WO2024044160A1 - Matériaux structuraux fabriqués à résistance améliorée, et leurs procédés de fabrication et d'utilisation - Google Patents

Matériaux structuraux fabriqués à résistance améliorée, et leurs procédés de fabrication et d'utilisation Download PDF

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Publication number
WO2024044160A1
WO2024044160A1 PCT/US2023/030783 US2023030783W WO2024044160A1 WO 2024044160 A1 WO2024044160 A1 WO 2024044160A1 US 2023030783 W US2023030783 W US 2023030783W WO 2024044160 A1 WO2024044160 A1 WO 2024044160A1
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WIPO (PCT)
Prior art keywords
plant material
layers
densified
lignin
engineered
Prior art date
Application number
PCT/US2023/030783
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English (en)
Inventor
Liangbing Hu
Yu Liu
Jiaqi DAI
Allan Bradshaw
Original Assignee
University Of Maryland, College Park
Inventwood Inc.
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Application filed by University Of Maryland, College Park, Inventwood Inc. filed Critical University Of Maryland, College Park
Publication of WO2024044160A1 publication Critical patent/WO2024044160A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
    • E04C3/122—Laminated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27D—WORKING VENEER OR PLYWOOD
    • B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
    • B27D1/04—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring to produce plywood or articles made therefrom; Plywood sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27M—WORKING OF WOOD NOT PROVIDED FOR IN SUBCLASSES B27B - B27L; MANUFACTURE OF SPECIFIC WOODEN ARTICLES
    • B27M3/00—Manufacture or reconditioning of specific semi-finished or finished articles
    • B27M3/0013—Manufacture or reconditioning of specific semi-finished or finished articles of composite or compound articles
    • B27M3/006—Manufacture or reconditioning of specific semi-finished or finished articles of composite or compound articles characterised by oblong elements connected both laterally and at their ends
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
    • B32B21/04—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B21/042—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood as the main or only constituent of a layer, which is next to another layer of the same or of a different material of wood
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
    • B32B21/13—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board all layers being exclusively wood
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B21/00—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board
    • B32B21/14—Layered products comprising a layer of wood, e.g. wood board, veneer, wood particle board comprising wood board or veneer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/022—Mechanical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/03—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers with respect to the orientation of features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/02—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising animal or vegetable substances, e.g. cork, bamboo, starch
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B9/042—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of wood
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
    • E04C3/14—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with substantially solid, i.e. unapertured, web
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
    • E04C3/00—Structural elongated elements designed for load-supporting
    • E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
    • E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
    • E04C3/16—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with apertured web, e.g. trusses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/72—Density

Definitions

  • the present disclosure relates generally to engineered structural materials, and more particularly, to strength-enhanced structures employing plant materials (e.g., wood, bamboo, etc.), such as, but not limited to, cross-laminated timber (CLT), glued laminated timber (glulam), laminated veneer lumber (LVL), oriented strand board (OSB), and/or oriented structural straw board (OSSB).
  • plant materials e.g., wood, bamboo, etc.
  • CLT cross-laminated timber
  • glulam glued laminated timber
  • LDL laminated veneer lumber
  • OSB oriented strand board
  • OSSB oriented structural straw board
  • CLT Cross -laminated timber
  • Embodiments of the disclosed subject matter may address one or more of the abovenoted problems and disadvantages, among other things.
  • the engineered structural material comprises multiple plant material layers (e.g., comprising one or more plant material pieces) glued, adhered, joined, or otherwise coupled together to form a laminate.
  • At least one of the plant material layers within the laminate can be a densified plant material layer (e.g., comprising one or more densified plant material pieces), for example, compressed to collapse lumina of its native cellulose-based micro structure so as to have an increased density of at least 1.15 g/cm 3 .
  • the densified plant material layer can be formed from lignin- compromised material, for example, in situ lignin-modified plant material or partially delignified plant material.
  • the densified plant material layer can reinforce the overall structure, thereby allowing the other plant material layers to have a lower strength, allowing the laminate to be used in a more demanding application, and/or allowing the laminate to have a smaller cross-section.
  • an engineered structure can comprise a first laminate.
  • the first laminate can comprise a plurality of constituent plant material layers.
  • the plurality of constituent plant material layers can comprise one or more first layers and one or more second layers.
  • Each plant material layer can be adhered to an adjacent plant material layer via one or more respective glues.
  • Each first plant material layer can be a densified plant material layer having a density greater than or equal to 1.15 g/cm 3 and a mechanical strength greater than or equal to a first value.
  • Each second plant material layer can be a plant material layer having a density less than 1.15 g/cm 3 and a mechanical strength less than the first value.
  • an engineered structural material can comprise one or more laminate structures.
  • Each laminate structure can have a plurality of constituent plant material layers.
  • Each plant material layer can be coupled to an adjacent plant material layer via one or more respective glues.
  • At least one of the plurality of constituent plant material layers can be a densified plant material layer having a density greater than or equal to 1.15 g/cm 3 .
  • a method can comprise providing one or more first layers. Each first layer can comprise a densified plant material having a density greater than or equal to 1.15 g/cm 3 and a mechanical strength greater than or equal to a first value. The method can further comprise providing one or more second layers. Each second layer can comprise a plant material having a density less than 1.15 g/cm 3 and a mechanical strength less than the first value. The method can also comprise coupling the one or more first layers to the one or more second layers via one or more respective glues so as to form a laminate.
  • FIGS. 1A-1G are simplified schematic diagrams of various strength-enhanced engineered structures formed from one or more plant materials, according to one or more embodiments of the disclosed subject matter.
  • FIGS. 2A-2B are partial isometric views of strength-enhanced cross -laminated timber (CLT) structures, according to one or more embodiments of the disclosed subject matter.
  • FIGS. 3A-3D are partial isometric views of various strength-enhanced glued laminated timber (glulam) structures, according to one or more embodiments of the disclosed subject matter.
  • FIGS. 4A-4D are partial isometric views of various strength-enhanced laminated veneer lumber (LVL) structures, according to one or more embodiments of the disclosed subject matter.
  • LTL laminated veneer lumber
  • FIGS. 5A-5E show various strength-enhanced I-joist structures, according to one or more embodiments of the disclosed subject matter.
  • FIG. 6 is a simplified process-flow diagram for fabricating a strength-enhanced engineered structure from one or more plant materials, according to one or more embodiments of the disclosed subject matter.
  • Plant Material A portion (e.g., a cut piece or portion, via mechanical means or otherwise) of any photosynthetic eukaryote of the kingdom Plantae in its native state as grown.
  • the plant material comprises wood (e.g., hardwood or softwood), bamboo (e.g., any of Bambusoideae, such as but not limited to Moso, Phyllostachys vivax, Phyllostachys viridis, Phyllostachys bambusoides, and Phyllostachys nigra), reed (e.g., any of common reed Phragmites australis), giant reed (Arundo donax), Burma reed (Neyraudia reynaudiana), reed canary-grass (Phalaris arundinacea), reed sweet-grass (Glyceria maxima), small-reed (Calamagrostis species
  • the natural wood can be any type of hardwood (e.g., having a native lignin content in a range of 18-25 wt%) or softwood (e.g., having a native lignin content in a range of 25-35 wt%), such as, but not limited to, basswood, oak, poplar, ash, alder, aspen, balsa wood, beech, birch, cherry, butternut, chestnut, cocobolo, elm, hickory, maple, oak.
  • the plant material can be any type of fibrous plant composed of lignin, hemicellulose, and cellulose.
  • the plant material can be bagasse (e.g., formed from processed remains of sugarcane or sorghum stalks) or straw (e.g., formed from processed remains of cereal plants, such as rice, wheat, millet, or maize).
  • Engineered Structure or Engineered Structural Material' A structure formed from a plurality of pieces or layers of natural or modified plant materials coupled together using glue or other adhesive to form a structure with improved strength and/or durability.
  • Examples of such structures/materials include, but are not limited to, cross -laminated timber (CLT), glued laminated timber (glulam), laminated veneer lumber (LVL), oriented strand board (OSB), and/or oriented structural straw board (OSSB).
  • Lignin-compromised plant material Plant material that has been modified by one or more chemical treatments to (a) in situ modify the native lignin therein, (b) partially remove the native lignin therein (i.e., partial delignification), or (c) fully remove the native lignin therein (i.e., full delignification).
  • the lignin-compromised plant material can substantially retain the native micro structure of the natural plant material formed by cellulose- based cell walls.
  • Partial Delignification The removal of some (e.g., at least 1%) but not all (e.g., less than or equal 90%) of native lignin (e.g., on a weight percent basis) from the naturally-occurring plant material.
  • the partial delignification can be performed by subjecting the natural plant material to one or more chemical treatments.
  • the lignin content after partial delignification can be in a range of 0.9-23.8 wt% for hardwood or in a range of 1.25-33.25 wt% for softwood.
  • Lignin content within the plant material before and after the partial delignification can be assessed using known techniques in the art, for example, Laboratory Analytical Procedure (LAP) TP-510-42618 for “Determination of Structural Carbohydrates and Lignin in Biomass,” Version 08-03-2012, published by 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, both of which are incorporated herein by reference.
  • LAP Laboratory Analytical Procedure
  • TP-510-42618 for “Determination of Structural Carbohydrates and Lignin in Biomass”
  • NREL National Renewable Energy Laboratory
  • ASTM E1758-01(2020) Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography
  • Full Delignification- The removal of substantially all (e.g., 90-100%) of native lignin from the naturally-occurring plant material.
  • the full delignification can be performed by subjecting the natural plant material to one or more chemical treatments. Lignin content within the plant material before and after the full delignification can be assessed using the same or similar techniques as those noted above for partial delignification.
  • the full delignification process can be, for example, as described in U.S. Publication No. 20200238565, published July 30, 2020 and entitled “Delignified Wood Materials, and Methods for Fabricating and Use Thereof,” which delignification processes are incorporated herein by reference.
  • Lignin modification- In situ altering one or more properties of native lignin in the naturally-occurring plant material, without removing the altered lignin from the plant material.
  • the lignin content of the plant material prior to and after the in situ modification can be substantially the same, for example, such that the in situ modified plant material retains at least 95% (e.g., removing no more than 1%, or no more than 0.5%, of the native lignin content) of the native lignin content.
