An investigation on eutectic binary phase diagram of volatilizable energetic materials by high pressure DSC

The eutectic binary phase diagrams of volatilizable energetic material 1,3,3-trinitroazetidine (TNAZ) with 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and 1-methyl-2,4-dinitroimidazole (MDNI) have been investigated by high pressure differential scanning calorimeter (PDSC), respectively. The liquefying and melting processes of TNAZ/RDX and TNAZ/MDNI volatilizable systems have been studied. On the basis of the data of apparent fusion heat and liquefying temperature, the phase diagrams of apparent fusion heat (H) with composition (X) and liquefying temperature (T) with composition (X) were constructed, respectively. The results showed that the gasification or volatilization of easy volatile energetic materials could be efficiently restrained by high pressure atmosphere, and the perfect and ideal phase diagrams can be constructed. The eutectic temperatures for TNAZ/RDX and TNAZ/MDNI are measured to be 95.5 and 82.3 °C, respectively. The eutectic compositions of mole ratios for the two systems are obtained to be 93.55/6.45 (T–X method), 93.79/6.21 (H–X method) and 62.25/37.75 (T–X method), 63.29/33.71 (H–X method), respectively.     

Thermal Analysis of Solid-Solid Interactions in Binary Mixtures of Alkylcyclohexanes Using DSC

Differential scanning calorimetry (DSC) was used to construct phase diagrams of binary mixtures of alkylcyclohexanes and to characterize metastable phases formed in the binary mixtures. The experimentally measured liquidus curves were compared to the liquidus curves calculated using ideal solution theory. The measured phase diagrams of pentadecylcyclohexane/nonadecylcyclohexane and octadecylcyclohexane/nonadecylcyclohexane binary mixtures are consistent with theoretical phase diagrams constructed based on the assumption that these mixtures form eutectic systems. It was also observed that a metastable phase formed in some binary mixtures of pentadecylcyclohexane/nonadecylcyclohexane under fast cooling conditions. It is hypothesized that this metastable phase recrystallizes into the eutectic phase upon heating. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ternary phase diagrams of DNTF and TNAZ and their eutectics

The eutectic ternary phase diagrams of some typical volatilizable energetic materials have been investigated by high pressure differential scanning calorimeter (PDSC). The ternary H–X phase diagrams for TNT/TNAZ/DNTF (TTD) and TNAZ/DNTF/RDX (TDR) systems were constructed by the correlation of the apparent fusion heat with the composition (H–X method). And, the ternary T–X phase diagrams (the temperature dependence on composition) for the two ternary systems were constructed by calculating from the data of the five T–X binary phase diagrams. The eutectic compositions (mol%) of TTD and TDR ternary systems were obtained to be 52.3/27.3/20.4 (H–X method), 53.2/25.8/21.0 (T–X method) and 54.9/39.6/5.5 (H–X method), 55.1/42.2/2.7 (T–X method), respectively. The eutectic temperatures of the ternary systems were obtained by PDSC determination and T–X method calculation to be 76.5 and 76.7 °C, 47.5 and 50.2 °C, respectively. It is shown that the results obtained by two methods are in agreement and the error in measuring or calculating eutectic compositions and temperatures for the two ternary systems are within allowable ranges of ±3 mol% and ±3 °C, respectively. Moreover, by means of constructing two ternary H–X phase diagrams with different fixed composition of a component and comparing the apparent fusion heat of eutectics with calculated one, the results obtained from H–X method for TTD system were proved. The results showed that the gasification or volatilization of easy volatile materials could be efficiently restrained by high pressure atmosphere, and the perfectly and ideally H–X ternary phase diagrams can be constructed. In comparison with T–X method, H–X method has as a virtue of being quick and simple, especially on constructing ternary phase diagram.     

Use of the Wilson equation to calculate solid-liquid phase equilibria in binary and ternary systems

Generalized formulation is presented for calculating simple eutectic type solid-liquid phase diagrams for binary and ternary systems by using the Wilson equation for molar excess Gibbs energy in the liquid phase. The liquidus surface and eutectic points of molten salt mixtures with a common ion were calculated and compared with experimental values. The average error in the estimation of ternary eutectic composition was ± 0.013 (mole fraction) for the two ternary systems tested. The agreement was generally better than that obtained with the regular solution approximation.     

