CN114959951B - Preparation method of polyacrylonitrile-based pre-oxidized fiber - Google Patents
Preparation method of polyacrylonitrile-based pre-oxidized fiber Download PDFInfo
- Publication number
- CN114959951B CN114959951B CN202210532728.3A CN202210532728A CN114959951B CN 114959951 B CN114959951 B CN 114959951B CN 202210532728 A CN202210532728 A CN 202210532728A CN 114959951 B CN114959951 B CN 114959951B
- Authority
- CN
- China
- Prior art keywords
- polyacrylonitrile
- silicone oil
- based pre
- oxidized
- oxidized fiber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
- D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
- Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
Abstract
The invention provides a preparation method of novel polyacrylonitrile-based pre-oxidized fiber. The preparation method comprises the following steps: (1) Pretreating polyacrylonitrile-based precursor tows in high-temperature silicone oil; (2) passing the filament bundle obtained in the step (1) through a cleaning tank; (3) Dipping the tows obtained in the step (2) in a strong oxidizing solution; (4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil; (5) And (3) passing the tows obtained in the step (4) through a cleaning tank, and cleaning off residual silicone oil on the surfaces to obtain the polyacrylonitrile-based pre-oxidized fibers. The method greatly shortens the traditional preoxidation time, and can prepare the polyacrylonitrile-based preoxidized fiber more quickly and efficiently.
Description
Technical Field
The invention relates to a preparation method of polyacrylonitrile-based pre-oxidized fiber.
Background
The large amount of cyano groups contained in the polyacrylonitrile precursor structure are extremely strong polar functional groups, and strong acting forces exist between the functional groups, so that the melting point of the precursor reaches 335 ℃, and because the polyacrylonitrile molecules are hot melt polymers, the molecular chains are melted after the reaction temperature reaches 335 ℃, the fiber morphology cannot be maintained, and finally, the corresponding carbon fiber cannot be prepared.
Therefore, in order to obtain a carbon fiber having a fiber morphology, it is necessary to stabilize the filaments by thermal oxidation to strengthen the molecular structure of the polyacrylonitrile filaments and to change the linear molecular chains having melting properties into a trapezoid structure having heat resistance and stability. In the preoxidation process, the polyacrylonitrile macromolecular chain undergoes relatively complex physical and chemical reactions, and the linear polyacrylonitrile molecule undergoes internal cyclization, intermolecular crosslinking and the like. Wherein the addition cyclization reaction between unsaturated cyano (-C≡N) groups contained on PAN linear molecular chains is the main reaction in the pre-oxidation process, imine bonds (-C=N-) are generated in the cyclization reaction process, conjugated heat-resistant trapezoid structures are generated between the hydrogenated molecular chains, and hydroxyl groups, carbonyl groups and other groups are generated by oxidation reaction with oxygen in air atmosphere, so that the stability of the polyacrylonitrile molecular chain structure is enhanced, and the smooth proceeding of the subsequent reaction is ensured.
The traditional preoxidation process of the polyacrylonitrile fiber is usually carried out in a high-temperature air atmosphere, and the oxidation cyclization reaction degree of the precursor is controlled by adjusting the reaction time, temperature and drawing under different temperature conditions. Only in the case of suitable reaction conditions can the preoxidation of the precursor be ensured to be completed successfully. The stable pre-oxidation process widely used at present requires 4-6 pre-oxidation temperature areas, the pre-oxidation temperature is 210-280 ℃, the pre-oxidation time is 60-80 min, and the pre-oxidation time accounts for about 90% of the total production time of the carbon fiber. It is evident that long-term pre-oxidation becomes a major factor affecting the production of pre-oxidized filaments and final carbon fibers. Therefore, on the premise of ensuring the quality, how to effectively promote the permeation of oxygen into the fiber, lighten the sheath-core structure of the fiber, and reduce or shorten the pre-oxidation time becomes the key for improving the yield and greatly reducing the production cost of the pre-oxidized fiber.
