Determination of Glass Transition Temperature at Specific Sites in Polymers by Microwave Power Saturation in Electron Spin Resonance. (English)
In: Kobunshi Ronbunshu, Jg. 69 (2012-07-01), Heft 7, S. 366-372
academicJournal
Zugriff:
We report a novel method for determination of glass transition temperatures that applies the phenomenon of microwave power saturation in electron spin resonance (ESR). Amorphous polystyrene (PS) and semi-crystalline polyethylene (PE) were used as samples for the measurement. In order to evaluate the glass transition temperature (T g ) at the specific sites in the polymers, we spin-labeled the end or inner segments in PS and inner segments in PE with paramagnetic species. When the microwave power is small enough, the intensity of ESR spectrum is proportional to the square root of the magnitude of the microwave power. However, the intensity of the spectrum no longer increases when an excess power is applied. This is the power saturation phenomenon which is influenced by the relaxation time of the molecular mobility around the spin labels. No significant difference in T g of PS between end and inner segments was revealed by the ESR microwave power saturation method. This can be explained by in terms of cooperation in the segmental motion at the T g . As for PE, it was found that T g in the amorphous region of PE depended on the crystallinity. [ABSTRACT FROM AUTHOR]
Copyright of Kobunshi Ronbunshu is the property of Society of Polymer Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Titel: |
Determination of Glass Transition Temperature at Specific Sites in Polymers by Microwave Power Saturation in Electron Spin Resonance. (English)
|
---|---|
Autor/in / Beteiligte Person: | Yamamoto, Katsuhiro ; Miwa, Yohei |
Zeitschrift: | Kobunshi Ronbunshu, Jg. 69 (2012-07-01), Heft 7, S. 366-372 |
Veröffentlichung: | 2012 |
Medientyp: | academicJournal |
ISSN: | 0386-2186 (print) |
DOI: | 10.1295/koron.69.366 |
Schlagwort: |
|
Sonstiges: |
|