Flexible coaxial energy storage cable for electromagnetic ejection, material, preparation method and application

Abstract

The invention mainly relates to the technical field of spaceflight coaxial cables, and particularly provides a flexible coaxial energy storage cable for electromagnetic catapulting, a material, a preparation method and application, the cable material comprises a base material and a solid-solid composite phase change material, the base material comprises ethylene butyl acrylate and ethylene propylene diene monomer, and the mass ratio of ethylene butyl acrylate to ethylene propylene diene monomer is 3: 2-5: 3; the solid-solid composite phase change material is a silicon carbide-feldspar powder-based filler treated by pentaerythritol and trimethylolethane, the mass ratio of pentaerythritol to a trimethylolethane treatment agent is 1: 0.5-1: 1, and the content of the filler is 5-15% of the mass of the base material. By designing novel material components and a dual-crosslinking network structure, the problems of thermal management, interfacial compatibility, insufficient mechanical properties and the like of the existing cable material during high-current transmission are solved, stable work of the cable in a wide-temperature-range and high-stress environment is realized, and the service life of the cable is prolonged. And the harsh requirement of spaceflight electromagnetic emission equipment on large-current transmission is met.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of aerospace coaxial cables, specifically to flexible coaxial energy storage cables for electromagnetic catapults, materials, preparation methods, and applications. Background Art

[0002] At a time when aerospace electromagnetic launch technology is developing rapidly, flexible coaxial energy storage cables for electromagnetic catapults, as core components of energy transmission, undertake the critical task of transmitting large currents of up to 20,000 Arms in a short period of time. At the same time, they need to adapt to complex working conditions such as a wide temperature range of -60°C to 125°C and high-frequency bending. In the existing technology, cable insulation and sheath materials mostly use traditional single polymer matrices, such as polyvinyl chloride, ethylene propylene rubber, etc. Such materials are widely used in the field of conventional power transmission due to their cost advantages and easy processing. Although the applicant of the present invention, Anhui Valin Cable Group, has designed a series of cables and components for the ejection test line of the Aerospace Science and Industry Flight Technology Research Institute, which has initially met some basic functions, there are still significant technical gaps in core indicators such as achieving a stable flow of 20,000 Arms@14s at a rated voltage of 18 / 30kV, dust and water resistance in complex aerospace environments, and adaptability to a wide temperature range.

[0003] However, existing technologies still have many defects that need to be addressed. In terms of thermal management, the thermal conductivity of a single polymer matrix is ​​generally low. When a large current flows, the large amount of Joule heat generated inside the material cannot be dissipated in time, causing a sharp rise in local temperature, which can easily cause the material to soften, the insulation performance to deteriorate, and even safety hazards such as thermal breakdown. Even if nanofillers are introduced, due to the poor interface compatibility between the filler and the matrix, there is a significant thermal resistance interface, making it difficult for the filler to form an effective thermal conductivity network, and the improvement in heat conduction efficiency is limited.

[0004] Furthermore, the cross-linked polyethylene insulation used in traditional cables is difficult to install and lay due to its high hardness and large bending radius, making it difficult to adapt to the flexible layout requirements within the compact space of aerospace equipment. In terms of mechanical properties, the cross-linked structure of traditional materials is simple and unstable, making them unable to withstand the high-frequency mechanical stresses experienced during electromagnetic catapult launches. After long-term use, they are prone to cracking and breaking, and their bending fatigue life is generally low, making it difficult to meet the reliability requirements of the equipment. Summary of the Invention

[0005] In response to the above problems, the invention aims to provide flexible coaxial energy storage cables, materials, preparation methods, and applications for electromagnetic catapults. By designing new material components and double cross-linked network structures, it solves the thermal management problems, interface compatibility problems, and insufficient mechanical properties of existing cable materials during high current transmission, and enables the cable to operate stably in a wide temperature range and high stress environment, meeting the stringent requirements of aerospace electromagnetic launch equipment for large current transmission.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: In a first aspect, the present invention provides a flexible coaxial energy storage cable material for electromagnetic catapult, comprising a base material and a solid-solid composite phase change material.

[0007] The base materials consist of ethylene butyl acrylate (EBA) and ethylene propylene diene monomer (EPDM) in a mass ratio of 3:2 to 5:3. The butyl acrylate content of EBA is 40% to 60%, imparting a certain polarity to the material. This polarity can interact with polar groups on the surface of subsequently added functional fillers, such as through hydrogen bonding or dipole-dipole interactions, thereby enhancing the filler-matrix bonding. The asymmetric diene content of EPDM is 35% to 45%, providing the material with excellent elasticity and aging resistance. Keeping the mass ratio within the range of 3:2 to 5:3 enables the polar groups of EBA to form a nanoscale interpenetrating network with the elastic segments of EPDM, ensuring the material's flexibility while providing a favorable matrix environment for subsequent cross-linking reactions.

[0008] At the same time, solid-solid composite phase change materials play a key role in thermal management. They are silicon carbide-feldspar powder-based fillers treated with pentaerythritol and trimethylolethane. The mass ratio of pentaerythritol to trimethylolethane treatment agents is 1:0.5 to 1:1, and the filler content is 5% to 15% of the base material mass. Silicon carbide has high thermal conductivity, while feldspar powder can regulate the phase change temperature of the material to a certain extent. After the filler is treated, the pentaerythritol on the surface reacts with trimethylolethane through hydroxyl groups to form a polymer-like interface layer. This interface layer significantly improves the dispersion of the filler in the matrix and reduces thermal resistance. When the cable generates heat through current, it can absorb heat through solid-solid phase change, controlling the local temperature fluctuation of the cable within ±15°C and achieving efficient thermal management.

[0009] In some feasible ways, in order to further improve the performance of the insulation layer and sheath layer materials, the following functional components are added: Functional fillers, including but not limited to aluminum oxide, magnesium oxide, or other metal oxide fillers, comprise 10% to 15% of the base material by weight. These fillers are modified with acrylate-siloxane copolymers to form surface-coated copolymer-modified fillers. The siloxane segments of the acrylate-siloxane copolymer interact with the filler surface, while the acrylate segments provide active sites for subsequent cross-linking with the matrix. This significantly enhances the interfacial bonding strength between the filler and the matrix, allowing for uniform distribution of the filler within the matrix and forming a structure that facilitates heat conduction.

