A Double-Modulation ESR Study of Internal Dynamics in the Glassy Polymer Matrix Detected by a Nitroxide Spin Probe
✍ Scribed by B Rakvin; Z Veksli
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 137 KB
- Volume
- 125
- Category
- Article
- ISSN
- 1090-7807
No coin nor oath required. For personal study only.
✦ Synopsis
The double-modulation ESR spin-probe technique was emmotion regime, the homogeneous linewidth (1/T 2 ) is larger ployed to study slow-motional dynamics in amorphous polymer than 1/T 1 , one can expect that the measurement of T 1 would matrices of polybutadiene, polyisobutylene, poly(methyl methacmake it possible to reach the smallest detectable local dyrylate), and paraffin. It was shown that the low-lying excitation namical effects (approximately the same order of magnitude levels of the polymer matrix, found in the range from 77 to 190 as 1/T 1 ) which can be detected in the vicinity of a probe K below the internal spin-probe transition, affect the effective by the ESR-probe method (4).
relaxation rate of a perdeuterated nitroxide probe. The interrela-
In some cases it is also convenient to study an apparent tionship between the effective relaxation rates and the local molecspin-lattice relaxation time T * 1 , where T * 1 £ T 1 (4), as an ular dynamics of side-chain groups attached to the polymer backalternative way of approaching the complex dynamical bebone was observed. Possible relaxation mechanisms are discussed within the electron-nuclear dipolar interaction. ᭧ 1997 Academic Press havior of a spin probe in the slow-motion region. This relaxation time is basically a T 1 slightly affected by some other dynamically sensitive relaxation process. For example, in the region near the rigid limit of the probe motion, one