High-temperature-resistant polysulfone composite material and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant polysulfone composite material and a preparation method thereof. The material is composed of polysulfone (polysulfone), modified multi-walled carbon nanotubes and modified carbon nanofibers. A dopamine self-polymerization reaction is carried out in a Tris-HCl buffer solution (pH = 8.5), so that functional modification of the surface of the carbon nanomaterial is realized, an active layer containing hydroxyl and amino is formed on the surface of the carbon nanomaterial, and the dispersity and interface bonding performance of the carbon nanomaterial in polysulfone are remarkably improved. The composite material prepared through air oxidation, solution mixing, ultrasonic dispersion and segmented heating forms a compact multi-scale heat conduction network. Test results show that when the weight of each of the two fillers is 1.5 wt.%, the tensile strength reaches 82 MPa, the initial degradation temperature is increased to 546 DEG C, and excellent mechanical properties and high temperature resistance are shown. The method is simple, convenient and environment-friendly, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a high-temperature resistant polysulfone composite material and its preparation method. Background Technology

[0002] Polysulfone (PSB) is a class of high-molecular-weight engineering plastics with a main chain structure of –SO2–, –O–, and aromatic rings. It possesses excellent mechanical properties, radiation resistance, and chemical stability, and is widely used in electronic and electrical components, medical devices, and high-temperature filtration membranes. However, although PSB has a glass transition temperature of up to 185°C, it still exhibits significant drawbacks at higher temperatures. The ether bonds and sulfone groups in the PSB main chain are easily oxidized and degraded in high-temperature air, leading to molecular chain breakage and a sharp decline in the material's mechanical properties. Its thermal decomposition temperature is typically only around 530°C. Under prolonged high-temperature loads, its structure is prone to embrittlement, deformation, and even carbonization. It also exhibits low thermal conductivity and a significant thermal accumulation effect. PSB is a non-thermal conductive polymer with a thermal conductivity of only about 0.25 W·m. -1 ·K -1 When used in electronic or aerospace components, heat is difficult to conduct in a timely manner, easily causing localized overheating and accelerating aging and failure. Interfacial stress concentration occurs at high temperatures. Polysulfone has a large coefficient of thermal expansion at high temperatures; if internal micro-defects exist or filler is unevenly dispersed, thermal stress concentration will further weaken its dimensional stability and strength retention.

[0003] To overcome these problems, researchers have attempted to improve the heat resistance of polysulfone by introducing carbon nanomaterials. Multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs) possess excellent thermal conductivity and mechanical modulus, and are considered ideal reinforcing materials for improving the thermal conductivity and thermal stability of polysulfone. However, carbon nanomaterials have strong surface inertness and are prone to aggregation, resulting in poor dispersibility and weak interfacial bonding in non-polar polymers such as polysulfone. This often leads to limited reinforcing effects and even filler detachment and performance degradation at high temperatures.

[0004] To address this, polydopamine (PDA) surface modification technology has been proposed in recent years. This method utilizes dopamine self-polymerization under mild alkaline conditions to form a functional layer containing hydroxyl and amino groups. This not only improves the dispersion stability of carbon nanomaterials but also enhances their interfacial compatibility with polysulfone molecules through hydrogen bonding and dipole interactions. Studies have shown that PDA-modified carbon nanomaterials can effectively suppress thermal decomposition and interfacial debonding in high-temperature composite systems.

[0005] While existing studies have confirmed that MWCNT or CNF single modification systems can improve the thermal stability of polysulfone, synergistic enhancement between the two has not yet been achieved, and there is a lack of systematic research on the interfacial structural stability of "dual carbon" nanofillers under high-temperature conditions.

[0006] Therefore, developing a novel high-temperature resistant polysulfone composite material that combines PDA surface modification with the synergistic reinforcement mechanism of MWCNT / CNF has become a key direction for solving the problems of thermo-oxidative degradation, insufficient thermal conductivity, and interfacial failure of polysulfone under high-temperature conditions. This invention is based on this principle and aims to achieve long-term stability and high strength and toughness of polysulfone materials under high-temperature environments. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a high-temperature resistant polysulfone composite material and its preparation method.

