CN108943245B - Preparation method of multifunctional carbonized wood - Google Patents

Abstract

The invention discloses a method for preparing multifunctional carbonized wood, relating to a method for preparing carbonized wood. The present invention aims to solve the problem that the existing wood modification methods cannot simultaneously improve wood mechanical strength, impact toughness, waterproof performance, endow sterilization, flame-retardant magnetism and other functional problems. Methods: 1. pretreatment of wood softening; 2. superhydrophobic treatment of softened wood composited with inorganic nanomaterials; 3. wood compression and densification treatment; 4. high-temperature carbonization treatment of wood. The wood modified by the method of the present invention has a micro-nano-level microstructure endowed by inorganic nanomaterials and sandpaper. There are inorganic nanomaterials inside and on the surface of the wood, and the wood base is further covered by hydrophobic substances, similar to the microstructure of lotus leaves, and the porous structure of wood. It is compressed and dense, has super-hydrophobic function, and the tensile strength, compressive strength, impact toughness, hardness, wear resistance, elastic modulus and static bending strength are significantly improved. The invention is used in the field of wood modification.

Description

Preparation method of multifunctional carbonized wood

technical field

The invention relates to a preparation method of carbonized wood.

Background technique

Because of its complex and unique composition (mainly cellulose, hemicellulose and lignin), wood is easy to absorb water and cause swelling and deformation, easy to decay and degrade due to mold erosion, easy to burn and degrade due to heat, etc.; also because of its loose porous structure. This is especially true for the density and strength of fast-growing species of wood (such as poplar, fir, birch, etc.). In order to improve the strength of wood, prolong the service life of wood (improving its waterproof, anti-corrosion, flame-retardant and other durability), and even endow some unique functions such as magnetism, people use a variety of methods to modify wood. In general, it mainly includes The following types: 1. Use vinyl monomers to form polymers to fill wood through free radical polymerization in the wood pore-like cell cavity structure, or use (phenolic resin, melamine resin, etc.) prepolymers in the wood cell cavity structure Polymer filling wood is formed through polycondensation reaction, which can increase the density of wood, improve mechanical properties and partially improve durability (dimensional stability and anti-corrosion performance), but this method will lead to increased wood brittleness and reduced impact toughness; 2. The whole or surface of the wood is hydrothermally softened, and then the wood entity or surface is compressed along the direction perpendicular to the axial direction of the wood to make the whole or surface of the wood dense, so as to achieve the purpose of increasing the density of the compressed wood and improving the strength of the wood, but the The compressed and densified wood produced by the method is not waterproof, and it will rebound in size when it encounters water. Although people use phenolic resin and other polymers to fix the compressed and densified wood to a certain extent. The impact toughness of wood is greatly reduced, and the brittleness is increased; 3. Use high temperature (180-220°C) to heat treat wood to degrade the hemicellulose in the wood to a certain extent, and obtain environmentally friendly carbonized wood with good dimensional stability and certain anti-corrosion properties , is favored by the market, but the brittleness of the wood itself will increase and the mechanical properties will decrease; 4. Use nanotechnology to generate nano-inorganic bodies (such as silicon dioxide, titanium dioxide, zinc oxide, silver, ferric oxide, etc.) in situ in wood, Or directly filled with nano-inorganic bodies, it will endow wood with super waterproof, even bactericidal, flame retardant, electromagnetic shielding and other functions, so that the waterproof performance of wood can be fundamentally improved, but this method is difficult to effectively improve the mechanical strength of wood. In short, the current treatment methods cannot find a balance between the improvement of the mechanical strength of wood and the permanent waterproofing of wood, that is, they cannot simultaneously improve wood strength and waterproof performance, let alone impart other functional properties simultaneously.

In recent years, with the development of society and the improvement of people's living standards, wood has played an increasingly important role in human life; at the same time, the contradiction between wood demand and wood supply has become more and more acute. Therefore, through appropriate technology Improve wood, so that the strength, waterproof performance, bactericidal antiseptic performance and flame retardant performance of wood (especially low-quality fast-growing tree species wood) are significantly improved simultaneously, and even have a unique magnetic function, which is expected to greatly increase the added value of wood. service life and alleviate the dilemma of wood supply shortage.

Contents of the invention

The present invention aims to solve the problem that existing wood modification methods cannot simultaneously improve wood mechanical strength, impact toughness, waterproof performance, and endow functions such as sterilization and flame-retardant magnetism, and provides a preparation method of multifunctional carbonized wood.

The preparation method of multifunctional carbonized wood of the present invention, carry out according to the following steps:

1. Wood softening pretreatment:

Soak the wood in distilled water, heat it to 100°C, and cook the wood for 2 hours to obtain softened wood;

Or place the wood in 1.5-3wt% NaOH aqueous solution, heat it at 90°C for 2-4 hours to remove most of the hemicellulose, and then wash it with distilled water at room temperature until it becomes neutral to obtain softened wood.

Or spray steam at 120°C on the surface of the wood for 2 hours to obtain softened wood.

