Fe-doped TiO2 modified silicone rubber as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of silicone rubber, and particularly relates to Fe-doped TiO2 modified silicone rubber as well as a preparation method and application thereof. According to the Fe-doped TiO2 modified silicone rubber provided by the invention, Fe-TiO2 nanoparticles are prepared by using a flame spray pyrolysis method, the silicone rubber is modified, the Fe-TiO2 nanoparticles can be uniformly dispersed in the silicone rubber, and through dual effects of maintaining completeness of a main chain of the silicone rubber and reducing an excessive cross-linking reaction between silicon chains and oxygen chains in a high-temperature environment, the silicon rubber can be effectively modified, so that the silicon rubber can be effectively modified, and the service life of the silicon rubber is prolonged. The thermal aging resistance of the silicone rubber is remarkably improved, and the technical problem that high-performance thermal aging resistant silicone rubber is lacked in the prior art is solved.

Description

Technical Field

[0001] The present application belongs to the technical field of silicone rubber, and in particular relates to a Fe-doped TiO2-modified silicone rubber and a preparation method and application thereof. Background Art

[0002] Silicone rubber is a polymer with a three-dimensional network structure composed of repeating siloxane chains. With its molecular skeleton composed of high-energy Si-O bonds, it has excellent high and low temperature resistance. It also has good electrical insulation, radiation resistance and biocompatibility. It is widely used in high-tech equipment, aerospace, defense industry, chemical raw materials, medical devices and other fields.

[0003] With the continuous advancement of science and technology, higher and higher requirements are placed on the performance of silicone rubber in the fields of aerospace, defense industry, etc. Silicone rubber is required to maintain stable performance in high temperature environments, and extremely high requirements are placed on the high temperature resistance of silicone rubber; however, ordinary silicone rubber will undergo thermal aging in high temperature environments, which is mainly manifested in two aspects: on the one hand, its polysiloxane main chain will break and rearrange to produce cyclic oligomers, resulting in shortening of the main chain and softening of the material; on the other hand, in a high temperature aerobic environment, the side groups on the silicon atoms will split to form free radicals, triggering excessive cross-linking reactions between silicon oxygen chains, making the material hardened and brittle, and shrinking and significantly losing quality; these thermal aging problems limit the application of silicone rubber in higher temperature environments, so improving the high temperature resistance of silicone rubber has become an important research direction in the field of materials.

[0004] At present, the most common, effective, low-cost and easy-to-implement method in the industry to improve the high-temperature resistance of silicone rubber is to add metal oxide heat-resistant additives such as CeO2, Fe2O3, TiO2, etc. to its compound. However, the heat resistance of silicone rubber modified with metal oxide heat-resistant additives such as TiO2 still has room for improvement, and there is currently a lack of high-performance heat-resistant aging silicone rubber. Summary of the invention

[0005] In view of this, the present application provides a Fe-doped TiO2-modified silicone rubber and a preparation method and application thereof, which are used to solve the technical problem of the lack of high-performance heat-resistant aging silicone rubber in the prior art.

[0006] In a first aspect, the present application provides a Fe-doped TiO2 modified silicone rubber, the raw materials of which include silicone rubber raw rubber, liquid vulcanizing agent, reinforcing filler, vinyl silicone oil and Fe-TiO2 nanoparticles.

[0007] Preferably, the particle size of the Fe-TiO2 nanoparticles is 10-40 nm.

[0008] Preferably, the content of Fe atoms in the Fe-TiO2 nanoparticles is 1-3%.

[0009] Preferably, the silicone rubber raw rubber is selected from at least one of methyl silicone rubber raw rubber, methyl vinyl silicone rubber raw rubber, methyl phenyl vinyl silicone rubber raw rubber, and fluorosilicone rubber raw rubber.

[0010] Preferably, the silicone rubber raw rubber is selected from peroxide-cured methyl vinyl silicone rubber raw rubber.

[0011] Preferably, the liquid curing agent is selected from at least one of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, methyl ethyl ketone peroxide, tert-butyl peroxybenzoate, and di-tert-butyl peroxide.

