106 results about "Dielectric loss factor" patented technology

The invention discloses a high-precision transformer fault detection method and system, relates to the technical field of transformer detection, is used for solving the problems of insensitive fault characterization and delayed diagnosis under a light load condition, and judges whether to enter a load judgment mechanism or not by acquiring input side access voltage information and counting low-load accumulated duration. When entering a load discrimination mechanism, detecting the start-stop behavior of a load branch and the temperature rise trend of a winding, calculating a light load index, identifying a light load state, carrying out region division on an iron core, collecting magnetic flux density data, and calculating iron loss balance characteristics aiming at iron loss deviation which is easy to occur under a light load condition; the insulation degradation coefficient is calculated by fusing the oil temperature peak value and the dielectric loss factor, and the abnormal index is generated with the iron loss balance characteristic, so that the early warning of the early hidden fault of the transformer can be realized in a light load scene in which the traditional temperature rise and current indexes are insensitive, and the operation reliability and maintenance efficiency of the transformer in a power distribution system are improved.

The invention discloses a flame-retardant epoxy resin adhesive with a low dielectric constant and a low dielectric loss factor as well as a preparation method and application of the flame-retardant epoxy resin adhesive, and belongs to the technical field of electrical insulating materials. The method comprises the following steps: uniformly mixing and stirring epoxy resin and alicyclic epoxy resin to obtain an epoxy resin mixture; uniformly stirring liquid acid anhydride, a flame retardant, an epoxy active toughening agent and an accelerant to obtain an epoxy resin curing agent; and vacuumizing and uniformly stirring the epoxy resin mixture and the epoxy resin curing agent to obtain the flame-retardant epoxy resin adhesive with low dielectric constant and low dielectric loss factor. Dielectric loss of the epoxy resin mixture is reduced through polarity complementation, and molecular chain segment polarization is reduced through an alicyclic epoxy resin ring structure. And the flame retardant is dispersed into a uniform flame-retardant phase in liquid anhydride, so that the mechanical property is prevented from being reduced. A flexibilizer and anhydride are grafted to introduce a flexible chain segment, vacuum mixing is performed to eliminate an air gap, and after gradient curing, a low dielectric constant, a low dielectric loss factor and flame retardance are obtained.

The present invention relates to a benzocyclobutene resin, a resin composition, and uses thereof. The benzocyclobutene resin comprises at least one structural unit A and at least one structural unit B, where structural unit A has a structure represented by Formula I and structural unit B has a structure represented by Formula II. The benzocyclobutene resin has an all-hydrocarbon structure and has a sufficiently low dielectric constant Dk and dielectric dissipation factor Df. The benzocyclobutene resin also has a high glass transition temperature, low water absorption, good heat resistance and moist heat resistance, excellent dielectric properties, high modulus, and mechanical properties. Furthermore, the benzocyclobutene resin also has good processability, fully meeting the performance requirements for resin materials in high-performance PCBs.

The present invention provides: a fluororesin film for a multilayer structure substrate, with which it is possible to produce, without using an adhesive, a multilayer structure substrate that has less transmission loss during high-frequency communication; a method for producing the fluororesin film for a multilayer structure substrate; a copper-clad laminate; a multilayer structure substrate; a method for producing a multilayer structure substrate; and a circuit board.　Disclosed is a fluororesin film for a multilayer structure substrate, which contains a fluororesin and an inorganic filler that is dispersed in the fluororesin, wherein the dielectric loss tangent Df is 0.0013 or less and the loss elastic modulus at a temperature of 350°C is 1.6 MPa or more. The fluororesin film for a multilayer structure substrate is used for the purpose of producing a multilayer structure substrate by bonding, without using an adhesive, a plurality of copper-clad laminates that have a two-layer structure in which a copper foil and the fluororesin film for a multilayer structure substrate are laminated.

