Method for hydrophilic modification of polypropylene fibers and for improving the flexural strength of inorganic terrazzo reinforced with the same based on a BP neural network

Abstract

The application discloses a method for hydrophilic modification of polypropylene fibers and reinforced inorganic terrazzo flexural strength based on BP neural network, which comprises the following steps: 1) preparing modified polypropylene fibers by using ultraviolet lamp and silane coupling agent; 2) screening the optimal modification condition by using BP neural network; and 3) hydrophilic modification of polypropylene fibers reinforced inorganic terrazzo. The method for hydrophilic modification of polypropylene fibers provided by the application screens the optimal modification condition by using BP neural network; the polypropylene fibers are irradiated by using ultraviolet grafting method, so that the chains on the surface of the fibers are degraded, the carbonyl groups are generated, and the surface of the polypropylene fibers is etched to increase the surface roughness; and the surface of the polypropylene fibers is hydrophilically modified by using solution grafting method with anhydrous ethanol, water and silane coupling agent KH-570 solution. The modified polypropylene fibers prepared by using the method have excellent hydrophilic performance, the preparation process is simple, and a new idea is provided for quickly screening the optimal modification condition.

Description

Technical Field

[0001] This invention relates to the field of polypropylene fiber modification, and in particular to a method for hydrophilic modification of polypropylene fibers. Background Technology

[0002] Cement-based terrazzo is economical and possesses advantages such as fire resistance, durability, breathability, and slip resistance. However, it is slightly lacking in gloss, acid resistance, and stain resistance, and its service life is comparable to that of concrete. In the 1950s-1980s, terrazzo was primarily used for non-load-bearing components, focusing on surface smoothness and aesthetic quality. With advancements in materials and manufacturing processes, modern terrazzo is widely used in commercial and residential buildings, mainly for floors and slabs. It not only helps bear structural loads and increases the longitudinal stiffness of the floor system but also improves the lateral stiffness and load-bearing capacity of the floor slab. Therefore, higher requirements are placed on the stiffness and flexural strength of terrazzo. Currently, in the field of architectural design (different from the structural field), ultra-high performance inorganic polymers can achieve high compressive strength, but for thin building components, their flexural strength is usually the primary consideration. In practical applications, the high strength of the ultra-high performance inorganic polymer matrix is ​​often further enhanced and its toughness improved by adding small amounts of inorganic or organic fibers.

[0003] In ordinary cement-based composites, the appropriate addition of polypropylene fibers can effectively prevent early shrinkage and crack propagation in concrete, thus maintaining the superior performance of cement-based composites over a long period. However, polypropylene fibers have low surface polarity and lack polar groups, making them difficult to disperse in cement-based materials. Therefore, improving the polarity of polypropylene fibers and enhancing their bonding with the cement matrix is ​​crucial. To improve the surface polarity of polypropylene fibers and give them good hydrophilicity, hydrophilic modification of the fibers is necessary.

[0004] Currently, there are various methods for modifying polypropylene, mainly divided into physical modification and chemical modification. Physical modification includes blending modification, filler modification, functional modification, and reinforcement modification. Chemical modification methods include copolymerization, degradation, grafting, and crosslinking. Silane coupling agent solution grafting is a commonly used method, but due to the small surface area of ​​the fiber, the amount of silane coupling agent bound to the fiber surface is limited. Therefore, ultraviolet light is used to degrade the chains on the surface of polypropylene fibers, generating hydrophilic carbonyl groups while simultaneously etching the polypropylene fiber surface, increasing its surface roughness and surface area. After the silane coupling agent is hydrolyzed, hydrophilic groups are grafted onto the fiber surface. Polypropylene fibers treated with ultraviolet light have a rougher fiber surface, allowing more silane coupling agent to be loaded onto it, achieving a better hydrophilic modification effect.

[0005] The preparation of inorganic terrazzo typically takes about 30 days, resulting in a long preparation cycle and high material consumption. BP neural network is an error negative feedback neural network, which mainly includes two processes: signal forward propagation and error backward propagation. The network parameters are adjusted by calculating the error between the output layer and the expected value, thereby reducing the error.

[0006] To address these issues, a method based on a BP neural network for hydrophilic modification of polypropylene fibers and its enhancement of the flexural strength of inorganic terrazzo was designed. Summary of the Invention

[0007] The purpose of this invention is to optimize the above-mentioned problems existing in the prior art and provide a method for hydrophilic modification of polypropylene fibers based on BP neural network and its enhancement of the flexural strength of inorganic terrazzo, so as to improve the hydrophilicity of polypropylene fibers, so that the obtained polypropylene fibers have good compatibility in inorganic terrazzo, and can improve the flexural strength of inorganic terrazzo.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network and its enhancement of the flexural strength of inorganic terrazzo, characterized by comprising the following steps:

[0010] Step 1: Preparation of modified polypropylene fibers using ultraviolet lamps and silane coupling agents.

