A dynamic cross-linking wide-temperature-range environment-friendly damping composite material and a preparation method thereof

Abstract

This invention discloses a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material and its preparation method, belonging to the technical field of damping composite materials. The key technical point is that the damping composite material comprises the following raw materials in parts by weight: 50-80 parts butyl rubber, 20-50 parts polymethyl methacrylate, 10-40 parts hindered phenol, 3-8 parts disulfide bond extender, 5-15 parts phenolic resin vulcanizing agent, 10-20 parts modified mica powder, 5-20 parts plasticizer, and 3-5 parts zinc oxide. The weight ratio of butyl rubber to polymethyl methacrylate is (5-8):(2-5). A blend system of butyl rubber and polymethyl methacrylate is used. By adjusting the amount of hindered phenol and introducing a disulfide bond extender, the microphase separation structure is optimized to form a bicontinuous phase, allowing the damping peaks to superimpose and merge, thus widening the damping temperature range to -50~105℃, covering the entire operating condition from cold start to high temperature, while also effectively reducing the migration and precipitation of hindered phenol.

Description

Technical Field

[0001] This invention relates to the field of damping composite materials technology, and in particular to a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material and its preparation method. Background Technology

[0002] With the rapid development of modern industrial technology, the demand for vibration reduction and noise reduction materials is increasing in fields such as aerospace, rail transportation, shipbuilding, precision instruments, and national defense equipment. Damping composite materials, as viscoelastic materials capable of converting mechanical vibration energy into heat energy for dissipation, have become important materials for suppressing structural vibration and noise radiation. Among various damping composite materials, rubber-based viscoelastic damping composite materials are widely used in engineering vibration reduction due to their excellent energy dissipation capacity and good processability.

[0003] The damping performance of rubber-damped composites primarily stems from the dynamic mechanical relaxation behavior of polymer segments in the glass transition region. Near the glass transition temperature (Tg), polymer molecular segments gain sufficient degrees of freedom, resulting in significant hysteresis loss under external forces, manifested as a peak in the loss factor (tanδ). However, this high-damping range typically covers only a narrow temperature range (generally around 20–30 °C), and the damping performance rapidly diminishes in the low-temperature and high-temperature regions far from Tg. This characteristic severely limits the engineering applicability of traditional rubber-damped composites under variable-temperature conditions.

[0004] Butyl rubber (IIR), due to the large number of side methyl groups in its molecular chain and the significant internal rotational steric hindrance that hinders chain segment movement, exhibits excellent damping performance over a wide temperature and frequency range, making it one of the ideal matrices for preparing high-performance damping composites. However, the effective damping temperature range of pure IIR is still mainly concentrated in the low-temperature region, with significantly insufficient damping performance in the medium- and high-temperature ranges. Furthermore, the low double bond content and lack of polar groups in the IIR molecular chain result in poor compatibility with functionally modified mica powder, further limiting the potential for improving damping performance.

[0005] To further improve damping performance, hindered phenol / polymer hybrid damping systems have become a research hotspot in recent years. Hindered phenols (such as AO-80 and AO-60) are sterically hindered small organic molecules containing multiple phenolic hydroxyl groups and tert-butyl side groups, capable of forming reversible intermolecular hydrogen bond networks with polar polymer matrices. Under external forces, the breaking and recombination of hydrogen bonds can effectively dissipate energy, thereby significantly improving the damping performance of the material. However, hindered phenol / polymer hybrid systems face serious stability problems in practical applications. Studies have shown that during storage or long-term use, hindered phenol molecules undergo irregular migration in the polymer matrix, gradually aggregating and crystallizing to form large-sized crystalline aggregates. This phase separation process disrupts the original hydrogen bond network structure in the system, leading to a continuous decline in damping performance over time. Especially at high temperatures, the movement of molecular chain segments intensifies, further accelerating the migration and aggregation rates of hindered phenols, resulting in a more significant decline in damping performance and severely affecting the long-term reliability of the material. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material and its preparation method. The material employs a blend of butyl rubber and polymethyl methacrylate. By adjusting the amount of hindered phenol and introducing a disulfide bond extender, the microphase separation structure is optimized to form a bicontinuous phase, allowing the damping peaks to superimpose and merge. This broadens the damping temperature range to -50~105℃, covering the entire operating condition from cold start to high temperature, while also effectively reducing the migration and precipitation of hindered phenol.

