POLYMER DRYING .7. H-1-NMR STUDIES OF EVAPORATION FROM LIQUID SATURATED POLY(STYRENE-CO-DIVINYLBENZENE)

Composition-studies were carried out in which samples of films composed of poly(styrene-co-divinylbenzene) particles enmeshed by poly(tetrafluoroethylene) fibers were saturated with dichloromethane and then allowed to evaporate at 23-degrees-C to virtual dryness as the H-1-NMR signals and residual weight of sorbed liquid were monitored. The correlations of H-1-NMR line-widths with the corresponding log of the number, alpha(t), of residual sorbed molecules per monomer unit show that sharp changes occur as alpha(t) passes through alpha(G), the composition that exists when all the liquid not sorbed (i.e., not present within the liquid-saturated particles), has been eliminated, and again as alpha(t) passes through alpha(g), the composition that exists when the particles attain the rigidity characteristic of the glassy state. Correlation of the corresponding T1 relaxation times with log alpha(t) show that sharp changes occur when alpha(t) becomes equal first to alpha's and then to alpha'g, the compositions that exist respectively when, firstly, all the sorbed liquid not immobilized by adsorption to the polymer chains within the particles has been eliminated, and then when the desorption of immobilized liquid from the chains causes the composition to begin to undergo transition from its rubbery state to its glassy state.