A phase change material, its preparation method and application

Abstract

This invention belongs to the field of pipeline emergency repair and sealing technology, specifically relating to a phase change material, its preparation method, and its application. This invention provides a phase change material prepared from raw materials comprising the following mass fractions: 10-15% cyclodextrin, 15-25% polyethylene glycol, 1-5% temperature regulator, 5-8% salt bridge, and the balance water; the temperature regulator includes substituted benzoic acid. In this phase change material, polyethylene glycol molecules can enter the cavity of cyclodextrin, forming a tandem linear structure. The carboxyl groups in the temperature regulator react with the hydroxyl groups in the cyclodextrin to form a grafted structure. When the temperature rises, the salt bridge connects the linear molecular chains formed by the polyethylene glycol entering the cyclodextrin cavity. The cyclodextrins aggregate through hydrogen bonding, thereby forming a three-dimensional network structure. The resulting colloid has high strength, with a viscosity of 100,000-150,000 mPa·s after gelation, and can withstand high temperatures of 60-75°C.

Description

Technical Field

[0001] This invention belongs to the field of pipeline emergency repair and sealing technology, specifically relating to a phase change material, its preparation method, and its application. Background Technology

[0002] In pipeline transportation projects, sudden emergencies such as oil and gas leaks are frequently encountered, requiring emergency repairs. Furthermore, during long-term transportation, pipeline operations are unavoidable to ensure safety, including rerouting and maintenance. To minimize losses from these operations, it is necessary to conduct targeted work on specific sections of the pipeline while it is operating normally, requiring the isolation of those sections.

[0003] Pipeline transport media typically include flammable and explosive products such as petroleum, natural gas, and refined oil. Therefore, hot work is an extremely dangerous and high-risk activity during pipeline engineering operations. This necessitates pipeline isolation materials with excellent sealing properties, high sealing strength, and fire and high-temperature resistance. Common pipeline isolation methods are primarily physical isolation, such as folded plugs and capsule-type plugging techniques, which require complex external instruments, are cumbersome to operate, and are difficult to move. Another common chemical isolation method is the grease wall method; however, grease wall isolation is highly susceptible to melting at high temperatures, resulting in cracks or even collapse, posing a significant threat to the safety of operators. Therefore, the development of a sealing material with high sealing strength and the ability to withstand temperatures of 60–75°C is urgently needed. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a phase change material, its preparation method, and its application. The phase change material of this invention forms a colloidal structure with high strength at a temperature of 60–75°C.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a phase change material, prepared from raw materials comprising the following mass fractions:

[0007] Cyclodextrin 10-15%, polyethylene glycol 15-25%, temperature regulator 1-5%, salt bridge 5-8%, and the balance water;

[0008] The temperature regulator includes substituted benzoic acid.

[0009] Preferably, the substituted benzoic acid includes one or more of p-aminobenzoic acid, p-methylbenzoic acid, p-propylbenzoic acid, p-dodecylbenzoic acid, p-hexadecylbenzoic acid, and p-nitrobenzoic acid.

[0010] Preferably, the mass fraction of the temperature regulator in the raw material is 2%.

[0011] Preferably, the cyclodextrin includes α-cyclodextrin and / or β-cyclodextrin.

[0012] Preferably, the polyethylene glycol includes one or more of PEG-200, PEG-400 and PEG-600.

[0013] Preferably, the salt bridge comprises potassium oxalate and / or potassium carbonate.

[0014] Preferably, the phase change material is prepared from raw materials comprising the following mass fractions: 10-11% cyclodextrin, 15-20% polyethylene glycol, 1-2% temperature regulator, 5-6% salt bridge, and the balance being water.

[0015] The present invention also provides a method for preparing the phase change material described in the above technical solution, comprising the following steps:

[0016] The phase change material is obtained by mixing and dissolving cyclodextrin, polyethylene glycol, temperature regulator, salt bridge and water.

[0017] The present invention also provides the application of the phase change material described in the above technical solution or the phase change material obtained by the above preparation method in pipeline sealing.

[0018] Preferably, the application includes the following steps:

[0019] The phase change material is heated to obtain a colloid;

[0020] The colloid is introduced into the pipe to be sealed, thereby sealing the pipe.

[0021] The present invention provides a phase change material, which is prepared from raw materials comprising the following mass fractions: 10-15% cyclodextrin, 15-25% polyethylene glycol, 1-5% temperature regulator, 5-8% salt bridge and the balance water; wherein the temperature regulator comprises substituted benzoic acid.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] In this invention, polyethylene glycol molecules in the phase change material can enter the cavity of cyclodextrin to form a tandem linear structure. The carboxyl groups in the temperature regulator react with the hydroxyl groups in the cyclodextrin to form a graft structure. The temperature regulator changes the gelation temperature of the system by altering the solubility of cyclodextrin in water and the steric hindrance between cyclodextrins. When the temperature rises, salt bridges connect the linear molecular chains formed by polyethylene glycol molecules entering the cyclodextrin cavity. The cyclodextrins aggregate through hydrogen bonding to form a three-dimensional network structure. The resulting colloid has high strength, with a viscosity of 100,000–150,000 mPa·s after gelation, and can withstand high temperatures of 60–75°C.

