The Synthesis and Isothermal Aging Behavior of Oxygen-Free Acetylene Terminated Quinoxalines
Final technical rept. Jan 1979-Dec 1980
AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH
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Acetylene-terminated resins prepared to date have contained phenyl ether groups, limiting their thermooxidative stability to 315 deg C, as determined by isothermal aging in air. In order to determine whether the thermooxidative stability of the acetylene cure site exceeds 315 deg C, a series of three acetylene- terminated quinoxaline isomer mixtures containing only aromatic and quinoxaline rings, known to have 371 deg C stability, were prepared and their isothermal aging behavior in air was studied at 315 deg C, 343 deg C, and 371 deg C. The thermooxidative stability of one system was comparable with that of an analogous acetylene terminated quinoxaline which contained phenyl ether linkages. The other two systems, which both contained ethynyl groups directly bonded to a quinoxaline ring, showed poorer thermooxidative stability than a phenyl ether containing system.