| abstract |
A method for utilizing a purified exocellular polysaccharide, Zooglan, produced by Zoogloea ramigera, as a viscosity modifier, gellant, drag reducing agent, dispersant, flocculant, or emulsifying agent, wherein the properties of the polymer are dependent on, and can therefore be controlled by varying, the pH, the concentration of polymer, the ionic strength of the solution, and the processing parameters such as mechanical shear. The overall conformation of Zooglan, which is responsible for its functional properties, can be manipulated with pH and/or ionic strength of the solution. For example, the intrinsic viscosity of Zooglan (estimated m.w.=2x107) can vary from 16 to 170 dl/g in aqueous solution as a function of pH between 2-9 and salt concentration between 0 and 1M KCl. Zooglan is a polyelectrolyte above pH 2. The Zooglan chain is relatively stiff, with a stiffness parameter of 0.02. Zooglan solutions at a concentration above 0.01 g/dl are viscoelastic and pseudoplastic with thixotropic hysteresis and yield stress. The effects of shear rate and shearing time on the viscosity of Zooglan solutions are recoverable or non-recoverable based on solution conditions. Zooglan can form a gel or network by chain entanglement. This wide range of functional properties makes Zooglan an effective molecule for utilization in a variety of products such as pharmaceuticals, personal care and cosmetic products, food, paint and ink, textiles and paper products. |