[0010] Flame retardant: A compound of aluminum hydroxide and magnesium hydroxide, with a content of 5% to 15% of the base material mass. At high temperatures, the two decompose and absorb heat, and the generated water vapor dilutes the concentration of combustible gases. The decomposed metal oxides form a heat-insulating and oxygen-isolating protective layer on the surface of the material, meeting the stringent fire safety requirements of aerospace equipment.

[0011] Functional macromolecules: Acrylate-siloxane copolymers are prepared from acrylate monomers and silane monomers. The silane monomer is selected from at least one of vinyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane, and the silane monomer forms a siloxane bond (Si-O-Si) after hydrolysis and condensation. The acrylate monomer is selected from at least one of methyl methacrylate and butyl acrylate. The siloxane segments in the acrylate-siloxane copolymer form chemical bonds with the surface of the functional filler, while the acrylate segments undergo free radical copolymerization with the EBA and EPDM molecular chains during the subsequent crosslinking process, playing a key role in bridging the gap between filler surface modification and crosslinking network construction.

[0012] Elastomer: Hydrogenated nitrile rubber or silicone rubber, with a content of 0-10% of the base material mass, dispersed in the material to form an "island" structure, improving the material's toughness and low-temperature performance.

[0013] Additives: Antioxidants and lubricants, with a total content of 1% to 3% of the base material weight. Antioxidants inhibit oxidative degradation by capturing free radicals and decomposing hydroperoxides. Lubricants reduce internal friction and prevent high-temperature viscosity, ensuring smooth material flow during extrusion and a smooth, defect-free cable surface.

[0014] Introducing reinforcements is crucial for improving the mechanical properties of materials. Among them, porous chopped aramid fibers are aromatic polyamide fibers with a length of 0.5 to 2 mm, comprising 2% to 4% of the base material's mass. After plasma treatment to increase the surface microporous structure, the mechanical bond strength with the matrix is ​​significantly enhanced. Ultra-high molecular weight polyethylene (UHMWPE) with a molecular weight of 1.5 to 6 million, comprising 5% to 8% of the base material's mass, is gel-spun into short fibers and then blended with the aramid fibers. In the subsequent graded extrusion process, these fibers work synergistically to form a three-dimensional interwoven network, effectively dispersing and transmitting stress, significantly enhancing the cable's mechanical properties and increasing its tensile strength.

[0015] In some feasible embodiments, the antioxidant is at least one of hindered phenols or phosphites; during material processing and use, hindered phenol antioxidants capture free radicals and phosphite antioxidants decompose hydroperoxides, and the two work synergistically to inhibit oxidative degradation of the material and extend the service life of the cable.

[0016] And / or, the lubricant is at least one of stearic acid or polyethylene wax.

[0017] In a second aspect, the present invention further provides a method for preparing a flexible coaxial energy storage cable material for electromagnetic catapults, which is used for the above-mentioned cable material, comprising the following steps: S1. Basic blending: Ethylene butyl acrylate and EPDM rubber are fed into a twin-screw extruder at a certain mass ratio and blended for a period of time at 120-140°C to keep the two polymers in a viscous flow state. The shearing action of the screw promotes the mutual diffusion and entanglement of the molecular chains, forming a uniform and stable base material, which provides an excellent matrix for the subsequent addition and reaction of functional components.

[0018] The present invention utilizes the high elasticity and weather resistance of EPDM and the polar group advantages of EBA to form a well-compatible blend matrix. The polar groups of EBA (butyl acrylate) and the non-polar elastic segments of EPDM are physically entangled to form an interpenetrating network, which improves the toughness and weather resistance of the matrix, provides a stable dispersion environment for components such as functional fillers and flame retardants, and fundamentally improves the mechanical strength and electrical insulation properties of the material.

[0019] S2. Introduction of functional components: functional fillers, flame retardants, functional macromolecules, elastomers and additives are added to the base material and melt blended at 150-200°C. At this temperature, the polymer matrix is ​​in a highly elastic state and the molecular chains move actively, which is conducive to the full dispersion of each component. At the same time, the acrylate segments of the acrylate-siloxane copolymer undergo free radical cross-linking reactions with the EBA and EPDM molecular chains to form a primary physical-chemical double cross-linking network.

[0020] S3. Phase Change Material Dispersion: Add solid-solid composite phase change material and continue blending until it is dispersed at the nanoscale to ensure uniform distribution and fully utilize the thermal management function.

[0021] S4. Cross-linking Network Strengthening: Add 1.5% to 3% of the total blend weight of a cross-linking agent to initiate chemical cross-linking at 180-200°C to further strengthen the physical and chemical dual cross-linking network.

[0022] The physical-chemical dual cross-linking network includes: Solid filler cross-linked network: functional fillers are chemically bonded to ethylene butyl acrylate and EPDM rubber through acrylate-siloxane copolymer; Polymer matrix cross-linked network: Ethylene butyl acrylate and EPDM rubber molecular chains form a three-dimensional network structure through a cross-linking agent. The two interpenetrate to form a double cross-linked network, which greatly enhances the overall performance of the material.

[0023] S5. Reinforcement Forming: Reinforcement materials are added and a graded extrusion process is used to form an organic fiber reinforcement network. The first stage, at an extrusion temperature of 160-180°C and a pressure of 5-8 MPa, achieves initial fiber orientation. The second stage, at an extrusion temperature of 180-200°C and a pressure of 8-10 MPa, further melts and entangles the fibers.

[0024] S6. Extrusion molding: The mixed materials are extruded to prepare cable materials.

