阅读说明：本技术 以热塑性聚合物为基体的复合材料的改性剂的生产方法 (Method for producing modifier of composite material using thermoplastic polymer as matrix ) 是由 M·R·普列捷琴斯基 V·O·萨伊克 A·E·贝兹罗德尼耶 S·N·斯米尔诺夫 M·S·加尔 于 2020-03-17 设计创作，主要内容包括：提出了一种制备以热塑性聚合物(聚酰胺或聚碳酸酯)为基体的高强度复合材料的方法,包括将聚合物与纤维及碳纳米管混合。将碳纳米管作为包含聚合物和碳纳米管的改性剂的一部分引入聚合物中,所述改性剂中碳纳米管的浓度为5-33重量％。还提出了一种制备改性剂的方法。(A method for preparing a high strength composite material with a thermoplastic polymer (polyamide or polycarbonate) as a matrix is proposed, which comprises mixing the polymer with fibres and carbon nanotubes. Carbon nanotubes are introduced into a polymer as part of a modifier comprising the polymer and carbon nanotubes, the concentration of carbon nanotubes in the modifier being from 5 to 33 weight percent. A method of preparing the modifier is also presented.)

1. A process for producing a modifier for the preparation of a composite material based on a thermoplastic polymer, characterized in that the thermoplastic polymer is mixed with a solvent and an alkali metal salt in the following proportions (in% by weight):

thermoplastic polymer-3-15%,

70 to 94 percent of solvent,

alkali metal salt-3-15%,

until the polymer is completely dissolved, then no more than 5% by weight of carbon nanotubes are added to the mixture with stirring to produce a dispersion, then a coagulant is added to the dispersion with continuous stirring, then the resulting dispersion is filtered, and the filter cake is washed and dried.

2. The process according to claim 1, characterized in that the solvent is selected from: ethanol or N-methylpyrrolidone or dimethylacetamide.

3. The method according to claim 1, characterized in that the alkali metal salt is lithium chloride or calcium chloride.

4. The method of claim 1, wherein the carbon nanotubes are single-walled carbon nanotubes.

5. The method of claim 1, wherein the dispersion of carbon nanotubes is prepared using a high speed disperser, a probe sonicator, a microfluidizer, a high speed stirrer, a three roll mill.

6. The method according to claim 1, characterized in that the coagulant is water or ethanol.

7. The method according to claim 1, characterized in that the dispersion is filtered through a membrane filter having a filter pore size of 5-100 microns.

8. The method according to claim 1, characterized in that the filter cake is dried in a drying oven, followed by further drying using a rotary evaporator.

9. The method according to claim 1, characterized in that the filter cake is ground using a grinder and further subjected to vacuum treatment.

10. A process for producing a modifier for the preparation of composite materials based on thermoplastic polymers, characterized in that carbon nanotubes are mixed with caprolactam such that the content of carbon nanotubes in the mixture is at least 1% by weight, the dispersion obtained is heated to 80 to 120 ℃ and treated with ultrasound, a caprolactam polymerization catalyst and a caprolactam polymerization activator are added, and the dispersion obtained is heated and dried.

11. The method of claim 10, wherein the carbon nanotubes are single-walled carbon nanotubes.

12. The process according to claim 10, characterized in that the caprolactam polymerization catalyst is selected from the group consisting of: alkali metal or alkali metal hydride, or alkali metal oxide, or alkali metal hydroxide, or their compound with caprolactam.

13. Process according to claim 10, characterized in that the caprolactam polymerization catalyst is added to the dispersion in an amount of 0.1-10% by weight.

14. Process according to claim 10, characterized in that the caprolactam polymerization activator is selected from: isocyanates or diisocyanates.

15. The process according to claim 10, characterized in that the caprolactam polymerization activator is added to the dispersion in an amount of 0.01 to 10% by weight.

16. The method according to claim 10, characterized in that the dispersion is heated while continuously purging with dry nitrogen and stirring.

17. The method according to claim 10, characterized in that the dispersion is treated with ultrasound while continuously purging with dry nitrogen and stirring.

18. The method of claim 10, wherein the dispersion is produced using a probe sonicator or a microfluidic processor or a high speed mixer.

19. A method for producing a modifier for the preparation of a composite material based on a thermoplastic polymer, characterized in that carbon nanotubes are mixed with caprolactam such that the content of carbon nanotubes in the resulting mixture does not exceed 1% by weight, the dispersion obtained is heated to 100 ℃ and 120 ℃ and treated with ultrasound, after which it is filtered to form a concentrate, followed by the addition of a caprolactam polymerization catalyst, and the dispersion obtained is then heated and dried.

