CN114108317A - Preparation method of surface grafting modified PBO fiber - Google Patents

Preparation method of surface grafting modified PBO fiber Download PDF

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CN114108317A
CN114108317A CN202111608937.3A CN202111608937A CN114108317A CN 114108317 A CN114108317 A CN 114108317A CN 202111608937 A CN202111608937 A CN 202111608937A CN 114108317 A CN114108317 A CN 114108317A
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fiber
pbo fiber
pbo
vacuum
fibers
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CN114108317B (en
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刘群
郭程
孟昭瑞
刘薇
张殿波
朱晓琳
刘宗法
代勇
陈湘栋
钟蔚华
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Shandong Non Metallic Material Research Institute
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/10—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing oxygen
    • D06M13/184—Carboxylic acids; Anhydrides, halides or salts thereof
    • D06M13/207—Substituted carboxylic acids, e.g. by hydroxy or keto groups; Anhydrides, halides or salts thereof
    • D06M13/21—Halogenated carboxylic acids; Anhydrides, halides or salts thereof
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    • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/32—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond
    • D06M11/36—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with oxygen, ozone, ozonides, oxides, hydroxides or percompounds; Salts derived from anions with an amphoteric element-oxygen bond with oxides, hydroxides or mixed oxides; with salts derived from anions with an amphoteric element-oxygen bond
    • D06M11/38—Oxides or hydroxides of elements of Groups 1 or 11 of the Periodic Table
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    • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/51—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with sulfur, selenium, tellurium, polonium or compounds thereof
    • D06M11/55—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with sulfur, selenium, tellurium, polonium or compounds thereof with sulfur trioxide; with sulfuric acid or thiosulfuric acid or their salts
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/322—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing nitrogen
    • D06M13/35—Heterocyclic compounds
    • D06M13/355—Heterocyclic compounds having six-membered heterocyclic rings
    • D06M13/358—Triazines
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    • D06M2101/30—Synthetic polymers consisting of macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
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Abstract

The invention belongs to the field of high-performance fiber modification, and particularly relates to a preparation method of surface graft modified PBO fiber. And cleaning the PBO fiber, and drying in vacuum to obtain the clean PBO fiber. Obtaining fibers with amino groups on the surface by pretreating clean PBO fibers; adding 4, 4-hexafluoroisopropylidene-phthalic anhydride (6 FDA) into an organic solvent for dissolving, then adding PBO fibers with amino groups on the surface into the mixed solution, washing by deionized water after grafting reaction is finished, and heating by vacuum gradient temperature rise to obtain the modified PBO fibers with the surfaces grafted with polar groups and imide ring structures. The surface of the modified PBO fiber prepared by the invention contains a large amount of polar groups and groups with strong ultraviolet radiation resistance, the surface roughness is increased, the interface bonding property of the fiber and a resin matrix is obviously improved, and the ultraviolet aging resistance of the fiber is improved to a certain extent.

Description

Preparation method of surface grafting modified PBO fiber
Technical Field
The invention belongs to the field of high-performance fiber modification, and particularly relates to a preparation method of surface graft modified PBO fiber.
Background
The PBO fiber has excellent performances of high strength, high modulus, high heat resistance and high flame retardance, and is known as super fiber in the 21 st century. The PBO fiber reinforced composite material can be widely used in civil fields such as building reinforced materials, sports goods and the like, and military and aerospace fields such as bulletproof impact-resistant materials, weaponry and the like, and promotes the development of light weight, miniaturization and high performance of the equipment. Therefore, PBO fiber reinforced composites have become a hot spot of recent research in the field of materials.
It is well known that the level of mechanical properties of fiber reinforced composites is closely related to the nature of the interface, and that damage to the interface is a critical factor in the failure of the composite. The good interface bonding force can transfer the load borne by the matrix to the fibers, reduce the internal stress concentration and effectively improve the performance of the composite material. For PBO fiber, the surface of the fiber has no polar group, most of the PBO fiber is wrapped inside, the surface is inert and smooth, the PBO fiber cannot be well bonded with resin, the interface strength is low, and the wide application of the PBO fiber in advanced composite materials is restricted. Meanwhile, oxazole rings in PBO molecules are easy to open and break under ultraviolet irradiation, and the poor ultraviolet aging resistance of PBO fibers is also a non-negligible important factor influencing the service life of the fibers and the composite materials thereof.
