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Sample records for electrolytes synthesis rheology

  1. Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Saad A.: Fedkiw Peter S.; Baker, Gregory L.

    2007-01-24

    The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength

  2. Novel reversible and switchable electrolytes based on magneto-rheology

    Science.gov (United States)

    Ding, Jie; Peng, Gangrou; Shu, Kewei; Wang, Caiyun; Tian, Tongfei; Yang, Wenrong; Zhang, Yuanchao; Wallace, Gordon G.; Li, Weihua

    2015-10-01

    Replacing organic liquid electrolytes with solid electrolytes has led to a new perspective on batteries, enabling high-energy battery chemistry with intrinsically safe cell designs. However, most solid/gel electrolytes are easily deformed; under extreme deformation, leakage and/or short-circuiting can occur. Here, we report a novel magneto-rheological electrolyte (MR electrolyte) that responds to changes in an external magnetic field; the electrolyte exhibits low viscosity in the absence of a magnetic field and increased viscosity or a solid-like phase in the presence of a magnetic field. This change from a liquid to solid does not significantly change the conductivity of the MR electrolyte. This work introduces a new class of magnetically sensitive solid electrolytes that can enhance impact resistance and prevent leakage from electronic devices through reversible active switching of their mechanical properties.

  3. Electrolytic Synthesis and Characterizations of Silver Nanopowder

    OpenAIRE

    T. Theivasanthi; M. Alagar

    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 speci...

  4. Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

    OpenAIRE

    MichaelStoukides

    2014-01-01

    Developed in the early 1900s, 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 fa...

  5. THE EFFECT OF ELECTROLYTE CONCENTRATION AND PH ON THE FLOCCULATION AND RHEOLOGICAL BEHAVIOUR OF KAOLINITE SUSPENSIONS

    Directory of Open Access Journals (Sweden)

    M. S. NASSER

    2009-12-01

    Full Text Available The effects of the electrolyte concentration and pH on the settling behaviour, floc sizes and rheological behaviour of kaolinite suspensions were investigated. The results show that the settling behaviour of kaolinite changes with the ionic strength and pH of the suspension. In the acidic pH range, (pH 2 particles settle in flocculated form regardless of electrolyte concentration, however, in the basic pH range, the particles settle both, in dispersed form (at lower electrolyte concentrations and in flocculated form (at higher electrolyte concentrations. The Bingham yield stress and time-dependent behaviour for these flocculated and deflocculated suspensions was investigated. In this study, the fundamental of structural kinetic model (SKM was used to investigate the time-dependent viscosity behaviour of flocculated and deflocculated kaolinite suspensions. It was found that the kaolinite suspensions in the deflocculated form show viscosity time-independent behaviour with negligible Bingham yield stress. While, the flocculated suspensions show marked non-Newtonian time-dependent behaviour. This work has been very successful in establishing the link among particle-particle interactions, floc size, Bingham yield stress, breakdown rate constant, and extent of thixotropy.

  6. 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.

  7. 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 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)

  8. 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.

  9. Synthesis and Rheology of Model Comb Polymer Architectures

    OpenAIRE

    Kempf, Michael

    2012-01-01

    For a better understanding of the extent of branching and its influence on the rheological properties of commercial branched polymers, well-defined linear and branched (comb) model polymers were synthesized. The correlation between the melt rheological properties and the polymer topology was investigated under small amplitude oscillatory shear (SAOS), uniaxial extension and medium- (MAOS) respectively large amplitude oscillatory shear (LAOS) in combination with Fourier-Transform rheology.

  10. 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

  11. Rheology of concentrated, heterogeneous slurries containing >1M electrolyte - a case study in nuclear waste suspensions

    International Nuclear Information System (INIS)

    Neutralized current acid waste (NCAW) simulant was produced to chemically simulate the properties of the washed solids of a high-level waste stream generated from the reprocessing of irradiated nuclear fuel. The NCAW simulant was evaluated by viscosity, yield stress, solid loading, particle size, and anion and cation solubility. For similar solid loadings and pH, the NCAW simulant had higher yield stresses and viscosities than NCAW. The differences in the rheological behavior between NCAW and the simulant were attributed to differences in the suspension microstructure. The effects of formic and nitric acid additions to the NCAW simulant on yield stress and viscosity were measured as a function of solids loading and pH for both acids. In addition, anion and cation solubilities were evaluated. Viscosity and yield stress decreased as pH was lowered. The change in rheological properties was attributed to floc breakdown and particle dissolution, which were initiated by the solubilization of the waste constituents. These results show that the effectiveness of the simulant studied here is unproven rheologically. (orig.)

  12. Synthesis and rheological behavior of atactic polypropylene molecular bottlebrushes

    Science.gov (United States)

    Dalsin, Samuel; Bates, Frank; Hillmyer, Marc

    2014-03-01

    Molecular bottlebrushes are branched polymer structures characterized by an extremely high density of polymeric side chains emanating from a central backbone. Due to unique conformational and rheological properties, molecular bottlebrushes have become attractive candidates for developing new photonic bandgap materials, nanotubes and nanowires, and rheological modifiers. In this study, bottlebrushes comprised of atactic polypropylene (aPP) side chains were synthesized via ring-opening metathesis polymerization of norbornenyl-terminated aPP macromonomers. A series of bottlebrush polymers with fixed side chain length and variable backbone length was prepared using Grubbs' third-generation catalyst, yielding products with low dispersity in less than five minutes reaction time. Small-amplitude oscillatory shear measurements were performed to examine linear viscoelastic properties. Master curves of all bottlebrush polymers exhibited relaxation spectra devoid of any entanglement plateau, despite high molecular weights (up to 892 kg/mol). Lack of entanglement was further confirmed by zero shear viscosity experiments, which displayed a nearly linear dependence on molecular weight. These rheological properties are compared directly with a linear aPP control sample. Supported by ExxonMobil Chemical Company.

  13. Synthesis and rheological properties of poly(vinyl alcohol)

    International Nuclear Information System (INIS)

    Vinyl acetate usually used in PVA resin preparation was converted to PVAc by bulk poly-merization using AIBN as a initiator and PVA was synthesized by changing the concentration of NaOH added for saponification subsequently. As a result of estimating molecular weight using GPC, molecular weight increased as the NaOH concentration increased to 2.5 N, 5.0 N, 7.5 N and 10.0 N and polydispersity had similar values of 2.1?2.3, however, showed slightly decreasing tendency. In addition, PVA saponificated by 10.0 N-NaOH showed high syndiotacticity in observation of tacticity using NMR spectroscopy. From this fact, the degree of tacticity was predicted to be high and it was in good agreement with the tendency of polydisperisity by GPC. Also, from the result of FT-IR spectroscopy, it might be known that hydrolysis was more promoted in the PVA with 10.0 N-NaOH than other NaOH concentration. Intrinsic viscosity measured using Ubbelohde viscometer, which increased as the concentration of NaOH added for saponification increased. The change of shear strength with the change of shear rate was investigated using Brookfield viscometer, in consequence, viscosity of PVA synthesized decreased as shear rate increased. PVA solution confirmed to show the shear thinning behavior by Casson plot and PVA with 10.0 N-NaOH had the largest yield value. DSC measurement was performed to know the thermal properties of PVA. Tp had nearly constant value of 214 .deg. C in all cases except for adding 2.5 N-NaOH and ?H was increased as the concentration of NaOH increased. From this properties, it was concluded that the degree of hydrogen bonding was proportional to the added concentration of NaOH and the increase of the degree of hydrogen bonding and hydrophobic interaction could affect the rheological and thermal properties of title compound

  14. 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.

  15. 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.

  16. Electrolytes and Electrodes for Electrochemical Synthesis of Ammonia

    DEFF Research Database (Denmark)

    Lapina, Alberto

    .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...... evaluate their applicability to electrochemical synthesis of ammonia. First a number of potential electrolytes are investigated 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...

  17. 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

  18. 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.

  19. 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.

  20. Synthesis and characterization of polyethylene oxide based nano composite electrolyte

    Indian Academy of Sciences (India)

    M Malathi; K Tamilarasan

    2014-08-01

    Polyethylene oxide (PEO) – montmorillonite (MMT) composite electrolytes were synthesised by solution casting technique. The salt used for the study is Lithium perchlorate (LiClO4). The morphology and percentage of crystallinity data were obtained through X-ray Diffraction and Differential Scanning Caloriemetry. The ionic conductivity of the polymer electrolytes was studied by impedance spectroscopy. The addition of MMT resulted in an increase in conductivity over the temperature range of 25–60°C. The ionic conductivity of a composite polymer electrolyte containing 1.2 wt% MMT was 1 × 10-5 S cm−1 at 25°C, which is at least one order of magnitude higher than that of the polymer electrolyte (4 × 10-7S cm−1). The increase in ionic conductivity is explained on the basis of crystallinity of the polymer electrolyte.

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

    International Nuclear Information System (INIS)

    Highlights: ? Alkaline homogeneous electrolyte with transition metals complexes. ? Coatings contain metallic iron, nickel and their oxides in alumina–silica matrix. ? 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.

  2. Synthesis and electrochemical study of polymer-electrolyte for high energetic density accumulator.

    Czech Academy of Sciences Publication Activity Database

    Kerouani, N.; Vondrák, Ji?í

    Vol. 1. Brno : Akademické nakladatelství CERM, 2000 - (Vondrák, J.; Sedla?íková, M.), s. 4.1-4.6 ISBN 80-214-1614-9. [Advanced Batteries and Accumulators /1./. Brno (CZ), 28.08.2000-01.09.2000] Institutional research plan: CEZ:AV0Z4032918 Keywords : synthesis * polymer -electrolyte * electrochemistry Subject RIV: CG - Electrochemistry

  3. Synthesis of High-Quality Graphene through Electrochemical Exfoliation of Graphite in Alkaline Electrolyte

    OpenAIRE

    Tripathi, Prashant; Patel, Ch. Ravi Prakash; Shaz, M. A.; Srivastava, O N

    2013-01-01

    Owing to wide variety of applications of graphene, high-quality and economical way of synthesizing graphene is highly desirable. In this study, we report a cost effective and simple approach to production of high-quality graphene. Here the synthesis route is based on electrochemical exfoliation of graphite. Instead of using strong acids (which oxidise and damage the geometrical topology of graphene), we have used alkaline solution (KOH dissolved in water) as electrolyte. TEM analysis shows th...

  4. Electrochemical synthesis of ammonia at atmospheric pressure and low temperature in a solid polymer electrolyte cell

    OpenAIRE

    Kordali, V.; Kyriacou, G.; Lambrou, Ch.

    2012-01-01

    The heterogeneous electrocatalytic synthesis of ammonia rom nitrogen and water is carried out at Ru cathodes, using a Solid Polymer Electrolyte Cell (SPE), at atmospheric pressure and low temperature; the reduction rate increases with increase of temperature up to 100 °C, while with the increase of the negative potential a maximum is observed at 21.02 V vs. Ag/AgCl and gradually decreases in the hydrogen discharge region.

  5. Synthesis and Characterization of Thin Film Lithium-Ion Batteries Using Polymer Electrolytes

    Science.gov (United States)

    Maranchi, Jeffrey P.; Kumta, Prashant N.; Hepp, Aloysius F.; Raffaelle, Ryne P.

    2002-01-01

    The present paper describes the integration of thin film electrodes with polymer electrolytes to form a complete thin film lithium-ion battery. Thin film batteries of the type, LiCoO2 [PAN, EC, PC, LiN(CF3SO2)2] SnO2 have been fabricated. The results of the synthesis and characterization studies will be presented and discussed.

  6. 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 Sílvia 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 ...

  7. Synthesis of tough nanoporous metals by controlled electrolytic dealloying

    Science.gov (United States)

    Senior, N. A.; Newman, R. C.

    2006-05-01

    Dealloying (selective dissolution) of homogeneous metallic alloys such as Ag-Au generates nanoporous metals with intriguing properties. Until now, it has not been possible routinely to prepare such materials in a form in which they would resist mechanical strains, such as might be encountered in applications as membranes, sensors or actuators. Now a threshold potential has been identified, for dealloying of Ag-Au in aqueous HClO4, above which spontaneous transgranular fracture occurs due to the formation of a monolayer of gold hydroxide. The fracture mechanism involves a reduction in surface diffusivity, preventing relaxation of induced tension in the porous material, and possible more exotic effects. By optimizing the Au content of the alloy, staying below the threshold potential and increasing the temperature of the electrolyte, dealloyed membranes with a high degree of mechanical integrity have been prepared. When prepared in this way, the nanoporous material shows peculiar behaviours, such as grain-boundary sintering under annealing, and reversible stiffening and embrittlement when dried in air.

  8. Electrolytic Synthesis and Characterization of Electrocatalytic Ni-W Alloy

    Science.gov (United States)

    Elias, Liju; Scott, Keith; Hegde, A. Chitharanjan

    2015-11-01

    Inspired by the more positive (about 0.38 V nobler) discharge potential of hydrogen on Ni-W alloy compared to that on both Ni and W, a Ni-W alloy has been developed electrolytically as an efficient electrode material for water electrolysis. The deposition conditions, for peak performance of the electrodeposits for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH medium have been optimized. Electrocatalytic activity of the coatings, deposited at different current densities (c.d.'s) for water splitting reactions of HER and OER was tested by cyclic voltammetry and chronopotentiometry. It was found that Ni-W alloys deposited, at 4.0 A/dm2 (having about 12.49 wt.% W) and 1.0 A/dm2 (having about 0.95 wt.% W) are good electrode materials as cathode (for HER) and anode (for OER), respectively. A dependency of the electrocatalytic activity for HER and OER with relative amount of Ni and W, in the deposit was found. The variation of electrocatalytic activity with W content showed the existence of a synergism between high-catalytic property of W (due to low hydrogen overvoltage) and Ni (having increased adsorption of OH- ions), for hydrogen (as cathode) and oxygen (as anode) evolution, respectively. Electrocatalytic activities of the coatings, developed at different c.d.'s were explained in the light of their phase structure, surface morphology, and chemical composition, confirmed by XRD, FESEM, and EDX analysis. The effect of c.d. on thickness, hardness, composition, HER, and OER was analyzed, and results were discussed with possible mechanisms.

  9. Hot-pressed Ag+ Ion Conducting Glass-Polymer Electrolytes: Synthesis and Battery Application

    Scientific Electronic Library Online (English)

    Angesh, Chandra.

    2012-07-01

    Full Text Available Synthesis of new Ag+ ion conducting glass-polymer electrolytes (GPEs): (1-x) PEO: x [0.75(0.75AgI:0.25AgCl):0.25(Ag2O:P2O5)], where 0 [...] )], with conductivity (?) ? 6.0 × 10-6 S cm-1, was identified from the compositional dependent conductivity studies and this has been referred to as the Optimum Conducting Composition (OCC). Approximately three orders of conductivity enhancement have been achieved in GPE OCC from that of the pure polymer PEO. The glass-polymer complexation has been confirmed by SEM and DSC analysis. Ion transport parameters viz. ionic conductivity (?), ionic mobility (?), mobile ion concentration (n) and ionic transference number (tion) have been characterized using different experimental techniques. Solid-state polymeric batteries were fabricated using GPE OCC as electrolyte and the cell-potential discharge characteristics were studied under different load conditions at room temperature.

  10. High-temperature electrolytic synthesis of tungsten carbide in chloride metaphosphate melts under the excess pressure of carbon oxide

    International Nuclear Information System (INIS)

    Consideration is given to possibility of multielectron processes of tungsten electrolytic reduction from dimeric forms in a narrow potential range and control of process potential, using acidic-basis properties o melt. Conditions of convergence of reduction potentials of carbon dioxide and tungsten dimeric forms were determined. Principle possibility of direct electrolytic synthesis of tungsten carbide under the excess pressure of carbon dioxide was shown. 20 refs.; 5 figs

  11. 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.

  12. Synthesis of nanospherical Fe3BO6 anode material for lithium-ion battery by the rheological phase reaction method

    International Nuclear Information System (INIS)

    This paper developed a novel method, the rheological phase reaction method, to synthesize nanospherical Fe3BO6. The sizes and morphologies of products vary with the calcination temperatures. Spherical particles with a uniform size about 40 nm in a monodisperse state were obtained at 800 deg. C, while the spherical particles with a larger size of 100-500 nm were obtained at 900 deg. C. The electrochemical properties of these Fe3BO6 nanospheres were investigated. Sample synthesized at 800 deg. C delivers a high reversible capacity above 500 mAh g-1. Sample synthesized at 900 deg. C possesses relatively good cycleability with a capacity retaining of 376 mAh g-1 after 10 cycles. The measurement of electrochemical impedance spectra for the first time indicated that smaller Fe3BO6 nanoparticles intend to give higher impedance of solid-electrolyte interface layer and lower charge-transfer impedance after the first discharge. Additionally, it can be speculated that the increase of resistance charge-transfer is the possible reason for the capacity fading during cycling. - Graphical abstract: Nanospherical Fe3BO6 anode material for lithium-ion battery has been synthesized by the rheological phase reaction method. The electrochemical properties of these Fe3BO6 nanospheres show that sample synthesized at 800 deg. C delivers a high reversible capacity above 500 mAh g-1, and sample synthesized at 900 deg. C possesses relatively good cycleability with a capacity retaining of 376 mAh g-1 after 10 cycles

  13. 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 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.

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

    Directory of Open Access Journals (Sweden)

    LINGLING XIE

    2010-01-01

    Full Text Available 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 analysis (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.

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

    OpenAIRE

    LINGLING XIE; XIAOYU CAO; CHANGWEI LIU; CHIWEI WANG

    2010-01-01

    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 analysis (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 micr...

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

    DEFF Research Database (Denmark)

    Hietala, Sami; Mononen, Pekka; Strandman, Satu; Järvi, Paula; Torkkeli, Mika; Jankova Atanasova, Katja; Hvilsted, Søren; Tenhu, Heikki

    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...

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

    DEFF Research Database (Denmark)

    Hietala, Sami; Mononen, Pekka; Strandman, Satu; Järvi, Paula; Torkkeli, Mika; Jankova Atanasova, Katja; Hvilsted, Søren; Tenhu, Heikki

    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 b...

  18. 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)

  19. Synthesis, characterization and rheological property of biphenyl-based polyarylene ether nitrile copolymers

    Directory of Open Access Journals (Sweden)

    2007-08-01

    Full Text Available The high molecular weight biphenyl-based polyarylene ether nitrile copolymers were synthesized by nucleophilic substitution reaction of 2,6-dichlorobenzonitrile (DCBN with varying molar ratios of 4,4’-dihydroxybiphenyl (BP and hydroquinone (HQ. The BP content of the copolymers has influence on glass transition temperature (Tg, initial decomposition temperature (Tid, mechanical properties and the crystallinity. All the copolymers could be dissolved in NMP, DMF and DMAc on heating, and were stable up to 450°C with a high char yield above 50% at 800°C in nitrogen atmosphere. The glass transition temperature, the melting temperature and tensile strength of copolymers were found to increase with increase in concentration of the BP units in the polymer. The dynamical viscosity and the storage modulus have been influenced by the BP concentration, frequency, temperature and time. This rheological results show that these copolymers have best thermoplastic processability and stability at 300–400°C.

  20. Segmented polyurethane elastomers with liquid crystalline hard segments. 1. Synthesis, characterization and rheology

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.; MacKnight, W.J.; Welder, W. [Univ. of Massachusetts, Amherst, MA (United States)] [and others

    1995-12-01

    Segmented liquid crystalline polyurethanes (LCPUE) have been studied with hard segments composed of the mesogen 4,4`-bis(6-hydroxyhexoxy)biphenyl, 2,4-tolylene diisocyanate, and 2,6-tolylene diisocyanate and soft segments composed of poly(tetramethylene oxides). Differential scanning calorimetry and wide-angle X-ray scattering experiments show the existence of an enantiotropic mesophase in the hard domains of the elastomer. Compared with nonsegmented polyurethane containing the same mesogen, the isotropization temperature of the mesophase in the elastomer is depressed. This is a result of the oligomeric structure of the hard domains. The endotherm corresponding to the isotropization transition is also broadened, reflecting a lack of uniformity of the hard domains. Furthermore, the mesophase can be oriented by elastic deformation, and it forms a more ordered chain packing during this process. The tensile properties of these segmented polyurethanes are determined by their morphologies and can be manipulated by controlling the hard- and soft-segment concentration ratio. The rheological study indicates a broad transition from a viscoelastic solid to a viscoelastic liquid at the isotropization temperature of the mesophase. Physical gelation studies identify a liquid/solid transition when cooled to 106{degrees}C or below, and show the characteristic, critical behavior at the gel point with a power law relaxation spectrum at low frequencies.

  1. Synthesis, morphology and rheology of core-shell silicone acrylic emulsion stabilized with polymerisable surfactant

    Directory of Open Access Journals (Sweden)

    2010-11-01

    Full Text Available Core-shell silicone acrylic emulsions with 3-methacryloxypropyl trimethoxysilane (MPTS in the shell were prepared by seeded polymerization with the assistance of polymerisable maleate surfactant (MT. Fourier transform infrared (FT-IR demonstrated the incorporation of polymerisable surfactant in copolymer. It was found that small amount of octadecyl acrylate was beneficial to emulsion stability with decreasing the particle size from 194.6 to 165.7 nm. It was also found that the particle size increased from 165.7 to 242.9 nm with the increase of MPTS concentration. Furthermore, rheological measurement indicated that the emulsion was endowed with pseudoplasticity. At low shear rate, marginal reduction in viscosity was detected when MPTS concentration increased to 2%, while great increase in viscosity was observed with higher MPTS concentration, the interaction force among emulsion particles became the predominant factor instead of particle size. In addition, better water resistance was observed when MT concentration was lower than 1.5%, and MPTS concentration higher than 2%. Moreover, surface roughness was increased with MPTS addition, the crosslinking among core and shell reconstructed the surface morphology of film.

  2. 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)

  3. Synthesis and examination of electrolytic sodium-vanadium oxide compounds intended for cathodes of lithium batteries: the mechanism of formation of electrolytic bronze ?-NaxV2O5

    International Nuclear Information System (INIS)

    For ascertaining the mechanism of electrolytic sodium-vanadium oxide bronze e-NaxV2O5 formation, which had been previously synthesized from acid vanadyl sulfate electrolyte, synthesis of ?-bronze i-NaxV2O5 was performed by electrolytic (e) oxide e-V2O5 exposure in the same sodium-containing electrolyte without current and with subsequent annealing of the exposed sample. The investigation, conducted by the methods of IR spectroscopy thermal and X-ray phase analyses, permitted ascertaining the identity of two modification of ?-bronze (e-NaxV2O5, i-NaxV2O5) and the proof of ion-exchange mechanism realization of electrolytic precursors of ?-bronze NaxV2O5 was found

  4. Synthesis of carbon-supported titanium oxynitride nanoparticles as cathode catalyst for polymer electrolyte fuel cells

    International Nuclear Information System (INIS)

    Highlights: • A sol–gel route for the synthesis of rutile TiO2 was modified to synthesize TiOxNy-C. • N atoms were doped into TiOx nanoparticles solely by the heat-treatment under N2 gas. • The N2-treatment produced sites more active toward ORR compared with NH3-treatment. • TiOx doped with a small amount of N atoms are suggested to be responsible for ORR. -- Abstract: For use as the oxygen reduction reaction (ORR) catalyst in polymer electrolyte fuel cell cathodes, carbon-supported titanium oxynitride (TiOxNy-C) nanoparticles with a size of approximately 5 nm or less were synthesized without using NH3 gas. A sol–gel route developed for the synthesis of pure rutile TiO2 nanopowders was modified to prepare the carbon-supported titanium oxide nanoparticles (TiOx-C). For the first time, N atoms were doped into TiOx solely by heating TiOx-C under an inexpensive N2 atmosphere at 873 K for 3 h, which could be due to carbothermal reduction. The TiOx-C powder was also heated under NH3 gas at various temperatures (873–1273 K) and durations (3–30 h). This step resulted in the formation of a TiN phase irrespective of the heating conditions. Both N2- and NH3-treated TiOxNy-C did not crystallize well; however, the former showed a mass activity more than three times larger than that of the latter at 0.74 V versus the standard hydrogen electrode. Thus, titanium oxide nanoparticles doped with a small amount of N atoms are suggested to be responsible for catalyzing ORR in the case of N2-treated TiOxNy-C

  5. 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 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.

  6. Molecular rheology of branched polymers: Decoding and exploring the role of architectural dispersity through a synergy of anionic synthesis, interaction chromatography, rheometry and modeling

    KAUST Repository

    Van Ruymbeke, Evelyne

    2014-01-01

    An emerging challenge in polymer physics is the quantitative understanding of the influence of a macromolecular architecture (i.e., branching) on the rheological response of entangled complex polymers. Recent investigations of the rheology of well-defined architecturally complex polymers have determined the composition in the molecular structure and identified the role of side-products in the measured samples. The combination of different characterization techniques, experimental and/or theoretical, represents the current state-of-the-art. Here we review this interdisciplinary approach to molecular rheology of complex polymers, and show the importance of confronting these different tools for ensuring an accurate characterization of a given polymeric sample. We use statistical tools in order to relate the information available from the synthesis protocols of a sample and its experimental molar mass distribution (typically obtained from size exclusion chromatography), and hence obtain precise information about its structural composition, i.e. enhance the existing sensitivity limit. We critically discuss the use of linear rheology as a reliable quantitative characterization tool, along with the recently developed temperature gradient interaction chromatography. The latter, which has emerged as an indispensable characterization tool for branched architectures, offers unprecedented sensitivity in detecting the presence of different molecular structures in a sample. Combining these techniques is imperative in order to quantify the molecular composition of a polymer and its consequences on the macroscopic properties. We validate this approach by means of a new model asymmetric comb polymer which was synthesized anionically. It was thoroughly characterized and its rheology was carefully analyzed. The main result is that the rheological signal reveals fine molecular details, which must be taken into account to fully elucidate the viscoelastic response of entangled branched polymers. It is important to appreciate that, even optimal model systems, i.e., those synthesized with high-vacuum anionic methods, need thorough characterization via a combination of techniques. Besides helping to improve synthetic techniques, this methodology will be significant in fine-tuning mesoscopic tube-based models and addressing outstanding issues such as the quantitative description of the constraint release mechanism. © 2014 the Partner Organisations.

  7. 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.

  8. Computational rheology

    CERN Document Server

    Owens, RG

    2002-01-01

    Modern day high-performance computers are making available to 21st-century scientists solutions to rheological flow problems of ever-increasing complexity. Computational rheology is a fast-moving subject - problems which only 10 years ago were intractable, such as 3D transient flows of polymeric liquids, non-isothermal non-Newtonian flows or flows of highly elastic liquids through complex geometries, are now being tackled owing to the availability of parallel computers, adaptive methods and advances in constitutive modelling.Computational Rheology traces the development of numerical methods fo

  9. Alcohol-assisted room temperature synthesis of different nanostructured manganese oxides and their pseudocapacitance properties in neutral electrolyte

    Science.gov (United States)

    Subramanian, V.; Zhu, Hongwei; Wei, Bingqing

    2008-03-01

    Different nanostructured manganese oxides have been synthesized by a simple precipitation technique using KMnO4 and different alcohols. The synthesized manganese oxides were extensively studied using TEM, XRD, XPS, surface area measurements and electrochemical studies. TEM observations showed a range of nanostructures from nanowiskers to nanoparticles. This synthesis method promises the tuning of electronic and structural properties of the nanostructured manganese oxides by simply varying the alcohols used in the reactions. MnO2 shows more whisker-like morphology while the Mn2O3 shows particle morphology. The nanostructured manganese oxides showed excellent performance as a pseudocapacitor electrode in a neutral electrolyte.

  10. Synthesis and investigation of electrolytic sodium-vanadium oxide compounds for cathodes of lithium batteries: the production of compounds with stable initial characteristics

    International Nuclear Information System (INIS)

    Heterogeneous vanadium oxide compounds were prepared during electrolysis of vanadyl sulfate solution in the presence of sodium ions. The limits of process parameters for synthesis of electrolysis products with stable initial electrochemical characteristics were ascertained. It is shown that the presence of sodium ions gives rise to the deposit adhesion o substrate. Electrochemical properties of the electrolytic deposits depend on the content of sodium ions in deposition electrolyte and subsequent thermal treatment of the deposit. Specific discharge capacity of electrolytic Na-vanadium oxide compounds may reach 320 Ah/kg in case of discharge up to 2.0 V at a density of 100 ?A/cm2

  11. Synthesis and conductivity of PEGME branched poly(ethylene-alt-maleimide) based solid polymer electrolyte

    International Nuclear Information System (INIS)

    A thermally stable comb-like polymer electrolyte, poly(ethylene glycol) monomethyl ether (PEGME) grafted poly(ethylene-alt-maleimide), has been synthesized and characterized. The copolymer was thermally stable up to 250.deg.C and had good film forming property. The copolymer was well mixed with poly(ethylene glycol) dimethyl ether(PEGDME, Mw = 400). The activation energy of ionic conduction decreased and conductivity increased with the increase of PEGDME content in the polymer electrolyte. The maximum conductivity of the resulting polymer electrolyte containing 66 wt% of PEGDME was found to be 3 x 10-4 S/cm at 30.deg.C. The polymer electrolyte showed electrochemical stability window of greater than 4.7 V

  12. The Dilemma of Supporting Electrolytes for Electroorganic Synthesis: A Case Study on Kolbe Electrolysis.

    Science.gov (United States)

    Stang, Carolin; Harnisch, Falk

    2016-01-01

    Remarkably, coulombic efficiency (CE, about 50?% at 1?Farad equivalent), and product composition resulting from aqueous Kolbe electrolysis are independent of reactor temperature and initial pH value. Although numerous studies on Kolbe electrolysis are available, the interrelations of different reaction parameters (e.g., acid concentration, pH, and especially electrolytic conductivity) are not addressed. A systematic analysis based on cyclic voltammetry reveals that solely the electrolytic conductivity impacts the current-voltage behavior. When using supporting electrolytes, not only their concentration, but also the type is decisive. We show that higher concentrations of KNO3 result in reduced CE and thus in significant increase in electric energy demand per converted molecule, whereas Na2 SO4 allows improved space-time yields. Pros and cons of adding supporting electrolytes are discussed in a final cost assessment. PMID:26609800

  13. Synthesis and electrochemical characterization of PEO-based polymer electrolytes with room temperature ionic liquids

    International Nuclear Information System (INIS)

    New gel polymer electrolytes containing 1-butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) ionic liquid are prepared by solution casting method. Thermal and electrochemical properties have been determined for these gel polymer electrolytes. The addition of BMPyTFSI to the P(EO)20LiTFSI electrolyte results in an increase of the ionic conductivity, and at high BMPyTFSI concentration (BMPy+/Li+ = 1.0), the ionic conductivity reaches the value of 6.9 x 10-4 S/cm at 40 oC. The lithium ion transference numbers obtained from polarization measurements at 40 oC were found to decrease as the amount of BMPyTFSI increased. However, the lithium ionic conductivity increased with the content of BMPyTFSI. The electrochemical stability and interfacial stability for these gel polymer electrolytes were significantly improved due to the incorporation of BMPyTFSI

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

    OpenAIRE

    Rodrigues, Luísa; 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...

  15. 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 key factor for use in electrochemical applications

  16. 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 that were characterized by measurements of conductivity, cyclic voltammetry, differential scanning calorimetry and thermogravimetry.

  17. 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

  18. Facile synthesis of polypyrrole nanofiber and its enhanced electrochemical performances in different electrolytes

    Directory of Open Access Journals (Sweden)

    C. K. Das

    2012-12-01

    Full Text Available A porous nanocomposite based on polypyrrole (PPy and sodium alginate (SA has been synthesized by easy, inexpensive, eco-friendly method. As prepared nanocomposite showed fibrillar morphology in transmission electron microscopic (TEM analysis. The average diameter of ~100 nm for the nanofibers was observed from scanning electron microscopic (SEM analysis. As prepared nanofiber, was investigated as an electrode material for supercapacitor application in different aqueous electrolyte solutions. PPy nanofiber showed enhanced electrochemical performances in 1M KCl solution as compared to 1M Na2SO4 solution. Maximum specific capacitance of 284 F/g was found for this composite in 1 M KCl electrolyte. It showed 76% specific capacitance retention after 600 cycles in 1 M KCl solution. Electrochemical Impedance Spectra showed moderate capacitive behavior of the composite in both the electrolytes. Further PPy nanofiber demonstrated higher thermal stability as compared to pure PPy.

  19. Facile synthesis of polypyrrole nanofiber and its enhanced electrochemical performances in different electrolytes

    OpenAIRE

    Das, C. K.; Sahoo, S; S. Dhibar

    2012-01-01

    A porous nanocomposite based on polypyrrole (PPy) and sodium alginate (SA) has been synthesized by easy, inexpensive, eco-friendly method. As prepared nanocomposite showed fibrillar morphology in transmission electron microscopic (TEM) analysis. The average diameter of ~100 nm for the nanofibers was observed from scanning electron microscopic (SEM) analysis. As prepared nanofiber, was investigated as an electrode material for supercapacitor application in different aqueous electrolyte solutio...

  20. Synthesis and investigation of electrolytic sodium-vanadium oxide compounds for lithium battery cathodes: electrolytic bronze ?-Na0.33V2O5

    International Nuclear Information System (INIS)

    By the method of electrolysis from vanadyl sulfate electrolytes in the presence of 10-20 g/l of sium ions deposits were prepared, which after high-temperature effect transformed into bronze with monoclinic structure of ?-Na0.33V2O5 composition. The bronze composition and properties were studied by the method of X-ray diffraction and thermal analyses, absorption IR spectroscopy, as well as by electrochemical methods. It is shown that the synthesized electrolytic bronze ?-Na0.33V2O5 features a high specific discharge capacity and efficiency of cycling in propylenecarbonate + dimethoxyethane + 1 M LiClO4 electrolyte

  1. Piperidinium tethered nanoparticle-hybrid electrolyte for lithium metal batteries

    KAUST Repository

    Korf, Kevin S.

    2014-06-23

    We report on the synthesis of novel piperidinium-based ionic liquid tethered nanoparticle hybrid electrolytes and investigate their physical and electrochemical properties. Hybrid electrolytes based on the ionic liquid 1-methyl-1-propylpiperidinium bis(trifluoromethanesulfone) imide covalently tethered to silica nanoparticles (SiO2-PP-TFSI) were blended with propylene carbonate-1 M lithium bis(trifluoromethanesulfone) imide (LiTFSI). We employed NMR analysis to confirm the successful creation of the hybrid material. Dielectric and rheological measurements show that these electrolytes exhibit exceptional room-temperature DC ionic conductivity (10-2 to 10 -3 S cm-1) as well as high shear mechanical moduli (105 to 106 Pa). Lithium transference numbers were found to increase with particle loading and to reach values as high as 0.22 at high particle loadings where the particle jam to form a soft glassy elastic medium. Analysis of lithium electrodeposits obtained in the hybrid electrolytes using SEM and EDX spectra show that the SiO2-PP-TFSI nanoparticles are able to smooth lithium deposition and inhibit lithium dendrite proliferation in Li metal batteries. LTOSiO2-PP-TFSI/PC in 1 M LiTFSILi half-cells based on the SiO2-PP-TFSI hybrid electrolytes exhibit attractive voltage profiles and trouble-free extended cycling behavior over more than 1000 cycles of charge and discharge. This journal is © the Partner Organisations 2014.

  2. 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 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.

  3. 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 nm...

  4. Electrochemical synthesis of methanol from CO{sub 2} in high-pressure electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.; Prentice, G. [Univ. of Detroit Mercy, MI (United States). Dept. of Chemical Engineering

    1997-12-01

    The authors synthesized CH{sub 3}OH from CO{sub 2} and H{sub 2}O on a copper cathode in the high-pressure CO{sub 2}-C{sub 2}H{sub 5}OH-H{sub 2}O-LiCl system. Methanol was the only product of CO{sub 2} reduction detected in the electrolytic solution, with a maximum current efficiency for methanol production of 40% at a current density of 9 mA/cm{sup 2} and potential of {minus}1.1 V vs. Ag/AgCl. This is the highest efficiency yet reported for methanol production at this current density. Current-potential curves shifted in the positive potential direction with increasing temperature and with increasing CO{sub 2} pressure up to approximately 60 atm. When the applied potential is more negative than about {minus}1.2 V vs. Ag/AgCl, the current density decreases dramatically with time. Electrolyte conductivity in this system increases with increasing temperature, increasing concentration of LiCl, and decreasing CO{sub 2} pressure.

  5. Synthesis of polymeric pour point depressants for Nada crude oil (Gujarat, India) and its impact on oil rheology

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, Srushti; Bharambe, D.P. [Department of Applied Chemistry, Faculty of Technology and Engineering, The Maharaja Sayajirao University of Baroda, Kalabhavan, VADODARA-390 001, Gujarat (India)

    2008-03-15

    Five flow improvers have been synthesized to study rheological properties of Nada crude oil (Gujarat, India). Anhydride copolymers were prepared making use of the copolymerization of acrylates of different alkyls with maleic anhydride and the Poly (n-alkyl acrylates-co-N-hexadecylmaleimide) were prepared by the reaction of copolymer with hexadecylamine. The additives were purified and characterized by FTIR, GPC. The prepared polymeric additives shows dual function both as wax dispersants and flow improvers and all of them acts as good pour point depressants. Yield stress and the viscosity of the crude oil at different temperatures and concentrations of additives were evaluated by zero friction advanced rheometer AR-500 of TA instrument. Comparison of morphologies and structures of wax crystals or aggregates in waxy crude oils beneficiated with and without a PPD was also done by micro photographic studies which show the modification in wax crystal morphology due to additives. (author)

  6. Synthesis and Properties of Acyclic Ammonium-based Ionic Liquids with Allyl Substituents as Electrolytes

    Directory of Open Access Journals (Sweden)

    Young Gyu Kim

    2009-05-01

    Full Text Available Several new acyclic ammonium-TFSI ionic liquids with an allyl substituent(s were synthesized and their physicochemical and electrochemical properties were characterized. [AAMM]Am-TFSI (3 with two allyl groups showed the widest electrochemical stability window (5.9 V among the ammonium-based ILs reported to date because of the increment of both the anodic and cathodic limits. The charge-discharge performance of a LiCoO2-based half-cell containing [AAMM]Am-TFSI as an electrolyte was better in cycleability (the capacity retention ratio: 99% after 20 cycles than that of the cell with the corresponding partially saturated analogue, [AMMP]Am-TFSI (2 (the capacity retention ratio: 92% after 20 cycles.

