A high-performance adhesive impregnating carbon fiber and its curing method

Abstract

This invention belongs to the field of construction. It discloses a high-performance adhesive for impregnating carbon fibers and its curing method. The adhesive consists of 100 parts by weight of water glass, 50-100 parts by weight of a concrete interface treatment agent, and 1-2 parts by weight of a defoamer. The carbon fibers are impregnated in the adhesive for 10 minutes, then removed, straightened, and fixed. The curing time is no less than 3 days within the range of 5-25°C, and no less than 2 days above 25°C. After curing, this high-performance adhesive exhibits excellent water resistance, alkali resistance, and high-temperature resistance. Therefore, carbon fiber bundles impregnated with this adhesive, even after immersion in water or alkaline solutions, or in high-temperature environments, can maintain their mechanical properties unchanged.

Description

Technical fields:

[0001] This invention is applicable to the construction field, and particularly relates to a high-performance adhesive impregnating carbon fiber and a curing method thereof. Background technology:

[0002] Carbon Textile Reinforced Concrete (CTRC) is a lightweight, high-strength composite material with a very thin profile, making it suitable for structural reinforcement. To further enhance the mechanical properties of the carbon fiber mesh, it needs to be impregnated with an adhesive to ensure the internal carbon fiber filaments work together to bear the load. Currently, epoxy resin is commonly used as the adhesive. However, epoxy resin has poor high-temperature resistance; its glass transition temperature is generally below 100℃. Above its glass transition temperature, epoxy resin softens and loses its adhesive strength, preventing the fibers from working together to bear the load. Epoxy resin also has poor long-term chemical temperature stability; and after curing, it becomes brittle, exhibiting poor crack resistance and impact resistance.

[0003] Water glass is a commonly used adhesive in the construction industry, offering advantages such as low cost and good high-temperature resistance. However, its poor water and alkali resistance makes it unsuitable for use in concrete environments. Furthermore, cured water glass is brittle and exhibits poor crack and impact resistance. According to the invention of Du Yunxing et al., "A Curing Method for Inorganic Adhesive Impregnation of Carbon Fibers" (Chinese Invention Patent CN113277824A), adding a certain amount of sodium methylsilicate to water glass can improve its water resistance and also provides a good impregnation effect on carbon fibers. However, the water resistance of this modified water glass is limited, and its bonding performance in water only lasts for a few hours. Even for early-strength geopolymer concrete, steam curing at 80℃ requires at least one day to complete the reaction. Therefore, carbon fibers impregnated with the aforementioned modified water glass and cured cannot be used in concrete. Summary of the Invention:

[0004] To address the aforementioned problems, this invention provides a high-performance adhesive for impregnating carbon fibers and a curing method thereof. After curing, this high-performance adhesive exhibits excellent water resistance, alkali resistance, and high-temperature resistance. Therefore, carbon fiber bundles impregnated with this adhesive, even after being immersed in water or alkaline solutions, or subjected to high-temperature environments, can maintain their mechanical properties unchanged.

[0005] To achieve the above-mentioned technical effects, the technical solution of the present invention is as follows:

[0006] A high-performance adhesive impregnating carbon fiber and a method for curing the same, comprising the following steps:

[0007] Step 1: Weigh 100 parts by weight of water glass, 50-100 parts by weight of concrete interface treatment agent, and 1-2 parts by weight of defoamer;

[0008] Step 2: Stir the water glass, concrete interface treatment agent, and defoamer at a speed of 200 r / min for at least 5 minutes to obtain the carbon fiber impregnation adhesive.

[0009] Step 3: Immerse the carbon fiber cloth in the carbon fiber impregnation adhesive for 10 minutes. Remove the cloth, straighten it, and fix it. The curing time should be no less than 3 days within the range of 5-25℃. If the temperature is above 25℃, the curing time should be no less than 2 days.

[0010] A further improvement is made to the water glass modulus, which is 2.8 to 3.3.

[0011] A further improvement is that the concrete interface treatment agent is a water-soluble concrete interface treatment agent. The tensile bond strength of the concrete interface treatment agent after curing for 14 days is not less than 0.8 MPa. The tensile bond strength of the concrete interface treatment agent after curing for 7 days and immersing in water for 7 days is not less than 0.7 MPa. The tensile bond strength of the concrete interface treatment agent after curing for 7 days and placing it in an oven at (70±2℃) for 7 days is not less than 0.7 MPa.

[0012] Advantages of this invention:

[0013] (1) Low cost

[0014] Water glass is inexpensive, while concrete interface treatment agents are slightly more expensive, but still cheaper than epoxy resin. When mixed, the two form a liquid that does not harden over a long period after sealing, allowing for repeated use.

[0015] (2) Save time

[0016] The curing time of epoxy resin is limited by temperature, and it takes 5 to 7 days to fully harden in autumn and winter, while this adhesive only takes 2 to 3 days to harden.

[0017] (3) Easy to operate

[0018] Water-based concrete interface treatment agent is selected. After mixing with water glass, only stirring is required. The adhesive is in a liquid state before curing. It can be used to treat carbon fiber not only by impregnation, but also by brushing when conditions do not permit.

[0019] (4) Good water and alkali resistance

[0020] Compared to water glass, this adhesive can be used in water and alkaline environments, ensuring the coordinated force between the fibers.

[0021] (5) Good high temperature resistance

[0022] Compared to epoxy resin, this adhesive can maintain high bonding strength at high temperatures, and the tensile strength of the fiber bundles impregnated with this adhesive does not decrease significantly at high temperatures. Attached image description:

[0023] Figure 1 This is a cross-section of the carbon fiber bundle processed in this invention.

[0024] Figure 2 The tensile strength values ​​of carbon fiber bundles in Example 1 are the average tensile strength values ​​after immersion in water for 1, 2, and 4 days, and after soaking in alkali for 1, 2, and 4 days.

[0025] Figure 3 The stress-strain curves of the carbon fiber bundle placed in the geopolymer environment in Example 2 are shown.

[0026] Figure 4 It is a Type D Shore hardness tester.

[0027] Figure 5 The tensile strength of carbon fiber bundles impregnated with different proportions of adhesive in Example 3, the average tensile strength after immersion in water for 1 day, and the Shore hardness of the adhesive are shown.

[0028] Figure 6 The stress-strain curves of the carbon fiber bundle in Example 4 under tensile testing at 100°C are shown.

[0029] Figure 7 The stress-strain curves of the carbon fiber bundle in Example 4 under tensile testing at 200°C are shown. Detailed implementation method:

[0030] The technical solution of the present invention will be described below through specific embodiments.

[0031] Example 1

[0032] A high-performance adhesive impregnating carbon fiber and a method for curing the same, comprising the following steps:

[0033] Step 1: Weigh out 100g of sodium silicate, 100g of concrete interface treatment agent, and 2g of defoamer;

[0034] Step 2: Stir the sodium silicate, concrete interface treatment agent, and defoamer at a speed of 200 r / min for at least 5 minutes to obtain the carbon fiber impregnation adhesive.

[0035] Step 3: Immerse a bundle of radial carbon fibers in carbon fiber impregnation resin for 10 minutes. After removing it, straighten and fix the carbon fiber bundle and wait for it to cure (curing time is not less than 3 days in the range of 5 to 25℃, and not less than 2 days above 25℃).

[0036] Step 4: Use an MTS universal testing machine to perform tensile tests on the carbon fiber bundles to test their tensile strength. Place the carbon fiber bundles in water and 3% NaOH solution for 1 day, 2 days, and 4 days, respectively. After removing them and drying them, perform tensile tests to test their tensile properties.

[0037] like Figure 2 As shown: The tensile strength of the specimen without water / alkali immersion was (3024±350) MPa. The tensile strengths after water immersion for 1, 2, and 4 days were (2980±323) MPa, (2947±325) MPa, and (2936±465) MPa, respectively. The tensile strengths after alkali immersion for 1, 2, and 4 days were (2927±283) MPa, (2929±189) MPa, and (2925±389) MPa, respectively.

[0038] Example 2

[0039] A high-performance adhesive impregnating carbon fiber and a method for curing the same, comprising the following steps:

[0040] Step 1: Weigh out 100g of sodium silicate, 100g of concrete interface treatment agent, and 2g of defoamer;

[0041] Step 2: Stir the sodium silicate, concrete interface treatment agent, and defoamer at a speed of 200 r / min for at least 5 minutes to obtain the carbon fiber impregnation adhesive.

[0042] Step 3: Immerse a bundle of radial carbon fibers in carbon fiber impregnation resin for 10 minutes. After removing it, straighten and fix the carbon fiber bundle. It can be used after curing (curing time is not less than 3 days in the range of 5-25℃, and not less than 2 days above 25℃).

[0043] Step 4: Wrap the carbon fiber bundles with geopolymer slurry, and conduct a tensile test to test their tensile properties after 1 day.

[0044] like Figure 3 As shown: The tensile strength of the specimen after 1 day in a geopolymer environment was (3000±269) MPa.