According to the research, the precursor is pretreated in the high-temperature silicone oil, so that the intramolecular cyclization degree of the precursor is greatly improved, the release of subsequent reaction heat is reduced, and oil-soluble small molecules such as tar oil generated by the reaction can be rapidly dissolved in the high-temperature silicone oil in the reaction process, so that aggregation on the filament bundle is avoided, and the filament bundle is polluted; then, the polyacrylonitrile fiber is soaked by a strong oxidant such as hydrogen peroxide or permanganate solution, so that the polyacrylonitrile fiber is swelled and filled with the strong oxidizing solution, and when the subsequent high-temperature silicone oil is treated, oxygen decomposed from the internal residual solution directly reacts with an inner layer molecular chain to generate a heat-resistant trapezoid structure, and meanwhile, the reaction heat is easier to diffuse out through liquid-phase silicone oil, so that the fiber heat accumulation is avoided, and finally the polyacrylonitrile preoxidized fiber is prepared. The preparation flow in the research can greatly shorten the pre-oxidation time to within 15 minutes, and greatly reduce the production and processing cost of the pre-oxidized fiber.
Disclosure of Invention
Aiming at the problems of complex process, high equipment requirement, high energy consumption and the like of the existing method for preparing polyacrylonitrile-based preoxidized fibers, the invention provides a novel efficient energy-saving preparation method.
The invention solves the technical problems by the following technical means:
(1) The polyacrylonitrile precursor fiber bundle is subjected to air isolation ultrasonic pretreatment in high-temperature silicone oil;
(2) The silk bundles obtained in the step (1) pass through an ultrasonic cleaning tank to remove silicone oil on the surface of the fiber;
(3) Carrying out ultrasonic impregnation treatment on the tows obtained in the step (2) in strong oxidizing impregnation liquid;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil;
(5) And (3) passing the tows obtained in the step (4) through an ultrasonic cleaning tank to remove silicone oil on the surfaces of the fibers, and preparing the polyacrylonitrile-based pre-oxidized fibers.
Preferably, the high-temperature silicone oil treatment temperature in the step (1) is 230-280 ℃, the high-temperature silicone oil treatment time is 0.5-5 min, and the draft ratio is 0- +20%.
Preferably, the high-temperature silicone oil treatment in the step (1) is performed in an ultrasonic oscillation environment.
Preferably, the cleaning agent in the step (2) is an organic solvent capable of dissolving silicone oil.
Preferably, the cleaning treatment in the step (2) is performed in an ultrasonic oscillation environment.
Preferably, the impregnating solution in the step (3) is hydrogen peroxide aqueous solution or permanganate aqueous solution, the concentration is 0-40%, and the impregnating time is 0.5-3 min.
Preferably, the treatment of the strong oxidizing impregnation liquid in the step (3) is performed in an ultrasonic oscillation environment.
Preferably, the high-temperature silicone oil treatment temperature in the step (4) is 240-300 ℃, the high-temperature silicone oil treatment time is 3-10 min, and the draft ratio is-10%.
Preferably, the cleaning agent in the step (5) is an organic solvent capable of dissolving silicone oil, and the cleaning treatment is performed in an ultrasonic oscillation environment. The invention has the advantages that:
according to the research, the precursor is pretreated in the high-temperature silicone oil, so that the intramolecular cyclization degree of the precursor is greatly improved, the release of subsequent reaction heat is reduced, and oil-soluble small molecules such as tar oil generated by the reaction can be rapidly dissolved in the high-temperature silicone oil in the reaction process, so that aggregation on the filament bundle is avoided, and the filament bundle is polluted; then, the polyacrylonitrile fiber is soaked by a strong oxidant such as hydrogen peroxide or permanganate solution, so that the polyacrylonitrile fiber is swelled and filled with the strong oxidizing solution, and when the subsequent high-temperature silicone oil is treated, oxygen decomposed from the internal residual solution directly reacts with an inner layer molecular chain to generate a heat-resistant trapezoid structure, and meanwhile, the reaction heat is easier to diffuse out through liquid-phase silicone oil, so that the fiber heat accumulation is avoided, and finally the polyacrylonitrile preoxidized fiber is prepared. The preparation flow in the research can greatly shorten the pre-oxidation time to within 15 minutes, and greatly reduce the production and processing cost of the pre-oxidized fiber.
Drawings
FIG. 1 is a process flow diagram of a method for preparing a polyacrylonitrile-based pre-oxidized fiber according to the present invention.
