Synthesis and performance evaluation of composite modified starch
Crosslingking carboxymethl compound starch( CCMS) with high viscosity is prepared by using potato starch as material,epichlorohydrin as crosslinking reagent,monochloroacetic acid as etherifying reagent. The solvent method and pre-acid method are used in synthesis of CCMS. The optimum reaction formula and processing parameter are obtained. The results show that when the mole ratio of starch,monochloroacetic acid to sodium hydroxide is 1 ∶ 0. 57 ∶ 1. 01,mass fraction of crosslinking agent on the basis of the mass of starch is 0. 67%,ethanol concentration is 90. 0%,reaction temperature is 65 ℃ and reaction time is 70 min,the CCMS has better performance and higher shear viscosity. The CCMS can enhance viscosity,reducing filtration,resisting high temperature and salt in each drilling fluid. In each drilling fluid disposed by high temperature,the product's capability of reducing filtration is also excellent.