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

① Add inorganic nanomaterials with a diameter or thickness of 1-100nm to toluene, and add polydimethylsiloxane, then ultrasonically disperse at a power of 500-550Hz for 1-1.5h, and then at room temperature with 1000- Stir mechanically at a speed of 1200rpm for 70 to 74 hours; then centrifuge at a speed of 6000 to 7000rpm for 15 to 30min, and successively wash with dichloromethane and acetone repeatedly for 3 to 5 times, and then centrifuge at 6000 to 7000rpm for 15 to 30min. Dry at ~110°C for 22-26 hours; the volume ratio of the mass of inorganic nanomaterials to toluene is 1g:(90-110)mL, and the mass ratio of inorganic nanomaterials to polydimethylsiloxane is 1:(0.5～ 0.7);

②Add the inorganic nanomaterials treated in step 1 into absolute ethanol, then add dropwise fluorosilane to it as a hydrophobic substance, then mechanically stir at a speed of 1000-1200rpm for 1-1.5h, and then mix it under a power of 500-550Hz Ultrasonic dispersion for 1 to 1.5 hours, and finally stirred at 60 to 65°C for 30 to 40 minutes to obtain a liquid;

③Place the wood in the liquid obtained in step ②, then pressurize it under 0.8-0.9MPa pressure for 30-40min, then return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials.

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the treated wood in step 2, so that the rough surface of the sandpaper is in contact with the wood, then place the wood with sandpaper in a hot press, and compress at room temperature and 5-10 MPa Wood to 20%-25% of the original thickness; then gradually increase the temperature: first increase the temperature to 60-80°C and maintain the pressure for 8-10h, then continue to increase the temperature to 100-120°C and maintain the pressure for 24-48h, and then maintain the pressure The hot press is cooled to room temperature at a rate of 20°C/h, and then returned to normal pressure and the sandpaper is removed to complete the wood compression and densification treatment. At this time, the wood thickness is compressed to 20%-25% of the original.

4. Wood high temperature carbonization treatment:

Put the wood treated in step 3 in a high-temperature carbonization box, raise the temperature to 130-150°C at a rate of 5-10°C/h and keep it warm for 2-3h, and then continue to heat up to 180-200°C at a rate of 5-10°C/h ℃ and keep it warm for 24-48h; or continue to place it in a hot press, under the pressure of 5-10MPa in step 3, raise the temperature to 180-200°C at a rate of 5-10℃/h and keep it warm for 24-48h.

Afterwards, gradually cool down to 150°C at a rate of 3-5°C/h and keep it warm for 2-3 hours. During the heat preservation stage, spray water steam on the wood for 10 minutes every 1h; then gradually cool down to 120°C at a rate of 3-5°C/h. ℃ and keep warm for 2-3h, spray water steam on the wood for 10min every 1h during the heat preservation stage; The speed is cooled to room temperature, that is, multi-functional carbonized wood.

Further, the inorganic nanomaterials in step 2 ① are nano-silicon dioxide, nano-titanium dioxide, nano-silver, nano-zinc oxide, nano-ferric oxide, nano-calcium carbonate, two-dimensional nano-clay, two-dimensional nano-boron nitride, two-dimensional Graphene or two-dimensional graphene oxide and composites of two or more in any proportion, but not limited to these nanomaterials

Further, the mass ratio of inorganic nanomaterials to absolute ethanol in step 2② is 1:(29-31), and the mass ratio of inorganic nanomaterials to fluorosilane is 1:(0.2-0.4).

Further, the fluorosilane described in step 2 ③ is heptadecafluorosilyl trimethoxysilane, heptadecafluorosilyl triethoxysilane, tridecafluorosilyl trimethoxysilane, tridecafluorosilyl triethyl A mixture of one or more of the oxysilanes in any ratio.

Beneficial effects of the present invention:

The invention provides a multifunctional carbonized wood preparation method with simple operation, environmental friendliness, low cost, super waterproof, high strength, even partial sterilization, flame retardant and magnetic functions.

In order to increase the strength of the wood, the present invention applies hot-pressing treatment to the wood surface, so that the wood surface does not have a micron-level rough structure. Therefore, while compounding inorganic nanomaterials, 120-purpose sandpaper is covered to reduce the micron-scale roughness of the sandpaper during hot pressing. The super-hydrophobic function of the wood surface can be endowed with high strength and good wear resistance in combination with the nano-scale structure of the inorganic nanomaterial itself. performance. The purpose of hot pressing coated sandpaper in the present invention is to increase the roughness (unevenness) of the wood surface, thereby imparting super-hydrophobic properties.

The softening treatment in step 1 is convenient for ① wood is easier to compress and compact, so as to avoid the cell wall from being crushed and broken during compression and negatively affect the mechanical strength; ② when softened with alkaline water at high temperature, a large amount of hemicellulose can be removed, effectively avoiding The phenomenon of water absorption and rebound after wood compression is eliminated, ③ softening and removal of a large amount of hemicellulose not only provides enough nano space to store subsequent nano functional particles, thereby providing conditions for enriching the functionality of wood, but also facilitating the subsequent compression process, and The nano-functional particles are firmly sealed inside the wood by compression, so that the functionality lasts longer; the second step is to add inorganic nano-materials to the wood cell cavity, which can give the wood a nano-scale rough structure to facilitate the construction of a super-hydrophobic surface structure, and at the same time endow the wood with sterilization , flame retardant and even magnetic properties; the compression and densification in step 3 can increase the wood density and make the wood cells flattened. This densified layered structure can endow the wood with high strength, high hardness and toughness, and the surface-loaded sandpaper It can give the wood surface micron-scale protrusions, which is conducive to the construction of super-hydrophobic function; the high-temperature carbonization treatment in step 4 further removes part of the hemicellulose in the wood, improves the dimensional stability of the wood, and partially improves the anti-corrosion performance and thermal stability. In addition, the combined treatment of wood by compression and carbonization can firmly confine the nanomaterials in the wood, thereby improving the problem of water loss of the nanomaterials in the wood.

