Flexible low-ablation material as well as preparation method and application thereof

Abstract

The embodiment of the invention belongs to the technical field of polymer composite materials, and particularly relates to a flexible low-ablation material and a preparation method and application thereof. The flexible low-ablation material comprises epoxidized vinyl silicone rubber and fibers, the epoxidized vinyl silicone rubber and the fibers are mixed to form a three-dimensional interpenetrating network structure; the fibers comprise carbon fibers and aramid fibers; the vinyl content of the epoxidized vinyl silicone rubber is 60-80%, and the epoxy group content is 5-8%. According to the embodiment of the invention, the epoxidized vinyl silicone rubber with a unique three-dimensional cross-linked network structure is constructed by introducing high-content vinyl and epoxy groups, and then the epoxidized vinyl silicone rubber is compounded with the carbon fibers and the aramid fibers, so that a gradient carbon layer structure is constructed on the surface of the material, and the material has high-temperature airflow scouring resistance, is excellent in guarantee of low ablation rate and is easy to industrialize.

Description

Technical Field

[0001] The embodiments of the present invention belong to the technical field of polymer composite materials, and specifically relate to a flexible low-ablation material and a preparation method and application thereof. Background Art

[0002] Silicone rubber (Silicone Rubber) is a polymer elastic material with a silicon-oxygen bond (Si-O) as its main chain. Based on different vulcanization mechanisms, silicone rubber can be divided into room temperature vulcanization (RTV), heat vulcanization (HTV), and addition reaction silicone rubber (LSR). Among them, addition reaction silicone rubber (LSR) has the following notable characteristics: excellent temperature resistance, maintaining softness and elasticity over a wide temperature range of -65°C to 200°C for a long time; excellent stability with outstanding electrical and chemical properties, as well as resistance to weathering, water, and ozone; safety and environmental protection: non-toxic, odorless, non-corrosive, and physiologically inert; processing advantages: low linear shrinkage and easy processing and molding. Based on these excellent properties, addition reaction silicone rubber has been widely used in a variety of important fields such as aerospace, military equipment, medical equipment, power, automotive industry, building seals, and daily chemical products.

[0003] In the power industry, silicone rubber can also be used to manufacture cables. However, the oxygen index of silicone rubber itself is far less than 30, making it susceptible to ablation in extremely high-temperature environments and prone to aging under the impact of high-temperature airflow, leading to a decrease in electrical performance. In the existing technology, silicone rubber is often modified by adding copolyphenylsiloxane and POSS. Although this can partially improve its resistance to high-temperature airflow erosion and low ablation rate, it has problems such as complex processes, high costs, and uneven filler dispersion. Therefore, there is an urgent need to develop a new flexible ablative material that combines high carbon residue rate, low ablation rate, and good processability. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a flexible low-ablation material and its preparation method and application, so as to overcome the shortcomings of the existing technology. It is based on epoxidized vinyl silicone rubber (EMVQ) and is reinforced by carbon fiber (CF) and aramid fiber (AF). It has resistance to high-temperature airflow erosion and excellent low ablation rate, and is easy to industrialize.

[0005] In order to achieve the above objectives, the technical solutions of the embodiments of the present invention are as follows:

[0006] In a first aspect, an embodiment of the present invention provides a flexible low-ablation material, comprising epoxidized vinyl silicone rubber and fiber; the epoxidized vinyl silicone rubber and the fiber are mixed to form a three-dimensional interpenetrating network structure;

[0007] Fibers include carbon and aramid fibers;

[0008] The vinyl content of epoxidized vinyl silicone rubber is 60%-80%, and the epoxy content is 5-8%.

[0009] In some other embodiments, the mass ratio of epoxidized vinyl silicone rubber to fiber is (5-15): (1-3);

[0010] Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by mass: 800-1200 parts of octamethylcyclotetrasiloxane, 3-6 parts of a catalyst, and 10-20 parts of a vinyl end-capping agent.

[0011] In some other embodiments, the mass ratio of the epoxidized vinyl silicone rubber to the fiber is 10:1;

[0012] Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane, 5 parts of a catalyst, and 10-20 parts of a vinyl end-capping agent. The reaction is more complete within this ratio range.

