Title: Influence of the Hydroxypropylation of Starch on its Performance as Viscosity Modifying Agent

Author(s): Kun Zhang, Wolfram Schmidt, Alexander Mezhov

Publication: Symposium Paper

Volume: 354

Issue:

Appears on pages(s): 209-218

Keywords: potato starch, rheological, cement hydration, pore solutions

DOI: 10.14359/51736074

Date: 7/1/2022

Abstract:
Starch is a commonly used viscosity modifying agent (VMA). The performance of starch as VMA depends on its origin (e.g. potato, corn, cassava, etc.) and corresponding molecular properties, such as molecular weight, the ratio between amylose and amylopectin, etc. Depending upon the application, the efficiency of starch can be enhanced by hydroxypropylation. The maximum degree of substitution (DoS) cannot be greater than 3.0, which is the number of hydroxy groups per glucose monomer in the polymer. In the current research three potato starches exhibiting the DoS of 0.4, 0.6, and 0.8 were used. The influence of the modified starch on the rheological properties and hydration of cement paste, as well as the viscosity of the pore solution, were investigated. Our findings show that the starch with the highest DoS increases the dynamic yield stress the most, while the plastic viscosity is less dependent on the DoS. Additionally, starch with the highest DoS retards hydration to a lower degree than other starches.