ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Viscosity and light-scattering measurements have been made on five samples of poly-N-tert-butylacrylamide in methanol, for which brief preparative details are given. Specific viscosities ηsp have been determined at 25°C. with two U-tube viscometers, No. 0 and No. 1, over a range of concentrations c. The mean flow gradients lie in the range 360-750 sec.-1 for No. 0 and 535-940 sec.-1 for No. 1. Graphs of ηsp/C against c are linear for concentrations between 0.18 and 1.0 g./dl. at all gradients less than about 640 sec.-1 with samples having weight-average molecular weights of 24.5, 5.46, 4.04, 3.79, and 1.65 × 105. At lower concentrations, which give correspondingly higher gradients, the linear relation ceases. Possible reasons for this are suggested. By extrapolation of the linear portions of the appropriate curves to zero concentration, apparent limiting viscosity numbers \documentclass{article}\pagestyle{empty}\begin{document}$[\eta ]_{\begin{array}{*{20}c} {c = 0} \\ {G = 760} \\ \end{array}} $\end{document} have been obtained, where the value G = 760 sec.-1 is the gradient for pure methanol. Light-scattering data have been employed to obtain the molecular weights of the samples using the Zimm technique. Depolarization ratios, determined for different concentrations at wavelengths 4358 and 5461 A. and extrapolated to zero concentration, were negligible. The constants k1 and α in the expression \documentclass{article}\pagestyle{empty}\begin{document}$[\eta ]_{\begin{array}{*{20}c} {c = 0} \\ {G = 760} \\ \end{array}} $\end{document} =k1Mwα have the values 8.87 ± 0.44 × 10-4 and 0.525 ± 0.026, respectively.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1964.100020819
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