ISSN:
1435-1536
Schlagwort(e):
Key words Extremely dilute solutions
;
critical concentration c**
;
chain entanglements
;
solution shear rate
;
viscometry
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
Abstract When viscometry is used, a crossover phenomenon is observed separating the dilute solutions into extremely dilute solutions and dilute solutions. The critical concentration c **, determined from this crossover phenomenon, strongly depends on the shear rate in the solution. At very high values of shear rate the critical concentration c ** becomes very low and depends only on the contour length of the elongated chains of different polymers. An increase of the temperature induces an increase of c ** because the relaxation time of the chains decreases. If a polymer adopts a rodlike conformation (in a given solvent at a given temperature) the excluded volume of its chains increases and its critical concentration c ** decreases.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s003960050139
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