SYNTHESIS, CHARACTERIZATION, AND SOLUTION PROPERTIES OF HYDROPHOBICALLY-MODIFIED POLY(VINYL ALCOHOL)

A series of hydrophobically modified water-soluble poly(vinyl alcohol) (PVA) polymers was prepared by grafting urethanized PVA with varying fi actions of fatty acid chlorides of various chain lengths. The objec tive of the synthesis was to prepare polymers that can be applied to e nhanced oil recovery. The solution viscosity was investigated as a fun ction of polymer concentration, temperature, shear rate, and salinity. Furthermore, the surface and decane-water interfacial tensions were i nvestigated with respect to polymer and salt concentrations. Micelle f ormation was probed by measuring pyrene fluorescence as a function of polymer concentration. The solution viscosity was enhanced by the hydr ophobic modification, compared with the unmodified PVA as a result of hydrophobic association. The viscosity of a 3% polymer solution decrea sed with increasing salt concentration from 0.0 to 6.0 wt %, above whi ch some polymer precipitated from the solution. The solution viscosity decreased with both temperature and shear rate. Pyrene fluorescence m easurements showed that hydrophobic micelles formed above a polymer co ncentration of 0.5%. The micelle formation was relatively insensitive to salt concentration. The surface tension decreased sharply with incr easing polymer concentration to reach a minimum at a polymer concentra tion of 0.15% and then increased gradually up to a polymer concentrati on of 3%. Interfacial tension with n-decane showed a continuous decrea se with polymer concentration. (C) 1998 John Wiley & Sons, Inc.