Repairable ferroferric oxide microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material and preparation method thereof

Abstract

The present invention provides a Fe₃O₄ microsphere / multi-walled carbon nanotube / polyaryletherketone composite microwave absorbing material with reparability and a preparation method thereof, belonging to the technical field of polymer material preparation. This composite material is prepared by mixing Fe₃O₄ microspheres, multi-walled carbon nanotubes and polyaryletherketone, and the structural formula of the polyaryletherketone is as shown in Formula 1. The present invention improves the strength and hardness of polyaryletherketone through the cross-linked structure formed by the reaction of polyaryletherketone containing furan benzene side groups with multi-walled carbon nanotubes. In addition, through the research on the reparability of the composite material, it is found that this material has good reparability.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and in particular relates to a repairable ferrosoferric oxide microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material and a preparation method thereof. Background Art

[0002] Due to the rapid increase in the number of various highly integrated and high-power wireless communication systems and electronic devices, electromagnetic interference and electromagnetic pollution problems have become increasingly prominent, causing harm to human production and life that cannot be ignored. People are paying more and more attention to electromagnetic interference and radiation problems, and need to develop excellent electromagnetic wave (EM) absorbing materials to solve the problem of electromagnetic pollution. Electromagnetic wave absorbing materials have been widely studied. Nowadays, electromagnetic wave absorbing materials are developing in the direction of intelligence and miniaturization, but there are still problems such as complex preparation process and poor stability. Its performance is difficult to maintain for a long time and the maintenance cost is high, which limits its application to a certain extent, which puts higher requirements on the functionality of the material. For this reason, materials with recyclable and repairable properties have become the first choice for polymer matrices. Such self-repairable materials can greatly reduce maintenance costs and improve the durability of materials.

[0003] As an important magnetic material, ferroferric oxide is widely used in electromagnetic wave absorption materials due to its low cost, high saturation magnetization and high Curie temperature. 3 O 4 In the composite absorber of multi-walled carbon nanotubes (MWCNTs), Fe 3 O 4 The ability to bring magnetic loss to the material, MWCNTs enhance the dielectric loss capacity of the material. The special structure formed by hollow magnetic ferroferric oxide and multi-walled carbon nanotubes can not only enrich the interface inside the material, but also further increase the interaction between the electromagnetic wave and the absorber, which is conducive to the rapid loss of the incident electromagnetic wave. At the same time, the combination of the two also improves the electromagnetic matching characteristics and electromagnetic wave consumption capacity of the material, and has great application potential in the field of high-performance electromagnetic wave absorption materials. Special engineering plastics such as polyaryletherketone have excellent comprehensive properties such as good mechanical properties, radiation resistance, high temperature resistance and solvent resistance, and are widely used in both military and civilian high-tech fields. The stable covalent cross-linked structure in thermosetting polymer materials gives them excellent mechanical properties, solvent resistance, wear resistance and load-bearing capacity, but due to the existence of the covalent cross-linked structure, it is infusible and insoluble after curing and molding, and it is difficult to recycle and reprocess. By introducing dynamic covalent bonds into thermosetting materials by different methods, its processability can be improved and made repairable. Fe 3 O 4 / Multi-walled carbon nanotubes and polyaryletherketone are composited to prepare materials with good electromagnetic wave absorption performance, and also have strong thermal and mechanical properties. Compared with other polymers, polyaryletherketone as a matrix has obvious advantages in thermal and mechanical properties. Therefore, polyaryletherketone-based composite hybrid materials can be made into high-performance, stable, and strong absorbing materials. Summary of the invention

[0004] The purpose of the present invention is to provide a repairable ferroferric oxide microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material and a preparation method thereof. The composite absorbing material of the present invention has good repairability and has both dielectric loss and magnetic loss functions.

[0005] The present invention first provides a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material. The composite material is Fe 3 O 4 The microspheres, multi-walled carbon nanotubes and polyaryletherketone are mixed and prepared, and the structural formula of the polyaryletherketone is shown in Formula 1:

[0006]

[0007] In Formula 1, the value range of n is 16-23.

[0008] Preferably, the Fe 3 O 4 The mass ratio of microspheres, multi-walled carbon nanotubes and polyaryletherketone is (10-40):2:100.

[0009] Preferably, the multi-walled carbon nanotubes MWCNTs have a length of less than 30 μm and an outer diameter of 10-20 nm.

