Foods are generally in a metastable state. Their texture depends on the structural changes that occur during processing. Molten chocolate is a suspension with properties that are strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Chocolate rheology is extensively studied, and it is known that chocolate texture and stability is strongly affected by the presence of specific crystals

  4. Rheology of unstable mineral emulsions

    Directory of Open Access Journals (Sweden)

    Sokolovi? Dunja S.

    2013-01-01

    Full Text Available In this paper, the rheology of mineral oils and their unstable water emulsion were investigated. The oil samples were domestic crude oil UA, its fractions UA1, UA4 and blend semi-product UP1, while the concentration of oil in water emulsions was in the range from 1 up to 30%. The results were analyzed based on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear stress (83.75 Pa, 297 Pa, then other two samples UA1 and UP1 (18.41 Pa, 17.52 Pa. Rheology of investigated oils due to its complex chemical composition should be analyzed as a simultaneous effect of all their components. Therefore, structural composition of the oils was determined, namely content of paraffins, naphthenes, aromatics and asphaltenes. All samples contain paraffins, naphthenes and aromatics but only oils UA and UA4 contain asphaltenes as well. All investigated emulsions except 30% EUA4 are Newtonian fluids. The EUA4 30% emulsion shows pseudoplastic behaviour, and it is the only 30% emulsion among investigated ones that achieves lower shear stress then its oil. The characteristics of oil samples that could have an influence on their properties and their emulsion rheology, were determined. These characteristics are: neutralization number, interfacial tension, dielectric constant, and emulsivity. Oil samples UA and UA4 have significantly higher values of neutralization number, dielectric constants, and emulsivity. The sample UA has the lowest value of interface tension and the greatest emulsivity, indicating that this oil, among all investigated, has the highest preference for building emulsion. This could be the reason why 20% and 30% emulsions of the oil UA achieve the highest shear stress among all investigated emulsions.

  5. Rheology of coal slurries. 1; Sekitan slurry no rheology

    Energy Technology Data Exchange (ETDEWEB)

    Usui, H. [Yamaguchi University, Yamaguchi (Japan)

    1995-09-20

    This paper summarizes rheological characteristics of coal slurries. Steady state models for coal slurries include the index law model, the Bingham model including yield stress in high shear velocity regions, and the Herschel-Bulkley model for the case of nonlinearity in regions higher than the yield stress. The Casson model is used to express nonlinearity and yield stress in slurry flows in middle to low shear velocity regions. While parameters for the models have been determined experimentally, discussions are given in the field of rheology on methods to forecast flow characteristics from slurry adjustment parameters. These methods may include the Einstein expression, the Guth-Simha expression, the Thomas forecasting expression, and the Happel`s cell model. The Mooney expression and the Roscoe expression are the semi-empirical expressions that can be applied to coagulation systems. Slurry preparation importantly requires high coal concentration and fluidity. For this requirement, an expression for the optimum grain size distribution has been proposed. This expression provides a volumetric rate for filling largest particles when a grain size distribution range is limited. The larger the rate, the freedom of movements of solid particles becomes larger. 18 refs., 4 figs.

  6. Batteries using molten salt electrolyte

    Science.gov (United States)

    Guidotti, Ronald A. (Albuquerque, NM)

    2003-04-08

    An electrolyte system suitable for a molten salt electrolyte battery is described where the electrolyte system is a molten nitrate compound, an organic compound containing dissolved lithium salts, or a 1-ethyl-3-methlyimidazolium salt with a melting temperature between approximately room temperature and approximately 250.degree. C. With a compatible anode and cathode, the electrolyte system is utilized in a battery as a power source suitable for oil/gas borehole applications and in heat sensors.

  7. Rheology of unstable mineral emulsions

    OpenAIRE

    Sokolovi? Dunja S.; Še?erov-Sokolovi? Radmila M.; Sokolovi? Slobodan M.

    2013-01-01

    In this paper, the rheology of mineral oils and their unstable water emulsion were investigated. The oil samples were domestic crude oil UA, its fractions UA1, UA4 and blend semi-product UP1, while the concentration of oil in water emulsions was in the range from 1 up to 30%. The results were analyzed based on shear stress. The oil samples UA, UA1 and UP1 are Newtonian fluids, while UA4 is pseudoplastic fluid. The samples UA and UA4 show higher value of shear stress (83.75 Pa, 297 Pa), ...

  8. Integrated Solid-Electrolyte Construction

    Science.gov (United States)

    Richter, R.

    1982-01-01

    Proposed construction method for electrolytic cells would integrate porous surface electrodes into a block of solid electrolyte. Porous electrodes would facilitate unrestricted gas flow thereby improving cell performance. Electrode wire mesh is embedded at surface of solid electrolyte. Construction would assure high electrode conductance and low resistance to gas flow.

  9. Blood rheology in marine mammals

    Directory of Open Access Journals (Sweden)

    OguzBaskurt

    2010-12-01

    Full Text Available The field of blood oxygen transport and delivery to tissues has been studied by comparative physiologists for many decades. Within this general area, the particular differences in oxygen delivery between marine and terrestrial mammals has focused mainly on oxygen supply differences and delivery to the tissues under low blood flow diving conditions. Yet, the study of the inherent flow properties of the blood itself (hemorheology is rarely discussed when addressing diving. However, hemorheology is important to the study of marine mammals because of the critical nature of the oxygen stores that are carried in the blood during diving periods. This review focuses on the essential elements of hemorheology, how they are defined and on fundamental rheological applications to marine mammals. While the comparative rationale used throughout the review is much broader than the particular problems associated with diving, the basic concepts focus on how changes in the flow properties of whole blood would be critical to oxygen delivery during diving. This review introduces the reader to most of the major rheological concepts that are relevant to the unique and unusual aspects of the diving physiology of marine mammals.

  10. Electrolytic 99TcO4- reduction at inert electrodes

    International Nuclear Information System (INIS)

    Electrolytic pertechnetate reduction at inert electrodes was studied as an alternative procedure for synthesizing Tc complexes. Pertechnetate reduction was carried out in aqueous media using different aminated ligands (en, dien, trien and 1,3-dap) forming [TcO2(amine)2]+ type complexes. Simultaneously with synthesis of the desired Tc complex, TcO2 was electrodeposited onto the cathode. Conversion of TcO4- to Tc complex and TcO2 was studied as a function of several variables (kind and concentration of supporting electrolyte, ligand concentration, pH, current and electrolysis time). (author) 9 refs.; 6 figs.; 1 tab

  11. Electrolytic polymerization and physical properties of film

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Katsumi (Osaka, Univ. (Japan))

    1988-09-05

    Synthesis by the electrolytic polymerization of conductive macromolecules and the physical properties of the formed film are described. The most important factors for the electroylytic polymerization method are the kind of solution, supporting electrolyte, and the kind and concentration of the monomer. Explanation is made on polypyrole, polythiophene, polyfuran, etc. as actual examples of electrolytic polymerization of conductive macromolecules. The conductivity and electrical properties of the obtained films are greatly different depending on the methods of polymerization. The film immeidately after the polymerization is in the doping state with high conductivity, and can be considered to be metallic, but loses conductivity by a great extent with the progress of de-doping, and becomes semiconductive or non-conductive. With the progress of doping, plasma reflection is observed in highly doped areas, and the metallic feature becomes evident. This phenomenon may be used as photo- or color-switching elements. It was found that the absorption spectrum of the film undergoes a considerable change with temperature. The magnetic properties also show substantial change depending on the molecular structure and doping. 1 reference, 8 figures.

  12. Erythrocyte rheology and lipid peroxidation in burns.

    Science.gov (United States)

    Bekyarova, G; Yankova, T; Yankov, D; Kozarev, I

    1991-01-01

    Alterations in the erythrocyte rheology and the contents of activated free radical oxidation products (conjugated dienes, products of thiobarbituric acid and Schiff bases) in the acute phase of experimental thermic injury of the skin were studied. Erythrocyte flexibility reduction and erythrocyte aggregation increase correlated with elevated amounts of free radical oxidation products. Alpha-tocopherol avoided the accumulation of free radical oxidation products and improved both antioxidant defence and erythrocyte rheology. Thus we suppose that free radical oxidation products probably participate in the pathogenesis of erythrocyte rheology disturbances after thermic trauma. PMID:1859388

  13. RHEOLOGICAL BEHAVIOUR OF PSYLLIUM GUM FRACTIONS

    Directory of Open Access Journals (Sweden)

    Mohammad Hojjatoleslamyi

    2013-10-01

    Full Text Available Psyllium (Plantago psyllium is a native plant that grows widely in India, Iran and Pinjab. Studies showed psyllium gum has good rheological properties for using in wide range of food products. In this study, different fractions of psyllium gum extracted by water and alkali treatment. Rheological properties of these fractions determined by Brookfield rheometer (RV DVIII. Obtained data fitted in three temperatures 30, 60 and 80°C by Herschel-bulkly rheological model. Results showed that fractions have different behaviour during heating treatment. The most difference observed in AEG0.5 fraction.

  14. Rheologically interesting polysaccharides from yeasts

    Science.gov (United States)

    Petersen, G. R.; Nelson, G. A.; Cathey, C. A.; Fuller, G. G.

    1989-01-01

    We have examined the relationships between primary, secondary, and tertiary structures of polysaccharides exhibiting the rheological property of friction (drag) reduction in turbulent flows. We found an example of an exopolysaccharide from the yeast Cryptococcus laurentii that possessed high molecular weight but exhibited lower than expected drag reducing activity. Earlier correlations by Hoyt showing that beta 1 --> 3, beta 2 --> 4, and alpha 1 --> 3 linkages in polysaccharides favored drag reduction were expanded to include correlations to secondary structure. The effect of sidechains in a series of gellan gums was shown to be related to sidechain length and position. Disruption of secondary structure in drag reducing polysaccharides reduced drag reducing activity for some but not all exopolysaccharides. The polymer from C. laurentii was shown to be more stable than xanthan gum and other exopolysaccharides under the most vigorous of denaturing conditions. We also showed a direct relationship between extensional viscosity measurements and the drag reducing coefficient for four exopolysaccharides.

  15. Rheology of sedimenting particle pastes

    Science.gov (United States)

    Fall, Abdoulaye; de Cagny, Henri; Bonn, Daniel; Ovarlez, Guillaume; Wandersman, Elie; Dijksman, Joshua A.; van Hecke, Martin

    We study the local and global rheology of non-Brownian suspensions in a solvent that is not density-matched, leading to either creaming or sedimentation of the particles. Both local and global measurements show that the incomplete density matching leads to the appearance of a critical shear rate above which the suspension is homogenized by the flow, and below which sedimentation or creaming happens. We show that the value of the critical shear rate and its dependence on the experimental parameters are governed by a simple competition between the viscous and gravitational forces, and present a simple scaling model that agrees with the experimental results from different types of experiments (local and global) in different setups and systems.

  16. Active rheology of phospholipid vesicles

    Science.gov (United States)

    Brown, Aidan T.; Kotar, Jurij; Cicuta, Pietro

    2011-08-01

    Optical tweezers are used to manipulate the shape of artificial dioleoyl-phosphatidylcholine (DOPC) phospholipid vesicles of around 30?m diameter. Using a time-shared trapping system, a complex of traps drives oscillations of the vesicle equator, with a sinusoidal time dependence and over a range of spatial and temporal frequencies. The mechanical response of the vesicle membrane as a function of the frequency and wavelength of the driving oscillation is monitored. A simple model of the vesicles as spherical elastic membranes immersed in a Newtonian fluid, driven by a harmonic trapping potential, describes the experimental data. The bending modulus of the membrane is recovered. The method has potential for future investigation of nonthermally driven systems, where comparison of active and passive rheology can help to distinguish nonthermal forces from equilibrium fluctuations.

  17. Solid electrolyte electrochemical cell

    International Nuclear Information System (INIS)

    A new type of electrochemical cell which can be used for generating electricity or in an electrolysis mode for producing gases such as hydrogen and oxygen comprises laterally spaced apart or side-by-side catalyst layers as electrodes with the gap between the catalyst layers being bridged by a solid electrolyte which provides an ion conductive path from one catalyst layer to the other. The catalyst layers and the electrolyte are preferably in the form of thin films or layers on the surface of an inert supporting substrate. A plurality of these cells may be disposed on the substrate and interconnected electrically forming a network of series and parallel connected cells. Means are provided to feed fuel and oxidant to the electrodes either as separate gases or mixed together if appropriate catalytic materials are selected

  18. Thin film amorphous electrolytes

    International Nuclear Information System (INIS)

    This paper reports on thin film amorphous electrolytes with compositions xLi2O:ySiO2:zP2O5 deposited by single and dual source rf magnetron sputtering and their compositions determined by electron and ion beam techniques. Films containing P but no Si were composed of mainly orthophosphate and some linear chain phosphate anions, whereas single phase films containing Si and P were evidently composed of branched and possibly cyclic and extended network structures. Films with Si/P > 1 appeared to contain two or more amorphous phases. In the range of compositions investigated, the lithium ion conductivity depends mainly on the lithium ion mobility which is sensitive to the structure of the films. An open circuit voltage form 1 to 3 V measured between blocking metal contracts on the electrolyte thin films suggests that the films might be electrets

  19. Electrolyte materials - Issues and challenges

    Science.gov (United States)

    Balbuena, Perla B.

    2014-06-01

    Electrolytes are vital components of an electrochemical energy storage device. They are usually composed of a solvent or mixture of solvents and a salt or a mixture of salts which provide the appropriate environment for ionic conduction. One of the main issues associated with the selection of a proper electrolyte is that its electronic properties have to be such that allow a wide electrochemical window - defined as the voltage range in which the electrolyte is not oxidized or reduced - suitable to the battery operating voltage. In addition, electrolytes must have high ionic conductivity and negligible electronic conductivity, be chemically stable with respect to the other battery components, have low flammability, and low cost. Weak stability of the electrolyte against oxidation or reduction leads to the formation of a solid-electrolyte interphase (SEI) layer at the surface of the cathode and anode respectively. Depending on the materials of the electrolyte and those of the electrode, the SEI layer may be composed by combinations of organic and inorganic species, and it may exert a passivating role. In this paper we discuss the current status of knowledge about electrolyte materials, including non-aqueous liquids, ionic liquids, solid ceramic and polymer electrolytes. We also review the basic knowledge about the SEI layer formation, and challenges for a rational design of stable electrolytes.

  20. Electrolyte materials - Issues and challenges

    Energy Technology Data Exchange (ETDEWEB)

    Balbuena, Perla B. [Department of Chemical Engineering, and Department of Materials Science and Engineering, Texas A and M University, College Station, Texas, 77843 (United States)

    2014-06-16

    Electrolytes are vital components of an electrochemical energy storage device. They are usually composed of a solvent or mixture of solvents and a salt or a mixture of salts which provide the appropriate environment for ionic conduction. One of the main issues associated with the selection of a proper electrolyte is that its electronic properties have to be such that allow a wide electrochemical window - defined as the voltage range in which the electrolyte is not oxidized or reduced - suitable to the battery operating voltage. In addition, electrolytes must have high ionic conductivity and negligible electronic conductivity, be chemically stable with respect to the other battery components, have low flammability, and low cost. Weak stability of the electrolyte against oxidation or reduction leads to the formation of a solid-electrolyte interphase (SEI) layer at the surface of the cathode and anode respectively. Depending on the materials of the electrolyte and those of the electrode, the SEI layer may be composed by combinations of organic and inorganic species, and it may exert a passivating role. In this paper we discuss the current status of knowledge about electrolyte materials, including non-aqueous liquids, ionic liquids, solid ceramic and polymer electrolytes. We also review the basic knowledge about the SEI layer formation, and challenges for a rational design of stable electrolytes.

  1. Electrolyte materials - Issues and challenges

    International Nuclear Information System (INIS)

    Electrolytes are vital components of an electrochemical energy storage device. They are usually composed of a solvent or mixture of solvents and a salt or a mixture of salts which provide the appropriate environment for ionic conduction. One of the main issues associated with the selection of a proper electrolyte is that its electronic properties have to be such that allow a wide electrochemical window - defined as the voltage range in which the electrolyte is not oxidized or reduced - suitable to the battery operating voltage. In addition, electrolytes must have high ionic conductivity and negligible electronic conductivity, be chemically stable with respect to the other battery components, have low flammability, and low cost. Weak stability of the electrolyte against oxidation or reduction leads to the formation of a solid-electrolyte interphase (SEI) layer at the surface of the cathode and anode respectively. Depending on the materials of the electrolyte and those of the electrode, the SEI layer may be composed by combinations of organic and inorganic species, and it may exert a passivating role. In this paper we discuss the current status of knowledge about electrolyte materials, including non-aqueous liquids, ionic liquids, solid ceramic and polymer electrolytes. We also review the basic knowledge about the SEI layer formation, and challenges for a rational design of stable electrolytes

  2. Wetting in electrolyte solutions

    OpenAIRE

    Ibagon, Ingrid; Bier, Markus; Dietrich, S.

    2013-01-01

    Wetting of a charged substrate by an electrolyte solution is investigated by means of classical density functional theory applied to a lattice model. Within the present model the pure, i.e., salt-free solvent, for which all interactions are of the nearest-neighbor type only, exhibits a second-order wetting transition for all strengths of the substrate-particle and the particle-particle interactions for which the wetting transition temperature is nonzero. The influences of th...

  3. Thin film composite electrolyte

    Science.gov (United States)

    Schucker, Robert C. (The Woodlands, TX)

    2007-08-14

    The invention is a thin film composite solid (and a means for making such) suitable for use as an electrolyte, having a first layer of a dense, non-porous conductive material; a second layer of a porous ionic conductive material; and a third layer of a dense non-porous conductive material, wherein the second layer has a Coefficient of thermal expansion within 5% of the coefficient of thermal expansion of the first and third layers.

  4. Ice electrode electrolytic cell

    Science.gov (United States)

    Glenn, D.F.; Suciu, D.F.; Harris, T.L.; Ingram, J.C.

    1993-04-06

    This invention relates to a method and apparatus for removing heavy metals from waste water, soils, or process streams by electrolytic cell means. The method includes cooling a cell cathode to form an ice layer over the cathode and then applying an electric current to deposit a layer of the heavy metal over the ice. The metal is then easily removed after melting the ice. In a second embodiment, the same ice-covered electrode can be employed to form powdered metals.

  5. Solid polymer electrolytes

    Science.gov (United States)

    Abraham, Kuzhikalail M. (Needham, MA); Alamgir, Mohamed (Dedham, MA); Choe, Hyoun S. (Waltham, MA)

    1995-01-01

    This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.

  6. Lithium ion conducting electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Angell, C.A.; Liu, C.

    1996-04-09

    A liquid, predominantly lithium-conducting, ionic electrolyte is described having exceptionally high conductivity at temperatures of 100 C or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH{sub 3}CN), succinnonitrile (CH{sub 2}CN){sub 2}, and tetraglyme (CH{sub 3}--O--CH{sub 2}--CH{sub 2}--O--){sub 2} (or like solvents) solvated to a Mg{sup +2} cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100 C conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone. 2 figs.

  7. Lithium ion conducting electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Angell, C. Austen (Tempe, AZ); Liu, Changle (Tempe, AZ)

    1996-01-01

    A liquid, predominantly lithium-conducting, ionic electrolyte having exceptionally high conductivity at temperatures of 100.degree. C. or lower, including room temperature, and comprising the lithium salts selected from the group consisting of the thiocyanate, iodide, bromide, chloride, perchlorate, acetate, tetrafluoroborate, perfluoromethane sulfonate, perfluoromethane sulfonamide, tetrahaloaluminate, and heptahaloaluminate salts of lithium, with or without a magnesium-salt selected from the group consisting of the perchlorate and acetate salts of magnesium. Certain of the latter embodiments may also contain molecular additives from the group of acetonitrile (CH.sub.3 CN) succinnonitrile (CH.sub.2 CN).sub.2, and tetraglyme (CH.sub.3 --O--CH.sub.2 --CH.sub.2 --O--).sub.2 (or like solvents) solvated to a Mg.sup.+2 cation to lower the freezing point of the electrolyte below room temperature. Other particularly useful embodiments contain up to about 40, but preferably not more than about 25, mol percent of a long chain polyether polymer dissolved in the lithium salts to provide an elastic or rubbery solid electrolyte of high ambient temperature conductivity and exceptional 100.degree. C. conductivity. Another embodiment contains up to about but not more than 10 mol percent of a molecular solvent such as acetone.

  8. Rheological and textural properties of cosmetic emulsions.

    Czech Academy of Sciences Publication Activity Database

    Morávková, Tereza; Štern, Petr

    2011-01-01

    Ro?. 21, ?. 3 (2011), s. 35200. ISSN 1430-6395 Institutional research plan: CEZ:AV0Z20600510 Keywords : cosmetic emulsions * rheology * texture * sensory analysis * psychorheology Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2011

  9. Ultrasonic irradiation to modify the PEO/P(VDF-HFP)/TiO2 nanoparticle composite polymer electrolyte for dye sensitized solar cells

    International Nuclear Information System (INIS)

    As a novel technology, ultrasonic irradiation was applied to modify the PEO/P(VDF-HFP)/TiO2 nanoparticle composite polymer electrolyte for dye sensitized solar cells (DSSCs). The ultrasonic irradiation effectively changes the rheology and the glass transition temperature and the crystallinity of the composite polymer. The experiments showed that 20 min moderate ultrasonic irradiation resulted in better penetration of the polymer electrolyte into the TiO2 nanoporous photo-anode, and the ionic conductivity was improved to 0.956 ms cm-1 compared with 0.386 ms cm-1 of the original polymer electrolyte. The DSSC fabricated with 20 min ultrasonic irradiation modified polymer electrolyte exhibited an improved solar energy conversion efficiency of 4.39% compared with the 3.6% of the unmodified polymer electrolyte DSSC at 30.2 mW cm-2 light intensity

  10. Possibilities of applying rheological measurements in metallurgy

    OpenAIRE

    Korolczuk-hejnak, M.

    2012-01-01

    Purpose: The purpose of this paper is to analyse from the literature point of view the issues concerning modern methods of measuring the viscosity of liquid steel and solid-liquid steel in the course of rheological research with the use of a high temperature rheometer. The paper reviews the subject of measuring and modelling the viscosity value of steel with the use of equations and data available in the literature. It also presents the difficulties connected to rheological measurements of li...

  11. PVC paste rheology: Study of process dependencies

    OpenAIRE

    Rasteiro, M. G.; Toma?s, A.; Ferreira, L.; Figueiredo, S.

    2009-01-01

    A plastisol is a dispersion (suspension) of fine particles of poly(vinyl chloride) with a plasticizer that is normally applied over a substrate, by spreading or coating, before the gelification and fusion into the final product. Because of the first step, the plastisol rheology study is a very important factor which has to be taken into consideration to determine and fine tune the process conditions. This work is concerned with the study of the rheology of plastisols from selected PVC samp...

  12. Rheology of compatibilized immiscible viscoelastic polymer blends

    OpenAIRE

    Iza, Mustapha; Bousmina, Mosto; Je?ro?me, Robert

    2001-01-01

    Rheological behavior of a PS/PE model viscoelastic immiscible blend compatibilized by two types of inter facial modifiers was investigated. Dynamic, steady shear, and transient experiments were performed to probe the effect of the interfacial modification on the rheological behavior of the blend. While the effect was relatively small in dynamic and steady shear experiments, significant signature of the presence of the copolymer was observed in transient experiments after start up of shear flo...

  13. Rheological properties of concentrated alumina slurries: influence of ph and dispersant agent

    International Nuclear Information System (INIS)

    The relationship between the ph, the electrolyte concentrations and the rheological properties of high concentrated alumina slurries in aqueous medium is of great importance because it is considered to be the key to control the stability of the slurries from flocculation. Zeta potential of alumina slurries with and without Duramax C (dispersant agent) as a function of ph was studied. Two ph around the zero point of charge of alumina slurries were selected for the investigation of rheological properties. The rheological properties of aqueous alumina slurries with respect to different parameters, e.g.: viscosity, elastic modulus (storage modulus G) and viscous modulus (loss modulus G), were investigated. Viscosity measurements of the slurries as a function of Duramax C content at both ph 8.4 and 9.4) were used to determine the state of slurries. Three states of slurries, termed flocculated, partially de flocculated and fully de flocculated, were selected for further investigation. The viscosity of the three slurries at both ph as a function of shear rate was determined. Fully de flocculated slurry shows Newtonian behavior at all shear rates at both tested ph compared by the partial de flocculated and flocculated system. Results of investigation of G and G at ph of 9.4 as a function of applied stress explored the critical stress

  14. Polymer-ceramic composite electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, B. (University of Dayton Research Inst., Dayton, OH (United States) Aero Propulsion and Power Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States)); Scanlon, L.G. (University of Dayton Research Inst., Dayton, OH (United States) Aero Propulsion and Power Directorate, Wright Laboratory, Wright-Patterson Air Force Base, OH (United States))

    1994-12-01

    This paper reviews the state-of-the-art of polymer-ceramic composite electrolytes in view of three main issues, i.e., conductivity, transport number, and electrode-electrolyte interfacial reactions. These issues are believed to be critical to the development and commercialization of solid polymer batteries. The ceramic phase in limited amounts augments conductivity, enhances the cationic transport number, and suppresses electrode-electrolyte interfacial reactions. Scientific explanation for these effects is also discussed. (orig.)

  15. Ceramic electrolyte coating and methods

    Science.gov (United States)

    Seabaugh, Matthew M. (Columbus, OH); Swartz, Scott L. (Columbus, OH); Dawson, William J. (Dublin, OH); McCormick, Buddy E. (Dublin, OH)

    2007-08-28

    Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  16. Magma rheology variation in sheet intrusions (Invited)

    Science.gov (United States)

    Magee, C.; O'Driscoll, B.; Petronis, M. S.; Stevenson, C.

    2013-12-01

    The rheology of magma fundamentally controls igneous intrusion style as well as the explosivity and type of volcanic eruptions. Importantly, the dynamic interplay between the viscosity of magma and other processes active during intrusion (e.g., crystallisation, magma mixing, assimilation of crystal mushes and/or xenolith entrainment) will likely bear an influence on the temporal variation of magma rheology. Constraining the timing of rheological changes during magma transit therefore plays an important role in understanding the nuances of volcanic systems. However, the rheological evolution of actively emplacing igneous intrusions cannot be directly studied. While significant advances have been made via experimental modelling and analysis of lava flows, how these findings relate to intruding magma remains unclear. This has led to an increasing number of studies that analyse various characteristics of fully crystallised intrusions in an attempt to ';back-out' the rheological conditions governing emplacement. For example, it has long been known that crystallinity affects the rheology and, consequently, the velocity of intruding magma. This means that quantitative textural analysis of crystal populations (e.g., crystal size distribution; CSD) used to elucidate crystallinity at different stages of emplacement can provide insights into magma rheology. Similarly, methods that measure flow-related fabrics (e.g., anisotropy of magnetic susceptibility; AMS) can be used to discern velocity profiles, a potential proxy for the magma rheology. To illustrate these ideas, we present an integrated AMS and petrological study of several sheet intrusions located within the Ardnamurchan Central Complex, NW Scotland. We focus on the entrainment and transport dynamics of gabbroic inclusions that were infiltrated by the host magma upon entrainment. Importantly, groundmass magnetic fabrics within and external to these inclusions are coaxial. This implies that a deviatoric stress was transmitted into the inclusions during magma flow. We suggest that this represents a modification of the magma dynamics from Newtonian-like to Bingham-like behaviour. Furthermore, the spatial restriction of inclusions within the sheet intrusions suggest that subtle variations in magma rheology may partition apparently continuous intrusions, perhaps affecting lateral mixing and the longevity of discrete sheet segments. Detailed fabric analysis of other inclusion-free intrusions in the Ardnamurchan Central Complex supports this interpretation. Our results highlight that the crystalline cargo of a magma can result in temporal and spatial variations in magma rheology. This can partition coalesced magma bodies into ';zones' characterised by different magma properties, potentially affecting the location of magma flow pathways or even eruption sites.

  17. Multivariant simulator for vacuum cooling processes of three component electrolyte systems

    OpenAIRE

    Suljkanovi? Midhat; Jotanovi? Milovan; Ahmetovi? Elvis; Ibri? Nidret

    2010-01-01

    In this paper, a computer aided analysis and synthesis of the crystallization processes from multicomponent electrolyte systems were studied. In addition, the vacuum crystallization processes with adiabatic cooling of the system are presented. The cooling process of a multicomponent electrolyte system can be considered as a process with the concentration of the system and/or the crystallization of the solid phase from the system. Requirements for multivariant options of the process simulator ...

  18. Solid-state graft copolymer electrolytes for lithium battery applications.

    Science.gov (United States)

    Hu, Qichao; Caputo, Antonio; Sadoway, Donald R

    2013-01-01

    Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (lithium ion batteries are not applicable to high temperature automotive applications. A safer alternative to organic electrolytes is solid polymer electrolytes. This work will highlight the synthesis for a graft copolymer electrolyte (GCE) poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). The conduction mechanism has been discussed and it has been demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence. Batteries containing commercially available LP30 organic (LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) at a 1:1 ratio) and GCE were cycled at ambient temperature. It was found that at ambient temperature, the batteries containing GCE showed a greater overpotential when compared to LP30 electrolyte. However at temperatures greater than 60 °C, the GCE cell exhibited much lower overpotential due to fast polymer electrolyte conductivity and nearly the full theoretical specific capacity of 170 mAh/g was accessed. PMID:23963203

  19. Norbornene-Based Polymer Electrolytes for Lithium Cells

    Science.gov (United States)

    Cheung, Iris; Smart, Marshall; Prakash, Surya; Miyazawa, Akira; Hu, Jinbo

    2007-01-01

    Norbornene-based polymers have shown promise as solid electrolytes for lithium-based rechargeable electrochemical cells. These polymers are characterized as single-ion conductors. Single-ion-conducting polymers that can be used in lithium cells have long been sought. Single-ion conductors are preferred to multiple-ion conductors as solid electrolytes because concentration gradients associated with multiple-ion conduction lead to concentration polarization. By minimizing concentration polarization, one can enhance charge and discharge rates. Norbornene sulfonic acid esters have been synthesized by a ring-opening metathesis polymerization technique, using ruthenium-based catalysts. The resulting polymer structures (see figure) include sulfonate ionomers attached to the backbones of the polymer molecules. These molecules are single-ion conductors in that they conduct mobile Li+ ions only; the SO3 anions in these polymers, being tethered to the backbones, do not contribute to ionic conduction. This molecular system is especially attractive in that it is highly amenable to modification through functionalization of the backbone or copolymerization with various monomers. Polymers of this type have been blended with poly(ethylene oxide) to lend mechanical integrity to free-standing films, and the films have been fabricated into solid polymer electrolytes. These electrolytes have been demonstrated to exhibit conductivity of 2 10(exp -5)S/cm (which is high, relative to the conductivities of other solid electrolytes) at ambient temperature, plus acceptably high stability. This type of norbornene-based polymeric solid electrolyte is in the early stages of development. Inasmuch as the method of synthesis of these polymers is inherently flexible and techniques for the fabrication of the polymers into solid electrolytes are amenable to optimization, there is reason to anticipate further improvements.

  20. Thin film polymeric gel electrolytes

    Science.gov (United States)

    Derzon, Dora K. (1554 Rosalba St. NE., Albuquerque, Bernalillo County, NM 87112); Arnold, Jr., Charles (3436 Tahoe, NE., Albuquerque, Bernalillo County, NM 87111); Delnick, Frank M. (9700 Fleming Rd., Dexter, MI 48130)

    1996-01-01

    Novel hybrid thin film electrolyte, based on an organonitrile solvent system, which are compositionally stable, environmentally safe, can be produced efficiently in large quantity and which, because of their high conductivities .apprxeq.10.sup.-3 .OMEGA..sup.-1 cm.sup.-1 are useful as electrolytes for rechargeable lithium batteries.

  1. Application of Organic Solid Electrolytes

    Science.gov (United States)

    Sekido, S.

    1982-01-01

    If ions are considered to be solid material which transport electric charges, polymer materials can then be considered as organic solid electrolytes. The role of these electrolytes is discussed for (1) ion concentration sensors; (2) batteries using lithium as the cathode and a charge complex of organic material and iodine in the anode; and (3) elements applying electrical double layer capability.

  2. Physics of Electrolytic Gas Evolution

    CERN Document Server

    Sequeira, Cesar A C; Sljukic, Biljana; Amaral, Luis

    2013-01-01

    A brief analysis of the physics and effects of electrolytic gas evolution is presented. Aspects considered include bubble nucleation, growth, and detachment, enhancement of mass and heat transfer, and decrease of apparent electrical conductivity of bubble containing electrolytes. This analysis is mainly oriented to hydrogen/oxygen evolving electrodes.

  3. Electrolytes - Technology review

    Energy Technology Data Exchange (ETDEWEB)

    Meutzner, Falk; Ureña de Vivanco, Mateo [Institut für Experimentelle Physik, Technische Universität Bergakademie Freiberg, Leipziger Straße 23, 09596 Freiberg (Germany)

    2014-06-16

    Safety, lifetime, energy density, and costs are the key factors for battery development. This generates the need for improved cell chemistries and new, advanced battery materials. The components of an electrolyte are the solvent, in which a conducting salt and additives are dissolved. Each of them plays a specific role in the overall mechanism of a cell: the solvent provides the host medium for ionic conductivity, which originates in the conductive salt. Furthermore, additives can be used to optimize safety, performance, and cyclability. By understanding the tasks of the individual components and their optimum conditions of operation, the functionality of cells can be improved from a holistic point of view. This paper will present the most important technological features and requirements for electrolytes in lithium-ion batteries. The state-of-the-art chemistry of each component is presented, as well as different approaches for their modification. Finally, a comparison of Li-cells with lithium-based technologies currently under development is conducted.

  4. Electrolytes - Technology review

    International Nuclear Information System (INIS)

    Safety, lifetime, energy density, and costs are the key factors for battery development. This generates the need for improved cell chemistries and new, advanced battery materials. The components of an electrolyte are the solvent, in which a conducting salt and additives are dissolved. Each of them plays a specific role in the overall mechanism of a cell: the solvent provides the host medium for ionic conductivity, which originates in the conductive salt. Furthermore, additives can be used to optimize safety, performance, and cyclability. By understanding the tasks of the individual components and their optimum conditions of operation, the functionality of cells can be improved from a holistic point of view. This paper will present the most important technological features and requirements for electrolytes in lithium-ion batteries. The state-of-the-art chemistry of each component is presented, as well as different approaches for their modification. Finally, a comparison of Li-cells with lithium-based technologies currently under development is conducted

  5. Electrolytes - Technology review

    Science.gov (United States)

    Meutzner, Falk; de Vivanco, Mateo Ureña

    2014-06-01

    Safety, lifetime, energy density, and costs are the key factors for battery development. This generates the need for improved cell chemistries and new, advanced battery materials. The components of an electrolyte are the solvent, in which a conducting salt and additives are dissolved. Each of them plays a specific role in the overall mechanism of a cell: the solvent provides the host medium for ionic conductivity, which originates in the conductive salt. Furthermore, additives can be used to optimize safety, performance, and cyclability. By understanding the tasks of the individual components and their optimum conditions of operation, the functionality of cells can be improved from a holistic point of view. This paper will present the most important technological features and requirements for electrolytes in lithium-ion batteries. The state-of-the-art chemistry of each component is presented, as well as different approaches for their modification. Finally, a comparison of Li-cells with lithium-based technologies currently under development is conducted.

  6. Rheological porperties of simulated vitrification feeds

    International Nuclear Information System (INIS)

    Radioactive waste will be immobilized in borosilicate glass at the Savannah River Site inside a remotely operated vitrification facility. In-process, on-line rheological measurements are preferred in a plant operating environment. Experiments were conducted to determine the rheological properties of a vitrification feed simulant to ensure compatibility with process equipment and determine the best data system for slurry characterization. Rheological feed properties were measured using a concentric cylinder rheometer and compared to theoretical models. Above shear rates of 200 sec-1, the appearance of the flow curves indicated inertial forces were significant and the analysis was hindered by variable gap sizes caused by particle deposition on the outer cylinder surface. Samples with varying weight percents of insoluble solids were analyzed to determine the variation in rheological properties with solids concentration. The consistency was found to be temperature dependent, but the yield stress was found to be relatively insensitive to temperatures between 25 and 50 C. These correlations were used to guide the operation of the dewatering process. The target solids concentration of the feed was set at 41 wt% insoluble solids to raise the yield stress of the slurry to about 100 dynes/cm2. This alleviated foaming of the material caused by entrainment of air within the processing equipment and the slurry was successfully vitrified. A combination of conccessfully vitrified. A combination of concentric cylinder rheometers and tube rheometers provides the best data system for characterizing the rheology of a vitrification slurry

  7. Unified Solid-Viscous Mantle Rheology

    Science.gov (United States)

    Morozov, I. B.

    2011-12-01

    Despite their general similarities, the existing models for seismic, tidal, and geodynamic anelasticity of the Earth are difficult to compare quantitatively. The principal problem is that the viscoelastic quality factor Q, which is typically used for describing the near-elastic energy dissipation, is often incompatible with mechanics. To resolve this inconsistency, we present a new formulation of anelasticity based entirely on analytical mechanics. The Jeffreys-Ricker model of "solid friction" is recast in Lagrangian form in terms of viscosities, and extended to non-Newtonian rheologies. A unified model of the Earth's anelasticity is thus created by using a dissipation function, D, which is dependent on both strains and strain rates. This function gives a common rheological law describing the behavior of Earth's materials under seismic, tidal, quasi-static laboratory (creep), and geodynamic conditions. Function D is both strain and strain-rate dependent, and its dependence on strain rate is close to the power-law rheological relation commonly used in geodynamics. The dependence on strain varies from power-law in the elastic limit to constant in the plastic-flow limit. For the mantle, the characteristic value of the proposed "rheological viscosity" is estimated as 2.109 Pa.s, and the two power-law exponents are ?0 = 0.47 (for weak strain) and ?1 = 0.6 (for strain rate). With such a common rheological law and rigorous mechanical formulation, a unified picture of physical processes within the Earth becomes possible at all scales.

  8. Initial rheological description of high performance concretes

    Directory of Open Access Journals (Sweden)

    Alessandra Lorenzetti de Castro

    2006-12-01

    Full Text Available Concrete is defined as a composite material and, in rheological terms, it can be understood as a concentrated suspension of solid particles (aggregates in a viscous liquid (cement paste. On a macroscopic scale, concrete flows as a liquid. It is known that the rheological behavior of the concrete is close to that of a Bingham fluid and two rheological parameters regarding its description are needed: yield stress and plastic viscosity. The aim of this paper is to present the initial rheological description of high performance concretes using the modified slump test. According to the results, an increase of yield stress was observed over time, while a slight variation in plastic viscosity was noticed. The incorporation of silica fume showed changes in the rheological properties of fresh concrete. The behavior of these materials also varied with the mixing procedure employed in their production. The addition of superplasticizer meant that there was a large reduction in the mixture's yield stress, while plastic viscosity remained practically constant.

  9. Initial rheological description of high performance concretes

    Scientific Electronic Library Online (English)

    Alessandra Lorenzetti de, Castro; Jefferson Benedicto Libardi, Liborio.

    2006-12-01

    Full Text Available Concrete is defined as a composite material and, in rheological terms, it can be understood as a concentrated suspension of solid particles (aggregates) in a viscous liquid (cement paste). On a macroscopic scale, concrete flows as a liquid. It is known that the rheological behavior of the concrete i [...] s close to that of a Bingham fluid and two rheological parameters regarding its description are needed: yield stress and plastic viscosity. The aim of this paper is to present the initial rheological description of high performance concretes using the modified slump test. According to the results, an increase of yield stress was observed over time, while a slight variation in plastic viscosity was noticed. The incorporation of silica fume showed changes in the rheological properties of fresh concrete. The behavior of these materials also varied with the mixing procedure employed in their production. The addition of superplasticizer meant that there was a large reduction in the mixture's yield stress, while plastic viscosity remained practically constant.

  10. Electrolyte treatment for aluminum reduction

    Science.gov (United States)

    Brown, Craig W. (Seattle, WA); Brooks, Richard J. (Seattle, WA); Frizzle, Patrick B. (Seattle, WA); Juric, Drago D. (Bulleen, AU)

    2002-01-01

    A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF.sub.3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

  11. Electrochemical investigations of polymer films and monolayers on electrode surfaces: Determination of the reaction entropy for Os(bpy)[sub 3][sup 3+/2+] in nafion, and the influence of supporting electrolyte activity on the formal potential of a monolayer containing a ruthenium redox center, and, Synthesis and characterization of monometallic and bimetallic complexes of ruthenium(II) and iron(II) with 4,4[prime]bipyrimidine (4,4[prime]BPM) and pyridyl viologen (PV[sup 2+])

    Energy Technology Data Exchange (ETDEWEB)

    Tunison, H.M.

    1992-01-01

    This thesis is comprised of two major projects: An analytical project and an inorganic synthesis project. The first project dealt with the investigation of the electrochemistry of thin polymer films and monolayers on electrode surfaces. The second project dealt with the synthesis of novel monometallic and bimetallic complexes of ruthenium and iron in which the metals were bridged by either 4, 4[prime] bipyrimidine or pyridyl viologen. The first project involved the investigation of the reaction entropy for a redox couple which had been exchanged into an ion-exchange polymer on an electrode surface. The measured values for the reaction entropy were shown to be dominated by the entropy change for partitioning the redox couple into the film and by supporting electrolyte cation transfer between the film and the polymer. Electrochemical studies were also carried out on an alkanethiol monolayer which contained a ruthenium redox center at the monolayer/solution interface. The electrochemistry supported the fact that the monolayer was displaying permselective behavior with the exclusion of supporting electrolyte cations from the monolayer. Equations were presented that described the electrochemical nature of the monolayer and the dependence of the formal potential for the monolayer on the supporting electrolyte cation transfer at the monolayer/solution interface. The second section of the thesis dealt with the synthesis and characterization of a number of novel ruthenium and iron complexes utilizing 4,4[prime] bipyrimidine and pyridyl viologen. The complexes show shifts in the energy of the MLCT bands and reduction potentials which can be correlated to either the reduction potential of the ligand involved in the complex or the relationship between iron and ruthenium in the group VIII family. Comparisons are made between the complexes studied and a number of ruthenium and iron complexes of nitrogen heterocycles from the literature.

  12. Rheological properties of alumina injection feedstocks

    Scientific Electronic Library Online (English)

    Vivian Alexandra, Krauss; Eduardo Nunes, Pires; Aloísio Nelmo, Klein; Márcio Celso, Fredel.

    2005-06-01

    Full Text Available The rheological behavior of alumina molding feedstocks containing polyethylene glycol (PEG), polyvinylbutyral (PVB) and stearic acid (SA) and having different powder loads were analyzed using a capillary rheometer. Some of the feedstocks showed a pseudoplastic behavior of n [...] e appearance of weld lines on molded parts. Their viscosity also displayed a strong dependence on the shear rate. The slip phenomenon, which can cause an unsteady front flow, was also observed. The results indicate that the feedstock containing a lower powder load displayed the best rheological behavior. The 55 vol. % powder loaded feedstock presented the best rheological behavior, thus appearing to be more suitable than the formulation containing a vol. 59% powder load, which attained viscosities exceeding 10³ Pa.s at low shear rates, indicating its unsuitability for injection molding.

