Self-healing material for microcracks in oil well cement stone, and preparation method therefor and use thereof
Patent Information
- Application Number
- PCT/CN2026/087847
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-27
- Filing Date
- 2026-04-01
- Publication Date
- 2026-09-03
Smart Images
Figure CN2026087847_03092026_PF_FP_ABST
Abstract
Description
A self-healing material for microcracks in cementing stone, its preparation method and application Technical Field
[0001] This invention relates to the field of oil and gas well cementing engineering technology, specifically to a self-healing material for micro-cracks in cementing stone, its preparation method, and its application. Background Technology
[0002] The integrity of the cement sheath itself, the integrity of the interface seal, and the integrity of the cement sheath corrosion are among the key technologies for ensuring the successful geological utilization and storage of carbon dioxide. During carbon dioxide storage, carbon dioxide dissolved in formation water generates carbonic acid and decomposes into carbonate, bicarbonate, and hydrogen ions, making the formation water weakly acidic. This can severely affect the performance of the oil well cement stone. In addition, the injection of supercritical carbon dioxide and interface mud cake can easily create micro-annular gaps between the cement sheath and the casing or wellbore, potentially leading to carbon dioxide formation water channeling and carbon dioxide leakage.
[0003] Preventing carbon dioxide from escaping from the wellbore after sealing is one of the key technologies requiring further research. Incorporating self-healing materials with low particle size into cementing fluid systems can seal leakage channels when micro-cracks or interfacial micro-annulus exist in the cement stone, as these materials expand upon contact with carbon dioxide, formation water, and carbon dioxide gas. This is undoubtedly significant for the long-term sealing of carbon dioxide. However, to date, no self-healing material has been found that can expand upon contact with carbon dioxide, formation water, and carbon dioxide gas in cementing fluids. Summary of the Invention
[0004] The purpose of this invention is to develop a self-healing material for microcracks in cementing stone, its preparation method, and its application. This material has the function of expanding when exposed to water and carbon dioxide gas under weak acid conditions. When this self-healing material is applied to the cementing fluid system, it has both expansion and self-healing functions.
[0005] The self-repairing cement stone microcrack material of the present invention, by weight, comprises the following raw materials: 30 parts deionized water, 3-12 parts monomer, 0.03-0.09 parts crosslinking agent, 0.06-0.3 parts initiator, 3-20 parts natural latex, 1.5-3 parts surfactant, and 0.03-1.5 parts filler.
[0006] The monomer is acrylamide, diethylaminoethyl methacrylate, or dimethylaminoethyl methacrylate, preferably dimethylaminoethyl methacrylate.
[0007] The crosslinking agent is N,N-methylenebisacrylamide.
[0008] The initiator is ammonium persulfate or potassium persulfate.
[0009] The natural latex comes from Taihua Rubber (Public) Co., Ltd. This latex is a viscous, milky-white liquid that flows from rubber trees. At 25°C, its pH is 10.50, its ammonia content is 0.69%, and it also contains small amounts of volatile fatty acids, magnesium, etc., with a solid content of 60%. Natural latex not only expands upon contact with carbon dioxide but also increases tensile strength.
[0010] The surfactant is a nonionic surfactant; the nonionic surfactant is an alkylphenol polyoxyethylene ether or a cocoamide polyoxyethylene ether.
[0011] The filler is hydrophilic nano-silica produced by the sol-gel method.
[0012] This invention further provides a method for preparing a self-healing material for microcracks in cementing stone, which is prepared by emulsion copolymerization and includes the following steps:
[0013] (1) Mix deionized water, natural latex and surfactant, and stir until homogeneous to obtain solution I;
[0014] (2) Mix deionized water and filler, stir well to obtain solution II;
[0015] (3) Mix deionized water, initiator, monomer, and crosslinking agent, stir to dissolve, and obtain solution III;
[0016] (4) Add solution I and solution II to solution III and stir evenly. Under anaerobic conditions, heat to 50-80℃ and let it stand to react. After the reaction is complete, process the product into powder, which is the self-healing material.
[0017] In this invention, the synthesized product is in a colloidal state, making it difficult to pulverize into micron-sized particles using vacuum drying. Therefore, this invention further investigates methods for processing the product into powder, taking into account its properties. The product can be processed into powder using the following two methods:
[0018] Method 1: The product is processed into powder using a centrifugal spray dryer, with a feed rate of 10% and an inlet temperature of 110℃. This method requires the addition of deionized water to form a liquid before spray drying, and the amount of powder obtained in a single test is relatively small.
