METHOD FOR PRODUCING A MODIFIER FOR PREPARING A COMPOSITE MATERIAL BASED ON A THERMOPLASTIC POLYMER

Abstract

A method for producing a modifier for preparing a composite material based on a thermoplastic polymer where the thermoplastic polymer is mixed with a solvent and salts of alkali metals with the following ratio of components (wt. %): thermoplastic polymer—3-15, solvent—70-94, salts of alkali metals—3-15, until the polymer is fully dissolved, and then carbon nanotubes are added to the mixture in an amount up to 5 wt. % while stirring to produce a dispersion, then a coagulant is added to the dispersion under continuous stirring, the resulting dispersion is then filtered, and the filter cake is rinsed and dried up. The solvent is selected from the group of: alcohol, or N-methylpyrrolidone, or dimethylacetamide. The alkali metal salt is lithium chloride or calcium chloride. The carbon nanotubes are single-wall carbon nanotubes.

Claims

1-44. (canceled)

45. A method for producing a modifier for preparing a composite material based on a thermoplastic polymer, the method comprising: mixing the thermoplastic polymer with a solvent and salts of alkali metals or calcium in a following ratio (wt. %): the thermoplastic polymer: 3-15, the solvent: 70-94, and the salts of alkali metals or calcium: 3-15, until the thermoplastic polymer is fully dissolved; adding carbon nanotubes to the mixture in an amount of up to 5 wt. % while stirring the mixture to produce a dispersion; adding a coagulant to the dispersion under continuous stirring; filtering the resulting coagulated dispersion to produce a filter cake; and rinsing and drying the filter cake.

46. The method of claim 45, wherein the solvent is selected from the group consisting of: alcohol, or N-methylpyrrolidone, or dimethylacetamide.

47. The method of claim 45, wherein the salt is lithium chloride or calcium chloride.

48. The method of claim 45, wherein the carbon nanotubes are single-wall carbon nanotubes.

49. The method of claim 45, wherein the dispersion of carbon nanotubes is prepared using a high-speed disperser, a probe sonicator, a microfluidic processor, a high-speed mixer, or a three roll mill.

50. The method of claim 45, wherein the coagulant is water or ethanol.

51. The method of claim 45, wherein the dispersion is filtered through a membrane filter with a pore size of 5 to 100 microns.

52. The method of claim 45, wherein the filter cake is dried in a drying cabinet followed by further drying the filter cake using a rotary evaporator.

53. A method for producing a modifier for preparing a composite material based on a thermoplastic polymer, the method comprising: mixing carbon nanotubes with caprolactam so that a content of the carbon nanotubes in the mixture is at least 1 wt. % in order to produce a dispersion; heating the dispersion to a temperature 80 to 120° C.; sonicating the heated dispersion; adding a caprolactam polymerization catalyst and a caprolactam polymerization activator to the dispersion; and heating and drying the dispersion.

54. The method of claim 53, wherein carbon nanotubes are single-wall carbon nanotubes.

55. The method of claim 53, wherein the caprolactam polymerization catalyst is selected from the group consisting of: alkali metals, hydrides of alkali metals, oxides thereof, hydroxides thereof, and/or their compounds with caprolactam.

56. The method of claim 53, wherein the caprolactam polymerization catalyst is added to the dispersion in an amount 0.1 to 10 wt. %.

57. The method of claim 53, wherein the caprolactam polymerization activator is an isocyanate or a diisocyanate.

58. The method of claim 53, wherein the caprolactam polymerization activator is added to the dispersion in an amount 0.01 to 10 wt. %.

59. The method of claim 53, wherein the dispersion is heated while it is continuously purged with dry nitrogen and stirred.

60. The method of claim 53, wherein the dispersion is sonicated while being continuously purged with dry nitrogen and stirred.

61. The method of claim 53, wherein the dispersion is produced using a probe sonicator, a microfluidic processor, or a high-speed mixer.

62. A method for producing a modifier for preparing a composite material based on a thermoplastic polymer, the method comprising: mixing carbon nanotubes with caprolactam so that their content in the resulting mixture is not more than 1 wt. %, to produce a dispersion; heating the dispersion to a temperature 100 to 120° C.; sonicating the dispersion; filtering the dispersion to form a concentrate; adding a caprolactam polymerization catalyst; and heating and drying the dispersion.

