A modified Tian-Calvet microcalorimeter for polymer solution measurements

Abstract

The commercially available Tian-Calvet microcalorimeter assembly has been modified extensively to make it more precise and adaptable for polymer solution and dilution measurements. The changes made lead to about a tenfold increase in sensitivity; increase in base-line stability without need for extensive temperature, humidity, and vibration control; flexibility in recording both low- and high-energy outputs over long periods of time; and no need for use of the Peltier effect. Further, cell assemblies have been developed which are easy to construct and use, and which allow controlled agitation under conditions where the mechanical energy input can be corrected for. Preliminary measurements made with the new assembly on solutions of polystyrene in toluene and ethylbenzene yield for the heat of glass destruction a value constant within ca. ± 3 % independent of solution concentration or the solvent used.