Microfocus X-ray Scattering and Raman Microspectrocopy Study of Transcrystalline Isotactic Polypropylene

Abstract

Isotactic polypropylene (iPP) is one of the most widely-used consumer polymers. It is a semicrystalline thermoplastic exhibiting four different polymorphs: the monoclinic phase (predominant under regular processing conditions), the trigonal phase (promoted under special processing conditions such as crystallization under shear), the orthorhombic phase (present in materials with low molecular weight or regular chain defects) and a mesomorphic phase (a semi-ordered phase).1 Moreover, when crystallization takes place in the presence of fibers, transcrystalline morphologies can develop. This work presents microfocus wide- and small-angle X-ray scattering together with Raman microspectroscopy on the transcrystalline-cylindritic morphology of iPP.2,3 The spatial distribution of the and phases with unprecedented spatial resolution will be shown. In addition, changes in the lamellar orientation of the row nuclei, which act as nucleation centers for the phase, have been found, whereas the lamellar structure of the phase did not show changes in orientation along the crystallization front.