High mechanical performance barrier polyamide composite and method for its preparation

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a high-mechanical-property barrier polyamide composite material and a preparation method thereof. The composite material comprises the following components in parts by weight: 80-90 parts of long-chain aliphatic polyamide, 10-20 parts of maleic anhydride grafted compatibilizer, 8-16 parts of barrier agent, and 0-6 parts of processing aid. The barrier agent is composed of pentaerythritol-based polyol, ethylene-acrylic acid ionomer and nano-montmorillonite in a mass ratio of (0.05-0.2):(0.4-0.8):1. The addition of the pentaerythritol-based polyol and the ethylene-acrylic acid ionomer improves the dispersion performance of the nano-montmorillonite, and is beneficial to the formation of a more perfect barrier network. Through the physical barrier of the nano-montmorillonite and the chemical bond densification effect of the pentaerythritol-based polyol and the ethylene-acrylic acid ionomer, a double barrier is formed for gas molecules, the permeation rate is significantly reduced, and the mechanical property of the composite material is improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a high-mechanical-performance barrier polyamide composite material and its preparation method. Background Technology

[0002] Composite materials are new materials made by combining several different materials, such as organic polymers, inorganic non-metals, or metals, through appropriate composite processes. Through design, the properties of the original components are correlated and complemented, resulting in superior overall performance. Environmental friendliness and the need for energy conservation and emission reduction have led to plastics replacing metals in many applications, reducing the weight of cars, airplanes, and ships, thereby lowering fuel consumption.

[0003] Polymer composites possess advantages such as low weight and high stiffness, leading to their widespread application in numerous fields including automotive, aerospace, marine, and sporting goods industries. Thermoplastic composites exhibit high modulus and strength; reinforcing thermoplastic composites to replace metal components can reduce product costs and weight. Given their widespread use in structural components as a substitute for high-fatigue-strength metals, improving the long-term reliability and service life of composite materials is imperative.

[0004] Polyamides are a general term for polymers containing repeating amide groups in their main chain. There are many types of polyamides, which can be broadly classified structurally into aliphatic polyamides, semi-aromatic polyamides, and fully aromatic polyamides. Depending on the monomers used in synthesis, aliphatic polyamides obtained by ring-opening polymerization of lactam monomers or self-condensation polymerization of amino acids are often denoted as PAn, such as PA6, PA11, and PA12, where n is the number of carbon atoms in the repeating unit structure. Aliphatic polyamides obtained by condensation polymerization of diacids and diamines are denoted as PAmn, such as PA66, PA610, and PA612, where m is the number of carbon atoms in the diamine and n is the number of carbon atoms in the diacid. Polyamides possess high mechanical strength, good wear resistance, self-lubrication, and excellent chemical resistance, and are easy to process and modify. Polyamides have been widely used in textiles, automobiles, electronics, aerospace, construction, gas storage, and other fields, becoming one of the most important synthetic materials in daily life.

[0005] Polyamide composites are widely used in gas transportation. The application of composite material hydrogen storage cylinders with plastic liners can improve the economic efficiency of tubular containers, but high aspect ratio cylinders are characterized by long bodies and weak rigidity. In recent years, with the development of new energy sources, barrier materials prepared from polyamides have received increasing attention. Chinese invention patent CN117430943A discloses an ultra-high hydrogen barrier nylon-based composite material for hydrogen storage cylinders and its preparation method, addressing the technical problems of the need to further improve the hydrogen barrier performance of existing nylon-based composite materials and the poor mechanical properties exhibited by nylon-based composite materials in hydrogen cylinders. The ultra-high hydrogen barrier nylon-based composite material for hydrogen storage cylinders is prepared by using modified nylon, crosslinking additives, polystyrene, polypropylene, and auxiliary additives in a ratio of 11g:2g:2g:4g:1g to form a composite film. The composite film is then completely immersed in a beaker containing a composite dispersion and modified to obtain the final product. This technology not only effectively improves the hydrogen barrier properties of nylon-based composite materials but also enhances their mechanical properties, resulting in good durability and stability when used in hydrogen cylinders. However, the complex manufacturing process and high cost limit its industrial application. Summary of the Invention

[0006] In view of this, the present invention provides a high mechanical property barrier polyamide composite material and its preparation method. The composite material not only has excellent mechanical properties, but also has high gas barrier properties, and can be used as a gas storage cylinder material, thus expanding the applications of polyamide composite materials.

