Phase separation and gelation of the aqueous solutions of acrylamide-acrylic acid copolymers in the presence of aluminium chloride are studied as a function of pH and ionic strength. At pH 7, only phase separation is observed as a flocculation of aluminium hydroxide particles by polymer bridges, but because of their small positive residual charge the phenomenon is partially due to electrostatic interactions and consequently depends on the ionic strength of the solution. At pH 5, gelation attributed to the presence of polycations A13~ - occurs for values of the polymer charge which increase with increasing ionic strength. A qualitative model is proposed to define the conditions and the limits of gelation in such systems.
Посилання на статтю:
Interactions between aluminium ions and acrylic acid-acrylamide copolymers in aqueous solution: 3. Influence of ionic strength on gelation and phase separation / Ramine Rahbari and Jeanne Francois* // Polymer. – 1992. – Vol 33. – P. 1449-1458.