Superfine polyethylene fiber and preparation method thereof

Abstract

The invention discloses a superfine polyethylene fiber and a preparation method thereof, and belongs to the technical field of polyethylene fibers.The preparation method of the superfine polyethylene fiber comprises the following steps of polyethylene resin modification, melt spinning, fiber surface treatment and heat treatment; the polyethylene resin modification comprises the following steps: dissolving benzoyl peroxide and 2-ethylhexyl acrylate in diethyl ether to obtain a premixed solution A, dissolving an antioxidant 1010 and dibenzothiazyl disulfide in chloroform to obtain a premixed solution B, uniformly mixing the premixed solution A, the premixed solution B and the polyethylene resin to completely volatilize the diethyl ether and the chloroform, banburying, extruding and granulating. The superfine polyethylene fiber prepared by the method disclosed by the invention is high in breaking strength and low in yarn breaking rate, the breaking strength is 9.47 to 9.86 cN / dtex, the modulus is 1678 to 1715 cN / dtex, and the yarn breaking rate is 0.32 to 0.41 percent.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyethylene fibers, and particularly relates to an ultra-fine polyethylene fiber and a preparation method thereof. Background Art

[0002] Polyethylene is a polymer produced on a large scale, with a wide range of raw material sources and relatively low production costs. Polyethylene has a relatively high carbon content, about 85.7%, and it is a thermoplastic that can be easily processed by a melt spinning process. The high carbon content, low cost, and good processability of polyethylene provide strong support for the application of polyethylene fibers as carbon fiber precursors.

[0003] Ultra-fine polyethylene fibers have the advantages of light weight, excellent mechanical properties, and good corrosion resistance. They are a potential lightweight material and have certain potential in the field of carbon fiber preparation.

[0004] Polyethylene fibers are made by a solution spinning process and can be stretched as needed to change their properties. When polyethylene fibers are stretched, the macromolecular chains inside will be oriented along the stress direction under the action of the tension force. This orientation reduces the defects inside the fibers and improves the crystallinity, thereby increasing the strength of the fibers. The increase in the draw ratio also changes the molecular structure of polyethylene fibers, and the orientation degree and crystallinity of the fibers will increase with the increase in the draw ratio, which helps to improve the mechanical properties and stability of the fibers.

[0005] Although increasing the draw ratio can enhance the strength of the fibers, in order to produce ultra-fine polyethylene fibers, super-drawing is required. When the draw ratio exceeds a certain limit, the excessive draw ratio will cause the molecular chains inside the fibers to be over-oriented and stretched, and even lead to the fracture and slip of the molecular chains. Crazes, broken filaments or other defects may appear on the fiber surface, resulting in a decrease in the breaking strength of the fibers.

