Home About us Contact
|
Home About us Contact | ||
|
|
||
Ternary Phase Diagram (ternary + phase_diagram)
Selected AbstractsNovel gel-entrapped base catalysts for the Claisen,Schmidt reactionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2004Sachin S Chaphekar Abstract Novel gel-entrapped base catalysts (GEBCs) were prepared by entrapping aqueous solutions of bases in a gel matrix of agar agar. The bases used were NaOH, KOH, morpholine and piperidine. Ternary phase diagrams were constructed for the water,base,agar agar system to identify the various phases and especially the solid phase, useful as a solid base catalyst. The 10% NaOH solid gel was used to effect the Claisen,Schmidt reaction between benzaldehydes and acetophenones in ethanol under heterogeneous conditions to obtain 70,100% yield of the products. The solid GEBCs obtained using other bases were also used for the same reaction; however, the yields were lower. The catalyst needed no activation prior to use and could be recycled. Copyright © 2004 Society of Chemical Industry [source] Solubilization of methanol and ethanol in palm oil stabilized by medium- and long-chain alkanolsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2002K Dzulkefly Abstract Solubilization of methanol and ethanol in crude palm oil, refined, bleached and deodorized palm oil (RBD PO) and RBD palm olein (POL) was studied using medium- and long-chain alkanols (C4,C12). Ternary phase diagrams were constructed to determine the solubilization (isotropic) region. The results showed that methanol and ethanol are solubilized to a greater extent in an unsaturated palm olein than the saturated CPO and RBD PO in the presence of long-chain alkanols. The minima of the solubilization curves for dodecanol, decanol and octanol were 27%, 30% and 33% of alkanol respectively in the methanol system, whereas in the ethanol system, the minima for the same alkanols were found at 22%, 24% and 27%. The longer chain-length alkanol (dodecanol) requires a lesser amount (21% and 32%) to achieve miscibility compared with 53% and 57% for butanol in mixtures containing 70:30 and 50:50 wt ratios respectively. The kinematic viscosity of the isotropic solutions increases with the chain-length and percentage of alkanols. Solubilization using a POL/methanol/butanol system significantly reduced the kinematic viscosity of POL from 72.7,mm2,s,1 to the value allowable for No 2 diesel fuel (1.9,4.1,mm2,s,1) or about a 96% reduction from the initial kinematic viscosity of POL. © 2002 Society of Chemical Industry [source] Thermal behaviour of cubic phases rich in 1-monooleoyl- rac -glycerol in the ternary systemFEBS JOURNAL, Issue 1 2003- d -glucoside/water, 1-monooleoyl- rac -glycerol/n -octyl- Using synchrotron X-ray diffraction the thermal behaviour was studied of the cubic phases in the 1-monooleoyl- rac -glycerol (MO)/n -octyl-,- d -glucopyranoside (OG)/2H2O system with 58 or 45 wt % MO concentration and varying OG/2H2O contents. These MO contents correspond to a Pn3m cubic single-phase or a Pn3m cubic phase in excess water on the binary MO/water axis of the ternary phase diagram. The cubic liquid crystalline phases are stable with small fractions of OG, while higher OG concentrations trigger a cubic-to-lamellar phase transition. Moreover, with increasing OG concentration the initial Pn3m structure is completely converted to an Ia3d structure prior to the L, phase being formed. Upon heating this effect is reversed, resulting in an Ia3d -to- Pn3m phase transition. For some samples additional peaks were observed in the diffractograms upon heating, resulting from the metastability notoriously shown by bicontinuous cubic phases. This judgement is supported by the fact that upon cooling these peaks were absent. Remarkably, both the Ia3d and the Pn3m cubic structures could be in equilibrium with excess water in this ternary system. A comparison is made with previous results on n -dodecyl-,- d -maltoside (DM), showing that cubic phases with OG have higher thermal and compositional stability than with DM. [source] Reactivity in LaGaO3/Ni and CeO2/Ni SystemsFUEL CELLS, Issue 2 2006N. Solak Abstract The reactivity in CeO2/Ni and LaGaO3/Ni systems, which are constituents of intermediate temperature solid oxide fuel cell (IT-SOFC) anodes, has been investigated both computationally and experimentally. The CALPHAD-method (CALculating of PHAse Diagrams), employing BINGSS and THERMOCALC software, was used to obtain a self-consistent set of Gibbs energy