[0010] The present invention also provides a method for preparing a repairable ferroferric oxide microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material, comprising:

[0011] Step 1: Fe 3 O 4 The microspheres, multi-walled carbon nanotubes and poly(aryletherketone) are dissolved in a solvent and ultrasonically mixed to obtain a mixed solution;

[0012] Step 2: Filter the mixed solution of step 1, pour it onto a glass plate, dry out the solvent, then heat and bake it, cool it to room temperature, and heat and bake it for the second time to obtain a composite absorbing material.

[0013] Preferably, the solvent in step 1 is DMAc.

[0014] Preferably, the step of baking out the solvent in step 2 is carried out at 60-80° C. for 20-24 hours.

[0015] Preferably, the temperature-raising baking in step 2 is carried out at 80-90° C., 100-110° C. and 120-130° C. at normal pressure for 2-3 hours each.

[0016] Preferably, the second temperature rise baking in step 2 is to vacuum bake at 60-70°C, 80-90°C, 100-110°C and 120-130°C for 2-3 hours each.

[0017] Beneficial effects of the present invention

[0018] The present invention provides a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material and a preparation method thereof. The present invention synthesizes porous magnetic FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material by hydrothermal method. 3 O 4 Hollow microspheres, and then MWCNTs and porous magnetic Fe 3 O 4 Hollow microspheres are compounded with polyaryletherketone containing furanbenzene side groups to prepare porous magnetic hollow microspheres@multi-walled carbon nanotubes / polyaryletherketone thermosetting composite film. The composite material improves the strength and hardness of polyaryletherketone through the cross-linked structure formed by the reaction of polyaryletherketone containing furanbenzene side groups and multi-walled carbon nanotubes. In addition, the repairability of the composite material is found to have good repairability.

[0019] The present invention constructs dynamic covalent bonds through the Dials-Alder reaction of the furan group of the polyaryletherketone containing furan benzene side groups and multi-walled carbon nanotubes, and introduces a cross-linking structure through a heating reaction to further improve the strength and hardness of the polyaryletherketone, solidify the composite material structure in time, and construct a multi-dimensional interface and a spatial network structure, so that the material has both dielectric loss and magnetic loss functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 0.3gPEG400, 0.6gPEG400, 0.3gPEG1000, 0.6gPE1000, 0.3gPEG4000, 0.6gPEG4000 modified Fe 3 O 4 XRD spectrum of

[0021] Figure 2 0.3gPEG400, 0.6gPEG400, 0.3gPEG1000, 0.6gPE1000, 0.3gPEG4000, 0.6gPEG4000 modified Fe 3 O 4 IR spectrum of

[0022] Figure 3 0.3gPEG400, 0.6gPEG400, 0.3gPEG1000, 0.6gPE1000, 0.3gPEG4000, 0.6gPEG4000 modified Fe 3 O 4 SEM images of

[0023] Figure 4 0.3gPEG400, 0.6gPEG400, 0.3gPEG1000, 0.6gPE1000, 0.3gPEG4000, 0.6gPEG4000 modified Fe 3 O 4 Magnetic hysteresis loop diagram of

[0024] Figure 5 0.3gPEG400, 0.6gPEG400, 0.3gPEG1000, 0.6gPE1000, 0.3gPEG4000, 0.6gPEG4000 modified Fe 3 O 4 TGA diagram of

[0025] Figure 6 This is a scanning electron microscope image of the composite absorbing material prepared in Example 7 of the present invention after being treated at 170° C.;

[0026] Figure 7 This is a scanning electron microscope image of the composite absorbing material prepared in Example 8 of the present invention after being treated at 170° C.;

[0027] Figure 8 This is a scanning electron microscope image of the composite absorbing material prepared in Example 9 of the present invention after being treated at 170° C.;

[0028] Fig. 9 DMA-storage modulus curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170° C.;

[0029] Fig.10 DMA-storage modulus curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170° C.;

[0030] Fig.11 DMA-storage modulus curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170° C.;

[0031] Fig.12DMA-Tanδ curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170°C;

[0032] Fig.13 DMA-Tanδ curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170°C;

[0033] Fig.14 DMA-Tanδ curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170°C;

[0034] Fig.15 TGA curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170° C.;

[0035] Fig.16 TGA curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170° C.;

[0036] Fig.17 TGA curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170° C.;

[0037] Fig.18 The tensile-strain curves (a2-c2) of the composite film prepared in Examples 7-9 of the present invention (a1-c1) and the composite film treated at 170°C;

[0038] Fig.19 This is a graph showing the wave absorption performance of the composite film prepared in Example 7 of the present invention;

[0039] Fig. 20 This is a graph showing the wave absorption performance of the composite film prepared in Example 8 of the present invention;

[0040] Fig.21 This is a graph showing the wave absorption performance of the composite film prepared in Example 9 of the present invention. DETAILED DESCRIPTION

[0041] The present invention first provides a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material. The composite material is Fe 3 O 4 The microspheres, multi-walled carbon nanotubes and polyaryletherketone are mixed and prepared, and the structural formula of the polyaryletherketone is shown in Formula 1:

[0042]

[0043] In Formula 1, the value range of n is 16-23.

