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  • 1
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To test the molecular parameters concerning gas sorption in polymers, the concentration of CO2, N2O, CO, N2, CH4 and the noble gases Ne, He in glassy poly(butylene terephthalate) films (PBTP) has been studied gravimetrically with a recording microbalance at 25°C. The sorption isotherms exhibit downward curvature to the pressure axis. As neither solubility nor adsorption can explain the experimental results, analysis was carried out based on the dual-sorption model: gas dissolution and microvoid filling are considered as independent sorption mechanisms. The parameters of the dual-sorption model for the mentioned penetrants are determined. The results indicate that for parameter correlation the Lennard-Jones potential parameters give a rough idea, but size exclusion of gases in small diameter microvoids is proposed and special chemical interactions must be considered.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 13-20 
    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: Sorption measurements of CO2, Ne, and Ar in poly(butylene terephthalate) (PBTP) films were studied by the gravimetric method with a recording microbalance at 298 K in the pressure range of 1-22 bar. The semicrystalline samples were annealed and oriented at 373 K. The sorption isotherms for CO2 in PBTP films in the glassy state can be well described by the dual-sorption theory. The nonlinear sorption behavior of Ne and Ar can be satisfactorily analyzed using the sorption model developed for noble gases in PBTP. For the undrawn annealed films, it has been found that the increment of crystallinity leads to the reduction of the equilibrium gas concentration. For the oriented films, the gas concentration rises with increasing draw ratio. It appears that the sorption behavior for all tested gases in the oriented PBTP films does not depend on the changes of crystallinity and crystalline morphology under extension. The difference of the critical pressure p* indicates the change in the size of the frozen microvoids existing in the noncrystalline phase, which was altered by annealing and drawing. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 123-126 
    ISSN: 1042-7147
    Keywords: Poly(p-phenylene sulphide) ; Carbon dioxide ; Transition temperatures ; Plasticization ; Dilatation ; 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
    Notes: Static pressure usually increases the transition temperatures of polymers by decreasing their free volume. If the pressurizing medium is soluble in the polymer matrix, the opposing effect of increasing the free volume is possible. Those shifts of transition temperatures were monitored with a medium-pressure Differential Scanning Calorimetry (DSC) device. The influences of sorbed and surrounding gas molecules are demonstrated by changes occurring in the transition temperature regions. The results show the severe plasticizing effect of CO2 on poly(p-phenylene sulphide) (PPS). The glass transition temperature TG and the temperature of crystallization TC are influenced by sorbed gas molecules. They decrease due to sorbed CO2 molecules. Glass transition is lowered, but is difficult to interpret, as relaxation phenomena which diminish with increasing pressure occur during DSC runs. In crystallites no gas solution is usually possible, so that the melting point of PPS is mainly affected by influences other than plasticization.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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