CN111098372B

CN111098372B - Preparation method of wood-based graphene conductive composite material

Info

Publication number: CN111098372B
Application number: CN201811265612.8A
Authority: CN
Inventors: 王喜明; 王丽; 张羽; 王哲; 张晓涛; 李丽丽; 王磊; 黄贺东
Original assignee: Inner Mongolia Agricultural University; Inner Mongolia University of Science and Technology
Current assignee: Inner Mongolia Agricultural University; Inner Mongolia University of Science and Technology
Priority date: 2018-10-29
Filing date: 2018-10-29
Publication date: 2022-01-28
Anticipated expiration: 2038-10-29
Also published as: CN111098372A

Abstract

The invention provides a preparation method of a wood-based graphene conductive composite material. The method comprises the following steps: s1, circularly boiling, freezing, steaming, freezing and boiling the wood by using deionized water until the residual liquid after the water boiling is clear and transparent, and then drying; s2, soaking the graphene oxide dispersion liquid into the dried wood under a pulse type vacuum condition; s3, drying the impregnated wood in a segmented manner to obtain a wood-based graphene oxide composite material; s4, carrying out thermal reduction reaction on the wood-based graphene oxide composite material in a protective gas atmosphere to obtain the wood-based graphene conductive composite material. The method adopts a water circulation wood pretreatment mode to achieve the improvement of the porosity of the wood, and adopts a pulse type vacuum impregnation method to add the graphene oxide dispersion liquid into the wood body; and finally, carrying out green thermal reduction reaction to reduce the graphene oxide into graphene.

Description

Preparation method of wood-based graphene conductive composite material

Technical Field

The invention belongs to the technical field of wood functionalization treatment, and particularly relates to a preparation method of a wood-based graphene conductive composite material.

Background

Electromagnetic radiation brought by the rapidly developing electronic industry has the defects of information leakage, serious interference on the operation of surrounding electronic equipment, harm to human health and the like, and becomes a big nuisance after being polluted by noise, atmosphere, water and solid waste. The metal resources with natural electromagnetic shielding effect are increasingly exhausted, the environmental problems caused by the smelting process are increasingly serious, the processing is difficult, the weight of the finished product is heavy, secondary interference is caused by the strong reflection effect of electromagnetic waves, and the like, so that the applicability of the electromagnetic shielding material is limited. The conductive polymer, the carbon material and the surfactant are easy to agglomerate and need to be processed and manufactured by other matrix materials. Therefore, the electromagnetic shielding material with wide absorption frequency band, good physical and mechanical properties, environmental protection and no pollution is explored, the pressure of non-renewable resources is relieved, the increasingly serious environmental problems are relieved, and the development of novel environment-friendly renewable electromagnetic shielding composite materials is urgent.

The wood is a green insulating material with a micron-to-nano-scale multi-scale structure, has the advantages of reproducibility, sound insulation, temperature and humidity regulation, decorative performance and the like, the natural framework form of the wood can be used as a matrix template of other materials, the surface of a porous channel is rich in a large number of active sites (carbon free radicals C) and groups (free hydroxyl-OH, carboxyl-COOH and the like), and a series of physical and chemical reactions can be carried out. The material can be developed into a green electromagnetic shielding material with a very prospect by combining with conductive materials (conductive polymers such as polypyrrole (PPy), Polyaniline (PANI), carbon materials such as Carbon Nano Tube (CNTs), graphene (Gr), metal materials such as silver, gold, nickel, copper and oxides thereof, tin oxide, lead oxide, titanium dioxide and the like, surfactants such as chlorinated-1-allyl-3-methylimidazolium chloride and the like), and meanwhile, the performances such as hygroscopicity, anisotropy, easy decay and the like of wood bodies are obviously improved, the high performance and functionalization of wood are realized, and the added value of the wood is improved.

The method mainly comprises the following steps that firstly, after a conductive filler is compounded with a wood unit, the conductive filler is compounded with a wood single plate in an interlayer mode through hot pressing to form the wood-based conductive composite material in a sandwich structure; directly coating a conductive material on the surface of the wood to achieve the effect of wood conductivity; and thirdly, compounding the conductive component with cellulose to prepare the flexible electrode with good conductive performance.

