Release of additives from packaging plastics

I.E. Helmroth

    Research output: Thesisinternal PhD, WU

    Abstract

    <em><p>Keywords</em> : migration, diffusion, additives, polymer, low density polyethylene, polymer swelling, Fick, stochastic modelling</p><p>The diffusion of small molecules from polymers into food is studied. A better understanding of this process is important for the development of mathematical models to predict migration from packaging plastics into food. To study the effect of food absorption by the plastic on diffusion, the simultaneous diffusion of a migrant (Irganox 1076) and a solvent in low density polyethylene (LDPE) were measured. The migrant diffuses out of the polymer, while the solvent is diffusing inwards. For solvents with low molar mass the diffusion coefficient of Irganox 1076 increases with increasing solvent uptake. No increase in diffusion coefficient was found upon uptake of tri-glycerides such as olive oil. A method using microtoming and GC-analysis is tested for the measurement of migrant concentration profiles inside the polymer. The diffusion of Irganox 1076 and solvent in LDPE have been measured as a function of time. The Fick equation with a migrant diffusivity depending on the solvent concentration gives a good description of the results for isooctane and <em>n</em> -heptane. The description is less good for the measurements with cyclohexane (when the polymer swells strongly). The use of predictive modelling for legislative purposes is evaluated for a deterministic, a worst-case and a new stochastic approach. All approaches give a reasonable, but rough, estimation of the diffusion coefficient. The new stochastic approach has the advantage that an entire probability distribution may be obtained.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    • Wageningen University
    Supervisors/Advisors
    • Jongen, W.M.F., Promotor, External person
    • Wesselingh, J.A., Promotor, External person
    • Dekker, Matthijs, Promotor
    Award date12 Nov 2002
    Place of PublicationS.l.
    Print ISBNs9789058087379
    Publication statusPublished - 2002

    Keywords

    • packaging materials
    • food packaging
    • plastics
    • migration
    • diffusion
    • diffusion models
    • stochastic models
    • additives

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