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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 19 (1968), S. 981-984 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 805-815 
    ISSN: 0887-624X
    Keywords: polystyrene ; sorption ; desorption ; evaporation ; polymer-inclusion complexes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The results obtained in time studies that monitored evaporation from liquid-saturated poly(styrene-co-divinylbenzene) to virtual dryness at temperatures ranging from 20 to 80°C confirm those reported earlier for multireplicated time studies at 23 ± 1°C; i.e., when the residual composition (αt, in sorbed molecules per phenyl group) attains the glassy state composition, the value of αt thereafter is given by a linear combination of no more than six exponential decay functions. The logarithms of the rate constants (ki) for decay of these populations at a given temperature decreased linearly with i, the population identification number in the order of decreasing decay rate. The Arrhenius activation energy (ΔEi) for increase in ki with temperature was characteristic of the sorbed species, but it was independent of i. The logarithms of the frequency factors (Ai) decreased linearly with i, the slope of which was numerically equal to that observed for the corresponding ki relationships, signifying that the stepwise decrease of the latter at a given temperature is attributable primarily to a corresponding incremental decrease in entropy. It is suggested that this reflects discrete changes in the molecular structure of polymeric inclusion complexes formed during the transition from the rubbery to the glassy state, as discussed in the text. © 1993 John Wiley & Sons, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 649-667 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In these time studies of evaporation from liquid-saturated microporous composite film samples, comprised of poly(styrene-co-divinylbenezene) particles enmeshed in poly(tetrafluoroethylene) microfibers, the samples were preswelled to saturation in a good solvent, such as toluene, which was then replaced via solvent exchange in excess test liquid before the start of the time study that monitored the residual weight (Wt) of sorbed liquid to virtual dryness. The patterns of change with time (i.e., Wt. vs. t and Log Wt vs. t) obtained thereby were compared with the corresponding time studies already reported for evaporation from equivalent polystyrene-liquid (PS-L) systems that did not have a history of preswelling in a better solvent. These comparisons show that the history of the samples in its liquid-saturated gel state can affect markedly the kinetics of desorption from the PS-L system in its glassy state, and also during the interval of transition from the rubbery state to the glassy state, as discussed in the text. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This kinetic restudy of the physical changes that occur during evaporation-induced transition from the rubbery to a glassy state of polystyrene-liquid systems shows that such transitions occur via two mechanistic pathways. The first is random nucleation of microdomains of self-associated polymer segments owing to a time-dependent logarithmic decrease in the number of adsorbed volatile molecules per phenyl group of residual mobile polymer segments. The second is a therodynamically driven self-association of adjacent monomer units with concomitant explusion of the adsorbed molecules, which appears to propagate via a “dominolike” chain reaction. Conceptually this is a three-dimensional “zippering-up” of suitably close polymer segments to produce the corresponding macrostructural network of self-associated polymer. The kinetics of the latter is zero-order, and this dominates the overall kinetics of evaporation during the latter portion of the transition interval, presumably owing to changes in entropy of the system as it progresses from the mobility characteristic of the rubbery state to the rigidity characteristic of a glassy state. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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