Preparation method of novel plastic liner of hydrogen storage cylinder
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI CLEAN ENERGY
- Filing Date
- 2026-03-23
- Publication Date
- 2026-06-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrogen storage cylinder plastic liner preparation technology, specifically a novel method for preparing a hydrogen storage cylinder plastic liner. Background Technology
[0002] Type IV hydrogen storage cylinder liners are key components in hydrogen fuel cell vehicles, responsible for airtightness and pressure resistance. Their structural stability throughout their service life directly affects the safety of vehicle operation. High-density polyethylene (HDPE) is widely used in the manufacture of these liners due to its excellent gas barrier properties and thermoplastic processing characteristics. In terms of molding process selection, plastic liners need to meet requirements such as large-size hollow structure, uniform wall thickness, and seamless integral molding. Compared with conventional thermoplastic processing methods such as injection molding and blow molding, rotational molding completes material melting and spreading under low shear and no internal pressure conditions, making it easier to obtain hollow products with complete structure, continuous wall thickness, and good integrity. Therefore, it has gradually become the main molding process for HDPE hydrogen storage cylinder liners.
[0003] However, during the rotational molding process, high-density polyethylene, as a semi-crystalline polymer material, inevitably undergoes significant crystallization shrinkage during the melt-cooling crystallization stage. This results in the formation and retention of residual internal stress inside the liner. During long-term service, the liner must withstand extreme temperature fluctuations ranging from -40°C to 85°C, making it prone to becoming brittle. At the same time, the residual internal stress will gradually be released and superimposed on the external load, leading to stress concentration in local areas. This easily induces the initiation and propagation of microcracks, ultimately causing the liner to buckle, crack, or even the gas cylinder to fail.
[0004] Therefore, how to effectively reduce the residual internal stress caused by material shrinkage while maintaining the advantages of rotational molding, so that the inner liner can maintain high toughness and high dimensional stability under long-term high and low temperature alternating environment, has become a key technical problem that urgently needs to be solved in the current manufacturing field of Type IV hydrogen storage cylinder inner liners. Summary of the Invention
[0005] The purpose of this invention is to provide a novel method for preparing a plastic inner liner for hydrogen storage cylinders. By constructing an organic-inorganic composite system with high interfacial compatibility and structural synergy, the high-density polyethylene inner liner for hydrogen storage cylinders can maintain a stable overall structure and performance continuity under rotational molding and long-term high and low temperature alternating service conditions, so as to meet the safety, dimensional stability and service reliability requirements of Type IV hydrogen storage cylinders in the long-term operation of hydrogen fuel cell vehicles.
[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a novel plastic inner liner for hydrogen storage cylinders, comprising the following steps: Thermoplastic high-density polyethylene composite powder and dicumyl peroxide are placed in a mixer and stirred for 5-10 minutes. The mixture is then added to the plastic inner liner molding mold of a rotational molding machine. Rotational molding is performed at 140-150℃ for 20-30 minutes under a nitrogen atmosphere. Subsequently, the temperature is raised to 170℃-190℃ and rotational molding is performed for another 20-30 minutes. The mixture is then cooled with circulating air for 30-40 minutes to obtain a novel plastic inner liner for hydrogen storage cylinders.
[0007] Furthermore, the volume of the plastic inner liner molding mold is 5-7L.
[0008] Furthermore, the mass ratio of thermoplastic high-density polyethylene composite powder to dicumyl peroxide is 350-450:6-8.
[0009] Furthermore, the preparation process of thermoplastic high-density polyethylene composite powder is as follows: High-density polyethylene, ethylene-octene copolymer, PE-g-MAH, silane-modified fumed silica, surface-modified nano-calcium carbonate with double bonds, and antioxidant 1010 are added to a twin-screw extruder, extruded, cooled and pelletized, then added to a low-temperature grinding mill for pulverization and sieving to obtain thermoplastic high-density polyethylene composite powder.
