View More View Less
  • 1 Istituto di Ricerche su Tecnologia dei Polimeri e Reologia del CNR 80072 Arcofelice NA
  • 2 Centro Studi dei Processi Ionici e della Proprietà dei Sistemi Macromolecolari del CNR, Ingegneria Chimica Università de Pisa 56100 Pisa Italy
Restricted access

The crystallization and melting behaviour of isotactic polypropylene (iPP) samples synthetized with different catalyst systems (low and high-yield) have been studied by differential scanning calorimetry and optical microscopy. The isothermal crystallization rates from the melt have been found to depend on the catalyst system employed and on the isotacticity index of the sample. Moreover, for low-yield iPP, Avrami analysis of the overall kinetics has provided evidence of the presence of secondary crystallization phenomena. The values of the equilibrium melting point, energy of nucleation and surface energy of folding of iPP lamellar crystals have been calculated according to the ‘Kinetic theories’ of polymer crystallization. The observed variation of such thermodynamic parameters for the various iPP samples has been accounted for by the amount and type of configurational irregularities present along the chains and by the differences in the molecular weight distribution.

Monthly Content Usage

Abstract Views Full Text Views PDF Downloads
Nov 2020 0 0 0
Dec 2020 0 0 0
Jan 2021 1 0 0
Feb 2021 1 0 0
Mar 2021 0 0 0
Apr 2021 0 0 0
May 2021 0 0 0