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Abstract
Some cases and reactions in binary isobaric phase diagram presenting variation of temperature and composition have no names; we propose to attribute names for some cases and reaction that we identified. The names of the invariant reactions are issued from Greek language as eutectic but concerning the curves of separation between domains, they have a Latin origin. We have respected these choices. ...
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Abstract
Determination of vapor pressure is critical for accurate detection of trace volatile hazardous materials, ensuring human health and environmental security. 2,4,6-Trinitrotoluene (TNT), 3,4-Dinitrofurazanfuroxan (DNTF), and 2,4-Dinitroanisole (DNAN) are an important class of volatile low-melting nitrocompounds which are widely used in military, aerospace, and defense industry. In this study, the sublimation and evaporation characteristics of these three nitrocompounds were investigated for the first time by using isothermal thermogravimetry (TG) undergoing zero order, non-activated evaporation processes, analyzed with the Antoine and Langmuir equations, ...
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Abstract
Enthalpy of pyrolysis and its variation in the pyrolysis process of four heavy oils: Daqing vacuum residue (DQVR), Karamay vacuum residue (KRVR), Liaohe vacuum residue (LHVR), and Venezuela vacuum residue (VNVR), have been quantitatively studied by differential scanning calorimetry associated with thermogravimetry. The results indicate that overall enthalpies at different heating rates show a linear trend with respect to the final coke yields in the thermal analysis. Classical kinetic method (Friedman method) is used to further analyze pyrolysis enthalpy variation in ...
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Abstract
In this work, we studied the thermal characterization of block copolymers based on ε-caprolactone. The copolymers were obtained by anionic polymerization techniques, using different co-monomers such as styrene (S) and dimethylsiloxane (DMS). Synthesized copolymers were characterized by H-nuclear magnetic resonance, size exclusion chromatography, and Fourier transform infrared spectroscopy. Isothermal crystallization was performed by differential scanning calorimetry (DSC), and Avrami’s theory was employed in order to obtain kinetics parameters of interest, such as the half-life for the crystallization process ( t 1/2 ...
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Abstract
The polythiophene nanoparticles (nano-PT) were prepared with average diameter of 20–35 nm. The nanostructurals of polythiophene were confirmed by TEM and SEM analyzes. The kinetics of the thermal degradation and thermal oxidative degradation of nano-PT were investigated by thermogravimetric analysis. Kissinger method, Flynn–Wall–Ozawa method, and advanced isoconversional method have been used to determine the activation energies of nano-PT degradation. The results showed that the thermal stability of nano-PT in pure N 2 is higher than that in air atmosphere. The analyzes ...
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Abstract
The effect of zinc bisdiethylphosphinate (ZnPi) and organoclay on mechanical, thermal, and flame retardant properties of poly(ethylene terephthalate) (PET) fiber was investigated. ZnPi was preferred due to its fusible character at spinning temperature and organoclay was used for synergistic interaction. The mechanical, thermal, and flame retardant properties of fibers were examined by tensile testing, thermogravimetric analysis (TG), and micro combustion calorimeter (MCC). The tensile strength of the PET fiber reduced with the addition of both ZnPi and organoclay. The TG results ...
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Abstract
Epoxy/glass fiber hybrid composites with organo-montmorillonite (OMMT) and decabromodiphenyl oxide (DBDPO) flame retardants were prepared by vacuum-assisted resin infusion technique. The effects of OMMT and DBDPO on the flammability properties of epoxy/glass fiber hybrid composites were evaluated through UL-94 vertical flammability test and limiting oxygen index (LOI). Thermal decomposition was studied by means of thermogravimetric analyzer (TG). Field emission scanning electron microscopy (FESEM) was used to study the char morphology of the epoxy hybrid composites after being subjected to UL-94 vertical ...
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Abstract
A novel natural carbon agent-based flame retardant urea salt of chitosan phosphate (UPCS) has been prepared with chitosan, phosphorus pentoxide, and urea. It was characterized by 13 C NMR, 31 P NMR, Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy. Its influence on thermal properties and flammability performance of polyvinyl alcohol was investigated through thermogravimetric analysis, microscale combustion calorimetry experiment, and real time FTIR. The surface morphology of the residual char was investigated with the scanning electron microscope measurement. The ...
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Abstract
CaFeO 2.5±δ single crystal was obtained after different steps of mechanical and thermal treatment and finally a crystallization in an image furnace. We performed dilatometric tests of this material according to the three crystallographic directions of the network, from ambient to 1,473 K, accompanied by DSC and TG tests. The tests performed on a single crystal CaFeO 2.5 confirmed the transitions already observed by other authors. For the first time, a dilatometric anomaly has been observed at 1,308 K. It has ...