[0010] Furthermore, the extrusion temperatures of the twin-screw extruder from the feed inlet to the die head are 150-160℃, 170-180℃, 180-190℃, and 190-210℃ respectively.
[0011] Furthermore, the mass ratio of high-density polyethylene, ethylene-octene copolymer, PE-g-MAH, silane-modified fumed silica, surface-modified nano-calcium carbonate containing double bonds, and antioxidant 1010 is 360-400:70-90:10-20:5-10:16-20:1-3.
[0012] Furthermore, the preparation process of silane-modified fumed silica is as follows: Fumed silica and anhydrous ethanol were placed in a reaction vessel and ultrasonically dispersed for 20-40 min. An aqueous solution of silane coupling agent was added, and the mixture was reacted at 60-80℃ for 2-4 h. After centrifugation, washing, and vacuum drying to constant weight, silane-modified fumed silica was obtained.
[0013] Furthermore, the ratio of fumed silica, silane coupling agent aqueous solution, and anhydrous ethanol is 10-20g: 150-300mL: 300-600mL. The silane coupling agent aqueous solution is obtained by mixing γ-methacryloyloxypropyltrimethoxysilane and deionized water at a volume ratio of 1:2.
[0014] Furthermore, the preparation process of surface-modified nano-calcium carbonate containing double bonds is as follows: Nano-calcium carbonate and anhydrous ethanol were placed in a reaction vessel and stirred at 50-60℃ for 10-20 min. Alkylvinylimidazolium ionic liquid was added, and the reaction was continued for 1-2 h. The mixture was then dried under vacuum to constant weight to obtain surface-activated nano-calcium carbonate containing double bonds.
[0015] Furthermore, the ratio of nano-calcium carbonate, alkylvinylimidazolium ionic liquid, and anhydrous ethanol is 40-60g: 2-4g: 300-500mL.
[0016] Furthermore, the preparation process of the alkylvinylimidazolium ionic liquid is as follows: The long-chain vinylimidazolium bromide intermediate, lithium bis(trifluoromethanesulfonylimide) and acetone were placed in a nitrogen atmosphere reactor and reacted at 25-35℃ for 10-14 h. The acetone was removed by rotary evaporation, the mixture was extracted, the organic phase was collected, filtered, rotary evaporated, and vacuum dried to constant weight to obtain the alkylvinylimidazolium ionic liquid.
[0017] Furthermore, the ratio of the long alkyl chain vinylimidazolium bromide intermediate, lithium bis(trifluoromethanesulfonylimide) and acetone is 6-10 g: 4-6 g: 100-200 mL.
[0018] Furthermore, the preparation process of the long alkyl chain vinylimidazolium bromide intermediate is as follows: N-vinylimidazolium and bromododecane were placed in a reaction vessel under nitrogen atmosphere and reacted at 60-70℃ for 20-24 h. Ethyl acetate was added to precipitate the product, which was then filtered, washed, and vacuum dried to constant weight to obtain a long-chain vinylimidazolium bromide intermediate.
[0019] Furthermore, the mass ratio of N-vinylimidazole to bromododecane is 4-6:10-20.
[0020] The beneficial effects of this invention are: 1. The novel hydrogen storage cylinder plastic liner prepared by this invention improves the crystallization and deformation behavior of high-density polyethylene matrix from the microstructure through the synergistic modification of various functional fillers. Among them, the nano-calcium carbonate activated by ionic liquid has a hydrophobic long chain structure that significantly improves the interfacial compatibility between polar nano-calcium carbonate and non-polar polyethylene matrix, and forms an internal lubrication effect between polymer molecular chains, thereby slowing down the crystallization rate of high-density polyethylene matrix, reducing crystallization perfection and reducing volume shrinkage. At the same time, highly active carbon-carbon double bonds are introduced on the surface of both fumed silica and nano-calcium carbonate. These reactive sites can chemically connect with the polymer matrix during the molding process, effectively limiting interfacial slippage and stress concentration during crystallization shrinkage. Together with the flexible phase formed by ethylene-octene copolymer, a composite system with synergistic effects of rigid support and toughness buffer is constructed, enabling the material to obtain better structural stability while maintaining high toughness.
