- Author
-
Yermolenko, I. N.
|
Sviridova, R. N.
- Title
- About the Forming of the Structure of Pyrolytic Carbonic Fibers.
- Coporate
- Air Force Systems Command, Wright-Patterson AFB, OH
- Report
-
FTD-MT-24-79-71
1969
11 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
carbon
|
fibers
|
rayon
|
pyrolysis
|
temperature rise
- Abstract
- Rayon fibers were oxidized with N oxides to poly(anhydrouronic acids) which were converted to the A1 salts. The pyrolysis of fibers contg. 11.5 percent COOH groups was carried out in a vacuum up to 850 degrees by raising the temp. at a 4 degrees min. rate. Higher yields of carbon fibers with higher ragidity were obtained from rayons contg. higher proportion of the COOH groups. Oxidn. to 50 percent gave optimal properties and yields. The pyrolysis temp. strength relation showed a min. strength at 200 degrees and a substantial increase in the strength at 800-850 degrees. Gas adsorption and the IR study demonstrated that the carbon fibers represented a highly packed structure of oriented molecules. Preoxidn. and Alsalts enhanced the formation of oriented structures. Slower rate of tem. raise during the pyrolysis or longer heating at 800 degrees, as well as drawing the fibers during the pyrolysis, increses the mech. strength of the carbon fibers.