[0012] Preferably, the reinforcing filler is selected from at least one of silica, carbon black, and mica powder.

[0013] Preferably, the silica is selected from at least one of fumed silica, precipitated silica, microemulsion silica, and sol-gel silica.

[0014] Preferably, the vinyl silicone oil is selected from at least one of hydroxy vinyl silicone oil and methyl vinyl silicone oil.

[0015] Preferably, calculated by mass, the Fe-doped TiO2 modified silicone rubber raw material comprises 50-150 parts by mass of silicone rubber raw rubber, 0.1-0.2 parts by mass of liquid catalyst, 0.1-1 part by mass of reinforcing filler, 0.5-1 part by mass of vinyl silicone oil, and 1-3 parts by mass of Fe-TiO2 nanoparticles.

[0016] The second aspect of the present application provides a preparation method of Fe-doped TiO2 modified silicone rubber, which can prepare the Fe-doped TiO2 modified silicone rubber described in the first aspect. The preparation method includes the following steps:

[0017] The step of preparing a paste heat-resistant agent, preparing Fe-TiO2 nanoparticles by flame spray pyrolysis, and mixing the Fe-TiO2 nanoparticles and vinyl silicone oil uniformly to obtain a paste heat-resistant agent;

[0018] The step of preparing a paste curing agent, mixing the reinforcing filler and the liquid curing agent uniformly to obtain a paste curing agent;

[0019] The step of silicone rubber mixing, sequentially adding the paste heat-resistant agent and the paste curing agent into the silicone rubber raw rubber in an open mill for mixing to obtain the mixed silicone rubber;

[0020] The step of silicone rubber vulcanization, vulcanizing the mixed silicone rubber to obtain Fe-doped TiO2 modified silicone rubber.

[0021] Preferably, in the step of preparing the paste-like heat-resistant agent, the step of preparing Fe-TiO2 nanoparticles by flame spray pyrolysis includes:

[0022] Step S1: Dissolve a titanium source and an iron source in a solvent to obtain an iron-titanium precursor solution;

[0023] Step S2: Connect the iron-titanium precursor solution to the nozzle of the flame spray pyrolysis reactor;

[0024] Step S3: Start the flame spray pyrolysis reactor so that the iron-titanium precursor solution is atomized into micron-sized droplets and the micron-sized droplets are pyrolyzed to obtain Fe-TiO2 nanoparticles.

[0025] Preferably, in step S1, dissolving the titanium source and the iron source in the solvent specifically means: dissolving tetrabutyl titanate and ferrocene in absolute ethanol.

[0026] Preferably, in step S3, starting the flame spray pyrolysis reactor so that the iron-titanium precursor solution is atomized into micron-sized droplets and the micron-sized droplets are pyrolyzed to obtain Fe-TiO2 nanoparticles specifically means:

[0027] Step S31: Start the flame spray pyrolysis reactor so that the atomizing oxygen supplied by the supporting oxygen flow supply device and the iron-titanium precursor solution supplied by the supporting solution supply device flow to the nozzle and are atomized into micron-sized droplets with a particle size of 2-100 µm;

[0028] Step S32: The hydrogen / air output from the hydrogen and air supply pipes supporting the flame spray pyrolysis reactor is ignited into a flame at 1500-2500 °C, so that the micron-sized droplets with a particle size of 2-100 µm are pyrolyzed to obtain Fe-TiO2 nanoparticles.

[0029] Preferably, after step S3, there is also step S4 of collecting the Fe-TiO2 nanoparticles using the vacuum pump and filter cloth supporting the flame spray pyrolysis reactor.

[0030] The third aspect of the present application provides the application of the Fe-doped TiO2 modified silicone rubber described in the first aspect in the fields of aerospace or national defense industry.