The surface modification method of the PBO fiber comprises surface etching, grafting reaction, coupling agent treatment, plasma modification, radiation method, coating method and the like. The surface grafting technology modified PBO fiber is one of the most studied technologies in the chemical modification method, is a low-damage treatment technology and has designability. One technique for modifying the properties of the body by creating chemical bonds between the reactive functional group-containing agent and the fiber surface is to leave the material unreacted and intact, so that the properties of the body are not modified or lost.
Currently, many researchers only improve the interfacial activity of the PBO fiber and the polymer matrix by a series of modification methods, and have less research on improving the comprehensive properties of the fiber. Therefore, the surface cohesiveness and the ultraviolet aging resistance of the PBO fiber can be simultaneously improved by adopting a proper modification method, and the method has important significance and application value.
Disclosure of Invention
Aiming at the defects of the prior art, the application provides a preparation method of surface grafting modified PBO fiber. And cleaning the PBO fiber, and drying in vacuum to obtain the clean PBO fiber. Obtaining fibers with amino groups on the surface by pretreating clean PBO fibers; adding 4, 4-hexafluoroisopropylidene-phthalic anhydride (6 FDA) into an organic solvent for dissolving, then adding PBO fibers with amino groups on the surface into the mixed solution, washing by deionized water after grafting reaction is finished, and heating by vacuum gradient temperature rise to obtain the modified PBO fibers with the surfaces grafted with polar groups and imide ring structures. The surface of the modified PBO fiber prepared by the invention contains a large amount of polar groups and groups with strong ultraviolet radiation resistance, the surface roughness is increased, the interface bonding property of the fiber and a resin matrix is obviously improved, and the ultraviolet aging resistance of the fiber is improved to a certain extent.
The specific technical scheme of the invention is as follows:
a surface graft modified PBO fiber and a preparation method thereof comprise the following steps:
(1) carrying out surface carboxylation treatment on the PBO fiber: adding a proper amount of clean PBO fiber into strong protonic acid, stirring and reacting for 2-10 h at 70-100 ℃, then placing the fiber into a proper amount of NaOH solution, adding chloroacetic acid, carrying out ultrasonic treatment, preferably treating for 4h, washing with deionized water for several times, preferably 6 times, and carrying out vacuum drying to obtain the PBO fiber with carboxyl on the surface.
The strong protonic acid in the step (1) is one of sulfuric acid, methane sulfonic acid, nitric acid and polyphosphoric acid or any combination thereof.
Wherein the adding amount of the PBO fiber is 0.2-2% of the mass of the strong protonic acid, the mass fraction of the strong protonic acid is 30-65%, and 60wt% of the strong protonic acid is preferably used.
The mass fraction of the sodium hydroxide solution in the step (1) is 2-15%; the addition amount of chloroacetic acid is 1-10% of the mass of the NaOH solution.
The protonation effect is generated by the action of the protonic acid and the fiber, and the concentration of the protonic acid is obviously increased; the role of chloroacetic acid is to convert hydroxyl group into carboxyl group by conjugation of acetic acid moiety, and too small amount of chloroacetic acid results in less carboxyl group formation and the effect of excessive chloroacetic acid is not significant.
As a preferred technical scheme, before the PBO fiber is subjected to surface carboxylation treatment, an organic solvent is adopted to clean the PBO fiber, and impurities and oil on the surface of the fiber are cleaned. The specific cleaning method comprises the following steps: proper amount of PBO fiber is put into organic solvent, heated and refluxed for a period of time, preferably 5h, then washed several times (preferably 6 times) by deionized water, and then the washed fiber is dried in vacuum to obtain clean PBO fiber. The organic solvent is preferably one of ethanol, acetone, petroleum ether and ethyl acetate or any combination thereof.
(2) Placing PBO fibers with carboxyl on the surfaces in N, N-Dimethylformamide (DMF), adding N, N-Dicyclohexylcarbodiimide (DCC) and melamine into a reaction system, and reacting for 6-48 h at 70-140 ℃; then the fiber is washed by deionized water and dried in vacuum, and the PBO fiber with amino on the surface is obtained.
In the step (2), the mass of DCC is 0.5-3 times of that of PBO fiber with carboxyl on the surface, and the mass of melamine is 0.2-2.5 times of that of PBO fiber with carboxyl on the surface.
(3) Under the protection of nitrogen gas, 4-hexafluoroisopropylidene-phthalic anhydride (6 FDA) is added into an aprotic polar solvent to be dissolved, PBO fibers with amino groups on the surfaces are added, then the mixture reacts for 12-36 h at 0-15 ℃, the 6FDA fully reacts with the surfaces of the PBO fibers, the PBO fibers after grafting are washed by deionized water for 6-10 times after the reaction is finished, and the PBO fibers after grafting are heated in vacuum by adopting step heating.
Wherein the mass of 6FDA is 0.5-3 times of that of PBO fiber with amino on the surface.
The aprotic polar solvent in the step (3) is N, N-Dimethylformamide (DMF), Dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), or the like.
The temperature of vacuum drying in the steps (1) and (2) is preferably 100 ℃, and the time is preferably 8 h; preferably, the step heating vacuum heating temperature in the step (3) is three-step heating, and the specific temperature sections are respectively as follows: 90-120 ℃, 180-210 ℃ and 270-320 ℃; the vacuum heating time per stage is preferably 1 h.
The amic acid structure formed by the 6FDA and the surface of the PBO fiber under low temperature conditions is very unstable at room temperature and is easily degraded, so that the amic acid is imidized by a stepwise temperature rise to form a more stable structure. Is favorable for improving the ultraviolet aging resistance of the fiber.
In addition, the other technical schemes of the invention all adopt the conventional prior art, and the inventor does not need to describe any more.
Compared with the prior art, the invention has the beneficial effects that:
(1) the 4, 4-hexafluoroisopropylidene-phthalic anhydride (6 FDA) structure is directly bonded on the surface of the PBO fiber in a chemical bond mode, the bonding effect is good, and the reduction of the using effect and the service life of a coating prepared by a physical method due to insufficient bonding force with the fiber and long-term use is avoided.
(2) The PBO fiber surface grafted 6FDA structure contains a large amount of living matterA linear group containing-CF2And a large amount of oxygen, so the reaction activity is high, the polarity of the fiber surface is increased, the roughness is increased, stable chemical bonding can be formed with various resins, and the interface bonding force of the fiber reinforced resin matrix composite material is improved.
(3) The modification method provided by the invention is simple to operate and high in flexibility, and can greatly improve the interface bonding force between the fiber and the resin on the premise of small strength loss of the fiber body.
(4) Melamine is a typical representative of polyamines, which function as molecular bridges to bind PBO fibers and to other modifying groups. The method has the advantages that the fiber grafting rate is high, 6FDA and PBO fiber carrying amino groups generate an imide ring structure, the strong electricity absorption effect of nitrogen-oxygen double bonds on the imide ring ensures the charge distribution density in the space, the structural bond energy is large, and the ultraviolet aging resistance of the modified PBO fiber can be effectively improved.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples, but it should not be construed that the scope of the above subject matter is limited to the following examples. All the technologies realized based on the above contents of the present invention belong to the scope of the present invention, and the following embodiments are all completed by adopting the conventional prior art except for the specific description.
Example 1:
a surface graft modified PBO fiber and a preparation method thereof comprise the following steps:
(1) and (3) placing 6g of PBO fiber in 300mL of acetone, heating and refluxing for 5h, then washing with deionized water for 6 times, and then drying the washed fiber at 100 ℃ for 8h in vacuum to obtain the clean PBO fiber.
