INVESTIGATION OF ETHYLENE 1-OCTENE COPOLYMERIZATION MODELS BY C-13 NMR

Statistical reaction models have been used to fit C-NMR spectra for et hylene/1-octene copolymers and to describe the polymerization reaction probabilities. Ten models ranging in complexity from a one-site Berno ulli probability to multiple site second-order Markov systems were stu died. Model parameters were determined by fitting the experimental int egrations of replicated spectra using a maximum likelihood method. The best fit to the experimental NMR spectra was obtained with a two-site model, one site producing mainly high-density polymer following a Ber noulli probability model, while the second site allows more incorporat ion of octene following a chain-end controlled probability described b y first-order Markov statistics. (C) 1994 John Wiley & Sons, Inc.