[0007] The present invention solves the above-mentioned technical problems by means of the following technical solution:

[0008] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0009] 80-90 parts of long-chain aliphatic polyamide, 10-20 parts of maleic anhydride graft compatibilizer, 8-16 parts of barrier agent, and 0-6 parts of processing aid.

[0010] The barrier agent is composed of pentaerythritol-based polyol, ethylene-acrylic acid ionomer, and nano-montmorillonite in a mass ratio of (0.05-0.2):(0.4-0.8):1.

[0011] Compared to short-chain aliphatic polyamides, long-chain aliphatic polyamides exhibit superior impact resistance and processability, significantly improving the low-temperature resistance of composite materials. However, long-chain aliphatic polyamides have poor barrier properties. To further enhance their barrier performance, this invention incorporates a certain amount of pentaerythritol-based polyol, ethylene-acrylic acid ionomer, and nano-montmorillonite as composite barrier agents.

[0012] Nano-montmorillonite is a two-dimensional sheet material that can be exfoliated during polymer melt processing and uniformly and parallelly dispersed in the polymer matrix. When small gas molecules attempt to pass through the composite material, they cannot directly penetrate the rigid nano-montmorillonite sheets. Gas molecules must travel along tortuous paths, bypassing these impenetrable sheets, which significantly increases the effective diffusion path length. Nano-montmorillonite has an extremely high aspect ratio, thus significantly reducing gas permeability even at low concentrations. However, nano-montmorillonite has poor compatibility with polyamides, making it difficult to completely exfoliate and uniformly disperse in the polyamide matrix, leading to agglomeration. Agglomeration reduces the effectiveness of the aspect ratio, becoming a defect and ultimately reducing the barrier properties of the polyamide composite. Although existing technologies have improved the compatibility of nano-montmorillonite with polyamide resins to some extent through organic modification, the improvement in barrier effect is limited, and it also reduces the temperature resistance of the composite material.

[0013] To address the aforementioned problems of nano-montmorillonite, this invention adds a certain amount of pentaerythritol-based polyol and ethylene-acrylic acid ionomer to a long-chain aliphatic polyamide-nano-montmorillonite system. This method eliminates the need for complex modification of the nano-montmorillonite, instead combining three materials with different barrier-enhancing mechanisms to synergistically solve the technical problem of decreased barrier properties during the use of long-chain aliphatic polyamides.

[0014] Among them, nano-montmorillonite serves as the core of the physical barrier. Its high aspect ratio lamellars form a physical barrier within the polyamide matrix, forming the framework that enhances intrinsic barrier properties. Ethylene-acrylic acid ionomer, as a multifunctional interfacial compatibilizer, acts as a bridge and toughener. The nonpolar ethylene segments in the ethylene-acrylic acid ionomer are compatible with the aliphatic chain portion of the long-chain aliphatic polyamide, while the polar carboxylic acid metal salt groups can form ion-dipole interactions with the amide groups of the polyamide, and also interact with the hydroxyl groups of pentaerythritol and the polar points on the surface of the montmorillonite lamellars. This significantly improves the interfacial adhesion between montmorillonite and the polyamide matrix, promotes montmorillonite dispersion, and prevents interfacial defects. Moreover, due to the physical cross-linking and densification effect of its internal ionic clusters, the ethylene-acrylic acid ionomer itself possesses excellent barrier properties, forming secondary barrier regions within the polyamide matrix. Furthermore, the ethylene-acrylic acid ionomer exhibits good toughness, which can buffer the brittleness introduced by the nanofillers and improve the overall toughness of the composite material. Pentaerythritol-based polyols exhibit good dispersibility and contain highly polar hydroxyl groups in their molecules. These hydroxyl groups can protect the amide bonds of polyamides from moisture plasticization, stabilizing the barrier properties of polyamides in humid environments. Furthermore, during processing, pentaerythritol-based polyols can act as linkers. Their hydroxyl groups can undergo esterification or amidation reactions with the terminal amino / carboxyl groups of polyamides, the polar groups on the surface of nano-montmorillonite, and the carboxyl groups of ionomers, or be reinforced through hydrogen bonding networks to form a certain cross-linked network. This further restricts chain segment movement, improves the thermal stability of the composite material, and reduces permeability.

