A basalt fiber surface modifier for thermoset resin composites

Abstract

The application discloses a basalt fiber surface modifier for thermosetting resin composite, and relates to the technical field of surface modifiers; the application provides a general structure of the basalt fiber surface modifier, simultaneously provides a preparation method of the basalt fiber surface modifier, and the basalt fiber surface modifier is used for modifying basalt fibers and preparing thermosetting resin / basalt fiber composite materials. The application designs a three-block polymer coupling agent with different functional groups, can effectively enhance the bonding strength of the thermosetting resin and the basalt fibers, simultaneously ensures certain toughness, and is used for preparing high-performance thermosetting resin / basalt fiber composite materials.

Description

Technical Field

[0001] The present invention relates to the technical field of surface modifiers, and in particular to a basalt fiber surface modifier for thermosetting resin composite materials. Background Art

[0002] With the development of science and technology, people have an increasingly higher demand for the mechanical properties, specific strength and specific stiffness of materials, so composite materials have come into being. Materials that are formed by combining two or more materials with different forms and properties by chemical or physical methods to form a comprehensive performance that is better than the performance of each component material are called composite materials. As a new type of material, composite materials have become an important pillar of high-performance structural materials, and together with polymer materials, inorganic non-metallic materials and metal materials, they are collectively known as the "four major materials". Among them, thermosetting resin-based composite materials (Thermoset Polymer Composites, referred to as "TSPC") have the advantages of light weight, high strength, corrosion resistance, fatigue resistance, good molding process, and strong designability. They are widely used in aerospace, sports and leisure, wind turbine blades, transportation, bridge construction and other fields. Thermosetting resins are a type of monomer molecules that undergo a series of addition and condensation reactions under the action of curing agents, heat or radiation to form a three-dimensional cross-linked network. It is a basically irreversible cross-linked structure. The main ones are epoxy resins, unsaturated polyesters, phenolic resins, etc. After curing, thermosetting resins often exhibit brittleness and insufficient toughness due to their high crosslink density, which has become a major obstacle to their application. Thermosetting resin-based composites, prepared by adding reinforcements to the resin matrix, can significantly improve their strength, toughness, and heat resistance. Currently, fiber materials such as carbon fiber, basalt fiber, glass fiber, and aramid fiber are widely used as reinforcements in resin-based composites. Carbon fiber-reinforced composites offer the best mechanical properties, but their high price limits their application in some areas. Glass fiber-reinforced composites are one of the most widely studied materials. Due to their low price and consistent mechanical properties, they can serve as a cost-effective alternative to carbon fiber-reinforced composites in certain applications. Basalt fiber-reinforced composites have mechanical properties similar to those of glass fiber-reinforced composites, are environmentally friendly, and are widely available. Therefore, cost-effective basalt fiber-reinforced thermosetting resin-based composites have broad market prospects.

[0003] Basalt fiber is made primarily from basalt ore, which is melted and drawn through a platinum-plated sieve. However, basalt fiber has a smooth, chemically inert surface, poor bundling and wettability, and poor adsorption capacity for most polymers. The interfacial bonding affects the composite's compressive strength, impact strength, damage initiation threshold, fracture toughness, interlaminar shear, fatigue life, thermal properties, and electrical properties. The significant differences in physical properties between basalt fiber and the resin matrix significantly impact the uniform stress transfer at the composite interface. Therefore, to further improve the overall performance of basalt fiber-reinforced resin-based composites, surface modification of the basalt is essential. By manipulating the thermosetting resin / basalt fiber interface structure, the interfacial bonding strength can be enhanced, the load transfer capacity at the interface can be improved, and the thermosetting resin matrix can be toughened, thereby enhancing the overall performance of thermosetting resin / basalt fiber composites.

[0004] As far as inorganic / organic interface modification is concerned, the use of coupling agents can significantly improve the interface bonding strength. Silane coupling agents, as commonly used modifiers, are compounds consisting of two chemically different groups (organic group Y and hydrolyzed group X (OR)) connected to the same silicon atom. Schematic diagram of the surface mechanism of silane coupling agent modified materials is shown in the figure below. Figure 1 As shown. Silane coupling agents hydrolyze to form silanols, which, through condensation, further form hydrogen bonds or AO-Si (A represents the material matrix) bonds with chemical groups on the material surface, allowing the silane coupling agent to be grafted and adsorbed on the material surface. As an important chemical reagent with a special structure that connects the surfaces of organic and inorganic materials, silane coupling agents can chemically react with organic polymer materials to form carbon functional groups, and can also chemically bond with the surfaces of inorganic polymer materials to form silicon functional groups. Therefore, whether organic or inorganic, different materials can be coupled together through the chemical or physical effects of silane coupling agents, further promoting the research and development of organic polymer composite materials and producing polymer materials with even better performance.

[0005] The use of silane coupling agents in composite materials can significantly improve their mechanical properties, weather resistance, water resistance, flame retardancy, adhesion, dispersibility, formability, and process operability. For the resin matrix, when using silane coupling agents that physically entangle with the resin matrix, due to the short non-polar molecular chains of small molecule coupling agents, this physical bonding force is weak, affecting the overall performance of the composite material. The use of polymer coupling agents can enhance the physical entanglement between the resin matrix and the interaction between the resin matrix and the inorganic filler, thereby optimizing the interface of the composite material. For thermosetting resin matrices, the use of small molecule silane coupling agents that can chemically bond with thermosetting resins can effectively increase the bond strength between the resin and the inorganic filler. However, due to the short molecular chains of small molecules, the bond between the resin and the inorganic filler is too tight, resulting in the stress at the interface not being well released, which is not conducive to improving the toughness of the composite material. In contrast, polymer coupling agents can ensure effective bonding between the resin matrix and the inorganic filler while forming a flexible layer at the interface, alleviating stress concentration and relaxing thermal stress, achieving the purpose of toughening. At the same time, by changing the molecular weight and molecular structure of the polymer coupling agent, the strength and modulus of the coupling agent can also be adjusted, thereby achieving control and optimization of the interface structure between the filler and the matrix.

[0006] Although polymer coupling agents offer numerous advantages over small molecule coupling agents, current research on silane coupling agents is primarily focused on small molecule coupling agents. Research on the synthesis of polymer silane coupling agents and their application in composite material modification is quite lacking. In particular, research on polymer silane coupling agents for use in thermosetting resin / basalt fiber composites is rare. Research on the targeted design and synthesis of silane coupling agents for surface modification of basalt fibers in thermosetting resin composites could help further enhance the overall performance of thermosetting resin / basalt fiber composites and meet the demand for higher-performance composite materials. Summary of the Invention

[0007] In order to solve the above technical problems, the purpose of the present invention is to provide a basalt fiber surface modifier for thermosetting resin composites, and to design a triblock polymer coupling agent with different functional groups, which can effectively enhance the bonding strength between thermosetting resin and basalt fiber while ensuring a certain toughness, and is used to prepare high-performance thermosetting resin / basalt fiber composites.

[0008] The present invention solves the above technical problems by providing a basalt fiber surface modifier for thermosetting resin composite materials, the general structural formula of which is:

[0009] -[Group A] x -[Group B] y -[Group C] z -;

[0010] Wherein, Group A is an olefin containing an epoxy group, an aldehyde group, a carboxyl group or an amine group;

[0011] Group B is olefins without active functional groups;

[0012] Group C is an olefin containing a silane group, a hydroxyl group, a carboxyl group, an isocyanate group, a phosphate group or a sulfonic acid group.

[0013] At the same time, since the surface modifier is a ternary random copolymer, the specific values ​​of x, y, and z cannot be determined.

[0014] Furthermore, x, y, z = 1:1:1.

[0015] Furthermore, Group B is ethylene, propylene or tetrafluoroethylene.

[0016] Furthermore, the basalt fiber surface modifier for thermosetting resin composite materials has the structural formula:

[0017]

[0018] The present invention also provides a method for preparing the above-mentioned basalt fiber surface modifier for thermosetting resin composite materials, comprising the following steps:

[0019] (1) Compound 1, Compound 2, and Compound 3 were dissolved in toluene, and then dibenzoyl peroxide was added. The mixture was reacted at 80°C for 2 h under an argon atmosphere. Dibenzoyl peroxide dissolved in toluene was further added, and the mixture was reacted at 80°C for 3 h. The mixture was cooled to room temperature, and the mixture was added dropwise to methanol for precipitation. The mixture was filtered to obtain a crude product.

[0020] (2) The crude product was dissolved in acetone, added dropwise to methanol for recrystallization, filtered, and vacuum dried to obtain a basalt fiber surface modifier for thermosetting resin composite materials.

[0021] Further, in step (1), the compound has the structural formula

[0022] Further, in step (1), the structural formula of compound II is

[0023] Further, in step (1), the compound three structural formula is

[0024] Furthermore, in step (1), the molar volume ratio of compound 1, compound 2, compound 3 and toluene is 28.14 mmol: 28.14 mmol: 14.07 mmol: 40 mL.

[0025] Furthermore, the concentration of dibenzoyl peroxide was 1 wt %.