(2) Pretreatment of PBO fiber:
putting 2.4g of clean PBO fiber into a three-neck flask filled with 320mL of sulfuric acid (the mass fraction is 40%), stirring and reacting for 8h at 70 ℃, putting the fiber into 280mL of NaOH solution with the mass fraction of 3%, adding 12.6g of chloroacetic acid, carrying out ultrasonic treatment for 4h, washing with deionized water for 6 times, and drying at 100 ℃ for 8h under vacuum to obtain the PBO fiber with carboxyl on the surface.
(3) 0.24g of PBO fiber having carboxyl groups on the surface thereof was added to a three-necked flask containing 320mL of N, N-Dimethylformamide (DMF), and then 0.29g N, N-Dicyclohexylcarbodiimide (DCC) and 0.34g of melamine were added to the reaction system. Reacting for 36 hours at 90 ℃, then washing the fiber for 6 times by deionized water, and drying for 8 hours in vacuum at 100 ℃ to obtain the PBO fiber with amino on the surface.
(4) Preparation of graft-modified PBO fiber:
0.15g of 6FDA was dissolved in a three-necked flask containing 320ml of N-methylpyrrolidone (NMP) under a nitrogen atmosphere, and 0.12g of PBO fiber having amino groups on the surface thereof was added to the mixed solution and reacted at 8 ℃ for 34 hours. After the reaction is finished, the grafted PBO fiber is washed by deionized water for 6 times, and then is heated for 1h in vacuum at 90 ℃, 1h in vacuum at 190 ℃ and 1h in vacuum at 280 ℃.
The PBO fibers before and after the surface graft modification obtained in this example were subjected to tensile strength testing of monofilaments according to ASTM-D3379 standard, wherein the gauge length was 20mm, the speed was 10mm/min, and 30 fiber samples per group were measured and averaged.
The preparation method comprises the steps of preparing epoxy resin E51 and curing agent H256 with the mass ratio of 3.31:1, uniformly mixing, uniformly dripping the mixture on the surface of a single fiber, curing for 2H at 70 ℃, curing for 2H at 100 ℃ and curing for 3H at 150 ℃ in an oven, testing the force value (IFSS) of a pellet to break away from a single fiber to evaluate the interfacial bonding property of the surface of the fiber, and taking the average value of 30 resin pellets under each condition.
The IFSS value of the initial PBO fiber is 22.63MPa, the IFSS value of the PBO fiber after grafting modification is 35.35 MPa, and the interface shear strength is improved by 56.2 percent.
The initial PBO fiber and the modified fiber are respectively processed by 800w/m2After the ultraviolet light is irradiated for 100 hours, the strength retention rate of the initial PBO fiber is 49.1%, and the strength retention rate of the modified PBO fiber is 63.4%.
Example 2:
a surface graft modified PBO fiber and a preparation method thereof comprise the following steps:
(1) and (3) placing 6g of PBO fiber in 300mL of ethanol, heating and refluxing for 5h, then washing with deionized water for 6 times, and then drying the washed fiber at 100 ℃ for 8h in vacuum to obtain the clean PBO fiber.
(2) Pretreatment of PBO fiber:
putting 2.4g of clean PBO fiber into a three-neck flask filled with 255mL of methane sulfonic acid (the mass fraction is 60%), stirring and reacting at 93 ℃ for 7.5h, putting the fiber into 250mL of NaOH solution with the mass fraction of 9.6%, adding 20.5g of chloroacetic acid, carrying out ultrasonic treatment for 4h, washing with deionized water for 6 times, and drying at 100 ℃ in vacuum for 8h to obtain the PBO fiber with carboxyl on the surface.
(3) 0.35g of PBO fiber having carboxyl groups on the surface thereof was added to a three-necked flask containing 255mL of N, N-Dimethylformamide (DMF), and then 0.84g of N, N-Dicyclohexylcarbodiimide (DCC) and 0.74g of melamine were added to the reaction system. Reacting for 35 hours at 115 ℃, then washing the fiber for 6 times by deionized water, and drying for 8 hours in vacuum at 100 ℃ to obtain the PBO fiber with amino on the surface.