[0011] 1) One-time processing:

[0012] 0.2 g of polypropylene fiber raw material was placed under a UV lamp with a UV wavelength of 200~400 nm and an irradiation time of 40~70 min to obtain UV-modified fiber;

[0013] Alternatively, 0.2 g of polypropylene fiber raw material can be added to a silane coupling agent solution, and the silane coupling agent treatment time can be 30-60 min to obtain silane coupling agent modified fiber.

[0014] 2) Secondary processing:

[0015] 0.2 g of UV-modified fiber was added to a silane coupling agent solution with a volume concentration of 25-40% and a treatment time of 30-60 min to obtain UV-silane coupling agent modified fiber.

[0016] Alternatively, place 0.2 g of silane coupling agent modified fiber under a UV lamp with a UV wavelength of 200~400 nm and an irradiation time of 40~70 min to obtain silane coupling agent-UV modified fiber;

[0017] Step 2: Use a BP neural network to screen for optimal modification conditions

[0018] 1) Place the UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber and polypropylene fiber raw materials obtained in step one into an electric heating drying oven and dry them at 40°C to constant weight. Record the weight of the modified fiber as M0 and the weight of the raw material as m0.

[0019] 2) Place the raw materials of UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and polypropylene fiber at constant weight in air under standard conditions of 70℃ and 65% relative humidity. After absorbing moisture, record the weight of the modified fiber as M1 and the weight of the raw material as m1. Then, according to the formula... Calculate the relative water absorption rate;

[0020] 3) Using UV irradiation time, coupling agent concentration, and coupling agent modification time as input layers, and the relative water absorption rate of modified polypropylene fiber as output layer, the number of hidden layers was set, and a BP neural network prediction model was built using MATLAB software to predict the optimal modification conditions.

[0021] Step 3: Hydrophilic modified polypropylene fiber reinforced inorganic terrazzo

[0022] 1) Dry-mix heavy calcium carbonate, fine sand, quartz sand and Portland cement in a mixer to obtain aggregate;

[0023] 2) Dry mix the stone and UV-modified fiber evenly, then add water-reducing agent and water, and mix thoroughly. Place the mixed mixture into a container. The steel mold was vibrated and the top surface was scraped flat. After curing at room temperature for 48 hours, it was demolded at a temperature not exceeding 40 ℃. After curing for 28 days, the UV-modified fiber-reinforced inorganic terrazzo was obtained.

[0024] Alternatively, the stone and silane coupling agent-modified fiber can be dry-mixed evenly, then water-reducing agent and water can be added and stirred thoroughly. The mixture can then be placed into a container. The steel mold was vibrated and the top surface was scraped flat. After curing at room temperature for 48 hours, it was demolded at a temperature not exceeding 40 ℃. After curing for 28 days, inorganic terrazzo modified with silane coupling agent and reinforced with fiber was obtained.

[0025] Alternatively, the stone can be dry-mixed with UV-silane coupling agent-modified fibers until uniform, then water-reducing agent and water can be added and thoroughly mixed. The mixed mixture can then be placed into... The steel mold was vibrated and the top surface was scraped flat. After curing at room temperature for 48 hours, it was demolded. The temperature did not exceed 40 ℃. After curing for 28 days, the inorganic terrazzo modified by ultraviolet light-silane coupling agent and reinforced by fiber was obtained.

[0026] Alternatively, dry-mix the stone with silane coupling agent-UV modified fiber until uniform, then add water-reducing agent and water, stir thoroughly, and place the mixture into a container. The steel mold was vibrated and the top surface was scraped flat. After curing at room temperature for 48 hours, it was demolded at a temperature not exceeding 40 ℃. After curing for 28 days, inorganic terrazzo reinforced with silane coupling agent-UV light modified fiber was obtained.

[0027] Alternatively, the stone and polypropylene fiber raw materials can be dry-mixed evenly, then water-reducing agent and water can be added and stirred thoroughly. The mixture can then be placed into a container. The steel mold was vibrated and the top surface was scraped flat. After curing at room temperature for 48 hours, it was demolded at a temperature not exceeding 40 ℃. After curing for 28 days, the raw material-reinforced inorganic terrazzo was obtained.

[0028] Furthermore, in step one, the silane coupling agent is prepared by mixing an ethanol solution with anhydrous ethanol and water in a volume ratio of 9:1 and the silane coupling agent. The volume concentration of the silane coupling agent is 25-40%, and the silane coupling agent is KH-570 with a purity of 97%.

[0029] Furthermore, in step two, the number of hidden layers is determined to be 12 according to Kolmogorov's theorem.

