Sulfonated polyetheretherketone / amino graphene composite sizing agent of aramid fiber and application of sulfonated polyetheretherketone / amino graphene composite sizing agent

Abstract

The invention relates to the field of fiber sizing agents and polymer-based composite materials thereof, in particular to a sulfonated polyetheretherketone / amino graphene composite sizing agent of aramid fibers and application of the sulfonated polyetheretherketone / amino graphene composite sizing agent. The sizing agent is composed of sulfonated polyetheretherketone, amino graphene, a reinforcing agent and a solvent, sulfonated polyetheretherketone and amino graphene are prepared through a specific process, and the sulfonated polyetheretherketone and the amino graphene are combined with the reinforcing agent to form a stable covalent bond and a cross-linked structure. The surface wettability and mechanical property of the aramid fiber are remarkably improved, the interface bonding force of the aramid fiber and thermoplastic resin is improved, the mechanical strength and toughness of the aramid fiber composite material are improved, and the method is suitable for the field of high-performance composite materials and has important industrial value.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber sizing agents and polymer-based composite materials thereof, and particularly relates to a sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber and application thereof. Background Art

[0002] High-performance fiber materials are increasingly used in aerospace, national defense, automobile manufacturing, and electronic and electrical fields. These fields have extremely stringent requirements on the performance of materials, requiring fiber materials to have not only excellent mechanical properties, but also good thermal stability, chemical corrosion resistance, and electrical conductivity. Aramid fiber has become an important representative of high-performance fiber materials due to its excellent strength, heat resistance, and chemical corrosion resistance. However, aramid fiber still faces some technical difficulties in practical applications, especially its low surface activity and poor interfacial bonding performance with thermoplastic resin matrix, which greatly limits its further application in high-performance composite materials. Traditional fiber sizing agents have certain limitations in mechanical strength, chemical stability, and surface wetting properties, and it is difficult to meet the stringent requirements of modern industry for high-performance materials. Therefore, the development of a multifunctional fiber sizing agent has become a research hotspot in this field.

[0003] Sulfonated polyetheretherketone (SPEEK) is a high-performance engineering plastic widely used in fuel cells, ultrafiltration membranes, and other electrochemical devices due to its excellent thermal stability, mechanical strength, and proton conductivity. The sulfonic acid groups in SPEEK not only impart excellent hydrophilicity and electrical conductivity but also enhance its compatibility with other materials. However, the performance of a single material often fails to meet the complex demands of practical applications. Graphene oxide (GO), a two-dimensional material with excellent mechanical, electrical, and chemical stability, has attracted considerable attention in composite material research in recent years. Chemical modifications, such as the introduction of amino groups, further enhance the functionality of GO, particularly its bonding with polymer matrices. Aminographene (EGO) not only retains the inherent properties of graphene but also strengthens its interfacial bonding with other materials, thereby improving the overall performance of the composite. Combining sulfonated polyetheretherketone with aminographene creates a synergistic composite material that can significantly improve the overall performance of the material.

[0004] Currently, key challenges in aramid fiber surface treatment technology include improving the fiber's surface wettability, enhancing its interfacial bonding with the resin matrix, and improving the overall mechanical properties of the composite. Existing technologies suffer from insufficient surface activity, resulting in poor interfacial properties between aramid fibers and the resin matrix, which in turn affects the mechanical strength and toughness of the composite. Furthermore, conventional sizing agents also lack chemical stability and functionality in complex environments.

