Measurement of thermal diffusivity in polymer melts using forced Rayleigh light scattering

Abstract

Thermal diffusivity measurements on three polymer melts were made using the Forced Rayleigh Light Scattering technique. The polymers, which were tested at room temperature where they are in the molten state, included a polydimethylsiloxane and two polyisobutylenes. The optical setup and procedures developed in this study to conduct thermal Forced Rayleigh Light Scattering experiments are shown to be capable of producing thermal diffusivity data with a high degree of accuracy and precision. From measurements on a reference fluid (ethanol), experimental error was estimated to be no greater than 2%, and could be reduced to less than 1% by appropriate design of a series of experiments. Discrepancies of 4 and 14% in thermal diffusivity data on the polymer samples between measured values and those found in the literature were observed. It is suggested that these deviations are attributable to either sample variations or to errors in the techniques used in previous investigations. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1069–1078, 1999