63. The method of claim 62, wherein carbon nanotubes are single-wall carbon nanotubes.

64. The method of claim 62, wherein the dispersion is heated while being continuously purged with dry nitrogen and stirred.

65. The method of claim 62, wherein the dispersion is sonicated while being continuously purged with dry nitrogen and stirred.

66. The method of claim 62, wherein the dispersion is produced using a probe sonicator, or a microfluidic processor, or a high-speed mixer.

67. The method of claim 62, wherein the caprolactam polymerization catalyst is added to the dispersion in an amount 1 to 10 wt. %.

68. The method of claim 62, wherein the caprolactam polymerization catalyst is water.

69. The method of claim 62, wherein the dispersion is filtered through a membrane filter with a pore size 2 to 100 μm.

70. The method of claim 62, wherein the drying is performed in a vacuum cabinet.

71. A method for producing a modifier for preparing a composite material based on a thermoplastic polymer, the method comprising: mixing carbon nanotubes with caprolactam using a three roll mill, so that a content of the carbon nanotubes in a resulting dispersion does not exceed 10 wt. %; adding a caprolactam polymerization catalyst to the resulting dispersion; polymerizing the dispersion in a reactor at a temperature about 260° C.; and removing and drying the dispersion.

72. The method according to claim 71, wherein the carbon nanotubes are single-wall carbon nanotubes.

73. The method according to claim 71, wherein the caprolactam polymerization catalyst is added to the dispersion in an amount of not more than 10 wt. %.

74. The method according to claim 71, wherein the caprolactam polymerization catalyst is water.

75. A modifier for preparing a composite material based on a thermoplastic polymer, the modifier produced using the following steps: mixing the thermoplastic polymer with a solvent and salts of alkali metals or calcium in a following ratio (wt. %): the thermoplastic polymer: 3-15, the solvent: 70-94, and the salts of alkali metals or calcium: 3-15, until the thermoplastic polymer is fully dissolved; adding carbon nanotubes to the mixture in an amount of up to 5 wt. % while stirring the mixture to produce a dispersion; adding a coagulant to the dispersion under continuous stirring; filtering the resulting coagulated dispersion to produce a filter cake; and rinsing and drying the filter cake.

76. A modifier for preparing a composite material based on a thermoplastic polymer, the modifier produced using the following steps: mixing carbon nanotubes with caprolactam using a three roll mill, so that a content of the carbon nanotubes in a resulting dispersion does not exceed 10 wt. %; adding a caprolactam polymerization catalyst to the resulting dispersion; polymerizing the dispersion in a reactor at a temperature about 260° C.; and removing and drying the dispersion.

77. A method for preparing a composite material based on a thermoplastic polymer, the method comprising mixing the thermoplastic polymer with fibers and a modifier, wherein the modifier is prepared by: mixing a thermoplastic polymer with a solvent and salts of alkali metals or calcium in a following ratio (wt. %): the thermoplastic polymer: 3-15, the solvent: 70-94, and the salts of alkali metals or calcium: 3-15, until the thermoplastic polymer is fully dissolved; adding carbon nanotubes to the mixture in an amount of up to 5 wt. % while stirring the mixture to produce a dispersion; adding a coagulant to the dispersion under continuous stirring; filtering the resulting coagulated dispersion to produce a filter cake; and rinsing and drying the filter cake.

78. The method of claim 77, wherein the thermoplastic polymer is polyamide, polypropylene, polyethylene, or polycarbonate.

79. The method of claim 77, wherein the fibers are carbon fibers, basalt fibers, or glass fibers.

80. A method for preparing a composite material based on a thermoplastic polymer, the method comprising mixing the thermoplastic polymer with fibers and a modifier, wherein the modifier is prepared by: mixing carbon nanotubes with caprolactam using a three roll mill, so that a content of the carbon nanotubes in a resulting dispersion does not exceed 10 wt. %; adding a caprolactam polymerization catalyst to the resulting dispersion; polymerizing the dispersion in a reactor at a temperature about 260° C.; and removing and drying the dispersion.

