Production of Long-Chain Branched Polyolefins with Two Single-Site Catalysts: Comparing CSTR and Semi-Batch Performance Saeid Mehdiabadi, Joa ˜o B. P. Soares, * Armenag H. Dekmezian Introduction Recent advances in polyolefin manufacture have focused on the production of differentiated commodity polyolefins, specialty polyolefins, and polyolefin hybrids. What differ- entiates these new polyolefin types from commodity polyolefins is that their molecular architectures are much more complex and often contain long chain branches (LCBs), leading to unique properties that make them competitive with specialty polymers. This is an exciting new research area in the polyolefin industry because it promises to open new markets for polyolefins that have been restricted to other polymers. One approach to produce these novel polyolefins is to use one or two single-site catalysts in two continuous stirred-tank reactors (CSTRs) in series. The first CSTR is used to make semi-crystalline polymer chains, some of which must be vinyl-terminated (macromonomers). These macromonomers are then incorporated, via terminal branching, onto the chains growing in the second CSTR, becoming LCBs. If the backbone and the macromonomer have different compositions, we call these chains cross- products. Since it is not possible to incorporate all macromonomers, the final polymer will consist of a complex mixture of linear chains made by the two catalysts, homogeneous-branched chains (that is, chains where the backbone and all LCBs are of the same type) and cross-products. The cross-product will add rather special properties to the polymer and, depending on its molecular architecture, it may act as a viscosity modifier, a thermoplastic elastomer (TPE), or a polymer blend Full Paper S. Mehdiabadi, J. B. P. Soares Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada E-mail: jsoares@uwaterloo.ca A. H. Dekmezian Baytown Technology and Engineering Complex, ExxonMobil Company, Baytown, TX 77522, USA We developed a mathematical model to describe the solution polymerization of olefins with two single-site catalysts in a series of two CSTRs. The model was used to simulate processes where semi-crystalline macromonomers produced in the first reactor are incorporated as long chain branches onto amorphous (or lower crystallinity) chains in the second reactor (cross- products). The simulation results show that CSTRs are more efficient to make chains with high LCB density and high weight percent of cross-products. The model can also predict the polydisper- sity index, average chain lengths, and fractions of the different polymer popu- lations, and help the polymer reactor engineer formulate new products with complex microstructures. Stereoselective Linear Catalyst + Propylene Isotactic PP Macromonomer LCB Catalyst Propylene + PP Macromonomer Linear Isotactic PP (unreacted) Linear Atactic PP Homogeneous Branched Atactic PP Cross-Product Macromol. React. Eng. 2008, 2, 529–550 ß 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/mren.200800025 529