  • the plant material can be in situ modified (e.g., by chemical reaction with OH ) to depolymerize lignin, with the depolymerized lignin being retained within the plant material micro structure.
  • LAP Laboratory Analytical Procedure
  • TP-510-42618 for “Determination of Structural Carbohydrates and Lignin in Biomass,” Version 08-03-2012, published by National Renewable Energy Laboratory (NREL), ASTM E1758-01(2020) for “Standard Test Method for Determination of Carbohydrates in Biomass by High Performance Liquid Chromatography,” published by ASTM International, and/or Technical Association of Pulp and Paper Industry (TAPPI), Standard T 222-om-83, “Standard Test Method for Acid- Insoluble Lignin in Wood,” all of which are incorporated herein by reference.
  • LAP Laboratory Analytical Procedure
  • the lignin modification process can be, for example, as described in International Publication No. WO 2023/028356, published March 2, 2023, and entitled “Waste-free Processing for Lignin Modification of Fibrous Plant Materials, and Lignin-modified Fibrous Plant Materials,” which lignin modification processes are incorporated herein by reference.
  • the densified plant material e.g., wood
  • the densified plant material can have a density greater than that of the native plant material, for example, at least 1.15 g/cm 3 , such as at least 1.2 g/cm 3 or even at least 1.3 g/cm 3 (e.g., 1.4- 1.5 g/cm 3 ).
  • the densified plant material can be formed as described in, but not limited to, U.S. Patent No. 11,130,256, issued September 28, 2021, entitled “Strong and Tough Structural Wood Materials, and Methods for Fabricating and Use Thereof,” and International Publication No. WO 2021/108576, published June 3, 2021, entitled “Bamboo Structures, and Methods for Fabrication and Use Thereof,” each of which is incorporated herein by reference.
  • Non-densified Plant Material or N on-densified Wood' A plant material (e.g., wood) that substantially retains its native density.
  • the non-densified plant material e.g., wood
  • the non-densified plant material can have a density of, for example, less than 1.15 g/cm 3 , such as less than or equal to 1.0 g/cm 3 or even less than or equal to 0.9 g/cm 3 (e.g., 0.1-0.9 g/cm 3 ).
  • the lumina of the cellulose-based microstructure of the non-densified plant material can remain substantially open, at least prior to inclusion within the engineered structure.
  • Longitudinal growth direction' A direction along which a plant grows from its roots or from a trunk thereof, with cellulose fibers forming cell walls of the plant being generally aligned with the longitudinal growth direction.
  • the longitudinal growth direction may be generally vertical or correspond to a direction of its water transpiration stream. This is in contrast to the radial direction, which extends from a center portion of the plant outward and may be generally horizontal.
  • the engineered structural materials can have enhanced mechanical strength, for example, as compared to existing engineered structural materials (e.g., formed with native or non-densified wood alone).
  • the engineered structural material can be made with a smaller cross-section (e.g., as compared to existing engineered structural materials) for a particular application (e.g., requiring a particular strength rating).
  • the engineered structural material with a same cross-section can be used in a more demanding application (e.g., as compared to existing engineered structural materials), for example, by spanning a longer distance.
  • the size and/or strength of the engineered structural material can be custom designed to a particular application by including an appropriate number and/or arrangement of densified plant material layers in the engineered structural material.
  • the engineered structural materials comprises a laminate structure having a plurality of constituent plant material layers joined, adhered, or otherwise coupled to each other via a glue, with at least one of the layers being a densified plant material layer, for example, having a density of at least 1.15 g/cm 3 (e.g., > 1.2 g/cm 3 or > 1.3 g/cm 3 , for example, in a range of 1.4- 1.5 g/cm 3 ).
  • one, some, or all of other layers of the laminate structure can be non-densified plant material layers, for example, having a density less than 1.15 g/cm 3 (e.g., ⁇ 1.0 g/cm 3 or ⁇ 0.9 g/cm 3 , for example, in a range of 0.1-0.9 g/cm 3 ).
  • the non-densified plant material layers can be formed of the native plant material (e.g., without compression).
  • one, some or all of the other layers of the laminate structure can be plant material layers that have been densified (e.g., prior to inclusion in the laminate or after inclusion in the laminate), but to a lesser degree than the densified plant material layers, for example, such that the densified density remains less than 1.15 g/cm 3 .
  • references to non-densified plant material layers are intended to include such lesser-densified plant material layers.
  • the densified plant material layers can have a mechanical strength greater than that of the other plant material layers (e.g. non-densified or lesser-densified).
  • each densified plant material layer can have a strength of at least 100 MPa (e.g., 100-600 MPa), while each non-densified plant material layer can have a strength less than 100 MPa (e.g., 15-65 MPa).
  • the laminate structure can have any number of plant material layers.
  • FIG. 1A illustrates a laminate structure 100 having a pair of plant material layers, in particular, a densified plant material layer 102 coupled to a non-densified plant material layer 106 via an intervening glue layer 104.
  • the glue layer 104 can comprise any type of adhesive, such as but not limited to epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, and/or sodium carboxymethyl cellulose (CMC).
  • one, some, or all of the plant material layers constituting the laminate structure can be formed of multiple plant material pieces.
  • densified plant material layers can be disposed at a location within the laminate structure that would be subject to stresses that exceed a predetermined threshold and/or a maximum stress.
  • densified plant material layers can be used as outermost layers of the laminate structure in a cross-sectional view, for example, as shown in FIG. IB.
  • laminate structure 110 has three plant material layers - a pair of densified plant material layers 102a, 102b coupled to opposite sides of a centrally-disposed non-densified plant material layer 106 via respective intervening glue layers 104a, 104b.
  • the densified plant material layer can be disposed at any location within the laminate structure.
  • densified plant material layers can be used as interior or central layers of the laminate structure in a cross-sectional view.
  • laminate structure 120 has three plant material layers - a pair of non-densified plant material layers 106a, 106b coupled to a centrally-disposed densified plant material layer 102 via respective intervening glue layers 104a, 104b.
  • FIGS. 1A-1C illustrate a single densified plant material layer or a single non- densified plant material layer
  • embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, multiple densified plant material layers and multiple non-densified plant material layers can be provided together in a single laminate structure.
  • FIG. ID illustrates a laminate structure 130 having more than three plant material layers.
  • the laminate structure 130 has a stack 132 of three non- densified plant material layers 106a- 106c coupled together via intervening glue layers 108a, 108b (which may be the same formulation or a different formulation than glue layers 104a, 104b).
  • the laminate structure 130 has a pair of densified plant material layers 102a, 102b coupled to the centrally-disposed stack 132 via respective intervening glue layers 104a, 104b.
  • the stack 132 can be a conventional engineered structure (e.g., CLT, glulam, LVL, OSB, etc.), and the pair of densified plant material layers 102a, 102b can serve to enhance or reinforce the strength of the stack 132.
  • lateral side surfaces of the non-densified plant material layers can be exposed.
  • densified plant material layers can also be provided over one, some, or all of these exposed surfaces, for example, to contain, bound, or otherwise enclose the non-densified plant material layers within a surrounding structure formed by the densified plant material layers.
  • the provision of densified plant material layers to enclose the non-densified plant material layers can form a post or beam that has improved aesthetics (e.g., more desirable appearance due to the densified layer as compared to the non-densified layers), improved durability (e.g., due to greater fire resistance and/or weatherability of the densified layer as compared to the non-densified layers), and/or installation flexibility (e.g., to provide enhanced strength regardless of orientation).
  • aesthetics e.g., more desirable appearance due to the densified layer as compared to the non-densified layers
  • improved durability e.g., due to greater fire resistance and/or weatherability of the densified layer as compared to the non-densified layers
  • installation flexibility e.g., to provide enhanced strength regardless of orientation.
  • IE illustrates a laminate structure 140 where the stack 132 of non-densified plant material layers 106a is capped on left and right sides thereof by densified plant material layers 102c, 102d and corresponding glue layers 142a, 142b, respectively (which may have a same or different formulation and/or thickness as glue layers 108a, 108b and/or glue layers 104a, 104b).
  • the top and bottom sides of the stack 132 of the laminate structure 140 are capped by densified plant material layers 102a, 102b, thereby enclosing the stack 132 within a circumferentially- surrounding wall formed by the densified plant material layers 102a- 102d.
  • FIGS. ID- IE illustrates non-densified plant material layers arranged in the stack along the thickness direction of the laminate structure
  • the non-densified plant material layers can be stacked with respect to a width and/or length direction of the laminate structure.
  • FIGS. IF illustrates a laminate structure 150 having a lateral stack 152 of three non-densified plant material layers 106a- 106c arranged along the width direction and coupled together via intervening layers 108a, 108b (which may the same or different formulation and/or thickness as glue layers 104a, 104b).
  • FIG. IF illustrates a laminate structure 150 having a lateral stack 152 of three non-densified plant material layers 106a- 106c arranged along the width direction and coupled together via intervening layers 108a, 108b (which may the same or different formulation and/or thickness as glue layers 104a, 104b).
  • FIG. 1G illustrates a laminate structure 160 having a lateral stack of three non- densified plant material layers 162a- 162c arranged along the width direction and coupled together via intervening glue layers 164a, 164b (which may be the same or different formulation and/or thickness as glue layers 104a, 104b). As shown in FIG. 1G, a height of each non- densified plant material layer 162a- 162c can be less than a width thereof. Other sizes and/or numbers of layers for the lateral stack are also possible according to one or more contemplated embodiments.
  • the laminate structures 150 and 160 have a pair of densified plant material layers 102a, 102b coupled to the centrally-disposed lateral stack via respective intervening glue layers 104a, 104b.
  • the lateral stack can be a conventional engineered structure (e.g., CLT, glulam, LVL, OSB, etc.), and the pair of densified plant material layers 102a, 102b can serve to enhance or reinforce the strength of the lateral stack.
  • FIGS. 1A-1G illustrate a laminate structure with at least one non-densified plant material layer
  • each of the layers of the laminate structure can be a densified plant material layer (e.g., with each having a density greater than or equal to 1.15 g/cm 3 ).
  • the separate densified plant material layers can be coupled to each other via intervening glue layers (e.g. similar to glue layer 104) or otherwise (e.g., without any glue and/or by relying on hydrogen bonding between facing surfaces of the densified plant material layers).