[0025] In some achievable embodiments, the method for preparing a solid-solid composite phase change material includes the following steps: S01. Dissolve pentaerythritol and trimethylolethane in a mixed solvent of ethanol and water at a certain mass ratio to prepare a treatment agent solution with a concentration of 5% to 10%, and stir at 30 to 40°C until completely dissolved; S02. Filler silicon carbide and feldspar powder are added to a high-speed mixer in a mass ratio of 1:1, the treatment agent solution is poured into the mixer, and stirred at 500-80°C and 500-800 r / min for 2-3 hours to allow the hydroxyl groups of the treatment agent to condense with the silanol groups on the filler surface to form a polymer-affinity interface layer; S03. The reacted filler is dried to obtain a nano-scale solid-solid composite phase change material, thereby ensuring that the phase change material has good thermal management performance and dispersibility.

[0026] In some possible implementations, step S2 includes: Filler surface modification: Mix the functional filler with acrylate-siloxane copolymer at a rate of 1% to 3% of the filler mass, and dry at 70-90°C for 1-3 hours to form a modified filler with the copolymer coated on the surface; Melt blending and crosslinking: The modified filler is melt-blended with ethylene butyl acrylate and EPDM rubber at 150-200°C, and 5%-15% of a flame retardant, 0.5%-1.5% of an antioxidant and 0-10% of an elastomer are added to the total weight of the blend to allow the acrylate segments of the copolymer to undergo free radical crosslinking reactions with the molecular chains of the blend to form a primary physical-chemical double crosslinking network; the temperature is then lowered to 120-125°C, and 0.5%-2% of a lubricant is added to the total weight of the blend. The mixture is then mixed for 5-10 minutes to further improve the processing performance of the material.

[0027] In some achievable embodiments, the method for preparing the acrylate-siloxane copolymer comprises the following steps: Mixing acrylate monomer and silane monomer in a mass ratio of 1:3 to 1:9, adding 0.5% to 2% of the total weight of the monomers as an initiator; heating to 60 to 90°C under nitrogen protection, stirring and reacting for 2 to 4 hours to form a linear copolymer containing acrylate segments and siloxane segments; The molecular weight of the copolymer is 1000-5000 Da, and the molar ratio of the siloxane segment to the acrylate segment is 1:4-1:9, thereby ensuring that the copolymer plays a key role in the material system.

[0028] In a third aspect, the present invention further provides a flexible coaxial energy storage cable for electromagnetic catapults. The coaxial structure of the cable, from the inside to the outside, comprises: an inner conductor, an inner conductor shielding layer, an inner insulating layer, an inner insulating shielding layer, an outer conductor layer, an outer conductor shielding layer, an outer insulating layer, an outer insulating shielding layer, an overall shielding layer, and an outer sheath layer. At least one of the materials of the inner insulating layer, the outer insulating layer, and the outer sheath layer is made of the material of the flexible coaxial energy storage cable for electromagnetic catapults described above. The inner conductor is made of a high-conductivity metal material to ensure efficient current transmission. The outer conductor layer is made of a flexible metal braided structure to meet the bending requirements of the cable. The inner and outer conductor shielding layers are made of a conductive polymer material. The overall shielding layer is made of a composite structure of metal foil and metal braiding, which can effectively shield electromagnetic interference and ensure stable and reliable signal transmission.

[0029] Fourthly, the present invention also provides the application of flexible coaxial energy storage cables for electromagnetic catapults. The cables are used in aerospace electromagnetic launch equipment. They are used to achieve stable transmission of large currents with a temperature rise of ≤±15°C under rated voltage of 18 / 30kV and 20,000Arms@14s current conditions. They have a flame retardant grade of C and a bending radius of ≤8D. The cables can adapt to a wide temperature range of -60°C to 125°C, and have a performance retention rate of ≥90% after 50 high and low temperature cycles. The number of bending fatigue times is >50,000 times, meeting the stringent requirements of aerospace equipment for cable performance.

[0030] Compared with the prior art, the present invention has the following beneficial effects: (1) In terms of thermal management performance, the thermal conductivity of single polymer matrix cables in the existing technology is low, and there is a thermal resistance interface between the filler and the matrix, which makes it difficult to effectively dissipate heat when a large current flows. The present invention introduces a solid-solid composite phase change material, a silicon carbide-feldspar powder-based filler treated with pentaerythritol and trimethylolethane, and forms a polymer-friendly interface layer through surface modification, achieving nano-scale dispersion and effectively reducing thermal resistance. At the same time, the functional filler and the acrylate-siloxane copolymer synergistically construct a continuous thermal conductive network, which significantly improves the thermal conductivity of the material. Under the synergistic effect of the two, the local temperature fluctuation of the cable is controlled within ±15°C under the flow condition of 20,000 Arms@14s, and the thermal diffusion rate is increased by more than 40% compared with traditional materials, which completely solves the overheating problem during large current transmission and provides a reliable guarantee for the stable operation of aerospace electromagnetic launch equipment.

[0031] (2) In terms of mechanical properties, the cross-linking structure of traditional cables is single and cannot withstand high-frequency mechanical stress. The present invention achieves innovative breakthroughs by designing a physical-chemical dual cross-linking network and an organic fiber reinforcement system. The dual cross-linking network constructed by acrylate-siloxane copolymer enhances the interfacial bonding force between the filler and the matrix and the cross-linking density of the polymer molecular chain at the nanoscale; the porous short-cut aramid fiber and ultra-high molecular weight polyethylene form a three-dimensional interwoven network through a graded extrusion process, which significantly improves the material's stress dispersion ability. Ultimately, the cable's tensile strength is improved, the number of bending fatigue times exceeds 50,000 times (180° bending), and the performance retention rate after 50 high and low temperature cycles is ≥90%. The mechanical properties far exceed those of existing products, meeting the stringent requirements of aerospace equipment for high reliability.

