Diffusion and relaxation in glassy polymer powders: 2. Separation of diffusion and relaxation parameters

摘要: Abstract Gravimetric sorption measurements for organic vapours in monodisperse glassy polymer powders have shown widely varied non-Fickian kinetic behaviour. These kinetics are interpreted by a single mathematical model involving linear superposition of one or two phenomenologically independent first order relaxation terms upon the ideal Fickian diffusion equation. Analysis experimental data submicron through this yields and equilibrium parameters describing individual contributions processes. This analysis has been applied to both integral incremental vinyl chloride, acetone, methanol poly(vinyl chloride) n-hexane polystyrene. Sorption initially penetrant-free samples is dominated rapid process, while sorptions show larger relative from slow The processes appear be related redistribution available free volume relatively large scale segmental motions relaxing polymer. diffusion—relaxation seems provide meaningful several ‘anomalies’, including very approach apparent equilibrium, two-stage sigmoidal curves, curves an initial maximum followed temporary desorption subsequent resorption.