20. The method of claim 19, wherein said carbon nanotubes are single-walled carbon nanotubes.

21. The method according to claim 19, characterized in that the heating of the dispersion is carried out under purging with dry nitrogen and stirring.

22. The method according to claim 19, characterized in that the dispersion is treated by ultrasound with continuous purging and stirring with dry nitrogen.

23. The method of claim 19, wherein the dispersion is produced using a probe sonicator or a microfluidic processor or a high speed mixer.

24. The process according to claim 19, characterized in that 1 to 10% by weight of caprolactam polymerization catalyst is added to the dispersion.

25. The process of claim 19, wherein the caprolactam polymerization catalyst is water.

26. The method according to claim 19, characterized in that the dispersion is filtered using a membrane filter having a filter pore size of 2-100 microns.

27. The method according to claim 19, characterized in that a vacuum pump and a flat bottom flask are used for the filtration.

28. The method according to claim 19, characterized in that the dispersion is filtered at a temperature not lower than 100 ℃ in an electric furnace.

29. The method according to claim 19, characterized in that the drying of the concentrate is carried out in a drying oven.

30. A process for producing a modifier for a compounded material based on a thermoplastic polymer, characterized in that carbon nanotubes and caprolactam are mixed using a three-roll mill so that the content of carbon nanotubes in the mixture obtained does not exceed 10% by weight, a caprolactam polymerization catalyst is added to the dispersion obtained, the polymerization is carried out in a reactor at about 260 ℃, and the material obtained is then removed and dried.

31. The method of claim 30, wherein said carbon nanotubes are single-walled carbon nanotubes.

32. The process according to claim 30, characterized in that not more than 10% by weight of the caprolactam polymerization catalyst is added to the dispersion.

33. The process of claim 30, characterized in that the caprolactam polymerization catalyst is water.

34. A modifier for use in the preparation of a composite material based on a thermoplastic polymer, characterised in that the modifier is prepared according to any one of claims 1 to 9, claims 10 to 18, claims 19 to 29 or claims 30 to 33 and comprises a thermoplastic polymer and 5 to 33% by weight of carbon nanotubes.

35. Modifier according to claim 34, characterized in that the at least one thermoplastic polymer is chosen from polyamides or polycarbonates.

36. The modifying agent according to claim 34, characterized in that said carbon nanotubes are single-walled carbon nanotubes.

37. A method for the preparation of a composite material based on a thermoplastic polymer, said method comprising mixing said polymer with fibres and carbon nanotubes, characterized in that said thermoplastic polymer is mixed with nanotubes contained in said modifier according to claims 34-36, said modifier comprising a thermoplastic polymer and 5-33% by weight of carbon nanotubes.

38. The method of claim 37, wherein the carbon nanotubes are single-walled carbon nanotubes.

39. The method according to claim 37, characterized in that the at least one thermoplastic polymer is chosen from polyamides or polypropylene or polyethylene or polycarbonate.

40. The method according to claim 37, characterized in that the composite material comprises not more than 70% by weight of fibers.

41. The method of claim 37, wherein the fibers are carbon fibers.

42. The method of claim 37 wherein said fibers are basalt fibers.

43. The method of claim 37, wherein the fibers are glass fibers.

44. The method of claim 37, wherein the polymer, fiber, and modifier are mixed using an extruder.

Technical Field

The present invention is a technique for actually producing a thermoplastic polymer-based composite material containing carbon fibers, glass fibers or basalt fibers (hereinafter referred to as "fibers") and carbon nanotubes (hereinafter referred to as "CNTs").

Background

To improve the physical and mechanical properties of thermoplastic polymers, various fillers and additives are used, including carbon-based additives. The addition of carbon fibers to thermoplastic polymers is a known method for making composite materials [ U.S. application No. 9249295 ]. However, composite materials based on thermoplastic polymers contain only carbon fibers, which have a series of disadvantages. One of the significant drawbacks of such composites is the low adhesion between the carbon fibers and the polymer matrix. This reduces the maximum strength range achievable with composites based on thermoplastic polymers, thereby limiting the possibilities for their use.