[0044] According to the present invention, the Fe 3 O 4 The mass ratio of microspheres, multi-walled carbon nanotubes and polyaryletherketone is (10-40):2:100.

[0045] According to the present invention, the magnetic hollow Fe 3 O 4 The microspheres are hollow structures with composite shells, the outermost shell of which is a polymer and the second outer shell is Fe 3 O 4 , its special hollow structure can increase the attenuation of electromagnetic waves inside it, and on the other hand, it can also reduce the density of the material. MWCNTs is a strong dielectric loss material, and its special tubular structure can reduce the density and increase the transmission path of electromagnetic waves; low-density polyaryletherketone (PAEK) as a polymer matrix can not only give the material excellent mechanical properties, high temperature resistance, corrosion resistance and other stability, but also construct dynamic covalent bonds between PAEK and multi-walled carbon nanotubes, thereby improving the processability of thermosetting materials and making them repairable.

[0046] The polyaryletherketone is a polyaryletherketone containing furan side groups, which can be prepared by the existing method without special restrictions. MWCNTs (purity>90%, length<30μm, outer diameter 10-20nm) were purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences.

[0047] The present invention also provides a method for preparing a repairable ferroferric oxide microsphere / multi-walled carbon nanotube / polyaryletherketone composite wave absorbing material, comprising:

[0048] Step 1: Fe 3 O 4 The microspheres, multi-walled carbon nanotubes and poly(aryletherketone) are dissolved in a solvent. Preferably, a portion of the poly(aryletherketone) is dissolved in a solvent to obtain a polymer solution, and then the remaining poly(aryletherketone), Fe 3 O 4 The microspheres and multi-walled carbon nanotubes are dissolved in a solvent, magnetically stirred, preferably for 2-3 hours, and then ultrasonicated, the ultrasonic time is preferably 4-5 hours, the uniformly dispersed mixed solution is added to the polymer solution, and ultrasonicated continuously, the ultrasonic time is preferably 2-3 hours, to obtain a mixed solution; the solvent is preferably DMAc;

[0049] Step 2: Filter the mixed solution of step 1, and then pour it on a glass plate, the size of the glass plate is preferably a 10cm×10cm glass plate, and bake out the solvent. Preferably, the mixed solution on the glass plate is baked at 60-80°C and normal pressure for 20-24 hours, and the solvent volatilized in the oven is wiped off every 6-8 hours. After most of the solvent is completely evaporated, the temperature is raised and baked, preferably at 80-90°C, 100-110°C, 120-130°C and normal pressure for 2-3 hours each. After cooling to room temperature, the temperature is raised and baked for the second time, preferably vacuuming and baking at 60-70°C, 80-90°C, 100-110°C, 120-130°C for 2-3 hours each. After the solvent is completely evaporated, the vacuum oven is cooled to room temperature, and the glass plate is taken out and soaked in deionized water to obtain a composite absorbing material.

[0050] According to the present invention, the Fe 3 O 4 The microspheres are preferably prepared according to the following method:

[0051] 1.1) Take ferric chloride, trisodium citrate twice the amount of ferric chloride, urea three times the amount of ferric chloride, polyacrylamide and polyethylene glycol (the mass ratio of polyacrylamide and polyethylene glycol to ferric chloride is 1:2 to 1:2.5 respectively);

[0052] 1.2) Place the ferric chloride, trisodium citrate and urea in step 1.1) into a beaker equipped with a magnetic stirrer, add distilled water, place the beaker on a magnetic stirrer, turn on the stirring switch until the raw materials are completely dissolved and dispersed, and turn off the stirring;

[0053] 1.3) Add the polyacrylamide and polyethylene glycol in step 1.1) to the beaker in step 1.2) and place it on a magnetic stirrer. Stir until completely dissolved and dispersed, then turn off stirring.

[0054] 1.4) Transfer the liquid in the beaker in step 1.3) to a high-temperature reaction kettle, place the reaction kettle in a hot air oven and set it to 190-210°C, react for 10-12 hours, turn off the oven, wait for the oven temperature to cool down, and then take out the reaction kettle and cool it to room temperature;

[0055] 1.5) The reaction solution in the reaction kettle in step 1.4) was centrifuged in batches in a centrifuge, and the lower layer of sediment after centrifugation was collected, and the sediment was washed with distilled water and alcohol three times each. The final product was placed in a watch glass, and the watch glass was placed in a vacuum drying oven, vacuumed at 50°C and dried, and the watch glass was taken out to obtain the hollow Fe 3 O 4 Microspheres.

