Triad sequence determination of ethylene-propylene copolymers - application of quantitative 13C NMR

A methodology for acquiring fully quantitative 13C{1H} NMR spectra for high performance ethylene-propylene copolymers has been proposed. To minimize the spectral acquisition time without sacrificing spectral quality, different amounts of chromium(III)acetylacetonate relaxation agent has been added to optimize its concentration. The study demonstrates the critical setting of delay time for determining six triad distributions from eight discrete set of resonances which otherwise leads to inaccurate determination of triad concentrations. It allows precise integral measurements of low intensity resonances depending on copolymer composition, and significant reduction of experimental time.