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Abstract
The standard Gibbs energy of formation of M 2 TeO 6 and M 6 TeO 12 (where M = Sc, Y), was determined from its vapor pressure measurements by employing thermogravimetry-based transpiration technique. This technique was validated by measuring the vapor pressure of well-studied substances such as TeO 2 (s) and CdCl 2 (s). The temperature dependence of the vapor pressure of TeO 2 (g) over the mixtures M 6 TeO 12 + M 2 O 3 (where M = Sc, ...
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Abstract
The effect of 13 viscosity modifying admixtures (VMA) on the Portland cement hydration was studied in this paper. In this purpose, thermal analyses (DTA and TG) were performed after 1, 7 and 28 days of hydration on cement pastes containing 0.01–0.5 % from the following VMA: diutan gum, welan gum, polygalactomannane ether, natural cellulose fibres, modified polysaccharide, polyacrylamide, high-molecular mass synthetic copolymer, hydroxypropyl starch and a chemically modified starch. It was noticed that the proportion of Ca(OH) 2 from the samples ...
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Abstract
Sodium alkoxides, namely, sodium n -propoxide and sodium iso-propoxide were synthesized and characterized by various analytical techniques. Thermal decomposition of these compounds was studied under isothermal and non-isothermal conditions using a thermogravimetric analyzer coupled with mass spectrometer. The onset temperatures of decomposition of sodium n -propoxide and sodium iso-propoxide were found to be 590 and 545 K, respectively. These sodium alkoxides form gaseous products of saturated and unsaturated hydrocarbons and leave sodium carbonate, sodium hydroxide, and free carbon as the decomposition ...
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Abstract
Biomass is an effective substitute for fossil fuels and has a substantial impact on CO 2 reduction. Meanwhile, alkali metal-related problem is a major barrier in biomass combustion. Sludge is a waste with low heating value, high water, sulfur, and nitrogen contents, as well as high phosphorus content, which makes the sludge a potential choice to inhibit the alkali metal-related problems during biomass combustion. The nitrogen behavior and the emissions of NO x and N 2 O are one of the ...
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Abstract
The oxo-diperoxo-molibdenum(VI)-potassium oxalate, K 2 [MoO(O 2 ) 2 (C 2 O 4 )] was synthesized using an adapted version of the method suggested by Dengel. The thermal behavior of the synthesized complex was investigated by simultaneous thermal analysis TG/DTG/DTA, in air or nitrogen atmosphere, to identify and characterize the mass-loss decomposition processes. In addition, for the characterization of the observed decomposition steps, the FT-IR spectra for the initial complex, evolved gaseous compounds and isolated complex at 230 and 430/383 °C ...
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Abstract
This work shows the evaluation of three antioxidants (2,6-di- t -butyl-4-methylphenol (BHT)—synthetic antioxidant, hydrogenated cardanol (HC), and alkyl hydrogenated cardanol (AHC)—both derived from cashew nut shell liquid) on the thermo-oxidative stability of the soybean biodiesel. The antioxidants were added at concentrations of 200, 300, and 400 ppm, and the oxidative stability of the biofuel with and without antioxidants were investigated by thermogravimetric analysis (TG-DTG and IPDT) and Metrohm 743 Rancimat per the EN 14112 method. The results showed that all antioxidants ...
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Abstract
Solid–liquid equilibria for three binary mixtures of n -eicosane (1) + methyl palmitate (2), n -tetracosane (1) + methyl stearate (2) and n -octacosane (1) + methyl stearate (2) were measured using differential scanning calorimeter. Simple eutectic behaviours for these systems were observed. The experimental results were correlated by means of the modified UNIFAC (Larsen and Gmehling versions), UNIQUAC and ideal models. The root-mean-square deviations of the solubility temperatures for all measured data vary from 0.21 K (for ...
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Abstract
In the present study, different transition metal forms of montmorillonite have been intercalated with mono-, di-, and triethanolammonium cations via d coordination mechanism to investigate their thermal behavior, structural characteristics, surface properties, and elemental composition using TG, XRD, BET, and CHNS techniques. Thermogravimetric analysis showed two thermal transition steps for transition metal-exchanged montmorillonites, which attributed to desorption of the physically adsorbed water and hydrated water, and dehydroxylation of the structural water; whereas for ammonium-montmorillonite complexes, the TG curves showed three thermal ...
