摘要:

AbstractThe deformations of various roads under alternating load were measured. The amplitude of the loading force ranged from 300‐2000 kg.‐force, and the frequencies from 5‐60 cycles/sec. The results give a good impression of the mechanical rigidity of the constructions and of the stresses and strains raised in the carpet.In addition, the rates of propagation of the vibrations were measured at various frequencies. From these rates the dynamic Young's moduli of the various construction layers could be accurately calcu

ISSN:0021-8871    

DOI:10.1002/jctb.5010010701

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractA large amount of work has been done during recent years in order to find out the main properties of submicroscopic particles dispersed in a liquid from the mean physical properties of their solutions, such as viscosity, light‐scattering power, osmotic pressure, and Brownian diffusion.In general it is necessary to study several of these properties before predicting mass, shape, dimensions, mechanical or optical characters of the particles.This paper gives a brief survey of the results that may be obtained from the study of the double refraction which can be induced in a macromolecular solution by application of a proper field of orientation, namely a hydrodynamical or an electrical field. The effect of a magnetic or of an ultrasonic field is not discussed in this paper because of the uncertainty of the interpretation of the experimental results so far obtained.The case of a hydrodynamical field (stream double‐refraction) has actually been previously studied more thoroughly; it is considered in this paper, but some results obtained in the second case (Kerr effect), which seem to be very promising, will also be gi

ISSN:0021-8871    

DOI:10.1002/jctb.5010010702

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractTheX‐ray diffraction of 2 : 2′‐dihydroxy‐5 : 5′‐dimethyldiphenylmethane and its 3‐, 4‐, and 5‐ring polymers, twop‐cresol‐formaldehyde resins of known average molecular weight, and the 1 : 1‐addition complex of the 4‐ring polymer and ethylene dichloride have been examined using a Frevel focusing camera of high resolving‐power. Each pattern of a crystalline individual, however, proved different from the others and the number of repeating units in the polymer chain of thep‐cresol series is insufficient to lead to regularities of the type observed in other homologous series. There is a definite change from the crystalline to the amorphous state on passing from the 4‐ring to the 5‐ring polymer and the latter gives a photograph showing that the compound is approaching the condition ofp‐cresol—formaldehyde resins. No polymorphism was observed in specimens of 2 : 2′‐dihydroxy‐5 : 5′‐dimethyldiphenylmethane prepared by crystallizing from different so

ISSN:0021-8871    

DOI:10.1002/jctb.5010010703

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractFilms of polyamides were exposed to heat, ultra‐violet radiant energy, and different atmospheric conditions. The degradation products were collected in some cases and analysed by mass‐spectrometric techniques. The unexposed and exposed specimens were examined by the following techniques to obtain information concerning the changes in chemical and physical structure of the polymer: infra‐red absorption, ultra‐violet absorption, viscosity of solutions, measurement of dielectric constant and dissipation factor, photomicrography,X‐ray diffraction, electron microscopy, and effect of organic liquids. In addition, pyrolysis studies were made and some physical properties were determined. The results of the investigation show clearly that no single method gives a complete picture but that the results from several of the methods give an insight into the degradation mechanism. The general course of the degradation of polyamides may be described as follows : (I) splitting of the polymer chain at the C‐N linkages; (2) changes in degree of crystallinity or local order; and (3) loss of dipole‐associated

ISSN:0021-8871    

DOI:10.1002/jctb.5010010704

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

摘要:

AbstractIn order to obtain information on the mechanism by which scale is formed from natural waters at temperatures below the boiling point, an investigation has been carried out into the formation of calcium carbonate by the thermal decomposition of calcium bicarbonate solutions. It has been shown that the rate of formation appears to be unaffected by the presence of glass surface but is greatly increased by the presence of various finely divided materials, particularly calcium carbonate powder. A quantitative estimate of the influence of calcium carbonate surface has been obtained and it has been shown that its effect increases with increasing temperature.The experimental results indicate that the thermal decomposition of calcium bicarbonate solutions may be represented by the relation whereCrepresents the calcium concentration at a timetandGEis the equilibrium concentration. The quantitymis a function of the initial supersaturation (CI‐CE) and for the temperature range 75°‐90° c. is given bym= 1.99 × 10−8(CI‐CE)2.5.The experimental results have also been applied to the formation of scale from natural waters and graphs are supplied from which it is possible to calculate amounts of scale deposition under various

ISSN:0021-8871    

DOI:10.1002/jctb.5010010705

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010010706

出版商:John Wiley&Sons, Ltd    

年代:1951

数据来源: WILEY