[0015] In one embodiment, the long-chain aliphatic polyamide is one or more of polyamide 610, polyamide 612, polyamide 1010, polyamide 11, polyamide 12, polyamide 1212, and polyamide 1012. Specifically, the long-chain aliphatic polyamide is polyamide 610 or polyamide 612; selecting short-chain and long-chain units to copolymerize the polyamide can better improve the mechanical properties of the composite material.

[0016] In one embodiment, the maleic anhydride graft compatibilizer is a maleic anhydride grafted olefin polymer.

[0017] In one embodiment, the maleic anhydride graft compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polystyrene, maleic anhydride-grafted ethylene octene copolymer, and maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber. The maleic anhydride graft compatibilizer not only improves the mechanical properties of polyamide composites, but also, through the interaction of the maleic anhydride groups with the polar groups on the surface of montmorillonite sheets, "anchors" the nano-montmorillonite to the polyamide matrix, preventing the formation of interfacial defects and enabling effective stress transfer.

[0018] In one embodiment, the pentaerythritol-based polyol is one or more of pentaerythritol monopentaerythritol, dipentaerythritol, and tripentaerythritol.

[0019] In one embodiment, the ethylene-acrylic acid ionomer is saline resin. Specifically, saline resin 9320 can be selected.

[0020] The addition of pentaerythritol-based polyols and ethylene-acrylic acid ionomers improves the dispersion properties of nano-montmorillonite, facilitating the formation of a more complete barrier network. Through the physical barrier effect of nano-montmorillonite and the densification effect of the chemical bonds of pentaerythritol-based polyols and ethylene-acrylic acid ionomers, a dual barrier is formed against gas molecules, significantly reducing permeability. The toughening effect of the ethylene-acrylic acid ionomers can counteract the brittleness caused by the rigid nanosheets and cross-linked structure, enabling the composite material to achieve high barrier properties while maintaining good flexibility and impact resistance, which is crucial for components subjected to pressure cycles, such as the inner liner of hydrogen storage cylinders. The small-molecule pentaerythritol-based polyols have good dispersibility in polyamide melts and can supplement cross-linking, improving the densification degree of the composite material. It is worth noting that, as a small-molecule filler, the amount of pentaerythritol-based polyols should not be excessive; otherwise, there is a risk of migration or seepage to the surface during processing and use, affecting the barrier properties and mechanical properties of the composite material. Specifically, the amount of barrier agent can be 8, 9, 10, 11, 12, 13, 14, 15, or 16 parts. Further, the amount of barrier agent can be 10-13 parts. A suitable amount of barrier agent can fully utilize its barrier properties while avoiding excessive filler leading to dispersion difficulties, effectively balancing barrier performance and mechanical properties. Furthermore, the barrier agent is composed of pentaerythritol-based polyol, ethylene-acrylic acid ionomer, and nano-montmorillonite in a mass ratio of (0.1-0.2):(0.45-0.65):1. By adjusting the amount of ethylene-acrylic acid ionomer, its barrier and cross-linking effects can be improved, preventing excessive cross-linking of the ethylene-acrylic acid ionomer from reducing the performance of the composite material.

[0021] In one embodiment, the processing aid is one or more of coupling agents, lubricants, antioxidants, flow modifiers, release agents, plasticizers, and heat stabilizers.

[0022] In one embodiment, the coupling agent is one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents; the antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants.

[0023] On the other hand, the present invention also provides a method for preparing a high-mechanical-performance barrier polyamide composite material, comprising the following steps:

[0024] (1) Mix long-chain aliphatic polyamide, maleic anhydride graft compatibilizer, barrier agent and processing aid evenly to obtain a mixture;

[0025] (2) The mixture is added to a twin-screw extruder, and after melting, extrusion and granulation, a high mechanical property barrier polyamide composite material is obtained.