  13. Rheological Characterization of Unusual DWPF Slurry Samples

    International Nuclear Information System (INIS)

    A study was undertaken to identify and clarify examples of unusual rheological behavior in Defense Waste Processing Facility (DWPF) simulant slurry samples. Identification was accomplished by reviewing sludge, Sludge Receipt and Adjustment Tank (SRAT) product, and Slurry Mix Evaporator (SME) product simulant rheological results from the prior year. Clarification of unusual rheological behavior was achieved by developing and implementing new measurement techniques. Development of these new methods is covered in a separate report, WSRC-TR-2004-00334. This report includes a review of recent literature on unusual rheological behavior, followed by a summary of the rheological measurement results obtained on a set of unusual simulant samples. Shifts in rheological behavior of slurries as the wt. % total solids changed have been observed in numerous systems. The main finding of the experimental work was that the various unusual DWPF simulant slurry samples exhibit some degree of time dependent behavior. When a given shear rate is applied to a sample, the apparent viscosity of the slurry changes with time rather than remaining constant. These unusual simulant samples are more rheologically complex than Newtonian liquids or more simple slurries, neither of which shows significant time dependence. The study concludes that the unusual rheological behavior that has been observed is being caused by time dependent rheological properties in the slurries being measured. Most of the cthe slurries being measured. Most of the changes are due to the effect of time under shear, but SB3 SME products were also changing properties while stored in sample bottles. The most likely source of this shear-related time dependence for sludge is in the simulant preparation. More than a single source of time dependence was inferred for the simulant SME product slurries based on the range of phenomena observed. Rheological property changes were observed on the time-scale of a single measurement (minutes) as well as on a time scale of hours to weeks. The unusual shape of the slurry flow curves was not an artifact of the rheometric measurement. Adjusting the user-specified parameters in the rheometer measurement jobs can alter the shape of the flow curve of these time dependent samples, but this was not causing the unusual behavior. Variations in the measurement parameters caused the time dependence of a given slurry to manifest at different rates. The premise of the controlled shear rate flow curve measurement is that the dynamic response of the sample to a change in shear rate is nearly instantaneous. When this is the case, the data can be fitted to a time independent rheological equation, such as the Bingham plastic model. In those cases where this does not happen, interpretation of the data is difficult. Fitting time dependent data to time independent rheological equations, such as the Bingham plastic model, is also not appropriate

  14. Charge relaxation dynamics of an electrolytic nanocapacitor

    CERN Document Server

    Thakore, Vaibhav

    2013-01-01

    Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology based electrochemical energy storage, electrochemomechanical energy conversion and bioelectrochemical sensing devices besides controlled synthesis of nanostructured materials. Here, using Lattice Boltzmann (LB) method, we present results from the simulations of an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL overlap, solvent viscosities, ratios of cation to anion diffusivity and electrode separations. A continuously varying molecular speed dependent relaxation time, proposed for use with the LB equation, recovers the correct microscopic description of molecular collision phenomena and holds promise for enhancing the stability of the LB algorithm. Results for large EDL overlap showed oscillatory behavior for ionic current densities in contrast to monotonic relaxation to equilibrium for low EDL overlap. Further, at low solv...

  15. Effects of Astaxanthin on Human Blood Rheology

    OpenAIRE

    Miyawaki, Hiromi; Takahashi, Jiro; Tsukahara, Hiroki; Takehara, Isao

    2008-01-01

    Effects of astaxanthin (AX) derived from H. pluvialis on human blood rheology were investigated in 20 adult men with a single-blind method. The experimental group was 57.5 ± 9.8 years of age and the placebo group was 50.8 ± 13.1 years of age. A blood rheology test that measures whole blood transit time was conducted using heparinized blood of the volunteers by a MC-FAN apparatus (microchannel array flow analyzer). After administration of AX 6 mg/day for 10 days, the values of the expe...

  16. Rheological study of chitosan in solution

    International Nuclear Information System (INIS)

    Chitosan is an abundant biopolymer with remarkable physicochemical and biological properties, usually employed in a wide range of applications. It acts as a cationic polyelectrolyte in aqueous acid solutions, leading to unique characteristics. In this work, chitosan was characterized by 1H NMR and its rheological behavior were studied as function of chitosan sample, shear rate, polymer concentration, ionic strength, time and temperature. In order to calculate rheological parameters and to understand the macromolecular dynamic in solution, the Otswald-de Waele model was fitted. (author)

  17. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    Bjerrum, Niels Technical University of Denmark,

    A method for preparing polybenzimidazole or polybenzimidazole blend membranes and fabricating gas diffusion electrodes and membrane-electrode assemblies is provided for a high temperature polymer electrolyte membrane fuel cell. Blend polymer electrolyte membranes based on PBI and various thermoplastic polymers for high temperature polymer electrolyte fuel cells have also been developed. Miscible blends are used for solution casting of polymer membranes (solid electrolytes). High conductivity and enhanced mechanical strength were obtained for the blend polymer solid electrolytes. With the thermally resistant polymer, e.g., polybenzimidazole or a mixture of polybenzimidazole and other thermoplastics as binder, the carbon-supported noble metal catalyst is tape-cast onto a hydrophobic supporting substrate. When doped with an acid mixture, electrodes are assembled with an acid doped solid electrolyte membrane by hot-press. The fuel cell can operate at temperatures up to at least 200 °C with hydrogen-rich fuel containing high ratios of carbon monoxide such as 3 vol% carbon monoxide or more, compared to the carbon monoxide tolerance of 10-20 ppm level for Nafion$m(3)-based polymer electrolyte fuel cells.

  18. Plasma spray synthesis of La{sub 10}(SiO{sub 4}){sub 6}O{sub 3} as a new electrolyte for intermediate temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Wei [LERMPS, University of Technology of Belfort-Montbeliard, Belfort 90010 (France); National Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Liao, Han-Lin; Coddet, Christian [LERMPS, University of Technology of Belfort-Montbeliard, Belfort 90010 (France)

    2008-05-01

    The apatite-type lanthanum silicate films were successfully synthesized by modified atmosphere plasma spraying using lanthanum oxide and silicon oxide mixed powders and precalcined hypereutectic powders in the size range 1-3 {mu}m and 5-8 {mu}m, respectively, as starting feedstock materials. The films differed not only in microstructural scale, but also in the characteristic of the degree of film densification. A detail describing the evolution of microstructure has been discussed. A considerable improvement in densification of the La{sub 10}(SiO{sub 4}){sub 6}O{sub 3} electrolyte films has been observed. (author)

  19. Antireduction Insulator For Solid-Electrolyte Cell

    Science.gov (United States)

    Shlichta, Paul J.

    1990-01-01

    Depletion of oxygen from electrolyte prevented. Proposed to add layer of electrical insulation between solid electrolyte and portion of porous negative electrode under negative metal contact in solid-electrolyte cell. Helps maintain efficiency of cell by preventing "shadow" effect degrading portion of electrolyte under negative contact and sometimes near seals.

  20. Composite Solid Electrolyte For Lithium Cells

    Science.gov (United States)

    Peled, Emmanuel; Nagasubramanian, Ganesan; Halpert, Gerald; Attia, Alan I.

    1994-01-01

    Composite solid electrolyte material consists of very small particles, each coated with thin layer of Lil, bonded together with polymer electrolyte or other organic binder. Material offers significant advantages over other solid electrolytes in lithium cells and batteries. Features include high ionic conductivity and strength. Composite solid electrolyte expected to exhibit flexibility of polymeric electrolytes. Polymer in composite solid electrolyte serves two purposes: used as binder alone, conduction taking place only in AI2O3 particles coated with solid Lil; or used as both binder and polymeric electrolyte, providing ionic conductivity between solid particles that it binds together.

  1. Polypropylene/Mg3Al-tartrazine LDH nanocomposites with enhanced thermal stability, UV absorption, and rheological properties

    OpenAIRE

    Wang, Q.; Wu, J.; Gao, Y.; Zhang, Z.; Wang, J.; Zhang, X.; Yan, X.; Umar, A.; Guo, Z.; O Hare, D.

    2013-01-01

    We report the synthesis of coloured polypropylene (PP)/Mg 3Al-tartrazine layered double hydroxide (LDH) nanocomposites with enhanced thermal stability, UV absorption capacity, and rheological properties using a modified solvent mixing method for the first time. SEM images indicated that the LDH nanoparticles were evenly dispersed within the PP matrix due to the favourable interactions between PP and LDHs. TGA and DSC analysis indicated that the thermal stability of PP/LDH nanocomposites was s...

  2. Effects of electrolyte concentration and counterion valence on the microstructural flow regimes in dilute cetyltrimethylammonium tosylate micellar solutions.

    Science.gov (United States)

    Tepale, N; Macías, E R; Bautista, F; Puig, J E; Manero, O; Gradzielski, M; Escalante, J I

    2011-11-15

    The shear thickening behavior and the transition to shear thinning are examined in dilute cetyltrimethylammonium tosylate (CTAT) micellar solutions as a function of surfactant concentration and ionic strength using electrolytes with different counterion valence. Newtonian behavior at low shear rates, followed by shear thickening and shear thinning at higher shear rates, are observed at low and intermediate surfactant and electrolyte concentrations. Shear thickening diminishes with increasing surfactant concentration and ionic strength. At higher surfactant or electrolyte concentration, only a Newtonian region followed by shear thinning is detected. A generalized flow diagram indicates two controlling regimes: one in which electrostatic screening dominates and induces micellar growth, and another, at higher electrolyte and surfactant concentrations, where chemical equilibrium among electrolyte and surfactant counterions controls the rheological behavior by modifying micellar breaking and reforming. Analysis of the shear thickening behavior reveals that not only a critical shear rate is required for shear thickening, but also a critical deformation, which appears to be unique for all systems examined, within experimental error. Moreover, a superposition of the critical shear rate for shear thickening with surfactant and electrolyte concentration is reported. PMID:21868025

  3. Doping electrolyte by charged nanoparticles

    Science.gov (United States)

    Shao, Linbo; Zheng, Mingxin; Wang, Wei

    2015-03-01

    Ions in electrolytes have been proposed to resemble carriers in solid semiconductors over decades. Recently, nanofluidic devices have been demonstrated to phenomenologically mimic semiconductor devices by modulating ion concentrations near the interface of electrolytes and solids. However, the link between the ion transportation in nanofluidics and the solid semiconductor is still missing. This letter proposes an electrolyte doping scheme by introducing charged nanoparticles as dopers, which holds potential in modulating ion concentration in a bulk sense. These nanoparticles show a strong modulation of ion concentrations, and thus bridge the ion transportation in nanofluidics with the well-established semiconductor physics. Ionic diodes based on the present electrolyte doping picture are theoretically and experimentally demonstrated. The current-voltage characteristics are scrutinized by the depletion approximation.

  4. Composite solid polymer electrolyte membranes

    Science.gov (United States)

    Formato, Richard M. (Shrewsbury, MA); Kovar, Robert F. (Wrentham, MA); Osenar, Paul (Watertown, MA); Landrau, Nelson (Marlborough, MA); Rubin, Leslie S. (Newton, MA)

    2001-06-19

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  5. Composite solid polymer electrolyte membranes

    Science.gov (United States)

    Formato, Richard M.; Kovar, Robert F.; Osenar, Paul; Landrau, Nelson; Rubin, Leslie S.

    2006-05-30

    The present invention relates to composite solid polymer electrolyte membranes (SPEMs) which include a porous polymer substrate interpenetrated with an ion-conducting material. SPEMs of the present invention are useful in electrochemical applications, including fuel cells and electrodialysis.

  6. Non-Newtonian Rheology in Blood Circulation

    CERN Document Server

    Sochi, Taha

    2013-01-01

    Blood is a complex suspension that demonstrates several non-Newtonian rheological characteristics such as deformation-rate dependency, viscoelasticity and yield stress. In this paper we outline some issues related to the non-Newtonian effects in blood circulation system and present modeling approaches based mostly on the past work in this field.

  7. Rheological properties of defense waste slurries

    International Nuclear Information System (INIS)

    The major objective of this two-year project has been to obtain refined and reliable experimental data about the rheological properties of melter feeds. The research has involved both experimental studies and model development. Two experimental facilities have been set up to measure viscosity and pressure drop. Mathematical models have been developed as a result of experimental observation and fundamental rheological theory. The model has the capability to predict the viscosity of melter slurries in a range of experimental conditions. The final results of the investigation could be used to enhance the current design base for slurry transportation systems and improve the performance of the slurry mixing process. If successful, the cost of this waste treatment will be reduced, and disposal safety will be increased. The specific objectives for this project included: (1) the design, implementation, and validation of the experimental facility in both batch and continuous operating modes; (2) the identification and preparation of melter feed samples of both the SRS and Hanford waste slurries at multiple solids concentration levels; (3) the measurement and analysis of the melter feeds to determine the effects of the solids concentration, pH value, and other factors on the rheological properties of the slurries; (4) the correlation of the rheological properties as a function of the measured physical and chemical parameters; and (5) transmission of the experimental data and resulting correlation to the DOE site user to guide melter feed preparation and transport equipment design

  8. Rheological Modifier Testing with DWPF Process Slurries

    Energy Technology Data Exchange (ETDEWEB)

    MICHAEL, STONE

    2004-02-01

    Rheological modification agents were tested on simulated SRAT and SME products to determine if a suitable agent could be found for the DWPF process slurries. The agents tested were dispersants that lower the rheological properties of slurries by preventing agglomerization. Dolapix CE64, an ethylene glycol, and Disperse-Ayd W28, a polyacrylate, were the most effective dispersants tested. Further evaluation and testing should be performed on Dolapix CE64 and Disperse-Ayd W28 to determine if implementation is possible in DWPF. The initial phase of future work will include optimization of the rheology modifier by the Illinois Institute of Technology (IIT) and development of a maximum concentration limit for the rheology modifiers. IIT has been commissioned to evaluate the properties of these chemicals to determine if the chemical makeup can be optimized to enhance the properties of these modifiers. An initial concentration limit based upon the DWPF flammability limit and other constraints should be calculated to determine the potential downstream impacts.

  9. Aggregate of nanoparticles: rheological and mechanical properties

    Science.gov (United States)

    2011-01-01

    The understanding of the rheological and mechanical properties of nanoparticle aggregates is important for the application of nanofillers in nanocompoistes. In this work, we report a rheological study on the rheological and mechanical properties of nano-silica agglomerates in the form of gel network mainly constructed by hydrogen bonds. The elastic model for rubber is modified to analyze the elastic behavior of the agglomerates. By this modified elastic model, the size of the network mesh can be estimated by the elastic modulus of the network which can be easily obtained by rheology. The stress to destroy the aggregates, i.e., the yield stress (?y), and the elastic modulus (G') of the network are found to be depended on the concentration of nano-silica (?, wt.%) with the power of 4.02 and 3.83, respectively. Via this concentration dependent behavior, we can extrapolate two important mechanical parameters for the agglomerates in a dense packing state (? = 1): the shear modulus and the yield stress. Under large deformation (continuous shear flow), the network structure of the aggregates will experience destruction and reconstruction, which gives rise to fluctuations in the viscosity and a shear-thinning behavior. PMID:21711644

  10. Rheological Modifier Testing with DWPF Process Slurries

    International Nuclear Information System (INIS)

    Rheological modification agents were tested on simulated SRAT and SME products to determine if a suitable agent could be found for the DWPF process slurries. The agents tested were dispersants that lower the rheological properties of slurries by preventing agglomerization. Dolapix CE64, an ethylene glycol, and Disperse-Ayd W28, a polyacrylate, were the most effective dispersants tested. Further evaluation and testing should be performed on Dolapix CE64 and Disperse-Ayd W28 to determine if implementation is possible in DWPF. The initial phase of future work will include optimization of the rheology modifier by the Illinois Institute of Technology (IIT) and development of a maximum concentration limit for the rheology modifiers. IIT has been commissioned to evaluate the properties of these chemicals to determine if the chemical makeup can be optimized to enhance the properties of these modifiers. An initial concentration limit based upon the DWPF flammability limit and other constraints should be calculated to determine the potential downstream impacts

  11. RHEOLOGY OF CHICKPEA PROTEIN CONCENTRATE DISPERSIONS

    Directory of Open Access Journals (Sweden)

    Aurelia Ionescu

    2011-12-01

    Full Text Available Chickpea proteins are used as ingredients in comminuted sausage products and many oriental textured foods. Rheological behaviour of chickpea protein concentrate was studied using a controlled stress rheometer. The protein dispersion prepared with phosphate buffer at pH 7.0 presented non-Newtonian shear thinning behaviour and rheological data well fitted to the Sisko, Carreau and Cross models. The viscoelastic properties of the chickpea protein suspensions were estimated by measuring the storage and loss moduli in oscillatory frequency conditions (0.1-10 Hz at 20°C. Moreover, thermally induced gelation of the chickpea proteins (16, 24 and 36% was studied at pH 7.0 and 4.5 in the temperature range 50 to 100oC and salt concentration ranging from 0 to 1 M. Gelling behaviour was quantified by means of dynamic rheological measurements. Gels formation was preceded by the decrease of storage modulus and loss moduli, coupled with the increase of the phase angle (delta. The beginning of thermal gelation was influenced by protein concentration, pH and salt level. In all studied cases, storage modulus increased rapidly in the temperature range 70-90°C. All rheological parameters measured at 90°C were significantly higher at pH 4.5 compared to pH 7.0.

  12. Rheologically acticated spiral flow in ice sheets

    Science.gov (United States)

    Schoof, C. G.; Clarke, G. K.

    2005-12-01

    Exposed glacier beds often have a furrowed appearance due to the presence elongated sediment ridges or `flutes' aligned in the former direction of ice flow. Measurements of the orientation of elongated rock fragments in these flutes have previously been interpreted as indicative of spiral flows in basal ice, with a component of velocity transverse to the mean flow direction which tends to move sediment from the troughs of flutes to their crests. The potential origins of such spiral flows are unclear: at the low Reynolds numbers typical of glacier and ice sheet flow, commonly employed rheological models such as Glen's law preclude their formation. Secondary, transverse flows are however possible if the deviatoric stress tensor is not parallel to the strain rate tensor alone, but depends also on the contraction of the strain rate tensor with itself. This rheological effect occurs in a number of complex (Reiner-Rivlin) fluids, where it accounts for such phenomena as rod climbing and the generation of deviatoric normal stresses in simple shearing flows. Here, we review the evidence for this effect occuring in ice, and explore its implications in terms of flute formation. Our results indicate that rheologically induced spiral flows can explain the formation of flutes, and that flute spacing depends on both, the rheology of ice and the specifics of sediment transport mechanism involved.

  13. Solid electrolytes: Problems and solutions

    International Nuclear Information System (INIS)

    Degradation phenomena occurring in sodium ?''-alumina solid electrolytes as a consequence of their use in sodium/sulfur batteries are reviewed. Four classes of degradation are discussed: electrolyte reduction, crack propagation, internal sodium precipitation, and reaction with the polysulfide electrode. While degradation reactions may adversely affect cell life, it has been found that these deleterious effects may be avoided by impurity control of the system and by microstructural modification of the ceramic, including grain size control and zirconia-dispersion toughening

  14. Interfacial Tension of Electrolyte Solutions

    CERN Document Server

    Levin, Y

    2000-01-01

    A theory is presented to account for the increase in surface tension of water in the presence of electrolyte. Unlike the original ``grand-canonical'' calculation of Onsager and Samaras, which relied on the Gibbs adsorption isotherm and lead to a result which could only be expressed as an infinite series, our approach is ``canonical'' and produces an analytic formula for the excess surface tension. For small concentrations of electrolyte, our result reduces to the Onsager-Samaras limiting law.

  15. Solid polymer electrolyte lithium batteries

    Science.gov (United States)

    Alamgir, Mohamed (Dedham, MA); Abraham, Kuzhikalail M. (Needham, MA)

    1993-01-01

    This invention pertains to Lithium batteries using Li ion (Li.sup.+) conductive solid polymer electrolytes composed of solvates of Li salts immobilized in a solid organic polymer matrix. In particular, this invention relates to Li batteries using solid polymer electrolytes derived by immobilizing solvates formed between a Li salt and an aprotic organic solvent (or mixture of such solvents) in poly(vinyl chloride).

  16. Ionic thermopower of composite electrolytes

    OpenAIRE

    Vennekamp, Martin; Janek, Ju?rgen

    1999-01-01

    The ionic thermopower of solid electrolyte composites which are composed of a solid electrolyte and an electrically insulating inert phase is analyzed. For a stoichiometric model system AX with Frenkel disorder in the cation sublattice we derive formal relations within a lattice point defect model for the change in ionic thermopower on dispersing the second phase. It is shown that thermopower measurements may provide information on the defect concentrations in the space charge regions surroun...

  17. Lithium Polymer Electrolytes and Solid State NMR

    Science.gov (United States)

    Berkeley, Emily R.

    2004-01-01

    Research is being done at the Glenn Research Center (GRC) developing new kinds of batteries that do not depend on a solution. Currently, batteries use liquid electrolytes containing lithium. Problems with the liquid electrolyte are (1) solvents used can leak out of the battery, so larger, more restrictive, packages have to be made, inhibiting the diversity of application and decreasing the power density; (2) the liquid is incompatible with the lithium metal anode, so alternative, less efficient, anodes are required. The Materials Department at GRC has been working to synthesize polymer electrolytes that can replace the liquid electrolytes. The advantages are that polymer electrolytes do not have the potential to leak so they can be used for a variety of tasks, small or large, including in the space rover or in space suits. The polymers generated by Dr. Mary Ann Meador's group are in the form of rod -coil structures. The rod aspect gives the polymer structural integrity, while the coil makes it flexible. Lithium ions are used in these polymers because of their high mobility. The coils have repeating units of oxygen which stabilize the positive lithium by donating electron density. This aids in the movement of the lithium within the polymer, which contributes to higher conductivity. In addition to conductivity testing, these polymers are characterized using DSC, TGA, FTIR, and solid state NMR. Solid state NMR is used in classifying materials that are not soluble in solvents, such as polymers. The NMR spins the sample at a magic angle (54.7') allowing the significant peaks to emerge. Although solid state NMR is a helpful technique in determining bonding, the process of preparing the sample and tuning it properly are intricate jobs that require patience; especially since each run takes about six hours. The NMR allows for the advancement of polymer synthesis by showing if the expected results were achieved. Using the NMR, in addition to looking at polymers, allows for participation on a variety of other projects, including aero-gels and carbon graphite mat en als. The goals of the polymer electrolyte research are to improve the physical properties of the polymers. This includes improving conductivity, durability, and expanding the temperature range over which it is effective. Currently, good conductivity is only present at high temperatures. My goals are to experiment with different arrangements of rods and coils to achieve these desirable properties. Some of my experiments include changing the number of repeat units in the polymer, the size of the diamines, and the types of coil. Analysis of these new polymers indicates improvement in some properties, such as lower glass transition temperature; however, they are not as flexible as desired. With further research we hope to produce polymers that encompass all of these properties to a high degree.

  18. Optimizing end-group cross-linking polymer electrolytes for fuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yu Seung [Los Alamos National Laboratory; Lee, Kwan Soo [Los Alamos National Laboratory; Jeong, Myung - Hwan [GIST, KOREA; Lee, Jae - Suk [GIST, KOREA

    2009-01-01

    This paper demonstrates the optimization of proton conductivity and water uptake for cross-linkable polymer electrolytes through synthesis and characterization of end-group cross-linkable sulfonated poly(arylene ether) copolymers (ESF-BPs). The extent of reaction of cross-linking was controlled by reaction time resulting in a series of polymers with two, independent tunable parameters, degree of sulfonation (DS) and degree of cross-linking (DC). For the polymers presented, cross-linking improved proton conductivity while reducing water uptake, an uncommon trend in polymer electrolytes where water is critical for proton conduction. Other trends relating to changes are reported and the results yield insight into the role of DS and DC and how to optimize electrochemical properties and performance of polymer electrolytes through these tunable parameters. Select polymer electrolytes were tested in fuel cells where performance and durability with accelerated relative humidity cycling were compared with Nafion{reg_sign}.

  19. Cyclic Macromolecules: Dynamics and Nonlinear Rheology, Final Report DOE Award # DE-FG02-05ER46218, Texas Tech University

    Energy Technology Data Exchange (ETDEWEB)

    McKenna, Gregory B.; Grubbs, Robert H.; Kornfield, Julia A.

    2012-04-25

    The work described in the present report had the original goal to produce large, entangled, ring polymers that were uncontaminated by linear chains and to characterize by rheological methods the dynamics of these rings. While the work fell short of this specific goal, the outcomes of the research performed under support from this grant provided novel macromolecular synthesis methods, new separation methods for ring and linear chains, and novel rheological data on bottle brush polymers, wedge polymers and dendron-based ring molecules. The grant funded a total of 8 archival manuscripts and one patent, all of which are attached to the present report.

  20. Supercapacitor behavior of ?-MnMoO4 nanorods on different electrolytes

    International Nuclear Information System (INIS)

    Graphical abstract: SEM image of ?-MnMoO4 nanorods on FTO substrate. Highlights: ? Synthesis of ?-MnMoO4 nanorods by spin coating method. ? First study on the effect of electrolyte on the pseudocapacitance behavior. ? ?-MnMoO4 nanorods exhibit maximum specific capacitance of 998 F/g. ? At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: ?-MnMoO4 nanorods were prepared on conducting glass substrate via sol–gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the ?-MnMoO4 nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H2SO4) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of ?-MnMoO4 in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M–O and Mo–O–Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. ?-MnMoO4 nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H2SO4 electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H2SO4.

  1. Hybrid proton-conducting membranes for polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    The synthesis and characterization of a novel hybrid organic-inorganic material formed by phosphomolybdic acid H3PMo12O40 (PMo12) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are stable up to 200 deg. C, and have a proton conductivity of 3 x 10-2 S cm-1 at 185 deg. C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100-200 deg. C

  2. Hybrid proton-conducting membranes for polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Romero, Pedro [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain)]. E-mail: pedro.gomez@icmab.es; Asensio, Juan Antonio [Institut de Ciencia de Materials de Barcelona (CSIC), Campus UAB, E-08193 Bellaterra (Barcelona) (Spain); Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain); Borros, Salvador [Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta 390, E-08017 Barcelona (Spain)

    2005-08-30

    The synthesis and characterization of a novel hybrid organic-inorganic material formed by phosphomolybdic acid H{sub 3}PMo{sub 12}O{sub 40} (PMo{sub 12}) and poly(2,5-benzimidazole) (ABPBI) is reported. This material, composed of two proton-conducting components, can be cast in the form of membranes from methanesulfonic acid (MSA) solutions. Upon impregnation with phosphoric acid, the hybrid membranes present higher conductivity than the best ABPBI polymer membranes impregnated in the same conditions. These electrolyte membranes are stable up to 200 deg. C, and have a proton conductivity of 3 x 10{sup -2} S cm{sup -1} at 185 deg. C without humidification. These properties make them very good candidates as membranes for polymer electrolyte membrane fuel cells (PEMFC) at temperatures of 100-200 deg. C.

  3. Role of Yield Stress in Magma Rheology

    Science.gov (United States)

    Kurokawa, A.; Di Giuseppe, E.; Davaille, A.; Kurita, K.

    2012-04-01

    Magmas are essentially multiphase material composed of solid crystals, gaseous bubbles and silicate liquids. They exhibit various types of drastic change in rheology with variation of mutual volumetric fractions of the components. The nature of this variable rheology is a key factor in controlling dynamics of flowing magma through a conduit. Particularly the existence of yield stress in flowing magma is expected to control the wall friction and formation of density waves. As the volumetric fraction of solid phase increases yield stress emerges above the critical fraction. Several previous studies have been conducted to clarify this critical value of magmatic fluid both in numerical simulations and laboratory experiments ([Lejeune and Pascal, 1995], [Saar and Manga 2001], [Ishibashi and Sato 2010]). The obtained values range from 13.3 to 40 vol%, which display wide variation and associated change in rheology has not been clarified well. In this presentation we report physical mechanism of emergence of yield stress in suspension as well as the associated change in the rheology based on laboratory experiments using analog material. We utilized thermogel aqueous suspension as an analog material of multiphase magma. Thermogel, which is a commercial name for poly(N-isopropyl acrylamide) (PNIPAM) undergoes volumetric phase change at the temperature around 35C:below this temperature the gel phase absorbs water and swells while below this it expels water and its volume shrinks. Because of this the volumetric fraction of gel phase systematically changes with temperature and the concentration of gel powder. The viscosity measured at lower stress drastically decreases across this phase change with increasing temperature while the viscosity at higher stress does not exhibit large change across the transition. We have performed a series of rheological measurements focusing on the emergence of yield stress on this aqueous suspension. Since the definition of yield stress is not well defined in the suspension rheology we tested three types of measurement in determination of yield stress. Two methods utilized cone-plate geometry performing creep test (stress controlled) and variable shear rate test and one utilized narrow-gap concentric cylinder geometry with variable shear rate. Herschel-Bulckley model can be successfully applied to variable shear-rate tests to determine yield stress. Creep test and H-B model give almost identical yield stress, for instance 45±5Pa at 2.5wt%. At the gel volume fraction of 50% yield stress emerges and it increases with the increase of the concentration of gel powder. This critical value roughly corresponds to the random loose packing fraction while the viscosity begins to increase at lower fraction.

  4. The Rheology of Phlegrean Field Magmas

    Science.gov (United States)

    Romano, C.; Giordano, D.; Caricchi, L.; Vona, A.; Burlini, L.; Ulmer, P.; Hess, K.; Dingwell, D. B.

    2007-12-01

    In order to quantify the effect of crystals on the rheology of Monte Nuovo magma, a series of torsional and compressional deformation-experiments have been performed in an internally heated Paterson-type apparatus at the ETH (Zurich). The porosity present in the scoriaceous samples has previously been removed, annealing the samples at 300 MPa confining P and 1073 K. Unconfined uniaxial compression experiments were also performed at the Geological Sciences Dep. of the University of Roma Tre; the EOS department at the UBC, Vancouver and the LMU, Munich. The three presses are complementary in nature, with different maximum loads (10, 44 and 300 KN, respectively) and displacement rates (from 10-1 to 10-6 cm/s, for the first two presses and 100 to 10-8 cm/s for the large press in Munich). Results from multiphase rheology of bubble-free (Paterson) and vesicle-bearing (uniaxial presses) samples show that viscosity of crystal-bearing samples is affected by the strain rate, showing clear non-Newtonian behaviour (shear-thinning) already at low deformation-rates. Within the regime of applied strain rate no yield stress can be observed. In addition to the multiphase rheological investigation, we have also investigated the liquid and, where possible, the liquid+crystal rheology of remelted products of Agnano Monte Spina (AMS), Monte Nuovo (MNV) and Fondo Riccio (FR) . Viscosities of pure liquids and liquid+crystals mixtures within the range 101-105 Pa s and T between 1100 and 1500° C were measured by concentric cylinder. Low-T viscosity was measured using the micropenetration technique. Isothermal holds measurements on MNV and AMS samples did not show any significant effect on the viscosity due to sample crystallization. However, viscosity measurement on FR samples at variable rates of strain suggest that non-Newtonian rheology occurs even at low crystal contents. In addition to evaluating the onset of non-Newtonian rheology, isothermal holds viscosity measurements can also define a time-temperature-viscosity window over which crystallization occurs. Results indicate that crystallization is dominantly governed by T (favouring) rather than viscosity (inhibiting). Below 1150° C a very rapid viscosity increase occurs due to a high crystallization rate.

  5. Fluid and Electrolyte Nutrition

    Science.gov (United States)

    Lane, Helen W.; Smith, Scott M.; Leach, Carolyn S.; Rice, Barbara L.

    1999-01-01

    Studies of fluid and electrolyte homeostasis have been completed since the early human space flight programs, with comprehensive research completed on the Spacelab Life Sciences missions SLS-1 and SLS-2 flights, and more recently on the Mir 18 mission. This work documented the known shifts in fluids, the decrease in total blood volume, and indications of reduced thirst. Data from these flights was used to evaluate the nutritional needs for water, sodium, and potassium. Interpretations of the data are confounded by the inadequate energy intakes routinely observed during space flight. This in turn results in reduced fluid intake, as food provides approximately 70% water intake. Subsequently, body weight, lean body mass, total body water, and total body potassium may decrease. Given these issues, there is evidence to support a minimum required water intake of 2 L per day. Data from previous Shuttle flights indicated that water intake is 2285 +/- 715 ml/day (mean +/- SD, n=26). There are no indications that sodium intake or homeostasis is compromised during space flight. The normal or low aldosterone and urinary sodium levels suggest adequate sodium intake (4047 +/- 902 mg/day, n=26). Because excessive sodium intake is associated with hypercalciuria, the recommended maximum amount of sodium intake during flight is 3500 mg/day (i.e., similar to the Recommended Dietary Allowance, RDA). Potassium metabolism appears to be more complex. Data indicate loss of body potassium related to muscle atrophy and low dietary intake (2407 +/- 548 mg/day, n=26). Although possibly related to measurement error, the elevations in blood potassium suggest alterations in potassium homeostasis. The space RDA for minimum potassium intake is 3500 mg/day. With the documented inadequate intakes, efforts are being made to increase dietary consumption of potassium.

  6. Air-Stable, High-Conduction Solid Electrolytes of Arsenic-Substituted Li4SnS4

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Gayatri [ORNL; Lin, Zhan [ORNL; Li, Juchuan [ORNL; Liu, Zengcai [ORNL; Dudney, Nancy J [ORNL; Liang, Chengdu [ORNL

    2014-01-01

    Lithium-ion-conducting solid electrolytes show promise for enabling high-energy secondary battery chemistries and solving safety issues associated with conventional lithium batteries. Achieving the combination of high ionic conductivity and outstanding chemical stability in solid electrolytes is a grand challenge for the synthesis of solid electrolytes. Herein we report the design of aliovalent substitution of Li4SnS4 to achieve high conduction and excellent air stability based on the hard and soft acids and bases theory. The composition of Li3.833Sn0.833As 0.166S4 has a high ionic conductivity of 1.39 mS/cm 1 at 25 C. Considering the high Li+ transference number, this phase conducts Li+ as well as carbonate-based liquid electrolytes. This research also addresses the compatibility of the sulfide-based solid electrolytes through chemical passivation.

  7. The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

    Science.gov (United States)

    Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

    1993-01-01

    Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

  8. Nonlinear Rheology of a Nanoconfined Simple Fluid

    Science.gov (United States)

    Bureau, Lionel

    2010-05-01

    We probe the rheology of the model liquid octamethylcyclotetrasiloxane (OMCTS) confined into molecularly thin films, using a unique surface force apparatus allowing us to explore a large range of shear rates and confinement. We thus show that OMCTS under increasing confinement exhibits the viscosity enhancement and the nonlinear flow properties characteristic of a sheared supercooled liquid approaching its glass transition. Besides, we study the drainage of confined OMCTS via the propagation of “squeeze-out” fronts. The hydrodynamic model proposed by Becker and Mugele [Phys. Rev. Lett. 91, 166104 (2003)PRLTAO0031-900710.1103/PhysRevLett.91.166104] to describe such front dynamics leads to a conclusion in apparent contradiction with the dynamical slowdown evidenced by rheology measurements, which suggests that front propagation is not controlled by large scale flow in the confined films.

  9. High Strain Rate Rheology of Polymer Melts

    Science.gov (United States)

    Kelly, Adrian; Gough, Tim; Whiteside, Ben; Coates, Phil D.

    2009-07-01

    A modified servo electric injection moulding machine has been used in air-shot mode with capillary dies fitted at the nozzle to examine the rheology of a number of commercial polymers at wall shear strain rates of up to 107 s-1. Shear and extensional flow properties were obtained through the use of long and orifice (close to zero land length) dies of the same diameter. A range of polyethylene, polypropylene and polystyrene melts have been characterized; good agreement was found between the three techniques used in the ranges where strain rates overlapped. Shear viscosity of the polymers studied was found to exhibit a plateau above approximately 1×106 s-1. A relationship between the measured high strain rate rheological behaviour and molecular structure was noted, with polymers containing larger side groups reaching the rate independent plateau at lower strain rates than those with simpler structures.

  10. Shear thickening, frictionless and frictional rheologies

    CERN Document Server

    Mari, Romain; Morris, Jeffrey F; Denn, Morton M

    2014-01-01

    Particles suspended in a Newtonian fluid raise the viscosity and also generally give rise to a shear-rate dependent rheology. In particular, pronounced shear thickening is observed at large solid volume fractions. In a recent article (R. Seto, R. Mari, J. F. Morris, and M. M. Denn., Phys. Rev. Lett., 111:218301, 2013) we have considered the minimum set of components to reproduce the experimentally observed shear thickening behavior, including Discontinuous Shear Thickening (DST). We have found frictional contact forces to be essential, and were able to reproduce the experimental behavior by a simulation including this physical ingredient. In the present article, we thoroughly investigate the effect of friction and express it in the framework of the jamming transition. The viscosity divergence at the jamming transition has been a well known phenomenon in suspension rheology, as reflected in many empirical laws for the viscosity. Friction can affect this divergence, and in particular the jamming packing fractio...

  11. Rheological properties of a calcium smectite

    International Nuclear Information System (INIS)

    The rheological and mechanical properties of a Ca-smectite have been investigated by different laboratory tests. By these tests the permeability, the water uptake properties, the swelling properties, the swelling pressure, the stress-strain properties, the strength and the creep properties have been determined. The influence of density, temperature, time and stress level have been considered. Mathematical models of the measured properties and behavior of the clay have been suggested so that calculations involving mechanical and rheological scenarios can be made. The behavior of the clay have been discussed with reference to the microstructure and comparisons between the investigated Ca-smectite and a Na-smectite (Mx-80) have been made. One main conclusion is that the difference between the properties and behavior of Ca-smectite and Na-smectite is small at densities >2.0 t/m3. At densities 3 the difference is increasing with decreasing density. (orig./HP)

  12. Glass transitions and shear thickening suspension rheology

    CERN Document Server

    Holmes, C B; Fuchs, M; Sollich, P

    2004-01-01

    We introduce a class of simple models for shear thickening and/ or `jamming' in colloidal suspensions. These are based on schematic mode coupling theory (MCT) of the glass transition, having a memory term that depends on a density variable, and on both the shear stress and the shear rate. (Tensorial aspects of the rheology, such as normal stresses, are ignored for simplicity.) We calculate steady-state flow curves and correlation functions. Depending on model parameters, we find a range of rheological behaviours, including `S-shaped' flow curves, indicating discontinuous shear thickening, and stress-induced transitions from a fluid to a nonergodic (jammed) state, showing zero flow rate in an interval of applied stress. The shear thickening and jamming scenarios that we explore appear broadly consistent with experiments on dense colloids close to the glass transition, despite the fact that we ignore hydrodynamic interactions. In particular, the jamming transition we propose is conceptually quite different from...

  13. The effect of low-molecular-weight poly(ethylene glycol) (PEG) plasticizers on the transport properties of lithium fluorosulfonimide ionic melt electrolytes.

    Science.gov (United States)

    Geiculescu, Olt E; Hallac, Boutros B; Rajagopal, Rama V; Creager, Stephen E; DesMarteau, Darryl D; Borodin, Oleg; Smith, Grant D

    2014-05-15

    The influence of low-molecular-weight poly(ethylene glycol) (PEG, Mw ? 550 Da) plasticizers on the rheology and ion-transport properties of fluorosulfonimide-based polyether ionic melt (IM) electrolytes has been investigated experimentally and via molecular dynamics (MD) simulations. Addition of PEG plasticizer to samples of IM electrolytes caused a decrease in electrolyte viscosity coupled to an increase in ionic conductivity. MD simulations revealed that addition of plasticizer increased self-diffusion coefficients for both cations and anions with the plasticizer being the fastest diffusing species. Application of a VTF model to fit variable-temperature conductivity and fluidity data shows that plasticization decreases the apparent activation energy (Ea) and pre-exponential factor A for ion transport and also for viscous flow. Increased ionic conductivity with plasticization is thought to reflect a combination of factors including lower viscosity and faster polyether chain segmental dynamics in the electrolyte, coupled with a change in the ion transport mechanism to favor ion solvation and transport by polyethers derived from the plasticizer. Current interrupt experiments with Li/electrolyte/Li cells revealed evidence for salt concentration polarization in electrolytes containing large amounts of plasticizer but not in electrolytes without added plasticizer. PMID:24773589

  14. Rheological analysis of crumb rubber modified binder

    OpenAIRE

    Mturi, G. A. J.; O Connell, J.

    2011-01-01

    In South Africa. the use of crumb rubber modified (CRM) bitumen has increased over the years as increased traftic loads have resulted in higher performance requirements. Empirical binder characterisation of CRM bitumen remains widespread internationally, even though empirical properties cannot predict asphalt mix performance. Advanced rheological characterisation of CRM bitumen using a dynamic shear rheometer (DSR) is a superior alternative once the morphological challenge of the binary binde...

  15. Rheological evaluation of pretreated cladding removal waste

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, D.; Chan, M.K.C.; Lokken, R.O.

    1986-01-01

    Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid.

  16. Rheological evaluation of pretreated cladding removal waste

    International Nuclear Information System (INIS)

    Cladding removal waste (CRW) contains concentrations of transuranic (TRU) elements in the 80 to 350 nCi/g range. This waste will require pretreatment before it can be disposed of as glass or grout at Hanford. The CRW will be pretreated with a rare earth strike and solids removal by centrifugation to segregate the TRU fraction from the non-TRU fraction of the waste. The centrifuge centrate will be neutralized with sodium hydroxide. This neutralized cladding removal waste (NCRW) is expected to be suitable for grouting. The TRU solids removed by centrifugation will be vitrified. The goal of the Rheological Evaluation of Pretreated Cladding Removal Waste Program was to evaluate those rheological and transport properties critical to assuring successful handling of the NCRW and TRU solids streams and to demonstrate transfers in a semi-prototypic pumping environment. This goal was achieved by a combination of laboratory and pilot-scale evaluations. The results obtained during these evaluations were correlated with classical rheological models and scaled-up to predict the performance that is likely to occur in the full-scale system. The Program used simulated NCRW and TRU solid slurries. Rockwell Hanford Operations (Rockwell) provided 150 gallons of simulated CRW and 5 gallons of simulated TRU solid slurry. The simulated CRW was neutralized by Pacific Northwest Laboratory (PNL). The physical and rheological properties of the NCRW and TRU solid slurries were evaluated in the laboratory. The properties displayed by NCRW allowed it to be classified as a pseudoplastic or yield-pseudoplastic non-Newtonian fluid. The TRU solids slurry contained very few solids. This slurry exhibited the properties associated with a pseudoplastic non-Newtonian fluid

  17. Rheology Modifiers for Radioactive Waste Slurries

    International Nuclear Information System (INIS)

    The goals of this study were to determine if trace levels of chemical additives could be used to reduce the rheological characteristics of radioactive waste slurries, identify potential chemical additives for this work and future testing, test a limited set of chemical additive candidates on simulated radioactive wastes, and develop advanced techniques to visualize the internal slurry structure and particle-particle interaction within the slurry

  18. Rheological models applied to wheat and corn dough

    Directory of Open Access Journals (Sweden)

    Eduardo Rodríguez Sandoval

    2010-04-01

    Full Text Available Rheological models of a food system are useful for simulating a material’s response to an applied stress or strain and for predicting the effect of composition and processing conditions. Rheological models can be applied when experimental data is expressed in fundamental units. This article describes two rheological models used for studying wheat and corn dough: the biaxial extensional model and the oscillatory dynamic model. The results of research related to this topic are also reported.

