ISSN:
0449-2951
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The second Newtonian viscosities η2 of solutions of polystyrene and polyisobutylene were determined in a coaxial cylinder viscometer at shear rates near 105 sec.-1. The second Newtonian viscosity numbers (η2 - ηs)/ηsc, where ηs is solvent viscosity and c is polymer concentration, were determined as a function of concentration. For polymer species of viscosity-average molecular weight \documentclass{article}\pagestyle{empty}\begin{document}$\overline M _v {\rm less than }1 \times 10^6 , {\rm }\mathop {\lim }\limits_{c \to 0} (\eta _2 - \eta _ {\rm s} )/\eta _ {\rm s} c$\end{document} appears almost identical to intrinsic viscosity [η]. Above M̄v ⋍ 1 × 106, a plateau of constant (η2 - η2)/ηsc is found when this function is plotted against c. For good solvents the plateau value: {(η2 - ηs)/ηsc}p lies below [η], but in poor solvents (near the θ temperature) the opposite is true. Correlation of plateau values vs. M̄v can be achieved in the manner of the Mark-Houwink equation: [η] = K′M̄va, by writing: {(η2 - ηs)/ηsc}p = K″M̄vb. The sum of a + b of any species in two given solvents is approximately unity. Though the data are inconclusive, it appears that even above M̄v ⋍ 1 × 106, the second Newtonian viscosity number tends to approach [η] as c approaches zero.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1963.100010411
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