Hybrid polyphosphazene and preparation method and application thereof, modified ethylene propylene diene monomer material and preparation method and application thereof

Abstract

The invention belongs to the technical field of thermal protection materials for spaceflight and weapons, and particularly relates to hybrid polyphosphazene and a preparation method and application thereof, and a modified ethylene propylene diene monomer material and a preparation method and application thereof. The hybrid polyphosphazene provided by the invention comprises acetenyl aniline polyphosphazene with a structure as shown in a formula 1, naphthylamine polyphosphazene with a structure as shown in a formula 2 or allyl phenoxy polyphosphazene with a structure as shown in a formula 3. The hybrid polyphosphazene provided by the invention is used as a modifier, and a functional group and a phosphorus-nitrogen long chain of the hybrid polyphosphazene can be co-crosslinked with EPDM to construct an interpenetrating network structure so as to improve the mechanical property and ablation resistance of an EPDM heat insulating layer. According to the modified ethylene propylene diene monomer material provided by the invention, the mechanical property, the elasticity and the ablation resistance of the material are remarkably improved on the premise of keeping the density basically unchanged, and the modified ethylene propylene diene monomer material can be widely applied as a heat insulating layer.

Description

Technical Field

[0001] This invention belongs to the field of aerospace and weaponry thermal protection materials technology, specifically involving hybrid polyphosphazene and its preparation method and application, and modified EPDM rubber materials and their preparation method and application. Background Technology

[0002] The thermal insulation layer is a thermal protection material of a certain thickness located between the solid rocket engine casing and the propellant. Its main function is to protect the engineering structure from being burned or damaged when the engine is working, and to ensure that its external structure or internal devices are within a given temperature range, so as to prevent the combustion chamber casing from reducing its shell strength due to overheating and endangering the structural integrity.

[0003] Ethylene propylene diene monomer (EPDM) rubber has a low density (~0.86 g / cm³). 3 With the lowest carbon content among all rubbers, high filler coefficient, and easy processing properties, EPDM is one of the most widely used insulation matrix materials. However, EPDM contains a large number of CH bonds, resulting in a relatively large average ablation weight loss at high temperatures and an insufficiently dense carbonized layer. Therefore, when EPDM is used as an insulation layer, it is necessary to add inorganic fillers, fibers, and other components to improve its strength and ablation resistance.

[0004] Generally speaking, inorganic (organic) fillers such as wollastonite, ceramic fillers, inorganic (organic) fibers, and novel nanofillers (such as carbon nanotubes) possess high-temperature resistance properties, which can improve material strength while reducing the ablation rate. However, while conventional reinforcement methods can improve the ablation resistance of materials, they can affect the material's density and mechanical properties.

[0005] Polyphosphazene is an organic-inorganic hybrid polymer whose main chain consists of alternating single and double bonds of phosphorus and nitrogen atoms, with side chains replaced by organic groups. Due to its molecular structure and the flexibility of its main chain, linear polyphosphazene possesses high-temperature resistance, high-efficiency flame retardancy, and mechanical reinforcement. Currently, some linear polyphosphazene elastomers, such as poly(aryloxyphosphazene) and fluorinated linear polyphosphazene, have been found to exhibit excellent elasticity and flame retardancy; however, their relatively simple structure and high cost limit their applications to some extent. Summary of the Invention

[0006] The purpose of this invention is to provide hybrid polyphosphazene and its preparation method and application, and modified EPDM rubber material and its preparation method and application. The modified EPDM rubber material obtained by using hybrid polyphosphazene as a modifier provided by this invention significantly improves the mechanical properties (elongation at break), elasticity and ablation resistance of the material while maintaining the density basically unchanged, and can be widely used as a heat insulation layer.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] This invention provides a class of hybrid polyphosphazenes, including ethynylaniline polyphosphazenes with the structure shown in Formula 1, naphthylamine polyphosphazenes with the structure shown in Formula 2, or allylphenoxy polyphosphazenes with the structure shown in Formula 3; wherein the degree of polymerization n of the hybrid polyphosphazenes is 100 to 150.

[0009]

[0010] This invention provides a method for preparing the hybrid polyphosphononitrile described above, comprising the following steps:

[0011] Hexachlorocyclotriphosphazene, solid acid, calcium sulfate and organic solvent are mixed and heated in a protective gas environment to carry out the first reaction, yielding intermediate product A;

[0012] When the hybrid polyphosphazene includes acetylenyl aniline polyphosphazene with the structure shown in Formula 1 or naphthylamine polyphosphazene with the structure shown in Formula 2, the intermediate product A, organic solvent and organic amine raw material are mixed, heated in a protective gas, and then an acid-binding agent is added to carry out a second reaction. The organic amine raw material includes 3-acetylenyl aniline or 1-naphthylamine, respectively, to obtain acetylenyl aniline polyphosphazene with the structure shown in Formula 1 or naphthylamine polyphosphazene with the structure shown in Formula 2.