  19. Rheological models applied to wheat and corn dough

    OpenAIRE

    Eduardo Rodríguez Sandoval; Alejandro Fernández Quintero; Alfredo Ayala Aponte

    2010-01-01

    Rheological models of a food system are useful for simulating a material’s response to an applied stress or strain and for predicting the effect of composition and processing conditions. Rheological models can be applied when experimental data is expressed in fundamental units. This article describes two rheological models used for studying wheat and corn dough: the biaxial extensional model and the oscillatory dynamic model. The results of research related to this topic are also reported.

  20. Rheological effects of bed rest in sickle cell disease.

    OpenAIRE

    Keidan, A. J.; Stuart, J.

    1987-01-01

    A serial rheological study in two patients with homozygous sickle cell disease whose leg ulcers healed as a consequence of bed rest showed an improvement in erythrocyte deformability (filterability) associated with evidence of decreased haemolysis and a fall in the number of irreversibly sickled cells. This rheological improvement may aid the healing of leg ulcers by increasing blood flow in the ulcer base. The effects of bed rest on the rheology of sickle cell disease should be taken into ac...

  1. Investigating the rheological properties of native plant latex

    OpenAIRE

    Bauer, Georg; Friedrich, Christian; Gillig, Carina; Vollrath, Fritz; Speck, Thomas; Holland, Chris

    2014-01-01

    Plant latex, the source of natural rubber, has been of interest to mankind for millennia, with much of the research on its rheological (flow) properties focused towards industrial application. However, little is known regarding the rheology of the native material as produced by the plant, a key factor in determining latex's biological functions. In this study, we outline a method for rheological comparison between native latices that requires a minimum of preparatory steps. Our approach provi...

  2. ALTERATION OF RHEOLOGICAL PROPERTIES OF BLOOD AT PATIENTS WITH TONSILLITIS

    Directory of Open Access Journals (Sweden)

    I.A. Zaitseva

    2008-09-01

    Full Text Available Complex research of rheological properties of blood at patients with lacunar tonsillitis lead depending on the period of disease. It is shown, that inflammatory process at patients to a great extent defines disturbances of rheological properties of blood. During normalization of a clinical presentation of disease there is no full recovery of rheological properties of blood due to preservation of blood raised viscosity and low deformability of erythrocytes membranes.

  3. Rheological properties of cementitious composites in fresh state

    OpenAIRE

    Hoc?evar, Andraz?

    2013-01-01

    Doctoral dissertation discusses the concept of the rheology of fresh cement based composites. On the territory of Slovenia, no one has dealt with the topic of rheology of fresh cement based composites with an emphasis on concrete. For this reason, the task is based more generally. Dissertation discusses the basic principles of the rheology of fresh cement composites and is then directed in a more specific topic. Reographs for use with Slovenian materials are established. Basic principles of r...

  4. High elastic modulus polymer electrolytes

    Science.gov (United States)

    Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel

    2013-10-22

    A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.

  5. Towards Prognostics of Electrolytic Capacitors

    Science.gov (United States)

    Celaya, Jose R.; Kulkarni, Chetan; Biswas, Gautam; Goegel, Kai

    2011-01-01

    A remaining useful life prediction algorithm and degradation model for electrolytic capacitors is presented. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their low reliability and given their criticality in electronics subsystems they are a good candidate for component level prognostics and health management research. Prognostics provides a way to assess remaining useful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. In particular, experimental results of an accelerated aging test under electrical stresses are presented. The capacitors used in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This preliminary remaining life prediction algorithm serves as a demonstration of how prognostics methodologies could be used for electrolytic capacitors.

  6. Anion exchange polymer electrolytes

    Science.gov (United States)

    Kim, Yu Seung; Kim, Dae Sik; Lee, Kwan-Soo

    2013-07-23

    Solid anion exchange polymer electrolytes and compositions comprising chemical compounds comprising a polymeric core, a spacer A, and a guanidine base, wherein said chemical compound is uniformly dispersed in a suitable solvent and has the structure: ##STR00001## wherein: i) A is a spacer having the structure O, S, SO.sub.2, --NH--, --N(CH.sub.2).sub.n, wherein n=1-10, --(CH.sub.2).sub.n--CH.sub.3--, wherein n=1-10, SO.sub.2-Ph, CO-Ph, ##STR00002## wherein R.sub.5, R.sub.6, R.sub.7 and R.sub.8 each are independently --H, --NH.sub.2, F, Cl, Br, CN, or a C.sub.1-C.sub.6 alkyl group, or any combination of thereof; ii) R.sub.9, R.sub.10, R.sub.11, R.sub.12, or R.sub.13 each independently are --H, --CH.sub.3, --NH.sub.2, --NO, --CH.sub.nCH.sub.3 where n=1-6, HC.dbd.O--, NH.sub.2C.dbd.O--, --CH.sub.nCOOH where n=1-6, --(CH.sub.2).sub.n--C(NH.sub.2)--COOH where n=1-6, --CH--(COOH)--CH.sub.2--COOH, --CH.sub.2--CH(O--CH.sub.2CH.sub.3).sub.2, --(C.dbd.S)--NH.sub.2, --(C.dbd.NH)--N--(CH.sub.2).sub.nCH.sub.3, where n=0-6, --NH--(C.dbd.S)--SH, --CH.sub.2--(C.dbd.O)--O--C(CH.sub.3).sub.3, --O--(CH.sub.2).sub.n--CH--(NH.sub.2)--COOH, where n=1-6, --(CH.sub.2).sub.n--CH.dbd.CH wherein n=1-6, --(CH.sub.2).sub.n--CH--CN wherein n=1-6, an aromatic group such as a phenyl, benzyl, phenoxy, methylbenzyl, nitrogen-substituted benzyl or phenyl groups, a halide, or halide-substituted methyl groups; and iii) wherein the composition is suitable for use in a membrane electrode assembly.

  7. Shear rheology of molten crumb chocolate.

    Science.gov (United States)

    Taylor, J E; Van Damme, I; Johns, M L; Routh, A F; Wilson, D I

    2009-03-01

    The shear rheology of fresh molten chocolate produced from crumb was studied over 5 decades of shear rate using controlled stress devices. The Carreau model was found to be a more accurate description than the traditional Casson model, especially at shear rates between 0.1 and 1 s(-1). At shear rates around 0.1 s(-1) (shear stress approximately 7 Pa) the material exhibited a transition to a solid regime, similar to the behavior reported by Coussot (2005) for other granular suspensions. The nature of the suspension was explored by investigating the effect of solids concentration (0.20 cocoa butter, and (2) a suspension of sugar of a similar size distribution (volume mean 15 mum) in cocoa butter and emulsifier. The chocolate and synthetic chocolate showed very similar rheological profiles under both steady shear and oscillatory shear. The chocolate and the sugar suspension showed similar Krieger-Dougherty dependency on volume fraction, and a noticeable transition to a stiff state at solids volume fractions above approximately 0.5. Similar behavior has been reported by Citerne and others (2001) for a smooth peanut butter, which had a similar particle size distribution and solids loading to chocolate. The results indicate that the melt rheology of the chocolate is dominated by hydrodynamic interactions, although at high solids volume fractions the emulsifier may contribute to the departure of the apparent viscosity from the predicted trend. PMID:19323742

  8. Ageing and Rheology in Soft Materials

    CERN Document Server

    Fielding, S M; Cates, M E

    1999-01-01

    We study theoretically the role of ageing in the rheology of soft materials. We define several generalized rheological response functions suited to ageing samples (in which time translation invariance is lost). These are then used to study ageing effects within a simple scalar model (the "soft glassy rheology" or SGR model) whose constitutive equations relate shear stress to shear strain among a set of elastic elements, with distributed yield thresholds, undergoing activated dynamics governed by a "noise temperature", $x$. (Between yields, each element follows affinely the applied shear.) For $1

  9. Rheological Characterization of Shale – Mud Interactions

    Directory of Open Access Journals (Sweden)

    W. O. Emofurieta

    2012-03-01

    Full Text Available

    In a bid to identify a best drilling fluid for a problematic oil field in the Niger Delta region, rheological tests were carried out on three mud samples; BW1, BW3 and BW4. The results affirm that the load bearing capacity of XP-07 formulated as BW3 and BW4 in this investigation is excellent and fall within the same range or even better than those of REF Mud with a more than 90% drilling success history in Niger Delta. The rheological changes of XP-07 with increase in temperature and “assimilated” microscopic shale particles are very negligible and smaller than those of REF mud. XP-07 has been strongly recommended for all drilling operations in the problematic field. It has been re-emphasised as part of our recommendations that new guidelines for the close monitoring of drilling fluids supplied by mud companies and those actually used in the field (during drilling be put in place.

    Key words: Shale – mud interactions; Rheological characterization; Niger delta

  10. Rheological properties of a vesicle suspension

    Science.gov (United States)

    Guedda, M.; Benlahsen, M.; Misbah, C.

    2014-11-01

    The rheological behavior of a dilute suspension of vesicles in linear shear flow at a finite concentration is analytically examined. In the quasispherical limit, two coupled nonlinear equations that describe the vesicle orientation in the flow and its shape evolution were derived [Phys. Rev. Lett. 96, 028104 (2006), 10.1103/PhysRevLett.96.028104] and serve here as a starting point. Of special interest is to provide, for the first time, an exact analytical prediction of the time-dependent effective viscosity ?eff and normal stress differences N1 and N2. Our results shed light on the effect of the viscosity ratio ? (defined as the inner over the outer fluid viscosities) as the main controlling parameter. It is shown that ?eff,N1 , and N2 either tend to a steady state or describe a periodic time-dependent rheological response, previously reported numerically and experimentally. In particular, the shear viscosity minimum and the cusp singularities of ?eff,N1 , and N2 at the tumbling threshold are brought to light. We also report on rheology properties for an arbitrary linear flow. We were able to obtain a constitutive law in a closed form relating the stress tensor to the strain rate tensor. It is found that the resulting constitutive markedly contrasts with classical laws known for other complex fluids, such as emulsions, capsule suspensions, and dilute polymer solutions (Oldroyd B model). We highlight the main differences between our law and classical laws.

  11. Post-seismic stress relaxation with a linear transient rheology

    Directory of Open Access Journals (Sweden)

    Antonio Piersanti

    2010-05-01

    Full Text Available We performed an analysis of post-seismic stress relaxation, taking into account generalized linear rheologies. We compared the stress field (and its derived functions obtained with a classical Maxwell rheology with that obtained with a transient Burgers body. From a set of synthetic case studies, we have revealed quantitative and qualitative differences both in relaxation times and in local stress values when a transient rheology is introduced. As a practical application, we modeled the time evolution of the Coulomb failure function following the 2009 L'Aquila earthquake, and we show that a transient rheology can lead to non-monotonic time dependence.

  12. pH effects on the molecular structure of ?-lactoglobulin modified air-water interfaces and its impact on foam rheology.

    Science.gov (United States)

    Engelhardt, Kathrin; Lexis, Meike; Gochev, Georgi; Konnerth, Christoph; Miller, Reinhard; Willenbacher, Norbert; Peukert, Wolfgang; Braunschweig, Björn

    2013-09-17

    Macroscopic properties of aqueous ?-lactoglobulin (BLG) foams and the molecular properties of BLG modified air-water interfaces as their major structural element were investigated with a unique combination of foam rheology measurements and interfacial sensitive methods such as sum-frequency generation and interfacial dilatational rheology. The molecular structure and protein-protein interactions at the air-water interface can be changed substantially with the solution pH and result in major changes in interfacial dilational and foam rheology. At a pH near the interfacial isoelectric point BLG molecules carry zero net charge and disordered multilayers with the highest interfacial dilatational elasticity are formed at the air-water interface. Increasing or decreasing the pH with respect to the isoelectric point leads to the formation of a BLG monolayer with repulsive electrostatic interactions among the adsorbed molecules which decrease the interfacial dilational elasticity. The latter molecular information does explain the behavior of BLG foams in our rheological studies, where in fact the highest apparent yield stresses and storage moduli are established with foams from electrolyte solutions with a pH close to the isoelectric point of BLG. At this pH the gas bubbles of the foam are stabilized by BLG multilayers with attractive intermolecular interactions at the ubiquitous air-water interfaces, while BLG layers with repulsive interactions decrease the apparent yield stress and storage moduli as stabilization of gas bubbles with a monolayer of BLG is less effective. PMID:23961700

  13. Mixed electrolytes producing very weak electroacoustic signal.

    Science.gov (United States)

    Kosmulski, Marek; Rosenholm, Jarl B

    2007-11-15

    The electrokinetic potential of powders dispersed in concentrated solutions of salts can be determined by electroacoustic methods when the ESA (electrokinetic sonic amplitude) signal of electrolyte is properly corrected for. We propose an alternative solution to the problem of electroacoustic measurements at high ionic strengths; that is, the composition of mixed electrolytes with common ions can be adjusted to minimize the ESA signal of the electrolyte. The measurement of electrokinetic potential of powders dispersed in such mixed electrolytes does not require electrolyte background correction. Mixed electrolytes, which produce very weak ESA signals, were prepared from the following salts with common ions: Li+ (LiNO3 + LiCl), Na+ (NaNO3 + NaBr), K+ (KBr + KNO3), and NO(-)3 (LiNO3 + KNO3). Proportions of the components in these mixed electrolytes are concentration dependent. The electrokinetic potentials of alumina in these mixed electrolytes determined with and without background correction were only marginally different. PMID:17686486

  14. Effective dielectric constant of electrolytes

    Science.gov (United States)

    Barbero, G.; Lelidis, I.

    2014-05-01

    We show that in the framework of the Poisson-Nernst-Planck model, where the ions are assumed point-like particles, the dielectric constant of the electrolyte coincides with that of the solvent in which the ions are dispersed. Only in the case where the ions are considered polarizable particles, their presence can contribute to the effective dielectric constant of the electrolyte and can play a role in the non-linear version of the Poisson-Nernst-Planck model. From this observation, it follows that generalizations of the linear Poisson-Nernst-Planck model in which the dielectric constant of the solution is considered depending on the ionic distributions are questionable.

  15. Novel poly(ethylene glycol) gel electrolytes prepared using self-assembled 1,3:2,4-dibenzylidene-D-sorbitol.

    Science.gov (United States)

    Lai, Wei-Chi; Chen, Chien-Chu

    2014-01-14

    Gel electrolytes have usually been prepared by adding gelators or polymers to the liquid organic solvent-based electrolytes. In this study, we proposed a method to prepare gel electrolytes using gelators in liquid (low molecular weight) polymer-based electrolytes. Inexpensive 1,3:2,4-dibenzylidene-D-sorbitol (DBS) was chosen as a gelator for poly(ethylene glycol) (PEG)-based electrolytes at relatively low DBS concentrations. A series of gel electrolytes was produced by varying the DBS amounts, PEG molecular weights and PEG end groups. First, we found that DBS molecules self-assembled into 3-D networks consisting of nanofibrils that were approximately 10 nm in diameter, as measured by transmission electron microscopy; they exhibited spherulite-like morphologies under polarizing optical microscopy. Second, the dynamic rheological measurements demonstrated that the elastic modulus and the dissolution temperature of DBS-PEG gels increased with the increasing DBS content. The thermal degradation temperature of these gels also increased when the DBS concentration increased, as determined by thermogravimetric analysis. In addition, adding DBS may help to facilitate the dissolution of iodide and iodine in PEG due to its ether groups. Furthermore, the conductivity of the prepared DBS-PEG gel electrolytes was similar to that of the liquid PEG electrolytes (without DBS). When used in dye-sensitized solar cells (DSSC), the PEG-based electrolytes having inactive methyl end groups achieved the highest energy conversion efficiency among the tested cells. The efficiency of DSSC filled with our gel electrolytes remained basically the same over a one-month period, implying that the materials were relatively stable. PMID:24651903

  16. Electrolytic indium refining from cadmium in glycerine electrolyte

    International Nuclear Information System (INIS)

    The results of investigations directed on development of electrochemical indium cleaning from cadmium in glycerine base electrolyte are presented. Optimal operational conditions, specific consumption of reactants and electric power are determined. Relationship between variation of concentration of cadmium impurity in refined metal and duration of electrolysis is revealed. The method for determination of cleaning time is proposed. Developed process was put into commercial operation

  17. A novel MOCVD strategy for the fabrication of cathode in a solid oxide fuel cell: Synthesis of La0.8Sr0.2MnO3 films on YSZ electrolyte pellets

    International Nuclear Information System (INIS)

    Porous La0.8Sr0.2MnO3 (LSMO) films have been prepared by metal organic chemical vapor deposition (MOCVD) technique for solid oxide fuel cell (SOFC) applications. LSMO samples have been deposited on yttria-stabilized zirconia (YSZ) electrolyte pellets. The adopted in situ strategy involves a molten mixture consisting of the La(hfa)3.diglyme, Sr(hfa)2.tetraglyme, and Mn(tmhd)3 [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = bis(2-methoxyethyl)ether; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione] precursors. It has been shown that porous LSMO films can be obtained through an accurate tuning of processing parameters, which affect the nucleation and growth processes. The structural and compositional characterizations of these films, carried out by X-ray diffraction (XRD) and energy dispersive X-ray analysis, point to the formation of a single polycrystalline La0.8Sr0.2MnO3 phase. The field emission scanning electron microscopy (FE-SEM) images confirm the formation of porous films. To evaluate the electrochemical activity of the cathodic films, an investigation by impedance spectroscopy (IS) has been performed.

  18. A novel MOCVD strategy for the fabrication of cathode in a solid oxide fuel cell: Synthesis of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} films on YSZ electrolyte pellets

    Energy Technology Data Exchange (ETDEWEB)

    Toro, Roberta G., E-mail: rgtoro@unict.it [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Fiorito, Davide M.R.; Fragala, Maria E. [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy); Barbucci, Antonio; Carpanese, Maria P. [Dipartimento di Ingegneria Chimica e di Processo, Universita di Genova, and INSTM, UdR P.le Kennedy 1, I-16129 Genova (Italy); Malandrino, Graziella, E-mail: gmalandrino@dipchi.unict.it [Dipartimento di Scienze Chimiche, Universita di Catania, ISMN-CNR and INSTM, UdR V.le Andrea Doria 6, I-95125 Catania (Italy)

    2010-12-01

    Porous La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) films have been prepared by metal organic chemical vapor deposition (MOCVD) technique for solid oxide fuel cell (SOFC) applications. LSMO samples have been deposited on yttria-stabilized zirconia (YSZ) electrolyte pellets. The adopted in situ strategy involves a molten mixture consisting of the La(hfa){sub 3}.diglyme, Sr(hfa){sub 2}.tetraglyme, and Mn(tmhd){sub 3} [Hhfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione; diglyme = bis(2-methoxyethyl)ether; tetraglyme = 2,5,8,11,14-pentaoxapentadecane; Htmhd = 2,2,6,6-tetramethyl-3,5-heptandione] precursors. It has been shown that porous LSMO films can be obtained through an accurate tuning of processing parameters, which affect the nucleation and growth processes. The structural and compositional characterizations of these films, carried out by X-ray diffraction (XRD) and energy dispersive X-ray analysis, point to the formation of a single polycrystalline La{sub 0.8}Sr{sub 0.2}MnO{sub 3} phase. The field emission scanning electron microscopy (FE-SEM) images confirm the formation of porous films. To evaluate the electrochemical activity of the cathodic films, an investigation by impedance spectroscopy (IS) has been performed.

  19. Review Of Rheology Modifiers For Hanford Waste

    International Nuclear Information System (INIS)

    As part of Savannah River National Laboratory (SRNL)'s strategic development scope for the Department of Energy - Office of River Protection (DOE-ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste feed acceptance and product qualification scope, the SRNL has been requested to recommend candidate rheology modifiers to be evaluated to adjust slurry properties in the Hanford Tank Farm. SRNL has performed extensive testing of rheology modifiers for use with Defense Waste Processing Facility (DWPF) simulated melter feed - a high undissolved solids (UDS) mixture of simulated Savannah River Site (SRS) Tank Farm sludge, nitric and formic acids, and glass frit. A much smaller set of evaluations with Hanford simulated waste have also been completed. This report summarizes past work and recommends modifiers for further evaluation with Hanford simulated wastes followed by verification with actual waste samples. Based on the review of available data, a few compounds/systems appear to hold the most promise. For all types of evaluated simulated wastes (caustic Handford tank waste and DWPF processing samples with pH ranging from slightly acidic to slightly caustic), polyacrylic acid had positive impacts on rheology. Citric acid also showed improvement in yield stress on a wide variety of samples. It is recommended that both polyacrylic acid and citric acid be further evaluated as rheology modifiers for Hanford waste. These materials are weak organic acids with the following potential issues: The acidic nature of the modifiers may impact waste pH, if added in very large doses. If pH is significantly reduced by the modifier addition, dissolution of UDS and increased corrosion of tanks, piping, pumps, and other process equipment could occur. Smaller shifts in pH could reduce aluminum solubility, which would be expected to increase the yield stress of the sludge. Therefore, it is expected that use of an acidic modifier would be limited to concentrations that do not appreciably change the pH of the waste; Organics are typically reductants and could impact glass REDOX if not accounted for in the reductant addition calculations; Stability of the modifiers in a caustic, radioactive environment is not known, but some of the modifiers tested were specifically designed to withstand caustic conditions; These acids will add to the total organic carbon content of the wastes. Radiolytic decomposition of the acids could result in organic and hydrogen gas generation. These potential impacts must be addressed in future studies with simulants representative of real waste and finally with tests using actual waste based on the rheology differences seen between SRS simulants and actual waste. The only non-organic modifier evaluated was sodium metasilicate. Further evaluation of this modifier is recommended if a reducing modifier is a concern

  20. Na+ Ion Conducting Hot-pressed Nano Composite Polymer Electrolytes

    OpenAIRE

    Angesh Chandra; Archan Chandra; Kiran Thakurb

    2012-01-01

    Synthesis, characterization and polymeric battery studies of Na+ ion conducting Nano- Composite Polymer Electrolyte (NCPE) membranes: (1-x) [75PEO: 25NaPO3]: x SiO2, where x = 0 - 15 wt. (%), has been reported. NCPE membranes have been casted using a novel hot-press technique in place of the traditional solution cast method. The dispersal of SiO2 in SPE host: (75PEO: 25NaPO3), a conductivity enhancement of an order of magnitude achieved in NCPE film: [93 (75PEO: 25NaPO3): 7 SiO2]. This has be...

  1. Solid lithium-ion electrolyte

    Science.gov (United States)

    Zhang, J.G.; Benson, D.K.; Tracy, C.E.

    1998-02-10

    The present invention relates to the composition of a solid lithium-ion electrolyte based on the Li{sub 2}O--CeO{sub 2}--SiO{sub 2} system having good transparent characteristics and high ion conductivity suitable for uses in lithium batteries, electrochromic devices and other electrochemical applications. 12 figs.

  2. Electrolyte measurement device and measurement procedure

    Science.gov (United States)

    Cooper, Kevin R. (Southern Pines, NC); Scribner, Louie L. (Southern Pines, NC)

    2010-01-26

    A method and apparatus for measuring the through-thickness resistance or conductance of a thin electrolyte is provided. The method and apparatus includes positioning a first source electrode on a first side of an electrolyte to be tested, positioning a second source electrode on a second side of the electrolyte, positioning a first sense electrode on the second side of the electrolyte, and positioning a second sense electrode on the first side of the electrolyte. current is then passed between the first and second source electrodes and the voltage between the first and second sense electrodes is measured.

  3. Fuel cell with electrolyte feed system

    Science.gov (United States)

    Feigenbaum, Haim (Highland Park, NJ)

    1984-01-01

    A fuel cell having a pair of electrodes at the sites of electrochemical reactions of hydrogen and oxygen and a phosphoric acid electrolyte provided with an electrolyte supporting structure in the form of a laminated matrix assembly disposed between the electrodes. The matrix assembly is formed of a central layer disposed between two outer layers, each being permeable to the flow of the electrolyte. The central layer is provided with relatively large pores while the outer layers are provided with relatively small pores. An external reservoir supplies electrolyte via a feed means to the central layer to compensate for changes in electrolyte volume in the matrix assembly during the operation of fuel cell.

  4. New trivalent imidazole-derived salt for lithium-ion cell electrolyte

    Science.gov (United States)

    Trzeciak, Tomasz; Niedzicki, Leszek; Groszek, Grazyna; Wieczorek, Piotr; Marcinek, Marek; Wieczorek, Wladyslaw

    2014-04-01

    Lithium-ion cells utilize almost exclusively monovalent lithium salts as main electrolyte component. Apart from scarce works on sulfonyl imide derivatives, even in terms of basic parameters little is known about multivalent lithium salts' behavior in electrolytes. Here we present the new trivalent lithium salt dedicated to electrolytes for lithium-ion cells. Trilithium 2,2?,2?-tris(trifluoromethyl)benzotris(imidazolate) (Li3BTI) synthesis and its performance in PC and EC:DMC solutions is described in this paper. The structure and stability of this new lithium salt was fully characterized by NMR and Raman techniques as well as thermal methods. Basic electrochemical parameters of electrolytes based on this salt were done by linear sweep voltammetry, lithium cation transference number and conductivity measurements. The salt was designed specifically to manifest extraordinarily high lithium cation transference number (0.73 in EC:DMC 1:1 ratio mixture). However this new salt exhibits also thermal stability of 160 °C and electrochemical stability up to 4.5 V vs Li, as well as conductivities of the 1 mS cm-1 order of magnitude in liquid electrolytes. Promising compatibility results of the obtained electrolyte against Si/C composite anodes are also reported in this paper.

  5. Iron-containing coatings obtained by microplasma method on aluminum with usage of homogeneous electrolytes

    International Nuclear Information System (INIS)

    The microplasma synthesis method of multicomponent oxide coatings including iron oxide on an aluminum alloy surface has been studied. The homogeneous electrolytes containing iron complexes with Edta4- under pH 9-10 have been used. The dynamics reducing the pH of the electrolyte during formation process have been studied. The content of iron in the coatings has been measured spectrophotometricaly. Morphlogy and phase composition of the coatings have been studied by the scanning electron microscopy and X-ray powder diffraction.

  6. Granular nanocrystalline zirconia electrolyte layers deposited on porous SOFC cathode substrates

    International Nuclear Information System (INIS)

    Thin granular yttria-stabilized zirconia (YSZ) electrolyte layers were prepared by chemical vapor synthesis and deposition (CVD/CVS) on a porous substoichiometric lanthanum-strontium-manganite (ULSM) solid oxide fuel cell cathode substrate. The substrate porosity was optimized with a screen printed fine porous buffer layer. Structural analysis by scanning electron microscopy showed a homogeneous, granular nanocrystalline layer with a microstructure that was controlled via reactor settings. The CVD/CVS gas-phase process enabled the deposition of crack-free granular YSZ films on porous ULSM substrates. The electrolyte layers characterized with impedance spectroscopy exhibited enhanced grain boundary conductivity.

  7. Iron-containing coatings obtained by microplasma method on aluminum with usage of homogeneous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Rogov, A.B., E-mail: alex-lab@bk.ru [Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Terleeva, O.P., E-mail: oterleeva@yandex.ru [Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Mironov, I.V., E-mail: imir@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation); Slonova, A.I., E-mail: antaris@ngs.ru [Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Ave, Novosibirsk, 630090 (Russian Federation)

    2012-01-15

    The microplasma synthesis method of multicomponent oxide coatings including iron oxide on an aluminum alloy surface has been studied. The homogeneous electrolytes containing iron complexes with Edta{sup 4-} under pH 9-10 have been used. The dynamics reducing the pH of the electrolyte during formation process have been studied. The content of iron in the coatings has been measured spectrophotometricaly. Morphlogy and phase composition of the coatings have been studied by the scanning electron microscopy and X-ray powder diffraction.

  8. Rheological behaviour of metallocene polypropylenes prepared by reactive extrusion process.

    Czech Academy of Sciences Publication Activity Database

    Pivokonský, Radek; Filip, Petr; Zatloukal, M.; Tzoganakis, C.

    Lisbon : European Society of Rheology, 2012. s. 394. [International Congress on Rheology /16./. 05.08.2012-10.08.2012, Lisbon] R&D Projects: GA ?R GA103/09/2066 Keywords : metallocene polypropylene * constitutive modelling * differential models Subject RIV: BK - Fluid Dynamics

  9. Rheological Properties of Gamma Irradiated Arrowroot (Pueraria thunbergina. B) Starch

    International Nuclear Information System (INIS)

    Rheological properties of gamma-irradiated arrowroot starch was examined to utilize as fundamental research data for processing. Irradiated arrowroot starch solutions (3, 4, 5, 6%) were gelatinized at 95? for 40 min, and its flow properties measured using rheometer at 30? and 10 to 200 rpm rotation rate. Rheological parameters of irradiated arrowroot starch gelatinized solution were calculated using Herschel-Bulkley equation

  10. SOME RHEOLOGICAL PROPERTIES OF AQUEOUS PEANUT FLOUR DISPERSIONS

    Science.gov (United States)

    The rheological behaviors of aqueous peanut flour dispersions were characterized across a range of conditions, including controlled heating and cooling rates under both large and small-strain deformations. Fat content of the dry flours influenced rheological characteristics, as dispersions of highe...

  11. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Chuanping Li

    2004-12-19

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the {sup 17}O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles' surfaces in the aqueous suspension. The viscosity of the suspension increases dramatically when the solid volume fraction exceeds 30 vol.%. The overlap of physically adsorbed water layers at this level causes the sharp increase in viscosity. Fructose molecules can weaken the interactions between the particle surfaces and water molecules, as a consequence, they release some bound water layers from the surfaces to the bulk medium. It is believed that fraction of the water that is bound by the solid surface is reduced hence becoming available for flow. The oxygen-17 relaxation time decreased with the increase of particle volume fractions in the suspension. Fructose addition increased the overall water mobility in the suspension. Only part of the alumina particle surfaces was covered with fructose molecules. This adsorption of fructose molecules on the particle surfaces increased the pH of the suspension with a concomitant decrease in {zeta}-potential of the alumina nanoparticles. The interactions between the nanometric alumina particles in water to a large extent can be explained by the DLVO theory. However, the interactions between particles in fructose solutions cannot be well described by the DLVO theory. The interaction forces (magnitude and range) as well as adhesive force and surface tension between nanometric alumina particles were decreased with the fructose concentration.

  12. Melt rheology and its applications in the plastics industry

    CERN Document Server

    Dealy, John M

    2013-01-01

    This is the second edition of Melt Rheology and its Role in Plastics Processing, although the title has changed to reflect its broadened scope. Advances in the recent years in rheometer technology and polymer science have greatly enhanced the usefulness of rheology in the plastics industry. It is now possible to design polymers having specific molecular structures and to predict the flow properties of melts having those structures. In addition, rheological properties now provide more precise information about molecular structure. This book provides all the information that is needed for the intelligent application of rheology in the development of new polymers, the determination of molecular structure and the correlation of processability with laboratory test data. Theory and equations are limited to what is essential for the use of rheology in the characterization of polymers, the development of new plastics materials and the prediction of plastics processing behavior. The emphasis is on information that wil...

  13. Rheological model and flow equation for elasto-viscoplastic mixtures ????????????? ?????? ? ????????? ??????? ??????-?????-?????????? ?????

    Directory of Open Access Journals (Sweden)

    Luk’yanov Nikolai Andreevich

    2013-05-01

    Full Text Available Advanced building materials technologies widely employ polymers. Viscoelastic and viscoplastic mixtures are used in the manufacturing of building materials and finishing products. Rheology studies deformation and flow patterns of different bodies.Markus Reiner developed mathematical formulations for rheological flows of viscous and plastic materials, processes of deformation of different bodies, behaviour of materials exposed to strain loads.A rheological flow of any material depends on deformation. Integrated analysis of linear deformations and strain is used to identify a relative change in the volume of an elasto-viscoplastic body. The flow of materials depends on their physicochemical properties. The flow of an elastic-viscous-plastic mixture in channels demonstrates its viscoelastic properties. Rheological equation of Oldroyd is used to relate strain to speed of displacement and the time of relaxation. The flow of polymeric materials is examined using Bingham’s rheological model.?????????? ??????? ????????? ?????????? ??????-?????-??????????? ?????????. ?????????? ???????????????? ????????? ???????? ? ????????????? ? ?????? ??????? ??????????, ??????? ?????????? ???????? ??????????? ????????? ????. ???????? ??????????? ??? ??????????? ?????????????? ????????? ?????? ??????-?????-????????????? ???? ??? ???????? ??????????. ?????????? ??????????? ?????????? ???????? ?????????????? ???????? ???? ?? ??????? ?????????? ??????????. ????????? ??????-?????-?????????? ????? ??????????? ?? ??????? ????????????? ?????? ???? ???????.

  14. RHEOLOGICAL BEHAVIOR STUDY OF HIDRAULIC OIL

    Directory of Open Access Journals (Sweden)

    IOANA STANCIU

    2012-03-01

    Full Text Available Rheological behavior of this article presents hydraulic oil. Dynamic viscosity of hydraulic oil was determined at temperatures between 400C -900C and shear rates ranging from 3.3-120s^-1. Temperature of hydraulic oil at 313K has a Bingham fluid behavior with correlation coefficient value close to one. Between 323 and 333K temperature behavior of oil has a Casson fluid and the temperature range 343 to363K oil and behaves like an Ostwald-de Waele fluid.

  15. Rheological properties of polypropylene/ attapulgite nanocomposite.

    Science.gov (United States)

    Zhang, Xiaohu; Guo, Jinshan; Zhang, Liji; Yang, Shiyuan; Zhang, Jie; He, Yutao

    2010-08-01

    The rheological properties of nanocomposites consisting of organic modified attapulgite and polypropylene are investigated. The morphology of the nanocomposites was studied with scanning electron microscopy and X-ray diffraction. Linear dynamic viscoelasticity and steady state flow step of the nanocomposites are presented. For the nanocomposites, the deviation from linear behavior occurs earlier than pure polypropylene at the strain. The storage moduli, loss moduli and dynamic viscosities of the nanocomposites increase monotonically with organoclay concentration. However, the nanocomposites show greater shear thinning tendency than pure polypropylene because of the orientation of the organoclay fibers. Therefore, the nanocomposites have higher moduli but better processibility compared with pure polypropylene. PMID:21125882

  16. Controlling Suspension Rheology with Novel Oligomeric Dispersants

    Science.gov (United States)

    Howe, Andrew M.; Wear, Trevor J.; Hone, John H. E.; Pitt, Alan R.

    2008-07-01

    Suspensions of cationic boehmite (Catapal 200) exhibit "challenging" rheological properties—irreversible shear thickening to viscoelastic or jammed states, dependent on the shear history. A range of commercially available dispersants—either small molecules or polymers—were able to reduce viscosity but not able to eliminate shear-induced jamming. We designed and synthesized oligomeric functional anchor-buoy dispersants, with a small, strongly adsorbing carboxylic acid based anchor and a simple, inexpensive water-soluble oligomeric buoy (typically 25-30 acrylamide units). In the presence of the dispersant, the viscosity was reduced and irreversible shear thickening eliminated.

  17. Rheology and Gelling Behavior of Boehmite Sols

    OpenAIRE

    Eng-Seng Chan; Pogaku Ravindra; Chu Chi Ming; Islam, M. A.

    2011-01-01

    Rheological studies of boehmite sols based on pH was (1) to study the nature of flow properties of the boehmite sols and (2) to identify the sol-gel transition of boehmite sols with the change of pH of the liquid. It is evident that the shear rate and viscosity of the liquid exhibit a pseudoplastic (shear thinning) flow behavior for all pH level. The transformation of sol-gel at low pH probably due to the hydrogen bond between the layers of the boehmite structure. The temperature has an appre...

  18. Electrolytic production of neodymium metal from a molten chloride electrolyte

    International Nuclear Information System (INIS)

    This paper reports that the U.S. Bureau of Mines conducted experiments on electrowinning of neodymium metal by using a molten-metal cathode at 650 degrees C and an electrolyte of 50 mol pet NdCl, (neodymium chloride) and 50 mol pet KCl (potassium chloride). The molten-metal cathodes were alloys of magnesium and zinc or magnesium and cadmium. Current efficiencies were 90 pct with a Mg-Zn cathode and 80 pct with a Mg-Cd cathode. The Mg-Cd cathode was easily separated from the electrolyte. In contrast, the Mg-Zn cathode tended to mix with the electrolyte, making separation difficult. The cathode metals were separated from the neodymium by distillation at 1,100 degrees C under a vacuum of 10-4 torr. Neodymium metal of 99.9 + purity was recovered from the Mg-Cd alloy cathode after 30 min distillation time. The neodymium recovered from the Mg-Zn system contained almost 2 pct Zn after vacuum distillation. Continuous operation using the Mg-Cd alloy cathode was demonstrated

  19. Solution rheology of polyelectrolytes and polyelectrolyte-surfactant systems

    Science.gov (United States)

    Plucktaveesak, Nopparat

    The fundamental understanding of polyelectrolytes in aqueous solutions is an important branch of polymer research. In this work, the rheological properties of polyelectrolytes and polyelectrolyte/surfactant systems are studied. Various synthetic poly electrolytes are chosen with varied hydrophobicity. We discuss the effects of adding various surfactants to aqueous solutions of poly(ethylene oxide)-b-poly(propylene oxide)- b-polyethylene oxide)-g-poly(acrylic acid) (PEO-PPO-PAA) in the first chapter. Thermogelation in aqueous solutions of PEO-PPO-PAA is due to micellization caused by aggregation of poly(propylene oxide) (PPO) blocks resulting from temperature-induced dehydration of PPO. When nonionic surfactants with hydrophilic-lipophilic balance (HLB) parameter exceeding 11 or Cn alkylsulfates; n-octyl (C8), n-decyl (C 10) and n-dodecyl (C12) sulfates are added, the gelation threshold temperature (Tgel) of 1.0wt% PEO-PPO-PAA in aqueous solutions increases. In contrast, when nonionic surfactants with HLB below 11 are added, the gelation temperature decreases. On the other hand, alkylsulfates with n = 16 or 18 and poly(ethylene oxide) (PEO) do not affect the Tgel. The results imply that both hydrophobicity and tail length of the added surfactant play important roles in the interaction of PEO-PPO-PAA micelles and the surfactant. In the second chapter, the solution behavior of alternating copolymers of maleic acid and hydrophobic monomer is studied. The alternating structure of monomers with two-carboxylic groups and hydrophobic monomers make these copolymers unique. Under appropriate conditions, these carboxylic groups dissociate leaving charges on the chain. The potentiometric titrations of copolymer solutions with added CaCl2 reveal two distinct dissociation processes corresponding to the dissociation of the two adjacent carboxylic acids. The viscosity data as a function of polymer concentration of poly(isobutylene-alt-sodium maleate), poly(styrene-alt-sodium maleate) and poly(diisobutylene- alt-sodium maleate) show the polyelectrolyte behavior as predicted. However, the viscosity as a function of concentration of sodium maleate based copolymers with 1-alkenes; 1-octene (C8), 1-decene (C10), 1-dodecene (C12) and 1-hexene (C14) exhibit an abnormal scaling power, which might be caused by aggregation of the alkene tails to form micelles. In the last chapter, we report the rheological properties of aqueous solutions of poly(acrylic acid) and oppositely charged surfactant, dodecyl trimethylammonium bromide (C12TAB). The solution viscosity decreases as surfactant is added, partly because the polyelectrolyte wraps around the surface of the spherical surfactant micelles, shortening the effective chain length. The effects of polymer molecular weight, polymer concentration, and polymer charge have been studied with no added salt. The results are compared with the predictions of a simple model based on the scaling theory for the viscosity of dilute and unentangled semidilute polyelectrolyte solutions in good solvent. This model takes into account two effects of added surfactant. The effective chain length of the polyelectrolyte is shortened when a significant fraction of the chain wraps around micelles. Another effect is the change of solution ionic strength resulting from surfactant addition that further lowers the viscosity. The parameters used in this model are independently determined, allowing the model to make a quantitative prediction of solution viscosity with no adjustable parameters. The model is also applied to predict the decrease in viscosity of various polyelectrolyte/oppositely charged surfactant systems reported in literature. The results are in good agreement with experimental data, proving that our model applies to all polyelectrolytes mixed with oppositely charged surfactants that form spherical micelles.

  20. New Polymer Electrolyte Cell Systems

    Science.gov (United States)

    Smyrl, William H.; Owens, Boone B.; Mann, Kent; Pappenfus, T.; Henderson, W.

    2004-01-01

    PAPERS PUBLISHED: 1. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Complexes of Lithium Imide Salts with Tetraglyme and Their Polyelectrolyte Composite Materials. Journal of the Electrochemical Society (2004), 15 1 (2), A209-A2 15. 2. Pappenfus, Ted M.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; Smyrl, William H. Ionic-liquidlpolymer electrolyte composite materials for electrochemical device applications. Polymeric Materials Science and Engineering (2003), 88 302. 3. Pappenfus, Ted R.; Henderson, Wesley A.; Owens, Boone B.; Mann, Kent R.; and Smyrl, William H. Ionic Conductivity of a poly(vinylpyridinium)/Silver Iodide Solid Polymer Electrolyte System. Solid State Ionics (in press 2004). 4. Pappenfus Ted M.; Mann, Kent R; Smyrl, William H. Polyelectrolyte Composite Materials with LiPFs and Tetraglyme. Electrochemical and Solid State Letters, (2004), 7(8), A254.

  1. Relaxation phenomena in cryogenic electrolytes

    Science.gov (United States)

    Shikin, V.; Chikina, I.; Nazin, S.

    2013-06-01

    Proposed is a scenario for the development of observed relaxation phenomena in a cryogenic electrolyte with the structure of "liquid hydrogen + injected ions." Ions of one sign are generated in the bulk of liquid hydrogen in the presence of external field E? by a stationary radioactive source of ± ions at the bottom of a vessel. After accumulation near the free surface of the liquid with a finite density ns the ions can break its stability producing a pulse of ion current to the collector located above the liquid surface. The outlined process is periodically repeated. Its period contains information on the ion mobility and, which is most interesting, on dissociation (association) processes occurring in a system of charged particles placed in an external field. The cryogenic problem is a good model for dissociation in the presence of external field occurring in normal electrolytes without any external ion sources.

  2. Rheological Investigation on the Effect of Shear and Time Dependent Behavior of Waxy Crude Oil

    OpenAIRE

    Japper-Jaafar A.; Bhaskoro P.; Sariman M.Z.; Rozlee R.

    2014-01-01

    Rheological measurements are essential in transporting crude oil, especially for waxy crude oil. Several rheological measurements have been conducted to determine various rheological properties of waxy crude oil including the viscosity, yield strength, wax appearance temperature (WAT), wax disappearance temperature (WDT), storage modulus and loss modulus, amongst others, by using controlled stress rheometers. However, a procedure to determine the correct parameters for rheological measurement...