  • FIGS. 1A-1G illustrate one or two densified plant material layers
  • densified plant material layers can constitute 5- 50% of the laminate structure (e.g., based on number of layers and/or by thickness and/or by weight), while the remaining 50-95% can constitute non-densified plant material layers.
  • the densified plant material layers can constitute a majority (e.g., > 50%) of the laminate structure, with the remainder formed of non-densified plant material layers.
  • 1A-1G illustrate the densified plant material layers at specific locations (e.g., top, bottom, or middle) of the laminate structure, embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, the densified plant material layers can be at any location within the laminate structure, for example, replacing any of the non-densified wood layers illustrated in FIGS. 1A-1G.
  • FIGS. 1A-1G illustrate a single piece of plant material in each layer
  • embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, multiple plant material pieces can be coupled together (e.g., via mechanical joining techniques, such as finger joints, and/or adhesive) at adjacent edges to form a respective layer, for example, to extend a width and/or length of the layer.
  • the plant material for each layer of the laminate structure can be from the same plant, or at least the same species.
  • the plant material for at least one of the layers in the laminate structure can be from a different species than that of at least one other layer.
  • each of the densified plant material layers can be formed from a same species, and/or each of the non-densified plant material layers can be formed from a same species (which may be the same as or different from the densified plant material layers).
  • the plant material layers can be arranged within the laminate structure such that their orientations (e.g., based on their respective longitudinal growth directions) are substantially aligned or parallel.
  • at least one of the plant material layers can be arranged within the laminate structure such that its orientation is substantially orthogonal to, or at least crossing, an orientation of at least another of the plant material layers.
  • each of the densified plant material layers can have substantially aligned orientations.
  • each of the non-densified plant material layers can have orientations (which may be the same as or different from that of the densified plant material layers) that are substantially aligned, crossing, or substantially orthogonal.
  • one, some, or all of the plant material layers may have random orientations (e.g., without consideration of orientations of the other plant material layers).
  • FIG. 2A illustrates a strength-enhanced cross-laminated timber (CLT) structure 200 having a laminate structure, with a stack 202 in between outer layers of densified wood panels 204a, 204b (e.g., having a thickness, tl or t2, of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm), such as 3/8-inch (9.35 mm)).
  • the stack 202 can be a conventional CLT structure, for example, having three layers (or five, or seven) of lumber boards.
  • each lumber board of the stack 202 can have a thickness of 5/8-inch to 2-inches (15.88 mm to 50.8 mm) and/or a width of 2.4-inches to 9.5-inches (60.96 mm to 241.3 mm).
  • the strength-enhanced CLT structure 200 can have a length, L, of at least 6-feet (1.83 m), for example, about 8-feet (2.43 m).
  • the strength-enhanced CLT structure 200 can have a width, W, of at least 1-foot (0.30 m), for example, about 2-feet (0.61 m).
  • the strength-enhanced CLT structure 200 can have a height, H, of at least 6-inches (15.2 cm), for example, about 8-inches (20.3 cm).
  • the lumber boards in each layer can be connected together via joining, for example, finger joints and/or structural adhesive.
  • the stack 202 can be formed by stacking the lumber boards crosswise at 90-degree angles and glued in place.
  • the outermost lumber boards 208a, 208b can have orientations 210a, 210b that are substantially aligned with each other
  • the central lumber board 212 can have an orientation 214 orthogonal to orientations 210a, 210b.
  • densified wood panels 204a, 204b can have orientations 206a, 206b that are substantially aligned with each other as well as with orientation 214 of central lumber board 212.
  • the orientation 206a, 206b of one or both densified wood panels 204a, 204b can be substantially aligned with the orientations 210a, 210b of the outer lumber boards 208a, 208b, or with none of the orientations 210a, 210b, 214 of stack 202.
  • additional densified wood can be provided as side layers 204c, 204d (e.g., with orientations 206d that are substantially aligned with each other as well as with orientation 214 of central lumber board 212) so as to enclose stack 202 (e.g., along a circumferential direction), for example, as shown for CLT structure 220 in FIG. 2B.
  • the densified wood as the top and bottom tension layers, the flatwise bending stiffness of the stack 202 can be improved (e.g., doubled), and/or the spanning capacity of the stack 202 can be increased.
  • Strength-enhanced CLTs such as CLT structure 200 and/or CLT structure 220, can be used in a broad range of applications, such as but not limited to flooring, walls, and roofing, for example, to replace steel-reinforced concrete in residential and commercial buildings.
  • FIG. 3A illustrates a strength-enhanced glued laminated timber (glulam) structure 300 having a laminate structure, with a lateral array 302 of wood layers 308 in between outer layers of densified wood panels 304a, 304b (e.g., having a thickness of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm)).
  • the array 302 can be a conventional glulam structure.
  • each wood panel of the array 302 in a cross-sectional plane perpendicular to the respective longitudinal growth direction, each wood panel of the array 302 can have a thickness of 1-inch to 6-inches (2.5 cm to 15.2 cm) and/or a width of 2-inches to 12-inches (5.1 cm to 30.5 cm).
  • wood segments in each layer can be connected together via joining, for example, finger joints and/or structural adhesive.
  • the array 302 can be formed by arranging individual wood layers 308 (and/or constituent segments thereof) with substantially aligned orientations 310 (e.g., substantially parallel wood fibers) and gluing together.
  • additional densified wood can be provided as side layers 304c, 304d to enclose stack 302 (e.g., along a circumferential direction), for example, as shown for glulam structure 350 in FIG. 3D.
  • densified wood panels 304a-304d can have orientations 306a-306d that are substantially aligned with each other as well as with orientation 310 of the wood layers 308.
  • the orientations 306a-306d of one, some, or all of densified wood panels 304a-304d can be substantially orthogonal to, or at least crossing with, orientation 310 of the wood layers 308.
  • FIG. 3B illustrates another strength-enhanced glulam structure 320 that employs a vertical array 322 of wood layers 328 in between outer layers of densified wood panels 324a, 324b (e.g., having a thickness of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm)).
  • the array 322 can be a conventional glulam structure, for example, with each wood panel of the array 322 having a thickness of 1-inch to 6-inches (2.5 cm to 15.2 cm) and/or a width of 2-inches to 12-inches (5.1 cm to 30.5 cm). Other dimensions are also possible, according to one or more contemplated embodiments.
  • wood segments in each layer can be connected together via joining, for example, finger joints and/or structural adhesive.
  • the array 322 can be formed by arranging individual wood layers 328 (and/or constituent segments thereof) with substantially aligned orientations 330 (e.g., substantially parallel wood fibers) and gluing together.
  • densified wood panels 324a, 324b can have orientations 326a, 326b that are substantially aligned with each other as well as with orientation 330 of the wood layers 328.
  • the orientations 326a, 326b of one or both densified wood panels 324a, 324b can be substantially orthogonal to, or at least crossing with, orientation 330 of the wood layers 328.
  • FIG. 3C illustrates another strength-enhanced glulam structure 340 that employs a vertical array 322 of wood layers 328 in between outer layers 324a, 324b of densified wood segments.
  • the top layer 324a can be formed by a plurality of densified wood segments 342a- 342c
  • the bottom layer 324b can be formed by a plurality of densified wood segments 344a- 344c.
  • each wood layer 328 of the vertical array 322 can be formed by a plurality of wood segments 346a-346d (which can be offset from each other along the length direction, L, and/or the width direction, W).
  • wood segments in each layer 324a, 324b, 328 can be connected together via joining, for example, finger joints and/or structural adhesive.
  • the use of multiple wood segments in each layer can allow the glulam structure 340 to be formed of any length without restriction.
  • each top densified wood segment 342a-342c can be substantially aligned (e.g., along the length direction, L, and/or width direction, W) with a corresponding one of the bottom densified wood segments 344a-344c.
  • the top and bottom densified wood segments can be offset from each other (e.g., in a manner similar to wood segments 346a-346d constituting the wood layers 328 of array 322), for example, to further enhance mechanical stiffness.
  • FIG. 4A illustrates a strength-enhanced laminated veneer lumber (LVL) structure 400 having a laminate structure, with a stack 402 of wood veneers 408 in between outer layers of densified wood panels 404a, 404b (e.g., having a thickness of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm)).
  • one or more densified wood panels can be provided as part of stack 402, for example, in place of, or in addition to, one or more of densified wood panels 404a, 404b.
  • the stack 402 can be a conventional LVL structure.
  • each wood veneer 408 of the stack 402 can have a thickness of 2.5-4.8 mm.
  • Other dimensions are also possible according to one or more contemplated embodiments.
  • the LVL stack 402 can be fabricated, for example, by gluing together (e.g., while pressing) veneers from rotary peeling (e.g., using a peeling lathe).
  • the veneers can be assembled along their longitudinal directions (e.g., with orientations 410 substantially aligned).
  • densified wood panels 404a, 404b can have orientations 406a, 406b that are substantially aligned with each other as well as with orientation 410 of wood veneers 408.
  • the orientations 406a, 406b of one or both densified wood panels 404a, 404b can be substantially orthogonal to, or at least crossing with, orientation 410 of the wood veneers 408.
  • a load 412 can be applied substantially parallel to a width direction of the strength-enhanced LVL structure 400 and/or substantially perpendicular to a direction in which veneers 408 are stacked (e.g., a height direction of stack 402).
  • FIG. 4B illustrates another strength-enhanced LVL structure 420 that employs a stack 422 of wood veneers 408 in between outer layers 404a, 404b of densified wood segments.
  • the top layer 404a can be formed by a plurality of densified wood segments 424a-424c
  • the bottom layer 404b can be formed by a plurality of densified wood segments 444a-444c.
  • wood segments in each layer 404a, 404b can be connected together via joining, for example, finger joints and/or structural adhesive.
  • each top densified wood segment 424a-424c can be substantially aligned (e.g., along the length direction, L, and/or width direction, W) with a corresponding one of the bottom densified wood segments 444a-444c.
  • the top and bottom densified wood segments can be offset from each other, for example, to further enhance mechanical stiffness.
  • FIG. 4C illustrates another strength-enhanced LVL structure 430 having a laminate structure, with a stack 432 of wood veneers 408 in between outer layers of densified wood panels 404a, 404b (e.g., having a thickness of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm)).
