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Diffusion, swelling, and consolidation in glassy polystyrene microspheres
Author(s) -
Enscore D. J.,
Hopfenberg H. B.,
Stannett V. T.
Publication year - 1980
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760200117
Subject(s) - sorption , desorption , materials science , polystyrene , hexane , diffusion , penetrant (biochemical) , swelling , thermodynamics , dispersity , consolidation (business) , kinetics , analytical chemistry (journal) , polymer , polymer chemistry , chromatography , chemistry , composite material , organic chemistry , adsorption , physics , accounting , quantum mechanics , business
The effects of prior thermal and swelling history on the kinetics and apparent equilibria of subsequent n‐hexane sorption in monodisperse, submicrometer diameter, glassy polystyrene microspheres were studied. Repetitive sorption and desorption cycling was compared with continuous sorption and desorption experiments. The apparent equilibrium uptake of n‐hexane in preswollen samples decreased monotonically with the cumulative time under vacuum independent of the cycle frequency or the number of sorption‐desorption cycles. This consolidation was modeled as a first order relaxation process with a single characteristic relaxation time. “As‐received” samples swelled in the presence of the penetrant and the apparent equilibrium n‐hexane content increased monotonically with the time under n‐hexane. The Berens‐Hopfenberg diffusion‐relaxation model accurately describes the cyclic and continuous swelling behavior of the “as‐received” sample. At each temperature studied, a true equilibrium n‐hexane content was approached asymptotically for the preswollen and “as‐received” samples after sufficient time under vacuum or n‐hexane, respectively. Whereas the apparent sorption equilibria were controlled by the cumulative time under vacuum or n‐hexane for the preswollen and “as‐received” samples, respectively, the absorption kinetics are subject to a systematic variation which depends only on the immediate prior vacuum history of the sample. The temperature dependence of the kinetic and equilibrium parameters describing diffusion, consolidation, and swelling suggests a unified molecular interpretation of these diverse glassy‐state transport and relaxation processes.