[0007] The first aspect of this invention is to provide a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material, which adopts the following technical solution:

[0008] A dynamic cross-linked wide-temperature-range environmentally friendly damping composite material comprises the following raw materials in parts by weight: 50-80 parts butyl rubber, 20-50 parts polymethyl methacrylate, 10-40 parts hindered phenol, 3-8 parts disulfide bond extender, 5-15 parts phenolic resin vulcanizing agent, 10-20 parts modified mica powder, 5-20 parts plasticizer, and 3-5 parts zinc oxide.

[0009] The weight ratio of butyl rubber to polymethyl methacrylate is (5-8):(2-5).

[0010] By adopting the above technical solution, non-polar butyl rubber and polymethyl methacrylate containing strong polar ester groups are compounded in an optimized ratio of (5-8):(2-5). Due to the thermodynamic incompatibility of the two, the system forms a nanoscale bicontinuous microphase separation structure. This structure causes the glass transition damping peak of the butyl rubber phase in the low temperature region (about -60℃ to -20℃) to partially overlap and merge with the secondary relaxation damping peak of the polymethyl methacrylate phase in the medium and high temperature region (about 20℃ to 105℃). This lays the foundation for expanding the effective damping temperature range of the composite material from the narrow low temperature region of pure butyl rubber to -50℃ to 105℃.

[0011] Based on the bicontinuous phase structure, multiple phenolic hydroxyl groups of the hindered phenol act as proton donors, forming a broad network of reversible intermolecular hydrogen bonds with the ester carbonyl groups of the polymethyl methacrylate segment and a small number of unsaturated bonds of the butyl rubber segment. This hydrogen bond network, acting as a dynamic sacrificial bond, undergoes a break-recombination process under external forces, effectively dissipating energy. It significantly improves the loss factor (tanδ≥0.35) in the mid-to-high temperature range (80℃~105℃), filling the damping trough that might occur in the bicontinuous phase structure at this temperature, and ensuring the continuity and stability of damping performance over a wide temperature range.

[0012] The synergistic effect of disulfide bond extenders and phenolic resin vulcanizing agents constructs a reversible dynamic crosslinking network at the interface between butyl rubber and polymethyl methacrylate and within the matrix. Within the 80-150℃ temperature range, disulfide bonds can break and recombine. This disulfide bond breakage-recombination process, along with the breakage-recombination of hindered phenolic hydrogen bonds and interfacial friction from modified mica powder, constitutes multiple energy dissipation pathways over a wide temperature range, ensuring that damping performance does not decrease in the high-temperature region. The sulfur free radicals generated by disulfide bond breakage effectively capture and fix free hindered phenolic molecules, irreversibly anchoring them to the dynamic crosslinking network backbone through the formation of thioether bonds. This mechanism completely inhibits the migration, aggregation, and crystallization of hindered phenols at the molecular level, reducing the hindered phenol migration rate to below 1.8%, ensuring that the high-temperature damping retention rate of the composite material exceeds 90% after 1500 hours of aging.

[0013] In a preferred embodiment, the butyl rubber is composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of (7-10):(0-3).

[0014] By adopting the above technical solution, while ensuring the above phase structure and hydrogen bond / dynamic cross-linking network, replacing part of the virgin butyl rubber with recycled butyl rubber has little impact on the overall damping performance and hindered phenol migration rate, but can significantly reduce costs, which is in line with the concept of environmental protection and recycling.

[0015] In a preferred embodiment, the hindered phenol is AO-80.