[0021] 2. The novel hydrogen storage cylinder plastic liner prepared by this invention, through the synergistic design of the material system and rotational molding process, helps to control the melt rheological behavior, improve wall thickness uniformity, and reduce molding internal stress. Among them, fumed silica forms a physical support network in the polymer melt, significantly endowing the system with good thixotropic properties. During rotational molding, it effectively suppresses the sag and accumulation of the melt at high temperatures, making the wall thickness distribution of the liner bottle mouth and body area more uniform, thereby eliminating local stress concentration caused by abrupt thickness changes and ensuring the overall dimensional consistency of the liner. In the early stage of molding, the composite powder is fully melted and evenly spread, ensuring that the product is seamless and structurally continuous. Subsequently, in-situ crosslinking reaction is introduced during the heating stage, causing the polymer molecular chains to chemically bond with the reactive groups on the filler surface, constructing a stable three-dimensional crosslinking network. The process path of molding first and then crosslinking effectively limits the excessive slippage and secondary crystallization shrinkage of polyethylene molecular chains while ensuring the integrity of rotational molding, thereby improving the material structural stability and long-term service reliability.
[0022] 3. The novel hydrogen storage cylinder plastic liner prepared by this invention constructs a composite network structure in which organic and inorganic phases work synergistically. This structure enables the material to maintain good stability under wide temperature range service conditions. The rigid skeleton formed by fumed silica significantly improves the material's creep resistance and deformation resistance under high temperature conditions, preventing the liner from softening and buckling during long-term service. Meanwhile, the flexible energy-dissipating region formed by ionic liquid-modified nano-calcium carbonate and ethylene-octene copolymer continuously dissipates external energy through craze-induced plastic deformation mechanisms under low temperature and high pressure impact conditions, significantly delaying the initiation and propagation of microcracks and ensuring the liner maintains its toughness at low temperatures. At the same time, the chemical cross-linking network between the polymer matrix and the inorganic filler achieves dynamic stress dispersion and release under the cyclic stress caused by thermal expansion and contraction, avoiding long-term stress accumulation. Through the above-mentioned multi-scale synergistic mechanism, the technical problem of the Type IV hydrogen storage cylinder liner easily becoming brittle and structurally failing under extreme temperature difference alternating environments is improved, significantly enhancing the material's stability and long-term durability under harsh working conditions. Detailed Implementation
[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0024] Example 1: This example provides a novel plastic inner liner for a hydrogen storage cylinder, prepared through the following steps: S1: 4g of N-vinylimidazolium and 10g of bromododecane were placed in a reaction vessel under a nitrogen atmosphere and stirred at 200r / min at 60℃ for 20h. After the reaction was completed, the mixture was cooled to room temperature, ethyl acetate was added to precipitate the product, and the mixture was filtered. The filter cake was washed twice with ethyl acetate and dried under vacuum at 40℃ to constant weight to obtain the long-chain vinylimidazolium bromide intermediate.
[0025] S2: 6g of long alkyl chain vinylimidazolium bromide intermediate, 4g of lithium bis(trifluoromethanesulfonylimide) and 100mL of acetone were placed in a nitrogen atmosphere reactor and stirred at 200r / min for 10h at 25℃. After the reaction was completed, the solvent was completely removed by rotary evaporation at 30℃. Extraction solution (dichloromethane and deionized water in a volume ratio of 1:1) was added to the product and extracted twice. The lower organic phase was collected, filtered to remove impurities, and then rotary evaporated at 30℃ until the solvent was completely removed. The product was then dried under vacuum at 40℃ to constant weight to obtain alkyl vinylimidazolium ionic liquid.
