Studies of the Initial Stages of the Degradation of Polymeric Precursors Used in the Preparation of Carbon/Graphite Fibers.
Abstract
The thermal degradation of Polyacrylonitrile (PAN) copolymers as a function of composition and temperature under reduced pressure and in air has been studied by Fourier transform infrared spectroscopy. Three PAN copolymers containing varying concentrations of the comonomers acrylamide (AM), Acrylic acid (AA) and itaconic acid (IA) have been examined. The results obtained for the copolymers containing AM units, degraded under reduced pressure are somewhat surprising and indicate that above a certain threshold of comonomer concentration the fraction of available nitrile groups that undergo reaction is limited and falls within a remarkably narrow range. From a consideration of the copolymer and stereochemical sequence distribution, the stereochemistry of ring formation and intermolecular crosslinking, a step ladder model for the degraded product may be applicable. Additionally, it is concluded that the distribution of tactic placements in the copolymer chains is indeed a factor limiting the degree of cyclization of the available nitrile groups. A computer program has been developed for calculating the extent of reaction of the acrylonitrile units based upon the above model and the results are in good agreement with the experimental observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 15, 1982
- Accession Number
- ADA121021
Entities
People
- George T. Sivy
Organizations
- Pennsylvania State University