Modification method of poly (p-phenylene benzobisoxazole) fiber

Abstract

The invention relates to the technical field of preparation of high-performance fibers, in particular to a modification method of poly (p-phenylene benzobisoxazole) fibers, which comprises the following steps: cutting the poly (p-phenylene benzobisoxazole) fibers, washing, immersing into a mixed solution of ethanol and acetone, washing with ethanol, and drying; adding into a polyvinyl alcohol aqueous solution, adding ferric salt or ferrous salt, uniformly immersing, adding persulfate, heating in a water bath, cooling, and taking out the cross-linked fiber; and putting into deionized water for ultrasonic washing, and drying to obtain the PVA / PBO fiber. The modification method of the poly (p-phenylene benzobisoxazole) fiber, which adopts the steps, is simple and efficient to operate, does not need complex equipment, is suitable for industrial production, and can remarkably improve the surface hydrophilicity on the premise of not damaging the body performance of the PBO fiber.

Description

Technical Field

[0001] The present invention relates to the technical field of high-performance fiber preparation, and particularly to a modification method for poly(p-phenylene benzobisoxazole) fiber. Background Art

[0002] Poly(p-phenylene benzobisoxazole) (PBO) fiber is prepared by polycondensation reaction of 4,6-diaminoresorcinol dihydrochloride and terephthalic acid in a polyphosphoric acid medium with phosphorus pentoxide as a dehydrating agent. The benzene rings and oxazole rings in the PBO fiber molecular chain have a coplanar structure. Affected by the combined effects of steric hindrance and conjugation effects, the molecular chains can be closely packed, endowing the PBO fiber with high strength, high modulus, high heat resistance and excellent flame retardant properties, making it an ideal fiber reinforcement material.

[0003] However, the PBO fiber has a high surface crystallinity and lacks polar functional groups, showing significant chemical inertness, which leads to a weak interfacial bonding force between it and the resin matrix and makes it difficult to achieve effective polymer bonding. Therefore, surface modification of PBO fiber is the key to improving its interfacial bonding force with the composite material. Summary of the Invention

[0004] The purpose of the present invention is to provide a modification method for poly(p-phenylene benzobisoxazole) fiber, which is simple and efficient in operation, does not require complex equipment, is suitable for industrial production, and can significantly improve the surface hydrophilicity without damaging the bulk properties of the PBO fiber.

[0005] To achieve the above purpose, the present invention provides a modification method for poly(p-phenylene benzobisoxazole) fiber, including the following steps,

[0006] S1. Cut and rinse the poly(p-phenylene benzobisoxazole) fiber (PBO fiber), then immerse it in a mixed solution of ethanol and acetone, rinse it with ethanol and dry it to obtain pretreated poly(p-phenylene benzobisoxazole) fiber;

[0007] S2. Dissolve polyvinyl alcohol (PVA) in water, heat it in a water bath at 80 - 100 °C, and stir until completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0008] S3. Add an iron salt or ferrous salt to the aqueous polyvinyl alcohol solution in S2, then add the pretreated poly(p-phenylene benzobisoxazole) fiber in S1, uniformly immerse it and then add a persulfate, heat it in a water bath for 0.5 - 3 h, and take out the cross-linked treated fiber after cooling;

[0009] S4. Put the cross-linked treated fiber obtained in S3 into deionized water for ultrasonic washing, and dry it to obtain PVA / PBO fiber.

[0010] In the modification method provided by the present invention, deionized water is used to rinse the poly(p-phenylene benzobisoxazole) fiber to remove the dust and soluble impurities attached to its surface.

[0011] Preferably, in S1, the solid-liquid ratio of the poly(p-phenylene benzobisoxazole) fiber to the mixed solution is 0.5 - 100 g / L, and the soaking time is 1 - 5 h.

[0012] More preferably, the solid-liquid ratio of the poly(p-phenylene benzobisoxazole) fiber to the mixed solution is 10 - 80 g / L, and the soaking time is 2 - 4 h.

[0013] Preferably, in S1, the volume ratio of ethanol to acetone in the mixed solution is 1:1.

[0014] In the modification method provided by the present invention, a mixed solution of ethanol and acetone is used to clean the poly(p-phenylene benzobisoxazole) fiber to remove the impurities and sizing agents attached to its surface.

[0015] Preferably, in S1, the drying temperature is 60 - 80 °C, and the drying time is 0.5 - 2 h.

[0016] More preferably, in S1, the drying temperature is 65 - 75 °C, and the drying time is 1 h.