[0024] Furthermore, this invention utilizes supramolecular chemistry principles to construct a phase change gel system. Self-assembly into a gel is achieved through non-covalent interactions such as hydrogen bonds between cyclodextrins, molecular-ionic forces (salt bridges exist in aqueous solution as potassium ions and acid radicals, which form molecular-ionic forces with cyclodextrin molecules), and host-guest interactions between cyclodextrins and polyethylene glycol. This enables effective sealing. The phase change material exhibits excellent thermal responsiveness, allowing for gel formation upon heating and self-destruction upon further heating. Additionally, this invention incorporates a benzoic acid derivative as a temperature regulator to adjust the gel formation temperature, adapting to different operating environments.

[0025] This invention also provides the application of the phase change material described in the above technical solution in pipeline plugging. The phase change material system of this invention is liquid before gelation, with low viscosity (30 mPa·s), strong fluidity, and is very easy to inject into pipelines. When the temperature is raised to the gelation temperature of 60-75℃, the viscosity of the system increases and it loses its fluidity. The phase change material of this invention contains a temperature regulator, which can adjust the electron cloud density on the surface of cyclodextrin, shorten the gelation time (only 0.5-2 hours), and the gel strength is high, which can effectively plug pipelines. After the plugging is completed, it can degrade on its own, which is environmentally friendly. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a photograph of the phase change material in Example 1 before it is gelled;

[0028] Figure 2 This is a photograph of the phase change material of Example 1 after gelation;

[0029] Figure 3 This is a photograph of the phase change material after it has been broken down in Example 1. Detailed Implementation

[0030] This invention provides a phase change material, prepared from raw materials comprising the following mass fractions:

[0031] Cyclodextrin 10-15%, polyethylene glycol 15-25%, temperature regulator 1-5%, salt bridge 5-8%, and the balance water;

[0032] The temperature regulator includes substituted benzoic acid.

[0033] Unless otherwise specified, all materials and equipment used in this invention are commercially available products in the field.

[0034] In this invention, the mass fraction of cyclodextrin in the raw material is preferably 10-11%.

[0035] In this invention, the cyclodextrin preferably includes α-cyclodextrin and / or β-cyclodextrin. The cyclodextrin molecule has a cavity and hydroxyl groups. Polyethylene glycol molecules enter the cyclodextrin cavity to form a tandem linear structure. At the same time, the carboxyl group of the temperature regulator can react with the hydroxyl group of the cyclodextrin to form a grafted structure.

[0036] In this invention, the mass fraction of polyethylene glycol in the raw material is preferably 15-20%.

[0037] In this invention, the polyethylene glycol preferably includes one or more of PEG-200, PEG-400 and PEG-600, and the molecular chains of the polyethylene glycol can enter the cavity of the cyclodextrin to form a tandem linear structure.

[0038] In this invention, the mass fraction of the temperature regulator in the raw material is preferably 1-2%.

[0039] In this invention, the substituted benzoic acid is a benzoic acid derivative containing a carboxyl group. Preferably, the substituted benzoic acid includes one or more of p-aminobenzoic acid, p-methylbenzoic acid, p-propylbenzoic acid, p-dodecylbenzoic acid, p-hexadecylbenzoic acid, and p-nitrobenzoic acid. The temperature regulator alters the gelation temperature of the system by changing the solubility of cyclodextrin in water and the steric hindrance between cyclodextrins. The amount of temperature regulator added can adjust the electron cloud density on the surface of the cyclodextrin, thereby affecting the gelation time. Since the temperature regulator is a benzoic acid derivative, the benzene ring is a rigid structure that provides support in the gel system, improving the gel strength.

[0040] In this invention, the mass fraction of salt bridge in the raw material is preferably 5-6%.

[0041] In this invention, the salt bridge preferably comprises potassium oxalate and / or potassium carbonate. The function of the salt bridge is to connect polyethylene glycol molecules into the linear molecular chain formed by the cyclodextrin cavity when the temperature rises.

[0042] In this invention, the water mass fraction in the raw material is preferably 63-68%, and the water is encapsulated in the network structure as a solvent, and the system undergoes a phase transition to form a gel.

