Weight Fraction Of Component Research Articles

Design and Sintering of All-Solid-State Composite Cathodes with Tunable Mixed Conduction Properties via the Cold Sintering Process.

Electrodes for solid-state batteries require the conduction of both ions and electrons for extraction of the energy from the active material. In this study, we apply cold sintering to a model composite cathode system to study how low-temperature densification enables a degree of control over the mixed conducting properties of such systems. The model system contains the NASICON-structured Na3V2(PO4)3 (NVP) active material, NASICON-structured solid electrolyte (Na3Zr2Si2PO12, NZSP), and electron-conducting carbon nanofiber (CNF). Pellets of varying weight fractions of components were cold-sintered to greater than 90% of the theoretical density at 350-375 °C, a 360 MPa uniaxial pressure, and with a 3 h dwell time using sodium hydroxide as the transient sintering aid. The bulk conductivity of the diphasic composites was measured with impedance spectroscopy; the total conductivities of the composites are increased from 3.8 × 10-8 S·cm-1 (pure NVP) to 5.81 × 10-6 S·cm-1 (60 wt % NZSP) and 1.31 × 10-5 S·cm-1 (5 wt % CNF). Complimentary direct current polarization experiments demonstrate a rational modulation in transference number (τ) of the composites; τ of pure NVP = 0.966, 60 wt % NZSP = 0.995, and 5 wt % CNF = 0.116. Finally, all three materials are combined into triphasic composites to serve as solid-state cathodes in a half-cell configuration with a liquid electrolyte. Electrochemical activity of the active material is maintained, and the capacity/energy density is comparable to prior work.

An Evaluation of Steady-State-Based Pressure-Saturation Predictions in Gas-Condensate Reservoirs Under Various Reservoir and Well Operating Conditions

Summary The analysis of pressure-transient and rate-transient data in gas-condensate reservoirs (GCRs), operating below dewpoint pressure (Pdew) often requires using two-phase pseudovariables. These are used to handle the nonlinearities that arise in the governing partial-differential equation as a result of pressure-dependent saturation, mobility, and fluid-property changes. The incorporation of relative permeability (kr) data in the computation of such pseudovariables requires a priori knowledge of sufficiently representative pressure-saturation relationships. For this purpose, a number of analytical and semianalytical pressure-saturation prediction methods can be found in the literature. In this study, a pressure-saturation prediction method, which relates component weight fractions (in the gas phase, the condensate phase, and the reservoir fluid mixture) and gas fractional flow [or gas to total gas-plus-condensate flow rate (GTR)] to pressure, was used to compute pressure-saturation relationships for various reservoir fluids and two rock types. The computed pressure-saturation relationships were compared to the responses observed in the near-wellbore region of corresponding single-well 1D radial homogeneous compositional reservoir-simulation models operated at constant well flowing pressures (Pwf) lower than Pdew. Sensitivities were conducted to highlight the impact of gas-condensate fluid richness, kr characteristics, degree of reservoir undersaturation (Pi – Pdew), and Pwf on observed trends in the representativity of the predicted pressure-saturation relationships. Like other methods based on two-phase steady-state (SS) assumptions, the condensate saturations predicted by the GTR method generally matched those observed around the wellbore in the simulation models when Pi – Pdew was sufficiently high. For cases in which Pi – Pdew was not sufficiently high, an examination of radial pressure and saturation profiles from the simulation models showed that the trend of increased condensate saturation levels observed around the wellbore with increasing degrees of reservoir undersaturation, as reported in literature, represents one of three possible trends (i.e., increasing, decreasing, and almost-constant condensate-saturation levels). For cases in which the predicted GTR-based pressure-saturation curve showed lower (higher) condensate saturations than the pressure/volume/temperature (PVT) liquid-saturation curves at the given Pwf, increasing Pi – Pdew resulted in decreasing (increasing) condensate-saturation levels around the wellbore. The results indicate that at low Pi – Pdew values, trends in two-phase SS-based analysis techniques are affected by the gas-condensate fluid richness and the nature of the kr characteristics. It is also shown that for cases in which there is not much of a difference between PVT-based and SS-based pressure-saturation curves, variations in the Pi – Pdew do not affect the condensate-saturation levels around the wellbore.

Local Structure of Ca2+ Alginate Hydrogels Gelled via Competitive Ligand Exchange and Measured by Small Angle X-Ray Scattering.

