Novel PEO-based solid composite polymer electrolytes with inorganic–organic hybrid polyphosphazene microspheres as fillers

Novel solid-state composite polymer electrolytes based on poly (ethylene oxide) (PEO) by using LiClO₄ as doping salts and inorganic–organic hybrid poly (cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) microspheres as fillers were prepared. Electrochemical and thermal properties of PEO-based polymer electrolytes incorporated with PZS microspheres were studied. Differential scanning calorimetry (DSC) results showed there was a decrease in the glass transition temperature of the electrolytes and the crystallinity of the samples in the presence of the fillers. Maximum ionic conductivity values of 1.2 × 10⁻⁵ S cm⁻¹ at ambient temperature and 7.5 × 10⁻⁴ S cm⁻¹ at 80° were obtained and lithium ion transference number was 0.29. Compared with traditional ceramic fillers such as SiO₂, the addition of PZS microspheres increased the ionic conductivity of the electrolytes slightly and led to remarkable enhancement in the lithium ion transference number.     

Experimental investigation on solid dispersion,power consumption and scale-up in moderate to dense solid–liquid suspensions

Detailed particle concentration distribution in dense solid–liquid suspension was measured by means of fiber optic probes. The effect of solid loading, impeller speed, and impeller type and clearance was investigated. Results were compared with modeling approaches to show the accuracy of sedimentation–dispersion model and its capability to describe complex phenomena taking place in dense liquid–solid mixing systems. Variation of power numbers by changing impeller clearance and solid loading were also investigated. It was shown that the impeller power number for a slurry system exhibited different trends in a moderate or dense liquid–solid system. In addition, scale-up rules to achieve the same level of homogeneity on a large scale as the laboratory scale were evaluated.     

Experimental investigation and CFD simulation of liquid–solid–solid dispersion in a stirred reactor

For understanding the monosodium aluminate hydrate crystallization from the supersaturated aluminate solution containing red mud as the leaching liquor of bauxite, the liquid–solid–solid dispersion of a simulant system, i.e. glycerite, red mud and sand, in a stirred reactor has been experimentally investigated as well as simulated using computational fluid dynamics model (CFD) for the first time. The computational model is based on the Eulerian multi-fluid model along with RNG k–ε turbulence model, where Syamlal–obrien-symmetric drag force model (Syamlal, 1987) of the inter-phase momentum transfer between two dispersed solid phases is taken into account. A good agreement is obtained between the experimental data of solid distributions and the simulation results in the flow fields of liquid–solid–solid as well as liquid–solid systems. The solid suspension qualities of both liquid–solid and liquid–solid–solid systems in the stirred reactors with and without draft tube were also studied in detail based on mixing time, the standard deviation of solid concentration proposed by Bohnet and Niesmak (1980), the flow pattern and power number. The influence of the interaction between two dispersed solid phases on the suspension of red mud is found significantly greater than that of sand. The holdup of sand below the impeller is considerably larger than that above the impeller and the red mud dispersion approaches homogeneous in the reactor. The mixing time of liquid–solid–solid suspension is longer than that of liquid–solid suspension under the same conditions, and the mixing times of both systems in the stirred reactor with draft tube are longer than that in the reactor without draft tube. Furthermore, the distributions of sand and red mud in the reactor with draft tube were found less homogeneous than those without draft tube in most cases.     