  7. Combustion synthesis-derived tantalum powder for solid-electrolyte capacitors

    International Nuclear Information System (INIS)

    In this paper, the synthesis of capacitor-grade tantalum (Ta) powder via the self-propagating high-temperature synthesis (SHS) method is described. In addition, the sintering aspects and electrical characteristics of the powder are discussed. Ta powder was prepared via the combustion of a Ta2O5-xMg-kNaCl mixture, under argon pressure. The morphology and size of the final powder particles was controlled by adjusting the Mg-NaCl concentration. The final powder particles had nodular shapes and sizes ranging from 0.1 to 0.5 ?m. A leakage current of a sintered Ta sample containing the smallest particle size was 10 ?A; its capacitance was 92,738 CV, when a 40-V voltage was applied to the sample.

  8. Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium

    International Nuclear Information System (INIS)

    The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density

  9. Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium

    Energy Technology Data Exchange (ETDEWEB)

    Bazzaoui, M. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: bazzaoui@fe.up.pt; Martins, J.I. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Reis, T.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Bazzaoui, E.A. [Faculte des Sciences, Departement de Chimie, Universite Mohammed I er, 60 000 Oujda (Morocco); Nunes, M.C. [Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Martins, L. [Centre de Recherche Public de la Sante, 18 rue Dicks (Luxembourg)

    2005-08-01

    The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density.

  10. 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.

  11. Synthesis of LiNi0.65Co0.25Mn0.1O2 as cathode material for lithium-ion batteries by rheological phase method

    International Nuclear Information System (INIS)

    Research highlights: ? In this paper, for the first time, rheological phase method, a simple and effective route, was applied to synthesis high capacity cathode material LiNi0.65Co0.25Mn0.1O2. ? All of the results obtained by X-ray diffraction spectrometer, X-ray photoelectron spectrometer, charge-discharge tests and electrochemical impedance spectroscopy show that the rheological phase production have better properties than that of the report. - Abstract: Rheological phase (RP) method has been successfully applied to synthesize a promising cathode material LiNi0.65Co0.25Mn0.1O2. X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma and transmission electron microscope are used to investigate the structure, composition and morphology, respectively. XRD result shows that the as-prepared powder has a layered ?-NaFeO2 structure. XPS pattern reveals that the Ni ions have valences of 2+ and 3+, and the Co and Mn are 3+, 4+, respectively. The electrode consisting of the obtained powder presents the better electrochemical properties, which is attributed to the fewer amounts of Ni2+ ions and the smaller particles. All the results suggest that the rheological phase method is a promising technique for the preparation of LiNi0.65Co0.25Mn0.1O2 cathode material of lithium-ion batteries.

  12. 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

  13. 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

  14. Synthesis, processing and characterization of calcia-stabilized zirconia solid electrolytes for oxygen sensing applications

    International Nuclear Information System (INIS)

    Precursor powders of calcia-stabilized zirconia (CSZ) solid electrolytes have been synthesized by a sol-gel method. The phase evolution of the precursor powders after thermal treatments at different temperatures were analysized by X-ray diffraction technique. Disc-shaped sensor elements were fabricated via uniaxial pressing of the calcined powders and subsequently sintered at 1650 deg. C. Scanning electron microscopy (SEM) was used to analyze the microstructure of the sintered pellets. Platinum electrodes were applied to the sintered elements to produce potentiometric/electrochemical gas sensors. The electrical response of the gas sensors to oxygen and the complex impedance of the sensors in air were measured at various temperatures. Impedance analyses indicate that the sensor cell with 15 mol% CaO has much lower resistance (the sum of bulk and grain-boundary resistance) than the sensor cell with 22 mol% CaO. This is also reflected by the EMF responses of both sensor cells to various oxygen concentrations in the testing gas. The EMF deviation from the theoretical value of the CSZ sensor cell with 22 mol% CaO was larger than that of the CSZ sensor cell with 15 mol% CaO. The corrrelations between material compositions, microstructures of the sintered pellets and the electrical properties of the sensors are discussed

  15. Synthesis and proton conductivity studies of doped azole functional polymer electrolyte membranes

    International Nuclear Information System (INIS)

    The development of anhydrous proton-conducting membranes is important for the operation of polymer electrolyte membrane fuel cell (PEMFC) at intermediate temperature (100-200 oC). In this work, poly(vinylbenzylchloride), PVBC was produced by free radical polymerization of 4-vinylbenzylchloride and then it was modified with 5-aminotetrazole (ATET) to obtain poly(vinylbenzylaminotetrazole), PVBC-ATET. The composition of the polymer was verified by elemental analysis (EA) and the structure was characterized by FT-IR and 13C NMR spectra. According to the elemental analysis result, PVBC was modified by ATET with 80% yield. The polymer was doped with trifluoromethanesulfonic acid (TA) at various molar ratios, x = 1.25, 2.5, 3.75 with respect to tetrazole unit. The proton transfer from TA to the tetrazole rings was proved with FT-IR spectroscopy. Thermogravimetry (TG) analysis showed that the samples are thermally stable up to approximately 200 oC. Differential scanning calorimetry (DSC) results illustrated the homogeneity of the materials. Cyclic voltammetry (CV) study illustrated that the electrochemical stability domain for PVBC-ATET-TA2.5 extends over 3.0 V. The proton conductivity of these materials increased with dopant concentration and the temperature. Maximum proton conductivity of PVBC-ATET-TA2.5 was found to be 0.01 S/cm at 150 oC in the anhydrous state.

  16. 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.

  17. Synthesis and Characterization of a Gel-Type Electrolyte with Ionic Liquid Added for Dye-Sensitized Solar Cells

    OpenAIRE

    Shi, Le-Yan; Chen, Tien-Li; Chen, Chih-hao; Cho, Kun-Ching

    2013-01-01

    This study intends to develop the electrolyte needed in dye-sensitized solar cells (DSSCs). Moreover, three different ionic liquids in different molalities are added to the gel-type electrolyte. Experimental results show that the DSSC composed of the gel-type electrolyte with no ionic liquid added can acquire 4.13% photoelectric conversion efficiency. However, the DSSC composed of the gel-type electrolyte with 0.4 M of 1-butyl-3-methylimidazolium chloride added has an open-circuit voltage of ...

  18. Synthesis and characterization of perfluorinated sulfonimide copolymers as polymer electrolyte membranes

    Science.gov (United States)

    Zhou, Shuang

    Ionomers for polymer electrolyte membranes in fuel cell applications were developed utilizing the acidic bis(perfluoromethyl sulfonyl) imide functional group. Perfluorinated vinyl ether sulfonimide monomers CF2=CFOCF 2CF(CF3)O(CF2)2SO2N(Na)SO 2CF3 (1), CF2=CFOCF2CF(CF 3)O(CF2)2SO2N(Na)SO2(CF 2)4SO2N(Na)CF3 (2), CF 2=CFOCF2CF(CF3)O(CF2)2SO 2N(Na)SO2(CF2)6SO2N(Na)CF 3 (3) and CF2=CFOCF2CF(CF3)O(CF2) 2SO2N(Na)SO2(CF2)2O(CF 2)2SO2N(Na)CF3 (4) were synthesized through multiple steps. The complete coupling reaction between the water sensitive CF3SO 2N(Na)Si(CH3)3 and the bromine-protected Dupont monomer BrCF2CFBrOCF2CF(CF3)O(CF2) 2SO2F is an important step to incorporate the sulfonimide group into the monomer 1. Bis(fluorosulfonyl) perfluoroalkanes FSO2RfSO2F (Rf = -(CF 2)4-, -(CF2)6- and -(CF 2)2O(CF2)2-) were used to introduce multifunctional sulfonimides into monomers 2, 3 and 4. Disulfonyl fluoride compounds were reacted with CF 3SO2N(Na)SiMe3 affording the unsymmetrical sulfonyl fluoride intermediates CF3SO2N(Na)SO2R fSO2F. After the transformation of -SO2F into -SO2N(Na)Si(CH3), the coupling reaction of the silyl compounds with BrCF2CFBrOCF2CF(CF3)O(CF 2)2SO2F followed by debromination gave the final products 2, 3 and 4. Copolymers of the sulfonimide monomers with tetrafluoroethylene (TFE) were produced by semi-batch free-radical emulsion copolymerizations. The perflurinated vinyl ether sulfonimide, TFE, the redox initiator pair (NH4) 2S2O8/NaHSO3, the emulsifier C 7F15COONH4 and the buffer NaH2PO 4/Na2HPO4 were mixed in a stirred Parr autoclave at 10°C. During the copolymerization, TFE pressure and the sulfonimide monomer concentration were kept nearly constant in the reaction system to generate copolymers with acidic groups randomly distributed in the polymer chains. Copolymerization conditions were optimized through variations of some important reaction parameters such as the initiator concentration, TFE pressure, the sulfonimide monomer concentration and the surfactant concentration. Self-emulsifying copolymerizations of 2, 3 and 4 with TFE were also investigated. Among them, only monomer 4 can be copolymerized with TFE in the absence of the emulsifier C7F 15COONH4. Perfluorinated sulfonimide copolymers were characterized using the functional analysis, NMR and thermal analyses. The membranes and solutions produced from these sulfonimide copolymers exhibited excellent performance when incorporated into membrane electrode assemblies for fuel cell testing.

  19. Synthesis and characterization of polymer electrolyte membranes with controlled ion transport properties

    Science.gov (United States)

    Xu, Kui

    2011-12-01

    Ion-containing block copolymers hold promise as next-generation polymer electrolyte membrane (PEM) materials due to their capability to self-assemble into ordered nanostructures facilitating proton transport over a wide range of conditions. Ion-containing block copolymers, sulfonated poly(styrene- b-vinylidene fluoride-b-styrene), with varied degrees of sulfonation were synthesized. The synthetic strategy involved a new approach to chain-end functionalized poly(vinylidene fluoride) as a macro-initiator followed by atom transfer polymerization of styrene and sulfonation. Characterization of the polymers were extensively carried out by 1H and 19F nuclear magnetic resonance and Fouriertransform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analysis. Tapping mode atomic force microscopy and transmission electron microscopy were applied to study the phase separation and self-assembled morphology. Strong dependence of ion exchange capacity, water absorption, morphology and proton conductivity on the degree of sulfonation has been found. It has been observed that the conductivities of the block copolymers are considerably higher than the random copolymers of polystyrene and sulfonated polystyrene possessing similar ion exchange capacities. Copolymers of vinylidene fluoride and perfluoro(4-methyl-3,6-dioxane-7-ene) sulfonyl fluoride containing amino end-groups were synthesized for the first time. The prepared aminoterminated polymers underwent cross-linking reactions with 1,3,5-benzene triisocyanate to form proton conductive networks. The chain-end crosslinked fluoropolymer membranes exhibited excellent thermal, hydrolytic and oxidative stabilities. The ion exchange capacity, water uptake, the state of absorbed water, and transport properties of the membranes were found to be highly dependent upon the chemical composition of the copolymers. The cross-linked membranes showed extremely low methanol permeability, while maintaining high proton conductivity at the same order of magnitude as Nafion. This unique transport feature gave rise to exceedingly higher electrochemical selectivity in relation to Nafion. The selectivity characteristics have been rationalized based on the formation of restrained ionic domains and the state of the absorbed water within the membranes. A series of new Nafion-based composite membranes were prepared via an in situ sol-gel reaction of 3-(trihydroxylsilyl) propane-1-sulfonic acid and solution casting method. The morphological structure, ion-exchange capacity, water uptake, proton conductivity, and methanol permeability of the resulting composite membranes were extensively investigated as functions of the content of sulfopropylated polysilsesquioxane filler, temperature, and relative humidity. Unlike the conventional Nafion/silica composites, the prepared membranes exhibit an increased water uptake and associated enhancement in proton conductivity compared to unmodified Nafion. In particular, considerably high proton conductivities at 80 and 120 °C under 30% relative humidity were demonstrated in the composite membranes, which are over 2 times greater than that of Nafion. In addition to a remarkable improvement in proton conductivity, the composite membranes displayed lower methanol permeability and superior electrochemical selectivity in comparison to the pure Nafion membrane. A versatile and facile synthetic approach was developed for the preparation of a family of new ionomers with rigid aromatic backbones and pendant perfluorinated sulfonic acid groups. Variation in the chemical composition and structure of the new aromatic ionomers were performed to optimize PEM properties and fuel cell performance. The ionomers prepared from condensation polymerization of Sodium 1,1,2,2-tetrafluoro-2-(2',3',5',6'-tetrafluoro-phenoxy)- ethane sulfonate and bisphenol monomers, e.g. hydroquinone, 4,4'-biphenol, or their mixture with appropriate ratio, exhibited comparable or greater proton conductivity in relation to Nafion. New aromatic ionomers also showed other outstanding PEM prop

  20. 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)

  1. Nickel electrocrystallization in different electrolytes: An in-process and post synthesis analysis

    International Nuclear Information System (INIS)

    The present report is solicited for contributions of nucleation–growth mechanisms of electrodeposition of nickel in different aqueous solutions. The cyclic voltammetry (CV) analysis has been performed on electrocrystallized Ni to understand the deposition and dissolution processes in four types of baths i.e. sulphate, chloride, Watts and sulphamate baths. The result shows that for chloride and sulphate bath there are distinct peaks but for Watts and sulphamate there is no such cathodic peaks, rather it increased to the specified vertex potential. And also it is observed that for sulphate bath the dissolution peak is observed but the physical observation of the electrode after the completion of CV depicts that dissolution takes place partially. The in-process and post synthesis analysis was studied by electrochemical techniques followed by morphological studies (by scanning electron microscope (SEM) and atomic force microscope (AFM)). The other technique used in this study includes XRD to analyze the phase, crystallite size and lattice strain, surface profilometer and Nanoindenter to analyze the structure and properties of deposits (residual stress and hardness). The thickness of the film varies from 1.3 to 2.7 ?m for baths from sulphate, sulphamate, Watts to chloride baths. The compressive stress obtained for different baths vary from 4.015 to 11.231 GPa and tensile stress vary from 3.778 to 16.608 GPa from sulphamate, Watts, sulphate to chloride baths. Also the stress reduces and hardness increases from sulphamate, Watts, sulphate to chloride baths. The grain size decreases and lattice strain increases from sulphamate, Watts, sulphate to chloride baths

  2. 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)

  3. Polymer Electrolytes

    Science.gov (United States)

    Hallinan, Daniel T.; Balsara, Nitash P.

    2013-07-01

    This review article covers applications in which polymer electrolytes are used: lithium batteries, fuel cells, and water desalination. The ideas of electrochemical potential, salt activity, and ion transport are presented in the context of these applications. Potential is defined, and we show how a cell potential measurement can be used to ascertain salt activity. The transport parameters needed to fully specify a binary electrolyte (salt + solvent) are presented. We define five fundamentally different types of homogeneous electrolytes: type I (classical liquid electrolytes), type II (gel electrolytes), type III (dry polymer electrolytes), type IV (dry single-ion-conducting polymer electrolytes), and type V (solvated single-ion-conducting polymer electrolytes). Typical values of transport parameters are provided for all types of electrolytes. Comparison among the values provides insight into the transport mechanisms occurring in polymer electrolytes. It is desirable to decouple the mechanical properties of polymer electrolyte membranes from the ionic conductivity. One way to accomplish this is through the development of microphase-separated polymers, wherein one of the microphases conducts ions while the other enhances the mechanical rigidity of the heterogeneous polymer electrolyte. We cover all three types of conducting polymer electrolyte phases (types III, IV, and V). We present a simple framework that relates the transport parameters of heterogeneous electrolytes to homogeneous analogs. We conclude by discussing electrochemical stability of electrolytes and the effects of water contamination because of their relevance to applications such as lithium ion batteries.

  4. Synthesis of polycarbonate polymer electrolytes for lithium ion batteries and study of additives to raise the ionic conductivity

    OpenAIRE

    Andersson, Jonas

    2015-01-01

    Polymer electrolyte films based on poly(trimethylene carbonate) (PTMC) mixed with LiTFSI salt in different compositions were synthesized and investigated as electrolytes for lithium ion batteries, where the ionic conductivity is the most interesting material property. Electrochemical impedance spectroscopy (EIS) and DSC were used to measure the ionic conductivity and thermal properties, respectively. Additionally, FTIR and Raman spectroscopy were used to examine ion coordination in the materi...

  5. High Ionic Conductivity of Composite Solid Polymer Electrolyte via In Situ Synthesis of Monodispersed SiO2 Nanospheres in Poly(ethylene oxide).

    Science.gov (United States)

    Lin, Dingchang; Liu, Wei; Liu, Yayuan; Lee, Hye Ryoung; Hsu, Po-Chun; Liu, Kai; Cui, Yi

    2016-01-13

    High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer-ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10(-3) S cm(-1) at 60 °C, 4.4 × 10(-5) S cm(-1) at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance. PMID:26595277

  6. 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.

  7. 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=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.

  8. 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.

  9. Synthesis and properties of aromatic polyethers containing poly(ethylene oxide) side chains as polymer electrolytes for lithium ion batteries

    International Nuclear Information System (INIS)

    Polymer electrolytes consisting of polar pyridine units in the backbone and poly(ethylene oxide) (PEO) side chains are designed for possible application in lithium ion batteries. In particular, aromatic polyethers bearing PEO side chains with varying length are synthesized either by copolymerization of the corresponding PEO based diols with different arylfluorides or by modification of dihydroxyl functionalized precursor polymers with poly(ethylene oxide) methyl ether tosylate. The formation of free standing films is dependent on the PEO content, polymers' composition as well as on the different monomers used. The mechanical properties study shows that the glass transition temperature can be controlled by varying the PEO content. Thermal stability is also influenced by the PEO length: the shorter the PEO side chain, the higher the stability. XRD analysis gives information about the desired amorphous character of these polymers, which is independent of the PEO content. Solid polymer electrolytes prepared by blending the PEO-based polymers with lithium salt and PEO 2000 (used as plasticizer) show ambient temperature conductivities in the range of 10−6 S/cm. To further improve conductivity doping of PEO-based polymers in liquid electrolyte (1 M LiPF6 in EC/DMC 1/1) in some cases results in high conductivities in the range of 10−3 S cm−1 at 80 °C. - Highlights: • Polymer electrolytes bearing PEO side chains of varying lengths were designed. • DMA and TGA show that Tg and Td can be controlled by varying the PEO content. • XRD confirms polymers amorphous character, independent of the PEO content. • Membranes doped in liquid electrolyte have high conductivities (10−3 S cm−1, 80 °C)

  10. Synthesis and properties of aromatic polyethers containing poly(ethylene oxide) side chains as polymer electrolytes for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Vöge, Andrea, E-mail: andreavoege@online.de [Department of Chemistry, University of Patras, 26500 Patras (Greece); Deimede, Valadoula, E-mail: deimede@upatras.gr [Department of Chemistry, University of Patras, 26500 Patras (Greece); Paloukis, Fotis; Neophytides, Stylianos G. [Foundation of Research and Technology – Hellas, Institute of Chemical Engineering Sciences (FORTH/ICE-HT), Patras 26504 (Greece); Kallitsis, Joannis K. [Department of Chemistry, University of Patras, 26500 Patras (Greece)

    2014-11-14

    Polymer electrolytes consisting of polar pyridine units in the backbone and poly(ethylene oxide) (PEO) side chains are designed for possible application in lithium ion batteries. In particular, aromatic polyethers bearing PEO side chains with varying length are synthesized either by copolymerization of the corresponding PEO based diols with different arylfluorides or by modification of dihydroxyl functionalized precursor polymers with poly(ethylene oxide) methyl ether tosylate. The formation of free standing films is dependent on the PEO content, polymers' composition as well as on the different monomers used. The mechanical properties study shows that the glass transition temperature can be controlled by varying the PEO content. Thermal stability is also influenced by the PEO length: the shorter the PEO side chain, the higher the stability. XRD analysis gives information about the desired amorphous character of these polymers, which is independent of the PEO content. Solid polymer electrolytes prepared by blending the PEO-based polymers with lithium salt and PEO 2000 (used as plasticizer) show ambient temperature conductivities in the range of 10{sup ?6} S/cm. To further improve conductivity doping of PEO-based polymers in liquid electrolyte (1 M LiPF{sub 6} in EC/DMC 1/1) in some cases results in high conductivities in the range of 10{sup ?3} S cm{sup ?1} at 80 °C. - Highlights: • Polymer electrolytes bearing PEO side chains of varying lengths were designed. • DMA and TGA show that T{sub g} and T{sub d} can be controlled by varying the PEO content. • XRD confirms polymers amorphous character, independent of the PEO content. • Membranes doped in liquid electrolyte have high conductivities (10{sup ?3} S cm{sup ?1}, 80 °C)

  11. Properties of Sulfolane Based Aprotic Electrolytes

    Scientific Electronic Library Online (English)

    Josef, Maca; Martin, Frk; Zdenka, Rozsivalova; Marie, Sedlarikova.

    2013-11-11

    Full Text Available The article deals with description of rheological and electrical properties of solvents for electrolytes of lithium-ion batteries. Solvents mixture of dimethyl sulfone and sulfolane at different volume ratios and with a lithium salt (LiClO4) appears as a potentially suitable electrolyte. In this wor [...] k, we investigate the influence of different solvents and their mixtures in order to find a solvent which increases the fire safety of such battery. The aim of this experiment is to investigate the rheological properties, particularly density and dynamic viscosity of solvents with lithium salt in temperature dependence and to find the optimal composition of the electrolyte from the perspective of achieving the lowest dynamic viscosity and better electrical conductivity, because both quantities are closely related with Walden's rule. The vibration method is used to determine the values of dynamic viscosity.

  12. Ce0.8Sm0.2O1.9 synthesis for solid oxide fuel cell electrolyte by ultrasound assisted co-precipitation method.

    Science.gov (United States)

    Okkay, Hikmet; Bayramoglu, Mahmut; Faruk Öksüzömer, M

    2013-05-01

    In this study, the synthesis of Ce(0.8)Sm(0.2)O(1.9) (SDC) solid electrolyte by the ultrasound assisted co-precipitation method was accomplished to explore the effects of ultrasound power, ultrasound pulse ratio and probe type upon the ionic conductivity of SDC as well as the lattice parameter, the microstructure and the density. Fine powders of uniform crystallite sizes (average 11.70±0.62nm) were obtained, needing lower sintering temperature. The SDC powders were successfully sintered to a relative density of over 95% at 1200°C (5°Cmin(-1)) for 6h. The micrograph of SDC pellets showed non-agglomerated and well-developed grains with average size of about 200nm. X-ray diffraction analysis showed that the lattice parameter increased with increasing acoustic intensity and reached a maximum for the 14.94Wcm(-2). Further, a linear relationship was detected between the lattice parameter and the ionic conductivity, inspiring a dopant like effect of US on the electrolyte properties. The highest ionic conductivity as ?(800°C)=3.07×10(-2)Scm(-1) with an activation energy E(a)=0.871kJmol(-1) was obtained with pulsed ultrasound for an acoustic intensity of 14.94Wcm(-2), using 19mm probe and 8:2 pulse ratio. PMID:23178079

  13. 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.

  14. 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...

  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 (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 studies of boron based anion receptors and their use in non-aqueous electrolytes for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.; Yang, X.Q.; Lee, H.S.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States); Choi, L.S. [Naval Research Lab., Washington, DC (United States)

    1998-12-31

    A new family of anion receptors based on boron compounds has been synthesized. These compounds can be used as anion receptors in lithium battery electrolytes and can greatly increase solubility and ionic conductivities of various lithium salts, such as LiF, LiCl, CF{sub 3}COOLi and C{sub 2}F{sub 5}COOLi, in DME solutions. Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy studies show that Cl{sup {minus}} anions of LiCl are complexed with these compounds in DME solutions. The electrochemical stability of lithium salts and one of the boron compounds in deferent solvents was studied. For the first time, LiF has been successfully used as conducting salt in a novel electrolyte with this boron compound as an additive in DME. A rechargeable Li/LiMn{sub 2}O{sub 4} cell using this electrolyte was successfully cycled 51 times. However, the capacity fades with cycling due to decomposition of the solvent. The cycling performance of the battery was greatly improved by replacing DME with PC-EC-DMC as the solvent.

  17. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  18. Rheological phenomena in focus

    CERN Document Server

    Boger, DV

    1993-01-01

    More than possibly any other scientific discipline, rheology is easily visualized and the relevant literature contains many excellent photographs of unusual and often bizarre phenomena. The present book brings together these photographs for the first time. They are supported by a full explanatory text. Rheological Phenomena in Focus will be an indispensable support manual to all those who teach rheology or have to convince colleagues of the practical relevance of the subject within an industrial setting. For those who teach fluid mechanics, the book clearly illustrates the difference be

  19. 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 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.

  20. Development of a model colloidal system for rheology simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, Peter Randall; Tallant, David Robert; Piech, Martin (United Technologies Research Center, East Hartford, CT); Bell, Nelson Simmons; Frischknecht, Amalie Lucile

    2008-10-01

    The objective of the experimental effort is to provide a model particle system that will enable modeling of the macroscopic rheology from the interfacial and environmental structure of the particles and solvent or melt as functions of applied shear and volume fraction of the solid particles. This chapter describes the choice of the model particle system, methods for synthesis and characterization, and results from characterization of colloidal dispersion, particle film formation, and the shear and oscillatory rheology in the system. Surface characterization of the grafted PDMS interface, dispersion characterization of the colloids, and rheological characterization of the dispersions as a function of volume fraction were conducted.

  1. Polyelectrolytes thermodynamics and rheology

    CERN Document Server

    P M, Visakh; Picó, Guillermo

    2014-01-01

    This book discusses current development of theoretical models and experimental findings on the thermodynamics of polyelectrolytes. Particular emphasis is placed on the rheological description of polyelectrolyte solutions and hydrogels.

  2. Synthesis and characterization of castor oil-based polyurethane for potential application as host in polymer electrolytes

    Indian Academy of Sciences (India)

    S Ibrahim; A Ahmad; N S Mohamed

    2015-09-01

    Polyurethane (PU) based on polyol, derived from castor oil has been synthesized and characterized for potential use as a base material for electrolytes. Transesterification process of castor oil formed a polyol with hydroxyl value of 190 mg KOH g–1 and molecular weight of 2786 g mol–1. The polyols together with 4,4′-diphenylmethane diisocyanate were used to synthesize the desired bio-based PU. The molecular structure of PU was investigated by Fourier transform infrared (FTIR) spectroscopy. The disappearance of NCO peak in the FTIR spectrum at 2270–2250 cm–1 showed that diisocyanate has completely reacted to form PU. Morphological characteristic of the PU film was analysed using scanning electron microscopy, whereas thermal characteristics of the materials were characterized using dynamic mechanical analysis and thermal gravimetric analysis. The cross-sectional micrograph showed that the prepared film was highly amorphous and homogeneous. Thermal studies revealed that the film had low glass transition temperature, –15.8°C, and was thermally stable up to 259°C. These observations indicated the synthesized PU possessed favourable properties to act as a base material in polymer electrolytes.

  3. Activated Sludge Rheology

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Horn, Willi; Helmus, Frank; Rosenberger, Sandra; Naessens, Wouter; Nopens, Ingmar; Bentzen, Thomas Ruby

    2013-01-01

    Rheological behaviour is an important fluid property that severely impacts its flow behaviour and many aspects related to this. In the case of activated sludge, the apparent viscosity has an influence on e.g. pumping, hydrodynamics, mass transfer rates, sludge-water separation (settling and filtration). It therefore is an important property related to process performance, including process economics. To account for this, rheological behaviour is being included in process design, necessitating it...

  4. Polymer electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Abbrent, Sabina; Greenbaum, S.; Peled, E.; Golodnitsky, D.

    Singapore : World Scientific Publishing, 2015 - (Dudney, N.; West, W.; Nanda, J.), s. 523-589 ISBN 978-981-4651-89-9 Institutional support: RVO:61389013 Keywords : polymer electrolytes * applications * mesuring techniques Subject RIV: CD - Macromolecular Chemistry

  5. Rheology of Active Gels

    Science.gov (United States)

    Chen, Daniel

    2015-03-01

    Active networks drive a diverse range of critical processes ranging from motility to division in living cells, yet a full picture of their rheological capabilities in non-cellular contexts is still emerging, e.g., How does the rheological response of a network capable of remodeling under internally-generated stresses differ from that of a passive biopolymer network? In order to address this and other basic questions, we have engineered an active gel composed of microtubules, bidirectional kinesin motors, and molecular depletant that self-organizes into a highly dynamic network of active bundles. The network continually remodels itself under ATP-tunable cycles of extension, buckling, fracturing, and self-healing. Using confocal rheometry we have simultaneously characterized the network's linear and non-linear rheological responses to shear deformation along with its dynamic morphology. We find several surprising and unique material properties for these active gels; most notably, rheological cloaking, the ability of the active gel to drive large-scale fluid mixing over several orders of flow magnitude while maintaining an invariant, solid-like rheological profile and spontaneous flow under confinement, the ability to exert micro-Newton forces to drive persistent directed motion of the rheometer tool. Taken together, these results and others to be discussed highlight the rich stress-structure-dynamics relationships in this class of biologically-derived active gels.

  6. Rheological Principles for Food Analysis

    Science.gov (United States)

    Daubert, Christopher R.; Foegeding, E. Allen

    Food scientists are routinely confronted with the need to measure physical properties related to sensory texture and processing needs. These properties are determined by rheological methods, where rheology is a science devoted to the deformation and flow of all materials. Rheological properties should be considered a subset of the textural properties of foods, because the sensory detection of texture encompasses factors beyond rheological properties. Specifically, rheological methods accurately measure "force," "deformation," and "flow," and food scientists and engineers must determine how best to apply this information. For example, the flow of salad dressing from a bottle, the snapping of a candy bar, or the pumping of cream through a homogenizer are each related to the rheological properties of these materials. In this chapter, we describe fundamental concepts pertinent to the understanding of the subject and discuss typical examples of rheological tests for common foods. A glossary is included as Sect. 30.6 to clarify and summarize rheological definitions throughout the chapter.

  7. 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.

  8. Synthesis and characterization of -Bi2O3 based solid electrolyte doped with Nb2O5

    Indian Academy of Sciences (India)

    Handan Ozlu; Soner Cakar; Caner Bilir; Ersay Ersoy; Orhan Turkoglu

    2014-06-01

    -phase bismuth oxide is a well known high oxygen ion conductor and can be used as an electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). This study aims to determine new phases of Bi2O3–Nb2O5 binary system and the temperature dependence of the electrical transport properties. The reaction products obtained in open air atmosphere were characterized by X-ray powder diffractions (XRD). The unit cell parameters were defined from the indexes of the powder diffraction patterns. The -Bi2O3 crystal system were obtained by doping 0.01 < mole% Nb2O5 < 0.04 at 750 °C for 48 and 96 h. Thermal behaviour and thermal stability of the phases were investigated by thermal analysis techniques. Surface and grain properties of the related phases were determined by SEM analysis. The temperature dependence of the electrical properties of -Bi2O3 solid solution was measured by four-point probe d.c. conductivity method. In the investigated system, the highest value of conductivity was observed for $\\sigma_{T}$ = 0.016 ohm-1 cm-1 at 650 °C on 4 mole% Nb2O5 addition. The electrical conductivity curves of studied materials revealed regular increase with temperature in the form of the Arrhenius type conductivity behaviour.

  9. Synthesis and characterization of sulfonated poly(ether sulfone)s containing mesonaphthobifluorene for polymer electrolyte membrane fuel cell.

    Science.gov (United States)

    Lim, Youngdon; Seo, Dongwan; Lee, Soonho; Hossain, Md Awlad; Lim, Jinseong; Lee, Sangyoung; Hong, Taehoon; Kim, Whangi

    2014-10-01

    The novel sulfonated poly(ether sulfone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and characterized their properties. The prepared polymers have highly conjugated aromatic structure due to the MNF group which is an allotrope of carbon and one atom thick planar sheets of sp2-bonded carbon atoms. Poly(ether sulfone)s bearing tetraphenylethylene on polymer backbone were synthesized by polycondensation and followed intra-cyclization from tetraphenylethylene to form MNF by Friedel-craft reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with conc. sulfuric acid. The structural properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the inducted highly conjugated aromatic structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 23-52%, compared with 32.13% for Nafion 211 at 80 degrees C. The synthesized membranes exhibited proton conductivities (80 degrees C, RH 90%) of 74.6-100.4 mS/cm, compared with 102.7 mS/cm for Nafion 211. PMID:25942900

  10. 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...

  11. Electrochemical ammonia synthesis from steam and nitrogen using proton conducting yttrium doped barium zirconate electrolyte with silver, platinum, and lanthanum strontium cobalt ferrite electrocatalyst

    Science.gov (United States)

    Yun, Dae Sik; Joo, Jong Hoon; Yu, Ji Haeng; Yoon, Hyung Chul; Kim, Jong-Nam; Yoo, Chung-Yul

    2015-06-01

    Electrochemical ammonia synthesis from steam and nitrogen has been systematically investigated using a proton-conducting electrolyte supported cell based on 20 mol% yttrium doped barium zirconate (BaZr0.8Y0.2O3-?) in a temperature range of 475-600 °C at atmospheric pressure. Silver (Ag), platinum (Pt), and lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-?) are used for both anode and cathode electrocatalysts. Maximum ammonia formation rates of 4.9 × 10-11 mol cm-2 s-1 and 8.5 × 10-11 mol cm-2 s-1 are observed for Ag and La0.6Sr0.4Co0.2Fe0.8O3-? electrocatalysts, respectively, when a voltage of 0.8 V is applied. However, Pt electrocatalyst shows a negligible ammonia formation rate lower than 1 × 10-12 mol cm-2 s-1. This is ascribed to the high activity of Pt for the hydrogen evolution reaction rather than the ammonia formation reaction. The conversion efficiency of all electrocatalysts is below 1%, primarily due to the limited nitrogen disassociation activity of the electrocatalysts.

  12. Synthesis, and crystal and electronic structure of sodium metal phosphate for use as a hybrid capacitor in non-aqueous electrolyte.

    Science.gov (United States)

    Sundaram, Manickam Minakshi; Watcharatharapong, Teeraphat; Chakraborty, Sudip; Ahuja, Rajeev; Duraisamy, Shanmughasundaram; Rao, Penki Tirupathi; Munichandraiah, Nookala

    2015-11-18

    Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Their synthesis, and crystal and electronic properties have been discussed, because of the importance of electronic conductivity in supercapacitors for high rate applications. The density of states of a mixed sodium transition metal phosphate (maricite, NaMn1/3Co1/3Ni1/3PO4) has been determined with the ab initio generalized gradient approximation (GGA)+Hubbard term (U) method. The computed results for the mixed maricite are compared with the band gap of the parent NaFePO4 and the electrochemical experimental results are in good agreement. A mixed sodium transition metal phosphate served as an active electrode material for a hybrid supercapacitor. The hybrid device (maricite versus carbon) in a non-aqueous electrolyte shows redox peaks in the cyclic voltammograms and asymmetric profiles in the charge-discharge curves while exhibiting a specific capacitance of 40 F g(-1) and these processes are found to be quasi-reversible. After long term cycling, the device exhibits excellent capacity retention (95%) and coulombic efficiency (92%). The presence of carbon and the nanocomposite morphology, identified through X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies, ensures the high rate capability while offering possibilities to develop new cathode materials for sodium hybrid devices. PMID:26530639

  13. Rheology of liquid foam

    International Nuclear Information System (INIS)

    Liquid foams can behave like solids or liquids, depending on the applied stress and on the experimental timescale. Understanding the origin of this complex rheology which gives rise to many applications and which resembles that of many other forms of soft condensed matter made of closely packed soft units requires challenging theoretical questions to be solved. We briefly recall the basic physics and physicochemistry of foams and review the experiments, numerical simulations and theoretical models concerning foam rheology published in recent years. (topical review)

  14. Synthesis of polymer electrolyte membranes from cellulose acetate/poly(ethylene oxide)/LiClO4 for lithium ion battery application

    Science.gov (United States)

    Nurhadini, Arcana, I. Made

    2015-09-01

    This study was conducted to determine the effect of cellulose acetate on poly(ethylene oxide)-LiClO4 membranes as the polymer electrolyte. Cellulose acetate is used as an additive to increase ionic conductivity and mechanical property of polymer electrolyte membranes. The increase the percentage of cellulose acetate in membranes do not directly effect on the ionic conductivity, and the highest ionic conductivity of membranes about 5,7 × 10-4 S/cm was observed in SA/PEO/LiClO4 membrane with cellulose ratio of 10-25% (w/w). Cellulose acetate in membranes increases mechanical strength of polymer electrolyte membranes. Based on TGA analysis, this polymer electrolyte thermally is stable until 270 °C. The polymer electrolyte membrane prepared by blending the cellulose acetate, poly(ethylene oxide), and lithium chlorate could be potentially used as a polymer electrolyte for lithium ion battery application.

  15. RHEOLOGY OF CONCENTRATED DISPERSIONS

    OpenAIRE

    Blanc, R

    1986-01-01

    In this paper we briefly present the main relevant physical quantities in the rheology of concentrated dispersions. Main lines of three topics (shear viscosity, sedimentation velocity and aggregation processes) are then given. The importance or ordered or random structures is emphasized.

