CN114539774B - Insulating and heat-conducting polyphenylene sulfide/carbon fiber composite material and preparation method thereof - Google Patents

Abstract

The invention provides an insulating heat-conducting polyphenylene sulfide/carbon fiber composite material and a preparation method thereof, wherein the insulating heat-conducting polyphenylene sulfide/carbon fiber composite material comprises the following raw materials: the modified carbon fiber is obtained by performing plasma treatment on the carbon fiber in an ammonia atmosphere, then soaking the carbon fiber in ammonia water, and finally grafting ferrocenecarboxaldehyde and fluorine-containing aldehyde on the surface; during graft modification, the mol ratio of the ferrocene formaldehyde to the fluorine-containing aldehyde is 10: 1-1.7. The polyphenylene sulfide/carbon fiber composite material prepared by the invention has improved thermal conductivity, mechanical strength and insulativity, and the composite material has good weather resistance. And the amino groups on the surface of the carbon fiber with aminated surface are uniformly distributed, and then grafted and modified, so that the distribution of the grafted groups is more uniform, the uniform heat conductivity of the composite material is favorably improved, and the application of the composite material in electronic components is more favorably realized.

Description

Insulating and heat-conducting polyphenylene sulfide/carbon fiber composite material and preparation method thereof

Technical Field

The invention belongs to the technical field of polyphenylene sulfide composite materials, and particularly relates to an insulating heat-conducting polyphenylene sulfide/carbon fiber composite material and a preparation method thereof.

Background

Polyphenylene Sulfide (PPS) is a rigid main chain formed by alternately arranging benzene rings and sulfur atoms, a large number of benzene rings on the main chain endow the PPS macromolecules with good rigidity, the sulfur atoms enable the PPS macromolecules to have certain flexibility, and the existence of a large pi bond on the structure enables the PPS performance to be very stable. Polyphenylene sulfide is widely used in various fields due to its excellent heat resistance, flame retardancy, dielectric properties, dimensional stability, chemical resistance and electron irradiation resistance, and is most commonly used in electronic and electrical products in daily life, such as high-voltage components, housings, sockets and terminals of televisions and computers, starting coils and blades of motors, brush holders and rotor insulation parts, contact switches, relays, electric irons, hair dryers, lamp holders, fan heaters, F-stage films and the like.

At present, the development trend of electronic components is integration and miniaturization, and the power density of the electronic components is higher and higher, so that the heat-conducting property of the polyphenylene sulfide material needs to be further improved. At present, in order to further improve the heat conductivity and mechanical properties of polyphenylene sulfide in the prior art, some functional fillers are often added, wherein carbon fibers are the most widely used materials. The carbon fiber has the advantages of light weight, large specific strength, high modulus, good thermal conductivity and good chemical stability, and can improve the thermal conductivity and mechanical strength of the polyphenylene sulfide. Polyphenylene sulfide/carbon fiber composites have been developed in great quantities in recent years. However, the interface affinity of the carbon fiber and the polyphenylene sulfide is poor, the surface inertness of the carbon fiber and the polyphenylene sulfide is very strong, the interface bonding of the carbon fiber and the PPS resin is very weak, the interface often becomes a stress concentration area of the composite material, the interface is a weak point of the whole composite material, and the application of the PPS material is limited.

How to improve the interface bonding force of carbon fiber and PPS is a hot point for researching polyphenylene sulfide/carbon fiber composite materials. The prior art generally adopts a method of modifying carbon fibers so as to improve the interface performance of the composite material. The existing methods for modifying carbon fibers mainly comprise plasma modification, coupling agent grafting, surface coating, electrochemical deposition and other methods. The carbon fiber modification method which is most widely applied at present is to firstly carry out plasma surface treatment on carbon fibers or use an interface modifier to enable the surfaces of the carbon fibers to have some chemical active groups, then carry out graft reaction with a coupling agent to obtain modified carbon fibers, and then prepare a composite material together with PPS. Such as methods reported in CN202110420484.5, CN202110869288.6, CN202111368686.6, CN202110648741.0, CN 201811232542.6. However, although these methods can improve the compatibility between the fiber and the polyphenylene sulfide, since a large interface is formed between the polyphenylene sulfide and a large amount of carbon fibers, phonon scattering is increased, and phonon propagation is seriously hindered, that is, the function of the carbon fibers to improve the thermal conductivity is not fully exerted, and the thermal conductivity of the polyphenylene sulfide composite material is not fully improved. The weather resistance of the composite material obtained by the method needs to be improved, and the interface bonding force of the carbon fiber and the PPS resin is weakened under a high-temperature and high-humidity environment, so that the performance is deteriorated.

The inventor of the prior patent CN2022103810170 adopts an ammonia plasma surface modification technology to enable the surface of carbon fiber to have rich active groups such as amino groups, and then the carbon fiber is grafted and reacted with ferrocene formaldehyde to obtain the modified carbon fiber which is used for preparing a composite material with PPS. The heat conductivity and the mechanical strength of the composite material can be obviously improved, and the weather resistance of the composite material is also improved. However, after grafting of ferrocene formaldehyde, due to the abundant conjugated structure on the surface, the conductivity of the composite material is improved, the insulating property is reduced, and the application in some fields strictly requiring insulating property is limited. In addition, when the carbon fiber surface is subjected to plasma treatment, the distribution of amino groups on the carbon fiber surface is not uniform enough, so that the local amino group content on the carbon fiber surface is high, and the local amino group content is low, which easily causes the situation that the difference between the in-plane thermal conductivity and the thickness thermal conductivity of the material is large, so that the thermal conductivity of the material in some directions is much better than that in other directions, which may cause heat concentration, and particularly, the PPS composite material for miniature electronic components can cause adverse effects.

Disclosure of Invention

In order to solve the problem that the comprehensive performance of the polyphenylene sulfide/carbon fiber composite material in the prior art in insulation property, heat conductivity, mechanical property and weather resistance needs to be further improved, the invention provides an insulating heat-conducting polyphenylene sulfide/carbon fiber composite material and a preparation method thereof. The invention is realized by the following technical scheme:

the invention firstly provides an insulating heat-conducting polyphenylene sulfide/carbon fiber composite material, which comprises the following raw materials: the carbon fiber is subjected to plasma treatment in an ammonia atmosphere, then is immersed in ammonia water, and finally is grafted with ferrocenecarboxaldehyde and fluorine-containing aldehyde on the surface to obtain the modified carbon fiber.

Further, the mass ratio of the polyphenylene sulfide to the modified carbon fiber is 100: 20-40 parts of; further, the polyphenylene sulfide has a weight average molecular weight of 2-6 ten thousand; the carbon fiber is PAN chopped carbon fiber, the diameter of the carbon fiber is 1-20 mu m, and the length of the carbon fiber is 0.5-10 mm.

Furthermore, the carbon atom of the fluorine-containing aldehyde is 2-6, and the fluorine atom is more than or equal to 3. In a preferred embodiment of the present invention, the fluorine-containing aldehyde is at least one selected from pentafluoropropionaldehyde, 3,3, 3-trifluoropropionaldehyde, 2,2, 2-trifluoroacetaldehyde, 4,4, 4-trifluorobutanal, heptafluorobutanal, 3,3,4,4,5,5, 5-heptafluorovaleraldehyde, nonafluorovaleraldehyde, and 2,2,3,3,4,4,5, 5-octafluorovaleraldehyde.

Further, during graft modification, the molar ratio of the ferrocene formaldehyde to the fluorine-containing aldehyde is 10: 1-1.7, wherein the mass ratio of the total dosage of the ferrocenecarboxaldehyde and the fluorine-containing aldehyde to the carbon fiber is 0.17-0.25: 1, the grafting rate of the modified carbon fiber after grafting is 11.5-16.4%.

The inventor unexpectedly finds that after the obtained grafting modified carbon fiber is compounded with PPS (polyphenylene sulfide) by using ferrocene formaldehyde and fluorine-containing aldehyde compounded in a certain proportion and reacting with amino on the surface of the carbon fiber through Schiff base, the thermal conductivity and the mechanical strength of the composite material can be improved, and meanwhile, the resistivity cannot be obviously increased. The defects that although the thermal conductivity and the mechanical property of the composite material are improved by modifying the carbon fibers in the prior patent of the inventor, the insulativity is correspondingly poor are overcome.

The invention relates to a treatment method for amination of the surface of carbon fiber, which comprises the steps of firstly carrying out low-temperature plasma surface treatment under ammonia gas and then soaking in ammonia water. Specifically, plasma treatment is carried out in an ammonia atmosphere, and low-temperature plasma is used for treating the surface of the carbon fiber by using an ammonia discharge medium; more specifically, the flow rate of ammonia gas is 30-50mL/min, the pressure in the low-temperature plasma reaction chamber is 30-100Pa, the speed of the carbon fiber passing through the low-temperature plasma emission device is 50-100m/h, the distance between the carbon fiber and the low-temperature plasma emission device is 20-50mm, the plasma emission power is 100-900W/beam, the treatment temperature is 10-20 ℃, and the treatment time is 1-5 min. The concentration of the ammonia water is 10-15wt%, and the dipping time is 5-10 s.

After the plasma treatment, the carbon fiber surface has abundant amino groups which can be used for further chemical grafting modification, but the amino group distribution is not uniform enough, so that the subsequent chemical grafting is not uniform enough. The carbon fiber treated by ammonia low-temperature plasma is quickly immersed in ammonia water, so that the distribution condition of amino on the surface of the carbon fiber can be improved, the distribution of the modified carbon fiber grafted aldehyde group is more uniform, the difference between the in-plane thermal conductivity and the thickness thermal conductivity can be finally reduced, and the thermal conductivity of the obtained polyphenylene sulfide/carbon fiber material is more uniform.

Further, the modified carbon fiber is obtained by a preparation method comprising the following steps:

s1) carrying out ultrasonic cleaning on the carbon fiber, carrying out vacuum drying, then treating the surface of the carbon fiber by using low-temperature plasma with ammonia gas as a discharge medium, soaking the treated carbon fiber in ammonia water for 5-10S, washing, and drying for later use;

s2) ultrasonically dispersing the surface-treated carbon fiber and the dehydrating agent obtained in the step S1 in an organic solvent, heating to a reflux state, dropwise adding a solution containing ferrocene formaldehyde and fluorine-containing aldehyde, reacting at a constant temperature after dropwise adding, naturally cooling to room temperature, filtering, washing and drying to obtain the carbon fiber and the dehydrating agent.

Further, the ultrasonic cleaning solvent in step S1) includes one or two of deionized water and ethanol; in the low-temperature plasma treatment process, the flow of the ammonia gas is 30-50mL/min, the pressure in the low-temperature plasma reaction chamber is 30-100Pa, the speed of the carbon fiber passing through the low-temperature plasma emission device is 50-100m/h, the distance of the carbon fiber from the low-temperature plasma emission device is 20-50mm, the plasma emission power is 100-900W/beam, the treatment temperature is 10-20 ℃, and the treatment time is 1-5 min. The concentration of the ammonia water is 10-15wt%, and the dipping time is 5-10 s.

The flow rate of ammonia gas is too small, or the plasma treatment time is too short, so that the number of amino groups on the surface of the carbon fiber is insufficient, and the subsequent grafting efficiency of ferrocene formaldehyde and ferrocene formaldehyde is influenced; the flow rate of ammonia is not easy to be overlarge, the treatment time is not easy to be overlong, otherwise, the number of amino groups on the surface of the carbon fiber is too large, and the resistivity of the composite material is influenced. The ammonia water concentration is too low, or the dipping time is too short, so that the aim of more uniformly distributing amino groups on the surface of the carbon fiber cannot be fulfilled; the ammonia concentration is too low, or the dipping time is too long, which cannot further improve the dispersion degree of amino, so in the ammonia dipping operation of the invention, the ammonia concentration is 10-15wt%, and the dipping time is 5-10 s.

Further, in step S2), the dewatering machine is selected from one or a combination of two or more of calcium oxide, sodium sulfate and magnesium sulfate, and the amount of the dewatering agent is 10-20wt% of the carbon fiber; the organic solvent and the solvent in the solution of ferrocene carboxaldehyde and fluoroaldehyde are selected from at least one of benzene, petroleum ether and tetrahydrofuran. Preferably, the organic solvent used for dispersing the carbon fibers and the dehydrating agent is the same as the organic solvent used for dissolving ferrocenecarboxaldehyde and the fluorine-containing aldehyde. In the step S2), the reaction temperature is 60-80 ℃, and the reaction time is 6-10 h.

Furthermore, the raw materials of the insulating and heat conducting polyphenylene sulfide/carbon fiber composite material also comprise auxiliary materials, such as an antioxidant, a toughening agent, a lubricant, a compatilizer and the like. The selection and the dosage of the auxiliary materials are well known in the art, such as antioxidant which accounts for 1 to 5 weight percent of the mass of the polyphenylene sulfide, lubricant which accounts for 0.5 to 3 weight percent of the mass of the polyphenylene sulfide and toughening agent which accounts for 0 to 5 weight percent of the mass of the polyphenylene sulfide are added. The antioxidant is selected from at least one of phosphite esters, phenols and amine antioxidants; the lubricant is selected from at least one of fatty acid, ethylene bis stearamide and pentaerythritol tetrastearate, and the flexibilizer is selected from at least one of nylon flexibilizers, such as nylon 6, nylon 65 and nylon 66.

The second purpose of the invention is to provide a preparation method of the insulating and heat-conducting polyphenylene sulfide/carbon fiber composite material, which comprises the following steps:

1) and uniformly mixing the polyphenylene sulfide and the modified carbon fiber. Optionally, adding auxiliary materials;

2) extruding and granulating the mixture obtained in the step 1) in a double-screw extruder to obtain the insulating heat-conducting polyphenylene sulfide/carbon fiber composite material.

Further, the extrusion temperature of the twin-screw extruder in the step 2) is 265-.

Compared with the prior art, the principle and the beneficial effect of the invention are explained as follows:

the polyphenylene sulfide/carbon fiber composite material prepared by the invention is prepared by carrying out plasma surface treatment and ammonia water impregnation on carbon fibers in an ammonia gas atmosphere, carrying out uniform surface amination treatment on the carbon fibers, and then carrying out graft modification on the carbon fibers with ferrocene formaldehyde and fluorine-containing aldehyde, wherein the dosage of the aldehyde is controlled so that the grafting rate of the graft-modified carbon fibers is 11.5-16.4%. The surface modification of the carbon fiber greatly improves the interface bonding force of the carbon fiber and the polyphenylene sulfide resin, the interface between the carbon fiber and the polyphenylene sulfide base material is fuzzy, the interface phonon scattering is weakened, phonon propagation is facilitated, on the other hand, the delocalized pi bond of the ferrocene structure and the large pi bond of the polyphenylene sulfide attract each other to generate resonance, the phonon heat conduction channel between the interfaces is continuous, the heat transmission is further improved, and the heat conductivity is further improved. Meanwhile, the composite material has excellent weather resistance, and the thermal conductivity and the mechanical property are not reduced under the high-temperature and high-humidity condition.

Secondly, by introducing fluorine-containing aldehyde, on one hand, the grafting density of the ferrocenecarboxaldehyde on the surface of the carbon fiber is reduced, and the influence of the ferrocenecarboxaldehyde on the insulating property is weakened; on the other hand, a conductive path formed by lapping carbon fibers is blocked, and the conductivity of the composite material is reduced, so that the insulation property of the polyphenylene sulfide/carbon fiber composite material obtained by the invention is improved. In addition, the introduction of the fluorine-containing aldehyde further improves the high-temperature high-humidity weather resistance of the composite material.

And thirdly, after the carbon fiber is treated by the plasma, the carbon fiber is also soaked in ammonia water, so that the amino groups are more uniformly distributed on the surface of the carbon fiber, and the defect of heat accumulation caused by nonuniform heat conduction and transmission due to partial failure of grafting of the grafted and modified carbon fiber is overcome.

Detailed Description

The present invention will be further described with reference to the following examples, but the present invention is not limited to the descriptions in the following. Unless otherwise specified, "parts" in the examples of the present invention are all parts by weight. All reagents used are commercially available in the art.

Polyphenylene sulfide was purchased from Jiangxi PolyZhen science and technology development Co., Ltd, and had a weight average molecular weight of 4.3 ten thousand.

PAN carbon fiber is purchased from Sangxin carbon fiber Limited of Jilin city, and has the length of 6mm and the diameter of 5 mu m.

Surface resistivity: testing by referring to a GB/T1410-2006 solid insulating material volume resistivity and surface resistivity test method;

coefficient of thermal conductivity: the thermal conductivity of the composite material was tested with reference to the standard GB/T22588-2008.

Preparation of modified carbon fiber

Testing the grafting rate of the modified carbon fiber: weighing mass M of carbon fiber before modification₀And mass M of modified carbon fiber after grafting ferrocene carboxaldehyde₁The grafting ratio G was calculated with reference to the following formula:

G=（M₁-M₀）/M₀×100%。

preparation examplePreparation of modified carbon fiber

Preparation example 1

S1) in an ultrasonic cleaning container, performing ultrasonic cleaning on 100 parts of carbon fiber by using deionized water, performing vacuum drying for 2h at 60 ℃, then using ammonia gas as a discharge medium, and treating the surface of the carbon fiber by using low-temperature plasma, wherein the flow rate of the ammonia gas is 30mL/min, the pressure in a low-temperature plasma reaction chamber is 30Pa, the distance between the carbon fiber and a low-temperature plasma emission device is 20mm, the speed of the carbon fiber passing through the emission device is 60m/h, the emission power of the plasma is 100W/beam, the treatment temperature is 10 ℃, and the treatment time is 2 min;

s2) soaking the carbon fiber with the surface treated by the plasma obtained in the step S1) in 10wt% ammonia water for 5S, taking out, washing to be neutral by deionized water, and vacuum drying for 2h at 60 ℃;

s3) ultrasonically dispersing the surface-treated carbon fiber obtained in the step S2) and 10 parts of calcium oxide powder (with the particle size of 100nm) in 300 parts of benzene, and heating to a reflux state; and dropwise adding a mixed aldehyde solution, wherein the mixed aldehyde solution is prepared by dissolving 17 parts of total amount of ferrocenecarboxaldehyde and 3,3, 3-trifluoropropionaldehyde in benzene according to a molar ratio of 10:1.5, preparing 300 parts of mixed aldehyde benzene solution, and maintaining a reflux state to continue reacting for 10 hours after dropwise adding is completed within 2 hours. Cooling to room temperature, carrying out suction filtration, alternately washing with ethanol and water for three times, and carrying out vacuum drying to obtain the modified carbon fiber, wherein the grafting rate is 11.5% in a test.

Preparation example 2

The same as preparation example 1 except that, in step (S3), 25 parts of ferrocenecarboxaldehyde and 4,4, 4-trifluorobutanal in a molar ratio of 10:1.7 were dissolved in benzene to give 300 parts in total of a benzene solution of the mixed aldehydes. The grafting rate of the finally obtained modified carbon fiber is 16.1 percent.

Preparation example 3

The same as in production example 2 except that the carbon fiber was immersed in the ammonia water for 10 seconds in step (S2). The grafting rate of the finally obtained modified carbon fiber is 16.4%.

Preparation example 4

The same as preparation example 1 except that, in step (S3), 30 parts of a mixed aldehyde of ferrocenecarboxaldehyde and 3,3, 3-trifluoropropionaldehyde were dissolved in benzene at a molar ratio of 10:1. The grafting ratio of the finally obtained modified carbon fiber is 19.5 percent.

Preparation example 5

The same as preparation example 1 except that, in step (S3), 15 parts of a mixed aldehyde of ferrocenecarboxaldehyde and 3,3, 3-trifluoropropionaldehyde were dissolved in benzene at a molar ratio of 10: 1.5. The grafting rate of the finally obtained modified carbon fiber is 10.4 percent.

Preparation example 6

The same as preparation example 3 except that, in step (S3), the mixed aldehyde was mixed aldehyde in which 25 parts of ferrocenecarboxaldehyde and 4,4, 4-trifluorobutanal were dissolved in benzene in a molar ratio of 10:0.7 to obtain a total of 300 parts of a benzene solution of the mixed aldehyde. The grafting rate of the finally obtained modified carbon fiber is 16.3 percent.