[0031] Compared with the prior art, the Fe-doped TiO2 modified silicone rubber, preparation method and application provided by the present application at least include the following beneficial effects:

[0032] 1. In the Fe-doped TiO2 modified silicone rubber provided by the present application, Fe-TiO2 nanoparticles are used

[0033] Modification was carried out, and by utilizing the dual effects of Fe-TiO₂ nanoparticles of "maintaining the integrity of the silicone rubber main chain and reducing the excessive cross-linking reaction between silicon-oxygen chains" in a high-temperature environment, the heat aging performance of the silicone rubber was significantly improved.

[0034] 2. In the Fe-doped TiO₂ modified silicone rubber provided in this application, specific Fe-TiO₂ nanoparticles

[0035] and vinyl silicone oils such as hydroxy vinyl silicone oil are made into a paste-like heat-resistant agent, and specific reinforcing fillers such as fumed silica and a liquid curing agent are made into a paste-like curing agent, and a certain solid content is controlled to make the Fe-TiO₂ nanoparticles uniformly dispersed in the silicone rubber, forming a stable three-dimensional cross-linked structure and improving the performance of the silicone rubber product. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 It is a schematic flow chart of the preparation method of the Fe-doped TiO₂ modified silicone rubber provided in Embodiment 1 of this application;

[0038] Figure 2 It is a schematic flow chart of the preparation of iron-doped titanium dioxide nanoparticles (Fe-TiO₂ nanoparticles) by flame spray pyrolysis in the preparation method of the Fe-doped TiO₂ modified silicone rubber provided in Embodiment 1 of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] This application provides an Fe-doped TiO₂ modified silicone rubber, its preparation method and application, which are used to solve the technical problem of the lack of high-performance heat-resistant aging silicone rubber in the prior art.

[0040] The following will clearly and completely describe the technical solutions of this application with reference to the drawings. Obviously, the described embodiments are some embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0041] In view of the fact that the heat resistance of silicone rubber modified with heat-resistant additives such as TiO2 and other metal oxides still has room for improvement, and there is currently a lack of high-performance heat-resistant aging silicone rubber; the present application provides a silicone rubber modified with Fe-doped TiO2, and the raw materials include silicone rubber raw rubber, liquid curing agent, reinforcing filler, vinyl silicone oil, and Fe-TiO2 nanoparticles.

[0042] In the Fe-doped TiO2 modified silicone rubber provided by the present application, Fe-TiO2 nanoparticles are used to modify the silicone rubber; the Fe-TiO2 nanoparticles with nanoscale have a large surface area, and the active sites on the surface can form weak chemical bonds or strong physical adsorption with the Si-O main chain, which is like adding additional "anchoring points" on the main chain; in a high-temperature environment, the thermal motion of the molecular chains of the silicone rubber without adding Fe-TiO2 nanoparticles is intensified, and the Si-O bond is easily broken due to vibration and stretching. After using Fe-TiO2 nanoparticles for modification, when the thermal motion of the molecular chains of the silicone rubber is intensified by heating, the interaction between the Fe-TiO2 nanoparticles and the main chain restricts the disordered motion of the molecular chains, disperses the stress on the main chain, reduces the local stress borne by the Si-O bond, and reduces the occurrence of Si-O bond breakage, effectively maintaining the integrity of the main chain; on the other hand, Fe is doped into the TiO2 lattice in the Fe-TiO2 nanoparticles, which causes a change in the crystal phase structure of TiO2. The Fe doping causes lattice distortion of TiO2, increases the defects inside the crystal, and then generates more oxygen vacancies. These oxygen vacancies become active centers for capturing free radicals, and the captured free radicals can no longer initiate the excessive cross-linking reaction between the siloxane chains, thus avoiding the hardening and embrittlement of the silicone rubber due to excessive cross-linking, and maintaining the flexibility and stability of the silicone rubber. Thus, the thermal stability of the silicone rubber at high temperature is greatly improved. The Fe-TiO2 nanoparticles provided by the present application significantly improve the heat-resistant aging performance of the silicone rubber through the dual effects of "maintaining the integrity of the silicone rubber main chain and reducing the excessive cross-linking reaction between the siloxane chains in a high-temperature environment", thereby overcoming the defect of the current lack of high-performance heat-resistant aging silicone rubber.

