Polyetherimide fiber reinforced polyimide aerogel material as well as preparation method and application thereof
By introducing polyetherimide fibers into polyimide aerogel, the mechanical strength and sound absorption properties of the aerogel are improved, overcoming the shortcomings of polyimide aerogel materials in terms of lightweight, high-efficiency flame retardancy and thermal insulation, making it suitable for a variety of complex environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-06
- Publication Date
- 2026-04-07
AI Technical Summary
Existing polyimide aerogel materials are difficult to simultaneously achieve lightweight, high-efficiency flame retardancy, excellent heat insulation and sound absorption properties, and long-term dynamic fatigue stability.
Polyetherimide fibers are used as reinforcements, dispersed in the pore walls of polyimide aerogels and interspersed therein as a skeleton, to improve the mechanical properties and roughness of the pore walls. Polyetherimide fiber-reinforced polyimide aerogels are prepared by methods including stirring, freeze drying and thermal imidization treatment.
It improves the fatigue resistance and sound absorption of aerogel while maintaining its thermal insulation performance, enhances its flame retardancy, and has low density and low thermal conductivity, making it suitable for traffic noise reduction, aerospace and equipment vibration reduction.
Smart Images
Figure CN121801152A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of multifunctional composite material preparation technology, specifically relating to a polyetherimide fiber reinforced polyimide aerogel material, its preparation method, and its application. Background Technology
[0002] Aerogels, as solid materials with nanoporous structures, exhibit significant advantages in efficient thermal insulation and sound absorption due to their extremely low density and high porosity. Their nanoscale pore structure effectively suppresses air convection heat transfer and significantly reduces solid-state heat conduction, thus endowing the material with excellent thermal insulation performance. Simultaneously, sound waves passing through the porous network are significantly dissipated due to air viscous resistance and internal friction, achieving the conversion of sound energy into heat energy and demonstrating good sound absorption potential.
[0003] Aerogels can be broadly classified into inorganic and organic categories based on their chemical composition. Organic aerogels, in particular, have attracted widespread attention due to their ability to overcome the inherent drawbacks of inorganic aerogels, such as high brittleness and poor flexibility. Polyimide aerogels, as an important type of organic aerogel, retain the excellent thermal stability, mechanical strength, and chemical resistance of polyimide polymers while also possessing typical aerogel characteristics, such as high specific surface area, high porosity, and ultra-low thermal conductivity. Therefore, they exhibit outstanding performance in various organic aerogel systems. However, pure polyimide aerogels typically exhibit a sheet-like porous structure, resulting in insufficient mechanical strength and toughness. While some existing research aims to improve the performance of polyimide aerogels, none can simultaneously achieve lightweight, highly efficient flame retardancy, excellent thermal insulation and sound absorption properties, and long-term dynamic fatigue stability.
[0004] Therefore, under the current technological conditions, developing a multifunctional polyimide aerogel material that can simultaneously achieve lightweight, high-efficiency flame retardancy, excellent heat insulation and sound absorption properties, and long-term dynamic fatigue stability remains a key technical challenge that urgently needs to be overcome in this field. Summary of the Invention
[0005] To address the challenge of simultaneously achieving sound absorption, heat insulation, and flame retardancy with fatigue resistance in existing polyimide aerogel materials, this invention provides a polyetherimide fiber-reinforced polyimide aerogel material, its preparation method, and its applications. This overcomes the difficulty of polyimide aerogel materials simultaneously achieving multiple functions and adapting to complex environments. This invention uses polyetherimide fibers as the reinforcing material. A portion of the polyetherimide fibers is dispersed within the pore walls of the polyimide aerogel, while another portion of the fibers acts as a skeleton interwoven within the polyimide aerogel matrix. This improves the mechanical properties of the aerogel pore walls, giving them excellent fatigue resistance, and also increases the roughness of the pore walls, enhancing sound absorption performance.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a method for preparing a polyetherimide fiber-reinforced polyimide aerogel material, comprising the following steps:
[0007] Polyetherimide (PEI) fibers were dispersed in water to obtain a fiber dispersion. Then, polyamic acid salts and organic amines were added to the fiber dispersion. After the polyamic acid salts were completely dissolved, stirring was continued, followed by freeze-drying. Finally, thermal imidization was performed under vacuum to obtain the polyetherimide fiber-reinforced polyimide (PI) aerogel material. Continued stirring was to ensure a more uniform dispersion of the polyetherimide fibers.
