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Manufacturing of Decadiene Copolymers

Job D. Guzman1, Daniel Arriola2, Joshua Gaubert1, Teresa Karjala1, and Brian Kolthammer1. (1) Polyolefins R&D, The Dow Chemical Co., 2301 N. Brazosport Blvd., Freeport, TX 77541, (2) Chemical Sciences, The Dow Chemical Co., Dow Center, Midland, MI 48674

The copolymerization of ethylene with small amounts of 1,9-decadiene can lead to massive crosslinking of the polyethylene resin and severe fouling of commercial reactors. This work is a first step towards developing the manufacturing know-how to reliably produce 1,9-decadiene/ethylene copolymers. We have developed a gel-point model to predict the maximum amount of 1-9-decadiene, permitting fouling-free operation of well-mixed reactors. The gel-point model relies on three reactivity ratios to characterize the response of a catalyst system. A series of 1,9-decadiene copolymers has been synthesized in a continuous stirred-tank reactor to determine the reactivity ratios for a metallocene catalyst, and to validate the model predictions for the polymer properties and for the onset of fouling. The experimental results indicate that the double bonds in 1,9-decadiene are, on average, as reactive as those found in alpha olefins of similar molecular weight, and that the reactivity of 1,9-decadiene double bonds decreases after the 1,9-decadiene molecules become part of a polymer chain. The gel-point model predictions of polymer properties agree well with chromatographic, density, and mass-balance data, and the gel-point model was successful in preventing unintended fouling during the duration of the experimental campaign.