Modified PBO fiber as well as preparation method and application thereof

Abstract

The invention relates to a modified PBO fiber as well as a preparation method and application thereof, and the modified PBO fiber is prepared by coating the surface of the PBO fiber with a monolithic layer MXene by using a supramolecular cross-linked network of polybenzimidazole PBI and Cu < 2 + > as a coupling agent. The excellent mechanical property and thermal stability of PBO are reserved, the conductivity, the electromagnetic shielding performance and the infrared stealth performance are improved at the same time, and the composite material has the potential of large-scale application in multiple fields.

Description

Technical Field

[0001] This invention belongs to the field of high-performance fibers, and specifically relates to a modified PBO fiber, its preparation method, and its application. Background Technology

[0002] Poly(p-phenylenebenzodioxazole) (PBO) fiber is a revolutionary high-performance fiber, hailed as the "super fiber of the 21st century" due to its superior specific strength, specific modulus, impact resistance, heat resistance, and flame retardancy. This superiority stems from its highly conjugated, rigid rod-shaped macromolecules. The benzene and oxazole rings are almost coplanar with the chain axis, allowing for very close packing of the molecular chains, resulting in higher rigidity. PBO fibers are now widely used in high-temperature heat-resistant filter materials, aerospace materials, and high-strength protective ropes. However, the high orientation degree and extremely low number of surface-active groups in PBO fibers make their surface smooth and chemically inert, leading to poor interfacial bonding with the matrix resin. This affects the overall performance of the composite material and reduces its functionality, significantly limiting the full potential of PBO fibers and their application in functional materials. Therefore, surface modification treatment of PBO fibers is particularly important. Chinese patent CN103590234B discloses a method for preparing PBO fibers modified with zinc oxide nanowires. This patent involves activating PBO fibers with sulfuric acid and then growing dense zinc oxide nanowires on the surface for modification. The modified PBO fibers enhance the interfacial shear strength of epoxy resin by 20%-41% compared to the untreated fibers, and maintain tensile strength by 10%-21%. Surface coating modification offers advantages such as a faster and more effective process, no damage to fiber properties, and suitability for large-scale production. Different modifying materials and processes can be selected according to different needs to directionally modify existing PBO fibers. However, research on improving the overall performance and functionality of PBO fibers is still lacking. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a modified PBO fiber, its preparation method and application, so as to realize that the PBO fiber has both high strength and multifunctionality.

[0004] This invention provides a modified PBO fiber, utilizing polybenzimidazole (PBI) and Cu 2+ The PBO fiber was prepared by coating a single layer of MXene onto the surface of the fiber using a supramolecular cross-linked network as a coupling agent.

[0005] Furthermore, the structure of the PBI is shown in equation (I): , Where R1 and R2 are different or the same aliphatic or aromatic functional groups, and n is a positive integer greater than 2.

[0006] Furthermore, the polybenzimidazole PBI has a similar structure to PBO fibers and exhibits good interfacial compatibility with PBO fibers, while the imidazole groups are compatible with Cu. 2+ It can form strong metal coordination bonds, allowing polybenzimidazole to react with Cu. 2+ A supramolecular crosslinked network as shown in formula (II) is formed, and monolayer MXene is firmly coated onto the surface of PBO fibers. .

[0007] Preferably, the Cu 2+ It is derived from any one of copper sulfate, copper chloride, copper nitrate, and copper acetate.

[0008] This invention also provides a method for preparing modified PBO fibers, comprising the following steps: (1) Lithium fluoride (LiF) was dissolved in hydrochloric acid solution to prepare an etching solution, and titanium aluminum carbide (Ti3C2T) was added. x The etching process was performed; then, the MXene monolayer was obtained by centrifugation and washing, and a DMSO solution of the MXene monolayer was obtained by solvent exchange with DMSO. (2) Add polybenzimidazole PBI and Cu to the monolayer MXene DMSO solution described in step (1). 2+ Stirring yields MXene / PBI / Cu 2+ Solution; (3) Soak the PBO fiber in the MXene / PBI / Cu described in step (2). 2+ The solution is then dried to allow the monolayer MXene to adhere uniformly to the surface of the PBO fiber, thus obtaining the modified PBO fiber.

[0009] Preferably, the amount of LiF used in step (1) is 1~5 g, and the LiF and Ti3C2T x The mass ratio is 1:1, and the amount of hydrochloric acid solution used is 20~100 ml.

