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Methyl‐hydroxypropyl cellulose ‐ shear induced birefringence measurements in the semi–dilute regime
Author(s) -
Schmidt Jürgen,
Weigel Richard,
Burchard Walther,
Richtering Walter
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971200125
Subject(s) - birefringence , rheometer , materials science , flow birefringence , anisotropy , micelle , rheology , shear (geology) , composite material , core (optical fiber) , optics , relaxation (psychology) , shear flow , chemical physics , aqueous solution , mechanics , chemistry , physics , organic chemistry , psychology , social psychology
The present study was induced by unexpected findings with this and other not fully substituted cellulose derivatives. Although fully transparent aqueous solutions were prepared, static light scattering (LS) revealed a strong aggregation. A detailed analysis of the LS‐data as well as transmission electron‐microscope pictures gave evidence for fringed micelles as aggregate structure. These particles consist of several side‐by‐side aligned chains that form a compact core from which many dangling chains emerge. The core in this model has a geometrical anisotropic shape and flow birefringence became detectable when orienting the particles by the action of shear forces. Induced flow birefringence is a common feature of many other materials and therefore a set‐up was constructed that could be attached to a common constant stress rheometer of Bohlin. The reported experiments present first examples measured with this set‐up and demonstrate the efficiency of this technique. In the following the equipment is briefly described and the results obtained so far are tentatively interpreted.