In addition, it is particularly noted that composites based on thermoplastic polymers contain carbon nanotubes as reinforcing additives, which are considered to be among the most promising fillers for improving the strength properties of thermoplastic polymers, due to their own unique physical and mechanical properties. In addition, the carbon nanotube additive can impart electrical conductivity to the composite.

A method for the preparation of thermoplastic polymer based composites is known, which is based on the chemical interaction of a polymer and modified carbon nanotubes, wherein the percentage by weight of carbon nanotubes in the composite is between 0.1 and 5, said polymer being directly producible from comonomers by a polymerization reaction in a synthesis reactor [ us patent 6426134 ]. The disadvantage of this method is the complex manufacturing process of the composite material, which requires modification of the carbon nanotubes and polymerization in a reactor, which does not allow the use of standard equipment for processing thermoplastic materials.

A known process for the preparation of Composite Materials comprises mixing polyamide 6 (praa-6) particles, carbon nanotubes, carbon fibres or basalt fibres, using a twin-screw extruder, and the final sample of Composite material is prepared by means of injection moulding techniques [ synergistic effect of carbon nanotubes on mechanical properties of basalt and carbon fibre reinforced polyamide 6 mixed Composite Materials, Jozsef Szakacs) and Laszlo Meszaros, Journal of the thermoplastic Composite Materials2018, Vol.3 ]. One of the disadvantages of this method is that it does not allow to reach the maximum strength of the composite material, since the strength of the composite material depends on how well the carbon nanotubes are distributed in the matrix, but the carbon nanotubes have a higher tendency to aggregate, which prevents the preparation of a good quality carbon nanotube dispersion. In this case, high-intensity stirring is not suitable for reducing the aggregation, and high-intensity stirring using an extruder causes damage to the carbon fibers, which results in a decrease in the strength of the composite material.

The state of the art therefore has some drawbacks, in particular the insufficient strength of the composite materials comprising the known thermoplastic polymers as matrix.

Disclosure of the invention

The invention solves the problem of developing a method for preparing a high-performance composite material taking a thermoplastic polymer as a matrix. To solve this problem, we propose a method for preparing a modifier, a high quality concentrate of carbon nanotubes produced in a polymer, and a modifier for preparing a composite material. The synergistic effect is achieved by adding a modifier containing carbon nanotubes and fibers to the composite material, which is reflected in the high strength of the finished composite material, which also has electrical conductivity.

This problem is solved by providing a method for preparing a high performance composite material with a thermoplastic polymer (e.g. polyamide or polycarbonate) as matrix, said method comprising mixing said polymer with fibres and carbon nanotubes. The carbon nanotubes are introduced into the polymer by a modifier comprising a polymer and carbon nanotubes. The concentration of carbon nanotubes in the modifier is 5 to 33 wt%. The concentration of fibers in the composite material does not exceed 70% by weight. The fibers are carbon fibers, basalt fibers or glass fibers. The mixing of the polymer, the fiber and the modifier containing the carbon nanotubes is performed on an extruder. Single-walled carbon nanotubes are mainly used. To prepare the modifier, Tuball single-walled carbon nanotubes were used. Basic properties of Tuball single-walled carbon nanotubes: the carbon content is over 85 wt%, the single-walled carbon nanotube is over 75 wt%, the length is over 5 microns, the average outer diameter is 1.6 +/-0.5 nm, the intensity ratio of G and D oscillation modes is over 100 when the electrified wavelength is 532 nm, the content of metal impurities is less than 15 wt%, and the specific surface area is over 500 square meters per gram.

The problem is also solved by providing a modifier for the preparation of a composite material based on a thermoplastic polymer, said modifier containing carbon nanotubes and the content of carbon nanotubes in the modifier being from 5 to 33% by weight.

The carbon nanotubes comprised in the modifier are preferably single-walled carbon nanotubes and the at least one thermoplastic polymer is selected from the group consisting of: polyamide or polycarbonate.

The problem is also solved by providing a process for producing a modifier for the preparation of high performance composites based on thermoplastic polymers.

In a first embodiment, a solution-based method for preparing a modifier based on a thermoplastic polymer is provided, comprising mixing the thermoplastic polymer with a metal salt or acid capable of reducing hydrogen bonding of the polymer in a polar solvent.

Typically the concentration of polymer is 3-15 wt% and the concentration of salt/acid is 3-15 wt% of the total weight. Stirring until the polymer is completely dissolved, adding up to 5 wt% (inclusive) of carbon nanotubes thereto, adding a coagulant to the dispersion with stirring, filtering the dispersion, rinsing and drying the filter cake. The thermoplastic polymer is a polyamide. Ethanol, N-methylpyrrolidone or dimethylacetamide can be used as the polar solvent.

