Cooperative motions in PVC studied by thermally stimulated currents: Comparison with A.C. dielectric derivative analysis
✍ Scribed by Aurora Nogales; Bryan B. Sauer
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 179 KB
- Volume
- 36
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
The thermally stimulated current-thermal sampling (TSC-TS) technique was used to study the broadened glass transition in conventional ''atactic'' poly(vinyl chloride), PVC. The activated parameters obtained from the TSC-TS data, mainly the apparent activation energy (E a ), characterize the breadth of glass transitions in a very sensitive way. These results are compared with those values of E a obtained from the literature, using a recently proposed method of analyzing a.c. dielectric constants and their derivatives, over the temperature range of 0100-130ЊC. Both techniques detect weak cooperative glass transition-like relaxations well below the main glass transition of ca. 80ЊC. As is the case with ''atactic'' PMMA, the data suggest that compositional heterogeneity related to a small fraction of predominantly isotactic sequences contribute to the broad glass transition extending ca. 60ЊC below the main glass transition in atactic PVC.