[0006] After high-drawing of polyethylene, it needs to be heat-treated in an inert gas atmosphere such as nitrogen to carry out a solid-phase polymerization reaction, change the crystal structure of the polyethylene fibers, increase the crystallinity, improve the thermal stability of the fibers, and eliminate the microporous structure formed during the fiber stretching process to ensure that the finally produced polyethylene fibers have excellent properties. However, high-temperature heat treatment easily causes the ultra-fine polyethylene fibers to bond together again, affecting the properties such as the fineness and strength of the fibers. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the present invention provides an ultra-fine polyethylene fiber and a preparation method thereof. The ultra-fine polyethylene fiber prepared by this method is easy to stretch and form, has high tensile strength, high modulus, and low broken filament rate.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A preparation method of ultrafine polyethylene fibers, comprising the following steps: modification of polyethylene resin, melt spinning, fiber surface treatment, heat treatment; The step of modifying the polyethylene resin is to dissolve benzoyl peroxide and 2-ethylhexyl acrylate in ether to obtain premixed solution A, dissolve antioxidant 1010 and dibenzothiazole disulfide in chloroform to obtain premixed solution B, mix premixed solution A, premixed solution B and polyethylene resin evenly, completely volatilize ether and chloroform, then carry out internal mixing for 12-18 min, control the internal mixing temperature at 160-180 °C, and extrude and pelletize after the internal mixing is completed to obtain modified polyethylene resin; The mass ratio of benzoyl peroxide, 2-ethylhexyl acrylate, and ether in the premixed solution A is 0.04-0.08:0.08-0.12:2; The mass ratio of antioxidant 1010, dibenzothiazole disulfide, and chloroform in the premixed solution B is 0.18-0.22:0.1-0.2:2; The mass ratio of the polyethylene resin, premixed solution A, and premixed solution B is 100:2.0-2.1:2.1-2.3; The polyethylene resin is in the form of particles with a diameter of 0.5-2 mm; The weight-average molecular weight of the polyethylene resin is 10.4×10 4 -15.2×10 4 ; The step of melt spinning is to mix, melt, and extrude the modified polyethylene resin, lubricant, and antioxidant through a screw machine, and after metering, extrude through a spinneret with a pore diameter of 0.08-0.12 mm, and cool in a water bath to obtain polyethylene raw filaments; perform three-stage high-stretch drawing and winding on the polyethylene raw filaments to obtain an ultrafine polyethylene fiber preform; The lubricant is selected from one of polyethylene oxide wax, calcium stearate, and stearyl alcohol; The antioxidant is antioxidant 1010; The mass ratio of the modified polyethylene resin, lubricant, and antioxidant is 100:1-1.2:0.2-0.4; The melt extrusion temperature is 200-230 °C; In the three-stage high-stretch drawing, the first-stage drawing temperature is 70-80 °C, the drawing ratio is 5-7 times, the second-stage drawing temperature is 100-110 °C, the drawing ratio is 4-6 times, the third-stage drawing temperature is 130-140 °C, and the drawing ratio is 2-3 times.

[0009] The steps of the fiber surface treatment are as follows: Graphite is dispersed in absolute ethanol and ball-milled in a ball-milling device at a ball-to-material ratio of 10-20:1 for 60-80 minutes. After ball-milling, it is filtered and dried to obtain exfoliated graphite. After mixing the exfoliated graphite and aluminum aluminate coupling agent DL-411 evenly, the temperature is raised to 90-110 °C and reacted for 3-5 minutes to obtain modified graphite. The modified graphite is evenly sprayed on the surface of the ultra-fine polyethylene fiber preform at 45-50 °C, and then the temperature is raised to 90-110 °C and maintained for 3-5 minutes. After the reaction, graphite-treated ultra-fine polyethylene fibers are obtained. The mass ratio of the graphite to the absolute ethanol is 105:120-140; The mass ratio of the exfoliated graphite to the aluminum aluminate coupling agent DL-411 is 100:1-1.2; The mass ratio of the modified graphite attached to the graphite-treated ultra-fine polyethylene fibers to the ultra-fine polyethylene fiber preform is 0.5-1:100.

[0010] The steps of the heat treatment are as follows: The graphite-treated ultra-fine polyethylene fibers are heat-treated in a dry nitrogen atmosphere at 210-215 °C for 2-3 hours, and then heat-treated at 230-235 °C for 12-14 hours. After the heat treatment, ultra-fine polyethylene fibers are obtained.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: The ultra-fine polyethylene fibers prepared by the method of the present invention are easy to stretch and form, have high breaking strength, low wire breakage rate, with a breaking strength of 9.47-9.86 cN / dtex, a modulus of 1678-1715 cN / dtex, and a wire breakage rate of 0.32-0.41%. Detailed Embodiments

[0012] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention are now described.

[0013] Example 1 A method for preparing ultra-fine polyethylene fibers Comprises the following steps: (1) Modification of polyethylene resin 0.04 g of benzoyl peroxide and 0.08 g of 2-ethylhexyl acrylate are dissolved in 2 g of ether to obtain premixed solution A. 0.18 g of antioxidant 1010 and 0.1 g of dibenzothiazyl disulfide are dissolved in 2 g of chloroform to obtain premixed solution B. 2.0 g of premixed solution A and 2.1 g of premixed solution B are mixed evenly with 100 g of polyethylene resin, and the ether and chloroform are completely volatilized. Then, it is kneaded for 12 minutes, and the kneading temperature is controlled at 180 °C. After kneading, it is extruded and granulated by a screw to obtain modified polyethylene resin; The polyethylene resin is in the form of particles with a diameter of 0.5 mm; The weight-average molecular weight of the polyethylene resin is 10.4×10 4 .