[0026] S3: Place 40g of nano-calcium carbonate and 300mL of anhydrous ethanol in a reaction vessel, stir at 200r / min for 10min at 50℃, add 2g of alkylvinylimidazolium ionic liquid, and continue the reaction for 1h at the same temperature and stirring rate. After the reaction is completed, sonicate for 20min, and vacuum dry the reaction solution at 40℃ to constant weight. After grinding, sieve through a 200-mesh sieve to obtain nano-calcium carbonate with double bonds and surface activation.
[0027] S4: Place 10g of fumed silica and 300mL of anhydrous ethanol in a reaction vessel, sonicate for 20min, add 150mL of silane coupling agent aqueous solution (the silane coupling agent aqueous solution is obtained by mixing γ-methacryloyloxypropyltrimethoxysilane and deionized water in a volume ratio of 1:2), stir at 200r / min at 60℃ for 2h, after the reaction is completed, centrifuge to collect the solid, wash twice with deionized water and anhydrous ethanol, and vacuum dry at 80℃ to constant weight to obtain silane-modified fumed silica.
[0028] S5: 360g of high-density polyethylene, 70g of ethylene-octene copolymer, 10g of PE-g-MAH, 5g of silane-modified fumed silica, 16g of surface-modified nano-calcium carbonate with double bonds, and 1g of antioxidant 1010 (antioxidant) are added to a twin-screw extruder. The extrusion temperature from the feed inlet to the die head is 150℃, 170℃, 180℃, and 190℃ respectively, and the screw speed is 200r / min. After extrusion, the material is cooled and pelletized, then added to a low-temperature grinding mill for pulverization. After sieving through a 200μm sieve, thermoplastic high-density polyethylene composite powder is obtained.
[0029] S6: Place 350g of thermoplastic high-density polyethylene composite powder and 4g of dicumyl peroxide (crosslinking agent) in a mixer and stir at 800r / min for 5min. Add the mixed material to a 5L plastic inner liner molding mold and purge the mold with nitrogen to replace the air. Set the rotational molding machine rotational parameters to 4r / min for the main shaft and 1r / min for the secondary shaft. Rotate at 140℃ for 20min, then raise the temperature to 170℃ and rotate for another 20min. After rotational molding, keep the mold rotating and cool with circulating air for 30min. After cooling, open the rotational molding mold to obtain a new type of hydrogen storage cylinder plastic inner liner.
[0030] Example 2: This example provides a novel plastic inner liner for a hydrogen storage cylinder, prepared through the following steps: S1: 5g of N-vinylimidazolium and 15g of bromododecane were placed in a reaction vessel under nitrogen atmosphere protection and stirred at 250r / min at 65℃ for 22h. After the reaction was completed, the mixture was cooled to room temperature, ethyl acetate was added to precipitate the mixture, and the precipitate was filtered. The filter cake was washed three times with ethyl acetate and dried under vacuum at 50℃ to constant weight to obtain the long-chain vinylimidazolium bromide intermediate.
[0031] S2: 8g of long alkyl chain vinylimidazolium bromide intermediate, 5g of lithium bis(trifluoromethanesulfonylimide) and 150mL of acetone were placed in a nitrogen atmosphere reactor and stirred at 250r / min at 30℃ for 12h. After the reaction was completed, the solvent was completely removed by rotary evaporation at 30℃. Extraction solution (dichloromethane and deionized water in a volume ratio of 1:1) was added to the product and extracted 3 times. The lower organic phase was collected, filtered to remove impurities, and then rotary evaporated at 30℃ until the solvent was completely removed. The product was then dried under vacuum at 50℃ to constant weight to obtain alkyl vinylimidazolium ionic liquid.
