Method of making hollow fiber with gradient properties

Patent metadata

Field	Value
Publication number	US-10774447-B2
Application number	US-201916377257-A
Country	US
Kind code	B2
Filing date	Apr 8, 2019
Priority date	Dec 10, 2011
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

There is provided a method of making a hollow fiber. 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, and spinning the inner-volume portion mixture and the outer-volume portion mixture to form a precursor fiber. The method further includes heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber, and during heating, extracting the fugitive polymer from the inner-volume portion mixture. The method further includes obtaining the 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, 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, to form an inner-volume portion mixture;
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 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 during heating, extracting the fugitive polymer from the inner-volume portion mixture; 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 a 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 mixing, in the first solvent, the plurality of nanostructures, the one or more first polymers, and the fugitive polymer further comprises, mixing the one or more first polymers comprising 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 mixing, in the second solvent, the one or more second polymers further comprises, mixing the one or more second polymers comprising a polymer comprising polyacrylonitrile (PAN), pitch, polyphenylene sulfide (PPS), viscose, cellulose, polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), or combinations thereof.

5. The method of claim 1 , wherein mixing in the first solvent and mixing in the second solvent further comprise, mixing in the first solvent and mixing in the second solvent, wherein each of the first solvent and the second solvent comprises 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).

6. The method of claim 1 , wherein mixing, in the first solvent, the plurality of nanostructures, the one or more first polymers, and the fugitive polymer further comprises, mixing the fugitive polymer comprising polymethylmethacrylate, polyvinyl alcohol, polyethylene oxide, polyacrylamide, polylactic acid, polystyrene, polyester, or water-soluble copolyester resins, copolymers, terpolymers, or mixtures thereof.

7. The method of claim 1 , wherein mixing, in the first solvent, the plurality of nanostructures, the one or more first polymers, and the fugitive polymer further comprises, mixing the plurality of nanostructures comprising carbon nanostructures, nanotubes, carbon nanotubes, halloysite nanotubes, or boron nitride nanotubes.

8. The method of claim 1 , wherein spinning the inner-volume portion mixture and the outer-volume portion mixture further comprises, spinning comprising solution spinning, gel spinning, wet spinning, electrospinning, dry spinning, or combinations there.

9. The method of claim 1 , wherein obtaining the hollow fiber further comprises, obtaining the hollow fiber where 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.

10. The method of claim 1 , wherein heating the precursor fiber comprises heating the precursor fiber at a temperature in a range of from 600 degrees Celsius to 3000 degrees Celsius.

11. The method of claim 1 , wherein extracting the fugitive polymer during heating further comprises, extracting the fugitive polymer via diffusion through one or more of, the plurality of nanostructures, and the one or more first polymers.

12. A method of making a continuous-filament hollow finished fiber, 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;
heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber, and during heating, decomposing and removing the fugitive polymer from the inner-volume portion mixture; 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 a fiber-matrix interface.

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

14. The method of claim 12 , wherein decomposing and removing the fugitive polymer during heating further comprises, removing the decomposed fugitive polymer via diffusion through one or more of, the plurality of nanostructures, and the one or more first polymers.

Assignees

• Boeing Co

Inventors

• Tsotsis Thomas Karl

Classifications

• B29C48/09

  Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels · CPC title

• Y10T428/2975

  Tubular or cellular · CPC title

• B29C48/022

  characterised by the choice of material · CPC title

• D01D5/06

  Wet spinning methods {(D01D5/0046 takes precedence)} · CPC title

• B29C48/21

  the layers being joined at their surfaces · CPC title