[0030] Furthermore, in step two, the Newff function is used to establish a BP neural network prediction model, the Leveberg-Marquardt algorithm is selected as the error algorithm, Trainlim is selected as the training function, the minimum expected mean square error is set to 0.001, the maximum number of iterations and the learning rate are set to 5000 and 0.05 respectively.

[0031] Furthermore, after determining the input and output layers in step two, they are normalized using premnmx to ensure that all results are between 0 and 1. After simulation and training, the data is then denormalized.

[0032] Preferably, in step one, the amount of UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and raw material is 0.2 g each.

[0033] Preferably, in step one, when the ultraviolet light irradiation time is 40 min, the concentration of the silane coupling agent is 25%, and the silane coupling agent treatment time is 30 min.

[0034] Preferably, in step one, when the ultraviolet light irradiation time is 40 min, the concentration of the silane coupling agent is 30%, and the silane coupling agent treatment time is 40 min.

[0035] Preferably, in step one, when the ultraviolet light irradiation time is 50 min, the concentration of the silane coupling agent is 35%, and the silane coupling agent treatment time is 60 min.

[0036] Preferably, in step one, when the ultraviolet light irradiation time is 50 min, the concentration of the silane coupling agent is 40%, and the silane coupling agent treatment time is 50 min.

[0037] Preferably, in step one, when the ultraviolet light irradiation time is 60 min, the concentration of the silane coupling agent is 35%, and the silane coupling agent treatment time is 30 min.

[0038] Preferably, in step one, when the ultraviolet light irradiation time is 60 min, the concentration of the silane coupling agent is 40%, and the silane coupling agent treatment time is 40 min.

[0039] Preferably, in step one, when the ultraviolet light irradiation time is 70 min, the concentration of the silane coupling agent is 25%, and the silane coupling agent treatment time is 60 min.

[0040] Preferably, in step one, when the ultraviolet light irradiation time is 70 min, the concentration of the silane coupling agent is 30%, and the silane coupling agent treatment time is 50 min.

[0041] Preferably, in step one, when the concentration of the silane coupling agent is 35% and the treatment time of the silane coupling agent is 50 min, the ultraviolet irradiation time is 40 min.

[0042] Preferably, in step one, when the concentration of the silane coupling agent is 40% and the treatment time of the silane coupling agent is 60 min, the ultraviolet light irradiation time is 40 min.

[0043] Preferably, in step one, when the concentration of the silane coupling agent is 25% and the treatment time of the silane coupling agent is 40 min, the ultraviolet irradiation time is 50 min.

[0044] Preferably, in step one, when the concentration of the silane coupling agent is 30% and the treatment time of the silane coupling agent is 30 min, the ultraviolet light irradiation time is 50 min.

[0045] Preferably, in step one, when the concentration of the silane coupling agent is 25% and the treatment time of the silane coupling agent is 50 min, the ultraviolet light irradiation time is 60 min.

[0046] Preferably, in step one, when the concentration of the silane coupling agent is 30% and the treatment time of the silane coupling agent is 60 min, the ultraviolet light irradiation time is 60 min.

[0047] Preferably, in step one, when the concentration of the silane coupling agent is 35% and the treatment time of the silane coupling agent is 40 min, the ultraviolet irradiation time is 70 min.

[0048] Preferably, in step one, when the concentration of the silane coupling agent is 40% and the treatment time of the silane coupling agent is 30 min, the ultraviolet light irradiation time is 70 min.

[0049] Preferably, in step two, the amount of UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and raw material is 0.2 g.

[0050] Preferably, in step one, the amount of UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and raw material is 1.7 g.

[0051] Furthermore, in step three, the raw materials for UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and polypropylene fiber are all 1.7 g, and the Portland cement is P·O52.5; the quartz sand in step three uses one of three specifications: 1~3mm, 3~5mm, or 5~7mm; the water-reducing agent in step three is a self-developed high-efficiency water-reducing agent; the water in step three is tap water; among them, the quartz sand is 6 kg, the heavy calcium carbonate and silt is 2 kg, the Portland cement is 2 kg, the water content is 35% of the cement content, and the water-reducing agent content is 10% of the cement content.

[0052] Preferably, the UV modification time in step three is 40 min.

[0053] Preferably, in step three, the volume concentration of the silane coupling agent is 40%, and the modification time of the silane coupling agent is 40 min.

[0054] Preferably, the Portland cement used in step three is P·O 52.5.

[0055] Preferably, the quartz sand in step three has three specifications: 1~3mm, 3~5mm and 5~7mm.

[0056] Preferably, the water-reducing agent in step three is a self-developed high-efficiency water-reducing agent.

[0057] Preferably, the water used in step three is tap water.