[0013] In some other embodiments, the catalyst is one of potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, and tetraethylphosphonium hydroxide;

[0014] The vinyl end-capping agent is one of vinyldimethylchlorosilane and vinyl-terminated phenyl polysiloxane;

[0015] Optionally, the catalyst is tetramethylammonium hydroxide;

[0016] The vinyl end-capping agent is vinyldimethylsilyl chloride.

[0017] In some other embodiments, the fibers are a blend of carbon fibers and aramid fibers;

[0018] The mixed mass ratio of carbon fiber and aramid fiber is (2-4): (1-3);

[0019] Optionally, the carbon fiber and aramid fiber are mixed in a mass ratio of 3:2.

[0020] In a second aspect, an embodiment of the present invention provides a method for preparing the flexible low-ablation material according to the first aspect, comprising the following steps:

[0021] Under a nitrogen atmosphere, octamethylcyclotetrasiloxane and a catalyst are mixed to react, and then a vinyl end-capping agent is added dropwise to continue the reaction. After the reaction is completed, water is added to terminate the reaction to obtain epoxidized vinyl silicone rubber.

[0022] The flexible low-ablative material is prepared by mixing epoxidized vinyl silicone rubber and fiber and then hot pressing.

[0023] In some other embodiments, in the method for synthesizing epoxidized vinyl silicone rubber, the reaction temperature is 85-95° C. and the reaction time is 3-5 h;

[0024] The temperature for adding the vinyl blocking agent dropwise is 55-65°C and the addition time is 20-40 minutes;

[0025] The reaction time is 1.5-2.5h;

[0026] Optionally, the reaction temperature is 90° C. and the reaction time is 4 h;

[0027] The temperature for adding the vinyl blocking agent dropwise is 60°C and the addition time is 30 min;

[0028] The reaction time was continued for 2 h.

[0029] The raw materials in this reaction process are easy to add and the reaction process is relatively mild, which is conducive to improving processing efficiency.

[0030] In some other embodiments, the method for synthesizing epoxidized vinyl silicone rubber further comprises, after terminating the reaction, continuing stirring, vacuum distillation, and filtering; the stirring time is 20-40 minutes, the vacuum distillation temperature is 115-125° C., and the pressure is -0.09 to -0.08 MPa;

[0031] Optionally, the stirring time is continued for 30 minutes, the temperature of the reduced pressure distillation is 120° C., and the pressure is -0.095 MPa.

[0032] Continuing to stir after terminating the reaction facilitates a more complete reaction, and vacuum distillation removes unreacted D4, methanol, and the byproduct HCl. Filtration yields a transparent, viscous liquid, EMVQ.

[0033] In some other embodiments, the mass ratio of epoxidized vinyl silicone rubber and fiber is (5-15): (1-3);

[0034] The fiber is made of carbon fiber and aramid fiber mixed in a mass ratio of (2-4): (1-3);

[0035] The hot pressing temperature is 120-160°C and the time is 3-10 minutes;

[0036] Optionally, the mass ratio of epoxidized vinyl silicone rubber and fiber is 10:1;

[0037] The fiber is a mixture of carbon fiber and aramid fiber in a mass ratio of 3:2;

[0038] The hot pressing temperature was 150°C and the time was 5 min.

[0039] In a third aspect, an embodiment of the present invention provides an application of the flexible low-ablation material described in the first aspect in wires and cables.

[0040] In a fourth aspect, an embodiment of the present invention provides a wire and cable using the flexible low-ablation material described in the first aspect.

[0041] Beneficial effects of the embodiments of the present invention:

[0042] (1) The epoxidized vinyl silicone rubber (EMVQ) in the embodiments of the present invention constructs a unique three-dimensional cross-linked network structure by introducing a high content of vinyl and epoxy groups. Under high temperature conditions, the vinyl forms a dense carbonized layer through a free radical cross-linking reaction, while the epoxy groups participate in the formation of a stable Si-OC bond network. This dual cross-linking mechanism can effectively inhibit the "backbiting degradation" and cyclization reaction of the silicone rubber main chain, thereby improving the carbon residue rate of the material at high temperatures. Carbon fiber (CF) and aramid fiber (AF) are used as reinforcing fibers to construct a skeleton support structure, thereby improving the density of the carbon layer and its anti-scouring ability.