[0017] Preferably, in S2, the concentration of the polyvinyl alcohol aqueous solution is 0.05 - 1 g / L, and the polyvinyl alcohol includes one or more of polyvinyl alcohol 0588 type (degree of polymerization 500), polyvinyl alcohol 1788 type (degree of polymerization 1700), and polyvinyl alcohol 2488 type (degree of polymerization 2400).

[0018] More preferably, in S2, the concentration of the polyvinyl alcohol aqueous solution is 0.1 - 1 g / L.

[0019] Preferably, in S3, the solid-liquid ratio of the pretreated poly(p-phenylene benzobisoxazole) fiber to the polyvinyl alcohol aqueous solution is 0.5 - 10 g / L.

[0020] Preferably, in S3, the concentration after adding the iron salt or ferrous salt is 1 - 10 mmol / L. The iron salts include one or more of ferric chloride, ferric nitrate, ferric sulfate, and their hydrates;

[0021] More preferably, in S3, the concentration of iron ions after adding the iron salt or ferrous salt is 4.5 - 6.5 mmol / L.

[0022] The ferrous salts include one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, and their hydrates.

[0023] Preferably, in S3, the concentration after adding the persulfate is 0.5 - 10 mmol / L. The persulfates include one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0024] More preferably, in S3, the concentration after adding persulfate is 1-5 mmol / L.

[0025] Preferably, in S3, the heating temperature is 60-90 °C and the heating time is 1-3 h.

[0026] More preferably, in S3, the heating temperature is 75-85 °C and the heating time is 1.5 h.

[0027] Preferably, in S4, the drying temperature is 60-80 °C and the drying time is 0.5-2 h.

[0028] Mechanism of the present invention:

[0029] Utilize iron ions to catalyze the decomposition of persulfate to generate free radicals, and the free radicals further initiate the self-polymerization reaction of PVA on the surface of PBO fibers, forming a uniform and dense polymer coating, thereby significantly improving the surface properties of PBO fibers, while the mechanical properties of PVA / PBO fibers are not affected.

[0030] Therefore, the present invention adopts the above-mentioned steps for a modification method of poly(p-phenylene benzobisoxazole) fibers. PVA only crosslinks on the surface of PBO fibers and does not affect the internal structure of PBO fibers. It can significantly improve the surface hydrophilicity without damaging the bulk properties of PBO fibers. The water contact angle of the obtained PVA / PBO fibers is significantly reduced to 60°-90°;

[0031] The modification method provided by the present invention is simple and efficient in operation, does not require complex equipment, and is suitable for industrial production.

[0032] Next, through examples, the technical solutions of the present invention will be further described in detail. Detailed implementation manners

[0033] Next, in combination with examples, the present invention will be further described. Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those of ordinary skill in the field to which the present invention belongs. The above-mentioned features mentioned in the present invention or the features mentioned in the specific examples can be combined arbitrarily. These specific examples are only used to illustrate the present invention and do not limit the scope of the present invention.

[0034] Example 1

[0035] A modification method of poly(p-phenylene benzobisoxazole) fibers, comprising the following steps,

[0036] S1. Cut 1 g of poly(p-phenylene benzobisoxazole) fibers into 5 cm and rinse with deionized water, then immerse in 50 mL of a mixed solution of ethanol and acetone (V 乙醇 :V 丙酮It was placed in [a certain solution] for 3 h at a volume ratio of 1:1, rinsed with ethanol, and then dried in a vacuum oven at a drying temperature of 65 °C for 1 h to obtain clean pretreated poly(p-phenylene benzobisoxazole) fibers;

[0037] S2. Dissolve 1 g of polyvinyl alcohol type 1788 in 1.5 L of water, heat it in a water bath at 95 °C, and stir until completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0038] S3. Add 0.49 g (3 mmol) of ferric chloride to the aqueous polyvinyl alcohol solution in S2, then add 1 g of the pretreated poly(p-phenylene benzobisoxazole) fibers in S1. After uniformly immersing, add 1 g of potassium persulfate to initiate the modification reaction, heat it in a water bath at 80 °C for 1.5 h, and take out the cross-linked fibers after cooling;

[0039] S4. Put the cross-linked fibers obtained in S3 into deionized water for ultrasonic washing, with a drying temperature of 65 °C and a drying time of 1 h. After drying, PVA / PBO fibers are obtained.

