Effects of ion beam bombardment on the crystalline structure of polymers

The authors discuss the amorphization process of semicrystalline and oriented PET (poly(ethyleneterephtalate)) thin foils by ion beam irradiation. A decrease in the bombarded samples melting point and enthalpy of fusion in the bombarded samples, as analyzed by differential scanning calorimetry (DSC), is associated with changes in the crystalline morphology and with an increase in the polymer disordered regions. Those facts are confirmed also by a large decrease in the main x-ray diffraction peak amplitude as the fluence increases. A model of ion induced amorphization originally constructed for metals and semiconductors was applied and cross-sections for the process were obtained. The experimental data are well fitted using this model based on amorphization through the overlap of damage clusters, but an exclusive elastic collisions mechanism for the damage production cannot be inferred