[0013] When the hybrid polyphosphazene is an allylphenoxy polyphosphazene with the structure shown in Formula 3, the sodium hydride, 2-allylphenol and solvent are mixed and a third reaction is carried out in a protective gas to obtain a third reaction solution B; the third reaction solution B, intermediate product A and organic solvent are mixed and a fourth reaction is carried out to obtain an allylphenoxy polyphosphazene with the structure shown in Formula 3.

[0014] Preferably, the solid acid includes one or more of succinic anhydride, phosphoric acid, and aminosulfonic acid; the acid-binding agent includes one or more of pyridine, triethylamine, diisopropylethylamine, potassium carbonate, and sodium hydroxide; the molar ratio of hexachlorocyclotriphosphazene, solid acid, and calcium sulfate is 1:(0.00358-0.358):(0.04038-0.4038); the molar ratio of hexachlorocyclotriphosphazene, organic amine raw material, and acid-binding agent is 1:1-6:6-12; and the molar ratio of hexachlorocyclotriphosphazene, 2-allylphenol, and sodium hydride is 1:1-6:6-12.

[0015] Preferably, the temperature of the first reaction is 190–230°C and the time is 5–7 h; the temperature of the second reaction is 50–70°C and the time is 12–24 h; the time of the third reaction is 10–60 min; and the temperature of the fourth reaction is 50–70°C and the time is 12–24 h.

[0016] This invention provides the application of the hybrid polyphosphazene described in the above technical solution or the hybrid polyphosphazene prepared by the preparation method described in the above technical solution in modified EPDM rubber materials.

[0017] This invention provides a modified EPDM rubber material, comprising the following raw materials in parts by weight: 100 parts EPDM rubber, 3-10 parts nano-metal oxide, 10-15 parts fumed silica, 10-15 parts organic chopped fibers, 10-15 parts modifier, 1-5 parts sulfur, and 0.5-6 parts peroxide crosslinking agent; the organic chopped fibers have a length of 3-6 mm; the modifier is the hybrid polyphosphazene described in the above technical solution or the hybrid polyphosphazene prepared by the preparation method described in the above technical solution.

[0018] Preferably, the third monomer of the EPDM rubber is ethylene-imide norbornene, dicyclopentadiene, or 1,4-hexadiene, and the content of ethylene monomer in the EPDM rubber is 54-55%.

[0019] Preferably, the nano-metal oxide comprises zinc oxide and / or magnesium oxide, and the average particle size of the nano-metal oxide is 50-100 nm;

[0020] The specific surface area of ​​the fumed silica is 150-200 m² / g;

[0021] The organic chopped fibers include one or more of aramid fibers, polyimide fibers, and poly(p-phenylenebenzobisoxazole) fibers;

[0022] The peroxide crosslinking agent includes one or more of dicumyl peroxide (DCP), 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (DBPMH), and 1,4-bis-tert-butylperoxyisopropylbenzene (BIPB).

[0023] This invention provides a method for preparing the modified EPDM rubber material described in the above technical solution, comprising the following steps:

[0024] The raw materials for preparing the modified EPDM rubber material are mixed to obtain a rubber compound;

[0025] The rubber compound is vulcanized to obtain a modified EPDM rubber material.

[0026] This invention provides the application of the modified EPDM rubber material described in the above technical solution or the modified EPDM rubber material prepared by the preparation method described in the above technical solution in the ablation-resistant heat insulation layer.

[0027] This invention provides a class of hybrid polyphosphazenes, including ethynylaniline polyphosphazenes with the structure shown in Formula 1, naphthylamine polyphosphazenes with the structure shown in Formula 2, or allylphenoxy polyphosphazenes with the structure shown in Formula 3; the degree of polymerization n of the hybrid polyphosphazenes is 100-150. Figure 5 The schematic diagram shows that the hybrid polyphosphazene provided by this invention utilizes acetylene aniline (C≡C-C6H4-NH-) and naphthylamine (C 10 Modification with functional groups such as H7-NH- or allylphenoxy (-O-C6H4-CH2CH=CH2) imparts both chemical reactivity and thermal stability. Specifically: double and triple bonds provide sulfur crosslinking sites (participating in the EPDM sulfurization system); aromatic rings enhance π-π stacking (increasing the graphitization degree of the carbon layer); ethynylaniline and allylphenoxy groups provide both sulfur crosslinking sites and enhance π-π stacking, while also providing an ordered carbon structure (promoting graphitic carbon formation); the phosphorus and nitrogen backbone promotes the formation of the phosphate glass phase (increasing char yield). The Ph-NPs in ethynylaniline-based polyphosphononitriles and the NA-NPs in aniline-based polyphosphononitriles both possess strong polarity. Furthermore, the Ph-OPs in allylphenoxy-based polyphosphononitriles can form hydrogen bonds and other adsorption interactions with the hydroxyl groups on the SiO2 surface, covering the SiO2 surface and significantly reducing its surface energy. This reduces the exposed hydroxyl groups on the SiO2 surface, thereby suppressing the self-aggregation tendency of SiO2 and improving its dispersibility in EPDM materials. The hybrid polyphosphononitriles provided in this invention, as a modifier, possess functional groups and long phosphorus and nitrogen chains that can co-crosslink with EPDM to construct an interpenetrating network structure, thereby improving the mechanical properties and ablation resistance of the EPDM insulation layer.

