RHEOLOGY AND PHASE-BEHAVIOR OF THE SYSTEM PBZT-PHOSPHORIC-ACID-WATER

Citation
H. Fischer et al., RHEOLOGY AND PHASE-BEHAVIOR OF THE SYSTEM PBZT-PHOSPHORIC-ACID-WATER, Journal of macromolecular science. Physics, B37(4), 1998, pp. 401-409
Citations number
11
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Polymer Sciences
ISSN journal
0022-2348
Volume
B37
Issue
4
Year of publication
1998
Pages
401 - 409
Database
ISI
SICI code
0022-2348(1998)B37:4<401:RAPOTS>2.0.ZU;2-3
Abstract
Solutions of poly-p-phenylenebisbenzthiazole (PBZT) in phosphorous aci d were examined in a rheogoniometer for shear response and relaxation as a function of concentration and temperature based on knowledge of t he phase diagram of the system. It was found that the various regions of the phase diagram (i.e., the isotropic, the nematic, and the biphas ic regions) and the various kinds of crystal solvates were reflected b y their rheological behavior. This shows that rheological properties c an be used to map, at least, the broad features of phase diagrams; con versely, the knowledge of the phase diagram is a prerequisite for the appreciation of rheological behavior. At the same time, the stress inv olved in the rheological tests themselves can modify, to a lesser exte nt, the positions of the phase dividing lines compared to those in the static system, which at appropriate points in the phase space can lea d to stress-induced phase transitions. The principal rheological effec t, here used diagnostically, is in itself novel; it is a spontaneous s tress buildup in the stationary state of the rheometer after the stres ses generated by the preceding shearing have decayed following stoppag e of the rotor. The effect itself will be followed up in a separate st udy.