[0026] The present invention also provides application of the basalt fiber surface modifier for thermosetting resin composite materials in basalt fiber modification.

[0027] The present invention also provides the use of the basalt fiber surface modifier for thermosetting resin composite materials in the preparation of thermosetting resin / basalt fiber composite materials.

[0028] The present invention has the following beneficial effects:

[0029] 1. To enable the polymer to chemically bond simultaneously with both the thermosetting resin and basalt fiber, the olefin block polymer of this invention requires at least three different olefin monomers, designated Group A, Group B, and Group C. Group A contains functional groups capable of chemically bonding with the thermosetting resin, anchoring the polymer to the resin matrix; Group C contains functional groups capable of chemically bonding with the basalt fiber, anchoring the basalt fiber reinforcement; Group B chemically reacts neither with the thermosetting resin nor with the basalt fiber, primarily serving to adjust the flexibility of the bond between the resin matrix and the basalt fiber. Based on this design, epoxy or imidazole groups are introduced into the Group A units. These groups react chemically with the active methylene hydroxyl groups in thermosetting resins, such as phenolic resins, and the epoxy groups in epoxy resins. The stability of the chemical bond affects the bond strength. The silane groups in the Group C units undergo hydrolysis and polymerization upon heating on the basalt fiber surface, firmly bonding to the basalt fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the surface mechanism of materials modified by silane coupling agents;

[0031] Figure 2 This is an infrared spectrum graph of the product obtained in Example 1;

[0032] Figure 3 This is an infrared spectrum graph of the product obtained in Example 2;

[0033] Figure 4 This is the thermogravimetric curve of the product obtained in Example 1-2. DETAILED DESCRIPTION

[0034] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0035] Example 1

[0036] A basalt fiber surface modifier for thermosetting resin composite materials, having the structural formula:

[0037]

[0038] The preparation method of the basalt fiber surface modifier for thermosetting resin composite materials comprises the following steps:

[0039] (1) Compound 1 (4.00 g, 28.14 mmol), Compound 2 (2.93 g, 28.14 mmol) and Compound 3 (3.49 g, 14.07 mmol) were dissolved in toluene (40 mL), and then dibenzoyl peroxide (0.10 g, 1 wt%) was added. The mixture was reacted at 80°C for 2 h under an argon atmosphere. Dibenzoyl peroxide (0.10 g, 1 wt%) dissolved in toluene was further added, and the mixture was reacted at 80°C for 3 h. The mixture was cooled to room temperature, and the mixture was added dropwise to methanol for precipitation. The mixture was filtered to obtain a crude product.

[0040] (2) The crude product was dissolved in acetone, dropped into methanol for recrystallization, filtered, and vacuum dried to obtain a basalt fiber surface modifier for thermosetting resin composite materials.

[0041] Among them, the structural formula of compound 1 is The structural formula of compound II is The three structural formulas of the compound are

[0042] Example 2

[0043] A basalt fiber surface modifier for thermosetting resin composite materials, having the structural formula:

[0044]

[0045] The preparation method of the basalt fiber surface modifier for thermosetting resin composite materials comprises the following steps:

[0046] (1) Compound 1 (3.20 g, 28.14 mmol), Compound 2 (2.93 g, 28.14 mmol) and Compound 3 (3.49 g, 14.07 mmol) were dissolved in toluene (40 mL), and then dibenzoyl peroxide (0.10 g, 1 wt%) was added. The mixture was reacted at 80°C for 2 h under an argon atmosphere. Dibenzoyl peroxide (0.10 g, 1 wt%) dissolved in toluene was further added, and the mixture was reacted at 80°C for 3 h. The mixture was cooled to room temperature, and the mixture was added dropwise to methanol for precipitation. The mixture was filtered to obtain a crude product.

[0047] (2) The crude product was dissolved in acetone, dropped into methanol for recrystallization, filtered, and vacuum dried to obtain a basalt fiber surface modifier for thermosetting resin composite materials.

[0048] Among them, the structural formula of compound 1 is The structural formula of compound II is The three structural formulas of the compound are Test example

[0049] 1. The molecular structure of the product obtained in Example 1-2 was determined using a Spectrum Two Fourier infrared spectrometer. Potassium bromide was used to prepare the sample. The product to be tested and potassium bromide were dried in a vacuum drying oven before testing. The test results were as follows: Figure 2-3 shown.