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Abstract
The aim of this study is to develop a method and to determine by means of isothermal microcalorimetry the activity of supercritical extracts obtained from growth-controlled wormwood ( Artemisia absinthium L.) over Spodoptera littoralis L. ( S. littoralis ), a polyphagous pest of the Mediterranean crops. In order to achieve this goal, a three-step microcalorimetric method has been developed to insure the quality of the measurements and the validity of the results. Once optimized, different extracts of wormwood obtained by means ...
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Abstract
Recently, Drebushchak (J Therm Anal Calorim 103:753–759, [ 1 ]) has stated that, “Various ways of thermodynamic evaluations can yield different results, contradicting to one another,” and that, “Thermodynamics is not a rigorous mathematical science.” These are radical claims. If they were true, thermodynamics as it is now understood would have to be abandoned. In this paper, I will defend thermodynamics by demonstrating that these statements are incorrect. Thermodynamics remains a valid, self-consistent scientific theory, and we are justified in continuing ...
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Abstract
The critical temperature and mechanism functions for thermal decomposition of ε-CL-20, RS-ε-CL-20, α-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4 were evaluated based on non-isothermal TG data. A two-step mechanism has been found for thermal decomposition of α-CL-20, ε-CL-20/C4, and RS-ε-CL-20/C4, where the initial step is partly controlled by crystal structure of CL-20. The more reasonable mean activation energies could be obtained after peak separation for each individual steps. In fact, the activation energy for the post integrated process is almost equivalent with that of ...
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Abstract
In the present work, the temperature dependence of heat capacity of dipotassium diiron(III) hexatitanium oxide has been measured for the first time in the range from 10 to 300 K by means of precision adiabatic vacuum calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity $$ C_p^ \circ (T) $$ , enthalpy $$ H^ \circ (T) - H^ \circ (0) $$ , entropy $$ S^ \circ (T) - S^ \circ ...
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Abstract
A solid urethane acrylate macromonomer with bis-aromatic as well as alicyclic moieties was synthesized and the kinetics of photopolymerization reactions were studied in the presence of varying concentration of photoinitiator and large excess of reactive diluent using photo DSC. The studies show that the rate of maximum polymerization was found to increase with increase in concentration of photoinitiator while a decrease was observed by an increase in temperature. The final conversion showed a decrease at highest isothermal condition due to vitrification. ...
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Abstract
The objective of the present investigation was to study the effect of eutectic formation on in vitro dissolution of simvastatin (SIM) released from mixtures with acetylsalicylic acid (ASA) prepared by a grinding method. SIM–ASA mixtures were characterized by means of differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray powder diffractometry (XRPD), and in vitro dissolution tests. IR spectroscopy and XRPD studies indicated no interaction between SIM and ASA in the solid state. The DSC investigation has revealed that SIM and ASA ...
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Abstract
Using the thermochemical approach to interpret the kinetics of heterogeneous reactions and the mechanism of congruent dissociative decomposition of solids developed in the 1980s and (re)analyzing the experimental data available in the literature over the last 90 years, a novel mechanism for the catalytic oxidation of H 2 by PtO 2 is proposed. In place of the conventional Langmuir–Hinshelwood and Eley–Rideal adsorption reaction mechanisms, our model is based on the reactions: PtO 2 (s) + 2H 2 ↔ Pt(g) + 2H ...
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Abstract
The NiTi SMA was studied by temperature (mainly at 373 K) and by stress–temperature aging. The temperature induces monotonic changes in Rs transformation temperature near 10–20 K/year. The simultaneous stress/temperature aging produced strong changes in the stress–strain cycles and in the necessary stress to continue transforming with an increase of maximal stress near 45 MPa/month at 373 K. ...
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Abstract
The present investigation concerns with thermal analysis of biomaterials such as Chitosan, Xanthan gum, Guar gum Pectin, Karaya gum, Sodium alginate, and Psyllium husk mucilage. The DSC curve of the natural polymers showed its specific endothermic peaks and Δ H f values, and these will be helpful in determining the fitness of the polymers with active drug. The drug and natural polymer compatibility study is now one of the recognized methods for preformulation step in pharmaceutical drug development. All the natural ...
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Abstract
Thermal oxidation of commercial ilmenite concentrate from Kahnouj titanium mines, Iran, at 500–950 °C was investigated for the first time. Fractional conversion was calculated from mass change of the samples during oxidation. Maximum FeO to Fe 2 O 3 conversion of 98.63 % occurred at 900 °C after 120 min. Curve fit trials together with SEM line scan results indicated constant-size shrinking core model as the closest kinetic mechanism of the oxidation process. Below 750 °C, chemical reaction with activation energy ...
