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Keywords:

  • chemical composition distribution (CCD);
  • crystallization analysis fractionation (CRYSTAF);
  • crystallization elution fractionation (CEF);
  • metallocene catalysts;
  • polyethylene (PE)

Abstract

Thumbnail image of graphical abstract

Ethylene/1-olefin copolymers with controlled bimodal molecular weight distributions (MWDs) and chemical composition distributions (CCDs) have improved mechanical and rheological properties. In this work, the Stockmayer's distribution was used to develop a criterion for CCD bimodality. The proposed criterion was validated theoretically using simulation data and experimentally using crystallization analysis fractionation (CRYSTAF) and crystallization elution fractionation (CEF) of ethylene/1-octene copolymer blends. The effect of mass fraction and number average molecular weight of copolymer produced with each metallocene catalyst on CCD bimodality was also examined. The proposed criterion was then used as a benchmark for describing cocrystallization effects in both CRYSTAF and CEF techniques.