[0010] Preferably, the etching temperature in step (1) is 35~45 ℃ and the etching time is 24~48 h.

[0011] Preferably, the centrifugation speed in step (1) is 5000~10000 rpm / min and the time is 5~30 min.

[0012] Preferably, the mass fraction of MXene in the DMSO solution of monolayer MXene in step (1) is 0.5~2 wt%.

[0013] Preferably, the PBI in step (2) includes, but is not limited to, polyether-type benzimidazole OPBI, the structure of which is shown in formula (III): , Where n is a positive integer greater than 2.

[0014] Preferably, the mass ratio of PBI to monolayer MXene in step (2) is 1:5~20.

[0015] Preferably, the imidazole group and Cu in the PBI of step (2) 2+ The molar ratio is 2~10:1.

[0016] Preferably, the stirring time in step (2) is 30~60 min.

[0017] Preferably, in step (3), the number of soaking times is 1 to 8, the soaking time is 2 to 4 minutes, the drying temperature is 75 to 85 ℃, and the drying time is 1 to 3 hours.

[0018] The present invention also provides an application of the above-mentioned modified PBO fiber in the fields of conductive fibers, electromagnetic shielding, and infrared stealth.

[0019] Beneficial effects

[0020] (1) The preparation method of the present invention has the advantages of low cost and simple operation, and does not damage the surface of PBO fiber, and will not reduce the excellent mechanical properties of PBO fiber itself; using polybenzimidazole crosslinking network as coupling agent will not reduce the thermal stability of PBO fiber itself.

[0021] (2) The present invention retains the excellent mechanical properties and thermal stability of PBO itself, while improving the conductivity, electromagnetic shielding performance and infrared stealth performance, and has the potential for large-scale application in multiple fields. Attached Figure Description

[0022] Figure 1 The image shows the morphology of the modified PBO fiber PBO-MOC2 obtained in Example 2.

[0023] Figure 2 The image shows the morphology of the modified PBO fiber PBO-MOC2 after micro-debonding obtained in Example 2.

[0024] Figure 3 The image shows the morphology of the modified PBO fiber PBO-M2 obtained in Comparative Example 1.

[0025] Figure 4 The conductivity of the series of modified PBO fibers (PBO-MOC) obtained by different soaking-drying cycles in Example 2 is given.

[0026] Figure 5The conductivity of the series of modified PBO fibers (PBO-M) obtained by different soaking-drying cycles in Comparative Example 1 is shown.

[0027] Figure 6 The electromagnetic shielding performance of a series of modified PBO fibers (PBO-MOC) obtained by different soaking-drying cycles in Example 2 is shown in the figure.

[0028] Figure 7 The electromagnetic shielding performance of a series of modified PBO fibers (PBO-M) obtained by different soaking-drying cycles in Comparative Example 1 is shown in the figure.

[0029] Figure 8 The image shows the infrared stealth effect of a series of modified PBO fibers (PBO-MOC) obtained by different soaking-drying cycles in Example 2.

[0030] Figure 9 Infrared stealth effect of a series of modified PBO fibers (PBO-M) obtained with different soaking-drying cycles in Comparative Example 1. Detailed Implementation

[0031] To enable those skilled in the art to more clearly understand the technical solutions of this application, the technical solutions of the present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0032] Except for the experimental conditions already specified, the other procedures in the examples are generally performed under standard conditions or according to the conditions recommended by the reagent company; unless otherwise specified, the reagents, consumables, etc. used in the following examples are all commercially available.

