Chlorine-containing aryloxy polyphosphazene as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polyphosphazene, and particularly discloses chlorine-containing aryloxy polyphosphazene as well as a preparation method and application thereof. The specific chlorine-containing aryloxy side group capable of catalyzing carbon formation is introduced into the molecular structure of the polyphosphazene, so that the carbonization efficiency of the polyphosphazene material is remarkably improved, a compact carbon layer is formed in a high-temperature environment, and the carbon residue rate is increased; besides, the polar chlorine-containing group can generate interface interaction with a substrate material, so that the interface bonding force is improved, the interface adhesion performance between the substrate and a heat insulation material layer is enhanced, and the layering or falling risk caused by thermal stress is reduced, so that the overall ablation resistance of the substrate is improved, the effectiveness of the substrate in an extreme environment is ensured, and the service life of the substrate is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of polyphosphazenes, and in particular to a chlorine-containing aryloxy polyphosphazene, a preparation method thereof and an application thereof. Background Art

[0002] Flexible thermal insulation materials have important application values in the thermal protection system of the combustion chamber of a solid rocket motor (SRM) due to their excellent ductility, low thermal conductivity and low density. Facing the development of new-generation SRMs operating under high energy, high overload and high pressure conditions, as well as new SRMs with dual-pulse and solid / liquid hybrid power, flexible thermal insulation materials need to meet the performance requirements such as high temperature oxidation resistance, particle erosion resistance and efficient char formation under extreme ablation conditions. At the same time, the inner thermal insulation layer of an SRM is usually bonded to a metal shell or a composite material shell. Under the action of high temperature, high gas flow erosion and thermal stress, if the interfacial bonding performance is insufficient, it may lead to the separation of the thermal insulation layer from the shell, affecting the structural integrity; and after the interfacial failure, the hot gas flow will penetrate into the peeled area, accelerating the ablation of the material and affecting the thermal protection effect. In order to ensure effectiveness in extreme environments, the inner thermal insulation material needs to have high interfacial bonding ability and high thermal-oxidative char yield, and the optimization of these two is crucial for improving the overall heat resistance, ablation resistance and service stability of the engine.

[0003] As one of the earliest polyphosphazene materials, aryloxy polyphosphazene has a series of excellent properties such as heat resistance, flame retardancy, ablation resistance, electrical insulation and solvent resistance due to its special molecular main chain and aryloxy side group structure. Therefore, it can be regarded as an ideal material for the thermal insulation layer of a solid rocket motor. Therefore, developing an aryloxy polyphosphazene with high char yield and high interfacial interaction has important engineering application values.

[0004] Currently, the modification methods of polyphosphazenes mainly focus on: (1) introducing side groups such as ethoxyphenoxy cyclotriphosphazene, fluorinated phenoxy or fluorinated alkoxy groups, which may generate low molecular volatiles during the high-temperature ablation process, affecting the char yield and having limited improvement in the interfacial bonding performance; (2) adding inorganic fillers such as SiO2, Al2O3, inorganic fibers, etc. This method can improve the thermal stability and ablation resistance of the material to a certain extent, but it is easy to affect the flexibility of polyphosphazene and reduce the interfacial bonding property. Therefore, developing an aryloxy polyphosphazene with high char yield and excellent interfacial bonding performance has important values for improving the comprehensive performance of flexible thermal protection materials. Summary of the Invention

[0005] In view of the problems existing in the polyphosphazene materials in the prior art, such as low char residue rate and insufficient interfacial bonding performance, the present invention provides a chloroaryloxy polyphosphazene, a preparation method thereof and an application. By optimizing the molecular structure, the present invention introduces chloroaryloxy side groups on the polyphosphazene main chain, enhances the high-temperature carbonization ability and interfacial bonding performance of the polyphosphazene material, balances the multiple properties of carbon formation effect, flexible mechanics and interfacial bonding force of the polyphosphazene material, and enables it to better meet the flexible thermal protection requirements in various complex environments.

[0006] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0007] In the first aspect, the present invention provides a preparation method of chloroaryloxy polyphosphazene, comprising the following steps:

[0008] S1, prepare polydichlorophosphazene shown in formula (Ⅰ);

[0009]

[0010] S2, add side group raw materials to an organic solvent of a sodium-based substance, react to obtain a sodium salt solution;

[0011] The side group raw materials include at least two of chloroalcohol / phenol, alkenyl alcohol / phenol compound, methylene alcohol / phenol compound or phenol and its methyl derivatives;

[0012] S3, react the polydichlorophosphazene with the sodium salt solution to obtain chloroaryloxy polyphosphazene.

