| Autor: |
Tsvetkov, V. N., Shtennikova, I. N., Skazka, V. S., Rjumtsev, E. I. |
| Zdroj: |
Journal of Polymer Science Part C: Polymer Symposia; 1967, Vol. 16 Issue: 6 p3205-3217, 13p |
| Abstrakt: |
The flow and electric birefringence of a number of poly-?-benzyl-l-glutamate (PBLG) fractions in dichloroethane and m-cresol have been studied. Molecular weights (0.4–3.4 × 105) of the fractions are determined from measurements of diffusion and sedimentation of solutions. The hydrodynamic, optical, and electrical data obtained are used for quantitative evaluation of molecular conformation and flexibility. From the experimental dependence of molecular optical anisotropy on molecular weight, an apparent persistence length a= 1200 A. is calculated for the PBLG chain. This value is obtained by using both the intrinsic anisotropy of molecules and their microform anisotropy. A similar value, a= 1100 A., is also obtained from the dependence of diffusion and sedimentation coefficients on molecular weight. The value a= 700 A. determined from the dependence of dipole moment upon molecular weight appears to be considerably lower. This means that orientation processes of polar PBLG molecules in mechanical and electrical fields should not be considered identical and that a marked difference exists in the correlation of molecular chain segments with the phenomena of flow and electrical birefringence. |
| Databáze: |
Supplemental Index |
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