The invention discloses an insulation detection method for cable windings of a phase modifier, and relates to the field of phase modifiers, and the method comprises the following steps: S1, sequentially embedding an A-phase cable, a B-phase cable and a C-phase cable into iron core grooves of a stator iron core to respectively form a corresponding A-phase winding, a B-phase winding and a C-phase winding, and the insulating layer of each phase cable is made of a crosslinked polyethylene material; s2, cable terminal connectors are mounted at the wire outlet end and the neutral end of each phase of winding and are grounded; s3, respectively carrying out insulation resistance detection test on each phase of winding; s4, respectively carrying out an alternating current withstand voltage test on each phase of winding; and S5, respectively carrying out dielectric loss factor detection test on each phase of winding. The device can detect the insulation performance of the cable winding of the direct-hanging phase modifier, and has the advantages of comprehensive detection and high reliability.

This invention discloses a multi-physics in-situ testing platform for aramid-synthetic ester composite insulating materials. The method includes: pre-treating an aramid substrate by drying and impregnation to obtain a composite sample; clamping the sample between test electrodes; applying a stable and controllable temperature field and an electric field to the sample sequentially or simultaneously; and measuring the dielectric constant, dielectric loss factor, and conductivity of the sample in situ under stable thermo-electric coupling conditions. The testing platform includes test electrodes for clamping the sample, a temperature control module for applying the temperature field, an electric field loading module for applying and adjusting the electric field, and a data acquisition module for in-situ data collection. By optimizing the sample pre-treatment process and the synchronous loading control of multi-physics fields, this invention achieves high-precision and highly repeatable in-situ testing of the dielectric properties of materials under actual service conditions within a wide temperature and field strength range. It is particularly suitable for evaluating the performance evolution of composite insulating materials under thermo-electric coupling.

This invention relates to a transformer body unit and an electromagnetic voltage transformer device. The transformer body unit includes an iron core element, a first coil element and a second coil element respectively housed on the lower and upper parts of the iron core element, a first shielding element and a second shielding element respectively housed on the first coil element and the second coil element, and a lower insulating element and an upper insulating element respectively housed on the first shielding element and the second shielding element. Its advantages are: by utilizing the upper and lower insulating elements, optimal electric field distribution is obtained, making the transformer device capacitive, effectively avoiding resonance between the electromagnetic voltage transformer device and circuit breaker capacitance, line-to-ground distributed capacitance, etc., ensuring the safe operation of the power grid; by using the transformer body unit, the diameter of the porcelain bushing unit can be reduced, reducing oil weight and overall weight; the upper and lower insulating elements give the product good electrical strength and insulation performance as well as a low dielectric loss factor; overcoming the disadvantages of unstable performance, poor transient performance, and small output capacity.

Embodiments in accordance with the present invention encompass compositions containing the polymer formed from a variety of polycycloolefinic monomers at least one of which monomer contains an additional unpolymerized ethylenic bond, melamine, clay such as bentonite or montmorillonite, optionally fillers such as hexagonal boron nitride or silica, a crosslinker, a free radical initiator, a tackifier and one or more suitable additives. The compositions of this invention can be formed into a variety of three-dimensional insulating articles upon exposure to suitable high temperature, such as for example films. The objects formed from the compositions of this invention exhibit hitherto unattainable low dielectric constant and low-loss properties, fire-retardancy and very high thermal properties. The compositions of this invention are useful in various applications, including as insulating materials in millimeter wave radar antennas, among others. The films formed from the compositions of this invention exhibit a UL-94 rating of at least V-1, dielectric constant (Dk) less than 2.9 and dielectric dissipation factor (Df) of less than 0.003.

