Structures with circumferentially extending densified fibrous plant material, manufacturing system, method and use thereof - Patents.com

Abstract

The structure can be formed by wrapping one or more densified, lignin-impaired wood veneers wrapped around a central axis. The wrapped wood veneers can form a circumferentially extending wood wall. The adhesive can be provided on one or more surface portions of each wood veneer. The wood veneers can be lignin-impaired by in situ lignin modification, partial delignification, or full delignification. The circumferentially extending wood wall can form a hollow member, for example, a tube, pipe, cup, tank, or bottle. Alternatively, the circumferentially extending wood wall can surround a central member, for example, to form a rod, bat, club, or dowel.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 364,794, entitled “Densified Wood-Based Hollow Structures and Their Production and Use,” filed May 16, 2022, the entirety of which is incorporated herein by reference.

[0002] (Statement Regarding Federally Sponsored Research) This invention was made with Government support under DEAR0001025 awarded by the Department of Energy, Advanced Research Projects Agency-Energy (ARPA-E) and under HR00112320009 awarded by the Defense Advanced Research Projects Agency (DARPA). The United States Government has certain rights in this invention.

[0003] The present disclosure relates generally to the processing of fibrous plant material, and more particularly to structures formed by wrapping densified, lignin-impaired fibrous plant material, such as wood or bamboo veneer. [Background technology]

[0004] In structural applications requiring hollow members, metals (e.g., aluminum) have typically been used due to their relatively strong mechanical properties and existing manufacturing capabilities to form such metals (e.g., by casting) into various sizes and shapes. For example, aluminum tubes have been used in the manufacture and construction of buildings (e.g., facade designs, curtain walls, and / or window frames). Other applications of hollow members, such as for fluid transport, typically use plastics and concrete, as well as metals. However, the manufacture of metal, concrete, and plastic parts can generate greenhouse gas emissions, and plastic waste can be a significant source of pollution. Although wood has been considered a more sustainable alternative to metals, concrete, and plastics, traditional wood-based hollow structures generally have insufficient mechanical properties for such applications. Summary of the Invention [Problem to be solved by the invention]

[0005] Embodiments of the disclosed subject matter may address, among other things, one or more of the problems and shortcomings set forth above. [Means for solving the problem]

[0006] An embodiment of the disclosed subject matter provides a structure having one or more densified, lignin-impaired fibrous plant material veneers forming a circumferentially extending wall. In some embodiments, one or more fibrous plant material veneers are subjected to in situ lignin modification or delignification (e.g., partially or completely), densified by pressing in a direction transverse to the longitudinal growth direction of the fibrous plant material, and then wrapped around or molded around a central axis to form the circumferentially extending wall. In some embodiments, the circumferentially extending wall forms a hollow structure, such as a tube or pipe. Alternatively, in some embodiments, the circumferentially extending wall forms part of a solid structure, such as, for example, a dowel or rod.

[0007] By using veneers wrapped around a central axis at a specific angle, the dimensional limitations of the raw fibrous plant material (e.g., the size of a tree trunk or bamboo stalk) can be overcome, thereby achieving structures of any desired size (e.g., length, diameter, wall thickness, etc.) and shape (e.g., circular, triangular, rectangular, etc.). Furthermore, by appropriately selecting the number of veneer layers forming the fibrous plant material wall, the thickness of the veneer layers and / or walls, the diameter of the structure, and / or the orientation of the cellulose fibers within the veneer layers, the mechanical properties of the resulting structure can be tailored to the desired application. For example, in some embodiments, wood tubes with improved energy absorption properties can be manufactured to take advantage of the weaker directions of wood by exhibiting a unique petal-like failure behavior.

[0008] In one or more embodiments, the structure can include one or more densified, lignin-impaired fibrous plant material veneers wrapped around a central axis to form a circumferentially extending wall.

[0009] In one or more embodiments, the energy absorption system can include a plurality of structures, each of which can include one or more densified, lignin-impaired, fibrous plant material veneers wrapped around a central axis to form a circumferentially extending wall.

[0010] In one or more embodiments, the method can include subjecting one or more natural fibrous plant material veneers to one or more chemical treatments to form one or more lignin-impaired veneers. In some embodiments, the one or more chemical treatments can in situ modify the lignin in the veneer, can partially delignify the veneer, or can fully delignify the veneer. The method can further include compressing the one or more lignin-impaired veneers along a direction transverse to the longitudinal growth direction of the fibrous plant material to form one or more densified, lignin-impaired veneers. The method can also include wrapping the one or more densified, lignin-impaired veneers around a central axis to form a circumferentially extending wall.

[0011] Any of the various innovations of the present disclosure can be used in combination or separately. This summary is provided to introduce in a simplified form a selection of concepts that are further described in the detailed description below. 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 drawings. [Brief description of the drawings]

[0012] Embodiments will now be described with reference to the accompanying drawings, which are not necessarily drawn to scale. Where applicable, some elements may be simplified or otherwise not shown to help illustrate and explain the underlying features. Like reference numbers refer to like elements throughout the drawings. [Figure 1A] FIG. 1A illustrates radial, longitudinal, and rotational cuts of a natural wood, as well as a cross-section of the natural wood in a radial-tangential plane, in accordance with one or more embodiments of the disclosed subject matter. [Figure 1B]FIG. 1B is a simplified schematic diagram of a partially delignified and densified wood veneer in accordance with one or more embodiments of the disclosed subject matter. [Figure 1C] FIG. 1C shows macro-scale and micro-scale images of natural wood veneer and densified, partially delignified wood veneer. [Figure 1D] FIG. 1D is a simplified schematic diagram of lignin modification and densification of wood veneer in accordance with one or more embodiments of the disclosed subject matter. [Figure 1E] FIG. 1E is a simplified schematic diagram illustrating the continuous cutting of veneers from a wood trunk, in accordance with one or more embodiments of the disclosed subject matter. [Figure 1F] FIG. IF is a simplified schematic diagram illustrating a manufacturing setup for forming densified, lignin-impaired wood veneer in accordance with one or more embodiments of the disclosed subject matter. [Figure 1G] FIG. 1G illustrates a simplified partial cutaway view of a natural bamboo segment with a rotated section, in accordance with one or more embodiments of the disclosed subject matter. [Figure 1H] FIG. 1H shows a magnified image (top) of the stem of the natural bamboo segment of FIG. 1G and a further magnified image (bottom) showing the hierarchical microstructure of the stem wall. [Figure 2A] FIG. 2A is a simplified schematic diagram illustrating the wrapping of densified, lignin-impaired wood veneer with cellulose fibers parallel to a central mold axis to form a circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 2B] FIG. 2B is a simplified schematic diagram illustrating a manufacturing setup for simultaneously wrapping multiple densified, lignin-impaired wood veneers with cellulose fibers parallel to a central mold axis to form a multi-layered, circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 2C]FIG. 2C is a simplified schematic diagram illustrating a manufacturing process using a cylindrical mold for wrapping multiple densified, lignin-impaired wood veneers to form a multi-layered, circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 2D] FIG. 2D illustrates the wrapping of multiple densified, lignin-impaired wood veneers with cellulose fibers parallel to a central mold axis to form a cylindrical tube, according to one or more embodiments of the disclosed subject matter. [Figure 2E] FIG. 2E shows macro-scale and micro-scale images of a cylindrical tube fabricated based on the wrapping orientation of FIG. 2D, in accordance with one or more embodiments of the disclosed subject matter. [Figure 2F] FIG. 2F shows an image of cellulose fibers within the cylindrical tube of FIG. 2E. [Figure 3A] FIG. 3A is a simplified schematic diagram illustrating the wrapping of densified, lignin-impaired wood veneer with cellulose fibers at an angle to a central mold axis to form a circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 3B] FIG. 3B is a simplified schematic diagram illustrating a manufacturing setup for simultaneously wrapping multiple lignin-impaired wood veneers with cellulose fibers at an angle to a central mold axis to form a multi-layered, circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 3C] FIG. 3C is a simplified schematic diagram illustrating the wrapping of another densified, lignin-impaired wood veneer with cellulose fibers at another angle relative to the central mold axis to form a multi-layered, circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 4A] FIG. 4A illustrates the wrapping of multiple densified, lignin-impaired wood veneers with cellulose fibers at an angle of approximately 45° to a central mold axis to form a cylindrical tube, in accordance with one or more embodiments of the disclosed subject matter. [Figure 4B] FIG. 4B shows macro-scale and micro-scale images of a cylindrical tube made based on the wrapping orientation of FIG. 4A in accordance with one or more embodiments of the disclosed subject matter. [Figure 4C] FIG. 4C shows images of cellulose fibers in different veneer layers of the cylindrical tube of FIG. 4B. [Figure 4D] FIG. 4D illustrates the wrapping of multiple densified, lignin-impaired wood veneers with cellulose fibers at a 45° intersecting angle to a central mold axis to form a cylindrical tube, according to one or more embodiments of the disclosed subject matter. [Figure 4E] FIG. 4E shows macro-scale and micro-scale images of a cylindrical tube fabricated based on the wrapping orientation of FIG. 4D, in accordance with one or more embodiments of the disclosed subject matter. [Figure 4F] FIG. 4F shows images of cellulose fibers in different veneer layers of the cylindrical tube of FIG. 4E. [Diagram 5] FIG. 5 is a simplified schematic diagram illustrating the wrapping of densified, lignin-impaired wood veneer with cellulose fibers substantially perpendicular to a plane containing the central mold axis to form a circumferentially extending wood wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 6A] FIG. 6A shows a simplified cross-sectional view of a hollow tube formed by wrapping a single densified, lignin-impaired fibrous plant material veneer, according to one or more embodiments of the disclosed subject matter. [Figure 6B] FIG. 6B shows a simplified cross-sectional view of another hollow tube formed by wrapping a single densified, lignin-impaired fibrous plant material veneer, according to one or more embodiments of the disclosed subject matter. [Figure 6C] FIG. 6C shows a simplified cross-sectional view of a hollow tube formed by wrapping multiple densified, lignin-impaired fibrous plant material veneers, according to one or more embodiments of the disclosed subject matter. [Figure 6D]FIG. 6D shows a simplified cross-sectional view of a composite pipe formed by wrapping one or more densified, lignin-impaired fibrous plant material veneers according to one or more embodiments of the disclosed subject matter. [Figure 6E] FIG. 6E is an image of an exemplary tube cross-section that may be formed by wrapping densified, lignin-impaired wood veneer according to one or more embodiments of the disclosed subject matter. [Figure 7A] FIG. 7A shows an energy absorbing structure of circumferentially extending wood walls formed by one or more densified, lignin-impaired wood veneers wrapped around a central axis in accordance with one or more embodiments of the disclosed subject matter. [Figure 7B] FIG. 7B illustrates an exemplary energy absorption behavior of a circumferentially extending wood wall when subjected to an axial compressive load, in accordance with one or more embodiments of the disclosed subject matter. [Figure 7C] FIG. 7C illustrates a petal failure mode at the axial end of the circumferentially extending wood wall of FIG. 7B. [Figure 8A] FIG. 8A is a simplified cross-sectional view of an axial loading structure for use with a circumferentially extending wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 8B] FIG. 8B illustrates an energy absorbing system employing multiple circumferentially extending walls in accordance with one or more embodiments of the disclosed subject matter. [Figure 8C] FIG. 8C illustrates an energy absorbing system employing multiple circumferentially extending walls in accordance with one or more embodiments of the disclosed subject matter. [Figure 9A] FIG. 9A is a simplified cross-sectional view of a closed-ended hollow structure formed by a circumferentially extending wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 9B] FIG. 9B is a simplified cross-sectional view of a closed-ended hollow structure formed by a circumferentially extending wall in accordance with one or more embodiments of the disclosed subject matter. [Figure 9C]FIG. 9C is a simplified cross-sectional view of a solid structure formed by circumferentially extending walls surrounding a central member, in accordance with one or more embodiments of the disclosed subject matter. [Figure 9D] FIG. 9D is a simplified cross-sectional view of a solid structure formed by circumferentially extending walls surrounding a central member, in accordance with one or more embodiments of the disclosed subject matter. [Figure 9E] FIG. 9E is an image of a solid rod made by wrapping multiple densified, lignin-impaired wood veneers around a natural wood core, according to one or more embodiments of the disclosed subject matter. [Figure 9F] FIG. 9F is an image of a solid bat made by wrapping multiple densified, lignin-impaired wood veneers around a natural wood core in accordance with one or more embodiments of the disclosed subject matter. [Figure 10A] FIG. 10A is a simplified process flow diagram illustrating a method for forming a densified, lignin-impaired fibrous plant material veneer according to one or more embodiments of the disclosed subject matter. [Figure 10B] FIG. 10B is a simplified process flow diagram illustrating a method for wrapping one or more densified, lignin-impaired fibrous plant material veneers to form a circumferentially extending wall according to one or more embodiments of the disclosed subject matter. [Figure 11] FIG. 11 is a graph of the compressive strength of cylindrical tubes formed by wrapping densified, partially delignified wood veneer for different manufacturing and tube parameters. [Figure 12A] FIG. 12A is a graph comparing force-displacement curves for a cylindrical tube made of densified, partially delignified wood veneer with the wood fibers parallel to the central mold axis (flat wrapping), a cylindrical tube made of aluminum, and a cylindrical tube made of carbon fiber cloth. [Figure 12B]FIG. 12B is a graph comparing the energy absorption of a cylindrical tube made of densified, partially delignified wood veneer with the wood fibers parallel to the central axis (flat wrapping), a cylindrical tube made of aluminum, and a cylindrical tube made of carbon fiber cloth. [Figure 13A] FIG. 13A is a graph of gas pressure versus time for a cylindrical tube formed from densified, partially delignified wood veneer to determine the gas permeability of the cylindrical tube. [Figure 13B] FIG. 13B is a graph comparing the flexural strength of a cylindrical pipe made of concrete and a cylindrical pipe made of densified, partially delignified wood veneer with the wood fibers parallel to the central mold axis (flat wrapping). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] General Considerations For purposes of this specification, certain aspects, advantages, and novel features of the disclosed embodiments are described herein. The disclosed methods and systems should not be construed as limiting in any way. Instead, the disclosure is directed to all novel and non-obvious features and aspects of the various disclosed embodiments, both alone and in various combinations and subcombinations with each other. The methods and systems are not limited to any particular aspects, features, or combinations thereof, and the disclosed embodiments do not require that any one or more particular advantages exist or problems be solved. Techniques from any embodiment or example can be combined with techniques described in any one or more of the other embodiments or examples. In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are merely illustrative and should not be construed as limiting the scope of the disclosed technology.

[0014] Although some operations of the disclosed methods are described in a particular order for convenient presentation, it should be understood that this method of description encompasses reordering, unless a particular ordering is required by the specific language described below. For example, operations described in sequence may be reordered or performed simultaneously in some cases. Furthermore, for simplicity, the accompanying drawings may not show the various ways in which the disclosed methods may be used in conjunction with other methods. Furthermore, the description may use terms such as "provide" or "achieve" to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the specific implementation and are readily discernible by those skilled in the art.

[0015] Disclosure of numerical ranges should be understood to refer to each discrete point within the range, including the endpoints, unless otherwise indicated. Unless otherwise indicated, all numbers expressing amounts of ingredients, molecular weights, percentages, temperatures, times, and the like, used in this specification or claims should be understood to be modified by the term "about". Thus, unless otherwise implicitly or explicitly indicated, or unless the context is properly understood by those skilled in the art to have a clearer structure, the numerical parameters described are approximations that may depend on the desired properties sought and / or the limits of detection under standard test conditions / methods, as known to those skilled in the art. Whenever the embodiment numbers are directly and explicitly distinguished from the prior art discussed, the embodiment numbers are not approximations unless the word "about" is recited. Whenever "substantially", "approximately", "about", or similar language is explicitly used in conjunction with a particular value, a variation of up to 10% of that value is intended, unless explicitly stated otherwise.

[0016] Directions and other relative references may be used to facilitate the description of the figures and principles herein, but are not intended to be limiting. For example, certain terms such as "inside," "outside," "up," "down," "top," "bottom," "internal," "external," "left," "right," "front," "rear," "rear side," and the like may be used. Such terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated embodiments. However, such terms are not intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, a "top" portion may become a "bottom" portion by simply flipping the object over. Nevertheless, it is still the same portion and the subject remains the same.

[0017] As used herein, "comprising" means "including," and the singular forms "a" or "an" or "the" include plural references unless the context clearly dictates otherwise. The term "or" refers to a single element or a combination of two or more elements of the referenced alternative elements, unless the context clearly dictates otherwise.

[0018] The various components, parameters, operating conditions, and the like described herein may be alternatives, but these alternatives are not necessarily equivalent and / or will function equally well. Nor is it meant to imply that the options are listed in order of preference, unless otherwise indicated. Any of the groups defined below may be substituted or unsubstituted, unless otherwise indicated.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs.Methods and materials similar or equivalent to those described herein can be used in the practice or testing of this disclosure, but suitable methods and materials are described below.The materials, methods, and examples are illustrative only and are not intended to be limiting.Features of the subject matter of this disclosure will become apparent from the following detailed description and the appended claims.

