NANOMATERIAL-BIOMASS FIBER COMPOSITE AND PREPARATION METHOD THEREOF

Abstract

A nanomaterial-biomass fiber composite and preparation method thereof. The biomass fibers are cut or sliced, and then dried. The dried biomass fibers are mixed with a nanomaterial and conveyed to the preheating cylinder of a defibrator for cooking treatment. The cooked mixture is pushed between the grinding discs of the defibrator for hot grinding treatment. The resulting material is then hot pressed to obtain the nanomaterial-biomass fiber composite material. The preparation method benefits from simple operation, low cost, low energy consumption, suitability for industrialized production, and wide application prospect in the field of production of binderless fiberboard.

Claims

1. A nanomaterial-biomass fiber composite, which is prepared by: cutting or slicing biomass fibers and drying; mixing dried biomass fibers with a nanomaterial, and conveying them to a preheating cylinder of a defibrator for cooking treatment; and pushing a cooked mixture between grinding discs of the defibrator for hot grinding treatment, and then hot pressing a resulting material to obtain the nanomaterial-biomass fiber composite.

2. The nanomaterial-biomass fiber composite according to claim 1, wherein the biomass fiber is selected from at least one of wood, bamboo, processing residues, crop waste, and Gramineae weed.

3. The nanomaterial-biomass fiber composite according to claim 2, wherein the crop waste is at least one of rice straw, wheat straw, corn straw, cotton straw and bagasse; and wherein the Gramineae weed is at least one of reed and miscanthus.

4. The nanomaterial-biomass fiber composite according to claim 1, wherein the nanomaterial is selected from at least one of nano-TiO.sub.2, nano-ZnO, nano-Ag, nano-SiO.sub.2, nano-Fe.sub.3O.sub.4, nano-CaCO.sub.3, nano-Al.sub.2O.sub.3, nano-Mg(OH).sub.2, nano-Al(OH).sub.3, nano-CeO.sub.2, nano-MnO.sub.2, nano-cellulose, nano-graphene, nano-carbon fiber and carbon nanotube.

5. The nanomaterial-biomass fiber composite according to claim 1, wherein a weight of the nanomaterial accounts for 0.01%-20% of ae absolute dry weight of the biomass fibers.

6. The nanomaterial-biomass fiber composite according to claim 1, wherein the nanomaterial-biomass fiber composite is free of adhesive.

7. The nanomaterial-biomass fiber composite according to claim 1, wherein the nanomaterial-biomass fiber composite is free of auxiliary agent.

8. A method of preparing a nanomaterial-biomass fiber composite, comprising steps of: cutting or slicing biomass fibers, and then drying the biomass fibers so that a moisture content of the biomass fibers is less than 10%; mixing dried biomass fibers with a nanomaterial to obtain a mixture, and conveying the mixture to a preheating cylinder of a defibrator for cooking treatment; pushing a cooked mixture between grinding discs of the defibrator for hot grinding treatment to obtain a slurry of the nanomaterial-biomass fiber composite; and filtering a hot-grinded slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite.

9. The preparation method according to claim 8, wherein in the mixing step, a cooking temperature is 100-250 C., a steam pressure is 0.01-10 Mpa, and a cooking time is 1-60 minutes.

10. The preparation method according to claim 8, wherein in the pushing step, a rotating speed for the hot grinding treatment is 500-3000 rpm, and a time for the hot grinding treatment is 1-24 hours.

11. The preparation method according to claim 8, wherein in the filtering step, a hot pressing temperature is 100-220 C., a hot pressing time is 10-300 minutes, and a hot pressing pressure is 1-8 MPa.

12. The method according to claim 8, wherein the step of mixing the dried biomass fibers with the nanomaterial is carried out by directly adding the nanomaterial to the dried biomass fibers and mixing them.

13. The preparation method according to claim 8, wherein the step of mixing the dried biomass fibers with the nanomaterial is carried out by conveying the nanomaterial to a discharge valve of the defibrator via a pipe and injecting the nanomaterial into the discharge valve via a nozzle so as to mix the nanomaterial with the dried biomass fibers.

