Method of making hollow fiber with gradient properties

Patent metadata

Field	Value
Publication number	US-10253433-B2
Application number	US-201715441174-A
Country	US
Kind code	B2
Filing date	Feb 23, 2017
Priority date	Dec 10, 2011
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

There is provided a method of making a hollow fiber having improved resistance to microfracture formation at a fiber-matrix interface. The method includes mixing in a first solvent a plurality of nanostructures, one or more first polymers, and a fugitive polymer which is dissociable from the nanostructures and the one or more first polymers, to form an inner-volume portion mixture. The method further includes mixing in a second solvent one or more second polymers to form an outer-volume portion mixture, spinning the inner-volume portion mixture and the outer-volume portion mixture and extracting the fugitive polymer from the inner-volume portion mixture to form a precursor fiber, heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber, and obtaining a hollow fiber with the inner-volume portion having the nanostructures and the first polymers, and with the outer-volume portion having the second polymers.

First claim

What is claimed is:

1. A method of making a hollow fiber having improved resistance to microfracture formation at a fiber-matrix interface, the method comprising:
mixing in a first solvent a plurality of nanostructures, one or more first polymers, and a fugitive polymer which is dissociable from the nanostructures and the one or more first polymers, in order to form an inner-volume portion mixture;
mixing in a second solvent one or more second polymers in order to form an outer-volume portion mixture;
spinning the inner-volume portion mixture and the outer-volume portion mixture and extracting the fugitive polymer from the inner-volume portion mixture in order to form a precursor fiber;
heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber; and
obtaining the hollow fiber comprising:
an inner-volume portion having a first-core portion with the nanostructures and with the one or more first polymers being oriented in a direction parallel to a longitudinal axis of the hollow fiber, the inner-volume portion further having one or more hollow second-core portions, the first-core portion being in contact with and encompassing the one or more hollow second-core portions, and
an outer-volume portion having the one or more second polymers, the outer-volume portion being in contact with and completely encompassing the inner-volume portion,
wherein the inner-volume portion has at least one of a tensile modulus and a strength that are higher than at least one of a tensile modulus and a strength of the outer-volume portion, resulting in the hollow fiber having improved resistance to microstructure formation at the fiber-matrix interface.

2. The method of claim 1 further comprising curing a resin matrix to a plurality of the hollow fibers to form a composite part.

3. The method of claim 1 wherein the one or more first polymers and the one or more second polymers each comprise a polymer comprising polyacrylonitrile (PAN), pitch, polyphenylene sulfide (PPS), viscose, cellulose, polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), or combinations thereof.

4. The method of claim 1 wherein the first solvent and the second solvent each comprise a solvent comprising dimethylacetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethyl sulfone (DMSO 2 ), ethylene carbonate, propylene carbonate (PPC), chloroacetonitrile, dimethyl phosphate (DDVP), or acetic anhydride (Ac 2 O).

5. The method of claim 1 wherein the fugitive polymer comprises polymethylmethacrylate, polyvinyl alcohol, polyethylene oxide, polyacrylamide, polylactic acid, polystyrene, polyester, or water-soluble copolyester resins, copolymers, terpolymers, or mixtures thereof.

6. The method of claim 1 wherein the nanostructures comprise carbon nanostructures, nanotubes, carbon nanotubes, halloysite nanotubes, or boron nitride nanotubes.

7. The method of claim 1 wherein the spinning comprises solution spinning, gel spinning, wet spinning, electrospinning, dry spinning, or combinations there.

8. The method of claim 1 wherein the one or more hollow second-core portions comprise a single hollow second-core portion configuration extending through a length of the hollow fiber or a plurality of hollow second-core portions configuration extending through a length of the hollow fiber to form an islands-in-a-sea configuration.

9. A method of making a continuous-filament hollow finished fiber having improved resistance to microfracture formation at a fiber-matrix interface, the method comprising:
forming an inner-volume portion mixture comprising:
a first solvent;
a plurality of nanostructures selected from the group consisting of nanotubes, carbon nanotubes, halloysite nanotubes, and boron nitride nanotubes;
a first polymer selected from the group consisting of polyacrylonitrile (PAN), pitch, polyphenylene sulfide (PPS), viscose, cellulose, polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), and combinations thereof; and
a fugitive polymer which is dissociable from the plurality of nanostructures and the first polymer;

forming an outer-volume portion mixture comprising:
a second solvent; and
a second polymer selected from the group consisting of polyacrylonitrile (PAN), pitch, polyphenylene sulfide (PPS), viscose, cellulose, polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), and combinations thereof;

forming a precursor fiber by spinning the inner-volume portion mixture and the outer-volume portion mixture and extracting the fugitive polymer from the inner-volume portion mixture;
heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber; and
obtaining the continuous-filament hollow finished fiber comprising:
an inner-volume portion having a first-core portion with the plurality of nanostructures and with the first polymer, the plurality of nanostructures substantially aligned along a longitudinal axis of the continuous-filament hollow finished fiber and polymer chains of the first polymer oriented in a direction parallel to the longitudinal axis of the continuous-filament hollow finished fiber; and one or more hollow second-core portions, the first-core portion being in contact with and encompassing the one or more hollow second-core portions; and
an outer-volume portion having the second polymer, the outer-volume portion being in contact with and completely encompassing the inner-volume portion,
wherein the inner-volume portion of the continuous-filament hollow finished fiber has a greater tensile modulus and/or tensile strength than the outer-volume portion of the continuous-filament hollow finished fiber, resulting in the continuous-filament hollow finished fiber having improved resistance to microstructure formation at the fiber-matrix interface.

10. The method of claim 9 wherein forming the inner-volume portion mixture and forming the outer-volume portion mixture further comprise using the same first polymer and second polymer in the inner-volume portion mixture and the outer-volume portion mixture, respectively.

11. The method of claim 10 wherein forming the inner-volume portion mixture and forming the outer-volume portion mixture further comprise using the same first polymer and the second polymer each comprising a solution spinnable polyacrylonitrile (PAN).

12. The method of claim 9 further comprising curing a resin matrix to a plurality of the continuous-filament hollow finished fibers to form a composite part.

13. The method of claim 9 wherein forming the inner-volume portion mixture and forming the outer-volume portion mixture further comprise using the first solvent and the second solvent each comprising dimethylacetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO), dimethyl sulfone (DMSO 2 ), ethylene carbonate, propylene carbonate (PPC), chloroacetonitrile, dimethyl phosphate (DDVP), or acetic anhydride (Ac 2 O).

14. The method of claim 9 wherein forming the inner-volume portion mixture comprises using the fugitive polymer comprising polymethylmethacrylate, polyvinyl alcohol, polyethylene oxide, polyacrylamide, polylactic acid, polystyrene, polyester, or water-soluble copolyester resins, copolymers, terpolymers, or mixtures thereof.

15. The method of claim 9 wherein forming the inner-volume portion mixture comprises using the plurality of nanostructures comprising carbon nanotubes.

16. The method of claim 9 wherein forming the precursor fiber further comprises using spinning comprising solution spinning, gel spinning, wet spinning, electrospinning

Assignees

• Boeing Co

Inventors

• Tsotsis Thomas Karl

Classifications

• D01D5/0046

  the fibre formed by coagulation, i.e. wet electro-spinning · CPC title

• D01D5/003

  the material being a polymer solution or dispersion (D01D5/0053 takes precedence) · CPC title

• B29C48/18

  the components being layers · CPC title

• D01F9/14

  by decomposition of organic filaments · CPC title

• Y10T428/24994

  Fiber embedded in or on the surface of a polymeric matrix · CPC title