High-heat and high-toughness pa11t composite material and preparation method thereof

Abstract

The application relates to the technical field of nylon materials, in particular to a high-heat-resistance high-toughness PA11T composite material and a preparation method thereof, wherein the high-heat-resistance high-toughness PA11T composite material comprises the following raw materials in parts by weight: PA11T resin 90-110 parts, chopped carbon fibers 10-30 parts, hyperbranched polymer 5-10 parts, modified carbon nanotubes 3-7 parts and a compatilizer 4-8 parts. The high-heat-resistance high-toughness PA11T composite material prepared by the application has excellent heat resistance and toughness.

Description

Technical Field

[0001] This invention relates to the field of nylon materials technology, specifically to a high heat-resistant and high-toughness PA11T composite material and its preparation method. Background Technology

[0002] PA11T is a high-temperature resistant, long-chain, semi-aromatic polyamide formed by the condensation polymerization of 1,11-diaminoundecane and terephthalic acid. It retains the mechanical strength, abrasion resistance, and chemical corrosion resistance of polyamides, while the introduction of a benzene ring structure gives it low water absorption, high dimensional stability, and basic heat resistance, making it a potential key material in high-end fields such as electronics, automotive manufacturing, and aerospace. However, pure PA11T still faces challenges in balancing heat resistance and toughness; traditional melt polycondensation methods result in low molecular weight and easy yellowing and degradation; solution polycondensation methods are costly; and the compatibility of fillers and matrix in blended modified composite materials remains to be solved.

[0003] Patent CN106543718B discloses a high-toughness, high-temperature resistant nylon composite material, comprising the following components by weight: 78-98.5 parts of high-temperature resistant nylon matrix resin; 1-20 parts of toughening modifier; and 0.5-2 parts of antioxidant. This invention uses a star-shaped nylon with a specific single-arm molecular weight and a specific molecular structure containing ether bonds as the core, added as a toughening modifier to the high-temperature resistant nylon matrix resin. This improves both the melt flowability and toughness of the high-temperature resistant nylon matrix resin; and the preparation method is simple and easy to industrialize. However, its toughening effect on the nylon resin is essentially achieved through the deformation and stress transfer of ether bonds, which may impair the heat resistance and mechanical strength of the matrix.

[0004] Patent CN106147224A discloses a high-temperature resistant and thermally conductive nylon composite material, composed of the following components by weight: 100 parts PA66, 40-80 parts high-temperature resistant nylon, 10-50 parts nylon elastomer, 10-30 parts carbon fiber, 20-50 parts thermally conductive filler, 0.2-1.5 parts reactive flow modifier, 0.3-1.2 parts antioxidant, and 0.3-2 parts lubricant. The high-temperature resistant nylon is one or a combination of PA9T, PA10T, PA11T, and PA12T; the reactive flow modifier is Sanstab 2303; and the thermally conductive filler is one or a combination of alumina, aluminum nitride, boron nitride, silicon carbide, and graphite. This material exhibits excellent high-temperature resistance and thermal conductivity, while also possessing good mechanical properties and ease of processing. However, the formula contains extremely high levels of inorganic fillers and carbon fiber fillers, which may lead to problems such as a significant increase in the density of the composite material, a decrease in toughness, and a narrowing of the processing window.

[0005] Therefore, there is an urgent need in the market for a PA11T composite material with high heat resistance and high toughness. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain a PA11T composite material with excellent heat resistance and toughness.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a high heat-resistant and high-toughness PA11T composite material, which, by weight, comprises the following raw materials: 90-110 parts of PA11T resin, 10-30 parts of chopped carbon fiber, 5-10 parts of hyperbranched polymer, 3-7 parts of modified carbon nanotubes, 4-8 parts of compatibilizer, and 0.5-2 parts of antioxidant.

[0008] This application describes a PA11T composite material with excellent heat resistance and toughness obtained by compounding PA11T resin, short-cut carbon fibers, hyperbranched polymers, modified carbon nanotubes, and compatibilizers.

[0009] In some embodiments, the chopped carbon fibers have a length of 3-6 mm and a diameter of 5-10 μm.

[0010] In some embodiments, the hyperbranched polymer is one or more of hyperbranched polyester, hyperbranched polyamide, and hyperbranched polyethylene.

[0011] Preferably, the hyperbranched polymer is a hyperbranched polyamide.