  16. Rheological phase synthesis and characterization of Li3V2(PO4)3/C composites as cathode materials for lithium ion batteries

    International Nuclear Information System (INIS)

    Li3V2(PO4)3/C composites as cathode materials for lithium ion batteries were successfully synthesized through the rheological phase reaction method using LiOH·H2O, V2O5, NH4H2PO4, and C6H8O7·H2O as raw materials. The as-prepared powders were characterized by means of powder X-ray diffraction (XRD), scan electron microscope (SEM), and transmission electron microscope (TEM). The electrochemical properties of Li3V2(PO4)3/C composites were examined by the galvanostatic charge/discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicate that the sintering temperatures have a significant effect on the crystal structure, morphology, and electrochemical performances of Li3V2(PO4)3/C composites. XRD reveals that Li3V2(PO4)3/C composites are well crystallized single phase, where Li3V2(PO4)3/C composite synthesized at 800 °C for 8 h displays the maximum cell volume and uniformly distributed particles. It can be seen from TEM that there is a carbon layer of about 200-500 nm thick on the particle surface. The apparent DLi+ calculated from CV is in the order of magnitude of 10?7 cm2 s?1. Electrochemical tests show that Li3V2(PO4)3/C composite synthesized at 800 °C for 8 h exhibits excellent cycling performance of 129.149 mAh g?1 after 60 cycles at the current of 15 mA g?1 and a superior rate capability of 112.101 mAh g?1 after 60 cycles at the current of 90 mA g?1

  17. 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)

  18. Rheology of Attractive Emulsions

    OpenAIRE

    Datta, Sujit S.; Gerrard, Dustin D.; Rhodes, Travers S.; Mason, Thomas G.; Weitz, David A

    2012-01-01

    We show how attractive interactions dramatically influence emulsion rheology. Unlike the repulsive case, attractive emulsions below random close packing, RCP, can form soft gel-like elastic solids. However, above RCP, attractive and repulsive emulsions have similar elasticities. Such compressed attractive emulsions undergo an additional shear-driven relaxation process during yielding. Our results suggest that attractive emulsions begin to yield at weak points through the bre...

  19. Blood rheology and aging

    OpenAIRE

    Simmonds, Michael J.; Meiselman, Herbert J.; Baskurt, Oguz K

    2013-01-01

    The flow properties of blood play significant roles in tissue perfusion by contributing to hydrodynamic resistance in blood vessels. These properties are influenced by pathophysiological processes, thereby increasing the clinical relevance of blood rheology information. There is well-established clinical evidence for impaired blood fluidity in humans of advanced age, including enhanced plasma and whole blood viscosity, impaired red blood cell (RBC) deformability and enhanced RBC aggregation. ...

  20. Linear and nonlinear rheology of wormlike micelles

    Science.gov (United States)

    Sood, A. K.; Bandyopadhyay, Ranjini; Basappa, Geetha

    1999-07-01

    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 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 ( ~ 0.9 wt%) without the addition of electrolytes. Microrheology measurements of G(w )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 s is a nonmonotonic function of the shear rate g . In stress-controlled experiments, the shear stress shows a plateau for g larger than some critical strain rate, similar to the earlier reports on CPyCl/NaSal system. Cates et al have proposed that the plateau is a signature of mechanical instability in the form of shear bands. We have carried out extensive experiments under controlled strain rate conditions, to study the time-dependence of shear stress. The measured time series of shear stress has been analysed in terms of correlation integral and Lyapunov exponent to show unambiguously that the behaviour is typical of low dimensional dynamical systems.

  1. 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.

  2. Rheology of electrorheological fluids

    International Nuclear Information System (INIS)

    We present experimental and theoretical results on the shear thinning of electrorheological fluids. Rheological measurements on a model fluid consisting of monodisperse silica spheres immersed in a dielectric liquid show a power-law dependence ???-? of the apparent viscosity ? on the strain rate ?, with ? in the range ?=0.68--0.93. We present a theoretical treatment of steady-state cluster formation in applied electric and shear fields, which correctly predicts the observed power-law shear thinning albeit with an exponent ?=2/3. We observe no true yield stress in this material

  3. 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.

  4. Utilization of the secondary energy of Itaipu, Parana State, Brazil, for electrolytical ammonia production for nitrogenous fertilizers synthesis; Utilizacao da energia secundaria da usina hidreletrica de Itaipu, PR, Brasil para producao de amonia eletrolitica para sintese de fertilizantes nitrogenados

    Energy Technology Data Exchange (ETDEWEB)

    Souza, S.N.M. de; Siqueira, J.A.C.

    2000-07-01

    Secondary energy can be described as a surplus of electrical energy in hydraulic power plant due to the lower demand of energy during some periods of time, and the excess of water in the reservoir, during rainy periods. The largest hydroelectric power plant both in Brazil and South America is Itaipu, jointly operated by Brazil and Paraguay. This power plant has a large amount of secondary energy available, and this energy is lost as no turbine spilled water out of the reservoir. This study proposes the using of this energy for electrolytic hydrogen production and ammonia for nitrogenous fertilizers. The hydrogen is produced as a gas by mean of electrolyses and with the atmospheric nitrogen for the electrolytic ammonia synthesis, used as the most important raw material for the nitrogen fertilizers synthesis. This study performs the determination of the minimal cost of hydrogen production and the correspondent hydrogen production capacity in accordance with the ammonia market for nitrogenated fertilizers in the Center/South region, estimating the better production capacity for an ammonia plant to be installed close to Itaipu.

  5. 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.

  6. Rheological behavior study of a clay-polymer mixture: effects of the polymer addition

    International Nuclear Information System (INIS)

    The aim of the present work is to establish a bibliographical synthesis on the microstructure, the colloidal and rheological characterization of bentonite suspensions with and without polymer/surfactant addition; to lead to a rheological characterization of clay-additive mixtures and to understand the interaction between the clay particles and polymer/surfactants. Different experimental measurements: rheology, particle sizing, and x-ray diffraction were used to study the rheological character of the water-bentonite-anionic additive mixtures (CMC, SDS, xanthane) as well as the nature of the particle-particle interactions and particle-additive. The modeling part led to the adoption of Tiu and Boger's model to predict the thixotropy of the bentonite suspensions without additive. Thus, a new model is proposed with physical parameters for a better correlation of the rheological behavior of the various studied mixtures. (author)

  7. Synthesis and characterization of sulfonate polystyrene-lignosulfonate-alumina (SPS-LS-Al2O3) polyblends as electrolyte membranes for fuel cell

    Science.gov (United States)

    Gonggo, Siang Tandi

    2015-09-01

    The new type of electrolyte membrane materials has been prepared by blend sulfonated polystyrene (SPS), lignosulfonate (LS), and alumina (SPS-LS-Al2O3) by casting polymer solution. The resulting polymer electrolyte membranes were then characterized by functional groups analysis, mechanical properties, water uptake, ion exchange capacity, and proton conductivity. SPS-LS-Al2O3 membranes with alumina composition various have been proven qualitatively by analysis of functional groups. Increasing the Al2O3 ratio resulted in higher ion exchange capacity (IEC), mechanical strength and proton conductivity, but water uptake decreased. The SPS-LS-Al2O3 blend showed higher proton conductivity than Nafion 117.

  8. 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.

  9. Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia

    International Nuclear Information System (INIS)

    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 ?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)

  10. Rheology of carbon nanotube dispersions

    CERN Document Server

    Huang, Y Y; Terentyev, E M

    2006-01-01

    We report on rheological properties of a dispersion of multi-walled carbon nanotubes in a viscous polymer matrix. Particular attention is paid to the process of nanotubes mixing and dispersion, which we monitor by the rheological signature of the composite. The response of the composite as a function of the dispersion mixing time and conditions indicates that a critical mixing time t* needs to be exceeded to achieve satisfactory dispersion of aggregates, this time being a function of nanotube concentration and the mixing shear stress. At shorter times of shear mixing, tt*, has several universal rheological features; at nanotube concentration above a characteristic value ~2-3wt% the effective elastic gel network is formed, while the low-concentration composite remains a viscous liquid. We use this rheological approach to determine the effects of aging and re-aggregation.

  11. Rheological characterization of dental waxes

    OpenAIRE

    Zhang, Kehao

    2004-01-01

    Objectives The purpose of this study was to evaluate the rheological behaviour of new experimental dental waxes in dependent on temperature. Material and method Seven experimental dental waxes, provided by Dentaurum GmbH, were tested. No.018 was chosen as a control. Rheological experiments were performed at different temperatures using a Paar Physica Rheometer UDS200 equiped with a parallel plate cell. The temperature was regulated with a Peltier system (TEK130P) and a thermostat un...

  12. RHEOLOGICAL CHARACTERIZATION OF AGED ASPHALTS

    OpenAIRE

    Natalia Afanasieva; Mario Álvarez; Mónica J. Ortiz

    2002-01-01

    The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different t...

  13. 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)

  14. Electro-rheological disk pump

    Science.gov (United States)

    Iorio, Vincent M.; Loy, Luke W.

    1993-02-01

    The invention is directed to a device for pumping electro-rheological fluids comprising a casing that defines an inner rotor chamber having a central inlet opening and a peripheral discharge opening. Rotatably disposed within said chamber is a rotor for imparting energy to the pumped electro-rheological fluid comprising of a plurality of non-conducting coaxial substantially parallel spaced disks. On one face of each disk are embedded one or more electrodes and on the opposing face of each disk are attached one or more conductive surfaces. By selectively applying an electric charge to the embedded electrodes, an electric field is produced between the electrodes and the conducting surfaces of adjacent disks. As a result, the viscosity of the electro-rheological fluid exposed to the applied electric field is increased thereby producing electro-rheological fluid vanes between adjacent disks. When the rotor is placed in rotation and a voltage is applied to the embedded electrodes, the electro-rheological fluid that is not exposed to the applied electric field, it is accelerated from the center of the rotor towards the outer periphery by the combined action of the electro-rheological fluid vanes and the friction force acting between the fluid and the rotating disks.

  15. The Deflocculation of Kaolin Suspensions – the Effect of Various Electrolytes

    OpenAIRE

    P?nkavová, V?ra

    2013-01-01

    The deflocculation effect of conventional additives to kaolin suspensions is evaluated from the results standard rheological measurements. Several widely used electrolytes (NaOH, Na2CO3, Na2SiO3, SHMP = sodium hexametaphosphate, and CMC = sodium salts of carboxymethylcellulose) have been tested. The optimal concentrations of these deffloculants, in respect to reaching the maximum reduction of initial suspension viscosity, are found. The stability of deflocculated kaolin suspensions against...

  16. The deflocculation of kaolin suspensions : the effect of various electrolytes

    OpenAIRE

    Penkavová, V.; Guerreiro, Margarida; Tihon, J.; Teixeira, J. A.

    2013-01-01

    The deflocculation effect of conventional additives to kaolin suspensions is evaluated from the results standard rheological measurements. Several widely used electrolytes (NaOH, Na2C03, Na2Si03, SHMP = sodium hexametaphosphate, and CMC = sodium salts of carboxymethylcellulose) have been tested. The optimal concentrations of these deffloculants, in respect to reaching the maximum reduction of initial suspension viscosity, are found. The stability of deflocculated kaolin suspens...

  17. Synthesis, characterization and electrical properties of solid electrolyte for solid oxide fuel cell; Preparacao, caracterizacao e propriedades eletricas de eletrolito solido para celula a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Berton, Marco Antonio Coelho; Garcia, Carlos Mario; Matos, Jeferson Hrenechen [Instituto de Tecnologia para o Desenvolvimento (LACTEC), Curitiba, PR (Brazil)], Emails: felsky@latec.org.br, garcia@latec.org.br, jeferson.h@latec.org.br

    2010-04-15

    Solid electrolytes of BaCe{sub 08}Gd{sub O29} were prepared by the polymeric precursor method. X-ray diffraction data shows a single phase with orthorhombic crystalline structure. The densification process was followed by scanning electronic microscopy and apparent density measurements. The apparent density was developed for different temperatures of sintering, reaching > 96% for sintered temperature of 1550 {sup 0}C deg . The electrochemical impedance analysis was development in the temperature of 400-700 deg C, in air atmosphere at 700 deg C a value of 30,6 mS.cm{sup -1} was obtained. The results of conductivity have confirmed the gadolinium doped barium cerate has a great potential for use as solid electrolyte for intermediate temperature solid oxide fuel cell, at experimental controlled conditions. (author)

  18. Blood rheology and aging

    Directory of Open Access Journals (Sweden)

    Michael J. Simmonds

    2013-09-01

    Full Text Available The flow properties of blood play significant roles in tissue perfusion by contributing to hydrodynamic resistance in blood vessels. These properties are influenced by pathophysiological processes, thereby increasing the clinical relevance of blood rheology information. There is well-established clinical evidence for impaired blood fluidity in humans of advanced age, including enhanced plasma and whole blood viscosity, impaired red blood cell (RBC deformability and enhanced RBC aggregation. Increased plasma fibrinogen concentration is a common finding in many studies owing to the pro-inflammatory condition of aged individuals; this finding of increased fibrinogen concentration explains the higher plasma viscosity and RBC aggregation in elderly subjects. Enhanced oxidant stress in advanced age is also known to contribute to altered blood fluidity, with RBC deformability being an important determinant of blood viscosity. Several studies have shown that physical activity may improve the hemorheological picture in elderly subjects, yet well-designed observational and mechanistic studies are required to determine the specific effects of regular exercise on hemorheological parameters in healthy and older individuals.

  19. Rheology of fractal networks

    CERN Document Server

    Patricio, Pedro; Duarte, Jorge; Januario, Cristina

    2015-01-01

    We investigate the rheology of a fractal network, in the framework of the linear theory of viscoelasticity. We identify each segment of the network with a simple Kelvin-Voigt element, with a well defined equilibrium length. The final structure retains the elastic characteristics of a solid or a gel. By considering a very simple regular self-similar structure of segments in series and in parallel, in 1, 2 or 3 dimensions, we are able to express the viscoelasticity of the network as an effective generalised Kelvin-Voigt model with a power law spectrum of retardation times, $\\phi\\sim\\tau^{\\alpha-1}$. We relate the parameter $\\alpha$ with the fractal dimension of the gel. In some regimes ($0<\\alpha<1$), we recover the weak power law behaviours of the elastic and viscous moduli with the angular frequencies, $G'\\sim G''\\sim w^\\alpha$, that occur in a variety of soft materials, including living cells. In other regimes, we find different and interesting power laws for $G'$ and $G''$.

  20. 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...

  1. 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.

  2. Dry granular flows: Rheological measurements of the ?(I)-rheology

    Science.gov (United States)

    Fall, A.; Ovarlez, G.; Hautemayou, D.; Mézière, C.; Roux, J.-N.; Chevoir, F.

    2015-07-01

    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 $\\mu(I)$-rheology.

  3. 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.

  4. Synthesis, structural analysis and electrochemical performances of BLSITCFx as new cathode materials for solid oxide fuel cells (SOFC) based on BIT07 electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Letilly, M.; Le Gal La Salle, A.; Joubert, O. [Institut des Materiaux Jean Rouxel (IMN), CNRS- Universite de Nantes, 2 rue de la Houssiniere, BP 32229, 44322 Nantes (France); Lachgar, A. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States)

    2010-08-01

    BaIn{sub 0.3}Ti{sub 0.7}O{sub 2.85} (BIT07) is a suitable electrolyte for Solid Oxide Fuel Cell (SOFC) but half cells based on La{sub 0.58}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (LSCF) as a cathode material show a degradation of the Area Specific Resistance (ASR) at 700 C with time. This study deals with the characterization of alternative cathode materials showing a better compatibility with BIT07 than LSCF. A new solid solution, Ba{sub x}La{sub 0.58(1-x)}Sr{sub 0.4(1-x)}In{sub 0.3x}Ti{sub 0.7x}Co{sub 0.2(1-x)} Fe{sub 0.8(1-x)}O{sub 3-{delta}}, with 0 {<=} x {<=} 1, also called BLSITCFx, with in this case x expressed in molar %, derived from BIT07 and LSCF, has been synthesized at 1350 C in air using BIT07 and LSCF powders. Two compositions, BLSITCF12 and BLSITCF25, have been selected due to their thermal expansion and conductivity properties. Symmetrical half cells based on these two new materials deposited on BIT07 electrolyte have been studied by complex impedance spectroscopy in air versus temperature and time. Their behaviour is comparable to LSCF's, with ASR values never exceeding 0.2 {omega}cm{sup 2} at 700 C, and moreover their less important Thermal Expansion Coefficient (TEC) mismatch with BIT07 lead to a better mechanical compatibility with time. These new compounds are therefore better candidates than LSCF as cathode materials for SOFC based on BIT07 electrolyte. (author)

  5. 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.

  6. Design of magneto-rheological (MR) valve

    OpenAIRE

    Grunwald, Artur; Olabi, Abdul-Ghani

    2008-01-01

    Magneto-Rheological Fluid (“MRF”) technology has been successfully employed in various low and high volume automotive applications. Good understanding of specific design constraints is required to define and to optimize a magneto-rheological device. This article presents parametrical analyses with magnetic simulations, of a magneto-rheological valve and a magneto-rheological orifice. Experimental rig assemblies of two different control devices have been designed, built and the performances ha...

  7. 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...

  8. Molecular Rheology of Complex Fluids

    DEFF Research Database (Denmark)

    Huang, Qian; Rasmussen, Henrik Koblitz

    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...

  9. Rheology for chemists an introduction

    CERN Document Server

    Goodwin, J W

    2000-01-01

    Rheology is an integral part of life, from decorative paint and movement of volcanic lava to the flow of blood in our veins. This book describes, without the use of complex mathematics, how atoms and molecules interact to control the handling properties of materials ranging from simple ionic crystals through polymers to colloidal dispersions.Beginning with an introduction to essential terminology, Rheology for Chemists goes on to discuss limiting behaviour, temporal behaviour and non-linear behaviour. Throughout, examples of everyday experiments are provided to illustrate the theory, which inc

  10. Synthesis, Multinuclear NMR Characterization and Dynamic Property of Organic–Inorganic Hybrid Electrolyte Membrane Based on Alkoxysilane and Poly(oxyalkylene Diamine

    Directory of Open Access Journals (Sweden)

    Hsien-Ming Kao

    2012-06-01

    Full Text Available Organic–inorganic hybrid electrolyte membranes based on poly(propylene glycol-block-poly(ethylene glycol-block-poly(propylene glycol bis(2-aminopropyl ether complexed with LiClO4 via the co-condensation of tetraethoxysilane (TEOS and 3-(triethoxysilylpropyl isocyanate have been prepared and characterized. A variety of techniques such as differential scanning calorimetry (DSC, Fourier transform infrared (FTIR spectroscopy, alternating current (AC impedance and solid-state nuclear magnetic resonance (NMR spectroscopy are performed to elucidate the relationship between the structural and dynamic properties of the hybrid electrolyte and the ion mobility. A VTF (Vogel-Tamman-Fulcher-like temperature dependence of ionic conductivity is observed for all the compositions studied, implying that the diffusion of charge carriers is assisted by the segmental motions of the polymer chains. A maximum ionic conductivity value of 5.3 × 10?5 Scm?1 is obtained at 30 °C. Solid-state NMR results provide a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains.

  11. Simple rheology of mixed proteins

    Science.gov (United States)

    Mixing different proteins to form strong gel networks for food applications may create synergistic increases in viscoelasticity that cannot be achieved with a single protein. In this study, small amplitude oscillatory shear analyses were used to investigate the rheology of calcium caseinate (CC), e...

  12. 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.)

  13. 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.

  14. 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.

  15. Synthesis and ceramic processing of zirconia alumina composites for application as solid oxide fuel cell electrolytes; Sintese e processamento de compositos de zirconia-alumina para aplicacao como eletrolito em celulas a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Rafael Henrique Lazzari

    2007-07-01

    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)

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

    International Nuclear Information System (INIS)

    Highlights: •γ-BIMNVOX was synthesized by ethylene glycol–citrate sol–gel route. •γ-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 γ-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 γ-BIMNVOX samples with appreciably small average particle sizes after only 25 min of microwave heating. The electrical properties of microwave calcined γ-BIMNVOX system make it an advanced low-temperature solid electrolyte suitable for use in oxide-ion based electrochemical applications

  17. Gel-combustion synthesis of LiFePO4/C composite with improved capacity retention in aerated aqueous electrolyte solution

    International Nuclear Information System (INIS)

    Highlights: ? Gel combustion route was used to prepare LiFePO4/C composite with high carbon content ? Theoretical discharge capacity was achieved in non-aqueous medium at rate 0.1 C ? Best so far reported capacity retention in aqueous electrolyte was achieved ? Thick C shell seems to be of crucial importance for LiFePO4 in aqueous media. -- Abstract: The LiFePO4/C composite containing 13.4 wt.% of carbon was synthesized by combustion of a metal salt–(glycine + malonic acid) gel, followed by an isothermal heat-treatment of combustion product at 750 °C in reducing atmosphere. By a brief test in 1 M LiClO4–propylene carbonate solution at a rate of C/10, the discharge capacity was proven to be equal to the theoretical one. In aqueous LiNO3 solution equilibrated with air, at a rate C/3, initial discharge capacity of 106 mAh g?1 was measured, being among the highest ones observed for various Li-ion intercalation materials in aqueous solutions. In addition, significant prolongation of cycle life was achieved, illustrated by the fact that upon 120 charging/discharging cycles at various rates, the capacity remained as high as 80% of initial value. The chemical diffusion coefficient of lithium in this composite was measured by cyclic voltammetry. The obtained values were compared to the existing literature data, and the reasons of high scatter of reported values were considered

  18. Sol-gel synthesis and characterization of Zn2+ and Mg2+ doped La10Si6O27 electrolytes for solid oxide fuel cells

    Science.gov (United States)

    Setsoafia, D. D. Y.; Hing, P.; Jung, S. C.; Azad, A. K.; Lim, C. M.

    2015-10-01

    Achieving high densification at low sintering temperatures for lanthanum silicate apatites is a major technological hurdle to enable this class of materials to be evaluated as electrolytes for solid oxide fuel cells. Using sol-gel process, materials close to 97% of theoretical density have been obtained at a low sintering temperature of 1773 K for both doped and undoped samples. The effect of varying concentrations of Zn2+ doping on the sinterability, electrical, thermal and microstructural properties of 0.2 mol Mg2+ doped La10Si6O27 were investigated. Ionic conductivity of the samples was measured using electrochemical impedance spectroscopy in the temperature range of 573 K-1073 K. A total ionic conductivity of 1.7 × 10-2 Scm-1 with a corresponding activation energy of 0.33 eV at 1073 K were measured for the composition La10Zn0.2(SiO4)5.8O2.5 which is higher than 9 × 10-3 Scm-1 for the undoped composition La10(SiO4)6O3. The composition La10Mg0.2Zn0.4(SiO4)5.4O4.8 has the lowest thermal expansion coefficient of 8.470 × 10-6 K-1 of all the samples investigated.

  19. 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.

  20. 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 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.

  1. 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.

  2. Rheology of Martian lava flows

    OpenAIRE

    Chevrel, Magdalena Oryaelle

    2013-01-01

    In recent years, high-resolution topographic images from Mars’ surface as well as mineralogical and chemical data, have rapidly become more accessible. Martian volcanic landforms are characterized by giant low slope shield volcanoes, abundant lava flood plains and long lava flows. In-situ rock analysis and remote sensing spectroscopy reveal mainly basaltic compositions with particularly high iron concentrations, distinct from terrestrial basalts. As yet, very little is known about the rheolog...

  3. Combined neutron reflectometry and rheology

    OpenAIRE

    Wolff, Max; Kuhns, Peter; Liesche, Georg; Ankner, John F.; Browning, Jim F.; Gutfreund, Philipp

    2013-01-01

    We have combined neutron reflectometry with rheology in order to investigate the solid boundary of liquids and polymers under shear deformation. Our approach allows one to apply a controlled stress to a material while resolving the structural arrangements on the sub nanometer length scale with neutron reflectivity, off-specular and small angle scattering at the same time. The specularly reflected neutron intensity of a 20 % by weight solution of the Pluronic F127 in deuterat...

  4. Towards Prognostics of Electrolytic Capacitors

    Data.gov (United States)

    National Aeronautics and Space Administration — A remaining useful life prediction algorithm and degradation model for electrolytic capacitors is presented. Electrolytic capacitors are used in several...

  5. Synthesis and Characterization of Cu- and Co-Doped Bi4V2O11 for Intermediate-Temperature Solid Oxide Fuel Cell Electrolytes by Carbonate Coprecipitation

    Science.gov (United States)

    Lee, Jin Goo; Yoon, Hyon Hee

    2011-01-01

    Bi2MexV1-xO5.5-3x/2 (Me = Cu; 0≤x≤0.2) powders were prepared by the ammonium carbonate coprecipitation method. The starting salts were bismuth nitrate, copper nitrate, cobalt nitrate, and vanadium sulphate. The thermal decomposition of Bi2MexV1-xO5.5-3x/2 precursors was completed at about 500 °C. The crystallite structure, surface morphology, and ionic conductivity of the prepared powders and pellets were examined using X-ray diffractometry, field emission scanning electron microscopy, and an impedance analyzer, respectively. The average particle sizes of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 powders were 10-50 nm. The tetragonal structure (γ-phase) appeared at sintering temperatures higher than 700 °C and the peak intensity increased at higher sintering temperatures. The ionic conductivities of the Bi2Cu0.1V0.9O5.35 and Bi2Co0.1V0.9O5.35 pellets sintered at 800 °C showed the highest values of 6.8×10-2 S cm-1 at 700 °C and 9.1×10-2 S cm-1 at 700 °C, respectively. The optimum concentration of the Cu and Co dopants in Bi2MexV1-xO5.5-3x/2 was determined to be 0.1. The results of this study demonstrated that the ammonium carbonate coprecipitation process could be used as an economical method for the preparation of Bi2MexV1-xO5.5-3x/2 electrolytes for intermediate-temperature solid oxide fuel cells.

  6. Synthesis of anodic titania nanotubes in Na2SO4/NaF electrolyte: A comparison between anodization time and specimens with biomaterial based approaches

    International Nuclear Information System (INIS)

    Surface modification of commercially pure titanium (cp-Ti) has been carried out by electrochemical anodic oxidation at constant voltage for different time periods (0.5, 1, 2 and 4.5 h). Currents developed during the anodization indicate that the nanotubes are formed due to the competition of titania formation and dissolution under the assistance of electric field. Topologies of the anodized titanium change remarkably with time of oxidation. The morphology of the as-prepared nanotubes was characterized by scanning electron microscopy and atomic force microscopy while the chemistry and crystallinity were characterized by energy-dispersive X-ray spectroscopy and X-ray diffraction respectively. The as-anodized oxide was of amorphous but transformed to anatase and/or rutile crystal structure upon annealing for 3 h at 600 °C. The anatase structure showed excellent apatite-forming ability and produced a compact apatite layer covering the surface completely upon treatment in simulated body fluid (SBF) solution for 30 h. Corrosion of anodized titanium samples was studied in a SBF solution using open circuit potential, polarization and electrochemical impedance measurements and compared with that of non-oxidized titanium. Among these samples, titanium anodized for 4.5 h exhibited superior corrosion properties. - Highlights: • We synthesized TiO2 nanotubes by anodization in Na2SO4/NaF electrolyte. • Topologies of the anodized titanium change remarkably with oxidation time. • We studied surface morphologies of TiO2 nanotubes. • TiO2 nanotubes show superior corrosion resistance

  7. Structural Rheology of the Smectic Phase

    OpenAIRE

    Shuji Fujii; Shigeyuki Komura; Chun-Yi David Lu

    2014-01-01

    In this review article, we discuss the rheological properties of the thermotropic smectic liquid crystal 8CB with focal conic domains (FCDs) from the viewpoint of structural rheology. It is known that the unbinding of the dislocation loops in the smectic phase drives the smectic-nematic transition. Here we discuss how the unbinding of the dislocation loops affects the evolution of the FCD size, linear and nonlinear rheological behaviors of the smectic phase. By studying the FCD formation from...

  8. 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

  9. 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.

  10. Lithium-ion transport in inorganic solid state electrolyte

    Science.gov (United States)

    Jian, Gao; Yu-Sheng, Zhao; Si-Qi, Shi; Hong, Li

    2016-01-01

    An overview of ion transport in lithium-ion inorganic solid state electrolytes is presented, aimed at exploring and designing better electrolyte materials. Ionic conductivity is one of the most important indices of the performance of inorganic solid state electrolytes. The general definition of solid state electrolytes is presented in terms of their role in a working cell (to convey ions while isolate electrons), and the history of solid electrolyte development is briefly summarized. Ways of using the available theoretical models and experimental methods to characterize lithium-ion transport in solid state electrolytes are systematically introduced. Then the various factors that affect ionic conductivity are itemized, including mainly structural disorder, composite materials and interface effects between a solid electrolyte and an electrode. Finally, strategies for future material systems, for synthesis and characterization methods, and for theory and calculation are proposed, aiming to help accelerate the design and development of new solid electrolytes. Project supported by the National Natural Science Foundation of China (Grant No. 51372228), the Shanghai Pujiang Program, China (Grant No. 14PJ1403900), and the Shanghai Institute of Materials Genome from the Shanghai Municipal Science and Technology Commission, China (Grant No. 14DZ2261200).

  11. Anion exchange polymer electrolytes

    Science.gov (United States)

    Kim, Yu Seung; Kim, Dae Sik

    2015-06-02

    Anion exchange polymer electrolytes that include guanidinium functionalized polymers may be used as membranes and binders for electrocatalysts in preparation of anodes for electrochemical cells such as solid alkaline fuel cells.

  12. Rheology of Soft Glassy Materials

    CERN Document Server

    Sollich, P; Hébraud, P; Cates, M E; Sollich, Peter; Lequeux, Francois; Hebraud, Pascal; Cates, Michael E

    1997-01-01

    We attribute similarities in the rheology of many soft materials (foams, emulsions, slurries, etc.) to the shared features of structural disorder and metastability. A generic model for the mesoscopic dynamics of ``soft glassy matter'' is introduced, with interactions represented by a mean-field noise temperature x. We find power law fluid behavior either with (x<1) or without (1

  13. Nanoscale Organic Hybrid Electrolytes

    KAUST Repository

    Nugent, Jennifer L.

    2010-08-20

    Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. 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

  15. Nonlinear rheology of colloidal dispersions

    International Nuclear Information System (INIS)

    Colloidal dispersions are commonly encountered in everyday life and represent an important class of complex fluid. Of particular significance for many commercial products and industrial processes is the ability to control and manipulate the macroscopic flow response of a dispersion by tuning the microscopic interactions between the constituents. An important step towards attaining this goal is the development of robust theoretical methods for predicting from first-principles the rheology and nonequilibrium microstructure of well defined model systems subject to external flow. In this review we give an overview of some promising theoretical approaches and the phenomena they seek to describe, focusing, for simplicity, on systems for which the colloidal particles interact via strongly repulsive, spherically symmetric interactions. In presenting the various theories, we will consider first low volume fraction systems, for which a number of exact results may be derived, before moving on to consider the intermediate and high volume fraction states which present both the most interesting physics and the most demanding technical challenges. In the high volume fraction regime particular emphasis will be given to the rheology of dynamically arrested states. (topical review)

  16. Microgravity Foam Structure and Rheology

    Science.gov (United States)

    Durian, Douglas J.

    1997-01-01

    To exploit rheological and multiple-light scattering techniques, and ultimately microgravity conditions, in order to quantify and elucidate the unusual elastic character of foams in terms of their underlying microscopic structure and dynamics. Special interest is in determining how this elastic character vanishes, i.e. how the foam melts into a simple viscous liquid, as a function of both increasing liquid content and shear strain rate. The unusual elastic character of foams will be quantified macroscopically by measurement of the shear stress as a function of static shear strain, shear strain rate, and time following a step strain; such data will be analyzed in terms of a yield stress, a static shear modulus, and dynamical time scales. Microscopic information about bubble packing and rearrangement dynamics, from which these macroscopic non-Newtonian properties presumably arise, will be obtained non-invasively by novel multiple-light scattering diagnostics such as Diffusing-Wave Spectroscopy (DWS). Quantitative trends with materials parameters, such as average bubble size, and liquid content, will be sought in order to elucidate the fundamental connection between the microscopic structure and dynamics and the macroscopic rheology.

  17. RHEOLOGICAL CHARACTERIZATION OF AGED ASPHALTS

    Directory of Open Access Journals (Sweden)

    Natalia Afanasieva

    2002-12-01

    Full Text Available The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of SHRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different temperatures and load times.En el presente trabajo se estudian las propiedades reológicas de los tres tipos de asfaltos industriales producidos en Colombia, en las refinerías de Barrancabermeja, Cartagena y Apiay, después del envejecimiento durante 18 meses en un banco de pruebas al aire libre especialmente diseñado. La evaluación del comportamiento reológico se realizó a través de ensayos basados en las nuevas especificaciones de la tecnología SHRP en los reómetros Brookfield y DSR para determinar características tales como: viscosidad, esfuerzo de corte, susceptibilidad térmica, velocidad de deformación y módulo de corte dinámico, a diferentes temperaturas y tiempos de carga.

  18. RHEOLOGICAL CHARACTERIZATION OF AGED ASPHALTS

    Scientific Electronic Library Online (English)

    Natalia, Afanasieva; Mario, Álvarez; Mónica J., Ortiz.

    2002-12-01

    Full Text Available En el presente trabajo se estudian las propiedades reológicas de los tres tipos de asfaltos industriales producidos en Colombia, en las refinerías de Barrancabermeja, Cartagena y Apiay, después del envejecimiento durante 18 meses en un banco de pruebas al aire libre especialmente diseñado. La evalua [...] ción del comportamiento reológico se realizó a través de ensayos basados en las nuevas especificaciones de la tecnología SHRP en los reómetros Brookfield y DSR para determinar características tales como: viscosidad, esfuerzo de corte, susceptibilidad térmica, velocidad de deformación y módulo de corte dinámico, a diferentes temperaturas y tiempos de carga. Abstract in english The present work shows the rheological properties of the three Colombian asphalts produced in the refineries at Barrancabermeja, Cartagena and Apiay, exposed to the open air during 18 months using a specially designed testing bank. Rheological behavior was evaluated using the new specifications of S [...] HRP technology in the Brookfield and DSR rheometers to determine viscosity, Shear Stress, Shear Rate, Dynamic Share Modulus and other related variables. The measurements were made using different temperatures and load times.

  19. 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.

  20. RHEOLOGIC BEHAVIOR OF PASTRY CREAMS

    Directory of Open Access Journals (Sweden)

    Camelia Vizireanu

    2012-03-01

    Full Text Available The increased social and economic importance of ready–made food production, together with the complexity of production technology, processing, handling and acceptance of these fragile and perishable products requires extensive knowledge of their physical properties. Viscoelastic properties play an important role in the handling and quality attributes of creams.Our study was to investigate the rheological properties of different confectionary creams, by scanning the field of shear rates at constant temperature and frequency, angular frequency scanning at small deformations and quantification of rheological changes during application of deformation voltages. The creams tested were made in the laboratory using specific concentrates as fine powders, marketed by the company “Dr. Oetker” compared with similar creams based on traditional recipes and techniques. Following the researches conducted we could conclude that both traditional creams and the instant ones are semi fluid food products with pseudoplastic and thixotropic shear flow behavior, with structural viscosity. Instant and traditional creams behaved as physical gels with links susceptible to destruction, when subjected to deformation forces.

  1. Synthesis and electrochemical characterization of hybrid membrane Nafion-SiO{sub 2} for application as polymer electrolyte in PEM fuel cell; Sintese e caracterizacao eletroquimica de membranas hibridas Nafion-SiO{sub 2} para aplicacao como eletrolito polimerico em celulas a combustivel tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Dresch, Mauro Andre

    2009-07-01

    In this work, the effect of sol-gel synthesis parameters on the preparation and polarization response of Nafion-SiO{sub 2} 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-SiO{sub 2} 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 H{sub 2}/O{sub 2} 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)

  2. Rheologycal properties of sodium carboxymethylcellulose in the presence of electrolyte and mixed micelle of surfactants

    Directory of Open Access Journals (Sweden)

    Sovilj Verica J.

    2003-01-01

    Full Text Available One of the most significant aspects of polymer-surfactant interaction, from the practical point of view, is that of rheology control and viscosity enhancement. In the oppositely charged polyelectrolyte-surfactant system strong ionic interaction often leads to precipitation of the formed complex yielding serious problems. In this paper the interaction between anionic polyelectrolyte - sodium carboxymethylcellulose (NaCMC and cationic surfactant - cethyltrimethylammonium bromide (CTMAB has been investigated by rheological measurements. Addition of electrolyte NaBr and nonionic surfactant - Tween 80 reduced the binding strength, prevented the precipitation of the complex and increased the viscosity of the system. It was found that rheological properties are strong influenced by NaCMC-CTMAB interaction and the system exhibits either pseudoplastic or thixotropic or rheopectic behavior according to the intensity of interaction.

  3. Lithium dendrite growth through solid polymer electrolyte membranes

    Science.gov (United States)

    Harry, Katherine; Schauser, Nicole; Balsara, Nitash

    2015-03-01

    Replacing the graphite-based anode in current batteries with a lithium foil will result in a qualitative increase in the energy density of lithium batteries. The primary reason for not adopting lithium-foil anodes is the formation of dendrites during cell charging. In this study, stop-motion X-ray microtomography experiments were used to directly monitor the growth of lithium dendrites during electrochemical cycling of symmetric lithium-lithium cells with a block copolymer electrolyte. In an attempt to understand the relationship between viscoelastic properties of the electrolyte on dendrite formation, a series of complementary experiments including cell cycling, tomography, ac impedance, and rheology, were conducted above and below the glass transition temperature of the non-conducting poly(styrene) block; the conducting phase is a mixture of rubbery poly(ethylene oxide) and a lithium salt. The tomography experiments enable quantification of the evolution of strain in the block copolymer electrolyte. Our work provides fundamental insight into the dynamics of electrochemical deposition of metallic films in contact with high modulus polymer electrolytes. Rational approaches for slowing down and, perhaps, eliminating dendrite growth are proposed.

  4. Theory of rheology in confinement

    Science.gov (United States)

    Aerov, Artem A.; Krüger, Matthias

    2015-10-01

    The viscosity of fluids is generally understood in terms of kinetic mechanisms, i.e., particle collisions, or thermodynamic ones as imposed through structural distortions upon, e.g., applying shear. Often the latter are more relevant, which allows a simpler theoretical description, and, e.g., (damped) Brownian particles can be considered good fluid model systems. We formulate a general theoretical approach for rheology in confinement, based on microscopic equations of motion and classical density functional theory. Specifically, we discuss the viscosity for the case of two parallel walls in relative motion as a function of the wall-to-wall distance, analyzing its relation to the slip length found for a single wall. The previously observed [A. A. Aerov and M. Krüger, J. Chem. Phys. 140, 094701 (2014)., 10.1063/1.4866450] deficiency of inhomogeneous (unphysical) stresses under naive application of shear in confinement is healed when hydrodynamic interactions are included.