In the present invention, polydimethylsiloxane is firstly used to coat the inorganic nanomaterials, so that the inorganic nanomaterials have a certain degree of hydrophobicity; then the fluorosilane is hydrolyzed into fluorosilanes with hydroxyl groups in ethanol, and then coated with a certain amount of fluorosilane on the surface The inorganic nanomaterials of polydimethylsiloxane are hydrolyzed and condensed into fluorosilanized nanomaterials, which make the nanomaterials themselves highly hydrophobic; It will further undergo condensation reaction with wood through hydroxyl groups, so that the surface of wood components is hydrophobized by fluorosilane, so wood becomes super hydrophobic under the action of micro-nano hierarchical structure and hydrophobic substances; it synthesizes polydimethylsiloxane And the double hydrophobic function of fluorosilane, so the super hydrophobic function is excellent.

The wood modified by the method of the present invention has a micro-nano-level microstructure endowed by inorganic nanomaterials and sandpaper, and there are inorganic nanomaterials inside and on the surface of the wood, and the wood base is further covered by fluorine-containing hydrophobic substances, which are similar to the microstructure of lotus leaves. The porous structure is compressed and dense, and the hydrophobic angle of each surface of the prepared wood is greater than 150°, that is, the modified wood has a super-hydrophobic function; the static water contact angle of the radial section of the wood after being rubbed 20 times by 240 mesh sandpaper loaded with 100g weight It is still as high as 150° or more, the rolling angle is less than 10°, and the water absorption of wood after continuous immersion in water for 10 days is less than 5%.

The tensile strength of the wood modified by the method of the present invention can reach 360-399MPa, the compressive strength (end surface) can reach 170-210MPa, the impact toughness (chord section) can reach 135-147KJ/ ^m2 , and the hardness can reach 8500-210MPa. 10800N, wear resistance can reach 0.8~1.0, elastic modulus can reach 14000~18000MPa, static bending strength can reach 190~230MPa, mass loss rate after 12 weeks of corrosion is 90%~92%, measured by cone calorimeter The peak heat release rate is 460~575kW/m ² .

The tensile strength, compressive strength, impact toughness, hardness, abrasion resistance, elastic modulus and static bending strength of the modified wood are respectively 5-7 times, 2.5-4 times, 2-3 times, 3 times higher than that of untreated wood -5 times, 2.4-3.6 times, 1.8-2.7 times and 2.2-3.3 times, the anti-corrosion performance is improved, the flame-retardant performance is significantly improved, and even the carbonized wood treated with nano-Fe3O4 has paramagnetism.

The wood obtained by the treatment method is expected to be used in the fields of building structure materials, sports equipment materials and transportation materials that require high material strength indoors and outdoors.

Description of drawings

Fig. 1 is the SEM topography figure of the multifunctional carbonized wood cross-section based on nano-silica in embodiment 1;

Fig. 2 is the SEM topography figure of the multifunctional carbonized wood longitudinal section based on nano-silica in embodiment 1;

Fig. 3 is the static water contact angle of the timber radial section prepared in embodiment 1;

Fig. 4 is the SEM topography figure of the multifunctional carbonized wood cross-section based on nano ferric oxide in embodiment 2;

Fig. 5 is the SEM topography figure of the longitudinal section of multifunctional carbonized wood based on nano ferric oxide in embodiment 2;

Fig. 6 is the hydrophobic angle of the timber radial section prepared in embodiment 2;

Fig. 7 is the SEM topography figure of the multifunctional carbonized wood cross-section based on nano-silver in embodiment 3;

Fig. 8 is the SEM topography figure of the multifunctional carbonized wood longitudinal section based on nano-silver in embodiment 3;

Fig. 9 is the hydrophobic angle of the timber radial section prepared in embodiment 3;

Fig. 10 is the SEM topography figure of boron nitride in the cell lumen of multifunctional charred wood based on two-dimensional layered nano boron nitride in embodiment 4;

Fig. 11 is the SEM topography figure of the cross-section of multifunctional carbonized wood based on two-dimensional layered nano boron nitride in embodiment 4;

Fig. 12 is the hydrophobic angle of the timber radial section prepared in embodiment 4;

Fig. 13 is the elemental energy spectrum analysis EDX corresponding to the cross-section of multifunctional carbonized wood based on two-dimensional layered nano-boron nitride in Example 4.

detailed description

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: the preparation method of multifunctional carbonized wood of this embodiment, carry out according to the following steps:

1. Wood softening pretreatment:

Wood is placed in 1.5-3 wt% NaOH aqueous solution, heated at 90°C for 2-4 hours to remove most of the hemicellulose, and then washed with distilled water at room temperature until neutral to obtain softened wood.