functions describing the systems. Interactions in the LaGaO3/Ni system were predicted using a thermodynamic database developed for the La-Ga-Ni-O system. Similarly, to analyze the CeO2/Ni system, the Ce-Ni-O ternary phase diagram was calculated using known thermodynamic data for binary Ce-O, Ni-O, and Ce-Ni systems. The experimental work was designed based on the calculated phase diagrams. While the La-Ga-Ni-O system experiments were conducted in air, the Ce-Ni-O system was also investigated in a reducing atmosphere. The calculated Ce-Ni-O diagram is in good agreement with the experimental results. It has been found that NiO does not react with CeO2. Extended solid solutions of La(Ga,Ni)O3, La2(Ni,Ga)O4, and La4(Ni,Ga)3O10 were found in the La-Ga-Ni-O system. Additionally, the compound LaNiGa11O19, with magnetoplumbite-type structure, has been found, which has not been reported in the literature so far. It is concluded that La2NiO4 is not chemically compatible, as a cathode material, with the LSGM electrolyte. [source] Polymerization of methyl methacrylate in the presence of a nonpolar hydrocarbon solvent.JOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Abstract This article presents the ternary phase diagram for methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), and n -hexane system at 70°C. It was constructed by both theoretical calculations and online laser light scattering (LLS) technique. In situ polymerization of MMA in a nonpolar nonsolvent carried out in a LLS cell provides a new means for the accurate detection of the cloud points of highly viscous polymer mixtures, with polymer weight fractions over 0.6. The ternary phase diagram measured in this study can be used to design the reaction conditions for the precipitation and/or dispersion polymerization in a nonpolar nonsolvent medium where polymerization kinetics as well as polymer particle morphologies are strongly affected by thermodynamic phase separation phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] IPM/DOSS/water microemulsions as reactors for silver sulfadiazine nanocrystal synthesisJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2005Jerry Nesamony Abstract The first goal of this work was the preparation of a water-in-oil microemulsion from components generally regarded as safe for use in humans. Stable formulations without need of a co-surfactant were prepared from isopropyl myristate (IPM), dioctyl sodium sulfosuccinate (DOSS), and water. A ternary phase diagram was prepared for the IPM/DOSS/water system. The IPM/DOSS/water microemulsions were characterized by conductivity and dynamic laser light scattering (DLS). The results obtained from conductivity experiments indicate conductivity values of less than 1 ,S/cm and were consistent with the formation of w/o microemulsions. The DLS results showed that the emulsified water droplets had an average diameter range of 9.2 to 19.7 nm, depending on composition. Modulation of the droplet size is possible by varying the water to DOSS molar ratio and DOSS to IPM ratio. The second goal of this work was the preparation of silver sulfadiazine (AgSD) nanoparticles. It was hypothesized that two separate microemulsions containing dispersed aqueous droplets of either sodium sulfadiazine or silver nitrate would react when mixed. The DLS results are consistent with the successful formation of submicron AgSD crystals. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1310,1320, 2005 [source] Morphology and Phase Stability of Nitrogen,Partially Stabilized Zirconia (N-PSZ)JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2001Tai-Joo Chung The surface layer of yttria-doped tetragonal zirconia materials that have been heat-treated with zirconium nitride was observed to consist of a nitrogen-rich cubic matrix with nitrogen-poor tetragonal precipitates. The precipitates had a thin, oblate-lens shape, similar to those observed in magnesia,partially stabilized zirconia. Because of the fast diffusion of N4, ions, the precipitates grew rather large, up to ,5 ,m in length, and remained stabilized in the tetragonal form at room temperature. Because the nitrided layer grew in the two-phase field, the size and distribution of the precipitates each was very irregular. The nitrogen content was observed to determine the proportion of cubic and tetragonal phases in the same way as in conventional cation-stabilized partially stabilized zirconia. A ternary phase diagram for the zirconium(yttrium),nitrogen,oxygen system was