[0020] Terminology Overview The following is provided to facilitate a description of various aspects of the disclosed subject matter and to guide those of ordinary skill in the art in practicing the disclosed subject matter.

[0021] Fibrous plant material: Parts (e.g., parts cut by mechanical or other means) of photosynthetic eukaryotic organisms of the kingdom Plantae, remaining in the original state in which they were grown. In some embodiments, the fibrous plant material is selected from the group consisting of wood (e.g., hardwood or softwood), bamboo (e.g., any of the bamboo family, e.g., Mosou, Oxygen reed, Viridis, Bamboo, and Nigra), reeds (e.g., Common Common Reed (Phragmites australis), Common Common Reed (Arundo donax), Burmese Reed (Neyraudia reynaudiana), Canary Reed (Phalaris arundinacea), Sweet Reed (Glyceria maxima), Small Reed (Calamagrostis species), Paper Reed (Cyperus papyrus), Bur Reed (Sparganium species), Reed Mace (Typha species), Cape Thatching Reed (Elegia tectorum), Thatching Reed (Thamnochortus insignis), or grasses (e.g., species selected from the Poales or the Poaceae family). Alternatively or additionally, in some embodiments, the plant material can be any type of fibrous plant composed of lignin, hemicellulose, and cellulose. For example, the plant material can be bagasse (e.g., formed from the processing residues of sugarcane or sorghum stalks) or straw (e.g., formed from the processing residues of cereal plants such as rice, wheat, millet, or corn).

[0022] Wood: The naturally occurring body of wood, comprising cellulose fibers embedded in a matrix of lignin and hemicellulose. In some embodiments, wood can be a hardwood (e.g., having a natural lignin content ranging from 18-25% by weight), or a softwood (e.g., but not limited to, basswood, oak, poplar, ash, alder, aspen, balsa wood, beech, birch, cherry, butternut, chestnut, cocobolo, elm, hickory, maple, oak, padauk, plum, walnut, willow, yellow poplar, bald cypress, cedar, Douglas fir, fir, hemlock, larch, pine, redwood, spruce, tamarack, juniper, and ginkgo).

[0023] Longitudinal growth direction (L): The direction in which a fibrous plant material grows from its roots or its body (e.g., the direction L of the stem 102 from the tree 100 in FIG. 1A). The cellulose nanofibers that form the cell walls of the fiber cells, vessels, and / or tracheid tubes of the fibrous plant material may generally be aligned with the longitudinal direction. In some cases, the longitudinal direction of the fibrous plant material may be generally vertical and / or may correspond to the direction of the plant's water transpiration flow (e.g., from the roots of a tree). The longitudinal direction may be substantially perpendicular to the radial and tangential directions of the fibrous plant material.

[0024] Radial growth direction (R): A direction extending outward from a central portion of a fibrous plant material (e.g., direction R of the trunk 102 from the tree 100 in FIG. 1A). In some embodiments, the ray cells of the fibrous plant material (e.g., ray cells 120 of the microstructure 110 in FIG. 1A) can extend along a radial direction. In some cases, the radial direction of the fibrous plant material may be generally horizontal. The radial direction may be substantially perpendicular to the longitudinal and tangential directions of the fibrous plant material.

[0025] Tangential growth direction (T): A direction that is substantially perpendicular to both the longitudinal and radial directions in a particular cut of fibrous plant material (e.g., direction T of the stem 102 from the tree 100 in FIG. 1A). In some cases, the tangential direction of the fibrous plant material may be generally horizontal. In some embodiments, the tangential direction may follow a growth ring of the fibrous plant material (e.g., along the circumferential direction of the stem 102).

[0026] Veneer: A continuous piece of fibrous plant material cut along a tangential direction (e.g., from a tree trunk or bamboo segment) and having a thickness of 3 mm or less. In some embodiments, the dimension of the continuous piece of fibrous plant material in a plane perpendicular to the thickness can be much greater than the thickness, e.g., at least an order of magnitude greater. In some embodiments, the thickness of the veneer can be 300 μm or less, e.g., in the range of 100-250 μm. In some embodiments, the veneer can be cut from the fibrous plant material using a rotary cutting technique (e.g., to obtain the rotary cut piece 108 of FIG. 1A).

[0027] Lignin-impaired fibrous plant material: A fibrous plant material that has been modified by one or more chemical treatments to in situ modify the native lignin therein, either to partially remove the native lignin therein (i.e., partially delignified), or to completely remove the native lignin therein (i.e., fully delignified). In some embodiments, the lignin-impaired fibrous plant material can substantially retain the native microstructure of the native fibrous plant material formed by the cellulosic cell walls.

[0028] Partial delignification: Removal of a portion (e.g., at least 1%) of the native lignin from naturally occurring fibrous plant material, but not all (e.g., 90% or less). In some embodiments, partial delignification can be performed by subjecting the native fibrous plant material to one or more chemical treatments. Lignin content can be assessed using techniques known in the art, such as Research and Analytical Procedure (LAP) TP-510-42618 for "Determination of Structural Carbohydrates and Lignin in Biomass" published by ASTM International, version 08-03-2012 published by the National Renewable Energy Laboratory (NREL), and ASTM E1758-01 (2020) for "Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography" published by ASTM International. In some embodiments, the partial delignification process can be, for example, as described in U.S. Patent Application Publication No. 2020 / 0223091, entitled “STRONG STRUCTURAL LUMBER AND METHODS FOR MANUFACTURING AND USING THEREOF,” published July 16, 2020, which delignification process is incorporated herein by reference.

[0029] Full delignification: The removal of substantially all (e.g., 90-100%) of the native lignin from a naturally occurring fibrous plant material. In some embodiments, full delignification can be carried out by subjecting the native fibrous plant material to one or more chemical treatments. The lignin content within the fibrous plant material before and after full delignification can be assessed using the same or similar techniques as described above for partial delignification. In some embodiments, the full delignification process can be, for example, as described in U.S. Patent Application Publication No. 2020 / 0238565, entitled "Pleasing Wood and Methods for Producing and Using the Same," published July 30, 2020, which delignification process is incorporated herein by reference.

[0030] Lignin modification: modifying one or more properties of native lignin in a naturally occurring fibrous plant material without removing the modified lignin in the fibrous plant material. In some embodiments, the lignin content of the fibrous plant material before and after in situ modification can be substantially the same, e.g., the in situ modified fibrous plant material retains at least 95% of the native lignin content (e.g., removing 1% or less, or 0.5% or less of the native lignin content). In some embodiments, the fibrous plant material is treated with OH to depolymerize the lignin (e.g., by cleaving the lignin with OH). - The depolymerized lignin can be modified in situ (by chemical reaction with lignin) and the depolymerized lignin is retained within the fibrous plant material microstructure. The lignin content within the fibrous plant material before and after lignin modification can be assessed using techniques known in the art, such as Research and Analytical Procedure (LAP) TP-510-42618 for "Determination of Structural Carbohydrates and Lignin in Biomass" published by ASTM International, and / or the Technical Association of the Pulp and Paper Industry (TAPPI), Standard T222-om-83, "Standard Test Method for Acid-Insoluble Lignin in Wood", Version 08-03-2012 published by the National Renewable Energy Laboratory (NREL), ASTM E1758-01(2020), all of which are incorporated herein by reference. In some embodiments, the lignin modification process can be, for example, as described in International Publication WO 2023 / 028356, published March 2, 2023, entitled "Waste-Free Process for Lignin Modification of Fibrous Plant Material, and Lignin-Modified Fibrous Plant Material," which lignin modification process is incorporated herein by reference.

[0031] Moisture content: The amount of fluid, typically water, retained within the microstructure of a fibrous plant material. In some embodiments, moisture content (MC) is determined by, for example, the weight change of a plant material achieved by oven drying (e.g., at 103° C. for 6 hours) according to the formula: TIFF2025517378000002.tif12157 を使用してIt can be determined by oven drying tests, by calculation, or alternatively or additionally, the moisture content can be assessed using techniques known in the art, such as an electric hygrometer or other techniques disclosed in ASTM D4442-20(2020) for "Standard Test Method for Direct Moisture Content Measurement of Wood and Wood-Based Materials" published by ASTM International.

[0032] Densified fibrous plant material: Fibrous plant material that has been subjected to a press such that the lumina formed by the cellulosic cells in the native microstructure is substantially disrupted and densified, and the density of the fibrous plant material is greater than the density of the native fibrous plant material prior to densification. In some embodiments, the densification of lignin-compromised fibrous plant material is at least 1 g / cm 3 , for example, 1.15 to 1.5 g / cm 3 (For example, about 1.3 g / cm 3 ) in thickness. In some embodiments, densification of the lignin-impaired fibrous plant material veneer can reduce the thickness of the veneer, for example, by at least a factor of two. For example, densification can reduce the veneer thickness from a first value in the range of 0.02-1.5 mm to a second value of 300 μm or less. In some embodiments, the densification process can be incorporated herein by reference, for example, as described in U.S. Patent Application Publication No. 2020 / 0223091, published on July 16, 2020, entitled "STRONG STRUCTURAL LUMBER AND METHODS FOR MANUFACTURING AND USE THEREOF," and / or International Publication No. WO2023 / 028356, published on March 2, 2023, entitled "Waste-Free Process for Lignin Modification of Fibrous Plant Material, and Lignin-Modified Fibrous Plant Material."

[0033] Introduction Disclosed herein are hollow or solid structures formed by wrapping or molding one or more fibrous plant material veneer layers around an axis (e.g., a common central axis), thereby forming a circumferentially extending wall. At least one of the fibrous plant material veneer layers may be a densified, lignin-impaired fibrous plant material veneer. To create the fibrous plant material veneer layers, the natural fibrous plant material can be cut into natural fibrous plant material veneers, for example, by rotary cutting. The lignin therein can then be impaired via one or more chemical treatments to soften the fibrous plant material veneer. The softened fibrous plant material veneer can be mechanically pressed to produce a densified, lignin-impaired fibrous plant material veneer. The thickness of the densified veneer can be sufficiently small (e.g., <1 mm) so that the veneer can be easily bent and shaped without breaking. In some embodiments, at least a portion of the surface of the densified, lignin-impaired fibrous plant material veneer may be coated with an adhesive (e.g., a substantially uniform coating on its surface) and then molded along (e.g., flat molded) or at an angle (e.g., spiral or cross spiral) to the cellulose fiber direction within the fibrous plant material veneer. The wall thickness of the molded structure may be selected by varying the number of fibrous plant material veneer layers (e.g., molded simultaneously or sequentially). In some embodiments, structures formed by circumferentially extending fibrous plant material walls may exhibit sufficiently high mechanical strength for use in structural applications (e.g., compressive strength of 50-90 MPa, higher than comparable aluminum alloy tubes). Alternatively or additionally, structures formed by circumferentially extending fibrous plant material walls may exhibit enhanced energy absorption. In some embodiments, the circumferentially extending fibrous plant material walls form a hollow structure, such as a tube or pipe. Alternatively, in some embodiments the circumferentially extending fibrous plant material wall forms part of a solid structure, such as, for example, a dowel or rod.

[0034] Densified, lignin-damaged veneer Natural wood has a unique three-dimensional porous microstructure that includes and / or is defined by various interconnected cells. For example, FIG. 1A shows a hardwood microstructure 110 in which conduits 112 are arranged in a hexagonal array of wood fiber cells 116 in a longitudinally extending cellular region. The conduits and fiber cells can extend along the longitudinal direction L of the wood. Thus, the lumen of each conduit 112 can have an extension axis 114 that is substantially parallel to the longitudinal direction L, and the lumen of each fiber cell 116 can have an extension axis 118 that is substantially parallel to the longitudinal direction L. Disposed between adjacent regions along the tangential direction T are radially extending cellular regions in which a plurality of ray cells 120 are arranged. The ray cells 120 can extend along the radial direction R of the wood. Thus, the lumen of each ray cell 120 can have an extension axis 122 that is substantially parallel to the radial direction R of the wood. Intracellular lamellae are located between the vessels 112, fiber cells 116, and ray cells 120 and function to interconnect the cells. Softwoods can have a similar microstructure to hardwoods, but with the vessels and wood fibers replaced by tracheid tubes that extend in the longitudinal direction L of the wood.

[0035] The cut direction of the original wood piece can determine the orientation of the cell lumen in the final structure. For example, in some embodiments, the natural wood piece can be cut vertically or longitudinally (e.g., parallel to the longitudinal wood growth direction L) from the trunk 102 of the tree 100, so that the longitudinally extending cell lumen is oriented substantially parallel to the major surface (e.g., maximum surface area) of the longitudinally cut wood piece 106. In the longitudinally cut wood piece 106, the tangential direction T can be substantially perpendicular to the major surface. Alternatively, in some embodiments, the natural wood piece can be cut horizontally or radially (e.g., perpendicular to the longitudinal wood growth direction L) such that the longitudinally extending cell lumen is oriented substantially perpendicular to the major surface of the radially cut wood piece 104. Alternatively, in some embodiments, the natural wood pieces may be cut rotationally (e.g., perpendicular to the longitudinal wood growth direction L and along the circumference of the stem 102) such that the lumens of the longitudinal cells are oriented substantially parallel to the major faces of the rotationally cut wood pieces 108. In some embodiments, the natural wood pieces may be cut in any other orientation between longitudinal cuts, radial cuts, and rotational cuts. In some embodiments, the cut direction of the wood pieces may determine certain mechanical properties of the final engineered wood.

[0036] FIG. 1B illustrates an embodiment for delignification and densification of wood veneer 134 for use in forming circumferentially extending wood walls. In the initial stage 132 before delignification, the wood veneer 134 can have open lumens 136 formed by the cellulosic cell walls in the natural microstructure of wood. For example, the microstructure can have longitudinally extending fibrous cell walls formed from a composite 140 of cellulose fibrils 142 bound together by a hemicellulose and lignin adhesive matrix 144, which is strong and rigid. The lignin matrix 144 can be dissolved by immersing the wood veneer 134 in one or more chemical solutions and then removed from the veneer by subsequent washing. For example, the chemical solutions can be NaOH (LiOH or KOH), NaOH+Na 2 SO 3 / Na 2 SO4 , NaOH+Na 2 S, NaHSO 3 +SO 2 +H 2 O, NaHSO 3 +Na 2 SO 3 , NaOH+Na 2 SO 3 , NaOH / NaH 2 O 3 +AQ, NaOH / Na 2 S+AQ, NaOH+Na 2 SO 3 +AQ, Na 2 SO 3 +NaOH+CH 3 OH+AQ, NaHSO 3 +SO 2 +AQ, NaOH+Na 2 Sx, where AQ is anthraquinone.

[0037] In a subsequent stage 148 after delignification, the lignin-compromised wood veneer 150 may have a microstructure 152 that retains the alignment of cellulose fibrils 142 (as well as the open lumens 136), but with a reduced lignin content. In some embodiments, the microstructure 152 of the wood veneer 150 may retain at least some lignin 154. However, the lignin-compromised wood veneer 150 in its native state is significantly softer than the wood veneer 134, thereby allowing the veneer 150 to be compressed to form a densified veneer 160 in a final stage 156, where the previously open cellulosic lumens 136 are substantially folded, as shown at 162 in FIG. 1B and in the image in FIG. 1C. In some embodiments, the densification press may be along a direction that is substantially perpendicular to, or at least transverse to, the longitudinal growth direction (L) of the wood veneer.

[0038] In some embodiments, the width W of the natural wood veneer 134 1 The veneer is densified and contains lignin, and is 160mm wide. 2In some embodiments, the thickness W 2 The wood is made of plywood 134W. 1 and / or the press may have a compression ratio (W) of 1.1:1 to 10:1. 1 :W 2 ) can result. For example, W 1 may be 5 mm or less (e.g., in the range of 0.02 mm to 1.5 mm), and W 2 can be 3 mm or less (e.g., 300 μm or less, e.g., in the range of 100-250 μm). In some embodiments, the densified, lignin-impaired wood veneer 160 can have an increased density as compared to the natural wood veneer 134. For example, the densified wood veneer 160 can have a density of at least 1.15 g / cm 3 (e.g., at least 1.2 g / cm 3 , or at least 1.3 g / cm 3 ), whereas natural wood veneer has a density of 1.0 g / cm 3 Less than (e.g., 0.9 g / cm 3 Less than or equal to 0.5 g / cm 3 The density of the sintered body may be less than 100 nm.

[0039] FIG. 1D illustrates an embodiment for lignin modification and densification of wood veneer 134 for use in forming a circumferentially extending wood wall. Similar to the example of FIG. 1B, the wood veneer 134 at an initial stage 170 prior to lignin modification can have open lumens 136 formed by cellulosic cell walls in the wood's natural microstructure, which can have longitudinally extending fibrous cell walls formed from a complex 140 of cellulose fibrils 142 bonded together by hemicellulose and lignin adhesive matrix 144. The wood veneer 134 can be, for example, infiltrated or infused with one or more chemicals via the natural lumens 136. Upon activation (e.g., via heating at elevated temperatures such as 80-180° C.), the infiltrated chemicals can modify the native lignin in situ. For example, in a subsequent step 174 after activation, the polymeric chains of the native lignin can be broken down into smaller segments 178, resulting in a more flexible composite 176 for the modified wood veneer 172 while still retaining the open cellulosic lumens 136 of the unmodified microstructure.