[0008] Furthermore, the polyetherimide fiber has a length of 0.5~1mm and a diameter of 1~5μm;
[0009] Preferably, the stirring speed is 300~400 r / min, and the stirring time is 6~8 h.
[0010] Furthermore, the preparation method of the polyetherimide fiber is as follows:
[0011] Polyetherimide is added to a polar solvent and stirred at 60-80°C for 6-8 hours to obtain a polyetherimide solution; then, the polyetherimide fiber is obtained by electrospinning.
[0012] Preferably, the polar solvent is at least one of N-methylpyrrolidone and dimethylformamide;
[0013] Preferably, the mass ratio of the polyetherimide to the polar solvent is (0.3~0.45):1;
[0014] Preferably, the stirring speed is 400~500 r / min;
[0015] Preferably, the electrospinning process parameters are set as follows: voltage 20~30kV, spinning distance 15~20cm, injection speed 1~1.2mm / min, humidity 40~60%, and temperature 20~30℃.
[0016] Furthermore, the preparation method of the polyamic acid salt is as follows:
[0017] Diamine is dissolved in a polar solvent at 0-5°C to obtain a diamine solution. Dianhydride is added to the diamine solution and stirred for 6-8 hours. Then an organic amine is added and stirred for 2-4 hours. After that, it is poured into an organic solvent to precipitate. The precipitate is crushed and washed repeatedly until the filtrate is clear. Finally, it is dried at 60-80°C under vacuum for 24-48 hours to obtain polyamic acid salt.
[0018] Preferably, the diamine is one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diamino-2,2'-dimethylbiphenyl;
[0019] Preferably, the dianhydride is one of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxobisphthalic anhydride, and pyromellitic dianhydride;
[0020] Preferably, the polar solvent is one of dimethylacetamide, N-methylpyrrolidone, and dimethylformamide;
[0021] Preferably, the organic amine is triethylamine or dipropylamine;
[0022] Preferably, the organic solvent is at least one selected from methanol, ethanol, isopropanol, and acetone;
[0023] Preferably, the molar ratio of the diamine, dianhydride, and organic amine is 1:(1~1.01):1;
[0024] Preferably, the stirring speed is 300~400 r / min;
[0025] Preferably, the stirring speed is 300~400 r / min.
[0026] Furthermore, the organic amine is triethylamine or dipropylamine.
[0027] Further, by weight, the composition includes 0.1 to 0.7 parts by weight of polyetherimide fiber, 0.5 to 1.5 parts by weight of polyamate, 0.2 to 0.5 parts by weight of organic amine, and 90 to 100 parts by weight of water.
[0028] Furthermore, the freeze-drying specifically involves first freezing in a freeze-drying apparatus, and then drying.
[0029] The freezing temperature is -30 to -50°C, and the freezing time is 4 to 8 hours.
[0030] The drying temperature is -50 to -60°C, the drying vacuum degree is 1 to 5 Pa, and the drying time is 72 to 96 hours.
[0031] Furthermore, the temperature of the thermal imidization is 250~350℃, and the time of the thermal imidization is 2~3h.
[0032] On the other hand, the present invention provides a polyetherimide fiber reinforced polyimide aerogel material, which is prepared by any of the preparation methods described above.
[0033] On the other hand, the present invention provides an application of polyetherimide fiber reinforced polyimide aerogel material prepared by any of the above-described preparation methods, or the polyetherimide fiber reinforced polyimide aerogel material described above, in the fields of traffic noise reduction, aerospace and equipment vibration reduction.
[0034] Compared with the prior art, the present invention has the following beneficial effects:
[0035] (1) The preparation process of this invention is simple and easy to operate, and it is a convenient and efficient preparation method.
[0036] (2) The polyetherimide fiber used in this invention can inhibit the shrinkage of aerogel and provide support for the pore walls of aerogel, thereby enhancing the mechanical strength of aerogel and giving it good fatigue resistance. On the other hand, it can effectively improve the flame retardancy and sound absorption effect of aerogel, while the heat insulation performance will not be reduced.
