Self-nucleation and recrystallization of isotactic polypropylene (α phase) investigated by differential scanning calorimetry

Authors

  • B. Fillon,

    1. Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    Current affiliation:
    1. Centre de Recherches de Voreppe, Groupe des Matériaux et Interfaces, B. P. 27, 38340 Voreppe, France
    Search for more papers by this author
  • J. C. Wittmann,

    Corresponding author
    1. Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    • Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    Search for more papers by this author
  • B. Lotz,

    Corresponding author
    1. Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    • Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    Search for more papers by this author
  • A. Thierry

    1. Institut Charles Sadron (CRM-EAHP), CNRS-ULP, 6 rue Boussingault, 67083 Strasbourg Cédex, France
    Search for more papers by this author

Abstract

The crystallization behavior after partial or complete melting of the α phase of iPP is examined by combined differential scanning calorimetry (DSC) and optical microscopy: calorimetric results are directly correlated with corresponding morphologies of microtome sections of DSC samples. On partial melting at various temperatures (hereafter referred to as Ts) located in a narrow range (4°C) below and near Tm, the number of nuclei increases (as in classical self-nucleation experiments), by several orders of magnitude; on subsequent cooling, the crystallization peak is shifted by up to 25°C. After partial melting in the lower part of the Ts range and recrystallization, the polymers display a prominent morphology “memory effect” whereby a phantom pattern of the initial spherulite morphology is maintained.

After partial melting in the upper part of the Ts range the initial morphology is erased and self-nucleation affects only the total number of nuclei. The present experimental procedures make it possible to define, under “standard” conditions, the crystallization range of the polymer and in particular, the maximum crystallization temperature achievable when “ideally” nucleated. © John Wiley & Sons, Inc.

Ancillary