A lightweight flexible shape memory constant temperature phase change foam and a preparation method thereof

Abstract

The application discloses a light flexible shape memory constant-temperature phase change foam and a preparation method thereof, relates to the technical field of phase change foam materials, and the constant-temperature phase change foam is prepared from the following components in parts by weight: 100 parts of encapsulating material, 50-200 parts of phase change material, 10-50 parts of nucleating agent, 1-3 parts of vulcanizing agent, 1-2 parts of vulcanization aid, 1-2 parts of activating agent, 3-5 parts of zinc oxide, 1-3 parts of anti-aging agent, 0.5-1 part of anti-scorching agent and 0.5-2 parts of temperature change powder. The application adopts the environment-friendly supercritical foaming technology and fine material design, effectively prevents PCM leakage, and guarantees the environmental friendliness and energy storage effect. The material has excellent flexibility and shape memory characteristics, and is suitable for building thermal insulation and electronic heat dissipation and other fields. Through optimization of the structure, efficient energy storage and low density are realized, and the temperature change powder is introduced to directly indicate the phase change process, and the use convenience is improved.

Description

Technical Field

[0001] This invention relates to the field of phase change foam materials technology, and in particular to a lightweight, flexible, shape-memory isothermal phase change foam and its preparation method. Background Technology

[0002] With increasingly stringent global standards for energy conservation and emission reduction, the demand for high-efficiency energy-saving materials in the construction sector continues to grow. Particularly in the research and development of building exterior wall insulation materials, the aim is to reduce energy consumption, maintain constant indoor temperatures, and improve the comfort of living and working environments. Phase change materials (PCMs), due to their unique heat storage and release properties, have become one of the key technologies for improving building energy efficiency. PCMs change their state of matter within a specific temperature range, absorbing or releasing a large amount of latent heat to store and convert heat, thereby maintaining a constant environmental temperature. However, despite the immense theoretical potential of PCM technology, its practical application still faces several technical challenges and limitations.

[0003] Currently, PCM materials used in building insulation are mainly added to traditional insulation materials. While these materials achieve temperature control and energy storage to some extent, several significant problems exist. First, PCM is prone to leakage during phase change, which not only pollutes the environment but also severely impacts the material's lifespan and energy storage efficiency. Second, most current PCM insulation materials remain solid at the phase change temperature, limiting the material's tight adhesion to the surface of the object being covered, thus affecting its performance and application range. Furthermore, existing technologies struggle to maintain low density and a uniform pore structure while simultaneously filling large quantities of PCM for efficient energy storage. Moreover, most materials achieve their cell structure by adding chemical foaming agents, a method that is not only environmentally unfriendly but also leads to uneven cell size distribution, voids, and cell breakage. Finally, current technologies cannot visually display the phase change process of PCM, making it difficult to control and predict the start and end times of the phase change.

[0004] In view of the limitations of the prior art, the present invention aims to solve a series of problems existing in the application of PCM-doped thermal insulation materials. Specifically, the objectives of the present invention include: (1) developing a new type of phase change foam material that can effectively prevent leakage of PCM during the phase change process, ensuring environmental friendliness and long-term stable energy storage effect; (2) realizing the flexibility and shape memory characteristics of the material at the phase change temperature through innovative material design, so that the material can better fit various surfaces and broaden its application range; (3) optimizing the material structure to achieve efficient filling of a large amount of PCM while maintaining a low density and uniform pore structure, thus achieving excellent energy storage effect; (4) adopting environmentally friendly supercritical fluid foaming technology to avoid the use of chemical foaming agents and obtain a uniform pore structure; (5) introducing thermochromic powder whose color change temperature range matches the phase change temperature of the phase change material to intuitively indicate the phase change process and help users accurately grasp the start and end time of the phase change. By solving these technical problems, the present invention aims to provide a more effective, environmentally friendly and reliable solution for the field of building thermal insulation materials. Summary of the Invention

[0005] In order to achieve the above-mentioned objectives and address the above-mentioned technical problems:

[0006] This invention provides a lightweight, flexible shape memory thermostatic phase change foam, which is prepared from the following components in parts by weight: 100 parts encapsulation material, 50-200 parts phase change material, 10-50 parts nucleating agent, 1-3 parts vulcanizing agent, 1-2 parts co-vulcanizing agent, 1-2 parts activator, 3-5 parts zinc oxide, 1-3 parts antioxidant, 0.5-1 part anti-scorching agent, and 0.5-2 parts thermochromic powder.