Detailed Description
The following further describes specific embodiments of the present invention to facilitate a further understanding of the present invention by those skilled in the art.
Example 1
The preparation method of the polyacrylonitrile preoxidized fiber in the embodiment specifically comprises the following steps:
(1) Ultrasonic treating 6K polyacrylonitrile precursor (Coomal polyacrylonitrile precursor, UK) in high temperature silicone oil at 250deg.C for 1min with draft ratio of +5%;
(2) Ultrasonically cleaning the tows obtained in the step (1) in a carbon tetrachloride solution;
(3) Carrying out ultrasonic pre-soaking treatment on the silk bundles obtained in the step (2) in a hydrogen peroxide solution with the concentration of 15% for 2min;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil at 280 ℃ for 8min, wherein the draft ratio is 0;
(5) Ultrasonically cleaning the tows obtained in the step (4) in a carbon tetrachloride solution;
the polyacrylonitrile-based pre-oxidized fiber is prepared according to the steps, the density of the fiber body is 1.36g/m < 3 >, the strength of a monofilament is 0.35GPa, and the limiting oxygen index is 32%.
Example 2
The preparation method of the polyacrylonitrile preoxidized fiber in the embodiment specifically comprises the following steps:
(1) Carrying out ultrasonic treatment on a 12K polyacrylonitrile precursor (Jilin chemical fiber polyacrylonitrile precursor) in high-temperature silicone oil at 240 ℃ for 1.5min, wherein the draft ratio is +2%;
(2) Ultrasonically cleaning the tows obtained in the step (1) in a carbon tetrachloride solution;
(3) Carrying out ultrasonic pre-soaking treatment on the filament bundles obtained in the step (2) in a 25% hydrogen peroxide solution for 2min;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil at 270 ℃ for 8min, wherein the draft ratio is +1%;
(5) Ultrasonically cleaning the tows obtained in the step (4) in a carbon tetrachloride solution;
the polyacrylonitrile-based pre-oxidized fiber is prepared according to the steps, the density of the fiber body is 1.37g/m < 3 >, the monofilament strength is 0.38GPa, and the limiting oxygen index is 34%.
Example 3
The preparation method of the polyacrylonitrile preoxidized fiber in the embodiment specifically comprises the following steps:
(1) Ultrasonic treating 48K polyacrylonitrile precursor (Shanghai petrochemical polyacrylonitrile precursor) in high-temperature silicone oil at 250 ℃ for 2min with a draft ratio of +5%;
(2) Ultrasonically cleaning the tows obtained in the step (1) in a carbon tetrachloride solution;
(3) Carrying out ultrasonic pre-soaking treatment on the filament bundles obtained in the step (2) in a potassium permanganate aqueous solution with the concentration of 25% for 2min;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil at 285 ℃ for 10min, wherein the draft ratio is +2%;
(5) Ultrasonically cleaning the tows obtained in the step (4) in a carbon tetrachloride solution;
the polyacrylonitrile-based pre-oxidized fiber is prepared according to the steps, the density of the fiber body is 1.41g/m < 3 >, the monofilament strength is 0.25GPa, and the limiting oxygen index is 42%.
Example 4
The preparation method of the polyacrylonitrile preoxidized fiber in the embodiment specifically comprises the following steps:
(1) Ultrasonic treating 96K polyacrylonitrile precursor (Shanghai petrochemical polyacrylonitrile precursor) in high-temperature silicone oil at 230 ℃ for 3min with a draft ratio of +5%;
(2) Ultrasonically cleaning the tows obtained in the step (1) in a carbon tetrachloride solution;
(3) Carrying out ultrasonic pre-soaking treatment on the filament bundles obtained in the step (2) in a 30% hydrogen peroxide solution for 3min;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil at 270 ℃ for 10min, wherein the draft ratio is-1%;
(5) Ultrasonically cleaning the tows obtained in the step (4) in a carbon tetrachloride solution;
the polyacrylonitrile-based pre-oxidized fiber is prepared according to the steps, the density of the fiber body is 1.43g/m < 3 >, the monofilament strength is 0.23GPa, and the limiting oxygen index is 44%.