[0005] To address these issues, the present invention proposes a composite sizing agent based on sulfonated polyetheretherketone (SPEEK) and aminographene, and introduces a reinforcing agent containing isocyanate groups to achieve a comprehensive improvement in material performance. The isocyanate groups react with the amino groups of aminographene and the hydroxyl groups of SPEEK to form stable covalent bonds and cross-linked structures, thereby significantly enhancing the mechanical properties and chemical stability of the material. This new sizing agent not only effectively improves the mechanical properties and surface wettability of aramid fibers, but also provides reliable protection for their use in harsh environments. It has important industrial value and broad application prospects. Summary of the Invention

[0006] This invention addresses the technical issues of existing aramid fibers, which suffer from low surface activity, insufficient interfacial bonding strength with thermoplastic resin matrices, and mechanical properties that fail to meet the requirements of high-performance composite materials. By providing a sulfonated polyetheretherketone / aminographene composite sizing agent for aramid fibers and its application, the invention utilizes specific components and a preparation process to modify the surface of aramid fibers, significantly improving their surface wettability, mechanical properties, and interfacial bonding strength with thermoplastic resin matrices.

[0007] The technical solution of the present invention is: The present invention provides a sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber, comprising sulfonated polyetheretherketone (SPEEK), amino graphene (EGO), a reinforcing agent, and a solvent. The weight percentage of the sulfonated polyetheretherketone is 0.1%, the weight percentage of the amino graphene is 0.1%, the weight percentage of the reinforcing agent is 0.3% to 0.5%, and the weight percentage of the solvent is 99.4% to 99.6%.

[0008] Furthermore, in the above-mentioned sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber, the solvent includes one or more of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc) or N,N-dimethylformamide (DMF).

[0009] Furthermore, in the above-mentioned sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber, the reinforcing agent includes one or more of 3-isocyanatepropyltriethoxysilane (ICPTES), 2,4-toluene diisocyanate (TDI) or 1,6-hexamethylene diisocyanate (HDI).

[0010] Furthermore, the aforementioned sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber is prepared by the following steps: adding 1.8% by weight of polyetheretherketone particles to 98.2% by weight of concentrated sulfuric acid and stirring at 80°C for 6 hours to introduce polar functional groups (-SO3H) into the polyetheretherketone molecular chains. After the reaction is complete, the mixture is slowly poured into an excess of ice-water with continuous stirring. After standing for 24 hours, the insoluble matter is separated using a centrifuge and the solution is washed multiple times with deionized water until the pH of the solution is neutral. Finally, the solution is vacuum dried at 80°C for 18 hours to obtain the sulfonated polyetheretherketone (SPEEK). The concentration of the concentrated sulfuric acid is greater than 98%.

[0011] Furthermore, the amino graphene (EGO) in the aforementioned sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber is prepared by the following steps: 0.073% by weight of single-layer or multi-layer graphene oxide powder is added to 34.4% by weight of N,N-dimethylformamide (DMF) and uniformly dispersed at room temperature using an ultrasonic device. Subsequently, 65.6% by weight of anhydrous ethylenediamine (EDA) is added, the temperature is raised to 80°C, and the mixture is stirred under nitrogen for 24 hours. After the reaction is completed, the product is washed multiple times with anhydrous ethanol until the pH of the solution is neutral, and then vacuum-dried at 60°C for 18 hours to obtain amino graphene (EGO).

[0012] Furthermore, the above-mentioned sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber is prepared as follows: 0.1% by weight of sulfonated polyetheretherketone is added to 49.7% to 49.8% by weight of solvent and stirred vigorously until completely dissolved; 0.1% by weight of amino graphene powder is added to 49.7% to 49.8% by weight of solvent and ultrasonically treated for 20 minutes to ensure uniform dispersion. Subsequently, the two parts are mixed evenly, and 0.3% to 0.5% by weight of reinforcing agent is added, and ultrasonic treatment is continued for 40 minutes to ensure uniform dispersion.

[0013] Furthermore, the sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber described above includes the following steps: adding the aramid fiber washed with acetone or ethanol to the sizing agent solution prepared above, continuing ultrasonic treatment for 20 minutes to ensure that the sizing agent is evenly coated on the fiber surface; and then drying in an oven at 60°C for 3 hours to obtain the aramid fiber evenly coated with the sizing agent.