[0037] (3) The density of the polyetherimide fiber-reinforced polyimide aerogel material of the present invention is as low as 0.02021 g / cm³. 3 Its thermal conductivity is as low as 0.03079 W / m². -1 K -1 With a limiting oxygen index as high as 47% and a sound absorption coefficient as high as 0.99, the energy loss coefficient after 1000 compression cycles is only 25.09%. This indicates that polyetherimide fiber, as a reinforcement, not only improves the sound absorption and flame retardant properties of aerogel without affecting its thermal insulation performance, but also gives it excellent fatigue resistance, making it suitable for various complex environments and promising broad application prospects in fields such as traffic noise reduction, aerospace, and equipment vibration reduction. Attached Figure Description
[0038] Figure 1 These are scanning electron microscope (SEM) images of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 of this invention and the polyimide aerogels prepared in Comparative Example 1.
[0039] Figure 2 This is a comparison chart of the sound absorption coefficients of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 of the present invention and the polyimide aerogels prepared in Comparative Example 1 in the range of 1000-6300Hz.
[0040] Figure 3 This is a comparison chart of the thermal conductivity coefficients of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 of this invention and the polyimide aerogels prepared in Comparative Example 1.
[0041] Figure 4This is a comparison chart of the limiting oxygen index of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 of this invention and the polyimide aerogels prepared in Comparative Example 1.
[0042] Figure 5 The stress-strain curves are shown for the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 of this invention and the polyimide aerogels prepared in Comparative Example 1.
[0043] Figure 6 The stress-strain curve of polyetherimide fiber-reinforced polyimide aerogel PI-2 prepared in Example 2 of the present invention after 1000 compression cycles at 50% strain is shown. Detailed Implementation
[0044] To better understand the content of this invention, the following detailed description is provided in conjunction with specific implementation methods. However, the scope of protection of this invention is not limited to the following embodiments.
[0045] Example 1
[0046] (1) Preparation of polyetherimide fibers
[0047] 2.6 g of polyetherimide particles were added to a mixed solvent of 3.7 g of N-methylpyrrolidone and 3.7 g of dimethylformamide, and dissolved by mechanical stirring at 400 r / min for 8 h at 60 °C to obtain a polyetherimide solution.
[0048] A 10 mL syringe was used to draw up the polyetherimide solution, and polyetherimide fibers with a diameter of 2.5 μm were prepared by electrospinning. The electrospinning settings were: voltage 20 kV, spinning distance 15 cm, injection speed 1 mm / min, humidity 60%, and temperature 20 °C.
[0049] (2) Preparation of polyamic acid salt
[0050] At 0°C, 20.024 g of 4,4'-diaminodiphenyl ether and 350 g of dimethylacetamide were slowly added to a flask and mechanically stirred at 300 r / min for 1 h to completely dissolve them, obtaining a diamine solution. 31.021 g of 4,4'-oxophthalic anhydride was gradually added to the diamine solution, and stirring was continued at 300 r / min for 8 h. Then, 10.119 g of triethylamine was slowly added dropwise, and the reaction was mechanically stirred at 300 r / min for 3 h. The reaction product was then poured into ethanol to precipitate it. The precipitate was crushed and washed three times with ethanol until the filtrate was clear. Finally, it was dried at 60°C under vacuum for 24 h to obtain polyamic acid salt.
[0051] (3) Preparation of polyetherimide fiber reinforced polyimide aerogel
[0052] First, 0.03 g of polyetherimide fiber was added to 30 g of deionized water. The fiber was then homogenized to 1 mm in length using a homogenizer and uniformly dispersed in the water to obtain a fiber dispersion. Next, 0.3 g of polyamic acid salt was added to the fiber dispersion, along with 0.1 g of triethylamine to promote dissolution. After the polyamic acid salt was completely dissolved, the mixture was stirred at 300 r / min for 6 h. After thorough mixing, the mixture was poured into a silicone mold. The samples were then transferred to a freeze dryer and first frozen at -30 °C for 8 h. Then, they were continuously freeze-dried at -50 °C under vacuum conditions (5 Pa) for 72 h. Finally, the samples were placed in a vacuum oven and subjected to thermal imidization treatment at 250 °C for 3 h under vacuum to obtain polyetherimide fiber-reinforced polyimide aerogel, named PI-1.