  3. Rheology and microstructure of concentrated suspensions

    International Nuclear Information System (INIS)

    This paper gives an overview of some of the experiments currently underway to study the coupling of the microstructure and rheology of concentrated suspensions. Nuclear magnetic resonance imaging, real-time x-ray radiography, and refractive index matching allow the viewing of particles in concentrated suspensions. Both shear flow experiments and falling ball rheometry are reviewed. In the slow flow of these suspensions of large, hard, particles in a viscous Newtonian fluid, colloidal forces are negligible and hydrodynamic forces dominate. Large local concentration changes are shown to occur rapidly in suspensions of uniform spheres subjected to flow between concentric rotating cylinders. Suspensions of spheres with a bimodal size distribution not only show similar phenomena, but also exhibit particle separation according to size. In addition, the large particles in the bimodal suspension migrate into ordered, concentric, cylindrical sheets, parallel to the axis of the cylinders. These sheets of particles rotate relative to each other. The particle migration and structure formation induced by this inhomogeneous shear flow is believed to be responsible for torque reductions and other anomalous behavior witnessed during the rheological testing of concentrated suspensions reported in the literature. Thus, suspensions may not always be characterized by a viscosity that is a scalar material property

  4. Rheological characterization of Poloxamer 407 nimesulide gels

    Directory of Open Access Journals (Sweden)

    M. N. Freitas

    2009-01-01

    Full Text Available The thermal gelling property of Poloxamer 407- nimesulide gels was characterized by rheological studies. Nimesulide, a local anti-inflammatory and anesthetic drug used for the treatment of acute and chronic pain, has a short duration of action and a long-acting single-dose injection would be of clinical importance. Thus a poloxamer 407 gel applied intramuscularly could prolong the release and action of nimesulide. In this study, aqueous gels with nimesulide, containing three different concentrations of Poloxamer 407, were prepared. Viscosity measurements were performed by rheologial studies to obtain the optimal sol-gel transition temperature . Poloxamer 407 gels are pseudoplastic and viscoelastic materials, which have an elastic modulus (G', characteristic of the solid, and a viscous modulus (G'', characteristic of the liquid material. Moreover, being pseudoplastic gels, when they are deformed by shearing, their viscosity decreases. Increase of the polymer concentration increased the viscosity of the gels, which could affect the releasing process of nimesulide. Furthermore, the presence of nimesulide led to a lowering of the sol-gel transition temperature. Keywords: Poloxamer 407 gels; nimesulide; rheological characterization; viscosity; sol-gel transition temperature.

  5. Chinese Lithosphere Rheology and Geodynamic Modeling

    Science.gov (United States)

    Shi, Y.; Zhang, H.; Cao, J.; Zhang, C.; Sun, L.

    2009-04-01

    Rock rheology is of critical importance to affect lithosphere deformation. Laboratory experiments show that viscosity of rocks strongly depends on temperature. Therefore, reliable estimation of geotherm is the first step for understanding lithospheric rheology. Deduction of geotherm from surface heat flow and thermal conductivity has been applied widely. However, error in temperature estimated this way increases with depth. In our study, we use seismic tomographic data to estimate mantle temperature ranges 50 to 200 km depth, and get a better constraint of temperature at depth. We use new petrology data to construct the crustal structure and viscosity model of China. To test the validity of extrapolation of flow law of rock from laboratory sample size and higher strain rate to large field scale and much lower strain rate, we use post seismic GPS deformation observation to invert lower crust viscosity for comparison. We then apply the viscosity model to simulate a number of tectonic problems in China, such as GPS velocity clockwise rotation around the eastern syntax of the Himalaya and uplift of the Tibetan plateau, decoupling of stress indicated by compression in the upper crust and extensional normal fault earthquake in the upper mantle in Taiwan southwest coast, and different stress accumulation rate in the upper and lower crust in Longmenshan area, Sichuan Province to estimate the reccurence time of large earthquakes.

  6. Thermal and rheological properties of breadfruit starch.

    Science.gov (United States)

    Wang, Xueyu; Chen, Ling; Li, Xiaoxi; Xie, Fengwei; Liu, Hongshen; Yu, Long

    2011-01-01

    The thermal and rheological properties of breadfruit starch were studied using DSC and 2 different rheometers. It was found that the gelatinization temperature of starch with excess moisture content (>70%) was at approximately 75 °C. A new endotherm was detected at about 173 °C when the moisture content was lower than required for full gelatinization of the starch. A detailed examination revealed that this endotherm represented the melting of amylose-lipid complexes. Breadfruit starch paste exhibited shear-thinning fluid characteristics, and good thermal and pH stability. The setback viscosity of the breadfruit starch was lower than that of potato and corn starches. The rheological properties of the breadfruit starch paste was well described by the Herschel-Bulkley model at a shear rate of 0 to 100 s(-1), where R(2) is greater than 0.95, and it behaved like a yield-pseudoplastic fluid. Both the storage modulus and loss modulus of the paste initially increased sharply, then dropped after reaching the gelatinization peak. Breadfruit starch gel showed both flexibility and viscosity. Suspension with 6% starch content exhibited very weak gel rigidity; however, this increased significantly at starch contents above 20%. PMID:21535676

  7. Improving feed slurry rheology by colloidal techniques

    International Nuclear Information System (INIS)

    Pacific Northwest Laboratory (PSN) has investigated three colloidal techniques in the laboratory to improve the sedimentation and flowability of Hanford simulated (nonradioactive) current acid waste (CAW) melter feed slurry: polymer-induced bridging flocculation; manipulating glass former (raw SiO2 or frit) particle size; and alteration of nitric acid content. All three methods proved successful in improving the rheology of the simulated CAW feed. This initially had exhibited nearly worst-case flow and clogging properties, but was transformed into a flowable, resuspendable (nonclogging) feed. While each has advantages and disadvantages, the following three specific alternatives proved successful: addition of a polyelectrolyte in 2000 ppM concentration to feed slurry; substitution of a 49 wt % SiO2 colloidal suspension (approx. 10-micron particle size) for the -325 mesh (less than or equal to 44-micron particle size) raw-chemical SiO2; and increase of nitric acid content from the reference 1.06 M to optimum 1.35 M. The first method, polymer-induced bridging flocculation, results in a high sediment volume, nonclogging CAW feed. The second method, involving the use of colloidal silica particles results in a nonsedimenting feed that when left unagitated forms a gel. The third method, increase in feed acidity, results in a highly resuspendable (nonclogging) melter feed. Further research is therefore required to determine which of the three alternatives is the preferred method of achieving rheological control of CAW melter feeds

  8. Rheology of asphaltene-toluene/water interfaces.

    Science.gov (United States)

    Sztukowski, Danuta M; Yarranton, Harvey W

    2005-12-01

    The stability of water-in-crude oil emulsions is frequently attributed to a rigid asphaltene film at the water/oil interface. The rheological properties of these films and their relationship to emulsion stability are ill defined. In this study, the interfacial tension, elastic modulus, and viscous modulus were measured using a drop shape analyzer for model oils consisting of asphaltenes dissolved in toluene for concentrations varying from 0.002 to 20 kg/m(3). The effects of oscillation frequency, asphaltene concentration, and interface aging time were examined. The films exhibited viscoelastic behavior. The total modulus increased as the interface aged at all asphaltene concentrations. An attempt was made to model the rheology for the full range of asphaltene concentration. The instantaneous elasticity was modeled with a surface equation of state (SEOS), and the elastic and viscous moduli, with the Lucassen-van den Tempel (LVDT) model. It was found that only the early-time data could be modeled using the SEOS-LVDT approach; that is, the instantaneous, elastic, and viscous moduli of interfaces aged for at most 10 minutes. At longer interface aging times, the SEOS-LVDT approach was invalid, likely because of irreversible adsorption of asphaltenes on the interface and the formation of a network structure. PMID:16316096

  9. Swollen and collapsed lyotropic lamellar rheology.

    Science.gov (United States)

    Youssry, Mohamed; Coppola, Luigi; Nicotera, Isabella; Morán, Carmen

    2008-05-15

    We have investigated linear rheological properties and the structure-flow relationship of the swollen (Lam(1)) and collapsed (Lam(2)) lamellar phases, formed on didodecyldimethylammonium bromide (DDAB)/lecithin/water ternary system at 25 degrees C. Both lamellar phases behaved like Bingham fluids and showed remarkable yield stresses. At rest the Lam(1) phase, which is characterized by densely packed vesicles whose sizes increase as the water content decreases in accordance to evolution of (2)H NMR spectral profiles of D(2)O, resulted in a strong elastic gel-like response. On the other hand, the Lam(2) phase, formed at high surfactant concentrations, showed a weak-gel viscoelasticity and (2)H NMR spectral patterns which are typical of planar bilayered structures. The increase of the quadrupole splitting as the water content decreases was assumed as a strong evidence of size increasing of the lamellar domains. We have demonstrated that by using dynamic rheology and the derived relaxation time spectra, along with (2)H NMR spectra of D(2)O, it is possible to differentiate between equilibrium lamellar structures occurring in a broad interval of total surfactant concentration. In addition, a shear-thickening regime, observed at intermediate shear-rate values, highlighted the onset of out-equilibrium lamellar structures which were present both on Lam(1) and Lam(2) phases. PMID:18342326

  10. Plasma electrolytic oxidation of tantalum

    OpenAIRE

    Petkovi? Marija; Stojadinovi? Stevan; Vasili? Rastko; Bel?a Ivan; Kasalica Be?ko; Zekovi? Ljubiša

    2012-01-01

    This paper is a review of our research on the plasma electrolytic oxidation (PEO) process of tantalum in 12-tungstosilicic acid. For the characterization of microdischarges during PEO, real-time imaging and optical emission spectroscopy (OES) were used. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDS and XRD. Oxide coating morphology is strongly dependent on PEO time. The elemental components of PEO coatings are Ta, O, Si and W....

  11. Plasma electrolytic oxidation of metals

    OpenAIRE

    Stojadinovi? Stevan

    2013-01-01

    In this lecture results of the investigation of plasma electrolytic oxidation (PEO) process on some metals (aluminum, titanium, tantalum, magnesium, and zirconium) were presented. Whole process involves anodizing metals above the dielectric breakdown voltage where numerous micro-discharges are generated continuously over the coating surface. For the characterization of PEO process optical emission spectroscopy and real-time imaging were used. These investigations enabled the determinati...

  12. Surface interactions in simple electrolytes

    OpenAIRE

    Kjellander, Roland; Marc?elja, Stjepan

    1988-01-01

    We present some new results and concepts which have emerged from the rigorous application of the integral equation methods of liquid state physics to the problem of inhomogeneous ionic fluids in the vicinity of charged surfaces. The report summarizes our recent results for surface interactions in mono- and divalent electrolytes obtained using the anisotropic Hypemetted Chain approximation. Compared to the Poisson-Boltzmann mean-field theory the major differences are an attractive contribution...

  13. Solid electrolyte oxygen regeneration system

    Science.gov (United States)

    Shumar, J. W.; See, G. G.; Schubert, F. H.; Powell, J. D.

    1976-01-01

    A program to design, develop, fabricate and assemble a one-man, self-contained, solid electrolyte oxygen regeneration system (SX-1) incorporating solid electrolyte electrolyzer drums was completed. The SX-1 is a preprototype engineering model designed to produce 0.952 kg (2.1 lb)/day of breathable oxygen (O2) from the electrolysis of metabolic carbon dioxide (CO2) and water vapor. The CO2 supply rate was established based on the metabolic CO2 generation rate for one man of 0.998 kg (2.2 lb)/day. The water supply rate (0.254 kg (0.56 lb)/day) was designed to be sufficient to make up the difference between the 0.952 kg (2.1 lb)/day O2 generation specification and the O2 available through CO2 electrolysis, 0.726 kg (1.6 lb)/day. The SX-1 was successfully designed, fabricated and assembled. Design verification tests (DVT) or the CO Disproportionators, H2 separators, control instrumentation, monitor instrumentation, water feed mechanism were successfully completed. The erratic occurrence of electrolyzer drum leakage prevented the completion of the CO2 electrolyzer module and water electrolyzer module DVT's and also prevented the performance of SX-1 integrated testing. Further development work is required to improve the solid electrolyte cell high temperature seals.

  14. Review Of Rheology Modifiers For Hanford Waste

    Energy Technology Data Exchange (ETDEWEB)

    Pareizs, J. M.

    2013-09-30

    As part of Savannah River National Laboratory (SRNL)'s strategic development scope for the Department of Energy - Office of River Protection (DOE-ORP) Hanford Tank Waste Treatment and Immobilization Plant (WTP) waste feed acceptance and product qualification scope, the SRNL has been requested to recommend candidate rheology modifiers to be evaluated to adjust slurry properties in the Hanford Tank Farm. SRNL has performed extensive testing of rheology modifiers for use with Defense Waste Processing Facility (DWPF) simulated melter feed - a high undissolved solids (UDS) mixture of simulated Savannah River Site (SRS) Tank Farm sludge, nitric and formic acids, and glass frit. A much smaller set of evaluations with Hanford simulated waste have also been completed. This report summarizes past work and recommends modifiers for further evaluation with Hanford simulated wastes followed by verification with actual waste samples. Based on the review of available data, a few compounds/systems appear to hold the most promise. For all types of evaluated simulated wastes (caustic Handford tank waste and DWPF processing samples with pH ranging from slightly acidic to slightly caustic), polyacrylic acid had positive impacts on rheology. Citric acid also showed improvement in yield stress on a wide variety of samples. It is recommended that both polyacrylic acid and citric acid be further evaluated as rheology modifiers for Hanford waste. These materials are weak organic acids with the following potential issues: The acidic nature of the modifiers may impact waste pH, if added in very large doses. If pH is significantly reduced by the modifier addition, dissolution of UDS and increased corrosion of tanks, piping, pumps, and other process equipment could occur. Smaller shifts in pH could reduce aluminum solubility, which would be expected to increase the yield stress of the sludge. Therefore, it is expected that use of an acidic modifier would be limited to concentrations that do not appreciably change the pH of the waste; Organics are typically reductants and could impact glass REDOX if not accounted for in the reductant addition calculations; Stability of the modifiers in a caustic, radioactive environment is not known, but some of the modifiers tested were specifically designed to withstand caustic conditions; These acids will add to the total organic carbon content of the wastes. Radiolytic decomposition of the acids could result in organic and hydrogen gas generation. These potential impacts must be addressed in future studies with simulants representative of real waste and finally with tests using actual waste based on the rheology differences seen between SRS simulants and actual waste. The only non-organic modifier evaluated was sodium metasilicate. Further evaluation of this modifier is recommended if a reducing modifier is a concern.

  15. The Rheological Properties of Aluminum Borate Whisker Filled Resins.

    Science.gov (United States)

    Kambara, Hajime

    The purpose of this work is to investigate the rheological properties of epoxy resin filled with high concentrations of aluminum borate (9Al_2 O_3-2B_2O _3) whiskers. Rheological measurements are performed with parallel plate rheometer. The rheology exhibits nonlinear viscoelasticity from low strain region through entire range studied. The presence of an effective network of whiskers comprising an internal structure is proposed. The thesis is consisted of three parts. The first is the conformation of the internal structure of whisker network and its deformation. By applying the external shearing force, both steady and dynamic, to the whisker suspension, the responses of the rheological properties have been monitored. The data is interpreted and quantitative analyses are carried out. The second is the reformation behavior of the deformed internal structure. No major study is done about reformation behavior of the internal structure of short fiber suspension. In this part, the condition of deformed internal structure is analyzed and then reformation behavior under zero shearing force is studied. The third is the phenomenological similarity of rheological properties between the whisker suspension and the liquid crystal polymer. This phenomenon is observed for only whisker suspension not for ordinary glass fiber suspension due to whiskers' small dimension. The fourth is the investigation about effects of whisker/whisker interaction and whisker/resin interaction on the rheological behavior. From these studies, the change of rheological status upon the external force such as processing procedure has been clarified.

  16. Synthesis and characterization of low cost magnetorheological (MR) fluids

    Science.gov (United States)

    Sukhwani, V. K.; Hirani, H.

    2007-04-01

    Magnetorheological fluids have great potential for engineering applications due to their variable rheological behavior. These fluids find applications in dampers, brakes, shock absorbers, and engine mounts. However their relatively high cost (approximately US600 per liter) limits their wide usage. Most commonly used magnetic material "Carbonyl iron" cost more than 90% of the MR fluid cost. Therefore for commercial viability of these fluids there is need of alternative economical magnetic material. In the present work synthesis of MR fluid has been attempted with objective to produce low cost MR fluid with high sedimentation stability and greater yield stress. In order to reduce the cost, economical electrolytic Iron powder (US 10 per Kg) has been used. Iron powder of relatively larger size (300 Mesh) has been ball milled to reduce their size to few microns (1 to 10 microns). Three different compositions have been prepared and compared for MR effect produced and stability. All have same base fluid (Synthetic oil) and same magnetic phase i.e. Iron particles but they have different additives. First preparation involves organic additives Polydimethylsiloxane (PDMS) and Stearic acid. Other two preparations involve use of two environmental friendly low-priced green additives guar gum (US 2 per Kg) and xanthan gum (US 12 per Kg) respectively. Magnetic properties of Iron particles have been measured by Vibrating Sample Magnetometer (VSM). Morphology of Iron particles and additives guar gum and xanthan gum has been examined by Scanning Electron Microscopy (SEM) and Particles Size Distribution (PSD) has been determined using Particle size analyzer. Microscopic images of particles, MH plots and stability of synthesized MR fluids have been reported. The prepared low cost MR fluids showed promising performance and can be effectively used for engineering applications demanding controllability in operations.

  17. Development of magneto-rheological fluid composites with rigidification characteristics

    International Nuclear Information System (INIS)

    Magnetic and magneto-rheological materials have been widely used in many engineering applications. The smart magnetic materials addressed in this study consist of magnetically activated composites made from a core layer of a carrier-material-like fabric, sponge and silicone in combination with small magnetizable ferrous particles suspended in a magneto-rheological fluid. Composite materials that contain magnetic and magneto-rheological ingredients are presently becoming very popular in shape and structure control solutions in a variety of engineering applications. The magneto-rheological response in smart materials allows for the real-time adaptation of material properties. Adequately designed magneto-rheological or magnetic composites are required to perform under different load conditions and provide some rigidification in a sample or a structure. Three different composites are developed in this study including: magneto-rheological fabric composites (MR/FC), magnetic elastomers (M-elastomers) and magneto-rheological sponge composites (MR/SC). The experimental set-up, including custom-made hardware, software and data acquisition system, is designed to conduct experiments used to quantify the material response in shear, tension and compression. The experimental results show a close correlation between the amount of magneto-rheological material present in the specimen and the final displacements in the samples. The resistance to the shear, compressive or tensile forceso the shear, compressive or tensile forces increases in the samples with the higher concentration of ferrous particles when subjected to a magnetic field. An increased intensity of the magnetic field allows for a stronger magneto-rheological effect and more stable formation of the ferrous chains inside the composites

  18. Nanocomposite polymer electrolyte for rechargeable magnesium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Yuyan; Rajput, Nav Nidhi; Hu, Jian Z.; Hu, Mary Y.; Liu, Tianbiao L.; Wei, Zhehao; Gu, Meng; Deng, Xuchu; Xu, Suochang; Han, Kee Sung; Wang, Jiulin; Nie, Zimin; Li, Guosheng; Zavadil, K.; Xiao, Jie; Wang, Chong M.; Henderson, Wesley A.; Zhang, Jiguang; Wang, Yong; Mueller, Karl T.; Persson, Kristin A.; Liu, Jun

    2014-12-28

    Nanocomposite polymer electrolytes present new opportunities for rechargeable magnesium batteries. However, few polymer electrolytes have demonstrated reversible Mg deposition/dissolution and those that have still contain volatile liquids such as tetrahydrofuran (THF). In this work, we report a nanocomposite polymer electrolyte based on poly(ethylene oxide) (PEO), Mg(BH4)2 and MgO nanoparticles for rechargeable Mg batteries. Cells with this electrolyte have a high coulombic efficiency of 98% for Mg plating/stripping and a high cycling stability. Through combined experiment-modeling investigations, a correlation between improved solvation of the salt and solvent chain length, chelation and oxygen denticity is established. Following the same trend, the nanocomposite polymer electrolyte is inferred to enhance the dissociation of the salt Mg(BH4)2 and thus improve the electrochemical performance. The insights and design metrics thus obtained may be used in nanocomposite electrolytes for other multivalent systems.

  19. Advances in electrolyte cooling tower technology

    International Nuclear Information System (INIS)

    Cooling towers play an important role in the production of metals by means of electrowinning. These towers are subject to severe operating conditions, and hence, standard cooling tower designs and practices are often not applicable. This paper reviews the operational requirements and conditions applicable to electrolyte cooling towers, specifically zinc electrolyte towers. Aspects covered include the physical factors influencing electrolyte cooling, cooling tower design, coupling of cooling towers to ventilation systems and environmental compliance requirements. (author)

  20. Fuel cell assembly with electrolyte transport

    Science.gov (United States)

    Chi, Chang V. (Brookfield, CT)

    1983-01-01

    A fuel cell assembly wherein electrolyte for filling the fuel cell matrix is carried via a transport system comprising a first passage means for conveying electrolyte through a first plate and communicating with a groove in a second plate at a first point, the first and second plates together sandwiching the matrix, and second passage means acting to carry electrolyte exclusively through the second plate and communicating with the groove at a second point exclusive of the first point.

  1. [Rheology and hyaluronic acid in inflammatory joint effusions (author's transl)].

    Science.gov (United States)

    Zeidler, H; Altmann, S

    1977-11-11

    The Weissenberg rheogoniometer was used to measure viscosity, normal force and the number of molecular entanglements, calculated from a shear modulus obtained by prestationary experiments, in inflammatory and non-inflammatory synovial fluid effusions. The rheological properties show greater pathological change in the inflammatory synovial fluid samples than in the non-inflammatory. Variation in the hyaluronic acid concentration is only partly responsible for the pathological rheology. Initial experiments with a normalization method for the viscosity flow curves suggest the possibility of determining changes in polymerization or structure of the hyaluronic acid by rheological measurements. PMID:919558

  2. Rheological properties of cupuassu and cocoa fats

    Directory of Open Access Journals (Sweden)

    Gioielli, L. A.

    2004-06-01

    Full Text Available Cocoa butter is an important ingredient in chocolate formulation as it dictates the main properties (texture, sensation in the mouth, and gloss. In the food industry, the texture of fat-containing products strongly depends on the macroscopic properties of the fat network formed within the finished product. Cupuassu ( Theobroma grandiflorum , Sterculiaceae is an Amazonian native fruit and the seeds can be used to derive a cocoa butter like product. In general, these fats are similar to those of cocoa, although they are different in some physical properties. The objective of this study was to analyze several properties of the cupuassu fat and cocoa butter (crystal formation at 25 ° C, rheological properties, and fatty acid composition and mixtures between the two fats (rheological properties, in order to understand the behavior of these fats for their use in chocolate products. Fat flow was described using common rheological models ( Newton , Power Law, Casson and Bingham plastic.La manteca de cacao es un ingrediente muy importante en la formulación de chocolates y es responsable de la mayor parte de sus propiedades (textura, palatibilidad y brillo. En la industria de alimentos, la textura de productos que contienen grasa depende enormemente de las propiedades macroscópicas de la red cristalina de la grasa en el producto final. El cupuaçu es una fruta nativa de la región amazónica y sus semillas pueden ser usadas para obtener una grasa semejante a la manteca de cacao. En general, esta grasa es similar a la manteca de cacao, pero difiere en algunas de sus propiedades fisicas . El objetivo de este estudio fue analizar algunas propiedades de la grasa de cupuaçu y de la manteca de cacao (formación de cristales a 25 °C, propiedades reológicas y composición en ácidos grasos y de algunas mezclas entre las dos grasas (propiedades reológicas, a fin de conocer el comportamiento de estas grasas para ser usadas en productos de la industria del chocolate. El flujo de la grasa se ha descrito utilizando modelos reológicos comunes (Newton, ley de la potencia, Casson y plástico de Bingham.

  3. Experimental Investigation of Orthoenstatite Single Crystal Rheology

    Science.gov (United States)

    fraysse, G.; Girard, J.; Holyoke, C. W.; Raterron, P.

    2013-12-01

    The plasticity of enstatite, upper mantle second most abundant mineral, is still poorly constrained, mostly because of its high-temperature (T) transformation into proto- and clino-enstatite at low pressure (P). Mackwell (1991, GRL, 18, 2027) reports a pioneer study of protoenstatite (Pbcn) single-crystal rheology, but the results do not directly apply to the orthorhombic (Pbca) mantle phase. Ohuchi et al. (2011, Contri. Mineral. Petrol , 161, 961) carried out deformation experiments at P=1.3 GPa on oriented orthoenstatite crystals, investigating the activity of [001](100) and [001](010) dislocation slip systems; they report the first rheological laws for orthoenstatite crystals. However, strain and stress were indirectly constrained in their experiments, which questioned whether steady state conditions of deformation were achieved. Also, data reported for [001](100) slip system were obtained after specimens had transformed by twinning into clinoenstatite. We report here new data from deformation experiments carried out at high T and P ranging from 3.5 to 6.2 GPa on natural Fe-bearing enstatite single crystals, using the Deformation-DIA apparatus (D-DIA) that equipped the X17B2 beamline of the NSLS (NY, USA). The applied stress and specimen strain rates were measured in situ by X-ray diffraction and imaging techniques (e.g., Raterron & Merkel, 2009, J. Sync. Rad., 16, 748; Raterron et al., 2013, Rev. Sci. Instr., 84, 043906). Three specimen orientations were tested: i) with the compression direction along [101]c crystallographic direction, which forms a 45° angle with both [100] and [001] axes, to investigate [001](100) slip-system activity; ii) along [011]c direction to investigate [001](010) system activity; iii) and along enstatite [125] axis, to activate both slip systems together. Crystals were deformed two by two, to compare slip system activities, or against enstatite aggregates or orientated olivine crystals of known rheology for comparison. Run products microstructures were investigated by transmission electron microscopy. Despite a significant hardening with P, enstatite [001](100) slip system is found to be the easiest system at mantle P and T. Furthermore, orthoenstatite crystals exhibit a higher sensitivity to stress than olivine crystals, i.e. a higher n exponent in classical power laws. At the low stress level prevailing in the Earth mantle, enstatite crystals are thus harder than olivine crystals.

  4. Electrolytic hydrogen fuel production with solid polymer electrolyte technology.

    Science.gov (United States)

    Titterington, W. A.; Fickett, A. P.

    1973-01-01

    A water electrolysis technology based on a solid polymer electrolyte (SPE) concept is presented for applicability to large-scale hydrogen production in a future energy system. High cell current density operation is selected for the application, and supporting cell test performance data are presented. Demonstrated cell life data are included to support the adaptability of the SPE system to large-size hydrogen generation utility plants as needed for bulk energy storage or transmission. The inherent system advantages of the acid SPE electrolysis technology are explained. System performance predictions are made through the year 2000, along with plant capital and operating cost projections.

  5. Handbook of Aqueous Electrolyte Thermodynamics Theory & Application

    CERN Document Server

    Zemaitis, Joseph F; Rafal, Marshall

    1986-01-01

    Expertise in electrolyte systems has become increasingly important in traditional CPI operations, as well as in oil/gas exploration and production. This book is the source for predicting electrolyte systems behavior, an indispensable "do-it-yourself" guide, with a blueprint for formulating predictive mathematical electrolyte models, recommended tabular values to use in these models, and annotated bibliographies. The final chapter is a general recipe for formulating complete predictive models for electrolytes, along with a series of worked illustrative examples. It can serve as a usef

  6. Photocured Gelled Electrolytes For Secondary Li Cells

    Science.gov (United States)

    Nagasubramanian, Ganesan

    1994-01-01

    Class of photocured polymers exhibiting lithium-ion conductivities greater than those of well-studied polymers based on polyethylene oxide (PEO) show promise as polymeric electrolytes in rechargeable lithium cells. Increase in conductivity occasioned by use of electrolytes, coupled with amenability of electrolytes to formation into uniform thin (less than 25 micrometers thick), wide films, expected to result in cells with power densities greater than 100 W h/kg and charge/discharge rates exceeding currents equal, in amperes, to ampere-hour ratings. All-solid-state lithium batteries containing these electrolytes used as high-power, high-rate rechargeable power sources in commercial and aerospace applications.

  7. Rheological properties of sulfoacetate derivatives of cellulose.

    Science.gov (United States)

    Chauvelon, Gaëlle; Doublier, Jean-Louis; Buléon, Alain; Thibault, Jean-François; Saulnier, Luc

    2003-04-01

    Water-soluble cellulose acetate sulfate derivatives (CAS) have been prepared through chemical reaction involving sulfuric acid as a catalyst. These CAS have been obtained from cellulosic materials of different origins (pure cellulose, wheat bran, maize bran) and their rheological behavior in salt-free aqueous solution has been estimated in dilute and semi-dilute regime using dynamic viscoelastic and viscosity measurements. Influence of concentration, temperature of solubilization and temperature of measurement has been investigated. Weak gel-like properties were exhibited at elevated concentration (typically above 7-8 g/L). These systems also exhibited thixotropic properties: the structure was partly broken down upon shearing and recovered at rest. They also displayed thermoreversibility with large hysteresis, the melting temperature being approximately 15 degrees C higher than the temperature at which gelation took place. These overall observations clearly indicate that these distinctive properties arise from intermolecular association of the macromolecular chains of the cellulose derivative. PMID:12668095

  8. Impact of Helicobacter Pylori on Mucus Rheology

    Science.gov (United States)

    Celli, Jonathan; Keates, Sarah; Kelly, Ciaran; Turner, Bradley; Bansil, Rama; Erramilli, Shyamsunder

    2006-03-01

    It is well known that the viscoelastic properties of gastric mucin are crucial to the protection of the lining of the stomach against its own acidic secretions and other agents. Helicobacter Pylori, a rod shaped, gram-negative bacteria that dwells in the mucus layer of approximately 50% of the world's population is a class I carcinogen and is associated with gastric ulcers and severe gastritis. The structural damage to the mucus layer caused by H. Pylori is an important aspect of infection with this bacteria. We are examining the impact of H. Pylori on mucin and mucus rheology quantitatively using a combination of dynamic light scattering and multiple particle tracking experiments. Video microscopy data will also be presented on the motility of this bacteria in mucin at different pH and in other viscoelastic gels.

  9. Rheology of irradiated honey from Parana region

    International Nuclear Information System (INIS)

    Viscosity characteristics can be governed by the molecular chain length of sugars present in the honey. Honey is essentially a mixture of sugar and water. When a physical treatment, as gamma radiation, is applied to food, some changes on its viscosity may occur. Viscosity is one of the important properties of honey and depends on water and sugar quantities. The objective of this work was to verify the rheological behavior of irradiated honey from Parana region in comparison to the unirradiated one. Each rheogram was measured at different shear rates that was increased to a certain value then immediately decreased to the starting point ('up and down curves'). These measurements were made for control and irradiated samples (5 and 10 kGy) in different temperatures (30 deg. C, 35 deg. C and 40 deg. C). The curves constructed with shear stress against shear rate presented linearity. Honey, irradiated and control, showed a Newtonian behavior and gamma radiation did not affect it

  10. Microfluidic Rheology of Soft Colloids near Jamming

    Science.gov (United States)

    Nordstrom, Kerstin; Verneuil, E.; Arratia, P. E.; Gollub, J. P.; Durian, D. J.

    2010-03-01

    The rheology near jamming of a suspension of soft colloidal spheres is studied using pressure-driven flow in a deep 25 ?m wide microchannel. The system is composed of N-isopropylacrylamide (NIPA) microgel particles which exhibit thermoresponsive behavior; the suspension packing fraction is modified with a slight change in temperature. We use a force balance argument to infer the shear stress in the channel and use particle image velocimetry (PIV) to measure the strain rate. Stress vs. strain rate curves show clear non-Newtonian behavior below the jamming point and yield stress behavior above the jamming point. The data may be collapsed onto two branches but with different critical exponents than those obtained by Olsson and Teitel [1]. These results give credence to the idea that jamming is similar to a phase transition, but with interaction-dependent critical exponents. [1] Olsson and Teitel, PRL 2007

  11. Dimorphic magnetorheological fluid with improved rheological properties

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Wanquan, E-mail: jiangwq@ustc.edu.cn [Department of Chemistry, University of Science and Technology of China (USTC), Hefei 230026 (China); Zhang Yanli [Department of Chemistry, University of Science and Technology of China (USTC), Hefei 230026 (China); Xuan Shouhu; Guo Chaoyang [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, USTC, Hefei 230027 (China); Gong Xinglong, E-mail: gongxl@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, USTC, Hefei 230027 (China)

    2011-12-15

    A type of dimorphic magnetorheological (MR) fluid was prepared by adding wire-like iron nanostructures into the conventional carbonyl iron based MR fluid. The Fe nanowires were synthesized through reducing Fe{sup 2+} ion with excessive sodium borohydride in aqueous solution. The rheological behaviors of the dimorphic MR fluids were measured with a rotational rheometer and the sedimentation properties were also studied in this work. It was found that the Fe wires additives can greatly enhance the stress strength of the dimorphic MR fluids comparing with the conventional MR fluids. The sedimentation of the dimorphic MR fluids was also mitigated greatly. - Highlights: > Dimorphic MR fluids with enhanced MR effect were prepared. > Fe nanowires and spherical carbonyl iron particles show a synergistic effect on improving the performance of MR fluid. > Sedimentations of the dimorphic MR fluids were mitigated greatly.

  12. Human cervical mucus. I. Rheologic characteristics.

    Science.gov (United States)

    Wolf, D P; Blasco, L; Khan, M A; Litt, M

    1977-01-01

    The viscoelastic properties of human cervical mucus were subjected to detailed characterization by microrheometry. An introduced to the range of parameters that can be measured and the sensitivity of microroheometry to variations in mucus viscoelasticity was presented, along with an interpretation of results obtained by this approach. Fresh cervical mucus samples were shown to be rheologically heterogeneous, reflecting compositional differences in situ. Mucas viscoelasticity was stable for several hours when samples were stored at ambient temperature in the microrheometer sample holder. Mucus viscoelasticity was strongly dependent upon nondialyzable solids (NDS) concentration. In order to eliminate (NDS) as a variable in comparative studies of mucus, procedures were developed for reconstitution of mucus at identical (NDS) or for normalization of viscoelasticity data derived from fresh samples to 2.5% NDS. The validity of this approach was then examined by applying these procedures to mucus collected during the follicular, ovulatory, and luteal phases of the normal menstrual cycle. PMID:556703

  13. Rheological and microstructural properties of Irradiated starch

    International Nuclear Information System (INIS)

    Gamma irradiation ia s fast and efficient method to improve the functional properties of straches. Wheat and potato starches were submitted, in the present study, at 3,5,10 and 20 kGy radiation dose. The changes induced by irradiation on the rheological properties of these starches showed a decrease in the viscosity with increasing radiation dose. Chemicals bond's hydrolysis has been induced by free radicals that have been identified by EPR. Wheat starch presents five EPR signals after irradiation, whiles potato starch has a weak EPR signal. On the other hand, irradiation caused decrease in amylose content. This decrease is more pronounced in potato starch. Dry irradiated starch's MEB revealed no change in the shape, size and distribution of the granules. While, the observation of wheat starch allowed the complete disappearance of the granular structure and the dissolution of its macromolecules after irradiation which justifies the significant decrease in wheat starch's viscosity irradiated at 20 kGy.

  14. The Rheological Property of Potato Starch Adhesives

    Directory of Open Access Journals (Sweden)

    Junjun Liu

    2014-02-01

    Full Text Available The main goal of this study was to use potato starch in the production of environmentally sound adhesives. ‘Three-formaldehyde glue’ pollutes the environment and harms to human health strongly, which widely used for wood-based panels preparation. Environment-friendly potato starch adhesives were prepared using method of oxidation-gelatinization, insteading of the three formaldehyde glue. The effects of the quality ratio of starch and water, temperature and shear rate on the apparent viscosity of the adhesive were studied. The rheological eigenvalue of apparent viscosity was studied through nonlinear regression. The results showed that the apparent viscosity of potato starch adhesives decreased with the increasing of temperature; the apparent viscosity decreased slowly with the increasing of rotor speed; the phenomenon of shear thinning appeared within potato starch adhesives which was pseudo-plastic fluids. Potato starch adhesives with characteristics of non-toxic, no smell and pollution could be applied in interior and upscale packaging.

  15. Dimorphic magnetorheological fluid with improved rheological properties

    International Nuclear Information System (INIS)

    A type of dimorphic magnetorheological (MR) fluid was prepared by adding wire-like iron nanostructures into the conventional carbonyl iron based MR fluid. The Fe nanowires were synthesized through reducing Fe2+ ion with excessive sodium borohydride in aqueous solution. The rheological behaviors of the dimorphic MR fluids were measured with a rotational rheometer and the sedimentation properties were also studied in this work. It was found that the Fe wires additives can greatly enhance the stress strength of the dimorphic MR fluids comparing with the conventional MR fluids. The sedimentation of the dimorphic MR fluids was also mitigated greatly. - Highlights: ? Dimorphic MR fluids with enhanced MR effect were prepared. ? Fe nanowires and spherical carbonyl iron particles show a synergistic effect on improving the performance of MR fluid. ? Sedimentations of the dimorphic MR fluids were mitigated greatly.

  16. Rheological properties of ferrofluids with microstructures

    International Nuclear Information System (INIS)

    This paper presents results of a theoretical study of the effects of linear chain-like as well as bulk drop-like heterogeneous aggregates on the rheological properties and behaviour of ferrofluids. The results demonstrate that the appearance of both these internal structures leads to a strong (one-two orders of magnitude) increase of the ferrofluid effective viscosity under the action of the magnetic field applied parallel to the gradient of the ferrofluid flow. When the ferrofluid fills a thin channel (gap) placed into a normal magnetic field, the drop-like structures can overlap with the channel. In the case of a rigid connection between the drop-like domains and the channel walls, the appearance of elastic and yield stress effects on the ferrofluid is expected

  17. Rheological properties of ferrofluids with microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Zubarev, A Yu; Iskakova, L Yu [Ural State University, 620083 Ekaterinburg (Russian Federation)

    2006-09-27

    This paper presents results of a theoretical study of the effects of linear chain-like as well as bulk drop-like heterogeneous aggregates on the rheological properties and behaviour of ferrofluids. The results demonstrate that the appearance of both these internal structures leads to a strong (one-two orders of magnitude) increase of the ferrofluid effective viscosity under the action of the magnetic field applied parallel to the gradient of the ferrofluid flow. When the ferrofluid fills a thin channel (gap) placed into a normal magnetic field, the drop-like structures can overlap with the channel. In the case of a rigid connection between the drop-like domains and the channel walls, the appearance of elastic and yield stress effects on the ferrofluid is expected.

  18. Rheological properties of ferrofluids with microstructures

    Science.gov (United States)

    Zubarev, A. Yu; Iskakova, L. Yu

    2006-09-01

    This paper presents results of a theoretical study of the effects of linear chain-like as well as bulk drop-like heterogeneous aggregates on the rheological properties and behaviour of ferrofluids. The results demonstrate that the appearance of both these internal structures leads to a strong (one-two orders of magnitude) increase of the ferrofluid effective viscosity under the action of the magnetic field applied parallel to the gradient of the ferrofluid flow. When the ferrofluid fills a thin channel (gap) placed into a normal magnetic field, the drop-like structures can overlap with the channel. In the case of a rigid connection between the drop-like domains and the channel walls, the appearance of elastic and yield stress effects on the ferrofluid is expected.

  19. Rheology of petroleum coke-water slurry

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, M.; Mall, B.K.; Mukherjee, A.; Basu, S.K.; Verma, S.K.; Narasimhan, K.S.

    1998-07-01

    This paper reports the results of the studies carried out on the optimization of particle size distribution, the rheological characteristics and stability of highly loaded petroleum coke-water slurry using three additives. The solids loading achieved in the slurries were in the range of 65% to 75.6% depending on the additives used. Slurry viscosity varied between 267 to 424 mPas at 128 s{sup {minus}} shear rate. The petroleum coke-water slurries exhibited pseudoplastic characteristics with yield tending towards Bingham plastic as the solids loading progressively increased. The effect of addition of petroleum coke to the extent of 25% in coal-water slurry prepared from low ash Ledo coal of Makum field in Assam was also examined. The slurry containing coal-petroleum coke blend showed better stability, having shelf life of 7 days as compared to 5 days in the case of petroleum coke-water slurry.

  20. Rheological properties of sodium smectite clay

    International Nuclear Information System (INIS)

    The rheological properties of Na-smectite Mx-80 have been investigated by various laboratory tests. The investigations include determination of the hydraulic conductivity, the undrained stress-strain-strength properties, the creep properties, the compression and swelling properties in drained and undrained conditions and the undrained thermomechanical properties. Measurements have been made at different densities, clay/sand mixtures and pore water compositions. The influence of temperature, rate of strain and testing technique has also been considered. The investigation has led to a supply of basic data for the material models which will be used at performance calculations. The results have also increased the general understanding of the function of smectitic clay as buffer material. The microstructural behaviour has been considered at the validation of the different test results and the validity of the effective stress theory has been discussed. Comparisons with the properties of Ca-smectite have also been made. (orig.)

  1. Rheology of dense sheared granular liquids (Invited)

    Science.gov (United States)

    Suzuki, Koshiro; Hayakawa, Hisao

    2014-12-01

    The rheology of dense sheared granular liquids is investigated based on the mode-coupling theory (MCT). This extended MCT includes correlations for the density-current mode as well as the density-density correlation mode, and a self-consistent coupling equation for the energy balance condition. The extended MCT exhibits disappearance of the two-step relaxation of the density-density correlation function, and also successfully reproduces the density dependence of the shear viscosity for volume fractions between 0.50 and 0.60, if we shift the density. However, it predicts unphysical tendency for the granular temperature. The cause of this drawback and the possibilities of its amendment are discussed.

  2. Rheological characterization of Alaska heavy oils

    Science.gov (United States)

    Akeredolu, Babajide

    Heavy crude oil reserves from the North Slope of Alaska are highly viscous, biodegraded oils that make standard oil production methods ineffective. A matrix of 18 mixtures with varying sand and water contents encompass the properties likely to be seen during production, especially cold production methods. Physical properties of the Alaska heavy oils were studied by viscosity measurements, including small amplitude shear tests and flow tests in a temperature range of -10°C to 60°C. The viscosity was observed to decrease with increasing temperature and displayed shear thinning. The activation energy of viscosity as a function of temperature ranged between 67 kJ/mol and 92 kJ/mol, similar to other heavy oils. Sand content alters the viscosity by up to 370% and non-monotonically while the water content changes viscosity by 53% or less. Also, a high pressure rheology apparatus was constructed to measure viscosity of Alaska heavy oil saturated with methane at pressures from 15 psi to 1800 psi and shear rates from 0.1 s-1 to 500 s-1. Viscosity of Alaska heavy oil is pressure dependent showing an order of magnitude decrease at a pressure of 1500 psi. Viscosity had a minimum value of 0.11 Pa-s and a maximum value of 590 Pa-s at 60°C/1810 psi and 0°C/15 psi, respectively. These rheological properties contribute to the overall objective of the project which is to advance seismic monitoring, using chemical and physical characterization of core samples in combination with stimulated production experiments, to optimize the recovery of heavy oils from Alaskan deposits.

  3. Surface Morphology and Microstructure of Zinc Deposit From Imidazole with Zinc Chloride Low Temperature Molten Salt Electrolyte in The Presence of Aluminium Chloride

    OpenAIRE

    Shanmugasigamani Srinivasan, M. Selvam

    2013-01-01

    Low temperature molten salts have variety of applications in organic synthesis, catalytic processing, batteries and electrode position due to their air and water stability. They have wide potential window for their applications in voltage and temperature and hence there is a possibility to deposit metals which could not be deposited from aqueous electrolytes. Our aim and scope of our research was to deposit zinc from low temperature molten salt electrolyte (LTM...

