Synthesis of Propylene/1-Butene Copolymers with Ziegler-Natta Catalyst in Gas-Phase Copolymerizations, 1 Kinetics and Macromolecular Properties Fabricio M. Silva, 1,2 Enrique L. Lima, 1 Jose ´ C. Pinto, 1 Timothy F. McKenna* 2 1 Programa de Engenharia Quı ´mica/COPPE, Universidade Federal do Rio de Janeiro, Cidade Universita ´ria, CP 68502, Rio de Janeiro, 21945-970, RJ, Brasil 2 LCPP–CNRS/ESCPE-Lyon, 43 Blvd du 11 Novembre 1918, Ba ˆt 308F, BP 2077, 69616 Villeurbanne, France Fax: þ33 (0)4-72-43-17-68; E-mail: mckenna@lcpp.cpe.fr Received: August 24, 2005; Revised: September 21, 2005; Accepted: September 26, 2005; DOI: 10.1002/macp.200500385 Keywords: 1-butene; gas-phase copolymerization; propylene; random copolymers; Ziegler-Natta polymerization Introduction Copolymerization reactions are widely used for the modi- fication of polymer properties. The appropriate choice of comonomers can be used to significantly modify the pro- perties of polymer resins, leading to considerable variety or improvement of product performance. In propylene poly- merization processes, comonomers can be used for modifi- cation of many important end use properties, such as hardness, tensile strength, stiffness, density, melting point, impact strength and transparency of the final polymer resin. Special attention has been paid to propylene films [non- oriented (NOPP) and biaxially oriented (BOPP)], which are made from a combination of highly isotactic polypropylene and random copolymers. Ethylene is the most common monomer used in propylene copolymerizations. Although ethylene can be successfully used to produce several polymer grades, different comonomers, such as 1-butene, can also be used to produce propylene copolymers with improved properties. It is well known that the melting point and the crystallinity of isotactic polypropylene-based polymers are lowered by incorporation of comonomer units. In the particular case of propene/1-butene copolymers (CPP1B), a decrease in the melting temperature is observed as conse- quence of the introduction of ethyl side chains formed by incorporation of 1-butene units into the polypropylene chains. According to Arnold et al., [1] CPP1B obtained with Summary: The appropriate choice of comonomers can be used to create a wide range of polymer properties, leading to considerable improvement of product performance. Exper- imental runs were performed to evaluate the effect of 1- butene on the crystallinity, the melt temperature and the molecular weight distribution (MWD) of the final propylene/ 1-butene copolymer resins. According to the results obtained, the melt temperature of the copolymer material can be reduced significantly compared to that of the polypropylene homopolymer. The incorporation of 1-butene into the copolymer chain leads to a decrease of the sealing initiation temperatures of propylene polymer resins. GPC analyses of copolymer samples showed that 1-butene concentration does not seem to significantly influence either the shape of the MWD or the polydispersity indexes for a given set of reaction conditions. Therefore, a family of propylene/1-butene ran- dom copolymers grades can be successfully developed for gas phase processes for packaging and film applications. Macromol. Chem. Phys. 2005, 206, 2333–2341 ß 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Full Paper DOI: 10.1002/macp.200500385 2333