(4) Preparation of graft-modified PBO fiber:
0.65g of 6FDA was dissolved in a three-necked flask containing 255mL of Dimethylacetamide (DMAC) under nitrogen protection, and 0.31g of PBO fiber having amino groups on the surface was added to the mixed solution and reacted at 4 ℃ for 26 hours. After the reaction is finished, the grafted PBO fiber is washed by deionized water for 7 times, and then is heated for 1h in vacuum at 110 ℃, 1h in vacuum at 200 ℃ and 1h in vacuum at 300 ℃.
The PBO fibers before and after the surface graft modification obtained in this example were subjected to tensile strength testing of monofilaments according to ASTM-D3379 standard, wherein the gauge length was 20mm, the speed was 10mm/min, and 30 fiber samples per group were measured and averaged. The preparation method comprises the steps of preparing epoxy resin E51 and curing agent H256 with the mass ratio of 3.31:1, uniformly mixing, uniformly dripping the mixture on the surface of a single fiber, curing for 2H at 70 ℃, curing for 2H at 100 ℃ and curing for 3H at 150 ℃ in an oven, testing the force value (IFSS) of a pellet to break away from a single fiber to evaluate the interfacial bonding property of the surface of the fiber, and taking the average value of 30 resin pellets under each condition.
The IFSS value of the initial PBO fiber is 22.63MPa, the IFSS value of the PBO fiber after grafting modification is 37.48MPa, and the interface shear strength is improved by 65.6 percent.
The initial PBO fiber and the modified fiber are respectively processed by 800w/m2After the ultraviolet light irradiation for 100h, the initial PBO fiber strength retention rate is 49.1%, and the PBO fiber strength retention rate is 72.7%.
Example 3:
a surface graft modified PBO fiber and a preparation method thereof comprise the following steps:
(1) and (3) placing 5.3g of PBO fiber in 300mL of petroleum ether, heating and refluxing for 5h, then washing with deionized water for 6 times, and then drying the washed fiber at 100 ℃ for 8h in vacuum to obtain the clean PBO fiber.
(2) Pretreatment of PBO fiber:
putting 2.6g of clean PBO fiber into a three-neck flask filled with 280mL of nitric acid (the mass fraction is 50%), stirring and reacting for 7.5h at 82 ℃, putting the fiber into 220mL of NaOH solution with the mass fraction of 7%, adding 14.1g of chloroacetic acid, carrying out ultrasonic treatment for 4h, washing for 6 times by deionized water, and drying for 8h at 100 ℃ in vacuum to obtain the PBO fiber with carboxyl on the surface.
(3) 0.42g of PBO fiber having carboxyl groups on the surface thereof was added to a three-necked flask containing 280mL of N, N-Dimethylformamide (DMF), and then 0.76g N, N-Dicyclohexylcarbodiimide (DCC) and 0.72g of melamine were added to the reaction system. Reacting for 41 hours at 100 ℃, then washing the fiber for 6 times by deionized water, and drying for 8 hours at 100 ℃ in vacuum to obtain the PBO fiber with amino on the surface.
(4) Preparation of graft-modified PBO fiber:
0.43g of 6FDA was dissolved in a three-necked flask containing 280mL of N, N-Dimethylformamide (DMF) under nitrogen protection, and 0.26g of PBO fiber having amino groups on the surface thereof was added to the mixed solution and reacted at 8 ℃ for 34 hours. After the reaction is finished, the grafted PBO fiber is washed by deionized water for 7 times, and then is heated for 1h in vacuum at 100 ℃, 1h in vacuum at 195 ℃ and 1h in vacuum at 290 ℃.
The PBO fibers before and after the surface graft modification obtained in this example were subjected to tensile strength testing of monofilaments according to ASTM-D3379 standard, wherein the gauge length was 20mm, the speed was 10mm/min, and 30 fiber samples per group were measured and averaged. The preparation method comprises the steps of preparing epoxy resin E51 and curing agent H256 with the mass ratio of 3.31:1, uniformly mixing, uniformly dripping the mixture on the surface of a single fiber, curing for 2H at 70 ℃, curing for 2H at 100 ℃ and curing for 3H at 150 ℃ in an oven, testing the force value (IFSS) of a pellet to break away from a single fiber to evaluate the interfacial bonding property of the surface of the fiber, and taking the average value of 30 resin pellets under each condition.