The technical scheme disclosed in CN 99122281.4 is to mix carbon fibers and urea-formaldehyde resin or phenol-formaldehyde resin uniformly, apply the mixture on the surface of wood units, sequentially perform assembly molding, form alternate laminated structures with multiple layers of wood units, and finally form a plate with conductive ability by hot pressing.

The technical scheme disclosed in CN 201710716619.6 is that nanometer magnesium oxide coated with oxidation buttons and glass fiber are used as fillers, modified bean gum and carbon powder modified silica sol are used as glue shaving agent, and 3 layers of eucalyptus plywood are prepared, wherein the 3 layers of eucalyptus plywood are formed by bonding 3 eucalyptus veneers and then hot-pressing.

The technical scheme disclosed in CN 201510434482.6 is to perform chemical plating treatment on nickel sulfate, sodium hypophosphite, surfactant and other components on the surface of wood for many times to obtain a corrosion-resistant high-conductivity wood electromagnetic shielding material, which can be used in the fields of electronics, aviation, medicine and the like.

The heating chip prepared by fusing the nano carbon fiber and the wood fiber in the technical scheme disclosed by CN201711165528.4 can be applied to the field of heating floors, and has the advantages of comfort, sanitation, health care, space saving, room beautification, high efficiency, energy saving and good geothermal stability.

The technical scheme disclosed in CN 201310674912.2 is to compound wood flakes with conductive polymer pyrrole and polyaniline to prepare a super capacitor, which has good flexibility and cycling stability.

The technical scheme disclosed in CN201510249246.7 is that the conductive material prepared by compounding nano silver and cellulose has the reproducibility of cellulose and new performances of conductivity, antibiosis, ultraviolet resistance, antistatic property, etc., and the method is simple to operate, low in cost and suitable for industrial production.

Traditional conducting molecule aniline was published by the world health organization international cancer research institute as a carcinogen in 2017, 10 months and 27 days; pyrrole vapor can cause anesthesia of people, can cause continuous increase of body temperature, is inflammable and has irritation; the metal material is a non-renewable resource and easily causes environmental pollution in the preparation process; carbon materials such as graphene, carbon nanotubes, carbon fibers, and the like have poor dispersibility and are difficult to be directly compounded with other substances.

Based on the above, the method has become a research hotspot by uniformly and organically combining the graphene oxide, which is a graphene derivative, with wood, and then reducing the graphene oxide to obtain the wood-based graphene conductive composite material. However, most of the reduction steps in the prior art are carried out by using a reducing agent, and the reducing agent is remained, so that the dimensional stability of the wood is easily deteriorated, and the prior art is complex to operate, high in cost and not green enough.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method of a wood-based graphene conductive composite material, which adopts graphene oxide, which is a graphene derivative, to be uniformly and organically combined with wood, and then releases graphene with conductive performance inside a wood body by a green thermal reduction means.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of a wood-based graphene conductive composite material, which comprises the following steps:

s1, circularly boiling, freezing, steaming, freezing and boiling the wood by using deionized water until the residual liquid after the water boiling is clear and transparent, and then drying;

s2, soaking the graphene oxide dispersion liquid into the dried wood under a pulse type vacuum condition;

s3, drying the impregnated wood in a segmented manner to obtain a wood-based graphene oxide composite material;

s4, carrying out thermal reduction reaction on the wood-based graphene oxide composite material in a protective gas atmosphere to obtain the wood-based graphene conductive composite material.

Preferably, the concentration of the graphene oxide dispersion liquid is 1-5 mg/mL;

preferably, the addition amount of the graphene oxide dispersion liquid is 0.1-3% by mass of the dried wood.

Preferably, the shielding gas is nitrogen, helium or argon.

Preferably, the impregnated wood is dried in stages in S3 to a moisture content of less than 10% and to prevent cracking. In the method, S3 is used for drying the impregnated wood in sections so that the water content is required to be kept below 10%, a large amount of free water in the wood body is removed, and the wood is not cracked, thereby facilitating the subsequent steps.

In the above method, the purpose of S1 is to remove the fillers in the pores of the wood body, so as to open the pores of the wood body, and facilitate the graphene oxide to enter the interior of the wood body in a lamellar structure. The pore structure and cell walls of the wood can be continuously shrunk and swelled through multiple different treatment steps, and the pouring filler and insoluble organic matters can be fully dissolved out to a greater extent, so that the subsequent impregnation process is facilitated.

