SYNTHESIS AND CHARACTERIZATION OF SOME WATER-SOLUBLE POLYMERS

Homopolymers and copolymers of acrylamide (AA) and acrylic acid (AAc) were synthesized by the free radical solution polymerization technique . Feed ratios of the monomers were 85 : 15 (w/w), 65 : 35 (w/w), and 5 0 : 50 (w/w) of acrylamide and acrylic acid, respectively, for synthes is of copolymers. All reactions were carried out in aqueous media, exc ept for the synthesis of polyacrylic acid, where the medium was n-buta nol. Hydrogen peroxide, potassium persulfate, and benzoyl peroxide wer e used as initiators. The copolymers were purified by removing homopol ymers. The homopolymers and copolymers were characterized by infrared (IR), C-13-nuclear magnetic resonance (NMR), H-1-NMR, differential sca nning calorimetry (DSC), thermogravimetric analysis (TGA), and viscosi ty measurements. The fusion temperature and the energy change for vari ous phase transitions were obtained from DSC measurements. The activat ion energy values for various stages of decomposition were calculated from TGA. The activation parameters for the viscous flow (i.e., free e nergy, enthalpy, and entropy of activation) were evaluated from the vi scosity measurements. Voluminosity and Simha shape factor were also ca lculated for different systems. Effects of various concentrations of e lectrolytes, NaNO3, and Al(NO3)(3) on viscosity behavior were studied. (C) 1997 John Wiley & Sons, Inc.