Abstract:

The copolymerization of propylene oxide(PO) with CO2 and homopolymerization of PO catalyzed by double metal cyanide(DMC) catalyst were investigated with focus on the reaction induced period. The results showed that the copolymerization initiated by DMC catalysts has shorter induced period than that of PO homopolymerization. At low pressure(1.0 MPa) of CO2, the induction period of homopolymerization was shorten from 45 min to 15 min. The initiation time prolongs with the increase of, the induction period, and increases from 15 min for copolymerization to 40 min for homopolymerization with enhancing the CO2 pressure from 1.0 to 7.0 MPa, respectively. The induction phenomenon of copolymerization differs dramatically from that of homopolymerization. For the former case, the pressure and temperature experience a sudden abnormal increase and then rapidly return to the state before induction. While in homopolymerization process, the temperature will slowly dropped after a sudden increase occurred in the induction period. Those observations suggest that CO2 can promote the activation of the DMC catalysts.

Key words: CO2, Propylene oxide, double metal cyanide, induction period