The invention relates to the technical field of transformer oil treatment, in particular to an adsorption regeneration transformer oil purification system and a control method.The adsorption regeneration transformer oil purification system comprises an adsorption device, the output end of the adsorption device is fixedly connected with a transfer device through a pipeline, and the output end of the transfer device is fixedly connected with a cooling device through a pipeline; through composite adsorption and vacuum dehydration and degassing, the dielectric loss factor of oil is greatly reduced, the withstand voltage value is remarkably improved, the insulation breakdown risk of the transformer is effectively avoided, the service life of equipment is prolonged, energy waste is reduced through constant-temperature control, cooling water is recycled, consumables and water resource consumption are reduced, the operation and maintenance cost of enterprises is reduced, full-process PLC automatic control is achieved, and the production efficiency is improved. Multiple monitoring protection of vacuum, pressure, liquid level and the like is matched, frequent manual intervention is not needed, risks of pipeline pressure building, leakage and the like are avoided, the operation stability is improved, waste gas is subjected to multi-stage treatment of buffering, spraying and activated carbon adsorption, peculiar smell is avoided, up-to-standard emission is achieved, and pollution to the surrounding environment is reduced.

The invention provides a composite insulating layer of a light superconducting cable and a preparation method and application of the composite insulating layer. The composite insulating layer is prepared from the following raw materials in parts by weight: 40-60 parts of fusible polytetrafluoroethylene, 30-50 parts of fluorinated ethylene propylene, 0.5-5 parts of an auxiliary agent, 1-5 parts of filler and 0.1-0.6 part of a nucleating agent. The composite insulating layer of the light superconducting cable has relatively high tensile strength, relatively low dielectric constant and dielectric loss factor, good mechanical property and high insulating strength; compared with the prior art, the composite insulation layer has the advantages of low average cell diameter and high cell density, which indicates that a uniform and fine cell structure is formed in the composite insulation layer, the overall density of the material can be effectively reduced, the insulation layer is light, and the composite insulation layer can be applied to preparation of light superconducting cables for medical equipment and realizes integrity and low loss of high-frequency signal transmission.

The invention relates to an intrinsic flame-retardant low-dielectric epoxy resin. The molecular structure of the epoxy resin comprises a) a biphenyl group, and at least one of b) a polyphenylene oxide (PPO) group, c) a polyether sulfone (PES) group or d) a polyamide imide (PAI) group. The preparation method comprises the following steps: dissolving biphenyl epoxy resin in a solvent, adding a polymer with an active group, adding independently or in a certain proportion in a combined manner, fully dissolving, adding a catalyst, heating, and carrying out solution polymerization; and after the reaction is finished, supplementing the solvent to prepare the solvent type modified epoxy resin. The obtained product can improve the limit oxygen index of the epoxy resin, reduce the dielectric constant Dk and the dielectric loss factor Df, realize a greener and more environment-friendly flame-retardant target, and better adapt to the performance requirements of high-end electronic products on high-speed transmission and low loss of electric signals.

Provided is a resin sheet which withstands adsorption and transportation by a vacuum adsorption pad for transportation, has low thermal expansion, and has a relative dielectric constant (Dk) of 2.50 to 3.30 in a high frequency band of 10 GHz band or more, and a dielectric dissipation factor (Df) of 0.0020 or less in a high frequency band of 10 GHz band or more. In addition, provided are a laminate, a printed wiring board, and a semiconductor package produced using the resin sheet. The resin sheet is specifically a resin sheet including a resin component (A), and an inorganic filler (B), in which the component (A) contains an elastomer (A1) having a number-average molecular weight of 10,000 or more, a content of the component (B) is 25 to 70 volume % based on a total amount of the resin sheet, and a breaking energy is 0.1 mJ / mm3 or more.

The application discloses a kind of 110kV capacitor voltage transformer does not remove lead test method, comprising, by through-type current transformer, the test current flowing through primary lead is converted into secondary current;Utilize negative feedback amplification circuit to amplify the secondary current of the through-type current transformer, and the through-type current transformer is shielded and protected by full metal shield cover;The amplified through-type current transformer is connected into Xilin bridge, and the main capacitance, the voltage dividing capacitance, the main capacitor dielectric loss factor and the voltage dividing capacitor dielectric loss factor of the through-type current transformer are calculated.The application does not need to remove and restore high voltage lead, does not need high place operation, work intensity is greatly reduced, eliminates the risk of falling in high place operation;At the same time, accurate measurement of capacitance and dielectric loss can be realized.

