ISSN:0005-9021    

DOI:10.1002/bbpc.19850891202

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891203

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe applicability of the recently proposed CDM theory of counterion spin relaxation in polyelectrolyte solutions [Halle, Wennerström&Piculell, J. Phys. Chem.88, 2482 (1984)] is extended to low degrees of polymerization. Polyion end effects on the counterion distribution and dynamics are described in the spheroidal‐cell model of Bratko&Dolar [J. Chem. Phys.80, 5782 (1984)]. The extended theory is applied to23Na spin relaxation data from saltfree solutions of sodium poly (styrenesulfonate) and it is found that the available data can be explained by a model in which polyions of length 20–100nm reorient as fully extended, rigid bo

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891204

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractHighly dispersed platinized‐carbon hydrogen anodes are developed for utilization in alkali and acidic media power sources viz., hydrogen/air fuel cells and nickel/hydrogen batteries, by tailor making both the macro as well as micro structures of these electrodes. The optimized hydrogen anodes can withstand load currents upto 350, 800 and 500 mA/cm2for extended periods in 6N KOH, 5N H2SO4and 2ON H3PO4electrolytes respectively. Characterization techniques such as photoelectron Spectroscopy, X‐ray absorption Spectroscopy, chemisorption, X‐ray diffraction, electron microscopy, electron spin resonance etc., are found to be useful in developing such electrodes. The study clearly demonstrates the significance of physico‐chemical characterization techniques in developing fuel cell ele

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891205

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractA high pressure autoclave with sapphire windows, auxiliary equipment and means and precautions needed for experiments with high pressure, high temperature oxygen are described. With water‐oxygen mixtures of different mole fractions,x, determinations were made of liquid‐gas phase equilibria conditions along “isopleths” between 500 and 660 K to 250 MPa. Molar volumes of the mixtures were measured at the three‐dimensional (PTx) phase equilibria surface and in the supercritical region at 673 K. The critical curve, an envelope for the isopleths, begins at the critical point of water (647 K), has a temperature minimum (640 K) at about 75 MPa and proceeds to 250 MPa at 663 K. Phase equilibria and critical curve data are given. The H2OO2critical PT curve is very close to the critical curve recently (10) determined for H2ON2. Values for the Henry‐constant from 300 K to 647 K for mixtures dilute in oxygen are presented. The Henry constant at room temperature has only about half the value of the Henry constant for nitrogen in water. At the critical temperature of water (647 K), however, both constants do not differ by more than the uncertainty of the determinations. The excess volume was calculated at 673 K from 30 to 250 MPa. All values are positive. The excess Gibbs energy and activity coefficients are presented. One isopleth for H2O‐air withx(H2O) = 0.80 was measured and molar volume values for this composition at 673 K between 33 and

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891206

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe thermodynamic and dielectric behaviours of liquid and solid cycloheptanol have been investigated using differential thermal analysis and capacitance measurements up to 10 MHz. The phase behaviour has been studied between 80 and 340 K and pressures up to 300 MPa. The well‐known phase transformations at 1 atm have also been observed atelevatedpressures that enables to calculate the associated volume changes. The static and complex permittivities have been determined in the temperature range 240–310 K and pressures up to 300 MPa. Activation parameters derived from the dielectric relaxation occurring in the two plastic phases are similar to previously reported data for cyclopentanol and cyclohexa

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891207

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe dielectric constant ϵ and the resistanceRhave been measured as a function of frequency in the region 1 kHz to 1 MHz. The measurements have been performed on two critical binary liquid mixtures cyclohexane + methanol and carbondisulphide + acetonitrile in the one phase region. The measurements are carried out using a double ratio transformer bridge, in a bath with millidegree temperature control. At low frequencies ϵ andRincrease withT → Tc+. Above 100 kHz the resistance reaches a maximum and begins to decrease asT → Tc+. The observed behaviour is explained qualitatively on the basis of interfacial polarization mechanisms (IPM) using the ideas of the droplet model theory of binary Liquid mixtures. The analysis of the low frequency data using the functional formRor ϵ ˜tθshows a value of θ near 0.9. The high frequency data have been analysed with a new functional form, but the quantitative discussions of the IPM are hampered by the lack of information of its depende

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891208

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractA new apparatus for the measurement of low temperature vapour‐liquid equilibrium data is described. The vapour recirculation method is used for the mixture to reach equilibrium in a cell equipped with glass windows. Samples of both phases can be withdrawn and analysed with high precision by optical absorption in the UV‐region. Measurements were made for the system nitrogen‐nitric oxide along three isotherms between 113 and 120 K. The area test showed thermodynamic consistency of the data. The deviations of the mixtures from ideality are large, caused by dimerization of the NO in the liquid. The maximum excess Gibbs energy is about 500

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891209

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractThe vaporization of tin(II), lead(II), and scandium(III) iodide was studied by high‐temperature mass spectrometry with a Knudsen cell. The monomer and dimer molecules (SnI2)i(g), (PbI2)i(g), and (ScI3)i(g) (i= 1,2) were identified. Enthalpies and entropies of dimerization, equilibrium partial pressures as well as enthalpies and entropies of sublimation were evaluated for the gaseous molecules. Their molecular parameters and the thermodynamic functions computed from them are given. Appearance potentials were determined for the various ions observed upon vaporizing the three different metal iodide

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891210

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY

摘要:

AbstractIt is observed that the rates of hydride formation or decomposition affect the subsequent plateau pressures of the intermetallic‐H systems which have been examined here, LaNi5‐H and LaCo5‐H and ZrMn2‐H. When small aliquots of hydrogen are added or removed in the two‐phase coexistence region, the plateau pressures for hydride formation and decomposition are higher and lower, respectively, than when large aliquots are employed. Thus the use of large aliquots of hydrogen reduces hysteresis in these systems. This effect illustrates the metastability of these plateau pressures. It introduces complicating features into some technological applications of metal hydrides, e.g., heat pump applications where constant and predictable plateau pressures are

ISSN:0005-9021    

DOI:10.1002/bbpc.19850891211

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1985

数据来源: WILEY