[0013] Compared with the prior art, by introducing specific carbonization-catalyzing chloroaryloxy side groups into the polyphosphazene molecular structure, the present invention significantly improves the carbonization efficiency of the polyphosphazene material, enables it to form a dense carbon layer in a high-temperature environment, thereby increasing the char residue rate; in addition, the polar chloro group can have an interfacial interaction with the substrate material, improve the interfacial binding force, help enhance the interfacial adhesion performance between the matrix and the heat-insulating material layer, reduce the risk of delamination or peeling caused by thermal stress, thereby improving the overall ablation resistance of the matrix, ensuring its effectiveness in extreme environments and extending the service life.

[0014] It should be noted that the above polydichlorophosphazene can be prepared by conventional bulk melting polymerization or solution polymerization methods in the art, and specifically, the polymerization method reported in CN110643046B can be referred to.

[0015] Further, in S2, the chloroalcohol / phenol includes at least one of 4-chloro-3-trifluoromethylphenol, 3-chloro-4-trifluoromethylphenol, 4-chlorophenol, 3-chlorophenol, 3-chloro-4-fluorophenol, 4-bromo-3-chlorophenol, 4-chloro-3-fluorophenol, trichloroethanol, 4-chlorobenzyl alcohol, 3-chlorobenzyl alcohol, 3-chloro-4-methylphenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol, 2,6-dichlorophenol, tetrachlorophenol or 2,4-dichlorophenol.

[0016] The preferred chloroalcohol / phenol is introduced as a side group into the main chain of the polyphosphazene molecule. Not only can it improve the carbonization ability of the material, but also it can form chemical bonds or physical entanglements with metals and epoxy / carbon fiber substrates at high temperatures, thereby enhancing the interfacial bonding force. At the same time, the presence of chlorine-containing side groups changes the intermolecular interactions and arrangements, strengthening the intermolecular forces and making the molecular chains stack more closely and orderly. This structural feature is not conducive to heat conduction, significantly reducing the thermal conductivity of the material. Therefore, in adiabatic applications, it can more effectively prevent heat from being conducted through the material, improving the adiabatic effect.

[0017] Further, in S2, the alkenyl alcohol / phenol compound includes at least one of 2-propenylphenol, 4-vinylphenol, 5-norbornene-2-methanol, 2-propenol, 2-butene-1-ol (cis + trans) or 3-methyl-2-butene-1-ol.

[0018] Further, the methylene alcohol / phenol compound includes at least one of 4-chloro-3-ethylphenol, o-propylphenol, p-propylphenylmethanol, m-propylphenol, methanol, ethanol, propanol, n-butanol or n-pentanol.

[0019] Further, in S2, the phenol and its methyl derivatives include at least one of phenol, o-methylphenol, p-methylphenol or m-methylphenol.

[0020] The preferred alkenyl alcohol / phenol compound, methylene alcohol / phenol compound, phenol and its methyl derivatives are introduced as side groups into the main chain of the polyphosphazene molecule, which is conducive to the polyphosphazene molecule reacting chemically with metals and epoxy / carbon fiber substrates, or physically entangling with the microscopic structure on the substrate surface, further enhancing the interfacial bonding force, enabling the material to maintain a good bonding state with the substrate in different environments, and thus effectively improving the service life and reliability of the material.

[0021] Further, in S2, the molar ratio of the side group raw material to the sodium-based substance is (1 - 3):1.

[0022] Specifically, the side-group raw materials in the present invention include chloroalcohol / phenol, and at least one of alkenyl alcohol / phenol compound or methylene alcohol / phenol compound. If only one of the alkenyl alcohol / phenol compound or methylene alcohol / phenol compound is included, the molar ratio of the chloroalcohol / phenol to any one of the substances is 1:(0.01 - 2). If both the alkenyl alcohol / phenol compound and methylene alcohol / phenol compound are included, the molar ratio of the chloroalcohol / phenol, alkenyl alcohol / phenol compound, and methylene alcohol / phenol compound is 1:(0.01 - 2):(0.01 - 2).

[0023] Specifically, the side-group raw materials in the present invention include chloroalcohol / phenol, phenol and its methyl derivatives, and at least one of alkenyl alcohol / phenol compound or methylene alcohol / phenol compound. If only one of the alkenyl alcohol / phenol compound or methylene alcohol / phenol compound is included, the molar ratio of the chloroalcohol / phenol, phenol and its methyl derivatives to any one of the substances is 1:(0.2 - 1):(0.01 - 2). If both the alkenyl alcohol / phenol compound and methylene alcohol / phenol compound are included, the molar ratio of the chloroalcohol / phenol, phenol and its methyl derivatives, alkenyl alcohol / phenol compound, and methylene alcohol / phenol is 1:(0.2 - 1):(0.01 - 2):(0.01 - 2).

