RHEOLOGICAL BEHAVIOR OF AQUEOUS SOLUTIONS OF COPOLYMERS OF ACRYLAMIDE-TYPE ANIONIC SURFACE-ACTIVE MONOMER AND ACRYLAMIDE
丙烯酰胺型阴离子表面活性单体与丙烯酰胺共聚物水溶液的流变特性

The homogeneous copolymerization of acrylamide (AM) and sodium 2-acrylamido-tetradecane sulfonate (NaAMC_ 14 S),which is a kind of acrylamide-type anionic surface-active monomer,was carried out in aqueous solutions.The concentrations of NaAMC_ 14 S were controlled above and below the critical micellar concentration (CMC),respectively,and the copolymers with two types of chain structures,random and microblocky were obtained.The structures of the copolymers were characterized by FTIR spectra,and their molecular weights were correspondingly expressed by the intrinsic viscosities obtained with an Ubbelohde viscometer.The hydrophobically associating properties of the copolymers and rheological characters of their aqueous solutions were studied mainly by using the fluorescence probe method and apparent viscosity measurements.The experimental results show that the copolymers with microblocky structure have strong hydrophobically associating properties,and the apparent viscosities of their aqueous solutions increase rapidly as their concentrations are over 0.2 wt%.The shear thinning behavior of their aqueous solutions is obviously reversible,and they exhibit strong shearing resistance.There is a special finding about a positive salinity sensitivity of the aqueous solution viscosity of the microblocky copolymers.For those copolymers with microblocky structure the apparent viscosity of their brine solution is much higher than that of their pure water solution.The apparent,viscosity of the salt solution is enhanced actually by three orders of magnitude as the concentration of the copolymer is 0.3 wt% and the concentration of CaCl_2 is 2 wt%,and a unique positive salt sensitivity,i.e.salinity thickening,is displayed.