[0043] (2) By optimizing the compounding ratio of carbon fiber (CF) and aramid fiber (AF), a gradient carbon layer structure was constructed on the surface of the material, in which CF provided rigid skeleton support with a dimensionality of more than 90%; AF filled the CF network gaps through a melting-carbonization process; and SiO2 generated by high-temperature decomposition of the EMVQ matrix further densified the carbon layer.

[0044] (3) The preparation process is simple and adopts an integrated synthesis process without the need for complex filler dispersion process. Vinyl silicone oil anionic ring-opening polymerization; in-situ m-CPBA epoxidation reaction; directly blended with carbon fiber (CF) and aramid fiber (AF) in a certain proportion. DETAILED DESCRIPTION

[0045] Those skilled in the art will appreciate that the following examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the present invention. Unless otherwise specified, the examples were performed under conventional conditions or manufacturer-recommended conditions. Components used without manufacturer identification are commercially available conventional products.

[0046] To facilitate understanding of the technical solutions of the embodiments of the present invention, the raw materials involved are further described as follows:

[0047] Raw materials: octamethylcyclotetrasiloxane (D4) manufacturer Aladdin reagent, tetramethylammonium hydroxide (TMAOH) manufacturer Aladdin reagent, vinyldimethylchlorosilane manufacturer Aladdin reagent, carbon fiber (CF) aspect ratio (100-500):1, aramid fiber (AF) aspect ratio (30-80):1.

[0048] The specific implementation methods of the embodiments of the present invention address the fact that silicone rubber itself has an oxygen index far less than 30, making it difficult to meet the high flame retardancy requirements for materials used in cable manufacturing. While existing technologies have partially improved the performance of silicone rubber by copolymerizing phenylsiloxane or adding POSS, these technologies suffer from complex processes, high costs, and uneven filler dispersion. Therefore, there is an urgent need to develop a new flexible ablative material that combines a high carbon residue rate, a low ablation rate, and good processability.

[0049] To address these technical challenges, embodiments of the present invention provide a flexible, low-ablation material, its preparation method, and its application. This flexible, low-ablation material can be used for cables in extremely high-temperature environments. This material, based on epoxidized vinyl silicone rubber (EMVQ) and reinforced with carbon fiber (CF) and aramid fiber (AF), exhibits excellent high-temperature resistance, a low linear ablation rate, and a high carbon residue rate.

[0050] The solutions provided by the embodiments of the present invention are as follows:

[0051] An embodiment of the present invention provides a flexible low-ablation material, comprising epoxidized vinyl silicone rubber and fiber; the epoxidized vinyl silicone rubber and fiber are mixed to form a three-dimensional interpenetrating network structure;

[0052] Fibers include carbon and aramid fibers;

[0053] The vinyl content of epoxidized vinyl silicone rubber is 60%-80%, and the epoxy content is 5-8%.

[0054] The inventors discovered that high vinyl content inhibits degradation of the epoxidized vinyl silicone rubber (EMVQ) backbone (composed of alternating Si-O-Si inorganic backbones and organic vinyl side chains), forming a dense cross-linked network and increasing the carbon residue rate. The epoxy functional groups are distributed within the three-dimensional network structure through chemical grafting, and the epoxy groups also enhance adhesion to the metal shell. Carbon fiber (CF) and aramid fiber (AF) serve as reinforcing fibers to construct a gradient carbon layer structure within the epoxidized vinyl silicone rubber. CF provides rigid skeletal support with a dimensionality ratio exceeding 90%. AF fills the gaps in the CF network through a melt-carbonization process. SiO2 generated by high-temperature cracking of the EMVQ matrix further densifies the carbon layer. The synergistic effect of the epoxidized vinyl silicone rubber and the fibers improves the carbon layer density and scour resistance of the composite material.

[0055] In some other embodiments, the mass ratio of the epoxidized vinyl silicone rubber to the fiber is (5-15): (1-3); this range value includes the boundary values, that is, the mass of the epoxidized vinyl silicone rubber is 5 and 15; the mass of the fiber is 1 and 3; the mass ratio of the epoxidized vinyl silicone rubber to the fiber can be 5:1, 5:2, 5:3, 15:1, 15:2, 15:3, or any intermediate range value can be used, such as 6:1, 6:2, 6:3, 8:1, 8:2, 8:3, 10:1, 10:2, 10:3, 12:1, 12:2, 12:3, 14:1, 14:2, 14:3.

[0056] Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by mass: 800-1200 parts of octamethylcyclotetrasiloxane, 3-6 parts of catalyst, and 10-20 parts of vinyl end-capping agent. This range value includes the boundary value, i.e., 800 and 1200 parts of octamethylcyclotetrasiloxane, 3 and 6 parts of catalyst, and 10 and 20 parts of vinyl end-capping agent. Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by mass: 800 parts of octamethylcyclotetrasiloxane, 3 parts of catalyst, and 10 parts of vinyl end-capping agent, or 1200 parts of octamethylcyclotetrasiloxane, 6 parts of catalyst, and 20 parts of vinyl end-capping agent, or 1000 parts of octamethylcyclotetrasiloxane, 5 parts of catalyst, and 15 parts of vinyl end-capping agent.

[0057] During the preparation of epoxidized vinyl silicone rubber, tetramethylammonium hydroxide (TMAOH) is used as an alkaline catalyst to initiate the ring-opening polymerization of the D4 ring to generate a hydroxyl-terminated polydimethylsiloxane (PDMS) intermediate: in the chain termination stage, a vinyl capping agent needs to be added to replace the terminal hydroxyl group and introduce vinyl groups to construct a unique three-dimensional cross-linked network structure.

[0058] In some other embodiments, the mass ratio of the epoxidized vinyl silicone rubber to the fiber is 10:1;

[0059] Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane, 5 parts of a catalyst, and 10-20 parts of a vinyl end-capping agent. The reaction is more complete within this ratio range.

[0060] In some other embodiments, the catalyst is one of potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide, and tetraethylphosphonium hydroxide;

[0061] The vinyl end-capping agent is one of vinyldimethylchlorosilane and vinyl-terminated phenyl polysiloxane;

[0062] Optionally, the catalyst is tetramethylammonium hydroxide;

[0063] The vinyl end-capping agent is vinyldimethylsilyl chloride.

[0064] The catalytic reaction of the catalyst within this range is more thorough; and the vinyl groups of the vinyl end-capping agent form a dense carbonized layer through free radical cross-linking reaction, thereby increasing the residual carbon rate.

[0065] In some other embodiments, the fibers are a blend of carbon fibers and aramid fibers;

[0066] The mixed mass ratio of carbon fiber and aramid fiber is (2-4): (1-3); this range value includes the boundary values, that is, the mass of carbon fiber is 2 and 4; the mass of aramid fiber is 1 and 3; the mixed mass ratio of carbon fiber and aramid fiber is 2:1, 2:2, 2:3, 4:1, 4:2, 4:3, and any intermediate range value can also be used, such as 3:1, 3:2, 3:3.

[0067] Optionally, the carbon fiber and aramid fiber are mixed in a mass ratio of 3:2.

[0068] By optimizing the compounding ratio of carbon fiber (CF) and aramid fiber (AF) (the optimal ratio is 3:2), a gradient carbon layer structure is constructed on the surface of the material: CF provides rigid skeleton support with a dimensionality rate of more than 90%; AF fills the CF network gaps through the melting-carbonization process, making the dispersion more uniform and further improving the mechanical properties.

[0069] Another embodiment of the present invention provides a method for preparing a flexible low-ablation material, comprising the following steps:

[0070] Under a nitrogen atmosphere, octamethylcyclotetrasiloxane and a catalyst are mixed to react, and then a vinyl end-capping agent is added dropwise to continue the reaction. After the reaction is completed, water is added to terminate the reaction to obtain epoxidized vinyl silicone rubber.

[0071] The flexible low-ablative material is prepared by mixing epoxidized vinyl silicone rubber and fiber and then hot pressing.

[0072] In some other embodiments, in the method for synthesizing epoxidized vinyl silicone rubber, the reaction temperature is 85-95° C. and the reaction time is 3-5 h;

[0073] The temperature for adding the vinyl blocking agent dropwise is 55-65°C and the addition time is 20-40 minutes;

[0074] The reaction time is 1.5-2.5h;

[0075] Optionally, the reaction temperature is 90° C. and the reaction time is 4 h;

[0076] The temperature for adding the vinyl blocking agent dropwise is 60°C and the addition time is 30 min;

[0077] The reaction time was continued for 2 h.

