Kinetics of hexene‐1 polymerization using [(N,N′‐diisopropylbenzene)‐2,3‐(1,8‐napthyl)‐1,4‐diazabutadiene] dibromonickel/methylaluminoxane catalyst system |
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Authors: | Ummadisetty Subramanyam Swaminathan Sivaram |
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Institution: | 1. Polyolefin Laboratory, Division of Polymer Science and Engineering, National Chemical Laboratory,Dr. Homi Bhabha Road, Pune 411 008, India;2. Polyolefin Laboratory, Division of Polymer Science and Engineering, National Chemical Laboratory,Dr. Homi Bhabha Road, Pune 411 008, IndiaPolyolefin Laboratory, Division of Polymer Science and Engineering, National Chemical Laboratory,Dr. Homi Bhabha Road, Pune 411 008, India |
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Abstract: | Kinetics of hexene‐1 polymerization was investigated using (N,N′‐diisopropylbenzene)2,3‐(1,8‐napthly)‐1,4‐diazabutadiene]dibromonickel/methylaluminoxane catalyst. Experiments were performed at varying catalyst and monomer concentrations in the temperature range of ?10 to 35 °C. First order time‐conversion plot shows a downward curvature at temperatures of 20 °C and 35 °C indicating the presence of finite termination reactions. A nonlinear plot of degree of polymerization (Pn) with respect to conversion indicates occurrence of transfer reactions and slow initiation. The experimental molar masses are higher than predicted, which implies that a fraction of catalyst species could not be activated or is deactivated at the early stages of the reactions. The efficiency of the catalyst (Cateff) varies from 0.77 to 0.89. The observed polydispersity of the poly(hexene‐1) s is in the range of 1.18–1.48. The reaction order was found to be 1.11 with respect to catalyst. The Arrhenius plot obtained using the overall propagation rate constant, kp, at five different temperatures (?10, 0, 10, 20, and 35 °C) was found to be linear with an activation energy, Ea = 4.3 kcal/mol. Based on the results presented it is concluded that the polymerization of hexene‐1 under the above‐mentioned conditions shows significant deviation from ideal “living” behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1093–1100, 2007 |
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Keywords: | activation energy chain transfer degree of polymerization hexene‐1 kinetics (polym ) nickel (α ‐diimine) |
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