Sound velocity measurements

High Pressure Sound Velocimeters. As discussed earlier, sound velocity measurements can yield precise compressibilities of solutions. Wilson (109) was the first to develop a high pressure sound velocimeter that could be used over a wide range of pressures and temperatures. He used the "sing around" system to measure the high pressure sound speeds of water (109), D2O (120), and seawater (121) to a precision of 0.2 m sec l which is equivalent to 0.012 x 10 bar- in 6s Barlow and Yazgan... 

Similarly, foamed urethane samples were prepared with various air contents, sound velocity measurements were made on the foamed... 

Passynski measured the compressibility of solvent (fig) and solution (fi), respectively, by means of sound velocity measurements. The compressible volume of the solution is Vand the incompressible part, v (v/V = a). The compressibility is defined in terms of the derivative of the volume with respect to the pressure, P, at constant temperature, T. Then,... 

One has to know the free volume available to the unbonded molecule, and its temperature dependence, so that the translational entropy may be calculated. The term V g may be found from sound velocity measurements [Eq. (2.96)]. If one takes a number of unassociated liquids and plots their free volumes Vy- obtained from the velocity of soimd against their molar weights, an extrapolation through a molar weight of 18 will give for a freely rotating monomer of water. A value of 0.2 cm mol for is obtained. The temperature dependence of V g is obtained from the integration of the heat capacity... 

There is a linear relation between the free volume from sound velocity measurements and the hole volume (from volume of fusion data). 

Note that Eq. (6.2.8) may be inverted to determine y from a measurement of the velocity of sound. Inasmuch as y = Cy + R)/Cy, both Cy and Cp are directly available from sound velocity measurements. 

The most accurate method of measuring elastic constants is based on the use of ultrasonic sound velocity measurements. This is a dynamical... 

Ultrasonic sound velocity measurements provide an easy method of determination of the elastic properties as a function of temperature by using a suitable variable temperature cell. 

C) Compressibility and Hydration. We will now consider whether the Increased ollgodextran-water interaction is reflected in its degree of hydration. Among many methods for estimation of the degree of hydration, a convenient technique is a compressibility method based on sound velocity measurements (19, 20, 21, 22). The principle of this method is as follows. 

Another possibility of correcting the velocity-of-sound effect is a recalibration of the transmitters or direct sound velocity measurement. 

Fig. 2. Electronics block diagram for pulse-echo-method sound-velocity measurements. Frequency divider is used to provide phase-coherent pulses for a pulse-superposition method for sound-velocity-change measurements, due to changing temperature in the present case.

Fig. 4. Electronics block diagram for resonance-method sound-velocity measurements. D, G, and S denote driver transducer, gauge transducer, and specimen. Specimen length is adjusted so that oscillator resonance occurs near the transducer resonance frequency.

Finally, a fluctuation volume/nue can be determined from sound-velocity measurements, and this describes the motion of the center of gravity of a molecule as a result of thermal motion (see Table 5-7). 

Methods used to characterize orientation are wide-angle X-ray scattering, ir spectroscopy, small-angle light scattering, birefringence measurements, polarized fluorescence, and sound-velocity measurements. They refer to effects resulting partly from a combination of both types (combined effect). 

Figure 5-36. Optical birefringence A Aiexp as a function of orientation factor/from sound-velocity measurements of different polymers (after H. M. Morgan).

The method allows the orientation factor to be determined for films and fibers during the actual straining or stretching process. A linear relationship between the orientation factor determined by sound-velocity measurement and that obtained by birefringence has been found experimentally (Figure 5-36). 

Macroscopic volume and mass Gas sorption SEM Static or d3mamic fluid permeation Sound velocity measurement Wetting EDX... 

Figure 4. The positive dispersion of the sound velocity, measured as (u — vo)/vo, is reported at all the investigated pressures, same symbols as in Fig. 3. Remarkably, it does not depend on pressure. Data from Ref. [16] at the room pressure melting point, 308 K, are also reported (dashed line).

Sound velocity measurements on crystals with large magnetostriction provide evidence for changes in the lattice dynamics at the spin reorientation transition. Mossbauer studies of such systems show that there are changes in the recoil-free fraction at the spin reorientation transition (Seh Nowik, 1981). 

The structure of diamond favors low-frequency transmission and the material has high sound velocity. Measurements of up to 20 knr /s are reported. By comparison, the speed of sound in beryllium is 12.89 km/s and in silicon slightly less than 10 km/s.( l... 

Compressibility and Viscosity. Maybury and Coulter have obtained the compressibilities of sodium-, lithium-, and calcium-ammonia solutions from sound-velocity measurements using the relation,... 

TABLE 2. Elastic constants c. y determined at room temperature for TSHD monomer and polymer using Brillouin scattering f45j and sound velocity measurements [47], ... 

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