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Keywords:

  • adsorption;
  • thermogravimetric analysis (TGA);
  • polyelectrolytes;
  • clay

Abstract

The adsorption behavior of poly(diallyldimethylammonium chloride) (PDADMAC) and of a copolymer with acrylamide on a native clay was studied as a function of the molecular weight of homopolymers, the ionic strength of the medium, and the ionic nature of the constituent blocks of the polymers. The clay was used without further purification or treatment in order to simulate a borehole environment. The properties of the clay–polymer systems studied were evaluated through total organic carbon analysis, thermogravimetric analysis (TGA), and X-ray diffraction analysis. The adsorption isotherms showed that all cationic polymers had high affinity for the clay, even in a highly saline medium and that the amount of polymer adsorbed strictly depended on the length of the macromolecular chain. The TGA results showed that polymer adsorption was able to reduce the water content of the clay surfaces, independently of the molecular weight of the homopolymer. The inhibitive properties of the polycations were measured by conventional oilfield cuttings rolling tests, which showed that these polymers were able to reduce the dispersion and disintegration of the clay cuttings. The results also showed that inhibition was directly related to the clay–polymer interactions and, therefore, to the polymer structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2158–2163, 2006.