Electron beam modified polyethylene insulating material combined with microwave pretreatment

Abstract

The invention discloses an electron beam modified polyethylene insulating material combined with microwave pretreatment. The material comprises low-crystallization highly-branched linear polyethylene, recombinant memory peptide modified chitosan particles, a cleavable polyether copolymer with polar end groups, a phytosterol phenol-quaternary ammonium salt block polymer and an antioxidant. The preparation process sequentially comprises the steps of pre-drying, microwave induction-electric field synergistic chain segment arrangement, electron beam directional crosslinking and inert gas cooling and shaping. Cooperative response of polar particles and a non-polar main chain is excited through coupling of microwaves and a low-frequency electric field, deep pre-arrangement of polyethylene chain segments within the thickness range of 2-4 mm is achieved, and a high-uniformity three-dimensional cross-linked network is formed in combination with electron beam irradiation. The material provided by the invention has high breakdown strength, excellent mechanical properties and thermal aging resistance, and is suitable for the fields of medium-voltage cables, photovoltaic cables, high-voltage new energy automobile cables and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer insulation materials, in particular to an electron beam modified polyethylene insulation material combined with microwave pretreatment. Background Art

[0002] Polyethylene (PE) is widely used in cable insulation due to its excellent electrical insulation properties, stable dielectric properties, and low raw material costs. Cross-linked polyethylene (XLPE), in particular, has become the mainstream material for medium and low voltage power cables due to its excellent heat resistance and electrical properties. However, existing polyethylene insulation modification methods often rely on the following traditional methods:

[0003] Thermochemical cross-linking method (such as DCP peroxide method): The cross-linking reaction needs to be initiated in a high temperature environment of 180-230°C. There are problems such as high equipment investment, high energy consumption, and residual cross-linking by-products (such as alcohols, ketones, and aldehydes). At the same time, this process is not conducive to recycling and does not meet the requirements of green manufacturing.

[0004] Electron beam irradiation modification technology: Although it has the advantages of low temperature and high efficiency, it is easy to cause random breakage of the main chain in actual application, forming a disordered cross-linked structure, resulting in a decrease in the mechanical properties of the material and increased embrittlement; especially in medium and thick specifications of cables, the electron beam has insufficient penetration, limited cross-linking depth, and low segment response efficiency, which limits its scope of engineering application.

[0005] Inorganic nanofiller enhancement and modification route: The insulation performance is improved by adding aluminum oxide, magnesium hydroxide, nano-silicon, etc., but the filler particle size is difficult to control and the interface compatibility is poor, which can easily lead to uneven dispersion and dielectric breakdown paths causing electrical weaknesses. The added amount also significantly increases the material density and cost.

[0006] Furthermore, most of the aforementioned modification technologies fail to effectively address the "non-polarity and high flexibility" of the polyethylene backbone. This results in a lack of chain segment alignment at the microscopic level, preventing the formation of an ordered cross-linked network structure. In particular, under energy field-assisted systems such as microwave excitation and infrared pretreatment, the PE segments respond poorly to the field energy, limiting both the efficiency and depth of modification.

[0007] Therefore, how to achieve directional reconstruction and stable cross-linking of the polyethylene main chain in a mild and green way without relying on high-temperature and high-pressure chemical reactions or a high proportion of inorganic fillers has become a technical bottleneck and R&D hotspot in this field. Summary of the Invention

[0008] The purpose of the present invention is: the present invention aims to provide an electron beam modified polyethylene insulation material combined with microwave pretreatment. The present invention realizes for the first time the synergistic control of microscale arrangement induction and free radical directional cross-linking of non-polar polyethylene main chain segments, while improving the insulation and mechanical properties of the material, realizing a low-energy, green, and automatable industrialization path, and has broad engineering application prospects.

[0009] The technical solution adopted in the present invention is as follows:

[0010] Electron beam modified polyethylene insulation material combined with microwave pretreatment, the material comprises the following components in weight percentage:

[0011] Low crystallinity highly branched linear polyethylene: 75% to 90%;

[0012] Recombinant memory peptide modified chitosan microparticles: 5% to 10%;

[0013] Cleavable polyether copolymer with polar end groups: 3% to 10%;

[0014] Phytosterol phenol-quaternary ammonium salt block polymer: 1% to 2%;

[0015] Antioxidant: 0.2%~0.5%.