[0078] The raw materials in this reaction process are easy to add and the reaction process is relatively mild, which is conducive to improving processing efficiency.

[0079] In some other embodiments, the method for synthesizing epoxidized vinyl silicone rubber further comprises, after terminating the reaction, continuing stirring, vacuum distillation, and filtering; the stirring time is 20-40 minutes, the vacuum distillation temperature is 115-125° C., and the pressure is -0.09 to -0.08 MPa;

[0080] Optionally, the stirring time is continued for 30 minutes, the temperature of the reduced pressure distillation is 120° C., and the pressure is -0.095 MPa.

[0081] Continuing to stir after terminating the reaction facilitates a more complete reaction, and vacuum distillation removes unreacted D4, methanol, and the byproduct HCl. Filtration yields a transparent, viscous liquid, EMVQ.

[0082] In some other embodiments, the mass ratio of epoxidized vinyl silicone rubber and fiber is (5-15): (1-3);

[0083] The fiber is made of carbon fiber and aramid fiber mixed in a mass ratio of (2-4): (1-3);

[0084] The hot pressing temperature is 120-160°C and the time is 3-10 minutes;

[0085] Optionally, the mass ratio of epoxidized vinyl silicone rubber and fiber is 10:1;

[0086] The fiber is a mixture of carbon fiber and aramid fiber in a mass ratio of 3:2;

[0087] The hot pressing temperature was 150°C and the time was 5 min.

[0088] Yet another embodiment of the present invention provides an application of a flexible low-ablative material in wires and cables.

[0089] Other embodiments of the present invention provide a wire and cable using the flexible low-ablation material described in the first aspect.

[0090] In order to verify or understand the solutions provided by the embodiments of the present invention, the following is a description using specific experimental examples:

[0091] The reaction mechanism and steps of epoxidized vinyl silicone rubber (EMVQ) in the embodiment of the present invention are as follows:

[0092] (1) Anionic ring-opening polymerization of octamethylcyclotetrasiloxane (D4)

[0093] Tetramethylammonium hydroxide (TMAOH) acts as a basic catalyst to initiate the ring-opening polymerization of the D4 ring to generate a hydroxyl-terminated polydimethylsiloxane (PDMS) intermediate:

[0094] Initiation phase:

[0095] [(CH3)2SiO]4+OH - →[(CH3)2SiO]3Si(CH3)2O - +H2O

[0096] Chain growth stage: silicon alkoxide anion (CH3)2SiO] - n Continuously attacking D4 molecules to form linear polymer chains:

[0097] [(CH3)2SiO] - n +[(CH3)2SiO]4→[(CH3)2SiO] - n+4

[0098] (2) Vinyl end-capping to generate epoxidized vinyl silicone rubber (EMVQ)

[0099] In the chain termination stage, a vinyl end-capping agent needs to be added to replace the terminal hydroxyl group and introduce a vinyl group:

[0100] [(CH3)2SiO] - n +CH2=CH-(CH3)2SiCl→CH2=CH-(CH3)2Si-[O-Si(CH3)2] n -O - +Cl - Finally terminated by neutralization reaction:

[0101] CH2=CH-(CH3)2Si-[O-Si(CH3)2] n -O - +H2O→CH2=CH-(CH3)2Si-[O-Si(CH3)2] n -OH+OH -

[0102] Example 1

[0103] A flexible low-ablation material and its preparation method

[0104] (1) Epoxidized vinyl silicone rubber (EMVQ), composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane (D4), 5 parts of tetramethylammonium hydroxide (TMAOH), and 10 parts of vinyldimethylchlorosilane. The tetramethylammonium hydroxide is a 25% methanol solution of tetramethylammonium hydroxide;

[0105] (2) A method for preparing epoxidized vinyl silicone rubber (EMVQ), comprising the following steps:

[0106] Step 1: Dehydration of octamethylcyclotetrasiloxane (D4)

[0107] D4 was added into the reactor and nitrogen was bubbled into the reactor for 30 minutes to remove trace moisture in the raw materials.

