A novel methodology is presented for studying the nature of multiple-site-type catalysts used for the synthesis of olefin copolymers. Experimental results of copolymer composition (short-chain branching) versus molecular weight are obtained by analyzing hightemperature gel-permeation chromatography fractions with Fourier-transform infrared spectroscopy. The molecular weight distribution obtained by gel-permeation chromatography is deconvoluted to determine the number of different site types on the catalyst. The average copolymer composition of chains made on each site type is then determined from copolymer composition versus molecular weight data. It is also shown how to extend this methodology to determine the comonomer reactivity ratios per site type.

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A measurement of the Raman spectrum of cyclopentane in the gas phase under moderately high resolution reveals that the ground state radial transition at 272.5 cm−1 has two associated Q branches at 265.3 and 257.8 cm−1, corresponding to the first two excited transitions of the radial mode. With this information and the pseudorotational combination and difference bands with the CH2 deformation observed by During and Wertz, we have used both the perturbation treatment developed by Ikeda et al. and the direct matrix diagonalization program developed earlier to obtain the potential energy surface for cyclopentane in the ground state and in the first excited state of the CH2 deformation. In the ground state the barrier to planarity is found to be 1824 ± 50 cm−1 (5.21 kcal) and the equilibrium out-of-plane amplitude qe=0.47 ± 0.025 Å.

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