Ultrasonic Study of Molecular Association of Polyethylenoxide Aqueous Solutions (A Method to Determine Molecular Weight)

Abstract

Ultrasonic velocity and isoentropic compressibility measurements are reported on aqueous solutions of polyethylenoxide of different molecular weights and different concentrations using pulsed ultrasonic apparatus operating at 2 MHz and 310 K. The data obtained as a function of concentration indicate the magnitude of the contribution due to relaxation of the backbone of the ethylene group. The results show a linear increase of density, velocity and viscosity values with increasing molecular weight and concentration of PEO. In contrast, the isoentropic compressibility decreases with increasing of molecular weight and concentration of PEO. A mathematical equation correlating isoentropic compressibility and molecular weight of the polymer is suggested. This was applied to the calculation of the molecular weight of unknown samples of PEO from their measured isoentropic compressibility; the results obtained agreed well with those obtained from osmometry.

Visco‐relaxation studies of polystyrene solutions in different solvents by ultrasonic

“…Densities were determined using a n ANTON PAAR densimeter (DMA-GO), thermostated with a precision of & 0.01 K [17]. The overall precision of the densities was estimated to be better than 3 x kg/m3.…”