[0014] The design idea of the present invention is: By leveraging the synergistic effect between sulfonated polyetheretherketone (SPEEK) and aminographene (EGO), the isocyanate groups (-NCO) in the reinforcing agent undergo cross-linking reactions with the hydroxyl groups (-OH) in SPEEK and the amino groups (-NH2) in EGO, forming a stable covalent bond and network structure. This network structure not only enhances the adhesion of the sizing agent to the fiber surface, but also significantly improves the surface wettability and mechanical properties of the fiber.

[0015] Furthermore, the sulfonated polyetheretherketone (SPEEK) retains the excellent mechanical properties, chemical stability, and thermal stability of polyetheretherketone by introducing sulfonic acid groups (-SO3H), while also exhibiting superior solubility, ion permeability, and hydrophilicity. The aminographene (EGO) is modified with ethylenediamine to form an imine structure (amide bond, imine) and a ring-opening product (new hydroxyl group), enhancing its chemical activity and functionalization. The reinforcing agent's isocyanate group (-NCO) cross-links with the hydroxyl groups (-OH) in SPEEK and the amino groups (-NH2) in EGO, forming a stable network structure and further improving the overall performance of the material.

[0016] Advantages and beneficial effects of the present invention: The aramid fibers and their composites before and after modification were characterized and analyzed using a scanning electron microscope (SEM), a contact angle meter, and a universal material testing machine. The results showed that the surface coating of the modified aramid fibers was uniform without obvious agglomeration or peeling. The contact angle of the modified aramid fibers with water was significantly reduced from 90.6° to 43.2°-51.2°, indicating that the surface hydrophilicity of the modified aramid fibers was significantly improved. The tensile strength of the modified aramid fibers was increased from 2.4 GPa to 2.48 GPa-2.61 GPa. The impact strength of the modified aramid fiber-reinforced PEEK-based composites was increased from 175.3 MPa to 199.8 MPa-203.6 MPa, the tensile strength was increased from 83.9 MPa to 89.2 MPa-95.3 MPa, and the elongation was increased from 1.90% to 2.04%-2.22%.

[0017] In summary, a stable network structure is formed through the cross-linking reaction of the reinforcing agent with the sulfonate and amino groups, thereby improving the uniformity of the sizing agent coating on the fiber surface. The sulfonated polyetheretherketone / amino graphene composite sizing agent provided by the present invention can significantly improve the surface wettability and mechanical properties of aramid fibers, thereby improving their overall performance after being composited with a thermoplastic resin matrix, thereby significantly broadening their application scope in high-demand industrial fields, such as aerospace, national defense and military industry, and high-performance composite materials. The sizing agent provides a new solution for the development of high-performance aramid fiber materials, and has broad application prospects and important industrial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Macroscopic morphology of aramid fiber after coating with ICPTES reinforcement sizing agent; Figure 2 The macromorphology of aramid fiber after coating with HDI reinforcement sizing agent; Figure 3 The macromorphology of aramid fiber after coating with TDI reinforcement sizing agent; Figure 4 The change of surface contact angle before and after modification of aramid fiber; Figure 5 The impact properties of the composite material composed of aramid fiber and PEEK before and after modification are changed. DETAILED DESCRIPTION

[0019] The present invention provides a sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber and its application. The core of the sizing agent is to modify the surface of the aramid fiber through specific components and preparation process, thereby significantly improving its surface wettability, mechanical properties and interfacial bonding strength with the thermoplastic resin matrix.

[0020] The specific implementation of the present invention will be described in detail below with reference to the specific drawings and embodiments in the accompanying drawings.