[0056] The present invention is further described in detail below with reference to specific examples, and the raw materials involved in the examples are all commercially available.

[0057] Example 1

[0058] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place it on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.3g of PEG400 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower sediment after centrifugation, wash the sediment three times with distilled water and alcohol each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0059] Example 2

[0060] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.6g of PEG400 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower sediment after centrifugation, wash the sediment three times with distilled water and alcohol each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0061] Example 3

[0062] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place it on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.3g of PEG1000 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower precipitate after centrifugation, wash the precipitate three times with distilled water and alcohol each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0063] Example 4

[0064] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.6g of PEG1000 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower sediment after centrifugation, wash the sediment with distilled water and alcohol three times each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0065] Example 5

[0066] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place it on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.3g of PEG4000 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower sediment after centrifugation, wash the sediment three times with distilled water and alcohol each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0067] Example 6

[0068] Weigh 2.06g of trisodium citrate, 0.72g of urea, and 0.65g of ferric chloride into a 150ml conical flask equipped with a magnetic stirrer, then add 80mL of distilled water, place it on a magnetic stirrer, turn on the stirring until the raw materials are completely dispersed and dissolved, and turn off the stirring switch. Then add 0.6g of polyacrylamide and 0.6g of PEG4000 to the conical flask, turn on the stirring until it is completely dissolved, and turn off the stirring switch. Transfer the solution in the conical flask to a 100mL polytetrafluoroethylene-lined stainless steel autoclave, and then place it in a 200℃ electric heated blast drying oven to react for 12h. After the oven temperature cools down, take out the reactor and cool it to room temperature; centrifuge the reaction liquid in the reactor in batches in a centrifuge for multiple times, and collect the lower layer of sediment after centrifugation, wash the sediment with distilled water and alcohol three times each, and finally put the product generated after washing into a watch glass, put the watch glass into a vacuum drying oven, vacuum dry at 50℃, and take out the watch glass to obtain the hollow Fe 3 O 4 Microspheres.

[0069] Figure 1 0.3gPEG400 (Example 1), 0.6gPEG400 (Example 2), 0.3gPEG1000 (Example 3), 0.6gPE1000 (Example 4), 0.3gPEG4000 (Example 5), 0.6gPEG4000 (Example 6) modified Fe 3 O 4XRD spectra (af) show that the diffraction peaks of a, c, and e are sharper than those of b, d, and f, indicating that the Fe 3 O 4 Crystallization is better.

[0070] Figure 2 0.3gPEG400 (Example 1), 0.6gPEG400 (Example 2), 0.3gPEG1000 (Example 3), 0.6gPE1000 (Example 4), 0.3gPEG4000 (Example 5), 0.6gPEG4000 (Example 6) modified Fe 3 O 4 The infrared spectra (af) show that the six groups of samples have the same characteristic peaks, all at 3436cm -1 With 1614cm -1 Characteristic peaks appear near the stretching vibration peak and bending vibration peak of OH, indicating that the prepared Fe 3 O 4 The surface has hydroxyl groups and is hydrophilic; the strong characteristic peak observed around 586cm-1 corresponds to Fe 3 O 4 Fe-O stretching vibration. This indicates that the mass and molecular weight of PEG have an important influence on Fe 3 O 4 There is no effect on the structure of the product.

[0071] Figure 3 0.3gPEG400 (Example 1), 0.6gPEG400 (Example 2), 0.3gPEG1000 (Example 3), 0.6gPE1000 (Example 4), 0.3gPEG4000 (Example 5), 0.6gPEG4000 (Example 6) modified Fe 3 O 4 Scanning electron microscope images (af) show that when the amount of polyethylene glycol added is the same, the magnetic Fe 3 O 4 The size of the hollow nanospheres tends to decrease with the increase of the molecular weight of polyethylene glycol. The smallest average diameter of the spheres obtained in number (e) is 199.9nm, and the largest average diameter of the spheres obtained in number (c) is 257.8nm. It can be clearly seen from the box in number (d) that Fe 3 O 4 After the microspheres were broken, they showed a bowl-shaped structure, indicating that the prepared Fe 3 O 4 The samples are hollow microspheres.