[0019] Method 2: After drying and heating the product into a solid block, cut it into small pieces. Add 20% (by weight of solid) of silica as a separator, and then pulverize it into powder using a liquid nitrogen pulverizer at a temperature of -80 to -120°C. Preferably, the material is pulverized twice using a liquid nitrogen pulverizer, resulting in a particle size of less than 70 mesh. In this process, the product, after being heated into a solid block and cut into large particles, cannot be directly pulverized using a liquid nitrogen pulverizer; otherwise, the large particles will easily stick together and clog the equipment. A certain amount of silica must be added as a separator before pulverizing using a liquid nitrogen pulverizer.
[0020] This invention further applies the self-healing material to cementing fluid, allowing it to be directly added as a component with both expansion and self-healing functions. The self-healing material obtained using the processing method described in this invention has a small particle size, resulting in a more uniform distribution in the cementing fluid. This avoids the problem of excessively large particle size causing some areas to absorb water and expand, thus affecting the performance of the cement stone. It also avoids the problem of excessively large particle size affecting the pore structure of the cement stone, thereby impacting its strength.
[0021] In this invention, the initiator decomposes into free radicals in deionized water and diffuses into micelles or initiates polymerization in latex particles. During graft copolymerization, rubber molecules and monomers undergo copolymerization. At the end of the polymerization reaction, the core of the resulting latex particle is mainly composed of rubber molecules, while the outer layer is composed of the product formed by the polymerization of the graft polymer and monomers. In this material, dimethylaminoethyl methacrylate determines the swelling ratio of the self-healing material in weak acid, while natural latex determines the swelling ratio in carbon dioxide. The working principle is as follows: dimethylaminoethyl methacrylate in the self-healing material undergoes a tertiary amine matrix protonation reaction in low pH solutions, resulting in swelling; additionally, the self-healing material contains natural latex, and when carbon dioxide gas permeates into the self-healing material, it causes changes in the cross-linking network, thereby producing swelling.
[0022] During the material synthesis process, it was discovered that directly mixing the monomers with latex resulted in rapid demulsification, forming large, gel-like masses. This is because latex particles carry a negative charge, while dimethylaminoethyl methacrylate (DMC) has amphoteric properties, easily destabilizing the emulsion system and leading to gelation. Using surfactants can improve the stability of the latex, ensuring the normal progress of the synthesis reaction. Fillers can alter the physical properties of the synthesized product, improve its mechanical properties, and reduce costs.
[0023] The self-healing material obtained using this invention has a high liquid absorption rate in weakly acidic solutions, a high expansion rate when exposed to carbon dioxide, and excellent mechanical properties.
[0024] Compared with the prior art, the advantages of the present invention are:
[0025] (1) This invention uses specific raw materials and proportions, supplemented by corresponding preparation methods, to achieve graft copolymerization of monomers and rubber molecules, and obtains a self-healing material with high liquid absorption ratio in weakly acidic solutions, high expansion ratio when exposed to carbon dioxide, and excellent mechanical properties. Moreover, the preparation process is safe and reliable.
[0026] (2) The self-healing material described in this invention can be directly applied to cementing fluid systems for use in supercritical CO2 and CO2 formation water corrosive media environments in a wet environment, thereby sealing the wellbore leakage channel and improving the sealing integrity of the wellbore. Attached Figure Description
[0027] Figure 1 shows the expansion ratio of the self-healing materials obtained in the examples and comparative examples in solutions with different pH values;
[0028] Figure 2 shows the expansion ratio of the self-healing materials obtained in the examples and comparative examples when exposed to carbon dioxide;
[0029] Figure 3 shows the tensile strength of the self-healing materials obtained in the examples and comparative examples. Detailed Implementation
[0030] These embodiments are provided to make the objectives and technical solutions of the present invention more thorough and complete. The embodiments are only for explaining the present invention, and all raw materials used are commercially available.
[0031] Example 1
[0032] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 5g acrylamide, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, 2g alkylphenol polyoxyethylene ether, and 0.1g nano silica.
[0033] Its preparation method is as follows:
[0034] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of alkylphenol polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I;
[0035] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II;
[0036] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 5g of acrylamide and 0.03g of N,N'-methylenebisacrylamide and stir evenly to obtain solution III.
[0037] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the obtained product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0038] Example 2
[0039] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 5g diethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, 2g cocoamide polyoxyethylene ether, and 0.1g nano silica.
[0040] Its preparation method is as follows:
[0041] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0042] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II;
[0043] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 5g of diethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0044] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the obtained product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0045] Example 3
[0046] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 5g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, 2g cocoamide polyoxyethylene ether, and 0.1g nano silica.
[0047] Its preparation method is as follows:
[0048] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0049] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II;
[0050] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 5g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0051] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the obtained product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0052] Example 4
[0053] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.2g ammonium persulfate, 5g natural latex, 2g cocoamide polyoxyethylene ether, and 0.3g nano silica.
[0054] Its preparation method is as follows:
[0055] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0056] (2) Add 10g of deionized water and 0.3g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II.