[0043] As a preferred technical solution, in the Fe-doped TiO2 modified silicone rubber provided by the present application, the particle size of the Fe-TiO2 nanoparticles used is 10-40 nm, and the content of Fe atoms in the Fe-TiO2 nanoparticles is 1-3%.

[0044] As a preferred technical solution, the silicone rubber raw rubber used in the Fe-doped TiO2 modified silicone rubber provided by the present application is selected from silicone rubber raw rubbers such as methyl silicone rubber raw rubber, methyl vinyl silicone rubber raw rubber, methyl phenyl vinyl silicone rubber raw rubber, fluorosilicone rubber raw rubber, etc. However, considering that the curing system used in the present application is a peroxide curing agent, the silicone rubber raw rubber should be selected as the peroxide-cured methyl vinyl silicone rubber raw rubber.

[0045] As a preferred technical solution, in the Fe-doped TiO2 modified silicone rubber provided by the present application, since the reinforcing filler and the vulcanizing agent need to be pre-made into a paste and added, the peroxide vulcanizing agent used in the present application is a liquid-state vulcanizing agent, such as 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, methyl ethyl ketone peroxide, tert-butyl peroxybenzoate, di-tert-butyl peroxide, etc., and the reinforcing filler is selected from reinforcing fillers such as silica, carbon black, mica powder, etc. Considering that the surface active groups of fumed silica are more, the silica used in the present application is further preferably fumed silica.

[0046] As a preferred technical solution, in the Fe-doped TiO2 modified silicone rubber provided by the present application, the vinyl silicone oil used can be hydroxy vinyl silicone oil, methyl vinyl silicone oil, etc. However, considering that hydroxy vinyl silicone oil contains both "vinyl" and "hydroxy"; it is further preferably hydroxy vinyl silicone oil, and the hydroxy vinyl silicone oil and Fe-TiO2 nanoparticles are pre-made into a paste heat-resistant agent.

[0047] Correspondingly, the present application provides a preparation method of Fe-doped TiO2 modified silicone rubber. The preparation method is as follows: pre-make the reinforcing filler such as fumed silica and the vulcanizing agent into a paste curing agent, and pre-make the Fe-TiO2 nanoparticles and the vinyl silicone oil such as hydroxy vinyl silicone oil into a paste heat-resistant agent. Then, use an open mill to knead the Fe-TiO2 nanoparticles prepared by flame spray pyrolysis, the paste heat-resistant agent, and the paste curing agent. Then, use equipment such as a flat vulcanizer to vulcanize the kneaded silicone rubber, so as to obtain the Fe-doped TiO2 modified silicone rubber; the Fe-TiO2 nanoparticles used in the preparation method provided by the present application are prepared by flame spray pyrolysis. Compared with the conventional sol-gel method, solid-state method, and hydrothermal method for preparing Fe-TiO2 nanoparticles, by virtue of the ultra-high temperature and rapid quenching characteristics during the flame spray pyrolysis process, the interaction between the active components of the Fe-TiO2 nanoparticles and the silicone rubber carrier is enhanced. There is a strong interaction between the Fe-TiO2 nanoparticles and the silicone rubber molecules, so as to improve the dispersibility of the Fe-TiO2 nanoparticles, increase the active sites on the material surface, and improve the heat aging performance of the silicone rubber; and the flame spray pyrolysis method can simplify the preparation steps, reduce the cost, and realize the rapid and large-scale preparation of Fe-TiO2 nanoparticles.

[0048] In the preparation method of Fe-doped TiO₂ modified silicone rubber provided by the present application, in the step of preparing Fe-TiO₂ nanoparticles by flame spray pyrolysis, a flame spray pyrolysis reactor is used. The flame spray pyrolysis reactor can atomize the iron-titanium precursor solution prepared from an iron source and a titanium source into micron droplets with a size of 2-100 µm, and pyrolyze the micron droplets into Fe-TiO₂ nanoparticles under a flame at 1500-2500 °C.

