High-density polyethylene materials with high hydrogen barrier properties, their preparation methods and applications

Abstract

This application relates to the field of materials technology, and discloses a high-density polyethylene material with high hydrogen barrier properties, its preparation method, and its application. The material comprises, by weight, 100 parts high-density polyethylene and 1-5 parts ionic liquid; the high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.246 × 10⁻⁶ under conditions of 10 MPa and 7°C. ‑16 mol·m / (m 2 The high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.447 × 10⁻⁶ Pa at 70 MPa and 20°C. ‑16 mol·m / (m 2 The technical solution provided in this application can improve the hydrogen barrier capability of high-density polyethylene without sacrificing its original performance.

Description

Technical Field

[0001] This application relates to the field of materials technology, and in particular to a high-density polyethylene material with high hydrogen barrier properties, its preparation method and application. Background Technology

[0002] High-density polyethylene (HDPE) is inadequate in hydrogen barrier properties, mainly due to its nonpolar linear and semi-crystalline structure, which leads to high hydrogen permeability. Existing technologies, such as filling with nanomaterials or blending with high-barrier polymers, can improve barrier properties, but often affect mechanical properties and thermal processing performance, and face problems such as poor dispersibility and insufficient compatibility.

[0003] To solve this technical challenge, it is necessary to improve the hydrogen barrier properties of HDPE without sacrificing its original performance, especially for applications in the storage, transportation, and safety requirements of hydrogen energy. Summary of the Invention

[0004] This application provides a high-density polyethylene material with high hydrogen barrier performance, its preparation method and application, which achieves the technical effect of improving its hydrogen barrier ability without sacrificing the original performance of high-density polyethylene.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include:

[0006] In one aspect, embodiments of this application provide a high-density polyethylene material with high hydrogen barrier properties, comprising, by weight, 100 parts of high-density polyethylene and 1-5 parts of ionic liquid; the high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.246 × 10⁻⁶ under conditions of 10 MPa and 7°C. -16 mol·m / (m 2 The hydrogen permeability coefficient of the high-density polyethylene material is less than or equal to 6.447 × 10⁻⁶ Pa under conditions of 70 MPa and 20°C. -16 mol·m / (m 2 ·s·Pa).

[0007] This embodiment demonstrates how adding an appropriate amount of ionic liquid to high-density polyethylene (HDPE) can effectively improve its hydrogen barrier properties. Within the addition range of 1 to 5 parts, the ionic liquid optimizes the microstructure of HDPE, enhances intermolecular interactions, and significantly reduces the hydrogen permeability coefficient. Under conditions of 10 MPa and 7°C, and 70 MPa and 20°C, the hydrogen permeability coefficient of the HDPE material is less than or equal to 6.246 × 10⁻⁶. -16 mol·m / (m 2 ·s·Pa) and 6.447×10 -16 mol·m / (m 2The ionic liquid exhibits excellent hydrogen barrier properties (·s·Pa). However, the amount of ionic liquid added needs to be strictly controlled. Below 1 part, the barrier performance improvement is not significant, while above 5 parts may disturb the microstructure of the high-density polyethylene material, thus affecting its mechanical and thermal processing properties. By precisely controlling the amount of ionic liquid added, it is possible to improve hydrogen barrier performance while maintaining the mechanical and thermal processing properties of the high-density polyethylene material, achieving an optimized balance of performance.

[0008] In one embodiment, the high-density polyethylene material has an elastic modulus ≥1179.68MPa, a yield strength ≥19.90MPa, a tensile strength ≥20.79MPa, and a maximum elongation ≥402.34%.

[0009] The high-density polyethylene (HDPE) material in this embodiment possesses excellent mechanical properties, such as an elastic modulus ≥1179.68 MPa, yield strength ≥19.90 MPa, tensile strength ≥20.79 MPa, and maximum elongation ≥402.34%, which significantly improves its hydrogen barrier properties while maintaining mechanical stability. These properties ensure that the HDPE material is not easily deformed or cracked when subjected to external pressure, dynamic loads, or impacts, thereby effectively reducing the possibility of hydrogen permeation. Furthermore, these improved mechanical properties also ensure that the HDPE material maintains good shape stability and ductility during hot processing, meeting the requirements for processing precision and material reliability in the manufacturing process.

[0010] In one embodiment, the high-density polyethylene material has a melting initiation temperature ≥123.15℃, a melting peak temperature ≥133.99℃, and a melting termination temperature ≥143.40℃.

[0011] This embodiment optimizes the melting initiation temperature (≥123.15℃), melting peak temperature (≥133.99℃), and melting termination temperature (≥143.40℃) of high-density polyethylene (HDPE) material, thereby improving its hydrogen barrier properties while maintaining its mechanical and thermal processing properties. A higher melting temperature helps increase the crystallinity of the material, thereby enhancing the close packing of molecules and improving its hydrogen barrier properties. Furthermore, a higher melting temperature ensures the stability of the material during thermal processing, provides a wider temperature window, and avoids performance degradation due to improper processing. Therefore, reasonable control of the melting temperature can ensure high hydrogen barrier performance while maintaining the material's strength, rigidity, and good processing characteristics, ensuring its stability in high-performance applications.

[0012] In one embodiment, the PE grade of the high-density polyethylene is PE80 or higher.

[0013] This embodiment uses high-density polyethylene (HDPE) of grade 80 or higher, which significantly improves the hydrogen barrier performance of HDPE while maintaining its excellent mechanical and thermal processing properties. HDPE of grade 80 or higher has a more regular microstructure and molecular chain arrangement, resulting in higher density and lower hydrogen permeability in hydrogen barrier performance. Furthermore, materials of grade 80 or higher have stronger compressive strength and impact resistance, enabling them to withstand higher internal pressures during long-term use, maintaining structural stability and avoiding performance degradation due to external impacts or aging. By combining with ionic liquids, the hydrogen barrier effect can be further enhanced without affecting its mechanical properties and thermal processing properties, ensuring the long service life and high reliability of HDPE in practical applications. Therefore, using HDPE of grade 80 or higher achieves the optimal balance between hydrogen barrier performance and the overall performance of HDPE.

[0014] In one embodiment, the PE grade of the high-density polyethylene is selected from PE80 or PE100.

[0015] This embodiment uses high-density polyethylene (HDPE) of PE80 or PE100, which significantly improves hydrogen barrier performance while maintaining excellent mechanical and thermal processing properties. Because PE80 and PE100 have more regular molecular chain arrangements and a denser microstructure, hydrogen diffusion is effectively hindered, thus enhancing the hydrogen barrier effect. Furthermore, these materials maintain good mechanical properties, such as tensile strength and impact resistance, under high temperature and high pressure conditions, while their thermal processing performance is also guaranteed, ensuring convenient molding in practical applications. When combined with ionic liquids, PE80 and PE100 further optimize crystallization behavior and molecular chain arrangement, enhancing the hydrogen barrier effect without affecting the material's mechanical properties and thermal stability. Therefore, using PE80 or PE100 not only improves hydrogen barrier performance but also ensures the material's stability and reliability during long-term use, making it suitable for hydrogen storage containers, seals, and hydrogen pipelines.

