ISSN:
0022-3832
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The enormous increases in the viscosity, η, and the associated activation heat, Qη, in concentrated polymer solutions are attributed to two different factors. One is the formation of intermolecular linkages between high polymer molecules, and the other is the increase of glass transition temperature, Tg, with increasing concentration of the solution. In this paper, the effect of the increase of Tg in solutions of extremely high concentration is discussed. The apparent activation heat of viscosity, Qη, in this concentration range is represented by the equation, Qη = 2ΔE + Qη0. The first term is the increase of Qη due to the intermolecular linkages, and ΔE is the energy to form a linkage. The second term is the activation energy for the vitrified solution where intermolecular linkages do not exist, and it is represented by the equations, (Qηs/Qη2)1/2 = 1 - Aw2 and A = 1 - (Qηs/Qη0)1/2, where A is a constant for the solution and Qη2 and Qηs are the activation heats of viscosity for the polymer and the solution, respectively. The value of A remains constant up to 100% for polystyrene in dibenzyl ether, polymethyl methacrylate in diethyl phthalate, and polyvinyl chloride in tricresyl phosphate. The constant A is always very close to unity for polymeric solutions. The general tendency of concentration dependence of Qη in the whole range of concentration is discussed.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1959.1204013620
