Determination of branches in terpolymers of ethylene, 1-butene, and long α-olefin by pyrolysis-hydrogenation-gas chromatography

Pyrolysis-hydrogenation-gas chromatography (PHGC) was applied to determine the branches in ethylene-1-butene-α-olefin terpolymers, where α-olefin was 1-decene, 1-dodecene, or 1-hexadecene. The polymers were prepared by using Ziegler-Natta catalysts in n-heptane suspension. Each branch type was identified from the characteristic methylalkane peak caused by β-scission of the branched carbon. Quantitative determinations were done by using ethylene-α-olefin copolymers as reference. Octyl, decyl, and tetradecyl branches were identified from the pyrograms. Branch contents determined by the PHGC technique were compared with those obtained by IR and ¹³C NMR spectroscopy. Few scissions were observed in the branches of the copolymers.