摘要:

AbstractThe contribution of carboxyl groups to the water sorbing properties of keratin has been investigated over the complete water vapour pressure range. A series of partially methylated wools were studied: below 80% R.H. there is a reduction in water content linear with the reduction in the number of carboxyl groups, but at humidities above 80% R.H. extra water is absorbed because of disruption of the structural network under the acid conditions of treatment.Extrapolation of the plot of equilibrium water content vs. free carboxyl group content of partially methylated wool samples at a particular humidity. made at several humidity values, enables an isotherm to be deduced for wool containing no COO groups. The reduction of water content for wool of zero carboxyl group content, as a function of relative humidity, represents the isotherm attributable to the free carboxyl groups in keratin; this is a simple Langmuir isotherm at low humidities. The reduction of water content is proportionately greater at lower humidities—at 5% R.H., 36% of the total water and at 65% R.H., 22% of the total water absorbed by keratin is associated with free carboxyl groups. The number of water molecules associated with each carboxyl group is greater than previous literature v

ISSN:0021-8871    

DOI:10.1002/jctb.5010180101

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe equilibrium Ca(OH)2⇌ CaO+H2O has been studied at pressures of steam up to 50 bars and at temperatures of up to 800° C. The dissociation pressures determined are in agreement with the data derived by some previous workers at pressures of less than one bar but they conflict with data published for higher pressures. The results can be expressed by the relationover the range 530–8

ISSN:0021-8871    

DOI:10.1002/jctb.5010180102

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractExperiments by isothermal calorimetry, indicate that the hydration of 3CaO·SiO2(C3S) is influenced very little by gibbsite; it is influenced by bayerite to a somewhat larger extent.In the presence of amorphous Al(OH)3the reaction of C3S with water shows a very complicated course and gives four heat peaks. If CaO is added in addition to this Al(OH)3, the third and the fourth heat peaks are more pronounced. From qualitative d.t.a., infra‐red, electron‐microscope andX‐ray investigations, as well as from quantitativeX‐ray analysis, a reaction mechanism is proposed.The quantity of C3S reacted, determined by means of quantitativeX‐ray analysis, is greater during the reaction of 2·00 g C3S with 0·40 g amorphous Al(OH)3, 0·08 g CaO and 2·00 ml water, than during the reaction of 2·00 g C3S wit

ISSN:0021-8871    

DOI:10.1002/jctb.5010180103

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractAn improved method for preparing methacrylate esters by transesterification makes use of molecular sieves to remove the alcohol of lower boiling point as it is formed. The procedure avoids the use of a large excess of reactant methacrylate or other entraining agent and the protracted collection of methanol or ethanol azeotropes. The reaction temperature and the reaction rate are thereby increased.

ISSN:0021-8871    

DOI:10.1002/jctb.5010180104

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe electrodialysis of monocarboxylic acids and their potassium salts in the series formic acid to valeric acid has been investigated. A laboratory‐scale continuous‐flow unit was operated over the current density range 0·4 to 6·0 mA/cm2with total feed concentrations of 13·1 and 26·2 meq/1. Initial experiments were conducted with chloride and sulphate, for which the total transport and selectivities are established. At pH values set to assure 95% dissociation of the monocarboxylic acids, the transport (in the presence of chloride) of formate, acetate and propionate was about 20%, but that of butyrate and valerate was less. Acid salt selectivities (transport compared with chloride) ranged from 0·5 for formate through propionate to 0·3 for butyrate and valerate.For butyrate, the percentage transport increased approximately linearly with current density and was a random function of equivalent fraction of butyrate in the feed. Increases in total concentration produced no increases in transport. Butyrate selectivities were somewhat independent of current density and of equivalent fraction.Throughout the study, there was only limited evidence of fouling of the membrane by the organic acids and their salts, although valerate did produce temporar

ISSN:0021-8871    

DOI:10.1002/jctb.5010180105

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractA nomogram scaled in logarithmic units, and a chart are provided for estimation of the effective thermal conductivities of two‐phase media. The former is useful for precise prediction, and the latter as an approximate guide to probable limiting values. The basis is a logarithmic equation proposed by Woodside&Mesmer, biased empirically following the study of about 150 experimental results for two‐phase media. The practical uses are numerous, e.g. estimations of the conductivities of filled plastics, filled rubbers; metal, ceramic and other powders in fluids or gases; ocean sediment; waterlogged and frozen soil, and other materi

ISSN:0021-8871    

DOI:10.1002/jctb.5010180106

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractAlgal particles fromLaminaria hyperboreastipes andLaminaria digitatawere exposed to a stream of hydrochloric acid in a continuous flow apparatus, and the ion‐exchange process Ca/H was investigated. The exchange rate was shown to depend upon such factors as acid concentration, particle size, agitation and time of acid residence.The results show that the exchange rate followed a first‐order reaction in the conditions used, and the exchange velocity was proportional to the logarithm of the hydrochloric acid concentration. Evidence is given which indicates that the exchange process is governed by a film‐diffusion mechanism, and the diffusion of calcium across a thin liquid film enveloping the particle is suggested to be the rate‐determining step. Exchange experiments with particles fromAscophyllum nodosumshow that another rate mechanism has to be considered in th

ISSN:0021-8871    

DOI:10.1002/jctb.5010180107

出版商:John Wiley&Sons, Ltd    

年代:1968

数据来源: WILEY