The concentration of the solvent in the mixture before coagulation is 70-94%. These solvents are the most efficient. Among these salts, lithium chloride or calcium chloride works best. Water or ethanol may be used as a coagulant. In order to obtain a good dispersion of carbon nanotubes, the following equipment can be utilized: high-speed dispersion machine, probe ultrasonic instrument, microfluid processor, high-speed stirrer or three-roller grinder. Filtration may be accomplished through a membrane filter having a pore size of 5-100 microns. To remove residual moisture, the filtrate was ground and treated under vacuum, then heated in a drying oven and/or rotary evaporator.

This method of preparing the modifier can also be applied to the same practice of other polyamides, such as semi-aromatic polyphthalamide (PPA) and nylon MXD-6.

In a second embodiment, the modifier for the preparation of high-performance composites based on thermoplastic polymers (PA-6) is obtained by anionic polymerization. This method involves mixing carbon nanotubes with molten caprolactam, heating the resulting dispersion and treating the dispersion with a probe sonicator, microfluidizer or high speed stirrer to improve dispersion quality. The dispersion is heated with stirring at 80-120 ℃ under moisture-free conditions, which are achieved by continuous purging with dry nitrogen or any other dry inert gas. When this method is used, the concentration of carbon nanotubes in the dispersion is at most 1% by weight (including the present number). The catalyst is added to the dispersion and alkali metals, alkali metal hydrides and their oxides or hydroxides, or their compounds with caprolactam can be used as catalyst. The concentration of the catalyst in the working mixture is between 0.1 and 10 (inclusive) wt.%. The polymerization can be initiated by the temperature rise and the use of an activator, the concentration of which in the working mixture can control the length of the polymer chains; the concentration may fluctuate between 0.1 and 10 wt.%, and is more effective between 0.1 and 1 wt.%. Isocyanates or diisocyanates, or their heat-activated analogs, can be used as activators. The polymerization is generally carried out at a temperature in the range of 120 to 180 ℃ for a period of not more than 30 minutes.

In a third embodiment, the modifier used for the preparation of the high-performance composite based on a thermoplastic polymer (PA-6) is prepared by a hydrolytic polymerization process. In the preparation of such modifiers, water is the catalyst for the polymerization of caprolactam, which requires higher temperatures and, correspondingly, higher pressures. In this embodiment, caprolactam is mixed with carbon nanotubes. When this method is used, the concentration of carbon nanotubes in the dispersion is at most 1% by weight. The resulting dispersion is heated to a temperature of 100 to 120 ℃ and treated with ultrasound. The dispersion was heated and sonicated without constant blowing of dry nitrogen and stirring. The dispersion is then filtered to form a concentrate, and caprolactam polymerization catalyst is added to the dispersion, water being the catalyst. Water is added in an amount of 1 to 10 (inclusive) weight percent. For the preparation of the dispersion, a probe sonicator, a microfluidizer or a high speed stirrer may be used. The dispersion was filtered with a membrane filter having a filter pore size of 2 to 100 microns. To accelerate filtration, a vacuum pump and a flat bottom flask were used. Filtering at the temperature not lower than 100 deg.C. The polymerization of caprolactam is carried out at 260 ℃. The concentrate was dried in a vacuum oven at a temperature of 60 ℃.

In a fourth embodiment, the modifier used to prepare the high performance composite based on a thermoplastic polymer (polyamide 6) is prepared by hydrolytic polymerization.

In this embodiment, milled caprolactam is mixed with carbon nanotubes in an amount up to 10% (inclusive) until a homogeneous mixture is obtained, which is then heated in the absence of oxygen until the caprolactam is completely melted. The hot mixture is processed on a three-roll mill with a rotating shaft heated beforehand until the desired dispersion quality is achieved. After cooling and grinding to powder with a grinder, up to 10% by weight of water is added to the powder with continuous stirring to ensure uniform wetting.

The polymerization is carried out by placing the material in a closed gas-tight container at a temperature of about 260 ℃ for a period of 10 to 20 hours inclusive. The prepared material was dried.

The problem is also solved by providing a modifier for the preparation of a composite material based on a thermoplastic polymer, which composite material can be prepared by one of the disclosed methods and comprises a thermoplastic polymer and about 5 to 33 wt.% of carbon nanotubes.

