Dispersion mechanisms of comb-type superplasticizers containing grafted poly(ethylene oxide) chains

This paper discusses the influence of graft chain length and dosage of con- lb-type superplasticizers on adsorption and dispersion mechanisms, and thei r subsequent effect on the fluidity of concentrated limestone suspensions. Contrary to the results obtained from interparticle potential calculations, the fluidity of concentrated suspension is improved by the use of comb-typ e polymers having shorter grafted chain length. The dispersion mechanism of comb-type polymers in a concentrated suspension is evaluated from the pers pective of molecular structure, the amount of adsorbed polymer, and the amo unt of entrapped water in the clusters of CaCO3 particles. Furthermore, the addition of certain soluble salts, which can effect the concentration of C a2+ in liquid phase of CaCO3 suspensions, has been observed to decrease the adsorption of comb-type polymers on CaCO3. Thus, the polymer adsorption pr ocess on solid surfaces can be selectively influenced by certain types of i ons.