[0058] The present invention discloses a method for hydrophilic modification of polypropylene fibers based on BP neural network and its enhancement of the flexural strength of inorganic terrazzo. The method for preparing hydrophilic modification of polypropylene fibers and their enhancement of inorganic terrazzo involves ultraviolet light irradiation modification, which increases the surface roughness of the fibers. After hydrolysis of the silane coupling agent, hydrophilic groups are grafted onto the fiber surface, which improves the hydrophilicity of the fibers and better optimizes the flexural strength of polypropylene fibers in inorganic terrazzo.

[0059] The beneficial effects of this invention are as follows: The method for hydrophilic modification of polypropylene fibers based on BP neural networks and its enhancement of the flexural strength of inorganic terrazzo described in this invention uses a small amount of experimental data to construct a BP neural network model. Using this model, the optimal UV modification time, silane coupling agent volume concentration, and silane coupling agent modification time for hydrophilic modification of polypropylene fibers can be quickly and easily screened. Modified polypropylene fibers prepared under optimal conditions improve the hydrophilicity of the fibers, better optimize the compatibility of polypropylene fibers in inorganic terrazzo, and improve the flexural strength of inorganic terrazzo.

[0060] The method described above, based on a BP neural network, for hydrophilic modification of polypropylene fibers and its enhancement of the flexural strength of inorganic terrazzo, utilizes ultraviolet light to increase the surface roughness and surface area of ​​polypropylene fibers. In an ethanol solution, a silane coupling agent undergoes hydrolysis, generating hydroxyl groups which are simultaneously grafted onto the polypropylene fiber surface, achieving hydrophilicity. During the reaction, the increased surface roughness of the ultraviolet-modified polypropylene fibers allows for a greater loading of silane coupling agent on the fiber surface, ultimately enhancing the hydrophilic modification effect. Attached Figure Description

[0061] Figure 1 The results of the BP neural network in Example 1 on the prediction of the water absorption rate of polypropylene fibers under different ultraviolet light irradiation times, different silane coupling agent concentrations, and different modification times are shown.

[0062] Figure 2 The images show the surface contact angles of the five types of polypropylene fibers used in Example 2: UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and the raw material.

[0063] Figure 3 The image shows the infrared spectra of UV-silane coupling agent modified fibers after different modification times, when the UV irradiation time was 40 min and the silane coupling agent concentration was 30% in Example 3.

[0064] Figure 4 The infrared spectra of UV-silane coupling agent modified fibers with different concentrations are shown in Example 4, where the UV irradiation time is 40 min and the silane coupling agent modification time is 40 min.

[0065] Figure 5The images show SEM images of the surface morphology of the raw materials and modified polypropylene fiber samples prepared in Example 5 (raw materials, UV modification for 40 min, silane coupling agent treatment time of 30 min when the concentration of silane coupling agent is 40%, silane coupling agent treatment time of 30 min after UV modification for 40 min, and silane coupling agent treatment time of 30 min after the concentration of silane coupling agent is 40%).

[0066] Figure 6 AFM micrographs of the surface roughness of the raw material and modified polypropylene fiber sample prepared in Example 6 (raw material, UV modification for 120 min).

[0067] Figure 7 This is a schematic diagram showing the relationship between the different fiber addition amounts of raw materials and UV-silane coupling agent modified fibers in Example 7 and the flexural strength curves of inorganic terrazzo.

[0068] Figure 8 This is a schematic diagram of the flexural strength curves of UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber, and inorganic terrazzo in Example 8. Detailed Implementation

[0069] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The silane coupling agent used in the following embodiments is preferably KH-570 silane coupling agent.

[0070] Example 1

[0071] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0072] Step 1: Preparation of modified polypropylene fibers using ultraviolet lamps and silane coupling agents.

[0073] ① Using raw polypropylene fiber as raw material;

[0074] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 40~70 min to obtain UV-modified fibers;

[0075] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the raw material to the silane coupling agent solution, the volume concentration of the silane coupling agent is 25~40%, the silane coupling agent treatment time is 30~60 min, and silane coupling agent modified fiber is obtained.

[0076] ④ Add the UV-modified fiber to the silane coupling agent solution. The UV wavelength is 300 nm, the irradiation time is 40~70 min, the volume concentration of the silane coupling agent is 25~40%, and the treatment time of the silane coupling agent is 30~60 min to obtain UV-silane coupling agent modified fiber.

[0077] ⑤ Place the silane coupling agent modified fiber under a UV lamp with a UV wavelength of 300 nm for 40-70 min, a silane coupling agent volume concentration of 25-40%, and a silane coupling agent treatment time of 30-60 min to obtain silane coupling agent-UV modified fiber.

[0078] Step 2: Use a BP neural network to screen for optimal modification conditions

[0079] ① Place the UV-modified fiber, silane coupling agent modified fiber, UV-silane coupling agent modified fiber, silane coupling agent-UV modified fiber and raw material from step one into an electric heating drying oven and dry them at 40℃ to constant weight. Record the weight of the modified fiber as M0 and the weight of the raw material as m0.

[0080] ② Place the UV-modified fiber, silane coupling agent-modified fiber, UV-silane coupling agent-modified fiber, silane coupling agent-UV-modified fiber, and raw material in air under standard conditions of 70℉ and 65% relative humidity. After absorbing moisture, record the weight of the modified fiber as M1 and the weight of the raw material as m1. Then, according to the formula... Calculate the relative water absorption rate;

[0081] ③ Using UV irradiation time, coupling agent concentration, and coupling agent modification time as the input layer, and the relative water absorption rate of modified polypropylene fiber as the output layer, the number of hidden layers was set, and a BP neural network prediction model was built using MATLAB software to predict the optimal modification conditions. In this embodiment, the number of hidden layers was determined to be 12 according to Kolmogorov's theorem. The BP neural network prediction model was built using the Newff function, the Leveberg-Marquardt algorithm was selected as the error algorithm, Trainlim was selected as the training function, the minimum expected mean square error was set to 0.001, and the maximum number of iterations and learning rate were set to 5000 and 0.05, respectively. After determining the input and output layers, they were normalized using premnmx to make all results between 0 and 1. After simulation and training, the data were finally denormalized.

[0082] Figure 1 This study demonstrates the prediction results of a BP neural network on the water absorption rate of polypropylene fibers under different UV irradiation times, silane coupling agent concentrations, and modification times. It can be seen that the water absorption rate of unmodified PP is extremely low, with only a small amount of moisture absorbed due to capillary action. Through experiments combined with a model established using a BP neural network, the optimal modification conditions were selected: a UV irradiation time of 40 min, a silane coupling agent concentration of 40% (KH-570), and a modification time of 30 min. Under these conditions, the moisture absorption rate of the modified polypropylene fiber is 564% of that of the original polypropylene fiber.

[0083] Example 2

[0084] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0085] Step 1: Hydrophilic modified polypropylene fiber

[0086] ① Using raw polypropylene fiber as raw material;

[0087] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm for 40 min to obtain UV-modified fibers;

[0088] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the raw material to the silane coupling agent solution, the volume concentration of the silane coupling agent is 40%, the treatment time of the silane coupling agent is 30 min, and silane coupling agent modified fiber is obtained.

[0089] ④ Add the UV-modified fiber to the silane coupling agent solution. The UV wavelength is 300 nm, the irradiation time is 40 min, the volume concentration of the silane coupling agent is 40%, and the silane coupling agent treatment time is 30 min to obtain UV-silane coupling agent modified fiber.

[0090] ⑤ Place the silane coupling agent modified fiber under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 40 min. The volume concentration of the silane coupling agent is 40% and the treatment time of the silane coupling agent is 30 min to obtain silane coupling agent-UV modified fiber.

[0091] like Figure 2 As shown in the figure, (a) is the original PP, (b) is modified PP-UV40, (c) is modified PP-40%SCA30, (d) is modified PP-UV40+40%SCA30, and (e) is modified PP-40%SCA30+UV40. Silane coupling agent modification can significantly enhance the hydrophilicity of polypropylene fibers. The effect is best when silane coupling agent modification is performed after UV irradiation, while UV irradiation after silane coupling agent modification cannot further improve hydrophilicity. Increasing the surface area and surface roughness through UV light is more conducive to the modification of silane coupling agents. When silane coupling agents are grafted onto the surface of polypropylene fibers, polar groups are introduced, and the fiber changes from a non-polar to a polar state, thereby increasing the wettability of its surface and correspondingly decreasing the contact angle.

[0092] Example 3

[0093] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0094] Step 1: Hydrophilic modified polypropylene fiber

[0095] ① Using raw polypropylene fiber as raw material;

[0096] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm for 40 min to obtain UV-modified fibers;

[0097] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the UV-modified fiber to the silane coupling agent solution, the volume concentration of the silane coupling agent is 30%, and the treatment time of the silane coupling agent is 20min / 30min / 40min / 50min to obtain UV-silane coupling agent modified fiber;

[0098] like Figure 3 As shown, the silane coupling agent undergoes both hydrolysis and condensation reactions in ethanol / water solution. At 1070 cm⁻¹ -1The Si-OC bond at this point represents the bond that must be broken during hydrolysis, characterizing the unhydrolyzed Si-O-CH3 groups. These groups will hydrolyze to generate hydrophilic groups, i.e., at 1750 cm⁻¹. -1 The carbonyl peak at [location missing]. When the hydrolysis time exceeds 30 min, this band almost disappears, indicating that the hydrolysis reaction is basically complete, while the peaks at 1015 and 980 cm⁻¹ [are missing]. -1 The presence of the Si-O-Si chain vibration band at this point indicates that the self-condensation reaction of the silane coupling agent is dominant in the solution. Therefore, the optimal time for modifying polypropylene fibers with silane coupling agent can be determined to be 30 min.

[0099] Example 4

[0100] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0101] Step 1: Hydrophilic modified polypropylene fiber

[0102] ① Using raw polypropylene fiber as raw material;

[0103] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm for 40 min to obtain UV-modified fibers;

[0104] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the UV-modified fiber to the silane coupling agent solution, the volume concentration of the silane coupling agent is 20% / 30% / 40% / 50%, the silane coupling agent treatment time is 20 min, and UV-silane coupling agent modified fiber is obtained;

[0105] like Figure 4 As shown, with the increase of silane coupling agent concentration, 1750 cm -1 The carbonyl peak at 1070 cm⁻¹ -1 The increased intensity of the Si-OC peak indicates a more vigorous hydrolysis reaction. The modification effect weakens when the silane coupling agent concentration is 50%. This is because at excessively high concentrations, the water molecules in the solution are insufficient to completely hydrolyze the silane coupling agent. Another reason is the diminishing marginal utility effect, meaning that further increases in coupling agent cannot further enhance the modification effect. Therefore, it can be concluded that a silane coupling agent concentration of 40% yields the best modification effect. These experimental results help determine the optimal silane coupling agent modification conditions, thereby further optimizing the hydrophilic properties of modified polypropylene fibers.

[0106] Example 5

[0107] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0108] Step 1: Hydrophilic modified polypropylene fiber

[0109] ① Using raw polypropylene fiber as raw material;

[0110] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm for 40 min to obtain UV-modified fibers;

[0111] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the raw material to the silane coupling agent solution, the volume concentration of the silane coupling agent is 40%, the treatment time of the silane coupling agent is 30 min, and silane coupling agent modified fiber is obtained.

[0112] ④ Add the UV-modified fiber to the silane coupling agent solution. The UV wavelength is 300 nm, the irradiation time is 40 min, the volume concentration of the silane coupling agent is 40%, and the silane coupling agent treatment time is 30 min to obtain UV-silane coupling agent modified fiber.

[0113] ⑤ Place the silane coupling agent modified fiber under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 40 min. The volume concentration of the silane coupling agent is 40% and the treatment time of the silane coupling agent is 30 min to obtain silane coupling agent-UV modified fiber.

[0114] like Figure 5 As shown in the figure, (a) is the original PP, (b) is the modified PP-UV40, (c) is the modified PP-40%SCA30, (d) is the modified PP-UV40+40%SCA30, and (e) is the modified PP-40%SCA30+UV40. The surface of the unmodified polypropylene fiber is relatively smooth. In contrast, the surface of the polypropylene fiber modified with silane coupling agent becomes rougher and has an obvious deposit layer. This phenomenon is consistent with the size of the surface contact angle. The silane coupling agent can be attached to the fiber surface, which can significantly improve its surface contact angle, thereby achieving the expected modification effect. Figure 5 The results show that the polypropylene fibers modified by ultraviolet light have a larger layer of deposits. This change is likely due to the increased surface roughness of the fibers caused by ultraviolet light irradiation, which promotes the accumulation of silane coupling agents on the fiber surface and increases the amount of coupling agents adhering to the fiber surface. This modification mechanism effectively improves the interfacial compatibility between the fibers and inorganic terrazzo, thereby significantly enhancing the flexural strength and toughness of the inorganic terrazzo.

[0115] Example 6

[0116] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network includes the following steps:

[0117] Step 1: Hydrophilic modified polypropylene fiber

[0118] ① Using raw polypropylene fiber as raw material;

[0119] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 120 min to obtain UV-modified fibers;

[0120] like Figure 6 As shown in Figure (a), the surface of unmodified polypropylene fibers was relatively smooth with minimal undulations and an Ra value of 35.04 nm. However, UV-modified polypropylene fibers exhibited significant surface undulations, with a surface roughness far exceeding that of unmodified fibers, and Ra values ​​reaching the micrometer level (b), (c), and (d). This indicates that UV modification can alter the surface morphology of polypropylene fibers, increasing their surface roughness. This, coupled with the surface contact angle, facilitates the adhesion of the silane coupling agent KH-570 to the polypropylene fiber surface, thereby improving the interfacial bonding between the polypropylene fibers and cement.

[0121] Example 7

[0122] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network and its enhancement of the flexural strength of inorganic terrazzo includes the following steps:

[0123] Step 1: Hydrophilic modified polypropylene fiber

[0124] ① Using raw polypropylene fiber as raw material;

[0125] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm for 40 min to obtain UV-modified fibers;

[0126] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the UV-modified fiber to the silane coupling agent solution, the volume concentration of the silane coupling agent is 40%, the silane coupling agent treatment time is 30 min, and UV-silane coupling agent modified fiber is obtained.