[0032] S3: Place 50g of nano-calcium carbonate and 400mL of anhydrous ethanol in a reaction vessel, stir at 250r / min for 15min at 55℃, add 3g of alkylvinylimidazolium ionic liquid, and continue the reaction for 1.5h at the same temperature and stirring rate. After the reaction is completed, sonicate for 30min, and vacuum dry the reaction solution at 50℃ to constant weight. After grinding, sieve through a 250-mesh sieve to obtain nano-calcium carbonate with double bonds and surface activation.
[0033] S4: Place 15g of fumed silica and 350mL of anhydrous ethanol in a reaction vessel, sonicate for 30min, add 225mL of silane coupling agent aqueous solution, stir at 250r / min at 70℃ for 3h, after the reaction is completed, centrifuge to collect the solid, wash three times with deionized water and anhydrous ethanol, and vacuum dry at 90℃ to constant weight to obtain silane-modified fumed silica.
[0034] S5: 380g of high-density polyethylene, 80g of ethylene-octene copolymer, 15g of PE-g-MAH, 8g of silane-modified fumed silica, 18g of surface-modified nano-calcium carbonate with double bonds, and 2g of antioxidant 1010 (antioxidant) are added to a twin-screw extruder. The extrusion temperatures from the feed inlet to the die head are 155℃, 175℃, 185℃, and 200℃ respectively, and the screw speed is 250r / min. After extrusion, the material is cooled and pelletized, then added to a low-temperature grinding mill for pulverization. After sieving through a 250μm sieve, thermoplastic high-density polyethylene composite powder is obtained.
[0035] S6: Place 400g of thermoplastic high-density polyethylene composite powder and 5g of dicumyl peroxide (crosslinking agent) in a mixer and stir at 1000r / min for 8min. Add the mixed material to a 6L plastic inner liner molding mold and purge the mold with nitrogen to replace the air. Set the rotational molding machine rotational parameters to 8r / min for the main shaft and 2r / min for the secondary shaft. Rotate at 145℃ for 25min, then raise the temperature to 180℃ and rotate for another 25min. After rotational molding, keep the mold rotating and cool with circulating air for 35min. After cooling, open the rotational molding mold to obtain a new type of hydrogen storage cylinder plastic inner liner.
[0036] Example 3: This example provides a novel plastic inner liner for a hydrogen storage cylinder, prepared through the following steps: S1: 6g of N-vinylimidazolium and 20g of bromododecane were placed in a reaction vessel under a nitrogen atmosphere and stirred at 300r / min at 70℃ for 24h. After the reaction was completed, the mixture was cooled to room temperature, ethyl acetate was added to precipitate the mixture, and the precipitate was filtered. The filter cake was washed four times with ethyl acetate and dried under vacuum at 60℃ to constant weight to obtain the long-chain vinylimidazolium bromide intermediate.
[0037] S2: 10g of long alkyl chain vinylimidazolium bromide intermediate, 6g of lithium bis(trifluoromethanesulfonylimide) and 200mL of acetone were placed in a nitrogen atmosphere reactor and stirred at 300r / min at 50℃ for 14h. After the reaction was completed, the solvent was completely removed by rotary evaporation at 30℃. The product was extracted four times with extractant, the lower organic phase was collected, filtered to remove impurities, and then completely removed by rotary evaporation at 30℃. The product was then dried under vacuum at 60℃ to constant weight to obtain alkyl vinylimidazolium ionic liquid.
[0038] S3: Place 60g of nano-calcium carbonate and 500mL of anhydrous ethanol in a reaction vessel, stir at 300r / min for 20min at 60℃, add 4g of alkylvinylimidazolium ionic liquid, and continue the reaction for 2h at the same temperature and stirring rate. After the reaction is completed, sonicate for 40min, and vacuum dry the reaction solution at 60℃ to constant weight. After grinding, sieve through a 300-mesh sieve to obtain nano-calcium carbonate with double bonds and surface activation.
