Surface Properties of Gamma-Irradiated Polypropylene

The effect of γ-irradiation on the surface properties of polypropylene (PP) has been studied as a function of the absorbed dose. It has been established that γ-irradiation leads to an increase in the free surface energy of the polymer, its acid–base component, and the surface polarity. An analysis of the IR spectra of γ-irradiated PP samples indicated the formation of oxygen-containing groups in the composition of PP macromolecules, which was confirmed by the values of the surface acidity parameter. An increase in the dose led to an increase in the concentration of products of radiation-induced conversion. A significant increase in the melt flow index (MFI) of polypropylene up to an absorbed dose of 150 kGy also evidenced the occurrence of oxidation and destruction processes. The MFI decreased at radiation doses above 150 kGy, and this fact indicates that such doses of ionizing radiation lead to the predominance of the processes of polymer structuring or crosslinking.