[0016] The method for preparing the material comprises the following steps:

[0017] (1) Dry all components at 40-60°C for 8-12 hours;

[0018] (2) treating the dried mixed material in a microwave field with a frequency of 2.3 to 2.6 GHz and a power of 1.0 to 1.5 kW for 30 to 60 seconds to stimulate the memory response unit and induce the main chain configuration adjustment;

[0019] (3) placing the microwave-treated material in an electron beam device with an acceleration voltage of 0.7 to 1.5 MeV and an irradiation dose of 40 to 80 kGy to perform directional chain cross-linking reconstruction;

[0020] (4) Cool and solidify in an inert atmosphere such as nitrogen at 15-30°C to complete the structural setting.

[0021] The microwave treatment step is carried out in a reflective microwave cavity with an inner wall of silver-plated ceramic and is equipped with a rotary feeding mechanism.

[0022] The electron beam irradiation step is carried out in a continuous belt conveyor system at a conveying speed of 5 to 15 m / min.

[0023] The material has a breakdown field strength of ≥36 kV / mm, a tensile strength of ≥18 MPa, an elongation at break of >500%, and a volume resistivity change rate of ≤±5% after thermal aging for 168 hours (120° C.).

[0024] The particle size of the recombinant memory peptide modified chitosan particles is 100 to 300 nm, and the particles exhibit transient conformational unfolding capability under microwave excitation to induce the arrangement and orientation of polyethylene chain segments.

[0025] The main chain of the cleavable polyether copolymer contains terminal hydroxyl groups or ester structures, which can preferentially undergo segment cleavage under the action of electron beams and form cross-linking active sites.

[0026] Among them, a room temperature static slow cooling stage is set after the microwave induction step, which lasts for 2 to 5 minutes to stabilize the primary alignment structure of the chain segments and enhance the cross-linking uniformity.

[0027] The time interval between microwave induction and electron beam irradiation does not exceed 10 minutes, and the two steps are continuously arranged on a production line to realize full-process automated modification.

[0028] Among them, the material is suitable for 3.6~35kV grade cable insulation layer, photovoltaic cables, charging pile cables, high-voltage electric vehicle cables and other medium-voltage cable products.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. Compared with existing insulation materials based on cross-linked polyethylene (XLPE) or metallocene polyethylene (mPE), the formula of the present invention has achieved significant advantages in the following key cable performance indicators:

[0031] The material of the present invention generally has a breakdown field strength of 36.5-38.7 kV / mm, while existing traditional XLPE materials generally have a breakdown field strength of 30-32 kV / mm. By creating an ordered cross-linked structure, the present invention improves insulation uniformity and electric field tolerance, enabling it to meet the technical requirements of higher-grade cable insulation (up to 35 kV).

[0032] In terms of tensile properties, the samples of this invention achieved a strength of 18.219.3 MPa and an elongation at break greater than 500%, significantly outperforming existing products. This demonstrates that this material not only offers superior insulation properties but also possesses excellent flexibility and mechanical stability, making it particularly suitable for flexible applications such as dynamic cables, automotive wiring harnesses, and photovoltaics.

[0033] After 168 hours of aging at 120°C, the volume resistivity of the material presented in this invention remains stable at ±2.0% to 3.0%, compared to ±7% to 8% for conventional XLPE. By establishing a precise cross-linked network structure, this material significantly improves its ability to maintain electrical properties in long-term high-temperature environments, extending the product lifecycle.

[0034] 2. Existing insulating materials have problems such as "crosslinking blind spots" and "structural disorder" during electron beam modification, especially the difficulty in inducing orientation in the non-polar polyethylene main chain. The present invention solves these key structural problems through the following technical means:

[0035] The introduction of recombinant memory peptide modified chitosan microparticles produces transient conformational unfolding under microwave excitation and induces quasi-oriented motion of polyethylene chain segments at the nanoscale.

[0036] A low-frequency alternating electric field is applied synchronously to stimulate micro-oscillation of the PE chain segments within the microwave thermal softening window, forming a cooperative arrangement effect of non-polar chain segments;

[0037] Under the action of the electron beam, the free radicals generated by the cleavage of the polyether end groups undergo precise cross-linking along the pre-arranged chain segments to construct a longitudinally guided three-dimensional network.

[0038] This triple synergistic mechanism of microwave + electric field + electron beam has achieved the controllable directional cross-linking of non-polar polymer structures for the first time, completely getting rid of the disorder and embrittlement problems of the existing cross-linking mechanism at the structural level.