[0016] In one embodiment, the ionic liquid comprises a cation and an anion; wherein the cation is selected from imidazole cations; and the anion is selected from at least one of acetate and diethyl phosphate.

[0017] This embodiment effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) by introducing an ionic liquid containing imidazole cations and anions such as acetate and diethylphosphate, while maintaining its mechanical and thermal processing properties. The cations and anions in the ionic liquid interact with the HDPE molecular chains, promoting their ordered arrangement and forming a denser microstructure. This denser structure reduces porosity and defects, effectively slowing hydrogen diffusion and improving hydrogen barrier performance. Furthermore, because imidazole cations and acetate anions have low reactivity with HDPE, they interact with HDPE through physical mixing and interfacial regulation, preventing chemical degradation and maintaining its mechanical and thermal stability. Therefore, HDPE material not only provides reliable hydrogen barrier performance but also maintains good mechanical strength and thermal processing properties under high temperature and high pressure conditions.

[0018] In one embodiment, the ionic liquid is selected from 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate; the purity of the 1-ethyl-3-methylimidazolium acetate or the 1-ethyl-3-methylimidazolium diethyl phosphate is ≥97%.

[0019] This embodiment introduces 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate with a purity ≥97% as an ionic liquid, which effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) while maintaining its mechanical and thermal processing properties. These ionic liquids are uniformly dispersed in polyethylene, promoting the ordered arrangement of molecular chains, forming a dense microstructure, increasing the diffusion resistance of hydrogen molecules, and thus improving the hydrogen barrier effect. The interaction between the imidazole cation and the polyethylene molecular chains further enhances the crystallinity and structural density of the molecular chains, while ensuring that the mechanical and thermal stability of HDPE is not compromised. Overall, the addition of ionic liquids not only improves the hydrogen barrier properties but also ensures the excellent performance of HDPE materials under high temperature and high pressure environments.

[0020] Secondly, embodiments of this application provide a method for preparing the high-density polyethylene material described above. The method includes: stirring high-density polyethylene to obtain stirred high-density polyethylene; mixing the stirred high-density polyethylene with an ionic liquid to obtain a premix; and subjecting the premix to hot pressing and cold pressing for shaping to obtain the high-density polyethylene material.

[0021] This embodiment, through careful design of process steps including stirring, ionic liquid mixing, hot pressing, and cold pressing, effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) while maintaining its mechanical and thermal processing properties. The stirring process uniformly disperses the HDPE particles, enhancing their flowability and providing a good foundation for subsequent mixing. When the ionic liquid is mixed with the stirred HDPE, it is uniformly dispersed within the HDPE, forming a dense microstructure that effectively increases the diffusion resistance of hydrogen and improves the hydrogen barrier effect. The combination of hot pressing and cold pressing ensures the material's uniformity, dimensional stability, and excellent mechanical properties. Ultimately, through the optimization of this series of processes, the obtained HDPE material improves hydrogen barrier properties while maintaining excellent mechanical and thermal processing properties, meeting the high-performance requirements of practical applications.

[0022] In one embodiment, the stirring conditions are: at a temperature of 140-200℃, the stirring time is 10-15 min, and the stirring speed is 30-60 rpm; the mixing conditions are: at a temperature of 140-200℃, the mixing time is 10-20 min, and the mixing speed is 30-60 rpm; the hot pressing conditions are: hot pressing pressure is 15-20 MPa, temperature is 140-200℃, and hot pressing time is 15-30 min; the cold pressing and shaping conditions are: cold pressing pressure is 15-20 MPa, temperature is 10-40℃, and cold pressing and shaping time is 20-40 min.

[0023] Thirdly, embodiments of this application provide an industrial-scale scale-up process, which includes: granulating, molding, and cooling high-density polyethylene material prepared by the above-described high-density polyethylene material or by the above-described preparation method to obtain industrial-scale scale-up high-density polyethylene material.

[0024] This embodiment utilizes a meticulously designed high-density polyethylene (HDPE) preparation process, including stirring, ionic liquid mixing, hot pressing, and cold pressing, to effectively enhance its hydrogen barrier properties while maintaining excellent mechanical and thermal processing performance. During industrial-scale scaling, HDPE material is first melt-extruded using granulation equipment to ensure material uniformity. Next, the granules are molded (e.g., injection molding, extrusion molding, compression molding, blow molding, thermoforming, rotational molding, etc.) with strictly controlled temperature, pressure, and injection speed to ensure the HDPE material fully fills the mold and meets molding quality requirements. Finally, the cooling and setting process guarantees the dimensional accuracy and surface quality of the HDPE material, thus maintaining its consistency and reliability. This series of process optimizations not only improves the hydrogen barrier effect but also ensures the application performance of HDPE material in hydrogen storage containers, seals, and hydrogen pipelines, providing an efficient hydrogen energy storage and transportation solution.

[0025] In one embodiment, the granulation temperature is 150-160°C; the molding temperature is 200°C.

[0026] Fourthly, this application provides an application of a high-density polyethylene material, wherein the high-density polyethylene material described above or the high-density polyethylene material prepared by the above preparation method is used in hydrogen storage and transportation containers, pipelines, pipeline joints, or fuel cell hydrogen seals. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0028] Figure 1 Scanning electron microscope images of Embodiment 1 and Comparative Example 1 provided in this application;

[0029] Figure 2 Infrared spectrum of Embodiment 1 provided in this application;

[0030] Figure 3 Infrared spectrum of Embodiment 2 provided in this application;

[0031] Figure 4 Infrared spectrum of Embodiment 3 provided in this application;

[0032] Figure 5 Infrared spectrum of Comparative Example 1 provided in this application;

[0033] Figure 6 The DSC curve of Embodiment 1 provided in this application;

[0034] Figure 7The DSC curve of Comparative Example 1 provided for this application;

[0035] Figure 8 TG and DTG curves for Embodiment 1 provided in this application;

[0036] Figure 9 The TG and DTG curves of Comparative Example 1 provided for this application. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] High-density polyethylene (HDPE) is a widely used material in gas transmission pipelines, containers, packaging materials, and fuel-related engineering due to its excellent mechanical properties, corrosion resistance, good processing performance, and low cost. While HDPE performs well in many applications, its hydrogen barrier properties are significantly lacking. HDPE is a non-polar linear polymer with high chain segment flexibility and weak interchain forces. Furthermore, its microstructure features an interweaving of crystalline and amorphous regions, resulting in high hydrogen permeability. This makes it unsuitable for applications with stringent gas barrier performance requirements, such as hydrogen storage and transportation and fuel cell casings.

[0039] The permeation of hydrogen in HDPE follows a "dissolution-diffusion" mechanism. Hydrogen molecules are first physically adsorbed and dissolved in the amorphous regions on the polyethylene surface, then diffuse in the free volume between polymer segments, and finally escape from the other side. Due to the semi-crystalline structure of HDPE, hydrogen mainly diffuses along the amorphous regions, while the crystalline regions form a physical barrier due to the tightly packed chain segments.

