George Halsey

The Adsorption of Hydrogen on Tungsten Powders

An analysis of the extensive experimental data of Frankenburg on the adsorption of hydrogen by metallic tungsten powder between −194 and 750°C has been made, using the Fowler‐Guggenheim treatment of adsorption phenomena as the mode of approach. It has not been found possible to interpret the data in terms of interaction between the adsorbed species on a uniform adsorbent surface. It is shown that the experimental data can be interpreted on the basis of a non‐uniform surface without interaction, the heterogeneity of the surface being specified in terms of an exponential distribution of sites given by the distribution function N=ce−χ/χm, where χ represents the energy difference between the lowest energy state of the gas and the lowest energy of the adsorption complex. Such a distribution function yields the experimentally observed relation d lnp/d lnθ=constant at constant temperature. Such a heterogeneity is especially significant in the case of tungsten metal which hitherto has been treated as an essential...

Mechanical Properties of Textiles, I:

In this paper the spring-dashpot theory which has been applied in previous papers in this series to single fibers and to yarns is applied here to the experimental investi gations of a plush fabric which have been published by Fox and Schwarz. This serves to outline the experimental methods which should be followed if the data are to have maximum theoretical significance.

A New Theory of Non-Linear Viscous Elasticity

The stress-strain curve of a material is calculated on the hypothesis that when flow occurs a section of the molecular chain constituting the material changes from a configuration A to a con figuration B and thereby becomes unable to elongate again. Except for a small elastic deformation of both structures, the elongation is proportional to the fraction of the material in the B configura tion. The two components are assumed to be in solution with one another, and the rates of trans formation are then proportional to the relative abundance of the transformed species. These rates are written in the manner of the Eyring theory of reaction rates. Systems of more than two com ponents are discussed and several examples are calculated. The calculated curves show good qualitative agreement with stress-strain curves of the nylon-wool-rubber type.

The Mechanical Properties of Textiles, III

This paper is concerned with the deformation of a number of essentially independent molecules or molecular segments distributed statistically with respect to the distance between the ends of the molecules. They are supposed to be free to assume many configurations (as a result of thermal agitation) except at certain points which are stabilized by chemical forces to form the more or less tightly held (and thus well-defined) ends of the molecules.The problem solved here is as follows: Given an equilibrium distribution as a function of certain parameters, and given the expression for bulk properties in terms of molecular coordinates, what is the form of the tension as a function of the elongation and the various parameters?

Mechanical Properties of Textiles: VI. A Study of Creep of Fibers

of breaking are to be distinguished. When in every portion of the sample there is equal flow and hence equal attenuation, the relationship between time and elongation will be nearly a linear one, in the range of small elongation, such as the ones commonly encountered in textile mechanics. When examined from the standpoint of stability, this apparently simple mode becomes complicated because of the special restrictions necessary to make it stable. The requirement is that when a given cross section changes from S to S 8S that its elastic constant k increases an amount 8k, so that

Mechanical Properties of Textiles, X: Analysis of Steinberger's Data on Creep of Cellulose Acetate Filaments

paper is to explain his results on the basis of the theory of the three-element model. Consideration of the mechanical properties of a fiber based on the three-element model gives rise to a creep curve of three distinct parts, as shown in Figure 1. The first two parts of the curve, OA and AB, correspond to the direct action of the threeelement model under discussion and can be explained on the basis of either form of this model as given in Figure 2. Both forms are equivalent, as can be seen. However, creep can be explained most conveniently by form B, which is the form on which all theoretical

The Mechanical Properties of Textiles: II. A General Theory of Elasticity with Application to Partially Rubber-Like Substances

This paper is concerned with the deformation of a number of essentially independent molecules or molecular segments distributed statistically with respect to the distance between the ends of the molecules. They are supposed to be free to assume many configurations (as a result of thermal agitation) except at certain points which are stabilized by chemical forces to form the more or less tightly held (and thus well-defined) ends of the molecules. The problem solved here is as follows: Given an equilibrium distribution as a function of certain parameters, and given the expression for bulk properties in terms of molecular coordinates, what is the form of the tension as a function of the elongation and the various parameters?

Mechanical Properties of Textiles, IX: A System Showing a Distribution of Non-Newtonian Viscous Elements

curves, using the method of the three-element model of previous papers, certain persistent difficulties have been encountered. The curve of Figure 1 shows an extreme case. The ultimate slope is well defined. Therefore, simple permanent set cannot be a factor over moderate time ranges. Repeated cycles could then be expected to yield a limiting curve (one of the criteria of Paper VIII). In order to place the line of ultimate relaxation, three procedures are resorted to, using the welldefined ultimate slope. First, the line is drawn from the origin. This is unsatisfactory for two reasons: first, the line does not cut the experimental curve with constant angle and, second, it does not agree with the position of ultimate relaxation as determined

Mechanical Properties of Textiles, VII* The Visco-Elastic Properties of a Wool Fiber

From a broad point of view, the answer to the latter question is: &dquo;If a material has been competitively selected for a textile fiber, it necessarily possesses certain properties, including a stress-strain diagram similar to that of any other fiber.&dquo; The query &dquo;Why, then, are two of these similar processes not discovered in a fiber, where the opportunity presents itself?&dquo; is not to be denied, but the general observation can be made that, if several competing processes seem qualitatively available, usually a single one will be easiest by far to the palpable exclusion of the others.

Mechanical Properties of Textiles, V: The Three-Element Model Under Any Experimental Condition

because only this restraint makes the equations amenable to simple treatment. In practice, it is often desirable to calculate behavior that is characterized by its dependence on any restraint, assuming in this discussion that the constants of the model have been evaluated from simple experiments of the type of equation (1) and hence are available for computation. However, in solving even the simplest cases analytical difficulties are met with, and it is of interest to consider here simple point-by-point methods. The method of synthesizing the total force, F, from the partial forces, f, on the dashpot and spring in series, and F-f, on the single spring will be employed, as in the earlier papers. If the restraint is of the form