Polymer drying, 1. Time‐studies of desorption from liquid saturated poly(styrene‐co‐divinylbenzene) microparticles

Abstract

AbstractTime studies of evaporation from liquid‐saturated poly[(Sty)98‐co‐(DVB)2] particles enmeshed in poly(tetrafluoroethylene) microfibers show that it is possible to distinguish kinetically between volatile sorbed molecules not absorbed to the polymer chain and those that are adsorbed to it. Elimination of the nonadsorbed molecules occurs first, and it follows zero‐order kinetics. The subsequent elimination of the residual volatiles, namely the adsorbed molecules, follows first‐order kinetics, with a rate constant that remains constant only until the enmeshed microparticles undergo transition from the gel to the glass state. Thereafter, is observed a sequence of up to six independent rate constants in a series of intervals, the durations of which increase exponentially. This is interpreted to mean that after evaporation to the glass transition composition, the total weight of residual adsorbed molecules is given by a linear combination of exponential decay functions for up to six populations of adsorption sites, the rate constants for which reflect the force of association between the sites and the retained molecules.