[0040] Existing technologies for improving the gas barrier properties of polyethylene (such as HDPE) mainly involve filling with nanomaterials (such as nano-montmorillonite, graphene oxide, etc.), blending with high-barrier polymers (such as EVOH, PA), or constructing dense composite layers. However, these methods generally suffer from several problems, primarily stemming from differences in the physicochemical properties of the materials and difficulties in process implementation. For example, when filling HDPE with nano-montmorillonite, the nanomaterials, due to their large surface area and high surface energy, are prone to agglomeration, making it difficult to achieve uniform dispersion using conventional physical blending processes. The microscopic defects formed by filler agglomeration can become channels for gas permeation, reducing the gas barrier effect. Simultaneously, polyethylene is a hydrophobic nonpolar polymer, while nano-inorganic fillers are often highly hydrophilic. This polarity difference leads to poor interfacial compatibility, making it difficult to achieve ideal interfacial bonding, easily resulting in debonding and porosity, thereby weakening barrier and mechanical properties. Furthermore, the filled nanomaterials form physical networks between polymer chains, hindering polymer chain movement and reducing the melt flow index (MFI), affecting the flowability and molding quality during thermal processing, such as injection molding, extrusion, and blow molding. When HDPE is blended with highly polar polymers (such as EVOH and PA), phase separation easily occurs due to the poor polarity, resulting in an uneven material structure, micropores, and impaired gas barrier properties and mechanical properties. Even with compatibilizers to improve dispersion and interface, the process becomes more complex, costs increase, and new migration or stability issues may arise. Furthermore, blending HDPE with EVOH often results in multiple melting peaks or a narrower melt-crystallization temperature range, leading to localized overheating, decomposition, or incomplete crystallization, narrowing the processing window, and requiring more stringent temperature control.

[0041] Furthermore, existing technologies often lead to a decline in the mechanical and thermal processing properties of materials. For example, the addition of nanofillers and high-barrier polymers often results in a decrease in the melt flow index (MFI) of HDPE, thus affecting thermal processing processes such as injection molding and extrusion. More importantly, although some technologies attempt to improve hydrogen barrier properties through surface modification or the addition of high-performance composite materials, these methods suffer from drawbacks such as complex processes, high costs, and unstable modification effects, making it difficult to meet the high requirements of fields such as hydrogen energy.

[0042] In summary, improving the hydrogen barrier properties of high-density polyethylene while maintaining its mechanical and thermal processing properties is a key technical problem that needs to be solved.

[0043] To address the aforementioned technical problems, according to embodiments of this application, a high-density polyethylene material with high hydrogen barrier properties is provided, comprising, by weight, 100 parts high-density polyethylene and 1-5 parts ionic liquid; the high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.246 × 10⁻⁶ under conditions of 10 MPa and 7°C. -16 mol·m / (m2 The hydrogen permeability coefficient of the high-density polyethylene material is less than or equal to 6.447 × 10⁻⁶ Pa under conditions of 70 MPa and 20°C. - 16 mol·m / (m 2 ·s·Pa).

[0044] Specifically, high-density polyethylene (HDPE), as a matrix material, possesses excellent mechanical properties, chemical resistance, and processability. Ionic liquids, on the other hand, are liquids composed of cations and anions that exist in a liquid state at or near room temperature. Ionic liquids are used as additives to improve the hydrogen barrier properties of HDPE. The addition of ionic liquids can alter the microstructure of HDPE, thereby affecting its gas barrier performance. Furthermore, the amount of ionic liquid added is controlled between 1 and 5 parts to ensure stable processability and mechanical properties while improving hydrogen barrier performance. When the amount of ionic liquid added is less than 1 part, the distribution of the ionic liquid in HDPE is uneven, the interface regulation and chain segment alignment induction effects are insufficient, making it difficult to form an effective hydrogen diffusion barrier structure, and the improvement in barrier performance is not significant. When the amount of ionic liquid added exceeds 5 parts, excessive ionic liquid will accumulate in HDPE, causing disturbances in the material's microstructure, increasing intergranular interface defects, and even affecting the melt processability and thermal stability of HDPE, thus leading to a decrease in mechanical properties. Therefore, by precisely controlling the amount of ionic liquid added, it is possible to improve the hydrogen barrier performance while maintaining the processability and mechanical properties of high-density polyethylene materials, thereby optimizing the overall performance.

[0045] This embodiment demonstrates how adding an appropriate amount of ionic liquid to high-density polyethylene (HDPE) can effectively improve its hydrogen barrier properties. Within the addition range of 1 to 5 parts, the ionic liquid optimizes the microstructure of HDPE, enhances intermolecular interactions, and significantly reduces the hydrogen permeability coefficient. Under conditions of 10 MPa and 7°C, and 70 MPa and 20°C, the hydrogen permeability coefficient of the HDPE material is less than or equal to 6.246 × 10⁻⁶. -16 mol·m / (m 2 ·s·Pa) and 6.447×10 -16 mol·m / (m 2 The ionic liquid exhibits excellent hydrogen barrier properties (·s·Pa). However, the amount of ionic liquid added needs to be strictly controlled. Below 1 part, the barrier performance improvement is not significant, while above 5 parts may disturb the microstructure of the high-density polyethylene material, thus affecting its mechanical and thermal processing properties. By precisely controlling the amount of ionic liquid added, it is possible to improve hydrogen barrier performance while maintaining the mechanical and thermal processing properties of the high-density polyethylene material, achieving an optimized balance of performance.

[0046] In one embodiment, the high-density polyethylene material has an elastic modulus ≥1179.68MPa, a yield strength ≥19.90MPa, a tensile strength ≥20.79MPa, and a maximum elongation ≥402.34%.

[0047] Specifically, the elastic modulus is an important indicator of a material's rigidity, referring to the ease with which a material undergoes elastic deformation under stress. For high-density polyethylene (HDPE), an elastic modulus ≥ 1179.68 MPa indicates that the HDPE material has high rigidity. Even under large external forces, its shape and size change are small, maintaining its original state. This characteristic is crucial for applications requiring precise dimensional control and long-term load bearing (such as pipes and structural components). This also allows HDPE to remain stable under high-intensity loads and is less prone to deformation. Yield strength is the critical stress value at which a material begins to undergo permanent deformation under stress. For HDPE, a yield strength ≥ 19.90 MPa means it can withstand large external forces without permanent deformation. Specifically, when the load is below this strength, HDPE can return to its original state; however, when the load exceeds this value, HDPE will enter the plastic deformation stage. This allows HDPE to maintain its performance under long-term loads or impacts, especially in applications requiring durability and long-term stability. Tensile strength refers to the maximum stress a material can withstand under tensile load. A tensile strength ≥20.79 MPa for high-density polyethylene (HDPE) means it can withstand high tensile forces without breaking. Higher tensile strength helps improve the service life of HDPE and reduces the risk of breakage due to excessive tensile stress. Elongation is the maximum deformability of a material under tension, representing the maximum deformation a material can withstand during stretching. A maximum elongation ≥402.34% for HDPE indicates very good ductility, allowing it to significantly elongate under tensile force without immediate breakage. This characteristic allows HDPE to absorb more energy when subjected to impact or dynamic loads, thus reducing the risk of brittle fracture.

