Solution temperature

Colinet C and Pasturel A 1994 High temperature solution calorimetry Solution Calorimetry, Experimental Thermodynamics vol IV, ed K N Marsh and PAG O Hare (Oxford Blackwell)... 

Sun Y-P, Wang P and Hamilton N B 1993 Fluorescence spectra and quantum yields of Buckminsterfullerene (Cgg) in room-temperature solutions. No excitation wavelength dependence J. Am. Chem. Soc. 115 6378-81... 

D. Elwell and H. J. Scheel, Crystal Growth from High Temperature Solution Academic Press, London, 1975. 

Eastman Chemical has utilized a unique, high temperature solution process for propylene polymerization. Polymerization temperatures are maintained above 150°C to prevent precipitation of the isotactic polypropylene product in the hydrocarbon solvent. At these temperatures, the high rate of polymerization decreases rapidly, requiring low residence times (127). Stereoregularity is also adversely affected by high temperatures. Consequentiy, the... 

For most LLE applications, the effect of pressure on can be ignored, and thus equation 228 constitutes a set of N equations relating equiUbrium compositions to each other and to temperature. Solution of these equations for a particular temperature requires a single expression for the composition dependence of suitable for both Hquid phases. Not all expressions for G suffice, even in principle, because some cannot represent Hquid—Hquid phase sphtting. 

Stability. Ascorbic acid, a white crystalline compound, is very soluble ia water and has a sharp, acidic taste. In solution, the vitamin oxidizes on exposure to air, light, and elevated temperatures. Solutions of ascorbic acid turn yellowish, followed by development of a tan color. Ascorbic acid is stable to air when dry but gradually darkens on exposure to light. 

Aqueous solutions of vitamin > 2 at pH 4.0 to 7.0 show no decomposition during extended storage at 25°C. For optimum stability at elevated temperatures, solutions should be adjusted to pH 4.0 to 4.5. Aqueous solutions in this pH range maybe autoclaved for 20 min at 120°C without significant decomp o sition. 

The influence of temperature, solution s pH and other parameters in formation of ionic associate is investigated. As a result, optimal conditions of determination are established pH 4,0 volume of acetate buffer - 0,5 ml volume of 0,1% aqueous solution of CV - 0,3 ml extraction time - 3 minutes. The ratio of aqueous and organic phases is 1 1. Photometric measurement of toluene layer is carried out at = 606,0 nm. The accuracy of procedures checked by the method of additives. 

Alhedai et al also examined the exclusion properties of a reversed phase material The stationary phase chosen was a Cg hydrocarbon bonded to the silica, and the mobile phase chosen was 2-octane. As the solutes, solvent and stationary phase were all dispersive (hydrophobic in character) and both the stationary phase and the mobile phase contained Cg interacting moieties, the solute would experience the same interactions in both phases. Thus, any differential retention would be solely due to exclusion and not due to molecular interactions. This could be confirmed by carrying out the experiments at two different temperatures. If any interactive mechanism was present that caused retention, then different retention volumes would be obtained for the same solute at different temperatures. Solutes ranging from n-hexane to n hexatriacontane were chromatographed at 30°C and 50°C respectively. The results obtained are shown in Figure 8. 

A more recent process, the P2 etch [60], which uses ferric sulfate as an oxidizer in place of sodium dichromate avoids the use of toxic chromates, but still provides a similar oxide surface morphology (Fig. 15) allowing a mechanically interlocked interface and strong bonding [9]. The P2 treatment has wide process parameter windows over a broad range of time-temperature-solution concentration conditions and mechanical testing confirms that P2-prepared surfaces are, at a minimum, equivalent to FPL-prepared specimens and only slightly inferior to PAA-prepared surfaces [61]. 

Differences in composition require different temperatures for the high-temperature solution treatment, as well as variations both in time and temperature of aging. Heat-treatable plate and sheet alloys are not widely used for process plant construction because heat treatment has to be applied after welding to restore the mechanical properties. 

Metal area in contact with the higher temperature solution... 

From X-ray diffraction experiments28 it is known that in the crystalline phase the erythrodiisotactic poly(l,2-dimethyltetramethylene) has a (g+aaa g aaa)n structure as shown in Fig. 13. The bold printed letters in the denotation give the conformation of the CH—CH bond. In agreement with this structure and low temperature solution state spectra of 2,3-dimethylbutane, 3,4-dimethylhexane, and 4,5-dimethyloctane 29 30) in which the CHCH bond rotation is frozen the crystalline signals can be assigned conclusively. Like for the crystalline state of poly(l,2-... 

Solution reactions between diacid chlorides and diols or diphenols are carried out in THF or CH2C12 at —10 to 30°C in die presence of tertiary amines such as triethylamine or pyridine, which play a role of both reaction catalyst and HC1 acceptor (Scheme 2.26). This synthetic mediod is also termed acceptor-catalytic polyesterification.295-297 High-temperature solution reactions have also been reported for a number of less soluble, generally semicrystalline, aromatic polyesters.6 They yield high-molar-mass polyesters exhibiting good mechanical properties and thermal stability. 

Morgan and Kwolek33 have described a large number of PA derived from phenylenediamines and aliphatic diacids by low-temperature solution polymerization starting with aliphatic diacid chlorides. 

High-temperature solution reactions, 75 HIPS. See High-impact polystyrene (HIPS)... 

It was possible (16) to obtain gels from the crude pectins in presence of sucrose and at acidic pH. The phase diagrams of the pectin systems (Figure 4) have been first established. The gel state was simply observed by visual inspection of the products obtained after heating (100°C, 30 min) and cooling (to room temperature) solutions containing different quantities of pectins and sucrose at pH3 (citric acid). 

Mixing of high temperature hydrothermal solution with high salinity and low temperature solution with low salinity of meteoric water origin seems the most likely mechanism for the base-metal vein-type deposition. 

Michard, A. and Albarede, F., Michard, G., Minsten, J.F. and Charlou, J.L. (1983) Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (I3°N). Nature (London), 303, 795-797. 

Barite and sphalerite tend to precipitate at lower temperature from the hydrothermal solution mixed with a large amount of cold seawater (but mixing ratio (seawater/hydrothermal solution) may be less than 0.2). These minerals precipitate on the seafloor and/or at very shallow subsurface environment. However, chalcopyrite tends to precipitate from high temperature solutions in ore bodies and/or at the sub-seafloor sediments. Usually shale which is relatively impermeable overlies the Besshi-type ore bodies. This suggests that hydrothermal solution could not issue from the seafloor and... 

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