[0024] Further, in S2, the mass-volume ratio of the sodium-based substance to the organic solvent is 1 g:(5 - 20) mL.

[0025] Specifically, in S2, the sodium-based substance is Na or NaH.

[0026] Specifically, in S2, the organic solvent includes at least one of methanol, ethanol, propanol, n-butanol, n-pentanol, petroleum ether, n-hexane, n-heptane or cyclohexane.

[0027] Specifically, in S2, the mass concentration of the sodium salt solution is 1 g / L - 100 g / L.

[0028] Further, in S3, the molar ratio of Cl in the polydichlorophosphazene to Na in the sodium salt solution is 1:(1 - 4).

[0029] It should be noted that the polydichlorophosphazene (PDCP) obtained by the polymerization reaction is dissolved in an organic solvent, and after obtaining a PDCP solution, it reacts with the sodium salt solution. The above organic solvent can be one of the following solvents: tetrahydrofuran, xylene, n-heptane, n-hexane or petroleum ether; preferably tetrahydrofuran.

[0030] Further, in S3, the temperature of the reaction is -30°C - 130°C, and the reaction time is 10 h - 56 h.

[0031] It should be noted that the PDCP solution is added dropwise to the sodium salt solution at -30°C to 30°C, and after the addition is completed, the temperature is raised to 60°C to 130°C for reaction, and the reaction time is 10h to 120h (including the addition time).

[0032] Specifically, in S3, after the reaction is completed, it further includes a post-treatment step: cooling the reaction solution to 15°C to 25°C, using an organic solvent and deionized water as precipitants to precipitate the reaction solution, redissolving the obtained solid in tetrahydrofuran, and further precipitating in deionized water to remove excess salts, and performing the cyclic operation 1 to 6 times to obtain a crude product; drying the crude product at 25 to 120°C and a vacuum degree of 10 to 100 KPa to obtain a chloroaryloxy polyphosphazene.

[0033] The above-mentioned organic solvent includes one or more of ethanol, methanol, deionized water, petroleum ether or n-heptane.

[0034] In a second aspect, the present invention provides a chloroaryloxy polyphosphazene prepared by the above-mentioned preparation method of chloroaryloxy polyphosphazene.

[0035] In a third aspect, the present invention provides the application of the above-mentioned chloroaryloxy polyphosphazene in the field of flexible thermal insulation materials.

[0036] The chloroaryloxy polyphosphazene provided by the present invention can simultaneously meet the requirements of a high char residue rate, excellent interfacial adhesion ability and good mechanical properties, and can ensure good adhesion and stability under high temperature and high gas flow erosion, meet the development needs of high-performance ablative-resistant materials, and have broad application prospects.

[0037] In a fourth aspect, the present invention provides a flexible thermal insulation material including the above-mentioned chloroaryloxy polyphosphazene.

[0038] Furthermore, the flexible thermal insulation material further includes a vulcanizing agent and silica.

[0039] As a specific embodiment of the present invention, the flexible thermal insulation material includes: 100 parts of chloroaryloxy polyphosphazene, 0.5 part of vulcanizing agent and 20 parts of silica.

[0040] The preparation method of the above-mentioned flexible thermal insulation material includes the following steps:

[0041] Mix the chloroaryloxy polyphosphazene, vulcanizing agent and silica and then perform flat vulcanization to obtain a flexible thermal insulation material.

[0042] Furthermore, the temperature of the flat vulcanization is 155°C to 165°C, and the time is 50min to 70min.

[0043] Vulcanizing the chlorine-containing aryloxy polyphosphazene with a vulcanizing agent at high temperature can form effective chemical bond crosslinks between the molecular chains of the chlorine-containing aryloxy polyphosphazene, thereby constructing a three-dimensional network structure and improving its tensile strength, tear resistance and heat resistance.

[0044] In a fifth aspect, the present invention also provides an application of the above flexible thermal insulation material in the thermal protection system of a solid rocket engine combustion chamber.

[0045] By introducing specific chlorine-containing aryloxy groups on the side chain of polyphosphazene, the present invention balances multiple properties such as the carbonization effect, mechanical properties and interfacial bonding strength of the material, improves its ablation resistance and heat insulation performance, and can significantly reduce the risk of delamination or peeling caused by thermal stress, extend the service life. When used in the thermal protection system of a solid rocket engine combustion chamber, it can greatly improve its ability to cope with various complex stresses during flight, ensure safety and stability at high altitudes, and has great potential application value in high-tech fields such as aerospace and military weapons. Description of the Drawings

[0046] Figure 1 It is a thermogravimetric diagram of the polyphosphazene products prepared in Example 2, Example 4, Example 8 and Comparative Example 1-2 of the present invention. Detailed Embodiments

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] In the following embodiments, unless otherwise specified, the reagents used are all commercially available analytical pure reagents. Unless otherwise specified, the following experimental methods and detection methods are all existing experimental methods and detection methods.