[0016] In a preferred embodiment, the modified mica powder is lignin-modified mica powder.

[0017] In a preferred embodiment, the lignin-modified mica powder is obtained by the following preparation method:

[0018] S1. Hydrolyze the silane coupling agent in a mixed solvent of ethanol and water to obtain a silane hydrolysate;

[0019] S2. Add lignin and mica powder to anhydrous ethanol and stir to disperse evenly;

[0020] S3. Heat the system temperature to 75-85℃, add silane hydrolysate dropwise, react for 2 hours after the addition is complete, then filter, wash and dry to obtain lignin-modified mica powder.

[0021] By adopting the above technical solution, this invention uses lignin-modified mica powder with silane coupling agents as functional modified mica powder. On the one hand, during the dynamic deformation of the matrix, the lamellar microstructure of mica powder generates strong interfacial sliding friction between lamellars and between lamellars and polymer chains, irreversibly converting mechanical vibration energy into heat energy. On the other hand, the lignin macromolecules are rich in phenolic hydroxyl groups and aromatic ring structures, which can participate in the construction of hydrogen bond networks as auxiliary damping components, and can also be chemically anchored to the surface of mica powder under the bridging effect of silane coupling agents. This organic-inorganic hybrid interface layer significantly improves the compatibility and interfacial bonding strength between the modified mica powder and the bicontinuous phase matrix, enabling stress to be efficiently transferred from the matrix to the interface of the modified mica powder lamellars, greatly enhancing the internal friction effect of the composite system. This effect is particularly prominent at high temperatures—when the internal friction of the matrix molecular chains decreases due to increased thermal motion, the interfacial friction between the modified mica powder networks becomes a key compensation mechanism for maintaining high-temperature damping performance.

[0022] In a preferred embodiment, the amount of the silane coupling agent is 2.5-3.5% of the total weight of lignin and mica powder, and the weight ratio of lignin to mica powder is 1:5.

[0023] In a preferred embodiment, the plasticizer is a naphthenic oil.

[0024] A second aspect of the present invention is to provide a method for preparing a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material, comprising the following steps:

[0025] S1. Mix butyl rubber and polymethyl methacrylate at 155-165℃ for 10-15 minutes.

[0026] S2. Add hindered phenol, plasticizer and modified mica powder to step S1, and mix at 110-120℃ for 10-15 minutes.

[0027] S3. When cooled to 60℃, add disulfide bond extender, phenolic resin vulcanizing agent and zinc oxide and mix for 10-15 minutes. Then, mold to obtain damping composite material.

[0028] In a preferred embodiment, when the butyl rubber is composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of (7-10):(0-3), the preparation steps are as follows:

[0029] S1. Mix virgin butyl rubber and polymethyl methacrylate at 155-165℃ for 10-15 minutes.

[0030] S2. Add hindered phenol, plasticizer, modified mica powder and recycled butyl rubber to step S1, and mix at 110-120℃ for 10-15 minutes.

[0031] S3. When cooled to 60℃, add disulfide bond extender, phenolic resin vulcanizing agent and zinc oxide and mix for 10-15 minutes. Then, mold to obtain damping composite material.

[0032] In summary, the present invention has the following beneficial effects: By optimizing the ratio of butyl rubber / polymethyl methacrylate, the amount of hindered phenol added, the disulfide bond extender, and the combination of lignin-modified mica powder, the present invention solves the problems of low energy dissipation efficiency and high-temperature migration and precipitation of hindered phenol in traditional damping composite materials in the extreme temperature range of -50℃ to 105℃. The resulting damping composite material is suitable for harsh scenarios such as vibration damping pads for drive motors of new energy vehicles (operating temperature -40~120℃) and vibration dampers for high-speed rail tracks (-50~100℃). Detailed Implementation

[0033] The present invention will be further described in detail below with reference to embodiments. All details not specifically stated herein are based on conventional conditions or conditions recommended by the manufacturer. All reagents and instruments, unless otherwise stated below, are commercially available conventional reagent products.