[0040] In some embodiments, the infiltrated chemical is hydroxide (OH - The amount of infiltrated chemical and / or duration of heating can be selected to ensure that all alkaline chemicals in the wood veneer react completely to obtain a neutral softened wood veneer, since prolonged exposure of wood to alkali can degrade cellulose (which in turn can result in a decrease in mechanical properties). For example, OH ions from the infiltrated alkaline chemical (e.g., NaOH) can be generated by heating the wood veneer to 100%. - The ions can react with the phenolic hydroxyl groups in lignin, and at the same time, OH - The ions can also break the bond bonds in the lignin polymer, thus shortening the lignin polymer chains. As a result of the modified lignin, the wood veneer is softened.

[0041] Additionally, lignin degradation products can react with the impregnated alkaline chemical (e.g., NaOH) to form salts of phenols (e.g., sodium salts of phenols). Alternatively or additionally, in some embodiments, the alkaline chemical impregnated into the wood veneer can react with native hemicellulose to cause its modification (e.g., degradation). For example, OH - The ions can cause the degradation of hemicellulose through exfoliation reactions, thereby producing acidic degradation products. These acidic products can react with alkaline chemicals (e.g., NaOH) to form neutral salts that can be immobilized within the final processed plant material. For example, hemicellulose degradation products can react with impregnated alkaline chemicals (e.g., NaOH) to form salts of alduronic acid (e.g., the sodium salt of alduronic acid).

[0042] Alternatively or additionally, in some embodiments, an alkaline chemical that is infiltrated into the wood veneer can react with the native cellulose, causing its modification (e.g., degradation). For example, OH - The ions can cause the degradation of cellulose by exfoliation reactions. The degradation products can react with alkaline chemicals (e.g., NaOH) to form neutral salts that can be immobilized in the final densified wood veneer 182. For example, cellulose degradation products can react with impregnated alkaline chemicals (e.g., NaOH) to form gluconates (e.g., sodium salts of gluconates). Reducing end groups in cellulose chains are susceptible to detachment under alkaline conditions, thereby exposing new reducing groups. The generation of new reducing ends can allow for repeated removal of reducing ends from cellulose macromolecules. Thus, significant amounts of gluconates (e.g., sodium salts) can be formed. In some embodiments, gluconates in the final in situ lignin modified wood can predominate (e.g., compared to salts of phenols and / or salts of alduronic acids).

[0043] As a result of the lignin-modified composite 176, the softened wood veneer 172 may be more easily densified. In some embodiments, the densification press may be along a direction substantially perpendicular to, or at least transverse to, the longitudinal growth direction (L) of the wood. For example, during the densification stage 180, the lignin-modified veneer 172 may be compressed to form a densified, lignin-impaired veneer 182, in which the previously open cellulosic lumens 136 are substantially crushed, as shown at 184 in FIG. 1D. In some embodiments, the width W of the natural wood veneer 134 may be reduced by 180 to 200 mm. 1 is a densified, lignin-containing wood veneer with a width of 182 W 3 In some embodiments, the thickness W 3 The W of the veneer is 134 1 and / or the press may have a compression ratio (W) of 1.1:1 to 10:1. 1 :W 3 ) can result. For example, W 1 may be 5 mm or less (e.g., in the range of 0.02 mm to 1.5 mm), and W 3 can be 3 mm or less (e.g., 300 μm or less, e.g., in the range of 100-250 μm). In some embodiments, the densified, lignin-impaired wood veneer 182 can have an increased density as compared to the natural wood veneer 134. For example, the densified wood veneer 182 can have a density of at least 1.15 g / cm 3 (e.g., at least 1.2 g / cm 3 , or at least 1.3 g / cm 3 ) while the natural wood veneer 134 may have a density of 1.0 g / cm 3 Less than (e.g., 0.9 g / cm 3 Less than or equal to 0.5 g / cm 3 The density of the sintered body may be less than 100 nm.

[0044] Referring to FIG. 1F, an exemplary process setup for forming densified, lignin-impaired wood veneers from natural wood is shown. The natural wood may be in the form of a log or cylindrical rod (e.g., tree trunk 102) with the lumen extending in a direction perpendicular to the page (e.g., longitudinal growth direction). In a sawing stage 188, the natural wood may be sawn, for example, using a rotary lathe 190, to separate a thin continuous veneer layer 134 of the natural wood for subsequent processing. In some embodiments, the natural veneer 134 may be conveyed directly from the sawing stage 188 to a lignin modification stage 191, such as, for example, a delignification stage. In the illustrated example, the veneer 134 is immersed in a chemical solution 194 in a processing station 192 to at least partially remove the lignin therein, thus resulting in a lignin-impaired veneer 150. Alternatively, in some embodiments, the lignin modification stage 191 may consist of a treatment station for lignin modification, for example, to infiltrate a portion of the veneer 134 therein with a chemical solution, and a subsequent station for heating the infiltrated veneer to effect the desired in situ modification.

[0045] After the lignin modification stage 191, the lignin modified veneer 150 can be conveyed directly to a compression station 196 for pressing in a direction substantially perpendicular to or at least transverse to the longitudinal growth direction. In the example shown in FIG. 1F, a pair of rollers 198 is used to mechanically press the lignin damaged veneer 150 therebetween to output a densified, lignin damaged veneer 160. However, other press configurations are possible according to one or more contemplated embodiments, such as, but not limited to, a single stationary roller, multiple successive stationary rollers (e.g., to cumulatively provide a desired compression time), single or multiple movable flat platens, single or multiple movable rollers, or any combination of the foregoing. Alternatively or additionally, the compression station 196 can be configured to heat one or both of the veneer 150 and / or rollers 198 prior to or during pressing. Other systems and configurations for forming densified, lignin damaged wood veneers are also possible according to one or more contemplated embodiments.

[0046] While the description above and elsewhere herein has focused on wood veneers, embodiments of the disclosed subject matter are not limited thereto. Rather, the lignin modification, densification, and wrapping of rotary cut veneers can be applied to other fibrous plant materials, such as, but not limited to, natural bamboo. FIG. 1G shows a partial cutaway view of a bamboo segment 151 in a naturally occurring state. The segment 151 has a stem wall 153 surrounding a hollow interior region 163 that is divided into interior nodal regions 159 along the length of the stem wall 153 by nodes 155 formed by internal nodal septa 157. The stem wall 153 has fibers extending along the longitudinal direction L of the bamboo segment 151 (e.g., the bamboo growth direction, or a direction substantially parallel to the axis defined by the hollow interior region 163) embedded in a lignin matrix. One or more branching stubs 161 can extend from a particular interior nodal region 159 and can act as roots from which stem walls for new bamboo segments may grow (e.g., thus defining a different longitudinal direction for the new segment).

[0047] Within the stem wall 153, bamboo exhibits a hierarchical cell structure with porous cells providing nutrient transport and dense cells providing mechanical support. For example, FIG. 1H shows an image of a cross-section of a bamboo segment 151, specifically showing the microstructure of parenchymal cells 165, conduits 167, and fiber bundles 169 that make up the stem wall 153. The fiber bundles 169 are highly aligned and extend substantially parallel to the longitudinal direction L, while the parenchymal cells 165 can be parallel or perpendicular to the longitudinal direction L. The density of the fiber bundles 169 can increase along the radial direction such that the outer portion of the bamboo 151 closest to the exterior surface has different mechanical properties than the inner portion of the bamboo closest to the hollow interior region 163.

[0048] Each conduit 167 can define an open lumen extending along the longitudinal direction L. Additionally, the elementary fibers forming the fiber bundles 169 can also have irregular small lumens in their centers. The fiber bundles 169, parenchymal cells 165, and conduits 167 are attached to each other via a polymer matrix composed of lignin and hemicellulose. The natural microstructure can also exhibit pit openings on the longitudinal walls of the fibers, porosity introduced by parenchymal cells, and / or open intercellular spaces between adjacent fibers. The cut direction of the original bamboo piece can determine the orientation of the cell lumens in the final structure. For example, the natural bamboo piece can be cut rotationally (e.g., perpendicular to the longitudinal growth direction L, along the circumferential direction of the segment 151), so that the lumens of the longitudinal cells are oriented substantially parallel to the major surfaces of the rotationally cut bamboo piece 171. Embodiments of the disclosed subject matter can compromise the natural polymer matrix in the bamboo piece to soften the bamboo for densification and / or further processing.

[0049] Wrapping densified and lignin-compromised wood veneers In some embodiments, the strength of the resulting circumferentially extending wall formed by wrapping one or more densified, lignin-impaired wood veneers around the forming axis may be influenced by the diameter of the circumferentially extending wall, the wall thickness (e.g., the thickness of each wood veneer and the number of wood veneer layers), and / or the orientation of the wood veneer (e.g., the longitudinal growth direction and / or the direction of the cellulose fibers relative to the central axis). In some embodiments, for example as shown in FIG. 2A, one or more densified, lignin-impaired wood veneers 202 may be wrapped around the forming axis 204 with the longitudinal growth direction 206 being substantially parallel to the forming axis 204. In the example shown in FIG. 2A, a single veneer 202 in the initial stage 200 is wrapped around the forming axis 204 to form a circumferentially extending wood wall 210 in stage 208. The wood wall 210 may be substantially centered on and extend parallel to the forming axis 204. Adhesive may be applied to the overlapping edges of the single veneer 202 to secure the wall 210 to the wrapped circumferentially extending structure.

[0050] In some embodiments, as shown in FIG. 2B, a plurality of densified, lignin-impaired wood veneers 214, 216 may be simultaneously wrapped around a forming axis 226 to form a circumferentially extending multi-layered wood wall 224. In the example shown in FIG. 2B, the longitudinal growth direction 218 is substantially parallel to the forming axis 226. The first and second wood veneers 214, 216 may be fed into an input end of a rolling station 220 comprising a plurality of rollers 222 in a substantially planar orientation (e.g., parallel to the forming axis 226). The rollers 222 may gradually bend the veneers 214, 216 into position around the forming axis 226 to form the multi-layered wood wall 224. In some embodiments, adhesive may be applied to some or all of the surface of the veneer 214 facing the veneer 216 and / or to some or all of the surface of the veneer 216 facing the veneer 214. Alternatively or additionally, in some embodiments, adhesive can be applied to overlapping edge portions of the outermost veneer layer (e.g., veneer 216) to secure wall 224 to the wrapped circumferentially extending structure.

[0051] In some embodiments, as shown in FIG. 2C, a plurality of densified, lignin-impaired wood veneers 234, 242 can be sequentially wrapped around a forming axis 250 to form a circumferentially extending multi-layered wood wall 254. As in the example of FIGS. 2A-2B, the longitudinal growth direction of each veneer 234, 242 can be substantially parallel to the forming axis 250. In the example shown in FIG. 2C, a forming member 232 (e.g., a cylindrical rod) is used to define the wrapped shape of the veneers 234, 242 (or at least the wrapped shape of the innermost veneer layer 238). In a first stage 230, a first densified, lignin-impaired veneer 234 is wrapped around the circumference of the forming member 232, thereby forming the innermost veneer layer 238 in a second stage 236. In some embodiments, prior to wrapping, adhesive may be applied to some or all of the surfaces of the veneer 234 that face the molding member 232 and / or some or all of the exposed surfaces of the molding member 232 (e.g., facing the veneer 234). Alternatively or additionally, in some embodiments, adhesive may be applied to overlapping or abutting edge portions of the wrapped veneer layer 238, for example, before, during, or after the wrapping of the first stage 230.

[0052] In a third stage 240, a second densified, lignin-impaired veneer 242 is wrapped around the circumference of the innermost veneer layer 238, thereby forming an outermost veneer layer 246 in a fourth stage 244. In some embodiments, prior to the wrapping in the third stage 240, an adhesive may be applied to some or all of the surface of the veneer layer 242 that faces the innermost veneer layer 238 and / or some or all of the exposed surfaces of the veneer layer 238 (e.g., facing the veneer 242). Alternatively or additionally, in some embodiments, an adhesive may be applied to overlapping or abutting edge portions of the wrapped veneer layer 246, for example, before, during, or after the wrapping in the third stage 240. Once the adhesive has dried, the molding member 232 may be removed in a fifth stage 248, thereby leaving behind the veneer layers 238, 246 to form the circumferentially extending wood wall 254. After removal of the molding member 232, the wood wall 254 forms a hollow structure having an open interior volume 252. In some embodiments, removal of the molding member 232 may be accomplished by displacing one or both of the molding member 232 and the wood wall 254 relative to one another along a direction parallel to the molding axis 250. Alternatively or additionally, in some embodiments, the molding member 232 may be removed by partially or completely dissolving or otherwise removing in situ (e.g., by melting, sublimation, etching, etc.).

[0053] 2A-2C depict each veneer layer extending around the entire circumference of the wood wall, but embodiments of the disclosed subject matter are not so limited. Rather, in some embodiments, one, some, or each layer of the circumferentially extending wood wall can be formed with multiple veneers that extend around only a portion of the circumference (e.g., each veneer has a semicircular shape in cross section). In addition, while a single veneer layer is shown in FIG. 2A and two veneer layers are shown in FIG. 2B-2C, any number of veneer layers (e.g., three or more) are possible according to one or more contemplated embodiments. Indeed, FIG. 2E-2F depict a cylindrical wood tube 260 formed according to the flat wrapping orientation of FIG. 2D, but with three or more veneer layers. 2D-2F , a cylindrical wood tube 260 is formed by a plurality of densified, partially delignified wood veneer layers and has a circumferentially extending wood wall 262 enclosing a hollow interior volume 264. Each wood veneer layer is oriented such that its longitudinal growth direction 266 (and the cellulose fiber direction therein) extends substantially parallel to the forming axis and length of the tube 260.

[0054] In some embodiments, for example as shown in FIG. 3A, one or more densified, lignin-impaired wood veneers 302 can be wrapped in a longitudinal extension direction 306 at an angle 308 (e.g., a non-zero, non-orthogonal angle, e.g., about 45°) relative to the molding axis 304. In the example shown in FIG. 3A, a single veneer 302 in an initial stage 300 is wrapped around the molding axis 304 to form a circumferentially extending wood wall 314 in stage 310. The wood wall 314 can be substantially centered on the molding axis 304 and extend parallel thereto, but the orientation 312 of the cellulose fibers therein (e.g., having a helical structure) is non-parallel to the molding axis 304. An adhesive can be applied to overlapping surface portions of the single veneer 302 to secure the wall 210 to the wrapped circumferentially extending structure. In some embodiments, the use of an angled orientation for wrapping can enable the formation of circumferentially extending wood walls 314 of any length (e.g., at least 1 m along a direction parallel to the forming axis 304).

[0055] In some embodiments, as shown in FIG. 3B, a plurality of densified, lignin-impaired wood veneers 318, 320 can be wrapped simultaneously around a forming axis 326 to form a circumferentially extending multi-layered wood wall 330. In the example shown in FIG. 3B, the longitudinal growth direction 328 of each veneer 318, 320 is non-parallel to the forming axis 326, but the longitudinal growth directions of the veneers 318, 320 are oriented substantially the same. As a result, the cellulose fibers within each veneer layer of the wood wall 330 are substantially parallel at the same angle. In the example shown in FIG. 3B, the first and second wood veneers 318, 320 can be fed in an offset orientation (e.g., across a plane that includes the forming axis 326) to an input end of a rolling station 322 that includes an inner roller 332 and an outer roller 324. Rollers 324, 324 can shape veneers 318, 320 into position about forming axis 326 to form multi-layer wood wall 330. In some embodiments, adhesive can be applied to some or all of the surface of veneer 318 facing veneer 320 and / or some or all of the surface of veneer 320 facing veneer 318. Alternatively or additionally, in some embodiments, adhesive can be applied to overlapping edge portions of the outermost veneer layer (e.g., veneer layer 320) to secure wall 330 to a circumferentially extending structure.

[0056] In some embodiments, the multiple densified, lignin-impaired wood veneers forming the circumferentially extending wood wall can have different orientations relative to their longitudinal growth direction. For example, as shown in FIG. 3C, a second veneer 342 in a successive step 340 can be wrapped around the previously wrapped veneer 302. The veneer 342 can be wrapped with its longitudinal extension direction 346 at an angle 348 (e.g., a non-zero, non-orthogonal angle of the angle 308, e.g., about -45o) relative to the molding axis 304. In some embodiments, the second veneer 342 can be wrapped in a direction opposite to that of the first veneer 302 (e.g., if the first veneer forms a left-handed helix, the second veneer forms a right-handed helix), but at the same angle. Thus, the cellulose fibers in the different layers present the same angle relative to the tube axis 326, but with opposite winding directions. In some embodiments, the opposite wrapping direction can continue for each subsequent wrapping layer until the desired wall thickness is reached. In the example shown in FIG. 3C, the wood wall 358 resulting from step 350 includes an innermost veneer layer 314 having an orientation 312 of cellulose fibers therein and an outermost veneer layer 354 having another orientation 352 of cellulose fibers therein. In some embodiments, the orientations 312, 352 in the multi-layer wood wall 358 can be considered as cross-helical structures. In some embodiments, the orientations 312, 352 can form an angle 356 of, for example, about 90°.

