Study on the rheological behavior of aqueous solutions of polyacryloylglycinamide.

Poly(N-acryloylglycinamide) (PNAGA) exhibits an upper critical solution temperature (UCST) behaviour in aqueous solutions, and unlike typical polymers, dissolution is more sensitive to temperature and solutions may exhibit an extraordinary rheological behavior. Homopolymers of NAGA with different molecular weights were synthesized, the rheological behavior of the polymer solutions was investigated, and the scaling relationships of the dilute solutions of polymers were analyzed. The results indicated that PNAGA is a thermoviscosifying polymer in aqueous solutions. Besides, the thermoviscosifying behaviour was intense above 50 °C, as well as at lower concentrations, and the viscosity rising up to 27.61 times at concentration of 0.1%. The lower molecular weight polymers prepared showed more thermoviscosification. The polymer solutions are thermoviscosified over the range of tested shear rates, exhibiting increased shear resistance. Light scattering tests showed that the molecular size increased with increasing temperature at the same concentration, combined with the scale relationship that the solution contact concentration decreased with increasing temperature, indicating polymer coil expansion with increasing temperature. [ABSTRACT FROM AUTHOR]