[0034] Preparation Example 1

[0035] The preparation method of lignin-modified mica powder includes the following steps:

[0036] S1. Add KH-550 to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 9:1), adjust the pH to between 4 and 5, and stir to hydrolyze to obtain a silane hydrolysate with a concentration of 5 wt%. The amount of KH-550 added is 3% of the total weight of lignin and mica powder.

[0037] S2. Add lignin and mica powder to anhydrous ethanol at a weight ratio of 1:5 and stir to disperse into a mixture with a concentration of 60%.

[0038] S3. Heat the mixture system to 75°C, add silane hydrolysate dropwise, react for 2 hours after the addition is complete, then filter, wash and dry to obtain lignin-modified mica powder.

[0039] Preparation Example 2

[0040] The preparation method of lignin-modified mica powder includes the following steps:

[0041] S1. Add KH-550 to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 9:1), adjust the pH to between 4 and 5, and stir to hydrolyze to obtain a 5wt% silane hydrolysate; the amount of KH-550 added is 2.5% of the total weight of lignin and mica powder.

[0042] S2. Add lignin and mica powder to anhydrous ethanol at a weight ratio of 1:5 and stir to disperse into a mixture with a concentration of 60%.

[0043] S3. Heat the mixture system to 80℃, add silane hydrolysate dropwise, react for 2 hours after the addition is complete, then filter, wash and dry to obtain lignin-modified mica powder.

[0044] Preparation Example 3

[0045] The preparation method of lignin-modified mica powder includes the following steps:

[0046] S1. Add KH-550 to a mixed solvent of ethanol and water (volume ratio of ethanol to water is 9:1), adjust the pH to between 4 and 5, and stir to hydrolyze to obtain a 5wt% silane hydrolysate; the amount of KH-550 added is 3.5% of the total weight of lignin and mica powder.

[0047] S2. Add lignin and mica powder to anhydrous ethanol at a weight ratio of 1:5 and stir to disperse into a mixture with a concentration of 60%.

[0048] S3. Heat the mixture system to 85℃, add silane hydrolysate dropwise, react for 2 hours after the addition is complete, then filter, wash and dry to obtain lignin-modified mica powder.

[0049] Example 1

[0050] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 8 kg of virgin butyl rubber, 2 kg of polymethyl methacrylate (relative molecular weight of 10000-125000 g / mol, Tg of about 120℃, the same polymethyl methacrylate is used in the following examples), 2 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 2011 kg of phenolic resin vulcanizing agent, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0051] The preparation includes the following steps:

[0052] S1. Mix virgin butyl rubber and polymethyl methacrylate at 160±5℃ for 10 min;

[0053] S2. Add hindered phenol AO-80, naphthenic oil and lignin-modified mica powder to step S1, and mix at 115±5℃ for 15 min.

[0054] S3. When cooled to 60℃, add disulfide bond extender DS, phenolic resin vulcanizing agent 201, and zinc oxide and mix for 10 min. Then, mold for 15 min at a pressure of 10 MPa to obtain a damping composite material.

[0055] Example 2

[0056] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 7 kg of virgin butyl rubber, 3 kg of polymethyl methacrylate, 2 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 1 kg of phenolic resin vulcanizing agent 201, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0057] The preparation method is the same as in Example 1.

[0058] Example 3

[0059] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 6 kg of virgin butyl rubber, 4 kg of polymethyl methacrylate, 2 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 1 kg of phenolic resin vulcanizing agent 201, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0060] The preparation method is the same as in Example 1.

[0061] Example 4

[0062] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts are as follows: 5 kg of virgin butyl rubber, 5 kg of polymethyl methacrylate, 2 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 1 kg of phenolic resin vulcanizing agent 201, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0063] The preparation method is the same as in Example 1.