[0026] In one embodiment, the twin-screw extruder has a screw speed of 200-500 r / min and an extrusion temperature of 200-300°C.

[0027] Beneficial effects:

[0028] This invention adds a certain amount of pentaerythritol-based polyol and ethylene-acrylic acid ionomer to a long-chain aliphatic polyamide-nanomontmorillonite system. Combining these three materials with different barrier-enhancing mechanisms aims to synergistically address the technical problem of low gas barrier properties in long-chain aliphatic polyamides. Nanomontmorillonite serves as the core of the physical barrier; its high aspect ratio layers form a physical barrier within the polyamide matrix, forming the framework for enhancing intrinsic barrier properties. Ethylene-acrylic acid ionomer acts as a multifunctional interfacial compatibilizer, bridging and toughening the surface. Pentaerythritol-based polyol exhibits good dispersibility and contains highly polar hydroxyl groups, which can protect the amide bonds of the polyamide from moisture plasticization, stabilizing the barrier properties of the polyamide in humid environments. The addition of pentaerythritol-based polyol and ethylene-acrylic acid ionomer improves the dispersion properties of nanomontmorillonite, facilitating the formation of a more complete barrier network. Through the physical barrier of nano-montmorillonite and the densification effect of the chemical bonds of pentaerythritol-based polyols and ethylene-acrylic acid ionomers, a dual barrier is formed for gas molecules, which significantly reduces permeability and improves the mechanical properties of composite materials. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0030] Unless otherwise specified, the raw material types and preparation processes used in the following examples and comparative examples are the same.

[0031] Specifically, the preparation method of the high mechanical property barrier polyamide composite material includes the following steps:

[0032] (1) Mix long-chain aliphatic polyamide, maleic anhydride graft compatibilizer, barrier agent and processing aid evenly to obtain a mixture;

[0033] (2) The mixture is added to a twin-screw extruder, and after melting, extrusion and granulation, a high mechanical property barrier polyamide composite material is obtained; the screw speed of the twin-screw extruder is 400 r / min and the extrusion temperature is 230℃.

[0034] Under the same conditions, the high mechanical properties barrier polyamide composite materials prepared in each embodiment and comparative example were prepared into standard samples, and their tensile strength (refer to GB / T1040-92), notched impact strength (refer to GB / T1843-1996), and hydrogen permeability coefficient (refer to JIS K7126-1) were tested respectively.

[0035] Example 1

[0036] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0037] The mixture comprises 80 parts of long-chain aliphatic polyamide 610, 10 parts of maleic anhydride-grafted polyethylene, 8 parts of a barrier agent, and processing aids (0.5 parts of antioxidant 168, 1 part of coupling agent KH550, and 1 part of lubricant calcium stearate). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.05:0.4:1. The tensile strength is tested to be 61.2 MPa, and the notched impact strength is 5.89 kJ / m². 2 The hydrogen permeability coefficient is 1.47 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0038] Example 2

[0039] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0040] The mixture comprises 90 parts of long-chain aliphatic polyamide 610, 20 parts of maleic anhydride-grafted polyethylene, 13 parts of a barrier agent, and processing aids (2 parts of antioxidant 1010, 2 parts of coupling agent KH550, and 2 parts of lubricant calcium stearate). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.2:0.7:1. The tensile strength is tested to be 56.3 MPa, and the notched impact strength is 6.36 kJ / m. 2 The hydrogen permeability coefficient is 0.95 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0041] Example 3

[0042] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0043] The composition comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 16 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.1:0.6:1. The tensile strength is tested to be 57.2 MPa, and the notched impact strength is 6.04 kJ / m. 2 The hydrogen permeability coefficient is 1.12 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0044] Example 4