[0043] In this invention, the phase change material is preferably made from raw materials comprising the following mass fractions: 10-11% cyclodextrin, 15-20% polyethylene glycol, 1-2% temperature regulator, 5-6% salt bridge, and the balance being water.

[0044] The present invention also provides a method for preparing the phase change material described in the above technical solution, comprising the following steps:

[0045] The phase change material is obtained by mixing and dissolving cyclodextrin, polyethylene glycol, temperature regulator, salt bridge and water.

[0046] In this invention, the mixing method is preferably stirring. This invention does not have special requirements for the stirring speed and time, as long as the phase change material is made clear and transparent.

[0047] In this invention, the stirring temperature is preferably room temperature.

[0048] The present invention also provides the application of the phase change material described in the above technical solution or the phase change material obtained by the above preparation method in pipeline sealing.

[0049] In this invention, the application preferably includes the following steps:

[0050] The phase change material is heated to obtain a colloid;

[0051] The colloid is introduced into the pipe to be sealed, thereby sealing the pipe.

[0052] In this invention, the heating temperature is preferably 60-75°C, more preferably 70-75°C, and the heating time is preferably 0.5-2h, more preferably 1-1.5h.

[0053] In this invention, the phase change material forms a colloid with high strength, and the viscosity after gelation is preferably 100,000 to 150,000 mPa·s, indicating high gel strength.

[0054] In this invention, the application process preferably includes debonding. After the operation is completed, the phase change material of this invention will automatically debond and become liquid, which will be discharged along with the oil and gas in the sealed pipeline.

[0055] In this invention, the breaking time is preferably 0.5 to 4 days, more preferably 20h, 24h or 48h.

[0056] In this invention, the temperature for breaking the glue is preferably 60-75°C, more preferably 70°C.

[0057] To further illustrate the present invention, the phase change materials, their preparation methods, and applications of the present invention are described in detail below with reference to the accompanying drawings and embodiments, but these descriptions should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] A method for preparing a phase change material for pipeline sealing is as follows:

[0060] Weigh out 11g of β-cyclodextrin, 15g of PEG-400, 5g of potassium oxalate and 1g of para-aminobenzoic acid and put them into a sample bottle. Add 68g of water and stir at room temperature until clear and transparent.

[0061] The sample vials containing the reagent were sealed and placed in an oil bath. The temperature was increased from room temperature at a rate of 0.2℃ / min until the liquid became flocculent or solidified. The temperature was then maintained, and the gelation process was observed. Gel formation was complete when no liquid flowed down after the sample vial was inverted. The gelation temperature was recorded as 60℃. Viscosity tests showed that the viscosity before gelation was 30 mPa·s, and the viscosity after gelation was 148,000 mPa·s, indicating high gel strength.

[0062] The gelled sample was placed in an oil bath at the gelation temperature and observed. As time went on, the gel slowly broke down, and the gel breaking time was recorded as 48 hours.

[0063] Example 2

[0064] A method for preparing a phase change material for pipeline sealing is as follows:

[0065] Weigh out 11g of β-cyclodextrin, 20g of PEG-400, 5g of potassium oxalate and 1g of p-methylbenzoic acid and put them into a sample bottle. Add 63g of water and stir at room temperature until clear and transparent.

[0066] The sample vials containing the reagent were sealed and placed in an oil bath. The temperature was increased from room temperature at a rate of 0.2℃ / min until the liquid became flocculent or solidified. The temperature was then maintained, and the gelation process was observed. Gel formation was complete when no liquid flowed down after the sample vial was inverted. The gelation temperature was recorded as 70℃. Viscosity tests showed that the viscosity before gelation was 30 mPa·s, and the viscosity after gelation was 135,000 mPa·s, indicating high gel strength.

[0067] The gelled sample was placed in an oil bath at the gelation temperature and observed. As time went on, the gel slowly broke down, and the gel breaking time was recorded as 24 hours.

[0068] Example 3

[0069] A method for preparing a phase change material for pipeline sealing is as follows:

[0070] Weigh out 10g of β-cyclodextrin, 15g of PEG-400, 6g of potassium oxalate and 2g of p-dodecylbenzoic acid and put them into a sample bottle. Add 67g of water and stir at room temperature until clear and transparent.

[0071] The sample vials containing the reagent were sealed and placed in an oil bath. The temperature was increased from room temperature at a rate of 0.2℃ / min until the liquid became flocculent or solidified. The temperature was then maintained, and the gelation process was observed. Gel formation was complete when no liquid flowed down after the sample vial was inverted. The gelation temperature was recorded as 75℃. Viscosity tests showed that the viscosity before gelation was 30 mPa·s, and the viscosity after gelation was 126,000 mPa·s, indicating high gel strength.