[0048] The high-density polyethylene (HDPE) material in this embodiment possesses excellent mechanical properties, such as an elastic modulus ≥1179.68 MPa, yield strength ≥19.90 MPa, tensile strength ≥20.79 MPa, and maximum elongation ≥402.34%, which significantly improves its hydrogen barrier properties while maintaining mechanical stability. These properties ensure that the HDPE material is not easily deformed or cracked when subjected to external pressure, dynamic loads, or impacts, thereby effectively reducing the possibility of hydrogen permeation. Furthermore, these improved mechanical properties also ensure that the HDPE material maintains good shape stability and ductility during hot processing, meeting the requirements for processing precision and material reliability in the manufacturing process.

[0049] In one embodiment, the high-density polyethylene material has a melting initiation temperature ≥123.15℃, a melting peak temperature ≥133.99℃, and a melting termination temperature ≥143.40℃.

[0050] Specifically, a melting onset temperature ≥123.15℃ means that during processing (such as injection molding and extrusion), the high-density polyethylene (HDPE) material needs to be heated to at least 123.15℃ to melt. A higher melting onset temperature also indicates that HDPE has good thermal stability at lower temperatures and is less prone to premature melting at high temperatures. A melting peak temperature ≥133.99℃ indicates that HDPE requires more heat to completely melt, which may affect energy consumption during processing. A higher melting peak temperature may also indicate higher crystallinity in HDPE, which is typically related to its strength and rigidity. A melting termination temperature ≥143.40℃ provides a wide temperature window for processing HDPE, helping to optimize processing conditions and ensure the fluidity and uniformity of the HDPE during processing. A higher melting termination temperature also signifies the potential of HDPE in high-temperature applications, such as structural materials or thermoplastic composites in high-temperature environments.

[0051] This embodiment optimizes the melting initiation temperature (≥123.15℃), peak melting temperature (≥133.99℃), and melting termination temperature (≥143.40℃) of high-density polyethylene (HDPE) material, thereby improving its hydrogen barrier properties while maintaining its mechanical and thermal processing properties. A higher melting temperature helps increase the crystallinity of the material, thereby enhancing the close packing of molecules and improving its hydrogen barrier properties. Furthermore, a higher melting temperature also ensures the stability of the material during thermal processing, providing a wider temperature window and avoiding performance degradation due to improper processing. Therefore, reasonable control of the melting temperature can ensure high hydrogen barrier properties while maintaining the material's strength, rigidity, and good processing characteristics, ensuring its stability in high-performance applications. In one embodiment, the HDPE has a PE grade of PE80 or higher.

[0052] Specifically, PE grades are classified based on performance indicators such as long-term hydrostatic strength. These grades reflect the material's mechanical properties and durability under specific conditions. For example, PE80 indicates that the material can withstand a long-term hydrostatic strength of 8.0 MPa under specified conditions; PE100 indicates that its long-term hydrostatic strength can reach 10.0 MPa. A higher grade means the material can withstand higher pressure during long-term use, exhibiting better mechanical properties and durability. High-density polyethylene (HDPE) selected from materials with a PE grade of 80 or higher has higher compressive strength, can withstand higher internal pressure, and has better impact resistance, maintaining structural integrity under external impact and reducing the risk of pipe rupture. Secondly, materials with a PE grade of 80 or higher maintain stable performance during long-term use, and are less prone to aging and performance degradation. This helps extend the service life of pipeline systems and reduce maintenance costs. HDPE with a PE grade of 80 or higher has a more regular microstructure, with more ordered molecular chains. This regular structure helps form a denser matrix, thus better hindering the diffusion of hydrogen molecules. When combined with ionic liquids, materials with a PE grade of 80 or higher can interact more effectively with the ionic liquids, forming a more efficient hydrogen diffusion barrier structure. The ionic liquid is more uniformly distributed in these high-PE grade materials, allowing for more effective control over the crystallization behavior and molecular chain arrangement of high-density polyethylene, further enhancing hydrogen barrier performance. Therefore, high-density polyethylene materials with a PE grade of 80 or higher are selected to ensure superior performance in mechanical properties, durability, and hydrogen barrier properties. These high-PE grade materials have higher compressive strength, better impact resistance, and long-term stability, enabling them to better synergize with ionic liquids and form a denser microstructure that effectively hinders the diffusion of hydrogen molecules.

[0053] This embodiment uses high-density polyethylene (HDPE) of grade 80 or higher, which significantly improves the hydrogen barrier performance of HDPE while maintaining its excellent mechanical and thermal processing properties. HDPE of grade 80 or higher has a more regular microstructure and molecular chain arrangement, resulting in higher density and lower hydrogen permeability in hydrogen barrier performance. Furthermore, materials of grade 80 or higher have stronger compressive strength and impact resistance, enabling them to withstand higher internal pressures during long-term use, maintaining structural stability and avoiding performance degradation due to external impacts or aging. By combining with ionic liquids, the hydrogen barrier effect can be further enhanced without affecting its mechanical properties and thermal processing properties, ensuring the long service life and high reliability of HDPE in practical applications. Therefore, using HDPE of grade 80 or higher achieves the optimal balance between hydrogen barrier performance and the overall performance of HDPE.

[0054] In one embodiment, the PE grade of the high-density polyethylene is selected from PE80 or PE100.

[0055] Specifically, PE80 and PE100 have more regular molecular chain arrangements and denser microstructures, which helps to form more effective hydrogen diffusion barrier structures. When combined with ionic liquids, PE80 and PE100 can interact better with the ionic liquids, forming a more uniform distribution. Ionic liquids can more effectively regulate the crystallization behavior and molecular chain arrangement of high-density polyethylene in these materials, further improving hydrogen barrier performance. The selection of PE80 or PE100 not only improves hydrogen barrier performance but also maintains the material's mechanical properties and thermal stability. This means that in practical applications, this material can maintain good performance under high pressure and temperature conditions, making it suitable for hydrogen storage containers, seals, and hydrogen pipelines.

[0056] This embodiment uses high-density polyethylene (HDPE) of PE80 or PE100, which significantly improves hydrogen barrier performance while maintaining excellent mechanical and thermal processing properties. Because PE80 and PE100 have more regular molecular chain arrangements and a denser microstructure, hydrogen diffusion is effectively hindered, thus enhancing the hydrogen barrier effect. Furthermore, these materials maintain good mechanical properties, such as tensile strength and impact resistance, under high temperature and high pressure conditions, while their thermal processing performance is also guaranteed, ensuring convenient molding in practical applications. When combined with ionic liquids, PE80 and PE100 further optimize crystallization behavior and molecular chain arrangement, enhancing the hydrogen barrier effect without affecting the material's mechanical properties and thermal stability. Therefore, using PE80 or PE100 not only improves hydrogen barrier performance but also ensures the material's stability and reliability during long-term use, making it suitable for hydrogen storage containers, seals, and hydrogen pipelines.

[0057] In one embodiment, the ionic liquid comprises a cation and an anion; wherein the cation is selected from imidazole cations; and the anion is selected from at least one of acetate and diethyl phosphate.