[0007] Preferably, the encapsulation material is one or more of natural rubber, styrene-butadiene rubber, cis-butadiene rubber, ethylene propylene rubber, butyl rubber, and SEBS.

[0008] Preferably, the phase change material is solid paraffin.

[0009] Preferably, the solid paraffin has a melting point of 48-70°C.

[0010] Preferably, the nucleating agent is one of silica aerogel, fumed silica, carbon black, calcium carbonate, nano titanium dioxide, carbon nanotubes, and graphene.

[0011] Preferably, the vulcanizing agent is any one of bis-tert-butylperoxyisopropylbenzene, dicumyl peroxide, 2,4-di-tert-butylperoxyisopropylbenzene, benzoyl peroxide, bis(2,4-di-tert-butylperoxyisopropylbenzene), and sulfur; the co-vulcanizing agent is any one of triallyl isocyanurate, N,N'-m-phenylenebismaleimide, trialkylmethylpropane methacrylate, and triallyl cyanurate; the activator is stearic acid; the anti-scorching agent is any one of N-cyclohexylthiophthalimide, salicylic acid, phthalic anhydride, and nitroso compounds; the antioxidant is any one of antioxidant RD, antioxidant OD, and antioxidant H; and the thermochromic powder is available in temperatures ranging from 40 to 70°C.

[0012] This application also provides a method for preparing the above-mentioned phase change foam, comprising the following steps:

[0013] S1 mixes the encapsulation material and phase change material using a melt mixing method. After mixing, a nucleating agent is added, and after mixing, a vulcanizing agent, a vulcanizing aid, an activator, zinc oxide, an antioxidant, an anti-scorching agent, and a thermochromic powder are added and mixed evenly to obtain a compounded rubber.

[0014] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 140-170℃, and the molding time includes hot pressing and cold pressing to obtain the molded rubber.

[0015] S3 The molding material from step S2 is subjected to supercritical foaming in a foaming kettle. The foaming gas is carbon dioxide, nitrogen, or a mixture of both. The foaming time is 1-3 hours and the gas pressure is 15-30 MPa to obtain the foamed material.

[0016] S4 involves a second high-temperature vulcanization of the foaming material from step S3 in an oven at a temperature of 170-200℃ to obtain phase change foam.

[0017] Preferably, the mixing temperature in step S1 is 80-100℃; the hot pressing time in step S2 is 4-10 minutes.

[0018] Preferably, the foaming temperature in step S3 is 60-100℃.

[0019] Preferably, the vulcanization time in step S4 is 20-30 minutes.

[0020] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0021] Effectively prevents PCM leakage: This invention, through meticulous material design and preparation processes, ensures the stability of phase change materials (such as solid paraffin) during the phase change process, effectively preventing PCM leakage during use and improving environmental friendliness and long-term stable energy storage performance. In particular, the use of supercritical foaming technology avoids the use of chemical foaming agents, which is not only environmentally friendly but also yields a more uniform and fine cell structure, further preventing PCM leakage.

[0022] Flexibility and Shape Memory Properties: The phase change foam material of this invention exhibits excellent flexibility and shape memory properties at the phase change temperature, enabling the material to better conform to various surface shapes and significantly expanding its application range in areas such as building thermal insulation and electronic product heat dissipation. These properties are achieved through the optimal combination of encapsulation materials and nucleating agents, effectively improving the material's flexibility and practical value.