  • the densified wood panels 404a, 404b are provided on opposite sides of stack 432 along a direction substantially perpendicular to a direction in which the wood veneers 408 are stacked. Similar to the structure 400 of FIG.
  • the stack 432 can be a conventional LVL structure, for example, with each wood veneer 408 of the stack 432 having a thickness of 2.5-4.8 mm in a cross-sectional plane perpendicular to longitudinal growth direction 410; however, other dimensions are also possible according to one or more contemplated embodiments.
  • the LVL stack 432 can be fabricated, for example, by gluing together (e.g., while pressing) veneers from rotary peeling. The veneers can be assembled along their longitudinal directions (e.g., with orientations 410 substantially aligned).
  • densified wood panels 404a-404d can have orientations 406a-406d that are substantially aligned with each other and parallel to orientation 410 of wood veneers 408.
  • the orientations 406a-406d of one or both densified wood panels 404a-404d can be substantially orthogonal to, or at least crossing with, orientation 410 of the wood veneers 408.
  • a load 434 can be applied substantially parallel to a width direction of the strength-enhanced LVL structure 430 or 450 and/or substantially perpendicular to a direction in which veneers 408 are stacked (e.g., a height direction of stack 432).
  • the load 434 can be applied substantially perpendicular to exposed surfaces of densified wood panels 404a, 404b.
  • the LVL structure 400, LVL structure 420, LVL structure 430, and/or LVL structure 440 can be employed as part of another engineered structure, for example, in place of one or both outermost layers 304a, 304b of glulam structure 300 in FIG. 3A, in place of one or both outermost layers 324a, 324b of glulam structure 320 in FIG. 3B, in place of one or both outermost layers 324a, 324b of glulam structure 340 in FIG. 3C, in place of one, some, or all of outermost layers 304a-304d of glulam structure 350 in FIG. 3D.
  • the LVL structure 400, LVL structure 420, LVL structure 430, and/or LVL structure 440 can be employed as part of the flange of an I-joist.
  • FIG. 5A shows a cross-section of an I-joist 500 that employs strength-enhanced LVL for flanges 502a, 502b.
  • top flange 502a has an LVL stack 504a arranged between a pair of densified wood layers 506a, 508a
  • bottom flange 502b has an LVL stack 504b arranged between a pair of densified wood layers 506b, 508b.
  • a web 512 can be inserted into respective grooves 510a, 510b in the flanges 502a, 502b and glued thereto (which glue may be the same formulation or a different formulation than that constituting the glue layers of the flange).
  • the web can be formed of plywood, LVL, oriented strand board (OSB), or other engineered wood structure.
  • the I-joist 500 can be end-trimmed and heat- cured, or left at room temperature, to reach approximately equilibrium moisture content.
  • FIG. 5B illustrates another I-joist 520 that employs LVL for the flanges. Similar to FIG.
  • the web 512 is coupled into respective grooves 510a, 510b and extends between the top and bottom flanges 502a, 502b.
  • the flanges only employ densified wood as outermost layers of the flanges.
  • top flange 522a has an LVL stack 524a and a densified wood layer 506a at an end of the LVL stack 524a opposite the web 512
  • bottom flange 522b has an LVL stack 524b and a densified wood layer 506b at an end of the LVL stack 524b opposite the web 512.
  • the flange of the I-joist can be formed of strength-enhanced solid wood instead of LVL.
  • FIG. 5C illustrates another I-joist 540 that employs strength-enhanced solid wood for flanges 542a, 542b (e.g., having a thickness of 3/16-inch to 1/4-inch (4.76 mm to 6.35 mm)).
  • top flange 542a has a solid wood panel 544a and a densified wood layer 546a glued to an end of the wood panel 544a opposite the web 552
  • bottom flange 542b has a solid wood panel 544b and a densified wood layer 546b glued to an end of the wood panel 544b.
  • the web 552 can be inserted into respective grooves 550a, 550b in the solid wood panels 544a, 544b and glued thereto (which glue may be the same formulation or a different formulation than that constituting the glue layers of the flange).
  • the web 552 can be formed of plywood, LVL, oriented strand board (OSB), or other engineered wood structure.
  • OSB oriented strand board
  • FIG. 5C shows strength enhancement via a single layer of densified wood for each flange of the I-joist
  • embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, multiple densified wood layers can be combined with the solid wood in each flange.
  • FIG. 5D shows a cross-section of another I-joist 560. Similar to the I-joist of FIG. 5A, the web 512 is coupled into respective grooves 510a, 510b and extends between the top and bottom flanges 562a, 562b. However, in contrast to FIG.
  • the top flange 562a has a solid wood panel 564a arranged between and glued to a pair of densified wood layers 506a, 508a
  • bottom flange 562b has a solid wood plane 564b arranged between and glued to a pair of densified wood layers 506b, 508b.
  • densified wood is limited to the flanges of the I-joist in FIGS. 5A- 5D, embodiments of the disclosed subject matter are not limited thereto. Rather, in some embodiments, densified wood can be used as part of the web, for example, to allow an open structure for the web.
  • FIG. 5E shows a side view of another I-joist 580 with a mesh 584 extending between the top and bottom flanges 582a, 582b.
  • densified wood can be used to form the mesh 584, or as part of an engineered wood structure used to form the mesh 584.
  • the mesh 584 can take the form of a truss or other open structure that is otherwise capable of supporting loads experienced by the I-joist 580.
  • FIGS. 2A-5E focuses on the use of wood, embodiments of the disclosed subject matter are not limited thereto. Rather, any or all of the above-described wood components can be replaced with other plant materials, according to one or more contemplated embodiments.
  • FIG. 6 illustrates aspects of a method 600 for fabricating an engineered structure from one or more plant material pieces.
  • the method 600 can initiate at process block 602, where one or more pieces of natural plant material can be provided.
  • the provision of process block 602 can include cutting, removing, or otherwise separating the piece from a parent plant (e.g., tree, bamboo stalk, etc.).
  • the cutting can form the natural plant material into a substantially flat planar structure, with a direction of cellulose fibers extending parallel to a plane of the structure (e.g., longitudinal cut or rotary cut) or extending perpendicular to a plane of the structure (e.g., radial cut).
  • the preparing can include pre-processing of the piece of natural plant material, for example, cleaning to remove any undesirable material or contamination in preparation for subsequent processing, forming the natural plant material into a particular shape in preparation for subsequent processing (e.g., slicing into strips), or any combination of the foregoing.
  • the cutting can form the plant material piece(s) into any one-dimensional (e.g., an elongated structure, where a thickness and a width are both at least an order of magnitude less than its length), two-dimensional (e.g., a substantially flat planar structure, where a thickness is at least an order of magnitude less than its length and width), or three-dimensional (e.g., a block, where a thickness, width, and length are all within an order of magnitude of each other) structure.
  • the provision of process block 602 can include assembling multiple plant material pieces into a single layer.
  • the assembling of multiple plant material pieces into a single layer can occur after processing, for example, after the optional pre-press modification of process block 617 but before the compression of process block 618, or after the compression of process block 618 but before the coupling of process block 626.
  • the method 600 can proceed to decision block 604, where it is determined if the plant material should be subject to a lignin-compromising treatment. In some embodiments, lignincompromising may not be desired, for example, where a lower degree of densification is desired for the plant material. In such embodiments, the method 600 can proceed directly from decision block 604 to optional process block 617. Alternatively, if in situ lignin modification is desired at decision block 604, the method 600 can proceed to process block 606, wherein the plant material piece(s) can be infiltrated with one or more chemical solutions to modify lignin therein. For example, in some embodiments, the infiltration can be by soaking the plant material piece(s) in a solution containing the one or more chemicals under vacuum.
  • the chemical solution can contain at least one chemical component that has OH’ ions or is otherwise capable of producing OH’ ions in solution.
  • one, some, or all of the chemicals in the solution can be alkaline.
  • the chemical solution includes p-toluenesulfonic acid, NaOH, LiOH, KOH, Na2O, or any combination thereof.
  • Exemplary combinations of chemicals can include, but are not limited to, 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, where AQ is Anthraquinone, any of the foregoing with NaOH replaced by LiOH or KOH, or any combination of the foregoing.
  • the chemical infiltration can be performed without heating, e.g., at room temperature (20-30 °C, such as -22-23 °C).
  • the chemical solution is not agitated in order to avoid disruption to the native cellulose-based microstructure of the plant material piece(s).
  • wood can be immersed in a chemical solution (e.g., 2-5% NaOH) in a container.
  • a chemical solution e.g., 2-5% NaOH
  • the container can then be placed in a vacuum box and subjected to vacuum. In this way, the air in the wood can be drawn out and form a negative pressure.
  • the vacuum pump is turned off, the negative pressure inside the wood can suck the solution into the wood through the natural channels therein (e.g., lumina defined by longitudinal cells).
  • the process can be repeated more than once (e.g., 3 times), such that the channels inside the wood can be filled with the chemical solution (e.g., about 2 hours).
  • the moisture content can increase from -10.2% (e.g., for natural wood) to -70% or greater.
  • the method 600 can proceed to process block 608, where the modification may be activated by subjecting the infiltrated plant material piece(s) to an elevated temperature, for example, greater than 80 °C (e.g., 80-180 °C, such as 120-160 °C), thereby resulting in softened plant material piece(s) (e.g., softened as compared to the natural plant material piece(s)).
  • the heating of process block 608 can be achieved via steam heating, for example, via steam generated in an enclosed reactor, via a steam flow in a flow-through reactor, and/or via steam from a superheated steam generator.
  • the heating of process block 608 can be achieved via dry heating, for example, via conduction and/or radiation of heat energy from one or more heating elements without separate use of steam.
  • the infiltrated plant material piece(s) can be subjected to the elevated temperature for a first time period of, for example, 1-5 hours (e.g., depending on the size of the plant material piece, with thicker pieces requiring longer heating times).
  • any steam generated by heating of the infiltrated plant material piece(s) can be released, for example, by opening a pressure release (e.g., relief valve) of the reactor.
  • the pressure release can be effective to remove -50% of moisture in the modified plant material piece(s).
  • the now softened plant material piece(s) can have a moisture content in a range of 30-50 wt%, inclusive.
