Design Problems in Ebulliometry of Polymers

Abstract

There are two fundamental problems in ebulliometry. The first is to find a detector with sufficient sensitivity to measure the very small boiling point elevations obtained with dilute solutions of high polymers. This problem is solved easily with thermistor bridges and modern high gain amplifiers. The second problem is that of random thermal fluctuations or background noise in the ebulliometer itself. When this study began, it was considered that there were three probable sources of noise, viz., (1) superheated liquid from the Cottrell pump, (2) pressure fluctuations and differences within the ebulliometer, and (3) the presence of foam which usually appears when a polymer solution is maintained at the boil. However, the tests carried out with the ebulliometers described here seem to indicate that the difficulties may be inherently associated with the polymer solutions themselves.