Study of gel formation by ionizing radiation in polypropylene

The objective of this work is to study the formation of microgel in pristine PP and modified PP. The modified PP in pellets was synthesized by gamma irradiation of pristine PP under a crosslinking atmosphere of acetylene in different doses of 5, 12.5 and 20 kGy, followed by thermal treatment for radical recombination and annihilation of the remaining radicals. The gel content of the modified polypropylenes was determined by extraction in boiling xylene for period of 12 h at 138 °C. The gel formed of pristine PP and modified (i.e., irradiated) was characterized using optical microscopy (OM), scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XDR). The PP morphological study indicated the microgel formation with increase of spherulitic concentration with dose.