  • the method 600 can proceed from process block 608 to process block 610, where the plant material piece(s) can optionally be dried to reduce the moisture content of the plant material piece(s), for example, without removing too much moisture that the plant material piece lose its softened nature (e.g., such that the moisture content is greater than or equal to -8-10 wt%).
  • the optional drying of process block 610 may be effective to reduce a moisture content of the plant material piece(s) from greater than 30 wt% (e.g., 30-50 wt%) to within a range of, for example, 10-20 wt% (e.g., -15 wt%).
  • 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 can be substantially consumed by the modification, and the residual salts can be retained within the microstructure of the softened plant material piece(s).
  • the method 600 can proceed to process block 612, where the plant material piece(s) can be subjected to one or more chemical treatments to remove at least some lignin therefrom, for example, by immersion of the plant material piece(s) (or portion(s) thereof) in a chemical solution associated with the treatment.
  • each chemical treatment or only some chemical treatments can be performed under vacuum, such that the solution(s) associated with the treatment is encouraged to fully penetrate the cell walls and lumina of the plant material piece(s).
  • the chemical treatment(s) can be performed under ambient pressure conditions or elevated pressure conditions (e.g., - 6-8 bar).
  • each chemical treatment or some chemical treatments can be performed at any temperature between ambient (e.g., - 23 °C) and an elevated temperature where the solution associated with the chemical treatment is boiling (e.g., - 70-160 °C).
  • the solution is not agitated in order to minimize the amount of disruption to the native cellulose-based microstructure of the plant material piece(s).
  • the immersion time can be in a range of 0.1 to 96 hours, inclusive, for example, 1-12 hours, inclusive.
  • the amount of time of immersion within the solution may be a function of the amount of lignin to be removed, type of plant material, size of the plant material piece, temperature of the solution, pressure of the treatment, and/or agitation. For example, smaller amounts of lignin removal, smaller plant material piece size (e.g., cross- sectional thickness), higher solution temperature, higher treatment pressure, and agitation may be associated with shorter immersion times, while larger amounts of lignin removal, larger plant material piece size, lower solution temperature, lower treatment pressure, and no agitation may be associated with longer immersion times.
  • each chemical treatment of process block 612 can comprise infusing, infiltrating, or otherwise exposing the plant material piece(s) to one or more first chemical solutions at a first temperature.
  • the first chemical solution can be an alkaline solution, and the first temperature can be less than 100 °C.
  • the first temperature can be in a range of 5-95 °C, inclusive, such as room temperature (e.g., -23 °C).
  • the one or more chemical treatments of process block 612 can include partially or fully immersing the plant material piece(s) in a second chemical solution at a second temperature greater than the first temperature.
  • At least one chemical treatment can comprise infusing, infiltrating, or otherwise exposing the plant material to the second chemical solution at the second temperature.
  • the second chemical solution can be an alkaline solution, and the second temperature can be greater than 100 °C.
  • the second temperature can be in a range of 120-180 °C, such as 160 °C.
  • the temperature of the chemical solution can be increased to 50-180 °C for 0.1-10 h to remove 5-95% lignin and hemicellulose from the plant material piece(s).
  • the second chemical solution may be the same solution as the first chemical solution. In such cases, the first chemical solution can be heated from the first temperature to the second temperature while the plant material piece remains therein.
  • a composition of the second chemical solution can be identical to a composition of the first chemical solution, for example, by providing a fresh batch of solution for use as the second chemical solution (e.g., by removing the plant material piece(s) from the first chemical solution and immersing in the second chemical solution, or by draining the first chemical solution and replacing with fresh second chemical solution).
  • a composition of the second chemical solution can be different from the composition of the first chemical solution.
  • the solution of the chemical treatment(s) can include sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na2SOs), sodium sulfide (Na2S), Na n S (where n is an integer), urea (CH4N2O), sodium bisulfite (NaHSOs), sulfur dioxide (SO2), anthraquinone (AQ) (C14H8O2), methanol (CH3OH), ethanol (C2H5OH), butanol (C4H9OH), formic acid (CH2O2), hydrogen peroxide (H2O2), acetic acid (CH3COOH), butyric acid (C4H8O2), peroxyformic acid (CH2O3), peroxyacetic acid (C2H4O3), ammonia (NH3), tosylic acid (p-TsOH), sodium hypochlorite (NaClO), sodium chlorite (NaCl
  • Exemplary combinations of chemicals for the chemical treatment can 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 2 O + 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 (where n is an integer), Na 2 SO 3 + NaOH + CH3OH + AQ, C2H5OH + NaOH, CH3OH + HCOOH, NH 3 + H2O, and NaC102 + acetic acid.
  • the first and second chemical solutions can be ⁇ 2 wt% NaOH and Na2SO3 (e.g., formed by adding H2SO3 acid to NaOH
  • the chemical treatment can continue (or can be repeated with subsequent solutions) until a desired reduction in lignin content in the plant material piece is achieved.
  • the lignin content can be reduced to between 0.1% (lignin content is 0.1% of original lignin content in the natural plant material) and 99% (lignin content is 99% of original lignin content in the natural plant material).
  • the chemical treatment reduces the hemicellulose content at the same time as the lignin content, for example, to the same or lesser extent as the lignin content reduction.
  • the lignin content after the chemical treatment(s) of process block 612 can be at least 10 wt% (e.g., in a range of 10-15 wt%, inclusive). In some embodiments, when the plant material piece is softwood, the lignin content after the chemical treatment(s) of process block 612 can be at least 12.5 wt% (e.g., 12.5-17.5 wt%, inclusive). In some embodiments, when the plant material piece is bamboo, the lignin content after the chemical treatment(s) of process block 612 can be at least 13 wt% (e.g., 13-18 wt%, inclusive).
  • the method 600 can proceed from process block 612 to process block 614, where rinsing can be performed.
  • the rinsing can be used to remove residual chemicals or particulate(s) resulting from the chemical treatment(s).
  • the delignified plant material piece(s) can be partially or fully immersed in one or more rinsing solutions.
  • the rinsing solution can be a solvent, such as but not limited to, de-ionized (DI) water, alcohol (e.g., ethanol, methanol, isopropanol, etc.), or any combination thereof.
  • the rinsing solution can be formed of equal volumes of water and ethanol.
  • the rinsing can be performed without agitation, for example, to avoid disruption of the microstructure.
  • the rinsing may be repeated multiple times (e.g., at least 3 times) using a fresh mixture rinsing solution for each iteration, or until a substantially neutral pH is measured for the chemically-treated plant material piece(s).
  • the method 600 can proceed to optional process block 616, where the chemically-treated plant material piece(s) can be dried, for example, such that the moisture content therein is less than 15 wt% (e.g., 8-12 wt%).
  • the drying of either process block 610 or process block 616 can include any of conductive, convective, and/or radiative heating processes, 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.
  • an air-drying process can include allowing the processed plant material piece(s) to naturally dry in static or moving air, which air may be at any temperature, such as room temperature (e.g., 23° C) or at an elevated temperature (e.g., greater than 23°C).
  • a vacuum-assisted drying process can include subjecting the processed plant material piece(s) to reduced pressure, e.g., less than 1 bar, for example, in a vacuum chamber or vacuum oven.
  • an oven drying process can include using an oven, hot plate, or other conductive, convective, or radiative heating apparatus to heat the processed plant material piece(s) at an elevated temperature (e.g., greater than 23° C), for example, 70° C or greater.
  • a freeze-drying process can include reducing a temperature of the processed plant material piece(s) to below a freezing point of the fluid therein (e.g., less than 0° C), then reducing a pressure to allow the frozen fluid therein to sublime (e.g., less than a few millibars).
  • a critical point drying process can include immersing the processed plant material piece(s) in a fluid (e.g., liquid carbon dioxide), increasing a temperature and pressure of the plant material piece(s) past a 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.
  • a microwave drying process can include using a microwave oven or other microwave generating apparatus to induce dielectric heating within the processed plant material piece(s) by exposing it to electromagnetic radiation having a frequency in the microwave regime (e.g., 300 MHz to 300 GHz), for example, a frequency of -915 MHz or -2.45 GHz.
  • a frequency in the microwave regime e.g. 300 MHz to 300 GHz
  • the method 600 can proceed to process block 617, where the processed plant material piece(s) can optionally be subjected to one or more internal modifications prior to pressing.
  • the modification may be applied to external features as well as internal features of the processed plant material piece(s), while in other embodiments the modification may be applied to either internal features or external features of the processed plant material piece(s) without otherwise affecting the other feature.
  • the internal modification can include forming, depositing, or otherwise providing non-native particles on surfaces of the processed plant material piece(s). Such surfaces can include at least internal surfaces, e.g., cell walls lining the lumina, but may also include external surfaces of the processed plant material piece(s).
  • the non-native particles incorporated onto the surfaces of the processed plant material piece(s) can imbue the final structure with certain advantageous properties, such as hydrophobicity, weatherability, corrosion resistance (e.g., salt water resistant), and/or flame resistance among other properties.
  • hydrophobic nanoparticles e.g., SiCh nanoparticles
  • SiCh nanoparticles can be formed on surfaces of the processed plant material piece(s).
  • the internal modification can include performing a further chemical treatment that modifies the surface chemistry of the processed plant material piece(s).
  • the further chemical treatment can provide weatherability or corrosion resistance can include at least one of cupramate (CDDC), ammoniacal copper quaternary (ACQ), chromated copper arsenate (CCA), ammoniacal copper 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 iodide (IPBC), and Na2BsOi3-4H2O.
  • CDDC cupramate
  • ACQ ammoniacal copper quaternary
  • CCA chromated copper arsenate
  • ACZA ammoniacal copper zinc arsenate
  • the internal modification of process block 617 can include infiltrating the processed plant material piece(s) with one or more polymers (or polymer precursors).
  • the processed plant material piece(s) can be immersed in a polymer solution under vacuum to form a hybrid material.
  • the polymer can be any type of polymer capable of infiltrating into the pores of the processed plant material piece(s), for example, a synthetic polymer, a natural polymer, a thermosetting polymer, or a thermoplastic polymer.
