The spherulitic and lamellar morphology of melt-crystallized isotactic polypropylene

A study is presented concerning the basic morphology of melt-crystallized isotactic polypropylene (iPP). Involved within, is the coordinated application of optical and electronmicroscopy on a range of commercial iPP-s, crystallized in the temperature range 100°C–150°C. For electron microscopy in particular, the permanganic etching technique has been used throughout, providing the simultaneous combination of both real space microstructures with electron diffraction information. The investigation itself has centred on the five different spherulite types, as identified optically, which were then correlated with the details of their particular lamellar morphology. It was found that each spherulite type is characterized by virtue of the arrangement of its constituent lamellae, in terms of orientation, habit type and crystal structure. Thus, specific correlations were obtained between the structural entities on all scales of the structure hierarchy.