[0049] Meanwhile, considering that the heat aging resistance of the Fe-doped TiO₂ modified silicone rubber provided by the present application is higher than that of silicone rubbers modified with metal oxide heat-resistant additives such as TiO₂, and its performance is excellent, which can meet the extremely high requirements for the high-temperature resistance of silicone rubber in the fields of aerospace or national defense industry. Therefore, the Fe-doped TiO₂ modified silicone rubber provided by the present application can be applied in the fields of aerospace and national defense industry.

[0050] Next, a Fe-doped TiO₂ modified silicone rubber, its preparation method and application provided by the present application will be specifically described in combination with examples and experimental examples.

[0051] Example 1

[0052] This example provides a preparation method of Fe-doped TiO₂ modified silicone rubber. The preparation method is as Figure 1-2 shown, and includes the steps of preparing Fe-TiO₂ nanoparticles by flame spray pyrolysis, preparing a paste-like heat-resistant agent, preparing a paste-like curing agent, mixing the silicone rubber, and vulcanizing the silicone rubber.

[0053] The steps of preparing Fe-TiO₂ nanoparticles by flame spray pyrolysis include:

[0054] Prepare an iron-titanium precursor solution. According to the preparation of 0.1 mol of Fe-TiO₂ nanoparticles, and in the total metal atoms of the Fe-TiO₂ nanoparticles, the content of Fe atoms is 2%. Weigh the corresponding tetrabutyl titanate solution (concentration: 0.5 mol / L) and ferrocene solid. First, pour an appropriate amount of absolute ethanol into a glass beaker, then slowly add the weighed tetrabutyl titanate solution, put a magnetic stir bar, turn on the magnetic stirrer, and stir at an appropriate speed to fully mix the tetrabutyl titanate in the absolute ethanol. After the tetrabutyl titanate is completely mixed, slowly add the weighed ferrocene to the above solution and continue to stir for a period of time to ensure that the ferrocene is also completely dissolved, forming a uniform iron-titanium precursor solution. During the stirring process, pay attention to observing the state of the solution. If turbidity or insoluble substances appear, it is necessary to check the quality of the raw materials or readjust the stirring conditions;

[0055] Debug the flame spray pyrolysis reactor, connect the container containing the iron-titanium precursor solution and the solution delivery pipeline of the flame spray pyrolysis reactor, ensure that the connection is firm and there is no risk of leakage; connect the solution delivery pipeline to the nozzle to ensure that the solution can be smoothly delivered to the nozzle; connect the high-speed oxygen flow supply device to the nozzle, adjust the oxygen flow rate to 8.5L / min to keep it stable; at the same time, connect the hydrogen and air supply pipelines of the flame spray pyrolysis reactor, check the connection tightness, and adjust the hydrogen flow rate to 3.3L / min and the air flow rate to 16.6L / min respectively. During the debugging process, use professional flow detection instruments to calibrate the gas flow to ensure that the flow is accurate;

[0056] The steps of atomization and high-temperature flame pyrolysis are as follows: After the iron-titanium precursor solution is connected to the flame spray pyrolysis reactor and debugged normally, the flame spray pyrolysis reactor is started, so that the matching high-speed oxygen flow supply device supplies oxygen through the nozzle at a stable flow rate; and the precursor solution delivery device delivers the iron-titanium precursor solution to the nozzle at a flow rate of 5mL / min. Under the action of the high-speed oxygen flow, the iron-titanium precursor solution is quickly atomized into tiny droplets with a size of 2~100µm and sprayed out from the nozzle; in this process, the delivery of the solution and Atomization effect: if the solution delivery is not smooth or the atomization is uneven, stop the machine in time for inspection and adjustment; after the atomized droplets are sprayed out, the hydrogen / air at the port of the ignited flame spray pyrolysis reactor diffuses the flame and burns stably. The flame temperature is about 2000°C. The high temperature of the flame will cause the atomized iron-titanium precursor droplets to undergo a rapid combustion reaction, and the organic components in them will quickly burn and decompose. The compounds of titanium and iron begin to undergo complex chemical reactions, gradually forming iron-doped titanium dioxide nanoparticles (Fe-TiO2 nanoparticles) with a diameter of 10~40nm.

