CN111535020B - Modification method of high-strength high-modulus PAN fiber for concrete - Google Patents
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- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
- D06M11/77—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with silicon or compounds thereof
- D06M11/79—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with silicon or compounds thereof with silicon dioxide, silicic acids or their salts
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/023—Chemical treatment
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- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
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- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- D06M2101/00—Chemical constitution of the fibres, threads, yarns, fabrics or fibrous goods made from such materials, to be treated
- D06M2101/16—Synthetic fibres, other than mineral fibres
- D06M2101/18—Synthetic fibres consisting of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D06M2101/26—Polymers or copolymers of unsaturated carboxylic acids or derivatives thereof
- D06M2101/28—Acrylonitrile; Methacrylonitrile
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Abstract
本发明提供了一种混凝土用高强高模PAN纤维的改性方法，包括如下步骤：S10制备改性PAN纤维，采用碱性极强的端氨基超支化聚合物改性PAN纤维获得超支化聚合物包覆的改性PAN纤维；S20制备纳米SiO2分散液，将第二预设浓度的纳米SiO2溶液搅拌分散2h，超声分散40min，获得所述纳米SiO2分散液；以及S30制备高强高模PAN纤维，将所述改性PAN纤维加入纳米SiO2分散液中反应一定时间后经后续处理获得高强高模PAN纤维。本发明的一种混凝土用高强高模PAN纤维的改性方法，采用氨基超支化聚合物改性PAN纤维，并将纳米二氧化硅接枝到改性PAN纤维表面，极大地提高了PAN纤维在水泥中的融合性、分散性以及纤维‑混凝土间界面结合力。
The invention provides a method for modifying high-strength and high-modulus PAN fibers for concrete, comprising the following steps: S10, preparing modified PAN fibers, and modifying PAN fibers with extremely alkaline amino-terminated hyperbranched polymers to obtain hyperbranched polymers The coated modified PAN fiber; S20 prepares a nano-SiO 2 dispersion, stirs and disperses the nano-SiO 2 solution of the second preset concentration for 2 hours, and disperses ultrasonically for 40 minutes to obtain the nano-SiO 2 dispersion; and S30 prepares a high-strength and high-modulus solution PAN fiber, adding the modified PAN fiber into the nano-SiO 2 dispersion for a certain period of time to obtain high-strength and high-modulus PAN fiber through subsequent treatment. The modification method of high-strength and high-modulus PAN fiber for concrete of the present invention adopts amino hyperbranched polymer to modify PAN fiber, and grafts nano-silica to the surface of modified PAN fiber, which greatly improves the PAN fiber in Fusion, dispersibility, and fiber-concrete interfacial bonding in cement.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to a method for modifying high-strength high-modulus PAN (polyacrylonitrile) fibers for concrete.
Background
The concrete has the characteristics of rich raw materials, low price, simple production process, wide application range and large demand. However, concrete has the characteristics of high compressive strength, poor tensile strength and poor impact resistance. In order to improve the disadvantages of concrete materials such as high brittleness and easy cracking, fibers are generally blended into concrete to improve the tensile strength, cracking resistance and impact resistance of the concrete. The tensile strength, bending resistance, impact strength, elongation and toughness of the concrete are improved mainly due to the high tensile strength and high elongation of the fibers, and the further development of cracks of the matrix concrete is controlled, so that the crack resistance of the concrete is improved. Organic fibers have also been widely used in the concrete field due to their light weight, corrosion resistance, and the like. Common organic fibers include Polyester (PET), polypropylene (PP), Polyethylene (PE), Polyamide (PA), Polyacrylonitrile (PAN), and the like.
Among them, the PAN fiber is one of the most popular fibers for reinforcing concrete due to its high tensile strength and elastic modulus, and strong ultraviolet and high temperature resistance and cold resistance. Many cyano groups (-CN) are arranged on a fiber macromolecular chain, and hydrogen bonds among molecules and in molecules can be formed, so that the molecular chain is tightly arranged, and the chemical stability is good.
Disclosure of Invention
In order to solve the problems, the invention provides a method for modifying high-strength high-modulus PAN fiber for concrete, which adopts amino hyperbranched polymer to modify PAN fiber, and grafts nano-silica on the surface of the modified PAN fiber, thereby greatly improving the fusion property and the dispersity of the PAN fiber in cement and the bonding force of the fiber-concrete interface.
In order to achieve the above purpose, the invention adopts a technical scheme that:
a method for modifying high-strength high-modulus PAN fiber for concrete comprises the following steps: s10, preparing modified PAN fiber, and modifying the PAN fiber by using amino-terminated hyperbranched polymer with extremely strong alkalinity to obtain modified PAN fiber coated by hyperbranched polymer; s20 preparation of nano SiO2Dispersing the second predetermined concentration of nano SiO2Stirring and dispersing the solution for 2h, and performing ultrasonic dispersion for 40min to obtain the nano SiO2A dispersion liquid; s30 preparing high-strength high-modulus PAN fiber, adding the modified PAN fiber into nano SiO2And reacting the dispersion liquid for a certain time, and then carrying out subsequent treatment to obtain the high-strength high-modulus PAN fiber.
Further, the step S10 includes the following steps: s11, dissolving the amino-terminated hyperbranched polymer with the first preset concentration in deionized water, stirring and dispersing for 2 hours to prepare a hyperbranched polymer solution; and S12, placing the PAN fiber and the hyperbranched polymer solution into a hydrothermal reaction kettle, and reacting for a first preset time under a first preset temperature condition to obtain the modified PAN fiber.
Further, the first preset concentration comprises 0.1g/30ml to 1g/30 ml; the first preset temperature is 100-200 ℃, and the first preset time is 2-10 hours.
Further, the second preset concentration comprises 0.1% -6%.
Further, the step S30 includes the following steps: s31 preparing high-strength and high-modulus PAN fiber mixture, and adding the modified PAN fiber into the nano SiO2In the dispersion liquid, reacting for a second preset time at a second preset temperature to obtain the high-strength high-modulus PAN fiber mixture; and S32, preparing the high-strength high-modulus PAN fiber, and cleaning and drying the high-strength high-modulus PAN fiber mixture to obtain the high-strength high-modulus PAN fiber.
Further, the second preset temperature is 25-90 ℃, and the second preset time is 1-9 hours.
And further, adding deionized water into the high-strength high-modulus PAN fiber mixture for cleaning, and placing the mixture into a vacuum oven at 60 +/-5 ℃ for drying for 24 hours to obtain the high-strength high-modulus PAN fiber.
Compared with the prior art, the technical scheme of the invention has the following advantages:
according to the method for modifying the high-strength high-modulus PAN fiber for concrete, disclosed by the invention, the PAN fiber is modified by adopting the amino hyperbranched polymer, and the nano silicon dioxide is grafted to the surface of the modified PAN fiber, so that the fusion property and the dispersity of the PAN fiber in cement and the bonding force of a fiber-concrete interface are greatly improved.
Drawings
The technical solution and the advantages of the present invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings.
FIG. 1 is a flow chart of a method for modifying high-strength high-modulus PAN fiber for concrete according to an embodiment of the invention;
FIG. 2 is a scanning electron microscope image of a high-strength high-modulus PAN fiber obtained in example 4 of the invention;
FIG. 3 is a scanning electron micrograph of the surface of an untreated virgin PAN fiber;
fig. 4 is an infrared spectrum of the amino-terminated hyperbranched polymer, the unmodified PAN fiber, the modified PAN fiber, and the nano-silica powder grafted PAN fiber provided in embodiments 1 to 5 of the present invention;
FIG. 5 is a drawing of the single PAN fiber tensile breaking strength under different modification conditions provided in examples 1-5 and comparative example 1 of the present invention;
FIG. 6 is a drawing force trend chart of examples 1 to 5 of the present invention and comparative example 2.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In this embodiment, a method for modifying a high-strength high-modulus PAN fiber for concrete is provided, as shown in fig. 1, and includes the following steps: preparing modified PAN fiber, namely modifying the PAN fiber by using amino-terminated hyperbranched polymer with extremely strong alkalinity to obtain modified PAN fiber coated by hyperbranched polymer; s20 preparation of nano SiO2Dispersing the second predetermined concentration of nano SiO2Stirring and dispersing the solution for 2h, and performing ultrasonic dispersion for 40min to obtain the nano SiO2A dispersion liquid; s30 preparing high-strength high-modulus PAN fiber, adding the modified PAN fiber into nano SiO2And reacting the dispersion liquid for a certain time, and then carrying out subsequent treatment to obtain the high-strength high-modulus PAN fiber.
The step S10 includes the following steps: s11, dissolving the amino-terminated hyperbranched polymer with the first preset concentration in deionized water, stirring and dispersing for 2 hours to prepare a hyperbranched polymer solution. And S12, placing the PAN fiber and the hyperbranched polymer solution into a hydrothermal reaction kettle, and reacting for a first preset time under a first preset temperature condition to obtain the modified PAN fiber. The first preset concentration comprises 0.1g/30 ml-1 g/30 ml; the first preset temperature is 100-200 ℃, and the first preset time is 2-10 hours.
The hyperbranched polymer is a highly branched dendritic macromolecule which has a three-dimensional spherical space structure, contains a large number of end groups and has an imperfect structure. The hyperbranched polymer becomes a fourth polymer system framework after having a linear structure, a cross-linked structure and a branched structure, and has potential application value in the fields of coatings, additives, medicines, gene transfer agents, nanotechnology, macromolecular construction, supermolecule science and the like. The hyperbranched polymer containing the polyamino is a water-soluble polymer, a plurality of cavities are arranged in the molecule, a plurality of terminal amino groups are arranged outside the molecule, and the hyperbranched polymer is strong alkaline. The hyperbranched polymer is used for surface modification of PAN, so that-CN in the PAN fiber can be hydrolyzed to form carboxyl, and simultaneously, the carboxyl can also react with terminal amino of the hyperbranched polymer to generate amido, so that the hyperbranched polymer is grafted to the surface of the PAN fiber, and the hydrophilicity of the PAN fiber is effectively improved.
Nano SiO2(SiO2NPs) is a nanoscale inorganic chemical material, and has a size range of 1-100 nm, so that the nanoscale inorganic chemical material has a plurality of unique properties, such as optical performance of resisting ultraviolet rays, and can improve the ageing resistance, strength and chemical resistance of other materials. Researches show that the nano-silica particles can fill gaps in cement concrete, reduce the porosity of a transition region and improve the compactness of cement, thereby increasing the strength of the cement, and on the other hand, the nano-silica particles have the volcanic ash activity and can be mixed with Ca (OH) generated in the hydration process of the cement2Reacting to form hydrated calcium silicate (C-S-H) gel, and interweaving the gel into a net structure, thereby obviously improving the defect of a cement-based interface transition zone. The nano particles can also generate a pinning effect at the interface of the cement matrix, and micro cracks are generated in the cement matrix, and the expansion of the micro cracks is reflected and hindered by the nano particles to consume energyIn an amount to limit crack growth and propagation, which can improve the fracture toughness of the cement matrix material.
The second preset concentration in the step S20 is 0.1% to 6%.
The step S30 includes the following steps: s31 preparing high-strength and high-modulus PAN fiber mixture, and adding the modified PAN fiber into the nano SiO2And reacting in the dispersion liquid at a second preset temperature for a second preset time to obtain the high-strength high-modulus PAN fiber mixture. The second preset temperature is 25-90 ℃, and the second preset time is 1-9 hours. And S32, preparing the high-strength high-modulus PAN fiber, and cleaning and drying the high-strength high-modulus PAN fiber mixture to obtain the high-strength high-modulus PAN fiber. And adding deionized water into the high-strength high-modulus PAN fiber mixture for cleaning, and putting the mixture into a vacuum oven at the temperature of 60 +/-5 ℃ for drying for 24 hours to obtain the high-strength high-modulus PAN fiber.
And modifying the PAN fiber by adopting an amino hyperbranched polymer, and grafting the nano silicon dioxide to the surface of the modified PAN fiber. The nitrile groups on the surface of the PAN fiber are hydrolyzed into carboxyl under certain conditions, and can react with the terminal amino group of the amino-terminated hyperbranched polymer, the hyperbranched polymer is used as a carrier, intermolecular hydrogen bonds are used for firmly combining the nano silicon dioxide, so that the nano silicon dioxide is loaded on the fiber, and meanwhile, the silicon dioxide can be combined with hydration products in cement to produce CSH gel, so that the interface bonding force between the fiber and a cement matrix is improved.
Example 1:
(1) weighing about 0.1g of PAN fiber, immersing the PAN fiber into 0.1g/30ml of hyperbranched polymer aqueous solution, placing reactants in a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in a drying oven at 100 ℃, taking out the fiber after placing for 2h, cooling the fiber to room temperature, taking out the fiber, repeatedly washing the fiber with deionized water, and drying the fiber in a vacuum drying oven at 60 ℃ to obtain the modified PAN fiber.
(2) Stirring 30ml of nano silicon dioxide with the concentration of 0.1% for 2 hours, and carrying out ultrasonic treatment for 40min to obtain nano silicon dioxide dispersion liquid.
(3) And (3) putting the modified PAN fiber into the nano silicon dioxide dispersion liquid, oscillating for 1h at 25 ℃, fully washing, and drying in a vacuum oven at 60 ℃ to obtain the high-strength high-modulus PAN fiber.