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

① Add inorganic nanomaterials with a diameter or thickness of 1-100nm to toluene, add polydimethylsiloxane, then ultrasonically disperse, then mechanically stir at room temperature for 70-74h; then centrifuge for 15-30min, and successively Repeatedly wash with dichloromethane and acetone for 3 to 5 times each, centrifuge for 15 to 30 minutes, and dry for 22 to 26 hours; the volume ratio of the mass of inorganic nanomaterials to toluene is 1 g: (90 to 110) mL, inorganic nanomaterials The mass ratio to polydimethylsiloxane is 1:(0.5～0.7);

②Add the inorganic nanomaterials treated in step 1 into absolute ethanol, then drop fluorosilane into it as a hydrophobic substance, then mechanically stir for 1-1.5 hours, then ultrasonically disperse, and finally stir at 60-65°C 30 ~ 40min, get the liquid;

③ put the wood in the liquid obtained in step ②, pressurize it under the pressure of 0.8-0.9 MPa for 30-40 minutes, then return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials;

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the wood treated in step 2 (diameter section), so that the rough surface of the sandpaper is in contact with the wood, and then place the wood with sandpaper in a hot press, at room temperature, 5 ~ Compress the wood to 20%-25% of its original thickness under 10MPa; then raise the temperature step by step: first raise the temperature to 60-80°C and keep the pressure for 8-10h, then continue to raise the temperature to 100-120°C and keep the pressure for 24-48h, then While maintaining the pressure, lower the hot press to room temperature at a rate of 20°C/h, then return to normal pressure and remove the sandpaper to complete the wood compression and densification treatment;

4. Wood high temperature carbonization treatment:

Put the wood treated in step 3 in a high-temperature carbonization box, raise the temperature to 130-150°C at a rate of 5-10°C/h and keep it warm for 2-3 hours, and then continue to heat up to 180-200°C at a rate of 5-10°C/h ℃ and keep it warm for 24-48 hours; or continue to place it in the hot press, under the pressure of 5-10MPa in step 3, raise the temperature to 180-200 ℃ at a rate of 5-10 ℃/h and keep it warm for 24-48h;

After that, gradually cool down to 150°C at a rate of 3-5°C/h and keep it warm for 2-3 hours. During the heat preservation stage, spray water vapor on the wood for 10 minutes every 1h; then gradually cool down to 120°C at a rate of 3-5°C/h. ℃ and keep it warm for 2-3 hours. During the heat preservation stage, spray water steam on the wood for 10 minutes every 1 hour; The speed is cooled to room temperature, that is, multi-functional carbonized wood.

Embodiment 2: This embodiment differs from Embodiment 1 in that the method of softening and pretreating wood in step 1 is cooking, alkali treatment or steaming. Others are the same as in the first embodiment.

Embodiment 3: This embodiment is different from Embodiment 2 in that: the cooking method is to soak the wood in distilled water, heat it to 100° C., and cook the wood for 2 hours to obtain softened wood. Others are the same as in the second embodiment.

Embodiment 4: The difference between this embodiment and Embodiment 2 is that the alkali treatment method is to place the wood in an aqueous NaOH solution with a mass concentration of 2%, and heat it at 90° C. for 2 hours to remove most of the hemifibers. Plain, and then washed with distilled water at room temperature until neutral to obtain softened wood. Others are the same as in the second embodiment.

Embodiment 5: This embodiment is different from Embodiment 2 in that: the steaming method sprays water vapor at a temperature of 120° C. to steam the wood surface for 2 hours to obtain softened wood. Others are the same as in the second embodiment.

Specific embodiment six: the difference between this embodiment and specific embodiment one is that the inorganic nanomaterials in step 2.1. are nano silicon dioxide, nano titanium dioxide, nano silver, nano zinc oxide, nano ferroferric oxide, nano calcium carbonate, Two-dimensional nanoclay, two-dimensional nano-boron nitride, two-dimensional graphene or two-dimensional graphene oxide. Others are the same as in the first embodiment.

Embodiment 7: This embodiment differs from Embodiment 1 in that the power of ultrasonic dispersion in step 2 ① is 500-550 Hz, and the time of ultrasonic dispersion is 1-1.5 h. Others are the same as in the first embodiment.

Embodiment 8: The difference between this embodiment and Embodiment 1 is that the speed of mechanical stirring in step 2 ① is 1000-1200 rpm. Others are the same as in the first embodiment.

Embodiment 9: The difference between this embodiment and Embodiment 1 is that the rotational speed of the centrifuge in step 2 ① is 6000-7000 rpm. Others are the same as in the first embodiment.

Embodiment 10: The difference between this embodiment and Embodiment 1 is that the drying temperature in step 2 ① is 90-110°C. Others are the same as in the first embodiment.

Embodiment 11: The difference between this embodiment and Embodiment 1 is that the mass ratio of inorganic nanomaterials to absolute ethanol in step 22 is 1: (29-31), and the mass ratio of inorganic nanomaterials to fluorosilane It is 1:(0.2～0.4). Others are the same as in the first embodiment.

Embodiment 12: This embodiment is different from Embodiment 1 in that: the speed of mechanical stirring in step 2 ② is 1000-1200 rpm. Others are the same as in the first embodiment.

Embodiment Thirteen: This embodiment differs from Embodiment 1 in that the power of ultrasonic dispersion in step 2 ② is 500-550 Hz, and the time of ultrasonic dispersion is 1-1.5 h. Others are the same as in the first embodiment.

Embodiment 14: The difference between this embodiment and Embodiment 1 is that the fluorosilane described in Step 2 ③ is Heptadecafluorosilyltrimethoxysilane, Heptadecafluorosilyltriethoxysilane, Thirteen A mixture of one or more of fluorosilyltrimethoxysilane and tridecafluorosilyltriethoxysilane in any ratio. Others are the same as in the first embodiment.

