阅读说明：本技术 一种电化学制备的功能化石墨烯阻燃剂及其应用 (Electrochemically prepared functionalized graphene flame retardant and application thereof ) 是由 付少海 仇明慧 王冬 李敏 张丽萍 刘明明 田安丽 于 2019-08-27 设计创作，主要内容包括：本发明公开了一种电化学制备的功能化石墨烯阻燃剂及其应用,属于阻燃复合材料技术领域。本发明以二乙烯三胺五甲叉磷酸钠的水溶液为电解质,以石墨片为阳极、铜棒为阴极,电解得到二乙烯三胺五甲叉磷酸钠修饰的低缺陷、少层的石墨烯,与铁源混合,得到功能化石墨烯阻燃剂。利用将本发明制备得到的功能化石墨烯阻燃剂与聚丙烯腈共混,得到石墨烯/聚丙烯腈纳米复合材料,显著提高聚丙烯腈材料的阻燃性能和热稳定性,且对材料的力学性能没有损坏影响,在汽车内饰、服装面料、篷布、窗帘和地毯等领域具有广阔的应用前景。(The invention discloses a functionalized graphene flame retardant prepared by electrochemistry and application thereof, and belongs to the technical field of flame-retardant composite materials. According to the invention, aqueous solution of diethylenetriamine penta-methylene sodium phosphate is used as electrolyte, graphite flake is used as anode, copper bar is used as cathode, low-defect and few-layer graphene modified by diethylenetriamine penta-methylene sodium phosphate is obtained through electrolysis, and the graphene is mixed with iron source to obtain the functionalized graphene flame retardant. The functional graphene flame retardant prepared by the method is blended with polyacrylonitrile to obtain the graphene/polyacrylonitrile nano composite material, so that the flame retardant property and the thermal stability of the polyacrylonitrile material are obviously improved, the mechanical property of the material is not damaged and influenced, and the graphene/polyacrylonitrile nano composite material has wide application prospects in the fields of automobile interiors, garment materials, tarpaulins, curtains, carpets and the like.)

1. A preparation method of a functionalized graphene flame retardant is characterized by comprising the following steps:

(1) electrolyzing by using an aqueous solution of sodium diethylenetriamine penta-methylene phosphate as an electrolyte, a graphite sheet as an anode and a metal rod as a cathode to obtain the graphene modified by the sodium diethylenetriamine penta-methylene phosphate;

(2) and (2) mixing the graphene modified by the diethylenetriamine penta-methylene sodium phosphate obtained in the step (1) with an iron source to obtain the functionalized graphene flame retardant.

2. The method according to claim 1, wherein the voltage for electrolysis in step (1) is 5-15V.

3. The method according to claim 1 or 2, wherein the concentration of the aqueous solution of sodium diethylenetriamine pentamethylene phosphate in the step (1) is 0.1mol/L to 0.5 mol/L.

4. The method according to any one of claims 1 to 3, wherein the electrolysis time in step (1) is 1 to 6 hours.

5. The functionalized graphene flame retardant prepared by the method of any one of claims 1 to 4.

6. A polyacrylonitrile composite material, characterized in that the composite material comprises the functionalized graphene flame retardant of claim 5.

7. The composite material of claim 6, wherein the polyacrylonitrile composite material is obtained by blending polyacrylonitrile and a functionalized graphene flame retardant through a solution and then drying.

8. The composite material according to claim 6 or 7, wherein the addition amount of the functionalized graphene flame retardant accounts for 1-5% of the total mass of the polyacrylonitrile and the functionalized graphene flame retardant.

9. A carpet or tarpaulin or window covering, characterized in that the polyacrylonitrile composite material of any one of claims 6 to 8 is contained in the carpet or tarpaulin or window covering.

10. Use of the functionalized graphene flame retardant of claim 5 or the polyacrylonitrile composite material of any one of claims 6 to 8 in the field of automotive interior or clothing fabric.

Technical Field

The invention belongs to the technical field of flame-retardant composite materials, and particularly relates to an electrochemically prepared functionalized graphene flame retardant and application thereof.

Background

The polyacrylonitrile material is fluffy and curled in appearance, has better elasticity and better heat retention than wool; the sun-proof performance is excellent, and the paint is acid-resistant and oxidant-resistant; the method is widely applied to the fields of automotive interiors, garment materials, tarpaulins, curtains, carpets and the like. However, the limit oxygen index of polyacrylonitrile materials is only 17%, polyacrylonitrile materials are flammable fibers, and toxic cyanide and the like are released in the combustion process, so that the application of polyacrylonitrile materials is limited to a certain extent.