[0049] To better illustrate the present invention, further examples are given below through embodiments.

[0050] In the following examples and comparative examples, the tensile strength and elongation at break were measured according to GB / T 528-2009; the thermal stability was measured according to GB / T 27761-2011; the limiting oxygen index was measured according to GB / T 10707-2008; the ablation performance was measured according to the oxyacetylene ablation test of GJB 323A-1996. The adhesive shear strength test was carried out in accordance with GB / T 13936-2014 "Determination Method for Tensile Shear Strength of Adhesion between Vulcanized Rubber and Metal".

[0051] In the following examples and comparative examples, the polydichlorophosphazene (PDCP) used was prepared according to the polymerization method reported in CN110643046B. The obtained PDCP product was added to tetrahydrofuran for dissolution at a ratio of 1 g:10 mL to obtain a PDCP solution.

[0052] Example 1

[0053] This example provides a method for preparing chloroaryloxy phosphazene, which specifically includes the following steps:

[0054] S1, Add 1.1 molar equivalents of 2 - allylphenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of metallic sodium until the metallic sodium reacts completely to obtain a sodium salt solution Na-Cl-1.0;

[0055] S2, Add 1 molar equivalent of 4 - chlorobenzyl alcohol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of metallic sodium until all the metallic sodium reacts completely to obtain a sodium salt solution Na-Cl-1.1;

[0056] S3, Gradually add 1 molar equivalent of trichloroethanol to a tetrahydrofuran solution of 1 molar equivalent of metallic sodium until all the metallic sodium reacts completely to prepare a sodium salt solution Na-Cl-1.2;

[0057] S4, Gradually drop the PDCP solution into a mixed solution composed of Na-Cl-1.0, Na-Cl-1.1 and Na-Cl-1.2 (the molar ratio of the three is 0.1:0.8:0.8). During the dropping process, control the temperature at -10 to 10 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 2:1. After the dropping is completed, raise the temperature to 60 °C and react for 12 h. After the reaction ends, concentrate the reaction solution system by rotary evaporation to obtain a product solution, then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salts. After performing the above precipitation-dissolution-precipitation cycle operation 3 times, a preliminary product is obtained, and then it is dried at 120 °C and -50 KPa for 48 h to obtain the final product C-ClPZ-1.

[0058] The above-prepared C-CIPZ-1 is in an elastic state, and the char residue rate at 800 °C is 47%.

[0059] Mix 100 parts of the above C-CIPZ-1 product, 0.5 part of sulfur and 20 parts of silicon dioxide evenly, and vulcanize on a flat plate at 160 °C for 55 min to obtain a flexible thermal insulation material.

[0060] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 375 °C, the tensile strength can reach 7 MPa, the elongation at break is 300%, the limiting oxygen index is 29, the linear ablation rate is 0.08 mm / s, and the volume resistivity is 1.08×10 14 , the adhesion strength with 45# steel is 4.0 MPa, and the adhesion strength with epoxy / carbon fiber is 3.8 MPa.

[0061] Example 2

[0062] This example provides a preparation method of chlorinated aryloxy phosphazene, which specifically includes the following steps:

[0063] S1, Add 1.1 molar equivalents of 5-norbornene-2-ol to a tetrahydrofuran solution (1 g / 15 mL) of 1 molar equivalent of sodium hydride until the sodium hydride reacts completely to obtain a sodium salt solution Na-Cl-2.0;

[0064] S2, Add 1.05 molar equivalents of 3-chloro-4-fluorophenol to a tetrahydrofuran solution (1 g / 15 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to obtain a sodium salt solution Na-Cl-2.1;

[0065] S3, Gradually add 1.05 molar equivalents of p-chlorophenol to a tetrahydrofuran solution (1 g / 15 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to prepare a sodium salt solution Na-Cl-2.2;

[0066] S4, Gradually drip the PDCP solution into a mixed solution composed of Na-Cl-2.0, Na-Cl-2.1 and Na-Cl-2.2 (the molar ratio of the three is 0.15:0.8:1.2). During the dripping process, control the temperature at -30~-20 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 3:1. After the dripping is completed, raise the temperature to 130 °C and react for 56 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, and then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salts. After performing the above precipitation-dissolution-precipitation cycle operation 3 times, a preliminary product is obtained, and then it is dried at 100 °C and -60 KPa for 48 h to obtain the final product C-ClPZ-2.

[0067] The above-prepared C-CIPZ-2 is in an elastic state, and the char residue rate at 800 °C is 51%.

