Velocity and absorption of ultrasound in binary solutions of polyvinylpyrrolidone and water

Abstract

Ultrasonic velocity and absorption and shear viscosity measurements were made as a function of concentration and temperature for binary aqueous solutions of the polymer polyvinylpyrrolidone. The polymer has a molecular weight of 360 000 and was mixed with water in several concentrations ranging from 0% to 9% by weight. The frequency used was 21 MHz and the temperature range was 20 øC to 45 øC. The velocity shows a nonlinear increase with temperature and a nearly linear increase with concentration. The a/f 2 and viscosity values increase monotonically with concentration, and these values decrease with temperature. The temperature behavior, in a general sense, for the velocity and a/f 2 of the solution is similar to that of pure water. As the concentration increases from 0% to 9%, the viscosity increases by more than two orders of magnitude, while the a/f 2 value increases by less than one order of magnitude. No strong evidence of a critical concentration was observed.

A feasibility study for non-invasive thermometry using non-linear ultrasound

“…The latter is the temperaturedependent coefficient for square power law acoustic absorption, which is typical for water; most biological tissues show frequency power law absorption with an exponent between 1 and 2. The functions in Figure 3 are obtained by interpolating a set of values that have been measured at p 0 ¼ 0.1 MPa and over the temperature range T ¼ [0 C, 100 C], as reported in [49][50][51]. Moreover, Equation 3 requires a model of c ¼ cð p, T Þ, i.e.…”

“…Continuous results (solid lines) are obtained by interpolating discrete values (dots). The values are obtained from Lide, Spickler et al, and Wilson[49][50][51].…”

Temperature dependence of the viscoelastic properties of a natural gastropod mucus by Brillouin light scattering spectroscopy

“…Rates of decrease and velocities intermediate to those of water and snail mucus are observed for several aqueous polymer solutions with polymer concentrations similar to the glycoprotein concentration in the mucus over the temperature range 20 °C to 45 °C. 28–34…”

“…The observed decrease with increasing temperature is similar to that previously reported for water 37 and other aqueous polymer solutions. 29–33…”

“…Rates of decrease and velocities intermediate to those of water and snail mucus are observed for several aqueous polymer solutions with polymer concentrations similar to the glycoprotein concentration in the mucus over the temperature range 20 1C to 45 1C. [28][29][30][31][32][33][34] For À2.5 1C Z T Z À11 1C, the mucus hypersound velocity displays an overall increase at a decreasing rate from its minimum value of B1570 m s À1 at T pt = À2.5 1C to B1700 m s À1 at À11.0 1C. This behaviour contrasts with that for supercooled water for which the velocity is B10-30% lower and which exhibits a rapid monotonic decrease with temperature over this range.…”