[0023] Highly efficient energy storage and low-density structure: This invention optimizes the material structure of phase change foam, maintaining a low-density and uniform pore structure even when filled with a large amount of PCM, achieving excellent energy storage performance. This is verified by mechanical property tests and scanning electron microscopy (SEM) images of the proportions and examples, demonstrating that the material can achieve efficient thermal energy storage and regulation without adding excessive weight.

[0024] Environmentally friendly manufacturing process: The supercritical foaming technology used is more environmentally friendly than traditional chemical foaming methods, reducing its impact on the environment. Furthermore, the selected encapsulation materials and nucleating agents are all environmentally friendly, ensuring a green and safe production process.

[0025] The introduction of thermochromic powder: By introducing thermochromic powder into phase change foam materials, the phase change process of the material can be intuitively indicated, helping users to accurately grasp the start and end time of the phase change, and improving the convenience and efficiency during use. Attached Figure Description

[0026] Figure 1 These are photos of the foaming experiments of Example 2 and Comparative Example 3 of the present invention.

[0027] Figure 2 This is a scanning electron microscope (SEM) image of Comparative Example 1 of the present invention.

[0028] Figure 3 This is a scanning electron microscope (SEM) image of Embodiment 1 of the present invention.

[0029] Figure 4 This is a scanning electron microscope (SEM) image of Comparative Example 2 of the present invention.

[0030] Figure 5This is a scanning electron microscope (SEM) image of Comparative Example 4 of the present invention.

[0031] Figure 6 This is a scanning electron microscope (SEM) image of Embodiment 2 of the present invention.

[0032] Figure 7 This is a scanning electron microscope (SEM) image of Embodiment 3 of the present invention.

[0033] Figure 8 This is a scanning electron microscope (SEM) image of Embodiment 4 of the present invention.

[0034] Figure 9 This is a scanning electron microscope (SEM) image of Embodiment 5 of the present invention.

[0035] Figure 10 This is a scanning electron microscope (SEM) image of Embodiment 6 of the present invention.

[0036] Figure 11 This is a scanning electron microscope (SEM) image of Embodiment 7 of the present invention.

[0037] Figure 12 This is a scanning electron microscope (SEM) image of Embodiment 8 of the present invention.

[0038] Figure 13 This is a scanning electron microscope (SEM) image of Embodiment 9 of the present invention.

[0039] Figure 14 This is a scanning electron microscope (SEM) image of Embodiment 10 of the present invention.

[0040] Figure 15 This is a scanning electron microscope (SEM) image of Embodiment 11 of the present invention.

[0041] Figure 16 This is a scanning electron microscope (SEM) image of Embodiment 12 of the present invention.

[0042] Figure 17 These are photographs of paraffin leakage experiments in Example 2 and Comparative Example 3 of the present invention.

[0043] Figure 18 This is a density curve diagram of Embodiment 2 and Comparative Example 3 of the present invention.

[0044] Figure 19 This is a quality curve graph of Embodiment 2 and Comparative Example 3 of the present invention.

[0045] Figure 20 This is a scanning electron microscope (SEM) image of Embodiment 13 of the present invention.

[0046] Figure 21 This is a scanning electron microscope (SEM) image of Embodiment 14 of the present invention.

[0047] Figure 22This is a scanning electron microscope (SEM) image of Embodiment 15 of the present invention.

[0048] Figure 23 This is a scanning electron microscope (SEM) image of Embodiment 16 of the present invention.

[0049] Figure 24 This is a scanning electron microscope (SEM) image of Embodiment 17 of the present invention.

[0050] Figure 25 This is a scanning electron microscope (SEM) image of Embodiment 18 of the present invention.

[0051] Figure 26 This invention describes the color change process of materials during phase transition.

[0052] Figure 27 This is a photograph illustrating the shape memory adaptability of the present invention.

