Preparation method and application of carbon nanotube modified nylon 66 flame retardant composite material

Abstract

This invention relates to the field of nylon 66 technology and discloses a carbon nanotube-modified nylon 66 flame-retardant composite material. The nitrogen element contained in polyacrylamide and maleimide produces non-flammable inert gases such as nitrogen during combustion, diluting the oxygen concentration near nylon 66, blocking the oxygen required for combustion, and promoting the formation of carbon on the nylon 66 matrix. Carbon nanotubes exhibit excellent thermal resistance and gas barrier capabilities. Grafting carbon nanotubes onto flame retardants avoids their aggregation. Introducing monomers containing the flame-retardant element bromine into the polymer chain, with its low C-Br bond energy, effectively provides flame retardancy. Upon heating, it decomposes into flammable hydrogen bromide gas, capturing active free radicals that propagate the combustion chain reaction and slowing down the combustion reaction. The resulting carbon nanotube-modified nylon 66 composite material possesses strong flame-retardant capabilities.

Description

Technical Field

[0001] This invention relates to the field of nylon 66 technology, specifically to a method for preparing and applying carbon nanotube modified nylon 66 flame-retardant composite materials. Background Technology

[0002] With the rapid development of my country's economy and industrialization, the total output of plastic products in my country has greatly increased, ranking second in the world. At the same time, some processing technologies have also reached the world's advanced level. The application rate of engineering plastics in my country has also grown at an average annual rate of 10% with economic development and the improvement of people's quality of life. However, there are still many problems in the actual production and manufacturing process. How to solve these problems and make corresponding improvements and innovations has important practical significance and value.

[0003] Polyhexamethylene adipamide (PHA), a member of the nylon family, is one of the most widely used thermoplastic resins in engineering plastics. It has a wide range of applications and is an excellent engineering plastic with high mechanical strength, wear resistance, and cold resistance. However, it has poor dimensional stability, poor electrochemical properties, poor heat resistance, and is easily combustible. Carbon nanotubes, due to their excellent chemical and thermal stability, unique structure, large specific surface area, and excellent electrochemical properties, can be used to modify nylon 66, which can greatly improve its mechanical properties. At the same time, its good thermal conductivity can quickly dissipate the large amount of heat accumulated inside nylon 66, avoiding local overheating and combustion reactions. Acrylamide decomposes into small molecule gases and low molecular weight polymers during heating, effectively promoting char formation. The nitrogen atoms it contains can also largely block the combustion of nylon 66. Brominated flame retardants have excellent flame retardant properties. The introduction of bromine atoms can largely prevent the combustion of nylon 66, and the resulting composite material exhibits good flame retardant effects.

[0004] (1) Technical problems solved

[0005] To address the shortcomings of existing technologies, this invention provides a carbon nanotube-modified nylon 66 flame-retardant composite material, which solves the problem of poor heat resistance and easy combustion of nylon 66.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a carbon nanotube-modified nylon 66 flame-retardant composite material, wherein the carbon nanotube-modified nylon 66 flame-retardant composite material and its preparation method are as follows:

[0008] (1) Add deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 in a mass ratio of 1200-1800:2000-3000:1.5-3.5:15-30:100 to the reaction flask. Under microwave radiation conditions, microwave radiation is carried out at 65-75℃ for 50-70 min. After the reaction is completed, wash, dry and Soxhlet extract is performed. After extraction, dry to obtain polyacrylamide grafted nylon 66.

[0009] (2) Add N,N-dimethylformamide solvent and carboxylated carbon nanotubes to the reaction flask, disperse them evenly by ultrasonication, add thionyl chloride, heat and stir to carry out the modification reaction, react at 80-100℃ for 18-24h, after the reaction is completed, evaporate by rotary evaporation and dry to obtain acyl chloride modified carbon nanotubes.

[0010] (3) Add dichloromethane solvent, 4-aminothiophenol and pyridine to the reaction flask, stir and mix evenly, then add acyl chloride modified carbon nanotubes dropwise, stir, and undergo amidation reaction at 15-35℃ for 12-24h. After the reaction is completed, distill under reduced pressure, dry, extract, and dry to obtain thiophenol modified carbon nanotubes.

[0011] (4) Add dichloromethane solvent and thiophenol-modified carbon nanotubes to the reaction flask, disperse them evenly by ultrasonication, add N-(2,4,6-tribromophenyl)maleimide and triethylamine, stir and mix, and a mercapto-olefin reaction occurs. React at 20-40℃ for 10-20h. After the reaction is completed, filter, wash and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0012] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide to a high-speed mixer, stir and mix evenly, transfer to a torque rheometer for melt blending, discharge and cool after mixing, process and mold on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0013] Preferably, in step (2), the mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide is 6000-12000:100:250-400.