[0045] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0046] The composition comprises 80 parts of long-chain aliphatic polyamide 610, 18 parts of maleic anhydride-grafted EPDM rubber, 12 parts of a barrier agent, and processing aids (0.5 parts of antioxidant 1010, 2 parts of coupling agent KH550, and 1 part of lubricant talc). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.05:0.7:1. The tensile strength is tested to be 55.1 MPa, and the notched impact strength is 5.92 kJ / m². 2 The hydrogen permeability coefficient is 1.31 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0047] Example 5

[0048] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0049] The mixture comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 12 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.1:0.8:1. The tensile strength is tested to be 56.8 MPa, and the notched impact strength is 6.11 kJ / m. 2 The hydrogen permeability coefficient is 1.24 × 10⁻⁶. -10 cm 3·cm / (cm 2 ·s·cmHg).

[0050] Example 6

[0051] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0052] The mixture comprises 82 parts of long-chain aliphatic polyamide 610, 13 parts of maleic anhydride-grafted ethylene-octene copolymer, 10 parts of barrier agent, and processing aids (0.8 parts of antioxidant 1010, 1.2 parts of coupling agent KH550, and 1.2 parts of lubricant calcium stearate). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.12:0.5:1. The tensile strength is tested to be 58.2 MPa, and the notched impact strength is 6.22 kJ / m. 2 The hydrogen permeability coefficient is 1.08 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0053] Example 7

[0054] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0055] The composition comprises 88 parts of long-chain aliphatic polyamide 610, 17 parts of maleic anhydride-grafted EPDM rubber, 11 parts of a barrier agent, and processing aids (1.6 parts of antioxidant 168, 1.8 parts of coupling agent KH550, and 1.8 parts of lubricant zinc stearate). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.17:0.65:1. The tensile strength is 61.1 MPa, and the notched impact strength is 6.07 kJ / m². 2 The hydrogen permeability coefficient is 1.30 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0056] Example 8

[0057] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0058] The mixture comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 12 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.1:0.6:1. The tensile strength is tested to be 60.2 MPa, and the notched impact strength is 6.35 kJ / m. 2 The hydrogen permeability coefficient is 0.88 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0059] Comparative Example 1

[0060] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0061] The mixture comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 12 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of Salin resin 9320 and nano-montmorillonite in a mass ratio of 0.7:1. The tensile strength is tested to be 56.1 MPa, and the notched impact strength is 5.13 kJ / m. 2 The hydrogen permeability coefficient is 3.31 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0062] Comparative Example 2

[0063] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0064] The composition comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 12 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of dipentaerythritol and nano-montmorillonite in a mass ratio of 0.7:1. The tensile strength is tested to be 48.8 MPa, and the notched impact strength is 4.25 kJ / m. 2 The hydrogen permeability coefficient is 4.38 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0065] Comparative Example 3

[0066] A high-mechanical-performance barrier polyamide composite material, comprising the following components in parts by weight:

[0067] The composition comprises 85 parts of long-chain aliphatic polyamide 610, 15 parts of maleic anhydride-grafted ethylene-octene copolymer, 12 parts of barrier agent, and processing aids (1 part of antioxidant 1010, 1.5 parts of coupling agent KH550, and 1.5 parts of lubricant talc). The barrier agent is composed of dipentaerythritol, saline resin 9320, and nano-montmorillonite in a mass ratio of 0.6:0.1:1. The tensile strength is tested to be 50.8 MPa, and the notched impact strength is 4.74 kJ / m. 2 The hydrogen permeability coefficient is 2.87 × 10⁻⁶. -10 cm 3 ·cm / (cm 2 ·s·cmHg).

[0068] As can be seen from the above examples and comparative examples, the present invention adds a certain amount of pentaerythritol-based polyol and ethylene-acrylic acid ionomer to the long-chain aliphatic polyamide-nanomontmorillonite system. Combining these three materials with different barrier-reinforcing mechanisms solves the technical problem of low gas barrier properties in long-chain aliphatic polyamides. Among them, nanomontmorillonite is the core of physical barrier; its high aspect ratio layers form a physical barrier in the polyamide matrix, serving as the framework for improving intrinsic barrier properties. Ethylene-acrylic acid ionomer, as a multifunctional interface compatibilizer, can act as a bridge and toughen agent. Moreover, due to the physical cross-linking and densification effect of its internal ionic clusters, ethylene-acrylic acid ionomer itself has excellent barrier properties, forming secondary barrier regions in the polyamide matrix. Pentaerythritol-based polyol has good dispersibility and its molecules contain highly polar hydroxyl groups, which can protect the amide bonds of the polyamide from moisture plasticization. Simultaneously, during processing, pentaerythritol-based polyol can also form a certain cross-linking network, further restricting chain segment movement, improving the thermal stability of the composite material, and reducing permeability.

