Method of forming a molecularly polarized polmeric sheet into a non-planar shape

• US 4,985,195 A
• Filed: 12/20/1988
• Issued: 01/15/1991
• Est. Priority Date: 12/20/1988
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Roman, Paul F., Wilson, David T., Dionesotes, Neil T.
• Primary Examiner(s): Lowe, James
• Application Number:
  US07/286,901
• Time in Patent Office: 756 Days
• Field of Search: 264/22, 264/320
• US Class Current: 264/320
• CPC Class Codes: B29C 51/002 characterised by the choice of material
• CPC Class Codes: B29C 53/005 characterised by the choice of material B29C53/36 and B29C53/56 take precedence
• CPC Class Codes: B29C 53/04 of plates or sheets B29C63/04 takes precedence; bending or folding paper B31F1/0003; folding films B65H45/00
• CPC Class Codes: B29C 53/12 helically, e.g. for making springs for textile fibres D02G1/00
• CPC Class Codes: B29C 53/382 using laminated sheets
• CPC Class Codes: B29C 53/42 using internal forming surfaces, e.g. mandrels
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29K 2027/12 containing fluorine
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: B29L 2009/00 Layered products
• CPC Class Codes: B29L 2023/22 Tubes or pipes, i.e. rigid bent tubes not for use as pipe couplings B29L2023/004
• CPC Class Codes: H10N 30/098 Forming organic materials

Abstract

A method for forming sheets of polarized PVDF into non-planar shaped bodies is described. The technique includes the steps of shaping the polymer material by disposing a sheet of the polymer material about a non-planar surface and subjecting the sheet of polymer material and said non-planar surface to an elevated temperature for a predetermined period of time until said non-planar shape is permanently imparted to the sheet of molecularly polarized polyvinylidenefluoride material.

Claims

1. A method of forming a sheet of molecularly polarized polymer material into a non-planar shape after said material has been molecularly polarized, comprises the steps of:

disposing said sheet of polymer material about a mold having a selected non-planar shape selected to impart a desired non-planar shape to said sheet; and

heating said sheet and mold to an elevated temperature above the thermal setting temperature of the material but below the piezoelectric transition temperature of the material for a predetermined period of time.

2. The method of claim 1 wherein said heating step occurs at a temperature of about 90°

C. for about 6 hours.

3. The method of claim 1 wherein said mold includes a pair of members having mutually complimentary shaped surfaces and said disposing step comprises the step of pressing said sheet between the pair of non-planar mutually complimentary shaped members.

4. The method of claim 2 wherein during said pressing step the pair of non-planar mutually complimentary shaped members are a first member having a concave surface and a second member having a convex surface, and said concave surface and said convex surfaces are disposed over said sheet of material to impart to at least a portion of said sheet of material a hemispherical surface.

5. The method of claim 4 wherein said heating step occurs at an elevated temperature of 90°

C. for about 6 hours.

6. The method of claim 1 wherein said mandrel is an elongated tubular member and wherein said disposing step comprises the step of winding said sheet about said elongated tubular member.

7. The method of claim 6 wherein said heating step occurs at an elevated temperature of 90°

C. for about 6 hours.

8. The method of claim 1 wherein said disposing step comprises the step of inserting said sheet of material into a mold to let the sheet be confined by the interior of the mold.

9. The method of claim 8 wherein the mold is a hollow elongated member.

10. The method of claim 9 wherein the heating step occurs at a temperature of 90°

C. for about 6 hours.

11. A method of forming a sheet of molecularly polarized polyvinylidenefluoride into a non-planar shape comprises the steps of:

disposing the sheet of polarized PVDF about a mandrel having a desired complimentary non-planar shape;

heating said polarized sheet disposed about the mandrel by subjecting the sheet and mandrel to an elevated temperature in the range of about 60°

C. to 100°

C. for a period of time of about 1 hour to 24 hours; and

removing said sheet of polyvinylidenefluoride having imparted thereto the desired non-planar shape.

12. The method as recited in claim 11 wherein the heating step occurs at a temperature in the range of about 88°

C. to 92°

C. for a period of time about 5 hours to 7 hours.

13. The method as recited in claim 12 wherein after the removing step, the method includes the steps of providing electrode surfaces over opposing major surfaces of said nonplanar shaped body.