[0028] This invention provides a modified EPDM rubber material, comprising the following raw materials in parts by weight: 100 parts EPDM rubber, 3-10 parts nano-metal oxide, 10-15 parts fumed silica, 10-15 parts organic chopped fibers, 10-15 parts modifier, 1-5 parts sulfur, and 0.5-6 parts peroxide crosslinking agent; the organic chopped fibers have a length of 3-6 mm; the modifier is the hybrid polyphosphazene described in the above technical solution or the hybrid polyphosphazene prepared by the preparation method described in the above technical solution. The modified EPDM rubber material provided by this invention uses EPDM as the matrix, fumed silica and modifiers as reinforcing phases, and organic chopped fibers as supplementary reinforcing phases. During vulcanization, the functional groups of the ethynylaminopolyphosphazene and allylphenoxypolyphosphazene modifiers undergo a grafting reaction with the double bonds of EPDM, forming a cross-linked three-dimensional interpenetrating network. Naphthylaminopolyphosphazene acts as a plasticizer in the EPDM composite material, improving the mechanical properties (including tensile strength) of the rubber material. Simultaneously, the phosphorus-nitrogen skeleton of the modifier promotes the formation of a glassy carbon layer (thickness > 2 mm) containing PO-Si bonds during high-temperature ablation, resulting in a linear ablation rate of the rubber material < 0.06 mm / s. Furthermore, this invention utilizes organic chopped fibers and fumed silica to jointly form a secondary reinforcing network. In summary, by optimizing the raw materials and mass ratios in the preparation of the modified EPDM rubber material, this invention significantly improves the mechanical properties (elongation at break), elasticity, and ablation resistance of the material while maintaining a relatively constant density, making it widely applicable as a thermal insulation layer. As can be seen from the results of the embodiments, the modified EPDM rubber material provided by the present invention can achieve an elongation at break of 918.94%, while reducing the linear ablation rate by 60.75% and the mass ablation rate by 6.41%. Attached Figure Description

[0029] Figure 1 A synthetic route diagram for acetylene-aniline-based polyphosphazene provided by the present invention;

[0030] Figure 2 A synthetic route diagram for naphthylamine polyphosphazene provided by the present invention;

[0031] Figure 3 The synthetic route diagram of allylphenoxy polyphosphazene provided by the present invention;

[0032] Figure 4 A preparation route diagram for the modified EPDM rubber material provided by this invention;

[0033] Figure 5 This is a schematic diagram illustrating the performance principle of the modified EPDM rubber material of this invention.

[0034] Figure 6 The tensile strength and elongation at break of the application examples 1 to 3 of this invention and the control samples are test results.

[0035] Figure 7 The results are the test results of linear ablation rate and mass ablation rate of application examples 1 to 3 of this invention and control samples. Detailed Implementation

[0036] This invention provides a class of hybrid polyphosphazenes, including ethynylaniline polyphosphazenes with the structure shown in Formula 1, naphthylamine polyphosphazenes with the structure shown in Formula 2, or allylphenoxy polyphosphazenes with the structure shown in Formula 3.

[0037]

[0038] This invention provides a method for preparing the hybrid polyphosphononitrile described above, comprising the following steps:

[0039] Hexachlorocyclotriphosphazene, solid acid, calcium sulfate and organic solvent are mixed and heated in a protective gas environment to carry out the first reaction, yielding intermediate product A;

[0040] When the hybrid polyphosphazene includes acetylenyl aniline polyphosphazene with the structure shown in Formula 1 or naphthylamine polyphosphazene with the structure shown in Formula 2, the intermediate product A, organic solvent and organic amine raw material are mixed, heated to 50-70°C in a protective gas, and then an acid-binding agent is added to carry out a second reaction. The organic amine raw material includes 3-acetylenyl aniline or 1-naphthylamine, respectively, to obtain acetylenyl aniline polyphosphazene with the structure shown in Formula 1 or naphthylamine polyphosphazene with the structure shown in Formula 2.

[0041] When the hybrid polyphosphazene is an allylphenoxy polyphosphazene with the structure shown in Formula 3, the sodium hydride, 2-allylphenol and solvent are mixed and a third reaction is carried out in a protective gas to obtain a third reaction solution B; the third reaction solution B, intermediate product A and organic solvent are mixed and a fourth reaction is carried out to obtain the allylphenoxy polyphosphazene.

