Graphene for preparing conductive enhanced long carbon chain nylon and preparation method thereof

Abstract

The invention relates to graphene for preparing conductivity-enhanced long carbon chain nylon and a preparation method thereof, and is characterized in that graphite is used as an anode, a platinum sheet is used as a cathode, a eutectic solvent is used as an electrolyte, a stripping process is triggered by applying a dynamic voltage, few-layer graphene is successfully prepared, and the yield is up to 85%. And carrying out suction filtration, collection and drying on the stripped sample to obtain the graphene filler. Graphene is prepared by using a dynamic potential regulation and control technology, the method is efficient and environment-friendly, the obtained graphene filler has good compatibility with nylon and glass fibers, and the graphene reinforced nylon composite material with high conductivity, low hygroscopicity and excellent mechanical properties is developed.

Description

Technical Field

[0001] This invention relates to the field of engineering plastics technology, specifically to a method for preparing graphene for conductive reinforced long carbon chain nylon. Background Technology

[0002] With the rapid development of electronic devices, flexible sensors, and electromagnetic shielding materials, the demand for high-performance conductive polymer composite materials is increasing. Traditional conductive materials (such as metals) often face problems such as high density, poor processability, and difficulty in balancing mechanical properties and conductivity. Nylon, as an important engineering plastic, is widely used in automotive, electronics, and aerospace fields due to its excellent mechanical strength, heat resistance, and chemical stability. However, the insulating properties of ordinary nylons (such as PA6 and PA66) limit their application in conductive scenarios, and the high amide bond density of short-chain nylons easily leads to increased water absorption, further affecting their electrical properties and dimensional stability. Therefore, developing nylon-based composite materials that combine high conductivity, low moisture absorption, and excellent mechanical properties has become a research hotspot.

[0003] In recent years, two-dimensional nanomaterials (such as graphene) have become a research hotspot in the field of conductivity modification due to their high specific surface area, intrinsic conductivity, and mechanical strength. Graphene possesses ultra-high carrier mobility and mechanical strength, which can significantly improve the conductivity and tensile strength of composite materials. Electrochemical liquid-phase exfoliation has great potential for efficient, low-cost, and large-scale preparation of two-dimensional materials. Layered materials are usually used as electrodes or dispersed in an electrolyte, and the layers are exfoliated through the interlayer by the insertion of ions in the electrolyte or the expansion of gas generated by the electrode reaction. Common electrochemical exfoliation techniques include constant voltage exfoliation and alternating frequency exfoliation with positive and negative electrodes. Both are essentially continuous exfoliation under a constant voltage, making it impossible to precisely control the exfoliation rate. Furthermore, graphene is prone to agglomeration due to van der Waals forces, resulting in incompatibility with long-chain nylon interfaces and leading to uneven performance. Therefore, it is particularly important to find a method for precisely controlling the preparation of graphene materials with strong compatibility with nylon substrates. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention aims to provide a method for preparing graphene with conductive reinforced long carbon chain nylon. Based on traditional constant-voltage electrochemical exfoliation, dynamic potential control technology is introduced. By programming, the potential is controlled to change according to a preset curve during the exfoliation process. Initially, a low potential is used for gentle exfoliation to avoid material damage, and then the potential is gradually increased to accelerate the exfoliation process. This method allows for more precise control of the exfoliation rate and material quality, improving production efficiency and product consistency.

[0005] The technical solution of this invention to solve the technical problem is: a method for preparing graphene for conductive reinforced long carbon chain nylon, using graphite as the anode, platinum sheet as the cathode, and eutectic solvent as the electrolyte. By applying a dynamic voltage to trigger the exfoliation process, few-layer (3-5 layers) graphene is successfully prepared with a yield as high as 85%. The exfoliated sample is filtered, collected, and dried to obtain graphene filler.

[0006] According to GB / T 30544.13—2018 and ISO / TS 80004-13:2020 standards, few-layer graphene is a two-dimensional carbon material composed of 3-10 complete graphene layers stacked together. Preferably, the dynamic voltage design three-step potential program is as follows: initial activation at 1-3 V for 20-40 min, followed by a ramp to 8-12 V at a slope of 40-60 mV / s, and finally stabilization at 8-12 V for 1.5-2.5 h.

[0007] Preferably, the dynamic voltage design three-step potential program is as follows: initial activation at 2 V for 30 min, followed by ramping up to 10 V at a slope of 50 mV / s, and finally stabilizing at 10 V for 2 h.

[0008] Preferably, the eutectic solvent includes, but is not limited to, one or more of quaternary ammonium salts-decanoic acid and menthol-organic carboxylic acids.

[0009] Preferably, the graphite includes, but is not limited to, one or more of microcrystalline graphite, flake graphite, and expanded graphite.

[0010] Graphene prepared by the method described in claims 1-5.

[0011] Application of graphene prepared by the method described in claims 1-5 in the preparation of long-chain nylon composite materials.