Preferably, the temperature of the deionized water in S1 is 80-100 ℃, more preferably 90 ℃;

preferably, the cooking treatment is carried out for 2 h;

preferably, the freezing is performed for 2 to 7 days, more preferably for 2 to 3 days;

preferably, the steaming is performed for 2 h;

repeating the above process for 3 times until the residual liquid after water boiling treatment is clear and transparent;

preferably, the drying process in S1 is performed in the following manner: drying at 103 deg.C for 30 min, at 80 deg.C for 4h, and at 60 deg.C for 2h under 0.2MPa vacuum.

Preferably, the pulsed vacuum condition in S2 is vacuum impregnation for 10 minutes, atmospheric impregnation for 3 minutes, and vacuum impregnation for 5 minutes; wherein the vacuum degree of the vacuum is 0.5-0.8 MPa.

Preferably, the step drying in S3 is performed sequentially in the following manner: drying in vacuum drying oven at 45-60 deg.C for 8-12 hr, preferably at 51 deg.C for 10 hr; drying in forced air drying oven at 45-60 deg.C for 5-7 hr, preferably at 51 deg.C for 6 hr; drying in vacuum drying oven at vacuum degree of 0.02-0.06MPa at 45-60 deg.C for 1-3 hr, preferably at 51 deg.C for 1 hr; drying with air at 45-60 deg.C for 8-12 hr, preferably at 53 deg.C for 10 hr.

S3 adopts this segmentation drying process mode can be under the prerequisite of guaranteeing that timber does not split, the drying of the biggest, evenly carries out timber. Graphene oxide can produce a large amount of black flaky substances above 60 ℃, seriously influences subsequent reduction treatment means, and finally influences the electric conduction effect, can improve the dispersion degree of graphene oxide in the wood body through this segmentation drying treatment, and the large crack that avoids producing among the wood drying process leads to graphene oxide to take place a large amount of deposits, influences final electric conduction effect.

Preferably, the temperature of the thermal reduction reaction in S4 is 170-230 ℃, and the reaction time is 1-5 h. More preferably, the thermal reduction reaction is to place the composite material in a muffle furnace for treatment, the temperature is raised for half an hour, the temperature is kept at 170-230 ℃ for 1-5 hours, and then the temperature is lowered for half an hour. The thermal reduction treatment removes oxygen atoms on the edge and the upper part of the graphene oxide ring structure in the wooden organism to the maximum extent in the form of water vapor and carbon dioxide to obtain the graphene with the conductive performance. The invention adopts the green and environment-friendly physical thermal reduction method, thereby not only saving the cost of the reducing agent and simplifying the operation process, but also completing the drying treatment of the wood-based composite material, saving the cost of wood drying, improving the crystallinity of the wood and reducing the moisture absorption and deformation performance of the wood. And the organic components in the composite material are obviously reduced, and the corrosion resistance, the strength and the toughness of the wood are improved.

Preferably, the wood is pinus sylvestris, larch, poplar, eucalyptus, or cedar.

The graphene oxide has optical properties similar to those of graphene and a large specific surface area, is used as an intermediate for converting the graphene, is compounded with wood by utilizing the advantages of good hydrophilicity and biocompatibility, and then is reduced to release the electrical and thermal properties of the graphene to the maximum extent, so that the comprehensive performance of the composite material is improved.

The invention also provides a wood-based graphene conductive composite material prepared by the preparation method.

In order to ensure that the graphene oxide lamellar structure smoothly enters the wood body, the method provided by the invention adopts a water circulation wood pretreatment mode to achieve the aim of improving the porosity of the wood on the premise of reducing the strength loss of the wood as much as possible. And adding the graphene oxide dispersion liquid into the wood body by adopting a pulse type vacuum impregnation method, so as to ensure that the graphene oxide is uniformly dispersed in the wood body as far as possible and is organically combined with active groups such as hydroxyl and carboxyl in the wood body. And finally, moving the composite material into a muffle furnace, reasonably controlling the temperature and time on the premise of not damaging the wood, and reducing the graphene oxide in the wood body to the maximum extent to obtain the composite material which has conductivity, weakens the moisture absorption and easy deformation of the wood and improves the mechanical property of the wood.