Partial phase diagrams for the water—cadmium nitrate, water—silver nitrate and water—cadmium nitrate—silver nitrate systems

Sub-ambient differential scanning calorimetry has been used to determine partial binary phase diagrams for the water—silver nitrate and water—cadmium nitrate systems. Both systems are shown to be eutectic with eutectic temperatures of 263 ± 0.5 K and 256.5 ± 0.5 K for the water—silver nitrate and water—cadmium nitrate systems, respectively. The eutectic compositions are at approximately 40.5 wt.% nitrate for each system. The freezing of ternary solutions containing a fixed silver nitrate/cadmium nitrate ratio but increasing concentrations of total nitrates are explained in terms of a partial ternary system containing two binary eutectic systems and a ternary eutectic reaction. The ternary eutectic temperature is shown to be 254 ± 0.5 K.     

Thermoanalysis of binary condensed eutectic phases evincing molecular interactions

This article discusses the thermoanalytical model developed in the current work to study the influence of the molecular interactions between binary condensed eutectic phases in terms of excess thermodynamic functions that exhort the ability of providing quantitative idea of the interactions. Non-ideality of binary eutectic systems over the entire range of mole fraction composition is ascertained by subjecting the experimentally determined solidus?Cliquidus equilibrium data to thermodynamic analysis and thereby, apprehending quantitative idea about the nature of molecular interactions. The estimation of molecular interactions model of binary naphthalene?Co-nitrophenol, ??-naphthol?Cnaphthalene, diphenylamine?C??-naphthol, benzil?Cdiphenyl, acenaphthene?Cantimonytrichloride and cadmium?Cbismuth eutectic systems authenticates the reliability of the excess functions, since the mixing of the eutectic phases either side of solidus?Cliquidus equilibrium curves of the systems is found to follow the criteria of spontaneity and Planck formulation S?=?klnw; where S, k and w, respectively, are the configurational entropy, Boltzmann constant and complexion number of constituent phase molecules. Moreover, the Guggenheim lattice theory applied to solidus mixtures at their liquidus temperatures offers supporting evidence to the essence of the excess functions and hence the thermomolecular interactions model.     

Computer models of eutectic-type <Emphasis Type="Italic">T</Emphasis>–<Emphasis Type="Italic">x</Emphasis>–<Emphasis Type="Italic">y</Emphasis> diagrams with allotropy

Using the eutectic-type T–x–y diagram as an example, it can be represented the analysis of its geometrical construction dependence on the temperature of a component two polymorphous modifications which participate in mono- and invariant metatectic and invariant eutectic (eutectoid) transformations above or below (and within) binary eutectics temperature intervals and below a ternary eutectic temperature. Computer models for considered phase diagrams have been designed. Such models help to solve applied tasks like visualization, isopleths and isothermal sections decoding, mass balances calculation and evaluation of phase and conglomerate concentration in microstructure.     

The solid-liquid phase diagrams of binary mixtures of even saturated fatty alcohols

This study is part of a work developed in the author's research group on the solid-liquid equilibrium of fatty substances. The phase diagrams of the following fatty alcohol systems were determined by differential scanning calorimetry (DSC): 1-octanol + 1-dodecanol, 1-octanol + 1-tetradecanol, 1-decanol + 1-tetradecanol, 1-decanol + 1-hexadecanol and 1-dodecanol + 1-octadecanol. The liquidus lines of three of these systems were previously reported in the literature but the other two systems were never published. Moreover other transitions, in addition to the eutectic temperature, were also detected in all the systems. A region of solid solution at the extreme left of the phase diagrams was observed for all the binary mixtures. Polarized light microscopy was used to complement the characterization of the systems for a full grasp of the phase diagrams. The solid-liquid equilibrium was modeled using the Margules 2-suffix, Margules 3-suffix, NRTL and UNIFAC Dortmund equations.     

Phase diagrams for the binary systems CaCl2-KCl and CaCl2-CaCrO4

Phase diagrams have been determined using differential thermal analysis for the binary systems CaCl₂-KCl and CaCl₂-CaCrO₄. CaCl₂-KCl phase diagrams have been previously reported but results were not consistent. No prior studies have been reported for the CaCl₂-CaCrO₄ system. In the CaCl₂-KCl binary system two eutectics have been located at 24.0 mole % KCl (m.p. 615°C) and 74.3 mole % KCl (m.p. 594°C). A double salt of composition CaKCl3 melting congruently at 741°C has been found. The CaCl₂-CaCrO₄ system is a simple eutectic system with the eutectic occurring at 23.4 mole % CaCrO₄ and melting at 660°C.     

