摘要:

AbstractCrude tars from six sources have been used in a full‐scale experiment to determine the physical and chemical changes that occur in road tar used in wearing‐course macadam. Samples taken from the road at intervals up to two years have been studied in the laboratory. It has been shown that when tars weather, there is an increase in viscosity due to two main processes, evaporation and oxidation. In the oxidation mechanism, ‘C2resin’, soluble in pyridine but not in benzene, is formed from material of lower molecular weight; it increases both the viscosity and the temperature coefficient of viscosity, so that in cold weather very high viscosities are attained. In the case of lower‐gravity tars, evaporation and oxidation account for similar amounts of hardening, but with coke‐oven tars, evaporation p

ISSN:0021-8871    

DOI:10.1002/jctb.5010191001

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe techniques employed on samples from the Hercies Road Experiment (Part I) were used to determine if chemical changes occurring during the weathering of road tar could be detected and to obtain information on the nature of these changes.The main changes were attributable to evaporation and condensation, and chemical changes due to the action of air and light play a relatively minor part.

ISSN:0021-8871    

DOI:10.1002/jctb.5010191002

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe effect of thermal treatment on talc‐magnesite in the presence of air in the temperature range 500–1000°, was studied by nitrogen adsorption and followed by t.g.a., d.t.a. andX‐ray analysis. From the nitrogen adsorption isotherms, the specific surface area as well as pore‐size distribution was estimated. The surface area increased with temperature, to reach a maximum at 600°. On immersion of the calcination products in water, magnesium hydroxide was formed. Decomposition of the hydration products in air at 450° resulted in solids of relatively higher surface areas, whereas decompositionin vacuoat the same temperature produced more active solids. Surface area of the products producedin vacuodecreased only slightly with the primary decomposition temperature, and they are characterised by sharp pore‐size distribution curves. Surface areas of the products produced in air were dependent on the primary calcination temperature, although they showed pore‐size spectra similar to those of the other products. Products obtained by direct decomposition in air showed wider pore spectra that shifted towards higher pore radii with rise

ISSN:0021-8871    

DOI:10.1002/jctb.5010191003

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe conditions under which platinum is lost from platinised titanium anodes during the electrolysis of dilute brine solutions have been studied. The phenomenon is explained in terms of a potential‐dependent change in surface structure and it is shown that platinum loss can be avoided by control of the anode potentia

ISSN:0021-8871    

DOI:10.1002/jctb.5010191004

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractConversions as high as 76·26% and 80·85% of chlorobenzene to benzoic acid were obtained when chlorobenzene was carboxylated with carbon monoxide and water at high pressure with nickel iodide‐silica gel catalyst (Ni:SiO2= 50:50) and without any catalyst (thermal) respectively, at the optimum temperature and pressure; these optima were much higher for the latter than for the former process. The lower yield in the catalytic process could be improved to some extent if the catalytic reaction was carried out at a pressure, reached by introducing nitrogen in addition to the usual input of carbon menoxide, almost equal to the optimum pressure of the thermal proc

ISSN:0021-8871    

DOI:10.1002/jctb.5010191005

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010191006

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY