Functional composite material based on inorganic compound system and preparation method

Abstract

The invention discloses a functional composite material based on an inorganic substance compound system and a preparation method, and belongs to the technical field of functional materials, and the preparation method comprises the following steps: processing and drying raw materials; modifying the salix psammophila fibers; step-by-step mixing and paving assembly are conducted; the inorganic compound system is prepared from montmorillonite, zinc oxide and nano conductive carbon black; and performing hot press molding: performing hot press molding on the obtained plate blank to obtain the functional composite material based on the inorganic matter compound system. The silane coupling agent KH550 is used as an interfacial activator of the wood flour and the polylactic acid matrix, so that the interfacial compatibility of the composite material is improved, the mechanical strength is improved, and meanwhile, an inorganic compound system is constructed to provide excellent mechanical, aging-resistant, electromagnetic shielding and flame-retardant properties for the composite material. Test results show that the mechanical strength, the surface resistivity, the electromagnetic shielding effectiveness and the flame retardant property of the composite material all meet corresponding national / industrial standard requirements, and the aging resistance and the thermal stability are remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of functional materials, and specifically, to a functional composite material based on an inorganic composite system and a preparation method thereof. Background Art

[0002] In recent years, with the increasing attention paid to the ecological environment by people and the continuous in-depth research in the field of materials, natural plant fiber / bio-degradable plastic composite materials have gradually attracted wide attention due to their excellent properties such as low cost, environmental friendliness, good mechanical properties, strong plasticity, and good chemical stability. They show good application prospects in the fields of building materials, gardening, vehicle and ship manufacturing, home decoration, etc.

[0003] As a natural environmental protection material, inorganic matter has functions such as flame retardancy, aging resistance, antibacterial, conductivity, and mechanics, and can improve the properties of composite materials. Therefore, introducing inorganic matter as a filler to improve the functionality of natural plant fiber / bio-degradable plastic composite materials plays an important role in the development of composite materials, provides a scientific basis and theoretical guidance for the development of plant fiber reinforced polymer composite materials, and can, to a certain extent, solve the urgent need for single performance of functional plant fiber polymer composite materials. In addition, developing an excellent performance and green environmental protection type of inorganic functional filler approach is an urgent problem to be solved in the current field of functional composite materials, and is of great significance for promoting the research of multi-functional composite materials. Solving the problem of single function of plant fiber reinforced polymer composite materials is of great significance for the development of multi-performance, safe and non-toxic material fields and the establishment of an environment-friendly society.

[0004] The development of functional composite material systems represents the development of multi-performance regulation. The functional reconstruction based on the traditional plant fiber polymer material system realizes the expansion of applications and has a synergistic effect in the field of sustainable manufacturing. Although breakthroughs have been achieved in the research of composite systems, the following problems still exist: (1) The functionalization of composite materials is mainly achieved through organic additives. The types of common functional organic additives are relatively traditional and have single efficacy, and it is difficult to meet multiple performance requirements at the same time; (2) Considering the broader application prospects of functional plant fiber reinforced PLA composite materials in the future, the research and development of antistatic, conductive, and electromagnetic shielding composite materials deserve more attention; (3) Some organic auxiliaries contain toxic components (such as flame retardants, etc.), which cause harm to human health or the environment.

[0005] Therefore, how to develop a functional composite material based on an inorganic composite system and a preparation method thereof is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a functional composite material based on an inorganic composite system and a preparation method thereof.

[0007] A preparation method of a functional composite material based on an inorganic compound system, comprising the following steps:

[0008] (1) Processing and drying of raw materials: After removing the skin of the Salix psammophila wood strips, they are crushed, sieved, and dried to obtain Salix psammophila fibers;

[0009] (2) Modification of Salix psammophila fibers: Dissolve the coupling agent in an ethanol aqueous solution with a volume fraction of 95% to obtain a coupling agent solution. Sprinkle the coupling agent solution evenly on the Salix psammophila fibers obtained in step (1), and dry to obtain modified Salix psammophila fibers;

[0010] (3) Step-by-step mixing and mat forming: Divide the modified Salix psammophila fibers, polylactic acid, and inorganic compound system obtained in step (2) into the first and second parts of materials according to mass. Stir and mix the first part of the modified Salix psammophila fibers, polylactic acid, and inorganic compound system, and then continue to add the remaining second part of the modified Salix psammophila fibers, polylactic acid, and inorganic compound system and stir and mix. Place the mixed material in a mold for mat forming, press the material, and let it stand for a period of time. After the material form is fixed, obtain a board blank;

[0011] The above inorganic compound system is montmorillonite, zinc oxide, and nano-conductive carbon black;

[0012] (4) Hot pressing and forming: Hot press and form the board blank obtained in step (3) to obtain the above-mentioned functional composite material based on the inorganic compound system.

[0013] Further, in step (1), sieve and select Salix psammophila wood powder with a particle size of 40 - 60 mesh, and the drying temperature is 70 ± 2 °C, and dry until the moisture content of the Salix psammophila fibers is below 2%.

[0014] The beneficial effects of adopting the above further technical solution: Research shows that Salix psammophila wood powder with a particle size of 40 - 60 mesh can form a good interweaving state inside the composite material, which is beneficial to the uniform distribution of the matrix and the effective transfer of stress, and further improves the mechanical properties. The drying temperature of 70 ± 2 °C can ensure the efficiency of achieving the drying effect of the modified wood powder, and at the same time, the wood powder will not become brittle due to too high a temperature. Drying to a moisture content below 2% not only ensures that the wood powder has a certain plasticity and is convenient for hot pressing and forming; at the same time, it will not produce too much water vapor during hot pressing due to too high a moisture content and affect the product quality.

[0015] Further, in step (2), the above coupling agent is silane coupling agent KH550.

[0016] Beneficial effects of adopting the above further technical solution: The silane coupling agent KH550 forms Si-O-C bonds with the surface hydroxyl groups of the willow wood powder through a hydrolysis and condensation mechanism, and its organic functional groups (such as vinyl, amino, etc.) further covalently bond with the polylactic acid matrix, realizing the strengthening of the two-phase interface and being beneficial to the improvement of mechanical strength.

[0017] Further, in step (2), the concentration of the above coupling agent solution is 20 wt%, and the dosage of the coupling agent is 2% of the mass of the willow fiber.

