ISSN:0021-8871    

DOI:10.1002/jctb.5010130908

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe data existing for the thermal decomposition equations of ammonium perchlorate (AP) have been reviewed after reducing them to a common basis (100 moles of AP). They have been evaluated from two points of view: (a) stoicheiometric balance of the elements present, and (b) establishment of thermodynamic equilibrium of the final gaseous products. From a knowledge of the distribution of the nitrogen between N2, N2O and NO, and of the chlorine between Cl2and HCl (the latter derived from the equilibrium constant for the Deacon process), the corresponding equilibrium temperatures (Teq) and the flame temperatures (Tt) have been calculated. These temperatures agree in a number of cases with the measured heating temperatures and temperatures of the gas flame.Extrapolation of the equilibrium gas compositions calculated for different pressures indicates that the gas composition at equilibrium lies between two asymptotic extremes which are:For zero pressure or for relatively lowTeq\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 2 NH}_{\rm 4} {\rm ClO}_4 = 4{\rm H}_2 {\rm O} + {\rm O}_2 + {\rm Cl}_2 + 2{\rm NO}, $$\end{document}and for high pressures or for relatively highTeq,\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm 4 NH}_{\rm 4} {\rm ClO}_4 = 6{\rm H}_2 {\rm O} + 5{\rm O}_2 + 4{\rm HCl} + 2{\rm N}\_2. $$\end{document}Below 300° some ClO2forms, and N2O instead of NO. NO when, formed reacts giving nitrosy1 compounds.At all temperatures there may occur a ‘freezing’ of non‐equilibrium compos

ISSN:0021-8871    

DOI:10.1002/jctb.5010130901

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractIn order that it may be possible to differentiate between adsorbed water and water chemically bound in hydrated Portland cement, a study was conducted of the dimensional‐change sorption characteristics at low relative vapour pressures.By use of compacts of bottle‐hydrated cement fabricated at loads between 5000 and 65, 000 lb., equilibrium as well as dynamic values were obtained for dimensional change and moisture change relationships below 20% R.H. The apparatus enabled experiments to be performed in high vacuum.For the first rewetting and second drying it was found that for equilibrium points from 7.2 to 17‐6 and 17‐7 to 7‐9% R.H. the plots of ( Δl/l) vs (ΔW/W) were both linear. After degassing the specimens beyond 7.9% R.H., the dynamic points continued along the straight line traced out by the equilibrium points in the plot mentioned and a sharp transition point was obtained. The vapour pressure in the region of this transition point, referred to as datum point, was less than 10 μ. Further degassing produced another linear region.It was concluded with supporting evidence from work on other porous materials that the datum point where the transition between the linear portions of the curve occurs, will yield a good estimate of the true value for adsorbed water and will thus approximate to the point for zero adsorbed water; it will also separate the processes of desorption and dehydration. This establishes therefore a method for determining the adsorbed water in hydrated cement.The results obtained from the compacts of bottle‐hydrated cement indicate that by this method the surface area, as calculated from the B.E.T. theory, will be considerably lower than that obtained from the high value for the evaporable water (determined by the method of C

ISSN:0021-8871    

DOI:10.1002/jctb.5010130902

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractA method has been developed, based on that of Mann&Marrinan,4for the accurate determination of the accessibility of regenerated cellulose films of thickness 20–25 μ such as are used commercially for packaging. The films are treated with heavy‐water vapour and the exchange reaction with accessible hydroxyl groups is followed spectroscopically.By application of this method it has been shown that the accessibility of these films is decreased by treatment with water or dilute alkali followed by drying. On prolonged drying of deuterated cellulose films fresh accessible hydroxyl groups are formed, which it is suggested is due to proton‐deuteron interchange in the fringes of crystallites.Introduction of hydroxyethyl side groups into the cellulose chain molecules causes the accessibility to increase. Over the range studied (78.6—86.9% accessible) the accessibility is proportional to the volume swelling in water, an increase of 1% in the accessibility corresponding to a 16% increase in the volume swelling. It is deduced from this large effect that the increase in accessibility is accompanied by disappearance of small crystallites (which act as junction points in the molecular chain network) as well as a reduction in the size of larger crys

ISSN:0021-8871    

DOI:10.1002/jctb.5010130903

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractOne of the simplest methods of surface area measurement is extended to include the size distribution of pores in the 10–300 Å radius range. This technique involves passing a mixture of 10% nitrogen in helium over the sample cooled in liquid nitrogen at a fixed rate and at various pressures to 150 p.s.i.a. causing the nitrogen partial pressure to reach its liquefaction point. Consequently the nitrogen relative pressure in the sample tube is varied in the range of about 0.16 to 1. Nitrogen adsorbed or desorbed by increasing or decreasing pressure in the sample tube is measured continuously at near atmospheric pressure by thermal conductivity. The thermal conductivity cell always ‘sees’ a reference of 10% nitrogen in helium. Hence the measured composition differences fall within a comparatively narrow range where the thermal conductivity cell output is linear. Isotherms developed by this method are compared with isotherms obtained by the pressure‐volume method of adsorption measurement and show good agreement. Simplicity of design and operation of the instrument provides fast and reliable

ISSN:0021-8871    

DOI:10.1002/jctb.5010130904

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractThe vapour pressure, in the range −50° to the normal boiling point (50‐2°), and the vapour density, in the temperature range 0–60° and at pressures up to the saturation vapour pressure, of halothane have been determined; the values are presented as equations. The vapour pressures and second virial coefficients are tabulated at temperature intervals of 10°, and gas densities at the same temperature intervals and pressure intervals of 1

ISSN:0021-8871    

DOI:10.1002/jctb.5010130905

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractA study has been made of the thermal hydrocracking of methylcyclohexane in a flow reactor with particular reference to the formation of aromatic hydrocarbons. Although much of the methylcyclohexane is converted into gaseous hydrocarbons, especially methane, the amounts of benzene and toluene formed are interesting in that benzene displaces toluene as the major aromatic product, as the reaction temperature is increased. Both 4‐methylcyclohexene and cyclohexene are found in appreciable quantities and their yields pass through maxima as the conversion of methylcyclohexane increases, while the respective yields of the corresponding aromatics continue to rise. The aromatics, therefore, are formed mainly as a result of dehydrogenation and demethylation of the naphthene. A possible reaction mechanism is discusse

ISSN:0021-8871    

DOI:10.1002/jctb.5010130906

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY

摘要:

AbstractA colorimetric method of estimating the degree of sealing of anodic oxide films on aluminium has been developed. Sealing in dichromate or chromate solutions may be followed directly by dissolving the anodic film in sodium hydroxide solution, acidifying with sulphuric acid and determining the chromium in the resulting solution with diphenylcarbazide. For other sealing electrolytes, the partially sealed film is treated for a standard time in potassium dichromate solution (‘post‐sealing’) before dissolution and estimation.In dichromate sealing, chromium uptake continues for long periods at all temperatures and any simultaneous hydration does not rapidly produce pore plugging. The post‐sealing estimation technique is shown to be sensitive to anodising and sealing variables for water sealing. The results support a mechanism of sealing involving some pore closure from the sides with more extensive plugging near the outer surface. The test also appears suitable for assessing films sealed in salt solutions such as nickel acetate and is apparently sensitive to the effects of ageing of the oxide film. It is concluded that it is the most appropriate of the absorptiometric and colorimetric tests because it may be developed on a quantitativ

ISSN:0021-8871    

DOI:10.1002/jctb.5010130907

出版商:John Wiley&Sons, Ltd    

年代:1963

数据来源: WILEY