[0014] (2) Melt spinning 100 g of the modified polyethylene resin, 1 g of oxidized polyethylene wax, and 0.2 g of antioxidant 1010 are mixed, melted, and extruded through a screw machine. After metering, they are extruded through a spinneret with a pore diameter of 0.08 mm and cooled in a water bath to obtain polyethylene raw filaments. The polyethylene raw filaments are subjected to three-stage high-draft drawing and winding to obtain an ultra-fine polyethylene fiber preform; The melt extrusion temperature is 200 °C; In the three-stage high-draft drawing, the first-stage drawing temperature is 70 °C, the drawing ratio is 5 times, the second-stage drawing temperature is 110 °C, the drawing ratio is 6 times, the third-stage drawing temperature is 130 °C, and the drawing ratio is 2 times.

[0015] (3) Fiber surface treatment 105 g of graphite is dispersed in 120 g of absolute ethanol and ball-milled in a ball mill at a ball-to-material ratio of 10:1 for 60 min. After ball milling, it is filtered and dried to obtain exfoliated graphite. 100 g of exfoliated graphite and 1 g of aluminate coupling agent DL-411 are mixed evenly, and then the temperature is raised to 90 °C and reacted for 5 min to obtain modified graphite. At 45 °C, 0.5 g of modified graphite is evenly sprayed on the surface of 100 g of the ultra-fine polyethylene fiber preform, and then the temperature is raised to 90 °C and maintained for 5 min. After the reaction, graphite-treated ultra-fine polyethylene fibers are obtained.

[0016] (4) Heat treatment The graphite-treated ultra-fine polyethylene fibers are heat-treated in a dry nitrogen atmosphere at 210 °C for 3 hours, and then at 230 °C for 14 hours. After the heat treatment, ultra-fine polyethylene fibers are obtained.

[0017] Example 2 A method for preparing ultra-fine polyethylene fibers Comprising the following steps: (1) Modification of polyethylene resin 0.06 g of benzoyl peroxide and 0.10 g of 2-ethylhexyl acrylate are dissolved in 2 g of ether to obtain premixed solution A. 0.2 g of antioxidant 1010 and 0.15 g of dibenzothiazole disulfide are dissolved in 2 g of chloroform to obtain premixed solution B. 2.1 g of premixed solution A and 2.2 g of premixed solution B are mixed evenly with 100 g of polyethylene resin, and the ether and chloroform are allowed to evaporate completely. Then, it is kneaded for 16 min, and the kneading temperature is controlled at 170 °C. After kneading, it is granulated by screw extrusion to obtain modified polyethylene resin; The polyethylene resin is in the form of particles with a diameter of 1 mm; The weight-average molecular weight of the polyethylene resin is 12.1×10 4 .

[0018] (2) Melt spinning 100 g of the modified polyethylene resin, 1.1 g of calcium stearate, and 0.3 g of antioxidant 1010 are mixed, melt-extruded through a screw machine, metered, and then extruded through a spinneret with a pore diameter of 0.1 mm, and cooled in a water bath to obtain polyethylene raw filaments; the polyethylene raw filaments are subjected to three-stage high-draft drawing and winding to obtain an ultra-fine polyethylene fiber preform; The melt extrusion temperature is 210 °C; In the three-stage high-draft drawing, the first-stage drawing temperature is 75 °C, the drawing ratio is 6 times, the second-stage drawing temperature is 105 °C, the drawing ratio is 5 times, the third-stage drawing temperature is 135 °C, and the drawing ratio is 2.5 times.

[0019] (3) Fiber surface treatment 105 g of graphite is dispersed in 130 g of absolute ethanol, ball-milled in a ball mill at a ball-to-material ratio of 15:1 for 70 min, filtered and dried after ball milling to obtain exfoliated graphite. After mixing 100 g of exfoliated graphite with 1.1 g of aluminate coupling agent DL-411 evenly, the temperature is raised to 100 °C and reacted for 4 min to obtain modified graphite; at 47 °C, 0.8 g of modified graphite is evenly sprayed on the surface of 100 g of ultra-fine polyethylene fiber preform, and then the temperature is raised to 100 °C and maintained for 4 min, and the reaction ends to obtain graphite-treated ultra-fine polyethylene fibers.