[0068] Mix 100 parts of the above C-CIPZ-2 product, 0.5 part of sulfur and 20 parts of silicon dioxide evenly, and vulcanize on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0069] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 450 °C, the tensile strength can reach 10 MPa, the elongation at break is 200%, the limiting oxygen index is 38, the linear ablation rate is 0.04 mm / s, and the volume resistivity is 2.2×10 14 , the adhesive strength with 45# steel is 3.9 MPa, and the adhesive strength with epoxy / carbon fiber is 3.7 MPa.

[0070] Example 3

[0071] This example provides a preparation method of chloroaryloxy polyphosphazene, which specifically includes the following steps:

[0072] S1, Add 1.1 molar equivalents of 4-vinylphenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of sodium hydride until the sodium hydride reacts completely to obtain a sodium salt solution Na-Cl-3.0;

[0073] S2, Add 1.05 molar equivalents of trichloroethanol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to obtain a chloro-containing sodium salt solution Na-Cl-3.1;

[0074] S3, Gradually add 1.05 molar equivalents of 4-bromo-3-chlorophenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to prepare a chloro-containing sodium salt solution Na-Cl-3.2;

[0075] S4, Gradually drip the PDCP solution into a mixed solution composed of Na-Cl-3.0, Na-Cl-3.1 and Na-Cl-3.2 (the molar ratio of the three is 0.05:1:1). During the dripping process, control the temperature at 0-10 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 2.5:1. After the dripping is completed, raise the temperature to 60 °C and react for 30 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, and then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salts. After performing the above precipitation-dissolution-precipitation cycle operation 5 times, a preliminary product is obtained, and then it is dried at 100 °C and -100 KPa for 72 h to obtain the final product C-ClPZ-3.

[0076] The above-prepared C-CIPZ-3 is in an elastic state, and the char residue rate at 800 °C is 47%.

[0077] Mix 100 parts of the above C-CIPZ-3 product, 0.5 part of sulfur and 20 parts of silica evenly, and vulcanize on a flat plate at 160 °C for 54 min to obtain a flexible thermal insulation material.

[0078] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 446 °C, the tensile strength can reach 10 MPa, the elongation at break is 300%, the limiting oxygen index is 42, the linear ablation rate is 0.04 mm / s, and the volume resistivity is 1.3×10 14 , the adhesion strength with 45# steel is 5.3 MPa, and the adhesion strength with epoxy / carbon fiber is 4.6 MPa.

[0079] Example 4

[0080] This example provides a preparation method of chlorinated aryloxy polyphosphazene, which specifically includes the following steps:

[0081] S1, Add 1.1 molar equivalents of 2-vinylphenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of sodium hydride until the sodium hydride reacts completely to obtain a sodium salt solution Na-Cl-4.0;

[0082] S2, Add 1.1 molar equivalents of p-chlorophenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of sodium hydride until the sodium hydride reacts completely to obtain a chlorinated sodium salt solution Na-Cl-4.1;

[0083] S3, Gradually drop the PDCP solution into the mixed solution composed of Na-Cl-4.0 and Na-Cl-4.1 (the molar ratio of the two is 0.01:2). Control the temperature at -5 to 5 °C during the dropping process, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 2:1. After the dropping is completed, raise the temperature to 100 °C and react for 30 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salt. After performing the above precipitation-dissolution-precipitation cycle operation 3 times, a preliminary product is obtained, and then it is dried at 80 °C and -80 KPa for 72 h to obtain the final product C-ClPZ-4.

[0084] The above-prepared C-CIPZ-4 is in a semi-crystalline plastic state, and the char residue rate at 800 °C is 48%.

[0085] Mix 100 parts of the above C-CIPZ-4 product, 0.5 part of sulfur and 20 parts of silica evenly, and vulcanize on a flat plate at 160 °C for 70 min to obtain a flexible thermal insulation material.

[0086] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 470 °C, the tensile strength can reach 12 MPa, the elongation at break is 50%, the limiting oxygen index is 34, the linear ablation rate is 0.02 mm / s, and the volume resistivity is 1.1×10 14 , the adhesion strength with 45# steel is 5.3 MPa, and the adhesion strength with epoxy / carbon fiber is 4.6 MPa.

[0087] Example 5

[0088] This example provides a preparation method of chloroaryloxy polyphosphazene, which specifically includes the following steps:

[0089] S1, Add 1.1 molar equivalents of 4-chloro-3-ethylphenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium hydride until the sodium hydride reacts completely to obtain a sodium salt solution Na-Cl-5.0;

[0090] S2, Add 1.1 molar equivalents of 2,4,6-trichlorophenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium hydride until all the sodium hydride reacts completely to obtain a chloro-containing sodium salt solution Na-Cl-5.1;

[0091] S3, Add 1.1 molar equivalents of 4-chloro-3-trifluoromethylphenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium hydride until all the sodium hydride reacts completely to prepare a chloro-containing sodium salt solution Na-Cl-5.2;

[0092] S4, Gradually drop the PDCP solution into a mixed solution composed of Na-Cl-5.0, Na-Cl-5.1 and Na-Cl-5.2 (the molar ratio of the three is 0.05:1:1). During the dropping process, control the temperature at 0-10 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 3:1. After the dropping is completed, raise the temperature to 110 °C and react for 36 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, and then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salt. After performing the above precipitation-dissolution-precipitation cycle operation 5 times, a preliminary product is obtained, and then it is dried at 80 °C and -100 KPa for 72 h to obtain the final product C-ClPZ-5.

[0093] The above-prepared C-CIPZ-5 is in an elastic state, and the char residue rate at 800 °C is 45%.

[0094] Mix 100 parts of the above C-CIPZ-5 product, 0.5 part of sulfur and 20 parts of silica evenly, and vulcanize on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0095] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 460 °C, the tensile strength can reach 12 MPa, the elongation at break is 340%, the limiting oxygen index is 43, the linear ablation rate is 0.04 mm / s, and the volume resistivity is 1.3×10 14 , the bonding strength with 45# steel is 5.7 MPa, and the bonding strength with epoxy / carbon fiber is 4.9 MPa.

[0096] Example 6

[0097] This example provides a preparation method of chloroaryloxy polyphosphazene, which specifically includes the following steps:

[0098] S1, Add 1.1 molar equivalents of 2-vinylphenol to a tetrahydrofuran solution (1 g / 15 mL) of 1 molar equivalent of metallic sodium until the metallic sodium reacts completely to obtain a sodium salt solution Na-Cl-6.0;

[0099] S2, Add 1.1 molar equivalents of 3-chlorobenzyl alcohol to a tetrahydrofuran solution (1 g / 15 mL) of 1 molar equivalent of metallic sodium until all the metallic sodium reacts completely to obtain a chloro-containing sodium salt solution Na-Cl-6.1;

[0100] S3, Gradually drop the PDCP solution into a mixed solution composed of Na-Cl-6.0 and Na-Cl-6.1 (the molar ratio of the two is 0.05:2). During the dropping process, control the temperature at -5 to 5 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 2.5:1. After the dropping is completed, raise the temperature to 60 °C and react for 10 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salt. After performing the above precipitation-dissolution-precipitation cycle operation 4 times, a preliminary product is obtained, and then it is dried at 100 °C and -80 KPa for 72 h to obtain the final product C-ClPZ-6.

[0101] The above-prepared C-CIPZ-6 is in a semi-crystalline plastic state, and the char residue rate at 800 °C is 47%.

[0102] Mix 100 parts of the above C-CIPZ-6 product, 0.5 part of sulfur and 20 parts of silica evenly, and vulcanize on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0103] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 320 °C, the tensile strength can reach 15 MPa, the elongation at break is 30%, the limiting oxygen index is 36, the linear ablation rate is 0.15 mm / s, and the volume resistivity is 0.8×1014 The adhesive strength with 45# steel is 5.3 MPa, and the adhesive strength with epoxy / carbon fiber is 4.6 MPa.

[0104] Example 7

[0105] This example provides a preparation method of chloroaryloxy polyphosphazene, which specifically includes the following steps:

[0106] S1. Add 1.2 molar equivalents of ethanol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium metal until the sodium metal reacts completely to obtain a sodium salt solution Na-Cl-7.0;

[0107] S2. Add 1.05 molar equivalents of 4-bromo-3-chlorophenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to obtain a chloro-containing sodium salt solution Na-Cl-7.1;

[0108] S3. Gradually add 1.05 molar equivalents of 2,4-dichlorophenol to a tetrahydrofuran solution (1 g / 10 mL) of 1 molar equivalent of sodium metal until all the sodium metal reacts completely to prepare a chloro-containing sodium salt solution Na-Cl-7.2;

[0109] S4. Gradually drop the PDCP solution into a mixed solution composed of Na-Cl-7.0, Na-Cl-7.1, and Na-Cl-7.2 (the molar ratio of the three is 0.15:0.85:0.8). During the dropping process, control the temperature at 0-10 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 3:1. After the dropping is completed, raise the temperature to 60 °C and react for 36 h. After the reaction ends, concentrate the reaction solution system by rotary evaporation to obtain a product solution, then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excessive salts. After performing the above precipitation-dissolution-precipitation cycle operation 4 times, obtain a preliminary product, and then dry it at 100 °C and -80 KPa for 72 h to obtain the final product C-ClPZ-7.

[0110] The above-prepared C-CIPZ-7 is in an elastic state, and the char residue rate at 800 °C is 35%.