  4. Ultrafast Li Electrolytes Based on Abundant Elements: Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$

    OpenAIRE

    Kuhn, Alexander; Gerbig, Oliver; Zhu, Changbao; Falkenberga, Frank; Maier, Joachim; Lotsch, Bettina V.

    2014-01-01

    We report on the synthesis and characterization of two solid electrolytes, Li$_{10}$SnP$_2$S$_{12}$ and Li$_{11}$Si$_2$PS$_{12}$, which are based exclusively on abundant elements. Both compounds feature extremely high Li ion diffusivities, with the Si-based material even surpassing the present record holder, the related electrolyte Li$_{10}$GeP$_2$S$_{12}$. The structure and dynamics were studied with multiple complementary techniques and the macroscopic diffusion could be t...

  5. Multivariant simulator for vacuum cooling processes of three component electrolyte systems

    Directory of Open Access Journals (Sweden)

    Suljkanovi? Midhat

    2010-01-01

    Full Text Available In this paper, a computer aided analysis and synthesis of the crystallization processes from multicomponent electrolyte systems were studied. In addition, the vacuum crystallization processes with adiabatic cooling of the system are presented. The cooling process of a multicomponent electrolyte system can be considered as a process with the concentration of the system and/or the crystallization of the solid phase from the system. Requirements for multivariant options of the process simulator are the result of practical needs in the design of new processes or the improvement of exploitation processes. According to this, there are needs for a simulation of a simple flashing of the system as well as for the vacuum cooling crystallization processes with the cyclic structure. The possibilities of the created process simulator are illustrated on three component electrolyte systems. Application of the process simulator for any other electrolyte systems requires only an update of the thermodynamic model, and physico-chemical properties related to electrolyte system.

  6. Improvement by heating of the electronic conductivity of cobalt spinel phases, electrochemically synthesized in various electrolytes

    International Nuclear Information System (INIS)

    The nature of the alkaline electrolyte (based on KOH, NaOH, LiOH), in which Co3O4 spinel type phases are synthesized by electrooxidation of CoO, is shown to play a key role on the composition, the structure and the electronic conductivity of the materials. In the materials, prepared in pure LiOH electrolyte or in mixed ternary electrolyte (KOH, NaOH, LiOH), Co4+ ions are present in the octahedral framework, which entails electronic delocalization in the cobalt T2g band and a high conductivity. The structure of the sample, synthesized in KOH, is on the opposite closer to that of ideal Co3O4, with only Co3+ in the octahedral sublattice, which leads to a semi-conducting behavior. Whatever the initial material, a thermal treatment induces an increase of the Co4+/Co3+ ratio in the octahedral network, resulting in a significant increase of the electronic conductivity. - Graphical abstract: In 'Co3O4' type spinel phases synthesized by eleectrooxidation, the nature of the alkaline electrolyte allows to monitor the amounts of hydrogen and lithium, inserted in spinel framework and therefore the electronic conductivity. Whatever the initial synthesis electrolyte, a moderate thermal treatment of the materials induces a significant increase of the electronic conductivity, due to a structural reorganization (illustrated by the evolution of the cell parameter) andy the evolution of the cell parameter) and an increase of the Co4+/Co3+ ratio in the octahedral framework.

  7. Fundamental Aspects of Ion Transport in Solid Electrolytes

    Science.gov (United States)

    Ratnakumar, B. V.; Narayanan, S. R.

    1994-01-01

    Solid electrolytes (also termed as superionic solids or fast ion conductors) are characterized by high electrical conductivity, comparable to concentrated liquid electrolytes or even molten salt electrolytes, made possible by rapid transport of ions in the crystalline lattice.

  8. Supercapacitor behavior of ?-MnMoO{sub 4} nanorods on different electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Purushothaman, K.K., E-mail: purushoth_gri@yahoo.co.in [Department of Physics, TRP Engineering College (SRM Group), Irungalur, Trichy, Tamilnadu (India); Cuba, M. [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India); Muralidharan, G., E-mail: muralg@rediffmail.com [Department of Physics, Gandhigram Rural Institute – Deemed University, Gandhigram, Tamilnadu (India)

    2012-11-15

    Graphical abstract: SEM image of ?-MnMoO{sub 4} nanorods on FTO substrate. Highlights: ? Synthesis of ?-MnMoO{sub 4} nanorods by spin coating method. ? First study on the effect of electrolyte on the pseudocapacitance behavior. ? ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g. ? At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior. -- Abstract: ?-MnMoO{sub 4} nanorods were prepared on conducting glass substrate via sol–gel spin coating method at the optimum doping level. The effect of electrolyte on the pseudocapacitance behavior of the ?-MnMoO{sub 4} nanorods was studied using para toluene sulfonic acid (p-TSA), sulfuric acid (H{sub 2}SO{sub 4}) and hydrochloric acid (HCl) as electrolytes. X-ray diffraction analysis reveals the formation of ?-MnMoO{sub 4} in monoclinic phase. FTIR spectra contain vibrational bands associated with Mo=O, M–O and Mo–O–Mo bonds. SEM image reveals the formation of nanorods. Supercapacitor behavior has been studied using cyclic voltammetry (CV) analysis. ?-MnMoO{sub 4} nanorods exhibit maximum specific capacitance of 998 F/g at a scan rate of 5 mV/s in H{sub 2}SO{sub 4} electrolyte while a specific capacitance of 784 F/g and 530 F/g have been obtained using p-TSA and HCl electrolytes, respectively. At higher scan rates p-TSA electrolyte exhibits superior capacitive behavior than H{sub 2}SO{sub 4}.

  9. Plasma electrolytic oxidation of tantalum

    Directory of Open Access Journals (Sweden)

    Petkovi? Marija

    2012-01-01

    Full Text Available This paper is a review of our research on the plasma electrolytic oxidation (PEO process of tantalum in 12-tungstosilicic acid. For the characterization of microdischarges during PEO, real-time imaging and optical emission spectroscopy (OES were used. The surface morphology, chemical and phase composition of oxide coatings were investigated by AFM, SEM-EDS and XRD. Oxide coating morphology is strongly dependent on PEO time. The elemental components of PEO coatings are Ta, O, Si and W. The oxide coatings are partly crystallized and mainly composed of WO3, Ta2O5 and SiO2.

  10. Electroreduction of oxide solid electrolytes

    International Nuclear Information System (INIS)

    Experimental data on the processes of electroreduction of solid oxide electrolytes (including ZrO2, Y2O3, CeO2, were systematized and generalized. A model of the process of electroreduction, relating it with the movement of electron conductivity front and appearance of colour centres, is suggested. Analytic and numerical calculation of reduction rate under isothermal conditions and when a high temperature gradient is applied to a sample. The rate of electroreduction is determined by the ratio of activation energies of ionic and electronic conductivities and heats of ion and electron transfer

  11. The rheology of sewage sludge at different steps of treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lotito, V.; Spinosa, L.; Antonacci, R. [Centro Nazionale delle Ricerche, Bari (Italy). Ist. di Ricerca sulle Acque; Mininni, G. [Centro Nazionale delle Ricerche, Rome (Italy). Ist. di Ricerca sulle Acque

    1998-12-31

    Rheological parameters are very important in sewage sludge management as controlling parameters in many treatments, such as stabilisation and dewatering.To study how different sludge treatments affect its rheological behaviour, research has been undertaken at CNR-IRSA, whose preliminary results are discussed in this paper. Sludge samples taken from three municipal wastewater treatment plants at different steps of treatment have been tested by a rotational viscometer and data interpreted through both Bingham plastic and Ostwald pseudo plastic models. Coefficients of above models have been then correlated to solids concentration. Results confirmed that solids concentration is the main parameter affecting sludge rheology and evidenced that a single parameter is not sufficient to represent the rheological behaviour, thus indicating that other parameters should be introduced and characteristics considered for a better understanding of the phenomenon.

  12. Rheological characterization of polyolefin composites with reduced flammability

    Science.gov (United States)

    Habrova, Veronika; Kalendova, Alena; Paravanova, Gordana

    2012-07-01

    In this work, the low-flammability halogen-free polyolefin composites were characterized with three rheological methods. In the extrusion process of the studied materials the end-products with a dissimilar surface quality were produced. Therefore, the diverse melt flow behaviours evaluated with common rheological techniques were also expected. Nevertheless, the conventional rotational and capillary rheometries were not able to describe the differences between investigated flame retarded composites in optimal way. Thus, the non-conventional rheological die Shark skin, originally designed to detect flow instabilities, was tested as a third possibility in order to better understand rheology of the filled polymer melts. It was found that the Shark skin technique is able to characterize the studied two kind flame retardants composites and can also be helpful to qualify the production bathes with identical additives/polymer formulation.

  13. Anomalous rheological behavior of long glass fiber reinforced polypropylene

    Science.gov (United States)

    Kim, Dong Hak; Lee, Young Sil; Son, Younggon

    2012-12-01

    Dynamic rheological properties of PP-based long glass fiber-reinforced thermoplastics (LFT) were investigated. Weight fractions of the glass fibers investigated in the present study ranged from 0.15 to 0.5, which are higher than those of previous studies. We observed very abnormal rheological behavior. Complex viscosity (?*) of the LFT increased with the glass fiber content up to 40 wt. %. However, the ?* with a weight fraction of 0.5 is observed to be lower than that of LFT with a weight fraction of 0.4 in spite of higher glass fiber content. From various experiments, we found that this abnormal behavior is analogous to the rheological behavior of a lyotropic liquid crystalline polymer solution and concluded that the abnormal rheological behavior for the LFT is attributed to the formation of a liquid crystal- like structure at high concentrations of long glass fibers.

  14. Bentonites from Boa Vista, Brazil: physical, mineralogical and rheological properties

    Scientific Electronic Library Online (English)

    Luciana Viana, Amorim; Cynthia Morais, Gomes; Helio de Lucena, Lira; Kepler Borges, França; Heber Carlos, Ferreira.

    2004-12-01

    Full Text Available SciELO Brazil | Language: English Abstract in english The aim of this work is to characterize physically and mineralogically six samples of natural and industrialized bentonites from Paraíba, Brazil, and to study its rheological properties to be used as a components of water based drilling fluids. Also it is intended to compare the evolution of the min [...] eralogical composition and rheology of these clays after 40 years of exploitation. The natural bentonite clays were transformed into sodium bentonite by addition of concentrated Na2CO3 solution. The suspensions were prepared with 4.86% w/w to measure their rheological properties (apparent and plastic viscosities and water loss). The results showed that: i) the samples present typical mineralogical compositions of bentonites, but after four decades of exploitation, presents inferior quality and ii) among the clays samples, only one presented satisfactory rheological properties be used as a components of water based drilling fluids.

  15. RHEOLOGY AND SCALING BEHAVIOR OF SWELLING CLAY DISPERSIONS

    Directory of Open Access Journals (Sweden)

    S. CHAOUI

    2012-12-01

    Full Text Available The microstructure and scaling of rheological properties of colloidal gels of bentonite investigated as a function of volume fraction and strength of interparticle interaction over a range of volume fractions, elastic modulus is well described with a scaling law functions of volume fractions, while the role of interparticle attractions can be accounted for by expressing these rheological properties as (?/?g-1n, where ?g captures the strength of particle interaction and n the microstructure.The scaling variable (?p/?pc-1, suggested in percolation theory to describe rheological behavior near percolation transition, acts to collapse G’ data suggesting that along lines of constant (?/?g-1 these gels are rheologically identical.

  16. Advances in the rheology of polymers. Novoe v reologii polimerov

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, G.V.

    1981-01-01

    The topics of the papers embrace a wide range of problems in theoretical, experimental, and instrumental rheology, pertaining to the properties of solutions and melts of macromolecular compounds, suspensions, pasty disperse systems, and highly filled composites.

  17. Bentonites from Boa Vista, Brazil: physical, mineralogical and rheological properties

    Directory of Open Access Journals (Sweden)

    Luciana Viana Amorim

    2004-12-01

    Full Text Available The aim of this work is to characterize physically and mineralogically six samples of natural and industrialized bentonites from Paraíba, Brazil, and to study its rheological properties to be used as a components of water based drilling fluids. Also it is intended to compare the evolution of the mineralogical composition and rheology of these clays after 40 years of exploitation. The natural bentonite clays were transformed into sodium bentonite by addition of concentrated Na2CO3 solution. The suspensions were prepared with 4.86% w/w to measure their rheological properties (apparent and plastic viscosities and water loss. The results showed that: i the samples present typical mineralogical compositions of bentonites, but after four decades of exploitation, presents inferior quality and ii among the clays samples, only one presented satisfactory rheological properties be used as a components of water based drilling fluids.

  18. Study and development of a hydrogen/oxygen fuel cell in solid polymer electrolyte technology

    Energy Technology Data Exchange (ETDEWEB)

    Mosdale, R.

    1992-10-29

    The hydrogen/oxygen fuel cell appears today as the best candidate to the replacing of the internal combustion engine for automobile traction. This system uses the non explosive electrochemical recombination of hydrogen and oxygen. It is a clean generator whom only reactive product is water. This thesis shows a theoretical study of this system, the synthesis of different kinds of used electrodes and finally an analysis of water movements in polymer electrolyte by different original technologies. 70 refs., 73 figs., 15 tabs.

  19. New Polymer Electrolyte Membranes Based on Acid Doped PBI For Fuel Cells Operating above 100°C

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    The technical achievement and challenges for the PEMFC technology based on perfluorosulfonic acid (PFSA) polymer membranes (e.g. Nafion®) are briefly discussed. The newest development for alternative polymer electrolytes for operation above 100°C. As one of the successful approaches to high operational temperatures, the development and evaluation of acid doped PBI membranes are reviewed, covering polymer synthesis, membrane casting, acid doping, physiochemical characterization and fuel cell tests.

  20. Electrochemical and rheological behaviour of a fluid zinc paste; Comportement electrochimique et rheologique d`une pate de zinc fluide

    Energy Technology Data Exchange (ETDEWEB)

    Sajot, N.

    1997-12-04

    Zinc is a performing anodic material in numerous types of batteries. The anode of alkaline cells is typically a suspension of metallic powder in a gelled potassium hydroxide electrolyte, called zinc paste. We process such a homogeneous, fluid and stable paste, we study its physical electrochemical and rheological properties. Electrical power delivered during galvano-static electrolysis is about a few tens of mW.cm{sup -2} for anodic overvoltages inferior to 200 mV until the complete oxidation of the metal, 10 oxidation-reduction cycles are realised on paste samples of few mm width. In other respects, the product has a Bingham-type flow behavior, of critical shearing stress close to 200 Pa, and plastic viscosity about Pa.s, valid from 0,1 s{sup -1} shear rate. Zinc paste circulates in a slim rectangular section channel. Movement is ensured by a peristaltic pump placed on a cylindrical flexible tube. The paste transit between rectangular and circular sections is made through a profiled mechanical piece called a fish tail, without draft edge or roughness. An electrolytic separator and a current collector form the walls of the parallelopipedal channel, thus an electrolysis cell is framed. We record electrical and rheological characteristics of 2 oxidation-reduction cycles, during which the paste continues to flow and remains conductive. Established performances on the elementary cell allow to make up an air-zinc circulating paste battery for an electrical vehicle: the hydraulic recharge of a 100 l anodic paste tank is made in a few minutes, corresponding to a 300 km autonomy. (author) 87 refs.

  1. In situ rheology of Staphylococcus epidermidis bacterial biofilms

    OpenAIRE

    Pavlovsky, Leonid; Younger, John G.; Solomon, Michael J.

    2012-01-01

    We developed a method to grow Staphylococcus epidermidis bacterial biofilms and characterize their rheological properties in situ in a continuously fed bioreactor incorporated into a parallel plate rheometer. The temperature and shear rates of growth modeled bloodstream conditions, a common site of S. epidermidis infection. We measured the linear elastic (G?) and viscous moduli (G?) of the material using small-amplitude oscillatory rheology and the yield stress using non-linear creep rheo...

  2. Rheological Characterization of Sludge Coming from a Wastewater Treatment Plant

    OpenAIRE

    Daniel Novarino; Ezio Santagata; Davide Dalmazzo; Mariachiara Zanetti

    2010-01-01

    Problem statement: The aim of this study was that of studying the rheology of sewage sludge using two different rheological test protocols taken from literature and comparing them in order to evaluate which useful information are given from every protocol. Approach: Two different protocols have been used taking particularly into account the problems connected to sludge heterogeneous composition and to the interaction between solid-solid and solid-water particles in order to completely underst...

  3. Modelling of Rheological Properties of Carbon Nanotube Suspensions

    OpenAIRE

    Cruz Bernal, Camilo Andre?s

    2010-01-01

    Single-walled carbon nanotubes (SWNTs) are frequently diluted in solvents with the aim of purify, functionalize and transform them. Control and optimization of those processes in liquid phase require a deep understanding of the rheology of SWNT suspensions. However, there is no consensus about the physical origin of some rheological signatures exhibited by the SWNT suspensions. This thesis is intended to elucidate this question by modelling the linear viscoelastic behaviour of SWNT dilute sus...

  4. Rheological properties of whey proteins concentrate before and

    OpenAIRE

    Zoran Herceg; Vesna Lelas; Suzana Rimac

    2001-01-01

    Hydrocolloids are long-chain polymers, used in food production at small quantities (from 0,05 to 5 %) to achieve appropriate rheological properties, prevent syneresis, increase the viscosity and stability of foodstuffs and for crystallization process control. The aim of this work was to investigate the influence of tribomechanical micronization of powdered whey protein concentrate on the rheological properties of whey proteins model systems as well as the influence of severalcarboxymethylcell...

  5. Rheology and texture of doughs: applications on wheat and corn

    OpenAIRE

    Eduardo Rodríguez Sandoval; Alejandro Fernández Quintero; Alfredo Ayala Aponte

    2010-01-01

    A dough made of maylacceou materials shows a viscoelastic behavior, its macroestructural behavior depends on processing conditions, its constitutents and the interaction among them. Studies on dough rheology and texture are useful and important for applications that include ingredient specifications, quality control, product design and adaptation of new processing technologies. This work is a review of rheological and textural principles, testing methods and characteristics of wheat and com d...

  6. Rheology and texture of doughs: applications on wheat and corn

    Directory of Open Access Journals (Sweden)

    Eduardo Rodríguez Sandoval

    2010-04-01

    Full Text Available A dough made of maylacceou materials shows a viscoelastic behavior, its macroestructural behavior depends on processing conditions, its constitutents and the interaction among them. Studies on dough rheology and texture are useful and important for applications that include ingredient specifications, quality control, product design and adaptation of new processing technologies. This work is a review of rheological and textural principles, testing methods and characteristics of wheat and com doughs.

  7. Rheological characterization of a time dependent fresh cement paste

    Science.gov (United States)

    Rubio-Hernández, F. J.; Velázquez-Navarro, J. F.; Galindo-Rosales, F. J.

    2009-05-01

    Combining equilibrium and non-equilibrium rheological tests, the yield stress and the plastic viscosity corresponding to the completely build-up structure of a fresh cement paste have been determined. This experimental method is proposed to characterize time-dependent fluids because the values of these parameters are not dependent on the particular structural state of the system and, consequently, are not affected by the particular way in which the rheological test has been designed.

  8. Rheology of the gelation process of silica gel

    OpenAIRE

    Filho, O. K.; Aegerter, Michel A.

    1988-01-01

    The rheology of silica sols prepared from mixtures of tetramethoxysilane (TMOS)-methanol-water under basic neutral conditions has been studied at 25, 40 and 60 ° C during the gelation process. The sols show non-Newtonian pseudoplastic behavior from the time of preparation with the appearance of yield stress near the gelation point. The results are analysed using rheological equations of state and the concept of the point of gelation is discussed. For neutral sols an apparent activation energ...

  9. Rheological Properties of Oil in Water Emulsions and Particulate Suspensions

    OpenAIRE

    Chen, Shukun

    2006-01-01

    This thesis aims at a better understanding of the rheologicalproperties of the important colloids in oil industry, i.e. suspensions, emulsions and waxes. The rheology of suspension system is a complex field influenced by a large range of variables. In this work, we mainly focused on the rheological properties of suspensions as a function of volume fraction of particles, particle size, surface properties, shear rate, and the nature of continuous mediums. The investigated suspensions behaved as...

  10. Influence of mineral additives on rheological properties of fresh concrete

    OpenAIRE

    Andrejka, Nejc

    2012-01-01

    The purpose of the research was to examine the influence of mineral admixture on the rheological properties of fresh concrete mixtures. Rheological properties of fresh concrete mixtures were obtained in three ways, with well known methods slump test and flow table test and with yet fairly non-established coaxial cylindrical rheometer ConTec Viscometer 5. Rheometer is a better and modern way to detect such properties of fresh concrete. Recently the approach has become indispensable, due to gro...

  11. Rheological and Electrical Transitions in Carbon Nanotube/Epoxy Suspensions

    OpenAIRE

    Allaoui, Aissa; El Bounia, Nour-eddine

    2010-01-01

    The rheological and electrical properties of suspensions of carbon nanotubes in an uncured epoxy resin were investigated by means of shear rheology and impedance spectroscopy. It was found that above an onset CNT weight fraction (0.1 wt %), the steady viscosity increased with CNT loading and presented a shear thinning behaviour. The concentration dependence of viscosity changed from a power law to an exponential with increasing shear rate, indicating a loss of interaction be...

  12. Rheological Characterization and Constitutive Modeling of Two LDPE Melts.

    Czech Academy of Sciences Publication Activity Database

    Rolón-Garrido, V. H.; Pivokonský, Radek; Filip, Petr; Zatloukal, M.; Wagner, M. H.

    Melville : American Institute of Physics, 2009 - (Zatloukal, M.), s. 32-43 ISBN 978-0-7354-0689-6. ISSN 0094-243X. - (AIP Conference proceedings. Vol. 1152). [Novel Trends in Rheology /3./. Zlín (CZ), 28.07.2009-29.07.2009] R&D Projects: GA AV ?R IAA200600703 Institutional research plan: CEZ:AV0Z20600510 Keywords : Rheology * MSF model * shear flow * elongational flow * train hardening * low-density polyethylene * polymer melts Subject RIV: BK - Fluid Dynamics

  13. Rheology of Carbon Fibre Reinforced Cement-Based Mortar

    International Nuclear Information System (INIS)

    Carbon fibre reinforced cement based materials (CFRCs) offer the possibility of fabricating 'smart' electrically conductive materials. Rheology of the fresh mix is crucial to satisfactory moulding and fresh CFRC conforms to the Bingham model with slight structural breakdown. Both yield stress and plastic viscosity increase with increasing fibre length and volume concentration. Using a modified Viskomat NT, the concentration dependence of CFRC rheology up to 1.5% fibre volume is reported

  14. Microstructures and electrolytic properties of yttrium-doped ceria electrolytes: Dopant concentration and grain size dependences

    International Nuclear Information System (INIS)

    The microstructures and electrolytic properties of Y xCe1-xO2-x/2 (x = 0.10-0.25) electrolytes with average grain size in the range 90 nm-1.7 ?m were systematically investigated. Through detailed transmission electron microscopy characterization, nanosized domains were observed. The relationship of the domains, the doping level and grain sizes were determined, and their impacts on the electrolytic properties were systematically studied. It was found that the formation of domains has a negative impact on the electrolytic properties, so that electrolytic properties can be adjusted through careful control of domain formation, doping level and grain size

  15. Electrical controlled rheology of a suspension of weakly conducting particles in dielectric liquid

    CERN Document Server

    Guegan, Q; Foulc, J N; Tillement, O; Guegan, Quentin

    2006-01-01

    The properties of suspensions of fine particles in dielectric liquid (electrorheological fluids) subjected to an electric field lead to a drastic change of the apparent viscosity of the fluid. For high applied fields (~ 3-5 kV/mm) the suspension congeals to a solid gel (particles fibrillate span the electrode gap) having a finite yield stress. For moderate fields the viscosity of the suspension is continuously controlled by the electric field strength. We have roposed that in DC voltage the field distribution in the solid (particles) and liquid phases of the suspension and so the attractive induced forces between particles and the yield stress of the suspension are controlled by the conductivities of the both materials. In this paper we report investigation and results obtained with nanoelectrorheological suspensions: synthesis of coated nanoparticles (size ~ 50 to 600 nm, materials Gd2O3:Tb, SiOx...), preparation of ER fluids (nanoparticles mixed in silicone oil), electrical and rheological characterization ...

  16. Highly flexible, proton-conductive silicate glass electrolytes for medium-temperature/low-humidity proton exchange membrane fuel cells.

    Science.gov (United States)

    Lee, Hyeon-Ji; Kim, Jung-Hwan; Won, Ji-Hye; Lim, Jun-Muk; Hong, Young Taik; Lee, Sang-Young

    2013-06-12

    We demonstrate highly flexible, proton-conductive silicate glass electrolytes integrated with polyimide (PI) nonwoven fabrics (referred to as "b-SS glass electrolytes") for potential use in medium-temperature/low-humidity proton exchange membrane fuel cells (PEMFCs). The b-SS glass electrolytes are fabricated via in situ sol-gel synthesis of 3-trihydroxysilyl-1-propanesulfonic acid (THPSA)/3-glycidyloxypropyl trimethoxysilane (GPTMS) mixtures inside PI nonwoven substrates that serve as a porous reinforcing framework. Owing to this structural uniqueness, the b-SS glass electrolytes provide noticeable improvements in mechanical bendability and membrane thickness, in comparison to typical bulk silicate glass electrolytes that are thick and easily fragile. Another salient feature of the b-SS glass electrolytes is the excellent proton conductivity at harsh measurement conditions of medium temperature/low humidity, which is highly important for PEMFC-powered electric vehicle applications. This beneficial performance is attributed to the presence of a highly interconnected, proton-conductive (THPSA/GPTMS-based) silicate glass matrix in the PI reinforcing framework. Notably, the b-SS glass electrolyte synthesized from THPSA/GPTMS = 9/1 (mol/mol) exhibits a higher proton conductivity than water-swollen sulfonated polymer electrolyte membranes (here, sulfonated poly(arylene ether sulfone) and Nafion are chosen as control samples). This intriguing behavior in the proton conductivity of the b-SS glass electrolytes is discussed in great detail by considering its structural novelty and Grotthuss mechanism-driven proton migration that is strongly affected by ion exchange capacity (IEC) values and also state of water. PMID:23672268

  17. Solid composite electrolytes for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Binod (Dayton, OH); Scanlon, Jr., Lawrence G. (Fairborn, OH)

    2000-01-01

    Solid composite electrolytes are provided for use in lithium batteries which exhibit moderate to high ionic conductivity at ambient temperatures and low activation energies. In one embodiment, a ceramic-ceramic composite electrolyte is provided containing lithium nitride and lithium phosphate. The ceramic-ceramic composite is also preferably annealed and exhibits an activation energy of about 0.1 eV.

  18. Ionometry in analysis of electrolyte solutions (review)

    International Nuclear Information System (INIS)

    The prospects for using ionometric analysis for analytical control of electrolyte solutions in electroplating baths, pickling solutions, and waste water are considered. The examples of a complete ionometric analysis of electrolytes in electroplating baths, as well as determination of cyanide and other complexes of metals (Cd, B, etc.) are presented. 61 refs., 4 tabs

  19. Electrolyte Additives for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Gang, Xiao; Hjuler, H.A.

    1993-01-01

    Electrochemical characteristics of a series of modified phosphoric acid electrolytes containing fluorinated car on compounds and silicone fluids as additives are presented. When used in phosphoric acid fuel cells, the modified electrolytes improve the performance due to the enhanced oxygen reduction rate. Among useful additives we found potassium perfluorohexanesulfonate (C6F13SO3K), potassium nonafluorobutanesulfonate (C4F9SO3K), perfluorotributylamine [(C4F9)3N], and polymethylsiloxanes [(-Si(CH3)2O-)n]. The wettability of the electrodes by the modified electrolytes also is discussed, as a fuel-cell performance with the modified electrolytes. Specific conductivity measurements of some of the modified phosphoric acid electrolytes are reported. At a given temperature, the conductivity of the C4F9SO3K-modified electrolyte decreases with an increasing amount of the additive; the conductivity of the remains at the same value as the conductivity of the pure phosphoric acid. At a given composition, the conductivity of any modified electrolyte increases with temperature. We conclude that the improved cell performance for modified electrolytes is not due to any increase in conductivity.

  20. Production of ceramic layers on aluminum alloys by plasma electrolytic oxidation in alkaline silicate electrolytes

    Science.gov (United States)

    Lugovskoy, Alex; Zinigrad, Michael; Kossenko, Aleksey; Kazanski, Barbara

    2013-01-01

    Plasma electrolytic oxidation (PEO) of aluminum alloy 5052 in alkaline-silicate electrolytes having different SiO2/Na2O ratios (silicate indexes) was studied. For all the electrolytes 20-90 ?m thick technological layer was obtained; composition, structure and properties of the oxidized layer were studied. For each sample, the oxidized layer consists of a denser internal and looser external sublayer. While for “n = 1 electrolytes” the oxidized layer is mainly formed by several kinds of alumina, the principal constituent of the oxidized layer for “n = 3 electrolytes” is mullite. Measurements of microhardness evidenced that it is apparently not influenced by the kind of silicate (n = 1 or n = 3) and by its concentration in the electrolyte. Electrolytes with silicate index n = 3 ensure better corrosion protection than those with n = 1. Corrosion protection parameters are significantly better for all PEO oxidized samples than for the untreated Al5052 alloy.

  1. Review Of Rheology Models For Hanford Waste Blending

    International Nuclear Information System (INIS)

    The area of rheological property prediction was identified as a technology need in the Hanford Tank Waste - waste feed acceptance initiative area during a series of technical meetings among the national laboratories, Department of Energy-Office of River Protection, and Hanford site contractors. Meacham et al. delivered a technical report in June 2012, RPP-RPT-51652 ''One System Evaluation of Waste Transferred to the Waste Treatment Plant'' that included estimating of single shell tank waste Bingham plastic rheological model constants along with a discussion of the issues inherent in predicting the rheological properties of blended wastes. This report was selected as the basis for moving forward during the technical meetings. The report does not provide an equation for predicting rheological properties of blended waste slurries. The attached technical report gives an independent review of the provided Hanford rheological data, Hanford rheological models for single tank wastes, and Hanford rheology after blending provided in the Meacham report. The attached report also compares Hanford to SRS waste rheology and discusses some SRS rheological model equations for single tank wastes, as well as discussing SRS experience with the blending of waste sludges with aqueous material, other waste sludges, and frit slurries. Some observations of note: Savannah River Site (SRS) waste samples from slurried tanks typically have yield stress >1 Pa at 10 wt.% undissolved solids (UDS), while core samples largely have little or no yield stress at 10 wt.% UDS. This could be due to how the waste has been processed, stored, retrieved, and sampled or simply in the differences in the speciation of the wastes. The equations described in Meacham's report are not recommended for extrapolation to wt.% UDS beyond the available data for several reasons; weak technical basis, insufficient data, and large data scatter. When limited data are available, for example two to three points, the equations are not necessarily satisfactory (justified) for interpolations, due to the number of unknown variables equal the number of known data points, resulting in a coefficient of determination of one. SRS has had some success predicting the rheology of waste blends for similar waste types using rheological properties of the individual wastes and empirical blending viscosity equations. Both the Kendall-Monroe and Olney-Carlson equations were used. High accuracy was not obtained, but predictions were reasonable compared to measured flow curves. Blending SRS processed waste with frit slurry (much larger particles and the source of SRS glass formers) is a different sort of problem than that of two similar slurries of precipitated waste particles. A different approach to rheology prediction has had some success describing the incorporation of large frit particles into waste than the one used for blending two wastes. In this case, the Guth-Simha equation was used. If Hanford waste is found to have significant particles in the >100 ?m diameter range, then it might be necessary to handle those particles differently from broadly distributed waste particles that are primarily <30 ?m in diameter. The following are recommendations for the Hanford tank farms: Investigate the impact of large-scale mixing operations on yield stress for one or more Hanford tanks to see if Hanford waste rheological properties change to become more like SRS waste during both tank retrieval and tank qualification operations; Determine rheological properties of mobilized waste slurries by direct measurement rather than by prediction; Collect and characterize samples during the waste feed qualification process for each campaign; From single source tanks that feed the qualification tanks; Blends from the qualification tanks; Predictive rheological models must be used with caution, due to the lack of data to support such models and the utilization of the results that come from these models in making process decisions (e.g. the lack of actual operation experience). As experience is gained, the use of blen

  2. Comparative study of polymer matrices for gelled electrolytes of lithium batteries; Etude comparative de matrices polymeres pour electrolytes gelifies de batteries au lithium

    Energy Technology Data Exchange (ETDEWEB)

    Du Pasquier, A.; Sarrazin, C.; Fauvarque, J.F. [CNAM, 75 - Paris (France); Andrieu, X. [Alcatel Alsthom Recherche, 91 - Marcoussis (France)

    1996-12-31

    A solid electrolyte for lithium batteries requires several properties: a good ionic conductivity of about 10{sup -3} S/cm at 298 deg. K, a high cationic transport number (greater than 0.5), a redox stability window higher than 4.5 V, a good stability of the interface with the lithium electrode, and a sufficient mechanical stability. The family of gelled or hybrid electrolytes seems to meet all these requirements. Thus, a systematic study of the gelling of an ethylene carbonate and lithium bistrifluorosulfonimide (LiTFSI) based electrolyte has been carried out. The polymers used for gel or pseudo-gel synthesis are POE, PMMA and PAN which represent 3 different cases of interaction with the electrolyte. All the properties mentioned above have been studied according to the nature of the polymer and to the concentration of lithium salt, showing the advantages and drawbacks of each polymer. The possibility of using some of these gels in lithium-ion batteries has been tested by lithium intercalation tests in UF2 graphite at the C/10 regime and by the cycling of LiCoO{sub 2}/UF{sub 2} batteries at the C/5 regime. Interesting performances have been obtained on Li/PPy batteries which can operate at the 7.5 C regime. (J.S.)

  3. LiNi0.5Mn1.5O4 spinel cathode using room temperature ionic liquid as electrolyte

    International Nuclear Information System (INIS)

    In this study, LiNi0.5Mn1.5O4 (LNMO) nanoparticles were prepared as a 5 V cathode material via a rheological phase method and annealed at different temperatures: 680 °C, 750 °C, and 820 °C. The sample annealed at 750 °C shows the best performance. A room temperature ionic liquid (RTIL) containing 1 M lithium bis(trifluoromethanesulfonyl) imide (LiNTf2) in N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl) imide (C4mpyrNTf2) was used as novel electrolyte in conjunction with the LNMO cathodes and their electrochemical properties have been investigated. The results show that the LNMO using RTIL as electrolyte has better coulombic efficiency and comparable discharge capacities to those of the cells assembled with standard liquid electrolyte (1 M LiPF6 in ethylene carbonate/diethyl carbonate). Electrochemical impedance spectroscopy shows that the RTIL is much more stable as the electrolyte for LiNi0.5Mn1.5O4 than the conventional electrolyte

  4. Solid polymer electrolyte from phosphorylated chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Fauzi, Iqbal, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Groups, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24

    Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component’s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it’s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10{sup ?6} S/cm up to 6.01 × 10{sup ?4} S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10{sup ?3} S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.

  5. Solid polymer electrolyte from phosphorylated chitosan

    International Nuclear Information System (INIS)

    Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component’s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it’s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10?6 S/cm up to 6.01 × 10?4 S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10?3 S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications

  6. Solid polymer electrolyte from phosphorylated chitosan

    Science.gov (United States)

    Fauzi, Iqbal; Arcana, I. Made

    2014-03-01

    Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component's composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it's characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10-6 S/cm up to 6.01 × 10-4 S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10-3 S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.

  7. Fluctuation theorems and work relations for single polymer rheology

    Science.gov (United States)

    Latinwo, Folarin Babajide

    Synthetic and biological polymeric materials are ubiquitous in nature and modern technology. The emergent properties afforded by these materials allows for wide a array of applications as found in adhesives, coatings, and synthetic polymers for plastics. Importantly, the molecular properties of polymeric systems ultimately determine their bulk macroscopic response and behavior in equilibrium and highly nonequilibrium conditions. As a result, the field of single polymer rheology can play a key role in establishing a molecular level understanding of polymeric systems by investigating the dynamics of single chains. Single polymer rheology is now a well-established approach to study polymer dynamics from experimental and computational perspectives. In general, this approach allows for the determination of molecular subpopulations, relaxation, and polymer chain dynamics in a wide variety of flows. Despite recent progress, current methods in single polymer rheology do not allow for the determination of equilibrium and nonequilibrium thermodynamic properties of polymeric systems. Moreover, it is challenging to connect backbone dynamics to key macroscopic rheological phenomena. In this context, the impact of single polymer rheology has remained limited for the past two decades. In this thesis, we address these challenges by developing and applying fluctuation theorems and nonequilibrium work relations to the field of single polymer rheology. The discovery of thermodynamic identities known as nonequilibrium work relations (NWRs) and fluctuation theorems (FTs) has catalyzed recent advances in statistical mechanics. In general, work relations provide an unprecedented route to extract fundamental materials properties of equilibrium and nonequilibrium systems. Furthermore, these identities have uncovered a broad range of unexpected and remarkable thermodynamic phenomena, including molecular level violations to the second law of thermodynamics. In the context of rheology and fluid mechanics, thermodynamics plays a key role in the understanding and design of a wide array of processes, including flow-induced phase separation and crystallization. As a result, there is a strong need for new methods to analyze the dynamics of complex fluids. In this thesis, we apply the Jarzynski/Hatano/Sasa equality and Crooks fluctuation theorem to determine equilibrium and nonequilibrium properties of polymer solutions in fluid flow. In particular, we use a combination of single molecule polymer experiments and computer simulations to probe the application of these NWRs to polymer dynamics in shear and extensional flows. Using this approach, we determine the equilibrium linear and nonlinear elasticity, the nonequilibrium free energies, and entropies of flowing polymer solutions. Interestingly, we also find that fundamental thermodynamic quantities are related to well known rheological functions such as the longest polymer relaxation time, viscosity, and stress. Overall, NWRs appear to provide a simple and distinct framework that connects thermodynamics and rheology, and this work opens new directions in an emerging field known as "thermo-rheology".

  8. THERMOPHYSICAL AND RHEOLOGIC PROPERTIES OF BIOOIL SAMPLES

    Directory of Open Access Journals (Sweden)

    Monika Bozikova

    2013-09-01

    Full Text Available This article deals with thermal properties of selected biooils Plahyd S biooil No1 and Plahyd N biooil No2 and rheologic properties of rapeseed oil. Plahyd S is a synthetic, rapidly biodegradable fluid which is based on sustainable raw materials. It is exceptionally suitable for applications in mobile and stationary hydraulic systems. Plahyd N is multigrade hydraulic oil based on rapeseed oil used in agricultural and construction machinery. For thermal parameters measurements was used Hot wire method. The experiment is based on measuring of the temperature rise vs. time evaluation of an electrically heated wire embedded in the tested material. The thermal conductivity is derived from the resulting change in temperature over a known time interval. Dependency of material resistance against the probe rotation was used at measurement of rheologic properties with instrument viscometer Anton Paar DV 3P. For two samples of biooils Plahyd N and Plahyd S were determined basic thermophysical parameters thermal conductivity, thermal diffusivity and volume specific heat. For each biooil samples were made two series of measurements. In the first series were measured thermal conductivity and thermal diffusivity at constant room temperature 20 C. Every thermophysical parameter was measured 10 times for each sample. The results were statistically processed. For biooil No1 thermal conductivity was 0.325 W*m 1 .K1 , it was higher value than we obtained for biooil No2 0.224 W*m 1 .K 1 . The similar results were obtained for thermal diffusivity of biooil No1 2.140.10 7 m 2 *s 1 and biooil No2 2.604.10 7 m 2* s 1 . For samples with constant temperature were calculated basic statistical characteristics as standard deviation for biooil No1 0.056 W*m 1*K 1 and biooil No2 0.054 W*m 1*K 1; probable error of the arithmetic average for biooil No 1 0.012 W*m 1*K 1 and biooil No 2 0.005 W*m 1*K 1, relative probable error in for biooil No1 3.69 per cent and biooil No2 2.23. The same statistical characteristics were calculated for thermal diffusivity. In the second series of measurements were measured relations of thermal conductivity and thermal diffusivity to the temperature in temperature range 20 29 C. From results was evident that all measured dependencies are nonlinear. For both thermophysical parameters were obtained polynomial functions of the second degree described by the polynomial coefficients. Type of function was selected according to statistical evaluation based on the coefficient of determination for every thermophysical parameter graphical dependency. In temperature dependency of rapeseed oil dynamic viscosity was used decreasing exponential function, which is in accordance with Arrhenius equation. The results obtained by the implementation of thermophysical and rheologic measurements on samples of biooils could be compared with the values presented in the literature.

  9. High-temperature electrochemical synthesis of zirconium diboride in halide melts

    International Nuclear Information System (INIS)

    To evaluate potentiality of high-temperature electrochemical synthesis of zirconium diboride a study using the method of voltammetry of zirconium electrochemical behaviour in the melt KCl-NaCl-Na-F-K2ZrF6 is carried out, the mechanism of zirconium diboride synthesis during joint reduction of zirconium and boron complexes in the melts of chloride-fluoride electrolytes being analyzed. It is ascertained that formation of zirconium(4) and boron(3) joint complexes controlling the electrode process precedes electrochemical synthesis of zirconium diboride. Compositions of electrolytes and electrolysis conditions for practical realization of high-temperature electrochemical synthesis of zirconium diboride powders and coatings are determined

  10. Rheological Characterization of Drag-Reducing Fluids.

    Science.gov (United States)

    Vlassopoulos, Dimitris

    The efficient design and commercialization of processes involving flow of dilute polymer solutions are based on a fundamental understanding of the complex rheological behavior of these fluids. Of particular importance are situations associated with the drag reduction phenomenon, because of the potential for significant energy savings. In this research the important rheological characteristics of dilute polymer solutions are investigated in ways that are meaningful for applications to drag reducing conditions. The approach used is an alternative to conventional viscometric techniques, which are unsuccessful in measuring elastic properties of such fluids. The steady streaming flow, manifested by fluid nonlinearities, is employed as a model nonviscometric flow for studying the response of polymer solutions. Flow reversal and several common features with turbulence, make this flow particularly interesting for non-Newtonian fluids. Fluid elasticity is determined by measuring the steady streaming velocity profiles and then fitting theoretical predictions to data, which reveals the relevant relaxation times. The Maxwell and Oldroyd models are employed, as special cases of a generalized Giesekus model, involving Gordon-Schowalter derivatives. The special features of these derivatives were found to have no effect on steady streaming. The experimental system is based on laser Doppler velocimetry and a photographic technique. The polymers are well characterized aqueous solutions of polyacrylamide or polyethylene oxide. Results show that elasticity increases with concentration or frequency. They also prove that the models used can adequately describe the features of steady streaming. A comparison with pipe flow experiments reveals an interesting correlation between elasticity and drag reduction, which suggests that ranking polymers according to their elasticity provides sufficient information on their drag reducing effectiveness. The relaxation times from this work seem to be more appropriate in characterizing polymer response in drag reducing flows, than the "longest relaxation time", estimated from viscometry. No stretching occurs as a result of the primary flow. Of special interest are surfactants, because of their shear and thermal stability. Aqueous mixtures of cetyltrimethylammonium bromide and sodium salicylate are found to behave like polymers. Therefore, the elasticity -drag reduction correlation holds for surfactants as well. No evidence of flow-induced structure is found.