[0057] Although Figures 3A-3C illustrate each veneer layer extending around the entire circumference of the wood wall, embodiments of the disclosed subject matter are not so limited. Rather, in some embodiments, one, some, or each layer of the circumferentially extending wood wall may be formed from multiple veneers that extend around only a portion of the circumference (e.g., each veneer has a C-shape in cross section). In addition, while a single veneer layer is shown in Figure 3A and two veneer layers are shown in Figures 3B-3C, any number of veneer layers (e.g., three or more) are possible according to one or more contemplated embodiments. Indeed, Figures 4B-4C show a cylindrical wood tube 400 formed according to the helical structure of Figure 4A but with more than two veneer layers, and Figures 4E-4F show another cylindrical wood tube 410 formed according to the cross helical structure of Figure 4D but with more than two veneer layers. In Figures 4A-4C, a cylindrical wood tube 400 is formed by a plurality of densified, partially delignified wood veneer layers and has a circumferentially extending wood wall 406 that surrounds a hollow interior volume 402. Each wood veneer layer (e.g., first layer 408a-second layer 408b in Figures 4A and 4C) is oriented such that its longitudinal growth direction 404 (and the cellulose fiber direction therein) extends at an angle to the molding axis and the length of the tube 400. In Figures 4D-4F, a cylindrical wood tube 410 is formed by a plurality of densified, partially delignified wood veneer layers 414a-414c and has a circumferentially extending wood wall 416 that surrounds a hollow interior volume 412. Each wood veneer layer 414a-414c is oriented with its respective longitudinal growth direction 418a-418c at an angle relative to the molding axis and the length of the tube 410. However, for each wood veneer layer 414a-414c, the respective longitudinal growth direction 418a-418c is in an opposite direction to the direction of the wood veneer layer immediately adjacent to it. For example, the first and third layers 414a, 414c have an orientation along the same direction (e.g., substantially parallel), while the direction of the second layer 414b has an opposite orientation to the first and third layers, as shown in FIG. 4F.

[0058] In some embodiments, for example as shown in FIG. 5, one or more densified, lignin-impaired wood veneers 502 may be wrapped with their longitudinal extension directions 506 aligned circumferentially (e.g., such that the orientation 512 of the cellulose fibers therein is at an angle 516 of about 90°, e.g., with respect to a plane 508 that includes the molding axis 504). In the example shown in FIG. 5, a single veneer 502 in an initial stage 500 is wrapped around the molding axis 504 to form a circumferentially extending wood wall 514 in stage 510. The wood wall 514 may be substantially centered on and extend parallel to the molding axis 504. An adhesive may be applied to overlapping surface portions of the single veneer 502 to secure the wall 514 to the wrapped circumferentially extending structure.

[0059] Tubes formed from plywood made from fibrous plant material In some embodiments, the densified, lignin-impaired fibrous plant material veneers may be wrapped to form a hollow structure, such as a substantially cylindrical tube or pipe. For example, FIG. 6A shows a hollow structure 600 including a single fibrous plant material veneer 606. The veneer 606 is wrapped around a central axis to form a circumferentially extending fibrous plant material wall 602 that encloses an interior volume 604. In the example shown in FIG. 6A, opposing side edges of the veneer 606 may face and / or abut one another, thereby forming joints 608. In some embodiments, an adhesive may be applied to the joints 608 to secure the veneer 606 into a desired wrapped shape. Alternatively or additionally, in some embodiments, the veneer 616 may overlap itself along a circumferential direction (e.g., at a side edge portion) to enclose an interior volume 614 and form a joint 618, as shown, for example, by the circumferentially extending wall 612 of the hollow structure 610 in FIG. 6B. The joint 618 may have an increased thickness along a radial direction compared to the remainder of the veneer. In some embodiments, an adhesive may be applied to the joint 618 to secure the veneer 616 in a desired wrapping shape. Alternatively or additionally, some or all surfaces of the veneer 606 and / or veneer 616 may be coated with an adhesive such that, as the adhesive dries, the stiffness of the veneer increases, thereby holding the veneer in a desired wrapped shape.

[0060] In some embodiments, multiple densified, lignin-impaired veneers can be wrapped to form a hollow structure, e.g., a substantially cylindrical tube or pipe. For example, FIG. 6C shows a hollow structure 620 including four veneer layers 622, 624, 626, and 628 that form a circumferentially extending fibrous plant material wall 630. The innermost fibrous plant material veneer 622 is wrapped about a central axis to enclose an interior volume 632, while the other veneers 624-628 are successively wrapped over the more radially inner veneers. In the illustrated example, the opposing side edges of each veneer can face and / or abut one another, thereby forming respective joints (for clarity, only 634 is labeled in FIG. 6C). In some embodiments, each joint may be offset from other joints, or at least joints of adjacent veneers within wall 630, along the circumference of structure 620, for example, to increase the strength of wall 630. In some embodiments, adhesive may be applied to each veneer joint (e.g., 634) to secure the veneer in the desired wrapped shape. Alternatively or additionally, the exposed radial surface of each veneer, or a portion thereof, may be coated with an adhesive for bonding to an opposing radial surface of another veneer. Alternatively or additionally, some or all surfaces of veneers 622, 624, 626, and / or 628 may be coated with an adhesive such that, as the adhesive dries, the stiffness of the veneer increases, thereby holding the veneer in the desired wrapped shape.

[0061] In some embodiments, the hollow structure formed by one or more densified, lignin-impaired veneers can be combined with one or more non-vegetable material (e.g., non-wood) layers to form a composite structure. For example, FIG. 6D shows a composite hollow structure 640 having a circumferentially extending wall 642 formed by wrapping one or more densified, lignin-impaired veneers around a central axis and enclosing an interior volume 644. A first non-vegetable layer 646 can be disposed on an inner surface of the wall 642. Alternatively or additionally, a second non-vegetable layer 648 can be disposed on an outer surface of the wall 642. In some embodiments, the first non-vegetable layer 646, the second non-vegetable layer 648, or both can be formed of concrete, metal, or polymer. In some embodiments, the thickness of the first non-vegetable layer 646, the second non-vegetable layer 648, or both, may be less than the thickness of the circumferentially extending fibrous plant material wall 642, e.g., 50% or less of the fibrous plant material wall thickness. In some embodiments, the second non-vegetable layer 648 may be provided (e.g., deposited, coated, laminated, etc.) on the fibrous plant material wall 642, e.g., after the veneer has been wrapped and any adhesive has dried. Alternatively or additionally, in some embodiments, the first non-vegetable layer 646 may be provided (e.g., deposited, coated, laminated, etc.) on the fibrous plant material wall 642, e.g., after the veneer has been wrapped and any adhesive has dried. Alternatively or additionally, in some embodiments, the first non-vegetable layer 646 may be embodied (e.g., as a tube or pipe) and used as a forming member around which the fibrous plant material veneer is wrapped to form the wall 642.

[0062] Although the above discussion has focused mainly on hollow structures having cylindrical cross sections, embodiments of the disclosed subject matter are not so limited. In fact, any cross-sectional shape of the circumferentially extending fibrous plant material wall is possible according to one or more possible embodiments. For example, FIG. 6E shows a hollow wood structure manufactured with a circular cross section 650, a triangular cross section 652, and a rectangular cross section 654.

[0063] Energy Absorption Structure In some embodiments, the densified, lignin-impaired fibrous plant material veneer can be strong in the direction along the cellulose fibers (e.g., having a mechanical strength of about 650 MPa) but relatively weak in the direction perpendicular to the cell fibers (e.g., having a mechanical strength of about 20 MPa). As a result, the flat-wrapped orientation (e.g., longitudinal growth direction 708 parallel to the forming axis 706) to form the circumferentially extending wood wall 702 can be anisotropic, being relatively strong when subjected to forces parallel to the forming axis 706 (e.g., forces along the axial direction) but relatively weak when subjected to forces perpendicular to the forming axis 706 (e.g., forces along the radial direction), as shown in the setup 700 of FIG. 7A. In addition, when subjected to axial compression as in FIG. 7A, the flat-wrapped wood tube 702 can exhibit a unique failure mode that differs from a tube made of an isotropic material. In some embodiments, this failure mode can increase the energy absorption capacity of the flat-wrapped wood wall 702.

[0064] As shown in the test progression 710 of Figures 7B-7C, when loaded in axial compression by two end caps, the flat-wrapped wood tube 702 fractures in a petal failure mode 712, which initiates at one or both ends of the tube 702 and steadily progresses along the axial direction as the two end caps approach. In contrast, when an isotropic tube made of aluminum is subjected to similar axial compression, the failure is characterized by severe localized distortion of the tube due to buckling. Referring to Figure 8A, an exemplary structure 800 for compression loading is shown, in which end caps 802a, 802b are inserted into opposite axial ends of a flat-wrapped wood tube 804, with a hollow volume 806 between them. In the illustrated example, each end cap 802 had an outer diameter D1 of 25.5 mm, an inner diameter D2 of 12.67 mm, a flange height H1 of 10.8 mm, and an insert height H2 of 10.1 mm, and the wood tube 804 had an inner diameter D3 of 12.75 mm, a flange-to-flange length H3 of 100 mm, and a wall thickness t of 0.64 mm.

[0065] At approximately 2% compressive strain, multiple cracks initiate along the axial direction at the end of the tube 704 in contact with the end cap due to the anisotropic mechanical behavior of the tube. As the two end caps approach each other more, the initial cracks propagate parallel along the axial direction, leading to the tube splitting into strips after the cracks. These densified, lignin-compromised wood strips curl outward as the cracks continue to propagate along the axial direction, forming a petal-like failure morphology of the tube, as shown in Figures 7B-7C.

[0066] In some embodiments, the high energy absorption provided by the petal failure mode in flat-wrapped wood walls can be exploited in energy absorbing devices (e.g., automobile bumpers, building crush protection, etc.). For example, FIG. 8B shows an energy absorbing structure 810 formed by an array 812 of flat-wrapped wood tubes 804 (each with a longitudinal growth direction 808 aligned with the axis of the tube 804) disposed between a pair of support members 814a, 814b. The support members 814a, 814b can be formed of any material (e.g., a metal such as aluminum). In some embodiments, the support members 814a, 814b can be coupled to the wood tube 804 via respective end caps (e.g., similar to the compression caps 802 in FIG. 8A, not shown in FIG. 8B). Thus, application of a sufficient force (e.g., impact or compression) between the support members 814a, 814b can be absorbed and / or dissipated by a petal failure of one or more of the tubes 804. Although a linear array 812 of only three tubes 804 is shown in Figure 8B, embodiments of the disclosed subject matter are not so limited. Rather, any number of tubes 804 and arrangements thereof are possible in accordance with one or more contemplated embodiments, such as, but not limited to, a rectangular array 822 of tubes 824 between aluminum plates 826a, 826b in the energy absorbing structure 820 of Figure 8C.

[0067] Closed ends and solid structures formed by fibrous plant material veneers Although the description above and elsewhere herein has focused on open-ended hollow structures, embodiments of the disclosed subject matter are not so limited. Rather, in some embodiments, a circumferentially extending wall formed by wrapping one or more densified, lignin-impaired fibrous plant material veneers around a central axis can be part of a closed-ended hollow structure and / or a solid structure. For example, FIG. 9A shows a closed-ended hollow structure 900 (e.g., a closed-ended tube, cup, tank, or bottle) having a circumferentially extending fibrous plant material wall 902 that encloses an interior volume 910. A second member 904 can be coupled to one end 906 of the wall 902 and close it, while an opposite end 908 of the wall 902 can remain open. The second member can be formed of any material, for example, natural fibrous plant material, metal, polymer, cork, concrete, densified fibrous plant material, densified, lignin-impaired fibrous plant material, or any combination thereof. In the example shown in Figure 9A, the second member 904 can extend over and / or be attached to an outer portion of the wall 902. Alternatively or additionally, the second member 914 can extend over and / or be attached to an inner portion of the wall 902, for example, as shown by structure 912 in Figure 9B.

[0068] FIG. 9C illustrates a solid structure 920 (e.g., a rod, dowel, bat, or club) having a circumferentially extending fibrous plant material wall 922 surrounding a central member 924. The central member 924 can be formed of any material, such as natural fibrous plant material, metal, cork, concrete, densified fibrous plant material, lignin-impaired fibrous plant material, densified and lignin-impaired fibrous plant material, or any combination thereof. For example, FIG. 9E illustrates an engineered solid structure formed by wrapping 10 layers of densified and partially delignified wood veneer around a wood core, and FIG. 9F illustrates an engineered solid structure formed by wrapping 90 layers of densified and partially delignified wood veneer around a wood core. In the example illustrated in FIG. 9C, the central member 924 is contained within the axial length of the wood wall 922. However, in some embodiments, the central member may extend beyond one or both ends of the fibrous plant material wall. For example, a central member 928 in a solid structure 926 in FIG. 9D has an extension 932 extending from a first end 930 of a circumferentially extending wood wall 922 .

[0069] Manufacturing method Referring to FIG. 10A, a method 1000 for producing a densified, lignin-impaired fibrous plant material veneer is shown. The method 1000 can begin with a process step 1002 in which a veneer of natural fiber plant material is prepared. For example, the preparation process 1002 can include cutting, removing, or otherwise separating the veneer of natural fiber plant material from a parent structure (e.g., a tree). In some embodiments, the cutting can form the veneer into a substantially flat, planar structure, with the direction of the cellulose fibers extending parallel to the plane of the structure. Optionally, in some embodiments, the preparing can include pre-processing the veneer of natural fiber plant material, such as washing to remove any undesirable material or contamination, in preparation for subsequent processing, forming the fibrous plant material into a particular shape in preparation for subsequent processing (e.g., slicing into strips), or any combination of the foregoing. In some embodiments, the preparation process 1002 can include obtaining one or more veneers by rotary directional cutting.

[0070] The method 1000 may proceed to a decision step 1004, where it is determined whether the veneer is to undergo lignin modification or delignification. If delignification is desired, the method 1000 may proceed to a treatment step 1006, where the natural fiber plant material veneer is subjected to one or more chemical treatments to remove at least some lignin therefrom, for example, by immersing the natural fiber plant material veneer (or a portion thereof) in a chemical solution associated with the treatment. In some embodiments, each or only some of the chemical treatments may be performed under vacuum, such that the solutions associated with the treatments are encouraged to fully penetrate the cell walls and lumens of the natural fiber plant material veneer. Alternatively, in some embodiments, the chemical treatments may be performed under ambient or elevated pressure conditions (e.g., 6-8 bar). In some embodiments, each or some of the chemical treatments may be performed at any temperature between ambient temperature (e.g., 23° C.) and elevated temperatures at which the solvents associated with the chemical treatments are boiling (e.g., 70-160° C.). In some embodiments, the solution is not agitated to minimize the amount of disruption to the microstructure of the natural fiber plant material.

[0071] In some embodiments, the soaking time can range from 0.1 hours to 96 hours, such as from 1 hour to 12 hours, inclusive. The amount of soaking time in the solution can be a function of the amount of lignin removed, the type of fibrous plant material, the size of the veneer, the temperature of the solution, the processing pressure, and / or agitation. For example, less lignin removal, smaller veneer size (e.g., thickness), higher solution temperature, higher processing pressure, and agitation can be associated with shorter soaking times, while more lignin removal, larger veneer size, lower solution temperature, lower processing pressure, and no agitation can be associated with longer soaking times.

[0072] In some embodiments, the chemical treatment solution includes an alkaline solution. In some embodiments, the chemical treatment solution includes sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na 2 SO 3), sodium sulfide (Na 2 S), Na n S (wherein n is an integer), urea (CH 4 N 2 O), sodium sulfite (NaHSO 3 ), sulfur dioxide (SO 2 ), anthraquinone (AQ) (C 14 H 8 O 2 ), methanol (CH 3 OH), ethanol (C 2 H 5 OH), butanol (C 4 H 9 OH), formic acid (CH 2 O 2 ), hydrogen peroxide (H 2 O 2 ), acetic acid (CH 3 COOH), butyric acid (C 4 H 8 O 2 ), peroxyformic acid (CH 2 O 3 ), peroxyacetic acid (C 2 H 4 O 3 ), ammonia (NH 3 ), tosylic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO 2 ), salt dioxide (ClO 2 ), Chlorine (Cl 2 ) or any combination of the above. Exemplary combinations of chemicals for chemical treatment include, but are not limited to, NaOH+Na 2 SO 3 , NaOH+Na 2 S, NaOH+urea, NaHSO 3 +SO 2 +H 2 O, NaHSO 3 +Na 2 SO 3 , NaOH+Na 2 SO 3 , NaOH+AQ, NaOH+Na 2 S+AQ, NaHSO 3 +SO 2 +H 2O+AQ, NaOH+Na 2 SO 3 + AQ, NaHSO 3 + AQ, NaHSO 3 +Na 2 SO 3 +AQ, Na 2 SO 3 +AQ, NaOH+Na 2 S+Na n S (n is an integer), Na 2 SO 3 +NaOH+CH 3 OH+AQ, C 2 H 5 OH+NaOH, CH 3 OH+HCOOH, NH 3 +H 2 O, and NaClO 2 Acetic acid may be mentioned.

