Phase Diagram Behavior Research Articles

Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

Background:The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.Methods:Nonionic surfactant blends of Tween® and Tween®/Span® series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween® 80 and five blends of Tween® 80/Span® 80 and Tween® 80/Span® 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7–14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature.Results:High solubilization capacity was obtained by Tween® 80 compared with other surfactants of Tween® series. High HLB blends of Tween® 80/Span® 85 and Tween® 80/Span® 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween® 80/Span® 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween® 80 and the oleyl group of the palm kernel oil esters.Conclusion:This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics.

Publisher’s Note: Phase diagram and critical behavior of a forest-fire model in a gradient of immunity [Phys. Rev. E83, 011125 (2011)

Publisher’s Note: Phase diagram and critical behavior of a forest-fire model in a gradient of immunity [Phys. Rev. E83, 011125 (2011)

Study of Pseudoternary Phase Diagram Behaviour and the Effect of Several Tweens and Spans on Palm Oil Esters Characteristics.

Palm oil esters are high molecular weight esters oil that has been newly synthesized by University Putra Malaysia researchers. It has received a lot of attention for its pharmaceutical and chemical application. The aim of this study is to study the effects of the palm oil esters with different HLB surfactant mixture on the ternary diagrams behaviour and to confine the various systems resulted from these combinations. These systems include traditional emulsion, gel area, transpernat micro-emulsion area, O/W and W/O emulsions. In this study, pseudoternary phase diagrams of water, POEs and non-ionic surfactant mixture of several HLB values were constructed using water titration method. The resultant mixtures collected after each addition and mixing of water were analysed visually, along with conductivity, dilution in water and dye test (methylene blue) to classify them as O/W emulsion (transparent and opaque) or W/O (opaque) and liquid or gel. As a conclusion, palm oil esters were found to be suitable for the formulation of different types of emulsion. Additionally, different HLB value of non-ionic surfactant(s) exhibited different pseudoternary phase diagram characteristics. Keywords: palm oil esters, Tween, Span, Pseudoternary phase diagram, O/W emulsion

Systematic investigation of global phase behavior of polymer mixtures in the pressure-temperature plane

We investigate the critical lines of polymer mixtures in the presence of their vapor phase at the mathematical double point, where two critical lines meet and exchange branches, and its environment. The model used combines the lattice gas model of Schouten, ten Seldam and Trappeniers with the Flory-Huggins theory. The critical line structure is displayed for various combinations of the chain length and system parameters in the pressure (P)-temperature (T) plane, as is usually done with experimental results. This type of work sheds light on the essential transition mechanism involved in the phase diagram's change of character, such as multi-critical points and mathematical double points, which are of great practical importance in supercritical fluid extraction processes. The P, T diagrams are discussed in accordance with the Scott and van Konynenburg binary phase diagram classification. We found that our P, T plots were in agreement with type II, type III, or type IV phase diagram behaviors. We also found that some of our phase diagrams represent the liquid-liquid equilibria in polymer solutions and mixtures.

Global phase diagrams for a compressible polymer-solvent system using the full Tompa model

We present the global phase diagrams for a compressible polymer-solvent system at the mathematical double point and its environment by using the full Tompa model for varying numbers of segments in each polymer chain. A principal transition mechanism is a mathematical double point at which two critical lines meet and exchange branches. We present the critical lines in the density-density and the P, T planes in detail. The locations of all significant features of the phase diagrams are described and compared with Scott and van Konynenburg phase diagram classifications. We find the type II, type III or type IV phase diagram behaviors of the Scott and van Konynenburg classifications. It is also found that the critical lines and phase behavior are extremely sensitive to small modifications in the chain length parameter.

1P-120 格子間隔に依存した2状態モデルにおける筋肉の状態相図(筋肉(筋蛋白質・収縮),第47回日本生物物理学会年会)

1P-120 格子間隔に依存した2状態モデルにおける筋肉の状態相図(筋肉(筋蛋白質・収縮),第47回日本生物物理学会年会)

1TA2-06 格子間隔に依存した2状態モデルにおける筋肉の状態相図(筋肉(筋蛋白質・収縮),第47回日本生物物理学会年会)

1TA2-06 格子間隔に依存した2状態モデルにおける筋肉の状態相図(筋肉(筋蛋白質・収縮),第47回日本生物物理学会年会)

Phase Diagram and Precipitation Behaviour in Ni-Rich Region of Ni-Ta-Al Ternary System

Tantalum (Ta) addition is one of the promising method for increasing the strength of Ni-based wrought alloys such as Inconel 718, because Ta is an element having a high melting temperature. For wrought alloys, it is necessary to make clear the phase relationships at 700~1000°C, but there is a few report on phase diagrams of Ni-Ta and Ni-Ta-Al systems at those temperatures. In this study, the phase diagram in Ni-rich region of Ni-Ta-Al system at 800°C, which is the important temperature for the practical use of the wrought alloys, was investigated. The equilibrium relations of each phase were examined by a conventional XRD, SEM/EDX and TEM observations. It was found that the γ-phase region expanded considerably towards Ta-rich compositional region in Ni-Ta-Al system at 800°C. Also, it was observed that the γ phase precipitated secondarily in the primary precipitated γ’ phase in Ni-10.5mol%Ta-5.5mol%Al alloy. Ni8Ta phase was not detected even in Ni-Ta binary system in this study, although this phase was reported previously.