[0033] Example 1

[0034] The method for preparing modified PBO fibers in this embodiment includes the following steps: (1) Place 2 g of LiF powder in a polytetrafluoroethylene reaction liner, add 40 ml of 9M HCl solution to the LiF powder, and stir magnetically at 40 °C for 20 min to obtain the etching solution; weigh 2 g of Ti3C2T xThe above etching solution was added and reacted at 40 °C for 36 h. After the reaction was completed, the mixture was centrifuged at 3500 rpm / min for 5 min and washed repeatedly until the pH of the supernatant was >6. Deionized water was added again, and the mixture was sonicated in an ice bath for 60 min. After centrifugation at 3500 rpm / min for 5 min, a monolayer MXene aqueous solution was obtained. Finally, the water in the MXene aqueous solution was replaced with DMSO solvent to prepare a monolayer MXene DMSO solution. (2) Add 1 wt% of polyether-type benzimidazole (OPBI, molecular weight 40000~50000 g / mol) and 2 wt% of Cu to a monolayer MXene DMSO solution. 2+ (Copper acetate), to prepare MXene / OPBI / Cu 2+ Solution (containing 1 wt% OPBI, 2 wt% Cu) 2+ The resistivity was measured to be 31 Ω / m. Add 2 wt% polyether benzimidazole (OPBI) and 4 wt% Cu to a monolayer MXene DMSO solution. 2+ MXene / OPBI / Cu were prepared. 2+ Solution (containing 2 wt% OPBI, 4 wt% Cu) 2+ The resistivity was tested to be 20.5 Ω / m. Add 3 wt% polyether benzimidazole (OPBI) and 6 wt% Cu to a monolayer MXene DMSO solution. 2+ MXene / OPBI / Cu were prepared. 2+ Solution (containing 3 wt% OPBI, 8 wt% Cu) 2+ The resistivity was measured to be 32 Ω / m. Add 4 wt% polyether-type benzimidazole (OPBI) and 8 wt% Cu to a monolayer MXene DMSO solution. 2+ MXene / OPBI / Cu were prepared. 2+ Solution (containing 4 wt% OPBI, 8 wt% Cu) 2+ The resistivity was measured to be 55 Ω / m.

[0035] Example 2

[0036] The preparation of the modified PBO fiber in this embodiment includes the following steps: The MXene / OPBI / Cu prepared in step (2) of Example 1 using surface-cleaned PBO fibers 2+ Solution (containing 2 wt% OPBI, 4 wt% Cu) 2+Soak in the solvent for 3 minutes, then dry in an oven at 80 ℃ for 3 hours to fully dry the solvent; Repeat the soaking-drying operation 1-8 times according to the above steps to obtain modified PBO fiber (PBO-MOC).

[0037] The modified PBO fiber (PBO-MOC2) was obtained by soaking and drying twice, and its morphology is as follows: Figure 1 As shown, this indicates that MXene / OPBI / Cu 2+ The coating was evenly applied to the surface of the PBO fibers; Figure 2 The image shows the morphology after micro-debonding, indicating a strong interfacial force between the surface-modified PBO fibers and the epoxy resin matrix. The PBO-MOC2 exhibits a conductivity of 5.85 S / cm in the 8.2 GHz–12.4 GHz EMISE range. T 6.41 dB, SE A 10.1 dB, SE R It has an infrared reflectance of 16.5 dB and an infrared reflection temperature of 50 °C under ambient conditions of 100 °C, achieving an infrared stealth efficiency of 50%.

[0038] The soaking-drying process was repeated four times to obtain modified PBO fibers (PBO-MOC4). The tested conductivity was 21.14 S / cm, and the EMISE performance was satisfactory in the 8.2 GHz–12.4 GHz range. T 10.6 dB, SE A 12.4 dB, SE R It has an infrared reflectance of 23.1 dB. Under ambient conditions of 100°C, the infrared reflection temperature is 49°C, and the infrared stealth efficiency reaches 51%.

[0039] The soaking-drying process was repeated 6 times to obtain modified PBO fiber (PBO-MOC6), which had a tested conductivity of 42.25 S / cm and passed the EMISE test at 8.2 GHz-12.4 GHz. T 12.5 dB, SE A 17.6 dB, SE R It has an infrared reflectance of 30.1 dB. Under ambient conditions of 100°C, the infrared reflection temperature is 48°C, and the infrared stealth efficiency reaches 52%.

[0040] The soaking-drying process was repeated 8 times to obtain modified PBO fibers (PBO-MOC8), whose morphology is as follows. Figure 1 As shown. The tested conductivity is 69.74 S / cm, in the EMISE range of 8.2 GHz–12.4 GHz. T 10.7 dB, SE A 19.6 dB, SER It has an infrared reflectance of 30.3 dB. Under ambient conditions of 100°C, the infrared reflectance temperature is 37°C, and the infrared stealth efficiency reaches 63%.

[0041] The electrical conductivity of modified PBO fibers (PBO-MOC) prepared by repeated soaking-drying operations 1-8 times is as follows: Figure 4 As shown, with the increase of soaking-drying cycles, the conductivity of PBO-MOC increases accordingly due to the increase in the content of attached MXene, while unmodified PBO fibers are non-conductive.