[0012] In some embodiments, the method for preparing the modified carbon nanotubes includes the following steps: A1. Add carbon nanotubes to dichloromethane, cool to 0-5℃, adjust the rotation speed to 500-600 rpm, add anhydrous AlCl3, and sonicate for 20-40 min to obtain a mixed solution; dissolve the acid anhydride reagent in dichloromethane and add it dropwise to the above mixed solution. After the addition is complete, first raise the temperature to room temperature, then heat to 40-60℃, and reflux for 12-48 h to obtain a mixture. A2. Pour the mixture obtained in step A1 into dilute hydrochloric acid at 0-5℃, stir for 3-5 minutes, filter, and wash with dilute hydrochloric acid, deionized water, ethanol and acetone in sequence until the filtrate is neutral and no chloride ions are detected. Dry to obtain pretreated carbon nanotubes. A3. Add the pretreated carbon nanotubes obtained in step A2 and 3-methoxypropylamine to N,N-dimethylformamide, heat to 40-60℃, add activator and catalyst, react for 12-24h, filter, wash and dry to obtain modified carbon nanotubes.

[0013] Preferably, the ratio of carbon nanotubes to dichloromethane is 1:(10-50) ml.

[0014] Preferably, the activator is 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride.

[0015] Preferably, the catalyst is 4-dimethylaminopyridine and / or 1-hydroxybenzotriazole.

[0016] More preferably, the catalyst is 4-dimethylaminopyridine.

[0017] Preferably, the concentration of the dilute hydrochloric acid is 1M, and the ratio of the mixture to the dilute hydrochloric acid is 1g:(10-15)ml.

[0018] This application utilizes a two-step tandem process of Friedel-Crafts acylation and amidation. First, anhydride segments containing benzene rings or double bonds are introduced, followed by the attachment of flexible amines containing ether bonds, to prepare modified carbon nanotubes containing multiple functional groups. The resulting PA11T composite material, prepared by blending this with PA11T resin, chopped carbon fibers, and additives, exhibits excellent heat resistance and toughness. This is likely due to two factors: firstly, the π-π conjugation / hydrogen bonds between the benzene ring groups on the modified carbon nanotubes and the segments of the PA11T resin exhibit strong interactions that are not easily disrupted at high temperatures, allowing the material to maintain high modulus and strength even at high temperatures; secondly, the amide bonds on the modified carbon nanotubes provide good compatibility with PA11T resin, allowing them to be uniformly dispersed in the composite material as "thermal channels" to distribute heat and reduce localized overheating. Furthermore, some residual anhydride groups on the modified carbon nanotubes can react with the terminal amino groups of the PA11T resin, further fixing the modified carbon nanotubes uniformly within the resin network as stress concentration points to dissipate energy, thereby significantly improving the impact toughness of the material and achieving a toughening effect. Meanwhile, under external impact, the ether bonds on the modified carbon nanotubes can absorb and dissipate a large amount of energy through movement, rotation, and slippage, preventing microcrack propagation and further improving the toughness of the composite material.

[0019] In some embodiments, the mass ratio of the carbon nanotubes to anhydrous AlCl3 is 1:(0.001-0.005).

[0020] In some embodiments, the anhydride reagent is maleic anhydride and / or pyromellitic anhydride.

[0021] Preferably, the acid anhydride reagent is pyromellitic tricarboxylic anhydride.

[0022] In some embodiments, the mass ratio of the carbon nanotubes to the acid anhydride reagent is 1:(0.5-1).

[0023] In some embodiments, the ratio of 3-methoxypropylamine to N,N-dimethylformamide is 1:(50-100) ml.

[0024] In some embodiments, the mass ratio of the pretreated carbon nanotubes to 3-methoxypropylamine in step A3 is 1:(0.3-0.7).

[0025] In some embodiments, the mass ratio of 3-methoxypropylamine to the activator is 1:(0.3-0.6).

[0026] In some embodiments, the mass ratio of 3-methoxypropylamine to catalyst is 1:(0.05-0.1).

[0027] In some embodiments, the compatibilizer is one or more of POE-g-GMA, EBA-g-GMA, EMA-g-GMA, POE-g-MAH, and EPDM-g-MAH.

[0028] Preferably, the compatibilizer is POE-g-MAH.