[0057] The steps of collecting and storing Fe-TiO2 nanoparticles are as follows: using the negative pressure provided by the vacuum pump of the flame spray pyrolysis reactor to collect the Fe-TiO2 nanoparticles generated by the reaction through the filter cloth along with the air flow; the nanoparticles are retained on the filter cloth, while the gas is sucked away by the vacuum pump through the filter cloth. During the collection process, it is necessary to pay attention to the operation of the collection device to prevent the filter cloth from being blocked and affecting the collection efficiency. After collecting for a period of time, carefully remove the filter cloth and transfer the collected Fe-TiO2 nanoparticles to a suitable storage container. The storage container should be kept dry and clean to prevent the Fe-TiO2 nanoparticles from being contaminated.

[0058] The steps of preparing the paste heat-resistant agent include: adding 3.5g of Fe-TiO2 nanoparticles and 1.5g of hydroxyvinyl silicone oil into a high-speed mixer, stirring at 2000rpm for 5min, and preparing a paste heat-resistant agent with a solid content of 70wt%.

[0059] The steps for preparing the paste curing agent include: putting a certain amount of 0.4 g of liquid curing agent 2,5-dimethyl-2,5-di-tert-butylperoxyhexane and 1.6 g of reinforcing filler fumed silica into a high-speed mixer, and stirring at a speed of 2000 rpm for 5 min to prepare a paste curing agent with a solid content of 80%.

[0060] The steps for mixing the silicone rubber include: weighing 100 g of peroxide-cured methyl vinyl silicone rubber raw rubber, adding 2.86 g of paste heat-resistant agent, and mixing on an open mill for 15 min. Then weigh 0.7 g of paste curing agent and add it, continue to mix evenly on the open mill, and the mixing time is 5 min. Extrude a sheet about 2 mm thick, which is the semi-finished silicone rubber after mixing; during the mixing process, all components are fully fused to ensure the consistency of the silicone rubber properties.

[0061] The steps for curing the silicone rubber include: putting the mixed silicone rubber sheet into a mold, and molding it under a pressure of 10 MPa for 15 min; then curing at 200 °C for 4 h to make the silicone rubber form a stable three-dimensional cross-linked structure, improving its physical and chemical properties, and obtaining an Fe-TiO2 nanoparticle-modified silicone rubber product.

[0062] Example 2

[0063] This example provides a preparation method of TiO2-modified silicone rubber. As the first comparative example, the preparation method includes the steps of preparing a paste heat-resistant agent, preparing a paste curing agent, mixing the silicone rubber, and curing the silicone rubber.

[0064] The steps for preparing the paste heat-resistant agent include: putting 3.5 g of TiO2 nanoparticles and 1.5 g of hydroxyvinyl silicone oil into a high-speed mixer, and stirring at 2000 rpm for 5 min to obtain a paste heat-resistant agent with a solid content of 70 wt%.

[0065] The steps for preparing the paste curing agent include: putting a certain amount of 0.4 g of liquid curing agent 2,5-dimethyl-2,5-di-tert-butylperoxyhexane and 1.6 g of reinforcing filler fumed silica into a high-speed mixer, and stirring at a speed of 2000 rpm for 5 min to prepare a paste curing agent with a solid content of 80%.

[0066] The steps for mixing the silicone rubber include: weighing 100 g of peroxide-cured methyl vinyl silicone rubber raw rubber, adding 2.86 g of paste heat-resistant agent, and mixing on an open mill for 15 min. Then weigh 0.7 g of paste curing agent and add it, continue to mix evenly on the open mill, and extrude a sheet about 2 mm thick, which is the semi-finished silicone rubber after mixing; during the mixing process, all components are fully fused to ensure the consistency of the silicone rubber properties.

[0067] The steps of silicone rubber vulcanization include: putting the kneaded silicone rubber sheet into a mold and pressing it at a pressure of 10 MPa for 15 min; then curing it at 200 °C for 4 h to form a stable three-dimensional crosslinked structure of the silicone rubber, improving its physical and chemical properties, and obtaining a TiO2-modified silicone rubber product.