In recent years, research on high-heat-resistance graphene and graphene derivative flame-retardant polymer materials improves the fireproof performance of the materials, and becomes a hot point of research. As an important two-dimensional carbon material, the graphene has the characteristics of high stability, strong barrier, large surface adsorption and the like, and can effectively reduce heat transfer and mass transfer in the material combustion process. When the graphene-based polymer flame retardant material encounters high temperature or open fire, on the one hand, since the graphene lamellar structure is compact and continuous, it can prevent oxygen from entering deep into the material. In addition, due to the excellent thermal conductivity of the graphene, local and excessively high heat of the material can be rapidly conducted to the rest part of the material, so that the heat can be well dispersed, and the fire is not easy to spread and diffuse. On the other hand, the graphene has extremely high specific surface area, so that organic volatile matters generated in the combustion process can be adsorbed, and the release and diffusion of the organic volatile matters in the combustion process are prevented. Therefore, the unique two-dimensional carbon atom lamellar structure can be used as a good flame retardant to improve the flame retardant property of the polymer material.

The preparation method of the existing functionalized graphene flame retardant mainly comprises the following steps: (1) and (3) non-covalently modifying graphene oxide by using a flame retardant. For example, patent CN201510689007.3 discloses a method for preparing a molybdenum oxide nano-loaded graphene flame retardant material, which comprises mixing graphene oxide and ammonium molybdate according to a certain mass ratio, ball-milling, heating from 100 ℃ to 150 ℃ under the protection of nitrogen, and keeping the temperature for a period of time, to obtain the molybdenum oxide nano-loaded graphene flame retardant material, wherein the graphene oxide used in the method is prepared by an improved Hummer method, the obtained graphene has many defects, and cannot be completely reduced, and many strong acids are used in the reaction process, and the strong oxidant and the reducing agent do not meet the requirement of green production. (2) And (3) covalently modifying graphene oxide by using a flame retardant. For example, patent CN201810290541.0 discloses grafting a flame retardant DOPO to graphene oxide, and then performing melt blending and compression molding on the obtained flame retardant modified graphene and polylactic acid to obtain a functionalized graphene flame retardant reinforced polylactic acid composite material. The composite material exhibits good flame retardant properties and thermal stability. On the one hand, the graphene oxide used in the functionalized graphene flame retardant prepared by the method is prepared by adopting an improved Hummer method, the obtained graphene has more defects and can not be completely reduced, and a lot of strong acid, strong oxidant and reducing agent are used in the reaction process; on the other hand, the covalent modification of graphene oxide in an organic solvent system does not meet the requirement of green production. In addition, although the flame retardant performance of the material is improved to a certain extent by introducing graphene at present, different material substrates are different, influence factors of mechanical properties are different, and how to enable the flame retardant performance and the mechanical properties to be compatible is a technical barrier needing important breakthrough. Therefore, the development of a flame retardant functionalized graphene which has the advantages of simple method, low defect, no pollution and no damage to the mechanical property of the composite material is urgently needed in the market.

Disclosure of Invention

According to the invention, the graphite paper is subjected to anodic electrolysis stripping in the flame retardant aqueous solution by an electrochemical method to prepare the flame retardant functionalized graphene with low defect and few layers, and the method is simple, environment-friendly and easy to operate; and then preparing the polyacrylonitrile/graphene nano composite material by using the functionalized graphene flame retardant and polyacrylonitrile by adopting a solution blending method, and researching the thermal stability, the heat release performance and the mechanical property of the composite material.

The invention mainly aims to provide a preparation method of a functionalized graphene flame retardant, which comprises the following steps:

(1) electrolyzing by using an aqueous solution of sodium diethylenetriamine penta-methylene phosphate as an electrolyte, a graphite sheet as an anode and a metal rod as a cathode to obtain the graphene modified by the sodium diethylenetriamine penta-methylene phosphate;

(2) and (2) mixing the graphene modified by the diethylenetriamine penta-methylene sodium phosphate obtained in the step (1) with an iron source to obtain the functionalized graphene flame retardant.

In one embodiment of the present invention, the voltage for electrolysis in the step (1) is 5 to 15V.

In one embodiment of the invention, the concentration of the aqueous solution of sodium diethylenetriamine pentamethylene phosphate in the step (1) is 0.1mol/L to 0.5 mol/L.

In one embodiment of the present invention, the time for electrolysis in the step (1) is 1 to 6 hours.

In one embodiment of the invention, the metal rod comprises a copper rod.

In one embodiment of the invention, the graphite flakes are graphite flakes having a thickness of 0.3mm to 1 mm.

In one embodiment of the invention, the graphite sheet comprises one or more of flake graphite, highly oriented graphite, expanded graphite.

In one embodiment of the invention, the anode and the cathode are placed in parallel at a distance of 1-2 cm.

In one embodiment of the present invention, the step (2) further comprises: and after the electrolysis is finished, filtering and drying to obtain the water-dispersible graphene.