[0064] Example 5

[0065] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 5 kg of virgin butyl rubber, 5 kg of polymethyl methacrylate, 1 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 1 kg of phenolic resin vulcanizing agent 201, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0066] The preparation method is the same as in Example 1.

[0067] Example 6

[0068] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 5 kg of virgin butyl rubber, 5 kg of polymethyl methacrylate, 4 kg of hindered phenol AO-80, 0.5 kg of disulfide bond extender DS, 1 kg of phenolic resin vulcanizing agent 201, 1.5 kg of lignin-modified mica powder obtained in Preparation Example 1, 1 kg of naphthenic oil, and 0.4 kg of zinc oxide;

[0069] The preparation method is the same as in Example 1.

[0070] Example 7

[0071] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 5 kg of virgin butyl rubber, 5 kg of polymethyl methacrylate, 2 kg of hindered phenol AO-80, 0.3 kg of disulfide bond extender DS, 0.5 kg of phenolic resin vulcanizing agent 201, 1 kg of lignin-modified mica powder obtained in Preparation Example 2, 0.5 kg of naphthenic oil, and 0.3 kg of zinc oxide;

[0072] The preparation method is the same as in Example 1.

[0073] Example 8

[0074] A dynamic crosslinked wide-temperature-range environmentally friendly damping composite material, the raw material amounts of which are as follows: 5 kg of virgin butyl rubber, 5 kg of polymethyl methacrylate, 2 kg of hindered phenol AO-80, 0.8 kg of disulfide bond extender DS, 1.5 kg of phenolic resin vulcanizing agent 201, 2 kg of lignin-modified mica powder obtained in Preparation Example 3, 2 kg of naphthenic oil, and 0.5 kg of zinc oxide;

[0075] The preparation method is the same as in Example 1.

[0076] Example 9

[0077] A dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material, differing from Example 4 in that the total amount of butyl rubber is 5 kg, composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of 7:3, and its preparation method is as follows:

[0078] The recycled butyl rubber was desulfurized at 120°C for 30 minutes (under nitrogen protection), and after impurities were removed by passing it through a 200-mesh sieve, it was added in step S2. The amount of other raw materials and the steps were the same as in Example 4.

[0079] Example 10

[0080] A dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material, differing from Example 4 in that the total amount of butyl rubber is 5 kg, composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of 9:1, and its preparation method is as follows:

[0081] The recycled butyl rubber was desulfurized at 120°C for 30 minutes (under nitrogen protection), and after impurities were removed by passing it through a 200-mesh sieve, it was added in step S2. The amount of other raw materials and the steps were the same as in Example 4.

[0082] Comparative Example 1

[0083] An environmentally friendly damping composite material, which differs from Example 4 in that it does not contain polymethyl methacrylate in the raw materials, but is otherwise the same as Example 4.

[0084] Comparative Example 2

[0085] An environmentally friendly damping composite material differs from Example 4 in that an equal amount of styrene-acrylonitrile copolymer (average weight-average molecular weight of 185,000 and acrylonitrile content of 30 wt%) is used instead of polymethyl methacrylate, while all other aspects are the same as in Example 4.

[0086] Comparative Example 3

[0087] An environmentally friendly damping composite material differs from Example 4 in that an equal amount of dimethylthiotoluene diamine is used instead of the disulfide bond extender DS; otherwise, they are the same as in Example 4.

[0088] Comparative Example 4

[0089] An environmentally friendly damping composite material differs from Example 4 in that the amount of hindered phenol AO-80 added is 0.8 kg, while all other aspects are the same as in Example 4.

[0090] Comparative Example 5

[0091] An environmentally friendly damping composite material differs from Example 4 in that unmodified mica powder is used instead of lignin-modified mica powder; otherwise, it is the same as Example 4.

[0092] Comparative Example 6

[0093] An environmentally friendly damping composite material differs from Example 4 in that the amount of virgin butyl rubber used is 4 kg and the amount of polymethyl methacrylate used is 6 kg, while all other aspects are the same as in Example 4.