[0018] Beneficial effects of adopting the above further technical solution: Adding the coupling agent in the form of a solution is beneficial to the dispersion of the coupling agent between the matrices, achieving a better interface modification effect; research shows that when the addition amount of the coupling agent is 2%, the interface modification effect is the best.

[0019] Further, in step (2), the drying temperature is 70 ± 2 °C, and the willow fiber is dried until the moisture content is below 2%.

[0020] Beneficial effects of adopting the above further technical solution: A drying temperature of 70 ± 2 °C can ensure the efficiency of achieving the drying effect of the modified wood powder, and at the same time, the wood powder will not become brittle due to too high a temperature. Drying to a moisture content below 2% not only ensures that the wood powder has a certain plasticity, facilitating hot pressing molding; but also will not produce too much water vapor during hot pressing due to too high a moisture content, affecting the product quality.

[0021] Further, in step (3), the mass ratio of the above modified willow fiber to polylactic acid is 3:7, the addition amount of the inorganic compound system is 3 - 9% of the total mass of the modified willow fiber and polylactic acid materials, and the mass ratio of montmorillonite, zinc oxide, and nano-conductive carbon black is (1 - 3):(1 - 3):(1 - 3).

[0022] Beneficial effects of adopting the above further technical solution: Research shows that a mass ratio of willow fiber to polylactic acid of 3:7 can ensure that the composite material has good mechanical toughness and fully exerts the strengthening effect of the willow fiber. The addition amount of the inorganic compound system being 3 - 9% of the total mass of the modified willow fiber and polylactic acid materials can ensure that the composite material has better functional properties. Under the condition that the mass ratio of montmorillonite, zinc oxide, and nano-conductive carbon black is (1 - 3):(1 - 3):(1 - 3), the synergistic effect mechanism of the three is relatively fully exerted.

[0023] Further, in step (3), the mass ratio of the first part and the second part of the materials is 3:7. The compound system of the modified Salix psammophila fiber, polylactic acid and inorganic matter in the first part is stirred and mixed for 5 - 10 min at a stirring speed of 20 - 30 revolutions per minute. Then, the compound system of the modified Salix psammophila fiber, polylactic acid and inorganic matter in the remaining second part is continuously added and stirred and mixed for 5 - 10 min at a stirring speed of 20 - 30 revolutions per minute.

[0024] Beneficial effects of adopting the above further technical solution: The "two-step" addition process can ensure more sufficient mixing of the materials and further improve the uniformity of the dispersion of the material system.

[0025] Further, in step (3), the pressure for pressing the material is 1 MPa and the standing time is 10 min.

[0026] Beneficial effects of adopting the above further technical solution: This process can achieve the preliminary shaping of the slab material. The slab has sufficient initial strength, which can ensure that the slab does not collapse and meet the convenience of subsequent processes such as slab transportation and loading.

[0027] Further, in step (4), the hot pressing forming temperature of the slab obtained in step (3) is 190 °C, the hot pressing pressure is 7 MPa, and the hot pressing time is 7 min.

[0028] Beneficial effects of adopting the above further technical solution: The above process can achieve the full shaping of the materials, achieving the dual effects of good sheet quality and high production efficiency.

[0029] The present invention also provides a functional composite material based on an inorganic matter compound system prepared by the above method, with a density of 0.80 - 1.20 g / cm 3 .

[0030] The beneficial effects of the present invention are as follows: Aiming at the problems of single function of organic functional additives and toxicity of some additives in the prior art, the present invention uses silane coupling agent KH550 as the interfacial activator between wood powder and polylactic acid matrix to improve the interfacial compatibility of the composite material and enhance the mechanical strength. At the same time, an "inorganic matter compound system" is constructed to provide excellent mechanical, anti-aging, electromagnetic shielding and flame retardant properties for the composite material. The test results show that the mechanical strength, surface resistivity, electromagnetic shielding efficiency and flame retardant properties of the composite material all meet the requirements of corresponding national / industry standards, and the anti-aging performance and thermal stability are significantly improved. Description of the Drawings

[0031] Figure 1Bar chart of the influence of the Na-MMT / ZnO / CCB compounding ratio on the mechanical properties of the SPP / PLA composite material. Among them, (a) is the bar chart of the flexural strength, (b) is the bar chart of the flexural strength retention rate, (c) is the bar chart of the elastic modulus, and (d) is the bar chart of the elastic modulus retention rate.

[0032] Figure 2 Bar chart of the influence of the Na-MMT / ZnO / CCB compounding on the impact strength of the SPP / PLA composite material. Among them, (a) is the bar chart of the impact strength, and (b) is the bar chart of the impact strength retention rate.

[0033] Figure 3 Physical diagram of the influence of the Na-MMT / ZnO / CCB compounding on the vertical burning of the SPP / PLA composite material. Among them, (a) is the initial burning state of the control group SPP / PLA composite material at 15 s, (a1) is the charred state of the control group SPP / PLA composite material, (b) is the initial burning state of the Na-MMT / ZnO / CCB compounding ratio 3:1:1 composite material at 15 s, (b1) is the charred state of the Na-MMT / ZnO / CCB compounding ratio 3:1:1 composite material, (c) is the initial burning state of the Na-MMT / ZnO / CCB compounding ratio 1:3:1 composite material at 15 s, (c1) is the charred state of the Na-MMT / ZnO / CCB compounding ratio 1:3:1 composite material, (d) is the initial burning state of the Na-MMT / ZnO / CCB compounding ratio 1:1:3 composite material at 15 s, and (d1) is the charred state of the Na-MMT / ZnO / CCB compounding ratio 1:1:3 composite material.

[0034] Figure 4 Curve diagram of the influence of the Na-MMT / ZnO / CCB compounding on the heat release rate and total amount of the composite material. Among them, (a) is the curve diagram of the heat release rate, and (b) is the curve diagram of the total heat release.

[0035] Figure 5 Curve diagram of the influence of the Na-MMT / ZnO / CCB compounding on the smoke release rate and total amount of the composite material. Among them, (a) is the curve diagram of the smoke release rate, and (b) is the curve diagram of the total smoke release.

[0036] Figure 6 Bar chart of the influence of the Na-MMT / ZnO / CCB compounding ratio on the mass loss of the composite material. Among them, (a) is the bar chart of the mass, and (b) is the curve diagram of the mass loss rate.

[0037] Figure 7 Bar chart of the influence of the Na-MMT / ZnO / CCB compounding ratio on the contact angle of the composite material.

[0038] Figure 8 It is a curve graph showing the influence of the compounding ratio of Na-MMT / ZnO / CCB on the thermal stability of the composite material. Among them, (a) is the weight loss rate curve graph, and (b) is the weight loss rate curve graph.

[0039] Figure 9 It is a bar graph showing the influence of the compounding ratio of Na-MMT / ZnO / CCB on the surface resistivity of the composite material.

[0040] Figure 10 It is a bar graph showing the influence of the compounding ratio of Na-MMT / ZnO / CCB on the electromagnetic shielding effectiveness of the composite material.

[0041] Figure 11 It is a schematic diagram of the synergistic mechanism of the inorganic compounding of Na-MMT / ZnO / CCB. Specific embodiments

[0042] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The silane coupling agent KH550 of the present invention is purchased from Nanjing Chuangshi Chemical Auxiliary Co., Ltd.

[0044] The polylactic acid used in the present invention is in powder form, 100 mesh, with a molecular weight of 5×10 4 , and a density of 1.24 g / cm 3 .

[0045] The nano-conductive carbon black of the present invention has a diameter of 30-40 nm.

[0046] Example 1

[0047] A preparation method of a functional composite material based on an inorganic compounding system includes the following steps:

[0048] (1) Processing and drying of raw materials: After peeling the willow wood strips, they are crushed, and the willow wood powder with a particle size of 40-60 mesh is selected by sieving, and dried at a temperature of 70±2°C until the moisture content of the willow fiber is below 2%;

[0049] (2)Modification of Salix psammophila fiber: Dissolve the coupling agent silane coupling agent KH550 in an ethanol aqueous solution with a volume fraction of 95% to obtain a coupling agent solution with a concentration of 20 wt%. Spray the coupling agent solution evenly on the Salix psammophila fiber obtained in step (1). The dosage of the coupling agent is 2% of the mass of the Salix psammophila fiber. Dry it at a temperature of 70±2 °C until the moisture content of the modified Salix psammophila fiber is below 2% to obtain the modified Salix psammophila fiber;

[0050] (3)Step-by-step mixing and mat forming: Divide the modified Salix psammophila fiber (SPP), polylactic acid (PLA) and inorganic compound system obtained in step (2) into the first part and the second part of the materials according to mass. The mass ratio of the first part and the second part of the materials is 3:7. Stir and mix the modified Salix psammophila fiber, polylactic acid and inorganic compound system in the first part for 8 min at a stirring speed of 25 revolutions per minute. Then continue to add the remaining modified Salix psammophila fiber, polylactic acid and inorganic compound system in the second part and stir and mix for 8 min at a stirring speed of 25 revolutions per minute. The mass ratio of the modified Salix psammophila fiber to polylactic acid is 3:7. The addition amount of the inorganic compound system is 5% of the total mass of the Salix psammophila fiber and polylactic acid materials. The inorganic compound system is montmorillonite (Na-MMT), zinc oxide (ZnO) and nano-conductive carbon black (CBB). The mass ratio of montmorillonite, zinc oxide and nano-conductive carbon black is 3:1:1. Place the mixed material in a mold of 200 mm×200 mm for mat forming, press the material to a thickness of 15 mm, the pressure for pressing the material is 1 MPa, and let it stand for 10 min. After the material form is fixed, obtain the board blank;

[0051] (4)Hot pressing and forming: Hot press and form the board blank obtained in step (3) at a temperature of 190 °C, a hot pressing pressure of 7 MPa, and a hot pressing time of 7 min. After trimming the specimen, make a functional composite material based on the inorganic compound system with a density of 1.0 g / cm 3 ³ and a thickness of 4 mm.

[0052] According to the above steps, the test results of the composite material performance are as follows:

[0053] The static bending strength and elastic modulus of the composite material are 34.49 MPa and 3662 MPa respectively, meeting the secondary index requirements of the static bending strength and elastic modulus for plain unfoamed indoor wood-plastic composites in LY / T 3274-2021 "Classification of Wood-Plastic Composites" (≥30 MPa, ≥2500 MPa), and at the same time meeting the requirements of GB / T 24137-2009 "Requirements for Wood-Plastic Decorative Boards" (≥20 MPa, ≥1880 MPa). The impact strength of the composite material is 4.03 kJ / m 2, meeting the requirements of the third-level index (≥4) for the notch-free impact strength of the plain and unfoamed outdoor wood-plastic composite materials in LY / T 3274-2021 "Classification of Wood-Plastic Composite Materials". The limiting oxygen index (LOI) of the composite material is 27.6%, reaching the flame-retardant level, and the vertical burning rating is V-1. The thermal stability is improved, the initial degradation temperature is increased by 200 °C, and the heat release is reduced by 9 MJ / m 2 , and the pre-flame smoke release is significantly reduced. The ignition time is 20 s, which is 9 s longer than that of the blank sample, and the mass loss is reduced by 366.6 g / m 2 .

[0054] Example 2

[0055] Compared with Example 1, except that the mass ratio of montmorillonite, zinc oxide and nano-conductive carbon black is 1:3:1, other steps and parameters are the same as those in Example 1.

[0056] Test results of the properties of the composite material:

[0057] After being treated by thermal-oxidative aging at 80 °C for 128 h, the flexural strength and elastic modulus of the composite material are 27.64 MPa and 2986 MPa respectively, meeting the requirements of the third-level index (≥23 MPa, ≥1800 MPa) for the flexural strength and elastic modulus of the plain and unfoamed outdoor wood-plastic composite materials in LY / T 3274-2021 "Classification of Wood-Plastic Composite Materials", and at the same time meeting the requirements of GB / T 24137-2009 "Wood-Plastic Decorative Boards" (≥20 MPa, ≥1880 MPa); the retention rates of mechanical strength are 92% and 91% respectively, the mass loss rate is only 0.3%, and the surface water contact angle is 115.5°, showing excellent hydrophobicity and heat-oxidative aging resistance.

[0058] Example 3

[0059] Compared with Example 1, except that the mass ratio of montmorillonite, zinc oxide and nano-conductive carbon black is 1:1:3, other steps and parameters are the same as those in Example 1.

[0060] Test results of the properties of the composite material:

[0061] After being treated by thermal-oxidative aging at 80 °C for 128 h, the flexural strength and elastic modulus of the composite material are 32.64 MPa and 3465 MPa respectively, meeting the requirements of the second-level index (≥30 MPa, ≥2500 MPa) for the flexural strength and elastic modulus of the plain and unfoamed indoor wood-plastic composite materials in LY / T 3274-2021 "Classification of Wood-Plastic Composite Materials", and at the same time meeting the requirements of GB / T 24137-2009 "Requirements for Wood-Plastic Decorative Boards" (≥20 MPa, ≥1880 MPa).

[0062] The surface resistivity of the composite material is 0.24 KΩ·cm, which is a superconducting material; the logarithm of the surface resistivity is 2, meeting the EP-2 grade (logarithm of surface resistivity ≤ 3) in the electrical property requirements of GB / T 32511-2016 "General Technical Requirements for Electromagnetic Shielding Plastics".

[0063] The electromagnetic shielding effectiveness of the composite material is 27.43 dB, meeting the requirements of the SE-3 grade (20 dB) of GB / T 32511-2016 "General Technical Requirements for Electromagnetic Shielding Plastics".

[0064] Comparative Example 1

[0065] Compared with Example 1, except for not adding the inorganic composite system of montmorillonite, zinc oxide and nano-conductive carbon black, other steps and parameters are the same as those in Example 1.

[0066] The following experiments were carried out using Examples 1-3 of the present invention and Comparative Example 1.

[0067] 1. Influence of Na-MMT / ZnO / CBB composite system on the properties of SPP / PLA composite materials

[0068] 1.1 Mechanical property analysis

[0069] The change trend of the mechanical properties of the Na-MMT / ZnO / CCB composite-reinforced SPP / PLA composite material before and after thermal-oxidative aging at 80 °C for 128 h is as shown in Figure 1 Figures (a)-(d). Before aging, when the compounding ratios of Na-MMT / ZnO / CCB are 3:1:1, 1:3:1, and 1:1:3 in turn, the flexural strength and elastic modulus of the composite material both show a trend of first decreasing and then increasing. When the compounding ratio of Na-MMT / ZnO / CCB is 3:1:1, the optimal values of the flexural strength and elastic modulus of the composite material are 34.49 MPa and 3662 MPa, respectively, which are 68% and 50% higher than those of the blank sample.

[0070] When the addition amount of Na-MMT increases, the unique lamellar structure of Na-MMT interacts with the matrix through chemical bonding and physical adsorption, enabling ZnO and CCB to be evenly distributed in the SPP / PLA matrix and avoiding the agglomeration of fillers. In addition, Na-MMT fills some voids and guides the distribution of ZnO and CCB, making the internal structure of the material relatively regular. When subjected to external forces, the stress inside the material can be evenly distributed, reducing the local stress concentration and improving the flexural strength and elastic modulus of the composite material. When the addition amount of Na-MMT decreases relatively, CCB can still play a synergistic role with Na-MMT. The lamellar structure of Na-MMT can intertwine with CCB to form a network structure, effectively filling the voids inside the material. This synergistic dispersion effect enables the fillers to reach a relatively uniform distribution state in the matrix again, enhancing the integrity of the internal structure of the material. When subjected to external forces, it can transfer and disperse stress, increasing the flexural strength and elastic modulus. However, due to the relatively stable structure at the ratio of 3:1:1 before, the performance at this time is slightly lower.

[0071] After the composite material is aged, when the compounding ratios of Na-MMT / ZnO / CCB are 3:1:1, 1:3:1, and 1:1:3 in sequence, and the addition amount of ZnO first increases and then decreases, the flexural strength retention rate and elastic modulus of the composite material show a gradually decreasing trend, and the retention rate shows a trend of first increasing and then decreasing. When the compounding ratio of Na-MMT / ZnO / CCB is 1:3:1, the flexural strength and elastic modulus of the aged composite material are 27.64 MPa and 2986 MPa respectively, and the optimal values of the mechanical retention rates are 92% and 91% respectively, with better heat and oxygen aging resistance.

[0072] When the ZnO content increases, ZnO can fully exert its antioxidant performance and absorb and consume free radicals generated during the thermal oxygen aging process. At the same time, Na-MMT, CCB, and ZnO play a synergistic role. The layered structure of Na-MMT blocks the diffusion of oxygen and free radicals, making it difficult for them to contact the matrix components inside the material. During this process, CCB assists ZnO in the antioxidant reaction through its own physical or chemical properties, stabilizing the internal structure of the composite material. This synergistic effect enables the material to maintain the integrity of its internal structure and interface stability, effectively transmit stress, and resist the damage of oxidation to the interface. As a result, the retention rates of the flexural strength and elastic modulus of the material reach the highest. When the ZnO content decreases relatively, the lamellar structure of Na-MMT has a certain protective effect on the internal microstructure of the composite material, filling some voids and guiding the distribution of fillers. During the thermal oxygen aging process, although Na-MMT and CCB have a certain effect, ZnO, as an effective antioxidant, its relatively low content limits the overall antioxidant capacity of the composite material, and its ability to scavenge free radicals and antioxidant protection of the internal microstructure are relatively insufficient, resulting in an increase in voids inside the material, molecular chain breakage, and structural damage, making it unable to resist deformation when subjected to external forces, and reducing the retention rates of the flexural strength and elastic modulus of the material.

[0073] The change trend of the impact strength of the Na-MMT / ZnO / CCB compound-reinforced SPP / PLA composite material before and after thermal oxygen aging at 80 °C for 128 h is as Figure 2 shown in Figures (a)-(b). Before aging, when the compounding ratios of Na-MMT / ZnO / CCB are 3:1:1, 1:3:1, and 1:1:3 in sequence, the impact strength of the composite material shows a trend of first decreasing and then increasing. When the compounding ratio of Na-MMT / ZnO / CCB is 3:1:1, the optimal value of the impact strength of the composite material is 4.03 kJ / m 2 , which is 57% higher than that of the blank sample.