[0069] Specifically, compared to Example 8, Comparative Examples 1 and 2 lacked pentaerythritol-based polyol and ethylene-acrylic acid ionomer, respectively, resulting in a certain degree of reduction in their mechanical properties and gas barrier properties. This indicates that the addition of the small molecule compounds pentaerythritol-based polyol and ethylene-acrylic acid ionomer improved the dispersion performance of nano-montmorillonite, which is beneficial for forming a more complete barrier network. In contrast, Comparative Example 3 had too much pentaerythritol-based polyol and too little ethylene-acrylic acid ionomer, resulting in a significant decrease in the gas barrier properties of the composite material. This suggests that as a small molecule filler, the amount of pentaerythritol-based polyol should not be excessive, otherwise it will affect the mechanical and barrier properties of the composite material.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-mechanical-performance barrier polyamide composite material, characterized in that, It contains the following components in parts by weight: 80-90 parts of long-chain aliphatic polyamide, 10-20 parts of maleic anhydride graft compatibilizer, 8-16 parts of barrier agent, and 0-6 parts of processing aid. The barrier agent is composed of pentaerythritol-based polyol, ethylene-acrylic acid ionomer, and nano-montmorillonite in a mass ratio of (0.05-0.2):(0.4-0.8):

1.

2. The high mechanical performance barrier polyamide composite material as described in claim 1, characterized in that, The long-chain aliphatic polyamide is one or more of polyamide 610, polyamide 612, polyamide 1010, polyamide 11, polyamide 12, polyamide 1212, and polyamide 1012.

3. The high mechanical property barrier polyamide composite material as described in claim 1, characterized in that, The maleic anhydride graft compatibilizer is a maleic anhydride grafted olefin polymer.

4. The high mechanical property barrier polyamide composite material as described in claim 1, characterized in that, The maleic anhydride graft compatibilizer is one or more of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, maleic anhydride-grafted polystyrene, maleic anhydride-grafted ethylene octene copolymer, and maleic anhydride-grafted ethylene propylene diene monomer (EPDM) rubber.

5. The high mechanical performance barrier polyamide composite material as described in claim 1, characterized in that, The pentaerythritol-based polyol is one or more of pentaerythritol monopentaerythritol, dipentaerythritol, and tripentaerythritol.

6. The high mechanical property barrier polyamide composite material as described in claim 1, characterized in that, The ethylene-acrylic acid ionomer is saline resin.

7. The high mechanical property barrier polyamide composite material as described in claim 1, characterized in that, The processing aid is one or more of the following: coupling agent, lubricant, antioxidant, flow modifier, release agent, plasticizer, and heat stabilizer.

8. The high mechanical property barrier polyamide composite material as described in claim 7, characterized in that, The coupling agent is one or more of silane coupling agents, titanate coupling agents, and aluminate coupling agents; the antioxidant is one or more of hindered phenolic antioxidants and phosphite antioxidants.

9. The method for preparing a high-mechanical-performance barrier polyamide composite material as described in claim 1, characterized in that, Includes the following steps: (1) Mix long-chain aliphatic polyamide, maleic anhydride graft compatibilizer, barrier agent and processing aid evenly to obtain a mixture; (2) The mixture is added to a twin-screw extruder, and after melting, extrusion and granulation, a high mechanical property barrier polyamide composite material is obtained.

10. The method for preparing a high-mechanical-performance barrier polyamide composite material as described in claim 9, characterized in that, The twin-screw extruder has a screw speed of 200-500 r / min and an extrusion temperature of 200-300℃.