[0094] Comparative Example 7

[0095] An environmentally friendly damping composite material differs from Example 4 in that the amount of virgin butyl rubber used is 9 kg and the amount of polymethyl methacrylate used is 1 kg, while all other aspects are the same as in Example 4.

[0096] Performance testing

[0097] The damping performance, mobility, and tensile properties of the damping composite materials obtained in the above embodiments and comparative examples were tested, and the test results are shown in the table below.

[0098] Damping performance includes tanδ (loss factor) and damping temperature range. The testing standard is ASTM D4065. The testing method is as follows: using a Dynamic Thermomechanical Analyzer (DMA), in tensile or shear mode, a temperature scan is performed at a specific frequency (10 Hz), strain amplitude (e.g., 0.1%), and heating rate (e.g., 3 °C / min). The effective damping temperature range is defined as the temperature range where tanδ ≥ 0.25.

[0099] High-temperature damping retention rate: The samples were placed in a 130℃ hot air aging chamber for 1500 hours, according to ASTM D573. After aging, they were removed and conditioned in a standard environment for 24 hours. According to ASTM D4065, a dynamic thermomechanical analyzer was used to test the loss factor of the samples before and after aging in the range of -80℃ to 150℃ under tensile mode, frequency 10Hz, strain 0.1%, and heating rate 3℃ / min. The tanδ value at 80℃ was used, and the high-temperature damping retention rate was calculated using the formula (tanδ after aging / tanδ before aging) × 100%.

[0100] Hindered phenol migration determination: Performed according to GB 31604.1-2015 and GB / T 23296.1-2009 (or specific method standards for phenolic compounds). A certain mass of sample is placed in a glass dish with a specified surface area, and a sufficient amount of the selected simulant (e.g., distilled water) is added. The mixture is migrated at 100°C for 2 hours. After migration, the simulant is collected, and the content of the hindered phenol AO-80 is determined using high-performance liquid chromatography (HPLC), and the migration ratio is calculated.

[0101] Mechanical properties (tensile strength) are tested according to ASTM D412 standard. The test method is to use a universal testing machine to stretch a standard dumbbell-shaped specimen until it breaks at a specific speed (500 mm / min).

[0102] Table 1. Performance Test Results of Damping Composite Materials

[0103] project 80℃tanδ Damping temperature range / ℃ High-temperature damping retention rate % migration rate % Tensile strength (MPa) Example 1 0.26 ﹣58~88 91 2.2 19.0 Example 2 0.28 ﹣55~85 92 2.0 18.6 Example 3 0.32 ﹣52~98 94 1.9 17.2 Example 4 0.35 ﹣50~105 95 1.7 16.5 Example 5 0.35 ﹣50~100 88 3.5 16.8 Example 6 0.32 ﹣55~100 80 8.5 14.5 Example 7 0.28 ﹣53~92 85 4.0 15.0 Example 8 0.34 ﹣51~103 93 1.7 18.0 Example 9 0.31 ﹣51~96 93 2.1 15.8 Example 10 0.30 ﹣48~102 94 1.9 16.3 Comparative Example 1 0.10 ﹣60~20 78 12.0 12.2 Comparative Example 2 0.22 ﹣54~75 82 6.5 15.5 Comparative Example 3 0.29 ﹣53~95 75 10.2 16.0 Comparative Example 4 0.20 ﹣52~82 80 5.0 15.2 Comparative Example 5 0.28 ﹣53~90 85 5.8 14.0 Comparative Example 6 0.25 ﹣45~108 82 4.5 13.5 Comparative Example 7 0.15 ﹣58~40 77 3.0 18.5

[0104] Based on the test data in Table 1:

[0105] In Examples 1-4, with the content of other raw materials remaining unchanged, as the amount of virgin butyl rubber added was gradually reduced and the amount of polymethyl methacrylate added was increased, the loss factor of the damping composite material increased with the amount of polymethyl methacrylate added, the damping temperature range widened, the high-temperature damping retention rate increased, and the hindered phenol migration rate decreased. It can be seen that as the proportion of polymethyl methacrylate added increases, the damping performance of the damping composite material is improved and the migration rate of hindered phenol decreases, but the tensile strength decreases accordingly. Therefore, when the weight ratio of virgin butyl rubber to polymethyl methacrylate is 5:5, the tensile performance of the damping composite material is guaranteed, and the damping performance of the damping composite material is also improved.