[0074] When the addition amount of Na-MMT increases, Na-MMT can fill the voids inside the material and guide the distribution of ZnO and CCB, making the internal structure of the material relatively regular. This regular microstructure endows the material with good toughness. When the material is subjected to impact, the regular microstructure can absorb and dissipate energy through deformation instead of brittle fracture, thereby improving the impact strength of the composite material. When the addition amount of Na-MMT decreases, the composite material agglomerates, resulting in voids and uneven regions inside the material, reducing the toughness of the material. When subjected to impact, the material is more likely to undergo brittle fracture. At the same time, the relatively small amounts of Na-MMT and CCB cannot effectively fill these voids and repair the microstructure, resulting in a decrease in impact strength.

[0075] After the composite material is aged, when the compounding ratios of Na-MMT / ZnO / CCB are 3:1:1, 1:3:1, and 1:1:3 in sequence, and the addition amount of ZnO first increases and then decreases, the impact strength retention rate of the composite material shows a trend of first increasing and then decreasing. When the compounding ratio of Na-MMT / ZnO / CCB is 1:3:1, the impact strength of the aged composite material is 3.21 kJ / m 2 , and the optimal value of the impact strength retention rate is 94%, and the heat and oxygen aging resistance is better.

[0076] When the addition amount of ZnO increases, the interfacial bonding is enhanced through chemical bonding or physical adsorption. At the same time, Na-MMT and CCB can also cooperate with ZnO to further improve the interfacial stability. During the heat and oxygen aging process, stress and energy can be effectively transmitted, so that when the material is impacted, the filler can better share the energy, reduce the degree of material damage, and increase the impact strength retention rate of the material. When the addition amount of ZnO is low, there is a certain basis for the interfacial stability between it and the matrix and other fillers. However, during the heat and oxygen aging process, due to limited antioxidant ability, peeling phenomena will gradually appear at the interface due to oxidation and stress. As aging progresses, the stress transfer ability at the interface decreases. When the material is impacted, energy cannot be effectively transmitted between the filler and the matrix, reducing the impact strength retention rate of the material.

[0077] 1.2 Limiting oxygen analysis

[0078] The influence of the compounding ratio of Na-MMT / ZnO / CBB on the LOI of SPP / PLA composite materials is shown in Table 1. When the compounding ratios of Na-MMT / ZnO / CBB are 3:1:1, 1:3:1, and 1:1:3 in sequence, the LOI of the composite material shows a trend of first decreasing and then increasing. When the compounding ratio of Na-MMT / ZnO / CBB added is 3:1:1, the optimal LOI of the composite material is 27.6, which is 6.3% higher than that of the blank sample, reaching the difficult-to-burn level. The composite material is upgraded from the flammable material grade to the difficult-to-burn material grade, improving the combustion resistance of the composite material. When the composite material encounters a flame, it requires a longer ignition time, which improves the flame retardancy of the composite material to a certain extent. When the compounding ratio changes, the LOI of the composite material is still higher than that of the blank sample, but the growth rate compared with that at 3:1:1 decreases.

[0079] Table 1 Influence of the compounding of Na-MMT / ZnO / CBB on the LOI of SPP / PLA composite materials

[0080]

[0081] When the addition amount of Na-MMT is the largest, there is a synergistic flame retardant effect among Na-MMT, ZnO and CCB. The physical barrier and carbon layer stabilization effects of Na-MMT are dominant. ZnO plays a role in inhibiting the free radical chain reaction of the combustion reaction. CCB can cooperate with Na-MMT to improve the physical structure of the material and enhance the flame retardant performance. The comprehensive synergistic flame retardant effect makes the LOI of the material the highest. When the addition amount of Na-MMT decreases, the synergistic flame retardant effect becomes unbalanced. Due to the relatively small amount of Na-MMT, its dominant role is weakened. Moreover, the flame retardant mechanism of ZnO cannot be well coordinated with the physical barrier and carbon layer stabilization mechanisms of Na-MMT. Although CCB can cooperate with Na-MMT to restore part of the physical barrier and carbon layer stabilization effects, and can also cooperate with ZnO to inhibit the combustion reaction. However, since the synergistic flame retardancy is relatively optimized at the ratio of 3:1:1, the LOI at this time is still lower than that at the ratio of 3:1:1.

[0082] 1.3 Vertical combustion analysis

[0083] The influence of the Na-MMT / ZnO / CCB compounding ratio on the vertical combustion of the composite material is shown in Table 2. The t1 time of the blank sample is 157 s. When the Na-MMT / ZnO / CCB compounding ratio is 3:1:1, 1:3:1, 1:1:3, the t1 times of the composite materials are 25 s, 96 s, 82 s respectively. When the Na-MMT / ZnO / CCB compounding ratio is 3:1:1, the composite material reaches the V-1 vertical combustion grade. The composite material has no dripping phenomenon and can self-extinguish. Compared with the blank sample, the first combustion time (t1) is significantly reduced, which reduces the combustion time after the composite material is ignited and enhances the flame retardant effect of the composite material.

[0084] The 15 s initial combustion and char residue state of the vertical combustion test of the composite material are as Figure 3 shown in Figures (a)-(d1). According to the results, the initial combustion state of the blank sample (a) is the most intense, the combustion height of the flame is the highest, and the char residue of the blank sample (a1) is the least, indicating that the composite material is easy to be ignited and the combustion process is sufficient. The greater the addition amount of Na-MMT, the better the flame retardant effect. The initial combustion states of the composite materials added with Na-MMT / ZnO / CCB are all slower than that of the blank sample, the combustion height of the flame is significantly lower than that of the blank sample, and the intensity of the initial combustion is significantly weakened. Compared with the blank sample, the char residues of the composite materials are all significantly increased, and the combustion is relatively incomplete, which shortens the combustion time in case of fire, and the existing char residues provide a supporting role for the material. Among them, when the Na-MMT / ZnO / CCB compounding ratio is 3:1:1, the char residue amount of the composite material (b1) is the largest, and the composite material is not easy to be ignited, the combustion time is the shortest, and the flame retardant effect of the composite material is significantly enhanced.

[0085] Table 2 Influence of the compounding ratio of Na-MMT / ZnO / CCB on the vertical burning of the composite material

[0086]

[0087] Note: t1 is the afterflame time of a single specimen; t2 is the afterflame time of a single specimen after the second application of the flame

[0088] The synergistic effect of Na-MMT / ZnO / CCB helps to rapidly and stably form a char layer on the material surface. CCB can promote the carbonization process on the material surface, ZnO can catalyze the carbonization reaction of the SPP / PLA component, and the layered structure of Na-MMT provides a good template for the growth of the char layer. The char layer, as a heat and oxygen barrier, prevents the heat of the flame from directly transferring to the underlying material, prevents oxygen from contacting the combustible components in the lower layer, improves the vertical burning performance, reduces the burning rate, and even causes the material to self-extinguish.