[0042] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0043] This invention involves mixing hexachlorocyclotriphosphazene, a solid acid, calcium sulfate, and an organic solvent, and carrying out a first reaction under a protective gas atmosphere to obtain intermediate product A. In this invention, the solid acid preferably includes one or more of succinic anhydride, phosphoric acid, and aminosulfonic acid. The calcium sulfate is preferably used in the form of calcium sulfate dihydrate. The molar ratio of hexachlorocyclotriphosphazene, the solid acid, and the calcium sulfate is preferably 1:(0.00358–0.358):(0.04038–0.4038), and in the examples, it can be 1:0.00358:0.04038. In this invention, the organic solvent is preferably 1,2,4-trichlorobenzene. This invention does not have special requirements on the amount of organic solvent used, as long as the first reaction proceeds smoothly. The protective gas is preferably nitrogen or argon. The temperature of the first reaction is preferably 190–230°C, and the time is preferably 5–7 hours. After the first reaction is completed, a first reaction solution is obtained directly. This invention preferably washes the first reaction solution with petroleum ether to remove the organic solvent used in the first reaction.

[0044] In this invention, when the hybrid polyphosphazene includes acetylenylaniline-based polyphosphazene or naphthylamine-based polyphosphazene, the intermediate product A, organic solvent, and organic amine raw material are mixed, heated in a protective gas atmosphere, and then an acid-binding agent is added to carry out a second reaction. The organic amine raw material includes 3-acetylenylaniline or naphthylamine, respectively, to obtain acetylenylaniline-based polyphosphazene or naphthylamine-based polyphosphazene. In this invention, the organic solvent preferably includes one or more of tetrahydrofuran, acetone, dichloromethane, and N,N-dimethylformamide (DMF). The protective gas is preferably nitrogen or argon. The acid-binding agent preferably includes one or more of pyridine, triethylamine, diisopropylethylamine, potassium carbonate, and sodium hydroxide. The molar ratio of hexachlorocyclotriphosphazene, organic amine raw material, and acid-binding agent is preferably 1:1 to 6:6 to 12. The acid-binding agent is preferably added dropwise. The acid-binding agent is preferably added dropwise in the form of an acid-binding agent solution. The temperature of the second reaction is preferably 50 to 70°C, and the time is preferably 12 to 24 hours. After the second reaction is completed, a second reaction solution is obtained directly. Preferably, the salt and organic solvent are removed from the second reaction solution to obtain the acetylene-aniline-based polyphosphazene or naphthylamine-based polyphosphazene.

[0045] In this invention, when the hybrid polyphosphazene is allylphenoxy polyphosphazene, the sodium hydride, 2-allylphenol, and solvent are mixed, and a third reaction is carried out under a protective gas to obtain a third reaction solution; the third reaction solution, intermediate product, and organic solvent are mixed to carry out a fourth reaction to obtain the allylphenoxy polyphosphazene. In this invention, the molar ratio of hexachlorocyclotriphosphazene, 2-allylphenol, and sodium hydride is preferably 1:1 to 6:6 to 12. The solvent preferably includes one or more of tetrahydrofuran, acetone, dichloromethane, and N,N-dimethylformamide (DMF). The temperature of the third reaction is preferably room temperature (20 to 35°C), and the time of the third reaction is preferably 10 to 60 minutes. In the fourth reaction, the intermediate product is preferably in the form of a tetrahydrofuran solution of the intermediate product. The temperature of the fourth reaction is preferably room temperature, and the time of the fourth reaction is 12 to 24 hours. After the fourth reaction is completed, the fourth reaction solution is obtained directly. Preferably, the salt and organic solvent are removed from the fourth reaction solution to obtain the allylphenoxy polyphosphazene.

[0046] This invention provides the application of the hybrid polyphosphazene described in the above technical solution or the hybrid polyphosphazene prepared by the preparation method described in the above technical solution in modified EPDM rubber materials.

[0047] This invention provides a modified EPDM rubber material, comprising the following raw materials in parts by weight: 100 parts EPDM rubber, 3-10 parts nano-metal oxide, 10-15 parts fumed silica, 10-15 parts organic chopped fibers, 10-15 parts modifier, 1-5 parts sulfur, and 0.5-6 parts peroxide crosslinking agent; the organic chopped fibers have a length of 3-6 mm; the modifier is the hybrid polyphosphazene described in the above technical solution or the hybrid polyphosphazene prepared by the preparation method described in the above technical solution.

[0048] The method for preparing the modified EPDM rubber material provided by the present invention, by weight, includes 100 parts of EPDM rubber. In the present invention, the third monomer of the EPDM rubber is preferably ethylene-imide norbornene, dicyclopentadiene, or 1,4-hexadiene, and the content of ethylene monomer in the EPDM rubber is preferably 54-55%, which can be 54.16% in the examples.