  11. Rheological Characterization of Foamy Oils under Pressure

    Science.gov (United States)

    Abivin, Patrice; Henaut, Isabelle; Moan, Michel; Argillier, Jean-Francois

    2008-07-01

    Heavy oils are a strategic source of hydrocarbons due to the large amount of reserves located mainly in Venezuela and Canada. They distinguish from conventional oils by their higher density and viscosity. When a reservoir is depleted, the lightest components (methane, ethane, etc.) can exsolve from the crude oil and create a gaseous phase. In conventional oils, bubbles grow and coalesce quickly. On the contrary, in heavy oils, bubbles are small and remain dispersed within the oil for a long time. This "foamy oil" phenomenon changes drastically the flow properties of the crude oil. This article is devoted to the characterization of the heavy oil foamy behavior through a rheological study. Our objectives are to study the kinetics of bubble evolution in heavy oil and to measure their influence on viscosity. A new experimental method was developed, based upon rheological measurements under pressure. Several heavy oils containing dissolved gas have been depleted inside the pressure cells of controlled stress rheometers to create foamy oils. Viscoelastic properties have been continuously measured using both oscillatory and continuous tests from the nucleation up to the total disengagement of bubbles from oil. The occurrence of bubbles was visualized using X-ray scanning experiments. Results demonstrate that foamy oil kinetics is mostly related to the oil viscosity. They also reveal that under low shear rates, the presence of bubbles leads to an increase in heavy oil viscosity, as predicted by the Hard Sphere Model or by Taylor's one. A theoretical model describing the viscosity of foamy oil was then established. It takes into account both first-order kinetics of appearance and release of bubbles in oil and a basic suspension model. Good agreement was obtained between experimental data and model predictions. Finally, several tests reveal the strong influence of the shear rate on the foamy oil behavior and point out the major role of bubble deformation on the viscosity of foamy oils, as shown previously in other viscous materials such as magmas and melt polymers. Under high shear rates, we suggest that the stabilization of the elongated bubbles in oil leads to the establishment of an anisotropic material, which can be seen as a sandwich-like structure. As a result, the viscosity appears lower in the direction of the deformed bubbles.

  12. Synthesis and characterization of partially fluorinated poly(acryl) ionomers for polymer electrolyte membrane fuel cells and ESR-spectroscopic investigation of the radically induced degradation of model compounds; Synthese und Charakterisierung teilfluorierter Poly(acryl)-Ionomere als Polymerelektrolytmembranen fuer Brennstoffzellen und ESR-spektroskopische Untersuchung der radikalinduzierten Degradation von Modellverbindungen

    Energy Technology Data Exchange (ETDEWEB)

    Schoenberger, Frank

    2008-07-09

    In the first part of this work different strategies for the design of sulfonated partially fluorinated poly(aryl)s are developed and synthetically realized. The applied concept is that partially fluorinated poly(aryl)s are distinguished from the nonfluorinated ones by an enhanced acidity. Moreover they possess higher bond dissociation energies of both the C-F bonds and any adjacent C-H bonds which should be associated with a gain in radical stability and thus in chemical and thermal stability. In order to investigate the influence of the chemical structure of (partially fluorinated) monomeric building blocks, homo-polymers with different structural units (with aromatic C-F bonds, C(CF3)2-bridged and/or CF3-substituted phenylene rings) are synthesized by polycondensation and structurally characterized (elemental analysis, NMR spectroscopy, gel permeation chromatography). Established organic reactions, such as the Balz-Schiemann reaction, Suzuki reaction and Ullmann's biaryl synthesis, are applied for the synthesis of the specific monomers. After sulfonation of the homo-polymers (ionically crosslinked) membranes are prepared and characterized in terms of suitability as polymer electrolyte membrane in fuel cells (ion-exchange capacity, proton conductivity, thermal and chemical stability, water uptake, dimensional change). Both the chemical nature of the monomers and their constitution in the ionomer are important for the properties of the resulting membranes. Therefore microphase-separated multiblock-co-ionomers based on hydrophilic (sulfonated) and hydrophobic (partially fluorinated) telechelic macromonomers are prepared and characterized. Both the influence of the block length and the chemical nature of the used monomers on the membrane properties are comparatively investigated. On the basis of the findings gained in this part of the work, the advantages and disadvantages of partially fluorinated ionomer membranes are analyzed and discussed. The second part of this work deals with the EPR-spectroscopic investigation of radically induced degradation reactions of model compounds which represent structural units of poly(aryl) ionomers prepared in the first part of this work. These model compounds are exposed to hydroxyl and hydroperoxyl radicals in a flow cell, which are generated directly by photolysis of hydrogen peroxide in the cavity of an ESR spectrometer. By using this experimental setup different parameters (such as concentration of hydroxyl radicals, monomer concentration, flow rate, and pH value) are varied systematically and their influences in terms of the observed product formation of the aromatic model compounds with the hydroxyl radicals are estimated. Conclusions in terms of possible radical reactions of the poly(aryl) ionomer can be drawn from these investigations and information of avoidable structural features (e.g. type of the end groups of the ionomers) and avoidable conditions (e.g. inhomogeneities of pH values in the membrane) are obtained. (orig.)

  13. Impact of Rheological Modifiers on Various Slurries Supporting DOE Waste Processing

    International Nuclear Information System (INIS)

    Controlling the stability and subsequent rheological properties of slurries has been an important but challenging issue in nuclear waste treatment, one that previous research has yet to sufficiently address. At the Hanford and Savannah River sites, operation of the waste treatment facilities at increased solids loading reduces the evaporative load on the melter systems and thereby increases waste processing rates. However, at these higher solids loadings, increased slurry rheology becomes a significant processing issue. The current study evaluates the use of several rheological modifiers to alleviate increased slurry rheology at high waste solids concentrations. Rheological modifiers change particle interactions in slurry. For colloidal slurries, modifiers mainly alter the electrostatic and steric interactions between particles, leading to a change in slurry rheology. Weak organic acid type rheological modifiers strengthen electrostatic repulsion whereas nonionic/polymer surfactant type rheological modifiers introduce a steric repulsion. We investigated various rheological modifiers using high level waste (HLW) nuclear waste simulants characterized typically by high ionic strength and a wide range of pH from 4 to 13. Using rheological analysis, it was found that citric acid and polyacrylic acid would be good rheological modifiers for the HLW simulants tested, effectively reducing slurry rheology by 40% or more. Physical insights into the mechanisms driving stabilizatits into the mechanisms driving stabilization by these rheological modifiers will be discussed.

  14. New electrolytes and electrolyte additives to improve the low temperature performance of lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiao-Qing

    2008-08-31

    In this program, two different approaches were undertaken to improve the role of electrolyte at low temperature performance - through the improvement in (i) ionic conductivity and (ii) interfacial behavior. Several different types of electrolytes were prepared to examine the feasibil.ity of using these new electrolytes in rechargeable lithium-ion cells in the temperature range of +40°C to -40°C. The feasibility studies include (a) conductivity measurements of the electrolytes, (b) impedance measurements of lithium-ion cells using the screened electrolytes with di.fferent electrochemical history such as [(i) fresh cells prior to formation cycles, (ii) after first charge, and (iii) after first discharge], (c) electrical performance of the cells at room temperatures, and (d) charge discharge behavior at various low temperatures. Among the different types of electrolytes investigated in Phase I and Phase II of this SBIR project, carbonate-based LiPF6 electrolytes with the proposed additives and the low viscous ester as a third component to the carbonate-based LiPF6 electrolytes show promising results at low temperatures. The latter electrolytes deliver over 80% of room temperature capacity at -20{degrees}C when the lithium-ion cells containing these electrolytes were charged at -20 °C. Also, there was no lithium plating when the lithium­-ion cells using C-C composite anode and LiPF{sub 6} in EC/EMC/MP electrolyte were charged at -20{degrees}C at C/5 rate. The studies of ionic conductivity and AC impedance of these new electrolytes, as well as the charge discharge characteristics of lithium-ion cells using these new electrolytes at various low temperatures provide new findings: The reduced capacity and power capability, as well as the problem of lithium plating at low temperatures charging of lithium-ion cells are primarily due to slow the lithium-ion intercalation/de-intercalation kinetics in the carbon structure.

  15. Catalyzed electrolytic plutonium oxide dissolution

    International Nuclear Information System (INIS)

    Catalyzed electrolytic plutonium oxide dissolution (CEPOD) was first demonstrated at Pacific Northwest Laboratory (PNL) in early 1974 in work funded by the Exxon Corporation. The work, aimed at dissolution of Pu-containing residues remaining after the dissolution of spent mixed-oxide reactor fuels, was first publicly disclosed in 1981. The process dissolves PuO2 in an anolyte containing small (catalytic) amounts of elements that form kinetically fast, strongly oxidizing ions. These are continuously regenerated at the anode. Catalysts used, in their oxidized form, include Ag2+, Ce4+, Co3+, and AmO22+. This paper reviews the chemistry involved in CEPOD and the results of its application to the dissolution of the Pu content of a variety of PuO2-containing materials such as off-standard oxide, fuels dissolution residues, incinerator ash, contaminated soils, and other scraps or wastes. Results are presented for both laboratory-scale and plant-scale dissolves

  16. Rheological studies of polysaccharides for skin scaffolds.

    Science.gov (United States)

    Almeida, Nalinda; Mueller, Anja; Hirschi, Stanley; Rakesh, Leela

    2014-05-01

    Polysaccharide hydrogels are good candidates for skin scaffolds because of their inherent biocompatibility and water transport properties. In the current study, hydrogels were made from a mixture of four polysaccharides: xanthan gum, konjac gum, iota-carrageenan, and kappa-carrageenan. Gel formation, strength, and structure of these polysaccharides were studied using rheological and thermal techniques. All gel samples studied were strong gels at all times because of the gradual water loss. However, after 12 h of storage, elastic (G') and loss (G'') moduli of hydrogel mixture containing all the ingredients is of one to two orders of magnitude greater than that of mixtures not containing either xanthan gum or iota-carrageenan, which confirmed the varied levels of gel strength. This is mainly due to the rate of water loss in each of these mixtures, resulting in gels of varying structures and dynamic moduli over a period of time. Iota-carrageenan and xanthan gum differ in their effect on gel strength and stability in combination with konjac gum and kappa-carrageenan. PMID:23703897

  17. Influence of Fat Content on Chocolate Rheology

    Science.gov (United States)

    Gabriele, D.; Migliori, M.; Baldino, N.; de Cindio, B.

    2008-07-01

    Molten chocolate is a suspension having properties strongly affected by particle characteristics including not only the dispersed particles but also the fat crystals formed during chocolate cooling and solidification. Even though chocolate rheology is extensively studied, mainly viscosity at high temperature was determined and no information on amount and type of fat crystals can be detected in these conditions. However chocolate texture and stability is strongly affected by the presence of specific crystals. In this work a different approach, based on creep test, was proposed to characterize chocolate samples at typical process temperatures (approximately 30 °C). The analysis of compliance, as time function, at short times enable to evaluate a material "elasticity" related to the solid-like behavior of the material and given by the differential area between the Newtonian and the experimental compliance. Moreover a specific time dependent elasticity was defined as the ratio between the differential area, in a time range, and total area. Chocolate samples having a different fat content were prepared and they were conditioned directly on rheometer plate by applying two different controlled cooling rate; therefore creep were performed by applying a low stress to ensure material linear behavior. Experimental data were analyzed by the proposed method and specific elasticity was related to single crystal properties. It was found that fat crystal amount and properties depend in different way on fat content and cooling rate; moreover creep proved to be able to detect even small differences among tested samples.

  18. Rheological and fractal hydrodynamics of aerobic granules.

    Science.gov (United States)

    Tijani, H I; Abdullah, N; Yuzir, A; Ujang, Zaini

    2015-06-01

    The structural and hydrodynamic features for granules were characterized using settling experiments, predefined mathematical simulations and ImageJ-particle analyses. This study describes the rheological characterization of these biologically immobilized aggregates under non-Newtonian flows. The second order dimensional analysis defined as D2=1.795 for native clusters and D2=1.099 for dewatered clusters and a characteristic three-dimensional fractal dimension of 2.46 depicts that these relatively porous and differentially permeable fractals had a structural configuration in close proximity with that described for a compact sphere formed via cluster-cluster aggregation. The three-dimensional fractal dimension calculated via settling-fractal correlation, U?l(D) to characterize immobilized granules validates the quantitative measurements used for describing its structural integrity and aggregate complexity. These results suggest that scaling relationships based on fractal geometry are vital for quantifying the effects of different laminar conditions on the aggregates' morphology and characteristics such as density, porosity, and projected surface area. PMID:25836036

  19. Rheology of cement mixtures with dolomite filler

    Directory of Open Access Journals (Sweden)

    Martínez de la Cuesta, P. J.

    2000-06-01

    Full Text Available This experimental program has studied the behavior of fresh paste made up from cements mixed with dolomite filler. Through prior experiments the starting point is obtained for the designs 22 and 23 factorials. With these designs the governing equations are established that influence the specific surface of the filler, the filler percentage and the ratio water/(cement + filler, used as objective functions: test probe penetration, flow on table and shear stress in viscometer. Also the type of rheological conduct is determined and the influence over initial and final setting is observed.

    Este programa experimental estudia el comportamiento de las pastas frescas fabricadas a partir de cementos mezclados con filler dolomítico. En los experimentos previos se obtiene el punto central para los diseños 22 y 23 factoriales. Con estos diseños se establecen las ecuaciones que rigen la influencia de la superficie específica del filler, el porcentaje de filler y la relación agua/(cemento + filler, utilizando como funciones objetivos la penetración de sonda, la mesa de sacudidas y la tensión de corte en el viscosímetro. También se determina el tipo de conducta reológica y la influencia sobre el principio y fin de fraguado.

  20. Foam rheology: a model of viscous phenomena

    International Nuclear Information System (INIS)

    A theoretical model for foam rheology that includes viscous forces is developed by considering the deformation of two-dimensional, spatially periodic cells in simple shearing and planar extensional flow. The undeformed hexagonal cells are separated by thin liquid films. Plateau border curvature and liquid drainage between films is neglected. Interfacial tension and viscous tractions due to stretching lamellar liquid determine the individual film tensions. The network motion is described by a system of nonlinear ordinary differential equations for which numerical solutions are obtained. Coalescense and disproportionation of Plateau borders results in the relative separation of cells and provides a mechanism for yielding and flow. This process is assumed to occur when a film's length reduces to its thickness. The time and position dependence of the cell-scale dynamics are computed explicitly. The effective continuum stress of the foam is described by instantaneous and time-averaged quantities. The capillary number, a dimensionless deformation rate, represents the relative importance of viscous and surface tension effects. The small-capillary-number or quasistatic response determines a yield stress. The dependence of the shear and normal stress material functions upon deformation rate, foam structure and physical properties is determined. A plausible mechanism for shear-induced material failure, which would determine a shear strength, is revealed for large capillary numbngth, is revealed for large capillary numbers. The mechanism involves large cell distortion and film thinning, which provide favorable conditions for film rupture

  1. Predictability of Complex Modulus Using Rheological Models

    Directory of Open Access Journals (Sweden)

    N.I.Md. Yusoff

    2010-01-01

    Full Text Available The objective of this study was to investigate the advantages and disadvantages of several linear visco-elastic rheological models applied to the unmodified and polymer-modified bitumens. It was found that all the models studied can be used to predict the linear visco-elastic of unmodified bitumens, aged and unaged samples reasonably well. In contrary, this condition was not really applicable on polymer-modified bitumens particularly for the unaged samples. The measured and predicted data was assessed using the discrepancy ratio (Ri, Mean Normalized Error (MNE and Average Geometric Deviation (AGD goodness of fitting statistical analysis. From the study, the modified Sigmoidal and Generalized Logistic Sigmoidal models were observed to be the most outstanding models, followed by the Christensen Anderson and Marasteanu (CAM, Christensen and Anderson (CA and 2S2P1D (2 springs, 2 parabolic elements and 1 spring models. The presence of semi-crystalline waves and elastomeric structures in the mixtures render the breakdown of time temperature equivalency principle.

  2. Microfluidic Rheology of Soft Colloidal Suspensions

    Science.gov (United States)

    Nordstrom, Kerstin; Arratia, Paulo; Verneuil, Emilie; Gollub, Jerry; Durian, Douglas

    2008-11-01

    The rheology of a suspension of soft colloidal particles is investigated using a pressure-driven flow in a deep 25 ?m wide microchannel. The system is composed of N-isopropylacrylamide (NIPA), colloidal microgel particles, suspended in aqueous solution. NIPA is temperature-sensitive in that the hydrodynamic radius of a particle decreases as temperature increases [1]. Therefore, colloidal suspensions of different packing fraction can be obtained simply by varying the temperature using a temperature-controlled stage. We determine the velocity profile and the local shear rate of the suspension using particle image velocimetry (PIV). We have developed methods to accurately infer the suspension shear viscosity and shear stress as a function of shear rate. The dynamical range of shear rates probed is approximately 5 orders of magnitude, ranging from 10-3 to 10^2 s-1. Results show that as the packing fraction is increased towards the jamming point, the velocity profiles are markedly non-Newtonian. Further, near the jamming point, the stress versus shear rate curves show yield stress behavior. [1] Alsayed, A.M., Islam, M.F., Zhang, J., Collings, P.J., Yodh, A.J., Science 309, 1207.-1210 (2005)

  3. Rheology of Soft Suspensions near Jamming

    Science.gov (United States)

    Nordstrom, Kerstin; Verneuil, Emilie; Arratia, Paulo; Gollub, Jerry; Durian, Douglas

    2009-03-01

    The rheology of a suspension of soft colloidal particles is investigated using a pressure-driven flow in a deep 25 ?m wide microchannel. The system is composed of N-isopropylacrylamide (NIPA) colloidal microgel particles, suspended in aqueous solution. NIPA is temperature-sensitive in that the hydrodynamic radius decreases as temperature increases [1]. Therefore, colloidal suspensions of different packing fraction can be obtained simply by varying the temperature using a temperature-controlled stage. We determine the velocity profile and the local shear rate of the suspension using particle image velocimetry (PIV). We have developed methods to accurately infer the suspension shear viscosity and shear stress as a function of shear rate. The dynamical range of shear rates probed is approximately 5 orders of magnitude, ranging from 10-4 to 10^1 s-1. Results show that as the packing fraction is increased towards the jamming point, the velocity profiles are markedly non-Newtonian. Further, above the jamming point, the stress versus shear rate curves show yield stress behavior. [1] Alsayed, A.M.;Islam, M.F.;Zhang, J.;Collings, P.J.;Yodh, A.J., Science 2005.

  4. Rheological profiles in the Central- Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    E. Mantovani

    1997-06-01

    Full Text Available Seismological investigations have provided an estimate of the gross structnral features of the crust/upper mantle system in the Mediterranean area. However, this information is only representative of the short-term me- chanical behaviour of rocks and cannot help us to understand slow deformations and related tectonic processes on the geological time scale. In this work strength envelopes for several major structural provinces of the Mediterranean area have been tentatively derived from seismological stratification and heat flow data, on the assumption of constant and uniforrn strain rate (10-16 S-1, wet rocks and conductive geotherm. It is also shown how the uncertainties in the reconstruction of thermal profiles can influence the main rheological prop- erties of the lithosphere, as thickness and total strength. The thickest (50-70 km and strongest mechanical lithospheres correspond to the coldest zones (with heat flow lower than or equal to 50 mW m-2, i.e., the Io- nian and Levantine mesozoic basins, the Adriatic and Eurasian foreland zones and NW Greece. Heat flows larger than 65 mW m-2, generally observed in extensional zones (Tyrrhenian, Sicily Channel, Northern Aegean, Macedonia and Western Turkey, are mostly related to mechanical lithospheres thinner than 20 km. The characteristics of strength envelopes, and in particular the presence of soft layers in the crust, suggest a reasonable interpretation of some large-scale features which characterize the tectonic evolution of the Central- Eastem Mediterranean.

  5. Rheological properties of asphalts with particulate additives

    Energy Technology Data Exchange (ETDEWEB)

    Shashidhar, N. [EBA Engineering, Baltimore, MD (United States); Chollar, B.H. [Federal Highway Administration, McLean, VA (United States)

    1996-12-31

    The Superpave asphalt binder specifications are performance-based specifications for purchasing asphalt binders for the construction of roads. This means that the asphalt is characterized by fundamental material (rheological) properties that relate to the distress modes of the pavements. The distress modes addressed are primarily rutting, fatigue cracking and low temperature cracking. For example, G*/sin({delta}) is designed to predict the rutting potential of pavements, where G* is the magnitude of the complex shear modulus and 6 is the phase angle. The binder for a road that is situated in a certain climatic zone requires the binder to have a minimum G*/sin({delta}) of 2200 Pa at the highest consecutive 7-day average pavement temperature the road had experienced. Implicit in such a performance based specification is that the fundamental property, G*/sin({delta}), of the binder correlates with rutting potential of the pavement regardless of the nature of the binder. In other words, the specification is transparent to the fact that the binder can simply be an asphalt, or an asphalt modified by polymers, particulates and other materials that can form a two-phase mixture. This paper discusses the asphalt-particulate system.

  6. Rheology and Gelling Behavior of Boehmite Sols

    Directory of Open Access Journals (Sweden)

    Eng-Seng Chan

    2011-01-01

    Full Text Available Rheological studies of boehmite sols based on pH was (1 to study the nature of flow properties of the boehmite sols and (2 to identify the sol-gel transition of boehmite sols with the change of pH of the liquid. It is evident that the shear rate and viscosity of the liquid exhibit a pseudoplastic (shear thinning flow behavior for all pH level. The transformation of sol-gel at low pH probably due to the hydrogen bond between the layers of the boehmite structure. The temperature has an appreciable effect on the activation energy during the sol-gel transition. The flow activation energies ?E? are in the range of 1.75 to 6.25 J mol-1 at temperature 298-384 K. Based on these results, the flow activation energy of boehmite sols sharply decreases with decreasing the pH. The flocculation of the suspension at pH 4 to 1 showed to be favourable in term of enhanced density of boehmite.

  7. Rheological Properties of Barley and Flaxseed Composites

    Directory of Open Access Journals (Sweden)

    George. E. Inglett

    2013-01-01

    Full Text Available The newly developed barley-flaxseed composites were unique because barley provides the soluble fiber ?-glucan that is beneficial for improving food texture and preventing coronary heart disease along with the health benefits of omega-3 polyunsaturated fatty acids (w-3 PUFAs of flaxseed. The new composites of barley with flaxseeds were prepared using prowashonupana, a barley variety containing high ?-glucan content, with 10, 20, and 50% flaxseed for enhancing health benefits of functional food. Besides the nutritional aspects of barley-flaxseed composites, they have improved water holding capacities, texture, and useful pasting and viscoelastic qualities measured using a Rapid Visco Analyzer (RVA followed by an advanced rheometer. The pasting and rheological properties of the barley flour were not greatly influenced by 10% ground flaxseed replacements but showed differences at the 50% replacement level. Shear thinning properties were observed for all the composites. These functional composites could be valuable and applicable for developing new functional food products with health benefits of decreasing heart problems, diabetes, and obesity along with providing desirable texture.

  8. Effects of ioxaglate to blood rheology

    International Nuclear Information System (INIS)

    Almen and Aspelin have shown that the use of non-ionic radio contrast media allows to increase the iodine concentration (which is desirable because of its effect on radio opacity) without a very large increase in osmolarity (which is undesirable because it impaires the fluidity of erythrocytes). This latter effect can also be diminished by reducing the osmolarity of a dimeric contrast medium as it has been achieved by incorporating more iodine atoms into the molecule in the case of Ioxaglate (Hexabrix). In various microrheological test systems, the fluidity of packed red cell suspension, the corrected filtration rate though 5 ?m pores and the relative apparent viscosity of blood - contrast media mixtures (1 to 50% concentration) were determined in experiments comparing this compound with Urografin 76 of the same iodine content. In all systems, the former showed lesser rheological effects. In whole blood viscometry, this can be detected only after appropriate corrections for the effects of the two contrast media on hematocrit and plasma viscosity. Owing to a more pronounced water shift from the cells to the plasma, Urografin tends to reduce the viscosity of the plasma-contrast media mixture. The concomitant reduction in MCV and hematocrit level tends to screen the macrorheological effect of the dehydrated cells becomes immediately obvious when the viscometric data are corrected for hematocrit value and plasma viscosity effects. (orig.) (orig.)

  9. The distinctive CFD challenges of computational rheology

    Science.gov (United States)

    Walters, K.; Webster, M. F.

    2003-10-01

    In this general lecture, we shall first outline the way computational non-Newtonian fluid mechanics differs from conventional computational fluid dynamics (CFD). We do this by briefly outlining the major historical developments in this relatively new field of science, which is conveniently called Computational Rheology. To illustrate essential features, we limit the discussion to the Oldroyd B, UCM and Phan-Thien/Tanner constitutive models. In order to provide a serious challenge to existing numerical codes, we describe some recent unpublished experimental results on flow through a contraction of constant viscosity (Boger) and also shear-thinning elastic liquids. Both planar and axisymmetric contractions are of interest, and pressure drops and observed flow structures provide the relevant points of contact between experiment and numerical prediction. Numerical codes developed at UWS involving a hybrid finite-element/finite-volume scheme for Oldroyd B and Phan-Thien/Tanner constitutive models are applied to the contraction-flow problems and an encouraging agreement is demonstrated between theory and experiment. Specifically, the dramatic experimental differences between flow in planar and axisymmetric contractions and between constant viscosity and shear-thinning polymer solutions are mirrored in the numerical predictions, at least in a qualitative sense. Notwithstanding these encouraging developments, the review ends with a realistic assessment of the challenges still awaiting computational rheologists, with particular reference to the choice of constitutive model and the possibility of further refinements to the numerical techniques.

  10. Rheological properties of cold recycled mixtures

    Directory of Open Access Journals (Sweden)

    Ján Gillinger

    2007-04-01

    Full Text Available The paper presents some of the results of research focused on cold recycled mixtures properties. Within the study, eight mixtures with a different amount of reclaimed asphalt, bitumen emulsion and cement were evaluated. The results of static creep, complex modulus and fatigue conducted on trapezoidal specimens are discussed in the paper. The static creep modulus and the complex modulus were investigated at temperatures 27 ºC, 11 ºC and 0 ºC. These temperatures represent temperatures of asphalt layer with a thickness in the range from 20 to 25 cm for summer, spring/ autumn and winter in Slovakia. In addition fatigue was investigated at the temperature of 27 ºC. It was found that the binder combination plays an important role in rheological performance of cold recycled mixtures. However, at different contents of reclaimed asphalt, the effect of bitumen emulsion was different. This can be observable particularly when analyzing the results of the fatigue test. The mixtures with a higher amount of cement were better in terms of the fatigue life. The investigated mixtures in general were little sensitive to the change of loading frequency which simulates the traffic speed.

  11. Polymeric ionic liquid and carbon black composite as a reusable supporting electrolyte: modification of the electrode surface.

    Science.gov (United States)

    Yoo, Seung Joon; Li, Long-Ji; Zeng, Cheng-Chu; Little, R Daniel

    2015-03-16

    One of the major impediments to using electroorganic synthesis is the need for large amounts of a supporting electrolyte to ensure the passage of charge. Frequently this causes separation and waste problems. To address these issues, a polymeric ionic liquid-Super?P carbon black composite has been formulated. The system enables electrolyses to be performed without adding an additional supporting electrolyte, and its efficient recovery and reuse. In addition, the ability of the composite to modify the electrode surface in?situ leads to improved kinetics. A practical consequence is that one can decrease catalyst loading without sacrificing efficiency. PMID:25619992

  12. Heavy water recovery from combined electrolytic and non-electrolytic hydrogen streams

    International Nuclear Information System (INIS)

    A method is described for heavy water recovery as a valuable by-product from combined electrolytic and non-electrolytic hydrogen streams. The process is based on an important modification of the Combined Electrolysis and Catalytic Exchange-Heavy Water Process (CECE-HWP). The CECE-HWP is now in the small pilot plant stage of development. A highly dispersed platinum-carbon-Teflon catalyst on a ceramic carrier achieves efficient deuterium exchange between hydrogen gas and liquid water. The range of acceptable ratios of electrolytic to non-electrolytic hydrogen which may be chosen in the Modified CECE-HWP is discussed. Bench-scale results are presented which clearly demonstrate recovery of heavy water from both the electrolytic and non-electrolytic hydrogen streams. The potential application of the process to ammonia production is discussed and other possible applications are mentioned briefly. Advantages of adopting the process are outlined, including the important benefit of conserving fossil resources. (author)

  13. Determination of rheological properties using hybrid optimisation method

    Directory of Open Access Journals (Sweden)

    B. Foder

    2012-12-01

    Full Text Available Purpose: of this paper is description of special software developed for identification of parameters values of rheological models used by ProCAST package for simulation of state of stress in the solidifying castings.Design/methodology/approach: The PyTensionTest uses a hybrid optimization algorithm. This algorithm includes the stochastic method which searches the starting point for direct search optimization method. The identification of parameters values is based on measurement results obtained within the confines of the material tests carried out using the testing machine.Findings: This paper presents the results of approximation of stress-strain relationship for two grades of steel using the elasto-plastic rheological model with power law hardening where its parameters are linearly dependent on temperature.Research limitations/implications: This paper presents the special software that allows user to define any rheological model.Practical implications: Application of obtained values of rheological parameters in the ProCAST software allows to determine stress and strain distribution in continuous castings. It can help to optimize important process parameters.Originality/value: Developed software can approximate the results of static tension tests using rheological model depended on material temperature. This software makes possible an approximation of several stressstrain curves simultaneously. Application of the hybrid optimization method allows to obtain very precise approximation due to determination of the global minimum of the goal function.

  14. Rheological properties of crumb rubber modified bitumen containing antioxidant

    International Nuclear Information System (INIS)

    Rheology has become a useful tool in the characterization of the bitumen performance on the pavement. Visco-elastic properties of crumb rubber modified bitumen with antioxidants (CR30) were determined by the means of rheological measurement. This measurement led to a better knowledge of bitumen behavior that occurs when subjected to different thermal and mechanical conditions, as seen during road construction and services in the field. Dynamic Shear Rheometer (DSR) was used to characterize the rheology of the binders before and after oven aging. The binders were aged for 3 and 9 days. Results of a compatibility test showed that the addition of CR30 modified bitumen is compatible with the base bitumen. The results of unaged samples indicated that the addition of 1% CR30 and 5% CR30 modified binders caused an increase in G value as a result of the rheological changes. Results showed that aging has significant influence on bitumen rheology, by increasing complex modulus and decreasing phase angle. (author)

  15. Single-ion conducting polymer-silicate nanocomposite electrolytes for lithium battery applications

    International Nuclear Information System (INIS)

    Solid-state polymer-silicate nanocomposite electrolytes based on an amorphous polymer poly[(oxyethylene)8 methacrylate], POEM, and lithium montmorillonite clay were fabricated and characterized to investigate the feasibility of their use as 'salt-free' electrolytes in lithium polymer batteries. X-ray scattering and transmission electron microscopy studies indicate the formation of an intercalated morphology in the nanocomposites due to favorable interactions between the polymer matrix and the clay. The morphology of the nanocomposite is intricately linked to the amount of silicate in the system. At low clay contents, dynamic rheological testing verifies that silicate incorporation enhances the mechanical properties of POEM, while impedance spectroscopy shows an improvement in electrical properties. With clay content ?15 wt.%, mechanical properties are further improved but the formation of an apparent superlattice structure correlates with a loss in the electrical properties of the nanocomposite. The use of suitably modified clays in nanocomposites with high clay contents eliminates this superstructure formation, yielding materials with enhanced performance

  16. Rheological Measurement of Waxy Crude Oil under Controlled Stress Rheometer: Determination of the Setting Parameters

    OpenAIRE

    Petrus, T. B.; Azuraien, J.

    2014-01-01

    Rheological measurements are essential in transporting crude oil, especially for waxy crude oil. A lot of rheological measurements have been conducted to determine various rheological properties of crude oil including the viscosity, yield strength, Wax Appearance Temperature (WAT), Wax Disappearance Temperature (WDT), storage modulus and loss modulus, amongst others, by using a controlled stress rheometer. However, a standard procedure to determine the correct parameters for rheological measu...

  17. Highly Quantitative Electrochemical Characterization of Non-Aqueous Electrolytes & Solid Electrolyte Interphases

    Energy Technology Data Exchange (ETDEWEB)

    Sergiy V. Sazhin; Kevin L. Gering; Mason K. Harrup; Harry W. Rollins

    2012-10-01

    The methods to measure solid electrolyte interphase (SEI) electrochemical properties and SEI formation capability of non-aqueous electrolyte solutions are not adequately addressed in the literature. And yet, there is a strong demand in new electrolyte generations that promote stabilized SEIs and have an influence to resolve safety, calendar life and other limitations of Li-ion batteries. To fill this gap, in situ electrochemical approach with new descriptive criteria for highly quantitative characterization of SEI and electrolytes is proposed. These criteria are: SEI formation capacity, SEI corrosion rate, SEI maintenance rate, and SEI kinetic stability. These criteria are associated with battery parameters like irreversible capacity, self-discharge, shelf-life, power, etc. Therefore, they are especially useful for electrolyte development and standard fast screening, allowing a skillful approach to narrow down the search for the best electrolyte. The characterization protocol also allows retrieving information on interfacial resistance for SEI layers and the electrochemical window of electrolytes, the other important metrics of characterization. The method validation was done on electrolyte blends containing phosphazenes, developed at Idaho National Laboratory, as 1.2M LiPF6 [80 % EC-MEC (2:8) (v/v) + 20% Phosphazene variety] (v/v), which were targeted for safer electrolyte variations.

  18. Electrolytic tiltmeters inside magnetic fields: Some observations

    International Nuclear Information System (INIS)

    We present observations of the electrolytic clinometers behaviour inside magnetic field environments introducing phenomenological expressions to account for the measured output voltage variations as functions of field gradients and field strengths

  19. An apparatus for carrying out electrolytic dissolutions

    International Nuclear Information System (INIS)

    The present invention relates to an electrolytic dissolution apparatus in which dissolution is achieved through contact with a solution. The apparatus is essentially characterized in that it comprises a container of electrically insulating material, a fixed first electrode, a mobile second electrode, means for insulating the electrodes from the substance to be dissolved while allowing the electrolyte to freely flow between them, members for passing an electric current between the electrodes and a device for causing the electrolyte to circulate throughout the apparatus. The second electrode is supported by the substance to be dissolved in such a manner that, during the dissolution step, it moves simultaneously with the substance upper level, so as to maintain a small spacing between that electrode and the substance and, thus, obtain an optimum efficiency from the apparatus. That apparatus is adapted to electrolytically dissolved metals such as plutonium

  20. Fluctuation induced effects in confined electrolyte solutions

    CERN Document Server

    Brandes, T

    2003-01-01

    We examine electrolyte systems confined between two parallel, grounded metal plates using a field-theoretic approach truncated at one-loop order. For symmetric electrolytes, the density distribution of the ions is non-uniform, with a maximum value at the center of the system. For asymmetric electrolytes, the system is no longer locally neutral, and there is a non-zero static electric potential. In addition, the surface of the metal plates becomes charged. When the plate separation becomes greater than the screening length, the charge distribution possesses two peaks with a local minimum at the center of the system. When the plates are immersed in a bulk electrolyte solution, an attractive fluctation induced force develops between them that is analogous to the Casimir force. Unlike the Casimir force, however, this attractive interaction has a finite limit in the zero separation limit and decays inversely with the separation at large separations.

  1. An electrolytic lapping technique for vanadium

    International Nuclear Information System (INIS)

    An electrolytic lapping technique has been developed for vanadium to take advantage of the many benefits this technique has already offered with other metals. Vanadium is particularly susceptible to surface smearing and embedment of particulate material during mechanical grinding and polishing; both of these problems are eliminated by electrolytic lapping. In addition, the technique has proven sufficiently reproducible to greatly facilitate preparation of large quantities of specimens. The use of electrolytic lapping also was a critical factor in the development of an etching technique which clearly delineates a wide range of deformation structures in vanadium. Examples of the application of this technique are presented from a study of the recrystallization of vanadium. Another equally important application of electrolytic lapping is the preparation of specimens for surface analytical techniques

  2. Kinetic characterization of non-linear soft-glassy rheology

    CERN Document Server

    Benzi, R; Sbragaglia, M; Succi, S

    2013-01-01

    Based on numerical simulations of a lattice kinetic model for soft-glassy materials, we characterize the global rheology of a dense emulsion-like system, under three representative load conditions: Couette flow, time-oscillating Couette flow and Kolmogorov flow. In all cases, it is found that the rheology is described by a Herschel-Bulkley (HB) relation, $\\sigma = {\\sigma}_{Y} + A S^{\\beta}$, with the yield stress ${\\sigma}_{Y}$ largely independent of the loading scenario. Under a proper rescaling of the HB parameters, we can also describe the local rheological behavior, which turns out to be different from the global one because of the spatial heterogeneities. Our analysis illuminates the crucial role of numerical simulations in allowing a seamless exploration of different loading scenarios and enabling measurements of local energy transfer within the flowing material.

  3. Glass transition and rheological redundancy in F-actin solutions.

    Science.gov (United States)

    Semmrich, Christine; Storz, Tobias; Glaser, Jens; Merkel, Rudolf; Bausch, Andreas R; Kroy, Klaus

    2007-12-18

    The unique mechanical performance of animal cells and tissues is attributed mostly to their internal biopolymer meshworks. Its perplexing universality and robustness against structural modifications by drugs and mutations is an enigma in cell biology and provides formidable challenges to materials science. Recent investigations could pinpoint highly universal patterns in the soft glassy rheology and nonlinear elasticity of cells and reconstituted networks. Here, we report observations of a glass transition in semidilute F-actin solutions, which could hold the key to a unified explanation of these phenomena. Combining suitable rheological protocols with high-precision dynamic light scattering, we can establish a remarkable rheological redundancy and trace it back to a highly universal exponential stretching of the single-polymer relaxation spectrum of a "glassy wormlike chain." By exploiting the ensuing generalized time-temperature superposition principle, the time domain accessible to microrheometry can be extended by several orders of magnitude, thus opening promising new metrological opportunities. PMID:18077385

  4. Rheological and microbiological study of flour treated by irradiation

    International Nuclear Information System (INIS)

    the aim this work is to study the effectiveness of radio treatment and its effect on the conservation of flour and their various parameters (physico-chemical and rheological). The flour has been treated with different doses (0, 0.75, 1.5 and 3 kGy), physico-chemical, rheological, microbiological and sensory analyses were made.The results show that the irradiation as a treatment for decontamination gave a highly effective. Indeed, a dose of 1.5 kGy allows a total destruction of yeasts and molds. Thus, from the point of view physico-chemical, increasing the dose of radiation causes a change in physical and chemical properties and rheological of flour. for the characteristics of bread, increasing the dose of radiation affects the quality of bread. (Author). 38 refs

  5. Rheological properties of simulated debris flows in the laboratory environment

    Science.gov (United States)

    Ling, Chi-Hai; Chen, Cheng-lung; Jan, Chyan-Deng

    1990-01-01

    Steady debris flows with or without a snout are simulated in a 'conveyor-belt' flume using dry glass spheres of a uniform size, 5 or 14 mm in diameter, and their rheological properties described quantitatively in constants in a generalized viscoplastic fluid (GVF) model. Close agreement of the measured velocity profiles with the theoretical ones obtained from the GVF model strongly supports the validity of a GVF model based on the continuum-mechanics approach. Further comparisons of the measured and theoretical velocity profiles along with empirical relations among the shear stress, the normal stress, and the shear rate developed from the 'ring-shear' apparatus determine the values of the rheological parameters in the GVF model, namely the flow-behavior index, the consistency index, and the cross-consistency index. Critical issues in the evaluation of such rheological parameters using the conveyor-belt flume and the ring-shear apparatus are thus addressed in this study.

  6. Hidden Invariants in Rheology: The Persistent Granular Nature of Liquids

    CERN Document Server

    Chafin, Clifford

    2014-01-01

    It is shown that the deviator, D$_{ij}$, after the process of symmetrization, is not sufficient to completely characterize all the nonrotational information that is contained in the first order flow and, therefore, this information is also lacking in many of the invariant based approaches to rheology based upon it. We recover it through an analysis of the discrete processes that must underlie deformation driven mixing in highly correlated fluids. This allows us to make an intrinsic distinction between pure shear and extension that has implications both for rheology and nonturbulent mixing. In particular, this gives an unambiguous microscopic notion of the rotation rate for every parcel and yields a more general class of invariant rheological theories. We discuss some implications of higher order flows on solutions and suspensions including possibilities for driving and stabilization nonuniform distributions using hydrodynamic forces alone.

  7. Practical determination of the rheological behavior of pasty biosolids.

    Science.gov (United States)

    Baudez, Jean-Christophe; Ayol, Azize; Coussot, Philippe

    2004-09-01

    In this paper, we demonstrate that the rheological behavior of pasty sewage sludges, regardless of origin, treatment or composition, follows a Herschel-Bulkley model. The yield stress and solid volume fraction are found to be the only two distinctive rheological characteristics of these materials. By scaling the shear rate and the shear stress with two parameters depending only on the yield stress and the solid fraction, the flow curves of 48 pasty sludges all fall along a unique dimensionless master curve. This result may be used in practice to determine, from simple, independent measurements, the rheological behavior of any pasty sludge: the yield stress can be measured with the help of the 'slump test' and the solid concentration determined from the organic and mineral matter contents. The results obtained with this technique are in very good agreement with those obtained by direct rheometry. PMID:15251224

  8. Rheological behaviour of suspensions of bubbles in yield stress fluids

    CERN Document Server

    Ducloué, Lucie; Goyon, Julie; Chateau, Xavier; Ovarlez, Guillaume

    2014-01-01

    The rheological properties of suspensions of bubbles in yield stress fluids are investigated through experiments on model systems made of monodisperse bubbles dispersed in concentrated emulsions. Thanks to this highly tunable system, the bubble size and the rheological properties of the suspending yield stress fluid are varied over a wide range. We show that the macroscopic response under shear of the suspensions depends on the gas volume fraction and the bubble stiffness in the suspending fluid. This relative stiffness can be quantified through capillary numbers comparing the capillary pressure to stress scales associated with the rheological properties of the suspending fluid. We demonstrate that those capillary numbers govern the decrease of the elastic and loss moduli, the absence of variation of the yield stress and the increase of the consistency with the gas volume fraction, for the investigated range of capillary numbers. Micro-mechanical estimates are consistent with the experimental data and provide...

  9. Rheological Characterization of Unusual DWPF Slurry Samples (U)

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. C.