The at least one thermoplastic polymer for the modifier is selected from: polyamide or polycarbonate.

The carbon nanotubes contained therein are single-walled carbon nanotubes.

The problem is also solved by providing a method for preparing a composite material based on a thermoplastic polymer, said method comprising mixing said polymer with fibres and carbon nanotubes, wherein said thermoplastic polymer is mixed with nanotubes comprised in a modifier, said modifier comprising a thermoplastic polymer and 5-33 wt% of carbon nanotubes.

Preferred embodiments of the invention

Example 1

1) Preparing a modifier based on polyamide.

To prepare the modifier, 50 g of lithium chloride are mixed with 50 g of polyamide 6 and 233 ml of N-methylpyrrolidone. The concentration of polyamide 6 is 15% of the total weight. After this, the mixture was stirred in a stirrer at 70 ℃ until the polyamide was completely dissolved in 6 hours. The resulting solution was poured into an IKA Ultra Turrax t 50 high speed disperser, 5.5 grams of single walled carbon nanotubes (1.62%) were added, and the solution was homogenized until the energy density was 2 kw x.h/liter. Then, 300 ml of distilled water was added to the resulting dispersion under stirring and left for 24 hours until complete coagulation. After coagulation, the resulting mixture was poured into a filter funnel (filter pore size 20 microns) and filtered with additional rinsing until complete removal of the methylpyrrolidone and lithium chloride from the solution. After filtration, the resulting material was dried in a drying oven at 80 ℃ to 50% humidity, after which the material was further dried on a rotary evaporator at a temperature of 110 ℃ and a pressure of 100 mbar to avoid air oxidation of the material. After this, it was ground to a powder using a grinder. Final drying is then done in a vacuum oven to completely remove the moisture from the material. The drying temperature was 120 ℃ for 10 hours.

The thus prepared single-walled carbon nanotube concentrate in polyamide, wherein the concentration of single-walled carbon nanotubes is 10% by weight and the concentration of polyamide is 90% by weight, can be used as a modifier in powder form.

If necessary, the composite material is melted in an extruder and the pellets are extruded for subsequent use on an injection molding machine.

2) Preparing the high-performance composite material taking polyamide as a matrix.

10 grams of the prepared modifier was mixed with 20 grams of carbon fiber and 170 grams of polyamide 6 polymer in a twin screw extruder. Composite pellets were obtained, from which test samples were then prepared by injection molding.

The polymer formulation prepared had the following composition: 89.5 percent of polyamide 6 polymer, 0.5 percent of single-walled carbon nanotube and 10 percent of carbon fiber. The breaking strength of the sample reaches 140 MPa. Resistivity of the sample-100 ohm cm.

3) Preparing the high-performance composite material taking polypropylene as a matrix.

5 g of a polyamide-based modifier were mixed with 10 g of glass fibers and 185 g of polypropylene (PP) in a twin-screw extruder. To obtain the composite particles. Test samples were then prepared by injection molding.

The polymer formulation prepared had the following composition: 92.5 percent of polyethylene polymer, 0.25 percent of single-walled carbon nanotube, 2.25 percent of polyamide and 5 percent of glass fiber.

The breaking strength of the sample reaches 50 MPa.

The resistivity of the sample reaches 10⁷Ohm cm.

4) Preparing the high-performance composite material taking polypropylene as a matrix.

15 g of a polyamide-based modifier, 35 g of basalt fibres and 150 g of polypropylene (PP) were mixed in a twin-screw extruder. Obtaining the composite particles. The standard sample was then prepared by injection molding.

The polymer composition prepared had the following composition: 75 percent of polypropylene polymer, 0.75 percent of single-walled carbon nanotube, 6.75 percent of polyamide and 17.5 percent of basalt fiber. The breaking strength of the sample reaches 73 MPa.

The resistivity of the sample reaches 10⁶Ohm cm.

Example 2

1) A modifier based on Polycarbonate (PC) was prepared.

To prepare the modifier, 50 g of polycarbonate and 300 ml of N-methylpyrrolidone are mixed. The concentration of polycarbonate was 16.7% by weight. After this, the mixture is stirred in a stirrer at a temperature of 70 ℃ until the polycarbonate has completely dissolved in 6 hours. The resulting solution was stirred using an IKA Ultra Turrax t 50 high speed disperser followed by the addition of 3 grams of Tuball single walled carbon nanotubes and the stirring of the compound to an energy density of 2 kw x.h/l.