The IFSS value of the initial PBO fiber is 22.63MPa, the IFSS value of the PBO fiber after grafting modification is 36.28 MPa, and the interface shear strength is improved by 60.3 percent.
The initial PBO fiber and the modified fiber are respectively processed by 800w/m2After the ultraviolet light irradiation for 100h, the initial PBO fiber strength retention rate is 49.1%, and the PBO fiber strength retention rate is 68.3%.
Example 4:
a surface graft modified PBO fiber and a preparation method thereof comprise the following steps:
(1) putting 4.5g of PBO fiber into 300mL of mixed solution of acetone and petroleum ether with the volume ratio of 1:1, heating and refluxing for 5h, then washing for 6 times by using deionized water, and then drying the washed fiber at 100 ℃ for 8h in vacuum to obtain the clean PBO fiber.
(2) Pretreatment of PBO fiber:
putting 2.1g of clean PBO fiber into a three-neck flask filled with 230mL of mixed solution (the mass fraction is 60%) of sulfuric acid and methane sulfonic acid in a volume ratio of 1:1, stirring and reacting at 100 ℃ for 7h, putting the fiber into 240mL of NaOH solution with the mass fraction of 12.3%, adding 22.8g of chloroacetic acid, carrying out ultrasonic treatment for 4h, washing with deionized water for 6 times, and drying at 100 ℃ in vacuum for 8h to obtain the PBO fiber with carboxyl on the surface.
(3) 0.55g of PBO fiber having carboxyl groups on the surface thereof was added to a three-necked flask containing 230mL of N, N-Dimethylformamide (DMF), and then 1.54g N, N-Dicyclohexylcarbodiimide (DCC) and 1.32g of melamine were added to the reaction system. Reacting for 42 hours at 120 ℃, then washing the fiber for 6 times by deionized water, and drying for 8 hours in vacuum at 100 ℃ to obtain the PBO fiber with amino on the surface.
(4) Preparation of graft-modified PBO fiber:
under the protection of nitrogen, 1.04g of 6FDA was dissolved in a three-necked flask containing 230mL of N, N Dimethylformamide (DMF), and 0.40g of PBO fiber having amino groups on the surface thereof was added to the mixed solution and reacted at 0 ℃ for 28 hours. After the reaction is finished, the grafted PBO fiber is washed by deionized water for 8 times, and then is heated for 1h in vacuum at 120 ℃, 1h in vacuum at 210 ℃ and 1h in vacuum at 310 ℃.
The PBO fibers before and after the surface graft modification obtained in this example were subjected to tensile strength testing of monofilaments according to ASTM-D3379 standard, wherein the gauge length was 20mm, the speed was 10mm/min, and 30 fiber samples per group were measured and averaged. The preparation method comprises the steps of preparing epoxy resin E51 and curing agent H256 with the mass ratio of 3.31:1, uniformly mixing, uniformly dripping the mixture on the surface of a single fiber, curing for 2H at 70 ℃, curing for 2H at 100 ℃ and curing for 3H at 150 ℃ in an oven, testing the force value (IFSS) of a pellet to break away from a single fiber to evaluate the interfacial bonding property of the surface of the fiber, and taking the average value of 30 resin pellets under each condition.
The IFSS value of the initial PBO fiber is 22.63MPa, the IFSS value of the PBO fiber after grafting modification is 38.06 MPa, and the interface shear strength is improved by 68.2 percent.
The initial PBO fiber and the modified fiber are respectively processed by 800w/m2After the ultraviolet light irradiation for 100h, the initial PBO fiber strength retention rate is 49.1%, and the PBO fiber strength retention rate is 75.4%.