[0072] Figure 4 0.3gPEG400 (Example 1), 0.6gPEG400 (Example 2), 0.3gPEG1000 (Example 3), 0.6gPE1000 (Example 4), 0.3gPEG4000 (Example 5), 0.6gPEG4000 (Example 6) modified Fe 3 O 4 The hysteresis loop diagram (af) shows that compared with the amount of polyethylene glycol added, the molecular weight of polyethylene glycol has an effect on the magnetic Fe 3 O 4 The saturation magnetization intensity of the hollow nanospheres has a greater influence. The coercive forces of (a), (b), (c), (d), (e), and (f) are 36.7Oe, 44.9Oe, 44.2Oe, 40.3Oe, 39.9Oe, and 39.1Oe, respectively. This shows that the porous magnetic hollow Fe 3 O 4 The reason why the microspheres have a lower coercivity is that the hollow Fe 3 O 4 is related to the size of nanocrystals.

[0073] Figure 5 0.3gPEG400 (Example 1), 0.6gPEG400 (Example 2), 0.3gPEG1000 (Example 3), 0.6gPE1000 (Example 4), 0.3gPEG4000 (Example 5), 0.6gPEG4000 (Example 6) modified Fe 3 O 4 TGA graphs (af) show that between 210℃ and 388℃, the mass decrease of samples numbered (a), (b), (c), (d), (e), and (f) is related to the decomposition of PEG, and the decrease percentages are 4.94%, 5.37%, 5.03%, 5.35%, 4.82%, and 5.22%, respectively. The decrease percentages of adding polyethylene glycols with different molecular weights are not much different, indicating that during the hydrothermal reaction, the mass of polyethylene glycol contained in the end is similar after adding polyethylene glycols with different molecular weights, and the thermal loss between 210℃ and 388℃ when adding 0.6g polyethylene glycol is greater than that when adding 0.3g polyethylene glycol.

[0074] Example 7

[0075] According to the feed ratio of 100:10:2, 1 g of PAEK-Fu polymer was weighed and dried thoroughly, and 0.1 g of Fe prepared in Example 3 was added. 3 O 4, 0.02gMWCNTs. 0.9gPAEK-Fu polymer was added to a 25ml conical flask, 10mlDMAc was added and magnetic stirring was performed to completely dissolve the polymer. At the same time, 0.1gFe 3 O 4 0.02gMWCNTs and 0.1gPAEK-Fu were dissolved in 2mlDMAc, magnetically stirred for 2 hours, and ultrasonicated for 4 hours. 3 O 4 The mixed solution of MWCNTs and MWCNTs was added to the polymer solution, and the mixed solution was ultrasonicated for 2 hours. The mixed solution was filtered on a copper mesh and then poured onto a glass plate of 10 cm × 10 cm in a vacuum oven preheated at 40°C. First, the solution was dried at 60°C and atmospheric pressure for 24 hours. During this period, the solvent evaporated in the oven was wiped off every 6 hours. After most of the solvent evaporated, the temperature was raised and dried at 80°C, 100°C, and 120°C for 2 hours each. After naturally cooling to room temperature, vacuum drying was carried out at 60°C, 80°C, 100°C, and 120°C for 2 hours each. After the solvent evaporated completely, the vacuum oven was cooled to room temperature, and the glass plate was taken out and soaked in deionized water to obtain PAEK-Fu:Fe 3 O 4 : Composite material film with the mass percentage of WMCNT being 100:10:2.

[0076] After the successfully prepared composite material was immersed in 180℃ heat treatment for 3 hours, the solution turned into black turbid liquid after ultrasound treatment, and obvious gel appeared after cooling to room temperature. After being treated at 180℃, the multi-walled carbon nanotubes in the composite material reacted with furan in the reverse reaction of DA reaction, so that the polymer and multi-walled carbon nanotubes in the composite material were separated, and reprocessing and repair were achieved.

[0077] Figure 6 This is a scanning electron microscope image of the composite absorbing material prepared in Example 7 of the present invention after being treated at 170° C. From the image, the morphology of the prepared composite absorbing material can be intuitively seen, and it can be observed that the MWCNTs are evenly dispersed in the matrix resin, which is beneficial to improving the mechanical properties of the material.

[0078] Fig. 9 DMA-storage modulus curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170°C. From the figure, changes in the storage modulus of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed.

[0079] Fig.12DMA-Tanδ curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170°C. From the figure, changes in the loss factor Tanδ of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed.

[0080] Fig.15 The TGA curves of the composite absorbing material (a1) prepared in Example 7 of the present invention and the composite absorbing material (a2) treated at 170°C. It can be observed from the figure that the prepared composite absorbing material and the composite absorbing material treated at 170°C have good thermal stability.

