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Effects of NaCl on steady rheological behaviour in aqueous solutions of hydrophobically modified polyacrylamide and its partially hydrolyzed analogues prepared by post‐modification
Author(s) -
Feng Yujun,
Grassl Bruno,
Billon Laurent,
Khoukh Abdel,
François Jeanne
Publication year - 2002
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.959
Subject(s) - thixotropy , dilatant , rheology , polyacrylamide , aqueous solution , hydrolysis , ionic strength , apparent viscosity , shear thinning , viscosity , chemical engineering , shear rate , thickening agent , chemistry , polymer , polymer chemistry , materials science , composite material , organic chemistry , thickening , polymer science , engineering
The influences of NaCl on the steady rheological behaviour of aqueous solution were investigated for a hydrophobically modified polyacrylamide (HMPAM) and its hydrolyzed derivatives (HHMPAM) prepared by post‐modification. The apparent viscosity (η app ) and reduced viscosity (η red ) were measured as a function of NaCl content. As salinity increased, η red decreased for both HMPAM and HHMPAM in dilute regime; in the semidilute solution, a continuous increase of η red was observed for HMPAM while η red passed through a minimum in the case of HHMPAM. At a given polymer concentration in semidilute regime, both shear thickening and anti‐thixotropic properties were observed as a function of salinity and hydrolysis degree, as well as ageing time. Dilatancy was observed over a range of shear rates beyond which solutions behaved as classical polymer systems. When salinity exceeded a critical value, dilatancy and anti‐thixotropy appeared as increasing functions of ionic strength and decreasing functions of hydrolysis degree. Prolongation of ageing time strongly enhanced both shear thickening and anti‐thixotropic behaviors. These results are interpreted by the changes of the relative numbers of intra‐ and intermolecular associations, and the participation of free hydrophobes in the formation of clusters under shear. © 2002 Society of Chemical Industry