  5. Theory of rheology in confinement.

    Science.gov (United States)

    Aerov, Artem A; Krüger, Matthias

    2015-10-01

    The viscosity of fluids is generally understood in terms of kinetic mechanisms, i.e., particle collisions, or thermodynamic ones as imposed through structural distortions upon, e.g., applying shear. Often the latter are more relevant, which allows a simpler theoretical description, and, e.g., (damped) Brownian particles can be considered good fluid model systems. We formulate a general theoretical approach for rheology in confinement, based on microscopic equations of motion and classical density functional theory. Specifically, we discuss the viscosity for the case of two parallel walls in relative motion as a function of the wall-to-wall distance, analyzing its relation to the slip length found for a single wall. The previously observed [A. A. Aerov and M. Krüger, J. Chem. Phys. 140, 094701 (2014).] deficiency of inhomogeneous (unphysical) stresses under naive application of shear in confinement is healed when hydrodynamic interactions are included. PMID:26565234

  6. 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.

  7. 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.

  8. Analogy between dynamics of thermo-rheological and piezo-rheological pendulums

    Energy Technology Data Exchange (ETDEWEB)

    Hedrih, K [Faculty of Mechanical Engineering University of Nis, Mathematical Institute SANU, ul. Vojvode Tankosic 3/V/22, 18000-Nis (Serbia)], E-mail: katica@masfak.ni.ac.yu, E-mail: khedrih@eunet.yu

    2008-02-15

    The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out.

  9. Analogy between dynamics of thermo-rheological and piezo-rheological pendulums

    International Nuclear Information System (INIS)

    The constitutive stress-strain relations of the standard thermo-rheological and piezo-rheological hereditary element in differential form as well as in two different integro-differential forms are defined. The considered problem of a thermo-rheological hereditary discrete system nonlinear dynamics in the form of thermo-rheological double pendulum system with coupled pendulums gets the significance of two constrained bodies in plane motion problem, as a problem important for studying a sensor dynamics or actuator dynamics in active structure dynamics. System of the averaged equations in the first approximation for amplitudes and phases are derived and qualitatively analyzed. Analogy between nonlinear dynamics of the double pendulum systems with thermo-rheological and piezo-rheological properties between pendulums is pointed out

  10. Rheology of glasses containing crystalline material

    International Nuclear Information System (INIS)

    The rheology of nonhomogeneous glassy melts that contain crystalline material has not been studied in much detail. In this study, the rheology of melts containing simulated nuclear waste has been characterized as a function of melt temperature and crystalline content. These melts can be either Newtonian or non-Newtonian fluids, depending on their crystalline contents. Melts which are free of crystals are strictly Newtonian. Melts which contain from 2 to 10 vol % crystals are Newtonian fluids, which obey the Einstein-Smoluchovsky equation. The rheology of the melts containing ? 13 vol % is complex, but can be explained in terms of absolute rate theory

  11. Rheology v.2 theory and applications

    CERN Document Server

    Eirich, Frederick

    1958-01-01

    Rheology: Theory and Applications, Volume II deals with the specific rheological subjects, such as deformational behavior in relation to the classic subjects and topics of rheology. This volume is divided into 13 chapters. Considerable chapters are devoted to the theory and aspects of viscoelastic and relaxation phenomena, as well as the applied theory concerning substances related to these phenomena, including elastomers, gelatins, and fibers. Other chapters cover the general principles of geological deformations derived from the study of less """"immobile"""" objects. The remaining chapt

  12. Polymer electrolytes for a rechargeable li-Ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Argade, S.D.; Saraswat, A.K.; Rao, B.M.L. [Technochem Co., Greensboro, NC (United States); Lee, H.S.; Xiang, C.L.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States)

    1996-10-01

    Lithium-ion polymer electrolyte battery technology is attractive for many consumer and military applications. A Li{sub x}C/Li{sub y}Mn{sub 2}O{sub 4} battery system incorporating a polymer electrolyte separator base on novel Li-imide salts is being developed under sponsorship of US Army Research Laboratory (Fort Monmouth NJ). This paper reports on work currently in progress on synthesis of Li-imide salts, polymer electrolyte films incorporating these salts, and development of electrodes and cells. A number of Li salts have been synthesized and characterized. These salts appear to have good voltaic stability. PVDF polymer gel electrolytes based on these salts have exhibited conductivities in the range 10{sup -4} to 10{sub -3} S/cm.

  13. Rheology of tetraphenylborate precipitate slurry

    International Nuclear Information System (INIS)

    Savannah River Plant (SRP) is the nation's primary source of nuclear materials for defense, space, medical, and energy applications. SRP was built in the early 1950's by the Du Pont Company for the U.S. Atomic Energy Commission. The Du Pont Company still operates the plant as prime contractor for the U.S. Department of Energy. Since plant startup, approximately 72 million gallons of radioactive waste have been generated. Approximately 10% of the waste is sludge, which contains most of the radionuclides. The rest of the waste is liquid and salt, which consists primarily of sodium nitrate, sodium nitrite, sodium aluminate, and sodium hydroxide. The salt solution, supernate, contains cesium-137 and strontium-90. The radioactive cesium and strontium will be removed from the supernate by an In-Tank Precipation Process as part of a permanent radioactive waste disposal plan. In the Precipitation Process, sodium tetraphenylborate is used to precipitate cesium and sodium titanate is used to adsorb strontium. Potassium also precipitates, forming potassium tetraphenylborate, which is a major solid component of the slurry. The slurry is washed with water to decrease the amount of soluble solids in the solution. After the phenyl groups are removed by the Precipitate Hydrolysis Process, the radionuclides will be incorporated into borosilicate glass in the Defense Waste Processing Facility. Rheological properties of slurry are needed to design slurry pumps, transfer pumps, transfer lines, and vessel agitation. Studies were conducted to determine the transport characteristics of the tetraphenylborate precipitate slurry. This paper presents rheological information on a simulated nonradioactive potassium tetraphenylborate precipitate

  14. Rheology of welding: experimental constraints

    Science.gov (United States)

    Quane, S. L.; Russell, J. K.; Kennedy, L. A.

    2003-04-01

    The rheological behavior of pyroclastic deposits during welding is incompletely understood and is based on a surprisingly small number of experimental studies. Previous pioneering experimental studies were done on small (1 cm thick) samples of ash/crystal mixtures under constant load. They established minimum welding temperatures between 600 and 700^oC under loads of 0.7 MPa (˜40 m of ignimbrite) to 3.6 MPa (˜250 m depth of ignimbrite). However, these data are neither sufficiently comprehensive nor coherent enough to fully describe the rheology of pyroclastic mixtures. In addition, previous studies did not examine the microstructural and geometric changes associated with welding compaction. Our goal is to provide accurate and comprehensive constitutive relationships between material properties, temperature, load and strain rate for pyroclastic material undergoing welding. Here we present results from a newly designed experimental apparatus. The experimental apparatus consists of a LoadTrac II fully automated uniaxial compression load frame manufactured by Geocomp Corporation. The load frame has a built in displacement transducer and can run both constant strain rate (10-6 to 0.25 cm/s) and constant load (up to 1150 kg) tests to a maximum displacement of 7.5 cm. The sample assembly comprises 5 cm diameter cylindrical upper and lower pistons (insulating ceramic with steel conductive ends) housed in a copper jacket. Samples are 5 cm diameter cores and can vary in length from 1 to 15 cm depending on experimental needs. A fiber insulated tube furnace capable of reaching temperatures ?1000^oC surrounds the sample assembly. Temperature is measured using a thermocouple located inside the sample through the bottom piston; the furnace controller is capable of maintaining temperature fluctuations to welding of pyroclastic material.

  15. Rheological properties of magnetorheological fluids

    Science.gov (United States)

    Genç, Seval; Phulé, Pradeep P.

    2002-02-01

    The effects of dispersed phase saturation magnetization and applied magnetic fields on the rheological properties of magnetorheological (MR) fluids are described. MR fluids based on two different grades of carbonyl iron powder with different average particle size, 7-9 ?m (grade A) and 2 ?m (grade B), were prepared. Vibrating sample magnetometer measurements showed that the saturation magnetization values were 2.03 and 1.89 T for grades A and B, respectively. Rheological measurements were conducted for 33 and 40 vol% grade A and grade B based MR fluids with a specially built double Couette strain rate controlled rheometer at flux densities ranging from 0.2 to ~0.8 T. The yield stresses of 33 and 40 vol% grade A were 100 +/- 3 and 124 +/- 3 kPa, respectively at 0.8 +/- 0.1 T. The yield stress values of MR fluids based on finer particles (grade B) were consistently smaller. For example, the yield stresses for 33 and 40 vol% grade B based MR fluid were 80 +/- 8 and 102 +/- 2 kPa, respectively at 0.8 +/- 0.1 T. The yield stresses at the flux density approaching magnetic saturation in particles (B ~ 0.8T) were found to increase quadratically with the saturation magnetization (?0Ms) of the dispersed magnetic phase. This is in good agreement with the analytical models of uniformly saturated particle chains developed by Ginder and co-workers. The results presented here show that the decrease in yield stress for finer particle based MR fluids is due to the relatively smaller magnetization of the finer particles.

  16. 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.

  17. Structural Rheology of the Smectic Phase

    Directory of Open Access Journals (Sweden)

    Shuji Fujii

    2014-07-01

    Full Text Available In this review article, we discuss the rheological properties of the thermotropic smectic liquid crystal 8CB with focal conic domains (FCDs from the viewpoint of structural rheology. It is known that the unbinding of the dislocation loops in the smectic phase drives the smectic-nematic transition. Here we discuss how the unbinding of the dislocation loops affects the evolution of the FCD size, linear and nonlinear rheological behaviors of the smectic phase. By studying the FCD formation from the perpendicularly oriented smectic layers, we also argue that dislocations play a key role in the structural development in layered systems. Furthermore, similarities in the rheological behavior between the FCDs in the smectic phase and the onion structures in the lyotropic lamellar phase suggest that these systems share a common physical origin for the elasticity.

  18. Rheologic characteristics experiment of coal slurry

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xue-yi; Fu Jian-zhuo; Cui Yu-jiang; Wu Miao [China University of Mining & Technology, Beijing (China). School of Mechanical Electronic & Information

    2006-07-01

    Slime, waste from cleaning and processing coal, has enough application value as a low calorific fuel because of its largish quantity of heat. Nowadays, the best approach to utilize slime is to transport it into boilers for combustion and power generation through the long-distance pipeline. As high density and viscosity material, slime is difficult to be transported through the pipeline. Research on the rheological characteristics of the slime is very important for studying pipeline transportation. The physical characteristics of slime and the instruments applied in experiment are introduced. According to the rheological characteristics curves and viscosity curves obtained through systematic test on slime (with a mass concentration of 55%-75%) its rheologic type was ascertained, the equations were deduced. The study of the rheological characteristics of slime can offer the basic parameters for optimization design of slime pipeline transportation equipment. 8 refs., 5 figs., 2 tabs.

  19. Rheology of a sonofluidized granular packing

    OpenAIRE

    Caballero-Robledo, G. A.; Clément, E

    2009-01-01

    We report experimental measurements on the rheology of a dry granular material under a weak level of vibration generated by sound injection. First, we measure the drag force exerted on a wire moving in the bulk. We show that when the driving vibration energy is increased, the effective rheology changes drastically: going from a non-linear dynamical friction behavior - weakly increasing with the velocity- up to a linear force-velocity regime. We present a simple heuristic model to account for ...

  20. Rheological characterization of media containing Penicillium chrysogenum

    DEFF Research Database (Denmark)

    Pedersen, Annemarie Gade; Bundgaard-Nielsen, Mikael; Nielsen, Jens; Villadsen, John; Hassager, Ole

    1993-01-01

    Samples from fed-batch fermentations of Penicillium chrysogenum on complex medium are rheologically characterized. The behavior is well described by a power law model for which the parameters are estimates. Furthermore, two types of model media are characterized and compared with the real fermentation samples. Xanthan solutions are found to mimic the rheological properties of the filamentous fungi much better than carboxymethyl cellulose (CMC) solutions.

  1. Conductance of strong electrolytes

    International Nuclear Information System (INIS)

    An introduction to the theory of strong electrolytes is presented. The derivation of Onsager's limiting law is presented and five empirical and theoretical conductance equations are given. These are compared with measurements by Chiu and Fouss on KCl and NaCl. APL programs for computing the conductivity from the different equations are listed

  2. Structure, Ion Transport, and Rheology of Nanoparticle Salts

    KAUST Repository

    Wen, Yu Ho

    2014-07-08

    Above a critical surface chemistry-dependent particle loading associated with nanoscale interparticle spacing, ligand-ligand interactions-both electrostatic and steric-come into play and govern the structure and dynamics of charged oligomer-functionalized nanoparticle suspensions. We report in particular on the structure, ion transport, and rheology of suspensions of nanoparticle salts created by cofunctionalization of silica particles with tethered sulfonate salts and oligomers. Dispersion of the hairy ionic particles into medium and high dielectric constant liquids yields electrolytes with unique structure and transport properties. We find that electrostatic repulsion imparted by ion dissociation can be tuned to control the dispersion state and rheology through counterion size (i.e., Li+, Na+, and K+) and dielectric properties of the dispersing medium. Analysis of small-angle X-ray scattering (SAXS) structure factors and the mechanical modulus shows that when the interparticle spacing approaches nanometer dimensions, weakly entangled anchored ligands experience strong and long-lived topological constraints analogous to those normally found in well-entangled polymeric fluids. This finding provides insight into the molecular origins of the surprisingly similar rubbery plateau moduli observed in hairy nanoparticle suspensions and entangled polymers of the same chemistry as the tethered ligands. Additionally, we find that a time-composition superposition (TCS) principle exists for the suspensions, which can be used to substantially extend the observation time over which dynamics are observed in jammed, soft glassy suspensions. Application of TCS reveals dynamical similarities between the suspensions and entangled solutions of linear polymer chains; i.e., a hairy particle trapped in a cage appears to exhibit analogous dynamics to a long polymer chain confined to a tube. © 2014 American Chemical Society.

  3. Investigation of interfacial rheology & foam stability.

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-05-01

    The rheology at gas-liquid interfaces strongly influences the stability and dynamics of foams and emulsions. Several experimental techniques are employed to characterize the rheology at liquid-gas interfaces with an emphasis on the non-Newtonian behavior of surfactant-laden interfaces. The focus is to relate the interfacial rheology to the foamability and foam stability of various aqueous systems. An interfacial stress rheometer (ISR) is used to measure the steady and dynamic rheology by applying an external magnetic field to actuate a magnetic needle suspended at the interface. Results are compared with those from a double wall ring attachment to a rotational rheometer (TA Instruments AR-G2). Micro-interfacial rheology (MIR) is also performed using optical tweezers to manipulate suspended microparticle probes at the interface to investigate the steady and dynamic rheology. Additionally, a surface dilatational rheometer (SDR) is used to periodically oscillate the volume of a pendant drop or buoyant bubble. Applying the Young-Laplace equation to the drop shape, a time-dependent surface tension can be calculated and used to determine the effective dilatational viscosity of an interface. Using the ISR, double wall ring, SDR, and MIR, a wide range of sensitivity in surface forces (fN to nN) can be explored as each experimental method has different sensitivities. Measurements will be compared to foam stability.

  4. Rheology of welding: Field constraints

    Science.gov (United States)

    Russell, K.; Quane, S.

    2003-04-01

    Pyroclastic deposits emplaced at high temperature and having sufficient thickness become welded via sintering, compaction and flattening of hot glassy particles. The welding process is attended by pronounced changes in the physical properties of the deposit and welding intensity can be tracked by measuring the density, porosity, fabric or strength of samples. Ultimately, the intensity of welding reflects the aggregate effects of load and residence time at temperatures above the glass transition temperature (Tg). This results in welding intensity varying with stratigraphic depth; vertical sections through welded ignimbrite deposits commonly show maximum (e.g., density) or minimum (porosity) values in physical properties in the lower half (30--40% above the base) of the unit. Here we explore the extent to which these data, serving as proxies for strain, can be used constrain the rheological properties of the pyroclastic deposit during the welding process. Our data include measurements of density, porosity, fabric and rock strength as a function of stratigraphic position for 4 sections through the Bandelier tuff, New Mexico. These profiles record changes in physical properties and, thus, map the cumulative strain associated with welding as a function of depth (load). We have used simple conductive heat transfer models to estimate cooling curves for each sample. Essentially, these curves provide the residence time within the "welding window" for each sample. The curves are dependent on sample position, thickness of ignimbrite, emplacement temperature and the glass transition temperature of the material. The unknowns in the problem are a number of physical constants in a generalized power-law relationship between strain-rate (?') and stress (?) for steady-state creep at constant load: ?' = A ?^n e[-Q/R T]. Specifically, we adopt an inverse-model approach whereby the observations on the natural material are used to constrain the pre-exponential constant (A), stress factor (n) and the activation energy (Q) governing the compaction and welding of the ignimbrite. The inversion of the natural dataset for these parameters provides us with a constitutive relationship for the rheology of pyroclastic material as a function of temperature, load and strain rate and can be used to investigate generalities concerning: a) the mechanisms of welding, b) the timescales of welding, or d) the distributions of welding in pyroclastic deposits.

  5. Gel polymer electrolytes for batteries

    Science.gov (United States)

    Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

    2014-11-18

    Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

  6. Electrolytic cell with reference electrode

    Science.gov (United States)

    Kessie, Robert W. (Naperville, IL)

    1989-01-01

    A reference electrode device is provided for a high temperature electrolytic cell used to electrolytically recover uranium from spent reactor fuel dissolved in an anode pool, the device having a glass tube to enclose the electrode and electrolyte and serve as a conductive membrane with the cell electrolyte, and an outer metal tube about the glass tube to serve as a shield and basket for any glass sections broken by handling of the tube to prevent their contact with the anode pool, the metal tube having perforations to provide access between the bulk of the cell electrolyte and glass membrane.

  7. Comportamento reológico de suspensões aquosas de cromito de lantânio / Rheological behaviour of lanthanum chromite aqueous suspension

    Scientific Electronic Library Online (English)

    L. F. G., Setz; I., Santacruz; M. T., Colomer; R., Moreno; S. R. H., Mello-Castanho.

    2011-06-01

    Full Text Available O cromito de lantânio (LaCrO3) é o material mais estudado para a produção de interconectores para células a combustível de óxido sólido (SOFC). Devido a complexidade das microestruturas e geometrias das SOFCs, freqüentemente são necessárias, técnicas de processamento coloidal, os quais têm recebido [...] maior atenção nos últimos anos por permitirem a obtenção de partes complexas com microestrutura controlada e reprodutíveis. Nos últimos anos, muito esforço tem sido direcionado ao processamento dos eletrólitos e eletrodos, mas aos componentes como o interconector, pouca atenção tem sido dada. Este artigo apresenta o estudo reológico e de conformação em moldes de gesso do cromito de lantânio para a produção de interconectores para SOFCs. A composição La0,80Sr0,20Cr0,92Co0,08O3, obtida por reação de combustão, foi utilizada. As suspensões aquosas foram preparadas com conteúdo de sólidos variando de 8 a 17,5% vol. utilizando-se, poliacrilato de amônia (PAA) como polieletrólito/dispersante e hidróxido de tetrametilamônio (HTMA) como provedor de alcalinidade. A influência da concentração dos aditivos e o tempo em moinho de bolas foram estudados. Os resultados indicam que o tempo 24 h de homogeneização em moinho de bolas, com 3% e 1%, em massa, de PAA e HTMA respectivamente, proporcionam as melhores condições para colagem em moldes de gesso, sendo possível obter peças após sinterização com densidades relativas elevadas. Abstract in english Lanthanum chromite (LaCrO3) is the most studied material for SOFC's interconnectors' production. The complexity of microstructures and geometries of SOFC devices often requires the use of colloidal processing techniques, which have received increased attention in the last years for obtaining complex [...] parts with controlled microstructure and high reliability. Much effort has been devoted to the processing of electrodes and electrolytes but the other layers, such as that of interconnecting material, have received scarce attention. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La0.80Sr0.20Cr0.92Co0.08O3 was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as polyelectrolyte/dispersant and tetramethylammonium hydroxide (TMAH) to assure basic pH. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.%, of PAA and TMAH respectively, yielded the best conditions for successful slip casting, leading to relatively dense sintered materials.

  8. Comportamento reológico de suspensões aquosas de cromito de lantânio Rheological behaviour of lanthanum chromite aqueous suspension

    Directory of Open Access Journals (Sweden)

    L. F. G. Setz

    2011-06-01

    Full Text Available O cromito de lantânio (LaCrO3 é o material mais estudado para a produção de interconectores para células a combustível de ??xido sólido (SOFC. Devido a complexidade das microestruturas e geometrias das SOFCs, freqüentemente são necessárias, técnicas de processamento coloidal, os quais têm recebido maior atenção nos últimos anos por permitirem a obtenção de partes complexas com microestrutura controlada e reprodutíveis. Nos últimos anos, muito esforço tem sido direcionado ao processamento dos eletrólitos e eletrodos, mas aos componentes como o interconector, pouca atenção tem sido dada. Este artigo apresenta o estudo reológico e de conformação em moldes de gesso do cromito de lantânio para a produção de interconectores para SOFCs. A composição La0,80Sr0,20Cr0,92Co0,08O3, obtida por reação de combustão, foi utilizada. As suspensões aquosas foram preparadas com conteúdo de sólidos variando de 8 a 17,5% vol. utilizando-se, poliacrilato de amônia (PAA como polieletrólito/dispersante e hidróxido de tetrametilamônio (HTMA como provedor de alcalinidade. A influência da concentração dos aditivos e o tempo em moinho de bolas foram estudados. Os resultados indicam que o tempo 24 h de homogeneização em moinho de bolas, com 3% e 1%, em massa, de PAA e HTMA respectivamente, proporcionam as melhores condições para colagem em moldes de gesso, sendo possível obter peças após sinterização com densidades relativas elevadas.Lanthanum chromite (LaCrO3 is the most studied material for SOFC's interconnectors' production. The complexity of microstructures and geometries of SOFC devices often requires the use of colloidal processing techniques, which have received increased attention in the last years for obtaining complex parts with controlled microstructure and high reliability. Much effort has been devoted to the processing of electrodes and electrolytes but the other layers, such as that of interconnecting material, have received scarce attention. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La0.80Sr0.20Cr0.92Co0.08O3 was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA as polyelectrolyte/dispersant and tetramethylammonium hydroxide (TMAH to assure basic pH. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.%, of PAA and TMAH respectively, yielded the best conditions for successful slip casting, leading to relatively dense sintered materials.

  9. Rheology of tetraphenylborate precipitate slurry

    International Nuclear Information System (INIS)

    The rheological properties of tetraphenylborate precipitate slurry were determined. This nonradioactive slurry simulates the radioactive tetraphenylborate precipitate generated at the Savannah River Plant by the In-Tank Precipitation Process. The data obtained in this study was applied in the design of slurry pumps, transfer pumps, transfer lines, and vessel agitation for the Defense Waste Processing Facility and other High Level Waste treatment projects. The precipitate slurry behaves as a Bingham plastic. The yield stress is directly proportional to the concentration of insoluble solids over the range of concentrations studied. The consistency is also a linear function of insoluble solids over the same concentration range. Neither the yield stress nor the consistency was observed to be affected by the presence of the soluble solids. Temperature effects on flow properties of the slurry were also examined: the yield stress is inversely proportional to temperature, but the consistency of the slurry is independent of temperature. No significant time-dependent effects were found. 4 refs., 4 figs., 3 tabs

  10. Coprecipitation synthesis and characterization of La0.8Sr0.2Ga(0.8-x)Mg0.2Co(x)O2.8 for intermediate temperature solid oxide fuel cell electrolytes.

    Science.gov (United States)

    Lee, Jin Goo; Yoon, Hyon Hee

    2012-01-01

    La0.8Sr0.2Ga(0.8-x)Mg0.2CO(x)O2.8 (LSGMC) electrolyte powders containing different amount of Co (0 < or = x < or = 0.15) were prepared by ammonium carbonate coprecipitation method. The precursors, the calcined powders, and the sintered pellets were characterized by thermogravimetry/differential thermal analysis, X-ray diffractometry, scanning electron microscopy, and an impedance analyzer. The thermal decomposition of the LSGMC precursors was completed at around 900 degrees C with the total weight loss of approximately 35%. The LSGMC samples sintered at 1350 degrees C consisted of the pure perovskite structure. The ionic conductivity was significantly improved by Co doping for the Ga-site of the La0.8Sr0.2Ga0.8Mg0.2O2.8 (LSGM) electrolytes. The ionic conductivity of LSGMC (x = 0.1) exhibited the highest values of 1.6 x 10(-1) S cm(-1) at 700 degrees C with an activation energy for the oxide-ion conduction of 0.29 eV. The results of this study indicated that the Co-doped LSGM electrolytes had excellent properties for use as an electrolyte in an IT-SOFC and the ammonium carbonate coprecipitation process could be employed as the efficient method for the preparation of the Co-doped LSGM electrolytes. PMID:22524055

  11. 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

  12. Nanoporous hybrid electrolytes

    KAUST Repository

    Schaefer, Jennifer L.

    2011-01-01

    Oligomer-suspended SiO2-polyethylene glycol nanoparticles are studied as porous media electrolytes. At SiO2 volume fractions, , bracketing a critical value y ≈ 0.29, the suspensions jam and their mechanical modulus increase by more than seven orders. For >y, the mean pore diameter is close to the anion size, yet the ionic conductivity remains surprisingly high and can be understood, at all , using a simple effective medium model proposed by Maxwell. SiO 2-polyethylene glycol hybrid electrolytes are also reported to manifest attractive electrochemical stability windows (0.3-6.3 V) and to reach a steady-state interfacial impedance when in contact with metallic lithium. © 2010 The Royal Society of Chemistry.

  13. Gel Polymer Electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Nová?ek, T.; Sedla?íková, M.; Vondrák, Ji?í

    Brno : University of Technology Brno, 2002, s. 42-1-42-2. ISBN 80-214-2082-0. [Advanced Batteries and Accumulators /3./. Brno (CZ), 16.06.2002-20.06.2002] R&D Projects: GA AV ?R IAA4032002; GA ?R GA104/02/0731 Institutional research plan: CEZ:AV0Z4032918 Keywords : gel polymer * electrolytes * polymer ization Subject RIV: CA - Inorganic Chemistry

  14. 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.

  15. Aprotic gel polymer electrolytes.

    Czech Academy of Sciences Publication Activity Database

    Vondrák, Ji?í; Sedla?íková, M.; Krejza, O.

    Brno : University of Technology Brno, 2008, s. 71-72. ISBN 978-80-214-3659-6. [International Conference Advanced Batteries and Accumulators /9./. Brno (CZ), 29.06.2008-03.07.2008] R&D Projects: GA ?R(CZ) GA104/06/1471; GA AV ?R(CZ) KJB208130604 Institutional research plan: CEZ:AV0Z40320502 Keywords : gel polymer electrolytes Subject RIV: CA - Inorganic Chemistry

  16. 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 (hybrid vehicles that are more economically viable to operate as oil prices continue to rise. Existing organic based electrolytes used in 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

  17. 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.

  18. 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.

  19. 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 concentric cylinder rheometers and tube rheometers provides the best data system for characterizing the rheology of a vitrification slurry

  20. Dilational surface rheology of polymer solutions

    Science.gov (United States)

    Noskov, B. A.; Bykov, A. G.

    2015-06-01

    The review concerns main achievements in dilational rheology of polymer adsorption films at the gas/liquid interfaces reported in the last fifteen years. The theoretical foundations of methods of surface rheology and the key results obtained in studies of solutions of amphiphilic nonionic polymers, polyelectrolytes, proteins and their complexes with low-molecular-mass surfactants are discussed. Interest in the surface dilational rheology is mainly caused by a small number of available experimental methods for investigation of the surface of liquids, by the fact that traditional methods of measurement of the surface tension that are widely used in studies of solutions of low-molecular-mass surfactants provide little information when applied to polymer solutions owing to very slow establishment of equilibrium as well as by weak dependence of the surface tension on the polymer concentration. Progress in the surface rheology is driven by the recent studies of the stability of foams and emulsions that demonstrated a key role of the dilational surface rheological properties in the dynamics of liquid-phase disperse systems. The bibliography includes 191 references.

  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. Extensional rheology of active suspensions

    Science.gov (United States)

    Saintillan, David

    2010-05-01

    A simple model is presented for the effective extensional rheology of a dilute suspension of active particles, such as self-propelled microswimmers, extending previous classical studies on suspensions of passive rodlike particles. Neglecting particle-particle hydrodynamic interactions, we characterize the configuration of the suspension by an orientation distribution, which satisfies a Fokker-Planck equation including the effects of an external flow field and of rotary diffusion. Knowledge of this orientation distribution then allows the determination of the particle extra stress as a configurational average of the force dipoles exerted by the particles on the fluid, which involve contributions from the imposed flow, rotary diffusion, and the permanent dipoles resulting from activity. Analytical expressions are obtained for the stress tensor in uniaxial extensional and compressional flows, as well as in planar extensional flow. In all types of flows, the effective viscosity is found to increase as a result of activity in suspensions of head-actuated swimmers (pullers) and to decrease in suspensions of tail-actuated swimmers (pushers). In the latter case, a negative particle viscosity is found to occur in weak flows. In planar extensional flow, we also characterize normal stresses, which are enhanced by activity in suspensions of pullers but reduced in suspensions of pushers. Finally, an energetic interpretation of the seemingly unphysical decrease in viscosity predicted in suspensions of pushers is proposed, where the decrease is explained as a consequence of the active power input generated by the swimming particles and is shown not to be directly related to viscous dissipative processes.

  3. Fault rheology beyond frictional melting.

    Science.gov (United States)

    Lavallée, Yan; Hirose, Takehiro; Kendrick, Jackie E; Hess, Kai-Uwe; Dingwell, Donald B

    2015-07-28

    During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or "pseudotachylytes." It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics. PMID:26124123

  4. The debris-flow rheology myth

    Science.gov (United States)

    Iverson, R.M.

    2003-01-01

    Models that employ a fixed rheology cannot yield accurate interpretations or predictions of debris-flow motion, because the evolving behavior of debris flows is too complex to be represented by any rheological equation that uniquely relates stress and strain rate. Field observations and experimental data indicate that debris behavior can vary from nearly rigid to highly fluid as a consequence of temporal and spatial variations in pore-fluid pressure and mixture agitation. Moreover, behavior can vary if debris composition changes as a result of grain-size segregation and gain or loss of solid and fluid constituents in transit. An alternative to fixed-rheology models is provided by a Coulomb mixture theory model, which can represent variable interactions of solid and fluid constituents in heterogeneous debris-flow surges with high-friction, coarse-grained heads and low-friction, liquefied tails. ?? 2003 Millpress.

  5. Rheological properties of alumina injection feedstocks

    Directory of Open Access Journals (Sweden)

    Vivian Alexandra Krauss

    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 < 0, which can lead to the 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.

  6. 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.

  7. Rheological Characterization Of Nano-Composite Hydrogels

    Science.gov (United States)

    Lombardi, Jack

    Engineered Polymer hydrogels and hydrogels from Bio macromolecules have visco-elastic properties that can be measured using Oscillatory Shear Rheology. Manipulation and measurement of physical properties in gels including F-127 Pluronic Block Co-Polymer and Poly(N-isopropylacrylamide)-Clay are shown through OSR by addition of salts, clays and glucose at physiological levels. Rheological analysis of f-127 illustrates changes in G' reduction with phase transition temperature. Measurements also indicate physical changes due to the aforementioned additives vary as a function of the gel physical and chemical structure. In particular, non-enzymatic glycation is shown to change the modulus of elasticity in both of the gels tested. Rheological analysis is also interpreted to produce a reduction In gel mesh size in the PNIPA -clay gels due to a possible co-solvency between phases of varying degrees of hydration.

  8. Numerical simulation of the rheological behavior of fresh concrete

    OpenAIRE

    Shyshko, Sergiy

    2014-01-01

    This thesis reports recent numerical investigation of the rheological behavior of fresh concrete using the Distinct Element Method (DEM). Some relevant questions of the concrete rheology e.g. the influence of the concrete composition on the rheological behavior of the fresh concrete, the experimental determination of the Bingham rheological constants as well as the use of these constants in the numerical simulation were discussed thoroughly. An important topic of the performed investigation w...

  9. Rheology of the lithosphere: selected topics.

    Science.gov (United States)

    Kirby, S.H.; Kronenberg, A.K.

    1987-01-01

    Reviews recent results concerning the rheology of the lithosphere with special attention to the following topics: 1) the flexure of the oceanic lithosphere, 2) deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins, 3) the rheological stratification of the continents, 4) strain localization and shear zone development, and 5) strain-induced crystallographic preferred orientations and anisotropies in body-wave velocities. We conclude with a section citing the 1983-1986 rock mechanics literature by category.-Authors

  10. 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)

  11. Rheological behavior of coal-water slurry

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, S.K.; Senapati, P.K.; Panda, D. [Regional Research Lab., Orissa (India). CPAF Division

    2002-02-01

    The rheological behavior of some Indian coal-water slurries (CWS) was investigated using a HAAKE RV30 viscometer. The objective was to study the effect of solid concentration, ash content, pH, and temperature on the rheology of CWS. It was found that CWS exhibits pseudoplastic behavior. The apparent viscosity varies with the amount of coal in the slurry, pH, and temperature, which is the highest around pH 6 and the lowest near pH 8. The effect of temperature on the viscosity could be described using an Arrhenius type of relation.

  12. 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.

  13. Electrolytic oxide reduction system

    Energy Technology Data Exchange (ETDEWEB)

    Wiedmeyer, Stanley G; Barnes, Laurel A; Williamson, Mark A; Willit, James L; Berger, John F

    2015-04-28

    An electrolytic oxide reduction system according to a non-limiting embodiment of the present invention may include a plurality of anode assemblies, a plurality of cathode assemblies, and a lift system configured to engage the anode and cathode assemblies. The cathode assemblies may be alternately arranged with the anode assemblies such that each cathode assembly is flanked by two anode assemblies. The lift system may be configured to selectively engage the anode and cathode assemblies so as to allow the simultaneous lifting of any combination of the anode and cathode assemblies (whether adjacent or non-adjacent).

  14. Electrolytic titanium production

    Energy Technology Data Exchange (ETDEWEB)

    Ginatta, M.; Berruti, R.; Orsello, G.; Semeraro, G.; Nidola, G. [GTT, Ginatta Torino Titanium (Italy)

    1992-12-31

    The Ginatta electrolytic plant was specifically designed and constructed for the production of titanium. Development stages that led to the construction of the electrowinning plant were reviewed. Electrochemical concepts and engineering criteria were outlined. Continuous steady state production of titanium crystals from the extraction compartments are obtained by supplying tetrachloride to the dissolution compartment. The cell electrodes are supplied with direct current from standard rectifiers. The equipment and the molten salt cells are operated by an aqueous tank house. The design is cost effective on an industrial scale because of significantly lower capital and operating costs. 13 refs., 5 figs.

  15. Rheological behavior study of a clay-polymer mixture: effects of the polymer addition; Etude du comportement rheologique de melanges argiles - polymeres. Effets de l'ajout de polymeres

    Energy Technology Data Exchange (ETDEWEB)

    Benchabane, A

    2006-11-15

    The aim of the present work is to establish a bibliographical synthesis on the microstructure, the colloidal and rheological characterization of bentonite suspensions with and without polymer/surfactant addition; to lead to a rheological characterization of clay-additive mixtures and to understand the interaction between the clay particles and polymer/surfactants. Different experimental measurements: rheology, particle sizing, and x-ray diffraction were used to study the rheological character of the water-bentonite-anionic additive mixtures (CMC, SDS, xanthane) as well as the nature of the particle-particle interactions and particle-additive. The modeling part led to the adoption of Tiu and Boger's model to predict the thixotropy of the bentonite suspensions without additive. Thus, a new model is proposed with physical parameters for a better correlation of the rheological behavior of the various studied mixtures. (author)

  16. An electrolyte CPA equation of state for mixed solvent electrolytes

    DEFF Research Database (Denmark)

    Maribo-Mogensen, Bjørn; Thomsen, Kaj; Kontogeorgis, Georgios M.

    2015-01-01

    predictive capabilities could be improved through the development of an electrolyte equation of state. In this work, the Cubic Plus Association (CPA) Equation of State is extended to handle mixtures containing electrolytes by including the electrostatic contributions from the Debye-Hückel and Born terms...

  17. Electrolytic pretreatment of urine

    Science.gov (United States)

    1977-01-01

    Electrolysis has been under evaluation for several years as a process to pretreat urine for ultimate recovery of potable water in manned spacecraft applications. The conclusions that were drawn from this investigation are the following: (1) A platinum alloy containing 10 percent rhodium has been shown to be an effective, corrosion-resistant anode material for the electrolytic pretreatment of urine. Black platinum has been found to be suitable as a cathode material. (2) The mechanism of the reactions occurring during the electrolysis of urine is two-stage: (a) a total Kjeldahl nitrogen and total organic carbon (TOC) removal in the first stage is the result of electrochemical oxidation of urea to CO2, H2O, and ammonia followed by chloride interaction to produce N2 from ammonia, (b) after the urea has been essentially removed and the chloride ions have no more ammonia to interact with, the chloride ions start to oxidize to higher valence states, thus producing perchlorates. (3) Formation of perchlorates can be suppressed by high/low current operation, elevated temperature, and pH adjustment. (4) UV-radiation showed promise in assisting electrolytic TOC removal in beaker tests, but was not substantiated in limited single cell testing. This may have been due to non-optimum configurations of the single cell test rig and the light source.

  18. Rheology and Fourier-transform rheology on water-based systems

    OpenAIRE

    Klein, Christopher

    2005-01-01

    The influence of shear fields on water-based systems was investigated within this thesis. The non-linear rheological behaviour of spherical and rod-like particles was examined with Fourier-Transform rheology under LAOS conditions. As a model system for spherical particles two different kinds of polystyrene dispersions, with a solid content higher than 0.3 each, were synthesised within this work. Due to the differences in polydispersity and Debye-length, differences were also found in the rheo...

