Fluidification of concentrated aqueous colloidal silica suspensions by adsorption of low-molecular-weight poly(ethylene oxide)

This paper deals with the effect of different low-molecular-weight poly(eth ylene oxide)s on the rheology of concentrated aqueous colloidal silica susp ensions (volume fraction >0.2) with the aim of obtaining web-dispersed medi a. Results are correlated with the physico-chemical characteristics of the systems that govern the ranges of the various operating interactions, i.e., mainly surface coverage, molecular weight of the polymer, and ionic streng th of the medium. Optimization of the fluidification occurs to be strongly linked to these parameters. An unexpected effect of free polymer bulk conce ntration leads to improved fluidification when the characteristic lengths o f the system are correctly adjusted; it has been interpreted in the frame o f recent theories. (C) 2000 Academic Press.