[0053] Example 2
[0054] The difference between this embodiment and Embodiment 1 is that the mass of the polyetherimide fiber in Embodiment 1 is changed to 0.09g, and the resulting polyetherimide fiber reinforced polyimide aerogel is named PI-2.
[0055] Example 3
[0056] The difference between this embodiment and Embodiment 1 is that the mass of the polyetherimide fiber in Embodiment 1 is changed to 0.15g, and the resulting polyetherimide fiber reinforced polyimide aerogel is named PI-3.
[0057] Example 4
[0058] The difference between this embodiment and Embodiment 1 is that the mass of the polyetherimide fiber in Embodiment 1 is changed to 0.21g, and the resulting polyetherimide fiber reinforced polyimide aerogel is named PI-4.
[0059] Comparative Example 1
[0060] The difference between Comparative Example 1 and Example 1 is that polyetherimide fiber is not added; otherwise, they are the same as in Example 1. The resulting polyimide aerogel is named PI-0.
[0061] The density of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1 was tested. The weights were measured using a measuring balance, and the dimensions were measured using calipers. Calculations showed that the densities of Examples 1-4 and Comparative Example 1 were 0.02021 g / cm³. 3 0.02244 g / cm 3 0.02409 g / cm 3 0.02663 g / cm 3 and 0.01873 g / cm3 .
[0062] SEM tests were performed on the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1. The results are as follows: Figure 1 As shown in the figure, it can be clearly seen that with the addition of polyetherimide fibers, the pore walls of the aerogel combine with the fibers, and the fibers connect different pore walls, giving the aerogel pores good mechanical properties.
[0063] The sound absorption performance of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1 was tested. Specifically, the sound absorption coefficients in the 1000-6300 Hz range were measured using an impedance tube. The results are as follows: Figure 2 As shown. According to Figure 2 It can be seen that the sound absorption coefficients of Examples 1, 2 and 3 are significantly improved compared with Comparative Example 1, and can be widely used in the field of sound absorption. Example 4 has an improved sound absorption coefficient in the high-frequency range above 6000Hz, and is suitable for the field of high-frequency noise reduction.
[0064] The thermal insulation performance of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1 was tested, specifically by measuring their thermal conductivity coefficients using a thermal conductivity meter. The results are as follows: Figure 3 As shown. According to Figure 3 It can be seen that the thermal conductivity coefficients of the embodiments and comparative examples are very low, and therefore they all have good thermal insulation performance.
[0065] The flame retardant properties of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1 were tested, specifically by measuring their limiting oxygen index using a limiting oxygen index meter. The results are as follows: Figure 4 As shown. According to Figure 4 It can be seen that the limiting oxygen index of Examples 1, 2, 3 and 4 is improved compared with Comparative Example 1. Among them, the limiting oxygen index of PI-2, PI-3 and PI-4 all reach 47%, and the UL94 is V-0 level.
[0066] The mechanical properties of the polyetherimide fiber-reinforced polyimide aerogels prepared in Examples 1-4 and the polyimide aerogel prepared in Comparative Example 1 were tested. Specifically, the stress-stress change curves under the same strain were measured using a universal testing machine. The results are as follows: Figure 5 As shown. By analyzing... Figure 5 The energy loss coefficients of Examples 1-4 and Comparative Example 1 were calculated by integral of the stress-strain curves to be 34.27%, 27.70%, 28.95%, 35.244% and 36.65%, respectively. It can be seen that Example 2 has the lowest energy loss coefficient.
[0067] The fatigue resistance of the polyetherimide fiber-reinforced polyimide aerogel prepared in Example 2 was tested by using a universal testing machine to perform 1000 compression cycles at 50% strain. The results are as follows: Figure 6 As shown. According to Figure 6 It can be seen that, after undergoing 1000 compression cycles with 50% strain, Example 2 still maintains more than 95% of its mechanical strength. Figure 6 The energy loss coefficient after 1000 compression cycles is only 25.09% according to the integral calculation of the stress-strain curve.