The following examples of the present invention are described in detail, and the following examples are implemented on the premise of the technical solution of the present invention, and detailed implementation schemes and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Embodiment 1: The preparation method of the multifunctional carbonized wood of this embodiment is carried out according to the following steps:

1. Wood softening pretreatment:

Soak basswood wood in distilled water, heat to 100°C, and cook the wood for 2 hours to obtain softened wood;

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

①Add 1g of inorganic nano-silica with a diameter of 100nm to 100ml of toluene, and add 0.6g of polydimethylsiloxane, then ultrasonically disperse at 500Hz for 1h, and then at room temperature at 1000rpm Stir mechanically at a speed of 72 h; then centrifuge at a speed of 6000 rpm for 15 min, and successively wash with dichloromethane and acetone for 3 times, centrifuge at 6000 rpm for 15 min, and dry at 100 °C for 24 h.

②Add the inorganic nanomaterials obtained in step 1 to 30g of absolute ethanol, then drop 0.3g of fluorosilane into it as a hydrophobic substance, then mechanically stir at a speed of 1000rpm for 1h, and then ultrasonically disperse at a power of 500Hz for 1h. Finally, it was stirred at 60°C for 30 minutes;

③Place the wood in the liquid obtained in step 2, pressurize it at 0.8 MPa for 30 minutes, return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials.

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the wood treated in step 2 (diameter section), so that the rough surface of the sandpaper is in contact with the wood, and then place the wood with sandpaper in a hot press, at room temperature and 10MPa. Compress the wood to 25% of its original thickness; then raise the temperature step by step: first raise the temperature to 80°C and keep the pressure for 8h, then continue to raise the temperature to 120°C and keep the pressure for 48h, and then keep the pressure with the hot press at 20°C/h Speed down to room temperature, then return to normal pressure and remove the sandpaper to complete the wood compression and densification treatment, at this time the wood thickness remains at 25% of the original.

4. Wood high temperature carbonization treatment:

Put the wood treated in step 3 in a high-temperature carbonization box, raise the temperature to 150°C at a rate of 5°C/h and keep it warm for 3h, then continue to raise the temperature to 200°C at a rate of 5°C/h and keep it warm for 48h; after that, heat it at 3°C Gradually cool down to 150°C at a speed of 5°C/h and keep it warm for 3 hours. During the heat preservation stage, spray water steam on the wood for 10 minutes every 1 hour; then gradually cool down to 120°C at a speed of 5°C/h and hold it for 3 hours. Spray water steam on the wood for 10 minutes; then gradually cool down to 100°C at a rate of 5°C/h and keep it warm for 3 hours; finally, cool down to room temperature at a rate of 20°C/h, that is, multi-functional carbonized wood.

The microscopic SEM topography of the wood modified by this method shows that the cross-section is compressed and dense, and the surface is more uniformly distributed with nano-silica (as shown in Figure 1), and the radial section (longitudinal section) is also uniformly distributed with nano-silica. Silica particles, the diameter is about 100nm (as shown in Figure 2), the fiber cell wall presents microscopic protrusions, and the entire surface presents a micro-nano structure, which is similar to the microstructure of lotus leaves, and the hydrophobic angle of the wood surface reaches 158° (as shown in Figure 3), that is, modified Wood has a super-hydrophobic function; the static water contact angle after 240-grit sandpaper load 100g weight rubbing 20 times on the radial section of wood is still as high as 156°, the rolling angle is 8°, and the water absorption of wood after continuous immersion in water for 10 days is only 3.2 %; and the tensile strength, compressive strength, impact toughness, hardness, abrasion resistance, elastic modulus and static bending strength (Table 1) of modified wood are respectively improved 6.1 times, 2.58 times, 2.91 times, 3.54 times, 3.1 times, 2.48 times and 2.59 times, anti-corrosion performance increased by 91.4%, the peak heat release rate tested by the cone calorimeter increased by 11% compared with untreated wood, the oxygen index increased by 6.1 compared with untreated wood, flame retardant Performance has improved significantly.

The wood obtained by the treatment method is expected to be used in the fields of building structure materials, sports equipment materials and transportation materials that require high material strength indoors and outdoors.

Embodiment 2: The preparation method of the multifunctional carbonized wood of this embodiment is carried out according to the following steps:

1. Wood softening pretreatment:

Basswood wood was placed in 2wt% NaOH aqueous solution, heated at 90°C for 2 hours to remove most of the hemicellulose, and then washed with distilled water at room temperature until neutral to obtain softened wood.

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

①Add 1g of inorganic nano-iron ferric oxide with a diameter of 30nm to 100ml of toluene, and add 0.6g of polydimethylsiloxane, then ultrasonically disperse at 500Hz for 1h, and then at room temperature with Stir mechanically at a speed of 1000rpm for 72h; then centrifuge at a speed of 6000rpm for 15min, and successively wash with dichloromethane and acetone for 3 times, centrifuge at 6000rpm for 15min, and dry at 100°C for 24h.

②Add the inorganic nanomaterials obtained in step 1 to 30g of absolute ethanol, then drop 0.3g of fluorosilane into it as a hydrophobic substance, then mechanically stir at a speed of 1000rpm for 1h, and then ultrasonically disperse at a power of 500Hz for 1h. Finally, it was stirred at 60°C for 30 minutes;

③Place the wood in the liquid obtained in step 2, pressurize it at 0.8 MPa for 30 minutes, return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials.