[0057] (3) Add 10g of deionized water and 0.2g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0058] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0059] Example 5
[0060] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 10g dimethylaminoethyl methacrylate, 0.09g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, 2g cocoamide polyoxyethylene ether, and 0.3g nano silica.
[0061] Its preparation method is as follows:
[0062] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0063] (2) Add 10g of deionized water and 0.5g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II.
[0064] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.09g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0065] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 8 hours. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0066] Example 6
[0067] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 10g natural latex, 2g cocoamide polyoxyethylene ether, and 0.1g nano silica.
[0068] Its preparation method is as follows:
[0069] (1) Add 10g of deionized water and 10g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0070] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II.
[0071] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0072] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 8 hours. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0073] Example 7
[0074] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 20g natural latex, 2g cocoamide polyoxyethylene ether, and 0.1g nano silica.
[0075] Its preparation method is as follows:
[0076] (1) Add 10g of deionized water and 20g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0077] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II.
[0078] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0079] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0080] Comparative Example 1
[0081] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 30g deionized water, 5g N-(3-dimethylaminopropyl)methacrylamide, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, 2g cocoamide polyoxyethylene ether, and 0.1g nano silica.
[0082] Its preparation method is as follows:
[0083] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0084] (2) Add 10g of deionized water and 0.1g of nano-silica to another beaker, and stir evenly with a magnetic stirrer to obtain solution II;
[0085] (3) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 5g of N-(3-dimethylaminopropyl)methacrylamide and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution III.
[0086] (4) Add solution I and solution II to solution III and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the obtained product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0087] Comparative Example 2
[0088] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 20g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g natural latex, and 2g cocoamide polyoxyethylene ether.
[0089] Its preparation method is as follows:
[0090] (1) Add 10g of deionized water and 5g of natural latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0091] (2) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution II.
[0092] (3) Add solution I to solution II and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0093] Comparative Example 3
[0094] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 20g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g styrene-butadiene latex, and 2g cocoamide polyoxyethylene ether.
[0095] Its preparation method is as follows:
[0096] (1) Add 10g of deionized water and 5g of styrene-butadiene latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0097] (2) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution II.
[0098] (3) Add solution I to solution II and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After that, there is still some white emulsion in the beaker. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0099] Comparative Example 4
[0100] A self-repairing material for microcracks in cementing stone, by weight, comprises the following raw materials: 20g deionized water, 10g dimethylaminoethyl methacrylate, 0.03g N,N'-methylenebisacrylamide, 0.1g ammonium persulfate, 5g styrene-acrylic latex, and 2g cocoamide polyoxyethylene ether.
[0101] Its preparation method is as follows:
[0102] (1) Add 10g of deionized water and 5g of styrene-acrylic latex to a beaker, add 2g of cocoamide polyoxyethylene ether and stir evenly with a magnetic stirrer to obtain solution I.
[0103] (2) Add 10g of deionized water and 0.1g of ammonium persulfate to the reaction vessel and stir with a magnetic stirrer to dissolve them. Then add 10g of dimethylaminoethyl methacrylate and 0.03g of N,N'-methylenebisacrylamide and stir until homogeneous to obtain solution II.
[0104] (3) Add solution I to solution II and stir evenly. After deoxygenation with nitrogen, let it stand in a water bath at 65°C for 6 hours. After that, there is still some white emulsion in the beaker. After the reaction is complete, heat the product in a drying oven at 100°C until it becomes a solid block, cut it into small pieces, add 20% by weight of silica as a separator, and then crush it into granules using a liquid nitrogen pulverizer at -100°C.
[0105] Experimental Example
[0106] The method for determining the liquid absorption ratio of self-healing materials is as follows:
[0107] Considering the application environment of the self-healing material, the test temperature for the liquid absorption ratio was set at 70℃. The test procedure was as follows: the pH of the test liquid was adjusted with glacial acetic acid and sodium hydroxide respectively; a 500-mesh nylon bag was moistened with the test liquid; a certain mass (m0) of sample particles was weighed and placed into the nylon bag, and the total mass of the nylon bag and the sample (m1) was weighed; the test liquid was poured into a container, and the nylon bag and the sample were placed in it; after soaking for 3 days, the nylon bag was removed, the moisture in the nylon bag was absorbed with a paper towel, and the total mass of the nylon bag and the sample (m2) was weighed. The liquid absorption expansion ratio of the self-healing material is Q=(m2-m1) / m0, and the test results are shown in Figure 1.
