Modeling and simulation of moisture absorption of anhydride-cured epoxy insulation material

Abstract

The application relates to the technical field of computer simulation of high polymer materials, in particular to a method for constructing a crosslinking network model of anhydride-cured epoxy insulating material and simulating moisture absorption, the method for constructing the crosslinking network model comprising the following steps: establishing a monomer molecular model of bisphenol A diglycidyl ether epoxy resin and methyltetrahydrophthalic anhydride; performing pre-ring-opening treatment on the anhydride ring of the methyltetrahydrophthalic anhydride; performing curing reaction simulation to construct a three-dimensional crosslinking network model; the method for simulating moisture absorption comprises the following steps: obtaining the effective free volume distribution of the model based on the crosslinking network model; identifying the gap region that can be occupied by water molecules; inserting water molecules according to a preset water absorption rate to obtain a moisture absorption state model. The application significantly improves the efficiency and accuracy of the construction of the crosslinking network and the simulation of the wet state behavior.

Description

Technical Field

[0001] This application relates to the field of computer simulation technology for polymer materials, specifically to a method for constructing a crosslinked network model and simulating moisture absorption of an anhydride-cured epoxy insulating material. Background Technology

[0002] Epoxy resin materials, especially anhydride-cured epoxy insulation materials based on the bisphenol A diglycidyl ether (DGEBA) / methyltetrahydrophthalic anhydride (MTHPA) curing system, are widely used in power equipment such as dry-type air-core reactors due to their excellent insulation and processing properties. However, in extremely high humidity environments, the intrusion of water molecules can significantly affect the microstructure and macroscopic properties of these materials, posing a potential threat to the long-term operational reliability of the equipment. To gain a deeper understanding of the mechanisms by which water molecules affect these materials, revealing the structural evolution of the materials during the curing and moisture absorption processes at the atomic scale becomes crucial.

[0003] In existing technologies, molecular dynamics simulations combined with experimental testing are commonly used to study the aforementioned anhydride-cured epoxy insulating materials. Specifically, existing methods establish monomer molecular models based on the actual molecular structures of bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride, and attempt to simulate the entire process of ring-opening of the anhydride ring and the chain-like curing reaction with epoxy groups under the induction of a curing accelerator (such as DMP-30) to construct a final cross-linked network model. This model is used to study the microscopic bonding mechanism and network topology evolution during the curing process. Furthermore, to simulate the material's hygroscopic behavior, existing technologies randomly embed a number of water molecules corresponding to a predetermined macroscopic water absorption rate into the constructed dry cross-linked network to construct a wet model. This model is used to characterize the material's microstructural response and performance evolution after water molecule intrusion.

[0004] However, existing methods have significant shortcomings in achieving the above simulations: the actual anhydride-cured epoxy crosslinking process is a chain-initiated process, where a very small amount of hydroxyl groups in DMP-30 molecules induces the ring-opening of the MTHPA anhydride, thereby triggering the subsequent crosslinking process. When constructing the anhydride-cured epoxy crosslinking network model, due to the extremely low amount of curing accelerator added in the actual formulation, it is difficult to effectively trigger and complete the full chain-opening and crosslinking reaction induced by a small amount of accelerator molecules within the limited timescale of molecular dynamics simulations. This results in high computational costs and low model construction efficiency. Furthermore, when simulating the hygroscopic behavior of materials to construct a wet model, the method of directly embedding water molecules randomly into the polymer model fails to fully consider the physical fact that water molecules are not uniformly distributed within real polymer materials but tend to preferentially occupy the free volume space inside the material. This leads to a deviation between the constructed wet model and the actual microscopic hygroscopic state of the material, reducing the accuracy of the simulation. Summary of the Invention

[0005] To address the technical problems of low efficiency in existing molecular dynamics simulation methods for anhydride-cured epoxy insulation materials, which require simulating chain reactions induced by trace amounts of promoters when constructing crosslinking network models, and the inability of randomly inserting water molecules to reflect the true distribution of water molecules preferentially occupying free volume when constructing wet models, thus reducing simulation accuracy, this application provides a method for constructing crosslinking network models and simulating moisture absorption in anhydride-cured epoxy insulation materials. By pre-opening the anhydride rings of MTHPA and simultaneously deleting excess hydrogen atoms and hydroxyl groups during the bonding process of the hydroxyl curing reaction, a reasonable crosslinking network model is efficiently constructed. Furthermore, a wet model is constructed by targeting the insertion of water molecules based on the effective free volume distribution of the model, thereby improving the efficiency and accuracy of constructing crosslinking network models and simulating moisture absorption behavior in anhydride-cured epoxy materials.

[0006] In a first aspect, this application provides a method for constructing a crosslinked network model of an anhydride-cured epoxy insulating material, comprising the following steps: S1. Establish molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer; S2. The anhydride ring of the methyltetrahydrophthalic anhydride monomer molecular model is pre-opened to obtain a pre-opened methyltetrahydrophthalic anhydride monomer molecular model with two carboxyl groups. S3. The curing reaction simulation was carried out on the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model to generate a dry crosslinking model with a three-dimensional network structure, which serves as the crosslinking network model for anhydride-cured epoxy insulation material. The curing reaction simulation includes simulations of esterification, etherification, and hydroxyl curing reactions.

[0007] It should be further noted that in step S1, when establishing the molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer, three-dimensional molecular configurations are constructed based on their actual molecular structural formulas.

[0008] It should be further noted that step S1 also includes labeling the epoxy group reaction site atoms in the bisphenol A diglycidyl ether molecule, specifically including: The distal carbon atom in the epoxy group is labeled R1, and the oxygen atom in the epoxy group is labeled R3; Step S2 also includes labeling the reaction site atoms of the pre-opened anhydride ring in the pre-opened methyltetrahydrophthalic anhydride monomer molecule model, specifically including: The carbonyl carbon atom formed by pre-opening the anhydride ring is labeled as R4, and the hydroxyl oxygen atom is labeled as R2.

[0009] It should be further noted that in step S1, when establishing the bisphenol A diglycidyl ether monomer molecular model, COMPASS III was used to perform geometric optimization on the constructed monomer molecular model.

[0010] It should be further noted that the geometric optimization of the constructed monomer molecule model using the COMPASS III force field specifically includes: The conjugate gradient method is used to minimize the energy of the atomic coordinates of the monomer molecule until the energy gradient of the molecular system is lower than the preset energy convergence threshold or the number of iterations reaches the preset maximum number of iterations. The energy convergence threshold is 0.001 kcal / mol, and the maximum number of iterations is 10,000.

[0011] It should be further explained that, in step S2, the pre-ring-opening treatment of the anhydride ring in the methyltetrahydrophthalic anhydride monomer molecule model is specifically as follows: The closed anhydride ring in the methyltetrahydrophthalic anhydride monomer molecule model was opened to form two carboxyl groups, giving the molecule two active carboxyl sites.

[0012] It should be further noted that, in step S3, the ratio of the number of bisphenol A diglycidyl ether monomer molecules to the number of pre-opened methyltetrahydrophthalic anhydride monomer molecules used in the curing reaction simulation of the bisphenol A diglycidyl ether monomer molecular model and the pre-opened methyltetrahydrophthalic anhydride monomer molecular model satisfies the following relationship:

[0013] in, The number of bisphenol A diglycidyl ether molecules; The number of pre-opened methyltetrahydrophthalic anhydride molecules; The molar mass of pre-ring-opened methyltetrahydrophthalic anhydride; The value represents the molar mass of bisphenol A diglycidyl ether.

[0014] It should be further noted that in step S3, the number of bisphenol A diglycidyl ether monomer molecular models used for the curing reaction simulation of the bisphenol A diglycidyl ether monomer molecular model and the number of pre-opened ring methyltetrahydrophthalic anhydride monomer molecular models is 100 and 166 respectively.

[0015] It should be further noted that in step S3, the simulated esterification reaction is as follows: Pre-ring-opened methyltetrahydrophthalic anhydride reacts with the epoxy group of bisphenol A diglycidyl ether. The bonds between R1 and R3 are broken, causing the epoxy group to open. R1 and R2 form an ester group. The hydrogen atom on R2 is transferred to R3 to become a hydroxyl group. R1 is the distal carbon atom in the epoxy group, R2 is the hydroxyl group formed by the pre-ring-opening of the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated etherification reaction is as follows: the hydroxyl group in the esterification product reacts with the epoxy group of bisphenol A diglycidyl ether. The R1 of the hydroxyl group in the esterification product breaks the bond with the R3 of the epoxy group of bisphenol A diglycidyl ether, causing the epoxy ring to open. R1 and R3 form an ether bond. The R3 of the newly reacted bisphenol A diglycidyl ether forms a new hydroxyl group with a hydrogen atom. R1 is the distal carbon atom in the epoxy group, R2 is the oxygen atom in the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated hydroxyl curing reaction is as follows: the hydroxyl group in the esterification product reacts with the pre-opened ring-methyltetrahydrophthalic anhydride, and R3 and R4, which have been converted into hydroxyl groups, form an ester group. At the same time, the hydrogen atom on the hydroxyl group in the reactant and the hydroxyl group on the pre-opened ring-methyltetrahydrophthalic anhydride are deleted. Among them, R3 is the oxygen atom in the epoxy group and R4 is the carbonyl carbon atom formed by the pre-opening of the anhydride ring.

[0016] It should be further explained that the simultaneous deletion of hydrogen atoms on the hydroxyl groups and the hydroxyl groups on the pre-opened ring-methyltetrahydrophthalic anhydride in the reactants specifically involves: When the pre-opened ring-methyltetrahydrophthalic anhydride monomer molecule participates in the hydroxyl curing reaction, the oxygen atom on the hydroxyl group in the esterification product bonds with the carbon atom on the carboxyl group in the pre-opened ring-methyltetrahydrophthalic anhydride to form an ester group; on this basis, the hydrogen atom on the hydroxyl group in the esterification product and the hydroxyl group on the carboxyl group in the pre-opened ring-methyltetrahydrophthalic anhydride are deleted.

[0017] It should be further noted that after simultaneously removing the hydrogen atom from the hydroxyl group in the reactants and the hydroxyl group from the pre-opened ring-methyltetrahydrophthalic anhydride, the following operations are also performed: The obtained pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model was relaxed for 50 ps under the NPT ensemble, with a time step of 0.5 fs, to release the local internal stress caused by the forced removal of atoms.

[0018] It should be further noted that in step S3, when simulating the curing reaction, the reaction priorities of the three types of reactions and the triggering conditions for the hydroxyl curing reaction are set. The specific reaction priorities of the three types of reactions are as follows: Esterification is the highest priority reaction, hydroxyl curing is the second highest priority reaction, and etherification is the lowest priority reaction; The hydroxyl curing reaction is triggered when the number of active R3 hydroxyl sites reaches 10. The etherification reaction is triggered when the number of active R3 hydroxyl sites reaches 15.

[0019] It should be further noted that in step S3, when simulating the curing reaction, a reaction site atom locking mechanism is used: Once a certain reaction site atom is selected to enter the reaction queue, other reaction site atoms belonging to the same functional group as that reaction site atom are simultaneously locked and prohibited from participating in other reactions until the current bonding and relaxation process is completed.

[0020] It should be further noted that the specific implementation method of the curing reaction simulation in step S3 is to write and execute a Perl script. When the Perl script is executed, the following operations are performed: Within the set search radius, identify all possible bonding reaction site atom pairs, screen atom pairs according to reaction priority and functional group locked state, and perform bond breaking and bonding operations in a step-by-step approach, bonding, and relaxation manner until the crosslinking degree of the system reaches the preset target crosslinking degree; The degree of crosslinking of the system is calculated as the percentage of the number of bonded R1 site atoms to the total number of R1 site atoms.

[0021] It should be further noted that the temperature for simulating the curing reaction in step S3 is set to 500K, the maximum bonding search radius is gradually increased from 3.5 Å to 6.0 Å, the step size is 0.5 Å, and a maximum of 10 model traversal iterations are performed under each search radius.

[0022] It should be further noted that in step S3, the target degree of crosslinking is ≥95%.

[0023] It should be further noted that in step S3, during the curing reaction simulation, the current model configuration is derived for every 20% increase in the degree of crosslinking of the system.

[0024] It should be further noted that in step S3, after the curing reaction simulation is completed, the obtained dry crosslinking model is subjected to geometric optimization and kinetic relaxation: using the ReaxFF force field, kinetic relaxation is performed for 500 ps under the NPT ensemble until the model density and total energy reach equilibrium.

[0025] It should be further noted that step S3 also includes: statistically analyzing the number of independent clusters and the maximum cluster mass during the solidification reaction simulation process, defining an atomic cluster connected by chemical bonds as an independent cluster; when the number of independent clusters drops sharply and the maximum cluster mass increases sharply, it is determined that the model crosses the gel point and enters the gel state.

[0026] Secondly, this application provides a method for simulating the hygroscopic behavior of an anhydride-cured epoxy insulation material crosslinking network model. The anhydride-cured epoxy insulation material crosslinking network model is constructed using the above-mentioned method for constructing anhydride-cured epoxy insulation material crosslinking network model, and includes the following steps: S4. Using the cross-linked network model of anhydride-cured epoxy insulation material as the initial polymer model, obtain the effective free volume distribution of the initial polymer model; S5. Based on the effective free volume distribution of the initial polymer model, a probe scanning algorithm is used to identify the void regions that water molecules can occupy in the initial polymer model; S6. Calculate the number of water molecules to be inserted based on the preset macroscopic water absorption rate, and target and insert the corresponding number of water molecule models into the gap regions that water molecules can occupy in the initial polymer model to obtain the hygroscopic model.

[0027] It should be further explained that the specific method for obtaining the effective free volume distribution of the initial polymer model in step S4 is as follows: The atomic coordinates of the initial polymer model are exported, and the model space is discretized into a grid with a preset grid spacing. The minimum distance from each grid point to all polymer atoms is calculated. This minimum value is compared with the preset probe radius. If the minimum value is greater than the probe radius, the grid point is determined to belong to the effective free volume region; otherwise, it is determined to be the polymer skeleton repulsion volume region.

[0028] It should be further noted that the grid spacing ranges from 0.5 angstroms to 1.0 angstroms; The probe radius is 1.4 angstroms, which corresponds to the radius of the equivalent spherical probe for water molecules.

[0029] It should be further noted that in step S4, each grid point Distance to the nearest atom in the polymer atom set Satisfy the following formula:

[0030] in, For the first The spatial coordinates of a polymer atom; The indicator function for determining whether a grid point belongs to the effective free volume region is:

[0031] in, The probe radius is... This indicates that the grid point can serve as an insertion site for water molecules.

[0032] It should be further noted that in step S4, before obtaining the effective free volume distribution, the initial polymer model is first subjected to a short-time NPT ensemble relaxation of 10ps-50ps. After the relaxation is completed, the spatial coordinates of the model atoms are exported.

[0033] It should be further noted that, in step S5, the specific steps of identifying the void regions in the initial polymer model that water molecules can occupy using the probe scanning algorithm include: Water molecules are approximated as spherical probes. The probes are scanned at the grid points corresponding to the effective free volume distribution of the initial polymer model with a preset probe radius. The spatial region formed by the grid points that meet the probe reachability conditions is identified as the void region that water molecules can occupy. The probe radius is 1.4 angstroms.

[0034] It should be further explained that the probe reachability conditions are as follows: The current grid point belongs to the effective free volume distribution, and the distance between the current grid point and the neighboring polymer atoms is greater than the probe radius.

[0035] It should be further explained that in step S5, when identifying the void regions that water molecules can occupy, adjacent grid points belonging to the effective free volume region are clustered, and spatially continuous and connected effective free volume grid point clusters are identified as the same void region.

[0036] It should be further noted that the formula for calculating the number of water molecules to be inserted based on the preset macroscopic water absorption rate is as follows:

[0037] in, The number of water molecules to be inserted. The preset macroscopic water absorption rate, 18.015 represents the total mass of the initial polymer model, and 18.015 represents the molar mass of a water molecule.

[0038] It should be further noted that the macroscopic water absorption rate ω ranges from 1.0 wt% to 5.0 wt%.

[0039] It should be further explained that in step S6, the specific method for targeting and inserting the corresponding number of water molecule models into the void regions that water molecules can occupy in the initial polymer model is as follows: from all grid points belonging to the void regions that water molecules can occupy, a number of grid points equal to the number of water molecules are randomly selected as water molecule insertion sites, and a water molecule model is placed at each insertion site.

[0040] It should be further explained that when the total number of grid points in the void area that a water molecule can occupy is greater than or equal to the number of water molecules to be inserted, random sampling is performed from all grid points; when the total number of grid points in the void area that a water molecule can occupy is less than the number of water molecules to be inserted, one water molecule is inserted into each of all grid points, and the remaining water molecules are not inserted.

[0041] It should be further noted that in step S6, after the water molecule model is inserted into the target, the obtained hygroscopic model is subjected to NPT ensemble relaxation of 50ps-200ps with a time step of 1fs to eliminate local stress and reach thermodynamic equilibrium.

[0042] Thirdly, this application provides a system for constructing a crosslinked network model of an anhydride-cured epoxy insulating material, used to implement the above-mentioned method for constructing a crosslinked network model of an anhydride-cured epoxy insulating material, including: The monomer model building module is used to build molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer. The pre-ring-opening module is used to pre-open the anhydride ring of the methyltetrahydrophthalic anhydride monomer molecular model to obtain a pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model with two carboxyl groups. The curing reaction simulation module is used to simulate the curing reaction of bisphenol A diglycidyl ether monomer molecular models and pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular models, generating a dry crosslinking model with a three-dimensional network structure, which serves as the crosslinking network model for anhydride-cured epoxy insulation materials.

[0043] Fourthly, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the steps of the above-described method for constructing a crosslinked network model of an anhydride-cured epoxy insulating material.

[0044] Fifthly, this application provides a storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described method for constructing a crosslinked network model of anhydride-cured epoxy insulating material.

[0045] As can be seen from the above technical solutions, this application has the following advantages: 1. This application solves the problem of low modeling efficiency caused by the need to simulate the chain reaction induced by trace amounts of DMP-30 accelerator in the prior art by establishing a molecular model of bisphenol A diglycidyl ether epoxy resin monomer and pre-opening the monomer model of acid anhydride curing agent, and then performing curing reaction simulation to generate a crosslinking network model. This significantly improves the construction efficiency and reliability of crosslinking network model of acid anhydride cured epoxy insulation material.

[0046] 2. This application achieves a correspondence with the actual curing process by pre-opening the anhydride ring of the methyltetrahydrophthalic anhydride monomer model and simultaneously deleting excess hydrogen atoms and hydroxyl groups during the subsequent hydroxyl curing reaction. Based on this, it bypasses the simulation of the ring-opening step induced by a curing accelerator added in extremely small amounts, solving the problem of high computational cost in existing methods due to the difficulty in simulating chain reaction triggering. This improves the construction efficiency of the crosslinking network model while ensuring the rationality of the model's chemical topology.

[0047] 3. This application solves the problem in existing wet model construction methods where the microscopic distribution of water molecules does not match the real physical situation due to the random insertion of water molecules by first obtaining the effective free volume distribution of the cross-linked network model and then identifying the void regions that water molecules can occupy, and then inserting the corresponding number of water molecule models in a targeted manner. This makes the constructed hygroscopic model more realistically reflect the preferential occupation behavior of water molecules in the free volume inside the polymer, and improves the accuracy of hygroscopic behavior simulation. Attached Figure Description

[0048] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model in one embodiment of this application.

[0050] Figure 2 This is a schematic diagram of the reaction process for simulating the curing reaction of a bisphenol A diglycidyl ether monomer molecular model and a pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model in one embodiment of this application.

[0051] Figure 3 This is a schematic diagram of a cross-linked network model of an anhydride-cured epoxy insulation material in one embodiment of this application. Detailed Implementation

[0052] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The following describes in detail the method for constructing a crosslinked network model of anhydride-cured epoxy insulation material according to this application. Specific details, such as particular system structures and techniques, are presented for illustrative purposes and not for limitation, to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details.

[0054] In the method for constructing a crosslinked network model of anhydride-cured epoxy insulation material involved in this application, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0055] To facilitate a clear description of the technical solutions of this application, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" do not necessarily imply that they are different.

[0056] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0057] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0058] The method for constructing a crosslinked network model of anhydride-cured epoxy insulation material provided in this application embodiment is executed by a computer device, and correspondingly, the system for constructing a crosslinked network model of anhydride-cured epoxy insulation material runs in the computer device.

[0059] The following are embodiments of the method for constructing a crosslinked network model of anhydride-cured epoxy insulation material provided in this application. The implementing entity of this method can be an anhydride-cured epoxy insulation material crosslinked network model construction system. This method for constructing a crosslinked network model of anhydride-cured epoxy insulation material includes: Step S1: Establish molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer.

[0060] By establishing molecular models of bisphenol A diglycidyl ether epoxy resin monomers and methyltetrahydrophthalic anhydride curing agent monomers, the most basic, unreacted molecular entities were provided for the construction of the crosslinking network model of the entire anhydride-cured epoxy insulation material.

[0061] In some specific embodiments, when establishing molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer, three-dimensional molecular configurations are constructed based on their actual molecular structures.

[0062] By constructing three-dimensional molecular configurations based on the actual molecular structure when building monomer molecular models, it is ensured that the constructed models are consistent with the actual molecules in spatial structure.

[0063] In some specific embodiments, when establishing the bisphenol A diglycidyl ether monomer molecular model, the COMPASSIII force field is used to perform geometric optimization on the constructed monomer molecular model.

[0064] By using the COMPASS III force field for geometric optimization when establishing the molecular model of bisphenol A diglycidyl ether epoxy resin monomer, the accurate description capability of the force field for organic systems can be utilized to automatically adjust the initially constructed molecular structure to a stable conformation with lower energy, thereby eliminating unreasonable structural parameters and providing a more physically reasonable initial structure of epoxy resin monomer for subsequent reaction simulation.

[0065] In some specific embodiments, the geometric optimization of the constructed monomer molecule model using the COMPASS III force field specifically includes: The conjugate gradient method is used to minimize the energy of the atomic coordinates of the monomer molecule until the energy gradient of the molecular system is lower than the preset energy convergence threshold or the number of iterations reaches the preset maximum number of iterations. The energy convergence threshold is 0.001 kcal / mol, and the maximum number of iterations is 10,000.

[0066] By employing the conjugate gradient method for energy minimization calculations and setting explicit energy convergence thresholds and maximum iteration steps, an efficient and stable numerical solution framework is provided for the geometric optimization process. This ensures that an optimized molecular configuration with internal force balance and gradient convergence is obtained within a controllable computational cost, thereby improving the structural reliability of the monomer model.

[0067] Step S2 involves pre-opening the anhydride ring of the methyltetrahydrophthalic anhydride monomer molecular model to obtain a pre-opened methyltetrahydrophthalic anhydride monomer molecular model with two carboxyl groups.

[0068] By pre-opening the anhydride ring of the monomer model of the methyltetrahydrophthalic anhydride curing agent and simultaneously deleting excess hydrogen atoms and hydroxyl groups to obtain a pre-opened ring model with two carboxyl groups, the key ring-opening step induced by the accelerator in the actual curing process is pre-completed at the molecular topology. This allows subsequent curing reaction simulations to be performed efficiently on the active intermediate, avoiding the huge computational burden caused by simulating this low-probability triggering event at the molecular dynamics scale.

[0069] In some specific embodiments, step S1 further includes labeling the epoxy group reaction site atoms in the bisphenol A diglycidyl ether molecule, specifically including: The distal carbon atom in the epoxy group is labeled R1, and the oxygen atom in the epoxy group is labeled R3; Step S2 also includes labeling the anhydride ring reaction site atoms in the methyltetrahydrophthalic anhydride molecule, specifically including: The carbonyl carbon atom in the anhydride ring is labeled R4, and the anhydride oxygen atom in the anhydride ring is labeled R2.

[0070] By labeling the distal carbon and oxygen atoms in the epoxy group as R1 and R3, respectively, and the carbonyl carbon atom and hydroxyl oxygen atom formed by the pre-ring-opening of the anhydride ring as R4 and R2, respectively, an unambiguous atomic mapping rule is established for the chemical bond breaking and formation events in the subsequent curing reaction simulation. This allows the three different types of reactions, namely esterification, etherification, and hydroxyl curing, to be precisely defined and executed through specific combinations of atomic labels.

[0071] In one specific embodiment, schematic diagrams of the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model are shown below. Figure 1 As shown, where: Figure 1 In the middle (a), there is a molecular model of the bisphenol A diglycidyl ether monomer. Figure 1 (b) is a molecular model of a pre-ring-opened methyltetrahydrophthalic anhydride monomer.

[0072] In some specific embodiments, the pre-ring-opening treatment of the anhydride ring in the methyltetrahydrophthalic anhydride monomer molecular model specifically involves: The closed anhydride ring in the methyltetrahydrophthalic anhydride monomer molecule model was opened to form two carboxyl groups, giving the molecule two active carboxyl sites.

[0073] By opening the closed anhydride ring into two carboxyl groups, the molecule directly possesses two active carboxyl sites, achieving equivalence to the actual reaction intermediate at the molecular topological level. This simplifies the model, allowing the simulation program to directly start subsequent crosslinking from the carboxyl groups with clearly defined reactivity, bypassing the complex simulation of the anhydride ring's own ring-opening reaction kinetics.

[0074] Step S3: Perform a curing reaction simulation on the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model to generate a dry crosslinking model with a three-dimensional network structure, which serves as the crosslinking network model for anhydride-cured epoxy insulation material. The curing reaction simulation includes simulations of esterification, etherification, and hydroxyl curing reactions.

[0075] By simulating the curing reaction of bisphenol A diglycidyl ether epoxy resin monomer model and pre-ring-opened methyltetrahydrophthalic anhydride curing agent monomer model, including esterification, etherification and hydroxyl curing reactions, the active molecules can be driven to automatically connect according to the set chemical reaction logic in the computational environment, and dynamically grow a dry crosslinking model with a three-dimensional network structure. Thus, the final crosslinking network of anhydride-cured epoxy insulation material is constructed and reproduced at the atomic scale.

[0076] In some specific embodiments, the ratio of the number of bisphenol A diglycidyl ether monomer molecules to the number of pre-opened methyltetrahydrophthalic anhydride monomer molecules used in the curing reaction simulation of the bisphenol A diglycidyl ether monomer molecular model and the pre-opened methyltetrahydrophthalic anhydride monomer molecular model satisfies the following relationship:

[0077] in, The number of bisphenol A diglycidyl ether molecules; The number of pre-opened methyltetrahydrophthalic anhydride molecules; The molar mass of pre-ring-opened methyltetrahydrophthalic anhydride; The value represents the molar mass of bisphenol A diglycidyl ether.

[0078] By ensuring that the number of the two monomer molecules involved in the simulation satisfies a specific relationship based on the ratio of their molar mass to their mass fraction, the feed ratio of the reactants in the simulation is strictly consistent with the actual production formula. This ensures that the chemical composition and crosslinking density of the final crosslinking network model can accurately reflect the expected results under the target formula, thereby enhancing the relevance and comparability of the simulation.

[0079] In some specific embodiments, the number of bisphenol A diglycidyl ether monomer molecular models used for simulating the curing reaction of the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model is 100, and the number of pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular models is 166.

[0080] In some specific embodiments, the simulated esterification reaction is as follows: Pre-ring-opened methyltetrahydrophthalic anhydride reacts with the epoxy group of bisphenol A diglycidyl ether. The bonds between R1 and R3 are broken, causing the epoxy group to open. R1 and R2 form an ester group. The hydrogen atom on R2 is transferred to R3 to become a hydroxyl group. R1 is the distal carbon atom in the epoxy group, R2 is the hydroxyl oxygen atom formed by the pre-ring-opening of the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated etherification reaction is as follows: the hydroxyl group in the esterification product reacts with the epoxy group of bisphenol A diglycidyl ether. The R1 of the hydroxyl group in the esterification product breaks the bond with the R3 of the epoxy group of bisphenol A diglycidyl ether, causing the epoxy ring to open. R1 and R3 form an ether bond. The R3 of the newly reacted bisphenol A diglycidyl ether forms a new hydroxyl group with a hydrogen atom. R1 is the distal carbon atom in the epoxy group, R2 is the oxygen atom in the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated hydroxyl curing reaction is as follows: the hydroxyl group in the esterification product reacts with the pre-opened ring-methyltetrahydrophthalic anhydride, and R3 and R4, which have been converted into hydroxyl groups, form an ester group. At the same time, the hydrogen atom on the hydroxyl group in the reactant and the hydroxyl group on the pre-opened ring-methyltetrahydrophthalic anhydride are deleted. Among them, R3 is the oxygen atom in the epoxy group and R4 is the carbonyl carbon atom formed by the pre-opening of the anhydride ring.

[0081] By clearly defining the specific atomic bond breaking and bonding mechanisms of esterification, etherification, and hydroxyl curing reactions, including specific processes such as R1-R2 bonding, R1-R3 bonding, and R3-R4 bonding, a complete and precise rule definition is provided for molecular dynamics simulation programs to execute chemical reactions, ensuring the correctness of the network growth process at the microscopic level.

[0082] In some specific embodiments, the simultaneous deletion of hydrogen atoms on the hydroxyl groups and hydroxyl groups on the pre-opened ring-methyltetrahydrophthalic anhydride in the reactants specifically involves: When the pre-opened ring-methyltetrahydrophthalic anhydride monomer molecule participates in the hydroxyl curing reaction, the oxygen atom on the hydroxyl group in the esterification product bonds with the carbon atom on the carboxyl group in the pre-opened ring-methyltetrahydrophthalic anhydride to form an ester group; on this basis, the hydrogen atom on the hydroxyl group in the esterification product and the hydroxyl group on the carboxyl group in the pre-opened ring-methyltetrahydrophthalic anhydride are deleted.

[0083] By simultaneously removing excess hydrogen atoms and hydroxyl groups, the correct chemical state of functional groups in the model was ensured, avoiding non-stoichiometric reactions or incorrect intermolecular interactions in subsequent simulations due to the presence of excess atoms.

[0084] In some specific embodiments, after simultaneously deleting the hydrogen atom on the hydroxyl group and the hydroxyl group on the pre-opened ring-methyltetrahydrophthalic anhydride in the reactants, the following operations are also performed: The obtained pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model was relaxed for 50 ps under the NPT ensemble, with a time step of 0.5 fs, to release the local internal stress caused by the forced removal of atoms.

[0085] By simultaneously removing hydrogen atoms from the hydroxyl groups in the reactants and hydroxyl groups from the pre-ring-opened methyltetrahydrophthalic anhydride, the obtained pre-ring-opened model is subjected to short-time kinetic relaxation under the NPT ensemble. This allows the equilibrium process simulated by molecular dynamics to naturally release any localized unreasonable internal stresses or spatial conflicts that may have been introduced by manually removing atoms, thereby obtaining a pre-ring-opened curing agent monomer model with a relaxed structure that is closer to equilibrium.

[0086] In one specific embodiment, a schematic diagram of the reaction process for simulating the curing reaction of the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model is shown below. Figure 2 As shown In some specific embodiments, when simulating the curing reaction, the reaction priorities of three types of reactions and the triggering conditions for the hydroxyl curing reaction are set. The specific reaction priorities of the three types of reactions are as follows: Esterification is the highest priority reaction, hydroxyl curing is the second highest priority reaction, and etherification is the lowest priority reaction; The hydroxyl curing reaction is triggered when the number of active R3 hydroxyl sites reaches 10. The etherification reaction is triggered when the number of active R3 hydroxyl sites reaches 15.

[0087] By setting different reaction priorities for esterification, etherification, and hydroxyl curing reactions, and setting triggering conditions based on the number of active hydroxyl groups for hydroxyl curing and etherification reactions, a dynamic control mechanism for reaction competition is introduced into the simulation program, enabling the network growth to simulate the evolution of main and side reactions with changes in conversion rate during the actual curing process.

[0088] In some specific embodiments, in step S3, when simulating the curing reaction, a reaction site atom locking mechanism is employed: Once a certain reaction site atom is selected to enter the reaction queue, other reaction site atoms belonging to the same functional group as that reaction site atom are simultaneously locked and prohibited from participating in other reactions until the current bonding and relaxation process is completed.

[0089] By employing a reaction site atom locking mechanism, when a certain reaction site atom is selected to enter the reaction queue, other reaction site atoms within the same functional group are simultaneously locked, prohibiting them from participating in other reactions before the current reaction is completed. This effectively prevents the non-physical situation of multiple reactions occurring in the same functional group in a single iteration, which could lead to errors in the chemical valence state of atoms, and ensures the chemical rationality of each bonding event.

[0090] In some specific embodiments, the curing reaction simulation is implemented by writing and executing a Perl script, which performs the following operations when executed: Within the set search radius, identify all possible bonding reaction site atom pairs, screen atom pairs according to reaction priority and functional group locked state, and perform bond breaking and bonding operations in a step-by-step approach, bonding, and relaxation manner until the crosslinking degree of the system reaches the preset target crosslinking degree; The degree of crosslinking of the system is calculated as the percentage of the number of bonded R1 site atoms to the total number of R1 site atoms.

[0091] By writing and executing Perl scripts to identify reaction site atom pairs within the search radius, filter according to rules, and perform operations in a step-by-step approach of bonding and relaxation until the target degree of crosslinking is achieved, the crosslinking network construction process is fully automated and programmed. It can systematically traverse and connect reaction sites, and efficiently and reliably generate a three-dimensional network structure model with a high degree of crosslinking.

[0092] In some specific embodiments, the temperature for simulating the curing reaction is set to 500K, the maximum bonding search radius is gradually increased from 3.5 angstroms to 6.0 angstroms, the step size is 0.5 angstroms, and a maximum of 10 model traversal iterations are performed under each search radius.

[0093] By setting the temperature of the curing reaction simulation to 500K and gradually increasing the maximum bonding search radius from 3.5 Å to 6.0 Å, sufficient mobility is provided for molecules to overcome the energy barrier in the simulation. The search range of atomic pairs is gradually broadened to simulate the process of diffusion becoming more difficult in the later stages of the reaction. This strategy helps to connect different reaction sites in the system more efficiently and rationally, thereby achieving a high degree of crosslinking.

[0094] In some specific embodiments, the target crosslinking degree is ≥95%.

[0095] By setting the target crosslinking degree to ≥95%, a high termination criterion is set for the curing reaction simulation, ensuring that the final crosslinking network model has near-completely transformed network integrity. Such a model can more realistically represent the intrinsic structure of epoxy materials after deep curing, making the performance prediction results based on the model more valuable.

[0096] In some specific embodiments, during the curing reaction simulation, the current model configuration is derived for every 20% increase in the degree of crosslinking of the system.

[0097] By deriving the current model configuration whenever the crosslinking degree of the system increases by 20% during the curing reaction simulation, the phased recording of the network formation process is realized. This allows researchers to obtain a series of intermediate models with different crosslinking degrees from low to high, which can then be used to systematically study the dynamic laws of the evolution of network structure parameters with the degree of curing.

[0098] In some specific embodiments, after the curing reaction simulation is completed, the obtained dry crosslinking model is subjected to geometric optimization and kinetic relaxation: using the ReaxFF force field, kinetic relaxation is performed for 500 ps under the NPT ensemble until the model density and total energy reach equilibrium.

[0099] After the curing reaction simulation is completed, the obtained dry crosslinking model is subjected to sufficient geometric optimization and kinetic relaxation using the ReaxFF force field under the NPT ensemble. This allows for the accurate description of the complex interactions in the network using the reactive force field, and enables the entire system to fully relax to an equilibrium state under a set environment. This results in a final equilibrium structural model that is energy stable, structurally balanced, and physically convergent. In one specific embodiment, a schematic diagram of the cross-linked network model of the anhydride-cured epoxy insulation material is shown below. Figure 3 As shown, the bisphenol A diglycidyl ether molecule and the pre-opened ring-methyltetrahydrophthalic anhydride molecule are displayed in a line model, while the newly generated cross-linked chemical bonds are displayed in a ball-and-stick model.

[0100] In some specific embodiments, step S3 further includes: counting the number of independent clusters and the maximum cluster mass during the curing reaction simulation process, defining an atomic cluster connected by chemical bonds as an independent cluster; when the number of independent clusters drops sharply and the maximum cluster mass increases sharply, determining that the model crosses the gel point and enters the gel state.

[0101] By statistically analyzing the number of independent clusters and the maximum cluster mass during the curing reaction simulation, an atomic cluster connected by chemical bonds is defined as an independent cluster. This provides an indicator for quantitatively monitoring the network gelation process, making it possible to determine the gel point by observing a sharp drop in the number of independent clusters and a sharp increase in the maximum cluster mass in the simulation. This is helpful for further research on curing kinetics.

[0102] The following are embodiments of the method for simulating moisture absorption behavior using a cross-linked network model of an anhydride-cured epoxy insulation material provided in this application. This method uses the cross-linked network model of the anhydride-cured epoxy insulation material constructed in the aforementioned embodiments. The method for simulating moisture absorption behavior using a cross-linked network model of an anhydride-cured epoxy insulation material includes: Step S4: Use the cross-linked network model of the anhydride-cured epoxy insulation material as the initial polymer model to obtain the effective free volume distribution of the initial polymer model.

[0103] By using the cross-linked network model of anhydride-cured epoxy insulation material as the initial polymer model and obtaining its effective free volume distribution, the spatial regions within the entire model that can accommodate water molecules were systematically identified and quantified at the atomic scale.

[0104] In some specific embodiments, the method for obtaining the effective free volume distribution of the initial polymer model in step S4 is as follows: The atomic coordinates of the initial polymer model are exported, and the model space is discretized into a grid with a preset grid spacing. The minimum distance from each grid point to all polymer atoms is calculated. This minimum value is compared with the preset probe radius. If the minimum value is greater than the probe radius, the grid point is determined to belong to the effective free volume region; otherwise, it is determined to be the polymer skeleton repulsion volume region.

[0105] By exporting the atomic coordinates of the initial polymer model, the model space is discretized into a grid with a preset grid spacing. The minimum distance from each grid point to all polymer atoms is calculated and compared with the probe radius to determine whether it belongs to the effective free volume region. The continuous model space is transformed into a discrete, computable set of grid points. A clear geometric reachability criterion is assigned to each grid point through distance calculation. Thus, the abstract concept of "free volume" is transformed into spatial location data that can be automatically and batch-processed by the program. This enables the systematic and quantitative identification and labeling of the spatial regions inside the polymer that can accommodate foreign small molecules.

[0106] In some specific embodiments, the grid spacing ranges from 0.5 angstroms to 1.0 angstroms; The probe radius is 1.4 angstroms, which corresponds to the radius of the equivalent spherical probe for water molecules.

[0107] By limiting the grid spacing to 0.5 Å to 1.0 Å and explicitly setting the probe radius to 1.4 Å to correspond to the equivalent spherical radius of a water molecule, specific and reasonable parameter settings are provided for the discretization calculation of the effective free volume distribution. The smaller grid spacing ensures the fineness of spatial scanning to accurately capture the edges of tiny gaps, while the probe radius matching the size of a water molecule ensures that the identified space can indeed physically accommodate a water molecule. This makes the subsequent analysis and water molecule insertion operations based on this distribution have clear physical meaning and accuracy on a scale.

[0108] In some specific embodiments, each grid point Distance to the nearest atom in the polymer atom set Satisfy the following formula:

[0109] in, For the first The spatial coordinates of a polymer atom; The indicator function for determining whether a grid point belongs to the effective free volume region is:

[0110] in, The probe radius is... This indicates that the grid point can serve as an insertion site for water molecules.

[0111] By employing mathematical formulas to explicitly define the method for calculating the minimum distance from a grid point to the nearest polymer atom, and introducing a binary indicator function based on comparing this minimum value with the probe radius to determine whether a grid point belongs to the effective free volume region that can serve as a water molecule insertion site, a clear, rigorous, and programmable mathematical logic is provided for the entire judgment process. This eliminates the subjectivity and ambiguity of manual judgment, enabling the classification and judgment of a large number of grid points to be performed efficiently and accurately by computers, thus ensuring the objectivity and repeatability of the effective free volume distribution calculation results.

[0112] In some specific embodiments, before obtaining the effective free volume distribution in step S4, the initial polymer model is first subjected to a short-time NPT ensemble relaxation of 10ps-50ps, and the spatial coordinates of the model atoms are then derived after the relaxation is completed.

[0113] By performing a short-term NPT ensemble relaxation on the initial polymer model before obtaining the effective free volume distribution, the model can undergo minor structural adjustments under set temperature and pressure conditions to achieve a more stable equilibrium conformation. Then, the spatial coordinates of the atoms at this point are derived for analysis. This step ensures that the atomic positions on which the subsequent free volume calculation is based are a reasonable arrangement of the model under thermodynamic equilibrium, avoiding instantaneous and unreasonable deviations in the free volume distribution calculation results caused by using non-equilibrium or high-energy configurations.

[0114] Step S5: Based on the effective free volume distribution of the initial polymer model, a probe scanning algorithm is used to identify the void regions that water molecules can occupy in the initial polymer model.

[0115] By using the effective free volume distribution based on the initial polymer model, a probe scanning algorithm is used to identify the void regions that water molecules can occupy in the model. The effective free volume space is then screened and clustered to accurately locate all the discretized spatial locations that are truly suitable for the initial inhabitation of water molecules in terms of size and connectivity.

[0116] In some specific embodiments, the use of probe scanning algorithms to identify the void regions in the initial polymer model that water molecules can occupy specifically includes: Water molecules are approximated as spherical probes. The probes are scanned at the grid points corresponding to the effective free volume distribution of the initial polymer model with a preset probe radius. The spatial region formed by the grid points that meet the probe reachability conditions is identified as the void region that water molecules can occupy. The probe radius is 1.4 angstroms.

[0117] By approximating water molecules as spherical probes and scanning the grid points corresponding to the effective free volume distribution with a preset probe radius, the spatial region formed by the grid points that meet the probe reachability conditions is identified as the void region that water molecules can occupy. Based on the identified "effective free volume", this method further verifies the occupancy of water molecules by using the physical size of the water molecules as the scale, and screens out regions that are not only spatially empty but also whose shape and size allow a water molecule sphere to exist. This further refines the range of potential insertion sites from geometric space to real voids that meet the physical containment conditions.

[0118] In some specific embodiments, the probe reachability conditions are as follows: The current grid point belongs to the effective free volume distribution, and the distance between the current grid point and the neighboring polymer atoms is greater than the probe radius.

[0119] By defining the probe reachability condition specifically as the current grid point belonging to the effective free volume distribution and the distance between it and the neighboring polymer atoms being greater than the probe radius, a dual and rigorous criterion is provided for the occupancy of water molecules. First, the point itself must be located within the free volume region. Second, the spherical space centered on the point and with the probe radius as its radius must not be invaded by any polymer atoms. This ensures that each occupancy site identified represents a specific spatial location that can completely accommodate a water molecule without spatially overlapping with the polymer skeleton.

[0120] In some specific embodiments, when identifying the void regions that water molecules can occupy, adjacent grid points belonging to the effective free volume region are clustered, and spatially continuous and connected effective free volume grid point clusters are identified as the same void region.

[0121] By clustering adjacent grid points belonging to the effective free volume region when identifying the void regions that water molecules can occupy, and identifying spatially continuous clusters of effective free volume grid points as the same void region, this method can aggregate scattered and isolated effective grid points into continuous volume units according to their spatial adjacency, thereby revealing the spatial distribution pattern of free volume inside the polymer, which helps to understand the possible diffusion paths and aggregation behavior of water molecules.

[0122] In some specific embodiments, the formula for calculating the number of water molecules to be inserted based on a preset macroscopic water absorption rate is as follows:

[0123] in, The number of water molecules to be inserted. The preset macroscopic water absorption rate, 18.015 represents the total mass of the initial polymer model, and 18.015 represents the molar mass of a water molecule.

[0124] By using a formula based on the preset macroscopic water absorption rate and the total mass of the polymer model to calculate the number of water molecules to be inserted, the macroscopically measurable or set mass water absorption rate target is directly and accurately converted into the specific number of water molecules to be created in the microscopic simulation model. This allows for precise control of the water content of the constructed wet model at the atomic scale, ensuring that the water absorption rate of the simulation system is consistent with the target value set by the real material or experiment in a macroscopic statistical manner.

[0125] In some specific embodiments, the macroscopic water absorption rate ω ranges from 1.0 wt% to 5.0 wt%.

[0126] By limiting the range of macroscopic water absorption rate to 1.0wt% to 5.0wt%, a clear and reasonable humidity condition range is set for the simulation of moisture absorption behavior. This range covers the medium to high levels of moisture absorption that epoxy resin materials may encounter in practical applications. This allows the wet model constructed by this method to be used specifically to study the structural and performance response of materials within this humidity range, and provides a standardized basis for setting the moisture content for comparative studies under different humidity conditions.

[0127] Step S6: Calculate the number of water molecules to be inserted based on the preset macroscopic water absorption rate, and target and insert the corresponding number of water molecule models into the gap regions that water molecules can occupy in the initial polymer model to obtain the hygroscopic model.

[0128] By calculating the number of water molecules to be inserted based on a preset macroscopic water absorption rate, and targeting the corresponding number of water molecule models in the identified gap regions that water molecules can occupy, the constructed hygroscopic model is ensured to meet the set target in terms of macroscopic water absorption rate. At the same time, the initial position of water molecules is forced to be in a thermodynamically more favorable free volume cavity, thus obtaining an initial configuration that is closer to the real hygroscopic equilibrium state.

[0129] In some specific embodiments, the specific method for targeting and inserting a corresponding number of water molecule models into the void regions that water molecules can occupy in the initial polymer model is as follows: from all grid points belonging to the void regions that water molecules can occupy, a number of grid points equal to the number of water molecules are randomly selected as water molecule insertion sites, and a water molecule model is placed at each insertion site.

[0130] By randomly selecting an equal number of grid points from all identified grid points belonging to the void regions that water molecules can occupy as insertion sites, and placing a water molecule model at each site, this method ensures that each water molecule is initially forced into a physical space that has been geometrically determined to accommodate it. This avoids the high-energy, non-physical configurations that may result from traditional random insertion methods, such as water molecules initially embedding themselves inside polymer chains or atomic overlap, significantly improving the rationality of the initial structure of the wet model. In some specific embodiments, when the total number of grid points in the void area that water molecules can occupy is greater than or equal to the number of water molecules to be inserted, random sampling is performed from all grid points; when the total number of grid points in the void area that water molecules can occupy is less than the number of water molecules to be inserted, one water molecule is inserted into each of all grid points, and the remaining water molecules are not inserted.

[0131] By explicitly defining that when the total number of grid points in the available gap area is greater than or equal to the number of water molecules to be inserted, random sampling and insertion are performed from all points, while when the total number of grid points is insufficient, only one water molecule is inserted from each of all points and no more are inserted, a complete logical branching process is provided for the water molecule insertion operation. This ensures that the program can execute stably and give clear results under various conditions. It makes full use of all identified available sites and avoids model distortion caused by forced insertion when space is insufficient, reflecting the rigor of the modeling process.

[0132] In some specific embodiments, after the water molecule model is targeted and inserted, the resulting hygroscopic model is subjected to NPT ensemble relaxation of 50ps-200ps with a time step of 1fs to eliminate local stress and reach thermodynamic equilibrium.

[0133] By performing NPT ensemble relaxation on the resulting hygroscopic model after targeted insertion of water molecules, the newly inserted water molecules can naturally adjust their position and orientation with the surrounding polymer network and with each other through molecular dynamics simulation. This eliminates local stress or unfavorable close contact that may be caused by initial placement, thereby relaxing the entire polymer-water composite system to a lower-energy and more stable thermodynamic equilibrium state under the set temperature and pressure conditions. This provides a reliable initial equilibrium structure for subsequent property calculations or dynamic simulations of any equilibrium state.

[0134] The following are embodiments of the cross-linked network model construction system for anhydride-cured epoxy insulation materials provided in this application. This cross-linked network model construction system for anhydride-cured epoxy insulation materials belongs to the same inventive concept as the cross-linked network model construction method for anhydride-cured epoxy insulation materials in the above embodiments. For details not described in detail in the embodiments of the cross-linked network model construction system for anhydride-cured epoxy insulation materials, please refer to the embodiments of the cross-linked network model construction and moisture absorption simulation method for anhydride-cured epoxy insulation materials described above.

[0135] The system for constructing cross-linked network models of anhydride-cured epoxy insulation materials includes: The monomer model building module is used to build molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer. The pre-ring-opening module is used to pre-open the anhydride ring of the methyltetrahydrophthalic anhydride monomer molecular model to obtain a pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model with two carboxyl groups. The curing reaction simulation module is used to simulate the curing reaction of bisphenol A diglycidyl ether monomer molecular models and pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular models, generating a dry crosslinking model with a three-dimensional network structure, which serves as the crosslinking network model for anhydride-cured epoxy insulation materials.

[0136] The anhydride-cured epoxy insulation material crosslinking network model construction system of this embodiment is used to realize the construction of crosslinking network model of anhydride-cured epoxy insulation material and the moisture absorption simulation method.

[0137] This application also provides an electronic device for implementing the various embodiments of this application. Figure 3 To illustrate the hardware structure of an electronic device according to various embodiments of this application, as shown in the following diagram... Figure 3 As shown, the electronic device includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor.

[0138] Those skilled in the art will understand that the electronic device structure involved in the embodiments of the application does not constitute a limitation on the electronic device. The electronic device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0139] In embodiments of this application, electronic devices include, but are not limited to, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Electronic devices may also represent various forms of mobile devices and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the embodiments of this application described and / or claimed herein.

[0140] In this application embodiment, the processor can be implemented using at least one of an Application-Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a processor, a controller, a microcontroller, a microprocessor, or an electronic unit designed to perform the functions described herein. In some cases, such implementations can be implemented within a controller. For software implementations, implementations such as processes or functions can be implemented with separate software modules that allow the performance of at least one function or operation. The software code can be implemented by a software application (or program) written in any suitable programming language, and the software code can be stored in memory and executed by the controller.

[0141] In addition, the electronic device includes some functional modules not shown, which will not be described in detail here.

[0142] Those skilled in the art will understand that the various aspects of the electronic device provided in this application can be implemented as a system, method, or program product. Therefore, the various aspects of this application can be specifically implemented in the following forms: a completely hardware implementation, a completely software implementation (including firmware, microcode, etc.), or a combination of hardware and software aspects, collectively referred to herein as a "circuit," "module," or "system."

[0143] This application also provides a storage medium storing a program product capable of constructing a crosslinked network model and simulating moisture absorption of anhydride-cured epoxy insulation materials. In some possible embodiments, various aspects of this application can also be implemented as a program product comprising program code that, when run on a terminal device, causes the terminal device to perform the steps described in the "Exemplary Methods" section of this specification according to various exemplary embodiments of this application.

[0144] The storage medium may be any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example,, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of readable storage media include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0145] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. 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 this application. Therefore, this application 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 constructing a crosslinked network model of an anhydride-cured epoxy insulating material, characterized in that, Includes the following steps: S1. Establish molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer; Labeling of the epoxy group reaction site atoms in the bisphenol A diglycidyl ether molecule, specifically including: The distal carbon atom in the epoxy group is labeled R1, and the oxygen atom in the epoxy group is labeled R3; S2. The anhydride ring of the methyltetrahydrophthalic anhydride monomer molecular model is pre-opened to obtain a pre-opened methyltetrahydrophthalic anhydride monomer molecular model with two carboxyl groups. The pre-ring-opening treatment of the anhydride ring in the methyltetrahydrophthalic anhydride monomer molecular model is as follows: The closed anhydride ring in the methyltetrahydrophthalic anhydride monomer molecule model was opened to two carboxyl groups, so that the molecule after ring opening has two active carboxyl sites. The atoms at the pre-opened anhydride ring reaction sites in the pre-opened methyltetrahydrophthalic anhydride monomer molecular model are labeled, specifically including: The carbonyl carbon atom formed by pre-opening the anhydride ring is labeled R4, and the hydroxyl oxygen atom is labeled R2. S3. The curing reaction simulation was carried out on the bisphenol A diglycidyl ether monomer molecular model and the pre-ring-opened methyltetrahydrophthalic anhydride monomer molecular model to generate a dry crosslinking model with a three-dimensional network structure, which serves as the crosslinking network model for anhydride-cured epoxy insulation material. The curing reaction simulation includes simulations of esterification, etherification, and hydroxyl curing reactions. The simulated esterification reaction is as follows: Pre-ring-opened methyltetrahydrophthalic anhydride reacts with the epoxy group of bisphenol A diglycidyl ether. The bonds between R1 and R3 are broken, causing the epoxy group to open. R1 and R2 form an ester group. The hydrogen atom on R2 is transferred to R3 to become a hydroxyl group. R1 is the distal carbon atom in the epoxy group, R2 is the hydroxyl oxygen atom formed by the pre-ring-opening of the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated etherification reaction is as follows: the hydroxyl group in the esterification product reacts with the epoxy group of bisphenol A diglycidyl ether. The R1 of the hydroxyl group in the esterification product breaks the bond with the R3 of the epoxy group of bisphenol A diglycidyl ether, causing the epoxy ring to open. R1 and R3 form an ether bond. The R3 of the newly reacted bisphenol A diglycidyl ether forms a new hydroxyl group with a hydrogen atom. R1 is the distal carbon atom in the epoxy group, R2 is the oxygen atom in the anhydride ring, and R3 is the oxygen atom in the epoxy group. The simulated hydroxyl curing reaction is as follows: the hydroxyl group in the esterification product reacts with the pre-opened ring methyltetrahydrophthalic anhydride, and R3 and R4, which have been converted into hydroxyl groups, form an ester group. At the same time, the hydrogen atom on the hydroxyl group in the reactant and the hydroxyl group on the pre-opened ring methyltetrahydrophthalic anhydride are deleted. Among them, R3 is the oxygen atom in the epoxy group and R4 is the carbonyl carbon atom formed by the pre-opening of the anhydride ring. When simulating the curing reaction, the reaction priorities of three types of reactions and the triggering conditions for the hydroxyl curing reaction are set. The specific reaction priorities of the three types of reactions are as follows: Esterification is the highest priority reaction, hydroxyl curing is the second highest priority reaction, and etherification is the lowest priority reaction; The hydroxyl curing reaction is triggered when the number of active R3 hydroxyl sites reaches 10. The etherification reaction is triggered when the number of active R3 hydroxyl sites reaches 15. Among them, the active R3 hydroxyl site is the hydroxyl group corresponding to the R3 atom with a hydrogen atom after esterification reaction; When simulating the curing reaction, an atomic locking mechanism for the reaction sites is employed: Once a certain reaction site atom is selected to enter the reaction queue, other reaction site atoms belonging to the same functional group as that reaction site atom are simultaneously locked and prohibited from participating in other reactions until the current bonding and relaxation process is completed.

2. The method for constructing a crosslinked network model of anhydride-cured epoxy insulating material as described in claim 1, characterized in that, In step S1, when establishing the molecular models of bisphenol A diglycidyl ether monomer and methyltetrahydrophthalic anhydride monomer, three-dimensional molecular configurations are constructed based on their actual molecular structural formulas. The specific implementation method for simulating the curing reaction in step S3 is to write and execute a Perl script. When the Perl script is executed, the following operations are performed: Within the set search radius, identify all possible bonding reaction site atom pairs, screen atom pairs according to reaction priority and functional group locked state, and perform bond breaking and bonding operations in a step-by-step approach, bonding, and relaxation manner until the crosslinking degree of the system reaches the preset target crosslinking degree; The degree of crosslinking of the system is calculated as the percentage of the number of bonded R1 site atoms to the total number of R1 site atoms.

3. A method for simulating the hygroscopic behavior of an anhydride-cured epoxy insulation material using a cross-linked network model, wherein the anhydride-cured epoxy insulation material cross-linked network model is constructed using the method for constructing an anhydride-cured epoxy insulation material cross-linked network model as described in any one of claims 1-2, characterized in that... Includes the following steps: S4. Using the cross-linked network model of anhydride-cured epoxy insulation material as the initial polymer model, obtain the effective free volume distribution of the initial polymer model; The specific method for obtaining the effective free volume distribution of the initial polymer model is as follows: The atomic coordinates of the initial polymer model are exported. The model space is discretized into a grid with a preset grid spacing. The minimum distance from each grid point to all polymer atoms is calculated. This minimum value is compared with the preset probe radius. If the minimum value is greater than the probe radius, the grid point is determined to belong to the effective free volume region. Otherwise, it is determined to be the polymer skeleton repulsion volume region. S5. Based on the effective free volume distribution of the initial polymer model, a probe scanning algorithm is used to identify the void regions that water molecules can occupy in the initial polymer model; When identifying the void regions that water molecules can occupy, cluster adjacent grid points belonging to the effective free volume region, and identify spatially continuous effective free volume grid point clusters as the same void region. S6. Calculate the number of water molecules to be inserted based on the preset macro water absorption rate, and target and insert the corresponding number of water molecule models into the void regions that water molecules can occupy in the initial polymer model to obtain the hygroscopic model. The specific method for targeting and inserting a corresponding number of water molecule models into the void regions that water molecules can occupy in the initial polymer model is as follows: randomly select a number of grid points equal to the number of water molecules from all grid points belonging to the void regions that water molecules can occupy as water molecule insertion sites, and place a water molecule model at each insertion site.

4. The method as described in claim 3, characterized in that, In step S5, the probe scanning algorithm is used to identify the void regions that water molecules can occupy in the initial polymer model, specifically including: Water molecules are approximated as spherical probes. The probes are scanned at the grid points corresponding to the effective free volume distribution of the initial polymer model with a preset probe radius. The spatial region formed by the grid points that meet the probe reachability conditions is identified as the void region that water molecules can occupy. The probe radius is 1.4 angstroms.

5. The method as described in claim 4, characterized in that, The probe reachability conditions are as follows: The current grid point belongs to the effective free volume distribution, and the distance between the current grid point and the neighboring polymer atoms is greater than the probe radius.

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