[0029] Another aspect of the present invention provides a method for preparing a high heat-resistant and high-toughness PA11T composite material, comprising the following steps: S1. Premix PA11T resin, hyperbranched polymer, modified carbon nanotubes, and compatibilizer in a high-speed mixer for 5-10 minutes to obtain the premixed material. S2. The premixed material and chopped carbon fiber obtained in step S1 are added to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 200-300 rpm, the extrusion temperature is 290-320℃, and the material is water-cooled, air-dried, and pelletized to obtain PA11T composite material.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) The PA11T composite material prepared by the present invention through PA11T resin, short carbon fiber, hyperbranched polymer, modified carbon nanotube and compatibilizer has excellent heat resistance and toughness.

[0031] (2) This invention uses a two-step process of Friedel-Crafts acylation and amidation to first introduce an active carboxyl group containing a benzene ring, and then connect it to a flexible amine containing an ether bond, thereby preparing modified carbon nanotubes containing benzene rings, ether bonds, and amide bonds. The modified carbon nanotubes generate strong interactions with the PA11T resin segments, such as π-π conjugation and hydrogen bonding, which allows them to be uniformly dispersed in the composite material as "thermal channels" to disperse heat, reduce local overheating, and give the prepared PA11T composite material excellent heat resistance and toughness.

[0032] (3) The residual anhydride groups on the modified carbon nanotubes prepared by this invention can react with the terminal amino groups of PA11T resin, further fixing the modified carbon nanotubes uniformly in the resin network and improving the toughening effect. Under external impact, the ether bonds on the modified carbon nanotubes can absorb and dissipate a large amount of energy, preventing the propagation of microcracks and further improving the toughness of the composite material. Detailed Implementation

[0033] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0034] In the following examples and comparative examples, except for the modified carbon nanotubes, all other compounds and related reagents used were commercially available. The carbon nanotubes had a diameter of 5-10 nm and an average length of 30 μm, and were purchased from Shanghai Maoguo Nanotechnology Co., Ltd.; the chopped carbon fibers had a length of 3-6 mm and an average diameter of 7 μm, and were purchased from Dongyiyang (Jinan) New Materials Co., Ltd.; the amino-terminated hyperbranched polyamide was PB40520, purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.; and POE-g-MAH was purchased from Dongguan Suda Plastic Raw Materials Co., Ltd.

[0035] Preparation Example 1 The preparation method of modified carbon nanotube-1 includes the following steps: A1. Add 10g of carbon nanotubes to 250ml of dichloromethane, cool to 3℃, adjust the rotation speed to 550rpm, add 0.03g of anhydrous AlCl3, and sonicate for 30min to obtain a mixed solution; dissolve 7.5g of pyromellitic anhydride in 50ml of dichloromethane, and add it dropwise to the above mixed solution at a dropping rate of 2 drops / s. After the addition is complete, first heat to room temperature, then heat to 50℃, and reflux for 24h to obtain a mixture. A2. Pour 50g of the mixture obtained in step A1 into 600ml of 1M dilute hydrochloric acid at 3℃, stir for 4min, filter, and wash repeatedly with 1M dilute hydrochloric acid, deionized water, anhydrous ethanol and anhydrous acetone until the filtrate is neutral and no chloride ions are detected. Dry to obtain pretreated carbon nanotubes. A3. Add 10g of the pretreated carbon nanotubes obtained in step A2 and 5g of 3-methoxypropylamine to 750ml of N,N-dimethylformamide, heat to 50℃, add 2.25g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.5g of 4-dimethylaminopyridine, react for 18h, filter, wash successively with N,N-dimethylformamide, deionized water and anhydrous ethanol, and dry to obtain modified carbon nanotube-1.

[0036] Preparation Example 2 The preparation method of modified carbon nanotubes-2 is the same as that in preparation example 1, except that the amount of anhydrous AlCl3 added is 0.07g.

[0037] Preparation Example 3 The preparation method of modified carbon nanotubes-3 is the same as that in preparation example 1, except that the amount of pyromellitic tricarboxylic anhydride added is 12g.

[0038] Preparation Example 4 The preparation method of modified carbon nanotube-4 is the same as that in preparation example 1, except that the amount of 3-methoxypropylamine added is 9g.