(4) In the implementation method, the high-strength high-modulus PAN fiber is subjected to a single fiber drawing test: the cement size is 1cm × 1cm × 0.2cm3Water-cement ratio of 0.35: 1, curing time 7 days, and the drawing strength of the modified fiber was measured.
Example 2
(1) Weighing about 0.1g of PAN fiber, immersing the PAN fiber into 1g/30ml of hyperbranched polymer aqueous solution, placing reactants in a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in a 120 ℃ oven, taking out the hydrothermal reaction kettle after placing the hydrothermal reaction kettle for 10 hours, cooling the hydrothermal reaction kettle to room temperature, taking out the PAN fiber, repeatedly cleaning the PAN fiber with deionized water, and drying the PAN fiber in a vacuum drying oven at 60 ℃ to obtain the modified PAN fiber.
(2) Stirring 30ml of nano silicon dioxide with the concentration of 6% for 2 hours at the temperature of 50 ℃, and carrying out ultrasonic treatment for 40min to obtain nano silicon dioxide dispersion liquid.
(3) And (3) putting the modified PAN fiber into the dispersion liquid (2), oscillating for 9h at 90 ℃, fully washing, and drying in a vacuum oven at 60 ℃ to obtain the high-strength high-modulus PAN fiber.
(4) In the implementation method, the high-strength high-modulus PAN fiber is subjected to a single fiber drawing test: the cement size is 1 × 1 × 0.2cm3Water-cement ratio of 0.35: 1, curing time 7 days, and the drawing strength of the modified fiber was measured.
Example 3
(1) Weighing about 0.1g of PAN fiber, immersing the PAN fiber into 0.5g/30ml of hyperbranched polymer aqueous solution, placing reactants in a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in a drying oven at 140 ℃, taking out the fiber after placing for 4h, cooling the fiber to room temperature, taking out the fiber, repeatedly cleaning the fiber with deionized water, and drying the fiber in a vacuum drying oven at 60 ℃ to obtain the modified PAN fiber.
(2) Stirring 30ml of nano silicon dioxide with the concentration of 3% for 2 hours at the temperature of 50 ℃, and carrying out ultrasonic treatment for 40min to obtain nano silicon dioxide dispersion liquid.
(3) And (3) putting the modified PAN fiber into the nano silicon dioxide dispersion liquid, oscillating for 4h at 50 ℃, fully washing, and drying in a vacuum oven to obtain the high-strength high-modulus PAN fiber.
(4) In the implementation method, the high-strength high-modulus PAN fiber is subjected to single fiber drawing measurementTest: the cement size is 1 × 1 × 0.2cm3Water-cement ratio of 0.35: 1, curing time 7 days, and the drawing strength of the modified fiber was measured.
Example 4
(1) Weighing about 0.1g of PAN fiber, immersing the PAN fiber into 0.7g/30ml of hyperbranched polymer aqueous solution, placing reactants in a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in a 160 ℃ oven, taking out the reactant after placing for 6h, cooling the reactant to room temperature, taking out the fiber, repeatedly cleaning the fiber with deionized water, and drying the fiber in a vacuum drying oven at 60 ℃ to obtain the modified PAN fiber. .
(2) Stirring 30ml of nano silicon dioxide with the concentration of 4% for 2 hours at the temperature of 50 ℃, and carrying out ultrasonic treatment for 40min to obtain nano silicon dioxide dispersion liquid.
(3) And (3) putting the modified PAN fiber into the nano silicon dioxide dispersion liquid, oscillating for 4h at 50 ℃, fully washing, and drying in a vacuum oven at 60 ℃ to obtain the high-strength high-modulus PAN fiber.
(4) In the implementation method, the high-strength high-modulus PAN fiber is subjected to a single fiber drawing test: the cement size is 1 × 1 × 0.2cm3Water-cement ratio of 0.35: 1, curing time 7 days, and the drawing strength of the modified fiber was measured.
Example 5
(1) Weighing about 0.1g of PAN fiber, immersing the PAN fiber into 0.8g/30ml of hyperbranched polymer aqueous solution, placing reactants in a hydrothermal reaction kettle, placing the hydrothermal reaction kettle in an oven at 170 ℃, taking out the reactant after placing for 7h, cooling the reactant to room temperature, taking out the fiber, repeatedly cleaning the fiber with deionized water, and drying the fiber in a vacuum drying oven at 60 ℃ to obtain the modified PAN fiber.
