Dynamic crystallization (DC) is a new characterization technique for measuring the chemical composition distribution (CCD) of semicrystalline copolymers. This technique fractionates polymers based on chain crystallizabilities under a constant cooling rate; a solvent is also fed through the column at a constant flow rate during the crystallization to enhance the physical separation of the polymer fractions. In this work, a DC model for ethylene/1-olefin copolymers on the basis of population balance, crystallization kinetics, and axial dispersion is proposed.

Temperature rising elution fractionation (TREF) is a characterization technique widely used to estimate chemical composition distribution (CCD) of semicrystalline copolymers. Although several mathematical models have been previously proposed to elucidate the TREF fractionation mechanism, all previous TREF models assume equilibrium fractionation; thus, they cannot describe important kinetics effects observed in TREF experiments. In this work, a new TREF model is developed incorporating crystallization and dissolution kinetic models during the fractionation process.

High-temperature thermal gradient interaction chromatography (HT-TGIC) was recently introduced into the area of polyolefin analysis. This new technique uses commercially available Hybercarb columns to separate polyolefin chains based on their interaction with the porous graphitic carbon stationary phase in a temperature gradient mode. In this paper, a systematic study of HT-TGIC operation conditions is presented for ethylene/1-octene copolymers and their blends.