[0045] Example 3

[0046] The steps are the same as in the previous two examples, but the mass ratio of sodium silicate to concrete interface treatment agent is changed, and the composition of each component is as follows:

[0047] Sodium silicate mass : Concrete interface treatment agent mass = 1:1

[0048] The ratio of sodium silicate mass to concrete interface treatment agent mass is 1:0.75.

[0049] The ratio of sodium silicate mass to concrete interface treatment agent mass is 1:0.5.

[0050] The ratio of sodium silicate mass to concrete interface treatment agent mass is 1:0.3.

[0051] The ratio of sodium silicate mass to concrete interface treatment agent mass is 1:0.1.

[0052] Sodium silicate mass : Concrete interface treatment agent mass = 1 : 0

[0053] Tensile strength of carbon fiber bundles impregnated with adhesives of different proportions and cured was tested using an MTS universal testing machine. The carbon fiber bundles were placed in water for one day, removed, and dried before undergoing tensile testing to assess their tensile properties. Figure 4 The D-type Shore hardness tester shown is used to test the hardness of adhesives with different ratios.

[0054] like Figure 5 As shown: Different formulations had no effect on the tensile strength of the carbon fiber bundles impregnated with the adhesive, but the water resistance of the adhesive improved with increasing concrete interface treatment agent content. The adhesive exhibited good water resistance when the mass of the concrete interface treatment agent was greater than 0.5 times the mass of water glass, and the best water resistance was achieved when the mass of the concrete interface treatment agent was equal to the mass of water glass. Regarding the hardness of the adhesive, sodium silicate is hard and brittle; carbon fiber bundles impregnated with sodium silicate cannot resist impact loads or shear forces. With increasing concrete interface treatment agent content, the colloid softened and its toughness increased. However, the cured concrete interface treatment agent is very soft, and excessive amounts can lead to deformation of the impregnated carbon fiber bundles. When the mass of the concrete interface treatment agent was 0.5 times the mass of water glass, its hardness was moderate, it was not easily deformed, and it possessed a certain degree of toughness. Sodium silicate exhibited good high-temperature resistance, while the concrete interface treatment agent exhibited poor high-temperature resistance. Considering water resistance, hardness, economy, and high temperature resistance, the adhesive with a mass ratio of sodium silicate to concrete interface treatment agent of 1:0.5 to 1 exhibits the best performance.

[0055] Example 4

[0056] A high-performance adhesive impregnating carbon fiber and a method for curing the same, comprising the following steps:

[0057] Step 1: Weigh out 100g of sodium silicate, 100g of concrete interface treatment agent, and 2g of defoamer;

[0058] Step 2: Stir the sodium silicate, concrete interface treatment agent, and defoamer at a speed of 200 r / min for at least 5 minutes to obtain the carbon fiber impregnation adhesive.

[0059] Step 3: Immerse a bundle of radial carbon fibers in carbon fiber impregnation resin for 10 minutes. After removing it, straighten and fix the carbon fiber bundle. It can be used after curing (curing time is not less than 3 days in the range of 5-25℃, and not less than 2 days above 25℃).

[0060] Step 4: Test its tensile strength at 100℃ and 200℃.

[0061] like Figures 6-7 As shown: The tensile strength of the carbon fiber bundle was not affected at 100℃, and the tensile strength of the carbon fiber bundle decreased by only 7% at 200℃.

Claims

1. A curing method for impregnating carbon fibers with a high-performance adhesive, characterized in that, Includes the following steps: Step 1: Weigh 100 parts by weight of water glass, 50-100 parts by weight of concrete interface treatment agent, and 1-2 parts by weight of defoamer; Step 2: Stir the water glass, concrete interface treatment agent, and defoamer at a speed of 200 r / min for at least 5 minutes to obtain the carbon fiber impregnation adhesive. Step 3: Immerse the carbon fiber cloth in the carbon fiber impregnation adhesive for 10 minutes. After removing it, straighten and fix the carbon fiber cloth. The curing time should be no less than 3 days in the range of 5~25°C and no less than 2 days when the temperature is above 25°C. The concrete interface treatment agent is a water-based concrete interface treatment agent. The tensile bond strength of the concrete interface treatment agent after curing for 14 days under standard test conditions is not less than 0.8 MPa. The tensile bond strength of the concrete interface treatment agent after curing for 7 days and immersing in water for 7 days under standard test conditions is not less than 0.7 MPa. The tensile bond strength of the concrete interface treatment agent after curing for 7 days under standard test conditions and placing it in an oven at (70±2°C) for 7 days is not less than 0.7 MPa.

2. The curing method for impregnating carbon fibers with adhesive as described in claim 1, characterized in that, The modulus of the water glass is 2.8 to 3.3.

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