Alginates, being linear anionic co-polymers of 1,4-linked residues β-d-ManA (M) and α-l-GulA (G), are widely applied as hydrogel biomaterials due to their favourable in vivo biocompatibility and convenient ionic crosslinking. The “egg-box” model is the prevailing description of the local structure of junction zones that form between the alginate chains and divalent cations, such as Ca2+, when ionic gelation occurs. In the present study we address to what extent signatures of lateral dimerization and further lateral association of junction zones also represent a valid model for the gelation of alginate using the recently reported method of competitive ligand exchange of chelated Ca2+ ions as a method for introducing gelling ions at constant pH. Small angle X-ray scattering with a q range from 0.1 to 3.3 nm−1 was employed to determine local structure in the hydrogel, using a custom-made fluid sample cell inserted in the X-ray beam. The scattering volume was intended to be localized to the contact zone between the two injected aqueous alginate solutions, and data was captured to resolve the kinetics of the structure formation at three different conditions of pH. The data show evolution of the local structure for the Ca2+ induced formation of junction zones in an alginate with 68% G residues, characterized by cross-sectional radii that could be accounted for by a two-component, broken rod like model. The evolution of the two component weight fractions apparently underpinned the connectivity, as reflected in the rheological data.

Reactive Nanofluids for Tuning Resin Hardness

ABSTRACTPolyurea resins derived from tolyldiisocyante (TDI) and a reactive solvent-free nanofluid (NF-NH2) surface-decorated with propylamines can be tuned over three to five orders of magnitude in storage modulus (10 MPa to 10 GPa) and hardness modulus (6 kPa to 4 GPa) by varying weight fractions of components. The thermal properties of this NF-NH2 are similar to several other nanofluids reported using the same bulky anionic counterion that also imparts liquidity in the absence of any solvent. This tuning suggests applications ranging from opaque protective coatings to clearcoats to sealants to adhesives.

Enhanced Wide‐Angle Energy Conversion Using Structure‐Tunable Waveguide Arrays as Encapsulation Materials for Silicon Solar Cells

The authors report on the enhancement in optical energy conversion in silicon solar cells encapsulated with a polymer film comprising of waveguide array structures. The structures are fabricated through light‐induced self‐writing with periodic arrangements of optical beams transmitted through a binary component photopolymer, wherein a periodic core‐cladding architecture is produced. The size, spacing, and arrangement of the cores are varied through the size and arrangement of the optical beams via photomask design. A range of waveguide array structures are produced using different masks and component weight fractions. External quantum efficiency (EQE) measurements reveal structures that provide the greatest enhancement for normal and non‐normal incidence irradiation, the latter for which reveals wide‐angle light capture and conversion. Encapsulated solar cells yield an approximate 10% enhancement in EQE and a 20% increase in the short circuit current, up to an incident angle of 40°, as compared to uniform encapsulants. The experimental results are corroborated by beam propagation simulations that show the spatial confinement of transmitted optical energy is the main effect that increases conversion efficiency. Principles that establish a structure‐property‐performance relationship are discussed, toward rational materials processing to increase energy conversion.

Production data analysis in gas condensate reservoirs using type curves and the equivalent single phase approach

Most modern production data type curve (PDTC) techniques, which are used in the estimation of reservoir and well productivity parameters such as permeability, drainage radius and skin, were originally developed with the assumption of Darcy flow (i.e. laminar flow, with pressure gradient proportional to the fluid superficial velocity, in accordance with Darcy's law) of a single-phase fluid. Two-phase conditions, e.g. in a gas condensate reservoir (GCR) operating below dewpoint pressure, introduce nonlinearities into the diffusivity equation, making the use of single-phase techniques questionable, and potentially producing erroneous parameter estimates. A common approach to linearizing the system is by the use of pseudovariables which account for the two-phase effects in addition to the pressure-dependence of fluid properties.In this study, GCR production data generated using homogeneous fine-grid compositional simulation models, were first analysed using a well-known conventional (single-phase) modern PDTC technique, namely the Blasingame type curves for radial flow around a vertical well in a circular drainage area. The conventional techniques were then modified using an equivalent single phase concept, which was employed in the computation of two-phase pseudovariables for use with the single-phase PDTC. To compute these two-phase pseudovariables, pressure-saturation/kr relationships are required. These were determined using a technique, which employs fluid component weight fractions and gas fractional flow of a fluid with constant fixed total composition. Sensitivities were conducted on reservoir fluid richness (maximum liquid dropout from 1% to 42%), relative permeability curves, degree of reservoir undersaturation and well operating pressures, to examine their impact on production decline response and subsequent conventional PDTC analysis, as well as their impact on the effectiveness of the equivalent single-phase based approach used in this study.The paper first highlights the impact of two-phase flow conditions in GCRs on conventional PDTC analysis, in terms of the quality of the type curve match (TCM) and estimates of permeability, drainage radius and skin. Then it is shown that, in GCR analysis where the impact of two-phase effects are important, significant improvements can be obtained, both in the quality of the TCM and subsequent parameter estimates, through the use of pseudovariables computed using equivalent single phase concepts. The results also identify conditions under which, depending on the fluid richness and/or the degree of undersaturation, two-phase effects, although present, may not significantly impact the quality of interpretation of long-term production data from GCRs, using conventional single-phase PDTC techniques.