[0012] The initial activation stage employs a low potential for gentle exfoliation. The main objective of this stage is to ensure the electrolyte fully wets the interlayer of the material while establishing a stable double-layer structure, laying the foundation for subsequent exfoliation. An excessively high initial potential can lead to irreversible damage to the material's edge structure, significantly reducing the quality of the final product. The intermediate acceleration stage uses a linear increase in potential to gradually increase the exfoliation rate. The slope of the potential change in this stage needs precise control; an excessively large slope can lead to runaway reaction, while an excessively small slope will affect production efficiency. The final stabilization stage maintains a relatively constant high potential for continuous exfoliation to prepare graphene.

[0013] The exfoliation mechanism is as follows: First, DES rapidly inserts into the interlayer when energized, effectively weakening the interlayer van der Waals forces. Second, the interlayer DES is electrolyzed, generating gas that causes interlayer expansion, triggering the exfoliation of the material and the intercalation of more DES. These two steps continue, ultimately yielding graphene material. The prepared graphene material has a layer of DES attached to its surface, containing polar functional groups such as hydroxyl groups, giving it excellent compatibility with both nylon materials and activated glass fibers.

[0014] Furthermore, the present invention provides a conductive long-chain nylon composite material. Graphene, long-chain nylon, glass fiber, and other additives are thoroughly mixed in a high-speed mixer according to parts by weight to obtain a premix, which is then fed into a twin-screw extruder for compounding, melting, homogenization, and extrusion granulation to obtain the conductive long-chain nylon composite material.

[0015] The dynamic potential control technology employed in this invention is a more precise and intelligent material preparation method compared to traditional constant-voltage electrochemical exfoliation. The potential of the working electrode changes over time according to a pre-designed curve, thereby achieving precise control over the electrochemical exfoliation process. The exfoliated graphene and glass fiber are added as fillers to long-chain nylon, resulting in a conductive reinforced long-chain nylon composite material that exhibits high conductivity, low moisture absorption, and excellent mechanical properties, making it promising for applications in the automotive, electronics, and aerospace industries. Detailed Implementation

[0016] To further illustrate the present invention, specific embodiments are provided below. It should be understood that these embodiments are only for aiding understanding of the present invention and do not constitute a limitation on the scope of the invention. Furthermore, it should be understood that after studying the content of this invention, those skilled in the art can make various improvements or adjustments, and these modifications should also be considered within the protection scope of this invention.

[0017] Before introducing specific embodiments of the present invention, it should be clarified that the scope of protection of the present invention is not limited to the specific embodiments described below. Furthermore, the terminology used in this invention is for the convenience of describing specific embodiments and is not intended to limit the scope of the invention. Unless otherwise defined, all technical terms in this invention should be interpreted in accordance with the common understanding of those skilled in the art. For experimental methods not specifically listed in the embodiments, they should generally be operated under conventional conditions or the recommended conditions of the equipment manufacturer. In addition to the specific methods, equipment, and materials used in the embodiments, the present invention can also be implemented using existing technical solutions that are similar to or equivalent to the methods, equipment, and materials described in the embodiments.

[0018] Example 1 A method for preparing graphene for use in the fabrication of conductive reinforced long-chain nylon: Microcrystalline graphite was used as the anode, platinum sheet as the cathode, and choline chloride-decanoic acid as the electrolyte. The exfoliation process was triggered by applying a dynamic voltage. A three-step potential program was designed: initial activation at 2 V for 30 min, followed by a ramp to 10 V at a slope of 50 mV / s, and finally stabilization at 10 V for 2.5 h. This successfully prepared 3-5 layers of graphene with a yield as high as 85%. The exfoliated samples were filtered, collected, and dried to obtain the graphene filler.

[0019] Example 2 A method for preparing graphene for use in the fabrication of conductive reinforced long-chain nylon: Using flake graphite as the anode, platinum sheet as the cathode, and menthol-acetic acid as the electrolyte, the exfoliation process was triggered by applying a dynamic voltage. A three-step potential program was designed: initial activation at 1 V for 40 min, followed by a ramp to 12 V at a slope of 60 mV / s, and finally stabilization at 12 V for 1.5 h, successfully preparing 3-5 layers of graphene with a yield as high as 85%. The exfoliated sample was filtered, collected, and dried to obtain the graphene filler.

[0020] Example 3 A method for preparing graphene for use in the fabrication of conductive reinforced long-chain nylon: Expanded graphite was used as the anode, platinum sheet as the cathode, and tetrabutylammonium chloride-decanoic acid as the electrolyte. The exfoliation process was triggered by applying a dynamic voltage. A three-step potential program was designed: initial activation at 3 V for 20 min, followed by a ramp to 8 V at a slope of 40 mV / s, and finally stabilization at 8 V for 2 h. This successfully prepared 3-5 layers of graphene with a yield as high as 85%. The exfoliated samples were filtered, collected, and dried to obtain graphene filler.