[0032] (3) In terms of environmental adaptability, traditional cross-linked polyethylene insulation materials cannot adapt to the flexible layout requirements of compact space in aerospace equipment due to their high hardness and large bending radius. This invention optimizes the basic material formula to form a nano-level interpenetrating network of EBA and EPDM, and introduces an elastomer to form an "island" structure, giving the cable excellent flexibility. It can still maintain good bending performance in a low-temperature environment of -60°C, and the bending radius can be reduced to 1 / 3 of traditional materials, effectively solving the installation and laying problems. At the same time, the material has stable performance in a wide temperature range of -60°C to 125°C, broadening the application range of the cable.

[0033] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of the preparation process of the flexible coaxial energy storage cable material for electromagnetic catapult of the present invention; Figure 2 Schematic diagram comparing the tensile strength of the cable materials prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention; Figure 3 Schematic diagram comparing thermal conductivity of cable materials prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention; Figure 4 Schematic diagram comparing the tensile strength retention rates of the cable materials prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0035] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly used by those skilled in the art to which the present invention pertains. The terminology used in the specification of the present invention is for the purpose of describing specific embodiments and is not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0037] Example 1: This example provides a flexible coaxial energy storage cable material for electromagnetic catapults, including the following components in parts by mass: 60 parts of ethylene butyl acrylate, 40 parts of EPDM rubber, 10 parts of solid-solid composite phase change material, 12 parts of functional filler, 10 parts of flame retardant, 0.24 parts of functional macromolecules, 5 parts of elastomer, 2 parts of additives and 9 parts of reinforcing material.

[0038] In this embodiment, the butyl acrylate content of the ethylene butyl acrylate is 50%, and the asymmetric diene content of the EPDM rubber is 40%. The solid-solid composite phase change material is a silicon carbide-feldspar powder-based filler treated with pentaerythritol and trimethylolethane, wherein the mass ratio of pentaerythritol to trimethylolethane is 1:0.8.

[0039] In this embodiment, the functional filler is aluminum oxide; the flame retardant is a compound of aluminum hydroxide and magnesium hydroxide, and the mass ratio of aluminum hydroxide to magnesium hydroxide is 1:1; and the elastomer is hydrogenated nitrile rubber.

[0040] In this embodiment, the functional macromolecule is an acrylate-siloxane copolymer prepared from an acrylate monomer and a silane monomer, wherein the silane monomer is vinyl triethoxysilane and the acrylate monomer is butyl acrylate.

[0041] In this embodiment, the auxiliary agent includes 0.8 parts of an antioxidant and 1.2 parts of a lubricant. The antioxidant is a hindered phenol 1010 antioxidant, and the lubricant is stearic acid.

[0042] In this embodiment, the reinforcing material includes porous chopped aramid fiber and ultra-high molecular weight polyethylene. The porous chopped aramid fiber is an aromatic polyamide fiber with a length of 0.5 to 2 mm and a content of 3% of the mass of the basic material; the ultra-high molecular weight polyethylene has a molecular weight of 3 million and a content of 6% of the mass of the basic material.

[0043] Based on the above-mentioned flexible coaxial energy storage cable material for electromagnetic catapult, this embodiment further provides a method for preparing the flexible coaxial energy storage cable material for electromagnetic catapult, which is used to prepare the above-mentioned cable material, comprising the following steps: S1. Basic Blending: Ethylene butyl acrylate and EPDM rubber are fed into a twin-screw extruder and blended for a period of time at a temperature of 120-140°C to form a base material. Specifically, the extruder temperature is set at 120°C in the first section, 130°C in the second section, and 140°C in the third section. The screw speed is 200 r / min and the blending is carried out for 15 minutes.

[0044] S2. Functional component introduction: functional fillers, flame retardants, functional macromolecules, elastomers, and additives are added to the base material and melt blended at 150-200°C to form a primary physical-chemical dual crosslinking network. Specifically, the following steps are involved: Filler surface modification: functional filler and acrylate-siloxane copolymer were mixed at a rate of 2% by mass of the filler, and dried at 80°C for 2 hours to form a modified filler with the copolymer coated on the surface; Melt blending and crosslinking: The modified filler is melt-blended with ethylene butyl acrylate and EPDM rubber at 180°C, and flame retardants, antioxidants and elastomers are added at the same time to allow the acrylate segments of the copolymer to undergo free radical crosslinking reactions with the molecular chains of the blend to form a primary physical-chemical double crosslinking network; then the temperature is lowered to 140°C, a lubricant is added, and mixing is continued for 8 minutes.

[0045] S3. Phase change material dispersion: Add a solid-solid composite phase change material and continue blending until it is dispersed at the nanoscale. The method for preparing the solid-solid composite phase change material comprises the following steps: S01. Pentaerythritol and trimethylolethane were dissolved in a mixed solvent of ethanol and water at a certain mass ratio to prepare an 8% concentration of a treatment agent solution, and stirred at 35°C until completely dissolved; S02. Silicon carbide filler and feldspar powder were added to a high-speed mixer in a mass ratio of 1:1. The treatment agent solution was added and stirred at 600 rpm for 2.5 hours at 60°C to allow the hydroxyl groups of the treatment agent to condense with the silanol groups on the filler surface to form a polymer-affinity interface layer. S03. Drying the reacted filler to obtain a nano-scale solid-solid composite phase change material.

[0046] S4. Crosslinking network strengthening: Add 2% of the total weight of the blend as a crosslinking agent, dicumyl peroxide, to initiate chemical crosslinking at 190°C for 30 minutes to further strengthen the physical-chemical dual crosslinking network. In this embodiment, the physical-chemical dual crosslinking network includes: Solid filler cross-linked network: functional fillers are chemically bonded to ethylene butyl acrylate and EPDM rubber through acrylate-siloxane copolymer; Polymer matrix cross-linked network: Ethylene butyl acrylate and EPDM rubber molecular chains form a three-dimensional network structure through cross-linking agents, and the two interpenetrate to form a double cross-linked network; S5. Reinforcement Material Forming: Reinforcement material is added and an organic fiber reinforcement network is formed through a staged extrusion process. Specifically, in this embodiment, the first stage has an extrusion temperature of 170°C and an extrusion pressure of 6 MPa to achieve initial fiber orientation. The second stage has an extrusion temperature of 195°C and an extrusion pressure of 9 MPa to further melt and entangle the fibers.

[0047] S6. Extrusion molding: The mixed materials are extruded to prepare cable materials.

[0048] In some embodiments, the preparation method of an acrylate-siloxane copolymer includes the following steps: mixing an acrylate monomer and a silane monomer in a mass ratio of 1:5, adding an initiator AIBN accounting for 1% of the total mass of the monomers; heating to 80°C under nitrogen protection, stirring and reacting for 3 hours to form a linear copolymer containing acrylate segments and siloxane segments; and the molecular weight of the copolymer is 3000Da, and the molar ratio of the siloxane segment to the acrylate segment is 1:6.

[0049] On the third aspect, this embodiment also provides a flexible coaxial energy storage cable for electromagnetic catapult. The coaxial structure of the cable is, from the inside to the outside, inner conductor, inner conductor shielding layer, inner insulation layer, inner insulation shielding layer, outer conductor layer, outer conductor shielding layer, outer insulation layer, outer insulation shielding layer, overall shielding layer and outer sheath layer. The materials of the inner insulation layer, outer insulation layer and outer sheath layer are the same, and are all made of the above-mentioned flexible coaxial energy storage cable material for electromagnetic catapult.

[0050] In some embodiments, the inner conductor utilizes a high-conductivity metal material to ensure efficient current transmission. The outer conductor layer utilizes a flexible metal braid structure to accommodate cable bending requirements. The inner and outer conductor shielding layers utilize a conductive polymer material. The overall shielding layer utilizes a composite structure of metal foil and metal braiding, effectively shielding electromagnetic interference and ensuring stable and reliable signal transmission. Since the present invention does not modify the conductor and shielding materials, the materials used are not limited and can be adapted from existing aerospace coaxial cable conductor and shielding materials.

[0051] Fourthly, this embodiment also provides the application of the above-mentioned flexible coaxial energy storage cable for electromagnetic catapults. The cable is used in aerospace electromagnetic launch equipment to achieve stable transmission of large current under the rated voltage of 18 / 30kV and 20000Arms@14s current flow conditions, and is adaptable to a wide temperature range of -60℃ to 125℃.

[0052] The cable material prepared in this embodiment can be applied to the cable model ZC-HLERTFP 18 / 30kv 2*630, which is an internal designation of the applicant company. The flame retardant grade of the cable material, oxygen index ≥30, complies with the national standard GB / T19666C, and the bending radius ≤8D.

[0053] The cable prepared in this embodiment has a temperature fluctuation of ≤±15℃ under 18 / 30kV voltage and 20000Arms@14s current, which verifies the thermal management performance of the material. Test conditions: Ambient temperature: 25℃±2℃; Thermocouple: Placed every 50cm at the interface between the insulation layer and the shielding layer; Sampling frequency: 10Hz Temperature fluctuation ≤±15℃ (take 6 points ΔT max ).

[0054] Note: The cable model ZC-HLERTFP18 / 30kV 2*630 shown in this embodiment is only used to illustrate the application scenario of this application material and does not constitute a limitation on the scope of protection. Any cable using the same material composition and double cross-linking structure is within the scope of protection of this application. After applying this material to the ZC-HLERTFP18 / 30kV2×630 cable, the measured performance is as follows: Thermal conductivity 0.52W / m·K (comparative example 1, traditional material is only 0.22W / m·K); Bending fatigue life 52,000 times; After 50 cycles from -60℃ to 125℃, the tensile strength retention rate is 92%, which meets the extreme working conditions of aerospace catapult equipment.

[0055] Example 2: The material of the flexible coaxial energy storage cable for electromagnetic catapult in this example is basically the same as that in Example 1, except that it includes the following components in parts by mass: 50 parts of ethylene butyl acrylate, 30 parts of EPDM rubber, 12 parts of solid-solid composite phase change material, 12 parts of functional filler, 12 parts of flame retardant, 0.36 parts of functional macromolecule, 8 parts of elastomer, 2.4 parts of additive and 9.6 parts of reinforcing material.

[0056] In this embodiment, the butyl acrylate content of the ethylene butyl acrylate is 60%, and the asymmetric diene content of the EPDM rubber is 45%. The solid-solid composite phase change material is a silicon carbide-feldspar powder-based filler treated with pentaerythritol and trimethylolethane, wherein the mass ratio of pentaerythritol to trimethylolethane is 1:1.

[0057] In this embodiment, the functional filler is magnesium oxide; the elastomer is silicone rubber.

[0058] In this embodiment, the functional macromolecule is an acrylate-siloxane copolymer prepared from an acrylate monomer and a silane monomer, wherein the silane monomer is γ-methacryloxypropyltrimethoxysilane and the acrylate monomer is methyl methacrylate.

[0059] In this embodiment, the auxiliary agent includes 0.8 parts of antioxidant and 1.6 parts of lubricant, the antioxidant is a phosphite antioxidant, and the lubricant is polyethylene wax.

[0060] In this embodiment, the content of the porous chopped aramid fibers is 4% of the mass of the basic material; the molecular weight of the ultra-high molecular weight polyethylene is 6 million, and its content is 8% of the mass of the basic material.

[0061] Based on the above-mentioned flexible coaxial energy storage cable material for electromagnetic catapult, this embodiment further provides a method for preparing the flexible coaxial energy storage cable material for electromagnetic catapult, which is used to prepare the above-mentioned cable material. The basic steps are consistent with those in Example 1, except that: In step S2, in the filler surface modification, the functional filler and the acrylate-siloxane copolymer are mixed at a rate of 3% by mass of the filler, and dried at 90° C. for 1 hour to form a modified filler with the copolymer coated on the surface; In the melt blending and crosslinking step, the modified filler is melt blended with ethylene butyl acrylate and EPDM rubber at 200°C, and flame retardants, antioxidants and elastomers are added at the same time to form a primary physical-chemical dual crosslinking network; then the temperature is lowered to 125°C, a lubricant is added, and mixing is continued for 5 minutes.

[0062] The preparation method of the solid-solid composite phase change material in this embodiment includes the following steps: S01. Pentaerythritol and trimethylolethane were dissolved in a mixed solvent of ethanol and water at a certain mass ratio to prepare a 10% concentration of a treatment agent solution, and stirred at 40°C until completely dissolved; S02. Silicon carbide filler and feldspar powder were added to a high-speed mixer in a mass ratio of 1:1. The treatment agent solution was added and stirred at 800 rpm for 2 hours at 80°C to allow the hydroxyl groups of the treatment agent to condense with the silanol groups on the filler surface to form a polymer-affinity interface layer. S03. Drying the reacted filler to obtain a nano-scale solid-solid composite phase change material.

[0063] In step S4 of this embodiment, dicumyl peroxide, a cross-linking agent, was added in an amount of 3% by weight of the total blend, and chemical cross-linking was initiated at 200° C. for 25 minutes.

[0064] In step S5 of this embodiment, reinforcing materials are added and an organic fiber reinforced network is formed through a graded extrusion process; specifically, in this embodiment, the extrusion temperature of the first section is 180°C and the extrusion pressure is 5 MPa; the extrusion temperature of the second section is 200°C and the extrusion pressure is 8 MPa.

[0065] In some embodiments, the preparation method of an acrylate-siloxane copolymer includes the following steps: mixing an acrylate monomer and a silane monomer in a mass ratio of 1:9, adding an initiator AIBN accounting for 2% of the total mass of the monomers; heating to 90°C under nitrogen protection, stirring and reacting for 4 hours to form a linear copolymer containing acrylate segments and siloxane segments; and the molecular weight of the copolymer is 5000Da, and the molar ratio of the siloxane segment to the acrylate segment is 1:9.

[0066] Example 3: The material of the flexible coaxial energy storage cable for electromagnetic catapult in this example is basically the same as that in Example 1, except that it includes the following components in parts by mass: 80 parts of ethylene butyl acrylate, 50 parts of EPDM rubber, 6.5 parts of solid-solid composite phase change material, 13 parts of functional filler, 6.5 parts of flame retardant, 1.3 parts of functional macromolecule, 6.5 parts of elastomer, 1.3 parts of additive and 9.1 parts of reinforcing material.

[0067] In this embodiment, the butyl acrylate content of the ethylene butyl acrylate is 60%, and the asymmetric diene content of the EPDM rubber is 35%. The solid-solid composite phase change material is a silicon carbide-feldspar powder-based filler treated with pentaerythritol and trimethylolethane, with the mass ratio of pentaerythritol to trimethylolethane being 1:0.5.

[0068] Based on the above-mentioned flexible coaxial energy storage cable material for electromagnetic catapult, this embodiment further provides a method for preparing the flexible coaxial energy storage cable material for electromagnetic catapult, which is used to prepare the above-mentioned cable material. The basic steps are consistent with those in Example 1, except that:

[0069] In step S2, in the filler surface modification, the functional filler and the acrylate-siloxane copolymer are mixed at a rate of 1% by mass of the filler, and dried at 70° C. for 3 hours to form a modified filler with the copolymer coated on the surface;

[0070] In the melt blending and crosslinking step, the modified filler is melt blended with ethylene butyl acrylate and EPDM rubber blend at 125°C, and flame retardants, antioxidants and elastomers are added at the same time to form a primary physical-chemical dual crosslinking network; then the temperature is lowered to 120°C, a lubricant is added, and mixing is continued for 10 minutes.

[0071] The preparation method of the solid-solid composite phase change material in this embodiment includes the following steps: S01. Pentaerythritol and trimethylolethane were dissolved in a mixed solvent of ethanol and water at a certain mass ratio to prepare a 5% concentration of a treatment agent solution, and stirred at 30°C until completely dissolved; S02. Silicon carbide filler and feldspar powder were added to a high-speed mixer in a mass ratio of 1:1. The treatment agent solution was added and stirred at 50°C and 600 rpm for 3 hours to allow the hydroxyl groups of the treatment agent to condense with the silanol groups on the filler surface to form a polymer-affinity interface layer. S03. Drying the reacted filler to obtain a nano-scale solid-solid composite phase change material.

[0072] In step S4 of this embodiment, dicumyl peroxide, a cross-linking agent, was added in an amount of 1% by weight of the total blend to initiate chemical cross-linking at 125° C. for 30 minutes.

[0073] In some embodiments, the preparation method of an acrylate-siloxane copolymer includes the following steps: mixing an acrylate monomer and a silane monomer in a mass ratio of 1:3, adding an initiator AIBN accounting for 0.5% of the total mass of the monomers; heating to 60°C under nitrogen protection, stirring and reacting for 2 hours to form a linear copolymer containing acrylate segments and siloxane segments; and the molecular weight of the copolymer is 1000Da, and the molar ratio of the siloxane segment to the acrylate segment is 1:4.

[0074] Comparative Example 1: The cable material in this comparative example uses single ethylene butyl acrylate as the base material, and no solid-solid composite phase change material is added. The specific raw material composition is: 100 parts of ethylene butyl acrylate, 12 parts of functional filler, 10 parts of flame retardant, 0.24 parts of functional macromolecule, 5 parts of elastomer, 2 parts of additive and 9 parts of reinforcing material.

[0075] Comparative Example 2: This comparative example uses traditional cross-linked polyethylene XLPE, and the specific raw material composition is: 100 parts of cross-linked polyethylene, 10 parts of solid-solid composite phase change material, 12 parts of unmodified filler alumina, 10 parts of flame retardant, 0.24 parts of functional macromolecules, 5 parts of elastomer, and 2 parts of additives.

[0076] Comparative Example 3: The cable material in this comparative example adopts a single EPDM rubber as the base material. The specific raw material composition is: 100 parts of EPDM rubber, 10 parts of untreated silicon carbide-feldspar powder-based filler, 12 parts of unmodified filler alumina, 10 parts of flame retardant, 0.24 parts of functional macromolecules, 5 parts of elastomer, 2 parts of additives and 9 parts of reinforcing material.

[0077] Comparative table of performance parameters of the cable materials prepared in Examples 1-3 and Comparative Examples 1-3.

[0078]

[0079] As can be seen from the table above, the examples have achieved comprehensive improvements in thermal management, mechanical properties, flame retardancy, and environmental adaptability through multi-component composite system design and process innovation: ethylene butyl acrylate and ethylene propylene diene monomer rubber are used to form a nano-interpenetrating network matrix, combined with a solid-solid composite phase change material treated with pentaerythritol and trimethylolethane and a functional filler modified with an acrylate-silane copolymer, to construct a physical-chemical dual cross-linked network (tensile strength 24.2~26.5MPa), and through the aramid fiber and ultra-high molecular weight polyethylene reinforcement system ( The material's thermal conductivity reaches 0.45-0.58 W / m·K, a 73%-93% increase compared to the comparative example (0.22-0.30 W / m·K), effectively addressing overheating issues during high current flow. The double-crosslinked network achieves a tensile strength of 24.2-26.5 MPa and a bending fatigue life of over 50,000 cycles, significantly improving upon the comparative example's tensile strength of 12.3-19.8 MPa and bending fatigue life of 12,000-30,000 cycles, meeting high-frequency mechanical stress requirements. Furthermore, the cable material prepared in this embodiment exhibits a performance retention rate of >90% after cycling at -60°C to 125°C, and an oxygen index of 30-34, meeting aerospace-grade flame retardancy and wide temperature range requirements.

[0080] In Comparative Example 1, a single EBA matrix is ​​used without a cross-linked network and phase change material, resulting in a thermal conductivity of only 0.22 W / m·K and a tensile strength of 12.3 MPa, which is unable to cope with high current heating and mechanical stress; in Comparative Example 2, traditional XLPE is used. Due to the lack of filler interface modification and double cross-linking, the thermal conductivity is 0.25 W / m·K, the bending radius reaches 18D, and the low-temperature performance is significantly degraded; in Comparative Example 3, there is no double cross-linking. Although it contains fillers but is not chemically modified, the insufficient cross-linking degree results in a tensile strength of 19.8 MPa and a thermal conductivity of 0.30 W / m·K. The overall performance still lags behind the examples.

[0081] The embodiment of the present invention solves the defects of traditional materials such as high thermal resistance, poor interface compatibility, and single mechanical structure through the synergistic mechanism of "nano interpenetrating network + double cross-linking + interface modification + fiber reinforcement", and meets the stringent requirements of aerospace electromagnetic catapult equipment.

[0082] The test methods and conditions for the relevant performance parameter data in the above table are as follows: 1.Tensile strength (MPa) standard: ASTM D638-14 (Type I dumbbell specimen); Test conditions: Sample size: 3.2 mm thickness, 50 mm gauge length; tensile speed: 5 mm / min; environmental conditions: 23°C ± 2°C, humidity 50% ± 5%; Equipment: Universal testing machine; 2. Thermal conductivity (W / m·K) standard: ASTM D5470-19 (heat flow meter method); Test conditions: Sample size: 50mm diameter, 2mm thickness; Test temperature: 25℃±1℃; Heat flux: 0.5W / cm²; Equipment: Thermal conductivity meter.

[0083] 3. Oxygen index (OI) standard: GB / T2406.2-2009 (vertical combustion method); Test conditions: Sample size: 150mm×10mm×4mm; Gas flow: 21% oxygen, 79% nitrogen; Ignition time: 30 seconds; Equipment: Oxygen index meter.

[0084] 4. Bending fatigue times (10,000 times) standard: ASTM E647-15 (rotational bending method); Test conditions: Sample size: 100 mm × 10 mm × 4 mm; Stress ratio (R): 0.1; Frequency: 20 Hz; Number of cycles: 10 6 Second-rate; Equipment: Fatigue testing machine (load accuracy ±1%).

[0085] 5. Wide temperature range stability (-60℃~125℃ retention rate) adopts temperature cycle test: Test conditions: Cycle parameters: -60℃ (30min) → 125℃ (30min), 50 cycles in total; Conversion time: ≤30 seconds; Post-test performance: tensile strength retention rate; Equipment: Temperature shock test chamber (temperature accuracy ±1°C).

[0086] Any numerical value cited herein includes all values ​​of the lower and upper values ​​in increments of one unit from the lower limit to the upper limit, and there is an interval of at least two units between any lower value and any higher value. For example, if the value of the quantity of a component or a process variable (such as temperature, pressure, time, etc.) is set forth to be from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in this specification. For values ​​less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples that are intended to be clearly expressed, and it can be considered that all possible combinations of the numerical values ​​listed between the minimum and maximum values ​​are explicitly set forth in this specification in a similar manner.

[0087] Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. When used with a range, "about" or "approximately" applies to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30," including at least the specified endpoints.

[0088] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the appended claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the foregoing claims is not intended to be a disclaimer of such subject matter, nor should it be assumed that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

[0089] The above description of the present invention is exemplified in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. Flexible coaxial energy storage cable material for electromagnetic catapult, characterized in that: Including basic materials and solid-solid composite phase change materials: The base material comprises ethylene butyl acrylate and EPDM rubber, the mass ratio of the two being 3:2 to 5:3, the butyl acrylate content in the ethylene butyl acrylate being 40% to 60%, and the asymmetric diene content in the EPDM rubber being 35% to 45%; The solid-solid composite phase change material is a silicon carbide-feldspar powder-based filler treated with pentaerythritol and trimethylolethane, wherein the mass ratio of pentaerythritol to trimethylolethane treating agent is 1:0.5 to 1:1, and the content of the filler is 5% to 15% of the mass of the base material.

