Oxidative degradation and morphological properties of gamma-irradiated isotactic polypropylene films.

Isotactic polypropylene (iPP) films of 25 μm thickness were subjected to gamma-ray irradiation for different doses (30, 60, 90 and 100 kGy) at ambient atmosphere and both molecular modifications and surface properties have been investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), respectively. The occurrence of the oxidation process is identified and quantified by the FTIR. In addition, it is found that the carbonyl index increases with the absorbed dose which confirms that the irradiation process induces the diffusion of the oxygen into the iPP matrix. The AFM image (for virgin and higher dose irradiated samples) showed a dramatic change in the surface topography. The gamma radiation induces the formation of the nanostructured iPP surface. The roughness of the polymer surface, measured by AFM, increases after gamma irradiation. These results revealed that the oxidative degradation may be correlated with the morphological properties. [ABSTRACT FROM AUTHOR]