[0089] 1.4 Cone calorimeter analysis

[0090] The influence of the compounding ratio of NaMMT / ZnO / CCB on the CONE of the composite material is as follows. The ignition time (TTI), maximum heat release rate (peak-HRR), average heat release rate (average HRR), total heat release (THR), total smoke production (TSP), and mass loss (Mass Lost) of the combustion performance of the composite material are shown in Table 3, and the heat release rate and total heat release curves are as Figure 4 shown in Figures (a)-(b) of Figure 5 and the smoke release rate and total smoke release are as shown in Figures (a)-(b) of 2 .

[0091] Table 3 Cone calorimeter test parameters of SPP / PLA composite materials

[0092]

[0093] When the compounding ratio of Na-MMT / ZnO / CCB is 3:1:1, during the thermal decomposition of the composite material, the inorganic components in the composite material will dilute the concentration of combustible components. From the perspective of the fire triangle (fuel, oxidizer, heat source), the concentration of the fuel is reduced, making the combustion reaction more difficult to occur and prolonging the ignition time. As a layered silicate mineral, Na-MMT improves the thermal stability of the composite material. Its layered structure forms a barrier, slowing down the heat transfer and reducing the decomposition rate of the material at high temperatures. ZnO catalyzes certain chemical reactions and promotes the stability of the material during decomposition. As a filler, CCB improves the structural strength and rigidity of the composite material, reduces the porosity of the material, reduces the diffusion of gas and heat, and improves the overall thermal stability. Therefore, the synergistic effect of the inorganic matter improves the compatibility between SPP / PLA, improves the uniformity and dispersion of the composite material, and reduces the mass loss during the heat treatment process.

[0094] The heat release represents the heat released by the composite material during combustion. According to Figure 4 it can be seen that when the compounding ratio of Na-MMT / ZnO / CCB is 3:1:1, both the average-HRR and HRR of the composite material decrease. The peak-HRR of the blank sample is 377.8 kW / m 2 , and the peak-HRR of the composite material after adding the inorganic matter compound is 353.5 kW / m 2 .

[0095] ZnO, CCB, and Na-MMT have a synergistic flame retardant effect. During heating, ZnO undergoes physical and chemical changes, absorbing heat or catalyzing some reactions, making the combustion reaction unable to proceed efficiently. CCB also plays a role as a physical barrier or participates in some reactions that inhibit combustion. When they act together with Na-MMT, the combustion efficiency will be further reduced, and thus the heat release rate is decreased.

[0096] TSP represents the total amount of smoke generated by the composite material during combustion. According to Figure 5 it can be seen that before 210 s, when the compounding ratio of Na-MMT / ZnO / CCB is 3:1:1, the SPR of the composite material is lower than that of the blank sample at the beginning stage. After 210 s, the SPR gradually becomes higher than that of the blank sample. Before 500 s, the TSP of the composite material is lower than that of the blank sample. After 500 s, it gradually increases, and the TSP is 3.9 m 2 , and the total amount of smoke generated increases.

[0097] This is because there is a synergistic effect among ZnO, Na-MMT and CCB during the initial stage of combustion, forming a network structure that inhibits the generation of combustion and smoke. After high temperature, this network structure is somewhat damaged, and Na-MMT, ZnO and CCB produce some volatile substances during the thermal degradation process, increasing the generation of smoke, increasing the flame propagation speed or changing the composition of the smoke generated during combustion, resulting in an increase in the total amount of smoke. It shows that the compounding of the three inorganic substances can improve the flame retardancy and thermal stability of the composite material, but there will be a side effect of suppressing smoke in the later stage.

[0098] 1.5 Analysis of aging resistance performance

[0099] (1) Mass loss test analysis

[0100] The mass change and mass loss rate of the Na-MMT / ZnO / CBB compounded and enhanced composite material before and after 80°C, 128h thermo-oxidative aging are as Figure 6 shown in Figures (a)-(b). When the compounding ratios of Na-MMT / ZnO / CBB are 3:1:1, 1:3:1, and 1:1:3 in sequence, the mass loss rate of the composite material shows a trend of first decreasing and then increasing. When the compounding ratio of Na-MMT / ZnO / CBB is 1:3:1, the masses of the composite material before and after aging are 9.65 g and 9.62 g respectively, and the optimal value of the mass loss rate is 0.3%, with better thermo-oxidative aging resistance effect.

[0101] When the addition amount of ZnO is low, there is a certain basis for the interfacial stability between it and the SPP / PLA matrix and fillers. The lamellar structure of Na-MMT enhances the interfacial bonding, but due to the limited content of ZnO, during the thermo-oxidative aging process, the improvement of the antioxidant ability and stress transfer ability at the interface is limited. With the progress of aging, peeling phenomena gradually appear at the interface. This leads to the destruction of the internal structure of the material and increases the mass loss of the material during the thermo-oxidative aging process. When the addition amount of ZnO increases, the interfacial bonding with the matrix and fillers is enhanced through chemical bonding or physical adsorption. At the same time, Na-MMT and CCB can cooperate with ZnO to further improve the interfacial stability. CCB can fill the voids at the interface and jointly resist the damage of oxidation to the interface with ZnO and Na-MMT. Even if a certain degree of oxidation reaction occurs inside the material, the stable interface ensures the relative integrity of the overall structure of the material, thereby reducing the mass loss and minimizing the mass loss rate.

[0102] (2) Contact angle test analysis

[0103] The contact angles of the Na-MMT / ZnO / CBB compounded and enhanced SPP / PLA composite material before and after 80°C, 128h thermo-oxidative aging are tested and photographed (after 30s of stabilization), and the change trend and state of the contact angle are as Figure 7As shown in the figure. When the compounding ratios of Na-MMT / ZnO / CBB are 3:1:1, 1:3:1, and 1:1:3 in turn, the contact angles of the composite materials before and after aging show a trend of first increasing and then decreasing. When the compounding ratio of Na-MMT / ZnO / CBB is 1:3:1, the contact angles of the composite material before and after aging are 127.4° and 115.5° respectively. The contact angle before aging is increased by 55% compared with the blank sample, and the difference in the contact angle of the composite material after aging is the lowest value in this group of tests, indicating better hydrophobicity and heat-aging resistance.