[0008] This invention is achieved through the following technical solution: A high-temperature resistant polysulfone composite material, comprising, by mass percentage: 1%–3% modified multi-walled carbon nanotubes; 1%–3% modified carbon nanofibers; and the balance being polysulfone.

[0009] Furthermore, the mass ratio of the modified multi-walled carbon nanotubes to the modified carbon nanofibers is 1-3:1-3.

[0010] Furthermore, the mass ratio of the polydopamine-modified multi-walled carbon nanotubes to the polydopamine-modified carbon nanofibers is 1.5:1.5.

[0011] Further, the preparation method of the polydopamine-modified multi-walled carbon nanotubes is as follows: a certain amount of Tris is accurately weighed, dissolved in purified water, and the pH is adjusted to 8.5 with HCl to prepare a Tris-HCl buffer solution; then, 1.80 g of MWCNTs are weighed and dispersed in 600 mL of Tris-HCl buffer solution. After being fully dispersed at room temperature, the solution is immediately transferred to an ultrasonic instrument and ultrasonically dispersed at 40 kHz for 30 min; then, dopamine hydrochloride is added to the dispersion at a mass ratio of 1:1 (dopamine hydrochloride:MWCNTs) and stirred continuously at room temperature for 24 h; then, the solution is filtered and washed until the filtrate is colorless and neutral, and the resulting filter cake is vacuum dried at 40°C for 24 h.

[0012] Furthermore, the MWCNTs have an outer diameter of 8–15 nm, a length of 50 μm, and a specific surface area >140 m². 2 / g.

[0013] Further, the preparation method of the polydopamine-modified carbon nanofibers is as follows: 0.1 g Tris-HCl and 200 mL deionized water are added to a container, and the pH is adjusted to 8.5 with 0.05 mol / L HCl; then 0.2 g dopamine hydrochloride and 0.7 g CNFs are added, and the mixture is stirred at 25°C for 24 h. The product is washed several times with deionized water until neutral, then filtered and dried at 60°C for 24 h.

[0014] Furthermore, the CNFs have a diameter of 50~200nm and a length of 1~15µm.

[0015] This invention also provides a method for preparing a polysulfone composite material, comprising the following steps: Step S1: Place the modified MWCNT and modified CNF in a quartz tube, then place it in a tube furnace and incubate at 450°C for 40 ml / min. -1 Oxidation was carried out at an air flow rate of 2 hours, with the quartz tube rotated every 30 minutes to improve the interfacial adhesion and dispersibility of modified MWCNT and modified CNF in polysulfone aggregates. Step S2: Disperse modified MWCNT and modified CNF in tetrahydrofuran, sonicate for 1 hour at a frequency of 22.5 kHz and a power of 100 W to obtain mixed solution A; then add polysulfone to mixed solution A; then add the required amount of polysulfone to solution A; wherein the mass of tetrahydrofuran is 10 times the sum of the masses of modified MWCNT, modified CNF and polysulfone; then stir for 30 minutes, then sonicate for 10 minutes, stir for another 10 minutes, and sonicate for another 10 minutes. Step S3: Evaporate the mixed solution obtained in step S2 overnight at room temperature; finally, perform segmented heating to completely remove the solvent and obtain a high-temperature resistant polysulfone composite material.

