Self-Diffusion of Small Molecules into Rubbery Polymers:A Lattice Free-Volume Theory

Liborio Ivano Costa, Liborio I. Costa, Giuseppe Storti

    Risultato della ricerca: Articlepeer review

    19 Citazioni (Scopus)

    Abstract

    In the framework of the Free Volume Theory, a new equation was derived for the evaluation of self-diffusion coefficients of small molecules in polymers above the mixture glass transition temperature. The derivation of the equation turned out to be straightforward once the equivalence between the free-volume and the unoccupied volume given by Thermodynamic Lattice Theories is assumed. A parameter evaluation scheme is proposed, which is substantially simpler compared to the conventional Vrentas-Duda approach, even without losing generality. The key assumption is discussed and its consistency is verified from a numerical viewpoint. A comparison with experimental solvent self-diffusion coefficients for several solvent/polymer binary systems confirmed that the proposed theory presents good correlative ability over wide temperature and composition ranges. Moreover, the introduced thermodynamic foundation allows one to easily include the pressure effect too. In the frame of the proposed Lattice-Free Volume theory, the sizes of the polymer jumping units decrease with temperature and increase with pressure. Such behavior converges with theoretical expectations and opens the way for a predictive Free Volume Theory.
    Lingua originaleEnglish
    pagine (da-a)529-540
    Numero di pagine12
    RivistaJOURNAL OF POLYMER SCIENCE. PART B, POLYMER PHYSICS
    Volume48
    Stato di pubblicazionePublished - 2010

    All Science Journal Classification (ASJC) codes

    • Condensed Matter Physics
    • Physical and Theoretical Chemistry
    • Polymers and Plastics
    • Materials Chemistry

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