[0127] Step 2: Hydrophilic modified polypropylene fiber reinforced inorganic terrazzo

[0128] ①Put heavy calcium carbonate, fine sand, quartz sand and Portland cement into a mixer and dry mix evenly to obtain aggregate;

[0129] ② Dry mix the stone with the UV-silane coupling agent modified fiber evenly, then add water-reducing agent and water, and mix thoroughly. Place the mixed material into a 32*32*2.5 cm steel mold, vibrate it, and scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test curing for 28 days to obtain inorganic terrazzo reinforced with UV-silane coupling agent modified polypropylene fiber.

[0130] ③ Mix the stone and raw materials evenly, then add water-reducing agent and water, and mix thoroughly. Place the mixed material into a 32*32*2.5 cm steel mold, vibrate it, and scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test curing for 28 days to obtain raw material-reinforced inorganic terrazzo.

[0131] like Figure 7 As shown, with the increase of polypropylene fiber addition, the flexural strength of the unmodified group gradually increased, reaching a maximum at 2 g, and then decreased with further increases in addition. This is because the polypropylene fibers agglomerated, indicating that their surface hydrophobicity is the main factor restricting their application. The flexural strength of the polypropylene fibers modified with coupling agent after UV irradiation reached a maximum at a fiber addition of 1.7 g, indicating that the hydrophilicity of the polypropylene fibers was greatly improved.

[0132] Example 8

[0133] A method for hydrophilic modification of polypropylene fibers based on a backpropagation neural network and its enhancement of the flexural strength of inorganic terrazzo includes the following steps:

[0134] Step 1: Hydrophilic modified polypropylene fiber

[0135] ① Using raw polypropylene fiber as raw material;

[0136] ② Place the raw material under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 40 min to obtain UV-modified fibers;

[0137] ③ Prepare an ethanol solution by mixing anhydrous ethanol and water at a volume ratio of 9:1, add silane coupling agent KH-570 to prepare a silane coupling agent solution, add the raw material to the silane coupling agent solution, the volume concentration of the silane coupling agent is 40%, the treatment time of the silane coupling agent is 30 min, and silane coupling agent modified fiber is obtained.

[0138] ④ Add the UV-modified fiber to the silane coupling agent solution. The UV wavelength is 300 nm, the irradiation time is 40 min, the volume concentration of the silane coupling agent is 40%, and the treatment time of the silane coupling agent is 30 min to obtain the UV-silane coupling agent modified fiber.

[0139] ⑤ Place the silane coupling agent modified fiber under a UV lamp with a UV wavelength of 300 nm and an irradiation time of 40 min. The volume concentration of the silane coupling agent is 40% and the treatment time of the silane coupling agent is 30 min to obtain silane coupling agent-UV modified fiber.

[0140] Step 2: Hydrophilic modified polypropylene fiber reinforced inorganic terrazzo

[0141] ①Put heavy calcium carbonate, fine sand, quartz sand and Portland cement into a mixer and dry mix evenly to obtain aggregate;

[0142] ② Mix the stone material and UV-modified fiber evenly, then add water-reducing agent and water, and stir thoroughly. Place the well-mixed mixture into a 32*32*2.5 cm steel mold, vibrate it, and then scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test curing for 28 days to obtain UV-modified polypropylene fiber reinforced inorganic terrazzo.

[0143] ③ Dry mix the stone with the silane coupling agent KH-570 modified fiber evenly, then add water-reducing agent and water, and mix thoroughly. Place the well mixed material into a 32*32*2.5 cm steel mold, vibrate it and scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test curing for 28 days to obtain inorganic terrazzo reinforced with silane coupling agent modified polypropylene fiber.

[0144] ④ Dry mix the stone with the UV-silane coupling agent modified fiber evenly, then add the water-reducing agent and water, and mix thoroughly. Place the mixed material into a 32*32*2.5 cm steel mold, vibrate it, and then scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test the curing for 28 days to obtain the inorganic terrazzo reinforced with UV-silane coupling agent modified polypropylene fiber.

[0145] ⑤ Dry mix the stone with silane coupling agent-UV modified fiber evenly, then add water-reducing agent and water, and stir thoroughly. Place the well mixed material into a 32*32*2.5 cm steel mold, vibrate it and scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. Test curing for 28 days to obtain inorganic terrazzo reinforced with silane coupling agent-UV modified polypropylene fiber.

[0146] like Figure 8As shown, the flexural strength of UV-modified polypropylene fibers is lower than that of fibers modified with silane coupling agents. This is because the hydrophilic modification effect of UV light is inferior to that of silane coupling agents, and UV light can cause degradation of the fiber surface, thus reducing its mechanical properties to some extent. Polypropylene fibers modified with coupling agents before UV irradiation are slightly stronger than the former, as the coupling agent has completely adhered and UV irradiation does not produce any additional effect. The flexural strength of cement mortar made from polypropylene fibers modified with silane coupling agents after UV irradiation is the highest. The coupling agent can adhere extensively to the fiber surface after UV irradiation, and its hydrophilic groups give the fiber good dispersibility and compatibility in cement, thereby enhancing its flexural strength.

