Ravindrachary, V. and Sreepad, H. R. and Chandrashekara, A. and Ranganathaiah, C. and Gopal, S. (1992) Thermally induced microstructural changes in undoped and doped polyacrylonitrile- A positron-annihilation study. Physical Review B, 46 (18). pp. 11471-11478.
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Thermally induced microstructural changes in undoped and doped polyacrylonitrile.pdf Restricted to Registered users only Download (368kB) | Request a copy |
Abstract
Positron-lifetime measurements have been made in undoped and polymers 0.8 wt %-iodine-doped polyacrylonitrile (PAN) under annealing from room temperature to 160-degrees-C. From the measured lifetimes, the free-volume size is calculated following the treatment of Nakanishi, Jean, and collaborators. The variation in free-volume size as function of temperature seems to suggest molecular-chain-folding processes in amorphous regions of the polymer, positron trapping at kink-type defects, and at the interface between crystalline and amorphous regions at lower temperatures. This study indicates that in the undoped state, the polymer has a glass transition temperature at 90-degrees-C which is shifted toward lower temperature in the doped state by 30-degrees-C. The results also suggest the degradation of the polymer in the two states after 100-degrees-C and the effect of annealing is only on the size but not on the density of free-volume sites.
| Item Type: | Article |
|---|---|
| Subjects: | D Physical Science > Physics |
| Divisions: | Department of > Physics |
| Depositing User: | Users 23 not found. |
| Date Deposited: | 16 May 2021 05:32 |
| Last Modified: | 28 Oct 2022 05:27 |
| URI: | http://eprints.uni-mysore.ac.in/id/eprint/16413 |
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