Control of Morphology in Polymer Blends through Light Self-Trapping: An in Situ Study of Structure Evolution, Reaction Kinetics, and Phase Separation

We report on how polymer morphology is controlled through the self-trapping of transmitted optical beams in photoreactive polymer blends. Self-trapped optical beams, characterized by divergence-free propagation, drives the growth of a congruent arrangement of polymer filaments in the blends. With suitable component weight fractions and exposure intensity, binary phase morphologies form in precisely the same pattern as the beams’ arrangement, thereby producing 2D structures in polymer blend volumes of large depth and area. Morphology evolution and the formation processes were observed by in situ microscopy. In situ confocal Raman measurements of polymer conversion and molecular weight increase along the filament regions reveal that polymerization undergoes autoacceleration, followed by the onset of mixing instability which leads to phase separation. These phenomena begin at the front end of the filament and propagate along its length over the depth of the blend. Control over morphology is discussed with respect to the competitive processes of phase separation and photo-cross-linking.

Influence of molecular weight on structure and rheological properties of microcrystalline chitosan mixtures

In the present work, the atomic force microscopy (AFM) studies and rheological properties of aqueous solutions of microcrystalline chitosan (MCCh), polyacrylamide (PAM) and their mixtures at different weight ratios have been investigated. Flow measurements were carried out using on solutions of native polymers and their mixtures with various weight fractions of components. It has been observed that the polymer solutions and their mixtures exhibited the non-Newtonian behavior with shear-thinning and/or shear-thickening areas. Rheological parameters from power law and activation energy of viscous flow are determined and discussed. The AFM images showed difference in surface properties films for the native polymers and their mixtures. The roughness of the mixtures increases with the increase of MCCh content. This may indicate a strong interaction between the polymeric components.

Mechanical characterization of bucky gel morphing nanocomposite for actuating/sensing applications

Since the demonstration of the bucky gel actuator (BGA) in 2005, a great deal of effort has been exerted to develop novel applications for this electro-active morphing nanocomposite. This three-layered bimorph nanocomposite can be easily fabricated, operated in air and driven with a few volts. The BGA with improved mechanical strength is an excellent candidate for application in macro- to micro-scale smart structures with actuating and sensing capabilities. However, developing new applications requires identifying and understanding the effective design parameters and mechanical properties, respectively. There has been limited published studies on the mechanical properties of BGA. In this study, the effect of three parameters—layer thickness, carbon nanotube type and weight fraction of components—on the mechanical properties was investigated. Samples were characterized via nano-indentation and DMA. The BGA composed of 22 wt% single-walled carbon nanotubes and 45 wt% ionic liquid exhibited the highest hardness, adhesion, viscosity, and elastic and storage moduli. This study revealed the important role of the carbon nanotube type on BGA adhesion. Samples made with multi-walled carbon nanotubes had the lowest adhesion, which is a required factor in applications such as microfluidics.

Thickness and composition dependence of the glass transition temperature in thin random copolymer films

Glass transition temperatures ( T g ) of thin poly(styrene-co-methyl methacrylate) and poly(2-vinyl pyridine-co-styrene) films coated on a native oxide surface of Si wafer (100) were measured by ellipsometry. The thickness dependence of T g can be properly fitted by previously suggested equation developed for homopolymers, based upon a continuous multi-layer model, although one component in thin random copolymer films demonstrates a slightly favorable interaction between a substrate and thin film, and another demonstrates a strongly favorable interaction. Surface and interface have a strong influence on T g of thin film coated on substrate: the surface has the effect of reducing T g , whereas the interface increases the T g according to the degree of interaction between a substrate and thin film. This degree of interaction can be quantified as an interaction parameter ( k ), and is dependent on the composition of random copolymers. For the estimation of k values of thin random copolymer films, we proposed a parallel type additive function (1/ k ran = w 1 / k 1 + w 2 / k 2 ) where w is a weight fraction of component.