[0039] Preparation Example 5 The preparation method of modified carbon nanotubes-5 includes the following steps: A1. Add 10g of carbon nanotubes to 250ml of dichloromethane, cool to 3℃, adjust the rotation speed to 550rpm, add 0.03g of anhydrous AlCl3, and sonicate for 30min to obtain a mixed solution; dissolve 7.5g of pyromellitic anhydride in 50ml of dichloromethane, and add it dropwise to the above mixed solution at a dropping rate of 2 drops / s. After the addition is complete, first heat to room temperature, then heat to 50℃, and reflux for 24h to obtain a mixture. A2. Pour 50g of the mixture obtained in step A1 into 600ml of 1M dilute hydrochloric acid at 3℃, stir for 4min, filter, and wash repeatedly with 1M dilute hydrochloric acid, deionized water, anhydrous ethanol, and anhydrous acetone until the filtrate is neutral and no chloride ions are detected. Dry to obtain modified carbon nanotubes-5.

[0040] Example 1 A high heat-resistant and high-toughness PA11T composite material, by weight, comprises the following raw materials: 100 parts PA11T resin, 20 parts chopped carbon fiber, 7 parts amino-terminated hyperbranched polyamide, 5 parts modified carbon nanotube-1, and 6 parts POE-g-MAH.

[0041] The preparation method of the high heat resistance and high toughness PA11T composite material in this embodiment includes the following steps: S1. PA11T resin, amino-terminated hyperbranched polyamide, modified carbon nanotube-1, and POE-g-MAH are premixed in a high-speed mixer for 7 minutes to obtain the premixed material. S2. The premixed material and chopped carbon fibers obtained in step S1 are added to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 250 rpm, the extrusion temperature is 305℃, and the material is water-cooled, air-dried, and pelletized to obtain PA11T composite material.

[0042] Example 2 A high heat-resistant and high-toughness PA11T composite material, by weight, comprises the following raw materials: 90 parts PA11T resin, 10 parts chopped carbon fiber, 5 parts amino-terminated hyperbranched polyamide, 3 parts modified carbon nanotube-1, and 4 parts POE-g-MAH.

[0043] The preparation method of the high heat resistance and high toughness PA11T composite material in this embodiment includes the following steps: S1. PA11T resin, amino-terminated hyperbranched polyamide, modified carbon nanotube-1, and POE-g-MAH are premixed in a high-speed mixer for 5 minutes to obtain the premixed material. S2. The premixed material and chopped carbon fibers obtained in step S1 are added to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 200 rpm, the extrusion temperature is 290℃, and the material is water-cooled, air-dried, and pelletized to obtain PA11T composite material.

[0044] Example 3 A high heat-resistant and high-toughness PA11T composite material, by weight, comprises the following raw materials: 110 parts PA11T resin, 30 parts chopped carbon fiber, 10 parts amino-terminated hyperbranched polyamide, 7 parts modified carbon nanotube-1, and 8 parts POE-g-MAH.

[0045] The preparation method of the high heat resistance and high toughness PA11T composite material in this embodiment includes the following steps: S1. PA11T resin, amino-terminated hyperbranched polyamide, modified carbon nanotube-1, and POE-g-MAH are premixed in a high-speed mixer for 10 minutes to obtain the premixed material. S2. The premixed material and chopped carbon fibers obtained in step S1 are added to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 300 rpm and the extrusion temperature is 320℃. After water cooling, air drying and pelletizing, PA11T composite material is obtained.

[0046] Example 4 A high heat-resistant and high-toughness PA11T composite material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the functional modified carbon nanotubes-1 are replaced with modified carbon nanotubes-2 in equal amounts.

[0047] Example 5 A high heat-resistant and high-toughness PA11T composite material and its preparation method are described. The specific implementation method is the same as that in Example 1, except that modified carbon nanotube-1 is replaced with modified carbon nanotube-3 in equal amounts.

[0048] Example 6 A high heat-resistant and high-toughness PA11T composite material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that modified carbon nanotube-1 is replaced with modified carbon nanotube-4 in equal amounts.

[0049] Example 7 A high heat-resistant and high-toughness PA11T composite material and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that modified carbon nanotube-1 is replaced with modified carbon nanotube-5 in equal amounts.

[0050] Comparative Example 1 A PA11T composite material and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the modified carbon nanotubes-1 are replaced with carbon nanotubes in equal amounts.

[0051] Performance testing The PA11T composite materials obtained in the above embodiments and comparative examples were tested: (1) Heat resistance: The heat distortion temperature (1.82MPa) of each PA11T composite material was tested according to the test method of ASTM D648 to evaluate its heat resistance.

[0052] (2) Toughness: The flexural strength of each PA11T composite material was tested according to the test method of ASTM D790 to evaluate its toughness.

