Pre-stressing of heat treated liquid crystalline polymer fiber to improve modulus
AssigneeHolechst Celanese Corporation
InventorsGeorge Collins, William M. Pleban, Frank Haimbach, IV, John A. Flint
Life of this patent
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Abstract
The tensile modulus of fibers made from liquid crystalline polymers comprising 6-oxy-2-naphthoate and 4-oxybenzoate monomer units that have been heat treated can be increased by applying and then releasing a stress at room temperature in the range of about 25% to about 90% of the tensile strength of the heat treated fiber to yield a "pre-stressed" fiber.
Claims21
A method of increasing the modulus of a heat treated fiber of an aromatic liquid crystalline polymer, comprising the steps of:
- (a) applying a stress to the heat treated fiber at a temperature in the range of about 10.degree. C. to about 40.degree. C., said stress being in the range of about 10% to about 90% of the tensile strength of said heat treated fiber;
- and
- (b) releasing said stress to yield a pre-stressed fiber having a modulus higher than the modulus of said heat treated fiber, wherein said aromatic liquid crystalline polymer comprises monomer units I and II, where
- I is ##STR8## and II is ##STR9## wherein one or more of monomer units I and II may optionally include substituents for one or more of the hydrogen atoms on the aromatic ring selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, fluorinated alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, halogen atoms, phenyl groups and mixtures thereof.
A method of increasing the modulus of a heat treated fiber of an aromatic liquid crystalline polymer, comprising the steps of:
- (a) applying a stress to the heat treated fiber at a temperature in the range of about 10.degree. C. to about 40.degree. C., said stress being in the range of about 10% to about 90% of the tensile strength of said heat treated fiber;
- and
- (b) releasing said stress to yield a pre-stressed fiber having a modulus higher than the modulus of said heat treated fiber,
- wherein said aromatic liquid crystalline polymer consists essentially of about 10 mole % to about 90 mole % of monomer unit I and about 90 mole % to about 10 mole % of monomer unit II, where
- I is ##STR15## and II is ##STR16## wherein one or more of monomer units I and II may optionally include substituents for one or more of the hydrogen atoms on the aromatic ring selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, fluorinated alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, halogen atoms, phenyl groups and mixtures thereof.
Dependencies are inferred from the claim text.