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US-12624500-B2 - Extraction of delignified, cellulose-based fibers from natural plant material, and materials incorporating such fibers

US12624500B2US 12624500 B2US12624500 B2US 12624500B2US-12624500-B2

Abstract

A piece of natural plant material is subjected to one or more chemical treatments to remove substantially all lignin therefrom, thereby allowing the extraction of delignified, cellulose-based fibers. For example, the natural plant material can be a grass, such as bamboo or gladiolus. Subsequent drying of the extracted fiber densifies the structure, yielding improved mechanical properties. In some embodiments, the extracted fibers can be used, either alone or in combination with other materials, as a structural material. For example, the extracted fibers can be embedded within, infiltrated with, coated by, or otherwise combined with a polymer or concrete to form a composite material.

Inventors

  • Liangbing Hu
  • Chaoji CHEN
  • Zhihan LI
  • Jianguo Li

Assignees

  • UNIVERSITY OF MARYLAND, COLLEGE PARK

Dates

Publication Date
20260512
Application Date
20210421

Claims (20)

  1. 1 . A composite material comprising: a structural matrix; and a plurality of delignified, cellulose-based macrofibers disposed within the structural matrix, each cellulose-based macrofiber having been chemically-extracted intact from a matrix of lignin and hemicellulose that joined microfibrils of one or more macrofibers to parenchyma cells in a microstructure of a respective piece of natural bamboo, wherein a content of lignin in each cellulose-based macrofiber is less than or equal to 4 wt %, each cellulose-based macrofiber is separate and distinct from any other cellulose-based macrofiber extracted from the natural bamboo, each cellulose-based macrofiber has a moisture content less than or equal to 10 wt % and exhibits a tensile strength of at least 1 GPa, and each cellulose-based macrofiber has a length of at least 5 cm, a diameter of at least 100 μm, and a density of at least 1 g/cm 3 .
  2. 2 . The material of claim 1 , wherein the structural matrix comprises a polymer or concrete.
  3. 3 . The material of claim 1 , wherein a content of the plurality of the cellulose-based macrofibers within the composite material is at least 0.1 wt %.
  4. 4 . The material of claim 1 , wherein each cellulose-based macrofiber has a specific strength of at least 0.5 GPa·cm 3 /g, a crystallinity of at least 40%, a Young's modulus of at least 20 GPa, or any combination of the foregoing.
  5. 5 . The material of claim 1 , wherein each cellulose-based macrofiber has a cellulose content of at least 70 wt % and a hemicellulose content less than or equal to 10 wt %.
  6. 6 . The material of claim 1 , wherein provided on or within each cellulose-based macrofiber is a conductive additive, a magnetic additive, a piezoelectric material, a stimuli-responsive material, a catalytic material, or any combination of the foregoing.
  7. 7 . The material of claim 2 , wherein: the polymer comprises epoxy resin, polyvinyl alcohol (PVA), polyethylene glycol (PEO), polyamide (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyacrylonitrile (PAN), polycaprolactam (PA6), poly(m-phenylene isophthalamide) (PMIA), poly-p-phenylene terephthalamide (PPTA), polyurethane (PU), polycarbonate (PC), polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), poly(butylene succinate-co-butylene adipate) (PBSA), polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(glycolic acid) (PGA), polypyrrole (PPy), polythiophene (PTh), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene vinyl alcohol (EVOH), poly(vinylidene chloride) (PVDC), polyxylylene adipamide (MXD6), polyethylene (PE), polyvinyl chloride (PVC), poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS), polyimide (PI), polyethylenimine (PEI), polylactic acid (PLA), octadecyltrichlorosilane (OTS), polyoctahedral silsesquioxane (POSS), paramethylstyrene (PMS), polydimethylsiloxane (PDMS), poly(ethylene naphthalate (PEN), a graft copolymer of acrylonitrile-butadiene-styrene-methylmethacrylate (ABSM), dodecyltrimethoxysilane (DTMS), rosin, chitin, chitosan, protain, plant oil, carboxymethyl cellulose, cellulose acetate, starch, agar, alginic acid, or any combination of the foregoing; or the concrete comprises Portland cement, agro-concrete, magnesium carbonate (MgCO 3 ), magnesium hydroxide (Mg(OH) 2 ), or any combination of the foregoing.