Polyacrylonitrile–poly(1-vinyl pyrrolidone-co-vinyl acetate) blend based gel polymer electrolytes incorporated with sodium iodide salt for dye-sensitized solar cell applications

New gel polymer electrolytes (GPEs) were prepared via the blending of a polyacrylonitrile polymer and a poly(1-vinyl pyrrolidone-co-vinyl acetate) copolymer. The sodium iodide (NaI) salt concentration was varied for each GPE sample. From ionic conductivity (σ) studies, we observed that the sample with a 40 wt % NaI salt content (N40) showed the highest σ of 3.54 × 10⁻³ ± 0.05 S/cm at room temperature, and all of the GPE samples obeyed Arrhenius behavior. The dielectric properties of the GPE samples were also analyzed to study the electrical polarization of the materials. The developed GPE samples were also characterized with X-ray diffraction and Fourier transform infrared spectroscopy. We also then used the developed GPE samples for the fabrication of dye-sensitized solar cells by sandwiching them between a photoanode and Pt counter electrode for photovoltaic studies. The highest photovoltaic performance was achieved by N40, with an efficiency of 3.04%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47810.     

Effects of amorphous silica nanoparticles and polymer blend compositions on the structural,thermal and dielectric properties of PEO–PMMA blend based polymer nanocomposites

The polymer nanocomposite (PNC) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrices dispersed with nanoparticles of amorphous silica (SiO₂) have been prepared by solution-cast method followed by melt-press technique. Effects of SiO₂ concentration (x?=?0, 1, 3 and 5 wt%) and PEO–PMMA blend compositional ratios (PEO:PMMA?=?75:25, 50:50, and 25:75 wt%) on the surface morphology, crystalline phase, polymer-polymer and polymer-nanoparticle interactions, melting phase transition temperature, dielectric permittivity, electrical conductivity, electric modulus and the impedance properties of the PNC films have been investigated. The crystalline phase of the PNC films decreases with the increase of PMMA contents which also vary anomalously with the increase of SiO₂ concentration in the films. The melting phase transition temperature and polymer-nanoparticle interactions significantly change with the variation in the compositional ratio of the blend polymers in the PNC films. It is observed that the effect of SiO₂ on the dielectric and electrical properties of these PNCs vary greatly with change in the compositional ratio of PEO and PMMA in the blends. The dielectric relaxation process of these films confirm that the polymers cooperative chain segmental dynamics becomes significantly slow when merely 1 wt% SiO₂ nanoparticles are dispersed in the polymer blend matrix.     

Product formation during discharge: a combined modelling and experimental study for Li–O $$_2$$ 2 cathodes in LiTFSI/DMSO and LiTFSI/TEGDME electrolytes

Journal of Applied Electrochemistry - Li–air or Li– $$\text{O}_2$$ batteries are a promising energy storage technology due to the potentially high energy density. However, significant...     

Impacts of polymer–polymer interactions and interfaces on the structure and conductivity of PEG-containing polyimides doped with ionic liquid

Polymer electrolyte membrane (PEM) fuel cells can provide alternatively sourced energy, but current PEMs lose performance under certain conditions. The current work examines composition, structure and properties of poly (ethylene glycol)-aromatic polyimide-ionic liquid systems for PEM applications, as poly (ethylene glycol) (PEG) is an ion conductor and polyimides are stable. To evaluate polymer interactions, different PEG concentrations (0–50% by weight) and different PEG molecular weights (990–6000 g/mole) were examined. Characterization techniques included Fourier transform infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, small-angle x-ray scattering, electrochemical impedance spectroscopy and cyclic voltammetry. By increasing the PEG amount, PEG domains and polymer flexibility are increased, which increases conductivity by two to three orders of magnitude. By increasing PEG molecular weight, PEG segmental motion and PEG-polyimide interface quality are decreased, which decreases conductivity by a factor of two. The maximum conductivity was 64 mS/cm at 80 °C and 70 %RH.     

