Modeling possible long chain branching reactions for polyethylene in a semi-batch reactor
May 20-25, 2018
Long chain branches (LCBs) in polyethylenes made with metallocene catalysts are conventionally accepted to be formed via random terminal branching reactions. However, other reactions such as C-H activation and intramolecular incorporation have been suggested in the literature as alternative pathways to LCB. In this simulation work, we contrasted two possible mechanisms for LCB formation in a semi-batch reactor: terminal branching and C-H activation to find out how different polymerization conditions and LCB mechanisms affected the polymer microstructure. The C-H activation reaction was broken down into 3 steps: bond activation of a dead chains, bond activation of macromonomers (dead chains with terminal vinyl groups), and bond activation of a living chain (intramolecular pathway). As it is quite difficult to determine which C-H bond activation reactions (if any) are relevant to LCB formation in these systems, we compared all possible scenarios to distinguish which are more likely to make polyethylenes with the microstructures observed experimentally in terms of molecular weight distribution, long chain branching density, and branching as a function of chain lengths for the different polymer species in the reactor.
Abdulrahman Albeladi, Saeid Mehdiabadi, and João B. P. Soares, "Modeling possible long chain branching reactions for polyethylene in a semi-batch reactor" in "Polymer Reaction Engineering X (PRE 10)", John Tsavalas, University of New Hampshire, USA Fouad Teymour, Illinois Institute of Technology, USA Jeffrey Stubbs, HP Inc., USA Jose R. Leiza, University of the Basque Country, Spain Eds, ECI Symposium Series, (2018). http://dc.engconfintl.org/prex/49