ASPECTS OF CROSSLINKING SULFONATED POLYACRYLAMIDES FROM RHEOLOGICAL STUDIES ON THEIR GELS

摘要

Crosslinking of sulfonated polyacrylamide by zirconium requires some acrylate sites on polymer chain, and a schematic reaction is proposed to describe this process. Moreover, gelation kinetics is found to be fairly proportional to polymer acrylate site content. On the other hand, decreasing sulfonation level or solvent salt concentration is shown to result in increasing the system gelation, and an explanation of such behavior is attempted. Furthermore, we find that gelation kinetic is highly dependent on zirconium concentration in an unusual manner. So, for a given polymer sample, a maximum of zirconium concentration exists above which gelation kinetic decreases until it vanishes. This behavior is interpreted by existence of a background reaction where highly stable zirconium complexes are formed. This reaction indeed competes against the polymer cross-linking process and zirconium concentration increases. (C) 1997 John Wiley & Sons, Inc. [References: 17]