The application discloses a kind of high-voltage transmission and distribution line equipment insulation aging monitoring method and system, it is related to equipment insulation state monitoring technical field, including, extracting voltage time-frequency feature matrix in voltage time series data set voltage time-frequency feature generation;Through the current mode component of separating current signal, output double-channel feature pair;Call high-voltage equipment standard parameter, according to double-channel feature pair calculation dielectric loss factor, through quantum tunneling effect eliminates measurement deviation and obtains correction dielectric loss factor;The frequency response characteristics of correction dielectric loss factor are analyzed, the aging type is judged by identifying offset mode, and the equipment aging degree coefficient is calculated to divide state grade;Based on aging type generation processing scheme, and according to state grade to obtain execution priority, through binding time stamp to generate maintenance instruction set.The application is combined with dynamic maintenance decision optimization response time by quantum tunneling effect, realizes the closed-loop management of insulation aging from accurate monitoring to active protection.

The application relates to an insulation and dielectric loss test switching device, a test system and a test method. The insulation and dielectric loss test switching device comprises a shell, a static contact, a conductive part, a limiting assembly and a reset part. The static contact is used for grounding. The conductive part has a connecting part and is in sliding connection with the shell and can be moved to a first position and a second position. The limiting assembly is used for limiting the movement of the conductive part relative to the shell when the conductive part is in the second position. The reset part is used for driving the conductive part to move from the second position to the first position when the limiting assembly removes the limitation of the conductive part. The structure to be measured is electrically connected with the conductive part. When the conductive part is located at the first position, the conductive part is separated from the static contact. The connecting part is used for electrically connecting an insulation resistance detector to detect the insulation resistance. When the conductive part is located at the second position, the conductive part is electrically connected with the static contact. The connecting part is used for electrically connecting a dielectric loss detector to detect the dielectric loss factor. Therefore, different equipment can be quickly switched to complete corresponding detection.

The invention discloses a current collection cable line fault positioning and hidden danger identification method, system and device and a medium, and belongs to the technical field of current collection cable line fault analysis, and the method comprises the steps: setting a plurality of measuring points on a current collection cable line to collect fault traveling wave signals, and obtaining the traveling wave current waveform of each measuring point; acquiring dielectric constant distribution and dielectric loss factor distribution of each cable section by analyzing propagation characteristics of traveling wave current waveforms among different measuring points; taking the dielectric constant and the dielectric loss factor as two-dimensional feature vectors, and calculating an insulation degradation index of each cable section through coupling analysis; dividing a degradation section according to the numerical distribution of the insulation degradation index; determining the coordinates of a fault breakdown point according to the polarity reversal position of the traveling wave current waveform; and marking a first-level insulation hidden danger point and a second-level insulation hidden danger area. According to the method, the problem of positioning errors caused by constant wave velocity hypothesis is solved, and the fault positioning precision and the hidden danger recognition accuracy are remarkably improved.

This patent discloses a heated cigarette with a water-containing capsule. The heated cigarette is heated in a high-frequency electric field with a frequency of 1MHz to 900MHz. The smoking section of the heated cigarette contains the water-containing capsule and anti-detuning hydrated salt, allowing for a gradient release of moisture during heating to control the dielectric loss factor. When the smoking section is heated to 25-150℃, the dielectric loss factor ε" remains between 18-35; when the smoking section is heated above 150℃, the dielectric loss factor ε" remains between 8-15. This patent maintains control over the dielectric loss factor by releasing water at different stages of heating, ensuring that the heated cigarette, after reaching 350℃, remains at approximately 350℃ until the end of smoking. The energy of the high-frequency electric field is always effectively converted into heat energy, preventing "heating failure" or "dry burning" and improving the smoking experience.