Structural evolution in binary halide systems with cations in the oxidation state +1

We analyze the structural evolution of binary halide systems with a common anion and cations in the oxidation state +1. For eutectic-type liquid-solid diagrams and in diagrams containing incomplete solid solutions or solid solutions with a liquidus minimum, absolute and relative deflections of the experimental liquidus curve from the ideal curve were determined. The major factors are recognized influencing the structural evolution from systems containing solid solutions to eutectic systems with a positive deflection of the experimental liquidus from the ideal curve and then to ideal eutectic systems, as well as from ideal eutectic systems to eutectic systems with a negative deflection of the experimental liquidus from the ideal curve and then to systems containing compounds.     

Solubility of polystyrene in selectively deuterated methyl acetate

Cloud point measurements were made for binary systems of polystyrene (PS) + methyl acetate (MA) and polystyrene (PS) + selectively deuterated MA: CD₃COOCH₃ and CH₃COOCD₃ with three PS samples of M_w = 4.0 × 10⁵, 2.0 × 10⁶, and 13.2 × 10⁶. All systems are characterized by the phase diagrams with upper and lower critical temperature. H/D isotope effects on miscibility for both selectively deuterated acetates are very large and appeared to be independent of the site of deuterium substitution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47:2140–2143, 2009     

Some thermochemical studies on binary faceted organic eutecitcs and 1∶1 molecular complexes

The phase diagrams of binary organic systems of benzidine with pyrogallol andp-nitrophenol give a double simple eutectic type phase diagram showing formation of a 1∶1 molecular complex with congruent melting point and two eutectics. The growth data on the pure components, the eutectics and the molecular complexes, determined by measuring the rate of movement of growth front in a capillary, justify the square relationship between growth velocity and undercooling. While enthalpy of mixing values suggest intermolecular hydrogen bonding, the excess thermodynamic functions reveal strong interactions among the components forming eutectics and addition compounds.     

Enumeration of melting diagrams of three-component systems with stoichiometric compounds

The topologic isomorphism of polyhedra having trivalent vertexes and phase diagrams of three-component systems allows the reduction of the problem of constructing the complete set of topologic types of diagrams having given characteristics to the problem of generating labeled cubic graphs. Each of them is the Schlegel projection of some polyhedron on one of its faces. This work is concerned with the problem of enumeration possible topologic types of phase diagrams containing M binary and N ternary stoichiometric compounds. Relations between the topologic characteristics of these diagrams are presented. A great variety of types of diagrams of the class in question is demonstrated.     

Effect of orientation of lateral methyl substituent on the thermal behaviour of the mesophase in binary systems of 4-substituted phenyl 4ʹ-(4”-alkoxy phenylazo) benzoates

Several binary systems made from two laterally substituted azo/ester isomers, namely 2?- (and 3?-) methyl-4-substituted phenyl 4?-(4?-alkoxyphenylazo) benzoates, where the length of the terminal alkoxy group = 8 and 16 carbons, while the other terminal substituent, X, varies between CH₃O, CH₃, H, Br and CN groups, were investigated using differential scanning calorimetry (DSC) and phases identified by polarised light microscope (PLM). For the sake of comparison, two another binary systems made from 2?- (or 3?-) methyl-4-substituted phenyl 4?-(4?-alkoxyphenylazo) benzoates (n = 8 and X = CH₃) each was mixed with its laterally neat analogue and similarly investigated. Results were discussed on the basis of constructed phase diagrams whereby various mesomorphic properties were observed dependent on X, n, and position of the lateral methyl group. In most of the cases, the mixtures exhibited eutectic compositions, while linear or nearly linear nematic and smectic A-composition temperature dependence were observed.     

Thermal,physicochemical and microstructural studies of binary organic eutectic systems

Solid–liquid phase equilibrium data of three binary organic systems, namely, 3-hydroxybenzaldehyde (HB)—4-bromo-2-nitroanilne (BNA), benzoin (BN)—resorcinol (RC) and urea (U)—1,3-dinitrobenzene (DNB), were studied by the thaw–melt method. While the former two systems show the formation of simple eutectic, the third system shows the formation of a monotectic and a eutectic with a large immiscibility region where two immiscible liquid phases are in equilibrium with a liquid of single phase. Growth kinetics of the pure components, the monotectic and the eutectics, studied by measuring the rate of movement (v) of solid–liquid interface in a thin U-tube at different undercoolings (ΔT) suggests the applicability of the Hillig–Turnbull’s equation: v = u (ΔT) ⁿ , where v and n are the constants depending on the nature of the materials involved. The thermal properties of materials such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy, and excess thermodynamic functions were computed from the enthalpy of fusion values, determined by differential scanning calorimeter (Mettler DSC-4000) system. The role of solid–liquid interfacial energy on morphologic change of monotectic growth has also been discussed. The microstructures of monotectic and eutectics were taken which showed lamellar and federal features.     

