| Abstract: | In order to elucidate the structure of the Ziegler-Natta polymerization center, we have carried out some kinetic studies on the polymerization of propylene with active TiCl3—Zn(C2H5)2 in the temperature range of 25–56°C. and the Zn(C2H5)2 concentration range of 4 × 10?3–8 × 10?2 mole/1., and compared the results with those obtained with active TiCl3—Al(C2H5)3. The following differences were found: (1) the activation energy of the stationary rate of polymerization is 6.5 kcal/mole with Zn(C2H5)2 and 13.8 kcal./mole with Al(C2H5)3; (2) the growth rate of the polymer chains with Zn(C2H5)2 is about times slower at 43.5°C.; and (3) the polymerization centers formed with Zn(C2H5)2 are more unstable. It can be concluded that the structure of the polymerization center with Zn(C2H5)2 is different from that with Al(C2H5)3. |
