Morphological changes in semicrystalline poly(ether ether ketone) and poly(ethylene terephthalate) during heating and structures of blends with poly(ether imide)
- Unviersite Catholoique de Louvain (Belgium)
- Almaden Research Center, San Jose, CA (United States)
Structural changes occurring during heating of cold crystallized PEEK and PET have been studied by real-time x-ray scattering using synchrotron radiation. Rapid melting/recrystallization is found when the semicrystalline PEEK and PET samples are heated above the previous highest annealing temperatures, Such melting/recrystallization results in irreversible increases in the lamellar long period, the crystal thickness and the density difference between the crystalline and amorphous regions. Throughout the entire temperature range up to the melting point, the linear crystallinity of lamellar stacks remains nearly constant around 0.3. The fact that both PEEK and PET form miscible blends with poly(ether imide) (PEI) in amorphous melts has been utilized to identify and to investigate the noncrystalline inter-lamellar region in the semicrystalline samples. For the semicrystalline blends of PEEK/PEI, both the small-angle x-ray scattering and dielectric loss measurements show that only a small amount of PEI is mixed in the inter-lamellar region. The majority of PEI, expelled from the lamellar stacks, is totally demixed from PEEK, demonstrating that the inter-lamellar region of semicrystalline PEEK is significantly different from the random amorphous melt. Therefore, the level of linear crystallinity and the miscibility characteristics indicate the presence of thick ordered interfacial layer on the lamellar surface, most likely due to the presence of rigid aromatic groups in PEEK and PET chains.
- OSTI ID:
- 126892
- Report Number(s):
- CONF-950402--
- Country of Publication:
- United States
- Language:
- English
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