[0068] Example 3

[0069] This example provides a preparation method of silicone rubber. As the second comparative example, the preparation method includes the steps of preparing a paste curing agent, kneading the silicone rubber, and vulcanizing the silicone rubber.

[0070] The steps of preparing the paste curing agent include: putting a certain amount of 0.4 g of liquid curing agent 2,5-dimethyl-2,5-di-tert-butylperoxyhexane and 1.6 g of reinforcing filler fumed silica into a high-speed mixer and stirring at a speed of 2000 rpm for 5 min to prepare a paste curing agent with a solid content of 80%.

[0071] The steps of kneading the silicone rubber include: weighing 100 g of peroxide-cured methyl vinyl silicone rubber raw rubber, adding 0.7 g of the paste curing agent, mixing evenly on an open mill, and extruding a sheet about 2 mm thick to obtain a semi-finished product of the kneaded silicone rubber; during the kneading process, all components are fully fused to ensure the consistency of the silicone rubber properties.

[0072] The steps of silicone rubber vulcanization include: putting the kneaded silicone rubber sheet into a mold and pressing it at a pressure of 10 MPa for 15 min; then curing it at 200 °C for 4 h to form a stable three-dimensional crosslinked structure of the silicone rubber, improving its physical and chemical properties, and obtaining an unmodified silicone rubber product.

[0073] Experimental Example 1

[0074] In this Experimental Example 1, the silicone rubber products provided in Examples 1-3 were subjected to performance tests. The performance tests were carried out according to ISO188:2023 "Vulcanized rubber or thermoplastic rubber - Tests for accelerated ageing and heat resistance". For the tensile strength, Young's modulus before and after the heat ageing test and the tensile strength test in the thermogravimetric test, the test was carried out with reference to GB / T 528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The Young's modulus test was carried out with reference to GB / T 528 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber". The thermogravimetric test was carried out with reference to GB / T 14837.1 "Rubber and rubber products - Determination of the composition of vulcanizates and uncured compounds by thermogravimetry". The test results are shown in Table 1.

[0075] Table 1: Heat ageing test results

[0076]

[0077] As can be seen from Table 1, the mechanical properties such as tensile strength, Shore hardness, and elongation at break of the silicone rubbers provided in Examples 1-3 before thermal aging are not very different. The silicone rubbers provided in Examples 1-2 have increased thermal weight loss temperature due to the addition of heat-resistant additives. After thermal aging at 300 °C for 72 hours, the silicone rubber provided in Example 3 was not modified with TiO2 nanoparticles and Fe-TiO2 nanoparticles and had completely embrittled after thermal aging at 300 °C for 72 hours, and its tensile strength, Shore hardness, and elongation at break could not be measured. The silicone rubber provided in Example 2 was modified with TiO2 nanoparticles. After aging at 300 °C for 72 hours, its mechanical properties such as tensile strength, Shore hardness, and elongation at break were maintained to a certain extent. After thermal aging of the silicone rubber, the tensile strength and elongation at break decayed relatively fast, while the Shore hardness increased significantly. The silicone rubber provided in Example 1 was modified with Fe-TiO2 nanoparticles. After aging at 300 °C for 72 hours, its mechanical properties such as tensile strength, Shore hardness, and elongation at break were significantly maintained. After thermal aging of the silicone rubber, the tensile strength and elongation at break remained at 44% and 23% of the original values respectively, and the Shore hardness only increased by 19%. The mechanical properties such as elongation at break were well maintained, and the hardness also increased less.

[0078] Meanwhile, the structural changes of the silicone rubber during high-temperature thermal aging were studied by infrared spectroscopy analysis. The results showed that after thermal aging at 300 °C for 72 hours, the -CH3 vibration peak of the silicone rubbers provided in Examples 2-3 decreased significantly, while the -CH3 vibration peak of the silicone rubber provided in Example 1 still maintained a relatively high intensity after thermal aging at 300 °C for 72 hours. Through the above tests, it can be shown that the Fe-TiO2 nanoparticles in the silicone rubber provided in this application significantly improved the heat aging resistance of the silicone rubber through the dual effects of "maintaining the integrity of the silicone rubber main chain and reducing the excessive cross-linking reaction between silicon-oxygen chains" in a high-temperature environment, and the mechanical properties were not easily attenuated, and the hardness was difficult to increase and become brittle.