[0108] Step 2: Anionic ring-opening polymerization

[0109] Add TMAOH methanol solution, raise the temperature to 90°C, and start stirring. React for 4 hours, monitoring the polymerization progress by viscosity changes or sampling and measuring molecular weight (GPC).

[0110] Step 3: Vinyl Capping

[0111] Cool to 60°C and slowly add vinyldimethylsilyl chloride dropwise over 30 minutes. Continue the reaction for 2 hours to ensure complete reaction of the terminal hydroxyl groups. The mixing ratio of D4 to vinyldimethylsilyl chloride is 100:1.

[0112] Step 4: Termination and post-processing

[0113] Add a small amount of deionized water to terminate the reaction and stir for 30 minutes. Raise the temperature to 120°C and distill under reduced pressure (-0.095 MPa) to remove unreacted D4, methanol, and the byproduct HCl. Filter to obtain a transparent, viscous liquid, EMVQ.

[0114] (3) A method for preparing a flexible low-ablation material, comprising the following steps:

[0115] EMVQ was blended with fibers (mixing mass ratio of 10:1, wherein the fibers were carbon fibers and aramid fibers mixed at a mass ratio of 3:2), and hot pressing was performed (temperature of 150°C, time of 5 min) to obtain a flexible ablative material.

[0116] Example 2

[0117] A flexible low-ablation material and its preparation method

[0118] (1) Epoxidized vinyl silicone rubber (EMVQ), composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane (D4), 5 parts of tetramethylammonium hydroxide (TMAOH), and 15 parts of vinyldimethylchlorosilane. The tetramethylammonium hydroxide is a 25% methanol solution of tetramethylammonium hydroxide;

[0119] (2) The preparation method of epoxidized vinyl silicone rubber (EMVQ) is different from that of Experimental Example 1 in that, in step 3, D4 (octamethylcyclotetrasiloxane) and vinyldimethylchlorosilane are mixed at a ratio of 200:3, and the other preparation steps are the same as those of Example 1.

[0120] (3) The method for preparing the flexible low-ablation material is different from that of Experimental Example 1 in that the epoxidized vinyl silicone rubber prepared in (2) is used, and the other preparation steps are the same as those of Example 1.

[0121] Example 3

[0122] A flexible low-ablation material and its preparation method

[0123] (1) Epoxidized vinyl silicone rubber (EMVQ), composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane (D4), 5 parts of tetramethylammonium hydroxide (TMAOH), and 20 parts of vinyldimethylchlorosilane. The tetramethylammonium hydroxide is a 25% methanol solution of tetramethylammonium hydroxide;

[0124] (2) The preparation method of epoxidized vinyl silicone rubber (EMVQ) is different from that of Experimental Example 1 in that, in step 3, D4 (octamethylcyclotetrasiloxane) and vinyldimethylchlorosilane are mixed at a ratio of 50:1, and the other preparation steps are the same as those of Example 1.

[0125] (3) The method for preparing the flexible low-ablation material is different from that of Experimental Example 1 in that the epoxidized vinyl silicone rubber prepared in (2) is used, and the other preparation steps are the same as those of Example 1.

[0126] Comparative Example 1

[0127] A flexible low-ablation material and its preparation method

[0128] (1) Epoxidized vinyl silicone rubber (EMVQ), composed of the following components, calculated by weight: 800 parts of octamethylcyclotetrasiloxane (D4), 200 parts of octaphenylcyclotetrasiloxane, 5 parts of tetramethylammonium hydroxide (TMAOH), and 10 parts of vinyldimethylsilyl chloride. The tetramethylammonium hydroxide is a 25% methanol solution of tetramethylammonium hydroxide;

[0129] (2) The preparation method of epoxidized vinyl silicone rubber (EMVQ) is different from that of Experimental Example 1 in that, in step 3, D4 (octamethylcyclotetrasiloxane) and vinyldimethylchlorosilane are mixed at a ratio of 80:1, and the other preparation steps are the same as those of Example 1.

[0130] (3) The method for preparing the flexible low-ablation material is different from that of Experimental Example 1 in that the epoxidized vinyl silicone rubber prepared in (2) is used, and the other preparation steps are the same as those of Example 1.