[0111] Mix 100 parts of the above C-CIPZ-7 product, 0.5 part of sulfur and 20 parts of silica evenly, and vulcanize on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0112] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 355 °C, the tensile strength can reach 8 MPa, the elongation at break is 400%, the limiting oxygen index is 37, the linear ablation rate is 0.07 mm / s, and the volume resistivity is 1.3×10 14 , the adhesion strength with 45# steel is 5.3 MPa, and the adhesion strength with epoxy / carbon fiber is 4.6 MPa.

[0113] Example 8

[0114] This example provides a preparation method of chlorinated aryloxy polyphosphazene, which specifically includes the following steps:

[0115] S1, Add 1.1 molar equivalents of 2-propenylphenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of metallic sodium until the metallic sodium reacts completely to obtain a sodium salt solution Na-Cl-8.0;

[0116] S2, Add 1.05 molar equivalents of trichloroethanol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of metallic sodium until all the metallic sodium reacts completely to obtain a chlorinated sodium salt solution Na-Cl-8.1;

[0117] S3, Gradually add 1.05 molar equivalents of phenol to a tetrahydrofuran solution (1 g / 20 mL) of 1 molar equivalent of metallic sodium until all the metallic sodium reacts completely to prepare a chlorinated sodium salt solution Na-Cl-8.2;

[0118] S4, Gradually add the PDCP solution to a mixed solution composed of Na-Cl-8.0, Na-Cl-8.1 and Na-Cl-8.2 (the molar ratio of the three is 0.05:1:1). During the dropping process, control the temperature at -10 to 0 °C, and the molar ratio of Na in the total sodium salt to Cl in the PDCP solution is 2.5:1. After the dropping is completed, raise the temperature to 60 °C and react for 120 h. After the reaction is completed, concentrate the reaction solution system by rotary evaporation to obtain a product solution, then pour it into a mixed solvent of petroleum ether and ethanol for precipitation. Redissolve the obtained product in tetrahydrofuran, and then add it to deionized water for precipitation to remove excess salts. After performing the above precipitation-dissolution-precipitation cycle operation 5 times, a preliminary product is obtained, and then it is dried at 100 °C and -100 KPa for 72 h to obtain the final product C-ClPZ-8.

[0119] The specific reaction route is as follows:

[0120]

[0121] The above-prepared C-CIPZ-8 is in an elastic state, and the char residue rate at 800 °C is 44%.

[0122] Mix 100 parts of the above C-CIPZ-8 product, 0.5 part of sulfur and 20 parts of silica evenly, and cure them on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0123] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 320 °C, the tensile strength can reach 12 MPa, the elongation at break is 300%, the limiting oxygen index is 33, the linear ablation rate is 0.05 mm / s, and the volume resistivity is 1.5×10 14 , the adhesion strength with 45# steel is 5.0 MPa, and the adhesion strength with epoxy / carbon fiber is 4.7 MPa.

[0124] Comparative Example 1

[0125] This comparative example provides a method for preparing polyphosphazene. The only difference from Example 4 is that p-chlorophenol in S2 is replaced with an equal amount of p-cresol, and the rest is exactly the same.

[0126] The polyphosphazene prepared in this comparative example is in a plastic state, and the char residue rate at 800 °C is 32%.

[0127] Mix 100 parts of the above polyphosphazene product, 0.5 part of sulfur and 20 parts of silica evenly, and cure them on a flat plate at 160 °C for 70 min to obtain a flexible thermal insulation material.

[0128] The maximum decomposition temperature of the above-prepared flexible thermal insulation material is 430 °C, the tensile strength can reach 7 MPa, the elongation at break is 50%, the limiting oxygen index is 29, the linear ablation rate is 0.10 mm / s, and the volume resistivity is 1.0×10 14 , the adhesion strength with 45# steel is 2.8 MPa, and the adhesion strength with epoxy / carbon fiber is 2.7 MPa.

[0129] Comparative Example 2

[0130] This comparison provides a method for preparing polyphosphazene. The only differences from Example 5 are that 4-chloro-3-ethylphenol in S1 is replaced with an equal amount of m-propylphenol, 2,4,6-trichlorophenol in S2 is replaced with an equal amount of phenol, and 4-chloro-3-trifluoromethylphenol in S3 is replaced with an equal amount of m-cresol, and the rest is exactly the same.

[0131] The polyphosphazene prepared in this comparative example is in an elastic state, and the char residue rate at 800 °C is 30%.