suggested to explain the concentration gradient in the cubic matrix and the phase distribution of the nitrided layer. [source] Novel aromatic polyimide fiber with biphenyl side-groups: Dope synthesis and filament internal morphology controlPOLYMER ENGINEERING & SCIENCE, Issue 2 2006Xiangyang Liu A new organic-soluble aromatic polyimide with biphenyl side-groups has been synthesized from 4,4,-oxydiphthalic anhydride and 3,5-diamino-benzonic-4,-biphenyl ester (DABBE) via a one-step polymerization in m -cresol. A higher molecular weight polyimide has been obtained by the addition of chlorotrimethylsilane (TMSCl) in the solution of DABBE to form, in situ, silylated diamine. The optimum mole amount of TMSCl relative to the number of amino groups is 100%. This polyimide is soluble in m -cresol, allowing fibers to be spun from isotropic solution using a dry-jet wet spinning method. Based on a ternary phase diagram of m -cresol, ethanol, and water, controlling of the internal morphology of as-spun fibers has been achieved by varying the rate of polyimide coagulation through adjustment of nonsolvent/solvent miscibility in the coagulation bath. Scanning electron microscopic pictures show that filament internal morphologies ranged from porous-like to fully solid. The solid as-spun fibers can be drawn at high temperatures (>330°C) under tension to high drawn ratios (up to 6×), which produces a remarkable increase in tensile strength to about 1.0 GPa and an initial modulus higher than 60 GPa. POLYM. ENG. SCI. 46:123,128, 2006. © 2005 Society of Plastics Engineers [source] Influence of the relative humidity on film formation by vapor induced phase separationPOLYMER ENGINEERING & SCIENCE, Issue 4 2003H. Caquineau The formation of polymer films produced by the phase separation process occurring when a cast poly(etherimide)/N-Methyl-2-Pyrrolidone solution was exposed to humid air was studied. It was found that above a relative humidity value of 27%, the films presented a cell-like structure. The size of the cells was shown to decrease when the relative humidity increased. This effect was more pronounced at the film/substrate interface than near the surface. A cell-size gradient from one face of the film to the other was also clearly observed. A phenomenological model has been proposed to explain the morphology obtained by a phase separation induced by the water vapor in the studied system, takin into account thermodynamics and kinetics considerations. In this model, the cell-like structure setting up is shown to result from a nucleation and growth process accompanied by a coalescence coarsening. It was illustrated by a composition path on the ternary phase diagram. It was shown how the relative humidity influenced the film composition leading to the preferential nucleation compared to the growth and coalescence of the cells. Finally, it was found that the cell-size anisotropy resulted in the solvent and non-solvent mass transfers in the film, bringing to the fore the determining role of kinetics. [source] Theoretical Modeling of the Phase Separation Dynamics in Blends of Reactive MonomersMACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2005Gregory R. Yandek Abstract Summary: Experimental observations of the dynamics of phase behavior for blends of reactive constituents, i.e. diglycidyl ether of bisphenol A (DGEBA), curing agent methylene dianiline (MDA), and a reactive liquid rubber (R45EPI), have been theoretically modeled by coupling system thermodynamics governed by a summation of the free energies of mixing and network elasticity with reaction kinetics and diffusion equations. Snap-shots of the temporal evolution of ternary phase diagrams have been established based on the self-condensation reactions of DGEBA-MDA and R45EPI as well as a cross-reaction between the two constituents forming a copolymer. Numerical solution of the proposed mean-field model provides good qualitative agreement with experimental results, namely, the observance of phase separation followed by a phase dissolution and subsequent secondary segregation in a 50/25.4/50 DGEBA/MDA/R45EPI mixture, as well as a single gradual phase separation in a 70/25.4/30 mixture. The phase separation dynamics are explained by a competition between the growth in molecular weights of the reactive species rendering the systems towards instability, and the formation of copolymer acting to compatibilize the mixtures. Theoretical phase diagram for a DGEBA/MDA/R45EPI system. [source] | |||||||||||||