[0053] Figure 28 This is a schematic diagram of the shape memory test principle of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0055] Example 1

[0056] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0057] S1 mixes 100 parts of ethylene propylene rubber and 50 parts of solid paraffin wax with a melting point of 56℃ using a melt mixing method at a mixing temperature of 80℃ and a rotor speed of 60 rpm; then reduces the rotor speed to 30 rpm, adds 10 parts of silica aerogel, and adjusts the rotor speed back to 60 rpm, mixing for 2 minutes; then adds 2 parts of di-tert-butylperoxyisopropylbenzene, 1 part of triallyl isocyanurate, 1 part of stearic acid, 5 parts of zinc oxide, 2 parts of antioxidant OD, 0.5 parts of N-cyclohexylthiophthalimide, and 1 part of thermochromic powder with a melting point of 56℃ (the thermochromic powder is commercially available and purchased from Qingdao Chongyu), and mixes for 4 minutes to obtain the compound;

[0058] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 160°C, and the molding time includes 5 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0059] S3 The molding material from step S2 is foamed in a foaming kettle with supercritical CO2 for 1 hour, at a foaming temperature of 60°C and a gas pressure of 17MPa to obtain the foamed material.

[0060] S4 The foaming material from step S3 is subjected to a second high-temperature vulcanization in an oven at a temperature of 170°C for 20 minutes to obtain phase change foam.

[0061] Example 2

[0062] Prepared using the same method as in Example 1, except that the amount of solid paraffin is 100 parts and the hot-pressing time is 6 minutes.

[0063] Example 3

[0064] Prepared using the same method as in Example 2, except that the amount of solid paraffin is 150 parts.

[0065] Example 4

[0066] Prepared using the same method as in Example 1, except that the amount of solid paraffin is 200 parts and the hot pressing time is 8 minutes.

[0067] Example 5

[0068] Prepared using the same method as in Example 3, except that the amount of silica aerogel is 20 parts.

[0069] Example 6

[0070] Prepared using the same method as in Example 5, except that the amount of silica aerogel is 30 parts and the vulcanization time is 15 minutes.

[0071] Example 7

[0072] Prepared using the same method as in Example 5, except that the amount of silica aerogel is 40 parts, the hot pressing time is 4 minutes, and the vulcanization time is 10 minutes.

[0073] Example 8

[0074] Prepared using the same method as in Example 5, except that the silica aerogel is 50 parts, the hot pressing time is 5 minutes, and the vulcanization time is 10 minutes.

[0075] Example 9

[0076] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0077] S1 mixes 100 parts of natural rubber and 100 parts of solid paraffin wax with a melting point of 68°C using a melt mixing method at a mixing temperature of 80°C and a rotor speed of 60 rpm. Then, the rotor speed is reduced to 30 rpm, 10 parts of silica aerogel are added, and the rotor speed is adjusted back to 60 rpm and mixed for 2 minutes. Next, 3 parts of sulfur, 2 parts of accelerator TMTD, 2 parts of stearic acid, 4 parts of zinc oxide, 3 parts of antioxidant OD, 1 part of N-cyclohexylthiophthalimide, and 1 part of thermochromic powder with a melting point of 68°C (thermochromic powder is commercially available and purchased from Qingdao Chongyu) are added and mixed for 4 minutes to obtain the compound.

[0078] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then subjected to high-temperature molding on a flat vulcanizing machine. The vulcanization temperature is set to 160°C, and the molding time includes 4 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0079] S3 The molding material from step S2 is foamed in a foaming kettle with supercritical N2 for 2 hours, at a foaming temperature of 80°C and a gas pressure of 30 MPa to obtain the foamed material.

[0080] S4 The foaming material from step S3 is subjected to a second high-temperature vulcanization in an oven at a temperature of 170°C for 20 minutes to obtain phase change foam.