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the wood treated in step 2 (diameter section), so that the rough surface of the sandpaper is in contact with the wood, and then place the wood with sandpaper in a hot press, at room temperature and 8MPa conditions. Compress the wood to 24% of its original thickness; then raise the temperature step by step: first raise the temperature to 60°C and keep the pressure for 10h, then continue to raise the temperature to 100°C and keep the pressure for 40h, and then keep the pressure under the heat press at 15°C/h Speed down to room temperature, then return to normal pressure and remove the sandpaper to complete the wood compression and densification treatment, at this time the wood thickness remains at 24% of the original.

4. Wood high temperature carbonization treatment:

Put the wood treated in step three into a high-temperature carbonization box, raise the temperature to 140°C at a rate of 8°C/h and keep it warm for 3h, then continue to raise the temperature to 200°C at a rate of 8°C/h and keep it warm for 40h. After that, gradually cool down to 150°C at a rate of 5°C/h and keep it warm for 2 hours. During the heat preservation stage, spray water steam on the wood for 10 minutes every 1 hour; then gradually cool down to 120°C at a rate of 3°C/h and keep it warm for 2 hours. In the stage, spray water vapor on the wood for 10 minutes every 1 hour; then gradually cool down to 100°C at a rate of 8°C/h and keep it warm for 3 hours; finally, cool down to room temperature at a rate of 15°C/h, that is, multi-functional carbonized wood.

The wood microscopic SEM topography figure after the modification of the inventive method shows that the cross-section is compressed and dense, and the surface is more evenly distributed with nano-ferric oxide (as shown in Figure 4), and also uniformly distributed on the radial section (longitudinal section). Nano ferric oxide particles, the diameter is about 50nm (as shown in Figure 5), the fiber cell wall presents microscopic protrusions, and the entire surface presents a micro-nano structure, which is similar to the microstructure of lotus leaves, and the hydrophobic angle of the wood surface reaches 153° (as shown in Figure 6). That is, the modified wood has super-hydrophobic function; the static water contact angle after 20 times of rubbing with 240-mesh sandpaper and 100g weight weight on the radial section of the wood is still as high as 150°, the rolling angle is 10°, and the water absorption of the wood after continuous immersion in water for 10 days Only up to 4.6%; and the tensile strength, compressive strength, impact toughness, hardness, abrasion resistance, elastic modulus and static bending strength (Table 1) of modified wood are respectively improved 6.22 times, 2.63 times, 2.83 times, 3.41 times, 2.91 times, 2.52 times and 2.64 times, the anti-corrosion performance increased by 90.6%, the peak heat release rate tested by the cone calorimeter increased by 12% compared with untreated wood, and the oxygen index increased by 6.6 compared with untreated wood , The flame retardant performance has been significantly improved; the magnetic strength can reach 52emu/g, and it has high paramagnetism.

The wood obtained by the treatment method is expected to be used in the fields of building structure materials, sports equipment materials and transportation materials that require high material strength indoors and outdoors.

Embodiment 3: The preparation method of the multifunctional carbonized wood of this embodiment is carried out according to the following steps:

1. Wood softening pretreatment:

Spray steam at a temperature of 120°C on the surface of basswood wood for 2 hours to obtain softened wood.

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

①Add 1g of inorganic nano-silver with a diameter of 20nm to 100ml of toluene, and add 0.6g of polydimethylsiloxane, then ultrasonically disperse at 500Hz for 1h, and then at room temperature at a speed of 1000rpm Stir mechanically for 72 hours; then centrifuge at 6000rpm for 15min, wash with dichloromethane and acetone three times successively, centrifuge at 6000rpm for 15min, and dry at 100°C for 24h.

②Add the inorganic nanomaterials obtained in step 1 to 30g of absolute ethanol, then drop 0.3g of fluorosilane into it as a hydrophobic substance, then mechanically stir at a speed of 1000rpm for 1h, and then ultrasonically disperse at a power of 500Hz for 1h. Finally, it was stirred at 60°C for 30 minutes;

③Place the wood in the liquid obtained in step 2, pressurize it at 0.8 MPa for 30 minutes, return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials.

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the wood treated in step 2 (diameter section), so that the rough surface of the sandpaper is in contact with the wood, and then place the wood with sandpaper in a hot press, at room temperature and 10MPa. Compress the wood to 23% of its original thickness; then raise the temperature step by step: first raise the temperature to 70°C and keep the pressure for 9h, then continue to raise the temperature to 120°C and keep the pressure for 44h, and then keep the pressure with the heat press at 17°C/h Speed down to room temperature, then return to normal pressure and remove the sandpaper to complete the wood compression and densification treatment, at this time the wood thickness is compressed to 23% of the original.

4. Wood high temperature carbonization treatment:

Put the wood treated in Step 3 in a high-temperature carbonization box, raise the temperature to 145°C at a rate of 9°C/h and keep it warm for 2.5h, then continue to raise the temperature to 195°C at a rate of 9°C/h and keep it warm for 35h; The speed of ℃/h is gradually lowered to 150 ℃ and kept for 2.5 hours. During the heat preservation stage, water steam is sprayed on the wood for 10 minutes every 1 hour; Spray water vapor on the wood for 10 minutes for 1 hour; then gradually cool down to 100 degrees Celsius at a rate of 9 degrees Celsius/h and keep it warm for 3 hours; finally, cool it down to room temperature at a speed of 18 degrees Celsius/hour, that is, multi-functional carbonized wood.