In one embodiment of the invention, the graphene modified by sodium diethylenetriamine pentamethylene phosphate in the step (3) is mixed with 10-20mmol of iron source per 1g of the graphene.

In an embodiment of the invention, the functionalized graphene flame retardant is obtained by mixing, ultrasonic treatment, filtration and drying in the step (3).

In an embodiment of the present invention, the method specifically includes:

(1) preparing an aqueous solution of diethylenetriamine penta (methylene sodium phosphate) with a certain molar concentration;

(2) the graphite flake is an anode, the copper rod is a cathode, the two electrodes are arranged in parallel at a distance of 1-2cm, a certain direct current voltage is applied to electrolyze and strip the graphite flake, and after the electrolysis is finished, the graphite flake is filtered, cleaned and dried to obtain the DTPMPA modified graphene;

(3) mixing the graphene modified by the sodium diethylenetriamine pentamethylene phosphate with an iron source, carrying out ultrasonic treatment for a period of time, filtering, and drying the obtained precipitate to obtain the functionalized graphene flame retardant.

The second purpose of the invention is to provide a functionalized graphene flame retardant, which is prepared by the method.

The third purpose of the invention is to provide a polyacrylonitrile composite material, wherein the composite material comprises the functionalized graphene flame retardant.

In one embodiment of the invention, the polyacrylonitrile composite material is obtained by blending polyacrylonitrile and a functionalized graphene flame retardant through a solution and then drying.

In one embodiment of the invention, the addition amount of the functionalized graphene flame retardant accounts for 1% -5% of the total mass of polyacrylonitrile and the functionalized graphene flame retardant.

The fourth purpose of the invention is to provide a carpet, a tarpaulin or a curtain, wherein the carpet, the tarpaulin or the curtain contains the polyacrylonitrile composite material.

The fifth purpose of the invention is to apply the functionalized graphene flame retardant or the polyacrylonitrile composite material in the field of automotive interior trim or clothing fabric.

The invention has the beneficial effects that:

(1) the number of layers of the graphene prepared by the method is less than 5; while obtaining graphene I_D/I_GThe value is not more than 0.8, and the defects are small.

(2) According to the invention, the phosphorus element, the nitrogen element and the iron element are successfully loaded on the surface of the graphene, so that the functionalized graphene flame retardant is prepared, the synergistic flame retardant effect of the phosphorus-nitrogen flame retardant element and the ferric iron catalyzed carbon formation and the physical barrier of graphene sheets is realized, and the flame retardant efficiency in the matrix is effectively improved.

(3) The functionalized graphene flame-retardant polyacrylonitrile composite material prepared by the invention has good flame-retardant performance and thermal stability. When the addition amount of the functionalized graphene flame retardant is 5%, the maximum heat release rate peak value (PHRR) of the polyacrylonitrile composite material is reduced to 111.2W/g from 172.5W/g, and is reduced by 35.5%; meanwhile, the carbon formation amount after combustion is increased from 46.8% to 50.3%, and the carbon layer becomes compact by SEM representation; meanwhile, the mechanical property of the material is not damaged, and even the material has a lifting effect.

The functionalized graphene flame retardant prepared by the invention improves the flame retardant property of the polyacrylonitrile composite material, and simultaneously, when the addition amount of the flame retardant is 5%, the thermal stability of the composite material is not affected, and simultaneously, the mechanical property of the material is also improved. The obtained composite material has wide application prospect in the fields of automobile interior trim, garment materials, tarpaulin, curtains, carpets and the like.

Drawings

FIG. 1 is a mechanism diagram of electrochemical preparation of a functionalized graphene flame retardant according to the present invention;

figure 2 high power TEM image of functionalized graphene flame retardant;

FIG. 3 is a Raman spectrum of a functionalized graphene flame retardant;

FIG. 4 is an X-ray photoelectron spectrum of a functionalized graphene flame retardant;

FIG. 5 is a micro calorimeter heat release rate curve of polyacrylonitrile/functionalized graphene flame retardant nanocomposite;

FIG. 6 is a thermogravimetric curve of a polyacrylonitrile/functionalized graphene flame retardant nanocomposite material under a nitrogen condition;

FIG. 7 is an SEM image of carbon residue of polyacrylonitrile/functionalized graphene flame retardant nanocomposite material burning at 550 ℃.

Detailed Description

In order to further illustrate the present invention, the electrochemical preparation of the functionalized graphene flame retardant and the polyacrylonitrile nanocomposite material flame-retarded by the same according to the present invention are described in detail below with reference to the examples.

In the following examples, polyacrylonitrile was purchased from believed to be a plastic material, Inc. and had a molecular weight of 220000.

The mechanism schematic diagram of the functionalized graphene flame retardant prepared by the invention is shown in fig. 1.