Hydroxypropyl starch ethers (HPS) are nonionic etherified starches, a type of modified starch, produced by the etherification reaction of natural starch with propylene oxide under alkaline conditions. Their main types can be further subdivided according to the degree of substitution (DS), raw material source, and application:
Classification by Degree of Substitution (DS)
Low degree of substitution (DS < 0.1): Requires heating to dissolve, suitable for applications where water solubility is not critical.
Medium-high degree of substitution (DS 0.1~1.0): Soluble in cold water, with good water solubility, widely used in food, building materials, pharmaceuticals, and other fields.
Classification by Raw Material Source
Different plant starches can be used as the base material, such as:
Corn starch
Potato starch
Cassava starch
Wheat starch
Different raw materials affect the viscosity, gelatinization temperature, and stability of the final product.
Classification by Function and Composite Modification
Single Etherification Type: Introduces only hydroxypropyl groups, emphasizing water retention and thickening properties; commonly used in building mortars.
Composite Modification Type: Combines crosslinking, esterification, and other chemical treatments to improve acid resistance, heat resistance, or shear strength; suitable for food or oil drilling fluids.
Classification by Application Area
Industrial Grade HPS: Used in building materials, papermaking, textiles, etc., emphasizing thickening, anti-sagging, and film-forming properties.
Food Grade HPS: Complies with GB2760 standards; used as a thickener and stabilizer in ice cream, dairy products, etc., with high safety (ADI not limited).
Oilfield Grade HPS: Used in drilling fluids, possessing properties such as reducing fluid loss, stabilizing the wellbore, and resisting salt and calcium contamination.