For coagulation, 300 ml of distilled water were added to the resulting dispersion under stirring and the mixture was left for 24 hours until complete coagulation. After coagulation, the mixture was poured into a filter funnel (filter pore size 20 microns) and filtered with additional rinsing until the N-methylpyrrolidone in the solution was completely removed. After filtration, the resulting material was dried in a drying oven at a temperature of 80 ℃ to a humidity of 50%. After that, the material was further dried on a rotary evaporator at a temperature of 110 ℃ and a pressure of 100 mbar to avoid air oxidation of the material. Thereafter, it is crushed into powder using a grinder. Final drying is then done in a drying oven to completely remove the moisture from the material. The drying temperature was 120 ℃ for 10 hours.

The concentration of single-walled carbon nanotubes in the polycarbonate thus prepared, wherein the concentration of single-walled carbon nanotubes was 16.7 wt% and the concentration of polycarbonate was 83.3 wt%, was then used as an improver. The modifier is in powder form.

If the concentrate is preferably in the form of pellets, it can be passed through an extruder to form pellets for further use.

2) Preparing the high-performance composite material taking polycarbonate as a matrix.

20 grams of the modifier, 20 grams of carbon fiber, and 160 grams of polycarbonate polymer were mixed in a twin screw extruder. Thus prepared composite particles were then used to prepare standard samples by injection molding.

The polymer composition prepared had the following composition: 88.33 percent of carbonate polymer, 1.67 percent of single-walled carbon nanotube and 10 percent of carbon fiber. The breaking strength of the sample reaches 64 MPa.

The resistivity of the sample reaches 10⁴Ohm cm.

Example 3

1) Preparing the modifier.

To prepare the dispersion, 4.2 g of Tuball single-walled carbon nanotubes (1.04%) were mixed with 40 g of caprolactam in a glass cup and then heated to 120 ℃ on a small oven with constant blowing of dry nitrogen and stirring using a magnetic stirrer. Stirring was continued for one hour to remove water from the caprolactam. Thereafter, the mixture was treated by ultrasonication for 10 minutes under a power of 240 watts with continuous blowing of dry nitrogen and continuous stirring. To the dispersion was added 1.2 grams of C10 catalyst (produced by brueggeemann Group, germany), then 0.8 grams of C20P activator was added and stirred for an additional minute, then heated to 150 ℃. This will start the polymerization of caprolactam, which is usually over 15 minutes.

Thus, a polyamide 6-wall carbon nanotube concentrate was prepared in which the concentration of single-wall carbon nanotubes was 10 wt% and the concentration of polyamide 6 was 90 wt%, which was then used as a modifier. The modifier is in powder form.

The prepared powder was stored in a container hermetically under nitrogen. If necessary, the composite material is melted in an extruder and the pellets are then extruded for further use on an injection molding machine.

2) Preparing the high-performance composite material taking polyamide as a matrix.

10 g of the modifier obtained were mixed together with 323 g of polyamide 6 polymer by means of a twin-screw extruder. The polymer composition prepared had the following composition: 99.7 percent of polyamide 6 polymer and 0.3 percent of single-walled carbon nanotube. The polymer component was in the form of pellets, and standard samples were prepared by injection molding using the pellets.

Flexural strength measurements showed an increase in the modulus of elasticity to 4.5 gigapascals and a strength of 164 megapascals, which is higher than the values for pure polyamide 6 polymer, which are 2.8 gigapascals and 150 megapascals for the corresponding values for pure polyamide 6 polymer. The values obtained are listed in table 1.

10 grams of the resulting modifier was mixed with 290 grams of polyamide 6 polymer and 33.3 grams of short carbon fibers using a twin screw extruder. The polymer composition prepared had the following composition: 89.7 percent of polyamide 6 polymer, 10 percent of carbon fiber and 0.3 percent of carbon nano tube. Then, a standard sample was prepared by injection molding. Flexural strength measurements showed that the modulus of elasticity increased to 9.5 gigapascals, while the strength reached 201 megapascals, which is higher than the value of the pure polymer polyamide 6.

