7-hydroxynadic acid: A new end cap for improved oxidation resistance in addition polyimides

Citation
Mab. Meador et al., 7-hydroxynadic acid: A new end cap for improved oxidation resistance in addition polyimides, CHEM MATER, 13(8), 2001, pp. 2649-2655
Citations number
37
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
CHEMISTRY OF MATERIALS
ISSN journal
08974756 → ACNP
Volume
13
Issue
8
Year of publication
2001
Pages
2649 - 2655
Database
ISI
SICI code
0897-4756(200108)13:8<2649:7AANEC>2.0.ZU;2-L
Abstract
We consider possible replacements for the norbornenyl end cap in addition p olyimides that should favor bridge degradation and lead to lower weight los s in the resin system. Our preliminary evaluation demonstrates that molding powder made with 7-hydroxynorbornene-2,3-dicarboxylic acid, 17, as the end cap can be fully imidized at 200 degreesC. By differential scanning calori metry (DSC), onset of cross-linking occurs approximately 50 degreesC lower than that for the unsubstituted end cap. The hydroxy-bearing carbon on 17 i s more easily oxidized to carbonyl on aging in the polymer than the parent end cap. Therefore, the new end cap more highly favors bridge degradation. However, processing studies, long-term weight loss, and careful evaluation of degradation mechanisms must be carried out to fully assess 17 as a more thermo-oxidatively stable replacement for the parent norbornenyl end cap.