[0021] S1. Preparation of sulfonated polyetheretherketone (SPEEK) 1.8% by weight of polyetheretherketone (PEEK) particles were added to 98.2% by weight of concentrated sulfuric acid (concentrated sulfuric acid concentration greater than 98%). The mixture was stirred at 80°C for 6 hours to introduce polar functional groups (-SO3H) into the PEEK molecular chains. After the reaction was complete, the mixture was slowly poured into an excess of ice-water with continuous stirring. After standing for 24 hours, insoluble matter was separated using a centrifuge and washed multiple times with deionized water until the solution reached a neutral pH. Finally, the mixture was vacuum-dried at 80°C for 18 hours to obtain sulfonated PEEK (SPEEK). This step ensured the successful introduction of sulfonic acid groups into the PEEK molecular chains, imparting the material with excellent solubility, ion permeability, and hydrophilicity.

[0022] S2. Preparation of amino graphene (EGO) 0.073% by weight of graphene oxide powder was added to 34.4% by weight of N,N-dimethylformamide (DMF) and uniformly dispersed at room temperature using an ultrasonic device. Subsequently, 65.6% by weight of anhydrous ethylenediamine (EDA) was added, the temperature was raised to 80°C, and the mixture was stirred under nitrogen for 24 hours. After the reaction, the product was washed multiple times with anhydrous ethanol until the pH of the solution was neutral, and then vacuum-dried at 60°C for 18 hours to obtain amino graphene (EGO). EDA modification formed an imine structure and a ring-opening product, enhancing its chemical activity and functionalization.

[0023] S3. Prepare sizing agent 0.1% by weight of sulfonated polyetheretherketone (SPEK) was added to 49.7% to 49.8% by weight of solvent and stirred vigorously until completely dissolved. The solvent consisted of one or more of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), or N,N-dimethylformamide (DMF). 0.1% by weight of aminographene powder was added to 49.7% to 49.8% by weight of solvent and sonicated for 20 minutes to ensure uniform dispersion. The two components were then mixed thoroughly, and 0.3% to 0.5% by weight of a reinforcing agent was added. Sonication was continued for another 40 minutes to ensure uniform dispersion. The reinforcing agent consisted of one or more of 3-isocyanatopropyltriethoxysilane (ICPTES), 2,4-toluene diisocyanate (TDI), or 1,6-hexamethylene diisocyanate (HDI). This step achieves a synergistic effect between sulfonated polyetheretherketone and aminographene, and the isocyanate groups in the reinforcing agent undergo cross-linking reactions with the hydroxyl groups in sulfonated polyetheretherketone and the amino groups in aminographene to form stable covalent bonds and network structures.

[0024] S4. Sizing process of aramid fiber After washing with acetone or ethanol, the aramid fibers were added to the sizing solution prepared above and ultrasonically treated for 20 minutes to ensure uniform coating of the sizing agent on the fiber surface. The fibers were then dried in an oven at 60°C for 3 hours to obtain uniformly coated aramid fibers. This step ensured uniform distribution of the sizing agent on the fiber surface, without significant agglomeration or flaking.

[0025] S5. Performance test of modified aramid fiber Scanning electron microscopy (SEM) was used to observe the surface morphology of aramid fibers before and after modification. Figures 1 to 3 Figure 2 shows the macromorphology of aramid fibers coated with ICPTES, HDI, and TDI-enhanced sizing agents, respectively. As can be seen from the figure, the surface coating of the modified aramid fibers is uniform, indicating that the sizing agents have successfully adhered to the fiber surface.

[0026] The surface wettability of aramid fibers before and after modification was tested using a contact angle meter. Figure 4 As shown in the figure, the contact angle of the modified aramid fiber with water decreased significantly from 90.6° to 43.2°~51.2°, indicating that its surface hydrophilicity was significantly improved. The mechanical properties of the modified aramid fiber were tested using a universal material testing machine. The results showed that the tensile strength of the modified aramid fiber increased from 2.4 GPa to 2.48 GPa~2.61 GPa.

[0027] S6. Performance test of modified aramid fiber reinforced composite materials.

[0028] 5% by weight of modified aramid fiber and 95% by weight of polyetheretherketone (PEEK) pellets were mixed and fed into an injection molding machine set at 340°C. The speed of the injection molding machine was adjusted to 90 rpm, and mixing was performed for 3 minutes to ensure that the aramid fiber and PEEK pellets were fully and evenly dispersed. After mixing, extrusion molding was performed.

