Chemical modification of polypropylene induced by high energy carbon ions

Abstract Polypropylene was irradiated with 12 C + ions of 3.6 and 5.4 MeV energy using 3 MV Pelletron. The spectral changes owing to ion bombardment were investigated by UV–VIS and Fourier-transform infrared (FTIR) spectroscopy. A gradual increase in absorbance was observed around visible and near visible region with increase in fluence of bombarding ions. The difference absorption spectra show formation of chromophoric groups with wavelength maximum near 380 nm at lower fluence, but at high fluence a shift in peak is observed. The chromophoric groups are likely to be the extended conjugated polyene system and the red shift in peak postion at high fluence may be attributed to the greater degree of conjugation. The formation of unsaturated linkage is confirmed by the FTIR spectra with observed stretching band around 1650 cm −1 and its intensity was found to increase with increase in ion fluence studied. The gases (in the range 2–80 amu) which were evolved due to interaction of polypropylene with 12 C + ions were measured with Residual Gas Analyzer (RGA). A large number of gaseous components were detected. This shows that polymer chains break into some smaller fragments which concomitantly leads to extended conjugation.