[0073] At determining step 1008, chemical treatment can be continued (or repeated with subsequent solutions) until a desired reduction in lignin content in the fibrous plant material veneer is achieved. The lignin content can be reduced between 0.1% (the lignin content is 0.1% of the original lignin content in the natural fiber plant material) and 99% (the lignin content is 99% of the original lignin content in the natural fiber plant material) depending on the desired application. In some embodiments, where it may be desirable to retain as much of the natural fibrous plant material as possible, for example, the reduction in lignin content can be relatively small, for example, the lignin content is reduced by 10% or less compared to the original lignin content of the natural fibrous plant material. In some embodiments, a greater amount of lignin can be removed, for example, at least 90% of the original lignin content is removed (e.g., 90-100% of the lignin is removed). In some embodiments, the lignin content is reduced by 50% or less compared to the original lignin content in the natural fiber plant material. In some embodiments, the chemical treatment reduces the hemicellulose content simultaneously with the lignin content, e.g., to the same or lesser extent than the reduction in lignin content. In some embodiments, if the fibrous plant material veneer is hardwood or bamboo, the lignin content after delignification of treatment step 1006 may be at least 10% by weight (e.g., in the range of 10-15% by weight). In some embodiments, if the fibrous plant material veneer is softwood, the lignin content after delignification of treatment step 1004 may be at least 12.5% ​​by weight (e.g., in the range of 12.5-17.5% by weight).

[0074] In some embodiments, process step 1006 and / or decision step 1008 (e.g., before proceeding to process step 1014) may further include an optional rinsing step after chemical treatment, e.g., to remove residual chemicals or particulates resulting from the delignification process. For example, the delignified veneer may be partially or completely immersed in one or more rinse solutions. The rinse solution may be a solvent, e.g., but is not limited to, deionized (DI) water, alcohol (e.g., ethanol, methanol, isopropanol, etc.), or any combination thereof. For example, the rinse solution may be formed of equal amounts of water and ethanol. In some embodiments, rinsing may be performed without stirring, e.g., to avoid destruction of the microstructure. In some embodiments, rinsing may be repeated multiple times (e.g., at least three times) using a fresh mixture rinse solution for each repeat.

[0075] Alternatively, if lignin modification is desired in determining step 1004, the method 1000 can proceed to a treating step 1010, where the natural fiber plant material veneer can be infiltrated with one or more chemicals to modify the lignin therein. For example, in some embodiments, the infiltration can be performed by immersing the natural fiber plant material veneer under vacuum in a solution containing one or more chemicals. In some embodiments, the chemical solution can be OH. - ions or else in solution - The solution may include at least one chemical structure element capable of generating ions. In some embodiments, one, some, or all of the chemicals in the solution may be alkaline. In some embodiments, the chemical solution may include p-toluenesulfonic acid, NaOH, LiOH, KOH, Na 2 O, or any combination thereof. Exemplary combinations of chemicals include p-toluenesulfonic acid, NaOH, NaOH+Na 2 SO 3 / Na 2 SO 4 , NaOH+Na 2 S, NaHSO 3+SO 2 +H 2 O, NaHSO 3 +Na 2 SO 3 , NaOH+Na 2 SO 3 , NaOH / NaH 2 O 3 +AQ, NaOH / Na 2 S+AQ, NaOH+Na 2 SO 3 +AQ, Na 2 SO 3 +NaOH+CH 3 OH+AQ, NaHSO 3 +SO 2 +AQ, NaOH+Na 2 Sx (wherein AQ is anthraquinone), any of the above where NaOH is replaced with LiOH or KOH, or any combination of the above.

[0076] For example, in some embodiments, a wood veneer (e.g., basswood) can be immersed in a chemical solution (e.g., 2-5% NaOH) in a container. The container can then be placed in a vacuum box and subjected to a vacuum. In this way, the air in the veneer can be evacuated to create a negative pressure. When the vacuum pump is turned off, the negative pressure in the veneer can draw the solution into the veneer through the natural channels (e.g., lumens defined by the longitudinal cells) therein. This process can be repeated two or more times (e.g., three times) so that the inner channels of the veneer can be filled with the chemical solution (e.g., for about 2 hours). After this process, the moisture content can increase from ~10.2% (e.g., for natural wood) to ~70% or more. In some embodiments, the chemical infiltration can be performed without warming, for example, at room temperature (20-30°C, e.g., ~22-23°C). In some embodiments, the chemical solution is not stirred to avoid destruction of the cellulosic microstructure of the veneer.

[0077] The method 1000 may proceed to a treatment step 1012, where the modification may be activated by subjecting the infiltrated veneer to an elevated temperature, e.g., above 80° C. (e.g., 80-180° C., e.g., 120-160° C.), thereby resulting in a softened veneer (e.g., softened as compared to a natural fiber plant material veneer). In some embodiments, the exposure to elevated temperature in treatment step 1012 may be accomplished via steam heating, e.g., via steam generated in a closed reactor, via steam flow in a flow-through reactor, and / or via steam from a superheated steam generator. Alternatively or additionally, in some embodiments, the exposure to elevated temperature in treatment step 1012 may be accomplished by dry heating, e.g., via conduction and / or radiation of thermal energy from one or more heating elements, without the separate use of steam. In some embodiments, during treatment step 1012, the infiltrated veneer may be exposed to elevated temperature for a first period of time, e.g., 1-5 hours (e.g., depending on the size of the veneer, thicker pieces require longer heating times). In some embodiments, after the first period of time, any steam generated by heating the infiltrated veneer may be released, for example, by opening a pressure relief (e.g., a relief valve) of the reactor. For example, in some embodiments, the pressure relief may be effective to remove about 50% of the moisture in the modified veneer. For example, in some embodiments, the softened veneer may have a moisture content in the range of 30-50% by weight, inclusive. In some embodiments, the veneer may be further dried to reduce the moisture content of the veneer, but not so much that the fibrous plant material veneer loses its softened nature (e.g., such that the moisture content is about 8-10% by weight or more). In some embodiments, pre-drying may be effective to reduce the moisture content of the fibrous plant material veneer from greater than 30% by weight (e.g., 30-50% by weight), for example, to within the range of 10-20% by weight (e.g., 15% by weight). Moisture may be removed from the softened veneer via heating and / or pre-drying (e.g., by evaporation), however, the removed moisture may be substantially free of residual salts and / or chemicals from the in situ lignin modification.Rather, in some embodiments, the chemicals may be substantially consumed by the modification, and the residual salts may be retained within the microstructure of the softened veneer.

[0078] After processing step 1012 or determining step 1008, the method may proceed to processing step 1014, where optional pre-press modifications may be performed. In some embodiments, the pre-press modifications may include internal modifications of the lignin-impaired fibrous plant material veneer. Although the term "internal" is used to refer to the modifications of processing step 1014, it is contemplated that in some embodiments, the modifications may be applied to external as well as internal features of the lignin-impaired fibrous plant material veneer, while in other embodiments, the modifications may be applied to either internal or external features of the lignin-impaired fibrous plant material veneer without affecting the other features. In some embodiments, the internal modifications may include forming, depositing, or otherwise providing non-native particles on a surface of the lignin-impaired fibrous plant material veneer. Such surfaces may include at least the interior surfaces, e.g., cell walls lining the lumens, but may also include the exterior surfaces of the lignin-impaired fibrous plant material veneer. Non-natural particles incorporated onto the surface of lignin-impaired fibrous plant material veneers can stimulate the final structure to have certain advantageous properties, such as hydrophobicity, weather resistance, corrosion resistance (e.g., salt resistance), and / or flame resistance, among other properties. For example, in some embodiments, hydrophobic nanoparticles (e.g., SiO 2 Nanoparticles) can be formed on the surface of lignin-impaired fibrous plant material veneers.

[0079] Alternatively or additionally, in some embodiments, the internal modification can include carrying out further chemical treatments to modify the surface chemistry of the lignin-impaired fibrous plant material veneer. For example, in some embodiments, the further chemical treatments can include cuprates (CDDC), ammoniacal copper quaternary (ACQ), chromate copper arsenate (CCA), ammoniacal zinc arsenate (ACZA), copper naphthenate, acid copper chromate, copper citrate, copper azole, copper 8-hydroxyquinolinate, pentachlorophenol, zinc naphthenate, copper naphthenate, creosote, titanium dioxide, propiconazole, tebuconazole, cyproconazole, boric acid, borax, organic iodides (IPBC), and Na 2 B 8 O 13 4H 2 O.

[0080] Alternatively or additionally, in some embodiments, the internal modification of process step 1014 can include infiltrating the lignin-impaired fibrous plant material veneer with one or more polymers (or polymer precursors) to form a composite. For example, the lignin-impaired fibrous plant material veneer can be immersed in a polymer solution under vacuum. The polymer can be any type of polymer capable of infiltrating the pores of the softened plant material, for example, a synthetic polymer, a natural polymer, a thermosetting polymer, or a thermoplastic polymer. In some embodiments, the polymer-infiltrated fibrous plant material composite can be subsequently densified, for example, if the thickness of the veneer is 1 mm or more, allowing the veneer to be wrapped without breaking, cracking, or otherwise compromising the structure of the veneer. In some embodiments, the polymer infiltration can occur after drying of the veneer but before pressing of process step 1016. Alternatively, in some embodiments, the polymer infiltration can occur after drying and / or partial pressing of the veneer but before pressing of process step 1016.

[0081] For example, in some embodiments, the polymer may be an 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 terephthalate (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 - Ko - butylene adipate) (PBSA), polyhydroxybutyrate (PHB), poly(3 - Hydroxybutyrate - Ko - 3 -Poly(hydroxyvalerate) (PHBV), poly(glycolic acid) (PGA), polypyrrole (PPy), polythiophene (PTh), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), polyxylylene adipamide (MXD6), polyethylene (PE), polyvinyl chloride (PVC), poly(methyl methacrylate) (PMMA), acrylonitrile butadiene styrene (ABS), polyimide (PI), polyethyleneimine (PEI), polylactic acid (PLA), octadecyltrichlorosilane (OT S), polyoctahedral silsesquioxane (POSS), paramethylstyrene (PMS), polydimethylsiloxane (PDMS), poly(ethylene naphthalate (PEN), graft copolymer of acrylonitrile-butadiene-styrene-methyl methacrylate (ABSM), dodecyltrimethoxysilane (DTMS), rosin, chitin, chitosan, protein, vegetable oil, lignin, hemicellulose, carboxymethylcellulose, cellulose acetate, starch, agar, or combinations thereof.

[0082] The method 1000 may proceed to process step 1016, where the lignin-impaired veneer is pressed in a direction transverse to its longitudinal growth direction. In some embodiments, the pressing may be in a direction substantially perpendicular to the longitudinal growth direction, while in other embodiments, the pressing may have a force component perpendicular to the longitudinal growth direction. In either case, the pressing may be effective to reduce the thickness of the lignin-impaired fibrous plant material veneer, thereby increasing its density, as well as to collapse (at least partially) the natural lumens (e.g., vessels, lumens of each fiber, parenchymal cells, etc.), voids, and / or interstices within the cross-section of the lignin-impaired fibrous plant material veneer. In some embodiments, the pressing may be performed along a single direction (e.g., along the radial direction R), for example, to reduce the thickness of the lignin-impaired fibrous plant material veneer (e.g., a dimensional reduction of at least 5:2 compared to the lignin-impaired fibrous plant material veneer prior to pressing).

[0083] In some embodiments, pressing may be performed without prior drying of the lignin-impaired fibrous plant material veneer or with the lignin-impaired fibrous plant material veneer retaining at least some water or other fluids therein. Thus, pressing may be effective to remove at least some water or other fluids from the lignin-impaired fibrous plant material veneer while its dimensions are reduced and density is increased. In some embodiments, a separate drying process may be combined with the pressing process. For example, the lignin-impaired fibrous plant material veneer may be first compressed to cause densification and removal of at least some water or fluids therefrom, followed by a drying process (e.g., air drying) to remove remaining water or fluids. Alternatively, in some embodiments, the lignin-compromised fibrous plant material veneer can be first dried to remove at least some water or fluid therefrom (e.g., first drying in a humidity chamber, followed by air drying at room temperature, so that the moisture content of the plant material remains above 15% by weight, e.g., approaching 10% by weight), and then pressed to cause densification (and potentially removal of water or other fluids, e.g., to a moisture content of less than 10% by weight, e.g., 3-8% by weight).

[0084] In some embodiments, pressing can promote hydrogen bond formation between cellulosic fibers in the cell walls of the lignin-impaired fibrous plant material veneer, thereby improving the mechanical properties of the densified, lignin-impaired fibrous plant material veneer. Additionally, any particles or materials formed on the surface of the lignin-impaired fibrous plant material veneer or within the lignin-impaired fibrous plant material veneer (e.g., via the internal modification of processing step 1014) can be retained after pressing, while particles / materials on the internal surface are embedded within the collapsed lumens and intertwined cell walls.

[0085] The pressure and timing of pressing may be a function of the size of the lignin-impaired fibrous plant material veneer before pressing, the desired size of the lignin-impaired fibrous plant material veneer after pressing, the water or fluid content within the lignin-impaired fibrous plant material veneer (if any), the temperature at which pressing is performed, the relative humidity, the properties of the material (e.g., the impregnating polymer) from internal modifications (if any), and / or other factors. For example, the lignin-impaired fibrous plant material veneer may be held under pressure for a period of at least one minute to several hours (e.g., 1 to 180 minutes, inclusive). In some embodiments, the lignin-impaired fibrous plant material veneer may be held under pressure for 3 to 72 hours, inclusive. In some embodiments, pressing may be performed at a pressure of 0.5 MPa to 20 MPa, inclusive, for example, 5 MPa. In some embodiments, pressing may be performed without heat (e.g., cold pressing), while in other embodiments, pressing may be performed with heat (e.g., hot pressing). For example, pressing may be performed at a temperature between 20°C and 160°C, e.g., 100°C or higher.

[0086] The method 1000 may proceed to an optional process step 1018, where the densified, lignin-impaired fibrous plant material veneer may undergo an external modification. Although the term "external" is used to refer to the modification of process step 1018, it is contemplated that in some embodiments, the modification may be applied to internal as well as external features of the densified, lignin-impaired fibrous plant material veneer, while in other embodiments, the modification may be applied to either the internal or external features of the densified, lignin-impaired fibrous plant material veneer without affecting the other features. In some embodiments, the external modification may include forming, depositing, or otherwise providing a coating on one or more external surfaces of the densified, lignin-impaired fibrous plant material veneer. Coatings can stimulate the densified, lignin-impaired fibrous plant material veneer to have certain advantageous properties, such as, but not limited to, hydrophobicity, weather resistance, corrosion resistance (e.g., salt resistance), and / or flame resistance. For example, the coating can include oil-based paints, hydrophobic paints, polymeric coatings, and / or fire-resistant coatings. In some embodiments, the fire-resistant coating can include nanoparticles (e.g., boron nitride nanoparticles). Alternatively or additionally, in some embodiments, coatings for the densified, lignin-impaired fibrous plant material veneer can include boron nitride (BN), montmorillonite clay, hydrotalcite, silicon dioxide (SiO 2 ), sodium silicate, calcium carbonate (CaCO 3 ), aluminum hydroxide (Al(OH) 3 ), magnesium hydroxide (Mg(OH) 2 ), Magnesium carbonate (MgCO 3), aluminum sulfate, ferrous sulfate, zinc borate, zinc borate, boric acid, borax, triphenyl phosphate (TPP), melamine, polyurethane, ammonium polyphosphate, phosphate, phosphite ester, ammonium phosphate, ammonium sulfate, phosphonate, diammonium phosphate (DAP), ammonium dihydrogen phosphate, monoammonium phosphate (MAP), guanylurea phosphate (GUP), guanidine, dihydrogen phosphate, antimony pentoxide, or any combination of the above.

[0087] In some embodiments, the optional external modification of process step 1018 can include sealing the densified, lignin-impaired fibrous plant material veneer to prevent moisture ingress or moisture egress. In some embodiments, the sealing is by placing the veneer in a sealed or controlled environment. Alternatively or additionally, the sealing can be achieved by a protective layer or coating provided on the exposed surface of the veneer. For example, the protective layer or coating can be a polyurethane coating, a paint, a silane hydrophobic coating, or any other coating effective to prevent or at least limit the migration of moisture into or out of the fibrous plant material. Alternatively or additionally, the external modification can include destructive modification, such as machining or cutting to prepare the densified veneer for subsequent use.

[0088] Method 1000 may proceed to process step 1020, where the densified, lignin-impaired fibrous plant material veneer may be wrapped around a central axis to form a circumferentially extending wall, or at least a portion thereof, as described, for example, with respect to FIG. 10B. Although steps 1002-1020 of method 1000 have been described as being performed once, in some embodiments, multiple iterations of a particular process step may be used before proceeding to the next determining step or process step. In addition, while steps 1002-1020 of method 1000 are illustrated and described separately, in some embodiments, the process steps may be combined and performed together (concurrently or sequentially). Furthermore, while FIG. 10A illustrates a particular order of steps 1002-1020, embodiments of the disclosed subject matter are not limited thereto. Indeed, in certain embodiments, the steps may occur in a different order than those illustrated, or simultaneously with other steps. In some embodiments, the method 1000 may include only some of steps 1002-1020 of FIG. 10A.