[0029] The mechanical properties of modified aramid fiber reinforced PEEK-based composites were tested using a universal material testing machine. Figure 5 As shown in the figure, the impact strength of the modified aramid fiber reinforced PEEK-based composites increased from 175.3 MPa to 199.8 MPa~203.6 MPa, the tensile strength increased from 83.9 MPa to 89.2 MPa~95.3 MPa, and the elongation increased from 1.90% to 2.04%~2.22%.

[0030] These data indicate that the modified aramid fibers significantly improve the overall performance of the composites.

[0031] S7. Analysis of actual application scenarios The sulfonated polyetheretherketone / amino graphene composite sizing agent provided by the present invention is suitable for the field of surface modification technology of high-performance aramid fibers, especially for applications in harsh environments such as aerospace, national defense and military industry, and high-performance composite materials. For example, in the field of aerospace, modified aramid fibers can be used to manufacture lightweight, high-strength composite materials components to meet the high requirements of aircraft for material properties. In the field of national defense and military industry, modified aramid fibers can be used to manufacture protective equipment such as bulletproof vests and armored vehicles to improve their impact resistance. In the field of high-performance composite materials, modified aramid fibers can be used to manufacture automotive parts, electronic and electrical equipment housings, etc., significantly broadening its scope of application.

[0032] Through the above-mentioned specific embodiments, the present invention provides a detailed technical solution for surface modification of aramid fibers. This sizing agent can significantly improve the surface wettability and mechanical properties of aramid fibers, thereby enhancing their overall performance after composite with a thermoplastic resin matrix, demonstrating broad application prospects and significant industrial value. Example

[0033] The preparation method of a sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber in this embodiment includes the following steps: 0.1% by weight of sulfonated polyetheretherketone was added to 49.8% by weight of N-methylpyrrolidone (NMP) solution and stirred vigorously until completely dissolved to obtain SPEEK / NMP solution.

[0034] (2) 0.1% by weight of amino graphene powder was added to 49.8% by weight of N-methylpyrrolidone (NMP) solution and ultrasonically treated for 20 minutes to obtain EGO / NMP dispersion.

[0035] (3) The SPEEK / NMP solution was added to the EGO / NMP solution, and after stirring and ultrasonic treatment for 20 minutes, 0.2% by weight of 3-isocyanatepropyltriethoxysilane (ICPTES) was added and the treatment was continued for 40 minutes to ensure uniform dispersion.

[0036] (4) The aramid fibers washed with acetone were added to the sizing agent solution and ultrasonic treatment was continued for 20 minutes to obtain aramid fibers uniformly coated with the sizing agent.

[0037] (5) 5% by weight of modified aramid fiber and 95% by weight of PEEK particles were mixed and placed in an injection molding machine set at 340°C. The speed of the injection molding machine was adjusted to 90 r / min and mixing was performed for 3 minutes to ensure that the aramid fiber and PEEK particles were fully and evenly dispersed. After mixing, extrusion molding was performed.

[0038] The tensile strength of the fiber is 2.53 GPa (unmodified AF is 2.4 GPa), and the contact angle with water is 47.2° (unmodified AF is 90.6°). The impact performance of fiber-reinforced PEEK-based composites is enhanced to 199.8 MPa (pure PEEK is 175.3 MPa), the tensile strength is enhanced to 91.2 MPa (pure PEEK is 83.9 MPa), and the elongation is 2.04% (pure PEEK is 1.90%). Example

[0039] This embodiment differs from Embodiment 1 in that 0.2% by mass of 3-isocyanatopropyltriethoxysilane (ICPTES) is replaced with 0.2% by mass of 1,6-hexamethylene diisocyanate (HDI).