[0021] Example 4 A method for preparing graphene for use in the fabrication of conductive reinforced long-chain nylon: Using microcrystalline graphite as the anode, platinum sheet as the cathode, and choline chloride-decanoic acid as the electrolyte, the exfoliation process was triggered by applying a dynamic voltage. A three-step potential program was designed: initial activation at 2 V for 30 min, followed by a ramp to 10 V at a slope of 50 mV / s, and finally stabilization at 10 V for 2 h, successfully preparing 3-5 layers of graphene with a yield as high as 85%. The exfoliated sample was filtered, collected, and dried to obtain the graphene filler.

[0022] Comparative Example 1 Graphite was used as the anode, platinum sheet as the cathode, and eutectic solvent (DES) as the electrolyte. The exfoliation process was triggered by applying a constant low voltage of 2 V for 2.5 h. The exfoliated sample was filtered, collected, and dried to obtain graphene-2 ​​filler.

[0023] Comparative Example 2 Graphite was used as the anode, platinum sheet as the cathode, and eutectic solvent (DES) as the electrolyte. The exfoliation process was triggered by applying a constant high voltage of 10 V for 2.5 h. The exfoliated sample was then filtered, collected, and dried to obtain graphene-3 filler.

[0024] The preparation method of conductive long-chain carbon nylon composite material is as follows: According to the weight proportions listed in Table 1, each component is thoroughly mixed in a high-speed mixer to obtain a premix, which is then fed into a twin-screw extruder for mixing, melting, homogenization, and extrusion granulation. The extrusion granulation temperature is 180-230℃ and the screw speed is 400-600rpm to obtain a conductive long carbon chain nylon composite material.

[0025] Water absorption test: After the sample is saturated with water for 72 hours, it is tested according to GB / T 1034-2008. The sample is a round piece with a diameter of 50 mm and a thickness of 3 mm.

[0026] Surface resistance test: The surface resistance of the material is tested using a digital high resistance meter according to GB / T 1410-2006. The lower the surface resistance, the better the conductivity.

[0027] Table 1. Results of Formulation and Material Performance Testing

[0028] The additives listed in the table are: hindered phenolic antioxidant 1098, phosphite antioxidant 168, and vinyl bis-stearamide lubricant, with a weight ratio of 0.5:0.5:1.

[0029] The graphene-1 described in Table 1 was prepared using the method described in Example 1.

[0030] According to the data in Table 1, the graphene-1 prepared by the dynamically controlled exfoliation method in groups 1-3 shows a significant contrast with that in groups 4-7. The surface resistivity of the conductive reinforced long-chain nylon composites in groups 1-3 is the lowest, reaching 10 Ω·cm. 5The surface resistance of graphene-1 is significantly lower than that of graphene-2 ​​(10¹³Ω) in group 4, demonstrating that dynamic potential control can significantly improve conductivity. Compared with groups 6 and 7 (graphene-2 ​​and graphene-3 prepared by constant low voltage 2V and constant high voltage 10V respectively), groups 1-3 have lower surface resistance, indicating that the dynamic potential control technology precisely controls the exfoliation rate through a three-step potential program, avoiding material damage or agglomeration problems caused by the constant voltage method. Furthermore, the water absorption rate of groups 1-3 is stable at 0.2%, significantly better than group 5 (1.8%), indicating that the synergistic effect of long-chain nylon substrate and dynamically controlled graphene-1 can effectively reduce hygroscopicity, which is beneficial for applications in precision electronics. In summary, graphene-1 prepared by the dynamic potential control method is superior to the traditional constant voltage method in terms of conductivity, material compatibility, and process stability, providing key technical support for high-performance conductive nylon composite materials.

[0031] The preferred embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method of preparing graphene for the preparation of electrically conductive reinforced long carbon chain nylon, characterized by: Graphite is used as anode, platinum plate is used as cathode, and eutectic solvent is used as electrolyte. The exfoliation process is triggered by applying dynamic voltage, and few-layer graphene is successfully prepared. The exfoliated sample is subjected to suction filtration, collection and drying to obtain graphene filler.

2. The method of claim 1, wherein the method of preparing graphene for preparing electrically conductive reinforced long carbon chain nylon is characterized by: The dynamic voltage is designed with a three-step potential program, i.e. 1-3 V initial activation for 20-40 min, then rising to 8-12 V at a slope of 40-60 mV / s, and finally maintaining at 8-12 V for 1.5-2.5 h.

3. The method of claim 2, wherein the method is characterized by: The dynamic voltage is designed with a three-step potential program, i.e. 2 V initial activation for 30 min, then rising to 10 V at a slope of 50 mV / s, and finally maintaining at 10 V for 2 h.

4. The method of claim 1, wherein the method is characterized by: The eutectic solvent includes but is not limited to one or more of quaternary ammonium salt-n-decanoic acid type, menthol-organic carboxylic acid type.

5. The method of claim 1, wherein the method is characterized by: The graphite includes but is not limited to one or more of microcrystalline graphite, flake graphite, expanded graphite.

6. Graphene prepared by the method of claims 1-5.

7. Use of graphene prepared by the method of claims 1-5 in the preparation of long carbon chain nylon composite material.

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