[0131] Comparative Example 2

[0132] A flexible low-ablation material and its preparation method

[0133] (1) Epoxidized vinyl silicone rubber (EMVQ), composed of the following components, calculated by weight: 1000 parts of octamethylcyclotetrasiloxane (D4), 5 parts of tetramethylammonium hydroxide (TMAOH), and 10 parts of vinyl-terminated phenyl polysiloxane. The tetramethylammonium hydroxide is a 25% methanol solution of tetramethylammonium hydroxide;

[0134] (2) The preparation method of epoxidized vinyl silicone rubber (EMVQ) is the same as that in Example 1.

[0135] (3) The method for preparing the flexible low-ablation material is different from that of Experimental Example 1 in that the epoxidized vinyl silicone rubber prepared in (2) is used, and the other preparation steps are the same as those of Example 1.

[0136] Comparative Example 3

[0137] A flexible low-ablation material and its preparation method

[0138] Different from Example 1, (3) CF and AF are not added during the preparation of the flexible ablative material.

[0139] Comparative Example 4

[0140] A flexible low-ablation material and its preparation method

[0141] The difference from Example 1 is that (3) only CF is added during the preparation of the flexible ablative material, and EMVQ and CF are blended (mixing mass ratio 50:5). The other preparation methods are the same as Example 1.

[0142] Comparative Example 5

[0143] A flexible low-ablation material and its preparation method

[0144] The difference from Example 1 is that in the preparation method of (3) the flexible low-ablation material, only AF is added, and EMVQ and AF are blended (mixing mass ratio 50:5). The other preparation methods are the same as Example 1.

[0145] Performance Testing

[0146] The content of vinyl and epoxy groups in epoxidized vinyl silicone rubber was determined by infrared spectroscopy: 910 cm -1 The characteristic peak of epoxy group appears around 1640cm -1 The specific content is shown in Table 1.

[0147] Table 1 Infrared spectrum measurement results

[0148] serial number Vinyl content (mol / g) <![CDATA[1640cm -1 Peak area]]> Epoxy content (mol / g) <![CDATA[1250cm -1 Peak area]]> Example 1 0.65 120 0.072 255 Example 2 0.72 245 0.068 170 Example 3 0.80 368 0.054 85

[0149] As shown in Table 1, the vinyl content of epoxidized vinyl silicone rubber is 60%-80% and the epoxy content is 5-8%. The high vinyl content in epoxidized vinyl silicone rubber inhibits backbone degradation, forming a dense crosslinked network and increasing carbon residue. The epoxy groups enhance adhesion to the metal shell. Carbon fiber (CF) and aramid fiber (AF) serve as reinforcing fibers, creating a skeletal support structure and improving carbon layer density and erosion resistance.

[0150] Table 2 shows the properties of the prepared flexible ablative material. The specific test methods are as follows:

[0151] Linear Ablation Rate Test Method (GJB 323B-2018): An oxyacetylene flame or plasma jet is directed vertically onto the specimen to ablate or burn through the material. The back surface temperature and ablation time of the specimen are measured during the ablation process. The thickness and mass changes of the specimen before and after the test are measured to calculate the linear ablation rate, mass ablation rate, and adiabatic index of the specimen.

[0152] Test method for residual carbon rate (GB / T8727-2008): The sample is heated at high temperature in an inert gas (nitrogen) until it is completely cracked (900°C). The percentage of the remaining carbon residue mass to the original sample is the residual carbon rate.

[0153] Dripping test method: The time it takes for organic matter to first drop during the combustion process (850°C).

[0154] Tear strength test method: Use a dumbbell-shaped or trouser-shaped specimen and stretch it uniformly through a tensile testing machine until the specimen is completely torn (stretching rate 500±50mm / min, specimen thickness <2mm), and record the maximum tearing force.

[0155] Test method for tensile strength after aging: reference standards are GB / T 2951 and JB / T10696.

[0156] Test method for elongation at break after aging: reference standards are GB / T 2951 and JB / T10696.