Compared with the prior art, the technical scheme of the invention has the following advantages: (1) the processing method of the invention endows the wood with the semiconductor conductive capability, effectively improves the antistatic and electromagnetic shielding capabilities of the wood, and enlarges the application field of the wood. (2) The thermal reduction part is green and pollution-free, no additional reducing agent is needed, the cost is reduced, and the residue problem is avoided. (3) The treatment method is simple and feasible, and has low requirement on equipment.

Drawings

FIG. 1 is a radial section of the wood extracted by pretreatment in the examples.

Fig. 2 is a radial sectional view of the wood-based-graphene conductive composite prepared in example 1.

Fig. 3 is a spectrum of the carbonized poplar in example 1.

Fig. 4 is a spectrum diagram of graphene oxide in example 1.

Fig. 5 is an energy spectrum of the wood-based graphene conductive composite in example 1.

FIG. 6 is an infrared spectrum of the pretreated carbonized wood material in the example.

Fig. 7 is an infrared spectrum of graphene oxide in the example.

Fig. 8 is an infrared spectrum of the wood-based graphene conductive composite (test piece) in example 1.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Example 1

The embodiment provides a wood-based graphene conductive composite material, which is prepared by the following steps:

(1) the wood pretreatment extraction process comprises the following steps: boiling wood (poplar materials) for 2 hours by using deionized water at 95 ℃, freezing for 2 days, performing hot steam treatment on the composite material for 2 hours, freezing for 2 days, boiling by using the deionized water, circulating the processes for many times until the color of the liquid boiled by the deionized water is clear and transparent, and finally drying (drying at 103 ℃ for 30 minutes, drying at 80 ℃ for 4 hours, and drying at 60 ℃ for 2 hours under the vacuum of 0.2 MPa).

(2) And (3) soaking the graphene oxide dispersion liquid with the concentration of 3mg/mL in a vacuum condition, putting the graphene oxide dispersion liquid into the fast growing wood body pretreated in the step (1), and performing vacuum impregnation for 10 minutes and normal pressure for 3 minutes and vacuum impregnation for 5 minutes by adopting a pulse type vacuum method with the vacuum degree of 0.8MPa to obtain the composite material.

(3) And (3) performing segmented drying on the wood-based graphene oxide composite material (the step of drying in a vacuum drying oven at 51 ℃ for 10 hours, the step of drying in an air blast drying oven at 51 ℃ for 6 hours, the step of drying in the vacuum drying oven at 0.02-0.06, the step of drying at 51 ℃ for 1 hour, and the step of drying in the air blast drying oven at 53 ℃ for 10 hours) to remove a large amount of free water in a wood body, so that the water content of the wood is kept below 10%, and the wood is not cracked, thereby obtaining the wood-based graphene oxide composite material.

(4) And (4) transferring the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 190 ℃ for 2 hours, and cooling for half an hour to reduce the graphene oxide into the reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

FIG. 1 is a radial sectional view of pure wood used in this example. Fig. 2 is a radial sectional view of the wood-based graphene conductive composite material prepared in this embodiment. The SEM images of figures 1 and 2 show that the grain hole structure of pure wood on the wall of the wood conduit under an electron microscope is clear and complete, the periphery is neat and clean, after graphene oxide is added and heat treatment is carried out, the typical folded lamellar structure of graphene on the wall of the conduit can be seen, and the graphene materials are distributed in the wood conduit in a large amount and are tightly adhered to the wall of the wood conduit in the form of a film or a large sheet layer, and the grain hole structure is coated in a large area without warping, which indicates that the combination degree of the graphene and the wood is good. And the graphene material exists in the duct tissue in the wood, so that a 'conductive path' along the direction of the duct can be integrally formed, the conductive possibility of the wood is structurally realized, and the subsequent resistance test proves that the graphene is really reduced in the poplar body and is uniformly distributed in the wood body.

Fig. 3 is an energy spectrum diagram of the poplar material after pretreatment and carbonization, the carbon-oxygen ratio is 3.5, fig. 4 is an energy spectrum diagram of graphene oxide, the carbon-oxygen ratio is 0.47, fig. 5 is an energy spectrum diagram of the composite material, and the carbon-oxygen ratio is 6. Energy spectrum analysis shows that the oxygen content in the composite material is obviously lower than that of poplar materials and graphene oxide after reduction, which indicates that the graphene oxide in a wood body is fully reduced to generate graphene after thermal reduction treatment, and the graphene can endow wood with certain conductivity.