[0016] Furthermore, the segmented heating process in step S3 is 2 hours at 60°C, 1 hour at 120°C, and 1 hour at 150°C.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention constructs a stable multi-scale thermally conductive and reinforcing network by synergistically introducing polydopamine-modified multi-walled carbon nanotubes and carbon nanofibers into a polysulfone matrix. This structure significantly improves the dispersibility and interfacial bonding of carbon nanomaterials in polysulfone, effectively suppressing thermo-oxidative degradation and stress concentration at high temperatures. The modified filler surface contains hydroxyl and amino groups, which can form hydrogen bonds with polysulfone molecules, improving stress transfer efficiency and interfacial thermal stability. Experimental results show that the tensile strength and modulus of the material of this invention are increased by approximately 30% and 50%, respectively, and the initial thermal decomposition temperature is increased to 546°C. The overall performance is significantly better than that of existing single-filler systems, demonstrating excellent high-temperature resistance and promising industrial application prospects. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0019] The preparation method of the modified MWCNT in this invention is as follows: A precise amount of Tris was weighed, dissolved in purified water, and the pH was adjusted to 8.5 with HCl to prepare a Tris-HCl buffer solution. Then, 1.80 g of multi-walled carbon nanotubes (MWCNTs) were weighed and dispersed in 600 mL of the Tris-HCl buffer solution. After thorough dispersion at room temperature, the solution was immediately transferred to an ultrasonicator and ultrasonically dispersed at 40 kHz for 30 min. Dopamine hydrochloride was then added to the dispersion at a mass ratio of 1:1 (dopamine hydrochloride:MWCNTs), and the mixture was stirred continuously at room temperature for 24 h. The mixture was then filtered and washed until the filtrate was colorless and neutral. The resulting filter cake was vacuum dried at 40 °C for 24 h. The MWCNTs had a purity >95%, an outer diameter of 8–15 nm, a length of 50 μm, and a specific surface area >140 m². 2 (g) was purchased from Aladdin Reagents (Shanghai) Co., Ltd.

[0020] The preparation method of the modified CNF in this invention is as follows: 0.1 g Tris-HCl and 200 mL deionized water were added to a container, and the pH was adjusted to 8.5 with 0.05 mol / L HCl. Then, 0.2 g dopamine hydrochloride and 0.7 g CNFs were added, and the reaction was stirred at 25°C for 24 h. The product was washed several times with deionized water until neutral, then filtered and dried at 60°C for 24 h. The CNF carbon nanofibers had a purity ≥97%, a diameter of 50–200 nm, and a length of 1–15 µm.

[0021] Example 1 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 1% modified MWCNT, 1% modified CNF, and the balance being polysulfone.

[0022] Its preparation method is as follows: Step S1: Place the modified MWCNT and modified CNF in a quartz tube, then place it in a tube furnace and incubate at 450°C for 40 ml / min. -1 Oxidation was carried out at an air flow rate of 2 h, with the quartz tube rotated every 30 min to improve the interfacial adhesion and dispersibility of modified MWCNT and modified CNF in polysulfone aggregates. Step S2: Disperse modified MWCNT and modified CNF in tetrahydrofuran, sonicate for 1 hour at a frequency of 22.5 kHz and a power of 100 W to obtain mixed solution A; then add polysulfone to mixed solution A; then add the required amount of polysulfone to solution A; wherein the mass of tetrahydrofuran is 10 times the sum of the masses of modified MWCNT, modified CNF and polysulfone; then stir for 30 minutes, then sonicate for 10 minutes, stir for another 10 minutes, and sonicate for another 10 minutes. Step S3: Evaporate the mixed solution obtained in step S2 at room temperature overnight; finally, perform segmented heating at 60°C for 2 h, 120°C for 1 h, and 150°C for 1 h to completely remove the solvent and obtain a high-temperature resistant polysulfone composite material.

[0023] Example 2 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 2% modified MWCNT, 2% modified CNF, and the balance being polysulfone.

[0024] The preparation method is the same as in Example 1.

[0025] Example 3 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 3% modified MWCNT, 3% modified CNF, and the balance being polysulfone.

[0026] The preparation method is the same as in Example 1.

[0027] Example 4 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 1.5% modified MWCNT, 1.5% modified CNF, and the balance being polysulfone.

[0028] The preparation method is the same as in Example 1.

[0029] Example 5 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 1% modified MWCNT, 2% modified CNF, and the balance being polysulfone.

[0030] The preparation method is the same as in Example 1.

[0031] Example 6 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 2% modified MWCNT, 1% modified CNF, and the balance being polysulfone.

[0032] The preparation method is the same as in Example 1.

[0033] Comparative Example 1 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 0.5% modified MWCNT, with the balance being polysulfone.