[0081] Example 10

[0082] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0083] S1 mixes 80 / 20 parts of styrene-butadiene rubber / butadiene rubber and 100 parts of solid paraffin wax with a melting point of 60°C using a melt mixing method at a mixing temperature of 80°C and a rotor speed of 60 rpm; then reduces the rotor speed to 30 rpm, adds 10 parts of silica aerogel, and adjusts the rotor speed back to 60 rpm, mixing for 2 minutes; then adds 1.5 parts of sulfur, 1 part of N-tert-butyl-2-benzothiazole sulfenamide (TBBS), 1.5 parts of stearic acid, 3 parts of zinc oxide, 3 parts of antioxidant H, 1 part of N-cyclohexylthiophthalimide, and 1 part of thermochromic powder at 60°C (the thermochromic powder is commercially available and purchased from Qingdao Chongyu), and mixes for 4 minutes to obtain the compound;

[0084] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then subjected to high-temperature molding on a flat vulcanizing machine. The vulcanization temperature is set to 160°C, and the molding time includes 4 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0085] S3 The molding material from step S2 is subjected to supercritical foaming in a foaming kettle. The foaming gas is 4MPa CO2 + 20MPa N2, the foaming time is 2 hours, the foaming temperature is 100℃, and the gas pressure is 24MPa to obtain the foamed material.

[0086] S4 involves a second high-temperature vulcanization of the foaming material from step S3 in an oven at a temperature of 180°C for 15 minutes to obtain phase change foam.

[0087] Example 11

[0088] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0089] S1 mixes 70 / 30 parts butyl rubber / natural rubber and 100 parts solid paraffin wax with a melting point of 66℃ using a melt mixing method at a mixing temperature of 80℃ and a rotor speed of 60 rpm; then reduces the rotor speed to 30 rpm, adds 10 parts silica aerogel, and adjusts the rotor speed back to 60 rpm, mixing for 2 minutes; then adds 2 parts sulfur, 2 parts accelerator DM, 2 parts stearic acid, 4 parts zinc oxide, 1.5 parts antioxidant RD, 1 part N-cyclohexylthiophthalimide, and 1 part thermochromic powder with a temperature of 66℃ (the thermochromic powder is commercially available and purchased from Qingdao Chongyu), and mixes for 4 minutes to obtain the compound;

[0090] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then subjected to high-temperature molding on a flat vulcanizing machine. The vulcanization temperature is set to 160°C, and the molding time includes 4 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0091] S3 The molding material from step S2 is foamed in a foaming kettle using supercritical CO2 for 2 hours, at a foaming temperature of 100°C and a gas pressure of 17MPa to obtain the foamed material.

[0092] S4 The foaming material from step S3 is subjected to a second high-temperature vulcanization in an oven at a temperature of 170°C for 20 minutes to obtain phase change foam.

[0093] Example 12

[0094] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0095] S1 mixes 100 parts of SEBS and 150 parts of solid paraffin wax with a melting point of 70℃ using a melt mixing method at a mixing temperature of 100℃ and a rotor speed of 60 rpm; then reduces the rotor speed to 30 rpm, adds 10 parts of silica aerogel, and adjusts the rotor speed back to 60 rpm, mixing for 2 minutes; then adds 1 part of dicumyl peroxide (DCP), 1 part of triallyl isocyanurate (TAIC), 1 part of stearic acid, 3 parts of zinc oxide, 2 parts of antioxidant OD, 0.5 parts of N-cyclohexylthiophthalimide, and 1 part of thermochromic powder at 70℃ (the thermochromic powder is commercially available and purchased from Qingdao Chongyu), and mixes for 4 minutes to obtain the compound.

[0096] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 160°C, and the molding time includes 8 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0097] S3 The molding material from step S2 is foamed in a foaming kettle with supercritical N2 for 2 hours, at a foaming temperature of 80°C and a gas pressure of 25MPa to obtain the foamed material.

[0098] S4 involves a second high-temperature vulcanization of the foaming material from step S3 in an oven at a temperature of 200°C for 10 minutes to obtain phase change foam.

[0099] Example 13

[0100] Prepared using the same method as in Example 2, except that the nucleating agent is graphene, the mixing temperature is 80°C, and the vulcanization time is 20 minutes.

[0101] Example 14

[0102] Prepared using the same method as in Example 13, except that the nucleating agent is carbon black N330.

[0103] Example 15

[0104] Prepared using the same preparation method as in Example 13, except that the nucleating agent is nano-titanium dioxide.

[0105] Example 16

[0106] Prepared using the same method as in Example 13, except that the nucleating agent is calcium carbonate.

[0107] Example 17

[0108] Prepared using the same preparation method as in Example 13, except that the nucleating agent is fumed silica.

[0109] Example 18

[0110] Prepared using the same method as in Example 13, except that the nucleating agent is carbon nanotubes.

[0111] Implementation 19

[0112] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0113] S1 mixes 100 parts of ethylene propylene rubber and 50 parts of solid paraffin wax with a melting point of 48°C using a melt mixing method at a mixing temperature of 80°C and a rotor speed of 60 rpm. Then, the rotor speed is reduced to 30 rpm, 10 parts of silica aerogel are added, and the rotor speed is adjusted back to 60 rpm and mixed for 2 minutes. Next, 1 part of di-tert-butylperoxyisopropylbenzene, 1 part of triallyl isocyanurate, 1 part of stearic acid, 3 parts of zinc oxide, 1 part of antioxidant OD, 0.5 parts of N-cyclohexylthiophthalimide, and 0.5 parts of thermochromic powder at 40°C (thermochromic powder is commercially available and purchased from Qingdao Chongyu) are added and mixed for 4 minutes to obtain the compound.

[0114] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 140°C, and the molding time includes 5 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0115] S3 The molding material from step S2 is foamed in a foaming kettle using supercritical CO2 for 1 hour, at a foaming temperature of 60°C and a gas pressure of 15MPa to obtain the foamed material.

[0116] S4 The foaming material from step S3 is subjected to a second high-temperature vulcanization in an oven at a temperature of 170°C for 20 minutes to obtain phase change foam.

[0117] Implementation 20

[0118] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0119] S1 mixes 100 parts of ethylene propylene rubber and 200 parts of solid paraffin wax with a melting point of 70°C using a melt mixing method at a mixing temperature of 100°C and a rotor speed of 60 rpm. Then, the rotor speed is reduced to 30 rpm, 50 parts of silica aerogel are added, and the rotor speed is adjusted back to 60 rpm for 2 minutes. Next, 3 parts of di-tert-butylperoxyisopropylbenzene, 2 parts of triallyl isocyanurate, 2 parts of stearic acid, 5 parts of zinc oxide, 3 parts of antioxidant OD, 1 part of N-cyclohexylthiophthalimide, and 2 parts of thermochromic powder with a melting point of 70°C (thermochromic powder is commercially available and purchased from Qingdao Chongyu) are added, and the mixture is mixed for 4 minutes to obtain the compound.

[0120] S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 170°C, and the molding time includes 10 minutes of hot pressing and 4 minutes of cold pressing to obtain the molded rubber.

[0121] S3 The molding material from step S2 is foamed in a foaming kettle using supercritical CO2 for 3 hours, at a foaming temperature of 100°C and a gas pressure of 30MPa to obtain the foamed material.

[0122] S4 involves a second high-temperature vulcanization of the foaming material from step S3 in an oven at a temperature of 200°C for 30 minutes to obtain phase change foam.

[0123] Comparative Example 1

[0124] Prepared using the same method as in Example 1, except that no solid paraffin is added and the hot pressing time is 4 minutes.

[0125] Comparative Example 2

[0126] Prepared using the same method as in Example 3, except that no carbon dioxide aerogel is added.