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Abstract
Thermodynamical, optical, and electrical properties of the binary mixtures of cholesteryl myristate (ChM) and 4- n -decyloxybenzoic acid (DOBA) have been carried out by the differential scanning calorimeter, polarized optical microscopy (POM), and impedance spectroscopy. Through thermodynamic study, various phase transition temperatures, transition enthalpies, and transition entropies have been determined to investigate temperature range and stability of the mesophases of the mixtures. Phase diagrams in the heating and cooling cycles have been drawn for the ChM–DOBA binary system. Optical textures of ...
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Abstract
For a complete picture of the phase behavior of a compound exhibiting dimorphism, not only the temperature but also the pressure, the second variable of the Gibbs energy, should be taken into account. Because volume reflects the dependence of the Gibbs energy on pressure, investigating the specific volumes of a compound provides information on its phase behavior under pressure. This can be quantified using the Clapeyron equation, which leads to a so-called topological pressure–temperature phase diagram. Bicalutamide is used as a ...
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Abstract
Several metallic tartrates deserve special attention due to their various applications. In the present investigation, mixed tartrate crystals of three different metals are reported. Using single diffusion gel growth technique, iron–nickel–manganese (Fe–Ni–Mn) ternary levo-tartrate compound crystals were grown with different concentrations. Spherulitic crystals with different coloration were obtained for various concentrations of metals. The concentrations of metals were determined by EDAX. The presence of functional groups was confirmed using Fourier transform infrared (FT-IR) spectroscopy. The powder XRD study suggested that the ...
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Abstract
Isothermal titration calorimetry (ITC) and potentiometric titration (PT) methods were used to study the interactions of cobalt(II) and nickel(II) ions with buffer substances 2-( N -morpholino)ethanesulfonic acid (Mes), dimethylarsenic acid (Caco), and piperazine- N , N ′-bis(2-ethanesulfonic acid) (Pipes). Based on the results of PT data, the stability constants were calculated for the metal–buffer complexes ( T = 298.15 K, ionic strength I = 100 mM NaClO 4 ). Furthermore, calorimetric measurements (ITC) were run in 100 mM Mes, Caco, and ...
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Abstract
In this study, thermal analysis in differential scanning calorimetry associated to Fourier self-deconvolution (FSD) of infrared spectra was applied to the study of anaerobic digestion of the organic fraction of domestic solid waste and sewage sludge mixed in 1:1 ratio under mesophilic and thermophilic conditions. Curves showed an exothermic peak in the high-temperature range and a number of endothermic and/or exothermic peaks in the low- and medium-temperature range. The high-temperature exotherm was a common feature on curves of all samples. Digestates ...
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Abstract
2-Hydroxy-3-methoxybenzaldehyde semicarbazone (HMBS) has been synthesized from 2-hydroxy-3-methoxybenzaldehyde and semicarbazide hydrochloride using sodium acetate as catalyst. Good quality single crystals of HMBS were successfully grown by slow evaporation method at room temperature using a mixture of DMF and ethanol as solvent. Fourier transform infrared and Fourier transform Raman spectral studies have been performed to identify the functional groups. Single-crystal XRD study was conducted to obtain the crystal structure and lattice parameters. The grown crystal was subjected to 1 H- and 13 ...
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Abstract
This study investigated the capacity of fast-scan (400 °C min −1 ) against conventional (10 °C min −1 ) differential scanning calorimetry (DSC) techniques to track crystallization phenomenon in tolbutamide–polyethylene glycol 3000 composites prepared by hot melt method (mass ratios 1:1, 1:5, and 1:9) and stored at 25 and 75 % relative humidities. Drug crystallization in composites was indicated by X-ray diffractometry (XRD) and scanning electron microscopy characterization over 40 days storage. With reference to XRD as gold measurement standard, fast-scan ...
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Abstract
Co-precipitation of alumina/YAG precursor from aluminum and yttrium nitrates solution with ammonium carbonate results in dawsonite (NH 4 Al(OH) 2 CO 3 ). Its crystallographic parameters differ from the compound precipitated without the yttrium additive. It indicates that yttrium ions become incorporated into the dawsonite structure. The DSC/TG and X-ray measurements show decomposition of dawsonite at elevated temperature resulting in γ-Al 2 O 3 which transforms to δ and θ modifications at still higher temperatures. The full transformation to α-Al 2 ...