Thickness and composition dependence of the glass transition temperature in thin random copolymer films

Glass transition temperatures ( T g) of thin poly(styrene-co-methyl methacrylate) and poly(2-vinyl pyridine-co-styrene) films coated on a native oxide surface of Si wafer (100) were measured by ellipsometry. The thickness dependence of T g can be properly fitted by previously suggested equation developed for homopolymers, based upon a continuous multi-layer model, although one component in thin random copolymer films demonstrates a slightly favorable interaction between a substrate and thin film, and another demonstrates a strongly favorable interaction. Surface and interface have a strong influence on T g of thin film coated on substrate: the surface has the effect of reducing T g, whereas the interface increases the T g according to the degree of interaction between a substrate and thin film. This degree of interaction can be quantified as an interaction parameter ( k), and is dependent on the composition of random copolymers. For the estimation of k values of thin random copolymer films, we proposed a parallel type additive function (1/ k ran= w 1/ k 1+ w 2/ k 2) where w is a weight fraction of component.

Release from or through a wax matrix system. III. Basic properties of release through the wax matrix layer.

Release property of reservoir device matrix tablet was examined. Wax matrix layer was prepared from physical mixture of lactose and hydrogenated castor oil to obtain basic release properties. Release process showed zero order kinetics in a steady state after a given lag times, and could be divided into two stages. The first stage was the formation process of water channel by dissolving the soluble component in the wax matrix layer. The lag time was considered to be the time required forming water channel and the time begun to release drug through the wax matrix layer at the same time. The lag time obtained by applying the square root law equation was well connected with the amount of matrix layer and mixed weight fraction of component in matrix layer. The second stage was the zero order release process of drug in the reservoir through the wax matrix layer. The release rate constants were calculated by taking into accounts of the thickness of matrix layer and permeability coefficient, and were well connected with the amount of matrix layer and mixed weight fraction of component. Also it was suggested that the tortuosity of matrix layer could be expressed by a function of the porosity defined by the mixed weight fraction.

Estimation of statistical uncertainties in quantitative phase analysis using the Rietveld method and the whole-powder-pattern decomposition method

Formulae for estimating statistical uncertainties in quantitative phase analysis using the Rietveld method and the whole-powder-pattern decomposition method have been derived. The relative magnitude of statistical uncertainty for a derived weight fraction of a component in a mixture is given by σ(Wm)/Wm= (1/Wm− 1)1/2F(D\textstyle\sum_{i = 1}^NYoi)−1/2, whereWmis the weight fraction of themth component,Fis the goodness-of-fit index,D(≤1) is a factor depending on the degree of peak overlap, and ∑Yoiis the total sum of profile intensities in the 2θ range used for whole-powder-pattern fitting. If the step width Δ2θ in step scanning is halved, ∑Yoiis almost doubled; on the other hand, ∑Yoiis proportional to the fixed counting timeT. Therefore, σ(Wm)/Wm∝ (Δ2θ/T)1/2. Extension of the 2θ range for whole-powder-pattern fitting towards the high-angle region is not effective for improving the precision of the derived weight fractions if the profile intensities in that region are weak. The formulae provide guidelines for optimizing experimental parameters in order to obtain a required precision.

Rheological properties of chitosan blends with poly(ethylene oxide) and poly(vinyl alcohol) in solution

The present work is concerned with experimental results on rheological characteristics of active chitosan salt blends with water solution of PEO and PVA. Flow measurements were carried out on solutions of pure polymers: chitosan (with deacetylation degree DD=73.3% and M w=3.2×10 5), PEO ( M w=1×10 5) and PVA ( M w low) of various concentrations and their blends with various weight fractions of components. Rheological parameters of rheological power law, such as n, A and E a (activation energy of viscous flow) with varying weight fraction of chitosan in blend solutions are calculated and discussed.

A study of thermal analytical values for coal blends burned in an air atmosphere

This study was aimed at providing a rapid and reliable method for predicting the performance of coal blends burned in industrial furnaces. The variation in certain coal blend parameters (such as T max, and R max), obtained by thermogravimetric analysis (TGA) were examined and compared with values of coal mixtures evaluated from the following general expression (linear additive rule) M = (1- x) M a + xM b where M represents the composite value of any of the parameters investigated, and x is the weight fraction of component b in the mixture. The TGA was operated in both the programming and isothermal modes to provide a wide range of sample heating rates. The results obtained were dependent on the sample heating rate: for the runs in the programming mode (low sample heating rates, not exceeding 100°C min −1) experimental values of T max, R max and T i for the coal blends did not follow the above equation, suggesting a non-additive relationship. When the isothermal mode was used (average sample heating rates up to 500 ° C min −1) values of t breakpoint, T combustion end-point and the residue for the blends did not follow the additive relationship.