Dielectric and electrical characterization of (PEO–PMMA)–LiBF<Subscript>4</Subscript>–EC plasticized solid polymer electrolyte films

Plasticized solid polymer electrolytes (PSPEs) consisting of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50/50 wt%) based matrix with lithium tetrafluoroborate (LiBF₄) as dopant ionic salt (10 wt%) and varied concentrations (x = 0, 5, 10 and 15 wt%) of ethylene carbonate (EC) as plasticizer have been prepared. Classical solution-cast (SC) and the ultrasonic assisted followed by microwave irradiated (US–MW) solution-cast methods have been used for the preparation of (PEO–PMMA)–LiBF₄–x wt% EC films, and the same have been hot–pressed to get their smooth surfaces. Dielectric relaxation spectroscopy (DRS) and X–ray diffraction (XRD) techniques have been employed to characterize the dielectric and electrical dispersions and the structural properties of the PSPE films, respectively. It has been observed that the ionic conductivity of these semicrystalline ion-dipolar complexes is governed by their dielectric permittivity and polymers chain segmental dynamics. The increase in ionic conductivity values with the increase of plasticizer concentration in the PSPEs also varies with the films’ preparation methods. The US–MW method prepared PSPE film containing 15 wt% EC has a maximum ionic conductivity (1.86 × 10^?5 S cm^?1) at room temperature, whereas, the films having low concentrations of EC exhibit the conductivity of the order of 10^?6 S cm^?1.     

Development of novel hybrid nanocomposites based on natural biodegradable polymer–montmorillonite/polyaniline: preparation and characterization

The problems with non-degradable materials in different applications have led to an interest in materials based on bionanocomposites. In this study, polymer–montmorillonite nanocomposites based on natural polymers (chitosan, alginate, gelatin and starch) and montmorillonite (MMT) were prepared using solution intercalation method. Then hybrid nanocomposites were synthesized by chemical oxidative polymerization of aniline in the presence of polymer–MMT nanocomposites. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) were employed to characterize the nanocomposites. FT-IR confirmed the successful preparation of hybrid nanocomposites. From the XRD results, intercalation of the MMT platelets in the matrix of polymers was examined. Further investigation by TEM images showed a mixed intercalated and flocculated structure for nanocomposites. Moreover, the TGA results showed improved thermal stability for the nanocomposites. The results presented in this study showed the feasibility of using these hybrid nanocomposites with improved properties in wide range of applications.     

A stable host–guest electro-optic polymer system with polyisoimide as a host

A stable host–guest electro-optic (EO) polymer system has been prepared for improving not only the EO effect but also the thermal stability of the effect using a polyisoimide as a host. Disperse Red 1 (DR1) and a polyisoimide (PII) synthesized from 2,2-bis(4-aminophenyl)hexafluoropropane and oxydiphthalic anhydride were used as the guest and the host, respectively. Analyses of a model compound reaction and the host–guest film after annealing at various temperatures show that the reaction between the isoimide groups in the PII and the hydroxyl groups in DR1 occurs at around 140 °C. The EO coefficient obtained at a wavelength of 1.55 μm was 13.7 pm/V from an EO polymer film with 30 wt% of DR1 as added guest. The EO signal was thermostable at high temperature due to the chemical reaction between the host and guest during poling.     

A new model in correlating and calculating the solid–liquid equilibrium of salt–water systems

In this work, a new activity coefficient model was deduced for the correlation of solid–liquid equilibrium(SLE) in electrolyte solutions. The new excess Gibbs energy equation for SLE contains two parts: the single electrolyte item and the mixed electrolyte item. Then a new hypothesis for the reference state of activity coefficients was proposed in the work. Literature data for single electrolyte solution and mixed electrolyte solution systems,with temperature spanning from 273.15 to 373.15 K, were successfully correlated using the developed model.     