[0058] Specifically, the introduction of ionic liquids can regulate the crystallization behavior of high-density polyethylene (HDPE). The cations and anions in the ionic liquids interact with the HDPE molecular chains, promoting their orderly arrangement and forming a denser microstructure. This denser microstructure means fewer pores and defects within the HDPE, effectively hindering hydrogen molecule diffusion and significantly reducing the hydrogen permeability coefficient. Ionic liquids containing imidazole cations, acetate groups, and diethyl phosphate groups exhibit low reactivity with HDPE, primarily interacting through physical mixing and interfacial modulation. This physical mixing and interfacial modulation does not disrupt the original structure of HDPE but rather hinders hydrogen diffusion by forming tiny "barriers" within the HDPE matrix. This minimal reactivity preserves the original structure of HDPE, preventing chemical degradation and ensuring that the intrinsic properties of the material remain unaffected.

[0059] This embodiment effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) by introducing an ionic liquid containing imidazole cations and anions such as acetate and diethylphosphate, while maintaining its mechanical and thermal processing properties. The cations and anions in the ionic liquid interact with the HDPE molecular chains, promoting their ordered arrangement and forming a denser microstructure. This denser structure reduces porosity and defects, effectively slowing hydrogen diffusion and improving hydrogen barrier performance. Furthermore, because imidazole cations and acetate anions have low reactivity with HDPE, they interact with HDPE through physical mixing and interfacial regulation, preventing chemical degradation and maintaining its mechanical and thermal stability. Therefore, HDPE material not only provides reliable hydrogen barrier performance but also maintains good mechanical strength and thermal processing properties under high temperature and high pressure conditions.

[0060] In one embodiment, the ionic liquid is selected from 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate; the purity of the 1-ethyl-3-methylimidazolium acetate or the 1-ethyl-3-methylimidazolium diethyl phosphate is ≥97%.

[0061] Specifically, 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate exhibits low volatility and high thermal stability, making it less prone to volatilization or decomposition during processing and use, and allowing it to exist stably in high-density polyethylene (HDPE). Furthermore, it possesses good dispersibility, enabling it to distribute uniformly within HDPE, promoting the ordered arrangement of HDPE molecular chains and forming a denser microstructure. This denser microstructure means fewer pores and defects within HDPE, effectively hindering the diffusion of hydrogen molecules. These ionic liquids can guide the arrangement of HDPE molecular chains, making them more regular. For example, the nitrogen atom of the imidazole cation can form a weak electrostatic interaction with the polar groups on the HDPE molecular chains, promoting the ordered arrangement of the molecular chains. The presence of ionic liquids also makes it easier for HDPE molecular chains to enter an ordered crystalline state, thereby forming a denser crystalline structure.

[0062] This embodiment introduces 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate with a purity ≥97% as an ionic liquid, which effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) while maintaining its mechanical and thermal processing properties. These ionic liquids are uniformly dispersed in polyethylene, promoting the ordered arrangement of molecular chains, forming a dense microstructure, increasing the diffusion resistance of hydrogen molecules, and thus improving the hydrogen barrier effect. The interaction between the imidazole cation and the polyethylene molecular chains further enhances the crystallinity and structural density of the molecular chains, while ensuring that the mechanical and thermal stability of HDPE is not compromised. Overall, the addition of ionic liquids not only improves the hydrogen barrier properties but also ensures the excellent performance of HDPE materials under high temperature and high pressure environments.

[0063] This application provides a method for preparing the high-density polyethylene material described above. The method includes: stirring high-density polyethylene to obtain stirred high-density polyethylene; mixing the stirred high-density polyethylene with an ionic liquid to obtain a premix; and hot-pressing and cold-pressing the premix to obtain the high-density polyethylene material.

[0064] Specifically, by stirring, high-density polyethylene (HDPE) granules or powder are fully dispersed, improving their uniformity and flowability. The stirred HDPE exhibits better flowability and uniformity. The stirred HDPE is then mixed with an ionic liquid in a specific ratio. Mixing equipment can include a twin-screw extruder, a high-speed mixer, or a kneader. During mixing, temperature and stirring speed can be controlled to ensure the ionic liquid is uniformly dispersed in the HDPE, forming a premix. Hot pressing melts and shapes the premix at high temperatures. During hot pressing, the HDPE melts and flows, and the ionic liquid is uniformly dispersed within the molten HDPE, forming a homogeneous HDPE material. Cold pressing allows the hot-pressed HDPE material to solidify during cooling, ensuring the dimensional stability and mechanical properties of the HDPE material.

[0065] This embodiment, through careful design of process steps including stirring, ionic liquid mixing, hot pressing, and cold pressing, effectively improves the hydrogen barrier properties of high-density polyethylene (HDPE) while maintaining its mechanical and thermal processing properties. The stirring process uniformly disperses the HDPE particles, enhancing their flowability and providing a good foundation for subsequent mixing. When the ionic liquid is mixed with the stirred HDPE, it is uniformly dispersed within the HDPE, forming a dense microstructure that effectively increases the diffusion resistance of hydrogen and improves the hydrogen barrier effect. The combination of hot pressing and cold pressing ensures the material's uniformity, dimensional stability, and excellent mechanical properties. Ultimately, through the optimization of this series of processes, the obtained HDPE material improves hydrogen barrier properties while maintaining excellent mechanical and thermal processing properties, meeting the high-performance requirements of practical applications.

[0066] In one embodiment, the stirring conditions are: at a temperature of 140-200℃, the stirring time is 10-15 min, and the stirring speed is 30-60 rpm; the mixing conditions are: at a temperature of 140-200℃, the mixing time is 10-20 min, and the mixing speed is 30-60 rpm; the hot pressing conditions are: hot pressing pressure is 15-20 MPa, temperature is 140-200℃, and hot pressing time is 15-30 min; the cold pressing and shaping conditions are: cold pressing pressure is 15-20 MPa, temperature is 10-40℃, and cold pressing and shaping time is 20-40 min.

[0067] This application provides an industrial-scale scale-up process, which includes: granulating, molding, and cooling high-density polyethylene material prepared by the above-described high-density polyethylene material or by the above-described preparation method to obtain industrial-scale scale-up high-density polyethylene material.

[0068] Specifically, the prepared high-density polyethylene (HDPE) material is placed in a granulation device, such as a twin-screw extruder or a single-screw extruder. Through heating and shearing, the material is melted and extruded to form uniform granules. These granules are then molded using methods such as injection molding, extrusion molding, compression molding, blow molding, thermoforming, and rotational molding. Taking injection molding as an example, the granulated granules are placed in the hopper of an injection molding machine and melted by heating. The molten material is then injected into a mold, and high pressure is applied to fill all corners of the mold. During injection molding, parameters such as temperature, pressure, and injection speed need to be controlled to ensure molding quality. After injection molding, the product is retained in the mold and cooled using a cooling system (such as water cooling or air cooling). The cooling time typically varies from tens of seconds to several minutes, depending on the thickness and shape of the product. After cooling, the mold is opened, and the industrial-scale HDPE material is removed. This industrial-scale process, through steps such as granulation, injection molding, and cooling, transforms laboratory or small-scale HDPE materials into products suitable for large-scale industrial applications. This process ensures material uniformity and consistency, improves the dimensional accuracy and surface quality of products, and meets the requirements of industrial production for material quality and efficiency. This material has wide applications in hydrogen storage containers, seals, hydrogen pipelines, and other industrial products, providing a new solution for hydrogen energy storage and transportation.