    2005-09-01

    A study was undertaken to identify and clarify examples of unusual rheological behavior in Defense Waste Processing Facility (DWPF) simulant slurry samples. Identification was accomplished by reviewing sludge, Sludge Receipt and Adjustment Tank (SRAT) product, and Slurry Mix Evaporator (SME) product simulant rheological results from the prior year. Clarification of unusual rheological behavior was achieved by developing and implementing new measurement techniques. Development of these new methods is covered in a separate report, WSRC-TR-2004-00334. This report includes a review of recent literature on unusual rheological behavior, followed by a summary of the rheological measurement results obtained on a set of unusual simulant samples. Shifts in rheological behavior of slurries as the wt. % total solids changed have been observed in numerous systems. The main finding of the experimental work was that the various unusual DWPF simulant slurry samples exhibit some degree of time dependent behavior. When a given shear rate is applied to a sample, the apparent viscosity of the slurry changes with time rather than remaining constant. These unusual simulant samples are more rheologically complex than Newtonian liquids or more simple slurries, neither of which shows significant time dependence. The study concludes that the unusual rheological behavior that has been observed is being caused by time dependent rheological properties in the slurries being measured. Most of the changes are due to the effect of time under shear, but SB3 SME products were also changing properties while stored in sample bottles. The most likely source of this shear-related time dependence for sludge is in the simulant preparation. More than a single source of time dependence was inferred for the simulant SME product slurries based on the range of phenomena observed. Rheological property changes were observed on the time-scale of a single measurement (minutes) as well as on a time scale of hours to weeks. The unusual shape of the slurry flow curves was not an artifact of the rheometric measurement. Adjusting the user-specified parameters in the rheometer measurement jobs can alter the shape of the flow curve of these time dependent samples, but this was not causing the unusual behavior. Variations in the measurement parameters caused the time dependence of a given slurry to manifest at different rates. The premise of the controlled shear rate flow curve measurement is that the dynamic response of the sample to a change in shear rate is nearly instantaneous. When this is the case, the data can be fitted to a time independent rheological equation, such as the Bingham plastic model. In those cases where this does not happen, interpretation of the data is difficult. Fitting time dependent data to time independent rheological equations, such as the Bingham plastic model, is also not appropriate.

  10. High pressure rheology of core mimetic liquids

    Science.gov (United States)

    Secco, R. A.

    2003-04-01

    New developments in techniques to study high pressure liquid rheology in metallic melts have allowed the measurement of the viscosity of core-mimetic liquid alloys of Fe. We present technical details and results of high pressure - temperature viscosity measurements on Fe-FeS liquids using Stokes' method and a tailored density, composite probe sphere. Synchrotron X-ray radiographic experiments were carried out at high P,T at the Advanced Photon Source to image, in-situ, the motion of a probe sphere rising through the pressurized sample melt. The composite sphere is made of an inner, high density, metallic spherical core and an exterior, low density, refractory spherical shell or mantle. The structure of the composite sphere prevents reaction between the metallic core and the sample and adjustment of core/mantle radii allows sphere density tailoring. Viscosity is calculated with a modified form of Stokes' equation using the terminal velocity of the probe sphere. The viscosity of Fe and Fe-8.5wt%S liquids is constant along the pressure dependent melting boundary and is consistent with a prediction based on semi-empirical formalism. Further experimental verification of viscosity invariance along the high pressure melting boundary, especially where abrupt boundary slope changes occur as a result of different parent solid structures (i.e. at triple points), is required. The existing experimental evidence for pure Fe, particularly in other physical properties such as electrical resistivity and recent high pressure liquid structure studies, suggests that the preceding solid phase structure may play an important role in controlling property behavior along the melting boundary.

  11. Molecular dynamics simulations of supramolecular polymer rheology

    Science.gov (United States)

    Li, Zhenlong; Djohari, Hadrian; Dormidontova, Elena E.

    2010-11-01

    Using equilibrium and nonequilibrium molecular dynamics simulations, we studied the equilibrium and rheological properties of dilute and semidilute solutions of head-to-tail associating polymers. In our simulation model, a spontaneous complementary reversible association between the donor and the acceptor groups at the ends of oligomers was achieved by introducing a combination of truncated pseudo-Coulombic attractive potential and Lennard Jones repulsive potential between donor, acceptor, and neighboring groups. We have calculated the equilibrium properties of supramolecular polymers, such as the ring/chain equilibrium, average molecular weight, and molecular weight distribution of self-assembled chains and rings, which all agree well with previous analytical and computer modeling results. We have investigated shear thinning of solutions of 8- and 20-bead associating oligomers with different association energies at different temperatures and oligomer volume fractions. All reduced viscosity data for a given oligomer length can be collapsed into one master curve, exhibiting two power-law regions of shear-thinning behavior with an exponent of -0.55 at intermediate ranges of the reduced shear rate ? and -0.8 (or -0.9) at larger shear rates. The equilibrium viscosity of supramolecular solutions with different oligomer lengths and associating energies is found to obey a power-law scaling dependence on oligomer volume fraction with an exponent of 1.5, in agreement with the experimental observations for several dilute or semidilute solutions of supramolecular polymers. This implies that dilute and semidilute supramolecular polymer solutions exhibit high polydispersity but may not be sufficiently entangled to follow the reptation mechanism of relaxation.

  12. Architecturally Complex Polymers: Viscoelasticity and Extensional Rheology

    Science.gov (United States)

    van Ruymbeke, E.; Kapnistos, M.; Muliawan, E. B.; Vlassopoulos, D.; Hirao, A.; Hadjichristidis, N.

    2008-07-01

    We test the coarse-grained time-marching model we developed for predicting the linear viscoelastic properties of branched polymers from the knowledge of their molecular structure on several new model architectures. Based on three viscoelastic parameters, i.e., the Rouse time of an entanglement segment, the plateau modulus and the entanglement molecular weight, this model uses the ingredients of the tube-based theories of McLeish and co-workers, and its implementation is based on a time-marching algorithm. With a new way to account for the motion of the molecular segments localized between two branching points and within the framework of dynamic tube dilation (using the extended criteria of Graessley), this conceptual approach was already successfully applied to linear, star, H and pom-pom polymers. In this work, we extend our work to tree-like polymers. Then, based on the predictions obtained for the linear data, we extended the model for predicting the non-linear rheology, following the approach proposed by McLeish and Larson, and Blackwell et al. We consider in particular the case of model symmetric Cayley tree polybutadienes and poly(methyl methacrylates) having 2, 3 or 4 generations with branches of varying degree of entanglements. In addition to systematic linear frequency sweep measurements, we performed uniaxial elongation measurements using the SER fixture. The samples tested exhibited significant strain hardening compared to the linear analogues at lower and intermediate Hencky strain rates. The extracted effective steady extensional viscosity scales with the elongational rate with a power exponent of about -0.5, in agreement with earlier findings with linear polystyrenes.

  13. Magnesium removal in the electrolytic zinc industry:

    OpenAIRE

    Booster, J. L.

    2003-01-01

    Electrolytic zinc plants need to take measures to control the magnesium content in their process liquors, because the natural magnesium bleed does not balance the input from concentrates. Presently used methods are environmentally unfriendly (due to the production of large amounts of waste gypsum) or expensive. Therefore, an alternative process route is explored in which magnesium is removed from zinc electrolyte by selective precipitation of magnesium fluoride (sellaite). As standard applica...

  14. Electrodeposition of Palladium Coatings from Iminodiacetate Electrolyte

    OpenAIRE

    Kublanovsky, Valeriy S.; Nikitenko, Vasiliy N.; Rudenko, Kostiantyn P.

    2013-01-01

    The ionic composition of an iminodiacetate electrolyte as a function of solution composition and pH has been deter-mined. The kinetic parameters (exchange currents and apparent transfer coefficients) of the electroreduction of a palla-dium(II) bis-iminodiacetate complex from an electrolyte containing excess ligand have been calculated. It has been shown that the rate of the electrode process is controlled by the diffusion of reduced ions to the electrode surface and by the electron-transfer r...

  15. Electrolyte : Semiconductor Combinations for Organic Electronic Devices

    OpenAIRE

    Said, Elias

    2009-01-01

    The discovery of semi-conducting organic materials has opened new possibilities for electronic devices and systems because of their solution processibility, lightweight and flexibility compared to inorganic semiconductors. The combination of semiconductors with electrolytes, and more especially organic semiconductors and solid electrolytes has attracted the attention of researchers because of the multiple phenomena originating from the simultaneous motion of electrons and ions. This thesis de...

  16. REMOVAL OF COPPER ELECTROLYTE CONTAMINANTS BY ADSORPTION

    OpenAIRE

    Gabai, B.; Dos Santos, N. A. A.; Azeve?do, D. C. S.; Brandani, S.; Cavalcante Jr, C. L.

    1997-01-01

    Abstract - Selective adsorbents have become frequently used in industrial processes. Recent studies have shown the possibility of using adsorption to separate copper refinery electrolyte contaminants, with better results than those obtained with conventional techniques. During copper electrorefinning, many impurities may be found as dissolved metals present in the anode slime which forms on the electrode surface, accumulated in the electrolyte or incorporated into the refined copper on the ca...

  17. Heat transfer in polymer electrolyte fuel cells

    OpenAIRE

    Matian, Mardit

    2011-01-01

    A three dimensional computational fluid dynamics (CFD) model of a polymer electrolyte membrane fuel cell (PEMFC) stack has been developed in order to study heat transfer in single-cell and two-cell stacks. In order to simplify the computational model, the electrochemical and water transport aspects of fuel cell operation were decoupled from those of heat transfer; the PEMFC fuel cell membrane electrode assembly (MEA), which comprises the electrode and electrolyte functional lay...

  18. Understanding Ionic Conductivity in Crystalline Polymer Electrolytes

    OpenAIRE

    Brandell, Daniel

    2005-01-01

    Polymer electrolytes are widely used as ion transport media in vital applications such as energy storage devices and electrochemical displays. To further develop these materials, it is important to understand their ionic conductivity mechanisms. It has long been thought that ionic conduction in a polymer electrolyte occurs in the amorphous phase, while the crystalline phase is insulating. However, this picture has recently been challenged by the discovery of the crystalline system LiXF6?PEO...

  19. A dynamic rheological model for thin-film lubrication

    International Nuclear Information System (INIS)

    In this study, the effects of the non-Newtonian rheological properties of the lubricant in a thin-film lubrication regime between smooth surfaces were investigated. The thin-film lubrication regime typically appears in Stribeck curves with a clearly observable minimum coefficient of friction (COF) and a low-COF region, which is desired for its lower energy dissipation. A dynamic rheology of the lubricant from the hydrodynamic lubrication regime to the thin-film lubrication regime was proposed based on the convected Maxwell constitutive equation. This rheology model includes the increased relaxation time and the yield stress of the confined lubricant thin film, as well as their dependences on the lubricant film thickness. The Deborah number (De number) was adopted to describe the liquid-solid transition of the confined lubricant thin film under shearing. Then a series of Stribeck curves were calculated based on Tichy's extended lubrication equations with a perturbation of the De number. The results show that the minimum COF points in the Stribeck curve correspond to a critical De number of 1.0, indicating a liquid-to-solid transition of the confined lubricant film. Furthermore, the two proposed parameters in the dynamic rheological model, namely negative slipping length b (indicating the lubricant interfacial effect) and the characteristic relaxation time ?0, were found to determine the minimum COF and the width of the low-COF region, both of which were required to optimize the shape of the Stribeck curve. The developed dynamic rheological model interprets the correlation between the rheological and interfacial properties of lubricant and its lubrication behavior in the thin-film regime. (condensed matter: structural, mechanical, and thermal properties)

  20. Polymer electrolytes based on polyanionic lithium salts

    International Nuclear Information System (INIS)

    Highlights: •Polymer electrolytes composed of PEO and a polyanionic lithium salt were prepared. •The addition of BF3·OEt2 increases the ionic conductivities by one to two orders. •The structure of functional group of lithium salts affects electrolytes properties. -- Abstract: Polymer electrolytes composed of poly(ethylene oxide) and a polyanionic lithium salt are prepared, and electrochemical and thermal properties were investigated in the absence and presence of BF3·OEt2. The addition of BF3·OEt2 increases the ionic conductivities, and the lithium ion transference number of the polymer electrolyte for the PEO/poly(lithium acrylate) (PLA) and PEO/poly(lithium vinylsulfonate) (PLVS) system were higher than that of PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) system. However, ionic conductivities of the polymer electrolyte in the presence of BF3·OEt2 for the PEO/PLVS system were higher than that for the PEO/PLA system below 50 °C, due to the suppression of the crystallization of PEO. It was found that the structure of functional group in polyanionic lithium salts significantly affect electrochemical and thermal properties of polymer electrolytes

  1. Charge regulation at semiconductor-electrolyte interfaces.

    Science.gov (United States)

    Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N

    2015-07-01

    The interface between a semiconductor material and an electrolyte solution has interesting and complex electrostatic properties. Its behavior will depend on the density of mobile charge carriers that are present in both phases as well as on the surface chemistry at the interface through local charge regulation. The latter is driven by chemical equilibria involving the immobile surface groups and the potential determining ions in the electrolyte solution. All these lead to an electrostatic potential distribution that propagate such that the electrolyte and the semiconductor are dependent on each other. Hence, any variation in the charge density in one phase will lead to a response in the other. This has significant implications on the physical properties of single semiconductor-electrolyte interfaces and on the electrostatic interactions between semiconductor particles suspended in electrolyte solutions. The present paper expands on our previous publication (Fleharty et al., 2014) and offers new results on the electrostatics of single semiconductor interfaces as well as on the interaction of charged semiconductor colloids suspended in electrolyte solution. PMID:25595623

  2. A new thermochemical and electrolytic hybrid hydrogen production process for FBR

    International Nuclear Information System (INIS)

    A new thermochemical hybrid hydrogen production process is under investigation to realize the hydrogen production from water by using the heat generation of coolant of sodium in Fast Breeding Reactor (FBR). Newly proposed cycle is based on sulfuric acid (H2SO4) synthesis and the decomposition processes developed earlier, and SO3 decomposition process at about 500degC is facilitated by electrolysis with ionic oxygen conductive solid electrolyte which is extensively utilized for high-temperature electrolysis of water. Measured decomposition voltage of sulfur trioxide (SO3) with 8mol yttria stabilized zirconia (8molYSZ) solid electrolyte and platinum electrode were lower than 0.5V at 500degC - 600degC, and oxygen permeation rate through YSZ into N2 purge gas agreed well with the calculated permeation rate from measured cell current. Preliminary measured oxygen permeation rate through La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) in air supplied experiments were higher than the rate through 8molYSZ. These results show the possibility of development of higher performance electrolytic cell using other solid electrolytes than YSZ. Thermal efficiency of the proposed cycle based on chemical reactions was 47.3% with no heat recovery. (author)

  3. A new thermochemical and electrolytic hybrid hydrogen production process for FBR

    International Nuclear Information System (INIS)

    A new thermochemical hybrid hydrogen production process (HHLT: thermochemical and electrolytic Hybrid Hydrogen production process in Lower Temperature range) for sodium cooled FBR is proposed. HHLT is based on sulfuric acid (H2SO4) synthesis and the decomposition processes (named Westinghouse process') developed earlier, and SO3 decomposition process is facilitated by electrolysis with ionic oxygen conductive solid electrolyte which is extensively utilized for high-temperature electrolysis of water. In the present study, theoretical total voltage required for electrolysis and thermal efficiency of HHLT considering chemical reactions were evaluated. Furthermore, advantages and technical problems of HHLT were considered. Evaluated theoretical total voltage was expected to be lower than about 0.5V. Theoretical thermal efficiency was changed under the influence of H2SO4 concentration and heat recovery, and maximum efficiency obtained in this evaluation was about 55%. HHLT has many advantages such as, simple process flow, low corrosion of structural materials and low risk for hydrogen explosion. Important problems to be solved consist of feasibility of electrolysis of SO3 using solid electrolyte, development of high performance oxygen conductive solid electrolyte under SO3 atmosphere, process structural materials and sulfuric acid synthesizer with high electrolysing efficiency. (author)ctrolysing efficiency. (author)

  4. The use of anions with sulfate function in electrolyte for lithium battery. Study of transport mechanism; Utilisation d'anions a fonction sulfate dans des electrolytes pour batterie au lithium. Etude des mecanismes de transport

    Energy Technology Data Exchange (ETDEWEB)

    Chauvin, Ch.

    2005-05-15

    Lithium salts based on oligo-ether sulfate were synthesized and characterised. They incorporate oxy-ethylene units which enable the lithium cation salvation and, potentially, their use as ionic liquids. Their properties as lithium salts dissolved in liquid or polymer electrolytes were evaluated. Their electrochemical and thermal stabilities are sufficient for lithium battery application. Due to their weak dissociation in POE, their conductivities are fairly low. On the other hand, they have high cationic transference numbers. In mixture with usual salts as LiTFSI, they provide a good compromise between conductivities/transference number/cost. The second part of this study deals with the synthesis and characterisation of an ionomer with sulfate function and polyether backbone. The electrochemical, physical and chemical properties of this material show that it could be used as polymer electrolyte. Its potential as cross-linked gelled polymer electrolyte is outstanding. Structural analyses on an ionomeric monocrystal have been corroborated with quantum chemistry calculations. (author)

  5. Rheology of Savannah River site tank 42 HLW radioactive sludge

    International Nuclear Information System (INIS)

    Knowledge of the rheology of the radioactive sludge slurries at the Savannah River Site is necessary in order to ensure that they can be retrieved from waste tanks and processed for final disposal. At Savannah River Site, Tank 42 sludge represents on of the first HLW radioactive sludges to be vitrified in the Defense Waste Processing Facility. The rheological properties of unwashed Tank 42 sludge slurries at various solids concentrations were measured remotely in the Shielded Cells at the Savannah River Technology Center using a modified Haake Rotovisco viscometer

  6. Longevity and rheology of cratons: key constraints from surface topography

    Science.gov (United States)

    Francois, T.; Burov, E. B.; Meyer, B.; Agard, P.

    2011-12-01

    Archean cratons are stable remnants of Earth's early continental lithosphere. Their structure, composition and survival over geological time spans make them ones of the most unique and enigmatic features of the Earth's surface. It has become evident from both geophysical and petrological studies that cratons exhibit deep lithospheric roots, which remained stable ever since their formation in the early Archean. The question of how some of the cratons survived destruction over timescales of billions of years remains a subject of vigorous debate. In order to understand what controls the long-term stability of the cratons, we investigated the impact of the thermo-rheological structure of the lithosphere on the evolution of both surface topography and cratonic roots using fully coupled thermo-mechanical numerical models (600*3000 km, free upper surface topography, layered lithospheric structure). Our model has a particular focus on the Canadian Shield, where considerable structural and thermal data are available from both geological and geophysical studies. In particular, we compare the implications of the "Cratonic" "Jelly-Sandwich" rheology (JS; strong dry olivine mantle, strong crust, cold geotherm with Moho temperature of 400°C, thermal lithosphere thickness of 250 km) with those of the "Crème Brûlée" rheology (CB; strong crust, weak wet olivine mantle, Moho temperature of 600°C, thermal lithosphere thickness of 150 km) (Figure 1). Our experiments show that, in the case of a laterally homogeneous lithosphere and in the absence of tectonic shortening or extension (blocked borders), both JS and CB rheologies may account for the stability of the shield and its surface topography. In this case continental lithosphere remains stable over large time spans, even for the weakest wet olivine mantle (but for "cold" thermal gradients). Nevertheless, for a laterally heterogeneous crust, as is the case for the Canadian Shield and most cratons, dry olivine mantle JS rheology provides a far more stable lithosphere, with surface undulations < 1000m over 0.3 Gy time spans, compared to the unlikely ~8000m surface undulations produced by CB rheology. In addition, the CB lithosphere gets quickly unstable when minor tectonic compression is applied, generating unrealistic short-wavelength surface undulations. These results demonstrate the need to consider buried loads and tectonic forces whenever constraining long-term rheological properties of the lithosphere, and suggest that the "Jelly-Sandwich" rheology so far better accounts for natural observations.

  7. Rheology of Wormlike Micelles Equilibrium Properties and Shear Banding Transition

    CERN Document Server

    Berret, J F

    2004-01-01

    We review the experimental and theoretical results obtained during the past decade on the structure and rheology of wormlike micellar solutions. We focus on the linear and nonlinear viscoelasticity and emphasize the analogies with polymers. Based on a comprehensive survey of surfactant systems, the present study shows the existence of standard rheological behaviors for semidilute and concentrated solutions. One feature of this behavior is a shear banding transition associated with a stress plateau in the nonlinear mechanical response. For concentrated solutions, we show that in the plateau region the shear bands are isotropic and nematic.

  8. Slow Transients and Metastability in Wormlike Micelle Rheology

    OpenAIRE

    Grand, C.; Arrault, J.; Cates, M.

    1997-01-01

    The steady-state nonlinear rheology of wormlike micellar systems is thought to be subject to shear banding (the underlying shear stress vs. strain rate curve $\\sigma(\\dot{\\gamma})$ is nonmonotonic). Shear banding may result in a plateau ($\\sigma(\\dot{\\gamma})=\\sigma_{\\rm p}$) in the measured flow curve (at controlled mean strain rate $\\dot{\\gamma}$). We present new rheological data for aqueous CPyCl/NaSal (100 mM/60 mM). Steady-state flow curves published previously for this system (Rehage ...

  9. Study of the formation of a solid electrolyte interphase (SEI) in ionically crosslinked polyampholytic gel electrolytes

    International Nuclear Information System (INIS)

    An ionic complex of anionic and cationic monomers was obtained by protonation of (N,N-diethylamino)ethylmethacrylate with acrylic acid. A novel ionically crosslinked polyampholytic gel electrolyte was prepared through the free radical copolymerization of the ionic complex and acrylamide in a solvent mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (1:1:1, v/v) containing 1 mol/L of LiPF6. The impedance analysis indicated that the ionic conductivity of the polyampholytic gel electrolyte was rather close to that of solution electrolytes in the absence of a polymer at the same temperature. The temperature dependence of the conductivity was found to be well in accord with the Arrhenius behavior. The formation processes of the solid electrolyte interphase (SEI) formed in both gel and solution electrolytes during the cycles of charge-discharge were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The cyclic voltammetry curves show a strong peak at a potential of 0.68 V and an increase of the interfacial resistance from 17.2 ? to 35.8 ? after the first cycle of charge-discharge. The results indicate that the formation process of SEI formed in both gel and solution electrolytes was similar which could effectively prevent the organic electrolyte from further decomposition and inserting into the graphite electrode. The morphologies of SEI formed in both gel and solution electrolytes were analyzed by field emn electrolytes were analyzed by field emission scanning electron microscopy. The results indicate that the SEI formed in the gel electrolyte showed a rough surface consisting of smaller solid depositions. Moreover, the SEI formed in the gel electrolyte became more compact and thicker as the cycling increased

  10. Electrolytic production of uranous nitrate

    International Nuclear Information System (INIS)

    Efficient production of uranous nitrate is important in nuclear fuel reprocessing because U(IV) acts as a plutonium reductant in solvent extraction and can be coprecipitated with plutonium and/or throium as oxalates during fuel reprocessing. Experimental conditions are described for the efficient electrolytic production of uranous nitrate for use as a reductant in the SRP Purex process. The bench-scale, continuous-flow, electrolysis cell exhibits a current efficiency approaching 100% in combination with high conversion rates of U(VI) to U(IV) in simulated and actual SRP Purex solutions. High current efficiency is achieved with a voltage-controlled mercury-plated platinum electrode and the use of hydrazine as a nitrite scavenger. Conversion of U(VI) to U(IV) proceeds at 100% efficiency. Cathodic gas generation is minimal. The low rate of gas generation permits a long residence time within the cathode, a necessary condition for high conversions on a continuous basis. Design proposals are given for a plant-scale, continuous-flow unit to meet SRP production requirements. Results from the bench-scale tests indicate that an 8-kW unit can supply sufficient uranous nitrate reductant to meet the needs of the Purex process at SRP

  11. Bis(fluoromalonato)borate (BFMB) Anion Based Ionic Liquid As an Additive for Lithium-Ion Battery Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiao-Guang [ORNL; Liao, Chen [ORNL; Baggetto, Loic [ORNL; Guo, Bingkun [ORNL; Unocic, Raymond R [ORNL; Veith, Gabriel M [ORNL; Dai, Sheng [ORNL

    2014-01-01

    Propylene carbonate (PC) is a good solvent for lithium ion battery applications due to its low melting point and high dielectric constant. However, PC is easily intercalated into graphite causing it to exfoliate, killing its electrochemical performance. Here we report on the synthesis of a new ionic liquid electrolyte based on partially fluorinated borate anion, 1-butyl-1,2-dimethylimidazolium bis(fluoromalonato)borate (BDMIm.BFMB), which can be used as an additive in 1 M LiPF6/PC electrolyte to suppress graphite exfoliation and improve cycling performance. In addition, both PC and BDMIm.BFMB can be used synergistically as additive to 1.0M LiPF6/methyl isopropyl sulfone (MIPS) to dramatically improve its cycling performance. It is also found that the chemistry nature of the ionic liquids has dramatic effect on their role as additive in PC based electrolyte.

  12. Electrochemical studies on polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) membranes prepared by electrospinning and phase inversion-A comparative study

    International Nuclear Information System (INIS)

    The synthesis, characterization and electrochemical properties of poly(vinylidene fluoride-co-hexafluoropropylene) {P(VdF-co-HFP)} prepared by electrospinning and phase inversion methods are reported. The morphologies of the membranes were studied by field emission scanning electron microscope and atomic force microscope. Thermal properties of the membranes were evaluated by differential scanning calorimetry. The resultant porous membranes are good absorbents of liquid electrolytes and exhibit high electrolyte retention capacity. The polymer electrolytes were prepared by soaking the membranes in liquid electrolyte. The temperature dependent ionic conductivity and electrochemical properties were evaluated. Li/LiFePO4 cell with electrospun membrane delivers a discharge capacity of 145 mAh/g, which corresponds to 85% utilization of active material under the test conditions and shows lower capacity fade under continuous cycling.

  13. Semi-active sliding mode control of vehicle suspension with magneto-rheological damper

    Science.gov (United States)

    Zhang, Hailong; Wang, Enrong; Zhang, Ning; Min, Fuhong; Subash, Rakheja; Su, Chunyi

    2015-01-01

    The vehicle semi-active suspension with magneto-rheological damper(MRD) has been a hot topic since this decade, in which the robust control synthesis considering load variation is a challenging task. In this paper, a new semi-active controller based upon the inverse model and sliding mode control (SMC) strategies is proposed for the quarter-vehicle suspension with the magneto-rheological (MR) damper, wherein an ideal skyhook suspension is employed as the control reference model and the vehicle sprung mass is considered as an uncertain parameter. According to the asymptotical stability of SMC, the dynamic errors between the plant and reference systems are used to derive the control damping force acquired by the MR quarter-vehicle suspension system. The proposed modified Bouc-wen hysteretic force-velocity ( F- v) model and its inverse model of MR damper, as well as the proposed continuous modulation (CM) filtering algorithm without phase shift are employed to convert the control damping force into the direct drive current of the MR damper. Moreover, the proposed semi-active sliding mode controller (SSMC)-based MR quarter-vehicle suspension is systematically evaluated through comparing the time and frequency domain responses of the sprung and unsprung mass displacement accelerations, suspension travel and the tire dynamic force with those of the passive quarter-vehicle suspension, under three kinds of varied amplitude harmonic, rounded pulse and real-road measured random excitations. The evaluation results illustrate that the proposed SSMC can greatly suppress the vehicle suspension vibration due to uncertainty of the load, and thus improve the ride comfort and handling safety. The study establishes a solid theoretical foundation as the universal control scheme for the adaptive semi-active control of the MR full-vehicle suspension decoupled into four MR quarter-vehicle sub-suspension systems.

  14. Effect of electrolyte on surface properties of pure titanium coated by plasma electrolytic oxidation

    International Nuclear Information System (INIS)

    Graphical abstract: Highlights: ? K4P2O7 electrolyte produced the crater-like structure of micro pores. ? Electrochemical reactions of P2O74- exhibited a high resistance resulting in porous surface. ? Oxide film under K4P2O7 electrolyte condition contained high amount of anatase phase. ? Forming ability of biomimetic apatite was improved under K4P2O7 electrolyte condition. - Abstract: The present study investigated the surface characteristics of pure titanium subjected to a plasma electrolytic oxidation (PEO) process using two different electrolytes containing either potassium pyrophosphate or potassium triphosphate. For this purpose, a series of PEO coating were carried out at ambient temperature with a current density of 200 mA/cm2. The surface structures of the oxide films were observed via scanning electron microscopy and the volume fractions of constitutive phases were determined based on X-ray diffraction analysis. The surface roughness of the PEO-coated sample in the electrolyte with potassium pyrophosphate was more complicated than that with potassium triphosphate. The volume fraction of metastable anatase phase in the sample coated with potassium pyrophosphate was relatively higher than that with potassium triphosphate, which was mainly attributed to different electrochemical reactions between the substrate andeactions between the substrate and electrolytes during PEO coating. It was also found that the oxide film coated in the potassium pyrophosphate containing electrolyte showed the easy formation of biomimetic apatite in a simulated body fluid solution.

  15. The Rheology of Acoustically Fluidized Sand

    Science.gov (United States)

    Conrad, J. W.; Melosh, J.

    2013-12-01

    The collapse of large craters and the formation of central peaks and peak rings is well modeled by numerical computer codes that incorporate the acoustic fluidization mechanism to temporarily allow the fluid-like flow of rock debris immediately after crater excavation. Furthermore, long runout landslides require a similar mechanism to explain their almost frictionless movement, which is probably also a consequence of their granular composition coupled with internal vibrations. Many different investigators have now confirmed the ability of vibrations to fluidize granular materials. Yet it still remains to fully describe the rheology of vibrated sand as a function of stress, frequency and amplitude of the vibrations in the sand itself. We constructed a rotational viscometer to quantitatively investigate the relation between the stress and strain rate in a horizontal bed of strongly vibrated sand. In addition to the macroscopic stain rate, the amplitude and frequency of the vibrations produced by a pair of pneumatic vibrators were also measured with the aid of miniaturized piezoelectric accelerometers (B&K 4393) whose output was recorded on a digital storage oscilloscope. The initial gathering of the experimental data was difficult due to granular memory, but by having the sand compacted vibrationally for 8 minutes before each run the scatter of data was reduced and we were able to obtain consistent results. Nevertheless, our major source of uncertainty was variations in strain rate from run to run. We find that vibrated sand flows like a highly non-Newtonian fluid, in which the shear strain rate is proportional to stress to a power much greater than one, where the precise power depends on the amplitude and frequency of the applied vibrations. Rapid flow occurs at stresses less than half of the static yield stress (that is, the yield stress when no vibration is applied) when strong vibrations are present. For a Newtonian fluid, such as water, the relation between strain rate and stress is linear. In our experiments we found that the shear strain rate is proportional to shear stress raised to the powers 5.9 and 8.4 at frequencies of 8.5 kHz and 7.4 kHz and increasing amplitude of vibration, respectively. This demonstrates that vibrated sand behaves as a strongly nonlinear pseudo-plastic material that, like glacier ice, can also be approximated as a Bingham material with a rate-dependent yield stress. The flow of acoustically fluidized granular materials provides a reasonable explanation of crater collapse, long runout landslides, and other events involving large masses of granular material.

  16. Lithium carbon batteries with solid polymer electrolyte; Accumulateur lithium carbone a electrolyte solide polymere

    Energy Technology Data Exchange (ETDEWEB)

    Andrieu, X.; Boudin, F. [Alcatel Alsthom Recherche, 91 - Marcoussis (France)

    1996-12-31

    The lithium carbon batteries studied in this paper use plasticized polymer electrolytes made with passive polymer matrix swollen by a liquid electrolyte with a high ionic conductivity (> 10{sup -3} S/cm at 25 deg. C). The polymers used to prepare the gels are polyacrylonitrile (PAN) and vinylidene poly-fluoride (PVdF). The electrochemical and physical properties of these materials are analyzed according to their composition. The behaviour of solid electrolytes with different materials of lithium ion insertion (graphite and LiNiO{sub 2}) are studied and compared to liquid electrolytes. The parameters taken into account are the reversible and irreversible capacities, the cycling performance and the admissible current densities. Finally, complete lithium ion batteries with gelled electrolytes were manufactured and tested. (J.S.) 2 refs.

  17. Impact of Environmental Conditions (pH, Ionic Strength, And Electrolyte Type) On The Surface Charge And Aggregation Of Silver Nanoparticles Suspensions

    Science.gov (United States)

    The impact of capping agents and environmental conditions (pH, ionic strength, and background electrolytes) on surface charge and aggregation potential of silver nanoparticles (AgNPs) suspensions were investigated. Capping agents are chemicals used in the synthesis of nanopartic...

  18. NMR and conductivity study of PEO-based composite polymer electrolytes

    International Nuclear Information System (INIS)

    The influence of the space charge created by the presence of TiO2 nanoparticles on the lithium and polymer chain mobility have been investigated in solid composite polymer electrolytes (CPE), poly(ethylene oxide) (PEO) LiClO4, by using complex impedance spectroscopy and nuclear magnetic resonance (NMR). Special care was taken with the synthesis and the characterization of the TiO2 particles and with the composite preparation. The conductivity and NMR measurements were undertaken in composite samples nanoparticles having constant total surface area. Proton (1H) and lithium (7Li) lineshapes and spin-lattice relaxation times were measured as a function of temperature. Activation energies extracted from the 7Li relaxation data are in the range 0.20-0.22 eV. The NMR decoupling experiment suggests that the Li-Li interactions are stronger in the composites when compared with those of the ceramic free electrolytes

  19. Interfacial rheology: an overview of measuring techniques and its role in dispersions and electrospinning.

    Science.gov (United States)

    Pelipenko, Jan; Kristl, Julijana; Rošic, Romana; Baumgartner, Saša; Kocbek, Petra

    2012-06-01

    Interfacial rheological properties have yet to be thoroughly explored. Only recently, methods have been introduced that provide sufficient sensitivity to reliably determine viscoelastic interfacial properties. In general, interfacial rheology describes the relationship between the deformation of an interface and the stresses exerted on it. Due to the variety in deformations of the interfacial layer (shear and expansions or compressions), the field of interfacial rheology is divided into the subcategories of shear and dilatational rheology. While shear rheology is primarily linked to the long-term stability of dispersions, dilatational rheology provides information regarding short-term stability. Interfacial rheological characteristics become relevant in systems with large interfacial areas, such as emulsions and foams, and in processes that lead to a large increase in the interfacial area, such as electrospinning of nanofibers. PMID:22750813

  20. Rheological Investigation on the Effect of Shear and Time Dependent Behavior of Waxy Crude Oil

    Directory of Open Access Journals (Sweden)

    Japper-Jaafar A.

    2014-07-01

    Full Text Available Rheological measurements are essential in transporting crude oil, especially for waxy crude oil. Several rheological measurements have been conducted to determine various rheological properties of waxy crude oil including the viscosity, yield strength, wax appearance temperature (WAT, wax disappearance temperature (WDT, storage modulus and loss modulus, amongst others, by using controlled stress rheometers. However, a procedure to determine the correct parameters for rheological measurements is still unavailable in the literature. The paper aims to investigate the effect of shear and time dependent behaviours of waxy crude oil during rheological measurements. It is expected that the preliminary work could lead toward a proper rheological measurement guideline for reliable rheological measurement of waxy crude oil.

  1. Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia; Sintese, processamento e caracterizacao das meia-celulas de oxido solido catodo/eletrolito de manganito de lantanio dopado com estroncio/zirconia estabilizada com itria

    Energy Technology Data Exchange (ETDEWEB)

    Chiba, Rubens

    2010-07-01

    The ceramic films of strontium-doped lanthanum manganite (LSM) and strontium doped lanthanum manganite/Yttria-stabilized zirconia (LSM/YSZ) are used as cathodes of the high temperature solid oxide fuel cells (HTSOFC). These porous ceramic films had been deposited on the YSZ dense ceramic substrate, used as electrolyte, structural component of the module, thus conferring a configuration of half-cell called auto-support. The study of the half-cell it is basic, therefore in the interface cathode/electrolyte occurs the oxygen reduction reaction, consequently influencing in the performance of the HTSOFC. In this direction, the present work contributes for the processing of thin films, using the wet powder spraying technique, adopted for the conformation of the ceramic films for allowing the attainment of porous layers with thicknesses varied in the order of micrometers. The LSM powders were synthesized by the citrate technique and the LSM/YSZ powders synthesized by the solid mixture technique. In the stage of formation were prepared organic suspensions of LSM and LSM/YSZ fed by gravity in a manual aerograph. For the formation of the YSZ substrate was used a hydraulic uniaxial press. The attainment of solid oxide half-cells cathode/electrolyte was possible of crystalline structures hexagonal for phase LSM and cubic for phase YSZ. The half-cells micrographs show that the YSZ substrate is dense, enough to be used as solid electrolyte, and the LSM and LSM/YSZ films are presented porous with approximately 30 {mu}m of thickness and good adherence between the cathodes and the electrolyte. The presence of composite cathode between the LSM cathode and YSZ substrate, presented an increase in the electrochemical performance in the oxygen reduction reaction. (author)

  2. Rheological properties of silica suspensions in aqueous cellulose derivatives solutions

    Science.gov (United States)

    Ryo, Y.; Kawaguchi, M.

    1992-05-01

    The rheological properties of the silica suspensions in aqueous solutions of hydroxypropylmethylcellulose (HPMC) were investigated in terms of the shear stress and storage and loss moduli (G' and G`) as a function of silica content, HPMC concentration, and HPMC molecular weight by using a coaxial cylinder rheometer.

  3. Particle laden fluid interfaces: dynamics and interfacial rheology.

    Science.gov (United States)

    Mendoza, Alma J; Guzmán, Eduardo; Martínez-Pedrero, Fernando; Ritacco, Hernán; Rubio, Ramón G; Ortega, Francisco; Starov, Victor M; Miller, Reinhard

    2014-04-01

    We review the dynamics of particle laden interfaces, both particle monolayers and particle+surfactant monolayers. We also discuss the use of the Brownian motion of microparticles trapped at fluid interfaces for measuring the shear rheology of surfactant and polymer monolayers. We describe the basic concepts of interfacial rheology and the different experimental methods for measuring both dilational and shear surface complex moduli over a broad range of frequencies, with emphasis in the micro-rheology methods. In the case of particles trapped at interfaces the calculation of the diffusion coefficient from the Brownian trajectories of the particles is calculated as a function of particle surface concentration. We describe in detail the calculation in the case of subdiffusive particle dynamics. A comprehensive review of dilational and shear rheology of particle monolayers and particle+surfactant monolayers is presented. Finally the advantages and current open problems of the use of the Brownian motion of microparticles for calculating the shear complex modulus of monolayers are described in detail. PMID:24200090

  4. Influence of rheology on debris-flow simulation

    Directory of Open Access Journals (Sweden)

    M. Arattano

    2006-01-01

    Full Text Available Systems of partial differential equations that include the momentum and the mass conservation equations are commonly used for the simulation of debris flow initiation, propagation and deposition both in field and in laboratory research. The numerical solution of the partial differential equations can be very complicated and consequently many approximations that neglect some of their terms have been proposed in literature. Many numerical methods have been also developed to solve the equations. However we show in this paper that the choice of a reliable rheological model can be more important than the choice of the best approximation or the best numerical method to employ. A simulation of a debris flow event that occurred in 2004 in an experimental basin on the Italian Alps has been carried out to investigate this issue. The simulated results have been compared with the hydrographs recorded during the event. The rheological parameters that have been obtained through the calibration of the mathematical model have been also compared with the rheological parameters obtained through the calibration of previous events, occurred in the same basin. The simulation results show that the influence of the inertial terms of the Saint-Venant equation is much more negligible than the influence of the rheological parameters and the geometry. A methodology to quantify this influence has been proposed.

  5. Hysteresis and Avalanches in Two Dimensional Foam Rheology Simulations

    CERN Document Server

    Jiang, Y; Saxena, A; Asipauskas, M; Glazier, J A

    1999-01-01

    Foams have unique rheological properties that range from solid-like to fluid-like. We study two-dimensional non-coarsening foams of different disorder under shear in a Monte Carlo simulation, using a driven large-Q Potts model. We find that the dynamics of topological rearrangements depend sensitively on the structural disorder.

  6. Continuum modeling of secondary rheology in dense granular materials.

    Science.gov (United States)

    Henann, David L; Kamrin, Ken

    2014-10-24

    Recent dense granular flow experiments have shown that shear deformation in one region of a granular medium fluidizes its entirety, including regions far from the sheared zone, effectively erasing the yield condition everywhere. This enables slow creep deformation to occur when an external force is applied to a probe in the nominally static regions of the material. The apparent change in rheology induced by far-away motion is termed the "secondary rheology," and a theoretical rationalization of this phenomenon is needed. Recently, a new nonlocal granular rheology was successfully used to predict steady granular flow fields, including grain-size-dependent shear-band widths in a wide variety of flow configurations. We show that the nonlocal fluidity model is also capable of capturing secondary rheology. Specifically, we explore creep of a circular intruder in a two-dimensional annular Couette cell and show that the model captures all salient features observed in experiments, including both the rate-independent nature of creep for sufficiently slow driving rates and the faster-than-linear increase in the creep speed with the force applied to the intruder. PMID:25379938

  7. X-ray radiography for investigating rheological processes

    International Nuclear Information System (INIS)

    The applicability of X-ray radiography for investigating rheological processes during heated tool welding of polyethylene has been tested experimentally and is illustrated for 10 mm thick polyethylene pipes having diameter of 110 mm. Molybdenum powder has been used as contrast media

  8. Activation energy measurements in rheological analysis of cheese

    Science.gov (United States)

    Activation energy of flow (Ea) was calculated from temperature sweeps of cheeses with contrasting characteristics to determine its usefulness in predicting rheological behavior upon heating. Cheddar, Colby, whole milk Mozzarella, low moisture part skim Mozzarella, Parmesan, soft goat, and Queso Fre...

  9. Historical evolution of oil painting media: A rheological study

    Science.gov (United States)

    de Viguerie, Laurence; Ducouret, Guylaine; Lequeux, François; Moutard-Martin, Thierry; Walter, Philippe

    2009-09-01

    Rheology is the science of flow, which is a phenomenon found in every painting operation, such as decorative paintings or protective coatings. In this article, the principles of rheology as applied to paintings and coatings are recalled in a first part and the rheological criteria required in the paint industry presented. Indeed, different flow behaviours leads to different finishes. The same procedure and techniques as in industry can be employed to explain some evolutions in oil painting aspects over the centuries. The first recipes for oil painting indicate the use of treated oil, resins and spirits. This article deals with the evolution of the composition of these systems as media for oil painting, according to rheological clues. During the Renaissance period, the media used were Newtonian or slightly shear thinning and allowed one a perfect levelling. Then techniques changed, paints became more opaque with less addition of oil/resin media, and brushstrokes appeared visible. Some preparations containing lead, oil and mastic resin, whose flow behaviour is closed to those required in industry, may have appeared during the 17th century and are still used and sold today. To cite this article: L. de Viguerie et al., C. R. Physique 10 (2009).

  10. Rheological properties of magnetoelectrorheological fluids with complex disperse phase

    International Nuclear Information System (INIS)

    The results of experimental investigations of mechanical properties of magnetoelectrorheological fluids - adaptive media, which respond to both electric and magnetic fields - are presented. The influence of the concentration of components of complex disperse phase on the rheological sensitivity is investigated. All compositions have shown a synergetic effect.

  11. THE THERMAL AND RHEOLOGICAL PROPERTIES OF LUPINUS ALBUS FLOUR

    Science.gov (United States)

    The thermal and rheological properties of lupin flour meal were investigated by DSC and rheometry. DSC study exhibited that non-de-fatted and de-fatted lupin meal had the identical thermal properties, and lupin had the same glass transition as the wheat protein gluten. By measuring the linear rheo...