[0049] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 3 to 10 parts of nano-metal oxide, which in the examples can be 3, 4, 5, 6.6, 7, 9, or 10 parts. In the present invention, the nano-metal oxide preferably includes zinc oxide and / or magnesium oxide. The average particle size of the nano-metal oxide is preferably 50 to 100 nm.

[0050] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 10-15 parts of fumed silica, which in the examples can be 10 parts, 11 parts, 11.67 parts, 13 parts, 13.33 parts, or 15 parts. In the present invention, the specific surface area of ​​the fumed silica is preferably 150-200 m² / s. 2 / g.

[0051] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 10-15 parts of organic chopped fibers, which in the examples can be 10 parts, 11.67 parts, 13 parts, or 15 parts. In the present invention, the organic chopped fibers preferably include one or more of aramid fibers, polyimide fibers, and poly(p-phenylenebenzobisoxazole) fibers. The length of the organic chopped fibers is preferably 3-6 mm.

[0052] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 10 to 15 parts of modifier, which can be 10 parts, 11.6 parts, 13 parts or 15 parts in the examples.

[0053] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 1 to 5 parts of sulfur, which can be 1 part, 3 parts, 3.33 parts, 3.5 parts, 4 parts or 5 parts in the examples.

[0054] Based on the mass fraction of the EPDM rubber, the preparation method of the modified EPDM rubber material provided by the present invention includes 0.5 to 6 parts of a peroxide crosslinking agent, which can be 0.5, 0.8, 2, 3, 3.5, 4, 4.5, 5, 5.5, or 6 parts in the examples. In the present invention, the peroxide crosslinking agent preferably includes one or more of DCP, DBPMH, and BIPB.

[0055] This invention provides a method for preparing the modified EPDM rubber material described in the above technical solution, comprising the following steps:

[0056] The raw materials for preparing the modified EPDM rubber material are mixed to obtain a rubber compound;

[0057] The rubber compound is vulcanized to obtain a modified EPDM rubber material.

[0058] This invention involves mixing the raw materials for preparing the modified EPDM rubber material to obtain a rubber compound. Preferably, the mixing is performed in a Banbury mixer. The mixing speed is preferably 40-50 r / min. The mixing process preferably includes sequentially adding the EPDM rubber, nano-metal oxides, fumed silica, organic chopped fibers, modifier, sulfur, and peroxide crosslinking agent to the Banbury mixer for mixing. Each raw material is preferably mixed for 1-2 minutes after addition before adding another raw material. After mixing, an initial rubber compound is obtained. Preferably, this invention further includes placing the initial rubber compound in a two-roll mill for sequential plasticizing, uniform rolling, two-roll milling, and pressing to obtain the final rubber compound.

[0059] After obtaining the rubber compound, the present invention vulcanizes the rubber compound to obtain a modified EPDM rubber material. In the present invention, the vulcanization is preferably carried out in a vulcanizing machine. The vulcanization temperature is preferably 170-175°C, the pressure is preferably 10-15 MPa, and the time is preferably 0.5-1.5 h.

[0060] This invention provides the application of the modified EPDM rubber material described in the above technical solution or the modified EPDM rubber material prepared by the preparation method described in the above technical solution in the ablation-resistant heat insulation layer.

[0061] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0062] In Example 1 below, acetylene-based aniline-based polyphosphazene is prepared according to... Figure 1 The synthetic route shown is used to synthesize naphthylamine polyphosphazene according to... Figure 2 The synthetic route shown is used to synthesize allylphenoxy polyphosphazene according to... Figure 3 The synthesis route shown is used for synthesis.

[0063] The following application examples are based on Figure 4 The synthetic route was used to prepare modified EPDM rubber materials.

[0064] Example 1

[0065] This embodiment provides a method for preparing acetylene-based aniline-based polyphosphazene (AYP), as detailed below:

[0066] (1) 0.04314 mol hexachlorocyclotriphosphazene, 0.0001545 mol aminosulfonic acid, and 0.001742 mol calcium sulfate dihydrate were added to 15 mL of 1,2,4-trichlorobenzene, and the mixture was heated to 220 °C for 5 h under a nitrogen atmosphere. After the reaction was complete, the product was removed and added to petroleum ether. The solvent was washed away by pouring the petroleum ether into the reaction flask. Finally, tetrahydrofuran was added to obtain a tetrahydrofuran solution for later use.

[0067] (2) Add 0.25884 mol of 3-ethynylaniline to the tetrahydrofuran solution prepared in step (1), and add 0.25884 mol of acid-binding agent (potassium carbonate) dropwise under a nitrogen atmosphere to 70 °C. React for 24 h. After the reaction is complete, remove the salt and solvent to obtain ethynylaniline-based polyphosphazene.

[0068] This embodiment provides a method for preparing naphthylamine-based polyphosphazene (NLP), which is basically the same as the method for preparing acetylenylaniline-based polyphosphazene, except that acetylenylaniline is replaced with 1-naphthylamine.

