RHEOLOGICAL PROPERTIES OF SEMIDILUTE AQUEOUS-SOLUTIONS OF HYDROPHOBICALLY-MODIFIED PROPYLENE-GLYCOL ALGINATE DERIVATIVES

New hydrophobically associating water-soluble polymers have been prepa red by covalent fixation of dodecyl and tetradecyl hydrocarbon side ch ains onto propylene glycol alginate (PGA). The viscosity of aqueous so lutions of such derivatives is highly dependent not only on the shear rate but also on the shear time. The obtention of reliable data in thi s domain therefore requires that measurements are carefully carried ou t under steady state conditions. In the semi-dilute regime, intermolec ular hydrophobic associations can be evidenced at low shear rates. The se interactions result in considerably enhanced viscosities and the fo rmation of physically cross-linked gel-like structures may ultimately be observed.