[0072] The gelled sample was placed in an oil bath at the gelation temperature and observed for a while. As time went on, the gel slowly broke down, and the gel breaking time was recorded as 20 hours.

[0073] Table 1. Phase transition processes after adding different temperature regulators in Examples 1-3.

[0074]

[0075] Note: The gelation time is the time from the appearance of flocculent or solid particles to the time when the sample bottle is inverted and no liquid flows down; the gel breaking time is the time from the beginning of liquid appearance to the complete disappearance of solids.

[0076] Example 4

[0077] A method for preparing a phase change material for pipeline sealing is as follows:

[0078] Weigh out 10g of β-cyclodextrin, 20g of PEG-200, 5g of potassium oxalate and 1g of p-methylbenzoic acid and put them into a sample bottle. Add 64g of water and stir at room temperature until clear and transparent.

[0079] The sample vials containing the reagent were sealed and placed in an oil bath. The temperature was increased from room temperature at a rate of 0.2℃ / min until the liquid became flocculent or solidified. The temperature was then maintained, and the gelation process was observed. Gel formation was complete when no liquid flowed down after the sample vial was inverted. The gelation temperature was recorded as 70℃, and the gelation time as 2 hours. Viscosity tests showed that the viscosity before gelation was 30 mPa·s, and the viscosity after gelation was 121,000 mPa·s, indicating high gel strength.

[0080] The gelled sample was placed in an oil bath at the gelation temperature (70°C) and observed for a period of time. The gel slowly broke down over time, and the gel breaking time was recorded as 96 hours.

[0081] Comparative Example 1

[0082] A method for preparing a phase change material for pipeline sealing is as follows:

[0083] Weigh out 10g of β-cyclodextrin, 20g of PEG-200 and 5g of potassium oxalate and put them into sample bottles. Add 65g of water and stir at room temperature until clear and transparent.

[0084] The sample vials containing the reagent were sealed and placed in an oil bath. The temperature was increased from room temperature at a rate of 0.2℃ / min until the liquid became flocculent or solidified. The temperature was then maintained, and the gelation process was observed. Gel formation was complete when no liquid flowed down after the sample vial was inverted. The gelation temperature was recorded as 85℃, and the gelation time as 3 hours. Viscosity tests showed that the viscosity before gelation was 30 mPa·s, and the viscosity after gelation was 53,000 mPa·s, indicating low gel strength.

[0085] The gelled sample was placed in an oil bath at the gelation temperature (85°C) and observed for a period of time. The gel slowly broke down over time, and the gel breaking time was recorded as 72 hours.

[0086] Figures 1-3 These are photographs of the phase change material in different states as described in Example 1. Figure 1 Before gelation, Figure 2 After gelation, Figure 3 After the glue breaks. Figures 1-3 It is known that the present invention has successfully developed a temperature-controlled phase change material. This material can achieve a "liquid-solid-liquid" phase change under temperature control. It has low viscosity before gelation and after gelation, making it easy to transport and store. In the gelation state, it has high strength and can be used in the field of pipeline sealing.

[0087] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on the present invention without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A phase change material, characterized in that, is prepared from raw materials comprising the following mass fractions: cyclodextrin 10~15%, polyethylene glycol 15~25%, temperature regulator 1~5%, salt bridge 5~8%, and the balance of water; the temperature regulator comprises substituted benzoic acid; the substituted benzoic acid comprises one or more of p-aminobenzoic acid, p-methylbenzoic acid, p-propylbenzoic acid, p-dodecylbenzoic acid, p-hexadecylbenzoic acid, and p-nitrobenzoic acid; the polyethylene glycol comprises one or more of PEG-200, PEG-400, and PEG-600; the salt bridge comprises potassium oxalate and / or potassium carbonate.

2. The phase change material of claim 1, wherein, The mass fraction of the temperature regulator in the raw materials is 2%.

3. The phase change material of claim 1, wherein, The cyclodextrin comprises α-cyclodextrin and / or β-cyclodextrin.

4. The phase change material according to any one of claims 1 to 3, characterized in that, The phase change material is prepared from raw materials comprising the following mass fractions: cyclodextrin 10~11%, polyethylene glycol 15~20%, temperature regulator 1~2%, salt bridge 5~6%, and the balance of water.

5. The method of producing a phase change material according to any one of claims 1 to 4, characterized by, comprising the following steps: mixing and dissolving cyclodextrin, polyethylene glycol, temperature regulator, salt bridge, and water to obtain the phase change material.

6. Use of the phase change material of any one of claims 1~4 or the phase change material obtained by the preparation method of claim 5 in pipe plugging.

7. Use according to claim 6, characterized in that, The use comprises the following steps: heating the phase change material to obtain a colloid; introducing the colloid into a pipe to be plugged to plug the pipe.

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