[0069] This embodiment provides a method for preparing allylphenoxy polyphosphazene (hereinafter referred to as APP), as follows:

[0070] (1) 0.04314 mol hexachlorocyclotriphosphazene, 0.0001545 mol aminosulfonic acid, and 0.001742 mol calcium sulfate dihydrate were added to 1,2,4-trichlorobenzene, and the mixture was heated to 220 °C for 3 hours under an inert atmosphere. After the reaction was complete, the product was removed and petroleum ether was added to wash away the 1,2,4-trichlorobenzene. Finally, tetrahydrofuran was added to obtain a linear tetrahydrofuran solution of polyphosphazene for later use.

[0071] (2) 0.25884 mol sodium hydride, 0.25884 mol 2-allylphenol and tetrahydrofuran were reacted at room temperature under a nitrogen atmosphere for 60 min. The tetrahydrofuran solution prepared in step (1) was then added and reacted at 70 °C for 24 h. After the reaction was completed, the salt and solvent were removed to obtain allylphenoxy polyphosphazene.

[0072] Application Example 1:

[0073] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps:

[0074] Weigh out 30g of EPDM rubber, 1.5g of nano zinc oxide, 4.5g of fumed silica, 3g of aramid fiber with a length of 6mm, 3g of ethynyl aniline polyphosphazene prepared in Example 1, 1g of sulfur, and 1.05g of crosslinking agent DCP.

[0075] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano zinc oxide, fumed silica, 6 mm aramid fiber, acetylenyl aniline polyphosphazene, sulfur and crosslinking agent DCP in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0076] The mixed rubber compound is placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 175℃ and a pressure of 10MPa for 0.5h. After cooling, the modified EPDM rubber material (denoted as EP-AYP) is obtained.

[0077] Application Example 2:

[0078] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps: weighing 30g of EPDM rubber, 1.5g of nano zinc oxide, 4.5g of fumed silica, 3g of aramid fiber with a length of 6mm, 3g of naphthylamine polyphosphazene prepared in Example 1, 1g of sulfur, and 1.05g of crosslinking agent DCP.

[0079] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano zinc oxide, fumed silica, 6mm aramid fiber, naphthylamine polyphosphazene, sulfur and crosslinking agent DCP in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0080] The mixed rubber compound is placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 175℃ and a pressure of 10MPa for 0.5h. After cooling, the modified EPDM rubber material (denoted as EP-NLP) is obtained.

[0081] Application Example 3:

[0082] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps:

[0083] Weigh out 30g of EPDM rubber, 1.5g of nano zinc oxide, 4.5g of fumed silica, 3g of aramid fiber with a length of 6mm, 3g of allyl phenoxy polyphosphazene prepared in Example 1, 1g of sulfur, and 1.05g of crosslinking agent DCP.

[0084] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano zinc oxide, fumed silica, 6 mm aramid fiber, allyl phenoxy polyphosphazene, sulfur and crosslinking agent DCP in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, wrap it evenly around the rollers, start milling, adjust the roller gap and compress the thickness.

[0085] The mixed rubber compound is placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 175℃ and a pressure of 10MPa for 0.5h. After cooling, the modified EPDM rubber material (denoted as EP-APP) is obtained.

[0086] Application Example 4:

[0087] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps:

[0088] Weigh out 30g of EPDM rubber, 1.98g of nano magnesium oxide, 4.5g of fumed silica, 3.9g of aramid fiber with a length of 3mm, 3g of allyl phenoxy polyphosphazene prepared in Example 1, 1.2g of sulfur, and 1.5g of crosslinking agent DBPMH.

[0089] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano magnesium oxide, fumed silica, 3 mm aramid fiber, allyl phenoxy polyphosphazene, sulfur and crosslinking agent DBPMH in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0090] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 170℃ and a pressure of 15MPa for 1.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0091] Application Example 5:

[0092] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps: weighing 30g of EPDM rubber, 1.5g of nano-magnesium oxide, 3.9g of fumed silica, 4.5g of aramid fiber with a length of 6mm, 4.5g of acetylenyl aniline polyphosphazene prepared in Example 1, 1.2g of sulfur, and 1.5g of crosslinking agent DCP.

[0093] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano magnesium oxide, fumed silica, 6 mm aramid fiber, acetylenyl aniline polyphosphazene, sulfur and crosslinking agent DCP in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0094] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 175℃ and a pressure of 10MPa for 1.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0095] Application Example 6:

[0096] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps:

[0097] Weigh out 30g of EPDM rubber, 3g of nano magnesium oxide, 3g of fumed silica, 3g of polyimide fiber with a length of 3mm, 3g of ethynyl aniline polyphosphazene prepared in Example 1, 1.5g of sulfur, and 1.5g of crosslinking agent BIPB.