[0020] (4) Heat treatment The graphite-treated ultra-fine polyethylene fibers are heat-treated in a dry nitrogen atmosphere at 212 °C for 2.5 hours, and then heat-treated at 232 °C for 13 hours. After the heat treatment, ultra-fine polyethylene fibers are obtained.

[0021] Example 3 A method for preparing ultra-fine polyethylene fibers comprising the following steps: (1) Modification of polyethylene resin 0.08 g of benzoyl peroxide and 0.12 g of 2-ethylhexyl acrylate are dissolved in 2 g of diethyl ether to obtain premixed solution A, 0.22 g of antioxidant 1010 and 0.2 g of dibenzothiazole disulfide are dissolved in 2 g of chloroform to obtain premixed solution B. 2.1 g of premixed solution A and 2.3 g of premixed solution B are mixed evenly with 100 g of polyethylene resin, and the diethyl ether and chloroform are completely volatilized, and then kneaded for 18 min, controlling the kneading temperature at 160 °C. After kneading, it is extruded and granulated by a screw to obtain modified polyethylene resin; The polyethylene resin is in the form of particles with a diameter of 2 mm; The weight-average molecular weight of the polyethylene resin is 15.2×104 .

[0022] (2) Melt spinning 100 g of modified polyethylene resin, 1.2 g of stearyl alcohol, and 0.4 g of antioxidant 1010 were melt - kneaded and extruded through a screw machine. After metering, they were extruded through a spinneret with a pore diameter of 0.12 mm and cooled in a water bath to obtain polyethylene raw filaments; the polyethylene raw filaments were subjected to three - stage high - draw and winding to obtain an ultra - fine polyethylene fiber preform; The melt - extrusion temperature was 230 °C; In the three - stage high - draw, the first - stage drawing temperature was 80 °C, the draw ratio was 7 times, the second - stage drawing temperature was 100 °C, the draw ratio was 4 times, the third - stage drawing temperature was 140 °C, and the draw ratio was 3 times.

[0023] (3) Fiber surface treatment 105 g of graphite was dispersed in 140 g of absolute ethanol and ball - milled in a ball mill at a ball - to - material ratio of 20:1 for 80 min. After ball - milling, it was filtered and dried to obtain exfoliated graphite. 100 g of exfoliated graphite was mixed evenly with 1.2 g of aluminate coupling agent DL - 411, and then the temperature was raised to 110 °C and reacted for 3 min to obtain modified graphite; at 50 °C, 1 g of modified graphite was evenly sprayed on the surface of 100 g of ultra - fine polyethylene fiber preform, and then the temperature was raised to 110 °C and maintained for 3 min. After the reaction, graphite - treated ultra - fine polyethylene fibers were obtained.

[0024] (4) Heat treatment The graphite - treated ultra - fine polyethylene fibers were heat - treated in a dry nitrogen atmosphere at 215 °C for 2 hours, and then at 235 °C for 12 hours. After the heat treatment, ultra - fine polyethylene fibers were obtained.

[0025] Comparative Example 1 Comparative Example 1 adopted the preparation method of the ultra - fine polyethylene fibers described in Example 2. The difference was that in the step of modifying the polyethylene resin, the addition of dibenzothiazole disulfide was omitted, and the other operation steps were the same.

[0026] Comparative Example 2 Comparative Example 2 adopted the preparation method of the ultra - fine polyethylene fibers described in Example 2. The difference was that in the step of fiber surface treatment, the step of "mixing 100 g of exfoliated graphite evenly with 1.1 g of aluminate coupling agent DL - 411, raising the temperature to 100 °C, and reacting for 4 min to obtain modified graphite" was omitted. The step of fiber surface treatment was changed to: 105 g of graphite was dispersed in 130 g of absolute ethanol and ball - milled in a ball mill at a ball - to - material ratio of 15:1 for 70 min. After ball - milling, it was filtered and dried to obtain exfoliated graphite. At 47 °C, 0.8 g of exfoliated graphite was evenly sprayed on the surface of 100 g of ultra - fine polyethylene fiber preform to obtain graphite - treated ultra - fine polyethylene fibers.