[0079] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A silicone rubber modified by Fe-doped TiO2, characterized in that, It includes silicone rubber raw rubber, liquid vulcanizing agent, reinforcing filler, vinyl silicone oil and Fe-TiO₂ nanoparticles.

2. The silicone rubber modified by Fe-doped TiO2 according to claim 1, characterized in that, The particle size of the Fe-TiO₂ nanoparticles is 10 - 40 nm.

3. A silicone rubber modified by Fe-doped TiO2 according to claim 1, wherein, In the Fe-TiO₂ nanoparticles, the content of Fe atoms is 1 - 3%.

4. A silicone rubber modified with Fe-doped TiO2 according to claim 1, characterized in that, The silicone rubber raw rubber is selected from at least one of methyl silicone rubber raw rubber, methyl vinyl silicone rubber raw rubber, methyl phenyl vinyl silicone rubber raw rubber, and fluorosilicone rubber raw rubber.

5. A silicone rubber modified by Fe-doped TiO2 according to claim 1, characterized in that, The liquid vulcanizing agent is selected from at least one of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, methyl ethyl ketone peroxide, tert-butyl peroxybenzoate, and di-tert-butyl peroxide; The reinforcing filler is selected from at least one of silica, carbon black, and mica powder.

6. A silicone rubber modified with Fe-doped TiO2 according to claim 1, characterized in that, The vinyl silicone oil is selected from at least one of hydroxy vinyl silicone oil and methyl vinyl silicone oil.

7. A silicone rubber modified by Fe-doped TiO2 according to claim 1, characterized in that, Calculated by mass, the silicone rubber raw material modified by Fe-doped TiO₂ includes 50 - 150 parts by mass of silicone rubber raw rubber, 0.1 - 0.2 parts by mass of liquid catalyst, 0.1 - 1 part by mass of reinforcing filler, 0.5 - 1 part by mass of vinyl silicone oil, and 1 - 3 parts by mass of Fe-TiO₂ nanoparticles.

8. A method for preparing a Fe-doped TiO2 modified silicone rubber according to any one of claims 1-7, characterized in that, It includes the following steps: The step of preparing a paste heat-resistant agent, preparing Fe-TiO₂ nanoparticles by flame spray pyrolysis method, and mixing the Fe-TiO₂ nanoparticles and vinyl silicone oil evenly to obtain a paste heat-resistant agent; The step of preparing a paste curing agent, mixing the reinforcing filler and liquid vulcanizing agent evenly to obtain a paste curing agent; The step of silicone rubber mixing, adding the paste heat-resistant agent and paste curing agent into the silicone rubber raw rubber in turn in an open mill for mixing to obtain the mixed silicone rubber; The step of silicone rubber vulcanization, vulcanizing the mixed silicone rubber to obtain the silicone rubber modified by Fe-doped TiO₂.

9. The preparation method of a Fe-doped TiO2 modified silicone rubber according to claim 8, characterized in that, In the step of preparing the paste heat-resistant agent, the step of preparing Fe-TiO₂ nanoparticles by flame spray pyrolysis method includes: Step S1, dissolving a titanium source and an iron source in a solvent to obtain an iron-titanium precursor solution; Step S2, connecting the iron-titanium precursor solution to the nozzle of the flame spray pyrolysis reactor; Step S3, starting the flame spray pyrolysis reactor, atomizing the iron-titanium precursor solution into micron droplets, and pyrolyzing the micron droplets to obtain Fe-TiO₂ nanoparticles.

10. Application of a silicone rubber modified by Fe-doped TiO₂ according to any one of claims 1 - 7 in the fields of aerospace or national defense industry.

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