  • the polymer can be epoxy resin, polyvinyl alcohol (PVA), polyethylene glycol (PEO), polyamide (PA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyacrylonitrile (PAN), polycaprolactam (PA6), poly(m-phenylene isophthalamide) (PMIA), poly-p-phenylene terephthalamide (PPTA), polyurethane (PU), polycarbonate (PC), polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT), poly(butylene succinate-co-butylene adipate) (PBSA), polyhydroxybutyrate (PHB), poly(3-hydroxybutyrate- co-3-hydroxyvalerate) (PHBV), poly
  • PVA polyviny
  • the method 600 can proceed to process block 618, where the processed plant material piece is pressed in a direction crossing its longitudinal direction.
  • the pressing can be in a direction substantially perpendicular to the longitudinal direction, while in other embodiments the pressing may have a force component perpendicular to the longitudinal direction.
  • the pressing can be effective to reduce a thickness of the processed plant material piece(s), thereby increasing its density as well as collapsing (at least partially) the natural lumina (e.g., vessels, lumen in each fiber, parenchyma cells, etc.), voids, and/or gaps within the cross-section of the processed plant material piece(s).
  • the pressing can be along a single direction (e.g., along radial direction R), for example, to reduce a thickness of the processed plant material piece(s) (e.g., at least a 5:2 reduction in dimension as compared to the plant material piece(s) prior to pressing).
  • the processed plant material piece(s) can be simultaneously pressed in two directions (e.g., along radial direction R and a second direction perpendicular to both the radial direction R and the longitudinal direction L), for example, to reduce a cross-sectional area of the plant material piece(s) (e.g., to produce a densified rectangular bar).
  • the processed plant material piece(s) can be sequentially pressed in different directions (e.g., first along radial direction R and then along a second direction perpendicular to the radial direction R and longitudinal direction L).
  • the pressing may be performed without any prior drying of the plant material piece(s) or with the plant material piece(s) retaining at least some water or other fluid therein. The pressing can thus be effective to remove at least some water or other fluid from the plant material piece(s) at the same time as its dimension is reduced and density increased.
  • a separate drying process can be combined with the pressing process.
  • the plant material piece(s) may initially be pressed to cause densification and remove at least some water or fluid therefrom, followed by a drying process (e.g., air drying) to remove the remaining water or fluid.
  • a drying process e.g., air drying
  • the plant material piece(s) may initially be dried to remove at least some water or fluid therefrom (e.g., initial drying in a humidity chamber followed by air drying at room temperature, such that the moisture content of the plant material piece(s) approaches but remains greater than 15 wt%, for example, 10 wt%), followed by pressing to cause densification (and potentially further removal of water or other fluid, for example, a moisture content less than 10 wt%, such as 3-8 wt%).
  • the pressing can encourage hydrogen bond formation between the cellulose-based fibers of the cell walls of the plant material piece(s), thereby improving mechanical properties of the plant material piece.
  • any particles or materials formed on surfaces of the plant material piece(s) or within the plant material piece(s) can be retained after the pressing, with the particles/materials on internal surfaces being embedded within the collapsed lumina and intertwined cell walls.
  • the pressure and timing of the pressing can be a factor of the size of plant material piece(s) prior to pressing, the desired size of the plant material piece(s) after pressing, the water or fluid content within the plant material piece(s) (if any), the temperature at which the pressing is performed, relative humidity, the characteristics of material (e.g., infiltrated polymer) from the internal modification (if any), and/or other factors.
  • the plant material piece(s) can be held under pressure for a time period of 1 minute up to several hours (e.g., 1-180 minutes, inclusive). In some embodiments, the plant material piece(s) can be held under pressure for 3- 72 hours, inclusive.
  • the pressing can be performed at a pressure between 0.5 MPa and 20 MPa, inclusive, for example, 5 MPa.
  • the pressing may be performed without heating (e.g., cold pressing), while in other embodiments the pressing may be performed with heating (e.g., hot pressing).
  • the pressing may be performed at a temperature between 20 °C and 160 °C, e.g., greater than or equal to 100 °C.
  • the pressing can be effective to fully collapse the lumina of the native cellulose- based microstructure of the plant material and/or can result in a density for the compressed plant material of at least 1.15 g/cm 3 (e.g., > 1.2 g/cm 3 or > 1.3 g/cm 3 , for example, in a range of 1.4- 1.5 g/cm 3 ).
  • the method 600 can proceed to process block 620, where the now-densified plant material piece(s) may optionally be subjected to an external modification.
  • an external modification is used to refer to the optional modification of process block 620, it is contemplated that, in some embodiments, the modification may be applied to internal features as well as external features of the densified plant material piece(s), while in other embodiments the modification may be applied to either internal features or external features of the densified plant material piece(s) without otherwise affecting the other feature.
  • the external modification can include forming, depositing, or otherwise providing a coating on one or more external surfaces of the densified plant material piece(s).
  • the coating may imbue the densified plant material piece(s) with certain advantageous properties, such as but not limited to hydrophobicity, weatherability, corrosion resistance (e.g., salt water resistant), and/or flame resistance.
  • the coating can comprise an oil-based paint, a hydrophobic paint, a polymer coating, and/or a fire-resistant coating.
  • the fire-resistant coating can include nanoparticles (e.g., boron nitride nanoparticles).
  • a coating for the densified plant material piece(s) can include boron nitride (BN), montmorillonite clay, hydrotalcite, silicon dioxide (SiCh), sodium silicate, calcium carbonate (CaCCh), aluminum hydroxide (Al(0H)3), magnesium hydroxide (Mg(OH)2), magnesium carbonate (MgCCh), aluminum sulfate, iron sulfate, 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
  • the method 600 can proceed to process block 622, where the densified plant material piece(s) can optionally be machined, cut, and/or otherwise physically manipulated in preparation for eventual use.
  • Machining processes can include, but are not limited to, cutting (e.g., sawing), drilling, woodturning, tapping, boring, carving, routing, sanding, grinding, and abrasive tumbling.
  • Manipulating process can include, but are not limited to, bending, molding, and other shaping techniques.
  • the manipulating can include assembling multiple processed plant material pieces into a single layer.
  • processed plant material strands can be mixed with a waterproof resin and interleaved together to form a mat, which can then be subjected to heat and/or pressure to bond the strands and resin together.
  • the method 600 can proceed to process block 624, where one or more non-densified plant material pieces can be provided.
  • the provision of process block 624 can be similar to the provision of process block 602.
  • the plant material of the nondensified pieces can be the same type of plant material or a different type of plant material as that used in process block 602.
  • the non-densified plant material pieces can have a density less than 1.15 g/cm 3 (e.g., ⁇ 1.0 g/cm 3 or ⁇ 0.9 g/cm 3 , for example, in a range of 0.1-0.9 g/cm 3 ).
  • the provision of process block 624 can include machining, cutting, or otherwise physically manipulating, for example, to form a layer of appropriate size for a desired configuration of the engineered structure.
  • the number of non-densified plant material pieces (or non-densified plant material layers) can be greater than the number of densified plant material pieces (or densified plant material layers), such as at least two times greater.
  • process block 626 can include layering, aligning, or otherwise positioning the non-densified and densified plant material pieces with respect to each other.
  • the non-densified plant material pieces and/or the densified plant material pieces can be coupled together using epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, and/or sodium carboxymethyl cellulose (CMC).
  • the coupling of non- densified and densified plant material pieces can form a laminated structure or portion thereof, for example, any of the engineered structures illustrated in FIGS. 1A-5E.
  • the method 600 can proceed to process block 628, where the engineered structure formed from densified and non-densified plant material pieces can be used in a particular application.
  • the engineered structure can be adapted for use as structural material (e.g., a load bearing component or a non-load bearing component).
  • structural material e.g., a load bearing component or a non-load bearing component.
  • blocks 602-628 of method 600 have been described as being performed once, in some embodiments, multiple repetitions of a particular process block may be employed before proceeding to the next decision block or process block.
  • blocks 602- process blocks may be combined and performed together (simultaneously or sequentially).
  • FIG. 6 illustrates a particular order for blocks 602-628, embodiments of the disclosed subject matter are not limited thereto. Indeed, in certain embodiments, the blocks may occur in a different order than illustrated or simultaneously with other blocks.
  • method 600 can include steps or other aspects not specifically illustrated in FIG.
  • method 600 may comprise only some of blocks 602-628 of FIG. 6.
  • An engineered structure comprising: a first laminate comprising a plurality of constituent plant material layers, the plurality of constituent plant material layers comprising one or more first layers and one or more second layers, each plant material layer being adhered to an adjacent plant material layer via one or more respective glues, wherein each first plant material layer is a densified plant material layer having a density greater than or equal to 1.15 g/cm 3 and a mechanical strength greater than or equal to a first value, and each second plant material layer is a plant material layer having a density less than 1.15 g/cm 3 and a mechanical strength less than the first value.
  • Clause 2 The engineered structure of any clause or example herein, in particular, Clause 1, wherein the plant material forming one, some, or all of the constituent layers in the first laminate is a wood or bamboo.
  • Clause 3 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-2, wherein the densified plant material forming one, some, or all of the one or more first layers is a densified wood or densified bamboo.
  • Clause 4 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-3, wherein the plant material forming one, some, or all of the one or more second layers is a native wood or native bamboo.
  • Clause 5. The engineered structure of any clause or example herein, in particular, any one of Clauses 1-4, wherein the plant material forming one, some, or all of the one or more first layers is the same plant material as that of one, some, or all of the one or more second layers.
  • Clause 6 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-5, wherein the plant material forming one, some, or all of the one or more first layers is a different plant material from that of one, some, or all of the one or more second layers.
  • the density of one, some, or all of the one or more first layers is greater than or equal to 1.2 g/cm 3 ;
  • the density of one, some, or all of the one or more second layers is less than or equal to 1.0 g/cm 3 ; or both (al) and (a2).
  • Clause 8 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-7, wherein:
  • the density of one, some, or all of the one or more second layers is less than or equal to 0.9 g/cm 3 ; or both (a3) and (a4).
  • Clause 9 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-8, wherein one, some, or all of the one or more second layers comprises one or more pieces of non-densified plant material that retains a native micro structure of cellulose-based lumina of the plant material.
  • Clause 10 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-9, wherein one, some, or all of the one or more first layers comprises one or more pieces of densified plant material, with cellulose-based lumina of a native microstructure of the plant material being substantially collapsed.
  • Clause 11 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-10, wherein one, some, or all of the one or more first layers comprises lignin-compromised plant material.