[0069] This embodiment utilizes a meticulously designed high-density polyethylene (HDPE) preparation process, including stirring, ionic liquid mixing, hot pressing, and cold pressing, to effectively enhance its hydrogen barrier properties while maintaining excellent mechanical and thermal processing performance. During industrial-scale scaling, HDPE material is first melt-extruded using a granulation device to ensure material uniformity. Next, the granules are molded, with strict control over temperature, pressure, and injection speed to ensure the HDPE material fully fills the mold and meets molding quality requirements. Finally, the cooling and setting process guarantees the dimensional accuracy and surface quality of the HDPE material, thus maintaining its consistency and reliability. This series of process optimizations not only improves the hydrogen barrier effect but also ensures the application performance of HDPE material in hydrogen storage containers, seals, and hydrogen pipelines, providing an efficient hydrogen energy storage and transportation solution.

[0070] In one embodiment, the granulation temperature is 150-160°C; the molding temperature is 200°C.

[0071] This application provides an application of high-density polyethylene material, wherein the high-density polyethylene material described above or the high-density polyethylene material prepared by the above preparation method is used in hydrogen storage and transportation containers, pipelines, pipeline joints or fuel cell hydrogen seals.

[0072] Specifically, in hydrogen storage and transportation containers, high-density polyethylene (HDPE) materials can incorporate other fillers or additives, such as glass fiber and carbon fiber, to further improve the material's mechanical properties and durability. Furthermore, it can be combined with other materials (such as metals) to form multi-layered structures, enhancing the overall performance and safety of the container.

[0073] In pipeline applications, high-density polyethylene (HDPE) can be combined with other materials (such as rubber) to form a multi-layered structure, enhancing the pipeline's sealing performance and corrosion resistance. Furthermore, it can contain other additives, such as antioxidants and UV absorbers, to improve the pipeline's weather resistance and service life.

[0074] In pipe fitting applications, high-density polyethylene (HDPE) materials can incorporate other fillers or additives, such as sealants and lubricants, to further improve the sealing performance and durability of the fittings. Furthermore, it can be combined with other materials (such as metals) to form multi-layered structures, enhancing the overall performance and safety of the fittings.

[0075] In fuel cell hydrogen sealing applications, high-density polyethylene (HDPE) materials can incorporate other additives, such as sealants and antioxidants, to further improve the sealing performance and durability of the seals. Furthermore, it can be compounded with other materials (such as rubber) to form multi-layer structures, enhancing the overall performance and reliability of the seals.

[0076] This high-density polyethylene (HDPE) material and its preparation method have broad application prospects in the field of hydrogen storage and transportation. By adding ionic liquids, the hydrogen barrier properties of HDPE are significantly improved while maintaining good mechanical properties and thermal stability. Furthermore, by incorporating other fillers or additives, and by forming multilayer structures with other materials, the performance of HDPE can be further enhanced, meeting the stringent performance requirements of hydrogen storage and transportation containers, pipes, pipe fittings, and fuel cell hydrogen seals. The application of this HDPE material provides a new solution for hydrogen energy storage and transportation, possessing significant practical importance and broad development prospects.

[0077] This embodiment optimizes the preparation process of high-density polyethylene (HDPE) material, particularly by adding ionic liquids, fillers, and additives, significantly improving its hydrogen barrier properties while maintaining excellent mechanical and thermal processing performance. These improvements enable HDPE materials to offer greater safety and longer service life in applications such as hydrogen storage and transportation containers, pipelines, pipe fittings, and fuel cell hydrogen seals.

[0078] To better explain and facilitate understanding of this application, a detailed description of the application is provided below through specific embodiments. Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to prior art methods. All parts represent parts by weight.

[0079] Example 1

[0080] The high-density polyethylene material with high hydrogen barrier properties in this embodiment is made from the following raw materials:

[0081]

[0082] The preparation method of high-density polyethylene material with high hydrogen barrier properties is as follows:

[0083] Step S1: Stir high-density polyethylene PE100 at a temperature of 200℃ for 10 minutes at a stirring speed of 40 rpm to obtain stirred high-density polyethylene.

[0084] Step S2: Introduce ionic liquid 1-ethyl-3-methylimidazolium acetate into the stirred high-density polyethylene, and continue stirring and mixing at a temperature of 200℃ for 20 min at a stirring speed of 40 rpm to obtain a premix.

[0085] Step S3: Place the premix into a mold for hot pressing. The hot pressing pressure is 17 MPa, the temperature is 200℃, and the compression time is 20 min.

[0086] Step S4: The product obtained in step S3 is cold-pressed and shaped. The cold pressing pressure is 17 MPa, the temperature is 20°C, and the cold pressing and shaping time is 40 min. After demolding, high-density polyethylene material is obtained.

[0087] Example 2

[0088] The high-density polyethylene material with high hydrogen barrier properties in this embodiment is made from the following raw materials:

[0089]

[0090] The preparation method of high-density polyethylene material with high hydrogen barrier properties is as follows:

[0091] Step S1: Stir high-density polyethylene PE100 at a temperature of 200℃ for 12 minutes at a stirring speed of 30 rpm to obtain stirred high-density polyethylene.

[0092] Step S2: Introduce the ionic liquid 1-ethyl-3-methylimidazolium acetate into the stirred high-density polyethylene, and continue stirring and mixing at a temperature of 200℃ for 15 minutes at a stirring speed of 30 rpm to obtain the premix.

[0093] Step S3: Place the premix into a mold for hot pressing. The hot pressing pressure is 15 MPa, the temperature is 180°C, and the compression time is 20 min.

[0094] Step S4: The product obtained in step S3 is cold-pressed and shaped. The cold pressing pressure is 15 MPa, the temperature is 10℃, and the cold pressing and shaping time is 20 min. After demolding, high-density polyethylene material is obtained.

[0095] Example 3

[0096] The high-density polyethylene material with high hydrogen barrier properties in this embodiment is made from the following raw materials:

[0097]

[0098] The preparation method of high-density polyethylene material with high hydrogen barrier properties is as follows:

[0099] Step S1: Stir high-density polyethylene PE100 at a temperature of 140℃ for 14 minutes at a stirring speed of 60 rpm to obtain stirred high-density polyethylene.

[0100] Step S2: Introduce ionic liquid 1-ethyl-3-methylimidazolium acetate into the stirred high-density polyethylene, and continue stirring and mixing at a temperature of 140°C for 10 min at a stirring speed of 60 rpm to obtain a premix.

[0101] Step S3: Place the premix into a mold for hot pressing. The hot pressing pressure is 20 MPa, the temperature is 200℃, and the compression time is 20 min.

[0102] Step S4: The product obtained in step S3 is cold-pressed and shaped. The cold pressing pressure is 20 MPa, the temperature is 30°C, and the cold pressing and shaping time is 30 min. After demolding, high-density polyethylene material is obtained.