[0089] Referring to FIG. 10B, a method 1022 for forming a circumferentially extending wall from one or more densified, lignin-impaired fibrous plant material veneers is shown. The method 1022 can begin with a determination step 1024 where the thickness of the veneer is evaluated. If the thickness is less than or equal to 1 mm (or if the veneer is more than 1 mm thick and is polymer impregnated), the method 1022 can proceed to a processing step 1026 where an adhesive can be applied to one or more surfaces (or surface portions) of the densified, lignin-impaired veneer. For example, the adhesive can be uniformly coated on the surface of the densified, lignin-impaired veneer prior to wrapping around a cylindrical form to form a hollow tube. In some embodiments, the veneer bonded by epoxy can exhibit a shear force of about 5.5 kN. For example, the adhesive may be an epoxy, polyvinyl acetate (PVA), polyurethane, cyanoacrylate, casein, urea-formaldehyde, aliphatic resin, contact cement, resorcinol-formaldehyde, phenol formaldehyde, sodium carboxymethylcellulose (CMC), animal collagen-derived glue, or any combination of the foregoing. The method 1022 may proceed to a process step 1028, where the densified, lignin-impaired veneer may be wrapped around a forming axis (e.g., a forming member, roller, and / or open space) to form a circumferentially extending layer. In some embodiments, the wrapping may have a longitudinal growth direction extending parallel to the forming axis (e.g., flat wrapping), a longitudinal growth direction at an angle to the forming axis (e.g., spiral wrap) or a longitudinal growth direction parallel to the circumferential direction (e.g., hoop wrap).

[0090] If the thickness of the veneer is greater than 1 mm (and / or the veneer is not impregnated with polymer), the method 1022 may proceed from decision step 1024 to decision step 1032, where it is determined whether a fluid shock treatment should be performed. If it is determined that a fluid shock will not be performed, the method 1022 may proceed from decision step 1032 to process step 1042, where the densified, lignin-damaged veneer may be partially dried. For example, the partial drying of process step 1042 may be such that the densified, lignin-damaged veneer has a moisture content of at least 30% by weight (e.g., ≧50% by weight). If it is instead determined that a fluid shock will be performed, the method 1022 may proceed from decision step 1032 to process step 1034, where the densified, lignin-damaged veneer is fully dried. For example, the thorough drying of process step 1034 may be such that the densified, lignin-impaired veneer has a moisture content of 15% by weight or less (e.g., less than 8-12% by weight, including, for example, 3-8% by weight).

[0091] The drying of either process step 1042 or process step 1034 can include any of a conductive, convective, and / or radiative heating process, including, but not limited to, an air drying process, a vacuum assisted drying process, an oven drying process, a freeze drying process, a critical point drying process, a microwave drying process, or any combination of the above. For example, an air drying process can include naturally drying the densified, lignin-damaged veneer in still or moving air, which can be at any temperature, such as room temperature (e.g., 23° C.) or elevated temperature (e.g., greater than 23° C.). For example, a vacuum assisted drying process can include subjecting the densified, lignin-damaged veneer to a reduced pressure, e.g., less than 1 bar, e.g., in a vacuum chamber or vacuum oven. For example, an oven drying process can include heating the densified, lignin-damaged veneer to an elevated temperature (e.g., greater than 23° C.), e.g., 70° C. or higher, using an oven, hot plate, or other conductive, convective, or radiative heating device. For example, a freeze drying step may involve lowering the temperature of the densified, lignin-damaged veneer below the freezing point of the fluid therein (e.g., below 0° C.) and then reducing the pressure to sublimate the frozen fluid therein (e.g., below a few millibars). For example, a critical point drying process may involve immersing the densified, lignin-damaged veneer in a fluid (e.g., liquid carbon dioxide), increasing the temperature and pressure of the densified, lignin-damaged veneer above the critical point of the fluid (e.g., 7.39 MPa, 31.1° C. for carbon dioxide), and then gradually releasing the pressure to remove the now gaseous fluid. For example, a microwave drying process can include inducing dielectric heating in the densified, lignin-impaired veneer by exposure to electromagnetic radiation having frequencies in the microwave regime (e.g., 300 MHz to 300 GHz), such as frequencies of ~915 MHz or ~2.45 GHz, using a microwave oven or other microwave generating device.

[0092] In some embodiments, the complete drying of process step 1034 causes the densified, lignin-compromised veneer to shrink, which in turn causes significant collapse of the cell walls. In some embodiments, the lumens formed by the longitudinal cells may collapse (e.g., completely collapse so that opposing faces of the channel walls touch, or at least the width of the channel is significantly narrowed). After drying of process step 1034, method 1022 can proceed to process step 1036, where the densified, lignin-compromised veneer is rehydrated using a fluid shock technique. For example, the densified, lignin-compromised veneer can be partially or completely immersed in a fluid (e.g., water, alcohol, or any combination thereof) for a short period of time (e.g., a few minutes, e.g., 3 minutes or less, e.g., on the order of a few seconds) such that the rehydrated material has a moisture content of at least 30% by weight (e.g., about 50% by weight). According to one or more embodiments, rehydration methods other than immersion in a fluid are also possible. For example, rehydration can be achieved by exposure to a humid environment.

[0093] In some embodiments, rehydration re-expands the cell walls, allowing larger lumens (e.g., vessels) to reopen, while smaller lumens (e.g., fiber cells) remain substantially collapsed. The swelling introduced by the fluid shock can create wrinkles in the cell wall structure, which can allow the softened fibrous plant material to accommodate severe tension and compression without damage.

[0094] For softened fibrous plant material having a moisture content of at least 30% by weight after either process step 1036 or process step 1042, method 1022 can proceed to process step 1038, where a water-based adhesive can be applied to one or more surfaces (or surface portions) of the densified, lignin-impaired veneer. For example, the adhesive can be uniformly coated on the surface of the densified, lignin-impaired veneer before wrapping it around a cylindrical form to form a hollow tube. For example, the water-based adhesive can be polyvinyl acetate (PVA), sodium carboxymethyl cellulose (CMC), water-based polyurethane, animal collagen-derived glue. Method 1022 can proceed to process step 1040, where the densified, lignin-impaired veneer can be wrapped around a forming axis (e.g., either a forming member or an open space) to form a circumferentially extending layer. In some embodiments, the wrapping may have a longitudinal growth direction parallel to the forming axis (e.g., flat wrapping), or may have a longitudinal growth direction at an angle to the forming axis (e.g., spiral wrap), or a longitudinal growth direction parallel to the circumferential direction (e.g., hoop wrap). During wrapping in process step 1040, the moisture content of the densified, lignin-impaired veneer may be at least 30% by weight, and thus may be substantially flexible / moldable. As a result, the veneer may readily adopt a desired circumferential shape without cracking, even though the veneer may be greater than 1 mm thick.

[0095] From either process step 1028 or process step 1040, method 1022 can proceed to decision step 1030, where it is determined whether another veneer layer should be added to the circumferentially extending wall. If an additional layer is desired, method 1022 can return to decision step 1024, otherwise the method can proceed to decision step 1044, where it is determined whether a post-molding modification is desired. In some embodiments, the post-molding modification can include applying a varnish, paint, stain, oil, wax, or any combination of the foregoing to one or more surfaces (e.g., inner, outer, and / or exposed surfaces) of the circumferentially extending wall. For example, the wrapped layers forming the wall can be sealed to prevent moisture ingress or egress, thereby maintaining the molded (e.g., rigid) state of the wall. Alternatively or additionally, the sealing can be achieved by a protective layer or coating provided on the exposed surface of the fibrous plant material. For example, the protective layer or coating can be a polyurethane coating, a paint, a silane hydrophobic coating, or any other coating effective to prevent or at least limit the migration of moisture into or out of the fibrous plant material. Alternatively or additionally, post-forming modification can include destructive modification, such as machining or cutting to prepare the lignin-modified fibrous plant material for subsequent use.

[0096] In some embodiments, post-molding modification can include forming a composite structure, in which case the method can proceed from determining step 1044 to processing step 1046. In processing step 1046, a non-vegetable layer can be provided (e.g., deposited, coated, laminated, etc.) on an inner surface of the wall extending in a circumferential direction, and / or another non-vegetable layer can be provided on an outer surface of the wall extending in a circumferential direction. In some embodiments, the non-vegetable layer can include metal, polymer, or concrete. If no modification is desired in determining step 1044, or after processing step 1046, the method can proceed to processing step 1048, where the wall formed by wrapping one or more densified, lignin-impaired fibrous plant material veneers around a central axis can be used in one or more applications, such as, but not limited to, structural applications, energy absorption (e.g., crash protection for buildings in earthquakes or other natural disasters, vehicle bumpers, aircraft ejector seats, etc.), and fluid transport. For example, in some embodiments, a tube made of densified, lignin-impaired wood veneer can have a compressive strength of -90 MPa, which is higher than an Al alloy tube.

[0097] Although some of steps 1024-1048 of method 1022 have been described as being performed once, in some embodiments, multiple iterations of a particular processing step may be used before proceeding to the next decision or processing step. Additionally, while steps 1024-1048 of method 1022 have been illustrated and described separately, in some embodiments, the processing steps may be combined and performed together (concurrently or sequentially). Furthermore, while FIG. 10B illustrates a particular order for 1024-1048, embodiments of the disclosed subject matter are not limited thereto. Indeed, in certain embodiments, steps may occur in a different order than illustrated, or simultaneously with other steps. In some embodiments, method 1022 may comprise only some of steps 1024-1048 of FIG. 10B.

[0098] Example of fabrication and experimental results Natural wood veneer (basswood, typical sample dimensions: 0.5 mm × 30 cm × 20 cm) was dissolved in 2.5 M NaOH and 0.4 M Na 2 SO 3 The wood veneer was then treated with a boiling aqueous solution of 0.01% glycerol for 1 hour, followed by several immersions in water to remove the chemicals. The partial delignification process removed approximately 70% of the lignin and 85% of the hemicellulose from the wood's lignocellulosic cell walls. The partially delignified wood veneer was then pressed at 105 °C under 5 MPa pressure for 5 minutes to reduce the density to 0.4 g / cm. 3 A highly dense delignified veneer was formed, with the tensile strength increasing from 0.01 g / cm to 1.3 g / cm. The tensile strength of the densified delignified veneer was ~650 MPa, approximately 10 times higher than that of natural wood veneer (66 MPa). Note that the tensile strength of the densified delignified veneer is tested along the cellulose fiber orientation, but due to the anisotropy of wood, the strength perpendicular to the cellulose fiber orientation is much lower (20.5 MPa).

[0099] The tubes were achieved by rolling the densified and delignified veneer onto a cylindrical mold in the direction of the wood fibers or at an angle and adhesion. Epoxy (Clear Weld 5 min, JB Weld) was used to glue adjacent layers within the tube wall. Three strategies for wrapping were adopted. The first strategy was to wrap the densified and delignified veneer onto a cylindrical mold along the cellulose fiber alignment direction and glue with epoxy. SEM morphology studies reveal that the different Superwood veneer layers are firmly glued to each other and the fibers are parallel to the axis of the tube, as shown in Figures 2E-2F. The second strategy was to wrap the densified and delignified veneer onto a cylindrical mold at a 45° angle and wrap each layer at the same angle, as shown in Figures 4A-4C. As a result, the cellulose fibers of each layer are parallel at the same angle. In this way, wood tubes of any length can be achieved. The third strategy was to roll up the densified and delignified veneer on the former with cross-spiral wrapping. Specifically, if the Superwood veneer on the first layer is rolled up in a left-handed spiral at an angle of 45°, the next layer is rolled up in the opposite direction (right-handed spiral) at the same angle, as shown in Figures 4D-4F, and repeated until the target wall thickness is reached. Thus, the cellulose fibers in different layers present the same angle to the tube axis, but opposite rolling directions.

[0100] The compressive strength of the resulting tube may depend on various parameters of the tube structure, including diameter, wall thickness, twist direction, etc. As shown in Figure 11, a tube with an inner diameter of 14 mm exhibits higher compressive strength than a tube with an inner diameter of 40 mm. The compressive strength increases as the wrap-up angle increases from 45° to 90° during the manufacture of the tube. Also, as shown in Figure 11, the compressive strength increases with increasing wall thickness. This indicates that the mechanical deformation of the circumferentially extending wood wall can be a multi-scale behavior that depends on the raw material (e.g., wood species), wood veneer (e.g., thickness, cutting direction), chemical treatment (e.g., lignin vs. cellulose fiber), tube (e.g., diameter, wrapping direction, number of veneer layers, and adhesive between layers).

[0101] Tubes prepared by cross-spiral wrapping (fiber direction is 45° away from the tube axial direction) also exhibit petal failure under compressive loading, but in a more complex manner. Under axial compression, tubes prepared by cross-spiral wrapping initially break at multiple locations at the ends along the cellulose fiber direction due to the anisotropy of the densified and delignified wood veneer. Furthermore, compressive loading causes the tube to split along the 45°. After splitting, the strip curls into a helical shape and protrudes radially. However, tubes prepared by rolling at a 45° angle did not exhibit the petal failure mode. Instead, the adhesive between the two layers of wrapped veneer is torn.

[0102] The unique failure mode of the densified and delignified wood veneer tube leads to a dramatic increase in energy absorption during the failure process compared to the failure of the isotropic aluminum tube. Figure 12(a) shows the force-displacement curves in an axial compression test of the flat-wrapped tube 1204, the aluminum tube 1202, and the carbon fiber cloth tube 1206. The compression failure of the aluminum tube is characterized by a sharp peak in the compression force at a fairly small displacement, corresponding to the onset of buckling of the tube, followed by a rapid drop in force to zero, indicating a loss of structural integrity as the deformation localizes at the buckling region, resulting in failure of the aluminum tube. In contrast, the force-displacement curve of the flat-wrapped tube 1204 peaks at a small displacement (corresponding to the onset of petals), but then drops to a moderate level and remains fairly constant over large displacements until the end of the test. The force-displacement curve of the carbon fiber cloth tube 1206 shows a similar trend, but with a dramatic drop in force after the peak. The area under the force-displacement curve measures the energy absorbed by the tube failure process. The tube prepared by flat wrapping exhibits a strong high specific energy absorption of 54.22 ± 2.18 J / g, which is 7.3, 1.3, and 1.5 times higher than the aluminum tube (7.41 ± 0.38 J / g), carbon fiber tube (41.80 ± 0.83 J / g), and cross-spiral wrapped tube (20.68 ± 1.71 J / g).

[0103] To further investigate the energy dissipation performance of wood tubes under different conditions, static (axial compression test) and dynamic (drop tower test) tests were conducted to investigate the failure behavior and the amount of energy absorbed by the tube. Two flat-wrapped tubes with different geometric dimensions, namely 40mm x 0.75mm x 100mm and 14mm x 0.75mm x 100mm (inner diameter x wall thickness x length), were used for the static tests. The inner diameter of the 40mm specimen shows a typical local buckling failure similar to the failure mode of aluminum alloy tubes. However, the inner diameter of the 14mm specimen exhibits a sunflower petal-like failure mode, which is rarely seen in other types of commercial tubes. The wood tube gradually cracks by splitting its thin circular wall into several petals, which curl on themselves during the test. Due to the significant amount of energy dissipation during wall splitting in the petal-like mode, the effective energy absorption under static compressive loading of the petal-like failure specimen (55.3 J / g) is ∼150 times higher than that of the locally buckled specimen (0.37 J / g).

[0104] To increase the energy dissipation in the inner diameter of the 40 mm wood tube, pre-cuts were applied to one end of the tube. Cracks initiated from these pre-cuts propagate along the axial direction as the compression cap is further displaced. The effective energy absorption of the pre-cut sample is 13.32 J / g, 36 times higher than that of the sample without pre-cuts (calculated from the area under the force-displacement curve in Figure S19).

[0105] A drop tower was used to dynamically test the wood tube. The tube was preloaded by the self-weight of a steel plate. A steel ball was dropped from a height and struck the center of the steel plate, dynamically impacting the wood tube. Due to the petal-like failure mode, the effective energy absorption in the dynamic shock test of the specimen was 48.34 J / g, which was comparable to that in the static test (55.3 J / g). Thus, the wood tube exhibits remarkable energy absorption performance under both static and dynamic loading.

[0106] Additionally, three successive shock tests were performed on the same three wood tubes. After the first shock test, the tube begins to petalize at the end that contacts the bottom end cap. After the second shock test, the petal formation at the bottom end of the tube progresses further and the top end of the tube also begins to petalize. After the third shock test, the petal formation at both ends progresses further. The wood tube is capable of absorbing dynamic shock energy at a level comparable to wood tubes under static compressive loads. Furthermore, the wood tube retains structural integrity even after being partially fractured by the petals. The unbroken portions of the wood tube are capable of continuing to absorb dynamic shock energy in subsequent tests. This is a unique and desirable feature that suggests potential use as a highly effective structural component for energy absorption, especially during dynamic shock.

