HPS(Hydroxy Propyl Starch Ether)Hydroxy Propyl starch ether is a chemically modified starch is made of propylene oxide and starch etherized, replacing the hydroxyl group in the starch polymer structure, become etherized starch, its physical properties are white (colorless) powder, with good fluidity and good water solubility can impart unique properties to cement and gypsum based products.