This application discloses a method and apparatus for predicting the electrical risk of oil-paper insulated equipment. The method includes: acquiring multiple oil and gas sample data with labels and confidence levels from the oil-paper insulated equipment at different time windows; generating a molecular model formulation of the mixture; constructing a molecular simulation mixture model of the mixture formulation at the current temperature; and performing geometric optimization, model annealing, and ensemble balancing to obtain a steady-state model. The method then calculates the total dipole moment of the molecular dynamics system of the steady-state model and the dielectric loss factor, using the planned quantitative value of the dielectric loss factor to assess the degree of electrical risk of the oil-paper insulated equipment. Therefore, this method provides a mechanistic and quantitative mapping from monitoring data to electrical risk, accurately calculates real-time dielectric parameters, considers individual equipment differences, quantifies risk values, and classifies them, improving the accuracy of early degradation identification and thus enhancing the accuracy of electrical risk monitoring for oil-paper insulated equipment.

This invention discloses a cross-linked polyethylene insulation material resistant to electrical tree aging for medium and high voltage cables, relating to the technical field of cross-linked polyethylene insulation materials for medium and high voltage cables. The material comprises an insulation composition consisting of polyethylene resin, a reactive precursor, and a peroxidation cross-linking agent, formed by cross-linking, and includes a main insulation layer region and an interface-confined reactive layer located on at least one side of the surface. Through the combination of the multifunctional molecular structure design of the reactive precursor and a three-layer co-extrusion continuous vulcanization process, the spatiotemporal synergy of three functions—deep trap construction, covalent network anchoring, and in-situ capture of cross-linking byproducts—is achieved in the micro-region of the insulation-semiconductive interface. This allows for the in-situ formation of an interface-confined reactive layer with high reactivity, deep trap energy levels, and low byproduct residue characteristics on the interface surface without significantly increasing the overall dielectric loss factor of the material, thereby improving the ability of the medium and high voltage cable insulation layer to inhibit electrical tree aging.

This invention discloses a method, apparatus, terminal equipment, and storage medium for power equipment condition assessment, belonging to the technical field of power equipment operation assessment. The method involves: acquiring structured and unstructured data of the power equipment; wherein the structured data includes: insulation resistance, oil gas concentration, dielectric loss factor, and DC resistance imbalance coefficient; and the unstructured data includes: infrared thermographic images and ultraviolet discharge images; generating a first membership degree of the structured data to each condition category based on the structured data; generating a second membership degree of the unstructured data to each condition category based on the unstructured data; calculating a comprehensive membership degree for each condition category based on the first and second membership degrees; and taking the condition category with the highest comprehensive membership degree as the power equipment condition assessment result. This invention, based on structured and unstructured data, improves the accuracy of power equipment condition assessment.

The invention discloses a method for evaluating the aging performance of flame-retardant insulating oil, and relates to the technical field of performance evaluation of insulating materials of power equipment, and the method comprises the following steps: S1, sample preparation; s2, a sequential coupling aging test: sequentially performing an accelerated thermal aging test and a disruptive discharge aging test on the flame-retardant insulating oil sample; s3, performance parameter testing and characteristic rule identification: testing a flash point, a breakdown voltage, a dielectric loss factor tan delta and an acid value of the sample at different stages of the sequential coupling aging test; analyzing an evolution rule of a flash point along with thermal aging time, change characteristics of a breakdown voltage in thermal aging and breakdown discharge aging processes, and change trends of a dielectric loss factor and an acid value; and S4, comprehensive performance and service life evaluation. According to the invention, through a sequential coupling aging test, a complex working condition of a thermal-electric stress synergistic effect in the transformer is comprehensively simulated, and the limitation of a traditional single aging mode is overcome.