[0107] In addition to excellent energy absorption, the wood tube also exhibits good thermal conductivity, suggesting that the wood tube can be used in construction. For example, the Superwood tube can replace aluminum alloy tubes for curtain wall door frames. The disclosed wood engineering process is also applied to the manufacture of pipes, and the wood pipes exhibit good gas barrier properties due to the dense structure of the densified and lignin-impaired wood veneer. As shown in Figure 13A, the permeability of the wood tube is 2.0 × 10 -17 2 / s, which is lower than the permeability of most polymers and comparable to that of steel tubes. Therefore, wood tubes are more resistant to the effects of oil and gas (e.g. H 2 and natural gas), but H 2 There is no problem of embrittlement.

[0108] The disclosed technology also includes, for example, curtain walls with low thermal conductivity instead of aluminum tubes, gas transport (e.g., H 2 , natural gas), but H 2It allows the preparation of tubes with low permeability without embrittlement problems, and tubes with good bending strength instead of concrete pipes. In the fabricated example, a wood pipe was constructed with a diameter of 16 cm. The wood tube exhibited a bending strength of 30.5 MPa, as shown in Figure 13B, which is about 5 times higher than that of the concrete pipe.

[0109] In addition to tubes and pipes, wood rods have also been produced by cross-spiral wrapping densified and delignified wood veneer onto a natural wood core at a 45° angle, which can improve the shock properties of the resulting product, as shown in Figure 9E. A 5 cm diameter baseball bat was also made by wrapping 90 layers of densified and delignified wood veneer onto a natural wood rod, as shown in Figure 9F.

[0110] Further examples of the disclosed technology In view of the above implementations of the disclosed subject matter, the present application discloses additional examples in the appendices listed below. It should be noted that any feature of the appendices alone, or two or more features of the appendices taken in combination, and optionally combined with one or more features of one or more additional appendices, are also included within the scope of the disclosure of the present application.

[0111] Appendix 1. A structure comprising one or more densified, lignin-impaired fibrous plant material veneers wrapped about a central axis to form a circumferentially extending fibrous plant material wall.

[0112] Appendix 2. The structure described in any section or example herein, particularly in Appendix 1, wherein adhesive is provided on one or more surface portions of each fibrous plant material veneer.

[0113] Appendix 3. The adhesive may specifically include epoxy, polyvinyl acetate (PVA), polyurethane, sodium carboxymethylcellulose (CMC), cyanoacrylate, casein, urea-formaldehyde, aliphatic resins, contact cement, resorcinol-formaldehyde, phenol formaldehyde, animal collagen-derived glue, or any combination of the foregoing, as described in any section or example herein, particularly the structure of Appendix 2.

[0114] Appendix 4. The structure of any one of the paragraphs or examples herein, particularly any one of appendices 2-3, wherein the circumferentially extending fibrous plant material wall consists essentially of one or more densified, lignin-impaired fibrous plant material veneers and adhesive.

[0115] Appendix 5. The structure of any one of the appendices or examples herein, particularly any one of appendices 1-4, wherein the circumferentially extending fibrous plant material walls exhibit a compressive strength of 50-90 MPa along a direction substantially parallel to the central axis.

[0116] Appendix 6. The structure of any one of the sections or examples herein, particularly any one of appendices 1-5, wherein each of the densified, lignin-impaired fibrous plant material veneers comprises cellulose nanofibers that form walls of disrupted longitudinal fibrous plant material cells, the cellulose nanofibers being substantially aligned with the longitudinal growth direction of the fibrous plant material.

[0117] Appendix 7. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 1-6, wherein each of the densified, lignin-impaired fibrous plant material veneers has a tensile strength along its longitudinal growth direction of at least 400 MPa.

[0118] Appendix 8. The structure of any one of the paragraphs or examples herein, particularly any one of appendixes 1-7, wherein the longitudinal growth direction of at least one of the one or more densified, lignin-depleted fibrous plant material veneers is substantially parallel to the central axis.

[0119] Appendix 9. The structure of any one of the paragraphs or examples herein, particularly any one of clauses 1-8, wherein the longitudinal growth direction of at least one of the one or more densified, lignin-impaired fibrous plant material veneers is substantially perpendicular to a plane containing the central axis.

[0120] Appendix 10. The structure of any one of the paragraphs or examples herein, particularly any one of appendixes 1-9, wherein the longitudinal growth direction of at least one of the one or more densified, lignin-impaired fibrous plant material veneers is at a non-zero angle relative to the central axis.

[0121] Appendix 11. The structure of any paragraph or example herein, particularly appended claim 10, wherein the non-zero angle between the longitudinal growth direction and the central axis is in the range of 10° to 80°.

[0122] Appendix 12. The non-zero angle between the longitudinal extension direction and the central axis is approximately 45°.

[0123] Appendix 13. The structure of any paragraph or example of the specification, particularly any one of paragraphs 10-12, wherein a first longitudinal growth direction orientation of the one or more densified, lignin-impaired fibrous plant material veneers intersects with a second longitudinal growth direction orientation of the one or more densified, lignin-impaired fibrous plant material veneers.

[0124] Appendix 14. The structure of any paragraph or example herein, particularly paragraph 13, wherein the longitudinal growth directions of a first and second of the one or more densified, lignin-impaired fibrous plant material veneers intersect at an angle of substantially 90°.

[0125] Appendix 15. At least one of the one or more densified, lignin-impaired fibrous plant material veneers has a density of at least 1 g / cm 3 or a structure according to any of the sections or examples herein, particularly any one of appendices 1 to 14, having a density of at least 1.15 g / cm.

[0126] Appendix 16. At least one of the one or more densified, lignin-impaired fibrous plant material veneers has a density of about 1.3 g / cm 3 , or 1.3 to 1.5 g / cm 3 The structure of any section or example herein, particularly any one of appendices 1 to 15, having a thickness of (inclusive).

[0127] Appendix 17. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 1-16, wherein the inner diameter of the circumferentially extending fibrous plant material wall is at least 5 mm, at least 1 cm, or at least 10 cm.

[0128] Appendix 18. The structure of any one of the paragraphs or examples herein, particularly any one of appendices 1-17, wherein the length of the fibrous plant material wall extending circumferentially along its axis is at least 1 cm, at least 10 cm, or at least 1 m.

[0129] Appendix 19. The structure of any one of the sections or examples herein, particularly any one of clauses 1-18, wherein the circumferentially extending fibrous plant material walls exhibit a specific energy absorption of at least 45 J / g under compression along a direction substantially parallel to the central axis.

[0130] Appendix 20. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 1-19, wherein the cross-sectional shape of the circumferentially extending fibrous plant material wall is circular, triangular, or rectangular.

[0131] Appendix 21. The structure according to any of the sections or examples herein, in particular any one of appendices 1 to 20, wherein the structure forms a hollow member open at both axial ends.

[0132] Appendix 22. The structure of any of the sections or examples herein, particularly any one of appendices 1 to 21, wherein the hollow member is a tube or a pipe.

[0133] Appendix 23. The structure of any of the sections or examples herein, particularly any one of appendixes 1-20, wherein the circumferentially extending fibrous plant material wall forms a hollow member open at one axial end, and the structure further comprises one or more second members closing an opposite axial end of the hollow member.

[0134] Appendix 24. The structure of any section or example herein, particularly claim 23, wherein the one or more second members are formed from a natural fibrous plant material, a metal, a polymer, cork, cement, a densified fibrous plant material, or a densified lignin-containing fibrous plant material.

[0135] Appendix 25. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 23-24, forming a closed-ended tube, cup, tank, or bottle.

[0136] Appendix 26. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 1-20, wherein the circumferentially extending fibrous plant material walls further comprise one or more central members wrapped therearound.

[0137] Appendix 27. The structure of any section or example herein, particularly appended claim 26, wherein the one or more central members comprise natural fibrous plant material rods, metal rods, polymer rods, cork rods, densified fibrous plant material rods, lignin-impaired fibrous plant material rods, densified and lignin-impaired fibrous plant material rods, or any combination of the foregoing.

[0138] Appendix 28. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 26-27, forming a rod, bat, club, or dowel rod.

[0139] Appendix 29. (a) one or more first non-vegetable layers disposed on an interior surface portion of the circumferentially extending fibrous plant material wall; (b) one or more second non-vegetable layers disposed on an outer surface portion of the circumferentially extending fibrous plant material wall; or Both (a) and (b); The structure of any one of the sections or examples herein, particularly any one of appendices 1 to 22, comprising:

[0140] Appendix 30. The structure of any of the clauses or examples herein, in particular any one of clauses 29, wherein some or all of the non-vegetable layers are comprised of metal, polymer, or concrete.

[0141] Appendix 31. The structure of any one of the paragraphs or examples herein, particularly any one of appendices 29-30, wherein the total thickness of the one or more first non-plant layers is 50% or less of the total thickness of the fibrous plant material walls extending in a circumferential direction along the radial direction of the fibrous plant material walls, and / or the total thickness of the one or more second non-plant layers is 50% or less of the total thickness of the fibrous plant material walls extending in a circumferential direction along the radial direction of the fibrous plant material walls.

[0142] Appendix 32. The structure of any paragraph or example herein, particularly any one of clauses 1-31, wherein one, some or all of the one or more densified, lignin-impaired fibrous plant material veneers comprise modified lignin therein, the modified lignin having shorter polymer chains than the native lignin in the natural fibrous plant material.

[0143] Appendix 33. The structure of any of the paragraphs or examples herein, particularly any one of appendices 1-32, wherein the content of modified lignin in one, some or all of the one or more densified, lignin-impaired fibrous plant material veneers is at least 90% of the content of native lignin in the native fibrous plant material.

[0144] Appendix 34. The structure of any one of the paragraphs or examples herein, particularly any one of paragraphs 1-33, wherein the modified lignin content in one, some or all of the one or more densified, lignin-impaired fibrous plant material veneers is at least 20% by weight.

[0145] Appendix 35. The structure of any one of paragraphs or examples herein, particularly any one of paragraphs 1-34, wherein one, some, or all of the one or more densified, lignin-impaired fibrous plant material veneers comprise an alkaline chemical salt immobilized within the cellulosic microstructure.

[0146] Appendix 36. The structure of any of the sections or examples herein, particularly appendix 35, wherein the salt is substantially pH neutral.

[0147] Appendix 37. The structure of any one of the sections or examples herein, particularly any one of clauses 1-31, wherein one, some or all of the one or more densified, lignin-compromised fibrous plant material veneers comprise at least partially delignified fibrous plant material.

[0148] Appendix 38. The structure of any paragraph or example herein, particularly appended claim 37, wherein the lignin content of the at least partially delignified fibrous plant material is between 10% and 99% (inclusive) of the lignin content of the natural fibrous plant material.

[0149] Appendix 39. The structure of any one of the paragraphs or examples herein, in particular any one of Appendices 37-38, wherein the at least partially delignified fibrous plant material is a hardwood or bamboo and the lignin content of the at least partially delignified fibrous plant material is between 1.8% by weight and 24.8% by weight, inclusive; or the at least partially delignified fibrous plant material is a softwood and the lignin content of the at least partially delignified fibrous plant material is between 2.5% by weight and 34.7% by weight, inclusive.

[0150] Appendix 40. The structure of any of the paragraphs or examples herein, particularly any one of paragraphs 37-38, wherein the lignin content of the at least partially delignified fibrous plant material is 10% by weight or less.

[0151] Appendix 41. The structure of any one of the paragraphs or examples herein, particularly any one of appendices 37-38, wherein the lignin content of the at least partially delignified fibrous plant material is less than 10% of the lignin content of the natural fibrous plant material.

[0152] Appendix 42. The structure of any one of the paragraphs or examples herein, in particular any one of appendices 37-38, wherein the at least partially delignified fibrous plant material is a hardwood or bamboo and the lignin content of the at least partially delignified fibrous plant material is less than 2.5% by weight, or the at least partially delignified fibrous plant material is a softwood and the lignin content of the at least partially delignified fibrous plant material is less than 3.5% by weight.

[0153] Appendix 43. The structure of any of the paragraphs or examples herein, particularly any one of paragraphs 1-42, wherein one, some or all of the densified, lignin-impaired fibrous plant material veneers have a thickness along a radial direction of the circumferentially extending fibrous plant material wall of 3 mm or less.

[0154] Appendix 44. The structure of any of the paragraphs or examples herein, particularly any one of paragraphs 1-43, wherein one, some or all of the densified, lignin-impaired fibrous plant material veneers have a thickness along a radial direction of the circumferentially extending fibrous plant material wall of 300 μm or less.

[0155] Note 45. The structure of any one of paragraphs or examples herein, particularly any one of paragraphs 1-44, wherein one, some or all of the densified, lignin-impaired fibrous plant material veneers have a thickness along a radial direction of the circumferentially extending fibrous plant material wall in the range of 100 to 250 μm, inclusive.

[0156] Appendix 46. The structure of any one of the sections or examples herein, particularly any one of Appendix 1, further comprising a protective layer or coating formed on one or more surfaces of the circumferentially extending fibrous plant material wall.

[0157] Appendix 47. The structure of any of the sections or examples herein, particularly any one of appendices 1-46, wherein one, some or all of the one or more densified, lignin-impaired fibrous plant material veneers are compressed in a direction substantially perpendicular to the longitudinal growth direction of the fibrous plant material, such that the lumens formed by the cellulosic cell walls in the fibrous plant material microstructure are substantially collapsed.

[0158] Note 48. The structure of any one of the sections or examples herein, particularly any one of clauses 1-47, wherein one, some or all of the one or more densified, lignin-impaired fibrous plant material veneers have a moisture content of 15% by weight or less.

[0159] Appendix 49. The structure of any of the paragraphs or examples herein, particularly any one of paragraphs 1-48, wherein the length of the fibrous plant material wall extending in a circumferential direction parallel to the central axis is at least 10 times the thickness of the fibrous plant material wall extending in a circumferential direction perpendicular to the central axis.

[0160] Note 50. The structure of any of the paragraphs or examples herein, particularly any one of paragraphs 1-49, wherein the fibrous plant material is hardwood, softwood, or bamboo.

[0161] Note 51. An energy absorption system comprising a plurality of structures, each of the plurality of structures comprising a structure according to any section or example herein, in particular any one of appendices 1-50.

[0162] Appendix 52. The energy absorption system of any section or example herein, particularly of Appendix 51, further comprising a pair of support members, the plurality of structures being sandwiched between the pair of support members.

[0163] Note 53. The energy absorption system of any section or example herein, particularly of Appendix 52, wherein the support member is formed from a natural fibrous plant material, a metal, a polymer, concrete, a densified fibrous plant material, or a densified, lignin-impaired fibrous plant material.

[0164] Note 54. The energy absorption system of any one of the paragraphs or examples herein, particularly any one of paragraphs 52-53, wherein the central axis of each structure is substantially perpendicular to the respective opposing surface portions of each support member.

[0165] Note 55. The energy absorption system of any one of the sections or examples herein, particularly any one of appendices 52-53, wherein the central axis of each structure is substantially parallel to the central axes of the other structures of the plurality of structures.

[0166] Note 56. The energy absorption system of any one of the sections or examples herein, particularly any one of notes 51-55, wherein each structure further comprises an end cap coupled to a respective axial end of the circumferentially extending fibrous plant material wall, the end cap being in contact with an opposing surface portion of the respective support member.

[0167] Note 57. The energy absorption system of any section or example herein, particularly any one of paragraphs 51-56, wherein at least a portion of one, some, or all of the plurality of structures is hollow.

[0168] Note 58. (a) subjecting one or more natural fiber plant material veneers to one or more chemical treatments to form one or more lignin-impaired veneers; (b) after (a), compressing the one or more lignin-damaged veneers along a direction transverse to the longitudinal growth direction of the fibrous plant material to form one or more densified lignin-damaged veneers; (c) after (b), wrapping and winding one or more densified, lignin-impaired veneers about the central axis to form a circumferentially extending fibrous plant material wall.

[0169] Note 59. The method of any section or example herein, particularly paragraph 58, further comprising, after (b) and prior to (c), providing an adhesive on one or more surface portions of one, some, or all of the one or more densified, lignin-impaired veneers.

[0170] Note 60. The method of any paragraph or example herein, particularly paragraph 59, wherein the adhesive comprises an epoxy, polyvinyl acetate (PVA), polyurethane, sodium carboxymethylcellulose (CMC), cyanoacrylate, casein, urea-formaldehyde, aliphatic resin, contact cement, resorcinol-formaldehyde, phenol formaldehyde, animal collagen-derived glue, or any combination thereof.

[0171] Appendix 61. The method of any of the paragraphs or examples herein, particularly any of Appendices 58-60, wherein after (b), each of the densified, lignin-impaired fibrous plant material veneers comprises cellulose nanofibers that form walls of disrupted longitudinal fibrous plant material cells, the cellulose nanofibers being substantially aligned with the longitudinal growth direction of the fibrous plant material.

[0172] Appendix 62. The method of any of the paragraphs or examples herein, particularly any of paragraphs 58-61, wherein the wrapping in (c) is such that the longitudinal growth direction of at least one of the one or more densified, lignin-impaired fibrous plant material veneers is substantially parallel to the central axis.