  8. 8 . The material of claim 1 , wherein: the length of each cellulose-based macrofiber is between 5 cm and 200 cm, inclusive; each cellulose-based macrofiber has a crystallinity of at least 50%; and each cellulose-based macrofiber has a Young's modulus of at least 60 GPa.
  9. 9 . The material of claim 1 , wherein: the microstructure of the natural bamboo has lumina formed at least in part by the matrix and the parenchyma cells, and the one or more delignified, cellulose-based macrofibers lack such lumina; and the natural bamboo has an aligned ordered structure for the microfibrils therein, and each cellulose-based macrofiber retains the aligned ordered structure for the microfibrils.
  10. 10 . The material of claim 1 , wherein the density of each cellulose-based macrofiber is about 1.45 g/cm 3 .
  11. 11 . A method comprising: (a) subjecting a piece of natural bamboo to one or more chemical treatments so as to remove lignin therefrom, at least one of the one or more chemical treatments comprising partial or full immersion in one or more chemical solutions, the natural bamboo having a microstructure with a plurality of cellulose-based macrofibers, parenchyma cells, and a matrix of lignin and hemicellulose that joins microfibrils of the cellulose-based macrofibers to the parenchyma cells, the one or more chemical treatments being effective to dissolve the matrix and break down the parenchyma cells such that the cellulose-based macrofibers are released; (b) after (a), extracting from the chemically-treated piece the plurality of cellulose-based macrofibers as individual, intact cellulose-based macrofibers separate and distinct from each other; (c) after (b), drying the cellulose-based macrofibers such that evaporation of water from each cellulose-based macrofiber causes self-densification thereof; and (d) after (c), embedding each cellulose-based macrofiber within a structural matrix to form a composite material, wherein, after (c): a content of lignin in each cellulose-based macrofiber is less than or equal to 4 wt %, each cellulose-based macrofiber has a moisture content less than or equal to 10 wt % and exhibits a tensile strength of at least 1 GPa, and each cellulose-based macrofiber has a length of at least 5 cm, a diameter of at least 100 μm, and a density of at least 1 g/cm 3 .
  12. 12 . The method of claim 11 , wherein (a) comprises: (a1) immersing at least a first portion of the piece of natural bamboo within a first solution to remove some of the lignin in the immersed first portion; and (a2) after (a1), immersing at least the first portion within a second solution to remove remaining lignin in the immersed first portion.
  13. 13 . The method of claim 12 , wherein the first solution comprises peroxyformic acid (CH 2 O 3 ).
  14. 14 . The method of claim 13 , wherein the second solution comprises sodium hydroxide (NaOH) or potassium hydroxide (KOH).
  15. 15 . The method of claim 12 , wherein the first solution comprises a mixture of potassium hydroxide (KOH) and sodium sulfite (Na 2 SO 3 ), a mixture of potassium hydroxide (KOH) and sodium sulfide (Na 2 S), a mixture of sodium hydroxide (NaOH) and sodium sulfite (Na 2 SO 3 ), or a mixture of sodium hydroxide (NaOH) and sodium sulfide (Na 2 S).
  16. 16 . The method of claim 15 , wherein the second solution comprises a mixture of hydrogen peroxide (H 2 O 2 ) and acetic acid (C 2 H 4 O 2 ), or a mixture of hydrogen peroxide (H 2 O 2 ) and formic acid (CH 2 O 2 ).
  17. 17 . The method of claim 11 , wherein the structural matrix comprises a polymer or concrete.
  18. 18 . The method of claim 11 , wherein (b) comprises agitating the chemically-treated piece in solution.
  19. 19 . The method of claim 11 , wherein the one or more chemical solutions comprise an alkaline solution.
  20. 20 . The method of claim 11 , wherein a volume of each cellulose-based macrofiber after (c) is at least 10% less than a volume thereof prior to (c).