[0039] S4: Place 20g of fumed silica and 600mL of anhydrous ethanol in a reaction vessel, sonicate for 40min, add 300mL of silane coupling agent aqueous solution, stir at 300r / min at 80℃ for 4h, after the reaction is completed, centrifuge to collect the solid, wash 4 times with deionized water and anhydrous ethanol, and vacuum dry at 100℃ to constant weight to obtain silane-modified fumed silica.
[0040] S5: 400g of high-density polyethylene, 90g of ethylene-octene copolymer, 20g of PE-g-MAH, 10g of silane-modified fumed silica, 20g of surface-modified nano-calcium carbonate with double bonds, and 3g of antioxidant 1010 (antioxidant) are added to a twin-screw extruder. The extrusion temperatures from the feed inlet to the die head are 160℃, 180℃, 190℃, and 210℃ respectively, and the screw speed is 300r / min. After extrusion, the material is cooled and pelletized, then added to a low-temperature grinding mill for pulverization. After sieving through a 300μm sieve, thermoplastic high-density polyethylene composite powder is obtained.
[0041] S6: Place 450g of thermoplastic high-density polyethylene composite powder and 6g of dicumyl peroxide (crosslinking agent) in a mixer and stir at 1200r / min for 10min. Add the mixed material to a 7L plastic inner liner molding mold and purge the mold with nitrogen to replace the air. Set the rotational molding machine rotational parameters to 12r / min for the main shaft and 3r / min for the secondary shaft. Rotate at 150℃ for 30min, then raise the temperature to 190℃ and rotate for another 30min. After rotational molding, keep the mold rotating and cool with circulating air for 40min. After cooling, open the rotational molding mold to obtain a new type of hydrogen storage cylinder plastic inner liner.
[0042] The novel hydrogen storage cylinder plastic liner prepared in Examples 1-3 above first utilizes the lone pair electrons of the nitrogen atom in the N-vinylimidazolium molecule to attack the electrophilic carbon center of bromododecane, resulting in a nucleophilic substitution reaction to generate a long-chain vinylimidazolium bromide intermediate. This intermediate then undergoes anion exchange with lithium bis(trifluoromethanesulfonylimide) to obtain an alkylvinylimidazolium ionic liquid. Subsequently, relying on the electrostatic attraction between the imidazolium cation and the calcium carbonate surface, and the hydrogen bond interaction between the active hydrogen on the imidazolium ring and the carbonate ion in the calcium carbonate, the ionic liquid is firmly anchored to the surface of nano-calcium carbonate, resulting in surface-activated nano-calcium carbonate containing double bonds. Simultaneously, through a hydrolysis-condensation reaction, γ-methacryloyloxypropyltrimethyl... Oxy-silanes form covalent bonds with hydroxyl groups on the surface of fumed silica, thereby introducing active double bonds on the surface of fumed silica to obtain silane-modified fumed silica. Then, using high-density polyethylene and ethylene-octene copolymer as the matrix, the material is uniformly dispersed by the strong shearing action of twin-screw extrusion to obtain thermoplastic high-density polyethylene composite powder. Finally, using the composite powder as raw material, the free radicals generated by the decomposition of dicumyl peroxide at high temperature are used to initiate a free radical polymerization reaction, driving the polymer matrix to undergo in-situ chemical copolymerization with the double bonds on the surface of nano-calcium carbonate containing double bonds and the double bonds on the surface of silane-modified fumed silica, constructing a strong organic-inorganic three-dimensional cross-linked network, and obtaining a novel plastic liner for hydrogen storage cylinders.
[0043] Comparative Example 1: The difference from Example 2 is that in step S5, commercially available nano-calcium carbonate is used instead of the surface-activated nano-calcium carbonate with double bonds prepared in step S3, while the other steps remain unchanged, to prepare a novel plastic liner for hydrogen storage cylinders.