[0173] Appendix 63. The method of any one of paragraphs or examples herein, particularly paragraphs 58-62, wherein the wrapping in (c) is such that a longitudinal growth direction of at least one of the one or more densified, lignin-impaired fibrous plant material veneers is at a non-zero angle relative to the central axis.

[0174] Note 64. The method according to any of the clauses or examples herein, particularly clause 63, wherein the non-zero angle between the longitudinal extension direction and the central axis is in the range of 10° to 80°, inclusive.

[0175] Note 65. The method of any one of the paragraphs or examples herein, particularly paragraphs 63-64, wherein the non-zero angle between the longitudinal extension direction and the central axis is about 45°.

[0176] Note 66. The method of any of the paragraphs or examples herein, particularly any one of paragraphs 58-65, wherein the wrapping in (c) is such that a first longitudinal growth direction orientation of the one or more densified, lignin-impaired fibrous plant material veneers intersects a second longitudinal growth direction orientation of the one or more densified, lignin-impaired fibrous plant material veneers.

[0177] Note 67. 67. The method of any one of claims 58-66, wherein the wrapping of (c) is such that the first and second longitudinal growth directions of the one or more densified, lignin-impaired fibrous plant material veneers intersect at an angle of substantially 90°.

[0178] Note 68. The method of any one of the paragraphs or examples herein, particularly any one of appendices 58-67, wherein the wrapping in (c) comprises: (c1) placing one or more densified, lignin-damaged fibrous plant material veneers onto the form; (c2) removing the mold from the one or more densified, lignin-impaired fibrous plant material veneers after the first time, such that at least a portion of the circumferentially extending fibrous plant material walls are hollow.

[0179] Note 69. The method according to any of the paragraphs or examples herein, particularly paragraph 68, wherein the mould has a circular, triangular or rectangular cross-section.

[0180] Appendix 70. (c) wrapping includes placing one or more densified, lignin-impaired, fibrous plant material veneers over the one or more first non-plant layers; After (c), the one or more first non-plant layers are retained on the inner surface portion of the circumferentially extending fibrous plant material wall.

[0181] Appendix 71. (d) after (c), disposing one or more first non-vegetable layers on the interior surface portion of the circumferentially extending fibrous plant material wall; (e) after (c), disposing one or more second non-vegetable layers over an exterior portion of the circumferentially extending fibrous plant material wall; or Both (d) and (e); The method of any one of the sections or examples herein, particularly any one of appendices 58 to 70, comprising:

[0182] Appendix 72. The method of any of the paragraphs or examples herein, particularly any one of paragraphs 70-71, wherein one, some, or all of the non-vegetable layers are comprised of metal, polymer, or concrete.

[0183] Appendix 73. (a) subjecting the material to one or more chemical treatments (a1) impregnating one or more natural fiber plant material veneers with one or more chemical solutions; (a2) after (a1), subjecting the one or more natural fiber plant material veneers to a first temperature of at least 80° C. for an i-th period of time to form one or more lignin-damaged veneers; Including, after (c), the retained lignin in the one or more lignin-impaired veneers has shorter polymer chains than the native lignin in the one or more natural fibrous plant material veneers prior to (a); The method of any one of the sections or examples herein, in particular any one of paragraphs 58 to 72.

[0184] Note 74. The method of any paragraph or example herein, particularly paragraph 73, wherein after (c), each lignin-compromised veneer comprises pH-neutral salts of one or more chemical solutions immobilized within the substantially disintegrated cellulose-based microstructure of the veneer.

[0185] Appendix 75. The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 73-74, wherein the salt is formed during (a2) by reaction of the one or more chemical solutions with acidic decomposition products of natural hemicellulose in the one or more natural fiber plant material veneers produced by the one or more chemical solutions.

[0186] Appendix 76. The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 73-75, wherein the one or more chemical solutions include an alkaline solution.

[0187] Appendix 77. One or more chemical solutions are p-toluenesulfonic acid, NaOH, NaOH+Na 2 SO 3 / Na 2 SO 4 , NaOH+Na 2 S, NaHSO 3 +SO 2 +H 2 O, NaHSO 3 +Na 2 SO 3 , NaOH+Na 2 SO 3 , NaOH / NaH 2 O 3 +AQ, NaOH / Na 2 S+AQ, NaOH+Na 2 SO 3 +AQ, Na 2 SO 3 +NaOH+CH 3 OH+AQ, NaHSO 3 +SO 2 +AQ, NaOH+Na 2Sx (wherein AQ is anthraquinone), any of the above wherein NaOH is replaced with LiOH or KOH, or any combination of the above.

[0188] Note 78. The method according to any of the paragraphs or examples herein, in particular any one of Appendices 73 to 77, wherein the first temperature is 120 to 160° C. (inclusive).

[0189] Appendix 79. The method according to any of the clauses or examples herein, particularly any one of appendices 73-78, wherein the first period of time is in the range of 1 to 5 hours (inclusive).

[0190] Note 80. The method of any one of the paragraphs or examples herein, particularly paragraphs 73-79, wherein at least 90% of the one or more chemical solutions infiltrated into the one or more natural fiber plant material veneers is consumed during (a2).

[0191] Appendix 81. The method of any one of the paragraphs or examples herein, particularly paragraphs 73-80, wherein the subjecting to the first temperature in (a2) comprises using steam to heat the one or more natural fiber plant material veneers having the one or more chemical solutions therein.

[0192] Note 82. The method of any one of paragraphs or examples herein, particularly any one of paragraphs 58-72, wherein (a) subjecting to one or more chemical treatments comprises partially or fully immersing in one or more chemical solutions at a second temperature for a second time to remove at least some lignin from the one or more natural fiber plant material veneers.

[0193] Note 83. The method of any of the paragraphs or examples herein, particularly paragraph 82, wherein the one or more chemical solutions comprises an alkaline solution.

[0194] Note 84. One or more chemical solutions may be sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na 2 SO 3 ), Sodium sulfate (Na 2 SO 4 ), sodium sulfide (Na 2 S), Na n S (where n is an integer), urea (CH 4 N 2 O), sodium bisulfite (NaHSO 3 ), NaH 2 O 3 , sulfur dioxide (SO 2 ), anthraquinone (C 14 H 8 O 2 OI), methanol (CH 3 OH), ethanol (C 2 H 5 OH), butanol (C 4 H 9 OH), formic acid (CH 2 O 2 ), hydrogen peroxide (H 2 O 2 ), acetic acid (CH 3 COOH), butyric acid (C 4 H 8 O 2 ), peroxyformic acid (CH 2 O 3 ), peroxyacetic acid (C 2 H 4 O 3 ), ammonia (NH 3 ), tosylic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaClO 2 ), chlorine dioxide (ClO 2 ), Chlorine (Cl 2 ), water (H 2 O), or any combination of the above, any one of the sections or examples herein, particularly any one of appendices 82-83.

[0195] Note 85. One or more chemical solutions contain sodium hydroxide and Na 2 SO 3 The method according to any of the sections or examples herein, particularly any one of appendices 82-84, comprising a boiling solution of

[0196] Note 86. (i) the second temperature is 100 to 160° C.; (ii) the second time period is within the range of 0.1 to 96 hours, inclusive; or Both (i) and (ii), The method of any one of the sections or examples herein, particularly any one of paragraphs 82 to 85.

[0197] Appendix 87. The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 82-86, wherein (a) subjecting to one or more chemical treatments removes between 1% and 90%, inclusive, of the native lignin in the one or more natural fibrous plant material veneers to form one or more lignin-impaired fibrous plant material veneers.

[0198] Note 88. The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 82-86, wherein (a) subjecting to one or more chemical treatments removes more than 90% of the native lignin in the one or more natural fibrous plant material veneers to form one or more lignin-impaired fibrous plant material veneers.

[0199] Appendix 89. The method of any section or example herein, particularly any one of paragraphs 58-88, wherein the one or more natural fiber plant material veneers have a first thickness along a direction substantially perpendicular to the longitudinal growth direction, and the one or more densified, lignin-impaired veneers have a second thickness along a direction substantially perpendicular to the longitudinal growth direction, the first thickness being at least twice the second thickness.

[0200] Appendix 90. The method of any one of the paragraphs or examples herein, particularly paragraph 89, wherein the first thickness is in the range of 0.02 mm to 1.5 mm (inclusive) and / or the second thickness is 300 μm or less.

[0201] Appendix 91. The method of any one of paragraphs or examples herein, particularly paragraphs 58-90, wherein the compressing of (b) comprises pressing the one or more lignin-impaired fibrous plant material veneers at a first pressure of at least 5 MPa for a pressing time.

[0202] Appendix 92. The first pressure is in the range of 5 to 20 MPa (inclusive); The pressing time is at least 5 minutes, or Both of the above, Any section or example herein, in particular the method of paragraph 91.

[0203] Appendix 93. The method of any one of the paragraphs or examples herein, particularly paragraphs 58-92, wherein the compressing in (b) comprises pressing the one or more lignin-impaired fibrous plant material veneers while subjecting them to a pressing temperature of at least 80°C.

[0204] Appendix 94. (c) wherein the one or more densified, lignin-impaired veneers have a moisture content in the range of 30 to 40 weight percent, inclusive; The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 58-93, further comprising, after (c), drying the one or more densified, lignin-impaired veneers to have a moisture content of 15% by weight or less.

[0205] Appendix 95. The method of any paragraph or example herein, particularly paragraph 94, wherein during (c), the thickness of the one or more densified, lignin-impaired veneers is within the range of 1 to 3 mm, inclusive.

[0206] Appendix 96. The method of any one of the paragraphs or examples herein, particularly paragraphs 58-93, wherein during (c), the moisture content of the one or more densified, lignin-damaged veneers is 15% by weight or less.

[0207] Appendix 97. The method of any paragraph or example herein, particularly paragraph 96, wherein during (c), the thickness of the one or more densified, lignin-impaired veneers is less than 1 mm.

[0208] Appendix 98. The method of any one of the paragraphs or examples herein, particularly paragraphs 58-97, further comprising, prior to (a), cutting a substantially cylindrical portion of the natural fiber plant material using a roll-cutting technique to form one or more natural fiber plant material veneers.

[0209] Appendix 99. The method of any paragraph or example herein, particularly any one of paragraphs 58-98, further comprising, after (c), subjecting the circumferentially extending fibrous plant material wall to an axial load such that one or both axial ends of the circumferentially extending fibrous plant material wall exhibit a petal-type failure mode.

[0210] Appendix 100. The method of any one of the paragraphs or examples herein, particularly paragraphs 58-99, further comprising, after (c), using the circumferentially extending fibrous plant material wall as a fluid carrying tube or pipe.

[0211] Appendix 101. The method of any one of the paragraphs or examples herein, particularly any one of paragraphs 58-100, further comprising, after (c), using a circumferentially extending fibrous plant material wall as an insulating component.

[0212] Appendix 102. The method of any one of the paragraphs or examples herein, particularly paragraphs 58-101, wherein the fibrous plant material is hardwood, softwood, or bamboo.

[0213] conclusion Any of the features shown or described herein, for example, with respect to Figures 1A-13B and Supplements 1-102, can be combined with any other features shown or described herein, for example, with respect to Figures 1A-13B and Supplements 1-102, to provide materials, systems, devices, structures, methods, and embodiments not otherwise shown or specifically described herein. All features described herein are independent of one another and can be used in combination with any other features described herein, unless structurally impossible. In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are examples only and should not be construed as limiting the scope of the disclosed technology. Rather, the scope is defined by the following claims. Accordingly, we claim all that comes within the scope and spirit of these claims.

Claims

1. (a) Subjecting one or more natural wood veneers to one or more chemical treatments to form wood veneers in which one or more lignins have been damaged. (b) After (a), compress one or more lignin-damaged wood veneers along a direction intersecting the longitudinal growth direction of the wood to form one or more high-density, lignin-damaged wood veneers. (c) After (b) above, one or more high-density, lignin-degraded wood veneers are wrapped around the central axis to form a circumferentially extending wood wall. Methods that include...

2. The method according to claim 1, further comprising providing an adhesive on one or more surface portions of each wood veneer after (b) and before (c).

3. After (b), each of the densely densified and lignin-damaged wood veneers contains cellulose nanofibers that form the walls of the collapsed longitudinal wood cells, wherein the cellulose nanofibers are substantially aligned with the longitudinal growth direction of the wood. The method according to claim 1, wherein the wrapping in (c) is such that the longitudinal growth direction of at least one of the one or more high-densification, lignin-degraded wood veneers is substantially parallel to the central axis.

4. After (b), each of the densely densified and lignin-degraded wood veneers contains cellulose nanofibers that form the walls of the collapsed longitudinal wood cells, wherein the cellulose nanofibers are substantially aligned with the longitudinal growth direction of the wood. The method according to claim 1, wherein the wrapping in (c) is such that the growth direction of each longitudinal side of the densely packed, lignin-degraded wood veneer is at a non-zero angle with respect to the central axis.

5. The wrapping in (c) is such that the growth direction of each longitudinal side of the densely packed, lignin-degraded wood veneer is at a non-zero angle with respect to the central axis, The method according to claim 1, wherein the angle between the longitudinal extension direction and the central axis is within the range of 10° to 80° (including both endpoints).

6. The method according to claim 1, wherein the wrapping in (c) is such that the orientation of the first longitudinal growth direction of one or more high-density, lignin-degraded wood veneers intersects with the orientation of the second longitudinal growth direction of one or more high-density, lignin-degraded wood veneers.

7. Subjecting to one or more chemical treatments as in (a) is: (a1) Impregnating one or more natural wood veneers with one or more chemical solutions, (a2) To form wood veneers in which one or more lignins have been damaged by impregnating one or more natural wood veneers with one or more chemical solutions and exposing them to a first temperature of at least 80°C for a first time, Includes, After (c) above, the lignin retained in the wood veneer in which one or more lignins have been damaged has shorter macromolecular chains than the natural lignin in the one or more natural wood veneers prior to (a) above. The method according to claim 1.

8. After (c), each of the lignin-damaged wood veneers comprises a pH-neutral salt of the one or more chemical solutions immobilized within the substantially disintegrated cellulosic microstructure of the wood veneer. The method according to claim 7, wherein the salt is formed during (a2) by a reaction between the one or more chemical solutions and the acidic decomposition products of natural hemicellulose in the one or more natural wood veneers produced by the one or more chemical solutions.

9. The method according to claim 1, wherein subjecting to one or more chemical treatments in (a) comprises partially or completely immersing in one or more chemical solutions at a second temperature for a second time to remove at least some lignin from one or more natural wood veneers.

10. (i) During the period of (c) above, the thickness of one or more high-density, lignin-degraded wood veneers is in the range of 1 to 3 mm (including both end values), and one or more high-density, lignin-degraded wood veneers have a water content in the range of 30 to 40% by weight, The above method further, The process, following (c) above, includes drying one or more high-density, lignin-degraded wood veneers to a moisture content of 15% by weight or less, or (ii) The method according to claim 1, wherein, during (c), the thickness of one or more high-density veneers with reduced lignin is less than 1 mm, and the moisture content of the one or more high-density veneers with reduced lignin is 15% by weight or less.

11. The wrapping in (c) is (c1) Placing one or more high-density, lignin-degraded wood veneers on the mold, (c2) After the first time, remove the mold from one or more densified, lignin-degraded wood veneers such that at least a portion of the circumferentially extending wood wall is hollow. The method according to claim 1, including the method described in claim 1.

12. The method according to claim 1, wherein the one or more natural wood veneers are hardwoods, conifers, or bamboo.

13. A circumferentially extending wooden wall formed by the method described in any one of claims 1 to 12, Each of the densely packed, lignin-degraded wood veneers contains cellulose nanofibers that form walls of broken longitudinal wood cells, the cellulose nanofibers extending circumferentially in a wood wall substantially aligned with the longitudinal growth direction of the wood.

14. At least one of the one or more high-densification, lignin-degraded wood veneers contains at least 1 g / cm³ ３ A circumferentially extending wooden wall according to claim 13, having the density of [a specific density].

15. The circumferentially extending wooden wall according to claim 13, wherein the circumferentially extending wooden wall exhibits a specific energy absorption of at least 45 J / g under compression along a direction substantially parallel to the central axis.

16. Applying an axial load to a wooden wall extending in the circumferential direction, Applying the aforementioned axial load causes one or both axial ends of the circumferentially extending wooden wall to exhibit a petal-shaped failure mode. A method for using a circumferentially extending wooden wall according to claim 13, further comprising:

17. A method for using a circumferentially extending wooden wall according to claim 13, further comprising using the circumferentially extending wooden wall as a fluid transport tube or pipe.

18. A method for using a circumferentially extending wooden wall according to claim 13, further comprising using the circumferentially extending wooden wall as an insulating structural material.

19. A plurality of circumferentially extending wooden walls as described in Claim 13, A pair of support members, Includes, An energy absorption system in which multiple circumferentially extending wooden walls are sandwiched between a pair of support members.

20. The energy absorption system according to claim 19, wherein the central axis of each of the circumferentially extending wooden walls is substantially perpendicular to each of the opposing surface portions of the support member.

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