{'fraction_non_alphanumeric': 0.02768549280177187, 'fraction_numerical': 0.0022148394241417496, 'mean_word_length': 5.796992481203008, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Influence of surface modifications with orthophosphoric acid on the charge stability of polypropylene electrets

It is known that both, physico-chemical surface modification and thermal treatment, can lead to enhanced electret properties of dielectric polymers. To further investigate the influence of surface modifications on charge storage in polypropylene (PP) electrets, a combined thermal and chemical treatment with orthophosphoric acid (H3PO4) is applied to PP films. Charged samples are then studied by means of thermally-stimulated-discharge (TSD) experiments, contact-angle measurements and Fourier-transform infrared (FTIR) spectroscopy. From the results, it can be concluded that additional deeper traps have been formed along with the treatment-induced conformation variations on the surface of the PP films. The new traps significantly improve the surface charge-stability of PP electrets.