[0103] Example 4

[0104] The high-density polyethylene material with high hydrogen barrier properties in this embodiment is made from the following raw materials:

[0105]

[0106] The preparation method of high-density polyethylene material with high hydrogen barrier properties is as follows:

[0107] Step S1: Stir high-density polyethylene PE80 at a temperature of 200℃ for 15 minutes at a stirring speed of 50 rpm to obtain stirred high-density polyethylene.

[0108] Step S2: Introduce ionic liquid 1-ethyl-3-methylimidazolium diethyl phosphate into the stirred high-density polyethylene, and continue stirring and mixing at a temperature of 200℃ for 20 min at a stirring speed of 50 rpm to obtain a premix.

[0109] Step S3: Place the premix into a mold for hot pressing. The hot pressing pressure is 18 MPa, the temperature is 140°C, and the compression time is 20 min.

[0110] Step S4: The product obtained in step S3 is cold-pressed and shaped. The cold pressing pressure is 18 MPa, the temperature is 40°C, and the cold pressing and shaping time is 40 min. After demolding, high-density polyethylene material is obtained.

[0111] Comparative Example 1

[0112] Same as Example 1, except that the ionic liquid 1-ethyl-3-methylimidazolium acetate was not added.

[0113] Comparative Example 2

[0114] Same as Example 3, except that the ionic liquid 1-ethyl-3-methylimidazolium acetate was not added.

[0115] Comparative Example 3

[0116] Same as Example 4, except that the ionic liquid 1-ethyl-3-methylimidazolium diethyl phosphate was not added.

[0117] Comparative Example 4

[0118] Same as Example 1, except that 8 parts of the ionic liquid 1-ethyl-3-methylimidazolium acetate were added.

[0119] Comparative Example 5

[0120] Same as Example 1, except that 2 parts of maleic anhydride are added to the formulation of Example 1.

[0121] For microstructure analysis of Example 1 and Comparative Example 1 above, please refer to [link / reference]. Figure 1 Scanning electron microscope images of Example 1 and Comparative Example 1 provided in this application. Figure 1 (a) is the sample of Comparative Example 1, which has obvious particles and defects on its surface and a relatively loose microstructure. This may be due to the irregular arrangement of the high-density polyethylene molecular chains, resulting in more voids and micropores. Figure 1(b) shows the sample from Example 1. The sample with added ionic liquid has a smoother, denser surface, with significantly reduced defects and particles. This indicates that the introduction of ionic liquid effectively promotes the ordered arrangement of high-density polyethylene molecular chains, improves inter-chain interactions, and thus constructs a denser and more uniform microstructure. The voids and micropores inside the material are the main channels for gas molecule diffusion. After adding ionic liquid, the microstructure of the high-density polyethylene material becomes denser, voids and micropores are significantly reduced, the diffusion path of hydrogen molecules is lengthened, and the diffusion resistance increases, thereby significantly reducing the hydrogen permeability coefficient and improving the gas barrier performance of the material.

[0122] Infrared spectroscopy tests were performed on Examples 1-3 and Comparative Example 1. Please refer to [link / reference]. Figure 2 Infrared spectrum of Embodiment 1 provided in this application. Figure 3 Infrared spectrum of Embodiment 2 provided in this application. Figure 4 Infrared spectrum of Example 3 provided in this application. Figure 5 The infrared spectrum of Comparative Example 1 provided in this application. Figure 2 , Figure 3 , Figure 4 and Figure 5 The results show that Examples 1-3 and Comparative Example 1 exhibit essentially the same position and intensity of their main characteristic absorption peaks, indicating that the introduction of the ionic liquid did not alter the chemical structure of high-density polyethylene. No new absorption peaks appeared in the infrared spectra of Examples 1-3, nor were there any significant shifts or disappearances of existing characteristic peaks, indicating that no new chemical bonds were formed between the ionic liquid and high-density polyethylene. This means that the interaction between the ionic liquid and high-density polyethylene is primarily physical mixing and interfacial modulation, rather than a chemical reaction. Since no chemical bonding reaction occurred, the main chain structure and chemical configuration of high-density polyethylene were maintained, and therefore its intrinsic properties, such as chemical stability, corrosion resistance, and thermal stability, remained unaffected.

[0123] For the DSC and TGA tests performed on Example 1 and Comparative Example 1 above, please refer to [link to relevant documentation]. Figure 6 , Figure 8 The DSC and TG / DTG curves of Embodiment 1 provided in this application. Figure 7 , Figure 9 The DSC and TG / DTG curves of Comparative Example 1 provided for this application. Figure 6 The melting initiation temperature, peak temperature, and termination temperature of Example 1 did not change significantly, indicating that the ionic liquid did not significantly alter the crystal structure of high-density polyethylene. The crystallinity increased from 72.63% to 77.61%, indicating that the ionic liquid promoted the ordered arrangement of high-density polyethylene molecular chains and enhanced crystallization ability, which is consistent with... Figure 1 The dense structure observed in (b) is consistent with that in the example. Figure 8 Example 1 and Figure 9 The TG curves of Comparative Example 1 are basically consistent, indicating that their thermogravimetric behavior is very similar. The peak positions of the DTG curves of Example 1 and Comparative Example 1 are consistent, indicating that the temperature of the maximum thermogravimetric rate has not shifted and the thermal decomposition mechanism has not changed. Moreover, the thermal stability has not decreased, indicating that the ionic liquid is stable at high temperatures and will not cause premature degradation.

[0124] Hydrogen permeation tests were conducted on Examples 1-4 and Comparative Examples 1-5 according to standard methods. The test results of the hydrogen permeation performance of the above samples are shown in Table 1:

[0125] Table 1. Hydrogen permeation performance test results

[0126]

[0127] As shown in Table 1, based on the comparison between Comparative Example 1 and Example 1, Comparative Example 2 and Example 3, and Comparative Example 3 and Example 4, the hydrogen permeability coefficient of Example 1 with an appropriate amount of ionic liquid added is significantly lower than that of Comparative Example 1 without ionic liquid added; the hydrogen permeability coefficient of Example 3 with an appropriate amount of ionic liquid added is significantly lower than that of Comparative Example 2 without ionic liquid added; and the hydrogen permeability coefficient of Example 4 with an appropriate amount of ionic liquid added is significantly lower than that of Comparative Example 3 without ionic liquid added. This indicates that the introduction of ionic liquid effectively hinders the diffusion of hydrogen molecules and improves the hydrogen barrier performance of the material.

[0128] According to the comparison between Comparative Example 4 and Example 1, the amount of ionic liquid added in Comparative Example 4 reached 8 parts, which exceeded the preferred range (1-5 parts). This caused the hydrogen permeability coefficient to increase instead of decrease, indicating that excessive ionic liquid may agglomerate, form defects or phase separation in the matrix, destroy the dense structure of the material and reduce the hydrogen barrier performance.

[0129] Based on the comparison between Comparative Example 5 and Example 1, it can be seen that Comparative Example 5, based on Example 1, added 2 parts of maleic anhydride, increasing the hydrogen permeability coefficient from 4.484 × 10⁻⁶. -16 mol·m / (m 2 The concentration of ·s·Pa rose to 6.069×10 -16 mol·m / (m 2 The result (·s·Pa) indicates that the addition of maleic anhydride did not further improve the hydrogen barrier performance; on the contrary, it may have interfered with the interfacial structure between the ionic liquid and the high-density polyethylene matrix, thus weakening the barrier effect.