Phase equilibrium study of the binary systems (N-hexyl-3-methylpyridinium tosylate ionic liquid + water,or organic solvent)

The (solid + liquid) phase equilibrium (SLE) and (liquid + liquid) phase equilibrium (LLE) for the binary systems ionic liquid (IL) N-hexyl-3-methylpyridinium tosylate (p-toluenesulfonate), {([HM³Py][TOS] + water, or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or an aromatic hydrocarbon (benzene, toluene, or ethylbenzene, or propylbenzene), or an alkane (n-hexane, n-heptane, n-octane)} have been determined at ambient pressure using a dynamic method. Simple eutectic systems with complete miscibility in the liquid phase were observed for the systems involving water and alcohols. The phase equilibrium diagrams of IL and aromatic or aliphatic hydrocarbons exhibit eutectic systems with immiscibility in the liquid phase with an upper critical solution temperature as for most of the ILs. The correlation of the experimental data has been carried out using the UNIQUAC, Wilson and the non-random two liquid (NRTL) correlation equations. The results reported here have been compared with analogous phase diagrams reported by our group previously for systems containing the tosylate-based ILs.     

Thermophysical behaviour of monofunctional acrylate and liquid crystal systems

The phase behavior of monofunctional acrylate and low molecular weight nematic liquid crystals (LC) is considered. Systems involving the monomeric 2-ethylhexylacrylate (2-EHA), the eutectic LC mixture known as E7 and the 4-cyano-4^′-n-pentyl-biphenyl (5CB) are investigated. A similar investigation is performed on mixtures involving a polymer poly-2-EHA with molecular weight M_w=48,000 g/mol and both LCs. The experimental phase diagrams are established using polarized optical microscopy and analyzed using a theoretical formalism which combines the Flory-Huggins theory of isotropic mixing and the Maier-Saupe theory of nematic order. The results lead to characterization of the miscibility of E7 and 5CB with monomeric and analogous polymeric 2-EHA systems.     

Solid solutions in binary halide systems having a common anion

Deviations of experimental liquidus curves from ideal curves calculated by the Schröder equation are analyzed for halides that form eutectic systems and systems containing solid solutions. Analysis of phase diagrams shows that the key factors for solid solution formation in binary halide systems having a common anion are as follows: component crystal lattices and close values of the effective radii and polarizing powers of the cations.     

稀土碘化物的合成及其发光性质的研究

本文将纯稀土金属与碘化汞在加温下合成了钪、镝、铒和铥的碘化物。并用DTA方法测定了NaI-ScI_3,NaI-DyI_3,NaI-ErI_3和NaI-TmI_3二元体系的相图,它们都是简单的有低共熔点的二元体系,但是后面三个体系在固相有相变,可能是形成了不稳定的化合物。文中还制造了填充不同比例的碘化钠和稀土金属碘化物混合物的金属卤化物灯,将它们的发光特性与汞灯进行了比较。碘化钠和稀土金属碘化物的加入能明显地改善灯的色温,显色性和光效。     

Phase diagrams of binary crystalline-crystalline polymer blends

A thermodynamically self-consistent theory has been developed to establish binary phase diagrams for two-crystalline polymer blends by taking into consideration all interactions including amorphous-amorphous, crystal-amorphous, amorphous-crystal, and crystal-crystal interactions. The present theory basically involves combination of the Flory-Huggins free energy for amorphous-amorphous isotropic mixing and the Landau free energy of polymer solidification (e.g., crystallization) of the crystalline constituents. The self-consistent solution via minimization of the free energy of the mixture affords determination of eutectic, peritectic, and azeotrope phase diagrams involving various coexistence regions such as liquid-liquid, liquid-solid, and solid-solid coexistence regions bound by liquidus and solidus lines. To validate the present theory, the predicted eutectic phase diagrams have been compared with the reported experimental binary phase diagrams of blends such as polyethylene fractions as well as polycaprolactone/trioxane mixtures.