Effect Of Temperature And CaCl₂on The Physical And Chemical Properties Of Sulfonate Anionic Polyelectrolyte Aqueous Solutions

Linear sulfonated polymers such as sodium polystyrene sulfonate (PSS) are a variety of strong water-soluble anionic polyelectrolytes with high charge density, good dispersion property in aqueous solution, without pH control and good surface and interfacial activities. They are widely used as stabilizers in suspension polymerization, slushing agents for concrete, oil well cement friction reducers, dispersants for coal-water slurries, and dispersants in pitch-water slurry, and also as surface modifiers of carbon nanotubes. Sulfonic acid type polymers are often used in oil and gas drilling, whose. dehydration and aggregation frequently brings about the difficulty of losing control of drilling fluid filtration at the elevated temperatures and salt concentrations. Besides, the influence of high temperatures on the Ca2+binding with these polymers was not clear.In this paper, we further investigated the change trend of Ca2+binding, molecular size and hydrophilicity of the two sulfonic acid type polymers before and after heating. In the experiment part, we studied two kinds of linear sulfonated polymers including sodium polystyrene sulfonate (PSS) and poly (2-Acrylamido-2-Methyl Propane Sulfonic Acid)(PAMPS). We used gel permeation chromatography, dynamic light scattering instruments, ion selective electrode method, infrared spectrophotometry, rheometry experiments, surface tension measurement and foam stability experiments to measure the effect of calcium concentration and high temperature on the physical and chemical properties of sulfonate anionic polyelectrolyte solutions. The results of experiments indicated that the change of dynamics size of the polymer molecules in aqueous solution under the conditions of high temperature and high salt is related to different molecular structures: the size of PSS molecular decreased significantly under the high-temperature and high-salt condition, however, under the same temperature the salt concentration has little effect on the size of PAMPS molecular because of intramolecule steric hindrance. Under the high-temperature and high-salt conditions, the apparent viscosity of polymer solutions decreased significantly. As temperature and calcium concentration increased, the hydrophilicity of the polymer PSS was reduced, causing the improvement of the surface activity of PSS molecules. However, the surface activity of the polymer PAMPS did not change significantly with the change of temperature and salt concentrations. When the PSS aqueous systems added CaCl2were heated and stored for one week, some woolly cloudlike aggregations formed in the systems, while for the PAMPS aqueous systems added CaCl2which have been heated and placed for a month, they were still clear and transparent.