Influence of Molecular Structure on Phase Diagram and Ferroelectric Behaviour

Discussion on the influence of molecular structure on dynamics and ferroelectric properties of two compounds with cyanic group in achiral chain is presented. Physical properties of these two compounds have been studied by dielectric spectroscopy, DSC calorimetry, texture observations and reversal current method. Based on the results of these studies the phase sequence of the compounds and the character of the ferro- paraelectric transition have been determined. Temperature dependence of the spontaneous polarization and dielectric parameters of the soft mode suggest that the SmC* - SmA* transition is of the second order type for both compounds studied.

XY-spin fluids in an external magnetic field: An integral equation approach

We develop an integral equation approach to study anisotropic fluids with planar spins in the presence of an external field. As a result, the integral equation calculations for these systems appear to be no more difficult than those for ordinary isotropic liquids. The method presented is applied to the investigation of phase coexistence properties of ferromagnetic XY-spin fluids in a magnetic field. The soft mean spherical approximation is used for the closure relation connecting the orientationally dependent two-particle direct and total correlation functions. The Lovett-Mou-Buff-Wertheim and Born-Green-Yvon equations are employed to describe the one-particle orientational distribution. The phase diagrams are obtained in the whole range of varying the external field for a wide class of XY-spin fluid models with various ratios of the strengths of magnetic to nonmagnetic Yukawa-like interactions. The influence of changing the screening radii of the interaction potentials is also considered. Different types of the phase diagram topology are identified. They are characterized by the existence of critical, tricritical, critical end, and triple points related to transitions between gas, liquid, and para- and ferromagnetic states, accompanied by different external field dependencies of critical temperatures and densities corresponding to the gas-liquid and liquid-liquid transitions. As is demonstrated, the integral equation approach leads to accurate predictions of the complicated phase diagram behavior which coincide well with those evaluated by the cumbersome Gibbs ensemble simulation and multiple-histogram reweighting techniques.

Antiferroelectric Modes Behaviour in a Wide Temperature Range SmC*A Phase

ABSTRACT Two liquid crystalline partially fluorinated compounds: (S)–(+)–4-(1-metyloheptyloxycarbonylphenyl) 4′-(6-perfluorobutanoyloxyhex-1-oxy) biphenyl-4-carboxylate, in short MHPP(9F)HBC and (S)–(+)-4-(1-metyloheptyloxy-carbonylbiphenyl) 4′-(6-perfluorobutanoyloxyhex-1-oxy) benzoate, in short P(9F)HPMHBC, exhibiting paraelectric, ferroelectric and antiferroelectric phases have been studied by dielectric spectroscopy and spontaneous polarization measurements. These two compounds have the same molecular weight but their terminal chains at para positions are interchanged. Influence of molecular structure on the phase diagram and dielectric behaviour is presented. Two relaxation process revealed in the antiferroelectric phase are interpreted as collective modes: anti-phase and in-phase fluctuation of phase and amplitude. The reorientation around the short molecular axis does not contribute to the dielectric spectra.

XYSpin Fluid in an External Magnetic Field

A method of integral equations is developed to study anisotropic fluids with planar spins in an external field. As a result, the calculations for these systems appear to be no more difficult than those for ordinary homogeneous liquids. The approach proposed is applied to the ferromagnetic XY spin fluid in a magnetic field using a soft mean spherical closure and the Born-Green-Yvon equation. This provides an accurate reproduction of the complicated phase diagram behavior obtained by cumbersome Gibbs ensemble simulation and multiple histogram reweighting techniques.

Thermodynamics of the Farey Fraction Spin Chain

We consider the Farey fraction spin chain, a one-dimensional model defined on (the matrices generating) the Farey fractions. We extend previous work on the thermodynamics of this model by introducing an external field h. From rigorous and more heuristic arguments, we determine the phase diagram and phase transition behavior of the extended model. Our results are fully consistent with scaling theory (for the case when a “marginal” field is present) despite the unusual nature of the transition for h = 0, and the presence of long-range forces.