[0027] Test Example 1 The fineness, breaking strength, modulus, and broken filament rate of the ultrafine polyethylene fibers prepared in Examples 1-3 and Comparative Examples 1-2 were respectively detected; the test results are shown in Table 1.

[0028] Fineness test: Accurately measure the length of the fiber to be tested as 10 m, precisely weigh its mass on an electronic balance, and then calculate the average value of 10 measurements according to the fiber fineness formula, and then calculate the single-filament fineness of the fiber according to the number of spinneret holes; Mechanical property test: Use an electronic universal testing machine to test the breaking strength and modulus characteristics of the fiber. The grip distance of the test chuck is 20 mm, the tensile speed is 10 mm / min, the test environment temperature is 25 °C, and the humidity is 60%. The test results are the average value of 10 tests.

[0029] Table 1

[0030] As can be seen from Table 1, compared with Example 2, the breaking strength of Comparative Example 1 decreased and the broken filament rate increased. In the polyethylene resin modification step of the present invention, under the action of benzoyl peroxide initiator, the polyfunctional small molecule substance 2-ethylhexyl acrylate was grafted onto the polyethylene long-chain molecule. The introduction of branched chains in polyethylene can improve the melt strength of the material and strengthen the strain hardening phenomenon under tensile conditions, which is beneficial to the stretching and processing of polyethylene materials during the spinning process. The introduction of branched chains in polyethylene shows a certain strain hardening phenomenon during the stretching process. When the material is subjected to external force and undergoes plastic deformation, the internal lattice structure will change and the dislocation density will increase, resulting in an increase in the material's ability to resist deformation. This strain hardening phenomenon enables branched polyethylene to better maintain its integrity and stability under ultra-high drawing conditions, reducing the breakage and slippage of molecular chains. At the same time, the presence of branched chains on the molecular chain of polyethylene limits the crystallization ability of the polymer, enabling the material to better disperse stress during the stretching process and avoid stress concentration. The branched chains also increase the intermolecular interaction force and improve the overall strength of the material.

[0031] On the basis of Example 2, Comparative Example 1 omitted the addition of dibenzothiazole disulfide. Polyethylene tended to crosslink more under the action of benzoyl peroxide. The crosslinked structure can improve the modulus of polyethylene fibers to a certain extent, but the crosslinked polyethylene is prone to produce insoluble and infusible gels during melt processing, which will limit the movement of molecular chains to a certain extent. During the stretching process, the crosslinked structure will hinder the effective arrangement and orientation of molecular chains, limit the extension ability of molecular chains, and is more likely to break when subjected to external force, resulting in a decrease in tensile strength and an increase in the broken filament rate.

[0032] In the step of modifying the polyethylene resin of the present invention, dibenzothiazole disulfide is added. Dibenzothiazole disulfide cracks at high temperature to generate dibenzothiazole disulfide radicals. The dibenzothiazole disulfide radicals are relatively stable and do not undergo hydrogen abstraction reactions. The dibenzothiazole disulfide radicals can reversibly combine with polyethylene macromolecular radicals, stabilizing the polyethylene macromolecular radicals and prolonging the lifetime of the radicals. They can also reversibly combine with 2-ethylhexyl acrylate radicals, promoting the monomer grafting reaction to a certain extent.

[0033] As can be seen from Table 1, compared with Example 2, the fineness of Comparative Example 2 increases, the modulus decreases, and the breaking strength decreases. In the fiber surface treatment step of Comparative Example 2, the modification of graphite by the aluminate coupling agent DL-411 is omitted, and the graphite sprayed on the surface of the polyethylene fiber is easily detached. As a result, during the heat treatment process, the single fibers are not separated by enough graphite, and the fibers are easily adhered together, increasing the fineness and affecting the fiber strength.

[0034] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing ultrafine polyethylene fibers, characterized in that, The preparation method includes the following steps: modification of polyethylene resin, melt spinning, fiber surface treatment, and heat treatment; The step of modifying the polyethylene resin is as follows: dissolve benzoyl peroxide and 2-ethylhexyl acrylate in ether to obtain premixed solution A, dissolve antioxidant 1010 and dibenzothiazole disulfide in chloroform to obtain premixed solution B, mix premixed solution A, premixed solution B and polyethylene resin evenly, completely volatilize ether and chloroform, then carry out internal mixing for 12 - 18 min, control the internal mixing temperature at 160 - 180 °C, and extrude and pelletize after the internal mixing is completed to obtain modified polyethylene resin.