[0104] When the addition amount of ZnO is low, there is a certain basis for the interfacial stability between Na-MMT, ZnO, CCB and the SPP / PLA matrix. However, due to the low ZnO content, during the thermal-oxidative aging process, the tiny damage at the interface causes the internal components to migrate to the surface, changing the surface chemical composition, increasing the surface hydrophilicity, decreasing the contact angle, and resulting in a large difference in the contact angle before and after aging. When the addition amount of ZnO increases, Na-MMT, CCB, and ZnO cooperate to improve the interfacial stability, prevent the internal components from migrating to the surface, and resist the influence of oxidation on the surface during the thermal-oxidative aging process. The stable interface ensures the relative stability of the physical and chemical properties of the material surface, making the difference in the contact angle before and after aging the smallest.

[0105] 1.6 Thermogravimetric test analysis

[0106] The TGA-DTG curves of the Na-MMT / ZnO / CBB compound-reinforced SPP / PLA composite materials are shown in Figures (a)-(b) as follows. It is found from the TGA-DTG curves that the process of weight loss of the composite material during heating is divided into three stages. The specific temperature range, weight loss rate, maximum decomposition rate and residual carbon content are shown in Table 4. Figure 8 As shown in Figures (a)-(b). Through the TGA-DTG curves, it is found that the process of weight loss of the composite material during heating is divided into three stages. The specific temperature range, weight loss rate, maximum decomposition rate and residual carbon content are shown in Table 4.

[0107] Table 4 Weight loss rate and temperature of each stage of the SPP / PLA composite material

[0108]

[0109] Note: Tmax / ℃ is the maximum weight loss temperature

[0110] The temperature range of the first stage of thermal decomposition of the composite material is 50-249℃. The main reason for the thermal decomposition in this stage is the evaporation of moisture in the composite material. When the compounding ratio of Na-MMT / ZnO / CBB is 3:1:1, the mass loss rate of the composite material is 0%, and the initial degradation temperature is increased by 200℃ compared with the blank sample. Since the interlayer ions of Na-MMT can interact with the active sites on the surface of ZnO and the functional groups of CCB to form new active centers, adsorbing the active groups on the PLA molecular chain, the ester bond cleavage reaction of PLA requires higher energy to start, thus increasing the initial degradation temperature.

[0111] The temperature range of the second stage of the thermal decomposition of the composite material is between 249 and 425 °C. When the compounding ratio of Na-MMT / ZnO / CBB is 3:1:1, the degradation temperature of the composite material increases by 348 °C compared with the blank sample, the mass loss rate is 74.9%, and Tmax increases by 204 °C. Due to the mutual cooperation of Na-MMT / ZnO / CCB in the composite material, a more powerful physical barrier system is constructed. Na-MMT forms a layered stack, ZnO is filled between the layers or adheres to its surface, and CCB further fills the gaps and distributes around. The heat transfer path inside the material is severely blocked by the structure.

[0112] The temperature range of the third stage of the thermal decomposition of the composite material is between 425 and 800 °C. When the compounding ratio of Na-MMT / ZnO / CBB is 3:1:1, the residual carbon content of the composite material is 23.1%. This is because the synergistic effect of the three changes the reaction path of thermal decomposition, which is more conducive to the formation of carbon.

[0113] 1.7 Resistivity Test Analysis

[0114] The influence of the compounding ratio of Na-MMT / ZnO / CBB on the surface resistivity of SPP / PLA composite materials is as Figure 9 shown. When the compounding ratios of Na-MMT / ZnO / CCB are 3:1:1, 1:3:1, and 1:1:3 in turn, the resistivity of the composite material gradually decreases. When the compounding ratio of MMT / ZnO / CBB is 1:1:3, the resistivity of the composite material is 0.24 KΩ·cm, becoming a superconducting material, which decreases by 99% compared with the blank sample.

[0115] When the addition amount of CCB increases, the interfacial conductivity performance is optimized. The groups in the chemical structure of CCB form stable chemical bonds or physical adsorption structures with the matrix, ZnO, and Na-MMT. The synergistically optimized interface can transfer electrons more effectively, reduce the scattering and loss of electrons at the interface, improve the connection points in the circuit, enable the current to pass more smoothly, and reduce the resistivity of the composite material. When the addition amount of CCB decreases, the improvement of the interfacial interaction between Na-MMT, ZnO, CCB and the matrix on the conductivity performance is limited. Due to the relatively low content of ZnO and CCB, the interfacial bonding with the matrix is not tight enough. In the process of electron transmission, regions with relatively high resistance are likely to appear at the interface because electrons are hindered when passing through the interface, resulting in a relatively high resistivity of the composite material.

[0116] 1.8 Electromagnetic Shielding Test Analysis

[0117] The influence of the compounding ratio of Na-MMT / ZnO / CBB on the electromagnetic shielding of SPP / PLA composite materials is as Figure 10As shown. When the compounding ratios are 3:1:1, 1:3:1, and 1:1:3 in sequence, the electromagnetic shielding of the composite material gradually increases. When the Na-MMT / ZnO / CBB compounding ratio is 1:1:3, the electromagnetic shielding effectiveness of the composite material is 27.43 dB, which is 862% higher than that of the blank sample, and the radiation attenuation rate reaches 99%, meeting the SE-3 level of GB / T 32511-2016 "General Technical Requirements for Electromagnetic Shielding Plastics".

[0118] When the addition amount of CCB increases, CBB forms chemical bonds or physical adsorption structures with the matrix, ZnO, and Na-MMT. The synergistically optimized interface can guide electromagnetic waves into the conductive network, reduce the energy loss at the interface, and enhance the electromagnetic shielding effect of the material. When the addition amount of CCB decreases, the electromagnetic properties at the interface between Na-MMT, ZnO, CBB, and the SPP / PLA matrix are relatively weak. Due to the low content of ZnO and CBB, the interface bonding with the matrix is not tight, resulting in a mismatch in electromagnetic characteristics. The transition of the dielectric constant and magnetic permeability at the interface is not smooth, which will cause the reflection and scattering of electromagnetic waves at the interface, reducing the overall effectiveness of electromagnetic shielding.

