Procedure for production of piezoelectric and pyroelectric films - by electrical polarisation of polyvinylidene fluoride films

摘要

Procedure for the production of peizoelectric and pyroelectric films by the electrical polarisation of polyvinyl fluoride films using voltage differences of the impulse type. The voltage differences have a maximum value of greater than 20 KV with a frequency of 50 Hz and are applied for less than 300 secs. The film is placed between electrodes at least one of which is pointed with a separation less than 15 cm. and kept at a temp. between 50 and 100 deg. C. Pref. the film is a homopolymer or copolymer of vinylidene fluorate containing less than 10% molar units derived from trifluoroethylene, tetrafluoroethylene, chloro-trifluoroethylene and hexafluoropropylene. Piezoelectric and pyroelectric films of thickness less than 1 mm and preferably less than 100 microns. Film is tested for a short time generally less than 10 mins. /5.