14. The preparation method according to claim 8, wherein the step of mixing the dried biomass fibers with the nanomaterial is carried out by conveying the nanomaterial onto a wood chip at a feed inlet of a grinding chamber of the defibrator via a delivery pump, and conveying the nanomaterial into a continuous discharge valve of the grinding chamber of the defibrator via a gear pump so as to mix the nanomaterial with the dried biomass fibers.

15. The preparation method according to claim 8, further comprising a step of adjusting a pH value of the cooked mixture to 1-14 before carrying out the hot grinding treatment in the pushing step.

16. A nanomaterial-biomass fiber composite, which is prepared by a method comprising steps of: cutting or slicing biomass fibers, and then drying the biomass fibers so that a moisture content of the biomass fibers is less than 10%; mixing dried biomass fibers with a nanomaterial to obtain a mixture, and conveying the mixture to a preheating cylinder of a defibrator for cooking treatment; pushing a cooked mixture between grinding discs of the defibrator for hot grinding treatment to obtain a slurry of the nanomaterial-biomass fiber composite; and filtering a hot-grinded slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite.

17. The nanomaterial-biomass fiber composite according to claim 16, wherein in the mixing step, a cooking temperature is 100-250 C., a steam pressure is 0.01-10 Mpa, and a cooking time is 1-60 minutes.

18. The nanomaterial-biomass fiber composite according to claim 16, wherein in the pushing step, a rotating speed for the hot grinding treatment is 500-3000 rpm, and a time for the hot grinding treatment is 1-24 hours.

19. The nanomaterial-biomass fiber composite according to claim 16, wherein in the filtering step, a hot pressing temperature is 100-220 C., a hot pressing time is 10-300 minutes, and a hot pressing pressure is 1-8 MPa.

20. The nanomaterial-biomass fiber composite according to claim 16, further comprising a step of adjusting a pH value of the cooked mixture to 1-14 before carrying out the hot grinding treatment in the pushing step.

Description

BRIEF DESCRIPTION OF FIGURES

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly described below. In all the figures, similar elements or parts are generally identified by similar reference numerals. In the drawings, various elements or parts are not necessarily drawn to actual scale.

[0029] FIG. 1 shows a flow chart of a preparation method of a nanomaterial-biomass fiber composite the examples of the present invention;

[0030] FIG. 2 is a scanning electron micrograph of a TiO.sub.2 nanomaterial-biomass fiber composite prepared in Example 1 of the present invention;

[0031] FIG. 3 is a scanning electron micrograph of a ZnO nanomaterial-biomass fiber composite prepared in Example 2 of the present invention;

[0032] FIG. 4 is a scanning electron micrograph of a Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite prepared in Example 5 of the present invention;

[0033] FIG. 5 is a scanning electron micrograph of a CaCO.sub.3 nanomaterial-biomass fiber composite prepared in Example 6 of the present invention;

[0034] FIG. 6 is a hysteresis loop of a Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite prepared in Example 5 of the present invention;

[0035] FIG. 7 is a graph showing the changing of the reflection loss frequency of the ZnO nanomaterial-biomass fiber composite prepared in Example 2 of the present invention; and

[0036] FIGS. 8A and 8B show a comparison of the mechanical properties between the binderless fiberboard prepared in Example 11 of the present invention and a conventional binderless fiberboard.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The examples of the inventive technical solution will be described in detail below with reference to the accompanying drawings. The following examples are merely used for more clearly explaining the technical solution of the present invention, and therefore, they are only examples, and cannot be used to limit the protection scope of the present invention.

[0038] It should be noted that, the technical terms or scientific terms used in this application shall be understood in the ordinary sense as understood by a person skilled in the art to which the present invention belongs unless otherwise specified.

[0039] The preparation method of a nanomaterial-biomass fiber composite provided by the present invention utilizes a hot grinding method to uniformly attach nanomaterials to biomass fibers, so as to prepare the nanomaterial-biomass fiber composite.

