Isothermal crystallization rate data for polypropylene films are obtained by a rapid scanning x-ray diffraction technique. These are compared with previously obtained data on similar samples of the same polymer by microscopic observation of spherulite nucleation and growth rates. The degree of crystallinity is found to increase more slowly than the weight fraction of the sample filled with spherulites, indicating that all of the crystallization does not occur at the growing spherulite surface. A mechanism for this secondary crystallization process occurring within the spherulite is proposed in which the spherulite first forms with an initial degree of crystallinity, and then the crystallization continues approaching a limiting degree of crystallinity. The kinetic parameters characterizing this secondary process are determined and their variation with temperature is studied. (Author).These are compared with previously obtained data on similar samples of the same polymer by microscopic observation of spherulite nucleation and growth rates.
|Title||:||The Kinetics of Crystallization of Polypropylene Fractions Ii|
|Author||:||E. Meinecke, MASSACHUSETTS UNIV AMHERST POLYMER RESEARCH INST.|