The microscopic SEM topography figure of wood after the modification of the inventive method shows that the cross-section is compressed and dense, and the surface is distributed with nano-silver (as shown in Figure 7), and nano-silver particles are also uniformly distributed on the radial section (longitudinal section), with a diameter of about 20nm (as shown in Figure 8), and the hydrophobic angle of the wood surface reaches 154° (as shown in Figure 9), that is, the modified wood has a super-hydrophobic function; the static water after the radial section of the wood is rubbed 20 times with 100g weights loaded with 240-mesh sandpaper The contact angle is still as high as 151°, the rolling angle is 9°, and the water absorption of the wood after continuous immersion in water for 10 days is only 4.3%; and the tensile strength, compressive strength, impact toughness, hardness, wear resistance, elastic modulus of the modified wood The weight and static bending strength (Table 1) are respectively increased by 5.61 times, 2.54 times, 2.68 times, 3.25 times, 2.88 times, 2.41 times and 2.52 times compared with untreated wood, and the anti-corrosion performance is improved by 94.8%. Compared with untreated wood, the peak release rate increased by 10%, the oxygen index increased by 5.7, and the flame retardant performance was significantly improved.

The wood obtained by the treatment method is expected to be used in the fields of building structure materials, sports equipment materials and transportation materials that require high material strength indoors and outdoors.

Embodiment 4: The preparation method of the functional carbonized wood of this embodiment is carried out according to the following steps:

1. Wood softening pretreatment:

Basswood wood was placed in 2wt% NaOH aqueous solution, heated at 90°C for 2 hours to remove most of the hemicellulose, and then washed with distilled water at room temperature until neutral to obtain softened wood.

2. Superhydrophobic treatment of softened wood composite inorganic nanomaterials:

①Add 1g of two-dimensional inorganic boron nitride sheet raw materials with a side length of 30μm and a thickness of 5μm into 100ml of toluene, and add 0.6g of polydimethylsiloxane, and then ultrasonically disperse at a power of 500Hz 1h, at this time, boron nitride is dispersed into a two-dimensional sheet material with a length of several microns and a thickness of several to tens of nanometers; then mechanically stir at a speed of 1000rpm at room temperature for 72h; then centrifuge at a speed of 6000rpm for 15min, and After repeated washing with dichloromethane and acetone three times each, centrifuged at 6000rpm for 15min, dried at 100°C for 24h.

②Add the inorganic nanomaterials obtained in step 1 to 30g of absolute ethanol, then drop 0.3g of fluorosilane into it as a hydrophobic substance, then mechanically stir at a speed of 1000rpm for 1h, and then ultrasonically disperse at a power of 500Hz for 1h. Finally, it was stirred at 60°C for 30 minutes;

③Place the wood in the liquid obtained in step 2, pressurize it at 0.8 MPa for 30 minutes, return to normal pressure, take out the wood, and complete the superhydrophobic treatment of softened wood composite inorganic nanomaterials.

3. Timber compression and densification treatment:

Use two pieces of 120-mesh sandpaper to completely cover the upper and lower surfaces of the wood treated in step 2 (diameter section), so that the rough surface of the sandpaper is in contact with the wood, and then place the wood with sandpaper in a hot press, at room temperature and 8MPa conditions. Compress the wood to 24% of its original thickness; then raise the temperature step by step: first raise the temperature to 60°C and keep the pressure for 10h, then continue to raise the temperature to 100°C and keep the pressure for 40h, and then keep the pressure under the heat press at 15°C/h Speed down to room temperature, then return to normal pressure and remove the sandpaper to complete the wood compression and densification treatment, at this time the wood thickness remains at 24% of the original.

4. Wood high temperature carbonization treatment:

Put the wood treated in step 3 in a hot press, and under the pressure of 8MPa in step 3, heat up to 200°C at a rate of 10°C/h and keep it warm for 24h; after that, gradually cool down to 150°C at a rate of 5°C/h And keep it warm for 2 hours. During the heat preservation stage, spray water vapor on the wood for 10 minutes every 1 hour; then gradually cool down to 120°C at a rate of 3°C/h and keep it warm for 2 hours. During the heat preservation stage, spray water steam on the wood for 10 minutes every 1 hour; Gradually cool down to 100°C at a speed of 8°C/h and keep warm for 3 hours; finally, cool down to room temperature at a speed of 15°C/h, that is, multi-functional carbonized wood.

The wood microscopic SEM-EDX topography figure after the method modification of the present invention shows, presents dispersed two-dimensional layered nano-boron nitride (as shown in the dotted line area of Figure 10) in the cell cavity of the radial section surface, and the length size is about 2-3 microns, It shows that boron nitride has been dispersed by ultrasound, the cells on the cross-section are compressed and dense (as shown in Figure 11), and the hydrophobic angle of the wood radial section reaches 152° (as shown in Figure 12), that is, the modified wood has superhydrophobic function, and the corresponding cross-section The boron nitride on the surface of energy spectrum scanning is compressed and confined in the wood (as shown in Figure 13, the place A in the figure refers to the N element, and the place B refers to the B element); the radial section of the wood is loaded with a weight of 100g through 240 mesh sandpaper After 20 times of friction, the static water contact angle is still as high as 150°, and the rolling angle is 10°. The water absorption of wood after 10 days of continuous immersion in water is only 3.6%; and the tensile strength, compressive strength, impact toughness, and hardness of the modified wood , wear resistance, elastic modulus and static bending strength (Table 1) were respectively 5.94 times, 3.12 times, 2.92 times, 4.32 times, 3.37 times, 3.15 times and 2.96 times higher than untreated wood, and the anti-corrosion performance was increased by 90.7%. The peak heat release rate measured by the shape calorimeter is 15% higher than that of untreated wood, the oxygen index is 8.2 higher than that of untreated wood, and the flame retardant performance is significantly improved.

