Macromolecular interactions and synergy in xanthan/HPAM aqueous solutions
It is known that the rheological properties of a polymer solution are strongly dependent on the polymer structure, composition, conformation and interactions between the polymer and the solvent. Indeed, the macromolecular interactions change the polymer conformation which can result in an improvement of rheological behavior. Herein, the synergy and interactions between hydrolyzed polyacrylamide (HPAM) and xanthan were explored by rheology experiments and dynamic light scattering. The results indicated that hydrogen bonding interactions occur between the HPAM and xanthan existing in saline solution. It was showed that negative or positive synergistic effects occurred when the proportions of partially hydrolyzed polyacrylamide and xanthan were changed and the maximum positive synergy occurred when the content of xanthan was ca. 80% for the present experimental conditions. In addition, the synergy of mixed solution was markedly influenced by temperature and the HPAM molecular weight and mineralization degree. The two types of synergistic effects tended to recede with increasing shear rate in the rheological experiments. It is noted the calculation of relaxation time (t) for the mixed solutions also demonstrated an interaction between the HPAM and xanthan in aqueous solutions.