Example 5
The preparation method of the polyacrylonitrile preoxidized fiber in the embodiment specifically comprises the following steps:
(1) Performing ultrasonic treatment on 50K polyacrylonitrile precursor (Jilin chemical fiber polyacrylonitrile precursor) in high-temperature silicone oil at 230 ℃ for 2min, wherein the draft ratio is +7%;
(2) Ultrasonically cleaning the tows obtained in the step (1) in a carbon tetrachloride solution;
(3) Carrying out ultrasonic pre-soaking treatment on the filament bundles obtained in the step (2) in a potassium permanganate aqueous solution with the concentration of 10% for 2min;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil at 275 ℃ for 4min, wherein the draft ratio is +2%;
(5) Ultrasonically cleaning the tows obtained in the step (4) in a carbon tetrachloride solution;
the polyacrylonitrile-based pre-oxidized fiber is prepared according to the steps, the density of the fiber body is 1.32g/m < 3 >, the strength of a monofilament is 0.40GPa, and the limiting oxygen index is 28%.
Claims (16)
1. The preparation method of the polyacrylonitrile-based pre-oxidized fiber is characterized by comprising the following steps of:
(1) The polyacrylonitrile precursor fiber bundle is subjected to air isolation ultrasonic pretreatment in high-temperature silicone oil;
(2) The silk bundles obtained in the step (1) pass through an ultrasonic cleaning tank to remove silicone oil on the surface of the fiber;
(3) Carrying out ultrasonic impregnation treatment on the tows obtained in the step (2) in strong oxidizing impregnation liquid;
(4) Heat-treating the tows obtained in the step (3) in high-temperature silicone oil;
(5) And (3) passing the tows obtained in the step (4) through an ultrasonic cleaning tank to remove silicone oil on the surfaces of the fibers, and preparing the polyacrylonitrile-based pre-oxidized fibers.
2. The method for preparing polyacrylonitrile-based preoxidized fibers according to claim 1, wherein the high-temperature silicone oil in the step (1) has a temperature of 230-280 ℃.
3. The method for preparing polyacrylonitrile-based pre-oxidized fibers according to claim 1, wherein the high-temperature silicone oil treatment time in the step (1) is 0.5-5 min.
4. The method for producing a polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the draft ratio in the step (1) is 0 to +20% when treated with a high-temperature silicone oil.
5. The method for preparing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the high-temperature silicone oil treatment in step (1) is performed in an ultrasonic oscillation environment.
6. The method for preparing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the cleaning agent in the step (2) is an organic solvent capable of dissolving silicone oil.
7. The method for producing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the washing treatment in step (2) is performed in an ultrasonic oscillation environment.
8. The method for producing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the strong oxidizing impregnation liquid in the step (3) comprises an aqueous hydrogen peroxide solution or an aqueous permanganate solution or an oil solution.
9. The method for producing a polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the concentration of the strong oxidizing impregnation liquid in the step (3) is 0 to 40%.
10. The method for preparing polyacrylonitrile-based pre-oxidized fibers according to claim 1, wherein the treatment time of the strong oxidizing impregnation liquid in the step (3) is 0.5-3 min.
11. The method for producing a polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the strong oxidizing impregnation treatment in the step (3) is performed in an ultrasonic oscillation environment.
12. The method for preparing polyacrylonitrile-based preoxidized fibers according to claim 1, wherein the high-temperature silicone oil in the step (4) is at a temperature of 240-300 ℃.
13. The method for preparing polyacrylonitrile-based pre-oxidized fibers according to claim 1, wherein the high-temperature silicone oil treatment time in the step (4) is 3-10 min.
14. The method for preparing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the stretching in the step (4) is-10% to +10% when treated with high-temperature silicone oil.
15. The method for preparing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the cleaning agent in the step (5) is an organic solvent capable of dissolving silicone oil.
