Synthesis And Dispersing Performance Of Anion Starch

In this paper, sulfonic-carboxymethyl starch (S-CMS) and sulfonic-starch succinate half ester (S-SSHE) were designed and synthesized based on the investigation relationship between molecular structure and performance (including viscosity, water-holding and dispersing capacity) of carboxymethyl starch (CMS), starch sulfonate (SS) and starch succinate half ester (SSHE). They were prepared by multiple-modified process and expected to have superior dispersing ability. The dispersing mechanism of CMS, SS and SSHE used as dispersants of cement was discussed, which contributed to the theoretical research level of cement dispersant of our country.CMS with high DS (0.1～0.7) was synthesized by solvent method. The study of viscosity proformance and water-holding capacity indicated that shear resistant,storing stability and water-holding capacity of CMS increased with the increase of crosslinkage, but crosslinkage had little effect on salt resistance and acid and alkali stability. All performances of CMS increased as DS increased. The CMS with low viscosity was used as cement dispersant, and the relationship between molecular structure and dispersing ability was investigated. The degradation degree and DS of the obtained CMS with best dispersing capacity were determined tO be 2M and 0.50.SSHE with high DS(0.1～0.6) was prepared by dry method. The experimental results indicated that the viscosities of all the products were lower than 100 mPa·s. Based on its low viscosity characteristic, SSHE was developed to be cement dispersant, and the DS of the product with the best dispersing capacity were measured to be 0.51.SS with high DS(0.1～0.9) was prepared with chlorosulfonic acid as sulfonated reagent. The viscosity and water-holding capacity of SS with high viscosity were investigated, the results showed that shear resistance and water holding capacity increased with the increase of crosslinkage and DS. In addition, SS presented storing stability, acid and alkali stability but poor salt resistance. SS with low viscosity (< 15mPa·s) was used as cement dispersant, and the degradation degree and DS of the produced SS with the best dispersing ability was 2M and 0.50, respectively.The novel molecular structures of S-CMS and S-SSHE were designed and synthesized by multiple-modified method. The dispersing ability of S-CMS and S-SSHE was compared with corresponding dual-modified starches and their complex. The results showed that S-SSHE (DS≈0.2) had superior dispersing capacity with low DS. The application and adsorption characteristics of CMS and SS were investigated in comparison with traditional naphthalene sulfonated formaldehyde condensates (FDN) whose dispersing ability mainly depended on electrostatic repulsive force. The results indicated that the dispersing ability of CMS and SS mainly came from steric hindrance effect, but their adsorption conformations were quite different. The dispersing ability of SSHE as cement dispersant also came from steric hindrance effect and long side chain contributed to steric hindrance in a certain degree.