[0034] Its preparation method is as follows: Step S1: Place the modified MWCNT in a quartz tube, then place it in a tube furnace and incubate at 450°C for 40 ml / min. -1 Oxidation was carried out at an air flow rate of 2 h, with the quartz tube rotated every 30 min to improve the interfacial adhesion and dispersibility of the modified MWCNT in the polysulfone aggregate. Step S2: Disperse the modified MWCNT in tetrahydrofuran and sonicate for 1 hour at a frequency of 22.5 kHz and a power of 100 W to obtain a mixed solution A; then add polysulfone to mixed solution A; then add the required amount of polysulfone to solution A; wherein the mass of tetrahydrofuran is 10 times the sum of the masses of the modified MWCNT and polysulfone; then stir for 30 minutes, then sonicate for 10 minutes, stir for another 10 minutes, and then sonicate for another 10 minutes. Step S3: Evaporate the mixed solution obtained in step S2 at room temperature overnight; finally, perform segmented heating at 60°C for 2 h, 120°C for 1 h, and 150°C for 1 h to completely remove the solvent and obtain a high-temperature resistant polysulfone composite material.

[0035] Comparative Example 2 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 1% modified MWCNT, with the balance being polysulfone.

[0036] Its preparation method is the same as that of Comparative Example 1.

[0037] Comparative Example 3 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 3% modified MWCNT, with the balance being polysulfone.

[0038] Its preparation method is the same as that of Comparative Example 1.

[0039] Comparative Example 4 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 5% modified MWCNT, with the balance being polysulfone.

[0040] Its preparation method is the same as that of Comparative Example 1.

[0041] Comparative Example 5 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 0.5% modified CNF, with the balance being polysulfone.

[0042] Its preparation method is as follows: Step S1: Place the modified CNF in a quartz tube, then place it in a tube furnace and incubate at 450°C for 40 ml / min. -1 Oxidation was carried out at an air flow rate of 2 h, with the quartz tube rotated every 30 min to improve the interfacial adhesion and dispersibility of the modified MWCNT in the polysulfone aggregate. Step S2: Disperse the modified CNF in tetrahydrofuran and sonicate for 1 hour at a frequency of 22.5 kHz and a power of 100 W to obtain a mixed solution A; then add polysulfone to mixed solution A; then add the required amount of polysulfone to solution A; wherein the mass of tetrahydrofuran is 10 times the sum of the masses of the modified CNF and polysulfone; then stir for 30 minutes, then sonicate for 10 minutes, stir for another 10 minutes, and then sonicate for another 10 minutes. Step S3: Evaporate the mixed solution obtained in step S2 at room temperature overnight; finally, perform segmented heating at 60°C for 2 h, 120°C for 1 h, and 150°C for 1 h to completely remove the solvent and obtain a high-temperature resistant polysulfone composite material.

[0043] Comparative Example 6 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 1% modified CNF, with the balance being polysulfone.

[0044] The preparation method is the same as that of Comparative Example 5.

[0045] Comparative Example 7 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 3% modified CNF, with the balance being polysulfone.

[0046] The preparation method is the same as that of Comparative Example 5.

[0047] Comparative Example 8 A high-temperature resistant polysulfone composite material, expressed as a percentage by mass, comprises: 5% modified CNF, with the balance being polysulfone.

[0048] The preparation method is the same as that of Comparative Example 5.

[0049] Comparative Example 9 It is a pure polysulfone material, without the addition of modified MWCNT and modified CNF.

[0050] Test Example 1 The materials prepared in the examples and comparative examples were subjected to tensile tests at room temperature on samples measuring 70 × 10 × 0.01 mm, according to ASTM D-882, using a universal testing machine (model 4468, Instron, USA) with a crosshead speed of 1 mm / min. Thermal decomposition behavior was measured using a thermogravimetric analyzer (TGA Q50 V6.1 series, TA Instruments, Newcastle, Delaware, USA) in a nitrogen atmosphere from room temperature to 650°C at a heating rate of 20°C / min. The sample weight used for TGA testing was approximately 8–9 mg. The results are shown in Table 1.

