Anomalous Diffusion of a Penetrant in a Viscoelastic Polymer: Modelling and Testing

Abstract

It is now well known that Fick's Law is frequently inadequate for describing penetrant diffusion in polymers or polymer composites. Non-Fickian or anomalous diffusion typically occurs when the rates of diffusion and viscoelastic relaxation in a polymer are comparable, and the ambient temperature is below the glass transition temperature (Tg) of the polymer. As a result, it is necessary to take into account the time-dependent response of a polymer, analogous to viscoelastic relaxation of mechanical properties, in constructing such a model. In this paper, a simple yet robust methodology is proposed that would allow characterization of non-Fickian diffusion coefficients from penetrant weight gain data for a polymer below its Tg. Reduced absorption plots are used to verify the thickness independence of the diffusivity data. Subsequently, these diffusion coefficients are used for predicting penetrant concentration profiles through the thickness of a polymer. Penetrant weight gain data at different temperatures for an epoxy and a urethane adhesive specimen is employed to test the model.

Department(s)

Computer Science

International Standard Serial Number (ISSN)

0967-3911

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2024 The Authors, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Publication Date

01 Jan 2000

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