[0081] Fig.19 The wave absorption performance diagram of the composite film prepared in Example 7 of the present invention shows that when the material thickness is 3.0 mm, the maximum RL of the absorber to electromagnetic waves in the frequency range of 12.32-13.42 GHz exceeds -10 dB (effective bandwidth is 1.10 GHz), and more than 90% of the electromagnetic waves are lost. When the thickness is only 3.0 mm, the RL value reaches -16.40 dB at 12.97 GHz, confirming that the porous magnetic hollow microspheres @ multi-walled carbon nanotubes / polyaryletherketone composite material has excellent wave absorption performance.

[0082] Example 8

[0083] According to the feed ratio of 100:20:2, 1 g of PAEK-Fu polymer that is fully dried is weighed, and 0.2 g of Fe prepared in Example 3 is 3 O 4 , 0.02gMWCNTs. 0.9gPAEK-Fu polymer was added to a 25ml conical flask, 10mlDMAc was added and magnetic stirring was performed to completely dissolve the polymer. At the same time, 0.2gFe 3 O 4 0.02gMWCNTs and 0.1gPAEK-Fu were dissolved in 2mlDMAc, magnetically stirred for 2 hours, and ultrasonicated for 4 hours. 3 O 4The mixed solution of MWCNTs and MWCNTs was added to the polymer solution, and the mixed solution was ultrasonicated for 2 hours. The mixed solution was filtered on a copper mesh and then poured onto a glass plate of 10 cm × 10 cm in a vacuum oven preheated at 40°C. First, the solution was dried at 60°C and atmospheric pressure for 24 hours. During this period, the solvent evaporated in the oven was wiped off every 6 hours. After most of the solvent evaporated, the temperature was raised and dried at 80°C, 100°C, and 120°C for 2 hours each. After naturally cooling to room temperature, vacuum drying was carried out at 60°C, 80°C, 100°C, and 120°C for 2 hours each. After the solvent evaporated completely, the vacuum oven was cooled to room temperature, and the glass plate was taken out and soaked in deionized water to obtain PAEK-Fu:Fe 3 O 4 : Composite material film with the mass percentage of WMCNT being 100:20:2.

[0084] After the successfully prepared composite material was immersed in 180℃ heat treatment for 3 hours, the solution turned into black turbid liquid after ultrasound treatment, and obvious gel appeared after cooling to room temperature. After being treated at 180℃, the multi-walled carbon nanotubes in the composite material reacted with furan in the reverse reaction of DA reaction, so that the polymer and multi-walled carbon nanotubes in the composite material were separated, and reprocessing and repair were achieved.

[0085] Figure 7 This is a scanning electron microscope image of the composite absorbing material prepared in Example 8 of the present invention after being treated at 170° C. From the image, the morphology of the prepared composite absorbing material can be intuitively seen, and it can be observed that the MWCNTs are evenly dispersed in the matrix resin, which is beneficial to improving the mechanical properties of the material.

[0086] Fig.10 DMA-storage modulus curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170°C. From the figure, changes in the storage modulus of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed.

[0087] Fig.13 DMA-Tanδ curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170°C. From the figure, changes in the loss factor Tanδ of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed.

[0088] Fig.16 The TGA curves of the composite absorbing material (b1) prepared in Example 8 of the present invention and the composite absorbing material (b2) treated at 170°C. It can be observed from the figure that the prepared composite absorbing material and the composite absorbing material treated at 170°C have good thermal stability.

[0089] Fig. 20 This is a graph of the wave absorption performance of the composite film prepared in Example 8 of the present invention. It can be seen from the figure that when the material thickness is 2.0 mm, the effective bandwidth exceeding -10 dB is 3.86 GHz, and when the thickness is only 2.5 mm, the RL value reaches -35.98 dB at 10.37 GHz, confirming that the porous magnetic hollow microspheres @ multi-walled carbon nanotubes / polyaryletherketone composite material has excellent wave absorption performance.

