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Lower temperature curing thermoset polyimides utilizing a substituted norbornene endcapMethoxycarbonyl bridgehead substituted nadic diacid monomethyl ester, when used as an endcapping monomer, lowered the cure temperature of thermoset PMR polyimides without seriously affecting other desirable properties, such as glass transition temperature and thermal oxidative stability. The C-13 CP/MAS NMR of model compounds was used to follow the cure of resin systems using both the unmodified nadic endcap and the methoxycarbonyl-substituted endcap. Rheological analysis and differential scanning calorimetry DSC also provided evidence for the lower curing nature of the substituted endcap. Two regioisomers of the bridgehead-substituted endcap were isolated, and their chemical structures were elucidated by X-ray crystallography. The model compound and molecular modeling studies conducted ruled out the possibility of regioisomeric imide formation in the substituted endcaps.
Document ID
19930060529
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Waters, John F.
(NASA Lewis Research Center Cleveland, OH, United States)
Sukenik, Chaim N.
(NASA Lewis Research Center Cleveland, OH, United States)
Kennedy, Vance O.
(NASA Lewis Research Center Cleveland, OH, United States)
Livneh, Mordechai
(NASA Lewis Research Center Cleveland, OH, United States)
Youngs, Wiley J.
(Case Western Reserve Univ. Cleveland, OH, United States)
Sutter, James K.
(NASA Lewis Research Center Cleveland, OH, United States)
Meador, Mary A. B.
(NASA Lewis Research Center Cleveland, OH, United States)
Burke, Luke A.
(Rutgers Univ. Camden, NJ, United States)
Ahn, Myong K.
(Indiana State Univ. Terre Haute, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: Macromolecules
Volume: 25
Issue: 15
ISSN: 0024-9297
Subject Category
Nonmetallic Materials
Accession Number
93A44526
Distribution Limits
Public
Copyright
Other

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