[0127] Comparative Example 3

[0128] A method for preparing a lightweight, flexible, shape-memory, isothermal phase change foam includes the following steps:

[0129] S1 Set the temperature of the internal mixer to 80℃. After the temperature stabilizes, add 100 parts of EPDM, 150 parts of PW with a melting point of 56℃ in sequence. After mixing evenly, add the vulcanization system (1 part of stearic acid (SA), 5 parts of zinc oxide (ZnO), 2 parts of bis-tert-butyl peroxyisopropylbenzene (BIPB), 1 part of triallyl isocyanurate (TAIC), 1 part of thermochromic powder, 1 part of anti-scorching agent N-cyclohexylthiophthalimide (PVI or CTP), 15 parts of azodicarbonamide (AC), and 1 part of antioxidant OD to obtain the compound rubber.

[0130] S2. The compound obtained in step S1 is put into a two-roll mill and pressed into a thin sheet by the two-roll mill. After cutting, a pressed test piece is obtained.

[0131] S3: Place the pressed sample obtained in step S2 into a mold and press it for 10 minutes using a flat vulcanizing machine at a temperature of 160℃ and a pressure of 10MPa to obtain a chemically foamed sample.

[0132] S4: Place the foamed sample obtained in step S3 into an oven and vulcanize it at 170°C for 20 minutes to obtain EPDM / PW phase change foam.

[0133] Experimental test:

[0134] 1. Shape memory test

[0135] Specific experimental procedure: (I) Heat the sample in an oven at 90℃; (II) Maintain the temperature for 30 min to promote complete melting of solid paraffin; (III) Bend the sample at 90 degrees; (IV) Cool to room temperature under constant external force; (V) Remove the external force and record the angle. (VI) Allow the solid paraffin to solidify at room temperature for 2 hours, then reheat at 90°C to promote shape recovery and record the angles. .

[0136] Shape fixation rate: SF (%) = [(90-α) / 90] × 100

[0137] Shape recovery rate: SF (%) = (β / 90) × 100

[0138] 2. Solid paraffin leakage test:

[0139] The example and comparative samples were placed on white paper and kept in an oven at 90°C for 72 hours. Every 2 hours, the samples were removed, their mass was measured on an analytical balance, their density was measured on a hydrometer (GT-XB320M), and any residues on the white paper were observed.

[0140] Table 1 Mechanical Performance Tests

[0141]

[0142] The data and scanning electron microscope images above show that with the increase of silica aerogel content, the density, hardness, tensile strength, and tear strength of the phase change foam are improved, while the thermal conductivity decreases and the average cell size becomes smaller, thereby improving the foam's thermal insulation, mechanical properties, and structural properties. These improvements indicate that by adjusting the amount of silica aerogel added, the performance of phase change foam can be effectively adjusted to meet different application requirements.

[0143] Table 2 Mechanical Performance Tests

[0144]

[0145] From the above comparative examples and embodiments, Figure 20-25 It can be seen that the type of nucleating agent has a significant impact on the physical properties of phase change foam, especially in improving tear strength and adjusting tensile strength. Although the changes in density and hardness are not significant, the nucleating agent has a significant effect on the microstructure and heat transfer properties of the material. Selecting an appropriate nucleating agent and optimizing its dosage is crucial for achieving specific material performance goals. These findings highlight the potential of materials science in optimizing the macroscopic properties of materials through microstructure regulation.

[0146] Table 3. Effects of different amounts of solid paraffin on shape memory

[0147]

[0148] As can be seen from the table, the amount of solid paraffin added has a significant impact on the shape memory function of the phase change foam material. Comparative Example 1, without the addition of solid paraffin, exhibits the lowest shape retention and shape recovery rates, indicating that it has almost no shape memory function. With the increase of the solid paraffin content, the shape memory function gradually improves, with Examples 2 and 3 achieving the best shape memory performance—100% shape retention and recovery rates—after adding a sufficient proportion of solid paraffin. These results clearly demonstrate the importance of the solid paraffin content in improving the shape memory performance of phase change foam materials.