[0090] Example 9

[0091] According to the feed ratio of 100:40:2, 1 g of PAEK-Fu polymer that is fully dried is weighed, and 0.4 g of Fe prepared in Example 3 is 3 O 4 , 0.02gMWCNTs. 0.9gPAEK-Fu polymer was added to a 25ml conical flask, 10mlDMAc was added and magnetic stirring was performed to completely dissolve the polymer. At the same time, 0.4gFe 3 O 4 0.02gMWCNTs and 0.1gPAEK-Fu were dissolved in 2mlDMAc, magnetically stirred for 2 hours, and ultrasonicated for 4 hours. 3 O 4 The mixed solution of MWCNTs and MWCNTs was added to the polymer solution, and the mixed solution was ultrasonicated for 2 hours. The mixed solution was filtered on a copper mesh and then poured onto a glass plate of 10 cm × 10 cm in a vacuum oven preheated at 40°C. First, the solution was dried at 60°C and atmospheric pressure for 24 hours. During this period, the solvent evaporated in the oven was wiped off every 6 hours. After most of the solvent evaporated, the temperature was raised and dried at 80°C, 100°C, and 120°C for 2 hours each. After naturally cooling to room temperature, vacuum drying was carried out at 60°C, 80°C, 100°C, and 120°C for 2 hours each. After the solvent evaporated completely, the vacuum oven was cooled to room temperature, and the glass plate was taken out and soaked in deionized water to obtain PAEK-Fu:Fe 3 O 4 : Composite material film with the mass percentage of WMCNT being 100:40:2.

[0092] After the successfully prepared composite material was immersed in 180℃ heat treatment for 3 hours, the solution turned into black turbid liquid after ultrasound treatment, and obvious gel appeared after cooling to room temperature. After being treated at 180℃, the multi-walled carbon nanotubes in the composite material reacted with furan in the reverse reaction of DA reaction, so that the polymer and multi-walled carbon nanotubes in the composite material were separated, and reprocessing and repair were achieved.

[0093] Figure 8This is a scanning electron microscope image of the composite absorbing material prepared in Example 9 of the present invention after being treated at 170°C. From the image, the morphology of the prepared composite absorbing material can be intuitively seen, and it can be observed that the MWCNTs are evenly dispersed in the matrix resin, which is beneficial to improving the mechanical properties of the material. Fig.12 , 13 By comparison, it is found that with the porous magnetic Fe 3 O 4 With the increase of hollow microsphere content, the density of hollow microspheres in the film gradually increased and was evenly distributed. Even when the mass ratio of matrix resin to hollow microspheres reached 100:40, the hollow microspheres did not aggregate and were able to be evenly dispersed.

[0094] Fig.11 The DMA-storage modulus curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170°C are shown in the figure. The changes in the storage modulus of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed from the figure. Fig.13 , 14 The results show that as the test temperature increases, the storage modulus of all composite absorbing materials does not fluctuate greatly in the early stage, but when the temperature rises to a certain extent, the storage modulus shows a sharp drop. This indicates that the DA reaction has occurred between the MWCNTs and the polymer matrix in the composite absorbing material system, and a thermoreversible covalent cross-linking network has been successfully constructed. The cross-linking structure gives the composite material a good ability to maintain the storage modulus. As the test temperature increases, the thermoreversible covalent cross-linking structure inside the composite absorbing material continues to move in the direction of the reverse reaction. When a certain temperature is reached, the DA reverse reaction is triggered, the covalent bonds in the cross-linking structure are broken, and the storage modulus of the material decreases rapidly. With the increase of the furan group content in the composite absorbing material and the increase of the heat treatment temperature, the DA reaction inside the composite absorbing material is more complete, the number of cross-linking points increases, the cross-linking density increases, and the triggering temperature of the DA reverse reaction also increases. The occurrence of the DA reaction and its reverse reaction in the composite absorbing material system realizes the repairability of the material.

[0095] Fig.14 The DMA-Tanδ curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170°C are shown in the figure. The changes in the loss factor Tanδ of the prepared composite absorbing material and the composite absorbing material treated at 170°C can be observed from the figure. Fig.16 , 17From the joint analysis, it can be seen that with the increase of the test temperature, all the composite absorbing materials have undergone glass transition. It can be seen from the figure that the glass transition temperature of the composite absorbing materials prepared in different proportions increases significantly after heat treatment. This is because after the composite absorbing materials are subjected to the heat treatment temperature, the DA reaction in the composite absorbing material system is more complete, and the cross-linking density increases accordingly, which improves the rigidity of the molecular chain segments, increases the intermolecular force, and makes the movement of the molecular chain segments more difficult, thereby improving the glass transition temperature and heat resistance of the composite absorbing materials.

[0096] Fig.17 The TGA curves of the composite absorbing material (c1) prepared in Example 9 of the present invention and the composite absorbing material (c2) treated at 170°C. It can be observed from the figure that the prepared composite absorbing material and the composite absorbing material treated at 170°C have good thermal stability.