Preparation example 7

The same as preparation example 3 except that, in step (S3), the mixed aldehyde was mixed aldehyde in which 25 parts of ferrocenecarboxaldehyde and 4,4, 4-trifluorobutanal were dissolved in benzene at a molar ratio of 10:2 to obtain a total of 300 parts of a benzene solution of the mixed aldehyde. The grafting rate of the finally obtained modified carbon fiber is 16.4 percent.

Preparation example 8

The same as in production example 1 except that the step (S2) was not performed, that is, the treatment of impregnating aqueous ammonia was not performed.

Comparative preparation example 1

The procedure was repeated except that 3,3, 3-trifluoropropionaldehyde was not added in step (S3), and the amount of ferrocenecarboxaldehyde used was 17 parts.

Example 1

1) 100 parts of polyphenylene sulfide, 40 parts of the modified carbon fiber of preparation example 1, 2.5 parts of antioxidant 1010 and 1 part of pentaerythritol tetrastearate are mixed uniformly;

2) extruding and granulating the mixture obtained in the step 2) in a double-screw extruder to obtain the heat-conducting polyphenylene sulfide composite material;

wherein the extrusion temperature of the double-screw extruder is 275 ℃, 285 ℃, 295 ℃, the head temperature is 310 ℃, the diameter of the screw is 65mm, the length-diameter ratio is 40:1, and the rotating speed of the screw is 350 rpm.

Examples 2 to 8

The rest was the same as example 1 except that modified carbon fibers were prepared for preparation examples 2 to 6, respectively.

Example 9

The procedure of example 1 was repeated except that the modified carbon fiber prepared in production example 1 was used in an amount of 20 parts.

Comparative example 1

The same as example 1 except that carbon fiber was prepared for comparative preparation example 1.

Comparative example 2

The rest is the same as example 1 except that the carbon fiber is not subjected to any treatment.

Effects of the invention

The polyphenylene sulfide composite materials prepared in the above examples and comparative examples were subjected to the following performance tests, and the results are shown in table 1:

testing the surface resistivity by reference to GB/T1410-2006;

the thermal conductivity coefficient of the composite material is tested according to the standard GB/T22588-2008;

the tensile strength is tested with reference to GB/T1040.2-2006;

high temperature and high humidity resistance: the test temperature is 85 ℃, the test temperature is 85 ℃ and the test temperature is 85RH percent, the test temperature is 30 days, the heat conductivity coefficient and the mechanical strength are retested, and the heat conductivity coefficient retention rate and the mechanical strength retention rate are calculated.

TABLE 1 Performance data for polyphenylene sulfide composites

The polyphenylene sulfide/carbon fiber composite material prepared by the invention has the advantages of improved thermal conductivity, mechanical strength and insulativity, good weather resistance, and small reduction of thermal conductivity and mechanical strength after long-time high-temperature and high-humidity treatment. However, the composite material of carbon fiber and polyphenylene sulfide which is not grafted and modified by the invention has poor weather resistance, and the performance is reduced to some extent under the conditions of high temperature and high humidity, thereby limiting the application of the composite material. In addition, the carbon fiber is pretreated, namely the carbon fiber is subjected to plasma surface treatment in an ammonia atmosphere and then is immersed in ammonia water, so that the amino groups on the surface of the carbon fiber with aminated surface are distributed more uniformly, and then grafting modification is carried out, the distribution of grafting groups is more uniform, the difference of the in-plane thermal conductivity and the thickness thermal conductivity of the material is reduced, and the application of the composite material in electronic components is facilitated.

Claims (10)

1. The insulating and heat-conducting polyphenylene sulfide/carbon fiber composite material is characterized by comprising the following raw materials: the modified carbon fiber is obtained by performing plasma treatment on the carbon fiber in an ammonia atmosphere, then soaking the carbon fiber in ammonia water, and finally grafting ferrocenecarboxaldehyde and fluorine-containing aldehyde on the surface; during graft modification, the mol ratio of the ferrocene formaldehyde to the fluorine-containing aldehyde is 10: 1-1.7.

2. The insulated heat-conducting polyphenylene sulfide/carbon fiber composite material as claimed in claim 1, wherein the mass ratio of the polyphenylene sulfide to the modified carbon fiber is 100: 20-40; the weight average molecular weight of the polyphenylene sulfide is 2-6 ten thousand; the carbon fiber is PAN chopped carbon fiber, the diameter of the carbon fiber is 1-20 mu m, and the length of the carbon fiber is 0.5-10 mm.

3. The polyphenylene sulfide/carbon fiber composite material as claimed in claim 1, wherein the carbon atoms of the fluorinated aldehyde are 2-6, and the number of fluorine atoms is not less than 3.

4. The polyphenylene sulfide/carbon fiber composite material as claimed in claim 3, wherein the fluorinated aldehyde is at least one selected from pentafluoropropionaldehyde, 3,3, 3-trifluoropropionaldehyde, 2,2, 2-trifluoroacetaldehyde, 4,4, 4-trifluorobutanal, heptafluorobutanal, 3,3,4,4,5,5, 5-heptafluorovaleraldehyde, nonafluorovaleraldehyde, and 2,2,3,3,4,4,5, 5-octafluorovaleraldehyde.

5. The polyphenylene sulfide/carbon fiber composite material with insulating and heat conducting functions as claimed in claim 1, wherein the mass ratio of the total amount of ferrocene formaldehyde and fluorine-containing aldehyde to the carbon fiber is 0.17-0.25: 1;

or the grafting rate of the modified carbon fiber after grafting is 11.5-16.4%.

6. The polyphenylene sulfide/carbon fiber composite material with the insulation and the heat conduction as claimed in claim 1, wherein the plasma treatment conditions are that the flow rate of ammonia gas is 30-50mL/min, the pressure in the low-temperature plasma reaction chamber is 30-100Pa, the speed of the carbon fiber passing through the low-temperature plasma emission device is 50-100m/h, the distance between the carbon fiber and the low-temperature plasma emission device is 20-50mm, the plasma emission power is 100-900W/beam, the treatment temperature is 10-20 ℃, and the treatment time is 1-5 min; the treatment condition of soaking in ammonia water is that the concentration of ammonia water is 10-15wt%, and the soaking time is 5-10 s.

7. The polyphenylene sulfide/carbon fiber composite material as claimed in claim 1, wherein the modified carbon fiber is obtained by a preparation method comprising the following steps:

s1) carrying out ultrasonic cleaning on the carbon fiber, carrying out vacuum drying, then treating the surface of the carbon fiber by using low-temperature plasma with ammonia gas as a discharge medium, soaking the treated carbon fiber in ammonia water for 5-10S, washing, and drying for later use;

s2) ultrasonically dispersing the surface-treated carbon fiber and the dehydrating agent obtained in the step S1 in an organic solvent, heating to a reflux state, dropwise adding a solution containing ferrocene formaldehyde and fluorine-containing aldehyde, reacting at a constant temperature after dropwise adding, naturally cooling to room temperature, filtering, washing and drying to obtain the carbon fiber and the dehydrating agent.

8. The polyphenylene sulfide/carbon fiber composite material as claimed in claim 7, wherein in step S2), the dehydrating agent is selected from one or a combination of more than two of calcium oxide, sodium sulfate and magnesium sulfate, and the amount of the dehydrating agent is 10-20wt% of the carbon fiber; the organic solvent and the solvent in the solution of ferrocene carboxaldehyde and fluoroaldehyde are selected from at least one of benzene, petroleum ether and tetrahydrofuran; in the step S2), the reaction temperature is 60-80 ℃, and the reaction time is 6-10 h.

9. The insulated heat-conducting polyphenylene sulfide/carbon fiber composite material as claimed in claim 1, further comprising auxiliary materials, wherein the auxiliary materials comprise an antioxidant, a toughening agent, a lubricant and a compatilizer.

10. The preparation method of the insulated heat-conducting polyphenylene sulfide/carbon fiber composite material as claimed in any one of claims 1 to 8, which is characterized by comprising the following steps:

1) uniformly mixing polyphenylene sulfide and modified carbon fiber;

2) extruding and granulating the mixture obtained in the step 1) in a double-screw extruder to obtain the insulating heat-conducting polyphenylene sulfide/carbon fiber composite material.