BAMBOO STRUCTURES, AND METHODS FOR FABRICATION AND USE THEREOF
Natural bamboo is chemically treated to remove at least some lignin therefrom. As a result, the bamboo becomes more porous and less rigid, while otherwise retaining the aligned microstructure of bamboo fibers and constituent cellulose nanofibers. In some embodiments, the treated bamboo can then be pressed such that the lumina therein at least partially collapse, thereby improving the strength and toughness of the bamboo among other properties. In some embodiments, the treated bamboo can be infiltrated with a polymer or polymer precursor, and/or have non-native particles added to surfaces thereof to tailor properties of the resulting bamboo structure. By further modifying, manipulating, or machining the treated bamboo, it can be adapted to various applications.
1 . A method comprising:
removing at least some lignin from a segment of wood or bamboo; and
after the removing, twisting the segment upon itself so as to form a densified structure with intertwined curved cell walls therein.
2 . The method of claim 1 , wherein:
after the removing and prior to the twisting, the segment retains natural lumina of the wood or bamboo; and
after the twisting, the retained lumina have collapsed.
3 . The method of claim 1 , wherein the twisting is about an axis substantially parallel to a longitudinal direction of the segment.
4 . The method of claim 1 , further comprising, after the removing and prior to the twisting, subjecting the segment to a softening treatment.
5 . The method of claim 4 , wherein the softening treatment comprises exposing the segment to steam at an elevated pressure.
6 . The method of claim 5 , wherein, during the softening treatment, the steam is at a temperature greater than 130° C. and a pressure in a range of 6-10 bar.
7 . The method of claim 5 , wherein an amount of lignin removed from the segment prior to the softening treatment is less than 10%.
8 . The method of claim 1 , wherein an amount of lignin removed from the segment prior to the twisting is at least 40%.
9 . The method of claim 1 , further comprising, after the twisting, applying a polymer coating to the densified structure.
10 . The method of claim 1 , further comprising, after the removing and prior to the twisting, infiltrating the segment with a polymer or precursor thereof.
11 . The method of claim 1 , wherein the removing at least some lignin comprises subjecting the segment to one or more chemical treatments.
12 . The method of claim 1 , further comprising, after the twisting, drying the densified structure.
13 . The method of claim 12 , wherein, after the drying, the densified structure has a mechanical strength of at least 450 MPa.
14 . A structure comprising:
a densified, partially-delignified segment of wood or bamboo twisted upon itself,
wherein the densified segment has intertwined curved cell walls and collapsed lumina therein.
15 . The structure of claim 14 , wherein the densified segment is in a form of a rope.
16 . The structure of claim 14 , further comprising a polymer coating on the densified segment.
17 . The structure of claim 14 , wherein the densified segment comprise a polymer infiltrated therein.
18 . The structure of claim 14 , wherein the densified segment has a mechanical strength of at least 450 MPa.
19 . A method comprising:
removing at least some lignin from a segment of bamboo by subjecting to one or more chemical treatments; and
after the removing, drying the bamboo segment so as to form a densified structure.
20 . The method of claim 19 , wherein the drying comprises microwave heating of the bamboo segment.