[0157] Table 2 Properties of flexible ablative materials

[0158]

[0159] As can be seen from Table 1, Comparative Example 1 (introduction of phenyl ring): phenyl improves thermal stability, but the movement of chain segments is hindered, resulting in a decrease in mechanical properties. Phenyl and methyl have poor compatibility, the material uniformity is reduced, and the ablation rate deteriorates. Comparative Example 2 (phenyl polysiloxane main chain): the phenyl main chain significantly improves thermal stability, but the excessive rigidity leads to deterioration of flexibility. Comparative Example 3 (no fiber reinforcement): the lack of fiber leads to an overall decrease in mechanical properties, and the residual carbon rate is the lowest. Comparative Example 4 (CF fiber only): CF improves tear resistance and residual carbon rate, but lacks the synergistic effect of AF, and the elongation at break is lower than that of Example 1. Comparative Example 5 (AF fiber only): AF improves flexibility, but the high temperature resistance is insufficient.

[0160] In summary, the embodiments of the present invention use multi-dimensional technological innovations. The high vinyl content and epoxy cross-linked network effectively inhibit the degradation of the main chain, and the tear strength far exceeds that of traditional silicone rubber. The CF / AF fibers synergistically form a dense carbon layer, and the resistance to high-temperature airflow erosion ensures a low ablation rate. The direct epoxidation method is easy to industrialize and does not require a complex filler dispersion process. The material can be used not only as a protective material for wires and cables, but also in their cable accessories.

[0161] The above description is merely an optional embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A flexible low ablative material, characterized in that: The invention comprises epoxidized vinyl silicone rubber and fiber; the epoxidized vinyl silicone rubber and the fiber are mixed to form a three-dimensional interpenetrating network structure; The fibers include carbon fibers and aramid fibers; The epoxidized vinyl silicone rubber has a vinyl content of 60%-80% and an epoxy content of 5-8%.

2. The flexible low ablative material according to claim 1, characterized in that: The mass ratio of the epoxidized vinyl silicone rubber to the fiber is (5-15): (1-3); Alternatively, the epoxidized vinyl silicone rubber is composed of the following components, calculated by mass: 800-1200 parts of octamethylcyclotetrasiloxane, 3-6 parts of a catalyst, and 10-20 parts of a vinyl end-capping agent.

3. The flexible ablative material according to claim 2, characterized in that: The catalyst is one of potassium hydroxide, lithium hydroxide, tetramethylammonium hydroxide and tetraethylphosphonium hydroxide; The vinyl end-capping agent is one of vinyldimethylchlorosilane and vinyl-terminated phenyl polysiloxane.

4. The flexible low ablative material according to claim 1, characterized in that: The fibers are made of a mixture of carbon fibers and aramid fibers; The mixing mass ratio of the carbon fiber and the aramid fiber is (2-4): (1-3).

5. A method for preparing the flexible low-ablation material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Under a nitrogen atmosphere, octamethylcyclotetrasiloxane and a catalyst are mixed to react, and then a vinyl end-capping agent is added dropwise to continue the reaction. After the reaction is completed, water is added to terminate the reaction to obtain epoxidized vinyl silicone rubber. The flexible low-ablative material is obtained by mixing epoxidized vinyl silicone rubber with fibers and then hot pressing.

6. The method for preparing the flexible low ablative material according to claim 5, characterized in that: In the synthesis method of the epoxidized vinyl silicone rubber, the reaction temperature is 85-95° C. and the reaction time is 3-5 hours; The temperature for adding the vinyl blocking agent dropwise is 55-65° C. and the adding time is 20-40 min; The reaction time is 1.5-2.5 hours.

7. The method for preparing the flexible low ablative material according to claim 5, characterized in that: In the synthesis method of the epoxidized vinyl silicone rubber, after the termination reaction, the method further comprises continuing stirring, vacuum distillation and filtration; the stirring time is 20-40 minutes, the vacuum distillation temperature is 115-125° C., and the pressure is -0.09 to -0.08 MPa.

8. The method for preparing the flexible low ablative material according to claim 5, characterized in that: The mass ratio of the epoxidized vinyl silicone rubber to the fiber is (5-15): (1-3); The fibers are formed by mixing carbon fibers and aramid fibers in a mass ratio of (2-4): (1-3); The temperature of the hot pressing is 120-160° C., and the time is 3-10 minutes.

9. Use of the flexible low-ablative material according to any one of claims 1 to 4 in wires and cables.

10. A wire and cable, characterized in that: The flexible low-ablative material according to any one of claims 1 to 4 is used.

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