[0042] The electromagnetic shielding performance of modified fibers PBO-MOC2, PBO-MOC4, PBO-MOC6 and PBO-MOC8 is shown in the figure below. Figure 6 As shown, this comparison indicates that the electromagnetic shielding effect of the fiber gradually improves with the increase of soaking-drying cycles, while unmodified PBO fiber does not have electromagnetic shielding properties.

[0043] Infrared stealth effect Figure 8 As shown, this comparison indicates that the infrared stealth effect of the fiber gradually improves with the increase of soaking-drying cycles, while the unmodified PBO fiber does not have infrared stealth properties.

[0044] In addition, the mechanical properties of unmodified PBO fibers and PBO-MOC modified fibers were tested respectively. The tensile strengths of PBO, PBO-MOC2, PBO-MOC4, PBO-MOC6 and PBO-MOC8 were 34.69, 35.12, 35.64, 36.13 and 36.78 cN / dtex, respectively, indicating that the surface modification method of the present invention does not damage the mechanical properties of the fibers.

[0045] Comparative Example 1

[0046] The preparation method of the modified PBO fiber in this comparative example includes the following steps: (1) Place 2 g of LiF powder in a polytetrafluoroethylene reaction liner, add 40 ml of 9M HCl solution to the LiF powder, and stir magnetically at 40 °C for 20 min to obtain the etching solution; weigh 2 g of Ti3C2T x The above etching solution was added and reacted at 40 °C for 36 h. After the reaction was completed, the mixture was centrifuged at 3500 rpm / min for 5 min and washed repeatedly until the pH of the supernatant was >6. Deionized water was added again, and the mixture was sonicated in an ice bath for 60 min. After centrifugation at 3500 rpm / min for 5 min, a monolayer MXene aqueous solution was obtained. Finally, the water in the MXene aqueous solution was replaced with DMSO solvent to prepare a monolayer MXene DMSO solution. (2) 2 wt% of polyether-type benzimidazole (OPBI) was added to a monolayer MXene DMSO solution to prepare an MXene / OPBI solution, and the resistivity was tested to be 28.3 Ω / m; (3) Soak the clean PBO fiber in the MXene / OPBI solution prepared in step (2) for 3 min, and dry it in an oven at 80°C for 3 h to fully dry the solvent.

[0047] Repeat the soaking-drying operation 1-8 times according to the above steps to obtain modified PBO fiber (PBO-M).

[0048] The modified PBO fiber (PBO-M2) was obtained by two soaking-drying operations, and its morphology is as follows: Figure 3 As shown, this indicates that no Cu was added. 2+ The modifier could not be uniformly coated on the fiber surface. The tested conductivity was 5.50 S / cm, and the EMISE was within the range of 8.2 GHz to 12.4 GHz. T 4.86 dB, SE A 10.3 dB, SE R It has an infrared reflectance of 15.1 dB and an infrared reflection temperature of 71°C under ambient temperature of 100°C, achieving an infrared stealth efficiency of 29%.

[0049] Modified PBO fibers (PBO-M4) were obtained by soaking and drying four times. The tested electrical conductivity was 11.69 S / cm, and the EMISE was within the range of 8.2 GHz to 12.4 GHz. T 5.63 dB, SE A 10.8 dB, SE R It has an infrared reflectance of 16.4 dB and an infrared reflection temperature of 65°C under ambient temperature of 100°C, achieving an infrared stealth efficiency of 35%.

[0050] Modified PBO fibers (PBO-M6) were obtained by soaking and drying six times. The tested conductivity was 23.17 S / cm, and the EMISE was within the range of 8.2 GHz to 12.4 GHz. T 7.72 dB, SE A 13.1 dB, SE R It has an infrared reflectance of 20.8 dB and an infrared reflection temperature of 56 °C under ambient temperature of 100 °C, achieving an infrared stealth efficiency of 44%.

[0051] Modified PBO fibers (PBO-M8) were obtained by repeating the soaking-drying process eight times. The tested conductivity was 29.09 S / cm, and the EMISE was within the range of 8.2 GHz to 12.4 GHz. T 7.62 dB, SE A13.5 dB, SE R It has an infrared reflectance of 21.1 dB, an infrared reflection temperature of 40°C under ambient temperature of 100°C, and an infrared stealth efficiency of 60%.