[0040] FIG. 1 shows a flow chart of a preparation method of a nanomaterial-biomass fiber composite provided by the present invention. Referring to FIG. 1, the preparation method comprises the steps of:

[0041] Step S1: cutting or slicing the biomass fiber, and then drying to the extent that the moisture content of the biomass fibers is less than 10%. As described herein, the biomass fiber includes wood, bamboo and their corresponding processing residues, crop waste, and Gramineae weed, the crop waste comprises rice straw, wheat straw, corn straw, cotton straw and bagasse, and the Gramineae weed comprises reed and/or miscanthus.

[0042] Step S2: mixing the dried biomass fiber with a nanomaterial to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment. Wherein, the cooking temperature in the preheating cylinder may be 100-250 C., the steam pressure may be 0.01-10 Mpa, the cooking time may be 1-60 min, and the nanometer material may include nano-TiO.sub.2, nano-ZnO, nano-Ag, nano-SiO.sub.2, nano-Fe.sub.3O.sub.4, nano-CaCO.sub.3, nano-Al.sub.2O.sub.3, nano-Mg(OH).sub.2, nano-Al(OH).sub.3, nano-CeO.sub.2, nano-MnO.sub.2, nano-cellulose, nano-graphene, nano-carbon fiber and carbon nanotube. The nanomaterial may account for 0.01%-20% of the absolute dry weight of the biomass fiber.

[0043] Step S3: pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment to obtain a slurry of nanomaterial-biomass fiber composite material.

[0044] Step S4: filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite material. Preferably, the hot pressing temperature is 100-220 C., the hot pressing time is 10-300 min, and the hot pressing pressure is 1-8 MPa. In an embodiment of the present invention, the size of the board blank is 20 cm20 cm6 cm.

[0045] According to the preparation method of the present invention, mixing the dried biomass fiber with the nanomaterial is carried out by directly adding the nanomaterial to the dried biomass fiber and mixing them.

[0046] According to the preparation method of the present invention, mixing the dried biomass fiber with the nanomaterial is carried out by conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber.

[0047] According to the preparation method of the present invention, mixing the dried biomass fiber with the nanomaterial is carried out by conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, and conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump so as to be mixed with the biomass fiber.

[0048] According to the preparation method of the present invention, the pH value of the cooked mixture is adjusted to 1-14 before carrying out the hot grinding treatment. This can increase the surface activity of the fiber and improve its compositing efficiency with the nano-particles. Specifically, the pH value of the cooked mixture may be adjusted with an aqueous solution of H.sub.3PO.sub.4, HCl, H.sub.2SO.sub.4 or NaOH.

[0049] The present invention also provides a nanomaterial-biomass fiber composite, which is prepared according to the preparation method of the present invention.

[0050] The preparation method of a nanomaterial-biomass fiber composite material provided by the present invention utilizes a hot grinding method to uniformly attach nanomaterials to biomass fibers with firm attachment, so as to prepare the nanomaterial-biomass fiber composite. The preparation method of the invention has the advantages of simple operation, low cost, low energy consumption, suitability for industrialized production, and wide application prospect in the field of production of binderless fiberboards.

[0051] The present invention composites nanomaterials with biomass fibers to endow the new composite with the excellent properties of nanomaterials, which not only can effectively improve and increase product properties such as anti-corrosion, flame retardancy, dimensional stability and wear resistance, ensure the reliability and safety in use of products, prolong service life, save resources and energy, and reduce environmental pollution; but can also endow the product with new properties, such as antibacterial property, self-cleaning, self-degradation, organics-containing, etc., thereby preparing a new type of high value-added functional binderless fiberboard and vigorously promoting the development of binderless fiberboard industry.

[0052] The preparation method of the present invention can overcome the technical problems of low bonding strength, high density, high brittleness and easy water absorption in the traditional binderless fiberboards; and enhance the flexibility and waterproof performance of the binderless fiber composite; and at the same time, the present invention is simple in operation, low in cost, low in energy consumption, and suitable for industrialized production.

[0053] The following several examples are provided with respect to the preparation method of the nanoparticle-fiber composite of the present invention. The defibrator used in the examples was purchased from Shanghai Shenou General Valve Industry Co., Ltd. in a model number of JM-L80.

