Simple model to predict gel formation in olefin‐diene copolymerizations catalyzed by constrained‐geometry complexes

Abstract

in Wiley InterScience (www.interscience.wiley.com).We have developed an analytical model to predict the onset of gel formation in ethylene/1-octene/1,9-decadiene terpolymerizations using constrained-geometry catalysts. The model relies on three kinetic parameters to characterize the catalyst response. Polymer resins have been synthesized in a continuous stirred-tank reactor to determine the model parameters, and to validate the model predictions for polymer properties and for the onset of gel formation and reactor fouling. The experimental results indicate that the free double bonds in 1,9-decadiene are as reactive as those found in 1-octene, and that the reactivity of 1,9-decadiene double bonds decreases after the 1,9-decadiene molecules become part of a polymer chain. The model predictions of polymer properties agree well with chromatographic, density, and mass-balance data. Moreover, the model was successful in preventing unintended reactor fouling during the duration of the experimental campaign. V

Copolymerization of Ethylene with 1,9‐Decadiene: Part I – Prediction of Average Molecular Weights and Long‐Chain Branching Frequencies

“…An interesting result from the Monte Carlo simulations is that LCBs were formed significantly only in chains with high molecular weights; for low and medium molecular weights, the LCB frequency is practically nil. This is in agreement with results previously published in the literature, indicating that copolymerizations performed with 1,9‐decadiene may eventually make polymers with very high molecular weights and gels.…”

Modeling of Synthesis and Flow Properties of Propylene–Diene Copolymers

“…Polypropylene (PP) polymerisation using most metallocene catalysts, typically propagated through 1,2 insertion and terminated by β-hydrogen elimination, leads to a sterically congested vinylidene chain-end that prohibits further inclusion in another growing chain 5,6 . Copolymerisation with non-conjugated dienes 7-9 offers a viable route to introduce LCB in one-step PP synthesis and to enhance amount of LCB during polyethylene synthesis using catalysts that allow macromonomer insertion 10,11 .…”

Static and Dynamic Scaling Close to Gelation in Chain‐Polymerization: Effect of Reactor Type

“…The heavy tailed nature of the molar mass distribution in CSTR for ethylene‐diene copolymerization has implicitly been recognized in some theoretical calculations and experiments by noting that the polydispersity index remains finite as the gel point is approached. However, the possibility that the weight averaged molar mass remain finite across the transition has been overlooked because of the approximate nature of the calculations.…”