[0149] Figure 17-19 The image shows a leakage test of solid paraffin. During the test, the mass and density of the phase change foam in Example 2 remained unchanged, while the volume of the phase change foam in Comparative Example 3 visibly shrank, and obvious solid paraffin residue was found on the white paper. Figure 1 It can be seen that the EPDM / PW phase change foam with AC as the foaming agent has a yellowish surface, cracks and bulges. The SEM image shows that the sample has an irregular cell structure, with perforations and collapses.

[0150] As can be seen from the SEM images of Examples 2, 3 and Examples 9-12, a fine bubble structure can be obtained by using the encapsulation technology of this scheme with different encapsulation materials. This achieves the goal of maintaining a low density and uniform pore structure while filling a large amount of PCM phase change material.

[0151] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lightweight, flexible, shape-memory, isothermal phase-change foam, characterized in that, The thermostatic phase change foam is prepared from the following components in parts by weight: 100 parts encapsulation material, 50-200 parts phase change material, 10-50 parts nucleating agent, 1-3 parts vulcanizing agent, 1-2 parts co-vulcanizing agent, 1-2 parts activator, 3-5 parts zinc oxide, 1-3 parts antioxidant, 0.5-1 part anti-scorching agent, and 0.5-2 parts thermochromic powder. The encapsulation material is one or more of the following: natural rubber, styrene-butadiene rubber, cis-butadiene rubber, ethylene-propylene rubber, butyl rubber, and SEBS. The isothermal phase change foam is prepared by supercritical foaming.

2. The phase change foam according to claim 1, characterized in that, The phase change material is solid paraffin.

3. The phase change foam according to claim 2, characterized in that, The melting point of the solid paraffin is 48-70℃.

4. The phase change foam according to claim 1, characterized in that, The nucleating agent is one of the following: silica aerogel, fumed silica, carbon black, calcium carbonate, nano-titanium dioxide, carbon nanotubes, and graphene.

5. The phase change foam according to claim 1, characterized in that, The vulcanizing agent is any one of bis-tert-butylperoxyisopropylbenzene, dicumyl peroxide, benzoyl peroxide, bis(2,5-diphenyl)propane, and sulfur; the co-vulcanizing agent is any one of triallyl isocyanurate, N,N'-m-phenylenebismaleimide, trialkylmethylpropane methacrylate, and triallyl cyanurate; the activator is stearic acid; the anti-scorching agent is any one of N-cyclohexylthiophthalimide, salicylic acid, phthalic anhydride, and nitroso compounds; the antioxidant is any one of antioxidant RD, antioxidant OD, and antioxidant H; and the thermochromic powder is available in temperatures ranging from 40 to 70°C.

6. A method for preparing phase change foam according to any one of claims 1-5, comprising the following steps: S1 mixes the encapsulation material and phase change material using a melt mixing method. After mixing, a nucleating agent is added, and after mixing, a vulcanizing agent, a vulcanizing aid, an activator, zinc oxide, an antioxidant, an anti-scorching agent, and a thermochromic powder are added and mixed evenly to obtain a compounded rubber. S2. The compounded rubber from step S1 is left to stand for 24 hours, and then high-temperature molding is performed on a flat vulcanizing machine. The vulcanization temperature is set to 140-170℃, and the molding time includes hot pressing and cold pressing to obtain the molded rubber. S3 The molding material from step S2 is subjected to supercritical foaming in a foaming kettle. The foaming gas is carbon dioxide, nitrogen, or a mixture of both. The foaming time is 1-3 hours and the gas pressure is 15-30 MPa to obtain the foamed material. S4 involves a second high-temperature vulcanization of the foaming material from step S3 in an oven at a temperature of 170-200℃ to obtain phase change foam.

7. The preparation method according to claim 6, characterized in that, The mixing temperature in step S1 is 80-100℃; the hot pressing time in step S2 is 4-10 minutes.

8. The preparation method according to claim 6, characterized in that, The foaming temperature in step S3 is 60-100℃.

9. The preparation method according to claim 6, characterized in that, The vulcanization time in step S4 is 20-30 minutes.

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