Abstract: In accordence with the reaction mechanism that the reaction of n-dodecyl alcoholethylene oxide(EO)is catalyzed by the strong base,the optimum reaction time expression ofthe relatively highest product containing at the given polymer number of EOis obtained bythe Laplace transform.Our expression was compared with Weibull's and Flory's ones undercertain conditions,and the relationship between the optimum reaction time and the averagepolymer number of EOis discussed.As an example,the conclusion is also proved with theresult that lauryl alcohol reacts with EOunder different catalytic conditions.

Key words: Polyoxyethylene n-didecyl alcohol ether, Base catalyst, Degree of polymerizationto compare our expression