Heats of water vapor sorption in swelling biopolymers

Abstract

Abstract Heats of water vapor sorption by three biopolymers, polygalacturonic acid, sodium hyaluronate, and calcium salt of bovine submaxillary mucin, were determined calorimetrically. These calorimetric heats of sorption were compared with the isosteric heats of sorption as a function of water uptake. Maxima in both of these functions occur at “monolayer” coverage. The differences between the calorimetric and isosteric heats are explained in terms of the irreversibility of the sorption process, especially in terms of the structural changes that occur in the biopolymers during swelling.