Small angle X-ray scattering investigation of deformation in PMMA toughened with core–shell particles

Abstract

Tensile deformation of PMMA toughened with core–shell particles has been investigated by in situ small angle X-ray scattering (SAXS). Each core–shell particle consisted of a PMMA core surrounded by a rubber shell, encased in a thin PMMA outer layer. Toughened PMMA (RTPMMA) specimens containing low and high particle concentrations were compared. The samples were tested under uniaxial tension at strain rates of 0.5 and 5.0 mm min^-1, at room temperature (20°C). The SAXS pattern of each undeformed RTPMMA specimen consisted of circular concentric fringes which correspond to the form factor of the core–shell particles. Highly localised failure within the particles was observed when low particle concentration samples were deformed beyond the yield point. This localised failure occurred at the poles of the particles at, or adjacent to, the core/shell interface. As the sample was stretched further, the failure was then seen to extend either side of the poles around, or alongside, the interface. In contrast, when the particle concentration was high, the particles stretched considerably without failing. No evidence for crazing was seen in the SAXS patterns obtained from these RTPMMA samples tested under the conditions used. Crazing was therefore not considered to be a major deformation mechanism.     

Simulation and investigation of periodic deflecting oscillation of gas–solid planar opposed jets

In this study, the Eulerian–Eulerian approach based on kinetic theory of granular flow (KTGF) was used to simulate the gas–solid planar opposed jets. The periodically deflecting oscillation was observed, i.e., the two opposed jets deflect off each other and swing up and down periodically. The system entropy production rate was calculated to explain this periodic oscillation for the first time. It was found that the periodic deflecting oscillation was dominated by a self-adjusting mechanism of planar opposed jets with the combined action of the pressure release and the entrainment of continuous jets. The effects of nozzle separation, initial jet Reynolds number and particle parameters on the oscillation period were analyzed. The period decreases as the jet Reynolds number or mass loading increases, but increases as the nozzle separation or the particle diameter increases. Furthermore, it is found that the residence time of particles was increased by increasing the mass loading.     

Enhanced performance of urea–glyoxal polymer with oxidized cassava starch as wood adhesive

To eliminate the hazard of formaldehyde from wood-based products to human and environment, formaldehyde was replaced by glyoxal to produce wood adhesive. Urea–glyoxal (UG) resin was environmental friendly, while its bonding strength was very poor, especially its water resistance. The object of this work was to improve the mechanical properties of UG resin by oxidized cassava starch addition. Hence, the urea–glyoxal (UG) resin was synthesized and the oxidized cassava starch was added through mechanical mixing. The bonding strength, structure distributions, and the morphology features of the cured UG resin system were investigated by producing a three-layer plywood, FTIR, and SEM analysis. The results of dry and wet shear strength of plywood indicated that there was a positive effect of oxidized cassava starch on bonding strength of a three-layer plywood, and when the oxidized cassava starch content was increased to 45%, the dry strength could reach 1.21 MPa, and the wet strength was 0.72 MPa. The FTIR results showed that chemical reaction between UG resin and oxidized cassava starch was beneficial to the branched structure formation and higher cohesion strength of UG resin. Meanwhile, the tightness structure of enhanced UG resin system was observed by SEM analysis as well. These improved properties were contributed to water resistance improvement of UG resin.

     

Development of a model for thin-film stability and spreading in solid–liquid–liquid systems

The presence of thin aqueous films and their stability has a profound effect on reservoir rock–fluids interactions involved in spreading and adhesion. The stability of thin wetting aqueous films on rock surfaces is governed by several variables including pH, brine and crude oil compositions, and capillary pressure. These variables govern the wetting states in the solid–liquid–liquid systems. The wetting states influence the residual oil saturation and the oil-water relative permeabilities and, consequently, the oil recovery. The objective of this study was to deduce a functional dependence of thin-film stability on the above parameters by considering intermolecular and surface interactions in rock–crude oil–brine systems. The surface forces are manifested as disjoining pressure in thin films. The disjoining pressure isotherms for the selected solid–liquid–liquid systems have been computed in terms of the bulk properties of the media. The equilibrium contact angles have also been computed from the integration of the Young–Laplace equation, which relates contact angle to the capillary pressure and disjoining pressure isotherm of the system. The contact-angle data obtained from sessile-drop experiments have been compared with the calculated results, as well as with other published results. Adhesion maps, which relate the film stability to brine pH and molarity, have been developed. The rock–fluids systems considered for this study consisted of smooth glass, quartz and Yates reservoir fluids. The DLVO theory has been used to model the intermolecular forces. The structural forces are incorporated to overcome the limitations of the DLVO theory. A charge regulation model has been used to analyze the crude oil–brine and glass–brine interfaces. The effects of multivalent ions have been incorporated using an equivalent molarity concept. The overall computational model developed in this study is aimed at providing a priori prediction capability of rock-fluids interactions in petroleum reservoirs for inclusion in reservoir simulators.     

