Polyethylene terephthalate capacitor film doping: Selection of conditions

Polyethylene terephthalate (PET) film has good dielectric properties but high radiation-induced conductivity, which can be reduced by doping commercially available electrical insulation films with small electron-trapping molecules. This study investigates the doping process of PET-CE capacitor film (State Standard 24234-80) using fluorenone-based dopants, such as 2,7-dinitro-9-fluorenone (DNF) and 2,5,7-trinitro-9-fluorenone (TNF), and focusing on the role of the solvent (ethylene glycol and benzyl alcohol). The optimal doping temperature range was selected to be between the glass transition temperature of the doping polymer (88 ° С for PET, lower limit) and the boiling point of the solvent (upper limit). The appropriate solvent and dopant solution concentrations were determined. Based on the experimental results, ethylene glycol and benzyl alcohol were selected as solvents for TNF and DNF, respectively. The following solvent selection criteria for doping systems were established: high boiling point, high dopant solubility, and low affinity for the polymer matrix.