[0098] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano magnesium oxide, fumed silica, 3 mm polyimide fiber, ethynyl aniline polyphosphazene, sulfur and crosslinking agent BIPB in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0099] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 170℃ and a pressure of 10MPa for 0.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0100] Application Example 7:

[0101] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps: weighing 30g of EPDM rubber, 1.98g of nano zinc oxide, 3g of fumed silica, 3g of 6mm long poly(p-phenylenebenzobisoxazole) fiber, 3.48g of naphthylamine polyphosphazene prepared in Example 1, 1.5g of sulfur, and 0.24g of crosslinking agent DBPMH.

[0102] Set the speed to 40 r / min in the internal mixer, and add EPDM rubber, nano zinc oxide, fumed silica, 6mm poly(p-phenylene benzobisoxazole) fiber, naphthylamine polyphosphazene, sulfur and crosslinking agent DBPMH in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0103] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 170℃ and a pressure of 15MPa for 0.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0104] Application Example 8:

[0105] This application example provides a method for preparing a modified EPDM rubber material, specifically including the following steps:

[0106] Weigh out 30g of EPDM rubber, 3g of nano zinc oxide, 3g of fumed silica, 3g of 3mm long poly(p-phenylenebenzobisoxazole) fiber, 4.5g of allylphenoxy polyphosphazene prepared in Example 1, 0.9g of sulfur, and 1.5g of crosslinking agent DBPMH.

[0107] Set the speed to 40 r / min in the internal mixer, and add EPDM rubber, nano zinc oxide, fumed silica, 3mm poly(p-phenylenebenzobisoxazole) fiber, allyl phenoxy polyphosphazene, sulfur and crosslinking agent DBPMH in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, uniformly wrapping the rollers, starting the mill, adjusting the roller gap, and pressing the thickness.

[0108] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 170℃ and a pressure of 15MPa for 1.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0109] Test example: The preparation of the control sample specifically includes the following steps:

[0110] Weigh out 30g of EPDM rubber, 1.5g of nano zinc oxide, 4.5g of fumed silica, 3g of aramid fiber with a length of 6mm, 1g of sulfur, and 1.05g of crosslinking agent DBPMH.

[0111] Set the speed in the internal mixer to 40 r / min, and add EPDM rubber, nano zinc oxide, fumed silica, 3mm aramid fiber sulfur and crosslinking agent DCP in sequence. Mix each raw material for 1-2 minutes after adding it before adding the next raw material. Put the mixed material into a two-roll mill for room temperature plasticizing, wrap it evenly around the rollers, start milling, adjust the roller gap, and press it to the desired thickness.

[0112] The prepared rubber compound was placed in a flat vulcanizing machine and vulcanized at a vulcanization temperature of 175℃ and a pressure of 10MPa for 0.5 hours. After cooling, the modified EPDM rubber material was obtained.

[0113] Table 1 shows the performance test results of the above-mentioned embodiments and comparative samples. The tensile strength and elongation at break of EPDM rubber were tested using a tensile testing machine. The specimens were cut into dumbbell shapes according to GB / T528-2009 national standard and GB / T2941. The time interval between cutting and curing of the specimens was more than 12 hours, and the interval between cutting and the tensile test specimens was more than 12 hours. The narrow portion of the dumbbell-shaped specimen had a length of 33±2.0 mm, a width of 6.0±0.4 mm, a thickness of 2.0±0.2 mm, and a gauge length of 25.0±0.5 mm. During the test, the clamping speed was 500 mm / min±50 mm / min, and the number of specimens in the same group was no less than five.

[0114] This experiment was conducted according to the GJB323A-96 standard. An oxyacetylene flame ablation method was used to test the ablation resistance of samples with a diameter of 30 mm and a thickness of 10 mm. The ablation time for the EPDM rubber system was 20 s. Changes in thickness and mass before and after ablation were recorded, and the linear ablation rate (LAR) and mass ablation rate (MAR) were calculated. Five samples were used in each group, and the average value was taken.

[0115] Table 1 shows the mechanical properties and ablation properties of the modified EPDM rubber materials prepared in the application examples of this invention.

[0116]

[0117] Figure 6 The tensile strength and elongation at break of the application examples 1 to 3 of this invention and the control samples are test results. Figure 7 The results show the linear ablation rate and mass ablation rate of application examples 1-3 and the control sample of this invention. As can be seen from the above examples, the hybrid polyphosphazene provided by this invention includes acetylenylaniline polyphosphazene with the structure shown in Formula 1, naphthylamine polyphosphazene with the structure shown in Formula 2, or allylphenoxy polyphosphazene with the structure shown in Formula 3. The hybrid polyphosphazene provided by this invention can improve the mechanical properties of EPDM insulation layers and replace some traditional fillers. Simultaneously, the reactive hybrid polyphosphazene can undergo crosslinking reactions with EPDM, introducing the phosphorus-nitrogen backbone and hybrid functional groups into the crosslinking network structure of EPDM, significantly improving the strength, elasticity, and ablation resistance of the EPDM insulation layer.