[0039] 3. Traditional cross-linking methods usually rely on high-temperature thermal cross-linking or peroxide cross-linking, which has problems such as many by-products, large equipment investment, and non-recyclability. In contrast, the present invention has the following technical advantages:

[0040] Microwave induction, electric field synergy and electron beam irradiation can all be integrated into continuous belt production lines, with precise energy consumption control, supporting intelligent joint control and Industry 4.0 standard transformation.

[0041] The entire process does not involve any chemical cross-linking agents or additives, and the product processing and use processes are non-toxic and harmless, meeting the requirements of sustainable development.

[0042] All functional materials are optimized based on natural modification or biodegradability, support customized adjustment and standard module replacement, and are suitable for a variety of application conditions.

[0043] 4. In actual engineering applications, the material of the present invention can be widely used in: 3.6-35kV medium-voltage cross-linked cable insulation layer; electric vehicle high-voltage wiring harness and charging pile cable system; photovoltaic cables, wind power system flexible high-temperature insulation layer; future aviation / rail system insulation structure with strong environmental adaptability and long aging life; in these scenarios that require flexibility, pressure resistance and environmental adaptability, the present invention provides an optimal solution for integrated structure and performance.

[0044] In summary, the present invention not only outperforms the existing technology in terms of performance, but also achieves a fundamental breakthrough in structural mechanism. Through reasonable material design and composite field energy induction strategy, a new system for preparing polyethylene insulation materials that is controllable, efficient, green and intelligent is constructed, which has significant industrialization prospects and broad technical scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the preparation method of the present invention;

[0046] Figure 2 Schematic diagram of the process of step 2 of the preparation method of the present invention;

[0047] Figure 3 Schematic diagram of the process of step 3 of the preparation method of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] See also Figure 1 The present invention relates to an electron beam modified polyethylene insulation material combined with microwave pretreatment, the insulation material comprising the following components in weight percentage:

[0050] Low-crystalline, highly branched linear polyethylene: 75% to 90%; linear low-density polyethylene, metallocene-catalyzed polyethylene, ultra-high molecular weight polyethylene modified by melt index adjustment, or bio-based PE prepared by cracking sugarcane ethanol can be selected; low-crystalline, highly branched linear polyethylene has good flexibility and breakdown strength, and can stably carry functional cross-linked networks; the branched structure provides "relaxation" conditions for chain response during microwave-induced and electron beam cross-linking, which is conducive to induced arrangement.

[0051] Recombinant memory peptide modified chitosan microparticles: 5% to 10%; the particle size of the recombinant memory peptide modified chitosan microparticles is 100 to 300 nm, and the microparticles exhibit transient conformational unfolding ability under microwave excitation to induce the arrangement and orientation of polyethylene chain segments; recombinant memory peptide modified chitosan microparticles can be selected from recombinant actin peptide-chitosan covalently grafted microparticles, hydrolyzable arginine-glutamic acid repeating peptide / chitosan complexes or thermosensitive allosteric short peptides and chitosan coatings; under microwave induction, the peptide structure of the recombinant memory peptide modified chitosan microparticles undergoes a "helical → linear" conformational transition, and the microparticles locally form an expansion-condensation dynamic interface; this interface induces micro-directional movement of the surrounding PE chain segments, providing a "template path" for subsequent electron beam-activated cross-linking.

[0052] Cleavable polyether copolymer with polar end groups: 3% to 10%; the main chain of the cleavable polyether copolymer contains terminal hydroxyl or ester structure, which can preferentially undergo segment cleavage and form cross-linking active sites under the action of electron beam; the cleavable polyether copolymer with polar end groups can be selected from polycaprolactone-polyethylene ether copolymer, polycaprolactone-polyethylene adipate, terminal diacrylate polyether or polysuccinic acid / polysebacic acid / polyether ternary block material; the hydroxyl, ester or double bond structure in the main chain of the cleavable polyether copolymer with polar end groups is preferentially broken during electron beam irradiation; after breaking, cross-linking active free radical centers are generated, which quickly bridge and bond with the arranged PE chain segments to form a three-dimensional dynamic network; it is the key to achieving the dual goals of "directional crosslinking + dynamic elasticity".

