Effects of dispersed medium systems on substitution pattern and solution performance of carboxymethyl cellulose

Abstract

Effects of three dispersed medium systems consisting of isopropyl alcohol (IPA), ethyl alcohol (EtOH) and toluene (TOL) on the substitution patterns of carboxymethyl cellulose (CMC) were studied, and the corresponding influences on solution performances were investigated on a rheometer. In EtOH-IPA system, the structure of higher average substitution degree and enlarged partial substitution degrees disparity (determined by ¹H nuclear magnetic resonance) but lower distribution uniformity along molecular chains (speculated from static/dynamic light scattering) were characterized by which the thixotropy and apparent viscosity of solution decreased due to the aggregation of longer unsubstituted segments. For the phase separation (identified by gas chromatography) of TOL-IPA system, considerable unsubstituted regions in the structure aggregated into hydrophobic centers to form swollen macrogel particles in solution, leading to the sharp rise in apparent viscosity and almost constant flow-behavior index with hardly any thixotropic behaviors presented.

Keywords

degree of substitution / alkalization / substitution uniformity / molecular interaction / aggregation