Thermal dependence of nucleation and growth rate in polypropylene by non isothermal calorimetry

Abstract

Abstract:Crystallization of polypropylene at a constant cooling rate is studied by differential scanning calorimetry. The results are interpreted using Ozawas theory, which allows the determination of the type of nucleation. In the studied polypropylene, a transition between a sporadic in time and an instantaneous nucleation is found at about 122 ~ Furthermore, an extension of Ozawa's theory is proposed to predict the thermal dependence of the spherulite growth rate. The results are consistent with those obtained by direct microscopic observation.

Crystallization of Polypropylene: Application of Differential Scanning Calorimetry Part I. Isothermal and Non-Isothermal Crystallization

“…DSC studies of iPP crystallization at a constant cooling rate enable determination of nucleation regime by applying the Ozawa's theory, delivering results consistent with those obtained by direct microscopic observation [2].…”

“…The subject of polymer crystallization has been of great interest for several decades due to the complex phenomena usually taking place, as well as its industrial importance [1][2][3][4][5].…”

Global weak solutions of non-isothermal front propagation problem

“…Recently the modeling of non-isothermal crystallization has been extensively studied in [27,31,34,29,15,16,3,5,6,7]. The local existence of a single smooth moving front in (1.1)-(1.3) was shown under the assumption that initial interface is a small perturbation of a sphere in Friedman-Velazquez [20].…”

Crystallization of Polypropylene: Application of Differential Scanning Calorimetry Part Ii. Crystal Forms and Nucleation

“…Monasse and Haudin have studied the thermal dependence of nucleation and growth rate in iPP by applying DSC at cooling rates ranged from 0.31-80 K/min [96]. The experimental data analyzed with the Ozawa theory showed transition between heterogeneous and homogeneous nucleation at about 122 o C. In the temperature range of heterogeneous nucleation they calculated the surface free energies, σ and e σ and the reported values (9.2x10 erg/cm Self-nucleation is a general term describing nucleation of a melt or solution by its own crystals grown previously.…”