[0050] Depend on Figure 2 It can be seen that the product obtained in Example 1 has a -1 is the stretching vibration absorption peak of CH on the benzene ring, 1600 cm -1 、1492cm -1 、1451cm -1 The absorption peak of the C=C chain in-plane stretching vibration on the benzene ring is 1730cm -1 It is the characteristic peak of the C=O double bond in the ester group; 1089cm -1 The characteristic peak of Si-O is at 1764cm -1 and 1850cm -1 The positions are the symmetric and antisymmetric stretching vibration absorption peaks of the CO bond in propylene oxide. It can be seen that the three units of Group A, Group B and Group C exist in the product TPCA-E obtained in Example 1.

[0051] Depend on Figure 3 It can be seen that the product obtained in Example 2 is at 3026cm -1 is the stretching vibration absorption peak of CH on the benzene ring, 1600 cm -1 、1492cm -1 、1451cm -1The peak at 1730 is the characteristic peak of the C=O double bond in the ester group; the peak at 1089 is the characteristic peak of Si-O; at 1602 cm -1 It is the stretching vibration absorption peak of the C=N bond. It can be seen that the three units of Group A, Group B and Group C exist in the product TPCA-N obtained in Example 2.

[0052] 2. The thermal stability of the product obtained in Example 1-2 was analyzed and tested using a NETZSCH TG209F1 thermogravimetric analyzer, using nitrogen as the protective atmosphere and a heating rate of 10°C / min. The results are shown in FIG. Figure 4 shown.

[0053] Depend on Figure 4 The 5% weight loss temperatures for the basalt fiber surface modifiers TPCA-E and TPCA-N for thermosetting resin composites of the present invention are 295°C and 196°C, respectively. At 320°C, the weight loss for both TPCA-E and TPCA-N is less than 10%. These results demonstrate that both TPCA-E and TPCA-N possess excellent thermal stability, meeting the temperature requirements for basalt fiber surface modification.

[0054] 3. Prepare the materials obtained in Example 1-2 as follows:

[0055] The basalt fiber and polymer coupling agent TPCA-E or TPCA-N were dissolved in toluene, refluxed and stirred at 110°C for 5 hours, cooled to room temperature, and the liquid was added dropwise to methanol to precipitate a white solid. The solvent was removed by filtration, and the mixture was dried under reduced pressure at 90°C to obtain a block-like white solid. Epoxy resin (10wt%), polyurethane (10wt%), aluminum hydroxide (10wt%) and sodium stearate (10wt%) were added to a kneader and stirred at room temperature for 30 minutes. The modified chopped basalt fiber (60wt%) was added and stirred at room temperature for 10 minutes. The mixed composite material was taken out.

[0056] The interlaminar shear strength of composite materials was determined using the three-point bending method. The test standard used was JC / T 773-2010. The sample dimensions were: thickness d = 2 ± 0.2 mm, length L = 20 mm, width b = 10 ± 0.5 mm, and span l = 5 d.

[0057] The results are shown in Table 1.

[0058] Table 1 Effect of the amount of basalt fiber surface modifier added on the properties of the composite material

[0059]

[0060] As shown in Table 1, the addition of the basalt fiber surface modifier for thermosetting resin composite materials of the present invention can effectively improve the shear strength of the composite materials. When the addition amount of TPCA-E is 15%, the composite material finally obtained has the optimal interlaminar shear strength performance.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A basalt fiber surface modifier for thermosetting resin composite materials, characterized in that: Its structural formula is: or ; x, y, z = 1:1:

1.

2. The method for preparing the basalt fiber surface modifier for thermosetting resin composite materials according to claim 1, characterized in that: The following steps are involved: (1) Compound 1, Compound 2, and Compound 3 were dissolved in toluene, and then dibenzoyl peroxide was added. The mixture was reacted at 80°C for 2 h under an argon atmosphere. Dibenzoyl peroxide dissolved in toluene was further added, and the mixture was reacted at 80°C for 3 h. The mixture was cooled to room temperature, and the mixture was dropped into methanol for precipitation. The mixture was filtered to obtain a crude product. (2) The crude product was dissolved in acetone, added dropwise to methanol for recrystallization, filtered, and vacuum dried to obtain a basalt fiber surface modifier for thermosetting resin composite materials; Among them, the structural formula of compound 1 is or ; The structural formula of compound II is ; The three structural formulas of the compound are .

3. The method for preparing a basalt fiber surface modifier for thermosetting resin composite materials according to claim 2, wherein: In step (1), the molar volume ratio of compound 1, compound 2, compound 3 and toluene is 28.14 mmol: 28.14 mmol: 14.07 mmol: 40 mL.

4. Use of the basalt fiber surface modifier for thermosetting resin composite materials according to claim 1 in basalt fiber modification.

5. Use of the basalt fiber surface modifier for thermosetting resin composite materials according to claim 1 in the preparation of thermosetting resin / basalt fiber composite materials.

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