[0040] Example 2

[0041] A method for modifying poly(p-phenylene benzobisoxazole) fibers, comprising the following steps

[0042] S1. Cut 1 g of poly(p-phenylene benzobisoxazole) fibers into 5 cm, rinse them with deionized water, and then immerse them in a mixed solution of 50 mL of ethanol and acetone (V 乙醇 :V 丙酮 at a volume ratio of 1:1) for 3 h, rinse with ethanol, and then dry. The drying temperature is 65 °C and the drying time is 1 h to obtain clean pretreated poly(p-phenylene benzobisoxazole) fibers;

[0043] S2. Dissolve 1 g of polyvinyl alcohol type 1788 in 1.5 L of water, heat it in a water bath at 95 °C, and stir until completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0044] S3. Add 0.5 g (4 mmol) of ferric chloride to the aqueous polyvinyl alcohol solution in S2, then add 1 g of the pretreated poly(p-phenylene benzobisoxazole) fibers in S1. After uniformly immersing, add 1 g of potassium persulfate to initiate the modification reaction, heat it in a water bath at 80 °C for 1.5 h, and take out the cross-linked fibers after cooling;

[0045] S4. Put the cross-linked fibers obtained in S3 into deionized water for ultrasonic washing, with a drying temperature of 70 °C and a drying time of 1 h. After drying, PVA / PBO fibers are obtained.

[0046] Example 3

[0047] A method for modifying poly(p-phenylene benzobisoxazole) fibers, comprising the following steps

[0048] S1. Cut 1 g of poly(p-phenylene benzobisoxazole) fiber into 5 cm, rinse it with deionized water, then immerse it in a 50 mL mixed solution of ethanol and acetone (V 乙醇 :V 丙酮 is 1:1) for 3 h. After rinsing with ethanol, dry it at a temperature of 65 °C for 1 h to obtain clean pretreated poly(p-phenylene benzobisoxazole) fiber;

[0049] S2. Dissolve 0.8 g of polyvinyl alcohol 1788 in 1.5 L of water, heat it in a water bath at 95 °C, and stir until it is completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0050] S3. Add 0.16 g (1 mmol) of ferric chloride to the aqueous polyvinyl alcohol solution in S2, then add 1 g of the pretreated poly(p-phenylene benzobisoxazole) fiber in S1. After uniformly submerging, add 1 g of potassium persulfate to initiate the modification reaction. Heat it in a water bath at 80 °C for 1.5 h, and take out the cross-linked fiber after cooling;

[0051] S4. Put the cross-linked fiber obtained in S3 into deionized water for ultrasonic washing, dry it at a temperature of 65 °C for 1 h, and obtain PVA / PBO fiber after drying.

[0052] Example 4

[0053] A method for modifying poly(p-phenylene benzobisoxazole) fiber, comprising the following steps,

[0054] S1. Cut 1 g of poly(p-phenylene benzobisoxazole) fiber into 5 cm, rinse it with deionized water, then immerse it in a 50 mL mixed solution of ethanol and acetone (V 乙醇 :V 丙酮 is 1:1) for 3 h. After rinsing with ethanol, dry it at a temperature of 65 °C for 1 h to obtain pretreated poly(p-phenylene benzobisoxazole) fiber;

[0055] S2. Dissolve 0.8 g of polyvinyl alcohol 0588 in 1.5 L of water, heat it in a water bath at 95 °C, and stir until it is completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0056] S3. Add 0.49 g (3 mmol) of ferric chloride to the aqueous polyvinyl alcohol solution in S2, then add 1 g of the pretreated poly(p-phenylene benzobisoxazole) fiber in S1. After uniformly submerging, add 1 g of potassium persulfate to initiate the modification reaction. Heat it in a water bath at 80 °C for 1.5 h, and take out the cross-linked fiber after cooling;

[0057] S4. Put the cross-linked fiber obtained in S3 into deionized water for ultrasonic washing, dry it at a temperature of 65 °C for 1 h, and obtain PVA / PBO fiber after drying.