[0068] The above description is only a specific embodiment of the present invention and not all embodiments. Any equivalent modifications made by those skilled in the art to the technical solutions of the present invention by reading the present invention specification shall be covered by the claims of the present invention.
Claims
1. A method for preparing a polyetherimide fiber-reinforced polyimide aerogel material, characterized in that, Includes the following steps: Polyetherimide fibers are dispersed in water to obtain a fiber dispersion. Then, polyamic acid salt and organic amine are added to the fiber dispersion. After the polyamic acid salt is completely dissolved, stirring is continued. Then, freeze-drying is performed, and finally, thermal imidization is carried out under vacuum to obtain the polyetherimide fiber-reinforced polyimide aerogel material.
2. The preparation method according to claim 1, characterized in that, The polyetherimide fiber has a length of 0.5~1mm and a diameter of 1~5μm; Preferably, the stirring speed is 300~400 r / min, and the stirring time is 6~8 h.
3. The preparation method according to claim 1, characterized in that, The polyetherimide fiber is prepared by: Polyetherimide is added to a polar solvent and stirred at 60-80°C for 6-8 hours to obtain a polyetherimide solution; then, the polyetherimide fiber is obtained by electrospinning. Preferably, the polar solvent is at least one of N-methylpyrrolidone and dimethylformamide; Preferably, the mass ratio of the polyetherimide to the polar solvent is (0.3~0.45):1; Preferably, the stirring speed is 400~500 r / min; Preferably, the electrospinning process parameters are set as follows: voltage 20~30kV, spinning distance 15~20cm, injection speed 1~1.2mm / min, humidity 40~60%, and temperature 20~30℃.
4. The preparation method according to claim 1, characterized in that, The preparation method of the polyamic acid salt is as follows: Diamine is dissolved in a polar solvent at 0-5°C to obtain a diamine solution. Dianhydride is added to the diamine solution and stirred for 6-8 hours. Then an organic amine is added and stirred for 2-4 hours. After that, it is poured into an organic solvent to precipitate. The precipitate is crushed and washed repeatedly until the filtrate is clear. Finally, it is dried at 60-80°C under vacuum for 24-48 hours to obtain polyamic acid salt. Preferably, the diamine is one of p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diamino-2,2'-dimethylbiphenyl; Preferably, the dianhydride is one of 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxobisphthalic anhydride, and pyromellitic dianhydride; Preferably, the polar solvent is one of dimethylacetamide, N-methylpyrrolidone, and dimethylformamide; Preferably, the organic amine is triethylamine or dipropylamine; Preferably, the organic solvent is at least one selected from methanol, ethanol, isopropanol, and acetone; Preferably, the molar ratio of the diamine, dianhydride, and organic amine is 1:(1~1.01):1; Preferably, the stirring speed is 300~400 r / min; Preferably, the stirring speed is 300~400 r / min.
5. The preparation method according to claim 1, characterized in that, The organic amine is triethylamine or dipropylamine.
6. The preparation method according to claim 1, characterized in that, By weight, the composition is: 0.1-0.7 parts by weight of polyetherimide fiber, 0.5-1.5 parts by weight of polyamate, 0.2-0.5 parts by weight of organic amine, and 90-100 parts by weight of water.
7. The preparation method according to claim 1, characterized in that, The freeze-drying process specifically involves first freezing the food in a freeze-drying apparatus, and then drying it. The freezing temperature is -30 to -50°C, and the freezing time is 4 to 8 hours. The drying temperature is -50 to -60°C, the drying vacuum degree is 1 to 5 Pa, and the drying time is 72 to 96 hours.
8. The preparation method according to claim 1, characterized in that, The temperature of the thermal imidization is 250~350℃, and the time of the thermal imidization is 2~3h.
9. A polyetherimide fiber-reinforced polyimide aerogel material, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 8.
10. The application of the polyetherimide fiber reinforced polyimide aerogel material prepared by any of the preparation methods according to claims 1 to 8 or the polyetherimide fiber reinforced polyimide aerogel material according to claim 9 in the fields of traffic noise reduction, aerospace and equipment vibration reduction.