[0044] Comparative Example 2: The difference from Example 2 is that commercially available fumed silica was used in step S5 instead of the silane-modified fumed silica prepared in step S4, while the other steps remained unchanged, and a new type of plastic liner for hydrogen storage cylinders was prepared.
[0045] Comparative Example 3: The difference from Example 2 is that the surface-activated nano-calcium carbonate with double bonds prepared in step S3 is not added in step S5, while the other steps remain unchanged, and a novel plastic liner for hydrogen storage cylinders is prepared.
[0046] Comparative Example 4: The difference from Example 2 is that the silane-modified fumed silica prepared in step S4 is not added in step S5, while the other steps remain unchanged, and a new type of plastic liner for hydrogen storage cylinder is prepared.
[0047] The high-density polyethylene purchased in the above embodiments and comparative examples was from Daqing Petrochemical Branch of China National Petroleum Corporation, grade 5000S, with a density of 0.954 g / cm3; the ethylene-octene copolymer was produced by Wanhua Chemical Group Co., Ltd., with a mass fraction of octene comonomer of 25%-30%; PE-g-MAH was produced by Ningbo Nengzhiguang New Material Technology Co., Ltd., with a grafting rate ≥0.9%; the fumed silica was produced by Evonik Industries AG, and was hydrophilic fumed silica; the nano-calcium carbonate was produced by Guangxi Huana New Material Technology Co., Ltd., with an average particle size of 40-80 nm.
[0048] The novel hydrogen storage cylinder plastic liners prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, and the test results are shown in Table 1. Sample preparation: The plastic inner liner of the novel hydrogen storage cylinder prepared in the above embodiments and comparative examples was cut along the circumference, and the sample was polished until the surface was flat and the thickness was uniform (average 2.5 mm). Some samples were placed in a high and low temperature alternating test chamber for pretreatment. The cycle program was set to first lower the temperature to -40℃ and keep it at a constant temperature for 1 hour, then quickly raise the temperature to 85℃ and keep it at a constant temperature for 1 hour. This was used as one cycle, and 100 cycles were performed continuously. After the cycle was completed, the sample was taken out and left to stand at room temperature for 24 hours for performance testing.
[0049] Mechanical properties: Referring to standard GB / T 1040.2-2006, pretreated and untreated specimens were subjected to tensile tests using a universal testing machine. The tensile speed was set to 50 mm / min until the specimen broke. The tensile strength and elongation at break of the material were recorded. The higher the tensile strength, the stronger the material's ability to resist external force damage and maintain structural dimensional stability. The higher the elongation at break, the better the material's flexibility and resistance to embrittlement.
[0050]
[0051] As shown in Table 1, the novel hydrogen storage cylinder plastic liners prepared in Examples 1-3 all exhibit superior performance compared to Comparative Examples 1-4. Furthermore, they maintain a high mechanical property retention rate even after 100 cycles of high and low temperature alternation. This demonstrates that the invention achieves a synergistic balance between rigidity and toughness by simultaneously introducing surface-activated nano-calcium carbonate with double bonds and silane-modified fumed silica to construct a synergistic composite reinforcement system. This system inhibits interfacial failure and microcrack propagation under high and low temperature alternation conditions, thereby achieving a synergistic improvement in the mechanical strength, toughness, and temperature difference stability of the hydrogen storage cylinder plastic liners.
[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.
Claims
1. A method for preparing a novel plastic inner liner for a hydrogen storage cylinder, characterized in that, Includes the following steps: Thermoplastic high-density polyethylene composite powder and dicumyl peroxide are placed in a mixer and stirred for 5-10 minutes. The mixture is then added to the plastic inner liner molding mold of a rotational molding machine. Under a nitrogen atmosphere, the mixture is rotated at 140-150℃ for 20-30 minutes. Subsequently, the temperature is raised to 170℃-190℃ and rotated for another 20-30 minutes. The mixture is then cooled with circulating air for 30-40 minutes to obtain a new type of hydrogen storage cylinder plastic inner liner. The thermoplastic high-density polyethylene composite powder, by weight, comprises the following raw materials: 360-400 parts of high-density polyethylene, 70-90 parts of ethylene-octene copolymer, 10-20 parts of PE-g-MAH, 5-10 parts of silane-modified fumed silica, 16-20 parts of surface-modified nano-calcium carbonate containing double bonds, and 1-3 parts of antioxidant 1010.
2. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 1, characterized in that, The surface-modified nano-calcium carbonate containing double bonds is prepared through the following steps: Nano-calcium carbonate and anhydrous ethanol were placed in a reaction vessel and stirred at 50-60℃ for 10-20 min. Alkylvinylimidazolium ionic liquid was added, and the reaction was continued for 1-2 h. The mixture was then dried under vacuum to constant weight to obtain surface-activated nano-calcium carbonate containing double bonds.
3. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 2, characterized in that, The ratio of the amount of nano-calcium carbonate, alkylvinylimidazolium ionic liquid and anhydrous ethanol is 40-60g: 2-4g: 300-500mL.
4. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 3, characterized in that, The alkylvinylimidazolium ionic liquid is prepared by the following steps: The long alkyl chain vinyl imidazole bromide intermediate, lithium bis(trifluoromethanesulfonylimide) and acetone were placed in a nitrogen atmosphere reactor and reacted at 25-35℃ for 10-14 h. The acetone was removed by rotary evaporation, the mixture was extracted, the organic phase was collected, filtered, rotary evaporated, and vacuum dried to constant weight to obtain the alkyl vinyl imidazole ionic liquid. The ratio of the long alkyl chain vinylimidazolium bromide intermediate, lithium bis(trifluoromethanesulfonylimide), and acetone is 6-10 g: 4-6 g: 100-200 mL.
5. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 4, characterized in that, The long alkyl chain vinylimidazolium bromide intermediate is prepared by the following steps: N-vinylimidazolium and bromododecane were placed in a reaction vessel under nitrogen atmosphere and reacted at 60-70℃ for 20-24h. Ethyl acetate was added to precipitate the product, which was then filtered, washed, and vacuum dried to constant weight to obtain a long-chain vinylimidazolium bromide intermediate. The mass ratio of N-vinylimidazolium to bromododecane is 4-6:10-20.
6. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 1, characterized in that, The silane-modified fumed silica is prepared through the following steps: Fumed silica and anhydrous ethanol were placed in a reaction vessel and ultrasonically dispersed for 20-40 min. An aqueous solution of silane coupling agent was added, and the mixture was reacted at 60-80℃ for 2-4 h. After centrifugation, washing, and vacuum drying to constant weight, silane-modified fumed silica was obtained. The ratio of the amount of fumed silica, silane coupling agent aqueous solution and anhydrous ethanol is 10-20g: 150-300mL: 300-600mL.
7. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 6, characterized in that, The aqueous solution of the silane coupling agent is obtained by mixing γ-methacryloxypropyltrimethoxysilane and deionized water at a volume ratio of 1:
2.
8. The method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 1, characterized in that, The thermoplastic high-density polyethylene composite powder is prepared through the following steps: High-density polyethylene, ethylene-octene copolymer, PE-g-MAH, silane-modified fumed silica, surface-modified nano-calcium carbonate with double bonds, and antioxidant 1010 are added to a twin-screw extruder, extruded, cooled and pelletized, then added to a low-temperature grinding mill for pulverization and sieving to obtain thermoplastic high-density polyethylene composite powder.
9. A method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 8, characterized in that, The extrusion temperatures of the twin-screw extruder from the feed inlet to the die head are 150-160℃, 170-180℃, 180-190℃ and 190-210℃ respectively.
10. A method for preparing a novel plastic liner for a hydrogen storage cylinder according to claim 1, characterized in that, The volume of the plastic inner liner molding mold is 5-7L.