[0106] Examples 5-6 further refined the amount of hindered phenol added based on the virgin butyl rubber and polymethyl methacrylate (PMMA) weight ratio of 5:5 (Example 4). It can be seen that when the amount of hindered phenol added is 1 kg or 4 kg, the high-temperature damping retention rate is significantly lower than in Example 4. Simultaneously, the high amount of hindered phenol significantly increases its migration rate, which will lead to a continuous decline in damping performance over time. Conversely, the low amount of hindered phenol also results in an increased migration rate. This is because an appropriate amount of hindered phenol molecules is sufficient to form a relatively dense and continuous reversible hydrogen bond network in the PMMA phase and interfacial region. The molecules provide more "anchoring points" and react fully with the sulfur free radicals generated by the disulfide bond extender, becoming firmly bonded to the dynamic cross-linked network backbone. Therefore, the migration rate is effectively suppressed to a minimum. However, when the content of hindered phenol is insufficient, the hydrogen bond network may become sparse, making it difficult to form a continuous and effective energy dissipation network. More hindered phenol molecules may exist in an isolated and dispersed form, reducing the anchoring efficiency. The probability and efficiency of the bonding reaction between the disulfide bond extender and the hindered phenol decrease. Free hindered phenol molecules that are not anchored in time are more likely to migrate and aggregate during thermal processing or subsequent use. Therefore, when the amount of hindered phenol added is low, the proportion of unfixed molecules (i.e., the migration rate) is higher.

[0107] Compared with Example 4, when the amounts of virgin butyl rubber, polymethyl methacrylate, and hindered phenol remained unchanged, by changing the amounts of other components, the damping composite material obtained in Example 7 had a lower loss factor, a narrower damping temperature range, a lower high-temperature damping retention rate, and an increased hindered phenol migration rate. The various properties of the damping composite material obtained in Example 8 were basically similar to those of Example 4.

[0108] Compared with Example 4, when partially recycled butyl rubber replaces virgin butyl rubber, the damping performance of the damping composite material obtained in Examples 9-10 is basically close to that in Example 4. However, the tensile strength decreases with the increase of recycled butyl rubber content, but the preparation cost will be significantly reduced.

[0109] Compared with Example 4, when polymethyl methacrylate was not present in the raw materials, the damping performance and tensile strength of the damping composite material obtained in Comparative Example 1 were significantly reduced, while the hindered phenol migration rate was significantly increased, resulting in the damping performance continuously decaying over time.

[0110] Compared with Example 4, when an equal amount of styrene-acrylonitrile copolymer was used to replace polymethyl methacrylate, although the glass transition temperatures of styrene-acrylonitrile copolymer and polymethyl methacrylate were similar, the damping performance of the damping composite material obtained in Comparative Example 2 was significantly reduced compared with Example 4, while the hindered phenol migration rate was significantly increased, indicating that the damping performance would continue to decline over time.

[0111] Compared with Example 4, when an equal amount of dimethylthiotoluene diamine was used to replace the disulfide bond extender DS, the hindered phenol migration rate increased significantly. At the same time, the damping performance of the damping composite material was also reduced compared with Example 4. This further illustrates that the combination of the disulfide bond extender DS and other raw materials in this application not only inhibits the migration and precipitation of hindered phenol, but also improves the damping performance of the damping composite material.

