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Sedimentation velocity of polymer solutions—II. Pressure dependence of the sedimentation coefficient

✍ Scribed by W.J. Closs; B.R. Jennings; H.G. Jerrard

Publisher
Elsevier Science
Year
1968
Tongue
English
Weight
456 KB
Volume
4
Category
Article
ISSN
0014-3057

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✦ Synopsis

The dependence of the sedimentation coefficient upon the hydrostatic pressure in the solution has been studied in the three polymer-solvent systems: (I) polymethylmethacrylate in n-butyl chloride at 35 °, (H) polystyrene in cyclohexane at 34 ° and (m) polyisobutylene in cyclohexane at 34 °, The first two are 0-systems. Analysis of the experimental data in terms of the Fujita equation yielded values for the pressure dependence parameter m. The pressure dependence coefficient (~) was obtained from the equation m/ro 2 ----(0"5) pt.#.,o2 where pt is the solute density at atmospheric pressure, ro the distance between the axis of rotation and solution meniscus and oJ the angular velocity of the rotor. For the three systems, ~, depended upon oa and for system (I), upon the solute concentration, although allowance had been made for the concentration dependence of the sedimentation coefficient. The reason for this may lie in the polydispersity of the solute or incorrect assumptions implicit in the Fujita equation or its application to these systems.

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