In a previous paper

the rate of propylene oxide (PO) polymerization catalyzed by double metal cyanide complexes (DMC) had been determined to be proportional to the catalyst amount e and the square of monomer concentration M. The same reaction in the presence of substances contMning active hydrogens which were applied to regulate the molecular weights of the produced polyethers was inrestigated in this paper．All the reactions were carried out in 0.1 L autoclaves equipped with manometers and the induction period to and polymerization rate Rp were determined by means of pressure measurements．It was found that regulators with higher OH functionality showed greater influence on to

which was prolonged with addition of regulators except cyclohexanol．It was also found that the polymerization rate depended on the type of regulators and was inversely proportional to a linear function of the regulator concentration Tr．Moreover

a limited amount of water behaved as a strong bifunctional regulator which intensively influenced to and Rp；the presence of excess water deactivated the catalyst and hindered the polymerization．It Was revealed that the DMC catalyst and the monomer beth were necessary for the initiation of the polymerization．Based on this understanding

a possible mechanism was propesed for the polymerization and a kinetic equation as following was deduced

which was in well accordance with experimental results． Rp=KM2c/(1+kTr)