Rheological behavior of compatible polymer blends. I. Blends of poly(styrene-Co-acrylonitrile) and poly(ɛ-caprolactone)

The rheological behavior of blends of poly(styrene-co-acrylonitrile) (SAN) and poly(e-caprolactone) (PCL) was investigated, using a cone-and-plate rheometer. For the study, blends of various compositions were prepared by melt blending using a twin-screw compounding machine. The rheological properties measured were shear stress (σ12), viscosity (η), and first normal stress difference (N1) as functions of shear rate (γ) in steady shearing flow, and dynamic storage modulus (G′) and loss modulus (G″) as functions of angular frequency (ω) in oscillatory shearing flow, at various temperatures. It has been found that logarithmic plots of N1 versus σ12, and logarithmic plots of G′ versus G″, become virtually independent of temperature but vary regularly with blend composition, and that the zero-shear viscosity of the blends, (ηo)blend, follows the relationship, 1/log(ηo)blend = wA/log η0A + wB/log η0B, where η0A and η0B are the zero-shear viscosities of components A and B, respectively, and wA and wB are the weight fractions of components A and B, respectively. The physical implications of the relationship found are discussed.

Extension of the chain-end free volume theory for predicting the Tg− M−1n relationship for homopolymer bimodal blends

The chain-end theory of free volume has been extended to describe the T g− M −1n behaviour of bimodal blends of homopolymers. The theory provides an equation of the form: T g=T g∞− K M A 1 X+(1−X)P X+(1−X)Q M A M B where P = α B α A is the ratio of free volume expansion for the individual chain-ends and Q = ( ϱ B ϱ A )( θ B θ A ) where ϱ is the density and θ is the chain-end free volume of each component. X is the weight fraction of component A. The equation fits experimental data for the T g− M −1 n relationship in two polycarbonate and two polystyrene blends.

Semiquantitative X-ray diffraction method for phase analysis using additions of a foreign component

A method is described for semiquantitative X-ray diffraction phase analysis, which involves the addition to the investigated multicomponent system of known large (about 80–95%) amounts of a crystalline substance originally not contained in the system. This results in a decrease of the diffraction line intensities of the components to be measured to small but detectable values. The weight fraction of a component is related to the added fraction of the doping substance and to the fraction of that component remaining in the doped sample. The method is very simple and yields the weight fractions of the major components in the system with a typical error of a few percent. The weight fractions of the minor components cannot be determined with fair accuracy in this way. The method is appropriate in cases where only a small amount of the investigated system is available. Optimum conditions to attain maximum accuracy of the method are discussed.

Adsorption of nuclides on mixtures of minerals

Distribution coefficients for adsorption of Sr(II) and Cs(I) on binary mixtures of various clay minerals and oxides have been determined in order to see whether distribution coefficients of mixtures can be predicted from those of the pure minerals. It is shown that in some cases, the distribution coefficients of mixtures are equal to the sum, ΣfiDi, where fi is the weight fraction of component of i and Di is the distribution coefficient of that mineral. However, in some cases significant deviations from this relation were observed which probably indicate the presence of the interactions between the minerals.

A study of the errors in x-ray quantitative analysis procedures for aerosols collected on filter media

A large number of experimental variables are utilized in the X-ray quantitative analysis of crystalline and amorphous components of aerosols collected by air filtration methods. The individual errors associated with these variables can be combined statistically through use of an error expression applied to the basic analytical equations providing that either measurements of standard deviations or their estimates can be obtained. This procedure has been developed for the variables of X-ray mass absorption, aerosol load density, transmission and diffraction intensities, and reference intensity constants, and has been applied in the quantitative analysis of two filter samples containing both crystalline and amorphous components. The results indicate that, despite some subjectivity in estimating some of the required parameters, reasonable error magnitudes for the component weight fractions are obtained. By being consistent in the way one obtains the initial standard deviations for the input data, one may determine which of the variables most seriously affects the accuracy of the determined weight fractions. For the samples studied here, a marked sensitivity of the resulting weight fractions to reference intensity constants and aerosol load density is revealed.