[0119] 2. Analysis of the synergistic effect principle of Na-MMT / ZnO / CCB

[0120] By constructing a Na-MMT / ZnO / CCB compound system and optimizing the compounding ratio, the synergistic effect on the mechanical, flame retardant, aging resistance, and electromagnetic shielding properties of the SPP / PLA composite material can be achieved. The specific synergistic mechanism analysis is as follows: First, Na-MMT interacts with the SPP / PLA matrix through chemical bonding and physical adsorption. With its lamellar structure, ZnO and CCB are evenly distributed in the matrix, avoiding the agglomeration of fillers and enhancing the mechanical properties of the composite material.

[0121] Secondly, there is a synergistic flame retardant effect among Na-MMT, ZnO, and CCB. The physical barrier and carbon layer stabilization effect of Na-MMT are dominant. It undergoes endothermic reactions to generate substances such as water (H2O), carbon dioxide (CO2), and carbon monoxide (CO), reducing the surface temperature of the material. At the same time, Na-MMT migrates to the material surface to form a silicon-containing porous carbon layer, hindering the heat exchange between the inside and outside of the material; ZnO inhibits the free radical chain reaction of the combustion reaction; CCB and Na-MMT synergistically improve the physical structure of the material, thereby improving the flame retardant performance.

[0122] In addition, Na-MMT, CCB, and ZnO synergistically enhance the aging resistance of the composite material. The antioxidant and thermal stability effects of ZnO are dominant. It can withstand a certain thermal load at high temperatures, absorb heat, slow down the thermal degradation rate of SPP and PLA, and at the same time form a dense oxide film with oxygen to prevent oxygen penetration, playing an antioxidant role; CCB is filled in the voids at the interface and jointly resists the damage to the interface caused by oxidation with ZnO and thermally stable Na-MMT, ensuring the relative integrity of the overall structure of the material and the relative stability of the surface physical and chemical properties, thereby slowing down the aging degree.

[0123] Finally, the synergistic effect of Na-MMT, CCB, and ZnO enhances the electromagnetic shielding effectiveness of the composite material. The good conductivity of CCB is dominant. The groups in its chemical structure can form more stable chemical bonds or physical adsorption structures with the matrix, ZnO, and Na-MMT, optimizing the interfacial conductivity, transferring electrons more effectively, improving the connection points in the circuit, enabling the current to pass more smoothly, and reducing the resistivity of the composite material. It better guides electromagnetic waves into the conductive network, reduces the energy loss at the interface, and further enhances the shielding effect of the material on electromagnetic waves. In summary, the mechanisms of the Na-MMT / ZnO / CCB compound-enhanced SPP / PLA composite material in terms of mechanical properties, flame retardancy, heat and oxygen aging resistance, and electromagnetic shielding performance are as Figure 11 shown.

[0124] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a functional composite material based on an inorganic matter compounding system, characterized in that It includes the following steps: (1) Processing and drying of raw materials: After peeling the Salix psammophila wooden strips, they are crushed, screened, and dried to obtain Salix psammophila fibers; (2) Modification of Salix psammophila fibers: The coupling agent is dissolved in an ethanol aqueous solution with a volume fraction of 95% to obtain a coupling agent solution. The coupling agent solution is evenly sprayed on the Salix psammophila fibers obtained in step (1) and dried to obtain modified Salix psammophila fibers; (3) Step-by-step mixing and laying up for blanking: The modified Salix psammophila fibers, polylactic acid, and inorganic compound system obtained in step (2) are divided into the first part and the second part of materials according to mass. The modified Salix psammophila fibers, polylactic acid, and inorganic compound system in the first part are stirred and mixed, and then the remaining second part of the modified Salix psammophila fibers, polylactic acid, and inorganic compound system are continuously added and stirred and mixed. The mixed material is placed in a mold for laying up, the material is pressed, and left standing for a period of time. After the material form is fixed, a board blank is obtained; The inorganic compound system is montmorillonite, zinc oxide, and nano-conductive carbon black; (4) Hot pressing and forming: The board blank obtained in step (3) is hot pressed and formed to obtain the functional composite material based on the inorganic compound system.

2. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (1), the screened Salix psammophila wood powder has a particle size of 40 - 60 mesh, the drying temperature is 70 ± 2 °C, and it is dried until the moisture content of the Salix psammophila fibers is below 2%.

3. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (2), the coupling agent is silane coupling agent KH550.

4. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (2), the concentration of the coupling agent solution is 20 wt%, and the dosage of the coupling agent is 2% of the mass of the Salix psammophila fibers.

5. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (2), the drying temperature is 70 ± 2 °C, and it is dried until the moisture content of the modified Salix psammophila fibers is below 2%.

6. The preparation method of a functional composite material based on an inorganic compounding system according to claim 1, characterized in that, In step (3), the mass ratio of the modified Salix psammophila fibers to polylactic acid is 3:7, the addition amount of the inorganic compound system is 3 - 9% of the total mass of the modified Salix psammophila fibers and polylactic acid materials, and the mass ratio of montmorillonite, zinc oxide, and nano-conductive carbon black is (1 - 3):(1 - 3):(1 - 3).

7. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, wherein, In step (3), the mass ratio of the first part and the second part of materials is 3:

7. The modified Salix psammophila fibers, polylactic acid, and inorganic compound system in the first part are stirred and mixed for 5 - 10 min, and the stirring speed is 20 - 30 revolutions per minute. Then the remaining second part of the modified Salix psammophila fibers, polylactic acid, and inorganic compound system are continuously added and stirred and mixed for 5 - 10 min, and the stirring speed is 20 - 30 revolutions per minute.

8. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (3), the pressure for pressing the material is 1 MPa, and the standing time is 10 min.

9. The preparation method of a functional composite material based on an inorganic composite system according to claim 1, characterized in that, In step (4), the hot pressing and forming temperature of the board blank obtained in step (3) is 190 °C, the hot pressing pressure is 7 MPa, and the hot pressing time is 7 min.

10. A functional composite material based on an inorganic composite system prepared by the method according to any one of claims 1-9, characterized in that, The density is 0.80 - 1.20 g / cm 3 .

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