[0014] Preferably, in step (3), the mass ratio of dichloromethane, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes is 3500-4500:240-420:150-380:100.

[0015] Preferably, in step (4), the mass ratio of dichloromethane, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine is 6500-8000:100:110-140:20-50.

[0016] Preferably, in step (5), the mass ratio of tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and stearamide is 2-6:100:0.5-1.

[0017] Preferably, the melting and blending temperature in step (5) is 220-240℃, and the melting and blending time is 12-20 min.

[0018] (III) Beneficial Technical Effects

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This carbon nanotube-modified nylon 66 flame-retardant composite material undergoes a synthesis process. During microwave irradiation, acrylamide polymerizes under the initiator potassium persulfate. Simultaneously, potassium persulfate induces the generation of active free radicals on the nylon 66 surface, leading to the grafting of polyacrylamide onto the nylon 66. In N,N-dimethylformamide solvent, thionyl chloride is used to acylchlorinate the carboxylated carbon nanotubes, yielding acylchlorinated carbon nanotubes. In dichloromethane solvent, the acyl chloride groups on the acylchlorinated carbon nanotubes and the amino groups on 4-aminobenzenethiophenol undergo amide reaction under the action of pyridine. A chemical reaction was carried out to obtain benzene-thiophenol-modified carbon nanotubes. The thiol groups on the benzene-thiophenol-modified carbon nanotubes and the alkenyl groups on N-(2,4,6-tribromophenyl)maleimide under the action of triethylamine under the action of thiol-alkene click reaction to obtain tribromophenyl carbon nanotube flame retardant. Nitrogen-containing heterocycles and bromine atoms were successfully introduced onto the carbon nanotubes. The tribromophenyl carbon nanotube flame retardant and polyacrylamide-grafted nylon 66 were mixed evenly in a high-speed mixer, melt-mixed in a torque rheometer, and then processed into molding in an injection molding machine to obtain carbon nanotube-modified nylon 66 flame retardant composite material.

[0021] This is a carbon nanotube-modified nylon 66 flame-retardant composite material. Both polyacrylamide and maleimide contain nitrogen (N). During combustion, nitrogen produces non-flammable inert gases such as nitrogen gas, which significantly dilutes the oxygen concentration near nylon 66, blocking the oxygen required for combustion. Simultaneously, nitrogen generates acidic substances during combustion, promoting the formation of a char layer on the nylon 66 matrix and increasing the char residue rate. Together with carbon nanotubes, it exhibits excellent thermal resistance and gas barrier capabilities. Grafting carbon nanotubes onto the flame retardant effectively prevents their aggregation, allowing them to be uniformly dispersed in the nylon 66 matrix. Introducing monomers containing the flame-retardant element bromine into the polymer chain, with its low C-Br bond energy and decomposition temperature similar to that of the polymer material, effectively provides flame retardancy. Upon heating, it decomposes into flammable hydrogen bromide gas, capturing active free radicals that propagate the combustion chain reaction and slowing down the combustion process. The resulting carbon nanotube-modified nylon 66 composite material possesses strong flame-retardant capabilities. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the synthesis of thiophenol-modified carbon nanotubes.

[0023] Figure 2 This is a schematic diagram illustrating the synthesis of tribromophenyl carbon nanotube flame retardant. Detailed Implementation

[0024] To achieve the above objectives, the present invention provides the following specific embodiments and examples: A method for preparing and applying a carbon nanotube-modified nylon 66 flame-retardant composite material is as follows:

[0025] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1200-1800:2000-3000:1.5-3.5:15-30:100. The mixture was then subjected to microwave irradiation at 65-75℃ for 50-70 minutes. After the reaction was completed, the mixture was washed, dried, and subjected to Soxhlet extraction with acetone solvent. After extraction, the mixture was dried to obtain polyacrylamide-grafted nylon 66.

[0026] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 6000-12000:100:250-400. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 80-100℃ for 18-24h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0027] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 3500-4500:240-420:150-380:100 to the reaction flask in sequence, stir, and carry out an amidation reaction at 15-35℃ for 12-24h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0028] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 6500-8000:100:110-140:20-50 to a reaction flask in sequence. Stir and mix to allow the mercapto-olefin reaction to occur. React at 20-40℃ for 10-20 h. After the reaction is complete, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0029] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide to a high-speed mixer in a mass ratio of 2-6:100:0.5-1. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 220-240℃ and the melt blending time is 12-20min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0030] Example 1

[0031] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1200:2000:1.5:15:100. The reaction was carried out at 65°C for 50 min under microwave irradiation conditions. After the reaction was completed, the flask was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the flask was dried to obtain polyacrylamide grafted nylon 66.

[0032] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 6000:100:250. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 80℃ for 18 hours. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0033] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 3500:240:150:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 15°C for 12 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0034] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 6500:100:110:20 to the reaction flask in sequence, stir and mix, and a mercapto-olefin reaction occurs. The reaction is carried out at 20°C for 10 h. After the reaction is completed, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0035] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide in a mass ratio of 2:100:0.5 to a high-speed mixer. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 220℃ and the melt blending time is 12min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0036] Example 2

[0037] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1400:2300:2:18:100. The reaction was carried out at 70°C for 55 min under microwave radiation conditions. After the reaction was completed, the mixture was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the mixture was dried to obtain polyacrylamide-grafted nylon 66.

[0038] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 8000:100:280. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 85°C for 20 h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0039] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 3800:300:220:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 20°C for 15 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0040] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 6800:100:115:25 to the reaction flask in sequence, stir and mix, and a mercapto-olefin reaction occurs. The reaction is carried out at 25°C for 12 hours. After the reaction is completed, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0041] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide in a mass ratio of 3:100:0.6 to a high-speed mixer. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 225℃ and the melt blending time is 14min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0042] Example 3

[0043] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1500:2500:2.5:20:100. The reaction was carried out at 70°C for 60 min under microwave irradiation conditions. After the reaction was completed, the mixture was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the mixture was dried to obtain polyacrylamide-grafted nylon 66.

[0044] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 9000:100:320. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 80-100℃ for 21 h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0045] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 4000:340:280:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 25°C for 18 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0046] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 7200:100:125:35 to the reaction flask in sequence, stir and mix, and a mercapto-olefin reaction occurs. The reaction is carried out at 30°C for 15 h. After the reaction is completed, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0047] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide in a mass ratio of 4:100:0.8 to a high-speed mixer. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 230℃ and the melt blending time is 15min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0048] Example 4

[0049] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1650:2800:3:24:100. The reaction was carried out at 70°C for 65 min under microwave radiation conditions. After the reaction was completed, the mixture was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the mixture was dried to obtain polyacrylamide-grafted nylon 66.

[0050] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After ultrasonic dispersion, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 11000:100:350. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 95℃ for 18-24h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0051] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 4200:380:320:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 30°C for 20 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0052] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 7500:100:132:42 to the reaction flask in sequence, stir and mix, and a mercapto-olefin reaction occurs. The reaction is carried out at 35°C for 18 hours. After the reaction is completed, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0053] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide in a mass ratio of 5:100:0.9 to a high-speed mixer. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 235℃ and the melt blending time is 18min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0054] Example 5

[0055] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1800:3000:3.5:30:100. The reaction was carried out at 75°C for 70 min under microwave irradiation conditions. After the reaction was completed, the flask was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the flask was dried to obtain polyacrylamide grafted nylon 66.

[0056] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 12000:100:400. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 100℃ for 24 h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0057] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 4500:420:380:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 35°C for 24 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0058] (4) Add dichloromethane solvent, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in a mass ratio of 8000:100:140:50 to the reaction flask in sequence, stir and mix, and a mercapto-olefin reaction occurs. The reaction is carried out at 40°C for 20 h. After the reaction is completed, filter, wash with methanol, and dry to obtain tribromophenyl carbon nanotube flame retardant.

[0059] (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and lubricant stearamide in a mass ratio of 6:100:1 to a high-speed mixer. After stirring and mixing evenly, transfer to a torque rheometer for melt blending. The melt blending temperature is 240℃ and the melt blending time is 20min. After mixing, discharge, cool, and process on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

[0060] Comparative Example 1

[0061] (1) Deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 were added to the reaction flask in a mass ratio of 1500:2500:2.5:20:100. The reaction was carried out at 70°C for 60 min under microwave irradiation conditions. After the reaction was completed, the mixture was washed, dried and extracted with acetone solvent using Soxhlet extraction. After the extraction was completed, the mixture was dried to obtain polyacrylamide-grafted nylon 66.

[0062] (2) N,N-dimethylformamide solvent and carboxylated carbon nanotubes were added to the reaction flask in sequence. After being ultrasonically dispersed evenly, sulfoxide was added. The mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide was 9000:100:320. The mixture was heated and stirred to carry out the modification reaction. The reaction was carried out at 90℃ for 20 h. After the reaction was completed, the mixture was rotary evaporated and dried to obtain acyl chloride modified carbon nanotubes.

[0063] (3) Add dichloromethane solvent, 4-aminothiophenol, pyridine and acyl chloride modified carbon nanotubes in a mass ratio of 4000:300:240:100 to the reaction flask in sequence, stir, and undergo amidation reaction at 25°C for 18 h. After the reaction is completed, distill under reduced pressure, dry, extract with dichloromethane, and dry to obtain thiophenol modified carbon nanotubes.

[0064] (4) Add thiophenol-modified carbon nanotubes, polyacrylamide-grafted nylon 66 and stearamide lubricant in a mass ratio of 4:100:0.8 to a high-speed mixer. After stirring and mixing evenly, transfer the mixture to a torque rheometer for melt blending. The melt blending temperature is 230℃ and the melt blending time is 15min. After the mixture is completed, discharge the material, cool it, and process it on an injection molding machine to obtain carbon nanotube-modified nylon 66 composite material.

[0065] The carbon nanotube-modified nylon 66 flame-retardant composite materials synthesized in the examples and comparative examples were cut into pieces with dimensions of 150×58mm. 2 The sample was tested for limiting oxygen index on an XWR-2406 oxygen index meter with an ignition time of 10s and the test standard was GB / T5454-1997.

[0066]

Claims

1. A carbon nanotube-modified nylon 66 flame-retardant composite material, characterized in that: The carbon nanotube-modified nylon 66 flame-retardant composite material and its preparation method are as follows: (1) Add deionized water, N,N-dimethylformamide solvent, potassium persulfate, acrylamide and nylon 66 in a mass ratio of 1200-1800:2000-3000:1.5-3.5:15-30:100 to the reaction flask. Under microwave radiation conditions, microwave radiation is carried out at 65-75℃ for 50-70 min. After the reaction is completed, wash, dry and Soxhlet extract is performed. After extraction, dry to obtain polyacrylamide grafted nylon 66. (2) Add N,N-dimethylformamide solvent and carboxylated carbon nanotubes to the reaction flask, disperse them evenly by ultrasonication, add thionyl chloride, heat and stir to carry out the modification reaction, react at 80-100℃ for 18-24h, after the reaction is completed, evaporate by rotary evaporation and dry to obtain acyl chloride modified carbon nanotubes. (3) Add dichloromethane solvent, 4-aminothiophenol and pyridine to the reaction flask, stir and mix evenly, then add acyl chloride modified carbon nanotubes dropwise, stir, and undergo amidation reaction at 15-35℃ for 12-24h. After the reaction is completed, distill under reduced pressure, dry, extract, and dry to obtain thiophenol modified carbon nanotubes. (4) Add dichloromethane solvent and thiophenol-modified carbon nanotubes to the reaction flask, disperse them evenly by ultrasonication, add N-(2,4,6-tribromophenyl)maleimide and triethylamine, stir and mix, and a mercapto-olefin reaction occurs. React at 20-40℃ for 10-20h. After the reaction is completed, filter, wash and dry to obtain tribromophenyl carbon nanotube flame retardant; the mass ratio of dichloromethane, thiophenol-modified carbon nanotubes, N-(2,4,6-tribromophenyl)maleimide and triethylamine in step (4) is 6500-8000:100:110-140:20-50; (5) Add tribromophenyl carbon nanotube flame retardant, polyacrylamide grafted nylon 66 and lubricant stearamide to a high-speed mixer, stir and mix evenly, transfer to a torque rheometer for melt blending, discharge and cool after mixing, process and mold on an injection molding machine to obtain carbon nanotube modified nylon 66 flame retardant composite material.

2. The carbon nanotube-modified nylon 66 flame-retardant composite material according to claim 1, characterized in that: In step (2), the mass ratio of N,N-dimethylformamide, carboxylated carbon nanotubes and sulfoxide is 6000-12000:100:250-400.

3. The carbon nanotube-modified nylon 66 flame-retardant composite material according to claim 1, characterized in that: In step (3), the mass ratio of dichloromethane, 4-aminobenzylthiophenol, pyridine and acyl chloride modified carbon nanotubes is 3500-4500:240-420:150-380:

100.

4. The carbon nanotube-modified nylon 66 flame-retardant composite material according to claim 1, characterized in that: In step (5), the mass ratio of tribromophenyl carbon nanotube flame retardant, polyacrylamide-grafted nylon 66 and stearamide is 2-6:100:0.5-1.

5. The carbon nanotube-modified nylon 66 flame-retardant composite material according to claim 1, characterized in that: The melting and blending temperature in step (5) is 220-240℃, and the melting and blending time is 12-20min.

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