81. The method of claim 80, wherein the fibers are carbon fibers, basalt fibers, or glass fibers.

Description

PREFERRED EMBODIMENTS OF THE INVENTION

EXAMPLE 1

[0027] 1) Preparing a Polyamide-Based Modifier.

[0028] 50 g of LiC1 is mixed with 50 g of PA-6 and 233 ml of NMP to prepare the modifier. The PA-6 concentration is 15% of the total weight. The mixture at 70° C. is then stirred with a mixer until PA is fully dissolved, for 6 hours. The resulting solution is poured into an IKA UltraTurrax T50 high-speed disperser, 5.5 g of SWCNT (1.62%) is added, and the solution is homogenized until energy density 2 kW*h/l. Then 300 ml of distilled water is added to the resulting dispersion while stirring and left for 24 hours until complete coagulation.

[0029] After coagulation, the resulting mixture is poured into a filtering funnel (filter pore size is 20 microns) and filtered with additional rinsing until NMP and LiCl are completely removed from the solution. After filtration, the resulting material is dried in a drying cabinet at a temperature of 80° C. to a humidity of 50% further dried in a rotary evaporator at 110° C. and 100 mbar pressure to avoid air oxidation of the material. After that, the material is ground into powder with a grinder (milled) and the final drying is carried out in a vacuum cabinet at 120° C. for 10 hours to completely remove moisture from the material.

[0030] Thus prepared SWCNT concentrate in polyamide with SWCNT concentration 10 wt. % and PA concentration 90 wt. % is then used as a modifier in the form of a powder.

[0031] Where necessary, the composite material is melted in an extruder followed by the production of pellets for further use on injection molding machines. [0032] 2) Preparing a high-performance polyamide-based composite materials.

[0033] 10 g of the resulting modifier is mixed with 20 g of carbon fibers and 170 g of PA-6 polymer using a twin screw extruder. Pellets of the composite material are prepared, from which the test samples are prepared by injection molding.

[0034] The prepared polymer formulation has the following composition: PA-6 polymer—89.5%, SWCNT—0.5%, carbon fibers—10%. The measured tensile strength of the samples was 140 MPa and the electrical resistivity—100 Ohm*cm. [0035] 3) Preparing high-performance polyethylene-based composite material.

[0036] 5 g of the PA-based modifier is mixed with 10 g of carbon fibers and 185 g of polyethylene (PE) using a twin screw extruder. Thus, prepared pellets of the composite material are then used for preparation of the test samples by injection molding.

[0037] The prepared polymer formulation has the following composition: PE polymer—92.5%, SWCNT—0.25%, PA—2.25%, glass fiber—5%. The tensile strength of the samples was 50 MPa and the electrical resistivity 10.sup.7 Ohm cm. [0038] 4) Preparing a high-performance polypropylene-based composite material.

[0039] 15 g of the PA-based modifier is mixed with 35 g of basalt fibers and 150 g of polypropylene

[0040] (PP) using a twin screw extruder. Thus prepared pellets of the composite material are then used for preparation of standard samples by injection molding.

[0041] The prepared polymer composition has the following composition: PP polymer—75%, SWCNT—0.75%, PA—6.75%, basalt fibers—17.5%. The tensile strength of the samples was 73 MPa and the electrical resistivity was 10.sup.6 Ohm cm.

EXAMPLE 2

[0042] 1) Preparing a polycarbonate (PC)-based modifier.

[0043] 50 g of PC is mixed with 300 ml of NMP to prepare the modifier. The PC concentration is 16.7% of the total weight. The mixture at 70° C. is then stirred with a mixer until PC is fully dissolved, for 6 hours. The resulting solution is mixed using an IKA UltraTurrax T50 high-speed disperser, where 3 g of Tuball SWCNT is subsequently added, and the mixture is mixed until energy density of 2 kWh/l.

[0044] To coagulate, 300 ml of distilled water is then added to the resulting dispersion while stirring, and the mixture is left for 24 hours until complete coagulation. After coagulation, the mixture is poured into a filtering funnel (filter pore size is 20 microns) and filtered with additional rinsing with water until NMP is completely removed from the solution. After filtration, the resulting material is dried in a drying cabinet at a temperature of 80° C. to a humidity of 50% and further dried in a rotary evaporator at a temperature 110° C. and a pressure 100 mbar to avoid air oxidation of the material. The material is then ground using a grinder (milled) and the final drying is carried out in a vacuum cabinet at 120° C. for 10 hours to completely remove moisture from the material.