  19. Fluid and electrolyte alterations during prolonged hypokinesia

    Science.gov (United States)

    Tsiamis, Costas B.

    2008-05-01

    The physiological and biochemical systems that regulate the level of each electrolyte in blood and other endogenous fluids, and the balance between the consumption and loss of fluid and electrolytes and the total fluid and electrolyte content of the body are significantly affected during hypokinesia (HK; diminished movement). Among the known effects of HK, the fluid and electrolyte deficiency has drawn a great interest due to the higher fluid and electrolyte deficiency with higher than lower fluid and electrolyte consumption. The impossibility of the body to use fluid and electrolytes, after the fluid and electrolyte deficiency has been established, has drawn the greatest interest. The fluid shifting to the thoracic region and the daily body rehydration are considered as the most effective methods to counteract fluid and electrolyte changes. To this end, the objective of this review was to report some of the findings in the fluid and electrolyte deficiency and fluid and electrolyte loss with fluid and electrolyte deficiency during prolonged HK.

  20. RHEOLOGY OF CONCENTRATED SOLUTIONS OF HYPERBRANCHED POLYESTERS

    Science.gov (United States)

    The solution rheology of different generations of hyperbranched polyesters in N-methyl-2- pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amido...

  1. Rheological characterization of media containing Penicillium chrysogenum

    DEFF Research Database (Denmark)

    Pedersen, Annemarie Gade; Bundgaard-Nielsen, Mikael; Nielsen, Jens; Villadsen, John; Hassager, Ole

    1993-01-01

    Samples from fed-batch fermentations of Penicillium chrysogenum on complex medium are rheologically characterized. The behavior is well described by a power law model for which the parameters are estimates. Furthermore, two types of model media are characterized and compared with the real ferment...

  2. 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.

  3. 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

  4. From Reactor to Rheology in LDPE Modeling

    International Nuclear Information System (INIS)

    In recent years the association between molecular structure and linear rheology has been established and well-understood through the tube concept and its extensions for well-characterized materials (e.g. McLeish, Adv. Phys. 2002). However, for industrial branched polymeric material at processing conditions this piece of information is missing. A large number of phenomenological models have been developed to describe the nonlinear response of polymers. But none of these models takes into account the underlying molecular structure, leading to a fitting procedure with arbitrary fitting parameters. The goal of applied molecular rheology is a predictive scheme that runs in its entirety from the molecular structure from the reactor to the non-linear rheology of the resin. In our approach, we use a model for the industrial reactor to explicitly generate the molecular structure ensemble of LDPE's, (Tobita, J. Polym. Sci. B 2001), which are consistent with the analytical information. We calculate the linear rheology of the LDPE ensemble with the use of a tube model for branched polymers (Das et al., J. Rheol. 2006). We then, separate the contribution of the stress decay to a large number of pompom modes (McLeish et al., J. Rheol. 1998 and Inkson et al., J. Rheol. 1999) with the stretch time and the priority variables corresponding to the actual ensemble of molecules involved. This multimode pompom model allows us to predict the nonlinear properties without any fitting parameter. We present and analyze our results in comparison with experimental data on industrial materials

  5. The rheological properties of different GNPs

    Directory of Open Access Journals (Sweden)

    Abdelhalim Mohamed Anwar K

    2012-01-01

    Full Text Available Abstract Background Rheological analysis can be employed as a sensitive tool in predicting the physical properties of gold nanoparticles (GNPs. Understanding the rheological properties of GNPs can help to develop a better therapeutic cancer product, since these physical properties often link material formulation and processing stages with the ultimate end use. The rheological properties of GNPs have not been previously documented. The present study attempted to characterize the rheological properties of different sizes of GNPs at: 1 fixed temperature and wide range of shear rates; 2 varied temperature and fixed shear rate. Methods 10, 20 and 50 nm GNPs was used in this study. Several rheological parameters of GNPs such as viscosity, torque%, shear stress and shear rate were evaluated using Brookfield LVDV-III Programmable rheometer supplied with temperature bath and controlled by a computer. To measure fluid properties (viscosity as function of shear rate, e.g., to determine whether the flow is Newtonian or non-Newtonian flow behaviour, and viscoelasticity (viscosity as function of temperature, rheological parameters were firstly measured at starting temperature of 37°C and wide range of shear rates from 375 to 1875 s-1, and secondly at a gradual increase of temperature from 37 to 42°C and fixed shear rate of 1875 s-1. Results The 10, 20 and 50 nm GNPs showed mean size of 9.45 ± 1.33 nm, 20.18 ± 1.80 nm, and 50 nm GNPs, respectively. The 10 and 20 nm GNPs showed spherical morphology while 50 nm GNPs showed hexagonal morphology using the transmission electron microscope (TEM. The relation between viscosity (cp and shear rate (s-1 for 10, 20 and 50 nm GNPs at a temperature of 37°C showed non-Newtonian behaviour. Although the relationship between SS (dyne/cm2 and SR (s-1 for 10, 20 and 50 nm GNPs was linearly related however their fluid properties showed non-Newtonian behaviour. Conclusions The torque%, viscosity (cp and SS (dyne/cm2 of all GNP sizes decreased with increasing the temperature and with decreasing the GNP size (for each fixed temperature value. For each shear rate value, the viscosity of all GNPs decreased with decreasing the GNP size. This study demonstrates that the physical, dimensional and morphological changes of GNPs have effective influence on their rheological properties. To understand and categorize the role of GNPs in drug delivery and cancer therapy, GNPs of varying size, number of particles, shape and surface should be taken into consideration. Moreover, further additional in vivo studies after administration of GNPs in rats should be performed to support this hypothesis.

  6. Gelled Electrolytes For Lithium Batteries

    Science.gov (United States)

    Nagasubramanian, Ganesan; Attia, Alan; Halpert, Gerald

    1993-01-01

    Gelled polymer electrolyte consists of polyacrylonitrile (PAN), LiBF4, and propylene carbonate (PC). Thin films of electrolyte found to exhibit stable bulk conductivities of order of 10 to the negative 3rd power S/cm at room temperature. Used in thinfilm rechargeable lithium batteries having energy densities near 150 W h/kg.

  7. Electrodecontamination using a basic electrolyte

    International Nuclear Information System (INIS)

    A decontamination procedure for stainless steel is described that has the following advantages: rapid decontamination, one minute of time to reach nonretrievable level; easy to separate contamination by filtration; contamination is easy to recover in nitric acid; the electrolyte has an extended life - can be reused; and the waste generated from spent electrolyte is compatible with Rocky Flats waste processing

  8. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

    DEFF Research Database (Denmark)

    2001-01-01

    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...

  9. Electrolytes for rechargeable lithium batteries

    International Nuclear Information System (INIS)

    There is growing interest in high specific energy lithium rechargeable batteries with improved discharge/charge cycles. Some of the promising battery systems under development are Li/CoO2, Li/V2O5 and Li/MnO2. A major factor that controls the specific performance of these batteries is the electrolyte. Recent advances made in the liquid electrolyte area for lithium high energy cathode systems are reviewed. Experimental work on the processing of solid thin film polymer electrolytes using plasticizers such as polyethylene glycol dimethoxy ether (PEGDME) and the properties such as conductivity and differential scanning calorimetry of polymer film electrolytes are presented. The advantages and the disadvantages of polymer thin film electrolytes are discussed

  10. All-solid-state polymer electrolyte with plastic crystal materials for rechargeable lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Li-Zhen [School of Materials Science and Engineering, University of Science and Technology Beijing, 100083 Beijing (China); Wang, Xiao-Liang [Department of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Tsinghua University, 100084 Beijing (China); Long, Fei [Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, Ministry of Education, Guilin University of Technology, 541004 Guilin (China)

    2009-04-01

    In this paper, we report the synthesis and properties of a series of composite polymer electrolytes formed by dispersion of a non-ionic organic plastic material succinonitrile (SN) into poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) complexed with four kinds of lithium salts. The addition of SN greatly enhances ionic conductivities of the electrolytes which is due to the high polarity and diffusivity of SN. The integrity of the plastic-crystalline phase is kept at low temperature range in polymer electrolytes. The high solubility of SN on Li salts is observed by Fourier transform infrared (FTIR) spectra measurement, thus could lead to enhanced lithium-ion transference number. The battery performances of composite polymer electrolytes at different temperatures are tested and the results are comparable to that of the pure plastic crystal electrolytes. (author)

  11. 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.

  12. Photopolymerized Electrolytes For Electrochromic Devices

    Science.gov (United States)

    Cogan, Stuart; Rauh, R. David

    1994-01-01

    Thin ion-conducting electrolyte films for use in electrochromic devices now fabricated relatively easily and quickly with any of class of improved formulations containing ultraviolet-polymerizable components. Formulations are liquids in their monomeric forms and self-supporting, transparent solids in their polymeric forms. Thin solid electrolytes form quickly and easily between electrode-bearing substrates. Film thus polymerized acts not only as solid electrolyte but also as glue holding laminate together: feature simplifies fabrication by reducing need for sealants and additional mechanical supports.

  13. Electrolytic preparation of molybdenum oxides

    International Nuclear Information System (INIS)

    Dependence of molybdenum oxides electrolytic deposition from ammonium molybdate solutions on current density at different temperatures (20-80 Deg C) and solution concentrations is studied. Analysis of kinetic curves and volt-ampere characteristics of cathode process permitted ascertaining the most preferable conditions for molybdenum oxides electrolytic deposition on substrates made of stainless steel: ammonium molybdate aqueous solution saturated at 20 Deg C, current cathode density is 10-30 mA/cm2, electrolyte temperature is 75-90 Deg C

  14. 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)

  15. 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...

  16. Analytical rheology of metallocene-catalyzed polyethylenes

    Science.gov (United States)

    Shanbhag, Sachin; Takeh, Arsia

    2011-03-01

    A computational algorithm that seeks to invert the linear viscoelastic spectrum of single-site metallocene-catalyzed polyethylenes is presented. The algorithm uses a general linear rheological model of branched polymers as its underlying engine, and is based on a Bayesian formulation that transforms the inverse problem into a sampling problem. Given experimental rheological data on unknown single-site metallocene- catalyzed polyethylenes, it is able to quantitatively describe the range of values of weight-averaged molecular molecular weight, MW , and average branching density, bm , consistent with the data. The algorithm uses a Markov-chain Monte Carlo method to simulate the sampling problem. If, and when information about the molecular weight is available through supplementary experiments, such as chromatography or light scattering, it can easily be incorporated into the algorithm, as demonstrated. Financial support from NSF DMR 0953002.

  17. Rheology of fresh concretes with recycled aggregates

    OpenAIRE

    Faleschini, Flora; Jiménez Fernández, Cristian Gonzalo; Barra Bizinotto, Marilda; Aponte Hernández, Diego Fernando; Vázquez Ramonich, Enric; Pellegrino, Carlo

    2014-01-01

    The most frequently used measure of rheology is the slump test, which evaluates workability. Since this value is often operator-sensitive, a more quantitative estimate can be derived in terms of fundamental physical quantities, such as plastic viscosity and yield stress. The higher heterogeneity in terms of experimental slump measure occurs when recycled aggregate concrete (RAC) is tested. In this work, 16 recycled mixes were analysed with two aggregates proportioning methods and results were...

  18. Rheology and structural arrest of casein suspensions

    OpenAIRE

    Dahbi, Louisa; Alexander, M (Michael); Trappe, Véronique; Dhont, J. K. G.; Schurtenberger, Peter

    2010-01-01

    The rheology of milk powder suspensions is investigated up to very high concentrations, where structural arrest occurs. The main component of the milk powder investigated is casein, so that the suspensions can be regarded as casein suspensions. Four concentration regimes are identified. For effective casein volume fractions less than 0.54 the concentration dependence of the zero-shear viscosity is similar to that of hard-sphere suspensions. However, due to the elastic deformation of the casei...

  19. Linear and nonlinear rheology of wormlike micelles

    OpenAIRE

    Sood, AK; Bandyopadhyay, Ranjini; Basappa, Geetha

    2000-01-01

    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 solutio...

  20. RHEOLOGICAL STUDIES OF CONDUCTING ACRYLIC PAINT

    Directory of Open Access Journals (Sweden)

    Ziceli Cardozo Nascimento

    2015-01-01

    Full Text Available In this study the conducting acrylic paint were development by the addition of conducting filler, carbon black, in the mechanical proceed by the higher mixing condition, 10000 rpm for 5 minutes. The conducting paint were analyzed in a rotational viscosimeter at different condition of shear rate and temperature. The carbon black changes significantly the rheological paint behavior, the high amount of carbon black showed lower activation energy at 200 S-1 which is good for the application in the roll.

  1. Aggregation kinetics in electro-rheological fluids

    Science.gov (United States)

    See, Howard; Doi, Masao

    1992-05-01

    We study the aggregation kinetics of Electro-Rheological Fluid particles which interact through dipoles induced by an external electric field and experience negligible thermal motion. For a system in d-dimensions, our theoretical calculations show that the average cluster size sav increases with time t as sav?t d/d+3. This result shows good agreement with experiments in 3 dimensions, and with computer simulation in 2 dimensions.

  2. Rheology of Active-Particle Suspensions

    CERN Document Server

    Hatwalne, Y; Rao, M; Simha, R A; Hatwalne, Yashodhan; Ramaswamy, Sriram; Rao, Madan

    2004-01-01

    We study the interplay of activity, order and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration and stress fields in a suspension of active, energy-dissipating particles. We make several predictions for the rheology of such systems, which can be tested on bacterial suspensions, cell extracts with motors and filaments, or artificial machines in a fluid. The phenomena of cytoplasmic streaming, elastotaxis and active mechanosensing find natural explanations within our model.

  3. Plastisol Gelation and Fusion Rheological Aspects

    OpenAIRE

    Verdu, Jacques; ZOLLER, Agnes; Marcilla, Antonio

    2013-01-01

    This study deals with the rheological aspects of poly-vinyl chloride (PVC) plastisol gelation and fusion processes in foamable formulations. Here, such processes are simulated by temperature-programmed experiment (5 K min?1) in which complex viscosity components are continuously recorded. Nineteen samples based on a PVC-VAC (vinyl acetate 95/5) copolymer with 100 phr plasticizer have been studied, differing only by the plasticizer structure. The sample shear modulus increases continuously wit...

  4. Normal force controlled rheology for thermoreversible gels

    OpenAIRE

    Mao, Bosi; Divoux, Thibaut; Snabre, Patrick

    2015-01-01

    A wide range of thermoreversible gels are prepared by cooling down to ambient temperature hot aqueous solutions of polymers. During the sol-gel transition, such soft solids may experience a volume contraction leading to experimental issues regarding rheological measurements such as the stress-induced release of solvent, and the partial loss of contact between the sample and the shear cell. In this article, we revisit the formation of thermoreversible gels through a series of...

  5. A spectral measure estimation problem in rheology

    Science.gov (United States)

    Gzyl, Henryk; ter Horst, Enrique; Molina, German

    2015-09-01

    In this paper we consider an inverse problem appearing in rheology, consisting of determining a spectral measure over the set of relaxation times, that yields an observed collection of loss and storage moduli. Mathematically speaking, the problem consists of solving a system of Fredholm equations. To solve it, we propose an extended version of the maximum entropy method in the mean which is flexible enough to incorporate potential measurement errors.

  6. 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

  7. Frequency Dependent Rheology of Vesicular Rhyolite

    OpenAIRE

    Bagdassarov, Nikolai; Dingwell, Donald B

    1993-01-01

    Frequency dependent rheology of magmas may result from the presence of inclusions (bubbles, crystals) in the melt and/or from viscoelastic behavior of the melt itself. With the addition of deformable inclusions to a melt possessing viscoelastic properties one might expect changes in the relaxation spectrum of the shear stresses of the material (e.g., broadening of the relaxation spectrum) resulting from the viscously deformable geometry of the second phase. We have begun to investigate the ef...

  8. A rheological investigation of vesicular rhyolite

    OpenAIRE

    Bagdassarov, Nikolai; Dingwell, Donald B

    1992-01-01

    The rheology of vesiculating rhyolitic systems exerts a strong control on the transport of silicic magmas in the subvolcanic to volcanic environments. We present here an investigation of vesiculating and vesiculated rhyolites using dilatometric methods. This study examines the effect of vesicle content on the viscosity of a natural supercooled rhyolitic liquid with 0–70% vesicles. The experimental samples of rhyolitic glass are derived from fusion of a natural obsidian from Little Glass B...

  9. Structure and rheology of organoclay suspensions

    International Nuclear Information System (INIS)

    We have characterized a montmorillonite-based organoclay dispersed in three different nonaqueous solvents using a combination of x-ray scattering, small-angle neutron scattering (SANS), and ultrasmall angle neutron scattering (USANS), together with rheological measurements. Consistent with these measurements, we present a structural model for the incompletely dispersed clay as consisting of randomly oriented tactoids made of partially overlapping clay sheets, with transverse dimensions of several microns. Intersheet correlation peaks are visible in x-ray scattering, and quantitatively fit by our model structure factor. SANS and USANS together show a power law of about -3 over a wide range of wave numbers below the intersheet correlation peak. Our model relates this power law to a power law distribution of the number of locally overlapping layers in a tactoid. The rheology data show that both storage and loss moduli, as well as yield stress, scale with a power law in volume fraction of about three. Equating the gel onset composition with the overlap of randomly oriented tactoids and taking into account the large transverse dimensions of the tactoids, we predict the gel point to be at or below 0.006 volume fraction organoclay. This is consistent with the rheology data

  10. PHYSICOCHEMICAL AND RHEOLOGICAL CHARACTERIZATION OF AVOCADO OILS

    Directory of Open Access Journals (Sweden)

    Tamara de Souza Jorge

    2015-08-01

    Full Text Available Avocado oil is rich in bioactive compounds, which can improve human health by acting as an antioxidant. It may be extracted from different varieties of avocado, such as Margarida and Hass varieties, each of them with particular characteristics. Aiming to evaluate the differences between them, avocado fruits and pulps from these were analyzed according to their physicochemical characteristics. After extracted, the oils had their bioactive characteristics studied and rheological behavior determined through a rotational rheometer. They were then compared to commercial avocado oil. The fruits of Margarida variety had greater size, higher weight (664.51 g, and higher pulp yield (72.19% than Hass variety, which showed higher lipid content (65.29 g/100 g dry basis. The commercial oil showed less primary oxidative degradation, whereas Margarida variety had a lower level of secondary degradation products as well as a higher content of bioactive compounds, such as phytosterols (999.60 mg/kg and tocopherols (36.73 mg/kg. The rheological behaviors of both oils were appropriately described through Newton model, with R2 > 0.999 for all temperatures. By an Arrhenius type equation, it was verified that Hass's rheological parameters are more influenced by temperature than Margarida and commercial oil, presenting activation energy of 33.6 kJ/mol.

  11. Electro-rheological finishing for optical surfaces

    Science.gov (United States)

    Cheng, Haobo; Wang, Peng

    2009-05-01

    Many polishing techniques such as fixed-abrasive polishing, abrasive-free polishing and magnetorheological finishing etc., have been developed. Meanwhile, a new technique is proposed using the mixture of the electro-rheological (Er) fluid with abrasives as polishing slurry, which is a special process does not require pad. Electrorheological fluid is a special suspension liquid, whose viscosity has an approximate proportional relation with the electric strength applied. When the field strength reaches a certain limit, the phase transition occurs and the liquid acquires a solid like character, and while the electric field is removed, the fluid regains its original viscosity during the order of milliseconds. In this research work, we employed the characteristics of viscosity change of Er fluid to hold the polishing particles for micromachining. A point-contact electro-rheological finishing (Erf) tool was designed with a tip diameter 0.5~1mm. Both the anode and the cathode of the electric field were combined in the tool. The electric field could be controllable. When the tool moves across the profile of the work piece, by controlling the electric field strength as well as the other manufacturing parameters we can assure the deterministic material removal. Furthermore, the electro-rheological finishing process has been planned in detailed.

  12. 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

  13. Rheological and boundary effects on microswimmers

    Science.gov (United States)

    Montenegro-Johnson, Thomas; Loghin, Daniel; Smith, David

    2013-11-01

    Two important environmental factors impacting cell motility are the rheological properties of the surrounding fluid and the presence of boundaries. In this talk we will present simulations that explore the relationship between microswimmer, fluid rheology and boundary features, with a particular emphasis on the example of human sperm. Human sperm must navigate the labyrinthine structure of human fallopian tubes, actively bending their flagella in order to propel themselves through physiological mucus. Sperm trajectories are greatly affected by boundaries, scattering over features such as steps and ripples. We present simulations of scattering sperm-like swimmers in confined geometries, comparing these results to experiments of swimmers in microchannels. The rheological properties of mucus also affect sperms' ability to penetrate. Using the method of femlets, a new finite element technique entailing an immersed force representation of the swimmer with a body-fitted mesh, we present novel physical mechanisms through which shear-thinning, an important property of physiological mucus affects microscopic swimmers. In particular, we show that these effects are sensitive to the swimming stroke employed, and present example reciprocal swimmers that violate Purcell's Scallop Theorem.

  14. 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.

  15. 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.

  16. 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.

  17. A highly conductive, non-flammable polymer–nanoparticle hybrid electrolyte

    KAUST Repository

    Agrawal, Akanksha

    2015-01-01

    © 2015 The Royal Society of Chemistry. We report on the physical properties of lithium-ion conducting nanoparticle-polymer hybrid electrolytes created by dispersing bidisperse mixtures of polyethylene glycol (PEG)-functionalized silica nanoparticles in an aprotic liquid host. At high particle contents, we find that the ionic conductivity is a non-monotonic function of the fraction of larger particles xL in the mixtures, and that for the nearly symmetric case xL ≈ 0.5 (i.e. equal volume fraction of small and large particles), the room temperature ionic conductivity is nearly ten-times larger than in similar nanoparticle hybrid electrolytes comprised of the pure small (xL ≈ 0) or large (xL ≈ 1) particle components. Complementary trends are seen in the activation energy for ion migration and effective tortuosity of the electrolytes, which both exhibit minima near xL ≈ 0.5. Characterization of the electrolytes by dynamic rheology reveals that the maximum conductivity coincides with a distinct transition in soft glassy properties from a jammed to partially jammed and back to jammed state, as the fraction of large particles is increased from 0 to 1. This finding implies that the conductivity enhancement arises from purely entropic loss of correlation between nanoparticle centers arising from particle size dispersity. As a consequence of these physics, it is now possible to create hybrid electrolytes with MPa elastic moduli and mS cm-1 ionic conductivity levels at room temperature using common aprotic liquid media as the electrolyte solvent. Remarkably, we also find that even in highly flammable liquid media, the bidisperse nanoparticle hybrid electrolytes can be formulated to exhibit low or no flammability without compromising their favorable room temperature ionic conductivity and mechanical properties.

  18. Rheological properties, gelling behavior and texture characteristics of polysaccharide from Enteromorpha prolifera.

    Science.gov (United States)

    Qiao, Leke; Li, Yinping; Chi, Yongzhou; Ji, Yinglu; Gao, Yan; Hwang, Hueymin; Aker, Winfred G; Wang, Peng

    2016-01-20

    Polysaccharide from Enteromorpha prolifera (PE) which is the most common green algae is gradually becoming an attractive candidate with novel functions by virtue of its unique chemical and physicochemical properties. The infrared spectrum (FT-IR) of PE confirmed that it is a distinctive, sulfated heteropolysaccharide. Dynamic rheology was systematically conducted to investigate the effect of concentration, temperature, pH, and electrolytes on PE. The flow behavior testing verified its pseudoplastic character. A closed hysteresis loop was obtained when the PE concentration reached 10g/L. For the phase angel (tan?) was always less than 1, the solid-like behavior of PE is also found at 10-14g/L PE in the linear viscoelastic region (LVR). Furthermore, study on its potential gelling behavior showed that 16g/L PE could form a gel and had well textural properties. The unique functional groups and characteristics of PE provided the possibility to apply into food industry. PMID:26572475

  19. Feeding electrolyte for sport horses

    OpenAIRE

    Bergero, Domenico; VALLE, EMANUELA

    2008-01-01

    Nowadays is necessary to have a multidisciplinary approach to the horse, to find the key for the optimal performance not only by considering macronutriens such as protein, fat and sugar, but also minerals such as electrolyte. The electrolytes include minerals such as Sodium (Na), Potassium (K) Chloride (Cl), Calcium (Ca) and Magnesium (Mg), that when dissolved in a appropriate solvent are ionized and conduct an electric current. In the body ions are dissolved in three main compartments: the ...

  20. Phase equilibria in electrolyte systems

    OpenAIRE

    Pinho, Simão

    2000-01-01

    The main objectives of this work are the study of solid-liquid equilibrium of salts in pure and mixed solvents, and of biomolecules, such as amino acids and peptides, in water. The correlation and prediction of properties for mixtures containing charged electric species, the electrolytes, is of great relevance for the chemical industry. A brief discussion about the whole interest of this work and the need of concentrating efforts to develop accurate models for electrolyte systems is ini...

  1. High cation transport polymer electrolyte

    Science.gov (United States)

    Gerald, II, Rex E. (Brookfield, IL); Rathke, Jerome W. (Homer Glen, IL); Klingler, Robert J. (Westmont, IL)

    2007-06-05

    A solid state ion conducting electrolyte and a battery incorporating same. The electrolyte includes a polymer matrix with an alkali metal salt dissolved therein, the salt having an anion with a long or branched chain having not less than 5 carbon or silicon atoms therein. The polymer is preferably a polyether and the salt anion is preferably an alkyl or silyl moiety of from 5 to about 150 carbon/silicon atoms.

  2. 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).

  3. Electrolytes for lithium ion batteries

    Science.gov (United States)

    Vaughey, John; Jansen, Andrew N.; Dees, Dennis W.

    2014-08-05

    A family of electrolytes for use in a lithium ion battery. The genus of electrolytes includes ketone-based solvents, such as, 2,4-dimethyl-3-pentanone; 3,3-dimethyl 2-butanone(pinacolone) and 2-butanone. These solvents can be used in combination with non-Lewis Acid salts, such as Li.sub.2[B.sub.12F.sub.12] and LiBOB.

  4. Ionic thermopower of composite electrolytes

    OpenAIRE

    Vennekamp, Martin; Janek, Jürgen

    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...

  5. Ionic liquids as electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Galinski, Maciej; Lewandowski, Andrzej; Stepniak, Izabela [Faculty of Chemical Technology, Poznan University of Technology, PL-60 965 Poznan (Poland)

    2006-08-15

    Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors. (author)

  6. Ionic liquids as electrolytes

    International Nuclear Information System (INIS)

    Salts having a low melting point are liquid at room temperature, or even below, and form a new class of liquids usually called room temperature ionic liquids (RTIL). Information about RTILs can be found in the literature with such key words as: room temperature molten salt, low-temperature molten salt, ambient-temperature molten salt, liquid organic salt or simply ionic liquid. Their physicochemical properties are the same as high temperature ionic liquids, but the practical aspects of their maintenance or handling are different enough to merit a distinction. The class of ionic liquids, based on tetraalkylammonium cation and chloroaluminate anion, has been extensively studied since late 1970s of the XX century, following the works of Osteryoung. Systematic research on the application of chloroaluminate ionic liquids as solvents was performed in 1980s. However, ionic liquids based on aluminium halides are moisture sensitive. During the last decade an increasing number of new ionic liquids have been prepared and used as solvents. The general aim of this paper was to review the physical and chemical properties of RTILs from the point of view of their possible application as electrolytes in electrochemical processes and devices. The following points are discussed: melting and freezing, conductivity, viscosity, temperature dependence of conductivity, transport and transference numbers, electrochemical stability, possible application in aluminium electroplating, lithium batteries and in electrochemical capacitors

  7. Polymer electrolyte fuel cells

    Science.gov (United States)

    Gottesfeld, S.

    The recent increase in attention to polymer electrolyte fuel cells (PEFC's) is the result of significant technical advances in this technology and the initiation of some projects for the demonstration of complete PEFC-based power system in a bus or in a passenger car. A PEFC powered vehicle has the potential for zero emission, high energy conversion efficiency and extended range compared to present day battery powered EV's. This paper describes recent achievements in R&D on PEFC's. The major thrust areas have been: (1) demonstration of membrane/electrode assemblies with stable high performance in life tests lasting 4000 hours, employing ultra-low Pt loadings corresponding to only 1/2 oz of Pt for the complete power source of a passenger car; (2) effective remedies for the high sensitivity of the Pt electrocatalyst to impurities in the fuel feed stream; and (3) comprehensive evaluation of the physicochemical properties of membrane and electrodes in the PEFC, clarifying the water management issues and enabling effective codes and diagnostics for this fuel cell.

  8. Nonlocal granular rheology: Role of pressure and anisotropy

    OpenAIRE

    Wandersman, Elie; Hecke, Martin van

    2014-01-01

    We probe the secondary rheology of granular media, by imposing a main flow and immersing a vane-shaped probe into the slowly flowing granulate. The secondary rheology is then the relation between the exerted torque T and rotation rate \\omega of our probe. In the absence of any main flow, the probe experiences a clear yield-stress, whereas for any finite flow rate, the yield stress disappears and the secondary rheology takes on the form of a double exponential relation betwee...

  9. Relationship between Rheology and Molecular Structure of Innovative Crystalline Elastomers

    OpenAIRE

    Ahmad, Naveed

    2013-01-01

    The study of the rheology of polyolefins based on homogenous metallocenic catalyst has been mainly devoted to the understanding of material process ability. When used at a more advanced and sophisticated level, however, rheology is a useful tool to highlight the details of the polymer microstructure, such as the chemical stereo-regularity or the degree of chain branching. Rheology is also used to study the crystallization kinetics of the polymers and it gives more precise analysis than the co...

  10. 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

  11. Effect of Hydrogen Bonding on Linear and Nonlinear Rheology of Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Shabbir, Aamir; Goldansaz, Hadi

    2015-01-01

    Supramolecular polymers are used in many applications such as adhesives, coatings, cosmetics, and printing. Characterizing the dynamics of such polymers is essential for tailoring user defined properties in products and applications. We present both linear and nonlinear rheological results for a model system of pure poly(n-butyl acrylate), PnBA, homopolymer and four PnBA? poly(acrylic acid), PnBA?PAA, copolymers with different number of AA side groups. The copolymers are synthesized via hydrolysis of the pure PnBA homopolymer. Therefore, all polymers studied have the same backbone length. The number of AA side groups (hydrogen-bonding groups) after hydrolysis is determined from NMR measurements. We show that using the theoretical dependency of modulus and reptation time on the packing length, we can account for the changes in linear viscoelasticity due to transformation of nBA side groups to AA along the backbone. Assuming superposition holds and subtracting out the linear chain rheology from LVE, the hydrogen bonding contribution to LVE is exposed. Hydrogen bonding affects linear viscoelasticity at frequencies below the inverse reptation time. More specifically, the presence of hydrogen bonds causes G? and G? as a function of frequency to shift to a power law scaling of 0.5. Furthermore, the magnitude of G? and G? scales linearly with the number of hydrogen-bonding groups. The nonlinear extensional rheology shows extreme strain hardening. The magnitude of extensional stress has a strongly nonlinear dependence on the number of hydrogenbonding groups. These results are aimed at uncovering the molecular influence of hydrogen bonding on linear and nonlinear rheology to aid future molecular synthesis and model development.

  12. 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.

  13. 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.

  14. 77 FR 25406 - Consortium on “Concrete Rheology: Enabling Metrology (CREME)”: Membership Fee Update

    Science.gov (United States)

    2012-04-30

    ...Technology Consortium on ``Concrete Rheology: Enabling Metrology...NIST/Industry Consortium on Concrete Rheology: Enabling Metrology...consortium is to predict the pumpability of a grout/mortar or a concrete from the rheological...

  15. Hectorite-based nanocomposite electrolytes for lithium-ion batteries

    Science.gov (United States)

    Riley, Michael William

    Hectorite clay is presented in this work as a promising component for electrolytes for lithium-ion batteries. This negatively-charged, plate-shaped (250 nm diameter by 1 nm thickness) clay has exchangeable cations for which lithium may be substituted. When properly dispersed in high-dielectric solvents such as the carbonates (ethylene carbonate and propylene carbonate) typically used in lithium-ion cells, a shear-thinning physical gel is created possessing a good conductivity (as high as 2 x 10-4 S/cm at room temperature has been measured) with near unity lithium-ion transference numbers. As a result, hectorite-based electrolytes could drastically reduce concentration polarization and present an inherently safer electrolyte as toxic salts such as LiPF6 that are typically used could be eliminated. Hectorite clay dispersions in aqueous and non-aqueous (1:1 (v:v) ethylene carbonate: poly(ethylene)glycol dimethyl ether 250 MW) solvents have been studied using rheology (dynamic and steady) and conductivity. The aqueous dispersions show a highly-exfoliated microstructure (fractal dimension, Df ? 1.6) created primarily through electrostatic repulsive forces which recovers after shear deformation by reorientation of the clay platelets. The non-aqueous dispersions form gel structures with a much higher degree of aggregation (Df ? 2.5), and recovery after shear deformation appears to be an aggregation controlled process as well. TEM imaging of non-aqueous clay dispersions shows the clay to be uniformly distributed, with the platelets existing in aggregates of 3 to 5 layers. Use of the hectorite-based electrolytes in lithium-ion cells requires electrodes that contain a single-ion conductor in the typically porous structures. Cathodes based on LiCoO2 that contain various lithium-conducting species (lithium hectorite, lithium LaponiteRTM, and lithium-exchanged NAFIONRTM) have been studied. AC impedance spectroscopy was used to probe the cells and equivalent circuits were used to model the physical processes that occur. Cathodes containing 4 wt. % lithium hectorite + 3 wt. lithium-exchanged NAFIONRTM + 3 wt. % carbon black exhibit capacities approximately 90 mAh/g LiCoO2. These hectorite-based electrolytes and clay-containing cathodes are potentially attractive for use in single-ion conducting lithium-ion batteries designed for high-discharge applications.

  16. An electrolyte CPA equation of state for mixed solvent electrolytes

    DEFF Research Database (Denmark)

    Maribo-Mogensen, BjØrn; Thomsen, Kaj

    2015-01-01

    Despite great efforts over the past decades, thermodynamic modeling of electrolytes in mixed solvents is still a challenge today. The existing modeling frameworks based on activity coefficient models are data-driven and require expert knowledge to be parameterized. It has been suggested that the predictive capabilities could be improved through the development of an electrolyte equation of state. In this work, the Cubic Plus Association (CPA) Equation of State is extended to handle mixtures containing electrolytes by including the electrostatic contributions from the Debye-Hückel and Born terms using a self-consistent model for the static permittivity. A simple scheme for parameterization of salts with a limited number of parameters is proposed and model parameters for a range of salts are determined from experimental data of activity and osmotic coefficients as well as freezing point depression. Finally, the model is applied to predict VLE, LLE, and SLE in aqueous salt mixtures as well as in mixed solvents.

  17. 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.

  18. Rheology of Three-Phase Magmas

    Science.gov (United States)

    Pistone, M.; Caricchi, L.; Ulmer, P.; Reusser, E.; Marone, F.; Burlini, L.

    2012-04-01

    Luigi Burlini was a conscious supervisor, a brilliant teacher and a dear friend. He instilled in me optimism and passion for research. His scientific eclecticism to combine several disciplines and methodologies to challenge and solve science issues has enhanced my approach of analysis and observation. His "simple" curiosity to test new scientific pathways and truly know the validity of own proposals represents my primary inspiration to continue the academic career. He was the far-seeing and carpe diem man at the same time; from this I learnt to live intensively day by day without forgetting what will be next. The work I will present is dedicated to him. We present experimental results from a study mainly aiming to constrain the dependence of rheology of three-phase magmas (ranging from dilute suspensions to crystal mushes) on the viscosity of the suspending silicate melt, on the relative contents of crystals and bubbles and on the interactions occurring between the three phases during deformation. Hydrous haplogranitic magmas containing variable amounts of quartz crystals (between 24 and 65 vol%), and fixed bubble volume (9-12 vol% CO2-rich bubbles) were deformed in simple shear with a Paterson-type rock deformation apparatus at high temperature (823-1023 K) and high pressure (200 MPa), in strain-rate stepping (5•10-5 s-1 - 4•10-3 s-1) from low to high deformation rate. The rheological results suggest that three-phase suspensions are characterized by strain rate-dependent rheology (non-Newtonian behavior). Two kinds of non-Newtonian behaviors were observed: shear thinning (decrease of viscosity with increasing strain rate) and shear thickening (increase of viscosity with increasing strain rate). Microstructural observations suggest that: shear thinning dominantly occurs in crystal-rich magmas (55-65 vol% crystals) because of crystal size reduction and shear localization; shear thickening prevails in dilute suspensions (24-44 vol% crystals) due to outgassing promoted by bubble coalescence.

  19. Anion exchange polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. 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.

  1. Rheology of spinel sludge in molten glass

    International Nuclear Information System (INIS)

    Spinel sludge, which forms while vitrifying high-level waste, obstructs the flow of molten glass and damages the melter. The effectiveness of removing spinel sludge from a high-level waste glass melter depends on its rheological behavior. We prepared spinel sludge in a laboratory crucible by allowing spinel to settle from molten glass and measured the response of the sludge to shear using a rotating spindle viscometer. The shear stress increased nonlinearly with the velocity gradient (the shear rate) and with time at a constant velocity gradient, as is typical for a pseudoplastic rheopectic liquid. The apparent viscosity of the sludge substantially increased when RuO-2 needles were present

  2. Integrated system for design and analysis of industrial processes with electrolyte system

    DEFF Research Database (Denmark)

    Takano, Kiyoteru; Gani, Rafiqul

    1999-01-01

    An algorithm for design and analysis of crystallization processes with electrolyte systems is presented. This algorithm consists of a thermodynamic part, a synthesis part and a design part. The three parts are integrated through a simulation engine. The main features of the algorithm is the use of thermodynamic insights not only to generate process alternatives but also to obtain good initial estimates for the simulation engine and for visualization of process synthesis/design. The main steps of...

  3. 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.

  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. Influence of the type of electrolyte on the morphological and crystallographic characteristics of lead powder particles

    Directory of Open Access Journals (Sweden)

    Nikoli? Nebojša D.

