The temperature dependence of the viscoelastic softening and terminal dispersions of linear amorphous polymers

Thermorheological simplicity is shown to hold for poly(vinyl acetate) in the temperature range extending from T g + 25°C to T g + 80°C. Between T g and T g + 25°C the softening (glass to rubberlike) viscoelastic dispersion exhibits time‐scale shift factors a T different from those of the terminal (r...

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Bibliographic Details
Published in:Journal of polymer science. Polymer physics edition 1982-04, Vol.20 (4), p.729-742
Main Author: Plazek, Donald J.
Format: Article
Language:English
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Summary:Thermorheological simplicity is shown to hold for poly(vinyl acetate) in the temperature range extending from T g + 25°C to T g + 80°C. Between T g and T g + 25°C the softening (glass to rubberlike) viscoelastic dispersion exhibits time‐scale shift factors a T different from those of the terminal (rubberlike to steady‐state) dispersion. The a T values calculated from zero‐shear viscosities coincide with those from the terminal dispersion in the temperature range 60–154°C ( T g ≅ 35°C). The a T shifts obtained from the response in the terminal dispersion can be fitted to the Williams, Landel, and Ferry equation over the entire temperature range 42–154°C. The a T obtained from the softening dispersion is shown to exhibit a different functionality. An empirical modification of the Doolittle equation yields a very flexible relation which can be fitted to some a T s which cannot be represented by the usual Doolittle free‐volume expression.
ISSN:0098-1273
1542-9385
DOI:10.1002/pol.1982.180200414