EXAMPLE 1

[0054] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is wood;

[0055] 2. adding nanomaterial into the biomass fiber and mixing them to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 100 C., the steam pressure is 0.01 MPa and the cooking time is 1 min; the nanomaterial is nano-TiO.sub.2, and the nanomaterial accounts for 0.01% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 1 using H.sub.3PO.sub.4 aqueous solution before carrying out the hot grinding treatment;

[0056] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0057] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 100 C., the hot pressing time is 270 min, and the hot pressing pressure is 7 MPa.

EXAMPLE 2

[0058] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is bamboo;

[0059] 2. conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 110 C., the steam pressure is 0.02 MPa and the cooking time is 2 min; the nanomaterial is nano-ZnO, and the nanomaterial accounts for 0.02% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 2 using HC1 aqueous solution before carrying out the hot grinding treatment;

[0060] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0061] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 120 C., the hot pressing time is 100 min, and the hot pressing pressure is 8 MPa.

EXAMPLE 3

[0062] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is wood and its processing residues;

[0063] 2. conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 120 C., the steam pressure is 0.05 MPa and the cooking time is 4 min; the nanomaterial is nano-Ag, and the nanomaterial accounts for 0.04% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 3 using H.sub.2SO.sub.4 aqueous solution before carrying out the hot grinding treatment;

[0064] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0065] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 200 C., the hot pressing time is 20 min, and the hot pressing pressure is 6 MPa.

EXAMPLE 4

[0066] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is bamboo and its processing residues;

[0067] 2. adding nanomaterial into the biomass fiber and mixing them to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 130 C., the steam pressure is 0.1 MPa and the cooking time is 6 min; the nanomaterial is nano-SiO.sub.2, and the nanomaterial accounts for 0.05% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 4 using H.sub.3PO.sub.4 aqueous solution before carrying out the hot grinding treatment;

[0068] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0069] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 150 C., the hot pressing time is 120 min, and the hot pressing pressure is 5 MPa.

EXAMPLE 5

[0070] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is crop waste, specifically rice straw;

[0071] 2. conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 140 C., the steam pressure is 0.2 MPa and the cooking time is 10 min; the nanomaterial is nano-Fe.sub.3O.sub.4, and the nanomaterial accounts for 0.1% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 5 using HCl before carrying out the hot grinding treatment;

[0072] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0073] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 180 C., the hot pressing time is 100 min, and the hot pressing pressure is 3 MPa.

EXAMPLE 6

[0074] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is crop waste, specifically wheat straw;

[0075] 2. conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 150 C., the steam pressure is 0.5 MPa and the cooking time is 12 min; the nanomaterial is nano-CaCO.sub.3, and the nanomaterial accounts for 0.2% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 6 using H.sub.2SO.sub.4 aqueous solution before carrying out the hot grinding treatment;

[0076] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0077] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 220 C., the hot pressing time is 20 min, and the hot pressing pressure is 7 MPa.

EXAMPLE 7

[0078] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is crop waste, specifically corn straw;

[0079] 2. adding nanomaterial into the biomass fiber and mixing them to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 160 C., the steam pressure is 0.8 MPa and the cooking time is 15 min; the nanomaterial is nano-Al.sub.2O.sub.3, and the nanomaterial accounts for 0.4% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 7 using H.sub.3PO.sub.4 aqueous solution and NaOH aqueous solution before carrying out the hot grinding treatment;

[0080] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0081] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 8

[0082] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is crop waste, specifically cotton straw;

[0083] 2. conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 170 C., the steam pressure is 1 MPa and the cooking time is 20 min; the nanomaterial is nano-Mg(OH).sub.2, and the nanomaterial accounts for 0.5% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 8 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0084] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0085] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 9

[0086] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is crop waste, specifically bagasse;

[0087] 2. conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 180 C., the steam pressure is 1.5 MPa and the cooking time is 25 min; the nanomaterial is nano-Al(OH).sub.3, and the nanomaterial accounts for 1% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 9 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0088] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0089] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 10

[0090] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is Gramineae weed, specifically reed;

[0091] 2. adding nanomaterial into the biomass fiber and mixing them to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 190 C., the steam pressure is 2 MPa and the cooking time is 30 min; the nanomaterial is nano-CeO.sub.2, and the nanomaterial accounts for 2% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 10 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0092] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0093] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 11

