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Separation of ethylene-propylene copolymers and ethylene-propylene-diene terpolymers using high-temperature interactive liquid chromatography Part A Polymer chemistry

Chitta, Rajesh, Macko, Tibor, Brüll, Robert, Van Doremaele, Gerard, Heinz, Lars-Christian
Journal of polymer science 2011 v.49 no.8 pp. 1840-1846
carbon, chemical composition, chemical structure, composite polymers, crystallization, ethylene, fractionation, liquid chromatography, molecular weight, solvents, temperature
Ethylene-propylene-diene terpolymers (EPDM) are generally amorphous and, therefore, do not crystallize from solution. Consequently, fractionation techniques based on crystallization, such as crystallization analysis fractionation or temperature rising elution fractionation, cannot be used to analyze their chemical composition distribution. Moreover, no suitable chromatographic system was known, which would enable to separate them according to their chemical composition. In this study, two different sorbent/solvent systems are tested with regard to the capability to separate EPDM-terpolymers and ethylene-propylene (EP)-copolymers according to chemical composition. While porous graphite/1-decanol system is selective towards ethylene and ethylidene-2-norbornene, carbon coated zirconia/2-ethyl-1-hexanol is preferentially selective towards ethylene. Consequently, the earlier system enables to separate both EP copolymers and EPDM according to the chemical composition and the latter mainly according to the ethylene content. The results prove that the chromatographic separation in both sorbent/solvent systems is not influenced by molar mass of a sample or by its long chain branching.