ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The storage and loss shear moduli, G, and G˝, have been measured for solutions of three samples of poly-γ-benzyl-L-glutamate with molecular weights from 16 to 57 × 104, by use of the Birnboim-Schrag multiple-lumped resonator. The frequency range was 106 to 6060 Hz, the concentration range 0.0015-0.005 g/ml, and the temperature 25°C. Two helicogenic solvents with widely different viscosities, dimethylformamide and m-cresol, were used to provide a broader effective frequency range. The intrinsic moduli, extrapolated to infinite dilution, were compared with the predictions of the theory of Ullman for rigid rods; agreement was rather good at the lowest frequencies, but unsatisfactory at high frequencies. The data over the entire frequency range of three of logarithmic decades could be described closely by a relaxation spectrum consisting of one terminal relaxation time separated by a gap from a sequence of relaxtion times spaced as in the Zimm theory. The terminal time agrees approximately with that calculated for end-over-end rotation of a rigid rod. The additional relaxation mechanisms are tentatively attributed to modes of flexural deformation of the helix.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.1973.360120816