[0130] In summary, the examples are consistently superior to the comparative examples, demonstrating that ionic liquids can effectively improve hydrogen barrier performance under different conditions.

[0131] Uniaxial tensile tests were performed on Examples 1-4 and Comparative Examples 1-5 above, following standard methods. The tensile mechanical properties of the samples are shown in Table 2.

[0132] Table 2 Results of tensile mechanical properties test

[0133]

[0134] As shown in Table 2, based on the comparison between Comparative Example 1 and Example 1, Comparative Example 2 and Example 3, and Comparative Example 3 and Example 4, the mechanical properties (elastic modulus, yield strength, tensile strength, and elongation) of the samples in the examples did not change significantly. This indicates that the addition of an appropriate amount of ionic liquid has little impact on the mechanical properties of high-density polyethylene and basically maintains the original mechanical properties of the material.

[0135] According to the comparison between Comparative Example 4 and Example 1, the amount of ionic liquid added in Comparative Example 4 reached 8 parts, which exceeded the preferred range (1-5 parts). This resulted in a significant decrease in elastic modulus, yield strength and tensile strength. It is indicated that excessive ionic liquid may agglomerate, form defects or phase separation in the matrix, destroy the structural integrity of the material and reduce its mechanical properties.

[0136] The comparison between Comparative Example 5 and Example 1 shows that Comparative Example 5, which added 2 parts of maleic anhydride to Example 1, saw its elastic modulus decrease from 1227.67 MPa to 1042.16 MPa, indicating that the addition of maleic anhydride reduced the material's rigidity. However, the yield strength and tensile strength did not change significantly, while the elongation decreased slightly, indicating that maleic anhydride had a limited impact on the overall mechanical properties of the material, but it did reduce its rigidity.

[0137] In summary, the mechanical properties of Examples 1-4 varied under different test conditions, but the influence of the addition of ionic liquid on the mechanical properties showed a consistent trend: appropriate addition had little impact on the mechanical properties, while excessive addition would reduce the mechanical properties.

[0138] DSC tests were performed on Examples 1-4 and Comparative Examples 1-5 above, following standard methods. The DSC test results for the above samples are shown in Table 3.

[0139] Table 3 DSC Test Results

[0140]

[0141] As shown in Table 3, based on the comparison between Comparative Example 1 and Example 1, Comparative Example 2 and Example 3, and Comparative Example 3 and Example 4, the melting start temperature, peak temperature, and termination temperature of the samples in the examples did not change much. This indicates that the appropriate addition of ionic liquid has little effect on the crystal structure and melting behavior of high-density polyethylene, and basically maintains the original thermal properties of high-density polyethylene.

[0142] According to the comparison between Comparative Example 4 and Example 1, when the amount of ionic liquid added in Comparative Example 4 reached 8 parts, the melting start temperature and peak temperature increased slightly, and the melting termination temperature decreased slightly, indicating that excessive ionic liquid may have a certain impact on the crystal integrity of high-density polyethylene.

[0143] According to the comparison between Comparative Example 5 and Example 1, Comparative Example 5 added 2 parts of maleic anhydride on the basis of Example 1, and the melting peak temperature and termination temperature increased significantly. This indicates that the addition of maleic anhydride may have changed the crystal structure of high-density polyethylene, making its crystallization more complete or forming a more stable crystal structure.

[0144] In summary, while the melting temperatures varied under different test conditions in Examples 1-4, the influence of ionic liquid on melting behavior showed a consistent trend, indicating that appropriate addition had a relatively small impact on melting behavior. Therefore, the addition of ionic liquid did not significantly alter the melting characteristics of high-density polyethylene, ensuring the reliability of its thermal processing performance.

[0145] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0146] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0147] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A high-density polyethylene material with high hydrogen barrier properties, characterized in that, By weight, it includes 100 parts high-density polyethylene and 1-5 parts ionic liquid; The PE grade of the high-density polyethylene is PE80 or higher; The ionic liquid is selected from 1-ethyl-3-methylimidazolium acetate or 1-ethyl-3-methylimidazolium diethyl phosphate; The high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.246 × 10⁻⁶ under conditions of 10 MPa and 7°C. - 16 mol·m / (m 2 ·s·Pa); The high-density polyethylene material has a hydrogen permeability coefficient of less than or equal to 6.447 × 10⁻⁶ under conditions of 70 MPa and 20°C. - 16 mol·m / (m 2 ·s·Pa).

2. The high-density polyethylene material according to claim 1, characterized in that, The high-density polyethylene material has an elastic modulus ≥1179.68MPa, yield strength ≥19.90MPa, tensile strength ≥20.79MPa, and maximum elongation ≥402.34%.

3. The high-density polyethylene material according to claim 1, characterized in that, The high-density polyethylene material has a melting start temperature ≥123.15℃, a melting peak temperature ≥133.99℃, and a melting end temperature ≥143.40℃.

4. The high-density polyethylene material according to claim 1, characterized in that, The PE grade of the high-density polyethylene is selected from PE80 or PE100.

5. The high-density polyethylene material according to claim 1, characterized in that, The purity of the 1-ethyl-3-methylimidazolium acetate or the 1-ethyl-3-methylimidazolium diethyl phosphate is ≥97%.

6. A method for preparing the high-density polyethylene material according to any one of claims 1-5, characterized in that, The preparation method includes: High-density polyethylene is stirred to obtain stirred high-density polyethylene; The stirred high-density polyethylene and ionic liquid are mixed to obtain a premix; The premix is ​​hot-pressed and cold-pressed to obtain the high-density polyethylene material.

7. The preparation method according to claim 6, characterized in that, The stirring conditions are: a temperature of 140-200℃, a stirring time of 10-15 minutes, and a stirring speed of 30-60 rpm. The mixing conditions are as follows: at a temperature of 140-200℃, the mixing time is 10-20 minutes, and the mixing speed is 30-60 rpm. The hot pressing conditions are: hot pressing pressure of 15-20 MPa, temperature of 140-200℃, and hot pressing time of 15-30 min. The conditions for cold pressing are: cold pressing pressure of 15-20 MPa, temperature of 10-40℃, and cold pressing time of 20-40 min.

8. An industrial-scale scale-up process, characterized in that, The industrial-scale scale-up process includes: The high-density polyethylene material according to any one of claims 1-5 or the high-density polyethylene material prepared by the preparation method according to any one of claims 6-7 is subjected to granulation, molding, and cooling to obtain a high-density polyethylene material for industrial scale-up.

9. The industrial-scale scale-up process according to claim 8, characterized in that, The granulation temperature is 150-160℃; The molding temperature is 200℃.

10. An application of a high-density polyethylene material, characterized in that, The high-density polyethylene material according to any one of claims 1-5 or the high-density polyethylene material prepared by the preparation method according to any one of claims 6-7 is used in hydrogen storage and transportation containers, hydrogen storage and transportation pipelines, hydrogen storage and transportation pipeline joints, or fuel cell hydrogen seals.

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