FIGS. 6-8 show examples of pretreated carbonized woodInfrared spectrum comparison graphs of the material, the graphene oxide and the wood-based-graphene conductive composite material (test piece). Compared with carbonized wood material and graphene oxide, the absorption peak position of the test piece is 3436cm^-1The graphene oxide is in an associated state-OH, the peak strength is obviously higher than that of a material, and the result shows that hydroxyl in the graphene oxide structure is combined with hydroxyl in wood to form a hydrogen bond, so that the combination degree of the hydroxyl and the wood is fully improved, the crystallinity of the wood is improved, and the conductivity of the wood is improved to a certain degree. Peak position 2900cm^-1The peak is C-H stretching vibration on aliphatic hydrocarbon, is a typical characteristic peak of cellulose, is weakened and moves to the left to a certain extent, and is caused by the structural aromatic hydrocarbon C-H stretching vibration enhancement effect after graphene is compounded with wood. 1741cm^-1The peak is the stretching vibration of C ═ O of hemicellulose, and is obviously weakened, probably caused by the esterification reaction of functional group-OH in graphene oxide and the functional group-OH. 1630. 1509, 1460cm^-1The peak is obviously enhanced and is caused by the stretching vibration of the C ═ C benzene ring on the graphene structure, 669.16cm^-1The bending vibration of the benzene ring is obviously enhanced, and is caused by the benzene ring structure of the graphene. 1373cm^-1For C-H bending vibration on the Lignin guaiacum units, 1257cm^-1The 2 absorption peaks are weakened due to stretching vibration of C-O-C phenolic ether bonds of lignin, and the absorption peak representing ether bond C-O-C stretching vibration on cellulose and hemicellulose at 1140 is also slightly reduced due to the fact that after graphene and wood are fully compounded, the proportion of benzene rings in the structure of the composite is increased, and methyl groups in the wood are covered to a certain degree. The change of the peak positions shows that the graphene oxide uniformly distributed in the wood body is fully reduced by the oxygen-insulating thermal reduction treatment, so that oxygen atoms on benzene rings of the graphene oxide are greatly reduced, and the effective carbon atom ratio is obviously increased. In conclusion, it can be proved that after the graphene oxide enters the wood body, the graphene oxide can generate a large amount of reducing graphene oxide through oxygen-isolating thermal reduction treatment, so that the conductive performance is released, the wood is endowed with good conductive performance, and the application field of the wood is further expanded.

Example 2

(1) the wood pretreatment extraction process comprises the following steps: boiling wood (poplar materials) for 2 hours by using deionized water at 95 ℃, then carrying out water saturation treatment for a week and freezing for 2 days, then carrying out hot steam treatment for 2 hours on the composite material, freezing for 2 days, boiling by using the deionized water, circulating the processes for many times until the color of the liquid boiled by the deionized water is clear and transparent, and finally drying (drying at 103 ℃ for 30 minutes, drying at 80 ℃ for 4 hours, and drying at 60 ℃ for 2 hours under the vacuum of 0.2 MPa).

(4) And (4) moving the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 210 ℃ for 2 hours, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

Example 3

(4) And (4) moving the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 230 ℃ for 2 hours, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

Example 4

(2) And (2) soaking the graphene oxide dispersion liquid with the concentration of 1mg/mL in a vacuum condition, putting the graphene oxide dispersion liquid into the fast growing wood body pretreated in the step (1), and performing vacuum impregnation for 10 minutes and normal pressure for 3 minutes and vacuum impregnation for 5 minutes by adopting a pulse type vacuum method with the vacuum degree of 0.8MPa to obtain the composite material.

(4) And (4) transferring the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 210 ℃ for 2 hours, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

Example 5

Example 6

(2) And (2) soaking the graphene oxide dispersion liquid with the concentration of 5mg/mL in a vacuum condition, putting the graphene oxide dispersion liquid into the fast growing wood body pretreated in the step (1), and performing vacuum impregnation for 10 minutes and normal pressure for 3 minutes and vacuum impregnation for 5 minutes by adopting a pulse type vacuum method with the vacuum degree of 0.8MPa to obtain the composite material.

