摘要:

The theory of plastic flow is based on the fundamental law proposed by Bingham, which is as follows:dvdr = μ(F − f)(1) wheredvdris the velocity gradientG, μ the mobility,Fthe shearing force, andfthe yield value.

ISSN:0148-6055    

DOI:10.1122/1.2116227

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

One may safely state thatevery material flows under certain conditions. It has been proved that this holds good forevery solid, even for extremely brittle materials, which under ordinary conditions crumble to pieces as soon as the stress applied exceeds the cohesion. The condition under which such a material has to be placed to make it flow is a sufficiently high pressure acting on all sides. The brittleness then disappears and the material, instead of being friable, flows, like any plastic substance. This has been shown for cubes of marble by Karman.

ISSN:0148-6055    

DOI:10.1122/1.2116288

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

Since attention was drawn by E. Hatschek and by E. C. Bingham to the anomalies of flow of suspensions and colloidal solutions, a great deal of work on this subject has been carried out, not only on suspensions of solid particles but also upon emulsions and solvated colloids.

ISSN:0148-6055    

DOI:10.1122/1.2116290

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

At the present time in the paint, varnish, and lacquer industry there are a number of different methods for determining the viscosity, or as the paint man expresses it “the consistency” of a paint, varnish, or lacquer. It is difficult, and in some cases impossible, to obtain a correlation between these methods, which means that practically each type of product in this industry has its empirical method for measuring consistency. It would be highly desirable if one method and apparatus could be used throughout the industry so that intercomparisons could be made between all types of products. This paper is a description of an attempt to produce such an instrument which in addition to being universal would be correct in theory, would have the speed necessary for industrial use, and would require only a small amount of material.

ISSN:0148-6055    

DOI:10.1122/1.2116291

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

The elastic limit is ordinarily defined as the limit beyond which Hooke's Law no longer holds. In terms of the usual engineering tests the elastic limit is indicated by a permanent deformation. More accurate measurements show, however, that the ratio of stress to strain is not a constant even before the point of permanent deformation. Calculations based on the electrostatic theory of crystal lattices show that instead of the stress,f, being simply proportional to the strain, Δr(i. e., f = f′Δr), it is to be represented by an infinite convergent series of the formf = f0 + f′ Δr + 12! f″(Δr)2 + 13! f‴(Δr)3± …. Normallyf0is zero, so that Hooke's Law is to be regarded as only an approximation based on the neglect of terms of higher order thanf′Δr. It is therefore to be expected that Hooke's Law will fail for very refined measurements. The fact that it holds as well as it does up to the point of permanent deformation led Joffé to investigate the mechanism by which a permanent set is produced.

ISSN:0148-6055    

DOI:10.1122/1.2116292

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

Large amounts of work have been carried out in the study of flow conditions of liquids since the classical work of Poiseuille in 1842. Numerous satisfactory methods of measurement have been used for the truly viscous liquids. In the study of colloidal dispersions these same methods of measurement and similar methods of calculation have been applied. With viscous liquids the shearing stress is directly proportional to the rate of shear, but this is not generally true for colloidal dispersions of the nitrocellulose type (Figures 4 to 8). Hatschek some time ago called attention to this fact. To account for the difference in behavior of viscous liquids and hydrophylic substances in dispersing medium, M. von Smoluchowski has considered the latter as highly solvated masses which enclose dead areas of liquid. When the solution is subjected to shear these particles deform and the liquid in the dead areas acts as a drag on free flow. Similar considerations have been brought forward and extended by R. Hess and W. Ostwald.

ISSN:0148-6055    

DOI:10.1122/1.2116293

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

In measuring the consistency of suspensions or plastic materials by the capillary tube method, it is necessary first to obtain a flow‐pressure graph. This requires that successive observations should be made at different rates of flow. With the earlier forms of plastometer or consistometer only one point could be obtained on the required graph with a single run, and it proved unduly time consuming to obtain a sufficient number of points to adequately define the graph.

ISSN:0148-6055    

DOI:10.1122/1.2116294

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

摘要:

Ever since Thomas Graham proposed the employment of a “liquid transpiration” tube (i. e., a capillary viscometer) as a “colloidoscope” (30b), internal friction or resistance to shear has been one of the most frequently used properties in the investigation of colloidal dispersions. Although it soon became evident that this property is in certain instances a very sensitive indicator of differences and changes in the inner structure of dispersions, the exact relationship between internal friction and structure has unfortunately remained obscure. In spite of this shortcoming, the “colloidoscope” or an equivalent instrument has proved its value as an empirical tool for both scientific investigations and industrial control. To serve these purposes, attention has been directed particularly to the refinement of experimental methods and to the empirical correlation of observable quantities.

ISSN:0148-6055    

DOI:10.1122/1.2116295

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.2116296

出版商:The Society of Rheology    

年代:1929

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.2116297

出版商:The Society of Rheology    

年代:1929

数据来源: AIP