  • Clause 12 The engineered structure of any clause or example herein, in particular, Clause 11, wherein the lignin-compromised plant material comprises modified lignin therein, and the modified lignin has shorter macromolecular chains than that of native lignin in the natural plant material.
  • Clause 13 The engineered structure of any clause or example herein, in particular, Clause 12, wherein a content of the modified lignin in the one, some, or all of the one or more first layers is at least 90%, on a weight percentage basis, of a content of the native lignin in the natural plant material.
  • Clause 14 The engineered structure of any clause or example herein, in particular, any one of Clauses 12-13, wherein a content of the modified lignin in the one, some, or all of the one or more first layers is at least 20 wt%.
  • Clause 15 The engineered structure of any clause or example herein, in particular, any one of Clauses 12-14, wherein the one, some, or all of the one or more first layers comprises a salt of an alkaline chemical immobilized within a cellulose-based micro structure of the lignin- compromised plant material.
  • Clause 16 The engineered structure of any clause or example herein, in particular, Clause 15, wherein the salt is substantially pH-neutral.
  • Clause 17 The engineered structure of any clause or example herein, in particular, Clause 11, wherein the lignin-compromised plant material comprises at least partially delignified wood.
  • Clause 18 The engineered structure of any clause or example herein, in particular, Clause 17, where a lignin content of the at least partially delignified plant material is between 5% and 95%, inclusive, of a lignin content of the natural plant material.
  • Clause 19 The engineered structure of any clause or example herein, in particular, any one of Clauses 17-18, wherein: the plant material is a hardwood or bamboo, and a lignin content of the at least partially delignified plant material is between 0.9 wt% and 23.8 wt%, inclusive; or the plant material is a softwood, and a lignin content of the at least partially delignified plant material is between 1.25 wt% and 33.25 wt%, inclusive.
  • Clause 20 The engineered structure of any clause or example herein, in particular, any one of Clauses 17-19, wherein a lignin content of the at least partially delignified plant material is at least 10 wt%.
  • each first layer consists essentially of densified plant material
  • each second layer consists essentially of non-densified wood; or both (a5) and (a6).
  • Clause 22 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-21, wherein the one or more respective glues comprise epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • the one or more respective glues comprise epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • Clause 23 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-22, wherein: one, some, or all of the one or more first layers is formed from a wood species that is the same as that of one, some, or all of the one or more second layers; or one, some, or all of the one or more first layers is formed from a wood species that is different from that of one, some, or all of the one or more second layers.
  • Clause 24 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-23, wherein one, some, or all of the one or more first layers is disposed within the first laminate at a respective location where the first laminate experiences a highest stress.
  • Clause 25 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-24, wherein one, some, or all of the one or more first layers is disposed as a respective outermost layer of the first laminate.
  • Clause 26 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-25, wherein the one or more first layers encloses the one or more second layers in a cross-sectional view.
  • Clause 27 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-26, wherein the one or more first layers fully encloses the one or more second layers on all sides.
  • Clause 28 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-27, wherein: the second layers comprise a stack of plant material boards arranged such that adjacent plant material boards have orthogonal orientations, and the stack of plant material boards is disposed between a pair of the first layers so as to form a reinforced cross -laminated timber (CLT) structure.
  • CLT cross -laminated timber
  • Clause 29 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-28, wherein the first laminate comprises a plurality of the second layers and a pair of first layers, each second layer comprising one or more plant material segments, the second layers being arranged in a stack such that adjacent second layers have parallel orientations, the stack being disposed between the pair of first layers so as to form a reinforced glued laminated (glulam) structure.
  • the first laminate comprises a plurality of the second layers and a pair of first layers, each second layer comprising one or more plant material segments, the second layers being arranged in a stack such that adjacent second layers have parallel orientations, the stack being disposed between the pair of first layers so as to form a reinforced glued laminated (glulam) structure.
  • Clause 30 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-28, wherein the first laminate comprises a plurality of the second layers and a pair of first layers, each second layer comprising one or more plant material veneers, the second layers being arranged in a stack such that adjacent second layers have parallel orientations, the stack being disposed between the pair of first layers so as to form a reinforced laminated veneer lumber (LVL) structure.
  • LTL reinforced laminated veneer lumber
  • Clause 31 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-30, further comprising: a second laminate comprising a second plurality of constituent plant material layers, the second plurality of constituent plant material layers comprising one or more third layers and one or more fourth layers, each plant material layer being adhered to an adjacent plant material layer via one or more respective glues; and a web extending between the first and second laminates, wherein each third layer is a densified plant material layer having a density greater than or equal to 1.15 g/cm 3 and a mechanical strength greater than or equal to a second value, each fourth layer is a plant material layer having a density less than 1.15 g/cm 3 and a mechanical strength less than the second value, the web and the first and second laminates together form an I-joist, and the first and second laminates form first and second flanges, respectively, of the I-joist. Clause 32. The engineered structure of any clause or example herein, in particular, Clause 31, wherein the web
  • Clause 33 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-32, wherein the web comprises one or more pieces of densified plant material, with cellulose-based lumina of a native microstructure of the plant material being substantially collapsed.
  • Clause 34 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-33, wherein the plant material forming one, some, or all of the constituent layers in the second laminate is a wood or bamboo.
  • the plant material forming one, some, or all of the one or more third layers is a densified wood or densified bamboo
  • the plant material forming one, some, or all of the one or more fourth layers is a native wood or native bamboo; or both (a7) and (a8).
  • Clause 36 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-35, wherein one of the one or more first layers forms an exposed side of the first flange opposite the web, and/or one of the one or more third layers forms an exposed side of the second flange opposite the web.
  • Clause 37 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-35, wherein:
  • one of the one or more second layers forms an exposed side of the first flange opposite the web, and one of the one or more first layers is disposed within the first flange between the exposed side of the first flange and the web;
  • one of the one or more fourth layers forms an exposed side of the second flange opposite the web, and one of the one or more third layers is disposed within the second flange between the exposed side of the second flange and the web; or both (a9) and (blO).
  • Clause 38 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-37, wherein the first value, the second value, or both are 100 MPa.
  • Clause 39 The engineered structure of any clause or example herein, in particular, any one of Clauses 31-37, wherein the mechanical strength of each first layer, the mechanical strength of each third layer, or both are in a range of 100-600 MPa, inclusive.
  • Clause 40 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-39, wherein the first value is about 100 MPa, or the first value is in a range of 100-600 MPa, inclusive.
  • Clause 41 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-40, wherein the first laminate has a first cross-sectional area, and the first laminate has a mechanical strength greater than a laminate structure having the first cross- sectional area and formed using only the one or more second layers with the one or more glues.
  • Clause 42 The engineered structure of any clause or example herein, in particular, any one of Clauses 1-40, wherein the first laminate has a first cross-sectional area and a mechanical strength, and the first cross-sectional area is less than that of a laminate structure having the same mechanical strength and formed using only the one or more second layers with the one or more glues.
  • An engineered structural material comprising: one or more laminate structures, each laminate structure having a plurality of constituent plant material layers, each plant material layer being coupled to an adjacent plant material layer via one or more respective glues, at least one of the plurality of constituent plant material layers being a densified plant material layer having a density greater than or equal to 1.15 g/cm 3 .
  • Clause 44 The engineered structural material of any clause or example herein, in particular, Clause 43, wherein the densified plant material layer is a densified wood or densified bamboo.
  • Clause 45 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43-44, wherein the densified plant material layer has a density greater than or equal to 1.2 g/cm 3 .
  • Clause 46 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43-45, wherein the densified plant material layer has a density greater than or equal to 1.3 g/cm 3 .
  • Clause 47 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43-46, wherein the densified plant material layer comprises one or more pieces of densified wood or densified bamboo, with cellulose-based lumina of a native microstructure of the wood or bamboo being substantially collapsed.
  • Clause 48 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43,-47 wherein the densified plant material layer comprises at least partially delignified plant material or lignin-modified plant material.
  • Clause 49 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43-48, wherein the one or more glues comprises epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • the one or more glues comprises epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • Clause 50 The engineered structural material of any clause or example herein, in particular, any one of Clauses 43-49, wherein the one or more laminate structures is formed as a cross-laminated timber (CLT) structure, a glued laminated timber (glulam) structure, a laminated veneer lumber (LVL) structure, an oriented strand board (OSB) structure, or part of an I-joist structure.
  • CLT cross-laminated timber
  • glulam glued laminated timber
  • LDL laminated veneer lumber
  • OSB oriented strand board
  • each of the plurality of constituent plant material layers is either a non-densified plant material layer having a density less than 1.15 g/cm 3 or a densified plant material layer having a density of at least 1.15 g/cm 3 .
  • each of the plurality of constituent plant material layers is either a native plant material layer having a density less than 1.15 g/cm 3 or a densified plant material layer having a density of at least 1.15 g/cm 3 .
  • Clause 53 A method comprising: providing one or more first layers, each first layer comprising a densified plant material having a density greater than or equal to 1.15 g/cm 3 and a mechanical strength greater than or equal to a first value; providing one or more second layers, each second layer comprising a plant material having a density less than 1.15 g/cm 3 and a mechanical strength less than the first value; and coupling the one or more first layers to the one or more second layers via one or more respective glues so as to form a laminate.
  • Clause 54 The method of any clause or example herein, in particular, Clause 53, wherein:
  • the plant material of one, some, or all of the one or more first layers comprises densified wood or densified bamboo
  • the plant material of one, some, or all of the one or more seconds layers comprises non-densified wood or non-densified bamboo; or both (bl) and (b2).
  • Clause 55 The method of any clause or example herein, in particular, any one of Clauses 53-54, wherein:
  • the plant material of one, some, or all of the one or more first layers comprises densified wood or densified bamboo
  • the plant material of one, some, or all of the one or more second layers comprises native wood or native bamboo; or both (b3) and (b4).
  • Clause 56 The method of any clause or example herein, in particular, any one of Clauses 53-55, wherein: the density of one, some, or all of the one or more first layers is greater than or equal to
  • the density of one, some, or all of the one or more first layers is greater than or equal to
  • the density of one, some, or all of the one or more second layers is less than or equal to 1.0 g/cm 3 ; the density of one, some, or all of the one or more second layers is less than or equal to 0.9 g/cm 3 ; or any combination of the foregoing.