The invention discloses a method and a system for calculating and monitoring section insulation parameters of a crossed and interconnected cable, and belongs to the technical field of high-voltage power cable state monitoring. In order to solve the problems that in existing long-distance cross interconnection high-voltage cable insulation monitoring, reference voltage selection is not accurate due to distribution parameters, leakage current coupling is difficult to separate due to a cross interconnection structure, and consequently an insulation degradation section cannot be accurately positioned, the method comprises the steps that a cable is a three-phase high-voltage cable, the metal sheath adopts a cross interconnection grounding mode, and a cross interconnection system comprises two groups of grounding boxes and transposition boxes; arranging current sensors on coaxial cables at the grounding box and the transposition box, and acquiring the current of each measuring point; separating current components flowing through metal protective layers of the A-phase cable, the B-phase cable and the C-phase cable; calculating insulation parameters of each segmented cable; the insulation parameters comprise equivalent resistance of the cable insulation, a dielectric loss factor and resistive current flowing through the cable insulation. The invention is used for the high-voltage power cable.

The invention relates to the technical field of food processing automation control, and discloses a bone soup enzymolysis process and oil-water separation production control system based on a multi-source sensor, which comprises an acoustic reaction kettle, a sound field driving execution subsystem, a multi-source sensing subsystem and an edge calculation control subsystem. The multi-source sensing subsystem collects complex dielectric constants of bone soup materials in real time through dielectric probes arranged at theoretical sound pressure nodes and antinode positions in the acoustic reaction kettle. And the edge calculation control subsystem calculates the absolute value of the difference value of the real parts of the nodal and antinode position dielectric constants, generates a frequency adjustment instruction based on the maximum search result of the difference value, and sends the frequency adjustment instruction to the sound field driving execution subsystem to lock the resonance frequency of the sound field. The system monitors the enzymolysis degree by using a high-frequency dielectric loss factor, and controls a sound field to switch between a cavitation-assisted enzymolysis mode and a standing wave oil-water separation mode. The problem of sound field detuning caused by bone soup physical property change is solved, and self-adaptive closed-loop control over the whole enzymolysis and separation process is achieved.

The invention discloses a partial discharge detection and positioning method, an insulation state prediction method and a monitoring system. The detection method comprises the steps that multiple physical quantity signals are synchronously collected from the same monitoring point, the multiple physical quantity signals comprise ultrahigh frequency signals, ultrasonic signals and dielectric loss factor changes, feature extraction is conducted on the multiple physical quantity signals to obtain multiple physical quantity features, fusion analysis is conducted on the multiple physical quantity features, and the discharge type is recognized. The dielectric loss factor change is introduced into online partial discharge detection as a core quantitative index and is fused with an ultrahigh frequency signal and an ultrasonic signal, and a direct physical quantity basis is provided for prediction of discharge types. The positioning method comprises the steps that through mutual verification and evidence fusion of ultrahigh frequency time difference positioning and ultrasonic wave array beam forming positioning, physical constraint is carried out through an amplitude attenuation model of dielectric loss factor changes, the problems that positioning is not accurate and is prone to interference in a single method are solved, and the positioning precision and reliability are greatly improved.

The embodiment of the invention discloses an insulation monitoring and early warning method and device for high-voltage equipment, equipment and a medium. A specific embodiment of the method comprises the steps of obtaining a multi-source signal set corresponding to high-voltage equipment in a smart power grid; performing interference separation processing on the partial discharge pulse signal to obtain a processed partial discharge pulse signal; performing first regulation and control processing on the high-voltage equipment based on the processed partial discharge pulse signal and the temperature distribution signal; performing optimization processing on the dielectric loss factor signal based on the temperature distribution signal to obtain an optimized dielectric loss factor signal; performing second regulation and control processing on the high-voltage equipment based on the processed partial discharge pulse signal and the optimized dielectric loss factor signal; and executing early warning processing according to the acquired first identification information and second identification information. According to the embodiment, insulation on-line monitoring and early warning are achieved, and a reliable decision basis is provided for safe operation and maintenance and reliable management of high-voltage equipment in an intelligent power grid.