    2013-01-01

    Full Text Available Lead electrodeposition processes from the basic (nitrate and complex (acetate electrolytes were mutually compared by the scanning electron microscopic and the X-ray diffraction analysis of the produced powder particles. The shape of dendritic particles strongly depended on the type of electrolyte. The dendrites composed of stalk and weakly developed primary branches (the primary type were predominantly formed from the basic electrolyte. The ramified dendrites composed of stalk and of both primary and secondary branches (the secondary type were mainly formed from the complex electrolyte. In the both type of powder particles Pb crystallites were predominantly oriented in the (111 plane. Formation of powder particles of the different shape with the strong (111 preferred orientation was discussed and explained by the consideration of the general characteristics of the growth of a crystal in the electrocrystallization processes. [Projekat Ministarstva nauke Republike Srbije, br. 172046: Electrochemical synthesis and characterization of nanostructured functional materials for application in new technologies

  6. Preparation of poly(acrylonitrile-butyl acrylate) gel electrolyte for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Tian Zheng [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); He Xiangming [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)]. E-mail: hexm@tsinghua.edu.cn; Pu Weihua [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Wan Chunrong [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China); Jiang Changyin [Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2006-10-25

    Poly(acrylonitrile-butyl acrylate) gel polymer electrolyte was prepared for lithium ion batteries. The preparation started with synthesis of poly(acrylonitrile-butyl acrylate) by radical emulsion polymerization, followed by phase inversion to produce microporous membrane. Then, the microporous gel polymer electrolytes (MGPEs) was prepared with the microporous membrane and LiPF{sub 6} in ethylene carbonate/diethyl carbonate. The dry microporous membrane showed a fracture strength as high as 18.98 MPa. As-prepared gel polymer electrolytes presented ionic conductivity in excess of 3.0 x 10{sup -3} S cm{sup -1} at ambient temperature and a decomposition voltage over 6.6 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for Li-ion batteries.

  7. Preparation of poly(acrylonitrile-butyl acrylate) gel electrolyte for lithium-ion batteries

    International Nuclear Information System (INIS)

    Poly(acrylonitrile-butyl acrylate) gel polymer electrolyte was prepared for lithium ion batteries. The preparation started with synthesis of poly(acrylonitrile-butyl acrylate) by radical emulsion polymerization, followed by phase inversion to produce microporous membrane. Then, the microporous gel polymer electrolytes (MGPEs) was prepared with the microporous membrane and LiPF6 in ethylene carbonate/diethyl carbonate. The dry microporous membrane showed a fracture strength as high as 18.98 MPa. As-prepared gel polymer electrolytes presented ionic conductivity in excess of 3.0 x 10-3 S cm-1 at ambient temperature and a decomposition voltage over 6.6 V. The results showed that the as-prepared gel polymer electrolytes were promising materials for Li-ion batteries

  8. 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.

  9. 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...

  10. 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.?????????? ??????? ????????? ?????????? ??????-?????-??????????? ?????????. ?????????? ???????????????? ????????? ???????? ? ????????????? ? ?????? ??????? ??????????, ??????? ?????????? ???????? ??????????? ????????? ????. ???????? ??????????? ??? ??????????? ?????????????? ????????? ?????? ??????-?????-????????????? ???? ??? ???????? ??????????. ?????????? ??????????? ?????????? ???????? ?????????????? ???????? ???? ?? ??????? ?????????? ??????????. ????????? ??????-?????-?????????? ????? ??????????? ?? ??????? ????????????? ?????? ???? ???????.

  11. Thermoelectricity in confined liquid electrolytes

    CERN Document Server

    Dietzel, Mathias

    2015-01-01

    The electric field in an extended phase of a liquid electrolyte exposed to a temperature gradient is attributed to different thermophoretic mobilities of the ion species. As shown herein, such Soret-type ion thermodiffusion is not required to induce thermoelectricity even in the simplest electrolyte if it is confined between charged walls. The space charge of the electric double layer leads to selective ion diffusion driven by a temperature-dependent electrophoretic ion mobility, which -for narrow channels- may cause thermo-voltages larger in magnitude than for the classical Soret equilibrium.

  12. Development of Alternative Rheological Measurements for DWPF Slurry Samples (U)

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. c.

    2005-09-01

    Rheological measurements are used to evaluate the fluid dynamic behavior of Defense Waste Processing Facility, DWPF, slurry samples. Measurements are currently made on non-radioactive simulant slurries using two state-of-the-art rheometers located at the Aiken County Technical Laboratory, ACTL. Measurements are made on plant samples using a rheometer in the Savannah River National Laboratory, SRNL, Shielded Cells facility. Low activity simulants or plant samples can be analyzed using a rheometer located in a radioactive hood in SRNL. Variations in the rheology of SB2 simulants impacted the interpretation of results obtained in a number of related studies. A separate rheological study was initiated with the following four goals: (1) Document the variations seen in the simulant slurries, both by a review of recent data, and by a search for similar samples for further study. (2) Attempt to explain the variations in rheological behavior, or, failing that, reduce the number of possible causes. In particular, to empirically check for rheometer-related variations. (3) Exploit the additional capabilities of the rheometers by developing new measurement methods to study the simulant rheological properties in new ways. (4) Formalize the rheological measurement process for DWPF-related samples into a series of protocols. This report focuses on the third and fourth goals. The emphasis of this report is on the development and formalization of rheological measurement methods used to characterize DWPF slurry samples. The organization is by rheological measurement method. Progress on the first two goals was documented in a concurrent technical report, Koopman (2005). That report focused on the types and possible causes of unusual rheological behavior in simulant slurry samples. It was organized by the sample being studied. The experimental portion of this study was performed in the period of March to April 2004. A general rheology protocol for routine DWPF slurry samples, Koopman (2004b), was drafted in addition to the companion technical report to this document.

  13. Development of Alternative Rheological Measurements for DWPF Slurry Samples

    International Nuclear Information System (INIS)

    Rheological measurements are used to evaluate the fluid dynamic behavior of Defense Waste Processing Facility, DWPF, slurry samples. Measurements are currently made on non-radioactive simulant slurries using two state-of-the-art rheometers located at the Aiken County Technical Laboratory, ACTL. Measurements are made on plant samples using a rheometer in the Savannah River National Laboratory, SRNL, Shielded Cells facility. Low activity simulants or plant samples can be analyzed using a rheometer located in a radioactive hood in SRNL. Variations in the rheology of SB2 simulants impacted the interpretation of results obtained in a number of related studies. A separate rheological study was initiated with the following four goals: (1) Document the variations seen in the simulant slurries, both by a review of recent data, and by a search for similar samples for further study. (2) Attempt to explain the variations in rheological behavior, or, failing that, reduce the number of possible causes. In particular, to empirically check for rheometer-related variations. (3) Exploit the additional capabilities of the rheometers by developing new measurement methods to study the simulant rheological properties in new ways. (4) Formalize the rheological measurement process for DWPF-related samples into a series of protocols. This report focuses on the third and fourth goals. The emphasis of this report is on the development and formalization of rheological measurement methods used to characterize DWPF slurry samples. The organization is by rheological measurement method. Progress on the first two goals was documented in a concurrent technical report, Koopman (2005). That report focused on the types and possible causes of unusual rheological behavior in simulant slurry samples. It was organized by the sample being studied. The experimental portion of this study was performed in the period of March to April 2004. A general rheology protocol for routine DWPF slurry samples, Koopman (2004b), was drafted in addition to the companion technical report to this document

  14. Shear rheology of a cell monolayer

    International Nuclear Information System (INIS)

    We report a systematic investigation of the mechanical properties of fibroblast cells using a novel cell monolayer rheology (CMR) technique. The new technique provides quantitative rheological parameters averaged over ?106 cells making the experiments highly reproducible. Using this method, we are able to explore a broad range of cell responses not accessible using other present day techniques. We perform harmonic oscillation experiments and step shear or step stress experiments to reveal different viscoelastic regimes. The evolution of the live cells under externally imposed cyclic loading and unloading is also studied. Remarkably, the initially nonlinear response becomes linear at long timescales as well as at large amplitudes. Within the explored rates, nonlinear behaviour is only revealed by the effect of a nonzero average stress on the response to small, fast deformations. When the cell cytoskeletal crosslinks are made permanent using a fixing agent, the large amplitude linear response disappears and the cells exhibit a stress stiffening response instead. This result shows that the dynamic nature of the cross-links and/or filaments is responsible for the linear stress-strain response seen under large deformations. We rule out the involvement of myosin motors in this using the inhibitor drug blebbistatin. These experiments provide a broad framework for understanding the mechanical responses of the cortical actin cytoskeleton of fibroblasts to different imposed mechanical stimuli

  15. Rheology of a sonofluidized granular packing.

    Science.gov (United States)

    Caballero-Robledo, G A; Clément, E

    2009-12-01

    We report experimental measurements on the rheology of a dry granular material under a weak level of vibration generated by sound injection. First, we measure the drag force exerted on a wire moving in the bulk. We show that when the driving vibration energy is increased, the effective rheology changes drastically: going from a non-linear dynamical friction behavior --weakly increasing with the velocity-- up to a linear force-velocity regime. We present a simple heuristic model to account for the vanishing of the stress dynamical threshold at a finite vibration intensity and the onset of a linear force-velocity behavior. Second, we measure the drag force on spherical intruders when the dragging velocity, the vibration energy, and the diameters are varied. We evidence a so-called "geometrical hardening" effect for smaller-size intruders and a logarithmic hardening effect for the velocity dependence. We show that this last effect is only weakly dependent on the vibration intensity. PMID:19998051

  16. Shear rheology of a cell monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Pablo [Experimentalphysik I, Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany); Heymann, Lutz [Technische Mechanik und Stroemungsmechanik, Universitaet Bayreuth, D-95440 Bayreuth (Germany); Ott, Albrecht [Experimentalphysik I, Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany); Aksel, Nuri [Technische Mechanik und Stroemungsmechanik, Universitaet Bayreuth, D-95440 Bayreuth (Germany); Pullarkat, Pramod A [Experimentalphysik I, Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)

    2007-11-15

    We report a systematic investigation of the mechanical properties of fibroblast cells using a novel cell monolayer rheology (CMR) technique. The new technique provides quantitative rheological parameters averaged over {approx}10{sup 6} cells making the experiments highly reproducible. Using this method, we are able to explore a broad range of cell responses not accessible using other present day techniques. We perform harmonic oscillation experiments and step shear or step stress experiments to reveal different viscoelastic regimes. The evolution of the live cells under externally imposed cyclic loading and unloading is also studied. Remarkably, the initially nonlinear response becomes linear at long timescales as well as at large amplitudes. Within the explored rates, nonlinear behaviour is only revealed by the effect of a nonzero average stress on the response to small, fast deformations. When the cell cytoskeletal crosslinks are made permanent using a fixing agent, the large amplitude linear response disappears and the cells exhibit a stress stiffening response instead. This result shows that the dynamic nature of the cross-links and/or filaments is responsible for the linear stress-strain response seen under large deformations. We rule out the involvement of myosin motors in this using the inhibitor drug blebbistatin. These experiments provide a broad framework for understanding the mechanical responses of the cortical actin cytoskeleton of fibroblasts to different imposed mechanical stimuli.

  17. Dynamics and Rheology of Soft Colloidal Glasses

    KAUST Repository

    Wen, Yu Ho

    2015-01-20

    © 2015 American Chemical Society. The linear viscoelastic (LVE) spectrum of a soft colloidal glass is accessed with the aid of a time-concentration superposition (TCS) principle, which unveils the glassy particle dynamics from in-cage rattling motion to out-of-cage relaxations over a broad frequency range 10-13 rad/s < ω < 101 rad/s. Progressive dilution of a suspension of hairy nanoparticles leading to increased intercenter distances is demonstrated to enable continuous mapping of the structural relaxation for colloidal glasses. In contrast to existing empirical approaches proposed to extend the rheological map of soft glassy materials, i.e., time-strain superposition (TSS) and strain-rate frequency superposition (SRFS), TCS yields a LVE master curve that satis fies the Kramers-Kronig relations which interrelate the dynamic moduli for materials at equilibrium. The soft glassy rheology (SGR) model and literature data further support the general validity of the TCS concept for soft glassy materials.

  18. Rheology and structural arrest of casein suspensions.

    Science.gov (United States)

    Dahbi, L; Alexander, M; Trappe, V; Dhont, J K G; Schurtenberger, P

    2010-02-15

    The rheology of milk powder suspensions is investigated up to very high concentrations, where structural arrest occurs. The main component of the milk powder investigated is casein, so that the suspensions can be regarded as casein suspensions. Four concentration regimes are identified. For effective casein volume fractions less than 0.54 the concentration dependence of the zero-shear viscosity is similar to that of hard-sphere suspensions. However, due to the elastic deformation of the caseins, the viscosity does not diverge at the hard sphere glass transition. In the volume-fraction range of 0.55-0.61 the viscosity exhibits a surprisingly weak dependence on concentration. The shape of the curve of the shear viscosity versus concentration deviates from hard sphere behavior in an unusual way, due to the observation of a region of almost constant viscosity. This concentration regime is followed by a regime where the viscosity steeply increases, eventually diverging at an effective volume fraction of 0.69. Frequency dependent rheology and diffusing wave spectroscopy measurements indicate that the suspensions are jammed for volume fractions above 0.69. Finally we found the concentration dependence of the relative zero-shear viscosity of casein suspensions to be very similar with the one of the micro-gels at volume fractions below 0.50 and above 0.55, which are know to shrink above a certain volume fraction, due to osmotic stress. PMID:19944426

  19. 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

  20. Vortex jamming in superconductors and granular rheology

    International Nuclear Information System (INIS)

    We demonstrate that a highly frustrated anisotropic Josephson junction array (JJA) on a square lattice exhibits a zero-temperature jamming transition, which shares much in common with those in granular systems. Anisotropy of the Josephson couplings along the horizontal and vertical directions plays roles similar to normal load or density in granular systems. We studied numerically static and dynamic response of the system against shear, i.e. injection of external electric current at zero temperature. Current-voltage curves at various strength of the anisotropy exhibit universal scaling features around the jamming point much as do the flow curves in granular rheology, shear-stress versus shear-rate. It turns out that at zero temperature the jamming transition occurs right at the isotropic coupling and anisotropic JJA behaves as exotic fragile vortex matter: it behaves as a superconductor (vortex glass) in one direction, whereas it is a normal conductor (vortex liquid) in the other direction even at zero temperature. Furthermore, we find a variant of the theoretical model for the anisotropic JJA quantitatively reproduces universal master flow-curves of the granular systems. Our results suggest an unexpected common paradigm stretching over seemingly unrelated fields-the rheology of soft materials and superconductivity.

  1. Rheological changes in irradiated chicken eggs

    International Nuclear Information System (INIS)

    Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25 degree sign C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications

  2. 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.

  3. 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

  4. Rheological changes in irradiated chicken eggs

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Lucia F. S.; Del Mastro, Nelida L

    1998-06-01

    Pathogenic bacteria may cause foodborne illnesses. Humans may introduce pathogens into foods during production, processing, distribution and or preparation. Some of these microorganisms are able to survive conventional preservation treatments. Heat pasteurization, which is a well established and satisfactory means of decontamination/disinfection of liquid foods, cannot efficiently achieve a similar objective for solid foods. Extensive work carried out worldwide has shown that irradiation is efficient in eradicating foodborne pathogens like Salmonella spp. that can contaminate poultry products. In this work Co-60 gamma irradiation was applied to samples of industrial powder white, yolk and whole egg at doses between 0 and 25 kGy. Samples were rehydrated and the viscosity measured in a Brookfield viscosimeter, model DV III at 5, 15 and 25 degree sign C. The rheological behaviour among the various kinds of samples were markedly different. Irradiation with doses up to 5 kGy, known to reduced bacterial contamination to non-detectable levels, showed almost no variation of viscosity of irradiated egg white samples. On the other hand, whole or yolk egg samples showed some changes in rheological properties depending on the dose level, showing the predominance of whether polimerization or degradation as a result of the irradiation. Additionally, irradiation of yolk egg powder reduced yolk color as a function of the irradiation exposure implemented. The importance of these results are discussed in terms of possible industrial applications.

  5. 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.

  6. 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.

  7. 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.

  8. Relating Single Crystal Rheology to Polyphase Aggregate Rheology - the Importance of Stress Percolation

    Science.gov (United States)

    Burnley, P. C.

    2014-12-01

    Percolation theory is used to describe the behavior of a large number of disordered systems including the passage of fluid through porous materials, the spread of forest fires, and the mechanical behavior of granular materials. By virtue of both variations in elastic and plastic properties between different rock forming minerals as well as the plastic and elastic anisotropy of individual mineral grains, polycrystalline rocks are elastically and plastically disordered systems. Using 2D finite element models I have shown that stress transmission in rocks can also be described as a percolation problem and that the modulation of stress states within a rock can in some cases, reach levels comparable to the differential load on the rock. The presence of such modulations in the internal stress state of a rock has many implications for understanding how the rock's rheology arises from the rheology of its constituent crystals. A first order result of stress percolation is the formation of shear localization. Depending on the degree of mechanical heterogeneity of the rock's mechanical components (including grain interiors and grain boundaries), the nature of the shear localization may be highly concentrated - and therefore observable or widely distributed and "cryptic" in nature. The modulations in stress states created by stress percolation create small regions (yield nuclei) distributed throughout the rock that yield well before the bulk of the rock has reached the yield criterion. Local yielding leads to percolation of yielded regions and shear localization. Whether the shear localization remains cryptic or is observable by virtue of the development of large offsets, is a function of the density and distribution of yield nuclei. The spatial distribution of yield nuclei is a function of the nature of the stress percolation pattern, the variation in yield strength of the mechanical components and their spatial distribution. The presence of shear localization changes the relationship between single-crystal rheology and bulk rock rheology and therefore must be taken into account when modelling bulk rheology based on single-crystal rheology. Figure: a) FE model mesh b)-e) Plastic strain b) Young's modulus, E = 500 to 0 GPa with v=0.1 to 0.4, c) E= 500 to 0 GPa with v=0.3 d) E= 200 to 20 GPa with v=0.3 and e) E =120 to 100 GPa with v=0.3.

  9. LOWER TEMPERATURE ELECTROLYTE AND ELECTRODE MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Keqin Huang

    2003-04-30

    A thorough literature survey on low-temperature electrolyte and electrode materials for SOFC is given in this report. Thermodynamic stability of selected electrolyte and its chemical compatibility with cathode substrate were evaluated. Preliminary electrochemical characterizations were conducted on symmetrical cells consisting of the selected electrolyte and various electrode materials. Feasibility of plasma spraying new electrolyte material thin-film on cathode substrate was explored.

  10. Efficient Electrolytes for Lithium–Sulfur Batteries

    OpenAIRE

    Angulakshmi, Natarajan; Stephan, Arul Manuel

    2015-01-01

    This review article mainly encompasses on the state-of-the-art electrolytes for lithium–sulfur batteries. Different strategies have been employed to address the issues of lithium–sulfur batteries across the world. One among them is identification of electrolytes and optimization of their properties for the applications in lithium–sulfur batteries. The electrolytes for lithium–sulfur batteries are broadly classified as (i) non-aqueous liquid electrolytes, (ii) ionic liquids, (iii) solid polyme...

  11. Polymer Electrolytes for Lithium/Sulfur Batteries

    OpenAIRE

    The Nam Long Doan; Denise Gosselink; Yongguang Zhang; Mikhail Sadhu; Ho-Jae Cheang; Pu Chen; Yan Zhao

    2012-01-01

    This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S) batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes.

  12. Polymer Electrolytes for Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    The Nam Long Doan

    2012-08-01

    Full Text Available This review evaluates the characteristics and advantages of employing polymer electrolytes in lithium/sulfur (Li/S batteries. The main highlights of this study constitute detailed information on the advanced developments for solid polymer electrolytes and gel polymer electrolytes, used in the lithium/sulfur battery. This includes an in-depth analysis conducted on the preparation and electrochemical characteristics of the Li/S batteries based on these polymer electrolytes.

  13. Non aqueous electrochemical cell and electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Prater, K. B.; Connolly, J. F.; Thrash, R. J.

    1985-05-28

    Disclosed is an ambient temperature, rechargeable non-aqueous electrochemical cell having an active metal anode of the second kind, a cathode depolarizer, positive electrode current collector and an electrolyte comprising a solvent, a supporting electrolyte salt, and an active metal salt. Also disclosed is an electrolyte for non-aqueous active metal cells.

  14. Rechargeable solid polymer electrolyte battery cell

    Science.gov (United States)

    Skotheim, Terji (East Patchoque, NY)

    1985-01-01

    A rechargeable battery cell comprising first and second electrodes sandwiching a solid polymer electrolyte comprising a layer of a polymer blend of a highly conductive polymer and a solid polymer electrolyte adjacent said polymer blend and a layer of dry solid polymer electrolyte adjacent said layer of polymer blend and said second electrode.

  15. 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.

  16. 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...

  17. Proton-conducting electrolyte membranes based on aromatic condensation polymers

    International Nuclear Information System (INIS)

    The results of investigations in the field of development and applications of proton-conducting electrolyte membranes based on aromatic condensation polymers are analysed and summarised. Primary attention is paid to the properties of the starting polymers, such as the thermal stability, water uptake and proton conductivity. General approaches to the preparation of aromatic condensation polymers with high proton conductivity are considered, including sulfonation, synthesis from monomers containing sulfonic acid groups, incorporation of alkylsulfonated substituents and formation of acid-basic polymer complexes. The bibliography includes 115 references.

  18. Shear History Extensional Rheology Experiment II (SHERE II) Microgravity Rheology with Non-Newtonian Polymeric Fluids

    Science.gov (United States)

    Jaishankar, Aditya; Haward, Simon; Hall, Nancy Rabel; Magee, Kevin; McKinley, Gareth

    2012-01-01

    The primary objective of SHERE II is to study the effect of torsional preshear on the subsequent extensional behavior of filled viscoelastic suspensions. Microgravity environment eliminates gravitational sagging that makes Earth-based experiments of extensional rheology challenging. Experiments may serve as an idealized model system to study the properties of lunar regolith-polymeric binder based construction materials. Filled polymeric suspensions are ubiquitous in foods, cosmetics, detergents, biomedical materials, etc.

  19. Highly Active Electrolytes for Rechargeable Mg Batteries Based on [Mg2(?-Cl)2]2+ Cation Complex in Dimethoxyethane

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Yingwen; Stolley, Ryan M.; Han, Kee Sung; Shao, Yuyan; Arey, Bruce W.; Washton, Nancy M.; Mueller, Karl T.; Helm, Monte L.; Sprenkle, Vincent L.; Liu, Jun; Li, Guosheng

    2015-01-01

    Highly active electrolytes based on a novel [Mg2(?-Cl)2]2+ cation complex for reversible Mg deposition were developed and analyzed in this work. These electrolytes were formulated in dimethoxyethane through dehalodimerization of non-nucleophilic MgCl2 by reacting with either Mg salts (such as Mg(TFSI)2, TFSI= bis(trifluoromethane)sulfonylimide) or Lewis acid salts (such as AlEtCl2 or AlCl3). The cation complex was identified for the first time as [Mg2(?-Cl)2(DME)4]2+ (DME=dimethoxyethane) and its molecular structure was characterized by single crystal X-ray diffraction, Raman spectroscopy and NMR. The electrolyte synthesis process was studied and rational approaches for formulating highly active electrolytes were proposed. Through control of the anions, electrolytes with efficiency close to 100%, wide electrochemical window (up to 3.5V) and high ionic conductivity (> 6 mS/cm) were obtained. The electrolyte synthesis and understandings developed in this work could bring significant opportunities for rational formulation of electrolytes with the general formula [Mg2(?-Cl)2(DME)4][anion]x for practical Mg batteries.

  20. 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 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

  1. Electrolytes for high-energy lithium batteries

    Science.gov (United States)

    Schaefer, Jennifer L.; Lu, Yingying; Moganty, Surya S.; Agarwal, Praveen; Jayaprakash, N.; Archer, Lynden A.

    2012-06-01

    From aqueous liquid electrolytes for lithium-air cells to ionic liquid electrolytes that permit continuous, high-rate cycling of secondary batteries comprising metallic lithium anodes, we show that many of the key impediments to progress in developing next-generation batteries with high specific energies can be overcome with cleaver designs of the electrolyte. When these designs are coupled with as cleverly engineered electrode configurations that control chemical interactions between the electrolyte and electrode or by simple additives-based schemes for manipulating physical contact between the electrolyte and electrode, we further show that rechargeable battery configurations can be facilely designed to achieve desirable safety, energy density and cycling performance.

  2. 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.)

  3. 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

  4. 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.

  5. A microvalve using magneto-rheological fluid

    International Nuclear Information System (INIS)

    For millimeter sized working micromachines using fluid power with high density, a novel microvalve with simple structure using magneto rheological (MR) fluid is proposed and called the micro MR valve. The micro MR valve utilizes the apparent viscosity controllability of the MR fluid in the magnetic field. To control sufficiently high magnetic flux density in the microvalve, a magnetic circuit using a permanent magnet, a thermosensitive ferrite, and Peltier elements called the thermo-control magnetic circuit is introduced. First, the micro MR valve is proposed and the basic characteristics are theoretically investigated. Second, the thermo-control magnetic circuit is fabricated and the static and dynamic characteristics are experimentally investigated and improved. Finally, a 3-port micro MR valve is fabricated and the characteristics are experimentally clarified and improved. (author)

  6. 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.

  7. 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.

  8. Rheological effects on friction in elastohydrodynamic lubrication

    Science.gov (United States)

    Trachman, E. G.; Cheng, H. S.

    1973-01-01

    An analytical and experimental investigation is presented of the friction in a rolling and sliding elastohydrodynamic lubricated contact. The rheological behavior of the lubricant is described in terms of two viscoelastic models. These models represent the separate effects of non-Newtonian behavior and the transient response of the fluid. A unified description of the non-Newtonian shear rate dependence of the viscosity is presented as a new hyperbolic liquid model. The transient response of viscosity, following the rapid pressure rise encountered in the contact, is described by a compressional viscoelastic model of the volume response of a liquid to an applied pressure step. The resulting momentum and energy equations are solved by an iterative numerical technique, and a friction coefficient is calculated. The experimental study was performed, with two synthetic paraffinic lubricants, to verify the friction predictions of the analysis. The values of friction coefficient from theory and experiment are in close agreement.

  9. 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.

  10. 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.

  11. Rheological properties of carbon mixes using a capillary rheometer. IV

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, G.

    1976-01-01

    The capillary rheometer has been used to determine the rheological properties of various carbon mixes consisting of petroleum coke as filler and coal tar pitch as binder. It has been shown that the carbon mixes containing various proportions of binder behave rheologically as Bingham material with yield stress and plastic viscosity. When binder level exceeds a certain optimum level, plastic viscosity shows a steep fall from 20 x 10/sup 5/ to 2 x 10/sup 5/ P (poises), while yield stress does not show much variation. A comparatively better rheological behavior is observed with capillary rheometer than that with parallel plate viscometer.

  12. [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

  13. [Effect of smoking on blood rheology].

    Science.gov (United States)

    Maurel, A; Apovo, M; Beuzard, Y; Boynard, M; Lagrue, G

    1997-10-01

    The aim of this study was to compare the effects of cigarette smoking on biologic and rheologic tests, chiefly on the red blood cells (RBC) in measuring the deformability by the Cell Transit Analyser (CTA) and their aggregation by using an ultrasonic interferometry method based on A-mode echography allowed for the measurement of the accumulation rate of particles in a solid plate which is related to their sedimentation rate (Echo-Cell). Nine male smoker subjects with a high nicotine addiction measured by Fagerström questionnaire (> 8) and level of carbon monoxide (CM) in the breathed out air (> 20 ppm), have been compared with ten healthy no-smoker volunteers (CM GT, ASAT, ALAT, uric acid, total cholesterol and glucose levels were not significantly different between the two groups. On the other hand, in the smoker group, white blood cells count, serum triglycerides and especially fibrinogen values were higher than in the non-smoker's group. RBC sedimentation rate was normal in the two groups but was higher in smoker's group too. Without consumption of alcohol, the mean RBC volume was more important in smokers (91.9 +/- 1.2 versus 87.5 +/- 0.4, p = 0.003). Rheologic tests were more pathologic in smokers. The transit time or RBC by CTA was longer than in control group (1.6 ms +/- 0.02 versus 1.2 +/- 0.05, p = 0.0003). Echo-Cell technic showed a number and size of RBC aggregates more important with a rate of speed of accumulation higher than in the control group. These results demonstrated the toxic effects of smoking alone on blood toward a propensity for thrombotic status. PMID:9411009

  14. Characteristics analysis of electrolytic tritium separation using solid polymer electrolyte

    International Nuclear Information System (INIS)

    The characteristics of electrolytic tritium separation using solid polymer electrode were analyzed. H-T separation factor (SFHT) and D-T separation factor (SFDT) were calculated from equilibrium constant of the hydrogen isotope exchange reaction between water and diatomic hydride and from two-phase distribution theory for isotopes. The calculated SFHT and SFDT were well agreed with the experimental values. The theory used in this study will available to select optimum cathode materials. (author)

  15. 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

  16. Aliovalently-Doped Garnets for Li Battery Solid State Electrolytes

    Science.gov (United States)

    Schwanz, Derek K.; Marinero, Ernesto E.

    2015-03-01

    We report on a new family of fast ionic conductivity electrolytes based on the garnet LiLaZrO. Partial substitution of Zr by aliovalent atomic species through solid state solution synthesis results in ionic conductivities 2 orders of magnitude larger than the tetragonal phase of LiLaZrO and comparable to that of its cubic phase. The synthesis temperature is 400C lower than that required for the cubic stabilization of LiLaZrO. Ongoing impovements on microstructure and film density as well as optimization of the garnet stoichiometry are expected to yield ionic conductivities surpassing the highest values reported to-date on cubic doped LiLaZrMO (Ta, Al, W, Nb)

  17. 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...

  18. 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....

  19. RHEOLOGY AND SCALING BEHAVIOR OF SWELLING CLAY DISPERSIONS

    Directory of Open Access Journals (Sweden)

    S. Chaoui

    2015-07-01

    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 (f/fg-1n, where fg captures the strength of particle interaction and n the microstructure. The scaling variable (fp/fpc-1, suggested in percolation theory to describe rheological behavior near percolation transition, acts to collapse G’ data suggesting that along lines of constant (f/fg-1 these gels are rheologically identical.

  20. 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.

  1. 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 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.

  2. Effect of a novel amphipathic ionic liquid on lithium deposition in gel polymer electrolytes

    International Nuclear Information System (INIS)

    Highlights: · Synthesis of a dimeric ionic liquid. · Gel polymer electrolytes providing uniform lithium deposit pathway. · An amphipathic ionic liquid locates at the interface between an electrolyte-rich phase and a polymer matrix in a gel polymer electrolyte. · The presence of PDMITFSI ionic liquid leads to the suppression of dendritic lithium formation on a lithium metal electrode. - Abstract: A novel dimeric ionic liquid based on imidazolium cation and bis(trifluoromethanesulfonyl) imide (TFSI) anion has been synthesized through a metathesis reaction. Its chemical shift values and thermal properties are identified via 1H nuclear magnetic resonance (NMR) imaging and differential scanning calorimetry (DSC). The effect of the synthesized dimeric ionic liquid on the interfacial resistance of gel polymer electrolytes is described. Differences in the SEM images of lithium electrodes after lithium deposition with and without the 1,1'-pentyl-bis(2,3-dimethylimidazolium) bis(trifluoromethane-sulfonyl)imide (PDMITFSI) ionic liquid in gel polymer electrolytes are clearly discernible. This occurs because the PDMITFSI ionic liquid with hydrophobic moieties and polar groups modulates lithium deposit pathways onto the lithium metal anode. Moreover, high anodic stability for a gel polymer electrolyte with the PDMITFSI ionic liquid was clearly observed.

  3. Modelling the linear viscoelastic rheological properties of bituminous binders

    OpenAIRE

    Md. Yusoff, Nur Izzi

    2012-01-01

    Rheology involves the study and evaluation of the flow and permanent deformation of time-and temperature-dependent materials, such as bitumen, that are stressed through the application of a force. The fundamental rheological properties of bituminous materials including bitumen are normally measured using a dynamic shear rheometer (DSR), from low to high temperatures. DSR is a powerful tool to measure elastic, viscoelastic and viscous properties of binders over a wide range of temperatures and...

  4. Rheological behavior of asphaltite-modified bituminous binders

    OpenAIRE

    THEMELI, Andrea; CHAILLEUX, Emmanuel; Farcas, Fabienne; Chazallon, Cyrille; DUCHEZ, Jean-Louis

    2013-01-01

    This work focuses on the rheological properties of asphaltite-modified bituminous binders. The natural asphaltite, employed to modify a petroleum-derived-bitumen, is mined in Albania. At a first time, penetration,ring ball temperature and rheological properties of both asphaltite and pure petroleum bitumen are determined. Then, the petroleum bitumen is mixed with 5, 10 and 15% of natural bitumen and the penetration and ring ball temperature of the blends are assessed. In addition to this, rhe...

  5. Rotational diffusion may govern the rheology of magnetic suspensions

    OpenAIRE

    Kuzhir, P.; Magnet, C.; Bossis, G.; Meunier, A; Bashtovoi, V.

    2011-01-01

    This paper is focused on the theoretical modeling of the rheological properties of the magnetic suspensions in shear flows under an external magnetic field aligned with the streamlines. The conventional theory postulates that the field-induced aggregates of magnetic particles are highly anisotropic and aligned with the flow direction. Therefore, no substantial variation in suspension viscosity would be expected in the presence of field. However, experiments reveal a strong Bingham rheological...

  6. Design and application of magneto-rheological fluid

    OpenAIRE

    Olabi, Abdul-Ghani; Grunwald, Artur

    2007-01-01

    Magneto-Rheological Fluid (MRF) technology is an old “newcomers” coming to the market at high speed. Various industries including the automotive industry are full of potential MRF applications. Magneto-Rheological Fluid technology has been successfully employed already in various low and high volume applications. A structure based on MRF might be the next generation in design for products where power density, accuracy and dynamic performance are the key features. Additionally, for product...

  7. 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...

  8. Analysis of Rheological Models of Selected Cement Slurries

    OpenAIRE

    Stryczek Stanislaw; Pinka Ján; Gonet Andrzej

    2004-01-01

    Cement slurries become more and more widely applicable in reinforcing and strengthening the rock mass. The processes taking place in fresh cement slurries were presented and their complex character analysed. The equations describing rheological models, e.g. cement slurries, were given. The selected cement slurries were analysed in laboratory conditions for various water-cement parameters and three temperatures. The obtained results were statistically analysed and the best fit of the rheologic...

  9. The rheological properties of silated hydroxypropylmethylcellulose tissue engineering matrices

    OpenAIRE

    Fatimi, Ahmed; Tassin, Jean-François; Quillard, Sophie; Axelos, Monique; Weiss, Pierre

    2008-01-01

    This paper describes the rheological properties of silated hydroxypropylmethylcellulose (HPMC-Si) used in biomaterials domain as a three-dimensional synthetic matrix for tissue engineering. The HPMC-Si is an HPMC grafted with 3-glycidoxypropyltrimethoxysilane (GPTMS). HPMC and HPMC-Si were studied. It is shown that although silanization reduces the hydrodynamic volume in dilute solution, it does not affect significantly the rheological behavior of the concentrated solutions. The HPMC-Si visco...

  10. Correlation between electrical and rheological measurements on sewage sludge

    OpenAIRE

    Dieudé-Fauvel, E; Baudez, J.C.; COUSSOT, P; Damme, H. Van

    2007-01-01

    In order to improve sewage sludge characterization for both dewatering and agricultural spreading, we have studied their electrical and rheological properties. On the one hand, electrical measurements give a picture of the microstructure of the material (charges, particles mobility), whereas on the other hand, rheological experiments describe its macrostructure (consistency). The interactions of the matter are the link between them. Our results showed that sludge becomes more conductive when ...

  11. Dynamics and electro-rheology of sheared immiscible fluid mixtures

    OpenAIRE

    Sakaue, Takahiro; Shitara, Kyohei; Ohta, Takao

    2014-01-01

    We analyze the electro-rheological effect in immiscible fluid mixtures with dielectric mismatch. By taking the electric field effect into account, which couples to the dynamics of domain morphology under flow, we propose a set of electro-rheological constitutive equations valid under the condition where the relative magnitude of the flow field is stronger than that of the electric field. Through the comparison with recent experiment, we point out a unique dynamical stress re...

  12. 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

  13. 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.

  14. Effect of ?-cyclodextrin on Rheological Properties of some Viscosity Modifiers

    OpenAIRE

    Rao, G. Chandra Sekhara; K.Ramadevi; K. Sirisha

    2014-01-01

    Cyclodextrins are a group of novel excipients, extensively used in the present pharmaceutical industry. Sometimes they show significant interactions with other conventional additives used in the formulation of dosage forms. The effect of ?-cyclodextrin on the rheological properties of aqueous solutions of some selected viscosity modifiers was studied in the present work. ?-cyclodextrin showed two different types of effects on the rheology of the selected polymers. In case of natural polymers ...

  15. Rheology of Wormlike Micelles : Equilibrium Properties and Shear Banding Transition

    OpenAIRE

    Berret, Jean-Francois

    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 associate...

  16. Rheology-Morphology Interrelationships for Nanocomposites based on Polymer Matrices:

    OpenAIRE

    Kulichikhin, V.; Semakov, A.; Karbushev, V.; Makarova, V.; Mendes, E.; Fisher, H; Picken, S.

    2010-01-01

    The main focus of this Chapter was targeted on novel approaches to compatibility of particles with polymer matrices and detail analysis of rheology-morphology interrelationships. Rather attractive method of mixing based on knowledge of rheological behavior of polymers at high shear rates was proposed and studied. The major fraction of ND around 40 nm and absence of agglomerates of micron dimensions allow us to recommend this method for industrial application. For successful processing of n...

  17. Rheology of dry, partially saturated and wet granular materials

    OpenAIRE

    Pakpour, M.

    2013-01-01

    This thesis is dedicated to the study of the rheology of dry, wet and partially saturated granular materials. Granular media, suspensions, emulsions, polymers and gels are ubiquitous in the chemical and materials processing industry, and despite their very different appearance, the rheology and study of the behaviour of these materials is the key to the large-scale industrial production. Granular materials are large collections of discrete particles. A granular material is called dry if th...

