Abstract: Ethoxylated ricinoleic acid methyl esters (ECAME-10) obtained directly from castor oil acid methyl esters by the use of a special homogeneous catalyst.The average ethylene oxide (EO) adduct number of ECAME-10 was determined by saponification value,gas chromatography (GC) and ¹HNMR.The hydrolysis resisting capacity of ECAME-10 was investigated under different pH value conditions.The appearance changes of ECAME-10 solution under different storing time periods was tracked and photographed and surface tension of different stages of the solution at different stages was measured.Results showed that the hydrolysis resisting capacity of ECAME-10 is rather strong.The hydrolysis rate of ECAME-10 is below 40% in pH value range of 4-9 after eight weeks.Surface tension of solutions can be kept stable after the hydrolysis reaction.

Key words: ethoxylated ricinoleic acid methyl esters, hydrolysis resisting capacity, surface tension