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PETIs as High-Temperature Resin-Transfer-Molding MaterialsCompositions of, and processes for fabricating, high-temperature composite materials from phenylethynyl-terminated imide (PETI) oligomers by resin-transfer molding (RTM) and resin infusion have been developed. Composites having a combination of excellent mechanical properties and long-term high-temperature stability have been readily fabricated. These materials are particularly useful for the fabrication of high-temperature structures for jet-engine components, structural components on highspeed aircraft, spacecraft, and missiles. Phenylethynyl-terminated amide acid oligomers that are precursors of PETI oligomers are easily made through the reaction of a mixture of aromatic diamines with aromatic dianhydrides at high stoichiometric offsets and 4-phenylethynylphthalic anhydride (PEPA) as an end-capper in a polar solvent such as N-methylpyrrolidinone (NMP). These oligomers are subsequently cyclodehydrated -- for example, by heating the solution in the presence of toluene to remove the water by azeotropic distillation to form low-molecular-weight imide oligomers. More precisely, what is obtained is a mixture of PETI oligomeric species, spanning a range of molecular weights, that exhibits a stable melt viscosity of less than approximately 60 poise (and generally less than 10 poise) at a temperature below 300 deg C. After curing of the oligomers at a temperature of 371 deg C, the resulting polymer can have a glass-transition temperature (Tg) as high as 375 C, the exact value depending on the compositions.
Document ID
20110015122
Acquisition Source
Langley Research Center
Document Type
Other - NASA Tech Brief
External Source(s)
http://www.techbriefs.com/component/content/255?task=view
Authors
Connell, John N. (NASA Langley Research Center Hampton, VA, United States)
Smith, Joseph G., Jr. (NASA Langley Research Center Hampton, VA, United States)
Hergenrother, Paul M. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
August 25, 2013
Publication Date
September 1, 2005
Publication Information
Publication: NASA Tech Briefs, September 2005
Subject Category
Composite Materials
Report/Patent Number
LAR-15834-1
Distribution Limits
Public
Copyright
Public Use Permitted.

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IDRelationTitle20110015102Collected WorksNASA Tech Briefs, September 2005
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