Abstract:The hydrolytic stability of synthetic ester is poor due to the presence of ester bond in the molecular structure,which is highly susceptible to hydrolysis.To study the process of hydrolysis of synthetic ester,the experiments of hydrolytic stability was carried out in a high pressure autoclave according to the standard of SH/T 03011993 for selected five kinds of synthetic ester base oils.The effects on the hydrolytic stability of synthetic ester were researched by the molecule structure of synthetic ester,hydrolytic time,hydrolytic temperature and water contents,and etc.The results show that the synthetic ester with lower initial acid value and stronger steric hindrance is exhibited of a better hydrolytic stability,and the effect of initial acid value on the stability is more notable than that of molecule structure.Compared with hydrolysis time and temperature,the water content has little effect on the hydrolytic stability of synthetic ester and the hydrolysis rate is mainly depended on the oilwater contact area.With the increasing of reaction temperature and time,the hydrolytic stability of synthetic ester becomes weakened,and a series of varieties of synthetic ester are appeared,such as higher acid value change,lower kinematic viscosity as well as deeper color,and so on.