[0053] Phytosterol-quaternary ammonium salt block polymer: 1% to 2%, which can be selected from stigmasterol-PEG-b-PAE block copolymer, rosin phenol / kasonol and quaternary ammonium salt functionalized alcohol ether block or triglyceride-quaternary ammonium salt type amphiphilic structural material; the quaternary ammonium salt in the phytosterol-quaternary ammonium salt block polymer provides polarity guidance, and the sterol phenol part is embedded in the polyethylene chain segment to form a stable micro-interface; in the microwave induction stage, it can improve the uniformity of the distribution of chitosan particles in PE; in the electron beam stage, it can buffer the impact of chain segment breakage and prevent embrittlement caused by excessive cross-linking.

[0054] Antioxidant: 0.2% to 0.5% (optional). Tetraaryl hindered phenols, linear polymer antioxidants, DL-α-tocopherol, or butylated cresol can be used. Antioxidants primarily protect the PE backbone and polyether chains from excessive breakage during the electron beam stage; during the static cooling stage, they inhibit the non-selective diffusion of chain-end free radicals, improving the precision of the crosslinking network; and during use, they delay thermal aging and resist oxidation reactions, ensuring long-term insulation stability.

[0055] For further information, see Figure 1 , the preparation method of the insulating material comprises the following steps:

[0056] Step 1: Pre-drying treatment to remove surface and internal molecular water in the particles, copolymers and other components in the formula to prevent excessive heat absorption or unstable reactions during subsequent microwave induction. Specific operation: Use a hot air circulation drying oven, set the temperature to 40-60°C and dry for 8-12 hours.

[0057] The residual water at the interface between the particle surface and the matrix is desorbed at low temperature; this keeps the microwave / electric field energy transmission path clean, ensuring the effectiveness and uniformity of the downstream induction step.

[0058] Step 2, see Figure 2 The dried mixed material is treated in a microwave field with a frequency of 2.3 to 2.6 GHz and a power of 1.0 to 1.5 kW for 30 to 60 seconds to stimulate the memory response unit and induce the main chain configuration adjustment; the microwave treatment step is carried out in a reflective microwave cavity with a silver-plated ceramic inner wall and equipped with a rotary feeding mechanism; after the microwave induction step, a room temperature static cooling stage is set for 2 to 5 minutes to stabilize the primary alignment structure of the chain segments and enhance the cross-linking uniformity;

[0059] Microwaves primarily act on polar particles (recombinant peptide chitosan, block additives, and polyether end groups), stimulating their molecular rotation and conformational transitions. In particular, the recombinant peptide segments undergo a transient conformational change from a helical state to a linear state at specific temperatures and field strengths. The extended linear peptide chains pull adjacent polyethylene segments into a "chain-aligned distribution," providing a microscopic alignment force field. During this process, the chitosan particles undergo a slight volume expansion, forming a dynamic "expansion-retraction" interface. The stimulated polar segments produce localized thermal effects and chain oscillations, inducing localized softening of the nonpolar PE backbone. Under rotating feed, microwave irradiation is more uniform, inducing the segments to form primary alignment domains.

[0060] Furthermore, if the electron beam stage is quickly initiated after the microwave and electric field treatments are complete, the chain segments may not fully freeze their aligned configurations. A short period of quiescence at room temperature can "lock" the aligned segments in an undisturbed state, suppressing free rebound and preventing re-disordered bending of the segments, thereby improving the accuracy of subsequent cross-linking. During this process, the local microstructure gradually cools, and the dynamically expanded peptide segments return to a compacted state, but their "induced memory" remains in the PE segments, and the material enters the "static preset state" before cross-linking.

[0061] Step 3, see Figure 3 The microwave-treated material is placed in an electron beam device with an acceleration voltage of 0.7 to 1.5 MeV and an irradiation dose of 40 to 80 kGy to carry out directional chain cross-linking reconstruction; the electron beam irradiation step is carried out in a continuous belt conveyor system with a conveying speed of 5 to 15 m / min; the time interval between microwave induction and electron beam irradiation does not exceed 10 minutes, and the two steps are continuously set up on a production line to realize full-process automated modification;

[0062] Polyether copolymers with polar end groups preferentially cleave hydroxyl groups, ester groups, or double bonds under electron beam irradiation. Free radicals generated rapidly undergo a "bridging reaction" along the aligned chain segments. The combined effect of template alignment and directional free radical expansion forms a highly efficient, directional, and moderately dense three-dimensional crosslinked network. During this process, the electron beam excites free radicals as it penetrates the material. The recombinant peptide-induced region segments, already aligned and aligned, become the preferred crosslinking sites. This creates a longitudinally reinforced crosslinked domain on a macroscopic scale, enhancing both breakdown voltage and mechanical strength.

