The results of ultrasonic absorption and velocity measurements for the system perfluoromethylcyclohexane-carbon tetrachloride are presented. In addition, viscosity measurements were made. Ultrasonic absorption at 5, 7, 10, 15, 21, and 25 MHz, above critical temperature Tc, is analyzed using the dynamic scaling theory of Ferrell and Bhattacharjee. The values of alpha/f2 vs f-1.06 show a good agreement with the theory. The experimental values of alpha/alpha c for the binary mixture are compared to the scaling function F(omega*).
The absorption and velocity of ultrasound were studied for solutions of 10 000 molecular-weight poly (ethylene glycol) and distilled water. The frequency used was 21 MHz and the concentration (by weight) ranged from 1% to 9% of poly (ethylene glycol) in water. The shear viscosity was also measured. Temperatures of 25, 30, 35, 40, 45 °C were used for the measurements. Observations showed that the ultrasonic absorption decreases with increasing temperature at a given concentration and also increases with concentration at a given temperature. The velocity increases with increasing temperature and concentration. Finally, the shear viscosity measurements show it decreasing with temperature but also increasing with concentration.
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 multiperturbation theory has been developed for molecular systems. In the present paper we extend this theory to fifth order in the energy. The "bare-nucleus" hydrogenic function is chosen as the zero-order wave function rather than the more customary hartree-fock function. With this choice the multiperturbation wave functions are independent of the nuclear charges and of the total number of nuclear centers and electrons for the molecule and are thus completely transferable to other systems. Making the simplest possible choice, we describe an n-electron, m-center polyatomic molecule as n "hydrogenic" electrons on a single center perturbed by electron-electron and electron-nucleus coulomb interactions. With this choice of zero-order Hamiltonian (H0) the first-order wave function for any polyatomic molecule will consist entirely of two-electron, one-center and one-electron, two-center first-order wave functions. These are exactly transferable from calculations on He-like and H2-like systems. To calculate the first-order and second order correction for the wave function of any polyatomic molecule, we need the first-order and second-order correction for a two-electron atomic wave function, the first-order and second-order correction for a one-electron diatomic molecular wave function and some additional mixed second-order corrections. The wave functions necessary will be two-center, one-electron at most. The second-order wave function for a polyatomic molecule contains additional contributions which cannot be obtained from the simple subsystems, but represent multiple perturbation contributions which are two electron diatomic, and one-electron triatomic in character. The expressions for the multiperturbation energy-expansion coefficients through fifth order are derived.
Ultrasonic velocity and absorption as a function of temperature, concentration, and frequency (5-25 MHz) and shear viscosity as a function of concentration and temperature are reported for the binary mixture nitrobenzene-n-hexane in the homogeneous phase above Tc. For the observed absorption at critical concentration and critical temperature ac/f 2 vsf-•.o6 yields a straight line as predicted by the dynamic scaling theory of Ferrell and Bhattacharjee [Phys. Rev. A 24, 1643 ( 1981 ) ]. Also, the critical amplitudes of the thermal expansion and specific heat have been calculated using the two-scale factor universality relation. The adiabatic coupling constant g is calculated and compared to the experimental value. In addition, the experimental values of a/ac (where a is the absorption at critical concentration above the critical temperature) for nitrobenzene-n-hexane are compared to the scaling function F(co*) and show a good agreement with the theory. Finally, the velocity for the system at the critical concentration above the critical temperature appears to decrease linearly with increasing temperature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.