Description

CROSS-REFERENCE TO RELATED APPLICATION The present application claims the benefit of U.S. Provisional Application No. 63/013,401, filed Apr. 21, 2020, entitled “Strong, Delignified Fibers, Methods of Making and Using the Same,” and U.S. Provisional Application No. 63/065,994, filed Aug. 14, 2020, entitled “Decoupled Fluidic Transport Materials and Methods of Preparing the Same,” each of which is incorporated by reference herein in its entirety. FIELD The present disclosure relates generally to processing of naturally-occurring cellulose-based materials, and more particularly, to extraction of delignified, cellulose-based fibers from fibrous plant materials and use thereof in structural materials and devices. SUMMARY Embodiments of the disclosed subject matter provide a simple, cost-effective “top-down” method of fabricating strong, tough fibers by chemically-extracting cellulose-based macrofibers (e.g., having a diameter of at least 5 μm) from natural plant materials. For example, the natural plant material can be bamboo, gladiolus, reed, or other grasses. In some embodiments, the fabrication method comprises a two-step delignification process. In a first step, the natural plant material is treated with an alkali solution of one or more chemicals in order to partially remove lignin and hemicellulose from the plant material. In a second step, the partially-delignified plant material can be treated with a different solution of one or more chemicals in order to further remove lignin and hemicellulose. Alternatively, in some embodiments, the fabrication method comprises a single-step delignification process using a single solution of one or more chemicals. In either case, the delignified plant material can be rinsed and agitated, resulting in release of the cellulose-based macrofibers from each other. In some embodiments, subsequent drying of the released macrofibers can result in self-densification, which can further improve the mechanical properties of the macrofibers. The resulting macrofibers can be employed as independent structural components (e.g., rope, cable, etc.) or as reinforcement to a matrix or base material (e.g., forming a composite material). Any of the various innovations of this disclosure can be used in combination or separately. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will hereinafter be described with reference to the accompanying drawings, which have not necessarily been drawn to scale. Where applicable, some elements may be simplified or otherwise not illustrated in order to assist in the illustration and description of underlying features. Throughout the figures, like reference numerals denote like elements. FIG. 1 is an exemplary process flow diagram for a method of extracting and using delignified, cellulose-based macrofibers from natural plant material, according to one or more embodiments of the disclosed subject matter. FIG. 2A is a simplified schematic diagram of a delignified, cellulose-based macrofiber extracted from natural plant material, according to one or more embodiments of the disclosed subject matter. FIGS. 2B-2D illustrate exemplary configurations for multiple delignified macrofibers as a bundle, one-dimensional array, and a two-dimensional array, respectively, according to one or more embodiments of the disclosed subject matter. FIGS. 3A-3D illustrate exemplary configurations for composite materials incorporating delignified macrofibers disposed in a non-woven configuration, a biaxial weave, a triaxial weave, and a knitted weave, according to one or more embodiments of the disclosed subject matter. FIG. 4A is a simplified schematic diagram illustrating infiltration of a polymer to delignified macrofibers to form a composite material, according to one or more embodiments of the disclosed subject matter. FIG. 4B is a simplified schematic diagram illustrating an exemplary setup for vacuum-assisted resin-transfer molding (VARTM), according to one or more embodiments of the disclosed subject matter. FIG. 5A is a simplified partial cut-away view of a natural bamboo segment from which cellulose-based fibers can be extracted, according to one or more embodiments of the disclosed subject matter. FIG. 5B is a top view image of a cross-section of a natural bamboo segment. FIG. 5C is a magnified image of the culm of the natural bamboo segment of FIG. 5B. FIG. 5D is a further magnified scanning electron microscope (SEM) image showing the hier