[0118] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A class of hybrid polyphosphazenes, characterized in that, The hybrid polyphosphazene includes acetylenyl aniline polyphosphazene with the structure shown in Formula 1, naphthylamine polyphosphazene with the structure shown in Formula 2, or allylphenoxy polyphosphazene with the structure shown in Formula 3; the degree of polymerization n of the hybrid polyphosphazene is 100 to 150.

2. The method for preparing the hybrid polyphosphononitrile according to claim 1, characterized in that, Includes the following steps: Hexachlorocyclotriphosphazene, solid acid, calcium sulfate and organic solvent are mixed and heated in a protective gas environment to carry out the first reaction, yielding intermediate product A; When the hybrid polyphosphazene includes acetylenyl aniline polyphosphazene with the structure shown in Formula 1 or naphthylamine polyphosphazene with the structure shown in Formula 2, the intermediate product A, organic solvent and organic amine raw material are mixed, heated in a protective gas, and then an acid-binding agent is added to carry out a second reaction. The organic amine raw material includes 3-acetylenyl aniline or 1-naphthylamine, respectively, to obtain acetylenyl aniline polyphosphazene with the structure shown in Formula 1 and naphthylamine polyphosphazene with the structure shown in Formula 2. When the hybrid polyphosphazene is an allylphenoxy polyphosphazene with the structure shown in Formula 3, the sodium hydride, 2-allylphenol and solvent are mixed and a third reaction is carried out in a protective gas to obtain a third reaction solution B; the third reaction solution B, intermediate product A and organic solvent are mixed and a fourth reaction is carried out to obtain an allylphenoxy polyphosphazene with the structure shown in Formula 3.

3. The preparation method according to claim 2, characterized in that, The solid acid includes one or more of succinic anhydride, phosphoric acid, and aminosulfonic acid; the acid-binding agent includes one or more of pyridine, triethylamine, diisopropylethylamine, potassium carbonate, and sodium hydroxide; the molar ratio of hexachlorocyclotriphosphazene, solid acid, and calcium sulfate is 1:(0.00358~0.358):(0.04038~0.4038); the molar ratio of hexachlorocyclotriphosphazene, organic amine raw material, and acid-binding agent is 1:1~6:6~12; the molar ratio of hexachlorocyclotriphosphazene, 2-allylphenol, and sodium hydride is 1:1~6:6~12.

4. The preparation method according to claim 2, characterized in that, The temperature of the first reaction is 190–230°C and the time is 5–7 h; the temperature of the second reaction is 50–70°C and the time is 12–24 h; the time of the third reaction is 10–60 min; and the temperature of the fourth reaction is 50–70°C and the time is 12–24 h.

5. The application of the hybrid polyphosphazene according to claim 1 or the hybrid polyphosphazene prepared by the preparation method according to any one of claims 2 to 4 in modified EPDM rubber materials.

6. A modified EPDM rubber material, comprising the following raw materials in parts by weight: 100 parts EPDM rubber, 3-10 parts nano-metal oxide, 10-15 parts fumed silica, 10-15 parts organic chopped fibers, 10-15 parts modifier, 1-5 parts sulfur, and 0.5-6 parts peroxide crosslinking agent; wherein the length of the organic chopped fibers is 3-6 mm; and the modifier is the hybrid polyphosphazene according to claim 1 or the hybrid polyphosphazene prepared by the preparation method according to any one of claims 2-4.

7. The modified EPDM rubber material according to claim 6, characterized in that, The third monomer of the EPDM rubber is ethylene-imide norbornene, dicyclopentadiene, or 1,4-hexadiene, and the content of ethylene monomer in the EPDM rubber is 54-55%.

8. The modified EPDM rubber material according to claim 6, characterized in that, The nano-metal oxide includes zinc oxide and / or magnesium oxide, and the average particle size of the nano-metal oxide is 50-100 nm. The specific surface area of ​​the fumed silica is 150–200 m². 2 / g; The organic chopped fibers include one or more of aramid fibers, polyimide fibers, and poly(p-phenylenebenzobisoxazole) fibers; The peroxide crosslinking agent includes one or more of dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and 1,4-di-tert-butylperoxyisopropylbenzene.

9. The method for preparing the modified EPDM rubber material according to any one of claims 6 to 8, characterized in that, Includes the following steps: The raw materials for preparing the modified EPDM rubber material are mixed to obtain a rubber compound; The rubber compound is vulcanized to obtain a modified EPDM rubber material.

10. The application of the modified EPDM rubber material according to any one of claims 6 to 8 or the modified EPDM rubber material prepared by the preparation method according to claim 9 in an ablation-resistant heat insulation layer.

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