[0053] The test results are shown in Table 1: Table 1

[0054] As shown in Table 1, the PA11T composite materials in Examples 1-3 of this invention exhibit excellent heat resistance and toughness. A comparison of Examples 4, 5, and Example 1 reveals that altering the ratio of carbon nanotubes to anhydrous AlCl3 intensifies the excessive electrophilic addition or Friedel-Crafts alkylation / acylation reaction of the anhydride reagent on the carbon nanotubes themselves. This may disrupt the conjugated structure of the carbon nanotubes, causing excessive defects or even breakage in the tube walls, ultimately impairing their intrinsic excellent properties and leading to a decrease in the heat resistance and toughness of the PA11T composite material. A comparison of Example 6 and Example 1 shows that altering the ratio of pretreated carbon nanotubes to 3-methoxypropylamine may result in excessively thick... The modification layer weakens the interfacial interaction between carbon nanotubes and the matrix, resulting in a slight decrease in the heat resistance and toughness of the PA11T composite material. A comparison between Example 7 and Example 1 shows that not using 3-methoxypropylamine to modify the pretreated carbon nanotubes reduces the heat resistance and toughness of the PA11T composite material. A comparison between Example 8 and Example 1 shows that not using dihydro-3-[3-(triethoxysilyl)propyl]furan-2,5-dione ethanol to modify the carbon nanotubes reduces the mechanical properties and toughness of the high-heat-resistant and high-toughness PA11T composite material. A comparison between Comparative Example 1 and Example 1 shows that without modification of the carbon nanotubes, the PA11T composite material exhibits poor heat resistance and toughness.

[0055] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high heat-resistant and high-toughness PA11T composite material, characterized in that, By weight, it includes the following raw materials: 90-110 parts PA11T resin, 10-30 parts chopped carbon fiber, 5-10 parts hyperbranched polymer, 3-7 parts modified carbon nanotubes, and 4-8 parts compatibilizer. The method for preparing the modified carbon nanotubes includes the following steps: A1. Add carbon nanotubes to dichloromethane, cool to 0-5℃, adjust the rotation speed to 500-600 rpm, add anhydrous AlCl3, and sonicate for 20-40 min to obtain a mixed solution; dissolve the acid anhydride reagent in dichloromethane and add it dropwise to the above mixed solution. After the addition is complete, first raise the temperature to room temperature, then heat to 40-60℃, and reflux for 12-48 h to obtain a mixture. A2. Pour the mixture obtained in step A1 into dilute hydrochloric acid at 0-5℃, stir for 3-5 minutes, filter, and wash with dilute hydrochloric acid, deionized water, ethanol and acetone in sequence until the filtrate is neutral and no chloride ions are detected. Dry to obtain pretreated carbon nanotubes. A3. Add the pretreated carbon nanotubes obtained in step A2 and 3-methoxypropylamine to N,N-dimethylformamide, heat to 40-60℃, add activator and catalyst, react for 12-24h, filter, wash and dry to obtain modified carbon nanotubes.

2. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The chopped carbon fibers have a length of 3-6 mm and a diameter of 5-10 μm.

3. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The hyperbranched polymer is one or more of hyperbranched polyester, hyperbranched polyamide, and hyperbranched polyethylene.

4. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The mass ratio of the carbon nanotubes to anhydrous AlCl3 is 1:(0.001-0.005).

5. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The acid anhydride reagent is maleic anhydride and / or pyromellitic anhydride.

6. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The mass ratio of the carbon nanotubes to the acid anhydride reagent is 1:(0.5-1).

7. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The mass ratio of the pretreated carbon nanotubes to 3-methoxypropylamine in step A3 is 1:(0.3-0.7).

8. The high heat-resistant and high-toughness PA11T composite material according to claim 1, characterized in that, The compatibilizer is one or more of POE-g-GMA, EBA-g-GMA, EMA-g-GMA, POE-g-MAH, and EPDM-g-MAH.

9. A method for preparing the high heat-resistant and high-toughness PA11T composite material according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Premix PA11T resin, hyperbranched polymer, modified carbon nanotubes, and compatibilizer in a high-speed mixer for 5-10 minutes to obtain the premixed material. S2. The premixed material and chopped carbon fiber obtained in step S1 are added to a twin-screw extruder for extrusion granulation. The feeding speed of the twin-screw extruder is 200-300 rpm, the extrusion temperature is 290-320℃, and the material is water-cooled, air-dried, and pelletized to obtain PA11T composite material.

Images