Study On The Regenerative Gel Of Low Molecular Weight Carboxymethyl Guar Gum And Rheological Properties

In this paper, carboxymethyl guar gum (CMG) and low molecular weight carboxymethyl guar gum (LMWCMG) were synthesized from guar gum splits. The formation and regeneration process of stable gel systems consisting of LMWCMG and borax were studied. Effects of LMWCMG and borate concentration on the gel systems were also investigated. Furthermore, the rheological properties of CMG solutions and the regenerative gel systems were studied. The main conclusions were obtained as follows:1) The carboxymethylation of guar gum splits was studied. The effects of reaction temperature, reaction time, dosage of CTAC, NaOH and carboxymethylation reagent (CA) on the apparent viscosity, carboxymethyl degree of substitution and substances not dissolved in water of CMG were disscussed. The proper process condition was obtained as follows:10.0 g guar gum splits and 0.3 g CTAC react with 3.0 g NaOH for 45 minutes at 25℃, then reacts with 4.0 g carboxymethylation reagent for 120 minutes at 85℃.2) The rheological properties of CMG solutions show that the apparent viscosity of CMG solutions increases with increasing concentration and decreases with increasing temperature and added sodium chloride. The CMG solutions behave as shear-thinning fluid and possess good thixotropy and visco-elasticity.3) The degradation process condition of LMWCMG by hydrogen peroxide (H2O2) was obtained. The stable gel systems consisting of LMWCMG and borax were obtained, the gel breaking and regeneration process were realized by control of pH value. The stable gel systems were proved as regenerative gel systems.4) The rheological studies show that the stable gel systems before and after regeneration possess good visco-elasticity and thixotropy, and shear thinning property. Non-linear co-rotational Jeffreys model can be applied to describe the viscosity curves of the gel systems correctly, and the calculated values are in good agreement with the experimental data.The study of this paper could provide the reological base for the further application of clean regenerative low molecular weight anion guar gum gel system in enhanced oil recovery.