Column Profile Maps. 2. Singular Points and Phase Diagram Behaviour in Ideal and Nonideal Systems

The first paper of this series [Tapp, M.; Holland, S. T.; Hildebrandt, D.; Glasser, D. Ind. Eng. Chem. Res. 2004, 43 (2), 364] analyzed the behavior of ternary homogeneous distillation systems by using column profile maps, which are generated by using the difference point equation. Ideal thermodynamics was assumed, and it has been shown how using column profile maps one can devise more creative designs. This paper explores the mathematics and the topology of the maps for systems with ideal and nonideal thermodynamics by looking at the occurrence of singular points in ternary homogeneous systems depending on the values of the design parameters of the difference point and the reflux ratio. Eigenvalue and eigenvector maps have been introduced, and their usefulness for manipulating phase diagrams and therefore the column profiles has been shown. The focus of the third part lies in the application of the tools presented in this paper for distillation process synthesis and design.

Transitional behavior of phase diagrams predicted by the Redlich–Kwong equation of state and classical mixing rules

Phase diagrams predicted by the Redlich–Kwong equation of state (EOS) and classical mixing rules are discussed at the transitional states between different types of phase behavior. Mixtures containing molecules of different sizes have been considered in the analysis. Zero- and infinite-pressure reference states for the estimation of the Gibbs energy of mixing are presented. These reference states constitute hypothetical states that have been found valuable for analyzing the key features of critical lines ending at these limiting conditions. An expression for predicting the possibility of critical immiscibility at infinite pressure was developed. This expression can be useful for determination of the existence of liquid–liquid critical lines in binary systems and may be applied to every cubic EOS of van der Waals type when classical mixing rules are used. The zero-pressure approach was used for analyzing the existence of the critical lines that intersect the zero-pressure line in a P–T projection. Special attention has been given to the possibility of predicting closed loops of liquid–liquid immiscibility. Closed loops were detected at the transition from Type V to Type III, but they do not correspond to the traditional topology observed in systems of Type VI and VII. The relation of the calculated diagrams to the systems with real pure component critical properties showing closed loops of liquid–liquid immiscibility is also discussed.

Phase diagram and critical behaviour of homopolymers with steric frustration

The effect of steric frustration on the collapse of a linear homopolymer is investigated. Depending on the temperature and the strength of the frustration, we find that three different phases exist: swollen, compact and branched. We study the phase diagram and the critical behaviour of the system through exact enumerations and Monte Carlo simulations. In addition we present an analytical argument which determines qualitatively the phase boundaries. Despite the similarity between our model and one previously introduced in the literature, there is a discrepancy on the value of a critical exponent.

Fluctuations of polymerized, fluid and hexatic membranes: Continuum models and simulations

The thermal behavior of membranes — surfaces of ultra-low tension — depends strongly on their internal state, which can be either fluid, crystalline (or polymerized), or hexatic. Thermal fluctuations have a dramatic effect on the conformation and elastic properties of membranes. Current research focuses on three areas: first, the properties of polymerized membranes with self-avoidance, attractive interactions, disorder, or external compression forces; second, the phase diagram and scaling behavior of fluid vesicles as a function of bending rigidity and pressure increment; and third, the destabilization of the crystalline phase by free dislocations at any finite temperature, and the properties of the resulting hexatic phase. Recent progress in this field is due to a fruitful interaction between theory and simulation studies of simple network models of membranes.

Chitin–cellulose blends: phase properties in dimethylacetamide–LiCl

AbstractChitin–cellulose blends dissolved in dimethylacetamide containing LiCl (7% w/w) have been studied in a wide concentration range, from very dilute solutions to medium concentrations and up to solid films (absence of diluent).The intrinsic viscosities at various chitin–cellulose ratios, as well as the phase diagram behavior, imply a good compatibility between the components. The result is confirmed by the infrared measurements on solid films. The lack of anisotropic phase formation in chitin–diluent binary solutions and the anomalous trend of v′CH–CE line on the phase diagram are both interpreted on the basis of aggregation phenomena.

Erratum: Phase diagram and critical behavior of the ferromagnetic Heisenberg fluid from density-functional theory

Erratum: Phase diagram and critical behavior of the ferromagnetic Heisenberg fluid from density-functional theory

Effects of Mixtures of Alkanes on the Bending Rigidity Constant K of AOT Monolayers at the Planar Oil-Water Interface

We have studied the phase diagrams of brine/oil/AOT mixtures in which the oils are mixtures of octane and tetradecane and the amount of AOT is small. In addition, the properties of the AOT monolayer at the brine/oil interface as a function of the volume fraction φ of tetradecane in the oil have been measured. The values of the interfacial tension and the phase diagram behaviour show that the Equivalent Alkane Carbon Number concept is valid in these systems, where a small change of φ induces a large change in the phase diagram. In addition we show that this concept applies to the bending elastic modulus K and probably to the saddle splay modulus K.