Metallocene–methyl aluminoxane catalysts for olefin polymerization. VIII. Infrared spectra of anisotactic polypropylene^†

Polypropylenes obtained with the homogeneous racemic ethylene bis(indenyl) zirconium dichloride/methyl-aluminoxane catalyst were fractionated by solvent extraction. The IR absorbance ratios, A₉₉₈/A₉₇₃ and A₈₄₁/A₉₇₃, were found to vary linearly with the homosteric sequence population, [m m m m] and [m m]. These results are compared with the results of a similar study by Burfield and Loi on commercial and laboratory polypropylenes of the conventional types.