[0063] Step 4: Cool and solidify in an inert atmosphere such as nitrogen at 15-30°C to complete the structural shaping.

[0064] If natural cooling is too slow, free radicals may continue to propagate crosslinks, leading to "over-crosslinking embrittlement." Rapid cooling under nitrogen effectively terminates the reactive free radicals, maintaining the elastic balance of the crosslinked network and preventing oxidation reactions or residual free radical polymerization from causing micropores or breakage points in the structure. During this process, the crosslinking reaction is "locked in," and the antioxidant absorbs residual free radicals, protecting the chain segments from damage. The resulting molded material exhibits excellent flexibility, stability, and high electrical insulation.

[0065] Furthermore, the material has a breakdown field strength of ≥36 kV / mm, a tensile strength of ≥18 MPa, an elongation at break of >500%, and a volume resistivity change rate of ≤±5% after thermal aging for 168 hours (120° C.).

[0066] Furthermore, the material is suitable for 3.6-35kV grade cable insulation layers, photovoltaic cables, charging pile cables, high-voltage electric vehicle cables and other medium-voltage cable products.

[0067] In addition, although a rotary feeding + reflection cavity is used, the PE main chain is a non-polar and highly flexible molecule, and its responsiveness in the microwave field is much lower than that of the chitosan / polyether component. The microscopic arrangement area is difficult to continuously expand within the overall volume, especially for medium-thickness (>2mm) materials, the arrangement depth may have a limit. Therefore, in order to solve this problem, in step (2), a low-frequency alternating electric field is applied synchronously during the microwave induction stage, with a frequency of 3 to 10kHz and an electric field strength of 10 to 30V / mm. The alternating electric field is applied through insulating ceramic-coated electrodes set at both ends of the microwave cavity to form a micro-electric coupling field. This electric field works synergistically with the microwave field to further enhance the micro-directional ability of the polyethylene non-polar chain segment, expand the range of action of the arrangement effect in the material thickness direction, and effectively overcome the problem of insufficient microwave response of the non-polar chain segment.

[0068] Polyethylene is a non-polar molecule with a weak microwave response. Applying an alternating electric field during thermal softening of the chain segments can induce dipole micro-oscillations and chain segment tension resonance in the non-polar long chains. Superimposing oscillations during the "just softening" window facilitates chain segment straightening and pre-alignment. The electric field intensity is controllable, the effect is mild, and no electrical breakdown occurs. During this process, the polar polyether and chitosan particles absorb energy and heat up, and the non-polar PE segments also produce a tension-guided response due to the temperature and electric field oscillations. A semi-oriented segment alignment layer, generated by the synergistic action of "microwave + electric field," gradually forms in the material, reaching a depth of 2 to 4 mm. A significant alignment conformation is already present before standing, establishing a "molecular guidance path" for subsequent cross-linking.

[0069] With overall synergy, the induced area is no longer limited to the surface, but can form a semi-directional chain segment arrangement domain within a depth range of 2 to 4 mm; when irradiated by electron beams, these arranged chain links are more likely to capture free radicals and cross-link to form a longitudinally guided cross-linked network.

[0070] The following is a statistical analysis of the test results using the formula and process of the present invention and existing mainstream products:

[0071]

[0072]

[0073] The specimen type is a flat extruded sheet with a thickness of 2.5 mm, a width of 10 mm, and a length of 120 mm. The ambient temperature is 23 ± 2°C and the humidity is 50 ± 5% RH. All mechanical and electrical tests are performed under standard laboratory conditions. After preparation, the samples are placed in a drying oven at room temperature for 24 hours to release internal stress and prevent short-term shrinkage from affecting test accuracy.

[0074] 1. Breakdown field strength test (Standard: GB / T 1408.1-2016)

[0075] Voltage type: AC 50Hz; Rising rate: 500V / s; Electrode type: Φ25mm spherical copper electrode; Dielectric: Mineral oil to prevent surface flashover; Termination criterion: Record the value at the first electrical breakdown; Number of repetitions: Take 5 samples per group and calculate the average value and standard deviation;

[0076] 2. Tensile strength and elongation at break (according to GB / T 1040.3-2006)

[0077] Clamp spacing: 80 mm; tensile speed: 200 mm / min; gauge length: 50 mm; number of specimens: 5 / formula; termination condition: until breaking;

[0078] 3. Thermal aging resistivity change rate, (IEC 60216-1 / GB / T 2951)