[0045] Thus, a concentrate of SWCNT in polycarbonate with an SWCNT concentration 16.7 wt. % and a PC concentration 83.3 wt. % is produced, which is then used as the modifier. The modifier is a powder.

[0046] If the concentrate is preferred in the form of pellets, it can be passed through an extruder to form pellets for further use. [0047] 2) Preparing a high-performance PC-based composite material.

[0048] 20 g of the resulting modifier is mixed with 20 g of carbon fibers and 160 g of PC polymer using a twin screw extruder. Thus, prepared pellets of the composite material are then used for preparation of the standard samples by injection molding.

[0049] The prepared polymer composite has the following composition: PC polymer—88.33%, SWCNT—1.67%, carbon fibers—10%. The tensile strength of the samples was 64 MPa and the specific resistivity 10.sup.4 Ohm cm.

EXAMPLE 3

[0050] 1) Preparing a modifier.

[0051] 4.2 g of Tuball SWCNT is placed in a beaker with 40 g of caprolactam and heated on a hot plate to 120° C. while continuously purging it with dry nitrogen and stirring with a magnetic stirrer. Stirring is continued for 1 hour to remove moisture from caprolactam and the mixture is then sonicated at 240 W for 10 minutes while purging with dry nitrogen and stirring. C10 catalyst (Bruggemann Group, Germany) in the amount of 1.2 g, and then 0.8 g of C20P activator are added into the dispersion and, after additional stirring for 1 minute, the temperature is increased to 150° C. This initiates polymerization of caprolactam, which usually ends within 15 minutes.

[0052] Thus, an SWCNT concentrate in polyamide 6 with SWCNT concentration 10 wt. % and PA-6 concentration 90 wt. % is produced, which is then used as the modifier. The modifier is a powder.

[0053] The resulting powder is stored in a sealed container in the nitrogen atmosphere. Where necessary, the composite material is melted in an extruder followed by the production of pellets for further use on injection molding machines. [0054] 2) Preparing high-performance polyamide-based composite material.

[0055] 10 g of the resulting modifier is mixed with 323 g of PA-6 polymer using a twin screw extruder. The prepared polymer composition has the following composition: PA-6 polymer—99.7%, SWCNT—0.3%. The polymer composition is produced as pellets, from which standard samples are prepared by injection molding.

[0056] The bending strength measurement shows that elastic modulus increased to 4.5 GPa, and strength was 164 MPa, which is higher than the values for pure PA-6 polymer, for which the respective values are 2.8 GPa and 150 MPa. The resulting values are provided in Table 1.

[0057] 10 g of the resulting modifier is mixed with 290 g of PA-6 polymer and 33.3 g of short carbon fibers using a twin screw extruder. The prepared polymer composition has the following composition: PA-6 polymer—89.7%, carbon fibers—10%, and CNT—0.3%. Standard samples are then prepared by injection molding. The bending strength measurement shows that elastic modulus increased to 9.5 GPa, and strength was 201 MPa, which is higher than the values for pure PA-6 polymer.

[0058] 2 g of the resulting modifier is mixed with 30 g of carbon fibers and 68 g of PA-6 polymer using a twin screw extruder. Pellets of the composite material are prepared. Standard samples are then prepared by injection molding. The prepared polymer composition has the following composition: PA-6 polymer—69.8%, CNT—0.2%, carbon fibers—30%. The bending strength of the samples was 585 MPa, and elastic modulus was 33 GPa. For comparison, a similar composite material that contains 30% carbon fibers but no CNT showed elastic modulus of 30 MPa and bending strength of 450 MPa. The results are provided in Table 1.

[0059] The specific resistivity of the samples was 0.1 Ohm.Math.cm.

EXAMPLE 4

[0060] 1) Preparing a modifier.