  • Clause 57 The method of any clause or example herein, in particular, any one of Clauses 53-56, wherein the providing the one or more first layers comprises: subjecting one or more pieces of natural plant material having native lignin therein to a chemical treatment so as to compromise the native lignin, thereby forming one or more pieces of lignin-compromised plant material; and compressing the one or more pieces of lignin-compromised plant material to form the densified plant material of the one or more first layers, wherein the density of the densified plant material after the compressing is greater than a density of the natural plant material prior to the subjecting.
  • Clause 58 The method of any clause or example herein, in particular, Clause 57, wherein the compressing is in a direction crossing a longitudinal growth direction of the one or more pieces of lignin-compromised plant material.
  • Clause 59 The method of any clause or example herein, in particular, any one of Clauses 57-58, wherein the compressing comprises pressing the one or more pieces of lignin- compromised plant material at a pressure of at least 1 MPa.
  • Clause 60 The method of any clause or example herein, in particular, any one of Clauses 57-59, wherein the compressing comprises pressing the one or more pieces of lignin- compromised plant material at a pressure in a range of 5-20 MPa, inclusive.
  • Clause 61 The method of any clause or example herein, in particular, any one of Clauses 57-60, wherein the compressing comprises pressing the one or more pieces of lignin- compromised plant material while subjecting to a temperature of at least 50 °C.
  • Clause 62 The method of any clause or example herein, in particular, any one of Clauses 57-61, wherein the compressing comprises pressing the one or more pieces of lignin- compromised plant material while subjecting to a temperature in a range of 80-180 °C, inclusive.
  • Clause 63 The method of any clause or example herein, in particular, Clause 57-62, wherein, after the subjecting, the one or more pieces of lignin-compromised plant material has modified lignin therein, and the modified lignin has shorter macromolecular chains than that of native lignin in the piece of natural plant material.
  • Clause 64 The method of any clause or example herein, in particular, Clause 63, wherein the subjecting to the chemical treatment comprises: infiltrating the one or more pieces of natural plant material with one or more chemical solutions; and after the infiltrating, subjecting the one or more pieces of natural plant material with the one or more chemical solutions therein to a first temperature of at least 80 °C for a first time, so as to form the one or more pieces of lignin-compromised plant material.
  • Clause 65 The method of any clause or example herein, in particular, Clause 64, wherein the one or more chemical solutions comprise 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, NaHSCh + SO2 + AQ, NaOH + Na2Sx, where AQ is Anthraquinone, any of the foregoing with NaOH replaced by LiOH or KOH, or any combination of the foregoing.
  • the one or more chemical solutions comprise p-toluenesulfonic acid, NaOH, NaOH + Na 2 SO 3 /Na 2 SO 4 , NaOH + Na 2
  • Clause 66 The method of any clause or example herein, in particular, any one of Clauses 64-65, wherein: the first temperature is in a range of 120-160 °C, inclusive; and/or the first time is in a range of 1-5 hours, inclusive.
  • Clause 67 The method of any clause or example herein, in particular, any one of Clauses 64-66, wherein at least 90% of the one or more chemical solutions infiltrated into the one or more pieces of natural plant material is consumed by the subjecting to the first temperature for the first time.
  • Clause 68 The method of any clause or example herein, in particular, any one of Clauses 64-67, wherein the subjecting to the first temperature for the first time comprises using steam to heat the one or more pieces of natural plant material with the one or more chemical solutions therein.
  • Clause 69 The method of any clause or example herein, in particular, any one of Clauses 64-68, wherein, after the subjecting to the first temperature for the first time:
  • a content of modified lignin in the one or more pieces of lignin-compromised plant material is at least 90%, on a weight percentage basis, of a content of the native lignin in the one or more pieces of natural plant material;
  • a content of modified lignin in the one or more pieces of lignin-compromised plant material is at least 20 wt%; or both (b5) and (b6).
  • Clause 70 The method of any clause or example herein, in particular, any one of Clauses 64-69, wherein, after the subjecting to the first temperature for the first time, a salt of an alkaline chemical is immobilized within a cellulose-based micro structure of the one or more pieces of lignin-compromised plant material.
  • Clause 71 The method of any clause or example herein, in particular, Clause 70, wherein the salt is substantially pH-neutral.
  • Clause 72 The method of any clause or example herein, in particular, any one of Clauses 70-71, wherein the salt is formed by reaction of the one or more chemical solutions with an acidic degradation product of native hemicellulose in the one or more pieces of natural plant material produced by the one or more chemical solutions.
  • Clause 73 The method of any clause or example herein, in particular, any one of Clauses 57-62, wherein, after the subjecting to a chemical treatment, the one or more pieces of lignin-compromised plant material is at least partially delignified.
  • Clause 74 The method of any clause or example herein, in particular, Clause 73, wherein the subjecting to the chemical treatment comprises partial or full immersion of the one or more pieces of natural plant material in one or more chemical solutions at a second temperature for a second time, so as to remove at least some lignin from the one or more pieces of natural plant material.
  • Clause 75 The method of any clause or example herein, in particular, Clause 74, wherein the one or more chemical solutions comprise an alkaline solution.
  • Clause 76 The method of any clause or example herein, in particular, any one of Clauses 74-75, wherein the one or more chemical solutions comprise sodium hydroxide (NaOH), lithium hydroxide (LiOH), potassium hydroxide (KOH), sodium sulfite (Na2SOs), sodium sulfate (Na2SO4), sodium sulfide (Na2S), Na n S wherein n is an integer, urea (CH4N2O), sodium bisulfite (NaHSOs), NaH2Os, sulfur dioxide (SO2), anthraquinone (C14H8O2), methanol (CH3OH), ethanol (C2H5OH), butanol (C4H9OH), formic acid (CH2O2), hydrogen peroxide (H2O2), acetic acid (CH3COOH), butyric acid (C4H8O2), peroxyformic acid (CH2O3), peroxyacetic acid (C2H4O3)
  • Clause 77 The method of any clause or example herein, in particular, any one of Clauses 74-76, wherein the one or more chemical solutions comprise a boiling mixture of NaOH and Na2SO3.
  • Clause 78 The method of any clause or example herein, in particular, any one of Clauses 74-77, wherein:
  • the second temperature is in a range of 100-160 °C, inclusive;
  • the second time is in a range of 0.1-96 hours, inclusive; or both (b7) and (b8).
  • Clause 79 The method of any clause or example herein, in particular, any one of Clauses 74-78, wherein a lignin content of the one or more pieces of lignin-compromised plant material is between 5% and 95%, inclusive, of a lignin content of the natural plant material. Clause 80.
  • any one of Clauses 74-79 wherein: the native plant material is a hardwood or bamboo, and a lignin content of the lignin- compromised plant material is between 0.9 wt% and 23.8 wt%, inclusive; or the native plant material is a softwood, and a lignin content of the lignin-compromised plant material is between 1.25 wt% and 33.25 wt%, inclusive.
  • Clause 81 The method of any clause or example herein, in particular, any one of Clauses 74-80, wherein a lignin content of the lignin-compromised plant material is at least 10 wt%.
  • each first layer consists essentially of densified plant material
  • each second layer consists essentially of non-densified or native plant material; or both (b9) and (blO).
  • Clause 83 The method of any clause or example herein, in particular, any one of Clauses 53-82, wherein the one or more respective glues comprise epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • the one or more respective glues comprise epoxy, polyurethane adhesive, polyvinyl acetate-isocyanate adhesive, resorcinol formaldehyde resin adhesive, phenolic resin, sodium carboxymethyl cellulose (CMC), or any combination of the foregoing.
  • Clause 84 The method of any clause or example herein, in particular, any one of Clauses 53-83, wherein the first and second layers are coupled in the form of a reinforced crosslaminated timber structure, a reinforced glued laminated structure, a reinforced laminated veneer structure, an oriented strand board structure, an I-joist structure, or a part of any of the foregoing.
  • Clause 85 The method of any clause or example herein, in particular, any one of Clauses 53-84, wherein one, some, or all of the one or more second layers comprises a nondensified plant material.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Forests & Forestry (AREA)
  • Ceramic Engineering (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)

Abstract

Une structure fabriquée peut comprendre un premier stratifié comportant une pluralité de couches de matériau végétal constitutives. La pluralité de couches de matériau végétal constitutives peut comprendre une ou plusieurs premières couches et une ou plusieurs secondes couches. Chaque couche de matériau végétal peut être collée à une couche de matériau végétal adjacente par l'intermédiaire de colle. Chaque première couche peut être une couche de matériau végétal densifié présentant une masse volumique supérieure ou égale à 1,15 g/cm3 et une première résistance mécanique. Chaque seconde couche peut être une couche de matériau végétal présentant une masse volumique inférieure à 1,15 g/cm3 et une seconde résistance mécanique inférieure à la première résistance mécanique. Par exemple, le matériau végétal de chaque couche peut être du bois ou du bambou.
PCT/US2023/030783 2022-08-22 2023-08-22 Matériaux structuraux fabriqués à résistance améliorée, et leurs procédés de fabrication et d'utilisation WO2024044160A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4413459A (en) * 1981-03-16 1983-11-08 Boise Cascade Corporation Laminated wooden structural assembly
US6224704B1 (en) * 1996-09-03 2001-05-01 Weyerhaeuser Company Method for manufacture of structural wood products
US20190099987A1 (en) * 2016-09-30 2019-04-04 Daiken Corporation Wood laminate material and method for manufacturing same
US20200122438A1 (en) * 2017-07-03 2020-04-23 Kronospan Luxembourg S.A. Oriented strand board, process for production of an oriented strand board and apparatus for producing an oriented strand board

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4413459A (en) * 1981-03-16 1983-11-08 Boise Cascade Corporation Laminated wooden structural assembly
US6224704B1 (en) * 1996-09-03 2001-05-01 Weyerhaeuser Company Method for manufacture of structural wood products
US20190099987A1 (en) * 2016-09-30 2019-04-04 Daiken Corporation Wood laminate material and method for manufacturing same
US20200122438A1 (en) * 2017-07-03 2020-04-23 Kronospan Luxembourg S.A. Oriented strand board, process for production of an oriented strand board and apparatus for producing an oriented strand board

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