Example 7

(4) And (4) moving the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 210 ℃ for 1 hour, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

Example 8

(4) And (4) moving the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 210 ℃ for 3 hours, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

Example 9

(4) And (4) moving the composite material obtained in the step (3) to a muffle furnace, heating for half an hour, keeping the temperature at 210 ℃ for 5 hours, and cooling for half an hour to reduce the graphene oxide into reductive graphene oxide to the maximum extent in the wood body, so as to obtain the wood-based graphene conductive composite material.

The wood-based graphene conductive composites prepared in examples 1 to 9 and poplar materials were tested for conductivity, and the results are shown in table 1.

Table 1 conductivity of wood-based graphene conductive composites and poplar materials of examples 1-9

Poplar material	Example 1	Example 2	Example 3	Example 4
					Resistivity, Ω · cm	5.973×10¹⁴	5.464×10⁵	1.274×10³	1.167×10²	1.644×10⁶
Example 5	Example 6	Example 7	Example 8	Example 9
					Resistivity, Ω · cm	7.031×10¹¹	3.250×10²	1.083×10⁵	4.239×10²	6.123×10³

As can be seen from the data in table 1: the volume resistivity of the poplar material is 5.973 multiplied by 10 before any treatment¹⁴Ω · cm, is an insulator. After addition of graphene oxide (example 5), there was a slight increase in conductivity, but still poor. After thermal reduction treatment, the conductivity can reach 3.250 multiplied by 10 best²Omega cm, has better conductive performance, obviously improves the electromagnetic shielding capability of poplar, expands the application field and range of wood, and has certain research value.

According to the invention, through carrying out extraction pretreatment on wood, impregnating graphene oxide by a pulse vacuum method, chemically bonding the graphene oxide with the wood, and then carrying out thermal reduction treatment on the composite material, the graphene oxide is fully reduced in a wood body to generate conductive reductive graphene oxide, so that the wood is endowed with uniform conductive capability, the crystallinity of the wood is obviously improved, free hydroxyl groups are fixed in a rivet mode, and the moisture absorption and water absorption properties of the wood are obviously weakened. The thermal reduction treatment is green and environment-friendly, the production cost is reduced, and the residue problem of the reducing agent is avoided.

Claims

1. A preparation method of a wood-based graphene conductive composite material is characterized by comprising the following steps:

the wood is poplar; the temperature of the deionized water is 80-100 ℃; the boiling is carried out for 2h, the freezing is carried out for 2-7 days, and the steaming is carried out for 2 h; the drying treatment is carried out in the following manner: drying at 103 deg.C for 30 min, at 80 deg.C for 4h, and at 60 deg.C under 0.2MPa for 2 h;

the pulse vacuum condition comprises vacuum impregnation for 10 minutes, normal pressure impregnation for 3 minutes and vacuum impregnation for 5 minutes; wherein the vacuum degree of the vacuum is 0.5-0.8 MPa;

the sectional drying is carried out in sequence according to the following modes:

drying in a vacuum drying oven at 45-60 deg.C for 8-12 h;

drying in a forced air drying oven at 45-60 deg.C for 5-7 hr;

drying in a vacuum drying oven at 45-60 deg.C for 1-3h under vacuum condition of 0.02-0.06 MPa;

drying with air blast at 45-60 deg.C for 8-12 hr;

s4, carrying out thermal reduction reaction on the wood-based graphene oxide composite material in a protective gas atmosphere to obtain the wood-based graphene conductive composite material; the temperature of the thermal reduction reaction is 170-230 ℃, the reaction time is 1-5h,

the protective gas is nitrogen, helium or argon.

2. The method for preparing the wood-based graphene conductive composite material according to claim 1, wherein the concentration of the graphene oxide dispersion liquid is 1-5 mg/mL.

3. The method for preparing the wood-based graphene conductive composite material according to claim 2, wherein the graphene oxide dispersion liquid is added in an amount of 0.1-3% by mass of the dried wood.

4. The method for preparing the wood-based graphene conductive composite material according to claim 1, wherein the impregnated wood is dried in a segmented manner in S3 to a moisture content of less than 10% and not cracked.

5. The preparation method of the wood-based graphene conductive composite material as claimed in claim 1, wherein the thermal reduction reaction is to place the wood-based graphene oxide composite material in a muffle furnace for processing, the temperature is raised for half an hour, the temperature is maintained at 170-230 ℃ for 1-5h, and then the temperature is lowered for half an hour.

6. The wood-based-graphene conductive composite material prepared by the method of any one of claims 1 to 5.