[0040] The tensile strength of the fiber is 2.48 GPa (unmodified AF is 2.4 GPa), and the contact angle with water is 51.2° (unmodified AF is 90.6°). The impact performance of fiber-reinforced PEEK-based composites is enhanced to 203.6 MPa (pure PEEK is 175.3 MPa), the tensile strength is enhanced to 89.2 MPa (pure PEEK is 83.9 MPa), and the elongation is 2.10% (pure PEEK is 1.90%). Example

[0041] This embodiment differs from Embodiment 1 in that 0.2% by mass of 3-isocyanatopropyltriethoxysilane (ICPTES) is replaced with 0.2% by mass of 2,4-toluene diisocyanate (TDI).

[0042] The tensile strength of the fiber is 2.61 GPa (unmodified AF is 2.4 GPa), and the contact angle with water is 43.2° (unmodified AF is 90.6°). The impact performance of fiber-reinforced PEEK-based composites is enhanced to 200.1 MPa (pure PEEK is 175.3 MPa), the tensile strength is enhanced to 95.3 MPa (pure PEEK is 83.9 MPa), and the elongation is 2.22% (pure PEEK is 1.90%).

Claims

1. A sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber, characterized in that: It is composed of sulfonated polyetheretherketone, amino graphene, a reinforcing agent and a solvent, wherein the mass proportion of sulfonated polyetheretherketone is 0.1%, the mass proportion of amino graphene is 0.1%, the mass proportion of the reinforcing agent is 0.3%~0.5%, and the mass proportion of the solvent is 99.4%~99.6%.

2. The sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber according to claim 1, characterized in that: The solvent includes one or more of N-methylpyrrolidone, N,N-dimethylacetamide or N,N-dimethylformamide.

3. The sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber according to claim 1, characterized in that: The reinforcing agent includes one or more of 3-isocyanatepropyltriethoxysilane, 2,4-toluene diisocyanate or 1,6-hexamethylene diisocyanate.

4. The sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber according to claim 1, characterized in that: The sulfonated polyetheretherketone is prepared by the following steps: adding 1.8% by weight of polyetheretherketone particles to 98.2% by weight of concentrated sulfuric acid, stirring at 80°C for 6 hours, then pouring the mixture into an ice-water mixture and continuously stirring, allowing the suspension to stand for 24 hours, separating insoluble substances using a centrifuge, washing with deionized water until neutral, and then vacuum drying at 80°C for 18 hours to obtain the sulfonated polyetheretherketone.

5. The sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber according to claim 1, characterized in that: The amino graphene is prepared by the following steps: adding 0.073% by weight of single-layer or multi-layer graphene oxide powder to 34.4% by weight of N,N-dimethylformamide and dispersing the powder evenly, then adding 65.6% by weight of anhydrous ethylenediamine, stirring for 24 hours at a temperature of 80° C. under nitrogen protection, washing the mixture with anhydrous ethanol several times until neutral, and vacuum drying the mixture at 60° C. for 18 hours to obtain the amino graphene.

6. The sulfonated polyetheretherketone / amino graphene composite sizing agent for aramid fiber according to claim 1, characterized in that: The sizing agent preparation process includes adding 0.1% by weight of sulfonated polyetheretherketone to 49.7-49.8% by weight of a solvent and vigorously stirring until completely dissolved; adding 0.1% by weight of amino graphene powder to 49.7-49.8% by weight of a solvent and ultrasonically treating for 20 minutes; then mixing the two together, adding 0.3-0.5% by weight of a reinforcing agent, and then continuing ultrasonic treatment for 40 minutes to ensure uniform dispersion.

7. The use of the composite sizing agent according to any one of claims 1 to 6, characterized in that: The cleaned aramid fiber was added to the composite sizing agent and ultrasonically treated for 20 minutes, and then dried at a temperature of 60° C. for 3 hours to obtain aramid fiber uniformly coated with the sizing agent.

8. The use of the composite sizing agent according to claim 7, characterized in that: The cleaning adopts acetone or ethanol as a cleaning agent.

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