2. The flexible coaxial energy storage cable material for electromagnetic catapult according to claim 1, characterized in that: Also includes the following components: Functional fillers: including but not limited to alumina, magnesia or other metal oxide fillers, whose content is 10% to 15% of the base material mass; Flame retardant: a compound of aluminum hydroxide and magnesium hydroxide, with a content of 5% to 15% of the base material mass; Functional macromolecule: acrylate-siloxane copolymer, prepared from acrylate monomer and silane monomer, wherein the silane monomer is selected from at least one of vinyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane; the acrylate monomer is selected from at least one of methyl methacrylate and butyl acrylate; Elastomer: hydrogenated nitrile rubber or silicone rubber, the content is 5-10% of the base material mass; Additives: antioxidants and lubricants, the total content is 1% to 3% of the base material mass.

3. The flexible coaxial energy storage cable material for electromagnetic catapult according to claim 2, characterized in that: Also included is a reinforcing material, the reinforcing material comprising: Porous chopped aramid fiber is an aromatic polyamide fiber with a length of 0.5 to 2 mm and a content of 2% to 4% of the base material mass; Ultra-high molecular weight polyethylene has a molecular weight of 1.5 million to 6 million, and its content is 5% to 8% of the base material mass.

4. The flexible coaxial energy storage cable material for electromagnetic catapult according to claim 2, characterized in that: The antioxidant is at least one of hindered phenols or phosphites; And / or, the lubricant is at least one of stearic acid or polyethylene wax.

5. A method for preparing a flexible coaxial energy storage cable material for electromagnetic catapult, used to prepare the cable material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Basic Blending: Ethylene butyl acrylate and EPDM rubber are fed into a twin-screw extruder at a specific mass ratio and blended for a period of time at 120-140°C to form the base material. S2. Functional component introduction: functional fillers, flame retardants, functional macromolecules, elastomers, and additives are added to the base material and melt blended at 150-200°C to form a primary physical-chemical dual crosslinking network; S3. Phase change material dispersion: Add solid-solid composite phase change material and continue blending until nanoscale dispersion; S4. Crosslinking Network Strengthening: Adding a crosslinker at 1.5% to 3% by weight of the total blend to initiate chemical crosslinking at 180-200°C further strengthens the physical and chemical crosslinking network. The physical-chemical dual cross-linked network comprises: Solid filler cross-linked network: functional fillers are chemically bonded to ethylene butyl acrylate and EPDM rubber through acrylate-siloxane copolymer; Polymer matrix cross-linked network: Ethylene butyl acrylate and EPDM rubber molecular chains form a three-dimensional network structure through cross-linking agents, and the two interpenetrate to form a double cross-linked network; S5. Reinforcement Molding: Add reinforcement materials and form an organic fiber reinforcement network through a graded extrusion process; S6. Extrusion molding: The mixed materials are extruded to prepare cable materials.

6. The method for preparing a flexible coaxial energy storage cable material for electromagnetic catapult according to claim 5, characterized in that: The preparation method of the solid-solid composite phase change material comprises the following steps: S01. Dissolve pentaerythritol and trimethylolethane in a mixed solvent of ethanol and water at a certain mass ratio to prepare a treatment agent solution with a concentration of 5% to 10%, and stir at 30 to 40°C until completely dissolved; S02. Filler silicon carbide and feldspar powder are added to a high-speed mixer in a mass ratio of 1:1, the treatment agent solution is poured into the mixer, and stirred at 500-80°C and 500-800 r / min for 2-3 hours to allow the hydroxyl groups of the treatment agent to condense with the silanol groups on the filler surface to form a polymer-affinity interface layer; S03. Drying the reacted filler to obtain a nano-scale solid-solid composite phase change material.

7. The method for preparing a flexible coaxial energy storage cable material for electromagnetic catapult according to claim 5, characterized in that: The step S2 includes: Filler surface modification: Mix the functional filler with acrylate-siloxane copolymer at a rate of 1% to 3% of the filler mass, and dry at 70-90°C for 1-3 hours to form a modified filler with the copolymer coated on the surface; Melt blending and crosslinking: melt blending the modified filler with ethylene butyl acrylate and EPDM rubber at 150-200° C., and simultaneously adding 5%-15% of a flame retardant, 0.5%-1.5% of an antioxidant and 0-10% of an elastomer, accounting for the total weight of the blend, so that the acrylate segments of the copolymer undergo free radical crosslinking reaction with the molecular chains of the blend to form a primary physical-chemical double crosslinking network; then cooling to 120-125° C., adding 0.5%-2% of a lubricant, accounting for the total weight of the blend, and continuing mixing for 5-10 minutes.

8. The method for preparing a flexible coaxial energy storage cable material for electromagnetic catapult according to any one of claims 5 to 7, characterized in that: The preparation method of the acrylate-siloxane copolymer comprises the following steps: Mixing acrylate monomer and silane monomer in a mass ratio of 1:3 to 1:9, adding 0.5% to 2% of the total weight of the monomers as an initiator; heating to 60 to 90°C under nitrogen protection, stirring and reacting for 2 to 4 hours to form a linear copolymer containing acrylate segments and siloxane segments; The molecular weight of the copolymer is 1000-5000 Da, and the molar ratio of the siloxane segment to the acrylate segment is 1:4-1:

9.

9. Flexible coaxial energy storage cable for electromagnetic catapult, characterized in that: The coaxial structure of the cable is, from the inside to the outside, an inner conductor, an inner conductor shielding layer, an inner insulating layer, an inner insulating shielding layer, an outer conductor layer, an outer conductor shielding layer, an outer insulating layer, an outer insulating shielding layer, a total shielding layer and an outer sheath layer, and at least one of the materials of the inner insulating layer, the outer insulating layer and the outer sheath layer is made of the flexible coaxial energy storage cable material for electromagnetic catapult according to any one of claims 1 to 4.

10. An application of the flexible coaxial energy storage cable for electromagnetic catapult according to claim 9, characterized in that: The cable is used in aerospace electromagnetic launch equipment, and is used for temperature rise ≤±15°C under rated voltage 18 / 30kV, 20000Arms@14s current conditions, and has a flame retardant grade of C, a bending radius ≤8D, and is adaptable to a wide temperature range of -60°C to 125°C.

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