[0097] Fig.18 The tensile-strain curves of the composite film (a1-c1) prepared in Examples 7-9 of the present invention and the composite film treated at 170°C (a2-c2) show that the mechanical properties of the composite material are significantly improved after heat treatment. This is because as the temperature increases, the DA reaction proceeds more completely, and the crosslinking density in the composite material gradually increases, resulting in a gradual increase in the tensile strength of the composite material and a gradual decrease in the elongation at break. However, as the porous magnetic Fe 3 O 4 As the content of hollow microspheres increases, their tensile strength decreases. The presence of more interfaces between the hollow microspheres and the resin will cause interface fractures and make the material brittle. 3 O 4 As the content of hollow microspheres increases, the elongation at break gradually decreases.

[0098] Fig.21 This is a graph of the wave absorbing performance of the composite film prepared in Example 9 of the present invention. It can be seen from the figure that when the material thickness is 5.5 mm, the maximum RL of the absorber to electromagnetic waves in the frequency ranges of 4.71-6.26 GHz and 15.19-17.62 GHz exceeds -10 dB (the effective bandwidth is 3.97 GHz). When the thickness is 5.5 mm, the RL value reaches -39.34 dB at 16.35 GHz, confirming that the porous magnetic hollow microspheres @ multi-walled carbon nanotubes / polyaryletherketone composite material has excellent wave absorbing performance.

Claims

1. A repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material. It is characterized in that The composite material was synthesized by hydrothermal method with porous magnetic Fe 3 O 4 Hollow microspheres, and then MWCNTs and porous magnetic Fe 3 O 4 The hollow microspheres are compounded with poly(aryletherketone) containing furanyl side groups to prepare a porous magnetic hollow microsphere@multi-walled carbon nanotube / poly(aryletherketone) thermosetting composite film, wherein the structural formula of the poly(aryletherketone) is shown in Formula 1: In formula 1, the value range of n is 16-23; The Fe 3 O 4 The mass ratio of microspheres, multi-walled carbon nanotubes and polyaryletherketone is (10-40):2:100; The Fe 3 O 4 The microspheres were prepared as follows: 1.1) Take ferric chloride, trisodium citrate twice the amount of ferric chloride, urea three times the amount of ferric chloride, polyacrylamide and polyethylene glycol; the mass ratio of polyacrylamide and polyethylene glycol to ferric chloride is 1:2 to 1:2.5 respectively; 1.2) Place the ferric chloride, trisodium citrate and urea in step 1.1) into a beaker equipped with a magnetic stirrer, add distilled water, place the beaker on a magnetic stirrer, turn on the stirring switch until the raw materials are completely dissolved and dispersed, and turn off the stirring; 1.3) Add the polyacrylamide and polyethylene glycol in step 1.1) to the beaker in step 1.2) and place it on a magnetic stirrer. Stir until completely dissolved and dispersed, then turn off stirring. 1.4) Transfer the liquid in the beaker in step 1.3) to a high-temperature reaction kettle, place the reaction kettle in a hot air oven and set it to 190-210°C, react for 10-12 hours, turn off the oven, wait for the oven temperature to cool down, and then take out the reaction kettle and cool it to room temperature; 1.5) The reaction solution in the reaction kettle in step 1.4) was centrifuged in batches in a centrifuge, and the lower layer of sediment after centrifugation was collected, and the sediment was washed with distilled water and alcohol three times each. The final product was placed in a watch glass, and the watch glass was placed in a vacuum drying oven, vacuumed at 50°C and dried, and the watch glass was taken out to obtain the hollow Fe 3 O 4 Microspheres.

2. The repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 1, It is characterized in that The multi-walled carbon nanotubes MWCNTs have a length of less than 30 μm and an outer diameter of 10-20 nm.

3. The method for preparing a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 1, It is characterized in that include: Step 1: Fe 3 O 4 The microspheres, multi-walled carbon nanotubes and poly(aryletherketone) are dissolved in a solvent and ultrasonically mixed to obtain a mixed solution; Step 2: Filter the mixed solution of step 1, pour it onto a glass plate, dry out the solvent, then heat and bake it, cool it to room temperature, and heat and bake it for the second time to obtain a composite absorbing material.

4. The method for preparing a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 3, It is characterized in that The solvent for step 1 is DMAc.

5. The method for preparing a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 3, It is characterized in that The step 2 of baking out the solvent is to bake at 60-80° C. for 20-24 hours.

6. The method for preparing a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 3, It is characterized in that The temperature rising baking in step 2 is baking at 80-90° C., 100-110° C. and 120-130° C. at normal pressure for 2-3 hours each.

7. The method for preparing a repairable FeO2 microsphere / multi-walled carbon nanotube / polyaryletherketone composite absorbing material according to claim 3, It is characterized in that The second temperature rise baking in step 2 is to vacuum bake at 60-70°C, 80-90°C, 100-110°C and 120-130°C for 2-3 hours respectively.

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