(2) Stirring 30ml of nano silicon dioxide with the concentration of 5% for 2h at the temperature of 50 ℃, and carrying out ultrasonic treatment for 40min to obtain nano silicon dioxide dispersion liquid.
(3) And (3) putting the modified PAN fiber into the nano silicon dioxide dispersion liquid, oscillating for 4h at 50 ℃, fully washing, and drying in a vacuum oven at 60 ℃ to obtain the high-strength high-modulus PAN fiber.
(4) In the implementation method, the high-strength high-modulus PAN fiber is subjected to a single fiber drawing test: the cement size is 1 × 1 × 0.2cm3Water-cement ratio of 0.35: 1, curing for 7 days, and measuringThe drawing strength of the modified fiber is improved.
As shown in fig. 2 to fig. 3, fig. 2 shows the PAN surface grafted with nano silica, fig. 3 shows the pure PAN fiber, and it can be seen that the PAN fiber in fig. 2 has a rough surface and obviously has dense nano particles on the surface.
As shown in FIG. 4, the above absorption peak changes indicate that HBP and nano SiO2 particles are successfully grafted on the surface of the fiber.
Comparative example 1
The individual modified PAN fibers were tested for breaking strength and the results are shown in figure 5. With SiO2Improvement of NPs concentration, modified fiber grafting SiO2The higher the amount of NPs, the more the strength is increased.
Comparative example 2
The modified PAN fiber is mixed with water and cement in a ratio of 0.35: 1, the size of the model is 1 × 1 × 0.2cm3The cement of (2) was subjected to a pull test, and the test results are shown in FIG. 6. With SiO2The increase of the NPs concentration and the pull strength are increased, mainly because of SiO2The higher the NPs concentration is, the SiO covered on the fiber surface2The more NPs, the stronger the bonding force with cement.
The above description is only an exemplary embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures or equivalent processes that are transformed by the content of the present specification and the attached drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (7)
1. A method for modifying high-strength high-modulus PAN fiber for concrete is characterized by comprising the following steps:
s10, preparing modified PAN fiber, and modifying the PAN fiber by using amino-terminated hyperbranched polymer with extremely strong alkalinity to obtain modified PAN fiber coated by hyperbranched polymer;
s20 preparation of nano SiO2Dispersing the second predetermined concentration of nano SiO2Stirring and dispersing the solution for 2h, and performing ultrasonic dispersion for 40min to obtain the nano SiO2A dispersion liquid; and
s30 preparing high-strength high-modulus PAN fiber, adding the modified PAN fiber into nano SiO2And reacting the dispersion liquid for a certain time, and then carrying out subsequent treatment to obtain the high-strength high-modulus PAN fiber.
2. The method for modifying high-strength high-modulus PAN fiber for concrete according to claim 1, wherein the step S10 comprises the steps of:
s11, dissolving the amino-terminated hyperbranched polymer with the first preset concentration in deionized water, stirring and dispersing for 2 hours to prepare a hyperbranched polymer solution; and
s12, placing the PAN fiber and the hyperbranched polymer solution into a hydrothermal reaction kettle, and reacting for a first preset time under a first preset temperature condition to obtain the modified PAN fiber.
3. The method for modifying high-strength high-modulus PAN fiber for concrete according to claim 2, wherein the first predetermined concentration comprises 0.1g/30ml to 1g/30 ml; the first preset temperature is 100-200 ℃, and the first preset time is 2-10 hours.
4. The method for modifying high-strength high-modulus PAN fiber for concrete according to claim 1, wherein the second predetermined concentration comprises 0.1% to 6%.
5. The method for modifying high-strength high-modulus PAN fiber for concrete according to claim 1, wherein the step S30 comprises the steps of:
s31 preparing high-strength and high-modulus PAN fiber mixture, and adding the modified PAN fiber into the nano SiO2In the dispersion liquid, reacting for a second preset time at a second preset temperature to obtain the high-strength high-modulus PAN fiber mixture; and
s32, preparing high-strength high-modulus PAN fiber, and cleaning and drying the high-strength high-modulus PAN fiber mixture to obtain the high-strength high-modulus PAN fiber.
6. The method for modifying high-strength high-modulus PAN fiber for concrete according to claim 5, wherein the second preset temperature comprises 25-90 ℃ and the second preset time comprises 1-9 hours.
7. The method for modifying the high-strength high-modulus PAN fiber for concrete according to claim 5, wherein the high-strength high-modulus PAN fiber mixture is washed by deionized water to remove impurities, and is dried in a vacuum oven at 60 +/-5 ℃ for 24 hours to obtain the high-strength high-modulus PAN fiber.
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