Bibliothek

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    ISSN: 1572-8935
    Schlagwort(e): Thermotropic liquid crystalline polymer ; Blend ; Miscibility ; Positron ; Free volume
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Abstract Blends of a thermotropic liquid crystalline polymer [poly(p-oxybenzoate-co-p-phenylene isophthalate)] (HIQ45) and a polycarbonate (PC) are studied with regard to their miscibility and free volume behavior. The glass transition temperatures (Tgs) of the blends are found to be uncharacteristically higher than those of the pure components, even increasing with the addition of the low-Tg component, HIQ45. Based on the non-appearance of the Tg of HIQ45 in the tanδ spectra of the blends and the observed homogeneous morphology of the blend, mixtures of HIQ45 and PC are concluded to be a miscible blend system. The free volume properties determined by positron annihilation lifetime spectroscopy show that close packing does not occur in these miscible blends as indicated by positive deviations in size and number concentration of free volume cavities from average values as a function of blend composition. The increase in free volume is attributed to the loss of liquid crystalline alignment of HIQ45 and disturbed packing of PC molecules due to intimate miscibility between different molecules. The free volume fraction index of the blend correlates well with measured blend density.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 451-458 
    ISSN: 0006-3592
    Schlagwort(e): immobilized glucose isomerase ; substrate protection ; reactor analysis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The effect of substrate protection on enzyme deactivation was studied in a differential bed and a packed bed reactor using a commercial immobilized glucose isomerase (Swetase, Nagase Co.). Experimental data obtained from differential bed reactor were analyzed based on Briggs-Haldane kinetics in which enzyme deactivation accompanying the protection of substrate was considered. The deactivation constant of the enzyme-substrate complex was found to be about half of that of the free enzyme. The mathematical analysis describing the performance of a packed bed reactor under the considerations of the effects of substrate protection, diffusion resistance, and enzyme deactivation was studied. The system equations for the packed bed reactor were solved using an orthogonal collocation method. The presence of substrate protection and the diffusion effect within the enzyme particles resulted in an axial variation of effectiveness factor, ηD, along the length of the packed bed. The axial distribution profile of ηD was found to be dependent on the operation temperature, Based on the effect of substrate protection, a better substrate feed policy could be theoretically found for promoting productivity in long-term operation. © 1993 John Wiley & Sons, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...