[0052] The electrical conductivity of modified PBO fibers (PBO-M) prepared by repeated soaking-drying operations 1-8 times is as follows: Figure 5 As shown, the electrical conductivity of the modified fiber increased with increasing soaking-drying cycles, but remained lower than that of the corresponding PBO-MOC fiber, indicating that Cu... 2+ Complexation facilitates the uniform adhesion of MXene to the surface of PBO fibers.

[0053] Electromagnetic shielding performance diagrams of modified fibers PBO-M2, PBO-M4, PBO-M6, and PBO-M8 are shown below. Figure 7 As shown, the electromagnetic shielding effect of modified fiber PBO-M increases with the number of coatings, but is lower than that of modified fiber PBO-MOC with the same number of coatings.

[0054] Infrared stealth effect Figure 9 As shown, the infrared stealth effect of the fiber also increases with the increase of the number of coatings, but it is still lower than that of PBO-MOC modified fiber with the same number of coatings.

[0055] In addition, the mechanical properties of unmodified PBO fibers and PBO-M modified fibers were tested separately. The tensile strengths of PBO, PBO-M2, PBO-M4, PBO-M6 and PBO-M8 were 34.69, 34.94, 35.43, 35.79 and 36.31 cN / dtex, respectively, indicating that coating with OPBI / MXene does not damage the mechanical properties of the fibers.

[0056] In summary, under the same conditions, Cu 2+ The addition of MXene increases the coating amount and uniformity of PBO fibers, which is beneficial to the improvement of electrical conductivity, thereby improving the electromagnetic shielding effect of modified fibers; the increase of MXene content on the surface of modified fibers is also beneficial to improving the infrared stealth effect of modified fibers.

Claims

1. A modified PBO fiber, characterized in that, The modified PBO fiber utilizes polybenzimidazole (PBI) and Cu 2+ The PBO fiber was prepared by coating a single layer of MXene onto the surface of the fiber using a supramolecular cross-linked network as a coupling agent.

2. The modified PBO fiber according to claim 1, characterized in that, The structure of the PBI is shown in equation (I): ， Where R1 and R2 are different or the same aliphatic or aromatic functional groups, and n is a positive integer greater than 2.

3. The modified PBO fiber according to claim 1, characterized in that, The polybenzimidazole PBI and Cu 2+ The structure of the supramolecular cross-linked network is shown in formula (II): 。 4. The modified PBO fiber according to claim 1, characterized in that, The Cu 2+ It is derived from any one of copper sulfate, copper chloride, copper nitrate or copper acetate.

5. A method for preparing modified PBO fiber, comprising the following steps: (1) Lithium fluoride (LiF) was dissolved in hydrochloric acid solution to prepare an etching solution, and titanium aluminum carbide (Ti3C2T) was added. x Etching was performed; then, the monolayer MXene aqueous solution was obtained by centrifugation and washing, and a DMSO solution of monolayer MXene was obtained by solvent exchange with DMSO. (2) Add polybenzimidazole PBI and Cu to the monolayer MXene DMSO solution described in step (1). 2+ Stirring yields MXene / PBI / Cu 2+ Solution; (3) Soak the PBO fiber in the MXene / PBI / Cu described in step (2). 2+ The solution is then dried to allow the monolayer MXene to adhere uniformly to the surface of the PBO fiber, thus obtaining the modified PBO fiber.

6. The preparation method according to claim 5, characterized in that, The amount of LiF used in step (1) is 1~5 g, and the LiF and Ti3C2T x The mass ratio is 1:1, and the amount of hydrochloric acid solution used is 20~100 ml.

7. The preparation method according to claim 5, characterized in that, The etching temperature in step (1) is 35~45 ℃ and the etching time is 24~48 h; the centrifugation speed is 5000~10000 rpm / min and the time is 5~30 min; the mass fraction of monolayer MXene in the DMSO solution of monolayer MXene is 0.5~2 wt%.

8. The preparation method according to claim 5, characterized in that, In step (2), the mass ratio of PBI to monolayer MXene is 1:5~20. The imidazole groups and Cu in PBI 2+ The molar ratio is 2~10:1; the stirring time is 30~60 min.

9. The preparation method according to claim 5, characterized in that, The number of soakings in step (3) is 1 to 8, the soaking time for each soak is 2 to 4 minutes, the drying temperature is 75 to 85 ℃, and the drying time for each drying is 1 to 3 hours.

10. An application of the modified PBO fiber as described in claim 1 in the fields of conductive fibers, electromagnetic shielding, and infrared stealth.

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