[0132] Mix 100 parts of the above polyphosphazene product, 0.5 part of sulfur and 20 parts of silica evenly, and cure them on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0133] The maximum decomposition temperature of the prepared flexible thermal insulation material is 430 °C, the tensile strength can reach 8 MPa, the elongation at break is 150%, the limiting oxygen index is 29, the linear ablation rate is 0.09 mm / s, and the volume resistivity is 1.3×10 14 , the adhesion strength with 45# steel is 3.0 MPa, and the adhesion strength with epoxy / carbon fiber is 2.9 MPa.

[0134] Comparative Example 3

[0135] This comparative example provides a preparation method of polyphosphazene. The only difference from Example 5 is that trichloroethanol in S2 is replaced with an equal amount of phenol, and the rest is exactly the same.

[0136] The polyphosphazene prepared in this comparative example is in a semi-elastic state, and the char residue rate at 800 °C is 27%.

[0137] Mix 100 parts of the above polyphosphazene product, 0.5 part of sulfur and 20 parts of silicon dioxide evenly, and vulcanize on a flat plate at 160 °C for 62 min to obtain a flexible thermal insulation material.

[0138] The maximum decomposition temperature of the prepared flexible thermal insulation material is 430 °C, the tensile strength can reach 5 MPa, the elongation at break is 120%, the limiting oxygen index is 29, the linear ablation rate is 0.12 mm / s, and the volume resistivity is 1.2×10 14 , the adhesion strength with 45# steel is 2.5 MPa, and the adhesion strength with epoxy / carbon fiber is 2.3 MPa.

[0139] In summary, the chloroaryloxy polyphosphazene prepared in the examples of the present invention has stable vulcanization and crosslinking properties, as well as excellent mechanical properties, ablation resistance and interface bonding properties, and has great potential application value in various practical application fields.

[0140] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a chlorine-containing aryloxy polyphosphazene, characterized in that, It includes the following steps: S1. Prepare polydichlorophosphazene shown in formula (Ⅰ); S2. Add the side-chain raw materials into an organic solvent of a sodium-based substance and react to obtain a sodium salt solution; The side-chain raw materials include at least two of chloroalcohol / phenol, alkenyl alcohol / phenol compound, methylene alcohol / phenol compound, or phenol and its methyl derivatives; S3. React the polydichlorophosphazene with the sodium salt solution to obtain chloroaryloxy phosphazene.

2. The preparation method of the chloroaryloxy polyphosphazene according to claim 1, characterized in that, In S2, the chloroalcohol / phenol includes at least one of 4-chloro-3-trifluoromethylphenol, 3-chloro-4-trifluoromethylphenol, 4-chlorophenol, 3-chlorophenol, 3-chloro-4-fluorophenol, 4-bromo-3-chlorophenol, 4-chloro-3-fluorophenol, trichloroethanol, 4-chlorobenzyl alcohol, 3-chlorobenzyl alcohol, 3-chloro-4-methylphenol, 4-chloro-3-methylphenol, 2,4,6-trichlorophenol, 2,6-dichlorophenol, tetrachlorophenol, or 2,4-dichlorophenol; and / or In S2, the alkenyl alcohol / phenol compound includes at least one of 2-propenylphenol, 4-vinylphenol, 5-norbornene-2-methanol, 2-propenol, 2-butene-1-ol (cis + trans), or 3-methyl-2-butene-1-ol.

3. The preparation method of the chloroaryloxy polyphosphazene according to claim 1, characterized in that, In S2, the methylene alcohol / phenol compound includes at least one of 4-chloro-3-ethylphenol, o-propylphenol, p-propylphenylmethanol, m-propylphenol, methanol, ethanol, propanol, n-butanol, or n-pentanol; and / or In S2, the phenol and its methyl derivatives include at least one of phenol, o-methylphenol, p-methylphenol, or m-methylphenol.

4. The preparation method of the chloroaryloxy polyphosphazene according to claim 1, characterized in that, In S2, the molar ratio of the side-chain raw materials to the sodium-based substance is (1 - 3):

1.

5. The preparation method of the chloroaryloxy polyphosphazene according to claim 1, characterized in that, In S3, the molar ratio of Cl in the polydichlorophosphazene to Na in the sodium salt solution is 1:(1 - 4); and / or In S3, the reaction temperature is 0°C to 130°C, and the reaction time is 10 h to 120 h.

6. A chlorine-containing aryloxy polyphosphazene, characterized in that, It is prepared by the preparation method of chloroaryloxy phosphazene according to any one of claims 1 - 5.

7. Application of the chloroaryloxy phosphazene according to claim 6 in the field of flexible thermal insulation materials.

8. A flexible thermal insulation material, characterized in that, It includes the chloroaryloxy phosphazene according to claim 6.

9. The flexible heat insulating material according to claim 8, wherein, It further includes a vulcanizing agent and silica.

10. Application of the flexible thermal insulation material according to claim 8 or 9 in the thermal protection system of a solid rocket engine combustion chamber.

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