[0147] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers, characterized by comprising the following steps: Step 1: Preparation of modified polypropylene fibers using ultraviolet lamps and silane coupling agents. 1) One-time processing: 0.2 g of polypropylene fiber raw material was placed under a UV lamp with a UV wavelength of 200-400 nm and an irradiation time of 40-70 min to obtain UV-modified fiber. 2) Secondary processing: 0.2 g of UV-modified fiber was added to a silane coupling agent solution with a volume concentration of 25-40% and a treatment time of 30-60 min to obtain UV-silane coupling agent modified fiber. Step 2: Use a BP neural network to screen for optimal modification conditions 1) Place the UV-silane coupling agent modified fiber and polypropylene fiber raw material obtained in step one into an electric heating drying oven and dry them at 40 ℃ to constant weight. Record the weight of the modified fiber as M0 and the weight of the polypropylene fiber raw material as m0. 2) Place the UV-silane coupling agent modified fiber and polypropylene fiber raw material of constant weight in air under standard conditions of 70℃ and 65% relative humidity. After absorbing moisture, record the weight of the modified fiber as M1 and the weight of the polypropylene fiber raw material as m1. Then, according to the formula... Calculate the relative water absorption rate; 3) Using UV irradiation time, coupling agent concentration, and coupling agent modification time as input layers, and the relative water absorption rate of modified polypropylene fiber as output layer, the number of hidden layers was set, and a BP neural network prediction model was built using MATLAB software to predict the optimal modification conditions. Step 3: Hydrophilic modified polypropylene fiber reinforced inorganic terrazzo 1) Mix a certain proportion of heavy calcium carbonate, fine sand, quartz sand and Portland cement in a mixer until uniform to obtain aggregate; 2) Dry mix the stone with the UV-silane coupling agent modified fiber obtained under the optimal modification conditions, then add water-reducing agent and water, and mix thoroughly. Place the well mixed material into a 32×32×2.5 cm steel mold, vibrate it, and scrape the top surface flat. After curing at room temperature for 48 hours, demold it. The temperature should not exceed 40 ℃. After curing for 28 days, the inorganic terrazzo reinforced with UV-silane coupling agent modified fiber is obtained.

2. The method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers according to claim 1, characterized in that, In step one, the silane coupling agent is prepared by mixing an ethanol solution containing anhydrous ethanol and water in a volume ratio of 9:1 with the silane coupling agent. The volume concentration of the silane coupling agent is 25-40%, and the silane coupling agent is KH-570 with a purity of 97%.

3. The method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers according to claim 1, characterized in that, In step two, the number of hidden layers is determined to be 12 according to Kolmogorov's theorem.

4. The method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers according to claim 1, characterized in that, In step two, the Newff function is used to build a BP neural network prediction model. The Levenberg-Marquardt algorithm is selected as the error algorithm, and Trainlim is selected as the training function. The minimum expected mean square error is set to 0.001, and the maximum number of iterations and the learning rate are set to 5000 and 0.05, respectively.

5. The method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers according to claim 1, characterized in that, In step two, the UV irradiation time, coupling agent concentration, and coupling agent modification time are determined as the input layer, and the relative water absorption rate of the modified polypropylene fiber is determined as the output layer. Then, the data is normalized using premnmx so that all results are between 0 and 1. After simulation and training, the data is finally reversed.

6. The method for enhancing the flexural strength of inorganic terrazzo using hydrophilically modified polypropylene fibers according to claim 1, characterized in that, In step three, the UV-silane coupling agent modified fiber is 1.7 g, and the Portland cement is P·O52.5; the quartz sand in step three uses one of three specifications: 1-3mm, 3-5mm, or 5-7mm; the water-reducing agent in step three is a self-developed high-efficiency water-reducing agent; the water in step three is tap water; the quartz sand is 6 kg, the heavy calcium carbonate and silt is 2 kg, the Portland cement is 2 kg, the water content is 35% of the cement content, and the water-reducing agent content is 10% of the cement content.

7. The inorganic terrazzo obtained by the method of reinforcing the flexural strength of inorganic terrazzo with hydrophilic modified polypropylene fibers according to any one of claims 1-6, characterized in that, UV irradiation modification increases the surface roughness of the fiber, thereby increasing the loading of silane coupling agent on the fiber surface. After hydrolysis of the silane coupling agent, hydrophilic groups are grafted onto the fiber surface, improving the hydrophilicity of the fiber and better optimizing the flexural strength of polypropylene fiber in inorganic terrazzo.

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