Swift heavy ion induced structural and chemical changes in BOPP film

Swift heavy ions (SHIs), such as, 80 MeV Si7+ and 120 MeV Ag9+ ions were used to irradiate 15 μm bi-axially oriented polypropylene (BOPP) films. The fluence (Φ) dependence of the structural and chemical changes in BOPP was investigated. The irradiated BOPP films were analyzed ex situ by means of FTIR, UV and DSC. Due to SHI irradiation, the isotactic helical structure of polypropylene (PP) gets reduced. PP undergoes distortion of its crystal lattice in magnitude proportional to the fluence. The scission of C–H bonds and production of unsaturated groups like dienes and trienes occurred after irradiation with Si ions for Φ ⩾ 1012 ions/cm2 and Ag ions for Φ ⩾ 1011 ions/cm2. It was found that Ag ions are better than Si ions for creation of free radical active sites on BOPP. The observed findings are very useful particularly in the selection of optimum experimental conditions for SHI induced graft copolymerization.