[0079] Equipment: Electric constant temperature blast oven with automatic temperature control system; Aging temperature: 120±2℃; Aging time: 168 hours (7 days); Air flow rate: 0.5-1.0m / s; Test method: Volume resistivity test before and after aging, using a megohmmeter;

[0080] 4. Definition of applicable voltage levels (refer to IEC 60502)

[0081] According to the breakdown field strength ≥36kV / mm standard, it can be adapted to: 3.6 / 6kV (low-end applications); 6 / 10kV (distribution systems); 8.7 / 15kV, 12 / 20kV, 18 / 30kV (medium voltage systems); 21 / 35kV (high-end medium voltage systems).

[0082] Experimental analysis:

[0083] Stronger insulation performance: The breakdown field strength of the samples of the present invention exceeds 36kV / mm, while the existing mainstream products are only 30-31kV / mm, and the safety margin is significantly improved.

[0084] Flexibility and mechanical properties are superior to traditional ones: tensile strength and elongation at break are significantly better than XLPE and mPE systems, especially in highly flexible scenarios such as new energy vehicles and photovoltaics.

[0085] More stable under thermal aging: The volume resistivity of existing XLPE changes by more than +8% after aging, while this solution controls it within +2%, indicating that it is more reliable under long-term high-temperature operation.

[0086] The comprehensive application voltage level is higher: most of the samples of the present invention are adapted to the medium voltage level of 20 to 35 kV, while most of the existing products stop at less than 10 kV, and the engineering adaptability range is wider.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Electron beam modified polyethylene insulation material combined with microwave pretreatment, characterized in that, The material includes the following components in weight percentage: Low crystallinity highly branched linear polyethylene: 75% to 90%; Recombinant memory peptide modified chitosan microparticles: 5% to 10%; Cleavable polyether copolymer with polar end groups: 3% to 10%; Phytosterol phenol-quaternary ammonium salt block polymer: 1% to 2%; Antioxidant: 0.2%~0.5%.

2. The material according to claim 1, wherein the preparation method comprises the following steps: (1) Dry all components at 40-60°C for 8-12 hours; (2) treating the dried mixed material in a microwave field with a frequency of 2.3 to 2.6 GHz and a power of 1.0 to 1.5 kW for 30 to 60 seconds to stimulate the memory response unit and induce the main chain configuration adjustment; (3) placing the microwave-treated material in an electron beam device with an acceleration voltage of 0.7 to 1.5 MeV and an irradiation dose of 40 to 80 kGy to perform directional chain cross-linking reconstruction; (4) Cool and solidify in an inert atmosphere such as nitrogen at 15-30°C to complete the structural setting.

3. The method according to claim 2, wherein the microwave treatment step is carried out in a reflective microwave cavity having an inner wall of silver-plated ceramic and equipped with a rotary feeding mechanism.

4. The method according to claim 2, wherein the electron beam irradiation step is performed in a continuous belt conveyor system at a conveying speed of 5 to 15 m / min.

5. The polyethylene insulation material according to claim 1, wherein the breakdown field strength is ≥36 kV / mm, the tensile strength is ≥18 MPa, the elongation at break is >500%, and the volume resistivity change rate after heat aging for 168 hours (120°C) is ≤±5%.

6. The polyethylene insulation material according to claim 1, wherein the particle size of the recombinant memory peptide modified chitosan microparticles is 100-300 nm, and the microparticles exhibit transient conformational unfolding ability under microwave excitation to induce the arrangement and orientation of polyethylene chain segments.

7. The polyethylene insulation material according to claim 1, wherein the main chain of the cleavable polyether copolymer contains terminal hydroxyl groups or ester structures, which can preferentially undergo segment cleavage under the action of electron beams and form cross-linking active sites.

8. The preparation method according to claim 2, wherein a room temperature slow cooling stage is provided after the microwave induction step, the duration of which is 2 to 5 minutes, to stabilize the primary alignment structure of the chain segments and enhance the cross-linking uniformity.

9. The preparation method according to claim 2, wherein the time interval between microwave induction and electron beam irradiation does not exceed 10 minutes, and the two steps are continuously arranged on a production line to achieve full-process automated modification.

10. The polyethylene insulation material according to claim 1 is suitable for 3.6-35kV grade cable insulation layers, photovoltaic cables, charging pile cables, high-voltage electric vehicle cables and other medium-voltage cable products.

Images