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Keywords:

  • impact poly(propylene) copolymer;
  • TREF;
  • HT HPLC;
  • HPer DSC

Summary

The microstructure and thermal behaviour of complex polyolefins affect the product properties significantly. Therefore a thorough characterization of such semi-crystalline materials is necessary to understand the relationship between molecular structure and melting and crystallization behaviour. In the present work, the correlation between the chain structure and thermal behaviour of various components in a complex midelution temperature TREF fraction (80 °C) of a commercial impact poly(propylene) copolymer were studied by using a combination of prep TREF and a highly selective separation method, HT HPLC, followed by thermal analysis of resulting dual fractions via a fast scanning DSC technique (HPer DSC). HT-HPLC can separate polymer chains according to their microstructure (chemical composition, tacticity and chain branching) within in short analysis time. The ability to measure the thermal properties of minute amounts of materials by HPer DSC helps to correlate their chemical structure with the melting and crystallization behaviour. In this way, the present hyphenated technique (prep-TREF-HT-HPLC-HPer DSC) provides a powerful tool to separate and analyse complex mixtures of polymer components having different chemical structures and thermal properties.