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Abstract
Coal combustion catalysts of mesoporous perovskite-type La 1−x Ca x MnO 3 were prepared by sol–gel method. The resulting powder was characterized by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, dynamic light scattering and differential scanning calorimetry. After partially substituting La with Ca in LaMnO 3 , Ca was found to occupy parts of La-site. As the substitution rate of Ca increased, the catalyst particle size distribution decreased and the pore size distribution of catalysts increased. Thermogravimetric measurements and combustion ...
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Abstract
The standard Gibbs energy of formation of chromium tellurate, Cr 2 TeO 6 was determined from the vapour pressure measurement of TeO 2 (g) over the phase mixture Cr 2 TeO 6 (s) + Cr 2 O 3 (s) in the temperature range 1,183–1,293 K. A thermogravimetry (TG)-based transpiration technique was used for the vapour pressure measurement. This technique was validated by measuring the vapour pressure of CdCl 2 (g) over CdCl 2 (s). The temperature dependence of the vapour pressure ...
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Abstract
Bio-composites (FF-PFA-D) were successfully compression moulded by reinforcing polyfurfuryl alcohol (PFA) with 10 layers of woven flax fabric (FF). FF-reinforced PFA-based bio-composites were then immersed in water to get wet bio-composite samples (FF-PFA-W). Mechanical and impact properties of the bio-composites in dry and wet state were determined. Characterisations of the bio-composites were performed by thermogravimetric analysis, thermomechanical behaviour, and cone calorimeter data. Results indicated the increase in α-relaxation temperature for FF-PFA-W. SEM micrograph showed that the flax fibres were completely coated ...
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posted by
1 person
andrzejwasiak
Abstract
Isotactic polypropylenes (iPP) samples were incorporated with two β-nucleating agents (NT-A and NT-C), respectively, and their non-isothermal crystallization and subsequent melt behaviors were investigated by means of differential scanning calorimeter. Jeziorny, Ozawa, and Mo methods were used to analyze non-isothermal crystallization kinetics of pure iPP and β-nucleated iPP samples. The activation energies (Δ E ) of non-isothermal crystallization were calculated by Kissinger method. And the nucleation activities were calculated according to the Dobreva method. It is found that the crystallization temperature ...
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Abstract
The phase transitions proceeding during melting of selected Sn–Ag–Cu alloys were determined by means of the DSC technique. Twelve compositions were studied along two cross-sections with silver to copper molar ratios X (Ag)/ X (Cu) = 1 and 7/3 and tin concentration from 0.4 to 0.9 mol fraction. The transition temperatures were calculated using Pandat software package and thermodynamic parameters from the SOLDERS database. The experimental results were compared with both available literature data and calculation results, and a good agreement ...
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Abstract
The experimental FTIR spectra and DSC curves of the ternary 40TeO 2 –(60− x )V 2 O 5 –xNiO glasses with 0 ≤ x ≤ 30 (in mol%) have been investigated. The glass transition properties that have been measured and reported in this paper, include the glass transition temperature ( T g ), glass transition width (Δ T g ), heat capacity change at glass transition (Δ C P ) and Fragility ( F ). Thermal stability, fragility, and glass-forming tendency ...
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Abstract
The present paper involves the synthesis of polyaniline (PANI) composite with photoadduct of potassium hexacyanoferrate (II) involving hexamine as a ligand and cobalt chloride as a complexing agent via in situ oxidative polymerization by ammonium persulphate. The photoadduct has been synthesized by photoirradiation followed by substitution with the hexamine ligand. The final product has been isolated by using CoCl 2 as complexing agent. Viscosity average molar mass has been determined by viscosity method using Ostwald’s viscometer. The photoirradiation, substitution, and successful ...
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Abstract
Chemical looping air separation (CLAS) has been suggested as a new and energy saving method for producing oxygen from air. The selection of suitable oxygen carriers is the key issue for CLAS system. This paper shows a comprehensive thermodynamic method for selecting oxygen carriers used for CLAS through studying the properties of 34 different oxygen releasing reactions referring to 18 elements at different temperatures. The research mainly includes analysis of oxygen releasing capacity by calculating the Gibbs free energy change (Δ ...
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Abstract
In the present work, the possibilities of application of the thermomagnetometry TG(M)/DTG(M) method for estimation of the phase homogeneity of end products of synthesis at different stages of ferritizing annealing are considered on the example of solid-state synthesis of Li 0.5(1−x) Fe 2.5−0.5x Zn x O 4 and Li 0.5(1 + x) Fe 2.5−1.5x Ti x O 4 ( x = 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6) lithium-substituted ferrospinels. Results of thermomagnetometric analysis are compared with XRD data. It is ...
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