Search

A method for measuring the modulus of elasticity of fibers and films by sonic means is described and the results of an exploratory study of the modulus in various natural and synthetic fibers and films are given. The method is based on the equation for the propagation of longitudinal waves in elastic materials, which expresses the velocity of propagation in terms of the elastic modulus and density of the medium. The procedure involves measuring the sound velocity and calculating the modulus, using the proper density value. The modulus so calculated is characteristic of a dynamic, short period measurement, since a sound frequency of approximately 10 kilocycles per second was used. The range of moduli found was from 1×1010 to 50×1010 dynes per square centimeter. Correlations of moduli with other physical properties are given. [ABSTRACT FROM AUTHOR]

The method of Ballou and Silverman for obtaining a dynamic modulus of elasticity in continuous filaments by measuring the velocity of longitudinal waves has been extended to include the measurement of attenuation of the wave along the sample. A theory of this method is presented in which special emphasis is placed on the measurement of the relatively low attenuations encountered in some polymeric materials, as compared to the higher attenuations in rubber-like materials reported by Nolle. The results of attenuation measurements on some polymers in filament form are presented to show the application of the method and theory. The use of attenuation measurements in characterizing some of the physical properties of high polymers is discussed. [ABSTRACT FROM AUTHOR]

The use of the fixed path supersonic interferometer has been extended to liquids, with a view to its possible application to the measurement of sound velocities in small amounts of liquid. The present study has been confined to small cylindrical cells of fixed length, containing 5 or 6 cc of liquid, bounded at one end by a quartz vibrator having a natural frequency around 3.5 megacycles per second, and at the other by a plane reflector. Successive cell resonances were obtained by varying the frequency, and detected optically by observing the increase in diffracted light intensity which occurs when standing waves are formed. In interpreting the results, account must be taken of the departure from unity of the reflection coefficient γ, which occurs at liquid-solid boundaries. This introduces a phase change which effectively lengthens the cell path. A description of the interferometer, its theory, and the results obtained with water, dextrose solution, and ethyl alcohol are given. [ABSTRACT FROM AUTHOR]

A method for measuring the modulus of elasticity of fibers and films by sonic means is described and the results of an exploratory study of this modulus in various natural and synthetic fibers and films are given. The method is based on the equation for the propagation of longitudinal waves in elastic materials, which expresses the velocity of propagation in terms of the elastic modulus and density of the medium. The procedure involves measuring the sound velocity and calculating the modulus, using the proper density value. The modulus so calculated is characteristic of a dynamic, short period measurement, since a sound frequency of approximately 10 kilocycles per second was used. The range of moduli found was from 1×1010 to 50×1010 dynes per square centimeter. Correlations of moduli with other physical properties are given. [ABSTRACT FROM AUTHOR]