2. The preparation method of an ultra-fine polyethylene fiber according to claim 1, characterized in that, In the step of modifying the polyethylene resin, In the premixed solution A, the mass ratio of benzoyl peroxide, 2-ethylhexyl acrylate, and ether is 0.04 - 0.08:0.08 - 0.12:2; In the premixed solution B, the mass ratio of antioxidant 1010, dibenzothiazole disulfide, and chloroform is 0.18 - 0.22:0.1 - 0.2:2; The mass ratio of the polyethylene resin, premixed solution A, and premixed solution B is 100:2.0 - 2.1:2.1 - 2.

3.

3. The preparation method of an ultra-fine polyethylene fiber according to claim 1, characterized in that, In the step of modifying the polyethylene resin, the polyethylene resin is in the form of particles with a diameter of 0.5 - 2 mm; the weight-average molecular weight of the polyethylene resin is 10.4×10 4 -15.2×10 4 .

4. The preparation method of an ultra-fine polyethylene fiber according to claim 1, characterized in that, The step of melt spinning is as follows: mix, melt, and extrude the modified polyethylene resin, lubricant, and antioxidant through a screw machine, extrude through a spinneret with a pore diameter of 0.08 - 0.12 mm after metering, and cool in a water bath to obtain polyethylene raw filaments; Perform three-stage high-stretch and winding on the polyethylene raw filaments to obtain an ultra-fine polyethylene fiber preform.

5. The preparation method of an ultra-fine polyethylene fiber according to claim 4, characterized in that, In the step of melt spinning, The lubricant is selected from one of polyethylene oxide wax, calcium stearate, and stearyl alcohol; The antioxidant is antioxidant 1010; The mass ratio of the modified polyethylene resin, lubricant, and antioxidant is 100:1 - 1.2:0.2 - 0.4; The melt extrusion temperature is 200 - 230 °C.

6. The preparation method of an ultra-fine polyethylene fiber according to claim 4, characterized in that, In the step of melt spinning, in the three-stage high-stretch, the first-stage stretching temperature is 70 - 80 °C, the stretching ratio is 5 - 7 times, the second-stage stretching temperature is 100 - 110 °C, the stretching ratio is 4 - 6 times, the third-stage stretching temperature is 130 - 140 °C, and the stretching ratio is 2 - 3 times.

7. The preparation method of an ultra-fine polyethylene fiber according to claim 1, characterized in that, The step of fiber surface treatment is as follows: disperse graphite in absolute ethanol, ball mill in a ball milling device according to a ball-to-material ratio of 10 - 20:1 for 60 - 80 min, filter and dry after ball milling to obtain exfoliated graphite, mix the exfoliated graphite and aluminate coupling agent DL-411 evenly, heat up to 90 - 110 °C, and react for 3 - 5 min to obtain modified graphite; spray the modified graphite evenly on the surface of the ultra-fine polyethylene fiber preform at 45 - 50 °C, then raise the temperature to 90 - 110 °C and keep it for 3 - 5 min, and obtain graphite-treated ultra-fine polyethylene fibers after the reaction ends.

8. The preparation method of an ultra-fine polyethylene fiber according to claim 7, characterized in that, In the step of fiber surface treatment, the mass ratio of the graphite and absolute ethanol is 105:120 - 140; The mass ratio of the exfoliated graphite and aluminate coupling agent DL-411 is 100:1 - 1.2; The mass ratio of the modified graphite attached to the graphite-treated ultra-fine polyethylene fibers and the ultra-fine polyethylene fiber preform is 0.5 - 1:

100.

9. The preparation method of an ultra-fine polyethylene fiber according to claim 1, characterized in that, The steps of the heat treatment are as follows: treating the graphite-treated ultra-fine polyethylene fibers in a dry nitrogen atmosphere at 210-215°C for 2-3 hours, and then at 230-235°C for 12-14 hours, and obtaining ultra-fine polyethylene fibers after the heat treatment ends.

10. Ultra-fine polyethylene fibers prepared by the preparation method according to any one of claims 1-9.

Images