| Abstract: | In this work the lamellar cluster model was found to be applicable to the explanation of the mechanical yield behavior in polypropylene materials. According to the lamellar clustering theory, a spherulite is composed of radiating arms, each arm is composed of lamellar clusters, and each lamellar cluster is an aggregate of structural units of the cluster, including several crystalline lamellae and amorphous layers. The intercluster links capable of supporting external force play a role in the destruction of lamellar clusters at the yield point. These morphological features were directly confirmed from TEM observation on two-dimensional polypropylene spherulites that were crystallized from mixtures of isotactic polypropylene and atactic polypropylene, with the latter being removed later by a solvent. In addition, the structural parameters, such as the distance between intercrystalline links and the lamellar cluster thickness, which were determined by applying the mechanical yielding data to the lamellar cluster theory, were confirmed to be in agreement with the quantitative estimations from the TEM images of the polypropylene spherulites. |