[0058] Example 5

[0059] A method for modifying poly(p-phenylene benzobisoxazole) fiber, comprising the following steps,

[0060] S1. Cut 1 g of poly(p-phenylene benzobisoxazole) fiber into 5 cm, rinse it with deionized water, and then immerse it in a mixed solution of 50 mL of ethanol and acetone (V 乙醇 :V 丙酮 is 1:1) for 3 h. After rinsing with ethanol, dry it. The drying temperature is 65 °C and the drying time is 1 h to obtain clean pretreated poly(p-phenylene benzobisoxazole) fiber;

[0061] S2. Dissolve 1 g of polyvinyl alcohol 2488 type in 1.5 L of water, heat it in a water bath at 95 °C, and stir until completely dissolved to obtain an aqueous polyvinyl alcohol solution;

[0062] S3. Add 0.49 g (3 mmol) of ferric chloride to the aqueous polyvinyl alcohol solution in S2, then add 1 g of the pretreated poly(p-phenylene benzobisoxazole) fiber in S1. After uniformly submerging, add 1 g of potassium persulfate to initiate the modification reaction. Heat it in a water bath at 80 °C for 0.5 h, and take out the cross-linked fiber after cooling;

[0063] S4. Put the cross-linked fiber obtained in S3 into deionized water for ultrasonic washing. The drying temperature is 65 °C and the drying time is 1 h. After drying, obtain PVA / PBO fiber.

[0064] Test example

[0065] Test the water droplet contact angles of the pretreated poly(p-phenylene benzobisoxazole) fibers (before modification) and PVA / PBO fibers (after modification) in Examples 1-5. The results are shown in Table 1.

[0066] It can be seen from the data in Table 1 that the surface properties of the PVA / PBO fibers (after modification) have been improved, the hydrophilicity of the PVA / PBO fiber surface has been significantly enhanced, and its surface water contact angle has been significantly reduced to 60°-90°.

[0067] Table 1. Data table of water droplet contact angles before and after modification in Examples 1-5

[0068]

[0069] Therefore, the method for modifying poly(p-phenylene benzobisoxazole) fiber adopting the above steps of the present invention utilizes iron ions to catalyze the decomposition of persulfate to generate free radicals. Under the action of the free radicals, PVA can undergo a self-crosslinking reaction and thus adhere to the surface of the PBO fiber to form a uniform and dense polymer coating, significantly improving the hydrophilicity of the PVA / PBO fiber surface.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for modifying poly(p-phenylene benzobisoxazole) fiber, characterized in that: The following steps are included: S1, cutting and washing the poly(p-phenylene benzobisoxazole) fiber, and then immersing the fiber in a mixed solution of ethanol and acetone, washing with ethanol and drying the fiber to obtain a pretreated poly(p-phenylene benzobisoxazole) fiber; S2, dissolving polyvinyl alcohol in water, heating in a water bath at 80-100° C., and stirring until completely dissolved to obtain a polyvinyl alcohol aqueous solution; S3, add ferric salt or ferrous salt to the polyvinyl alcohol aqueous solution in S2, then add the pretreated poly(p-phenylene benzobisoxazole) fiber in S1, add persulfate after evenly immersing, heat in a water bath for 0.5-3h, and take out the cross-linked fiber after cooling; S4. The cross-linked fiber obtained in S3 is put into deionized water for ultrasonic washing, and then dried to obtain PVA / PBO fiber.

2. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S1, the solid-liquid ratio of the poly(p-phenylene benzobisoxazole) fiber to the mixed solution is 0.5-100 g / L, and the soaking time is 1-5 h.

3. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S1, the volume ratio of ethanol to acetone in the mixed solution is 1:

1.

4. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S1, the drying temperature is 60-80°C and the drying time is 0.5-2h.

5. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S2, the concentration of the polyvinyl alcohol aqueous solution is 0.05-1g / L, and the polyvinyl alcohol includes one or more of polyvinyl alcohol type 0588, polyvinyl alcohol type 1788, and polyvinyl alcohol type 2488.

6. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S3, the solid-to-liquid ratio of the pretreated poly(p-phenylene benzobisoxazole) fiber and the poly(vinyl alcohol) aqueous solution is 0.5-10 g / L.

7. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S3, the concentration of iron ions after the addition of iron salt or ferrous salt is 1-10 mmol / L, and the iron salt includes one or more of ferric chloride, ferric nitrate, ferric sulfate, and hydrates thereof; The ferrous salt includes one or more of ferrous chloride, ferrous nitrate, ferrous sulfate, and hydrates thereof.

8. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S3, the concentration of persulfate after addition is 0.5-10 mmol / L, and the persulfate includes one or more of sodium persulfate, potassium persulfate and ammonium persulfate.

9. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S3, the heating temperature is 60-90°C and the heating time is 1-3h.

10. The method for modifying poly(p-phenylene benzobisoxazole) fiber according to claim 1, characterized in that: In S4, the drying temperature is 60-80°C and the drying time is 0.5-2h.

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