Macromol. Chem. Phys. zyxwvu 195,211-216 (1994) zyxwv 21 1 zy Chain propagation rate constants for gas-phase polymerization of propene and 1-butene with Ziegler-Natta catalysts Leone Oliva* Dipartimento di Fisica, Universith di Salerno, 1-84081 Baronissi (Italy) Martino Di Serio, Nicolangelo Peduto, Eli0 Santacesaria Dipartimento di Chimica, Universith Federico 11, via Mezzecannone 4, 1-801 34 Napoli zy (Italy) (Received: March 4, 1993; revised manuscript of April 20, 1993) SUMMARY 13C NMR analysis of propene/l -butene block copolymers obtained by gas-phase polymeriza- tion with Ziegler-Natta catalysts allows the determination of the propagation rate constants for the homopolymerization of the two monomers. They are very similar for the Solvay type catalyst 6-TiCI3/AIMe3 and the supported catalyst TiC1,/MgCl,/phthalate/AlMe3. The constant of propene polymerization is three times higher than that of 1-butenepolymerization. The high value of the constant found for propene polymerization is in agreement with the literature value determined by the stopped flow polymerization method. Introduction As reported in a previous paper zyxwv *), reasonably clear-cut block copolymers of a- olefins, e. g., ethylene and propene, can be prepared in the presence of heterogeneous isotactic specific catalysts such as 6-TiCl3/Al(CH,),, by feeding sequentially the comonomers. Because the average lifetime of the polymer chains is short (at most a few minutes) and the propagation rate is fast, copolymerization must be performed at low temperature. If reasonably short blocks are desired, the feed must be changed very often and the monomer concentration has to be low. Unreacted monomer must also be removed after each feeding step. In this way the chain propagation rate constants for homopolymerization of ethylene and propene, in the presence of zy 6- TiCl,/AI(CH,),, was evaluated from the length of the homosequence blocks. In this paper we extend the above study to the propene/l-butene pair with the aim of establishing whether the monomer pair chosen has any influence on the experimentally determined value of the propagation rate constant of propene. The improvement of the experimental accuracy obtained by changing the manner of feeding the comonomers and Al(CH,), is also reported. Experimental part Reagents: Solvay 6TiC1, and the supported catalyst have been prepared according to the literature2s3). AI(CH,), was purchased from Fluka and used as received. Propene and 1-butene (polymerization grade) were purchased from Societh Ossigeno Napoli. zyxw 0 1994, Hiithig & Wepf Verlag, Basel CCC 1022-1352/94/$08.OO