2 g of the modifier obtained were mixed with 30 g of carbon fibers and 68 g of polyamide 6 polymer in a twin-screw extruder. Preparing the composite particles. Then, a standard sample was prepared by injection molding. The polymer composition prepared had the following composition: 69.8 percent of polyamide 6 polymer, 0.2 percent of carbon nano tube and 30 percent of carbon fiber. The flexural strength of the sample was 585 mpa and the modulus of elasticity was 33 gpa. For comparison, a similar composite material containing 30% carbon fibers, but no carbon nanotubes, exhibited a modulus of elasticity of 30 gigapascals and a flexural strength of 450 mega pascals. The results are shown in Table 1.

The resistivity of the material was 0.1 ohm cm.

Example 4

1) Preparation of the modifier

To prepare the dispersion, 1 g of Tuball single-walled carbon nanotubes (1%) were placed in a glass cup and heated with 99 g of caprolactam on an electric furnace to 100 ℃ and 120 ℃ with constant blowing of dry nitrogen and stirring with a magnetic stirrer. Stirring was continued for 1 hour to remove water from the caprolactam. The mixture was then treated with ultrasound at 240 watts for 10 minutes, with stirring while blowing dry nitrogen. The resulting dispersion was filtered through a membrane filter having a 2 μm filter pore size. To speed up the filtration process, a vacuum pump and a flat bottom flask with a volume of 1 liter can be used. In order to maintain the temperature of the dispersion, it was filtered on an electric furnace at a temperature of not less than 100 ℃. The initial weight of the dispersion was 100 grams and the caprolactam filtered through the funnel reached 97 grams. The mass of concentrate remaining on the funnel was 3 grams and the concentration of nanotubes in the concentrate was 33.3%. 0.3 g of water was added as catalyst to the concentrate. The polymerization of caprolactam was carried out at 260 ℃ for six hours, and the caprolactam was subsequently dried in a vacuum oven at 60 ℃.

Thus, a polyamide 6-wall carbon nanotube concentrate was prepared in which the concentration of single-wall carbon nanotubes was 33 wt% and the concentration of polyamide 6 was 67 wt%, which was then used as a modifier. The modifier is in powder form.

2) Preparing the high-performance composite material taking polyamide as a matrix.

10 g of the resulting modifier, 20 g of polyamide 6 polymer and 3.3 g of carbon fibres were mixed in a twin-screw extruder to prepare a polyamide-based high-performance composite in the form of granules, from which standard samples were then prepared by injection moulding. The polymer composition prepared had the following composition: polyamide 6 polymer 80 wt%, carbon nanotube 10 wt% and carbon fiber 10 wt%.

The tensile strength of the sample with 10% carbon nanotubes was 160 mpa. This is 1.6 times higher than the tensile strength of the sample consisting of polyamide 6 and 10% carbon fibres, but this sample does not contain nanotubes.

The resistivity of the material was 1 ohm cm.

Example 5

1) Preparing the modifier.

4 grams of Tuball single-walled carbon nanotubes (10%), 40 grams of caprolactam and 4 grams of water (10%) were stirred together using an Exakt three roll mill. To obtain a dispersion of carbon nanotubes, 110 tests were completed. The caprolactam dispersion was allowed to polymerize in the reactor at 260 c for 12 hours. After the reactor was cooled to room temperature, the prepared material was taken out and dried in a vacuum oven at 60 ℃ for 1 hour.

Thus, a polyamide 6-wall carbon nanotube concentrate was prepared in which the concentration of single-wall carbon nanotubes was 10 wt% and the concentration of polyamide 6 was 90 wt%, which was then used as a modifier. The modifier is in powder form.

2) Preparing the high-performance composite material taking polyamide as a matrix.

In this example, to prepare a composite material based on a thermoplastic polymer and the resulting modifier, 1 gram of the resulting modifier, 20 grams of carbon fiber and 179 grams of polyamide 6 polymer were mixed together in a twin screw extruder, a twin screw extruder. Composite particles were prepared and then standard samples were prepared by injection molding.

The composite composition was prepared having the following composition: 0.5 percent of single-walled carbon nanotube, 10 percent of carbon fiber and 6 percent to 89.5 percent of polyamide. The breaking strength of the sample reaches 162 MPa.

The resistivity of the material was 2 ohms cm.

TABLE 1 characteristics of Polyamide 6 with Tuball carbon nanotubes and carbon fibers

Industrial applications

The invention can be used in different industrial fields, i.e. those where parts made of composite materials are required to have high strength, while maintaining low weight, such as: aerospace, automotive, as well as machine manufacturing, medical, sports production and applications where electrical conductivity is required for composite materials.