Sheets of stretched and polarized polymer materials and method of manufacturer
First Claim
1. A sheet comprising:
- a molecularly polarized polymer material having a multilayered structure comprising;
a pair of outer surface layers of said sheet each surface layer having a first modulus of elasticity, a first density, a first hydrostatic charge sensitivity and a first relative permittivity; and
an inner region of said sheet disposed between said pair of outer surface layers of the sheet having a second modulus of elasticity which is lower than the modulus of elasticity of each of said pair of outer surface layers, a second density which is lower than the density of said pair of outer surface layers, a second hydrostatic charge sensitivity which is higher than the hydrostatic charge sensitivity of said pair of outer surface layers, and a relative permittivity which is lower than the relative permittivity of said pair of outer surface layers.
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Abstract
A sheet of polymer material is secured between a pair of clamping members. The sheet is directed through a localized heated region to provide a localized heated portion of said sheet. A first one of said clamping members is pulled away from the second clamping members to stretch said sheet and create from the localized heated portion of said sheet a neck-down region. The neck-down region separates providing a pair of neck-down region portions and a reduced thickness portion or stretched portion of the sheet between said neck-down region portions. One of said neck-down regions propagates along unstretched portions of the sheet as the movable clamping member moves away from the fixed clamping member while the other neck-down region remains adjacent the fixed member. This propagating neck-down region portion of the sheet is kept within the localized heated region by moving the localized heated region at a rate related to the rate which unstretched material of the sheet is fed into the neck-down region portion. While the neck-down region portion is maintained within the localized heated region, an electric field is applied to the neck-down region portion to polarize the film.
53 Citations
13 Claims
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1. A sheet comprising:
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a molecularly polarized polymer material having a multilayered structure comprising; a pair of outer surface layers of said sheet each surface layer having a first modulus of elasticity, a first density, a first hydrostatic charge sensitivity and a first relative permittivity; and an inner region of said sheet disposed between said pair of outer surface layers of the sheet having a second modulus of elasticity which is lower than the modulus of elasticity of each of said pair of outer surface layers, a second density which is lower than the density of said pair of outer surface layers, a second hydrostatic charge sensitivity which is higher than the hydrostatic charge sensitivity of said pair of outer surface layers, and a relative permittivity which is lower than the relative permittivity of said pair of outer surface layers. - View Dependent Claims (2, 3)
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4. A sheet comprising:
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a molecularly polarized polymer material with said sheet having a multilayered cross section comprising; a first outer surface layer having a first modulus of elasticity and a first density; a second outer surface layer having a second modulus of elasticity and a second density; and an inner region layer disposed between said first and second outer surface layers having a third modulus of elasticity and a third density; wherein said first and second moduli are each higher than the third modulus, and the first and second density are each higher than the third density. - View Dependent Claims (5, 6, 7)
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8. A sheet comprising:
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a molecularly polarized polymer material having a multilayered cross-section with first and second outer surface regions, each having a first density and first hydrostatic charge sensitivity and an inner region disposed between said first and second outer surface regions having a second lower, density than said first density and second hydrostatic charge sensitivity; and said sheet having a substantially constant hydrostatic charge sensitivity as a function of operating temperature over the temperature range of 25°
C. to 90°
C. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification