Epoxy / acid anhydride crosslinking model thermal aging process dielectric constant calculation method and system based on molecular simulation

Abstract

The application discloses a kind of based on molecular simulation's epoxy / anhydride crosslinking model thermal aging process dielectric constant calculation method and system, including in software establishment epoxy resin monomer and anhydride curing agent molecular model and geometry optimization, the optimized molecular model is placed in cubic lattice and is mixed uniformly, forms amorphous cell structure;Epoxy resin monomer and the crosslinking script of anhydride curing agent are designed, and preset crosslinking reaction condition, according to crosslinking script and the preset crosslinking reaction condition makes epoxy resin monomer and anhydride curing agent molecule crosslinking reaction, forms stable crosslinking epoxy resin molecular model;Using software to simulate the aging characteristics of epoxy resin material under high temperature condition, finally, the relative dielectric constant of thermal aging process is calculated by statistical average dipole moment.Effectively solve the problem that stable dielectric constant cannot be obtained during epoxy resin accelerated thermal aging test process, and reduce test time, reduce test cost.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin materials technology, and more specifically to a method for calculating the dielectric constant of the epoxy / anhydride crosslinking model during thermal aging based on molecular simulation. Background Technology

[0002] Epoxy resin reacts with a curing agent to form a thermosetting material with a three-dimensional cross-linked network. This material possesses unique and excellent properties such as low shrinkage, easy curing, high breakdown strength, and stable chemical properties, making it widely used in electrical insulation. In particular, the epoxy / anhydride curing system exhibits high insulation performance and is one of the most commonly used insulation material substrates. With the development of high-voltage and ultra-high-voltage power transmission and transformation technologies in power systems, the size of electrical equipment is constantly shrinking, placing more stringent requirements on the insulation performance and aging resistance of epoxy resin insulation materials.

[0003] The relative permittivity is a key property of insulating materials, characterizing their degree of polarization. Under prolonged heating, the relative permittivity of insulating materials gradually increases. This leads to increased charging current and heat loss due to polarization, resulting in excessively high local temperatures, decomposition of the insulating material, and reduced insulation performance. Therefore, studying the changes in the relative permittivity of insulating materials during thermal aging is particularly important.

[0004] Traditional accelerated thermal aging tests are often affected by factors such as preparation process, test materials, and test conditions, resulting in fluctuating results that fail to accurately reflect the changes in the dielectric properties of epoxy resins under high-temperature conditions. Furthermore, traditional accelerated thermal aging tests are lengthy, requiring continuous operation of the temperature control equipment, which reduces the equipment's lifespan and consumes significant electrical resources, especially given the stringent requirements for sample preparation. Moreover, the service environment of the test material differs from the testing environment, with the service environment often being higher. Since the relative permittivity is highly sensitive to temperature, the relative permittivity measurement results obtained in the testing environment cannot directly reflect the dielectric properties of the test material during service.

[0005] Therefore, based on existing technology, it has been found that relying solely on traditional accelerated thermal aging tests to study the aging characteristics of epoxy resin cannot yield stable and reliable relative permittivity measurement results, and will also consume a lot of time and electricity resources. Summary of the Invention

[0006] In view of this, the present invention provides a method and system for calculating the dielectric constant of the epoxy / anhydride crosslinking model thermal aging process based on molecular simulation, so as to solve the problems in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On the one hand, the method for calculating the dielectric constant of the epoxy / anhydride crosslinking process based on molecular simulation is as follows:

[0009] S1. In MaterialStudio software, build molecular models of epoxy resin monomer DGEBA and curing agent THPA, and preprocess the molecular models.

[0010] S2. Mix an appropriate amount of epoxy resin monomer DGEBA and curing agent THPA thoroughly to obtain a lattice containing several epoxy resin monomers DGEBA and curing agent THPA.

[0011] S3. Bonding is performed on R1, R2, R3, and R4 within the lattice obtained in S2 to obtain an initial molecular model of crosslinked epoxy resin that meets the preset degree of crosslinking.

[0012] S4. Under the COMPASS force field, the initial model obtained in S3 is subjected to structural optimization and energy minimization to obtain a cross-linked epoxy resin molecular model for thermal aging simulation.

[0013] S5. Based on the reactive force field, perform NPT kinetic calculations on the cross-linked epoxy resin molecular model obtained in S4 for thermal aging simulation to simulate the actual thermal aging process.

[0014] S6. Based on the trajectory file generated by the NPT kinetic calculation in S4, track the small molecules CO2, H2O, CO, H2, and CH4 generated during the thermal aging process, extract their coordinates, and draw the spatiotemporal motion trajectory.

[0015] S7. In the trajectory file obtained in S5, small molecules that cannot be adsorbed by the cross-linked epoxy resin molecular model and thus escape from the molecular model are deleted to obtain the remaining solid material; the dipole moment of the remaining solid material is statistically analyzed, and the relative permittivity of the cross-linked epoxy resin during the aging process is calculated using the relative permittivity formula.

[0016] Preferably, in the above-described method for calculating the dielectric constant of the epoxy / anhydride crosslinking model during thermal aging based on molecular simulation, in step S1, the molecular models of the epoxy resin monomer DGEBA and the curing agent THPA are pretreated, and the pretreatment includes:

[0017] S2.1 The C atom at the end of the epoxy group and the O atom in the hydroxyl group of DGEBA are labeled as R1 and R4, respectively; the C atom of the carboxyl group and the O atom at the top of the curing agent THPA are labeled as R3 and R2, respectively.

[0018] S2.2 Remove the chemical bonds between R1 and R4, and between R2 and R3.

[0019] Preferably, in the above-mentioned method for calculating the dielectric constant of the epoxy / anhydride crosslinking model thermal aging process based on molecular simulation, in step S3, bonding is performed on R1, R2, R3, and R4, and the bonding includes:

[0020] S3.1 Perform NVT dynamics calculations on the lattice in S2, setting the temperature to 500K, to obtain the trajectory file;

[0021] S3.2 For the last frame of the trajectory file in S3.1, calculate the distance between the corresponding reaction atoms;

[0022] S3.3 When the distance between reacting atoms is less than the bonding radius, use the CreatBond command to connect the two reacting atoms to form a cross-linked chemical bond; at the same time as forming the cross-linked chemical bond, change the name of the reacting atom to reacted;

[0023] S3.4 Performs geometric optimization on the molecular model to ensure that the bond lengths of the cross-linked chemical bonds in S3.3 are within a reasonable range;

[0024] S3.5 Calculate the crosslinking degree of the molecular model; if the crosslinking degree of the molecular model does not meet the expectation, increase the bonding radius in S3.3, and repeat S3.1, S3.2, S3.3, and S3.4 until the molecular model meets the preset crosslinking degree.

[0025] Preferably, in the above-mentioned method for calculating the dielectric constant of the epoxy / anhydride crosslinking model during thermal aging based on molecular simulation, in step S4, the initial model undergoes structural optimization and energy minimization processing, which includes:

[0026] S4.1 Set the pressure to 0.5 GPa, perform NPT kinetic calculations on the initial model obtained in S3, and compress the volume of the initial model until it meets the actual density requirements; after the compression process is completed, a cross-linked epoxy resin molecular model that meets the actual density requirements is obtained.

[0027] S4.2 The cross-linked epoxy resin molecular model obtained in 4.1 that meets the requirements of actual density is annealed at 298K to 598K to cause the molecular chains to fold and shrink; after the annealing process, a cross-linked epoxy resin molecular model with folded and shrunken molecular chains is obtained.

[0028] S4.3 Perform NPT and NVT kinetic calculations on the cross-linked epoxy resin molecular model with molecular chain folding and shrinkage obtained in S4.2, and check the density and energy fluctuations during the calculation process; when the density and energy fluctuations are less than 10% of the average, the cross-linked epoxy resin molecular model enters a stable state, and a cross-linked epoxy resin molecular model for thermal aging simulation is obtained.

[0029] Preferably, in the above-described method for calculating the dielectric constant of the epoxy / anhydride crosslinking model thermal aging process based on molecular simulation, step S6 involves tracking small molecule substances generated during the thermal aging process, the tracking including:

[0030] S4.1 Extract the centroid coordinates of small molecules in each frame of the trajectory file in S5 and store them in the corresponding time table cell to obtain the temporal position table of a specific small molecule.

[0031] S4.2 Based on the temporal position table of the specific small molecules obtained in S4.1, draw the spatiotemporal trajectory of the specific small molecules;

[0032] S4.3 When the spatiotemporal trajectory of a specific small molecule obtained in S4.2 exceeds the range of the cross-linked epoxy resin molecule model used for thermal aging simulation in S4, the centroid coordinates of the excess molecule are marked with color.

[0033] Preferably, in the above-mentioned method for calculating the dielectric constant of the epoxy / anhydride crosslinking model thermal aging process based on molecular simulation, the relative dielectric constant formula in S7 is calculated based on the variance of the dipole moment, and its specific form is as follows:

[0034]

[0035] Where ε represents the relative permittivity, ε0 ​​represents the vacuum permittivity, M represents the electric dipole moment, V represents the dielectric volume, kB represents the Boltzmann constant, T represents the temperature, and <> represents averaging.

[0036] On the other hand, a system for calculating the dielectric constant of an epoxy / anhydride crosslinking model during thermal aging based on molecular simulation includes:

[0037] The molecular model building module, in MaterialStudio software, builds molecular models of epoxy resin monomer DGEBA and curing agent THPA, and preprocesses the molecular models.

[0038] The lattice building module fully mixes an appropriate amount of epoxy resin monomer DGEBA and curing agent THPA to obtain a lattice containing several epoxy resin monomers DGEBA and curing agent THPA.

[0039] The first molecular model construction module bonds R1, R2, R3, and R4 within the obtained lattice to obtain an initial molecular model of cross-linked epoxy resin that meets the preset degree of cross-linking.

[0040] The second molecular model construction module performs structural optimization and energy minimization on the initial molecular model of cross-linked epoxy resin obtained by the first molecular model construction module under the COMPASS force field, which meets the preset cross-linking degree, to obtain a cross-linked epoxy resin molecular model for thermal aging simulation.

[0041] The thermal aging process simulation module performs NPT kinetic calculations on the cross-linked epoxy resin molecular model obtained for thermal aging simulation based on the reactive force field, thus simulating the actual thermal aging process.

[0042] The spatiotemporal motion trajectory drawing module, based on the trajectory file generated by NPT dynamics calculation, tracks small molecules such as CO2, H2O, CO, H2, and CH4 generated during thermal aging, extracts their coordinates, and draws the spatiotemporal motion trajectory.

[0043] In the obtained trajectory file, the calculation module deletes small molecules that cannot be adsorbed by the cross-linked epoxy resin molecular model and thus escape from the molecular model, obtaining the remaining solid material; the dipole moment of the remaining solid material is statistically analyzed, and the relative permittivity of the cross-linked epoxy resin during the aging process is calculated using the relative permittivity formula.

[0044] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method and system for calculating the dielectric constant of the epoxy / anhydride crosslinking model thermal aging process based on molecular simulation. This method can simulate and analyze the aging characteristics of epoxy resin with lower time and material costs, and can be used for preliminary research on epoxy resin materials and further development of subsequent experiments. This significantly improves the efficiency of aging characteristic test research and is of great significance for the study of the aging mechanism and aging inhibition of epoxy resin materials. At the same time, the molecular dynamics simulation method solves the difficulty in obtaining stable and reliable relative dielectric constant measurement results in the accelerated thermal aging test of epoxy resin for studying its aging characteristics in the prior art. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0046] Figure 1 This is a diagram illustrating the reaction mechanism between epoxy resin and anhydride curing agent in this invention.

[0047] Figure 2 This is a flowchart of the crosslinking script designed for the dielectric constant calculation method of the thermal aging process of epoxy / anhydride cured composite crosslinking model based on the reactive force field of the present invention.

[0048] Figure 3 This is the cross-linked epoxy resin model with a cross-linking degree of 95% in this invention;

[0049] Figure 4 This is a flowchart of the method of the present invention. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] To achieve rapid analysis of the aging characteristics of epoxy resin under high temperature conditions and to explore its aging mechanism at the microscopic atomic level, this invention uses MS software to model the molecular model of epoxy resin material, uses the ReaxFF reactive force field in the GULP module of MS software to simulate the aging characteristics of epoxy resin material under high temperature conditions, and finally calculates the relative permittivity of the thermal aging process by statistical average dipole moment.

[0052] This invention discloses a method for calculating the dielectric constant of an epoxy / anhydride crosslinking model during thermal aging based on molecular simulation.

[0053] S1. Molecular models of epoxy resin monomer DGEBA and tetrahydrophthalic anhydride curing agent THPA were established using MaterialsStudio software. The geometry of these two molecular models was optimized using the Forcite module to obtain the configuration with the lowest energy. Then, the C atom at the end of the epoxy group and the O atom in the hydroxyl group of DGEBA were labeled as R1 and R4, respectively. The C atom of the carboxyl group and the O atom at the top of the tetrahydrophthalic anhydride were labeled as R3 and R2, respectively. The chemical bonds between R1 and R4 and between R2 and R3 were deleted to perform pre-ring-opening treatment.

[0054] S2, using the AmorphousCell module, the two optimized molecular models were mixed uniformly in a cubic lattice at a 1:2 ratio. In this example, 50 epoxy resin monomer molecules and 100 tetrahydrophthalic anhydride curing agent molecules were added respectively, with a curing density of 0.1 g / cm³. 3The initial density was determined, and periodic boundary conditions were applied to the cube to eliminate boundary effects and make the model closer to reality. The established model system was a mixture of epoxy resin and curing agent with a 1:1 ratio of reactive functional groups. The Forcite module was used again to perform geometric optimization on the cubic lattice to obtain the molecular structure model with the lowest energy. The optimized model was then subjected to NVT kinetic calculations at a temperature of 500K for a duration of 2000ps to relax the molecular system model.

[0055] In molecular dynamics simulations, the reaction conditions are simplified by using a case where no accelerator is present.

[0056] S3, see S3. Figure 1 Based on the cyclic reaction mechanism of epoxy groups of epoxy resin monomers and acid anhydride curing agents, a crosslinking script for epoxy resin and acid anhydride curing agents was designed, namely a Perl language script, and the crosslinking reaction conditions were preset, including a preset initial bonding radius of 4A, an increase of 0.5A in distance for each iteration, until a preset degree of crosslinking is reached, which is 90%.

[0057] Design the cross-linking script; refer to the specific process. Figure 2 The process involves reading in a predefined list of reactant atoms, setting an initial bonding radius, and then using the script to search for and locate reactant atoms by name. The script then calculates the distance between reactant atoms and compares it to the bonding radius. If the distance is less than the bonding radius, a cross-linking reaction is performed first, followed by a second geometry optimization. If the distance is greater than the bonding radius, the bonding radius is increased, the reactant atom list is updated, and the process returns to the initial reactant atom search and location step. This process is repeated until the preset cross-linking degree is reached.

[0058] During the cross-linking reaction, care should be taken to avoid excessive bonding of reacting atoms. When performing the bonding operation, the names of reacting atoms that have participated in bonding should be promptly modified and removed from the reacting atom list.

[0059] S4. Set the pressure to 0.5 GPa and perform NPT kinetic calculations on the initial model that has reached the preset crosslinking degree, compressing the volume of the initial model until it meets the actual density requirements. After the compression process, anneal the molecular model at 298K~598K to eliminate internal stress and allow the molecular chains to fold and shrink. Finally, perform NPT and NVT kinetic calculations on the crosslinked epoxy resin molecular model with folded and shrunken molecular chains, and check the density and energy fluctuations during the calculation process. When the density and energy fluctuations are less than 10% of the mean, the crosslinked epoxy resin molecular model enters a stable state, yielding the crosslinked epoxy resin molecular model for thermal aging simulation.

[0060] According to the crosslinking script and preset crosslinking reaction conditions, the epoxy resin and anhydride curing agent molecules in the amorphous unit cell structure undergo a crosslinking reaction. The distance between the terminal C atom R1 on the epoxy group of the DGEBA molecule and the single bond O atom R2 on the anhydride curing agent is calculated. If it is less than the bonding radius, crosslinking is performed. Similarly, the distance between the O atom R4 on the epoxy group of the DGEBA molecule and the C atom R3 on the carboxyl group of the anhydride curing agent is calculated. If it is less than the bonding radius, crosslinking is performed. Finally, a crosslinked epoxy resin model is formed. The Forcite module is used to perform geometric optimization on the model to obtain the configuration with the lowest energy. 100ps NPT and NVT kinetic simulations are performed to balance the configuration, and finally a stable crosslinked epoxy resin model is formed. For specific results, see [link to results]. Figure 3 .

[0061] S5. In the GULP module of MS software, the ReaxFF6.0 reactive force field is called to apply high temperature to the cross-linked epoxy resin model to perform thermal aging simulation. The time step is set to 0.25fs, and the temperature and pressure are controlled by the Anderson and Berenden methods, respectively. When calculating nonbonded interactions, the van der Waals force is set to Atombased with a cutoff of 9.5A, and the Coulomb force is set to Eward.

[0062] S6, the trajectory file obtained from the thermal aging simulation contains epoxy resin molecular models at different aging times. The script removes gas molecules that escape from the epoxy resin molecular models, leaving only the solid part for analysis and calculation of structural parameters and physical properties.

[0063] S7, the dielectric constant ε of the epoxy resin system is calculated using the following formula:

[0064]

[0065] Where <> represents averaging; M is the dipole moment; M 2 is the dipole moment autocorrelation function; V is the volume of the epoxy resin system; T is the thermodynamic temperature of the epoxy resin system. The value of M can be obtained using...

[0066] Use the `$molecule->DipoleMoment` command to read; M 2 The value of can be read using the Dipole autocorrelation function; the value of V can be read using the Lattice3D->CellVolume command; the value of T can be read using the $document->Temperature command; kB is the Boltzmann constant; ε0 is the vacuum permittivity.

[0067] S8, the dipole moment is the product of the distance between the centers of positive and negative charges and the charge of the center of charge. It is a vector. The connection between different atoms has different dipole moment values. In the cross-linked epoxy resin system, different aging times will change the number of chemical bonds and the distance between atoms in the overall system. The change in the number of chemical bonds and the distance between atoms will affect the change in the dipole moment of the overall system.

[0068] When performing statistical analysis of the dipole moment of the model, it is necessary to perform NVT dynamic calculations for each model for 100 ps at the thermal aging temperature, and to perform 10 calculations for each model group to obtain the average dipole moment. The average value of these calculations is then taken to reduce the error.

[0069] Another embodiment discloses a system for calculating the dielectric constant of an epoxy / anhydride crosslinking model thermal aging process based on molecular simulation, comprising:

[0070] The molecular model building module, in MaterialStudio software, builds molecular models of epoxy resin monomer DGEBA and curing agent THPA, and preprocesses the molecular models.

[0071] The lattice building module fully mixes an appropriate amount of epoxy resin monomer DGEBA and curing agent THPA to obtain a lattice containing several epoxy resin monomers DGEBA and curing agent THPA.

[0072] The first molecular model construction module bonds R1, R2, R3, and R4 within the obtained lattice to obtain an initial molecular model of cross-linked epoxy resin that meets the preset degree of cross-linking.

[0073] The second molecular model construction module performs structural optimization and energy minimization on the initial molecular model of cross-linked epoxy resin obtained by the first molecular model construction module under the COMPASS force field, which meets the preset cross-linking degree, to obtain a cross-linked epoxy resin molecular model for thermal aging simulation.

[0074] The thermal aging process simulation module performs NPT kinetic calculations on the cross-linked epoxy resin molecular model obtained for thermal aging simulation based on the reactive force field, thus simulating the actual thermal aging process.

[0075] The spatiotemporal motion trajectory drawing module, based on the trajectory file generated by NPT dynamics calculation, tracks small molecules such as CO2, H2O, CO, H2, and CH4 generated during thermal aging, extracts their coordinates, and draws the spatiotemporal motion trajectory.

[0076] In the obtained trajectory file, the calculation module deletes small molecules that cannot be adsorbed by the cross-linked epoxy resin molecular model and thus escape from the molecular model, obtaining the remaining solid material; the dipole moment of the remaining solid material is statistically analyzed, and the relative permittivity of the cross-linked epoxy resin during the aging process is calculated using the relative permittivity formula.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the dielectric constant of a thermal aging process of an epoxy / anhydride crosslinking model based on molecular simulation, characterized in that, The specific steps are as follows: S1, in the Material Studio software, the molecular model of epoxy resin monomer DGEBA and curing agent THPA is built, and the molecular model is pretreated; the pretreatment includes: S1.1, the C atom at the end of the epoxy group of DGEBA and the O atom in the hydroxyl group are marked as R1 and R4 respectively, and the C atom of the carboxyl group and the O atom at the top of the curing agent THPA are marked as R3 and R2 respectively; S2, a certain amount of epoxy resin monomer DGEBA and curing agent THPA are mixed to obtain a crystal lattice containing several epoxy resin monomers DGEBA and curing agent THPA; S3, bond the R1, R2, R3 and R4 in the crystal lattice obtained in S2 to obtain an initial molecular model of crosslinked epoxy resin with a preset crosslinking degree; S4, the initial molecular model obtained in S3 is subjected to structure optimization and energy minimization treatment under the COMPASS force field to obtain a crosslinked epoxy resin molecular model for thermal aging simulation; The structure optimization and energy minimization treatment includes: S4.1, set the pressure to 0.5 GPa, and perform NPT dynamics calculation on the initial molecular model obtained in S3 to compress the volume of the initial molecular model until the actual density requirement is met; after the compression process is completed, a crosslinked epoxy resin molecular model meeting the actual density requirement is obtained; S4.2, annealing treatment is performed on the crosslinked epoxy resin molecular model meeting the actual density requirement obtained in S4.1 at 298 K~598 K to make the molecular chain fold and shrink; after the annealing treatment process is completed, a crosslinked epoxy resin molecular model with folded and shrunk molecular chain is obtained; S4.3, the crosslinked epoxy resin molecular model with folded and shrunk molecular chain obtained in S4.2 is subjected to NPT and NVT dynamics calculation in sequence, and the density and energy fluctuations in the calculation process are checked; when the density and energy fluctuations are less than 10% of the average value, the state of the crosslinked epoxy resin molecular model enters a stable state, and a crosslinked epoxy resin molecular model for thermal aging simulation is obtained; S5, based on the reaction force field, NPT dynamics calculation is performed on the crosslinked epoxy resin molecular model for thermal aging simulation obtained in S4 to simulate the actual thermal aging process; S6, based on the trajectory file generated by the NPT dynamics calculation in S5, the small molecule substances CO2, H2O, CO, H2 and CH4 generated in the thermal aging process are tracked, their coordinates are extracted, and the space-time motion trajectory is drawn; In S6, the small molecule substances generated in the thermal aging process are tracked, and the tracking includes: S6.1, the center of mass coordinates of the small molecule substances in each frame of the trajectory file are extracted and stored in the table unit corresponding to the time to obtain the time sequence position table of the specific small molecules; S6.2, based on the time sequence position table of the specific small molecules obtained in S6.1, the space-time motion trajectory of the specific small molecules is drawn; S6.3When the time-space movement trajectory route of the specific small molecule obtained in S6.2 exceeds the range of the cross-linked epoxy resin molecular model for thermal aging simulation in S4, mark the exceeding center coordinates with a color; S7. In the obtained trajectory file, delete the small molecules that cannot be adsorbed by the cross-linked epoxy resin molecular model for thermal aging simulation so as to escape from the molecular model, and obtain the remaining solid material; the dipole moment of the remaining solid material is counted, and the relative dielectric constant formula is used to calculate the relative dielectric constant of the cross-linked epoxy resin in the aging process.

2. The method of claim 1, wherein the method is based on a molecular simulation of an epoxy / anhydride crosslinking model thermal aging process. In S1, the pretreatment of the molecular model of the epoxy resin monomer DGEBA and the curing agent THPA further includes: S1.2Delete the chemical bond between R1 and R4 and the chemical bond between R2 and R3.

3. The method of claim 1, wherein the method is based on a molecular simulation of an epoxy / anhydride crosslinking model thermal aging process. In S3, the bonding of R1, R2, R3 and R4 includes: S3.1Perform NVT dynamic calculation on the lattice in S2, set the temperature to 500K, and obtain a trajectory file; S3.2Calculate the distance between the corresponding reaction atoms of the last frame of the trajectory file in S3.1; S3.3When the distance between the reaction atoms is less than the bonding radius, use the CreatBond command to connect the two reaction atoms to form a cross-linking chemical bond; at the same time of forming the cross-linking chemical bond, the name of the reaction atom is changed to reacted; S3.4Geometrically optimize the molecular model so that the bond length of the cross-linking chemical bond in S3.3 is within a reasonable range; S3.5Statistically count the cross-linking degree of the molecular model; if the cross-linking degree of the molecular model does not reach the expectation, increase the bonding radius of S3.3, and repeat S3.1, S3.2, S3.3 and S3.4 until the molecular model meets the preset cross-linking degree.

4. The method of claim 1, wherein the method is based on a molecular simulation of an epoxy / anhydride crosslinking model thermal aging process. The relative dielectric constant formula in S7 is based on the variance of the dipole moment to calculate the relative dielectric constant, and the specific form is: where ε represents the relative dielectric constant, ε0represents the vacuum dielectric constant, M represents the dipole moment, V represents the dielectric volume, k B represents the Boltzmann constant, T represents the temperature, and < > represents the average.

5. A molecular simulation based epoxy / anhydride crosslinking model thermal aging process dielectric constant calculation system using the method of any one of claims 1-4, wherein, It includes: A molecular model building module, which builds the molecular model of the epoxy resin monomer DGEBA and the curing agent THPA in the Material Studio software, and pretreats the molecular model; A lattice building module, which fully mixes a proper amount of the epoxy resin monomer DGEBA and the curing agent THPA to obtain a lattice containing a plurality of epoxy resin monomers DGEBA and curing agents THPA; A first molecular model building module, which bonds R1, R2, R3 and R4 in the obtained lattice to obtain a cross-linked epoxy resin initial molecular model meeting a preset cross-linking degree; A second molecular model building module, which performs structure optimization and energy minimization processing on the cross-linked epoxy resin initial molecular model meeting the preset cross-linking degree obtained by the first molecular model building module under the COMPASS force field to obtain a cross-linked epoxy resin molecular model for thermal aging simulation; A thermal aging process simulation module, which performs NPT dynamic calculation on the obtained cross-linked epoxy resin molecular model for thermal aging simulation based on the reaction force field to simulate the actual thermal aging process; and A small molecule movement trajectory route marking module, which marks the time-space movement trajectory route of the small molecule in the obtained trajectory file with a color when the time-space movement trajectory route of the small molecule exceeds the range of the cross-linked epoxy resin molecular model for thermal aging simulation in S4. The space-time motion trajectory route drawing module tracks CO2, H2O, CO, H2 and CH4 small molecules generated in the thermal aging process, extracts coordinates of the small molecules, and draws a space-time motion trajectory route based on a trajectory file generated by NPT dynamics calculation; The calculation module deletes small molecules that cannot be adsorbed by the cross-linked epoxy resin molecular model and thus escape from the molecular model in the obtained trajectory file, and obtains remaining solid materials; the dipole moment of the remaining solid materials is counted, and the relative dielectric constant of the cross-linked epoxy resin in the aging process is calculated by using a relative dielectric constant formula.

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