Polymer Bulletin, Vol.39, No.4, 465-472, 1997
Successive Self-Nucleation/Annealing (SSA) - A Novel Technique to Study Molecular Segregation During Crystallization
A new procedure to fractionate ethylene/alpha-olefin copolymers using DSC is presented. This procedure allows melt/melt and melt/solid segregation to occur during thermal cycles that promote self-nucleation, crystallization and annealing processes (Successive Self-Nucleation/Annealing, SSA). The SSA has been compared with the Step-Crystallization (SC) method proposed earlier in the literature to qualitatively characterize chain branching distribution in a faster and easier way than Temperature Rising Elution Fractionation (TREF). In general, SSA produces better fractionation than SC and the DSC derived chain branching distribution by SSA can be qualitatively comparable to that obtained by TREF. The SSA technique could have important applications for the characterization of polymers that crystallize over a broad temperature range.
Keywords:LOW-DENSITY POLYETHYLENE;DIFFERENTIAL SCANNING CALORIMETRY;RISING ELUTION FRACTIONATION;RANDOM COPOLYMERS;MELTING BEHAVIOR;ETHYLENE;DSC;BLENDS;DISTRIBUTIONS;HOMOPOLYMERS