[0061] 1 g of Tuball SWCNT is placed in a beaker with 99 g of caprolactam and heated on a hot plate to 100-120° C. while continuously purging with dry nitrogen and stirring with a magnetic stirrer to produce a dispersion. Stirring is continued for 1 hour to remove moisture from caprolactam. The mixture is then sonicated at 240 W for 10 minutes while purging with dry nitrogen and stirring. The resulting dispersion is filtered through a membrane filter with a pore size of 2 μm. A vacuum pump and a 1 L Bunsen flask are used to accelerate the filtration process. To maintain the dispersion temperature, filtration is carried out in an electric oven at a temperature at least 100° C. When the initial dispersion weight is 100 g, the weight of caprolactam that passed through the filter is 97 g. The weight of the concentrate that was left on the filter is 3 g, the concentration of nanotubes in the concentrate is 33.3%. 0.3 g of water is added to said concentrate as a catalyst. Caprolactam polymerization is carried out at a temperature 260° C. for 6 hours followed by drying up in a vacuum cabinet at a temperature 60° C.

[0062] Thus, an SWCNT concentrate in polyamide with an SWCNT concentration 33 wt. % and a PA-6 concentration 67 wt. % is produced, which is then used as a modifier. The modifier is a powder. [0063] 2) Preparing a high-performance polyamide-based composite material.

[0064] 10 g of the resulting modifier is mixed with 20 g of PA-6 polymer and 3.3 g of carbon fibers using a twin screw extruder to produce a high-performance PA-based composite material in a form of pellets, from which standard samples were subsequently prepared by injection molding. The prepared polymer composition has the following composition: PA-6 polymer—80%, CNT—10%, carbon fibers—10%.

[0065] The samples with 10% CNT, have the tensile strength 160 MPa, which is 1.6 times higher than the tensile strength of the PA-6 samples with 10% carbon fibers but without nanotubes.

[0066] The specific resistivity of the samples is 1 Ohm.Math.cm.

EXAMPLE 5

[0067] 1) Preparing a modifier.

[0068] An Exakt three roll mill is used to mix 4 g of Tuball SWCNT, 40 g of caprolactam, and 4 g of water. 110 passes are carried out to prepare a nanotube dispersion. The resulting dispersion in caprolactam is polymerized in a sealed reactor at a temperature 260° C. for 12 hours. When the reactor cools down to room temperature, the resulting material is removed and dried in a vacuum oven at 60° C. for an hour.

[0069] Thus, an SWCNT concentrate in polyamide with an SWCNT concentration 10 wt. % and a PA-6 concentration 90 wt. % is produced, which is then used as the modifier. The modifier is a powder. [0070] 2) Preparing a high-performance polyamide-based composite material.

[0071] To produce a composite material based on a thermoplastic polymer and the resulting modifier, in this example, 1 g of the resulting modifier is mixed with 20 g of carbon fibers and 179 g of PA-6 polymer using a twin screw extruder. Pellets of the composite material are prepared and standard samples are then prepared by injection molding.

[0072] The composition of the resulting composite material is: SWCNT—0.5%, carbon fibers—10%, PA-6—89.5%, and has the measured tensile strength 162 MPa and the specific resistivity 2 Ohm cm.

TABLE-US-00001 TABLE 1 Properties of PA-6 with Tuball SWCNT and carbon fibers Bending Rel. Young's strength, MPa elongation, % modulus, GPa PA-6 150 20 2.8 PA-6 + 0.3% CNT 164 9 4.5 PA-6 + 0.3% CNT + 201 7 9.5 10% carbon fiber PA-6 + 30% carbon 450 3 30 fiber PA-6 + 0.2% CNT + 585 4 33 30% carbon fiber

INDUSTRIAL APPLICABILITY

[0073] The invention can be used in various industries where an increased strength of the parts made of composite thermoplastic materials is required while keeping their low weight, e.g., aerospace, aviation, automotive, as well as mechanical engineering, medicine, manufacture of sports products, as well as in applications where electrical conductivity requirements are imposed on the composite material.

[0074] Having thus described a preferred embodiment, it should be apparent to those skilled in the art that certain advantages of the described method and apparatus have been achieved.

[0075] It should also be appreciated that various modifications, adaptations and alternative embodiments thereof may be made within the scope and spirit of the present invention. The invention is further defined by the following claims. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.