[0051] Table 1. Performance Testing

[0052] Table 1 shows that the mechanical and thermal properties of the dual-filler synergistic system are significantly better than those of the single-filler or pure polysulfone materials. With increasing content of modified MWCNT and modified CNF, the material strength and modulus first increase and then decrease. The optimal overall performance is achieved when both are 1.5 wt.%, with a tensile strength of 82 MPa, an elastic modulus of 2720 MPa, an elongation at break of 42%, and an initial degradation temperature of 546°C. At this ratio, the material achieves a balance between rigidity and toughness. Excessively high filler content (above 3 wt.%) leads to agglomeration, reducing ductility. In contrast, while the single-filler system can improve the modulus to some extent, its overall performance is inferior to the dual-filler system, indicating a significant synergistic reinforcing effect between PDA-modified MWCNT and CNF.

Claims

1. A high-temperature resistant polysulfone composite material, characterized in that, By weight percentage, it comprises: 1%–3% modified multi-walled carbon nanotubes; 1%–3% modified carbon nanofibers; and the balance is polysulfone.

2. The polysulfone composite material according to claim 1, characterized in that, The mass ratio of the modified multi-walled carbon nanotubes to the modified carbon nanofibers is 1-2:1-2.

3. The polysulfone composite material according to claim 2, characterized in that, The mass ratio of polydopamine-modified multi-walled carbon nanotubes to polydopamine-modified carbon nanofibers is 1.5:1.

5.

4. The polysulfone composite material according to claim 3, characterized in that, The preparation method of the polydopamine-modified multi-walled carbon nanotubes is as follows: a certain amount of Tris is accurately weighed, dissolved in purified water, and the pH is adjusted to 8.5 with HCl to prepare a Tris-HCl buffer solution; then, 1.80 g of MWCNTs are weighed and dispersed in 600 mL of Tris-HCl buffer solution. After being fully dispersed at room temperature, the solution is immediately transferred to an ultrasonic instrument and ultrasonically dispersed at 40 kHz for 30 min; then, dopamine hydrochloride is added to the dispersion at a mass ratio of 1:1 (dopamine hydrochloride:MWCNTs) and stirred continuously at room temperature for 24 h; then, the solution is filtered and washed until the filtrate is colorless and neutral, and the resulting filter cake is vacuum dried at 40°C for 24 h.

5. The polysulfone composite material according to claim 4, characterized in that, The MWCNTs have an outer diameter of 8–15 nm, a length of 50 μm, and a specific surface area >140 m². 2 / g.

6. The polysulfone composite material according to claim 3, characterized in that, The modified carbon nanofibers were prepared as follows: 0.1 g Tris-HCl and 200 mL deionized water were added to a container, and the pH was adjusted to 8.5 with 0.05 mol / L HCl; then 0.2 g dopamine hydrochloride and 0.7 g CNFs were added, and the mixture was stirred at 25°C for 24 h; the product was washed several times with deionized water until neutral, then filtered and dried at 60°C for 24 h.

7. The polysulfone composite material according to claim 6, characterized in that, The CNFs have a diameter of 50~200nm and a length of 1~15µm.

8. The method for preparing the polysulfone composite material according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: Place the modified MWCNT and modified CNF in a quartz tube, then place it in a tube furnace and incubate at 450°C for 40 ml / min. -1 Oxidation was carried out at an air flow rate of 2 hours, with the quartz tube rotated every 30 minutes to improve the interfacial adhesion and dispersibility of modified MWCNT and modified CNF in the polysulfone matrix; Step S2: Disperse modified MWCNT and modified CNF in tetrahydrofuran, sonicate for 1 hour at a frequency of 22.5 kHz and a power of 100 W to obtain mixed solution A; then add polysulfone to mixed solution A; then add the required amount of polysulfone to solution A. The mass of tetrahydrofuran is 10 times the sum of the masses of modified MWCNT, modified CNF, and polysulfone; then stir for 30 minutes, sonicate for 10 minutes, stir for another 10 minutes, and sonicate for another 10 minutes. Step S3: Evaporate the mixed solution obtained in step S2 overnight at room temperature; finally, perform segmented heating to completely remove the solvent and obtain a high-temperature resistant polysulfone composite material.

9. The preparation method according to claim 8, characterized in that, The segmented heating process in step S3 is 2 hours at 60°C, 1 hour at 120°C, and 1 hour at 150°C.

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