[0112] Compared with Example 4, when the amount of hindered phenol added was lower, the damping temperature range narrowed, and the migration rate of hindered phenol also increased significantly. The reason for the increase in migration rate was the same as that in Example 5.

[0113] Compared with Example 4, when unmodified mica powder was used instead of lignin-modified mica powder, the damping performance and tensile strength of the damping composite material decreased, while the hindered phenol migration rate increased. This further illustrates that the combination of lignin-modified mica powder and other raw materials further improves the overall performance of the damping composite material.

[0114] Compared with Example 4, when the ratio of virgin butyl rubber to polymethyl methacrylate was not within the range of (5-8):(2-5), the migration rate of hindered phenol was significantly higher than that of Example 4, and the high-temperature damping retention rate was significantly lower than that of Example 4. It can be seen that its high-temperature damping performance was significantly reduced. In addition, when the amount of virgin butyl rubber added was small, the tensile strength of the damping composite material of Comparative Example 6 was significantly reduced, while when the amount of virgin butyl rubber added was too high, the damping performance of the damping composite material obtained in Comparative Example 7 was significantly reduced. Therefore, limiting the ratio of virgin butyl rubber to polymethyl methacrylate to the range of (5-8):(2-5) ensured the damping performance and tensile performance of the damping composite material.

[0115] The embodiments described herein are merely illustrative of preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material, characterized in that: The raw materials include the following parts by weight: 50-80 parts butyl rubber, 20-50 parts polymethyl methacrylate, 10-40 parts hindered phenol, 3-8 parts disulfide bond extender, 5-15 parts phenolic resin vulcanizing agent, 10-20 parts modified mica powder, 5-20 parts plasticizer, and 3-5 parts zinc oxide. The weight ratio of butyl rubber to polymethyl methacrylate is (5-8):(2-5).

2. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 1, characterized in that: The butyl rubber is composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of (7-10):(0-3).

3. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 1, characterized in that: The hindered phenol used is AO-80.

4. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 1, characterized in that: The modified mica powder is lignin-modified mica powder.

5. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 4, characterized in that: The lignin-modified mica powder is obtained by the following preparation method: S1. Hydrolyze the silane coupling agent in a mixed solvent of ethanol and water to obtain a silane hydrolysate; S2. Add lignin and mica powder to anhydrous ethanol and stir to disperse evenly; S3. Heat the system temperature to 75-85℃, add silane hydrolysate dropwise, react for 2 hours after the addition is complete, then filter, wash and dry to obtain lignin-modified mica powder.

6. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 5, characterized in that: The amount of the silane coupling agent is 2.5-3.5% of the total weight of lignin and mica powder, and the weight ratio of lignin to mica powder is 1:

5.

7. The dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 1, characterized in that: The plasticizer is a naphthenic oil.

8. A method for preparing a dynamically cross-linked, wide-temperature-range environmentally friendly damping composite material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix butyl rubber and polymethyl methacrylate at 155-165℃ for 10-15 minutes. S2. Add hindered phenol, plasticizer and modified mica powder to step S1, and mix at 110-120℃ for 10-15 minutes. S3. When cooled to 60℃, add disulfide bond extender, phenolic resin vulcanizing agent and zinc oxide and mix for 10-15 minutes. Then, mold to obtain damping composite material.

9. The method for preparing a dynamically cross-linked wide-temperature-range environmentally friendly damping composite material according to claim 8, characterized in that: When the butyl rubber is composed of virgin butyl rubber and recycled butyl rubber in a weight ratio of (7-10):(0-3), the preparation steps are as follows: S1. Mix virgin butyl rubber and polymethyl methacrylate at 155-165℃ for 10-15 minutes. S2. Add hindered phenol, plasticizer, modified mica powder and recycled butyl rubber to step S1, and mix at 110-120℃ for 10-15 minutes. S3. When cooled to 60℃, add disulfide bond extender, phenolic resin vulcanizing agent and zinc oxide and mix for 10-15 minutes. Then, mold to obtain damping composite material.