16. The method for producing polyacrylonitrile-based pre-oxidized fiber according to claim 1, wherein the washing treatment in step (5) is performed in an ultrasonic oscillation environment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210532728.3A CN114959951B (en) | 2022-05-11 | 2022-05-11 | Preparation method of polyacrylonitrile-based pre-oxidized fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210532728.3A CN114959951B (en) | 2022-05-11 | 2022-05-11 | Preparation method of polyacrylonitrile-based pre-oxidized fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114959951A CN114959951A (en) | 2022-08-30 |
| CN114959951B true CN114959951B (en) | 2023-10-13 |
Family
ID=82983713
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210532728.3A Active CN114959951B (en) | 2022-05-11 | 2022-05-11 | Preparation method of polyacrylonitrile-based pre-oxidized fiber |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114959951B (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012082541A (en) * | 2010-10-08 | 2012-04-26 | Toray Ind Inc | Method for producing carbon fiber |
| CN106637521A (en) * | 2016-12-27 | 2017-05-10 | 长春工业大学 | Preparation method of 48K polyacrylonitrile-based carbon fiber |
| CN110067044A (en) * | 2019-05-20 | 2019-07-30 | 中国科学院山西煤炭化学研究所 | A kind of PAN based graphite fiber and preparation method thereof |
-
2022
- 2022-05-11 CN CN202210532728.3A patent/CN114959951B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012082541A (en) * | 2010-10-08 | 2012-04-26 | Toray Ind Inc | Method for producing carbon fiber |
| CN106637521A (en) * | 2016-12-27 | 2017-05-10 | 长春工业大学 | Preparation method of 48K polyacrylonitrile-based carbon fiber |
| CN110067044A (en) * | 2019-05-20 | 2019-07-30 | 中国科学院山西煤炭化学研究所 | A kind of PAN based graphite fiber and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114959951A (en) | 2022-08-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102181963B (en) | Curing treatment method of carbon fiber precursor polyacrylonitrile fiber | |
| KR101689861B1 (en) | Nanocarbon composite carbon fiber with low cost and high performance and their preparation method | |
| CN111560666B (en) | Pre-oxidation method of polyacrylonitrile-based carbon fiber precursor | |
| Frank et al. | Carbon fibers: precursors, manufacturing, and properties | |
| EP2415913B1 (en) | Processes for producing carbon fiber precursor | |
| CN102733009B (en) | High strength polyacrylonitrile-base carbon fibers having structured surface grooves, and preparation method thereof | |
| KR101726822B1 (en) | Ultrafine carbon fibers and their preparation method | |
| CN102586952A (en) | Method for preparing graphene-reinforced polyacrylonitrile carbon fibers | |
| CN114959951B (en) | Preparation method of polyacrylonitrile-based pre-oxidized fiber | |
| CN111101241A (en) | Manufacturing method for improving strength of carbon fiber | |
| CN112226851B (en) | Preparation method of polyacrylonitrile-based carbon fiber | |
| Zhang et al. | Manufacture of carbon fibers from polyacrylonitrile precursors treated with CoSO4 | |
| CN110373729B (en) | Nascent fiber, polyacrylonitrile-based carbon fiber and preparation method thereof | |
| CN106592019B (en) | The preparation method of polyacrylonitrile-radical high-performance carbon fibre | |
| CN108611705B (en) | Preparation method of polyacrylonitrile-based high-performance carbon fiber | |
| CN110863270A (en) | Method for reducing ash content of high-strength polyacrylonitrile-based carbon fiber and application thereof | |
| CN102758272A (en) | Efficient preparation method of polyacrylonitrile-based carbon fibers | |
| CN112982027B (en) | Modification method of high-performance carbon paper based on supercritical fluid technology | |
| CN109322010A (en) | Utilize the polyacrylonitrile carbon fiber and preparation method thereof of waste polypropylene nitrile fiber preparation | |
| CN114790592A (en) | Method for preparing high-performance asphalt-based carbon fiber through rapid pre-oxidation | |
| CN107630268B (en) | Method for cyclizing PAN carbon fiber precursor | |
| CN106637520A (en) | Method for regulating and controlling homogenization degree of polyacrylonitrile preoxidized fiber | |
| CN110273198B (en) | Method for quickly pre-oxidizing mesophase pitch fibers | |
| CN114941188B (en) | Method for continuously preparing carbon fiber from acrylic fiber | |
| CN114457469A (en) | Preparation method of polyacrylonitrile pre-oxidized fiber, pre-oxidized fiber and application |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |