Method to double the piezo-and pyroelectric of polyvinylidine fluoride (PVDF) films
November 13, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod for production of composite piezoelectric material Piezoelectric and pyroelectric polymer film and process for preparing same Process for manufacturing a piezoelectric transducer made from a polymer material Process for manufacturing electromechanical transducers using at least one polymer film Process for producing piezoelectric polymer films Extrusion of films of vinylidene fluoride polymers Piezoelectric and pyroelectric film Articles comprising stabilized piezoelectric vinylidene fluoride polymers Die drawing process and apparatus for piezoelectric polymer films and tubes Patent #: 4800048 InventorAssigneeApplicationNo. 791275 filed on 11/13/1991US Classes:264/435, Molecular aligning or molecular orientating (e.g., poling, etc.)264/288.4, Stretching by applying tension264/483, Plasma (e.g., corona, glow discharge, etc.)425/174.8EElectro-staticExaminersPrimary: Thurlow, JefferyAttorney, Agent or FirmForeign Patent References
International ClassB29C 035/00Foreign Application Priority Data1990-12-11 CAAbstractPolyvinylidene fluoride (PVDF) films and co-polymers thereof possess the highest values of piezoelectric and pyroelectric constants of any known polymer. These films, up to present, have been first subjected to stretching and then to a high electric field (or corona charge) at an elevated temperature to provide a maximum piezoelectric constants (d31) of about 30-35 pC/N and a maximum pyroelectric constants (p) of about 3.5 nC/cm2 K. It has now been found that the piezoelectric constant d31 and pyroelectric constant p of these films can be increased up to about 60 pC/N and 6 nC/cm2 K respectively when they are subjected to simultaneously stretching and corona poling with a poling field Ep =0.55MV/cm, a stretching ratio S.R.=4.5X and a poling temperature Tp =80° C. | |