Studies on electrochemical properties of poly (ethylene oxide)-based gel polymer electrolytes with the effect of chitosan for lithium–sulfur batteries

Composite gel polymer electrolytes (CGPE), with different proportions of poly (ethylene oxide), plasticizers namely 1,3-dioxolane (DIOX)/tetraethelyneglygol dimethylether (TEGDME) and a lithium salt (LITFSI) with the addition of filler chitosan were prepared using the solution casting technique in an argon atmosphere. The membranes were subjected to various characterization techniques such as TG/DTA, FTIR and an ac impedance analysis. A lithium symmetric cell (Li/CGPE/Li) was assembled and the interfacial stability of the polymer electrolyte with a lithium anode was measured. The electrochemical stability and the transport properties of the high conducting sample were also measured. TG/DTA shows the thermal stability of the high conducting sample. The optimal value of the plasticizers was to be found in the ionic conductivity point of view.     

Development of Nicolais–Narkis model for yield strength of polymer nanocomposites reinforced with spherical nanoparticles

In this paper, the Nicolais–Narkis model for yield strength of polymer nanocomposites containing spherical nanoparticles is developed assuming the role of interphase between polymer and nanofiller phases. The predictions of the developed model are compared with the experimental results and also, the effects of interphase properties on the yield strength are expressed.The calculated results show that the developed model can give much accurate predictions for yield strength of nanocomposites by proper thickness and strength of interphase, while the yield strength is under-predicted by disregarding of interphase. The developed model demonstrates that the yield strength improves by reduction in nanoparticle size and increment in interphase thickness. Also, the detrimental effect of weak interfacial adhesion between polymer matrix and nanoparticles is revealed.     

Synthesis, characterization and device application of hot-pressed solid polymer electrolytes:(1 − x) PEO:x NaHCO3

Synthesis and io n transport characterization of hot-pressed solid polymer electrolyte (SPE) membranes:(1 ? x) poly (ethylene oxide) (PEO):x NaHCO₃, where 0 < x < 50 wt.%, have been reported. SPE films have been synthesized using a hot-press technique in place of the traditional solution-cast method. A conductivity enhancement of the two orders of magnitude was achieved in SPE film:70PEO:30NaHCO₃ and this composition has been referred to as optimum conducting composition (OCC). Materials characterization was done with the help of XRD, SEM, FTIR, DSC and TGA techniques. The ion transport behavior in SPE membranes has been discussed on the basis of experimental measurements on their ionic conductivity (σ), ionic mobility (μ) and some other important parameters. A solid-state polymer battery was fabricated using SPE OCC at room temperature, as a device application.     

Influence of ammonium salt formation on the activity and selectivity of the 12-molybdophosphate heteropolyacid catalyst prepared by solid–solid interaction in the ammoxidation of 2-methylpyrazine

The ammonium salt of 12-molybdophosphoric acid has been prepared by the solid-state interaction of the ammonium salts of molybdenum and phosphorus. The catalysts obtained by pretreatment of the precursor at various temperatures, have been characterized by nitrogen adsorption, X-ray diffraction (XRD), Fourier-transformed infrared (FTIR) spectroscopy and temperature-programmed decomposition (TPD) of the catalysts. Ammoxidation of 2-methylpyrazine has been carried out on these catalysts. The amount of ammonium salt present in the catalyst has been correlated with the activity and selectivity of the catalysts.