  18. The rheological transition in plagioclase-bearing magmas

    OpenAIRE

    Picard, David; Arbaret, Laurent; Pichavant, Michel; Champallier, Rémi; Launeau, Patrick

    2013-01-01

    Volcanological processes, such as melt segregation, ascent and eruption are directly dependent on the rheological behaviour 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 sh...

  19. Rheological Properties of HyperMacs—Long Chain Branched Analogues of Hyperbranched Polymers

    Science.gov (United States)

    Dodds, Jonathan M.; De Luca, Edoardo; Hutchings, Lian R.; Clarke, Nigel

    2008-07-01

    HyperMacs are long chain branched analogues of hyperbranched polymers, differing only in the sense that they have polymer chains, rather than monomers between branch points. Although the building blocks for HyperMacs, AB2 macromonomers, can be well-defined in terms of molecular weight and polydispersity, the nature of the coupling strategy adopted for the synthesis of the HyperMacs results in branched polymers with a distribution of molecular weights and architectures. Melt rheology showed polystyrene HyperMacs to be thermorheologically simple, obeying William-Landel-Ferry (WLF) behavior. Zero shear viscosities of the polymers were shown to increase with average molecular weight and the melts display shear thinning behavior. HyperMacs showed little evidence for relaxation by reptation and the rheological behavior agreed well with the Cayley tree model for hierarchical relaxation in tube models of branched polymers. This implies that HyperMacs exhibit architectures similar in nature to long chain branched polymers obtained commercially from metallocene catalysts.

  20. 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.

  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. Review Of Rheology Models For Hanford Waste Blending

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. C.; Stone, M.

    2013-09-26

    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; o From single source tanks that feed the qualification tanks; o 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 experie

  3. Rheological evolution of a Mediterranean subduction complex

    Science.gov (United States)

    Behr, Whitney Maria; Platt, John Paul

    2013-09-01

    We use field and microstructural observations, coupled to previously published P-T-time histories, to track the rheological evolution of an intracontinental subduction complex exposed in the Betic Cordillera in the western Mediterranean region. The body of rock we focus on, known as the Nevado-Filabride Complex (NFC), was originally part of the upper crust of the Iberian margin. It was subducted into hot asthenospheric mantle, then exhumed back toward the surface in two stages: an early stage of fast exhumation along the top of the subducting slab in a subduction channel, and a late stage of slower exhumation resulting from capture by a low-angle detachment fault rooted at the brittle-ductile transition. Each stage of deformation in the NFC was punctuated by changes in the dominant deformation mechanism. Deformation during initial subduction of the complex was accommodated by pressure-solution creep in the presence of a fluid phase - the grain sizes, stress magnitudes, and estimated strain rates for this stage are most consistent with a thin-film model for pressure solution in which the diffusion length scale is controlled by the grain size. During the early stages of exhumation within the subduction channel, deformation transitioned from pressure solution to dislocation creep due to increases in temperature, which resulted in increases in both water fugacity and grain size, each of which favor the dislocation creep mechanism. Differential stress magnitudes for this stage were ˜10 MPa, and are consistent with simple models of buoyancy-driven channel flow. With continuing subduction-channel exhumation, deformation remained within the dislocation creep field because sequestration of free water into hydrous, retrogressive minerals suppressed the pressure-solution mechanism. Differential stresses progressively increased to ˜100 MPa near the mouth of the channel during cooling as the rocks moved into mid-crustal levels. During the final, core-complex stage of exhumation, deformation was progressively concentrated into a narrow zone of highly localized strain beneath a mid-crustal detachment fault. Localization was promoted by a transition from dislocation creep to dislocation-creep-accommodated grain boundary sliding at temperatures of ˜350-380 °C, grain sizes of ˜4 ?m and differential stress magnitudes of ˜200 MPa. Peak differential stress magnitudes of ˜200 MPa recorded just below the brittle-ductile transition are consistent with Byerlee's law in the upper crust assuming a vertical maximum principal stress and near-hydrostatic pore fluid pressures. Overall, the distribution of stress with temperature, coupled to independent constraints on strain rate from field observations and geochronology, indicate that the naturally calibrated Hirth et al. (2001) flow law for wet quartzite accurately predicts the rheological behavior of mid-crustal rocks deforming by dislocation creep.

  4. Rheology and structure of thermoreversible hydrogels

    Science.gov (United States)

    Jiang, Jun

    2007-12-01

    Highly concentrated solutions of non-ionic amphiphilic triblock copolymer poly(ethylene oxide)99-poly(propylene oxide)67-poly(ethylene oxide)99 (Pluronic F127) are widely used in numerous biomedical applications, such as drug delivery vehicles, and surfactants for emulsification of food and personal care products. The Pluronic copolymers are popular for these applications, since their gelation properties are thermoreversible and easily controlled by varying the concentration. They are liquid below room temperature and gel at body temperature. Hence they are great injectable biomaterials for tissue engineering and implantation. In this dissertation, thermal gelation and structure of high concentration triblock copolymer Pluronic F127-clay (Cloisite Na+ and Lucentite SWN) aqueous solutions were characterized by rheological measurements, differential scanning calorimetry (DSC) and small angle X-ray/neutron scattering. Small angle neutron scattering (SANS), under shear using a Couette cell in radial and tangential scattering geometry, was performed to examine the structural evolution of the polymeric micellar macro-lattice formed by concentrated aqueous solutions of triblock copolymer-Pluronic F127, as a function of the shear rate. The micellar gel showed a shear thinning, i.e., a reduction of the resistance to shear, by forming a layered stacking of two-dimensional hexagonally close packed (HCP) polymer micelles. A theoretical model was developed to calculate 2D SANS scattering patterns that can be compared with the experimental data. In order to improve the mechanical properties of the gel, while still maintaining the thermo-reversibility, we synthesized multiblock structures, where the F127 construct would be repeated several times. In this manner, physical interconnections between the micelles could occur as the multiblock copolymers formed interlocking loops and tails, thereby greatly increasing the mechanical strength of the gels. The rheological and structural properties of the gels were characterized as a function of temperature, composition and degree of polymerization. For F127 solutions just below their gel point, substitution of F127 with as little as 1% multiblock succeeded in forming a physical gel. Percolation theory was used to understand the modulus growth when multiblock was added to F127 solutions just below their gel point, assuming the multiblocks form bridges between adjacent micelles.

  5. 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.

  6. 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

    2015-03-01

    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.

  7. Electrolyte Additives for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Gang, Xiao; Hjuler, H.A.; Olsen, C.A.; Berg, Rolf W.; Bjerrum, Niels

    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...

  8. 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".

  9. Engineering the Electrode-Electrolyte Interface: From Electrode Architecture to Zinc Redox in Ionic Liquid Electrolytes

    Science.gov (United States)

    Engstrom, Erika

    2011-12-01

    The electrode-electrolyte interface in electrochemical environments involves the understanding of complex processes relevant for all electrochemical applications. Some of these processes include electronic structure, charge storage, charge transfer, solvent dynamics and structure and surface adsorption. In order to engineer electrochemical systems, no matter the function, requires fundamental intuition of all the processes at the interface. The following work presents different systems in which the electrode-electrolyte interface is highly important. The first is a charge storage electrode utilizing percolation theory to develop an electrode architecture producing high capacities. This is followed by Zn deposition in an ionic liquid in which the deposition morphology is highly dependant on the charge transfer and surface adsorption at the interface. Electrode Architecture: A three-dimensional manganese oxide supercapacitor electrode architecture is synthesized by leveraging percolation theory to develop a hierarchically designed tri-continuous percolated network. The three percolated phases include a faradaically-active material, electrically conductive material and pore-former templated void space. The micropores create pathways for ionic conductivity, while the nanoscale electrically conducting phase provides both bulk conductivity and local electron transfer with the electrochemically active phase. Zn Electrodeposition: Zn redox in air and water stable N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, [C2nmm][NTf2] is presented. Under various conditions, characterization of overpotential, kinetics and diffusion of Zn species and morphological evolution as a function of overpotential and Zn concentration are analyzed. The surface stress evolution during Zn deposition is examined where grain size and texturing play significant rolls in compressive stress generation. Morphological repeatability in the ILs led to a novel study of purity in ionic liquids where it is found that surface adsorption of residual amine and chloride from the organic synthesis affect growth characteristics. The drivers of this work are to understand the processes occurring at the electrode-electrolyte interface and with that knowledge, engineer systems yielding optimal performance. With this in mind, the design of a bulk supercapacitor electrode architecture with excellent composite specific capacitances, as well as develop conditions producing ideal Zn deposition morphologies was completed.

  10. Novel Electrolytes for Lithium Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lucht, Brett L

    2014-12-12

    We have been investigating three primary areas related to lithium ion battery electrolytes. First, we have been investigating the thermal stability of novel electrolytes for lithium ion batteries, in particular borate based salts. Second, we have been investigating novel additives to improve the calendar life of lithium ion batteries. Third, we have been investigating the thermal decomposition reactions of electrolytes for lithium-oxygen batteries.

  11. Solid electrolytes general principles, characterization, materials, applications

    CERN Document Server

    Hagenmuller, Paul

    1978-01-01

    Solid Electrolytes: General Principles, Characterization, Materials, Applications presents specific theories and experimental methods in the field of superionic conductors. It discusses that high ionic conductivity in solids requires specific structural and energetic conditions. It addresses the problems involved in the study and use of solid electrolytes. Some of the topics covered in the book are the introduction to the theory of solid electrolytes; macroscopic evidence for liquid nature; structural models; kinetic models; crystal structures and fast ionic conduction; interstitial motion in

  12. Polymer gel electrolytes for lithium batteries

    International Nuclear Information System (INIS)

    The data on the most promising polymer gel electrolytes for lithium batteries published in the past decade are surveyed and described systematically. Gel electrolytes with matrices of polyethylene oxide, poly(vinylidene fluoride) and its copolymer with hexafluoropropylene, poly(methyl methacrylate), polyacrylonitrile, poly(vinyl chloride) and polyacrylates are discussed. A special section is devoted to gel electrolytes with ionic liquids as the solvents. The bibliography includes 160 references.

  13. Polymeric electrolytes based on hydrosilyation reactions

    Science.gov (United States)

    Kerr, John Borland (Oakland, CA); Wang, Shanger (Fairfield, CA); Hou, Jun (Painted Post, NY); Sloop, Steven Edward (Berkeley, CA); Han, Yong Bong (Berkeley, CA); Liu, Gao (Oakland, CA)

    2006-09-05

    New polymer electrolytes were prepared by in situ cross-linking of allyl functional polymers based on hydrosilation reaction using a multifunctional silane cross-linker and an organoplatinum catalyst. The new cross-linked electrolytes are insoluble in organic solvent and show much better mechanical strength. In addition, the processability of the polymer electrolyte is maintained since the casting is finished well before the gel formation.

  14. Effect of hydrotropic salt on the assembly transitions and rheological responses of cationic gemini surfactant solutions.

    Science.gov (United States)

    Lu, Ting; Huang, Jianbin; Li, Zihui; Jia, Shikai; Fu, Honglan

    2008-03-13

    Cationic gemini surfactant dimethylene-1,2-bis(dodecyldiethylammonium bromide), referred to as C12C2C12(Et), was synthesized. The effect of sodium salicylate (NaSal) on the assembly formation and transition of this cationic gemini surfactant solution was studied. Addition of NaSal induced rich aggregate morphologies in the C12C2C12(Et) system. The microstructures and rheological responses resulting from the addition of NaSal were studied systematically to explore the interaction between gemini surfactants and hydrotropic salts. The rich aggregation behavior can be attributed to the special molecular structure of the gemini surfactant and the appropriate interaction between the surfactant and NaSal. The study of gemini surfactant and hydrotropic salt interaction brings promise for applications in materials synthesis as soft templates. PMID:18275179

  15. Suspension of SiC Powders in Allyhydridopolycarbosilane (AHPCS): Control of Rheology

    Science.gov (United States)

    Hurwitz, Frances I.

    1998-01-01

    Inert particulate fillers can be blended with preceramic polymers prior to infiltration of composite preforms to increase pyrolysis yield and decrease shrinkage, thus reducing the number of infiltration/ pyrolysis cycles required for densification. However, particulate filler loadings and concentration of added dispersants necessary to maintain low viscosity (polymer batch. These batch to batch variations occur with alterations in the synthesis process and method of allyl substitution, which in turn alter polymer structure and molecular weight distribution. A number of different polymer batches were characterized by NMR, GPC and thermal analysis, and the influence of polymer structure on rheology of filled systems determined. When the high molecular weight fraction increased to too great a level, suitably fluid slurries could no longer be attained.

  16. Mudflow rheology in a vertically rotating flume

    Science.gov (United States)

    Holmes, Jr., Robert R.; Westphal, Jerome A.; Jobson, Harvey E.

    1990-01-01

    Joint research by the U.S. Geological Survey and the University of Missouri-Rolla currently (1990) is being conducted on a 3.05 meters in diameter vertically rotating flume used to simulate mudflows under steady-state conditions. Observed mudflow simulations indicate flow patterns in the flume are similar to those occurring in natural mudflows. Variables such as mean and surface velocity, depth, and average boundary shear stress can be measured in this flume more easily than in the field or in a traditional tilting flume. Sensitive variables such as sediment concentration, grain-size distribution, and Atterberg limits also can be precisely and easily controlled. A known Newtonian fluid, SAE 30 motor oil, was tested in the flume and the computed value for viscosity was within 12.5 percent of the stated viscosity. This provided support that the data from the flume can be used to determine the rheological properties of fluids such as mud. Measurements on mud slurries indicate that flows with sediment concentrations ranging from 81 to 87 percent sediment by weight can be approximated as Bingham plastic for strain rates greater than 1 per second. In this approximation, the yield stress and Bingham viscosity were extremely sensitive to sediment concentration. Generally, the magnitude of the yield stress was large relative to the change in shear stress with increasing mudflow velocity.

  17. 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.

  18. 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 numbers. The mechanism involves large cell distortion and film thinning, which provide favorable conditions for film rupture

  19. 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.

  20. 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.

  1. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  2. Rheology of water ices V and VI

    International Nuclear Information System (INIS)

    We have measured the mechanical strength (?) of pure water ices V and VI under steady state deformation conditions. Constant displacement rate compressional tests were conducted in a gas apparatus at confining pressures from 400 -7 -4 s-1. Most of the results fit to an empirical flow law of the form ampersand = A ?n exp (-E + PV)/RT, where the four material constants A, n, E, and I/* are (for ampersand in inverse seconds and P and ? in megapascals) 1023,0, 6.0, 136 kJ/mol, and 29 cm3/mol, respectively, for ice V; and 106,7, 4.5, 66 kJ/mol, and 11 cm3mol, respectively, for ice VI. Ice VI may weaken to a mechanism of higher E at T > 250 K. Ices V and VI are thus rheologically distinct but by coincidence have approximately the same strength under the conditions chosen for these experiments. To avoid misidentification, these tests are therfore accompanied by careful observations of the occurrences and characteristics of phase changes. One sample each of ice V and VI was quenched at pressure to metastably retain the high-pressure phase and the acquired deformation microstructures; X ray diffraction analysis of these samples confirmed the phase identification. Surface replicas of the deformed and quenched samples suggest that ice V probably deforms largely by dislocation creep, while ice VI deforms by a more complicated process involving substantial grain size reduction through recrystallization. 25 refs., 10 figs., 3 tabs

  3. 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.

  4. Rebalancing electrolytes in redox flow battery systems

    Science.gov (United States)

    Chang, On Kok; Pham, Ai Quoc

    2014-12-23

    Embodiments of redox flow battery rebalancing systems include a system for reacting an unbalanced flow battery electrolyte with a rebalance electrolyte in a first reaction cell. In some embodiments, the rebalance electrolyte may contain ferrous iron (Fe.sup.2+) which may be oxidized to ferric iron (Fe.sup.3+) in the first reaction cell. The reducing ability of the rebalance reactant may be restored in a second rebalance cell that is configured to reduce the ferric iron in the rebalance electrolyte back into ferrous iron through a reaction with metallic iron.

  5. [FTIR investigation of new polymer solid electrolytes].

    Science.gov (United States)

    Yang, Shu-ting; Chen, Hong-jun; Dong, Hong-yu; Jia, Jun-hua; Cao, Zhao-xia

    2004-04-01

    The conductivity of the porous polymer solid electrolyte blended with PVDF and PMMA, which was made by a micro-wave hot-cross-linking method, reached 2.05 x 10(-3) S x cm(-1) at room temperature. The polymer solid electrolyte was analyzed and investigated by FTIR. The results show that the PVDF, PMMA and LiClO4 in the polymer solid electrolyte were not simply blended, but certain kind of effect existed which was strengthened only when the polymer solid electrolyte came into being. PMID:15766150

  6. 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.

  7. Polymer-electrolyte water electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Moritaka [NKK Design and Engineering Corp., Yokohama (Japan); Maezawa, Shouji; Sato, Kouichi [Sanyo Corp., Osaka (Japan)

    1998-04-01

    The electricity for the electrolyzer is supplied by a variable electricity supply unit that simulates actual outputs of both series and parallel combinations of solar cells exposed to various solar intensities. An amorphous-silicon solar cell is used as a sensor for the unit. The operation was continued for more than 600 days without trouble. The case of direct connection of the solar cell and polymer electrolyte (PE) water electrolyzer is simulated: the test results show that more than 95% of the peak electricity power of the solar battery can be utilized for the electrolyzer over various solar radiation conditions. (author)

  8. Rheological behavior of hydroxyapatite and PSZ mixed slurries; Hydroxyapatite/zirconia kei kongo slurry no rheology

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Y.; Watanabe, R. [Tohoku Univ., Sendai (Japan). Graduate School; Iijima, H. [West Japan Railway Co., Ishikawa (Japan)

    1998-03-15

    Hydroxyapatite (HAp) is a kind of material excellent in affinity, while its strength is insufficient when it is used separately an implant material. Consequently, it is attempted to prepare a complex thereof with partially stabilized zirconia (PSZ) or the like that is a kind of bio-inactive but innocuous material having high strength and high tenacity. In this study, the rheological behavior of the individual HAp and PSZ, and the rheological behavior of HAp/PSZ mixed slurry are investigated as a fundamental research for the preparation of HAp/PSZ functionally graded materials. Each of HAp and PSZ has a different optimum dispersant concentration, and this value is not effected by a binder. The dispersion property of HAp/PSz mixed slurry works independently without being effected by the interactions between components, and its value depends on an effective surface area of powdery particles. Accordingly, the optimum dispersant concentration of the mixed slurry changes linearly with the volume ratio of PSZ. 14 refs., 8 figs.

  9. Intermediate Temperature Steam Electrolysis with Phosphate-Based Electrolytes

    DEFF Research Database (Denmark)

    Prag, Carsten Brorson

    2014-01-01

    Water electrolysis for hydrogen production has been predicted to get a prominent role in the energy system of the future. Current low temperature technologies rely on expensive noble metal catalysts and high temperature systems requires special construction materials to withstand the high temperatures. Electrolysis in the intermediate temperature (IT) region (200-400 °C) is of interest as it would allow for the use of non-noble metal catalysts, due to the improved kinetics, and a wide range of construction materials as a result of the more benign temperature. At these temperatures water is supplied as steam. This work centred on the design and development of a novel steam electrolysis concept based on phosphate electrolytes capable of operating in the IT range. Central for the work was the selection and evaluation of the materials and components for the test setup and cells as well as the technological issues and challenges faced. A setup suitable for intermediate temperature electrolysis has been constructed in order to accommodate testing in the IT region. This included the evaluation of multiple generations of components such as end plates and flow plates. Chemical vapour deposition of tantalum was used to protect stainless steel components from the highly oxidative environment of the oxygen side of the electrolyser. While such protection should not be necessary on the hydrogen side, it was found that the best results were obtained using tantalum coated stainless steel flow plates not only on the oxygen side but at the hydrogen side as well. Additional key steps and components for electrolysis testing are detailed in this thesis. This includes gas diffusion layers (GDL), sealing, cell assembly techniques, test operation, electrolytes and electrocatalysts. Gas diffusion layers of carbon with a PTFE bound micro-porous layer was used for the cathode side and tantalum coated stainless steel felt was used for the anode side due to the need of corrosion protection. For the cathode side a platinum electrocatalyst was used as benchmark (Pt-black ? 8 mg/cm2) and iridium oxide was used for the anode (? 3 mg/cm2). Symmetrical cell testing for hydrogen pumping at 200 _C revealed the cathode gas diffusion layers to be unstable over time. After 60 hours, the electrode resistance was more than tripled. The most prominent reason for this was thought to be a softening of the PTFE in the cathode micro-porous layer. CsH2PO4 and Sn0.9In0.1P2O7 were used as proof-of-concept electrolytes, with emphasis on the latter electrolyte. Evaluation of electrolysis cells with these electrolytes was done with a range of tools constantly under development. These tools included regression analysis of I-V curves, reference electrode measurements and electrochemical impedance spectroscopy (EIS). While reference electrode measurements were found hard to optimise, EIS, and especially complex non-linear least-square (CNLS) fitting, was found very useful. CNLS allowed for the estimation of electrolyte resistance and polarisation resistances givinga detailed view of the novel system. Electrolysis with CsH2PO4 as electrolyte revealed a need for steam on both cathode and anode in order to prevent dehydration of the electrolyte. Additional stabilisation in the form of SiC fibres was found to increase longevity considerably. Highest achieved current density was 60 mA/cm2 at 2.0 V and 250 °C. Measurements using Sn0.9In0.1P2O7 as electrolyte, Pt black as cathode electrocatalyst and IrO2 as anode electrocatalyst gave current densities as high as 313 mA/cm2 at 1.9 V and 200 °C. The stability of the electrolyte was found to be high at 200 °C and a water partial pressure of 0.05 atm. For stabilisation of the electrolyte at 250 °C a higher water partial pressure is needed. Variation of temperature from 200-250 °C showed both signs of activation of electrode processes and electrode degradation. Efforts were done to optimise the synthesis of Sn0.9In0.1P2O7 in order to establish a reproducible synthesis procedure. The synthesis used in this work required two heat

  10. Plasma electrolytic oxidation of metals

    Directory of Open Access Journals (Sweden)

    Stojadinovi? Stevan

    2013-01-01

    Full Text Available 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 determination of electron temperature, electron number density, spatial density of micro-discharges, the active surface covered by micro-discharges, and dimensional distribution of micro-discharges at various stages of PEO process. Special attention was focused on the results of the study of the morphology, chemical, and phase composition of oxide layers obtained by PEO process on aluminum, tantalum, and titanium in electrolytes containing tungsten. Physicochemical methodes: atomic force microscopy (AFM, scanning electron microscopy (SEM-EDS, x-ray diffraction (XRD, x-ray photoelectron spectroscopy (XPS, and Raman spectroscopy served as tools for examining obtained oxide coatings. Also, the application of the obtained oxide coatings, especially the application of TiO2/WO3 coatings in photocatalysis, were discussed.

  11. Complex rheological behaviors of loach (Misgurnus anguillicaudatus) skin mucus

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiang, E-mail: 11229036@zju.edu.cn; Su, Heng, E-mail: shtdyso@163.com; Lv, Weiyang, E-mail: 3090103369@zju.edu.cn; Du, Miao, E-mail: dumiao@zju.edu.cn; Song, Yihu, E-mail: s-yh0411@zju.edu.cn; Zheng, Qiang, E-mail: zhengqiang@zju.edu.cn [MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2015-01-15

    The functions and structures of biological mucus are closely linked to rheology. In this article, the skin mucus of loach (Misgurnus anguillicaudatus) was proved to be a weak hydrogel susceptible to shear rate, time, and history, exhibiting: (i) Two-region breakdown of its gel structure during oscillatory strain sweep; (ii) rate-dependent thickening followed by three-region thinning with increased shear rate, and straight thinning with decreased shear rate; and (iii) time-dependent rheopexy at low shear rates, and thixotropy at high shear rates. An interesting correlation between the shear rate- and time-dependent rheological behaviors was also revealed, i.e., the rheopexy-thixotropy transition coincided with the first-second shear thinning region transition. Apart from rheology, a structure of colloidal network was observed in loach skin mucus using transmission electron microscopy. The complex rheology was speculated to result from inter- and intracolloid structural alterations. The unique rheology associated with the colloidal network structure, which has never been previously reported in vertebrate mucus, may play a key role in the functions (e.g., flow, reannealing, lubrication, and barrier) of the mucus.

  12. 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)

  13. Toothpaste microstructure and rheological behaviors including aging and partial rejuvenation

    Science.gov (United States)

    Liu, Zhiwei; Liu, Lei; Zhou, Huan; Wang, Jiali; Deng, Linhong

    2015-08-01

    Toothpastes are mainly composed of a dense suspension of abrasive substances, flavors, and therapeutic ingredients in a background liquid of humectants and water, and usually exhibit complex rheological behaviors. However, the relationship between the rheology and microstructure of toothpaste remains to be studied. In this paper, three commonly used toothpastes, namely Colgate, Darlie and Yunnan Baiyao (Ynby), were qualitatively and quantitatively studied as soft glassy materials. We found that although the three toothpastes generally behaved in similar fashion in terms of rheology, each particular one was distinct from others in terms of the quantitative magnitude of the rheologcial properties including thixotropy, creep and relaxation, yield stress, and power-law dependence of modulus on frequency. In addition, the history-dependent effects were interpreted in terms of aging and rejuvenation phenomena, analogous to those existing in glassy systems, and Ynby seemed to result in greater extent of aging and rejuvenation as compared to the other two. All these differences in toothpaste rheology may well be attributed to the different microscopic network microstructures as observed in this study. Therefore, this study provides first evidence of microstructurebased rheological behaviors of toothpaste, which may be useful for optimizing its composition, manufacturing processing as well as end-user applications.

  14. 2012 SRNL-EM VANE RHEOLOGY RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, E.; Marzolf, A.; Hera, K.

    2012-08-31

    The vane method has been shown to be an effective tool in measuring the yield stress of both settled and mixed slurries in laboratory bench scale conditions in supporting assessments of both actual and simulant waste slurries. The vane has also been used to characterize dry powders and granular solids, the effect of non-cohesive solids with interstitial fluids and used as a guide to determine if slip is present in the geometries typically used to perform rheological flow curve measurements. The vane has been extensively characterized for measuring the shear strength in soils in both field and laboratory studies. The objectives for this task are: Fabricate vane instrument; Bench top testing to further characterize the effect of cohesive, non-cohesive, and blends of cohesive/non-cohesive simple simulants; Data from measurement of homogenized and settled bed of Kaolin sludge and assessment of the technology. In this document, the assessment using bench scale measurements of non-cohesive materials (beads) and cohesive materials (kaolin) is discussed. The non-cohesive materials include various size beads and the vane was assessed for depth and deaeration (or packing) via tapping measurements. For the cohesive (or non-Newtonian) materials, flow curves and yield stress measurements are performed using the vane and this data is compared to the traditional concentric cylinder flow curve measurement. Finally, a large scale vane was designed, fabricated, and tested with the cohesive (or non-Newtonian) materials to determine how a larger vane performs in measuring the yield stress and flow curve of settled cohesive solids.

  15. Micro and macro rheology of planar tissues.

    Science.gov (United States)

    Lokshin, Olga; Lanir, Yoram

    2009-06-01

    Tissues are intrinsically non-linear, anisotropic, viscoelastic, and undergo a process of mechanical adaptation (preconditioning). Previous constitutive laws considered one or two of these response aspects, often resulting in inadequate fit to data. Here we developed a general constitutive formulation encompassing the entire set of features. To exemplify this novel approach, constitutive equation for the skin was developed by stochastic incorporation of the fibers' orientation and undulation distributions. Predictions were contrasted with biaxial data of rabbit skin. The significance of each micro-feature was examined by sensitivity analysis. The results show that micro-structure based rheological characterization provides reliable representation under multiple biaxial protocols. Parametric investigation points to the essential roles of the fibers' orientation distributions (elastin and collagen) and waviness (collagen), their respective stress-strain relationship, and their viscoelasticity and preconditioning adaptation. The effect of ground substance is small but significant for model-to-data fit. Although the collagen is two order of magnitude stiffer, the contribution of elastin is predominant at low strains, and still significant (up to 20%) at high strains at which collagen carries the major load. The results are consistent with collagen preconditioning steming from stretch induced increase in the reference length, while in elastin it is the Mullins effect (strain softening). The most important impact of the study is that for the first time the entire scope of multi-axial tissue properties are unified in a single constitutive formulation. The potential implications are on the procedures of tissues characterization and on the design and analysis of artificial tissue scaffolds. PMID:19324407

  16. Rheological properties of confined thin films

    International Nuclear Information System (INIS)

    Shearing of monolayer and bilayer monatomic films confined between planar solid surfaces (walls) is simulated by a Monte Carlo technique in the isostress-isostrain ensemble, where temperature, number of film atoms, and applied normal stress are state variables. The walls consist of individual atoms that are identical with the film atoms and are fixed in the fcc (face centered cubic) (100) configuration. The lattice constant l of the walls is varied so that the walls are either commensurate with the (solid) film at fixed nominal lattice constant lf (i.e., l/lf=1) or homogeneously compressed (l/lff>1). Such rheological properties as shear stress Tzx and modulus are correlated with molecular structure of the layers, as reflected in translational and orientational correlation functions. If the walls are properly aligned in transverse directions, then the layers exhibit a high degree of fcc order. As such ordered films are subjected to a shear strain (by reversibly moving the walls out of alignment), they respond initially as an elastic solid: at small strains, Tzx depends linearly on the strain. As the shear strain increases, the response becomes highly nonlinear: Tzx rises to a maximum (yield point) and then decays monotonically to zero, where the maximum misalignment of the walls occurs. The correlation functions indicate that the films are not necessarily solid, even when the walls are in proper alignment. The results suggest that the principal mechanism by which disordered nonsolid films are able to resist shearing is ''pinning'': the film atoms are trapped in effective cages formed by their near neighbors and the mutual attraction of the walls for the caged atoms pins them together

  17. High-performance electrolyte in the presence of dextrose and its derivatives for aluminum electrolytic capacitors

    Science.gov (United States)

    Tsai, Ming-Liao; Lu, Yi-Fang; Do, Jing-Shan

    Dextrose and its derivatives (e.g. glucose, gluconic acid and gluconic lactone) are added to modify the characteristics of electrolytes used in aluminum electrolytic capacitors. The results show that the conductivity and sparking voltage of the electrolytes are severely affected by the concentration of dextrose gluconic acid and gluconic lactone. In addition, the pH of the electrolyte is only slightly affected by the quantity of gluconic acid and gluconic lactone. The capacitance, dissipation factor, and leakage current of capacitors impregnated with the electrolytes prepared in this work are periodically measured under storage conditions and loading at 105 °C.

  18. Identifying acid-base and electrolyte imbalances.

    Science.gov (United States)

    Gooch, Michael D

    2015-08-15

    Acid-base and electrolyte imbalances often complicate patient management in acute care settings. Correctly identifying the imbalance and its cause is vital. This article will review the physiology of acid-base and electrolyte balance, their common disturbances, associated causes, clinical manifestations, and management implications for nurse practitioners. PMID:26180912

  19. F4U production by electrolytic reduction

    International Nuclear Information System (INIS)

    As a part of the nuclear fuel cycle program developed at the Spanish Atomic Energy Commission it has been studied the electrolytic reduction of U-VI to U-IV. The effect of the materials, electrolyte concentration, pH, current density, cell size and laboratory scale production is studied. The Pilot Plant and the production data are also described. (Author) 18 refs

  20. ThO2-based solid electrolyte

    International Nuclear Information System (INIS)

    A ThO2-based fixed electrolyte contains 0.1 to 25 mol% of at least one of yttrium and magnesium oxides and 5 to 40 mol% of one of alkali earth and lanthanide oxides. The electrolyte not only has a high ion oxygen conductivity but also lower sintering interval. (J.P.)

  1. Solid composite electrolytes for lithium batteries

    Science.gov (United States)

    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.

  2. 77 FR 25406 - Consortium on “Concrete Rheology: Enabling Metrology (CREME)”: Membership Fee Update

    Science.gov (United States)

    2012-04-30

    ... From the Federal Register Online via the Government Printing Office DEPARTMENT OF COMMERCE National Institute of Standards and Technology Consortium on ``Concrete Rheology: Enabling Metrology (CREME... NIST/Industry Consortium on Concrete Rheology: Enabling Metrology (CREME)''. The notice stated...

  3. 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.

  4. 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.

  5. Rheological behavior of magnetic powder mixtures for magnetic PIM

    Science.gov (United States)

    Kim, Sung Hun; Kim, See Jo; Park, Seong Jin; Mun, Jun Ho; Kang, Tae Gon; Park, Jang Min

    2012-06-01

    Powder injection molding (PIM) is a promising manufacturing technology for the net-shape production of small, complex, and precise metal or ceramic components. In order to manufacture high quality magnets using PIM, the magneto-rheological (MR) properties of the PIM feedstock, i.e. magnetic powder-binder mixture, should be investigated experimentally and theoretically. The current research aims at comprehensive understanding of the rheological characteristics of the PIM feedstock. The feedstock used in the experiment consists of strontium ferrite powder and paraffin wax. Steady and oscillatory shear tests have been carried out using a plate-and-plate rheometer, under the influence of a uniform magnetic field applied externally. Rheological properties of the PIM feedstock have been measured and characterized for various conditions by changing the temperature, the powder fraction and the magnetic flux density.

  6. 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

  7. Nonlinear rheology of entangled polymers at turning point.

    Science.gov (United States)

    Wang, Shi-Qing

    2015-02-28

    Thanks to extensive observations of strain localization upon startup or after stepwise shear, a conceptual framework for nonlinear rheology of entangled polymers appears to have emerged that has led to discovery of many new phenomena, which were not previously predicted by the standard tube model. On the other hand, the published theoretical and experimental attempts to test the limits of the tube model have largely demonstrated that the most experimental data appear consistent with the tube-model based theoretical calculations. Therefore, the field of nonlinear rheology of entangled polymers is at a turning point and is thus a rather crucial area in which further examinations are needed. In particular, more molecular dynamics simulations are needed to delineate the detailed molecular mechanisms for the various nonlinear rheological phenomena. PMID:25606850

  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. Dielectric Relaxation and Rheological Behavior of Supramolecular Polymeric Liquid

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Nan [Shanghai Jiao Tong University, China; Wang, Yangyang [ORNL; Li, Xiaopeng [University of Akron, Akron, Ohio; Li, Haixia [Shanghai Jiao Tong University, Shanghai China; Wang, Ping [Dow Chemicals Company Limited, Shanghai China

    2013-01-01

    A model self-complementary supramolecular polymer based on thymine and diamidopyridine triple hydrogen-bonding motifs has been synthesized, and its dielectric and rheological behavior has been investigated. The formation of supramolecular polymers has been unequivocally demonstrated by nuclear magnetic resonance, electrospray ionization mass spectrometry with traveling wave ion mobility separation, dielectric spectroscopy, and rheology. The dynamical behaviors of this associating polymer generally conform to those of type-A polymers, with a low-frequency chain relaxation and a high-frequency relaxation visible in both rheological and dielectric measurements. The dielectric chain relaxation shows the ideal symmetric Debye-like shape, resembling the peculiar features of hydrogen-bonding monoalcohols. Detailed analysis shows that there exists a weak decoupling between the mechanical terminal relaxation and dielectric Debye-like relaxation. The origin of the Debye-like dielectric relaxation is further discussed in the light of monoalcohols.

  10. 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.

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

    OpenAIRE

    T.B. Petrus; J. Azuraien

    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...

  12. Study of the geopolymer restructuration by impulse rheology

    International Nuclear Information System (INIS)

    The aim of the study is to describe the evolution of the microstructure during the setting process of the geo-polymer using an original rheological method named Optimal Fourier Rheology (OFR). The alkali activation of meta-kaolin enables physicochemical transformation from a fresh paste to a hard meso-porous matrix. Classically, oscillatory rheology technique provides viscoelastic moduli spectrum and enables to determine rheological comportment of the material under investigation. However the duration to perform a complete spectrum (more than 2.5 h) makes useless this technique in the case of changing material. The OFR technique decreases the measurement duration under 10 minutes and enables to perform several snapshots of the evolving rheological behaviour. Contrary to monochromatic iterations, here the applied stress takes the form of a chirp function which contains the full usable bandwidth. Interpretations of spectrums provide efficient access to structural evolution along the setting. Results show that the number of oligomers increases into the solution due to the dissolution of the meta-kaolin leading to a constant increase of the viscoelastic parameters until the gradual appearance of the percolating networks. The gelling time was rigorously assessed by using the Winter and Chambon criterion. A fractal percolating network is formed inside the material after a reaction time depending on the formulation parameters; corresponding fractal dimensions were established. After the gel point, the viscoelastic moduli grow rapidly until geo-polymers reach a classic viscoelastic state. Structural unit size were determined using moduli curves crossover and equalled to 2.1 nm in the case of Na geo-polymer; this value fits extremely well with value previously obtained by SAXS. Finally, the elasticity becomes constant in a large frequency range and the viscous parameter strongly decreases which means that the solid porous network is under formation. In conclusion, this rheological approach gives an efficient tool to accurate the mechanisms occurring during the geo-polymerization. (authors)

  13. Structure and rheology of nanoparticle–polymer suspensions

    KAUST Repository

    Srivastava, Samanvaya

    2012-01-01

    Structure and rheology of oligomer-tethered nanoparticles suspended in low molecular weight polymeric host are investigated at various particle sizes and loadings. Strong curvature effects introduced by the small size of the nanoparticle cores are found to be important for understanding both the phase stability and rheology of the materials. Small angle X-ray scattering (SAXS) and transmission electron microscopy measurements indicate that PEG-SiO 2/PEG suspensions are more stable against phase separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions. The jamming transition is accompanied by what appears to be a unique evolution in the transient suspension rheology, along with large increments in the zero-shear, Newtonian viscosity. The linear and nonlinear flow responses of the jammed suspensions are discussed in the framework of the Soft Glassy Rheology (SGR) model, which is shown to predict many features that are consistent with experimental observations, including a two-step relaxation following flow cessation and a facile method for determining the shear-thinning coefficient from linear viscoelastic measurements. Finally, we show that the small sizes of the particles have a significant effect on inter-particle interactions and rheology, leading to stronger deviations from expectations based on planar brushes and hard-sphere suspension theories. In particular, we find that in the high volume fraction limit, tethered nanoparticles interact in their host polymer through short-range forces, which are more analogous to those between soft particles than between spherical polymer brushes. © 2012 The Royal Society of Chemistry.