The invention belongs to the field of high-frequency communication materials, and particularly discloses a Low-alpha ray spherical alumina / liquid crystal polymer 5G base station substrate material, which is characterized by comprising a liquid crystal copolymer matrix and a Ce < 3 + > doped spherical alumina filler, the liquid crystal copolymer matrix is prepared from three comonomers, namely 60 to 68 mol percent of p-hydroxybenzoic acid, 20 to 24 mol percent of 5, 5 '-dithiobis (2-nitrobenzoic acid) and 12 to 16 mol percent of 4-(5-amino-6-hydroxy-2-benzoxazole)-benzoic acid; the surface of the Ce < 3 + >-doped spherical alumina filler is sequentially coated with a Bi2Te3-xSex topological insulating layer and a phosphate silane grafting layer, wherein x is equal to 0.12-0.18. According to the Low-alpha ray spherical aluminum oxide / liquid crystal polymer 5G base station substrate material, the alpha ray shielding rate is larger than or equal to 99.95%, the heat conductivity is larger than or equal to 3.35 W / mK, the dielectric loss factor tan delta is smaller than 0.00014 under 28 GHz, and the strict requirements for high frequency, high reliability and the like of a substrate in 5G millimeter wave antenna application can be met.

Embodiments in accordance with the present invention encompass compositions containing a blend of polymers formed from a variety of polycycloolefinic monomers at least one of which monomer contains an olefinic functionality and another monomer contains an anhydride functionality, melamine, montmorillonite and optionally other fillers such as silica, a crosslinker, a free radical initiator, a tackifier and one or more suitable additives. The compositions of this invention can be formed into a variety of three-dimensional insulating articles upon exposure to suitable high temperature, such as for example films. The objects formed from the compositions of this invention exhibit hitherto unattainable low dielectric constant and low-loss properties, fire retardancy and very high thermal properties. The compositions of this invention are useful in various applications, including as insulating materials in millimeter wave radar antennas, among others. The films formed from the compositions of this invention exhibit a UL-94 rating of at least V-1, dielectric constant (Dk) less than 2.8 and dielectric dissipation factor (Df) of less than 0.002.

The application provides a method, system and medium for evaluating the dielectric stability of resin after long-term thermal oxygen aging, and belongs to the technical field of insulation material performance testing. The method performs a long-term aging experiment on H-grade resin in a thermal oxygen environment with a temperature of 245 DEG C + / - 2 DEG C to 250 DEG C + / - 2 DEG C and an oxygen concentration of 21% + / - 2%, and collects dielectric constant, dielectric loss factor and volume resistivity data in a frequency range of 50 Hz to 10 MHz. Three core indexes, i.e., dielectric constant fluctuation rate, dielectric loss growth coefficient and resistivity attenuation index, are defined to accurately and quantitatively evaluate the dielectric performance stability of H-grade resin after long-term thermal oxygen aging. Compared with the traditional method, the method solves the defects of short evaluation period, single frequency range and fuzzy indexes of the traditional method, the evaluation result is consistent with the actual service failure with a coincidence degree of greater than or equal to 92%, and is suitable for resin selection and life prediction of high-end equipment.

Embodiments in accordance with the present invention encompass compositions containing the polymer formed from a variety of polycycloolefinic monomers at least one of which monomer contains an additional unpolymerized ethylenic bond, melamine, clay such as bentonite or montmorillonite, optionally fillers such as hexagonal boron nitride or silica, a crosslinker, a free radical initiator, a tackifier and one or more suitable additives. The compositions of this invention can be formed into a variety of three-dimensional insulating articles upon exposure to suitable high temperature, such as for example films. The objects formed from the compositions of this invention exhibit hitherto unattainable low dielectric constant and low-loss properties, fire-retardancy and very high thermal properties. The compositions of this invention are useful in various applications, including as insulating materials in millimeter wave radar antennas, among others. The films formed from the compositions of this invention exhibit a UL-94 rating of at least V-1, dielectric constant (Dk) less than 2.9 and dielectric dissipation factor (Df) of less than 0.003.

An α-olefin-cyclic olefin-aromatic vinyl compound-aromatic polyene copolymer, the copolymer in an uncured state having: a dielectric constant of less than 2.5 and a dielectric loss tangent of less than 0.0007 at a measurement frequency of 40 GHz; and a storage modulus of less than 1,000 MPa as measured at 25°C.