Abstract
Modified starches such as hydroxyethyl, acethyl, hydrophobically-modified ester, and oxidized starches were widely used in papermaking industries as a surface strength agents or binders of coating color pigment. However, the molecular conformation of these modified starches in aqueous solutions were not fully understood. The purpose of this study is to investigate the molecular conformation of modified starches, which helps ideal chemical modification designs for a certain papermaking process.
Investigations based on size exclusion chromatography (SEC) and multi-angle laser light scattering (MALS) were conducted to assess the influence of chemical modifications and degrees of substitution (DS), molecular mass, and the solubilization methods on the macromolecular features in aqueous solutions of the modified starches for papermaking. SEC-MALS analysis revealed that the increasing the DS value of hydrophilic groups, decrease in the molecular mass by acid treatment or oxidation, and alkaline dissolution made the modified starch macromolecules more expanded conformations in aqueous solution.
