Separation of high-impact polypropylene using interactive liquid chromatography

Fractionation techniques such as temperature rising elution fractionation or crystallization analysis fractionation fail to fractionate the ethylene-propylene (EP) copolymers, which are a component of high-impact polypropylene (hiPP), according to their chemical composition. High-temperature high-performance liquid chromatography separates blends of EP-copolymers and polypropylene. The elution volume of the EP-copolymers depends linearly on the average content of ethylene. The separation according to the chemical composition was hyphenated with size exclusion chromatography. In this way, the relationship between the distribution with regard to chemical composition and molar mass, that is, the full chemical heterogeneity of hiPP, was revealed for the first time.