  14. 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.

  15. The rheology and composition of cryovolcanic flows on icy satellites

    Science.gov (United States)

    Kargel, Jeffrey S.

    1993-01-01

    The rheologic properties of terrestrial lavas have been related to morphologic features of their flows, such as levees, banked surfaces, multilobate structures, and compressible folds. These features also have been used to determine rheologies and constrain the compositions of extraterrestrial flows. However, with rare exceptions, such features are not resolvable in Voyager images of the satellites of outer planets. Often only flow length and edge thickness of cryovolcanic flows can be measured reasonably accurately from Voyager images. The semiempirical lava-flow model presented here is a renewed effort to extract useful information from such measurements.

  16. Seismic velocity, attenuation and rheology of the upper mantle

    Science.gov (United States)

    Anderson, D. L.; Minster, J. B.

    1980-01-01

    Seismic and rheological properties of the upper mantle in the vicinity of the low-velocity zone are expressed in terms of relaxation by dislocation glide. Dislocation bowing in the glide plane explains seismic velocities and attenuation. Climbing at higher stresses for longer periods of time give the observed viscosity, and explain the low velocity and high temperature attenuation found at seismic frequencies. Due to differing parameters, separate terms for thermal, seismic and rheological lithospheres are proposed. All three lithospheres, however, are related and are functions of temperature, and must be specified by parameters such as period, stress, and stress duration.

  17. Effects of polyethyleneimine adsorption on rheology of bentonite suspensions

    Indian Academy of Sciences (India)

    A Alemdar; N Öztekin; F B Erim; Ö I Ece; N Güngör

    2005-06-01

    The influence of the cationic polymer, polyethyleneimine polymer (PEI) on the flow behaviour of bentonite suspensions (2%, w/w), was studied. XRD, zeta potential and adsorption studies were done together with rheological measurements. The addition of PEI at concentration ranges of 10-5–4.5 g/l and their rheological properties and stability of bentonite suspensions were studied. The adsorption rates for the bentonite suspensions are very fast. The XRD results showed that the PEG molecules did not intercalate into the layers of the clay.

  18. Electro-Rheological Catch/clutch:. Inertial Simulations

    Science.gov (United States)

    Johnson, A. R.; Makin, J.; Bullough, W. A.

    A high-speed reciprocating mechanism is described in order to provide the basis of a general investigation into the required properties of electro-rheological fluids and associated materials for use in flexible, inertial mechanisms. The dynamic model of this, when run for realistic existing machine requirements clearly illustrates the need for a fully integrated approach to high speed machinery design. The work sets quantified targets and draws attention to the need for the continuing development of improved electro-rheological fluids which will have high yield stresses with acceptable viscosities and the conditions they must operate under: high shear rates, centrifugal loadings and accelerations.

  19. Flow instabilities in complex fluids: Nonlinear rheology and slow relaxations

    CERN Document Server

    Aradian, A

    2003-01-01

    We here present two simplified models aimed at describing the long-term, irregular behaviours observed in the rheological response of certain complex fluids, such as periodic oscillations or chaotic-like variations. Both models exploit the idea of having a (non-linear) rheological equation, controlling the temporal evolution of the stress, where one of the participating variables (a "structural" variable) is subject to a distinct dynamics with a different relaxation time. The coupling between the two dynamics is a source of instability.

  20. Rheology of Poly(N-isopropylacrylamide)-Clay Nanocomposite Hydrogels

    Science.gov (United States)

    Lombardi, Jack; Xu, Di; Bhatnagar, Divya; Gersappe, Dilip; Sokolov, Jonathan; Rafailovich, Miriam

    2015-03-01

    The stiffness of PNIPA Gels has been reported could be significant improved by gelation with clay fillers. Here we conducted systematic rheology study of synthesized PNIPA-Clay Composites at different clay concentration, in a range from fluid to strong gel, where G'' dominant changed to G' dominant. Molecular dynamics simulation was employed to analyze the structure of composites and corresponding mechanical changes with increased clays. Where we found viscoelastic behavior become significant only 1.5 times above percolation threshold. The yield stress extrapolated from our rheology results shows good fitting to modified Mooney's theory of suspension viscosity.

  1. Electrical conductivity and rheology of carbon black composites under elongation

    Science.gov (United States)

    Starý, Zden?k

    2015-04-01

    Electrical properties of conductive polymer composites are governed by filler particle structures which are formed in the material during the mixing. Therefore, knowledge of the behavior of conductive particle structures under defined conditions of deformation is necessary to produce materials with balanced electrical and rheological properties. Whereas the electrical conductivity evolution under shear can be nowadays studied even with the commercial rheometers, the investigations under elongation were not performed up to now. In this work simultaneous electrical and rheological measurements in elongation on polystyrene/carbon black composites are introduced. Such kind of experiment can help in understanding the relationships between processing conditions and properties of conductive polymer composites.

  2. Characterization of long-chain branching effects in linear rheology

    OpenAIRE

    Thimm, Wolfgang; Friedrich, Christian; Roths, Tobias; Trinkle, Stefan; Honerkamp, Josef

    2000-01-01

    This is the last part of a series of five articles published in Journal of Rheology (Maier et al. (1998), Thimm et al. (1999a), Thimm et al. (2000a), Thimm et al. (2000c)) in which progress on the determination of binary molecular weight distributions from rheological data has been reported. In this article is discussed in how far the developed methods can also be used to characterize long-chain branching effects. Monomodal samples which contain long-chain branches will sh...

  3. 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.

  4. Rheological Study of Mutarotation of Fructose in Anhydrous State

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yangyang [ORNL; Wlodarczyk, Patryk [Institute ofNon-Ferrous Metals, Sowinskiego Gliwice, POLAND; Sokolov, Alexei P [ORNL; Paluch, Marian W [ORNL

    2013-01-01

    Rheological measurement was employed to study the mutarotation of D-fructose in anhydrous state. By monitoring the evolution of shear viscosity with time, rate constants for mutarotation were estimated, and two different stages of this reaction were identified. One of the mutarotation stages is rapid and has a low activation energy, whereas the other is much slower and has a much higher activation energy. Possible conversions corresponding to these two phases are discussed. This work demonstrates that, in addition to the routine techniques such polarimetry and gas liquid chromatography, rheological measurement can be used as an alternative method to continuously monitor the mutarotation of sugars.

  5. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and Testing of Planar Single Cells. During this time period substantial progress has been made in developing low temperature deposition techniques to produce dense, nanocrystalline yttrium-stabilized zirconia films on both dense oxide and polymer substrates. Progress has been made in the preparation and characterization of thin electrolytes and porous LSM substrates. Both of these tasks are essentially on or ahead of schedule. In our proposal, we suggested that the ZrO{sub 2}/Sc system needed to be considered as a candidate as a thin electrolyte. This was because microcrystalline ZrO{sub 2}/Sc has a significantly higher ionic conductivity than YSZ, particularly at the lower temperatures. As a result, some 0.5 micron thick film of ZrO{sub 2}/16% Sc on an alumina substrate (grain size 20nm) was prepared and the electrical conductivity measured as a function of temperature and oxygen activity. The Sc doped ZrO{sub 2} certainly has a higher conductivity that either 20nm or 2400nm YSZ, however, electronic conductivity dominates the conductivity for oxygen activities below 10{sup -15}. Whereas for YSZ, electronic conductivity is not a problem until the oxygen activity decreases below 10{sup -25}. These initial results show that the ionic conductivity of 20nm YSZ and 20nm ZrO{sub 2}/16% Sc are essentially the same and the enhanced conductivity which is observed for Sc doping in microcrystalline specimens is not observed for the same composition when it is nanocrystalline. In addition they show that the electronic conductivity of Sc doped ZrO{sub 2} is at least two orders of magnitude higher than that observed for YSZ. The conclusion one reaches is that for 0.5 to 1 micron thick nanocrystalline films, Sc doping of ZrO{sub 2} has no benefits compared to YSZ. As a result, electrolyte films of ZrO{sub 2}/Sc should not be considered as candidates. However, they have the potential of being useful as an interface on the anode side of the electrolyte. NexTech has focused much of its effort during the past few months on establishing tape casting methods for porous LSM substrates. This work, performed under a separate DOE-funded program, involved tape casting formulations comprising LSM powders with bi-modal particle size distributions and fugitive pore forming additives. Sintered LSM substrates with porosities in the 30 to 40 vol% range, and pore sizes of 10 {approx} 20 microns have been prepared. In addition, tape casting formulations involving composite mixtures of LSM and Sm-doped ceria (SDC) have been evaluated. The LSM/SDC cathode substrates are expected to provide better performance at low temperatures. Characterization of these materials is currently underway.

  6. Introducing Students to Rheological Classification of Foods, Cosmetics, and Pharmaceutical Excipients Using Common Viscous Materials

    Science.gov (United States)

    Faustino, Ce´lia; Bettencourt, Ana F.; Alfaia, Anto´nio; Pinheiro, Lídia

    2015-01-01

    Rheological measurements are very important tools for the characterization of the flow and deformation of a material, as well as for optimization of the rheological parameters. The application and acceptance of pharmaceutical formulations, cosmetics, and foodstuffs depends upon their rheological characteristics, such as texture, consistency, or…

  7. Relations between rheological and textural characteristics of yoghurt-modified mayonnaise.

    Czech Academy of Sciences Publication Activity Database

    Štern, Petr; Pokorný, J.; Panovská, Z.

    Hersonisos : European Society of Rheology, 2006. s. 177. [Annual European Rheology Conference AERC 2006 /3./. 27.04.2006-29.04.2006, Hersonisos, Crete] R&D Projects: GA AV ?R IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : yoghurt -modified mayonnaise * rheology * viscoelasticity * sensory analysis * texture Subject RIV: BK - Fluid Dynamics

  8. 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.

  9. Solid polymer electrolytes based on alternating copolymers of vinyl ethers with methoxy oligo(ethyleneoxy)ethyl groups and vinylene carbonate

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis of alternating copolymers of vinyl ethers and vinylene carbonate. • Preparation of polymer electrolytes based on the alternating copolymers with LiTFSI. • Structure-property relationship for alternating copolymers-based electrolytes. • Interfacial stability between polymer electrolytes with lithium metal electrode. - Abstract: Alternating copolymers (poly(1a-g-alt-VC)) of vinyl ethers with various methoxy oligo(ethyleneoxy)ethyl groups and vinylene carbonate (VC) were prepared, and the thermal and electrochemical properties of their polymer electrolytes with LiTFSI and interfacial stability between the polymer electrolyte and Li metal electrode were investigated. Tg's increased linearly with salt contents, and decreased with an increase in the chain length of methoxy oligo(ethyleneoxy)ethyl groups in the vinyl ethers at constant salt concentration. The slopes of Tg vs. [Li]/[O] were identical, independent of the polymer structure. The ionic conductivities of the polymer electrolytes increased with increasing the side-chain ethyleneoxy (EO) unit length of the vinyl ether unit in the alternating copolymers, and also their temperature dependences became relatively smaller in the polymer electrolytes having longer EO units in the vinyl ethers. The highest ionic conductivity, 1.2 × 10−4 S/cm at 30 °C, was obtained in the alternating copolymer with a side-chain EO unit length of 23.5 in the vinyl ether unit. Ion transport coupled with the segmental motion of the polymer is dominant in these polymer electrolytes. Interfacial resistance increased gradually with contact time, indicative of the formation of passivation films on the Li metal electrode. These polymer electrolytes are thermally stable and have large electrochemical windows of use

  10. 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.)

  11. 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

  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. The buffer effect in neutral electrolyte supercapacitors

    DEFF Research Database (Denmark)

    Thrane Vindt, Steffen; Skou, Eivind M.

    2016-01-01

    The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading to a...... change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact...

  14. Reserve, flowing electrolyte, high rate lithium battery

    Science.gov (United States)

    Puskar, M.; Harris, P.

    Flowing electrolyte Li/SOCl2 tests in single cell and multicell bipolar fixtures have been conducted, and measurements are presented for electrolyte flow rates, inlet and outlet temperatures, fixture temperatures at several points, and the pressure drop across the fixture. Reserve lithium batteries with flowing thionyl-chloride electrolytes are found to be capable of very high energy densities with usable voltages and capacities at current densities as high as 500 mA/sq cm. At this current density, a battery stack 10 inches in diameter is shown to produce over 60 kW of power while maintaining a safe operating temperature.

  15. Electrolytic orthoborate salts for lithium batteries

    Science.gov (United States)

    Angell, Charles Austen [Mesa, AZ; Xu, Wu [Tempe, AZ

    2009-05-05

    Orthoborate salts suitable for use as electrolytes in lithium batteries and methods for making the electrolyte salts are provided. The electrolytic salts have one of the formulae (I). In this formula anionic orthoborate groups are capped with two bidentate chelating groups, Y1 and Y2. Certain preferred chelating groups are dibasic acid residues, most preferably oxalyl, malonyl and succinyl, disulfonic acid residues, sulfoacetic acid residues and halo-substituted alkylenes. The salts are soluble in non-aqueous solvents and polymeric gels and are useful components of lithium batteries in electrochemical devices.

  16. Rheology of defatted ultrafiltration-diafiltration soy proteins

    Science.gov (United States)

    The linear and non-linear rheological properties of defatted soy proteins produced by ultrafiltration-diafiltration were investigated at three temperatures. Five concentrations ranging from 10% to 30% of the defatted ultrafiltered-diafiltered (DUD) soy proteins were prepared. The properties of DUD...

  17. Topics in macro and micro rheology of blood

    International Nuclear Information System (INIS)

    Introduction Blood and blood vessels: general morphological, physiological, and physicochemical aspects of the cardiovascular system and blood tissue. Chapter I: Deformation and laminar flow of Newtonian and non-Newtonian materials in tubes with rigid walls. Turbulent flows in tubes. Blood flow in tubes with non-extensible walls: stationary flow and oscillating flow of an equivalent homogeneous continuum.Chapter II: Propagation of pressure pulses in tubes with visco-elastic walls. Pulse propagation in arterioles in laminar regimes and in arteries in laminar and turbulent regimes. Chapter III: Deformation and laminar flow of suspensions in tubes of inextensible walls. Macro-rheology of blood. Non-equilibrium thermodynamics and blood flow in vessels. Axial accumulation of blood cells.Chapter IV: The micro-rheological point of view in the study of laminar and oscillating flows of suspensions in tubes of rigid walls. Blood micro-rheology.Conclusions: Some comments about the biological and medical importance of the biophysical study of the macro and micro rheology of blood

  18. 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 EU Projects: European Commission(XE) 315233 Institutional support: RVO:61389013 Keywords : rheology * chitosan solutions * chitin nanofibrils Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.074, year: 2014

  19. Rheological properties of nanofiltered Athabasca bitumen and Maya crude oil.

    Czech Academy of Sciences Publication Activity Database

    Hasan, M.D.A.; Fulem, Michal; Bazyleva, A.; Shaw, J.M.

    2009-01-01

    Ro?. 23, - (2009), s. 5012-5021. ISSN 0887-0624 Institutional research plan: CEZ:AV0Z10100521 Keywords : viscosity * rheology * Athabasca bitumen * Maya crude oil * phase behavior * asphaltenes * nanofiltration Subject RIV: JJ - Other Materials Impact factor: 2.319, year: 2009

  20. Pasting and rheological properties of quinoa-oat composites

    Science.gov (United States)

    Quinoa (Chenopodium, quinoa) flour, known for its essential amino acids, was composited with oat products containing ß-glucan known for lowering blood cholesterol and preventing heart disease. Quinoa-oat composites were developed and evaluated for their pasting and rheological properties by a Rapid ...

  1. 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.

  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. Monitoring structural and rheologic properties of petroleum-based solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kasperskii, B.V.; Chistyakov, B.Y.; Krut, V.V.; Pen' kov, A.I.; Shishkov, S.N.; Vakhrushev, L.P.

    1981-01-01

    Investigation results are presented of the effect of products of interaction of carboxylic acid and polyethylene-polyamines on the structural and rheologic properties of petroleum-based muds. Also shown is the possibility of lowering viscosity and static shear stress of lime-bituminous solutions by use of indicated additives in the amount of up to 0.5 of percent by volume.

  4. Basic Properties of Gel-Structured Electro-Rheological Fluids

    Science.gov (United States)

    Kakinuma, Y.; Aoyama, T.; Anzai, H.; Isobe, K.; Tanaka, K.

    Electra-rheological fluids (ERFs) are composed of a functional fluid and colloidal suspension. Their rheological properties vary rapidly and reversibly with the applied electric field intensity. ERFs are mixtures of nonconductive silicone oil and inorganic/organic composite electro-rheological particles. Investigations into the properties of ERFs have led to remarkable advances in their performance in recent years. However, ERFs exhibit an undesirable property that obstructs the long-term use of ERF devices, namely the sedimentation and separation of ER particles from the silicone oil. The sedimentation of ER particles reduces the electro-rheological effect. In order to suppress the sedimentation and thereby improve the performance of ERF devices, a new functional material called Gel Structured ERF (ERG) is developed and its basic properties are analyzed in this study. The ER particles are sustained in the gel component, and thus will not precipitate out. This suppresses the decrease in ER effect associated with precipitation. The developed ERG shows large shear stress variation in response to the applied electric field. This high performance of ERGs involves a different mechanism than that observed in ERFs. In order to elucidate the mechanism in ERGs, the behavior of ER particles was observed under an electric field. Conditions at the interface between the electrode and ERG were found to change rapidly in response to the applied electric field, resulting in the variation of shear force.

  5. Electro-rheology fluids and liquid fuel flow

    Science.gov (United States)

    Tao, Rongjia

    1993-10-01

    The goals of this research are to: understand and clarify the physical mechanism underlying the electro-rheological (ER) phenomenon, such as viscosity, the structure of ER fluids, phase transitions, and properties; apply the ER phenomenon to fuels to control viscosity; and study cryogenic ER fluids and investigate applications of the ER effect to slurry rocket fuels.

  6. Rheological properties of whey proteins concentrate before and

    Directory of Open Access Journals (Sweden)

    Zoran Herceg

    2001-04-01

    Full Text Available 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 severalcarboxymethylcellulose hydrocolloids addition in such systems.Measurements were done using rotational viscosimeter, Brookfield DV-III at temperature 20 oC. The rheological parameters were determined by powerlaw model. The results of investigation have shown that all investigated systems are non-Newtonian. Depending on the pretreatment of whey proteins and the mass fractions of hydrocolloids they exhibited pseudoplastic or dilatant properties.Particle size analysis was performed using Fritsch – laser particle sizer “analysette 22”. The operation of tribomechanical micronization caused the decreasing of particle size and incrasing specific area of whey proteins. Tribomechanical treatment of whey proteins had significant influence on the rheological parameters and the type of flowing.

  7. The Role of Apparent Wall Slip Effect in Experimental Rheology.

    Czech Academy of Sciences Publication Activity Database

    Ve?e?, M.; P?nkavová, V?ra; Wein, Ond?ej

    Frankfurt : DECHEMA, 2011, P14.07. ISBN N. [European Congress of Chemical Engineering /8./. Berlin (DE), 25.09.2011-29.09.2011] R&D Projects: GA ?R GA104/09/0972 Institutional research plan: CEZ:AV0Z40720504 Keywords : rheology * apparent wall slip effect * solid surface Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  8. Rheological properties of chitosan solutions filled with chitin nanofibrils.

    Czech Academy of Sciences Publication Activity Database

    Mikešová, Jana; Tishchenko, Galina; Morganti, P.

    Pisa : University of Pisa, Department of Civil and Industrial Engineering , 2013, s. 44-45. [Workshop Green Chemistry and Nanotechnologies in Polymer Chemistry /4./. Pisa (IT), 04.09.2013-06.09.2013] EU Projects: European Commission(XE) 315233 Institutional support: RVO:61389013 Keywords : chitosan solution * chitin nanofibrils * rheology Subject RIV: CD - Macromolecular Chemistry

  9. Rheological Properties of Liquid and Particle Stabilized Foam

    Science.gov (United States)

    Özarmut, A. Ö.; Steeb, H.

    2015-04-01

    In Earth-Pressure-Balance (EPB) tunnelling the excavated ground is used as face support medium to prevent surface settlements. In general, the excavated ground (e.g. for cohesionless soils) does not exhibit suitable conditions to support the tunnelling face. This technical challenge can be solved by adding conditioning agents that are mainly foams. In order to physically understand the rheological properties of the (added) liquid foam and the foam-soil (foam-particle) mixture and to comprehend its influence on the soil, advanced rheological investigations are necessary. Therefore, rheological experiments such as flow curve tests have been performed to determine the effective yield stress. Since the morphology, i.e. the microstructure of the foam accounts for effective rheological properties, size, shape and distribution of the cells of the foam and particle-laden foam were characterized in detail applying imaging techniques. In order to perform the above mentioned experiments, polymer- stabilised shaving foam seems to be a good replacement of tunnelling foam and suitable for laboratory tests due to its time stability, characteristic length scales of the microstructure and accessibility. Glass beads (of different diameter and volume fractions, i.e. specific surface areas) are used to investigate the effective material behaviour of foam-particle mixtures. The experimental results are compared with yield stress models of modified Herschel-Bulkley- Papanastasiou type.

  10. Computer simulation studies of the rheology of soft condensed matter

    International Nuclear Information System (INIS)

    Full text: The rheology of soft condensed matter systems, such as polymer melts, polymer solutions and colloidal dispersions, is a subject of enduring interest - not only because of its importance in materials processing technology, but also because of the fascinating theoretical challenges it presents. Many of the rheological features possessed by these systems, such as normal stress differences, non-Newtonian viscosity and elasticity, are spectacularly evident on the macroscopic scale, but these properties are also crucial to emerging modern technologies such as micro- and nano-fluidics. Over the last seven years, we have studied many different aspects of the rheology of soft condensed matter systems using non-equilibrium molecular dynamics computer simulation techniques. Of particular importance, has been our development of a new algorithm for studying elongational flow, a comparison of the planar elongational and shear flow rheology of molecular fluids, our examination of the approach to the Brownian limit in colloidal fluids, and our detailed investigation of the concentration dependence of the viscosity and normal stress differences in short-chain polymer solutions. In this paper, we review the results of these investigations, discuss the current capabilities and limitations of non-equilibrium molecular dynamics simulations, and discuss our current work and future directions

  11. Dense granular flow rheology in turbulent bedload transport

    CERN Document Server

    Maurin, Raphael; Frey, Philippe

    2016-01-01

    The local granular rheology is investigated numerically in idealised turbulent bedload transport configurations. Using a coupled fluid-discrete element model, the stress tensor is computed as a function of the depth for a series of simulations varying the Shields number, the specific density and the particle diameter. The results are analyzed in the framework of the $\\mu(I)$ rheology and exhibit a collapse of both the shear to normal stress ratio and the solid volume fraction over a wide range of inertial numbers. The effect of the interstitial fluid on the granular rheology is shown to be negligible, supporting recent work suggesting the absence of a clear transition between the free-fall and the turbulent regime. In addition, the data collapse is observed up to unexpectedly high inertial numbers $I\\sim2$, challenging the existing conceptions and parametrization of the $\\mu(I)$ rheology. Focusing upon bedload transport modelling, the results are pragmatically analyzed in the $\\mu(I)$ framework in order to pr...

  12. 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 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.

  13. Rheological and Sensory Characteristics of Yoghurt-Modified Mayonnaise.

    Czech Academy of Sciences Publication Activity Database

    Štern, Petr; Pokorný, J.; Šedivá, A.; Panovská, Z.

    2008-01-01

    Ro?. 26, ?. 3 (2008), s. 190-198. ISSN 1212-1800 R&D Projects: GA AV ?R IAA2060404 Institutional research plan: CEZ:AV0Z20600510 Keywords : mayonnaise * rheology * sensory analysis * texture * yoghurt Subject RIV: BK - Fluid Dynamics Impact factor: 0.472, year: 2008

  14. 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.

  15. 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)

  16. 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.

  17. Rheology of Lignocellulose Suspensions and Impact of Hydrolysis: A Review.

    Science.gov (United States)

    Nguyen, Tien Cuong; Anne-Archard, Dominique; Fillaudeau, Luc

    2015-01-01

    White biotechnologies have several challenges to overcome in order to become a viable industrial process. Achieving highly concentrated lignocellulose materials and releasing fermentable substrates, with controlled kinetics in order to regulate micro-organism activity, present major technical and scientific bottlenecks. The degradation of the main polymeric fractions of lignocellulose into simpler molecules is a prerequisite for an integrated utilisation of this resource in a biorefinery concept. The characterisation methods and the observations developed for rheology, morphology, etc., that are reviewed here are strongly dependent on the fibrous nature of lignocellulose, are thus similar or constitute a good approach to filamentous culture broths. This review focuses on scientific works related to the study of the rheological behaviour of lignocellulose suspensions and their evolution during biocatalysis. In order to produce the targeted molecules (synthon), the lignocellulose substrates are converted by enzymatic degradation and are then metabolised by micro-organisms. The dynamics of the mechanisms is limited by coupled phenomena between flow, heat and mass transfers in regard to diffusion (within solid and liquid phases), convection (mixing, transfer coefficients, homogeneity) and specific inhibitors (concentration gradients). As lignocellulose suspensions consist of long entangled fibres for the matrix of industrial interest, they exhibit diverse and complex properties linked to this fibrous character (rheological, morphological, thermal, mechanical and biochemical parameters). Among the main variables to be studied, the rheological behaviour of such suspensions appears to be determinant for process efficiency. It is this behaviour that will determine the equipment to be used and the strategies applied (substrate and biocatalysis feed, mixing, etc.). This review provides an overview of (i) the rheological behaviour of fibrous materials in suspension, (ii) the methods and experimental conditions for their measurements, (iii) the main models used and (iv) their evolution during biocatalytic reactions with a focus on enzymatic hydrolysis. PMID:25786712

  18. 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.

  19. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  20. 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

  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. 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.

  3. 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

  4. Block-Copolymer Lithium Battery Electrolytes

    Science.gov (United States)

    Eitouni, Hany

    2011-03-01

    With high energy density at low cost, Li ion has become the most prevalent portable rechargeable battery chemistry in the world. As demand for smaller and lighter batteries grows, the energy density limitation of Li ion batteries presents a significant hurdle. Pushing the existing Li ion platform to higher energy densities compromises lifetime and safety, and these have emerged as the most pressing challenges in today's industry. The weakest link in terms of safety and stability of Li ion batteries is the organic liquid electrolyte that facilitates ionic transport between the electrodes. The continuous electrochemical degradation of the electrolyte at the electrodes causes poor cycle life of the batteries, and in some cases, runaway reactions that lead to explosions. Dry polymer electrolytes coupled to Li metal anodes had been considered a high energy alternative to liquid-based systems, as the solid-solid interface promised to alleviate the stability problems of the liquid electrolyte. However, repeated cycling of Li metal anodes leads to dendrite formation, reducing battery life and compromising safety. Recent theoretical work indicates that dendrite growth can be stopped if the shear modulus of current polymer electrolytes can be increased by three orders of magnitude without a significant decrease in ionic conductivity. Thus, the mechanical properties of polymer electrolytes are particularly important in rechargeable solid-state lithium batteries. Because ion transport in polymers is coupled to the motion of the molecules that are solvating the ions, the presence of mobile molecules is essential to allow for a conductive medium. However, the same mobility of molecules is detrimental to the polymer's structural integrity. There is, thus, a clear need to develop methodologies for decoupling the conductive and mechanical properties of polymer electrolytes. Electrolytes comprised of self-assembled block-copolymer nanostructures overcome this principal constraint.

  5. Production of electrolyte membranes for ZEBRA batteries

    OpenAIRE

    Mercadelli, Elisa; Capiani, Claudio; Sanson, Alessandra

    2012-01-01

    ZEBRA batteries (Zero Emission Battery Research Activities), are one of the possible solutions to electrical storage for stationary applications due to their high energy and power density. These systems are based on nickel-sodium chloride cells operating at high temperatures (about 270-350?C), and that rely on a ceramic ?"-alumina tube or planar membrane as solid electrolyte. The ceramic process needed to produce the electrolytic compartment has a key role to enhance and adapt the batter...

  6. 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...

  7. 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...

  8. 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

  9. Boron Clusters as Highly Stable Magnesium-Battery Electrolytes**

    Science.gov (United States)

    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W

    2014-01-01

    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electrolytes is very high. PMID:24519845

  10. Boron clusters as highly stable magnesium-battery electrolytes.

    Science.gov (United States)

    Carter, Tyler J; Mohtadi, Rana; Arthur, Timothy S; Mizuno, Fuminori; Zhang, Ruigang; Shirai, Soichi; Kampf, Jeff W

    2014-03-17

    Boron clusters are proposed as a new concept for the design of magnesium-battery electrolytes that are magnesium-battery-compatible, highly stable, and noncorrosive. A novel carborane-based electrolyte incorporating an unprecedented magnesium-centered complex anion is reported and shown to perform well as a magnesium-battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium-battery electrolytes is very high. PMID:24519845

  11. Kinetics of isothermal crystallization in isotactic polypropylene monitored with rheology and Fourier-transform rheology

    International Nuclear Information System (INIS)

    Linear and Fourier-transform rheology were used to study the influence of the oscillatory shear amplitude, ?0, on the isothermal crystallization at 140 deg. C of three commercial isotactic polypropylenes. The development of the crystallization was monitored through the time dependence of the dynamic storage modulus, G'(t), and the normalized intensity of the third harmonic of the stress waveform, I3 (t), a quantification of the degree of nonlinearity under oscillatory shear conditions. A change in the exponent, n, of the power law describing growth, according to Gnorm '(t) ? tn, was observed at t ? 4 h. For t 3 (t). Below ?0 0.05, these results were independent of the applied strain amplitude. Above ?0 = 0.05, failure of the polypropylene in the parallel plate geometry due to stress build-up was often observed in the late stages of crystallization. This was accompanied by a sharp decrease of G'(t), and a simultaneous sharp increase of I3 (t). Additionally, the presence of even harmonics in the spectrum was observed after failure. Notably, a plateau of I3 (t) at least 1 h before actual failure indicating a greater sensitivity to its onset than that of G'(t)

  12. Extensional Rheology Experiment Developed to Investigate the Rheology of Dilute Polymer Solutions in Microgravity

    Science.gov (United States)

    Logsdon, Kirk A.

    2001-01-01

    A fundamental characteristic of fluid is viscosity; that is, the fluid resists forces that cause it to flow. This characteristic, or parameter, is used by manufacturers and end-users to describe the physical properties of a specific material so that they know what to expect when a material, such as a polymer, is processed through an extruder, a film blower, or a fiber-spinning apparatus. Normally, researchers will report a shear viscosity that depends on the rate of an imposed shearing flow. Although this type of characterization is sufficient for some processes, simple shearing experiments do not provide a complete picture of what a processor may expect for all materials. Extensional stretching flows are common in many polymer-processing operations such as extrusion, blow molding, and fiber spinning. Therefore, knowledge of the complete rheological (ability to flow and be deformed) properties of the polymeric fluid being processed is required to accurately predict and account for the flow behavior. In addition, if numerical simulations are ever able to serve as a priori design tools for optimizing polymer processing operations such as those described above, an accurate knowledge of the extensional viscosity of a polymer system and its variation with temperature, concentration, molecular weight, and strain rate is critical.

  13. 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

  14. High Lithium Transference Number Electrolytes via Creation of 3-Dimensional, Charged, Nanoporous Networks from Dense Functionalized Nanoparticle Composites

    KAUST Repository

    Schaefer, Jennifer L.

    2013-03-26

    High lithium transference number, tLi+, electrolytes are desired for use in both lithium-ion and lithium metal rechargeable battery technologies. Historically, low tLi+ electrolytes have hindered device performance by allowing ion concentration gradients within the cell, leading to high internal resistances that ultimately limit cell lifetime, charging rates, and energy density. Herein, we report on the synthesis and electrochemical features of electrolytes based on nanoparticle salts designed to provide high tLi+. The salts are created by cofunctionalization of metal oxide nanoparticles with neutral organic ligands and tethered lithium salts. When dispersed in a conducting fluid such as tetraglyme, they spontaneously form a charged, nanoporous network of particles at moderate nanoparticle loadings. Modification of the tethered anion chemistry from -SO3 - to -SO3BF3 - is shown to enhance ionic conductivity of the electrolytes by facilitating ion pair dissociation. At a particle volume fraction of 0.15, the electrolyte exists as a self-supported, nanoporous gel with an optimum ionic conductivity of 10 -4 S/cm at room temperature. Galvanostatic polarization measurements on symmetric lithium metal cells containing the electrolyte show that the cell short circuit time, tSC, is inversely proportional to the square of the applied current density tSC ∼ J-2, consistent with previously predicted results for traditional polymer-in-salt electrolytes with low tLi+. Our findings suggest that electrolytes with tLi+ ≈ 1 and good ion-pair dissociation delay lithium dendrite nucleation and may lead to improved lithium plating in rechargeable batteries with metallic lithium anodes. © 2013 American Chemical Society.

  15. Electrolytic hydrogen in beta titanium

    International Nuclear Information System (INIS)

    Permeation of electrolytic hydrogen through beta titanium foils with palladium coated surfaces was studied using Ti--11.5 Mo--6 Zr--4.5 Sn. Ion bombardment etching followed by thin film vapor deposition of palladium were used to produce oxide-free titanium specimens for electrochemical hydrogen permeation and embrittlement studies. A thin metallic foil is cathodically charged with hydrogen on one side while the other side is maintained at a sufficiently anodic potential so that all the diffusing hydrogen is oxidized and turned into an equivalent current. The current is analyzed to determine diffusivity and solubility of hydrogen. X-ray diffraction was also used to determine the effects of hydrogen on the lattice parameter. Permeation experiments conducted with basic cyanide solutions exhibited simple diffusion behavior. The diffusivity at 210C for hydrogen through the beta alloy was 5.60 (+-1.92) x 10-7 cm2/s. Anomalous permeation occurred with hydrogen chemical potentials in acidic and basic solutions without cyanide during the later stages of the approach to steady state in the charging. This behavior is consistent with the trapping model of hydrogen in metals of McNabb and Foster. Plastic deformation and spontaneous cracking at the wetted portion of the specimen were observed under extreme conditions during this anomalous behavior. Part of the deformation is found to be reversible. In the mandrel bend experiments on the embrittlement phenomenon, the transgranular cleavage mode of fracture occurred. Interstitially dissolved hydrogen expanded the bcc lattice of the beta titanium with accompanying diffraction line broadening. The lattice contracted upon removal of the hydrogen. The satisfactory performance of the beta alloy Ti--11.5 Mo--6 Zr--4.5 Sn, in moderate electrochemical environments results principally from the protective oxide film

  16. 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 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.

  17. Ferrate(VI) synthesis at boron-doped diamond anode

    OpenAIRE

    ?ekerevac Milan; Nikoli?-Bujanovi? Ljiljana; Joki? Anja; Simi?i? Miloš

    2013-01-01

    The oxidation of iron compounds from alkaline 10 M KOH electrolytes on a boron doped diamond electrode is examined by cyclic voltammetry between the potentials of hydrogen evolution reaction and oxygen evolution reaction, due to ferrate(VI) electrochemical synthesis. It is shown that the anodic current peak that appears in iron free electrolyte at a less positive potential than the potential of oxygen evolution probably coincides with oxidation of hydrogen in >CH2 groups and C-sp2 gr...

  18. Tailoring disorder and dimensionality: strategies for improved solid oxide fuel cell electrolytes.

    Science.gov (United States)

    Garcia-Barriocanal, Javier; Rivera-Calzada, Alberto; Varela, Maria; Sefrioui, Zouhair; Díaz-Guillén, Mario R; Moreno, Karla J; Díaz-Guillén, José A; Iborra, Enrique; Fuentes, Antonio F; Pennycook, Stephen J; Leon, Carlos; Santamaria, Jacobo

    2009-05-11

    Reducing the operation temperature of solid oxide fuel cells is a major challenge towards their widespread use for power generation. This has triggered an intense materials research effort involving the search for novel electrolytes with higher ionic conductivity near room temperature. Two main directions are being currently followed: the use of doping strategies for the synthesis of new bulk materials and the implementation of nanotechnology routes for the fabrication of artificial nanostructures with improved properties. In this paper, we review our recent work on solid oxide fuel cell electrolyte materials in these two directions, with special emphasis on the importance of disorder and reduced dimensionality in determining ion conductivity. Substitution of Ti for Zr in the A(2)Zr(2-) (y)Ti(y)O(7) (A = Y, Dy, and Gd) series, directly related to yttria stabilized zirconia (a common fuel cell electrolyte), allows controlling ion mobility over wide ranges. In the second scenario we describe the strong enhancement of the conductivity occurring at the interfaces of superlattices made by alternating strontium titanate and yttria stabilized zirconia ultrathin films. We conclude that cooperative effects in oxygen dynamics play a primary role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity. PMID:19330781

  19. 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.

  20. Additives-containing functional electrolytes for suppressing electrolyte decomposition in lithium-ion batteries

    International Nuclear Information System (INIS)

    Several olefinic compounds such as vinyl acetate, divinyl adipate and allyl methyl carbonate were studied as additives for propylene carbonate (PC)-based electrolytes in lithium-ion battery, which kind of electrolytes always exfoliate graphitic carbon and decompose drastically to liberate organic gas. Three kinds of graphitic carbons commonly used in lithium-ion batteries, namely, natural graphite, MCMB 6-28 and MCF were chosen to test the decomposition-suppressing ability of additives. The effects of the type of graphitic anodes and the structure of additives on the electrolyte decomposition have been investigated in the terms solid electrolyte interface (SEI) formation, which was characterized by cyclic voltammetry (CV), ac impedance, SEM, XPS analyses, and auger electron spectroscopy (AES). The electrochemical performance of the additives-containing electrolytes in combination with LiCoO2 cathode and graphitic carbon anode was also tested in coin cells