The wood obtained by the treatment method is expected to be used in the fields of building structure materials, sports equipment materials and transportation materials that require high material strength indoors and outdoors.

Table 1 Comparison of mechanical properties of untreated basswood wood and modified wood in different embodiments

Remarks: The mechanical properties are tested according to GB/T 1928-2009, and each value is the average of three measurements.

Claims (5)

1. The preparation method of the multifunctional carbonized wood is characterized by comprising the following steps:

1. wood softening pretreatment:

softening and pretreating the wood by adopting a steaming method, an alkali treatment method or a steaming method;

2. super-hydrophobization treatment of the softened wood composite inorganic nano material:

(1) adding inorganic nano material with the diameter or thickness of 1-100nm into toluene, adding polydimethylsiloxane, then ultrasonically dispersing for 1-1.5 h at 500-550 Hz, and mechanically stirring for 70-74 h at the room temperature of 1000-1200 rpm; centrifuging for 15-30 min, repeatedly washing with dichloromethane and acetone for 3-5 times, centrifuging for 15-30 min, and drying for 22-26 h; wherein the volume ratio of the mass of the inorganic nano material to the toluene is 1g: (90-110) mL, wherein the mass ratio of the inorganic nano material to the polydimethylsiloxane is 1 (0.5-0.7);

the inorganic nano material is nano silicon dioxide, nano titanium dioxide, nano silver, nano zinc oxide, nano ferroferric oxide, nano calcium carbonate, two-dimensional nano clay, two-dimensional nano boron nitride, two-dimensional graphene or two-dimensional graphene oxide;

(2) adding the inorganic nano material treated in the step one into absolute ethyl alcohol, then dropwise adding fluorosilane serving as a hydrophobic substance into the absolute ethyl alcohol, then mechanically stirring for 1-1.5 hours, then performing ultrasonic dispersion, and finally stirring and treating for 30-40 min at the temperature of 60-65 ℃ to obtain liquid;

(3) putting wood into the liquid obtained in the step (2), pressurizing for 30-40 min under the pressure of 0.8-0.9 MPa, recovering to normal pressure, and taking out the wood to finish the super-hydrophobization treatment of the softened wood composite inorganic nano material; the mass ratio of the inorganic nano material to the absolute ethyl alcohol is 1 (29-31), and the mass ratio of the inorganic nano material to the fluorosilane is 1 (0.2-0.4);

3. wood compression and densification treatment:

completely covering the upper and lower surfaces of the longitudinal section of the wood treated in the second step by using two 120-mesh sand papers to enable the rough surface of the sand paper to be in contact with the wood, then placing the wood with the sand paper in a hot press, and compressing the wood to 20-25% of the original thickness under the conditions of room temperature and 5-10 MPa; then, gradually heating: firstly heating to 60-80 ℃ and keeping the pressure for 8-10h, then continuously heating to 100-120 ℃ and keeping the pressure for 24-48h, then cooling the hot press to room temperature at the speed of 20 ℃/h while keeping the pressure, then recovering to normal pressure and removing abrasive paper to finish the compression and densification treatment of the wood;

4. wood high-temperature carbonization:

putting the wood treated in the third step into a high-temperature carbonization box, heating to 130-150 ℃ at the speed of 5-10 ℃/h, preserving heat for 2-3h, then continuously heating to 180-200 ℃ at the speed of 5-10 ℃/h, and preserving heat for 24-48h; or continuously placing the mixture in a hot press, heating to 180-200 ℃ at the speed of 5-10 ℃/h under the pressure of 5-10MPa in the third step, and preserving heat for 24-48h;

then, gradually cooling to 150 ℃ at the speed of 3-5 ℃/h, preserving heat for 2-3h, and spraying steam on the wood every 1h in the heat preservation stage for 10min; then, gradually cooling to 120 ℃ at the speed of 3-5 ℃/h, preserving heat for 2-3h, and spraying water vapor on the wood every 1h in the heat preservation stage for 10min; then the temperature is gradually reduced to 100 ℃ at the speed of 5-10 ℃/h and is kept for 2-3h; and finally, cooling to room temperature at the speed of 10-20 ℃/h to obtain the multifunctional carbonized wood.

2. The method for preparing a multifunctional carbonized wood as described in claim 1, wherein the steaming process comprises soaking wood in distilled water, heating to 100 deg.C, and steaming for 2 hr to obtain softened wood.

3. The method for preparing multifunctional carbonized wood according to claim 1, wherein the alkali treatment process comprises placing wood in 2% by mass concentration NaOH aqueous solution, heating at 90 ℃ for 2h to remove most of hemicellulose, and washing with distilled water at room temperature to neutrality to obtain softened wood.

4. The method for preparing the multifunctional carbonized wood according to claim 1, wherein the steaming method is to steam the surface of the wood with water vapor at a temperature of 120 ℃ for 2 hours to obtain softened wood.

5. The method for preparing a multifunctional carbonized wood according to claim 1, characterized in that the fluorosilane in the step two (3) is one or a mixture of several of heptadecafluorosilyltrimethoxysilane, heptadecafluorosilyltriethoxysilane, tridecafluorosilyltrimethoxysilane and tridecafluorosilyltriethoxysilane in any ratio.

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