[0094] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber is Gramineae weed, specifically miscanthus;

[0095] 2. conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 200 C., the steam pressure is 3 MPa and the cooking time is 40 min; the nanomaterial is nano-MnO.sub.2, and the nanomaterial accounts for 5% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 11 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0096] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0097] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite (i.e., binderless fiberboard), wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 12

[0098] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber comprises a mixture of wood and wood processing residues;

[0099] 2. conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 210 C., the steam pressure is 5 MPa and the cooking time is 45 min; the nanomaterial is nano-cellulose, and the nanomaterial accounts for 10% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 12 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0100] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0101] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 13

[0102] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber comprises a mixture of bamboo and bamboo processing residues;

[0103] 2. adding nanomaterial into the biomass fiber and mixing them to obtain a mixture, and conveying the mixture to the preheating cylinder of a defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 220 C., the steam pressure is 6 MPa and the cooking time is 50 min; the nanomaterial is nano-graphene, and the nanomaterial accounts for 12% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 13 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0104] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0105] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 14

[0106] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber comprises a mixture of wood, bamboo and corresponding processing residues;

[0107] 2. conveying the nanomaterial to the discharge valve of the defibrator via a pipe and injecting it into the discharge valve via a nozzle so as to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 240 C., the steam pressure is 8 MPa and the cooking time is 55 min; the nanomaterial is nano-carbon fiber, and the nanomaterial accounts for 15% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 14 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0108] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and

[0109] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

EXAMPLE 15

[0110] 1. Cutting or slicing the biomass fiber, and then drying it to the extent that the moisture content of the biomass fiber is less than 10%, wherein the biomass fiber comprises a mixture of wood, bamboo and corresponding processing residues;

[0111] 2. conveying the nanomaterial onto a wood chip at the feed inlet of the grinding chamber of the defibrator via a delivery pump, conveying it into the continuous discharge valve of the grinding chamber of the defibrator via a gear pump to be mixed with the biomass fiber to obtain a mixture, and conveying the mixture to the preheating cylinder of the defibrator for cooking treatment, wherein the cooking temperature in the preheating cylinder is 250 C., the steam pressure is 10 MPa and the cooking time is 60 min; the nanomaterial is carbon nanotube, and the nanomaterial accounts for 20% of the absolute dry weight of the biomass fiber; and wherein the pH value of the cooked mixture is adjusted to 14 using NaOH aqueous solution before carrying out the hot grinding treatment;

[0112] 3. pushing the cooked mixture between the grinding discs of the defibrator for hot grinding treatment, wherein the rotating speed for the hot grinding is 2880 rpm, and the time for the hot grinding treatment is 6 h; and;

[0113] 4. filtering the hot-ground slurry followed by paving it into a plate blank, and hot pressing the plate blank to obtain the nanomaterial-biomass fiber composite, wherein the hot pressing temperature is 160 C., the hot pressing time is 180 min, and the hot pressing pressure is 4 MPa.

[0114] Product Structure and Performance Characterization

[0115] FIG. 2 is a scanning electron micrograph of a TiO.sub.2 nanomaterial-biomass fiber composite prepared in Example 1 of the present invention. Referring to FIG. 2, it can be observed that a large amount of inorganic nanomaterials, namely nano-TiO.sub.2, are loaded onto the biomass fibers.

[0116] FIG. 3 is a scanning electron micrograph of a ZnO nanomaterial-biomass fiber composite prepared in Example 2 of the present invention. Referring to FIG. 3, it can be observed that a large amount of inorganic nanomaterials, namely nano-ZnO, are loaded onto the biomass fibers.

[0117] FIG. 4 is a scanning electron micrograph of a Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite prepared in Example 5 of the present invention. Referring to FIG. 4, it can be observed that a large amount of inorganic nanomaterials, namely nano-Fe.sub.3O.sub.4, are loaded onto the biomass fibers.

[0118] FIG. 5 is a scanning electron micrograph of a CaCO.sub.3 nanomaterial-biomass fiber composite prepared in Example 6 of the present invention. Referring to FIG. 5, it can be observed that a large amount of inorganic nanomaterials, namely nano-CaCO.sub.3, are loaded onto the biomass fibers.

