Effect of beta irradiation on the structural changes of isotactic polypropylene

Abstract

The electron β-irradiation of isotactic polypropylene (iPP) influenced the sample chemical structure because it mostly caused the crosslinking of the polymer chains beside the macromolecule degradation. The irradiation effect led to the corresponding changes in physical properties (crystallinity, crystal size, melting and crystallisation temperatures). The amount of the β-phase in the samples decreased with the increasing β-irradiation dose, changing into the α - and amorphous phase. After the irradiation, the iPP melting and crystallisation temperatures decreased, and the spherulitic structure was partially decomposed. The imbibition of boiling xylene proved that the highest degree of crosslinking took place in the samples irradiated with a dose of 33 kGy, showing the highest crystallinity and melting temperature.