[0108] The method for evaluating the expansion ratio of self-healing materials when exposed to carbon dioxide gas is as follows:
[0109] After drying, the self-healing material was neatly cut into small pieces, and the sample mass M1 was weighed. The length, width, and height of the sample were measured with vernier calipers, and the volume V1 was calculated. Then, the sample was fixed in an intermediate container and a vacuum was drawn. The intermediate container was equipped with a pressure gauge, and CO2 gas at 5 MPa was introduced into the intermediate container. After one day, the sample was taken out, and the sample mass M2 was weighed again. The sample mass expansion factor P = (M2 - M1) / M1. However, it was found that the mass of the samples in the examples and comparative examples did not change much after the introduction of carbon dioxide. In addition, the sample after expansion due to the introduction of carbon dioxide was placed below the liquid level in a graduated cylinder containing a certain amount of deionized water, and the change in liquid level was observed. The volume expansion factor of the self-healing material in the presence of carbon dioxide gas was calculated from this. The test results are shown in Figure 2.
[0110] The mechanical property testing methods for self-healing materials are as follows:
[0111] After drying, the self-healing material was cut into rectangular strips of 30mm × 3mm × 5mm. The mechanical properties of the self-healing material samples were tested using a ZQ990 tensile testing machine. The maximum range of the testing machine was 2kN, the tensile rate was set to 50mm / min, and the experimental environment temperature was room temperature. Three samples were tested in each group, and the average value of the test results was taken. The stress (σ) was calculated by dividing the test tensile force (F) by the initial cross-sectional area (S0), σ = F / S0. The test results are shown in Figure 3.
[0112] Examples 1-3, Example 7, and Comparative Examples 1-4 show that the type and amount of monomers and latex added have a significant impact on the liquid absorption ratio of the self-healing material in a weakly acidic solution. Figures 2 and 3 show that the amount of natural latex added is the main factor affecting the expansion ratio and tensile strength of the self-healing material upon exposure to carbon dioxide. Examples 3-5 and Comparative Example 2 show that the amounts of crosslinking agent, initiator, and filler added have a certain impact on the expansion ratio and tensile strength of the self-healing material upon exposure to carbon dioxide. In Example 7, 20g of natural latex, 10g of dimethylaminoethyl methacrylate, and 0.1g of nano-silica were added. The resulting self-healing material exhibited a high liquid absorption ratio in a weakly acidic solution, with an expansion ratio exceeding 35 times upon exposure to carbon dioxide and a tensile strength reaching 0.7MPa.
[0113] The embodiments of the present invention are described illustratively and are not limited to the disclosed contents. Modifications and alterations made by those skilled in the art without departing from the technical solutions of the present invention are still within the protection scope of the present invention.
Claims
1. A self-healing material for micro-cracks in cementing stone, characterized in that, By weight, its raw material composition is as follows: 30 parts deionized water, 3-12 parts monomer, 0.03-0.09 parts crosslinking agent, 0.06-0.3 parts initiator, 3-20 parts natural latex, 1.5-3 parts surfactant, and 0.03-1.5 parts filler.
2. The self-healing material for micro-cracks in cementing stone according to claim 1, characterized in that, The monomer is acrylamide, diethylaminoethyl methacrylate, or dimethylaminoethyl methacrylate.
3. The self-healing material for micro-cracks in cementing stone according to claim 1, characterized in that, The crosslinking agent is N,N'-methylenebisacrylamide.
4. The self-healing material for micro-cracks in cementing stone according to claim 1, characterized in that, The initiator is ammonium persulfate or potassium persulfate.
5. The self-healing material for micro-cracks in cementing stone according to claim 1, characterized in that, The surfactant is a nonionic surfactant.
6. The self-healing material for micro-cracks in cementing stone according to claim 1, characterized in that, The filler is hydrophilic nano-silica.
7. A method for preparing a self-healing material for microcracks in cementing stone according to any one of claims 1-6, characterized in that, The preparation method is emulsion copolymerization, including the following steps: (1) Mix deionized water, natural latex and surfactant, and stir until homogeneous to obtain solution I; (2) Mix deionized water and filler, stir well to obtain solution II; (3) Mix deionized water, initiator, monomer, and crosslinking agent, stir to dissolve, and obtain solution III; (4) Add solution I and solution II to solution III and stir evenly. Under anaerobic conditions, heat to 50-80℃ and let the reaction stand. After the reaction is complete, process the product into powder, which is the self-healing material.
8. The method for preparing a self-repairing material for microcracks in cementing stone according to claim 7, characterized in that, The product was processed into powder using a centrifugal spray dryer with a feed rate of 10% and an inlet temperature of 110℃.
9. The method for preparing a self-repairing material for microcracks in cementing stone according to claim 7, characterized in that, The process of processing the product into powder is as follows: the product is dried and heated into a solid block, then cut into small pieces, 20% of the solid mass of silica is added for isolation, and then pulverized into powder using a liquid nitrogen pulverizer at a temperature of -80 to -120℃.
10. The application of the self-healing cementitious stone microcrack material according to any one of claims 1-6 in cementing fluid.