  12. Continuum-mechanics-based rheological formulation for debris flow

    Science.gov (United States)

    Chen, Cheng-lung; Ling, Chi-Hai

    1993-01-01

    This paper aims to assess the validity of the generalized viscoplastic fluid (GVF) model in the light of both the classical relative-viscosity versus concentration relation and the dimensionless stress versus shear-rate squared relations based on kinetic theory, thereby addressing how to evaluate the rheological parameters of the GVF model using Bagnold's data.

  13. Modelling elongational and shear rheology of two LDPE melts.

    Czech Academy of Sciences Publication Activity Database

    Rolón-Garrido, V. H.; Pivokonský, Radek; Filip, Petr; Zatloukal, M.; Wagner, M. H.

    2009-01-01

    Ro?. 48, ?. 6 (2009), s. 691-697. ISSN 0035-4511 R&D Projects: GA AV ?R IAA200600703 Institutional research plan: CEZ:AV0Z20600510 Keywords : Rheology * MSF model * Shear flow * Elongational flow * Strain hardening * Low-density polyethylene * Polymer melts Subject RIV: BK - Fluid Dynamics Impact factor: 1.882, year: 2009

  14. Mechanisms of Steady State Rheological Behavior of Polymer Nanoparticle Composites

    Science.gov (United States)

    Pryamitsyn, Victor; Ganesan, Venkat

    2006-03-01

    We use a mesoscale computer simulation framework to delineate the the mechanisms behind the linear and nonlinear dynamical properties of polymer-nanoparticle composites. Our studies specifically focus on the regimes where the particle sizes and the interparticle distances become comparable to the polymer sizes. Our results indicate that the zero shear viscosities of the composite can be described in a manner similar to colloidal suspensions in a simple fluid when both the particle-induced changes in the polymer relaxation spectra and the polymer slip effects are accounted. The nonlinear shear rheology and the first normal stresses of the composite exhibits a subtle interplay between the shear thinning arising from the polymer and particle stresses. Overall, at dilute and semidilute nanoparticle concentrations, the composite shear rheology is dominated by the shear thinning of the polymer chains which in turn is modified by the presence of the particles. For higher particle loads, especially in regimes where particle jamming manifests, the polymeric contribution to the rheology becomes much less important and the shear thinning is dominated by the particles stresses. These competing efffects lead to intriguing polymer molecular weight, particle loading dependencies for the steady shear rheological behavior. Our results and mechanistic explanations are in excellent agreement with associated experimental observations.

  15. Rheological study of chitosan acetate solutions containing chitin nanofibrils.

    Czech Academy of Sciences Publication Activity Database

    Mikešová, Jana; Hašek, Jind?ich; Tishchenko, Galina; Morganti, P.

    2014-01-01

    Ro?. 112, 4 November (2014), s. 753-757. ISSN 0144-8617 Grant ostatní: European Commission(XE) FP7-INFRASTRUCTURES n-CHITOPACK Project reference: 315233 Institutional support: RVO:61389013 Keywords : rheology * chitosan solutions * chitin nanofibrils Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.916, year: 2013

  16. Laboratory procedure for the rheological characterization of slurry suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.Y.

    1996-02-01

    This procedure provides rheology measurements that are more reliable and accurate than those described in the technical procedure PNL-(WTC-006-4). Methods are provided to measure the sweep rheogram and steady shear viscosity with concentric cylinders, to measure the yield stress directly with a shear vane, and to measure the sweep rheogram with parallel plates.

  17. Heavy-water extraction from non-electrolytic hydrogen streams

    International Nuclear Information System (INIS)

    Heavy water may be produced from non-electrolytic hydrogen streams using a combined electrolysis and catalytic exchange process. The method comprises contacting feed water in a catalyst column with hydrogen gas originating partly from a non-electrolytic hydrogen stream and partly from an electrolytic hydrogen stream, so as to enrich the feed water with the deuterium extracted from both the non-electrolytic and electrolytic hydrogen gas, and passing the deuterium water to an electrolyser wherein the electrolytic hydrogen gas is generated and then fed through the catalyst column. (L.L.)

  18. Rheology of bauxite-based low-cement shotcreting castables

    Science.gov (United States)

    Zhou, Xianxin

    Continuous research efforts on castable technology since two decades have lead to the transformation of placement mode from vibrating to self-flow to pumping and shotcreting. Shotcreting (an installation process of self-flow castables by combining pumping and shooting), as a high efficient installation technique, has demanded castable composition with specific characteristics in terms of rheology. Though, the understanding on self-low castable technology is appreciable, the state-of-art on shotcreting has not yet been revealed and the literature on this area is scarce. This demands an in-depth research on this particular subject. The goal of the current investigation is to develop a predictive method of shotcreting castable with good pumpability and self-flowability through rheological approach and to validate the approach through shotcreting trial. A bauxite-based low-cement self-flow castable has been chosen for this purpose. Basically, three test methods have been adopted to fulfill the stated purpose: flow table test, viscometer and a new rheometer. A rheometer has been used to measure the rheological behavior of chosen castables. Through this, two rheological constants are obtained which are used to predict the pumpability of chosen system. This approach has overcome the drawback of measuring rheology of fine matrix portion only to predict the castable behaviors. Fine matrix rheology has also been evaluated using viscometer for comparison purpose. The relationship between viscometer and rheometer measurement are analysed. To support the results of rheometer and viscometer, conductivity measurement on fine matrix portion, exothermic profile measurement on castable mix, mechanical and physical properties measurements after drying and the appearance of castable green bodies are also carried out. The whole work is divided into four stages. In stage I, all raw materials used in this work, including bauxites, cements, microsilicas, reactive aluminas, have been characterized for chemical composition and particle size distribution. In stage II, the influence of different variables such as particle size distribution, dispersant, cement, microsilica, reactive alumina, water addition and aging time on the rheology of low-cement castables has been studied. (Abstract shortened by UMI.)

  19. Combination for electrolytic reduction of alumina

    Science.gov (United States)

    Brown, Craig W. (Seattle, WA); Brooks, Richard J. (Seattle, WA); Frizzle, Patrick B. (Lynnwood, WA); Juric, Drago D. (Bulleen, AU)

    2002-04-30

    An electrolytic bath for use during the electrolytic reduction of alumina to aluminum. The bath comprises molten electrolyte having the following ingredients: AlF.sub.3 and at least one salt selected from the group consisting of NaF, KF, and LiF; and about 0.004 wt. % to about 0.2 wt. %, based on total weight of the molten electrolyte, of at least one transition metal or at least one compound of the metal or both. The compound is, a fluoride; oxide, or carbonate. The metal is nickel, iron, copper, cobalt, or molybdenum. The bath is employed in a combination including a vessel for containing the bath and at least one non-consumable anode and at least one dimensionally stable cathode in the bath. Employing the instant bath during electrolytic reduction of alumina to aluminum improves the wetting of aluminum on a cathode by reducing or eliminating the formation of non-metallic deposits on the cathode.

  20. Electrodeposited silicate films: importance of supporting electrolyte.

    Science.gov (United States)

    Collinson, Maryanne M; Higgins, Daniel A; Kommidi, Roshna; Campbell-Rance, Debbie

    2008-02-01

    Silica and hybrid organic-inorganic films, ca. 100-200 nm thick, can be grown on glassy carbon electrodes through reactions initiated by electrogenerated hydroxide or hydronium ions in water under reductive and oxidative conditions, respectively. A variety of different alkoxysilanes (tetramethoxysilane and organoalkoxysilanes) and supporting electrolytes were used to evaluate whether film formation takes place on glassy carbon electrodes. The results of the study indicate that the acid-base properties of the supporting electrolyte are an important factor in determining whether film formation will take place. For cathodic electrodeposition, thin films can be formed using supporting electrolytes that are close to neutral, such as KCl, KNO3, and NaClO4. For anodic electrodeposition, thin films can be formed using supporting electrolytes that are acidic, such as, KH2PO4, HNO3, H2SO4, etc. The acidity/basicity effects of the electrolytes arise in part from the strong dependence of the hydrolysis and condensation rates of the silicon alkoxide precursors on pH. PMID:18173288

  1. The rheological transition in plagioclase-bearing magmas

    Science.gov (United States)

    Picard, D.; Arbaret, L.; Pichavant, M.; Champallier, R.; Launeau, P.

    2013-04-01

    Volcanological processes, such as melt segregation, ascent, and eruption, are directly dependent on the rheological behavior of magmatic suspensions. An increase of the crystal fraction of the suspension leads to the formation of a solid-particle network, which abruptly increases magma viscosity. The crystal fraction at which this rheological transition occurs depends on parameters such as the strain rate and the size, shape, and sorting of particles. To determine the influence of the crystal shape on the rheological transition, suspensions of plagioclase, a representative anisometric crystal, have been investigated at high temperatures and pressures. Synthetic suspensions with crystal fractions (?s) ranging from 0.38 to 0.75 were deformed both in compression and torsion in a Paterson apparatus at 300 MPa, 900°C and 800°C, and for strain rates between 1.0 × 10-5 and 1.0 × 10-3 s-1. All suspensions exhibit a non-Newtonian shear thinning rheological behavior. The experimental results, coupled with existing data and models at low crystal fractions (?s strain weakening, each characterized by a specific microstructure. In particular, a progressive evolution from a pervasive to a strain partitioning fabric is found when increasing the crystal fraction. Our results highlight the influence of both the strain rate and the shape of crystals on the rheological behavior of magmas. During crystallization, magmatic suspensions of anisometric minerals such as plagioclase would develop a solid-particle network earlier (?s ~ 0.3) than suspensions of isometric minerals (?s ~ 0.5). Our study shows that localization of strain early in the crystallization history of mushy zones in the magma chamber, near the conduit margins, and at the base of lava flows would facilitate the mobilization, the transfer, and the final emplacement at the surface of highly viscous, feldspar-rich magmas.

  2. A High-Conduction Ge Substituted Li3AsS4 Solid Electrolyte with Exceptional Low Activation Energy

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Gayatri [ORNL; Rangasamy, Ezhiylmurugan [ORNL; Li, Juchuan [ORNL; Chen, Yan [ORNL; An, Ke [ORNL; Dudney, Nancy J [ORNL; Liang, Chengdu [ORNL

    2014-01-01

    Lithium-ion conducting solid electrolytes show potential to enable high-energy-density secondary batteries and offer distinctive safety features as an advantage over traditional liquid electrolytes. Achieving the combination of high ionic conductivity, low activation energy, and outstanding electrochemical stability in crystalline solid electrolytes is a challenge for the synthesis of novel solid electrolytes. Herein we report an exceptionally low activation energy (Ea) and high room temperature superionic conductivity via facile aliovalent substitution of Li3AsS4 by Ge, which increased the conductivity by two orders of magnitude as compared to the parent compound. The composition Li3.334Ge0.334As0.666S4 has a high ionic conductivity of 1.12 mScm-1 at 27oC. Local Li+ hopping in this material is accompanied by distinctive low activation energy Ea of 0.17 eV being the lowest of Li+ solid conductors. Furthermore, this study demonstrates the efficacy of surface passivation of solid electrolyte to achieve compatibility with metallic lithium electrodes.

  3. Microporous gel electrolytes based on amphiphilic poly(vinylidene fluoride-co-hexafluoropropylene) for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yu Shicheng [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Chen Lie, E-mail: chenlienc@163.com [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China) and Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Chen Yiwang, E-mail: ywchen@ncu.edu.cn [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Jiangxi Provincial Key Laboratory of New Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Tong Yongfen [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); School of Environmental and Chemical Engineering, Nanchang Hangkong University, 696 Fenghe South Avenue, Nanchang 330063 (China)

    2012-03-15

    Poly(vinylidene fluoride-co-hexafluoropropylene) grafted poly(poly(ethylene glycol) methyl ether methacrylate) (PVDF-HFP-g-PPEGMA) is simply prepared by single-step synthesis directly via atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) from poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Thermal, mechanical, swelling and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, are evaluated and the effects of the various contents and average molecular weights of PEGMA on those properties are also been investigated. By phase inversion technique, the copolymer membranes tend to form well-defined microporous morphology with the increase of content and average molecular weight of PEGMA, due to the competition and cooperation between the hydrophilic PEGMA segments and hydrophobic PVDF-HFP. When these membranes are gelled with 1 M LiCF{sub 3}SO{sub 3} in ethylene carbonate (EC)/propylene carbonate (PC) (1:1, v/v), their saturated electrolyte uptakes (up to 323.5%) and ion conductivities (up to 2.01 Multiplication-Sign 10{sup -3} S cm{sup -1}) are dramatically improved with respect to the pristine PVDF-HFP, ascribing to the strong affinity of the hydrophilic PEGMA segments with the electrolytes. All the polymer electrolytes are electrochemically stable up to 4.7 V versus Li/Li{sup +}, and show good mechanical properties. Coin cells based on the polymer electrolytes show stable charge-discharge cycles and deliver discharge capacities to LiFePO{sub 4} is up to 156 mAh g{sup -1}.

  4. Microporous gel electrolytes based on amphiphilic poly(vinylidene fluoride-co-hexafluoropropylene) for lithium batteries

    International Nuclear Information System (INIS)

    Poly(vinylidene fluoride-co-hexafluoropropylene) grafted poly(poly(ethylene glycol) methyl ether methacrylate) (PVDF-HFP-g-PPEGMA) is simply prepared by single-step synthesis directly via atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) from poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Thermal, mechanical, swelling and electrochemical properties, as well as microstructures of the prepared polymer electrolytes, are evaluated and the effects of the various contents and average molecular weights of PEGMA on those properties are also been investigated. By phase inversion technique, the copolymer membranes tend to form well-defined microporous morphology with the increase of content and average molecular weight of PEGMA, due to the competition and cooperation between the hydrophilic PEGMA segments and hydrophobic PVDF-HFP. When these membranes are gelled with 1 M LiCF3SO3 in ethylene carbonate (EC)/propylene carbonate (PC) (1:1, v/v), their saturated electrolyte uptakes (up to 323.5%) and ion conductivities (up to 2.01 × 10-3 S cm-1) are dramatically improved with respect to the pristine PVDF-HFP, ascribing to the strong affinity of the hydrophilic PEGMA segments with the electrolytes. All the polymer electrolytes are electrochemically stable up to 4.7 V versus Li/Li+, and show good mechanical properties. Coin cells based on the polymer electrolytesn cells based on the polymer electrolytes show stable charge-discharge cycles and deliver discharge capacities to LiFePO4 is up to 156 mAh g-1.

  5. Optimization of the lithium-ion cell electrolyte composition through the use of the LiTDI salt

    International Nuclear Information System (INIS)

    Highlights: • LiTDI salt was tested in popular solvent mixtures as an electrolyte for Li-ion cells. • Beneficial broad conductivity plateaux with 0.3 mol kg?1 onset were found. • Viscosity, ionic associations and solvent-ions interactions are investigated. • Studied electrolytes have high lithium cation transference numbers (over 0.5). • Li+ conductivities of 0.3 mol kg?1 LiTDI are superior to industry standard mixtures. - Abstract: Optimization of electrolyte composition for future traction batteries is presented in this paper. Extensive systematic studies of electrochemical performance, material utility and subsequently cost are reported in order to obtain optimal combination. Lithium salt of TDI anion (4,5-dicyano-2-trifluoromethanoimidazole) is used due to its superior thermal stability (compared to other commercially available lithium salts), stability in case of moisture presence, electrochemical stability and possible material savings when used in electrolyte. Critical selection of solvent mixtures is made with respect to the price of components. Conductivity dependence of salt concentration is shown. For all studied systems the increased conductivity region is observed in the salt low and broad concentration range of 0.3 to 0.8 mol kg?1. The structural and rheological explanation of the mentioned feature is performed. Lithium cation transference numbers are measured for highly conductive samples and used as the secondary parameter in the optimization procedure. The highest values are recorded for the very low salt content: 0.31 mol kg?1 LiTDI in EC:DMC (1:2 weight ratio) (? = 5.09 mS cm?1, tLi+ = 0.622) and 0.4 mol kg?1 LiTDI in EC:DMC:DME (8:16:1 weight ratio) (? = 6.17 mS cm?1, tLi+ = 0.648) giving the opportunity to substantial material savings in batteries

  6. REMOVAL OF COPPER ELECTROLYTE CONTAMINANTS BY ADSORPTION

    Directory of Open Access Journals (Sweden)

    B Gabai

    1997-09-01

    Full Text Available Abstract - Selective adsorbents have become frequently used in industrial processes. Recent studies have shown the possibility of using adsorption to separate copper refinery electrolyte contaminants, with better results than those obtained with conventional techniques. During copper electrorefinning, many impurities may be found as dissolved metals present in the anode slime which forms on the electrode surface, accumulated in the electrolyte or incorporated into the refined copper on the cathode by deposition. In this study, synthetic zeolites, chelating resins and activated carbons were tested as adsorbents to select the best adsorbent performance, as well as the best operating temperature for the process. The experimental method applied was the finite bath, which consists in bringing the adsorbent into contact with a finite volume of electrolyte while controlling the temperature. The concentration of metals in the liquid phase was continuously monitored by atomic absorption spectrophotometry (AAS

  7. Composite Solid Electrolyte Containing Li+- Conducting Fibers

    Science.gov (United States)

    Appleby, A. John; Wang, Chunsheng; Zhang, Xiangwu

    2006-01-01

    Improved composite solid polymer electrolytes (CSPEs) are being developed for use in lithium-ion power cells. The matrix components of these composites, like those of some prior CSPEs, are high-molecular-weight dielectric polymers [generally based on polyethylene oxide (PEO)]. The filler components of these composites are continuous, highly-Li(+)-conductive, inorganic fibers. PEO-based polymers alone would be suitable for use as solid electrolytes, were it not for the fact that their room-temperature Li(+)-ion conductivities lie in the range between 10(exp -6) and 10(exp -8) S/cm, too low for practical applications. In a prior approach to formulating a CSPE, one utilizes nonconductive nanoscale inorganic filler particles to increase the interfacial stability of the conductive phase. The filler particles also trap some electrolyte impurities. The achievable increase in conductivity is limited by the nonconductive nature of the filler particles.

  8. REMOVAL OF COPPER ELECTROLYTE CONTAMINANTS BY ADSORPTION

    Scientific Electronic Library Online (English)

    B, Gabai; N.A.A., dos Santos; D.C.S., Azevêdo; S., Brandani; C.L., Cavalcante Jr..

    1997-09-01

    Full Text Available SciELO Brazil | Language: English Abstract in english Abstract - Selective adsorbents have become frequently used in industrial processes. Recent studies have shown the possibility of using adsorption to separate copper refinery electrolyte contaminants, with better results than those obtained with conventional techniques. During copper electrorefinnin [...] g, many impurities may be found as dissolved metals present in the anode slime which forms on the electrode surface, accumulated in the electrolyte or incorporated into the refined copper on the cathode by deposition. In this study, synthetic zeolites, chelating resins and activated carbons were tested as adsorbents to select the best adsorbent performance, as well as the best operating temperature for the process. The experimental method applied was the finite bath, which consists in bringing the adsorbent into contact with a finite volume of electrolyte while controlling the temperature. The concentration of metals in the liquid phase was continuously monitored by atomic absorption spectrophotometry (AAS)

  9. Stable emulsions with thermally responsive microstructure and rheology using poly(ethylene oxide) star polymers as emulsifiers.

    Science.gov (United States)

    Saigal, Trishna; Yoshikawa, Alex; Kloss, Dennis; Kato, Masanari; Golas, Patricia Lynn; Matyjaszewski, Krzysztof; Tilton, Robert D

    2013-03-15

    Poly(ethylene oxide) star polymers (PEO stars) were prepared by atom transfer radical polymerization of 2000 molecular weight PEO methacrylate macromonomer with divinylbenzene as a crosslinking co-monomer. With an average of 460 arms per star, these PEO stars had a 12 nm radius of gyration that is consistent with a dense polymer core surrounded by an extended PEO corona. The PEO stars were extremely efficient emulsifiers, stabilizing cyclohexane-in-water or xylene-in-water emulsions against coalescence for several months at aqueous phase concentrations as low as 0.008 wt% or 0.01 wt%, respectively. Consistent with their emulsifying performance, PEO star adsorption decreased interfacial tension by approximately 22 mN/m and imparted significant dilatational elasticity to the xylene/water interface. PEO stars were thermally responsive, displaying a cloud point upon heating in water that was tuned by addition of kosmotropic electrolytes, and they in turn produced xylene-in-water emulsions that were thermally responsive in terms of the dispersion state of the emulsion droplets and the emulsion rheology. Emulsions prepared at room temperature mainly had non-flocculated droplets. Heating such an emulsion above the cloud point temperature triggered droplet flocculation, but not coalescence, that in turn was associated with increased viscous and elastic moduli of the emulsion measured after cooling back to room temperature. Emulsions that initially were homogenized above the cloud point temperature and then cooled showed neither droplet flocculation nor rheological thickening relative to emulsions that were prepared and held at room temperature. A mechanism based on the bridging behavior of PEO stars adsorbed at the droplet/water interface is postulated to explain this thermal response of the emulsion microstructure. PMID:23266031

  10. Recent results on aqueous electrolyte cells

    Science.gov (United States)

    Wessells, Colin; Huggins, Robert A.; Cui, Yi

    2011-03-01

    The improved safety of aqueous electrolytes makes aqueous lithium-ion batteries an attractive alternative to commercial cells utilizing flammable and expensive organic electrolytes. Two important issues relating to their use have been addressed in this work. One is the extension of the usable voltage range by the incorporation of lithium salts, and the other is the investigation of a useful negative electrode reactant, LiTi2(PO4)3. The electrochemical stability of aqueous lithium salt solutions containing two lithium salts, LiNO3 and Li2SO4, has been characterized using a constant current technique. In both cases, concentrated solutions had effective electrolyte stability windows substantially greater than that of pure water under standard conditions. At an electrolyte leakage current of 10 ?A cm-2 between two platinum electrodes in 5 M LiNO3 the cell voltage can reach 2.0 V, whereas with a leakage current of 50 ?A cm-2 it can reach 2.3 V. LiTi2(PO4)3 was synthesized using a Pechini method and cycled in pH-neutral Li2SO4. At a reaction potential near the lower limit of electrolyte stability, an initial discharge capacity of 118 mAh g-1 was measured at a C/5 rate, while about 90% of this discharge capacity was retained after 100 cycles. This work demonstrates that it is possible to have useful aqueous electrolyte lithium-ion batteries using the LiTi2(PO4)3 anode with cell voltages of 2 V and above.

  11. Electrolytic plasma processing of steel surfaces

    International Nuclear Information System (INIS)

    The thermo-chemical treatments of steels with plasma is normally carried out in low-pressure ionized gaseous atmospheres. Among the treatments used most often are: nitruration, carburization and boronized. A plasma can also generate at atmospheric pressure. One way to produce it is with an electrochemical cell that works at a relatively high inter-electrode voltage and under conditions of heavy gas generation. This type of plasma is known as electrolytic plasma. This work studies the feasibility of using electrolytic plasma for the surface processing of steels. Two processes were selected: boronized and nitruration., for the hardening of two types of steel: one with low carbon (1020) and one with low alloy (4140). In the case of the nitruration, the 1020 steel was first aluminized. The electrolytes were aqueous solutions of borax for the boronizing and urea for the nitruration. The electrolytic plasmas were classified qualitatively, in relation with their luminosity by low, medium and high intensity. The boronizing was carried out with low intensity plasmas for a period of one hour. The nitruration was performed with plasmas of different intensities and for period of a few minutes to half an hour. The test pieces processed by electrolytic plasma were characterized by micro-hardness tests and X-ray diffraction. The maximum surface hardnesses obtained for the 1020 and 4140 steels were the following: 300 and 700 HV for the boronizing, and 1650 and 1200 HV for the nitrurazing, and 1650 and 1200 HV for the nitruration, respectively. The utilization of an electrolytic plasma permits the surface processing of steels, noticeably increasing their hardness. With this type of plasma some thermo-chemical surface treatments can be done very rapidly as well (CW)

  12. Electrolytes: transport properties and non-equilibrium thermodynamics

    International Nuclear Information System (INIS)

    This paper presents a review on the application of non-equilibrium thermodynamics to transport in electrolyte solutions, and some recent experimental work and results for mutual diffusion in electrolyte solutions

  13. Composite electrolytes for rechargeable lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, B. [Univ. of Dayton Research Inst., OH (United States); Scanlon, L.G. [Wright Lab., Wright-Patterson AFB, OH (United States). Aero Propulsion and Power Directorate

    1997-12-31

    In the last two decades, considerable efforts were made to develop solid electrolytes for lithium rechargeable batteries. The conductivity of these electrolytes is marginal for many applications. In addition, they possess a low cationic transport number and poor interfacial stability with lithium electrodes., In view of these deficiencies, this paper explores a new technical approach which involves using grain boundaries as the conduction path for lithium ions. The authors will also report preliminary data on two model systems: Li{sub 3}N-LiPO{sub 3} and LiI-LiPO{sub 3}.

  14. Classical thermodynamics of non-electrolyte solutions

    CERN Document Server

    Van Ness, H C

    1964-01-01

    Classical Thermodynamics of Non-Electrolyte Solutions covers the historical development of classical thermodynamics that concerns the properties of vapor and liquid solutions of non-electrolytes. Classical thermodynamics is a network of equations, developed through the formal logic of mathematics from a very few fundamental postulates and leading to a great variety of useful deductions. This book is composed of seven chapters and begins with discussions on the fundamentals of thermodynamics and the thermodynamic properties of fluids. The succeeding chapter presents the equations of state for

  15. Solid electrolytes strengthened by metal dispersions

    Science.gov (United States)

    Lauf, Robert J. (Oak Ridge, TN); Morgan, Chester S. (Oak Ridge, TN)

    1983-01-01

    An improvement in solid electrolytes of advanced secondary batteries of the sodium-sulfur, sodium-halogen, and like combinations is achieved by providing said battery with a cermet electrolyte containing a metal dispersion ranging from 0.1 to 10.0 vol. % of a substantially nonreactive metal selected from the group consisting essentially of Pt, Cr, Fe, Co, Ni, Nb, their alloys, and their physical mixtures in the elemental or uncombined state, the remainder of said cermet being an ion-conductive ceramic material.

  16. Impedance of metal-solid electrolyte interfaces

    International Nuclear Information System (INIS)

    Previous studies have shown that the impedance of solid state cells such as Pt/Na ?-alumina/Pt can be described by the function which depends on R, the bulk resistance of the electrolyte and two terms which represent the ac response of the metal-electrolyte interface, D and n. Deviation from ideal behavior (N6 Hz. The effect of surface roughness is illustrated. The impedances observed for the same Pt/Na ?-alumina/Pt cell at several temperatures are represented and discussed

  17. Improved Preparation Of Solid-Electrolyte Films

    Science.gov (United States)

    Nagasubramanian, Ganesan; Attia, Alan

    1995-01-01

    Modified process ensures compatability among components. Improved chemical-blending procedure produces composite material for thin, large-area solid-electrolyte films for lithium batteries. Films have uniform compositions and dimensionally stable. Transport number of their lithium cations is high, close to unity. Batteries made with these films expected to have energy and power densities up to about 100 W h/kg and 100 W/kg, respectively. Previous version of composite material described in "Composite Solid Electrolyte for Lithium Cells" (NPO-18694).

  18. On the electrolytic generation of hydrated electron

    International Nuclear Information System (INIS)

    Investigations on the electrolytic generation of hydrated electron in oxygenated as well as oxygen-free solutions at different pH were undertaken. Since sup(-e)aq is known to react rapidly with O2 yielding the transient O2- ion, the latter was looked for through its interaction with phosphite ions resulting in their oxidation near the cathode. It appears from the results that in electrolytic processes, the primary electron (esup(-)sub(cathode)) probably reacts directly with reactive solutes like oxygen, bypassing the hydration step. Data obtained in oxygen-free solutions, however, support the possible formation of hydrated electron at least in alkaline solutions. (author)

  19. Solid composite electrolytes for lithium batteries

    Science.gov (United States)

    Kumar, Binod (Dayton, OH); Scanlon, Jr., Lawrence G. (Fairborn, OH)

    2001-01-01

    Solid composite electrolytes are provided for use in lithium batteries which exhibit moderate to high ionic conductivity at ambient temperatures and low activation energies. In one embodiment, a polymer-ceramic composite electrolyte containing poly(ethylene oxide), lithium tetrafluoroborate and titanium dioxide is provided in the form of an annealed film having a room temperature conductivity of from 10.sup.-5 S cm.sup.-1 to 10.sup.-3 S cm.sup.-1 and an activation energy of about 0.5 eV.

  20. Rheologies and ages of lava flows on Elysium Mons, Mars

    Science.gov (United States)

    Pasckert, Jan Hendrik; Hiesinger, Harald; Reiss, Dennis

    2012-05-01

    We present results of our study of the rheologies and ages of lava flows in the Elysium Mons region of Mars. Previous studies have shown that the geometric dimensions of lava flows reflect rheological properties such as yield strength, effusion rate and viscosity. In this study the rheological properties of lava flows in the Elysium Mons region were determined and compared to the rheologies of the Ascraeus Mons lava flows. We also derived new crater size-frequency distribution measurements (CSFDs) for the Elysium lava flows to identify possible changes in the rheological properties with time. In addition, possible changes in the rheological properties with the distance from the caldera of Elysium Mons were analyzed. In total, 35 lava flows on and around Elysium Mons were mapped, and divided into three groups, lava flows on the flanks of Elysium Mons, in the plains between the three volcanoes Elysium Mons, Hecates and Albor Tholus and lava flows south of Albor Tholus. The rheological properties of 32 of these flows could be determined. Based on our morphometric measurements of each individual lava flow, estimates for the yield strengths, effusion rates, viscosities, and eruption duration of the studied lava flows were made. The yield strengths of the investigated lava flows range from ˜3.8 × 102 Pa to ˜1.5 × 104 Pa, with an average of ˜3.0 × 103 Pa. These yield strengths are in good agreement with estimates for terrestrial basaltic lava flows. The effusion rates are on average ˜747 m3 s-1, ranging from ˜99 to 4450 m3 s-1. The viscosities are on average ˜4.1 × 106 Pa s, with a range of 1.2 × 105 Pa s to 3.1 × 107 Pa s. The eruption durations of the flows were calculated to be between 6 and 183 days, with an average of ˜51 days. The determined rheological properties are generally very similar to those of other volcanic regions on Mars, such as on Ascraeus Mons in the Tharsis region. Calculated yield strengths and viscosities point to a basaltic/andesitic composition of the lava flows, similar to basaltic or andesitic a'a lava flows on Earth. Absolute model ages of all 35 lava flows on Elysium Mons were derived from crater size-frequency distribution measurements (CSFD). The derived model ages show a wide variation from about 632 Ma to 3460 Ma. Crater size-frequency distribution measurements of the Elysium Mons caldera show an age of ˜1640 Ma, which is consistent with the resurfacing age of Werner (2009). Significant changes of the rheologies with time could not be observed. Similarly, we did not observe systematic changes in ages with increasing distances of lava flows from the Elysium Mons caldera.

  1. Liquid Redox Electrolytes for Dye-Sensitized Solar Cells

    OpenAIRE

    Yu, Ze

    2012-01-01

    This thesis focuses on liquid redox electrolytes in dye-sensitized solar cells (DSCs). A liquid redox electrolyte, as one of the key constituents in DSCs, typically consists of a redox mediator, additives and a solvent. This thesis work concerns all these three aspects of liquid electrolytes, aiming through fundamental insights to enhance the photovoltaic performances of liquid DSCs. Initial attention has been paid to the iodine concentration effects in ionic liquid (IL)-based electrolytes. I...

  2. Poly(phosphazene) solid state polymeric electrolytes for Li energy storage devices

    Science.gov (United States)

    Palmer, David N.

    ESCA and solvatochromic related modeling data suggest that poly-2-(2-methoxyethoxy/ethoxy/phosphazene) and related polymers may be good starting material candidates for room temperature solid-state Li salt complex electrolytes for thin film Li energy storage devices. Cyclic cell, complex impedance and ionic conductivity data indicate that the practical application of these or similar materials to primary and secondary Li devices is dependent on several factors including polymer syntheses methods; polymer substituent group moiety, Li anode reactive species after synthesis and purification, thin-film stability and resolution of current carrying limitations.

  3. Impact of particle size on interaction forces between ettringite and dispersing comb-polymers in various electrolyte solutions.

    Science.gov (United States)

    Ferrari, Lucia; Kaufmann, Josef; Winnefeld, Frank; Plank, Johann

    2014-04-01

    The inter-particle forces play a fundamental role for the flow properties of a particle suspension in response to shear stresses. In concrete applications, cement admixtures based on comb-polymers like polycarboxylate-ether-based superplasticizer (PCE) are used to control the rheological behavior of the fresh mixtures, as it is negatively impacted by certain early hydration products, like the mineral ettringite. In this work, dispersion forces due to PCE were measured directly at the surface of ettringite crystals in different electrolyte solutions by the means of atomic force microscopy (AFM) applying spherical and sharp silicon dioxide tips. Results show an effective repulsion between ettringite surface and AFM tips for solutions above the IEP of ettringite (pH?12) and significant attraction in solution at lower pH. The addition of polyelectrolytes in solution provides dispersion forces exclusively between the sharp tips (radius ? 10 nm) and the ettringite surface, whereas the polymer layer at the ettringite surface results to be unable to disperse large colloidal probes (radius ? 10 ?m). A simple modeling of the inter-particle forces explains that, for large particles, the steric hindrance of the studied PCE molecules is not high enough to compensate for the Van der Waals and the attractive electrostatic contributions. Therefore, in cement suspensions the impact of ettringite on rheology is probably not only related to the particle charge, but also related to the involved particle sizes. PMID:24491324

  4. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2001-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These endeavors have lead us to a solution which we think is quite unique and should allow us to obtain flaw free dense films of thickness in the 0.5 to 5 {micro}m range at processing temperatures {le} 900{sup o}. The process involves the deposition of a slurry of nanocrystalline YSZ onto a presintered porous LSM substrate. The key element in the deposition is that the slurry contains sufficient YSZ polymer precursor to allow adhesion of the YSZ particles to each other and the surface after annealing at about 600 C. This allows the formation of a porous film of 0.5 to 5 {micro}m thick which adheres to the surface. After formation of this film, YSZ polymer precursor is allowed to impregnate the porous surface layer (capillary forces tend to confine the polymer solution in the nanoporous layer). After several impregnation/heat treatment cycles, a dense film results. Within the next few months, this process should be developed to the point that single cell measurements can be made on 0.5 to 5 {micro}m films on a LSM substrate. This type of processing allows the formation of essentially flaw free films over areas > 1 cm{sup 2}.

  5. Ultrasonic hydrometer. [Specific gravity of electrolyte

    Science.gov (United States)

    Swoboda, C.A.

    1982-03-09

    The disclosed ultrasonic hydrometer determines the specific gravity (density) of the electrolyte of a wet battery, such as a lead-acid battery. The hydrometer utilizes a transducer that when excited emits an ultrasonic impulse that traverses through the electrolyte back and forth between spaced sonic surfaces. The transducer detects the returning impulse, and means measures the time t between the initial and returning impulses. Considering the distance d between the spaced sonic surfaces and the measured time t, the sonic velocity V is calculated with the equation V = 2d/t. The hydrometer also utilizes a thermocouple to measure the electrolyte temperature. A hydrometer database correlates three variable parameters including sonic velocity in and temperature and specific gravity of the electrolyte, for temperature values between 0 and 40/sup 0/C and for specific gravity values between 1.05 and 1.30. Upon knowing two parameters (the calculated sonic velocity and the measured temperature), the third parameter (specific gravity) can be uniquely found in the database. The hydrometer utilizes a microprocessor for data storage and manipulation.

  6. Epithelial Pathways in Choroid Plexus Electrolyte Transport

    Science.gov (United States)

    Helle Damkier (Aarhus University Anatomy)

    2010-08-01

    A stable intraventricular milieu is crucial for maintaining normal neuronal function. The choroid plexus epithelium produces the cerebrospinal fluid and in doing so influences the chemical composition of the interstitial fluid of the brain. Here, we review the molecular pathways involved in transport of the electrolytes Na+, K+, ClÂ?, and HCO across the choroid plexus epithelium.

  7. Conductivity studies on solid polymer electrolytes

    OpenAIRE

    Sequeira, C.; Plancha, M.; Arau?jo, L.

    1994-01-01

    This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the features, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed.

  8. Miniaturized Amperometric Solid Electrolyte Carbon Dioxide Sensors

    Science.gov (United States)

    Hunter, G. W.; Xu, J. C.; Liu, C. C.; Hammond, J. W.; Ward, B.; Lukco, D.; Lampard, P.; Artale, M.; Androjna, D.

    2006-01-01

    A miniaturized electrochemical carbon dioxide (CO2) sensor using Na3Z r2Si2PO12 (NASICON) as a solid electrolyte has been fabricated and de monstrated. Microfabrication techniques were used for sensor fabricat ion to yield a sensing area around 1.0 mm x 1.1 mm. The NASICON solid electrolyte and the Na2CO3/BaCO3 (1:1.7 molar ratio) auxiliary elect rolyte were deposited by sputtering in between and on top of the inte rdigitated finger-shaped platinum electrodes. This structure maximize s the length of the three-phase boundary (electrode, solid electrolyt e, and auxiliary electrolyte), which is critical for gas sensing. The robust CO2 sensor operated up to 600 C in an amperometric mode and a ttempts were made to optimize sensor operating parameters. Concentrat ions of CO2 between 0.02% and 4% were detected and the overall sensor performance was evaluated. Linear response of sensor current output to ln[CO2 concentration] ranging from 0.02% to 1% was achieved.

  9. Adsorption equation of electrolytes on solids

    International Nuclear Information System (INIS)

    Equation of electrolyte mixture, CaCl2 and NaI in particular, adsorption on a solid adsorbent has been derived in terms of average activity coefficients. Possible deformation of adsorbent in the course of adsorption and the difference in mechanical and thermodynamic surface tension in a solid body are made allowance for. 6 refs

  10. Conductivity studies on solid polymer electrolytes

    International Nuclear Information System (INIS)

    This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the feature, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed. (orig.)

  11. Composite Solid Electrolyte for Li Battery Applications

    Science.gov (United States)

    Nagasubramanian, G.; Attia, A. I.; Halpert, G.; Peled, E.

    1993-01-01

    The electrochemical, bulk and interfacial properties of the polyethylene oxide (PEO) based composite solid electrolyte (CSE) comprising LiI, PEO, and Al2O3 have been evaluated for Li battery applications. The bulk interfacial and transport properties of the CSEs seem to strongly depend on the alumina particle size. For the CSE films with 0.05 micron alumina while the bulk conductivity is around 10(exp -4) (mho/cm) at 103 C, the Li ion transport number seems to be close to unity at the same temperature. Compared to the PEO electrolyte this polymer composite electrolyte seems to exhibit robust mechanical and interfacial properties. We have studied three different films with three different alumina sizes in the range 0.01-0.3 micron. Effects of Al2O3 particle size on the electrochemical performance of polymer composite electrolyte is discussed. With TiS2 as cathode a 10 mAh small capacity cell was charged and discharged at C/40 and C/20 rates respectively.

  12. Macroscopic Modeling of Polymer-Electrolyte Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, A.Z.; Newman, J.

    2007-04-01

    In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.

  13. Energetics of the Semiconductor-Electrolyte Interface.

    Science.gov (United States)

    Turner, John A.

    1983-01-01

    The use of semiconductors as electrodes for electrochemistry requires an understanding of both solid-state physics and electrochemistry, since phenomena associated with both disciplines are seen in semiconductor/electrolyte systems. The interfacial energetics of these systems are discussed. (JN)

  14. Solubility prediction of weak electrolyte mixtures

    OpenAIRE

    Fe?votte, Gilles; Zhang, Xiang; Qian, Gang; Zhou, Xing-gui; Yuan, Wei-kang

    2011-01-01

    The solubility of materials is a thermodynamic variable that depends on their chemical composition and with temperature. Solubility is also affected by the pH, by the presence of additional species in the solution, and by the use of different solvents. On electrolyte, the calculation of solubility requires that the mean ionic activity coefficient be known along with a thermodynamic solubility product.

  15. A study of electrolytic tritium production

    International Nuclear Information System (INIS)

    Tritium production is being investigated using cathodes made from palladium and its alloys with various surface treatments. Three anode materials have been studied as well as different impurities in the electrolyte. Tritium has been produced in about 10% of the cells studied but there is, as yet, no pattern of behavior that would make the effect predictable. 15 refs., 4 figs., 6 tabs

  16. Fuel cell electrolyte membrane with basic polymer

    Science.gov (United States)

    Larson, James M.; Pham, Phat T.; Frey, Matthew H.; Hamrock, Steven J.; Haugen, Gregory M.; Lamanna, William M.

    2012-12-04

    The present invention is an electrolyte membrane comprising an acid and a basic polymer, where the acid is a low-volatile acid that is fluorinated and is either oligomeric or non-polymeric, and where the basic polymer is protonated by the acid and is stable to hydrolysis.

  17. Surface functionalization by molten salt electrolytic processes

    International Nuclear Information System (INIS)

    The attention has been paid to surface functionalization by molten salt electrolytic processes. Three topics on the experimental results obtained by the authors are described: the electrochemical formation of zirconium metal film and zirconium alloy film on ceramic, surface nitriding of titanium by electrochemical process and an anodic oxide film formation on nickel. (author)

  18. CHARACTERIZATION OF SURFACE STATES AT A SEMICONDUCTOR ELECTROLYTE INTERFACE BY ELECTROLYTE ELECTROREFLECTANCE SPECTROSCOPY

    OpenAIRE

    Tomkiewicz, M.; Siripala, W.

    1983-01-01

    Supra bandgap and subband gap Electrolyte Electroreflectance is being used to characterize surface states at semiconductor liquid interfaces. The surface states can manifest themselves either through direct optical transitions as in the case of n - TiO2 - aqueous electrolyte interface or through their effect on the response of the Fermi level to small changes in the electrode potential as in the case of single crystal CdIn2Se4 in polysulfide solutions.

  19. Investigations of rheological properties of diclofenac sodium gel preparation

    Directory of Open Access Journals (Sweden)

    Firuza Maksudova

    2013-04-01

    Full Text Available It is well-known that the majority of non-steroidal anti-inflammatory drugs (NSAIDs are ulcerogenic. Gel or ointment preparations of NSAIDs are free from this side-effect, which is a prerequisite for the increase of aforementioned forms of NSAIDs. A major quality indicator of gels and ointments are rheological properties. Along with determining the quality of preparation, they influence manufacturing, expiration date and terms of storage. This article demonstrates the results of investigation of rheological indices of 3% gel preparation of diclofenac sodium such as plasticity, structural viscosity, and thixotropy. Obtained results confirm that the developed gel preparation has thixotropy, plasticity and is classified as a Bingham system.

  20. Simulation and rheological analysis of Hanford Tank 241-SY-101

    International Nuclear Information System (INIS)

    Rheological characterization and small scale simulation of Hanford Tank 241-SY-101 has been initiated to aid in the remediation efforts for the Department of Energy Hanford Site. The study has been initiated in response to growing concerns about the potential flammability hazard pertaining to the periodic release of up to 10,000 cubic feet of hydrogen, nitrous oxide, nitrogen, and ammonia gases. Various stimulants emulating the radioactive waste stored in this tank have been used to ascertain the rheological parameters of the waste, simulate the ongoing processes of gas generation and release phenomenon inside the tank, and determine the feasibility of jet mixing to achieve a controlled release of the gas mixture