Temperature gradient method of nonuniformly poling a body of polymeric piezoelectric material and novel flexure elements produced thereby

A method of nonuniformly poling a body of polymeric piezoelectric material, comprising the steps of:

• establishing a temperature gradient of greater than about 10.degree. C. and less than about 100.degree. C., the lower temperature being greater than the glass transition temperature of the material and the higher temperature being less than the melting point of the material, across the thickness of the material;
• applying an electric field across the thickness of the material from one surface to another surface in an amount and for a time sufficient to nonuniformly polarize the material, the stronger polarization occurring near the colder surface;
• and reversing the direction of the temperature gradient and the polarity of the applied electric field for a time sufficient to polarize the portion of the material near the cold surface without substantially affecting the previously polarized portion of the material.

A body of nonuniformly poled polymeric piezoelectric material produced by the process of establishing a temperature gradient of greater than about 10.degree. C. and less than about 100.degree. C., the lower temperature being greater than the glass transition temperature of the material and the higher temperature being less than the melting point of the material, across the thickness of the material from one surface to another to thereby create a colder surface and a warmer surface;

• and applying an electric field across the thickness of the material, said nonuniformly poled material being characterized by having a stronger polarization in a portion near said colder surface.

A body of nonuniformly poled polymeric piezoelectric material produced by the process of establishing a temperature gradient of greater than 10.degree. C. and less than about 100.degree. C., the lower temperature being greater than the glass transition temperature of the material and the higher temperature being less than the melting point of the material, across the thickness of the material from one surface to another surface;

• applying an electric field across the thickness of the material;
• and reversing the polarity of the temperature gradient and the polarity of the applied electric field, said nonuniformly poled material being characterized by being polarized in a first direction in a portion near one surface thereof and being polarized in a direction opposite said first direction in a portion near the opposite surface thereof.

A flexure element comprising a sheet of nonuniformity poled polymeric piezoelectric material having stronger average polarization in a portion near one surface than in a portion near the opposite surface thereof, and said stronger polarization being in a direction inward from said surface.

A flexure element comprising a sheet of nonuniformly poled polymeric piezoelectric material having oppositely directed polarization in portions near opposite surfaces thereof and directed in an inward direction from said surfaces.