Claims (10)

1. A preparation method of surface grafting modified PBO fiber is characterized by comprising the following steps:
(1) carrying out surface carboxylation treatment on the PBO fiber: adding a proper amount of clean PBO fiber into strong protonic acid, stirring and reacting for 2-10 h at 70-100 ℃, then placing the fiber into NaOH solution, adding chloroacetic acid, carrying out ultrasonic treatment, washing with deionized water, and carrying out vacuum drying to obtain PBO fiber with carboxyl on the surface;
(2) placing PBO fiber with carboxyl on the surface in DMF, adding DCC and melamine into a reaction system, and reacting at 70-140 ℃ for 6-48 h; then washing the fiber with deionized water, and drying in vacuum to obtain PBO fiber with amino on the surface;
(3) under the protection of nitrogen gas, 6FDA is added into an aprotic polar solvent to be dissolved, PBO fibers with amino groups on the surfaces are added and then react for 12-36 h at 0-15 ℃, so that the 6FDA fully reacts with the surfaces of the PBO fibers, the PBO fibers after grafting are washed by deionized water after the reaction is finished, and the PBO fibers after grafting are heated in vacuum by adopting step heating.
2. The method of claim 1, further comprising: before the PBO fiber is subjected to surface carboxylation treatment, an organic solvent is adopted to clean the PBO fiber, and impurities and oil on the surface of the fiber are cleaned.
3. The method for preparing surface graft modified PBO fiber according to claim 2, wherein the specific cleaning method is as follows: and (2) placing the PBO fiber in an organic solvent, heating and refluxing, washing with deionized water, and drying the washed fiber in vacuum to obtain the clean PBO fiber.
4. The method for preparing surface graft modified PBO fiber according to claim 2 or 3, wherein the organic solvent is one of ethanol, acetone, petroleum ether, ethyl acetate or any combination thereof.
5. The method for preparing surface graft modified PBO fiber according to claim 1, wherein the strong protonic acid in step (1) is one of sulfuric acid, methane sulfonic acid, nitric acid, polyphosphoric acid, or any combination thereof.
6. The preparation method of the surface graft modified PBO fiber according to claim 1, wherein the PBO fiber is added in the step (1) in an amount of 0.2-2% by mass of the strong protonic acid, and the mass fraction of the strong protonic acid is 30-65%.
7. The preparation method of the surface graft modified PBO fiber according to claim 1, wherein the mass fraction of the sodium hydroxide solution in the step (1) is 2-15%; the addition amount of chloroacetic acid is 1-10% of the mass of the NaOH solution.
8. The method for preparing surface graft modified PBO fiber according to claim 1, wherein in step (2), the mass of DCC is 0.5 to 3 times that of PBO fiber with carboxyl on the surface, and the mass of melamine is 0.2 to 2.5 times that of PBO fiber with carboxyl on the surface.
9. The method for preparing surface graft modified PBO fiber according to claim 1, wherein the aprotic polar solvent of step (3) is selected from DMF, DMAC, DMSO, NMP; the mass of 6FDA in the step (3) is 0.5-3 times of that of the PBO fiber with amino on the surface.
10. The method for preparing the surface graft modified PBO fiber according to claim 1, wherein the step-heating vacuum heating temperature in step (3) is three-step heating, and the specific temperature sections are respectively as follows: 90-120 ℃, 180-210 ℃ and 270-320 ℃; the vacuum heating time of each stage is 1 h.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111534048A (en) * 2020-04-09 2020-08-14 上海大学 Thermosetting resin-based PBO fiber composite material and preparation method thereof
CN112431038A (en) * 2019-08-26 2021-03-02 东丽纤维研究所（中国）有限公司 Uvioresistant fiber structure
US20210222358A1 (en) * 2018-05-04 2021-07-22 Soochow University Surface-modified aramid fiber and preparation method therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210222358A1 (en) * 2018-05-04 2021-07-22 Soochow University Surface-modified aramid fiber and preparation method therefor
CN112431038A (en) * 2019-08-26 2021-03-02 东丽纤维研究所（中国）有限公司 Uvioresistant fiber structure
CN111534048A (en) * 2020-04-09 2020-08-14 上海大学 Thermosetting resin-based PBO fiber composite material and preparation method thereof

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