A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A flexible structure is formed by subjecting cellulose-based natural wood material to a chemical treatment that partially removes hemicellulose and lignin therefrom. The treated wood has a unique 3-D porous structure with numerous channels, excellent biodegradability and biocompatibility, and improved flexibility as compared to the natural wood. By further modifying the treated wood, the structure can be adapted to particular applications. For example, nanoparticles, nanowires, carbon nanotubes, or any other coating or material can be added to the treated wood to form a hybrid structure. In some embodiments, open lumina within the structure can be at least partially filled with a non-wood substance, such as a flexible polymer, or with entangled cellulose nanofibers. The unique architecture and superior properties of the flexible wood allow for its use in various applications, such as, but not limited to, structural materials, solar thermal devices, flexible electronics, tissue engineering, thermal management, and energy storage.

A method for improving the fire resistance of a cellulose material comprises mixing boric acid with methanol to form a boric acid ester, combining the borate ester with magnesium sulfate to form a low viscosity magnesium borate sulfate solution, treating the cellulose material with the magnesium borate sulfate solution, and heating the treated cellulose material to evaporate remaining alcohol and solvent to form a crystals of a complex mixture containing combinations of magnesium sulfate, boric acid, magnesium borate, magnesium borate sulfate and their hydrates.

The present invention discloses a one-step integrally-formed bamboo sleeper. For the one-step integrally-formed bamboo sleeper, a bamboo unit is used as a raw material, to be dried and modified at the temperature of 110-180° C., and then subject to adhesive dipping, adhesive throwing, solidification, dopamine solution treatment, anti-mildew and/or anti-corrosion and/or anti-insect treatment, and fastening, to obtain the one-step integrally-formed bamboo sleeper with a density of 0.9-1.5 g/cm.sup.3. The present invention further provides a preparation method for the foregoing bamboo sleeper. The bamboo sleeper prepared in the present invention has a suitable elastic modulus, and applicable for ballasted tracks of railways and urban rail transit systems.

The present invention discloses a one-step integrally-formed bamboo sleeper. For the one-step integrally-formed bamboo sleeper, a bamboo unit is used as a raw material, to be dried and modified at the temperature of 110-180° C., and then subject to adhesive dipping, adhesive throwing, solidification, dopamine solution treatment, anti-mildew and/or anti-corrosion and/or anti-insect treatment, and fastening, to obtain the one-step integrally-formed bamboo sleeper with a density of 0.9-1.5 g/cm.sup.3. The present invention further provides a preparation method for the foregoing bamboo sleeper. The bamboo sleeper prepared in the present invention has a suitable elastic modulus, and applicable for ballasted tracks of railways and urban rail transit systems.

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A super strong and tough densified wood structure is formed by subjecting a cellulose-based natural wood material to a chemical treatment that partially removes lignin therefrom. The treated wood retains lumina of the natural wood, with cellulose nanofibers of cell walls being aligned. The treated wood is then pressed in a direction crossing the direction in which the lumina extend, such that the lumina collapse and any residual fluid within the wood is removed. As a result, the cell walls become entangled and hydrogen bonds are formed between adjacent cellulose nanofibers, thereby improving the strength and toughness of the wood among other mechanical properties. By further modifying, manipulating, or machining the densified wood, it can be adapted to various applications.

A method for preparing a wood preservative composition, includes modifying lignin with Na.sub.2B.sub.4O.sub.7 or NaNO.sub.3 and then with a chromium (II) salt, copper (II), cadmium (II) or zinc (II), for example, metal nitrates (Cr(NO.sub.3).sub.2, Cu(NO.sub.3).sub.2, Cd(NO.sub.3).sub.2, Zn(NO.sub.3).sub.2); to the preservative obtainable by this method; and to a method for preserving wood; and to the preserved wood. The preservative prevents degradation by xylophagous and fungal agents, and also improves some properties of the wood, and the hygroscopicity and fire resistance.

A method (10) for ethanol-based extraction of soluble wood components. Wood is prepared (12), and chipped (18) to provide wood chips. The wood chips and a liquid are mixed (20) in a container to provide a mixture. After waiting (22) for a specified time, RF energy is applied (26) to the mixture while controlling (28) at least one an RF power level, a temperature of the mixture, a time of application of the RF energy, or a speed of a pump which is circulating the liquid in the mixture. The mixture is then cooled (30), the liquid and the components are removed (32) from the container, and are filtered (36) to provide a filtered extract. The wood may be heated (14) such as by charring and/or toasting before being chipped. Oxygen may be added (34) to the liquid and the components removed from the container before being filtered.