Studies On The Interaction Of Guar Gum With Various Alcohols And Polyacrylamide With Different Degree Of Hydrolysis

Guar gum is a natural and environment-friendly non-ionic polysaccharide produced from the seeds of two annual leguminous plants, Cyamopsis tetragonalobus and psoraloides. The guar gum macromolecule is a chain of (1- 4)-linkedβ-D-mannopyranose units withα-D-galactopyranose units connected to the mannose backbone through (1-6) glycosidic linkages. The poly-mannose chain is randomly substituted with galactose units at a mannose–to–galactose ratio of 2. Guar gum containing many hydroxyl, because of these associations guar gum possesses remarkable water solubility and can be cross-linked , is widely used to control viscoelasticity in food, oil drilling, medicine, cosmetics, textile, mining, mineral processing. Because of the random nature of the substitution, the least substituted sections of the guar gum molecules show the greatest tendency to associate, consequently restricted the solubility and the efficiency of thickening. How to design and modify the chain of guar gum polymer, to improve its solubility and thickening efficiency has always been one of the issues of concern. In this paper, different alcohol and polyacrylamide dissolved in guar gum solution, looking forward to an increasement of solubility, thickening efficiency and scope by the introduction of alcohol molecules or polyacrylamide polymer. The experimental results obtained are as follows:1. Effect of both isopropyl alcohol and ethylene glycol upon the viscosity of guar gum in aqueous solution was measured. It has been found that with the addition of isopropyl alcohol into guar gum solution the intrinsic viscosity of solution decreases gradually whereas the Huggins parameter kH increases successively. On the other hand, by adding ethylene glycol into guar gum solution, the intrinsic viscosity of solution increases gradually whereas the Huggins parameter kH decreases successively. Our experimental results indicate that both isopropyl alcohol and ethylene glycol associate greatly with guar gum in solution. However, the effect of either isopropyl alcohol or ethylene glycol upon the hydrophobic property and steric hindrance of guar gum is different. As a result, the effect of either isopropyl alcohol or ethylene glycol upon the viscosity behavior of guar gum is different.2. Effect of different degree of hydrolysis of polyacrylamide upon the viscosity of guar gum in aqueous solution was measured. It has been found that the maximum viscosity at a guar gum–to-HPAM molar ratio of 1:1, and the ratio did not change with the degree of hydrolysis of HPAM change, in a certain range of shear rate, nor with the shear rate varies. This is because the two macromolecules entangled with each other, interact to form a similar ladder structure of interpenetrating networks. In this structure, as the shear Rate increasing, the hydrogen bonds between molecules dissociated rapidly and formed again, so the system can better maintain the high viscosity state.3. Applied the above experimental results to the practical research and development of high temperature fracturing fluid, by adding certain additives, have attained abundant experimental results and explore a high temperature-resistant fracturing fluid system: the viscosity can be maintained over the 80mPa?s under 200℃, after 2 hours of continuous 170s-1 shear.