[0119] FIG. 6 is a hysteresis loop of a Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite prepared in Example 5 of the present invention. Referring to FIG. 6, where the abscissa is the magnetic field (Oe) and the ordinate is the saturation magnetization (emu/g). Three samples having Fe.sub.3O.sub.4 concentrations of 30 wt %, 35 wt % and 40 wt % respectively were taken from the Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite prepared in Example 5, and were measured at room temperature by a vibrating sample magnetometer. In FIG. 6, the specific curve is shown, with the saturation magnetization of the sample varying with the concentration of Fe.sub.3O.sub.4. When the Fe.sub.3O.sub.4 concentration is 30 wt %, the saturation magnetization thereof is 19.4 emu/g; when the Fe.sub.3O.sub.4 concentration is 35 wt %, the saturation magnetization thereof is 25.7 emu/g; and when the Fe.sub.3O.sub.4 concentration is 40 wt %, the saturation magnetization thereof is 30.9 emu/g. It can be seen from FIG. 6 that the composite material successfully inherits the magnetic property of Fe.sub.3O.sub.4, and as the concentration of Fe.sub.3O.sub.4 increases from 30 wt % to 40 wt %, the saturation magnetization also increases, which demonstrates that the Fe.sub.3O.sub.4 nanomaterial-biomass fiber composite have excellent magnetic properties.

[0120] FIG. 7 is a graph showing the changing of the reflection loss frequency of the ZnO nanomaterial-biomass fiber composite prepared in Example 2 of the present invention. Referring to FIG. 7, from the ZnO nanomaterial-biomass fiber composite prepared in Example 2 of the present invention, four samples only different in thickness, with the other parameters being the same, were taken, the thicknesses thereof being 2 mm, 2.5 mm, 3 mm, and 3.5 mm respectively, and they were subjected to a reflection loss-frequency test. It can be seen from FIG. 7 that, within a certain frequency range, the absorption effect of the sample increases as the thickness of the material increases.

[0121] When the sample thickness is 2 mm, the maximum attenuation is 5 dB at about 16.4 GHz; when the sample thickness is 2.5 mm, the maximum attenuation is 7 dB at about 16.2 GHz; when the sample thickness is 3 mm, the maximum attenuation is 8 dB at about 16.8 GHz; and when the sample thickness is 3.5 mm, the maximum attenuation is 9 dB at about 16.8 GHz. It can be seen from FIG. 7 that the composite material successfully inherits the wave absorption property of ZnO, which demonstrates that the ZnO nanomaterial-biomass fiber composite has good wave absorption properties.

[0122] FIGS. 8A and 8B show the comparisons between the mechanical properties as well as thickness swelling rate of water absorption of the nanomaterial-biomass fiber composite (i.e., a binderless fiberboard) prepared in Example 11 of the present invention and a conventional binderless fiberboard. Referring to FIG. 8A, compared with the 12.5 MPa static bending strength of the conventional binderless fiberboard, the static bending strength of the binderless fiberboard prepared in Example 11 of the present invention increases to 20.7 MPa. Referring to FIG. 8b, as compared with the 13.5% thickness swelling rate of the conventional binderless fiberboard, the thickness swelling rate of the binderless fiberboard prepared in Example 11 of the present invention reduces to 7.1%. The above results indicate that the binderless fiberboards of the present invention have a better performance.

[0123] The numerical values set forth in these examples do not limit the scope of the present invention unless otherwise specified. In all the examples shown and described herein, unless otherwise specified, any specific value should be interpreted as illustrative merely but not a limitation, and thus, other examples of the illustrative embodiments may have different values.

[0124] Finally, it should be noted that, the above examples are only used to illustrate the technical solutions of the present invention, rather than limit the same; although the present invention has been described in detail with reference to the foregoing examples, those skilled in the art should understand that, it is still possible to modify the technical solutions described in the foregoing examples or equivalently replace part or all of the technical features therein; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the examples of the present invention, and they should be all covered by the scope of the claims and the description of the present invention.