Abstract
The dielectric relaxation characteristics of amorphous and semicrystalline poly(ether ether ketone) have been investigated as a function of crystallization history; both the glass-rubber (α) relaxation and a sub-glass (β) relaxation were examined. The characteristics of the α relaxation were highly sensitive to crystallinity owing to the constraint imposed on the amorphous phase dipoles by the presence of the crystalline phase. The magnitude of the α relaxation strength indicated an immobilized rigid amorphous phase fraction in the semicrystalline samples which appeared to relax at temperatures above Tg; finite rigid amorphous fractions were observed for both cold-crystallized and melt-crystallized specimens. The sub-glass (β) relaxation was also sensitive to the presence of crystallinity: the isochronal loss maxima measured for the cold-crystallized samples were offset to higher temperatures as compared to the wholly-amorphous material, and a disproportionate decrease in the β relaxation strength with the degree of crystallinity was observed. The influence of the crystalline phase on the β relaxation thus appears to extend well into the amorphous material, suggesting sub-glass motions which encompass a larger segmental length scale as compared to more flexible polymers.
Original language | English |
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Pages (from-to) | 4252-4261 |
Number of pages | 10 |
Journal | Macromolecules |
Volume | 26 |
Issue number | 16 |
DOIs | |
State | Published - 1993 |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry