A method for constructing an epoxy asphalt thermal oxidation aging molecular model

Abstract

The application provides a construction method of an epoxy asphalt thermal oxygen aging molecular model, comprising the following steps: (1) constructing an unaged epoxy asphalt molecular model and relaxing the model; (2) constructing a mixed model of oxygen atoms and unaged epoxy asphalt; (3) writing a Perl language script, and realizing spontaneous reaction of the mixed model of oxygen atoms and epoxy asphalt through the Perl language script; (4) stopping the program after the target number of oxygen atoms is reached, and outputting the epoxy asphalt thermal oxygen aging molecular model. The application realizes the thermal oxygen aging process of epoxy asphalt through a script, determines the number of oxygen atoms increased in the thermal oxygen aging process according to the content change of oxygen elements, is consistent with the actual thermal oxygen aging mechanism in modeling thought, and obtains the epoxy asphalt thermal oxygen aging molecular model.

Description

Technical Field

[0001] This invention belongs to the field of polymer design and synthesis technology, and particularly relates to a method for constructing a molecular model of epoxy asphalt thermo-oxidative aging. Background Technology

[0002] Asphalt pavements are subjected to the combined effects of load, temperature, oxygen, ultraviolet radiation, and humidity during use, leading to defects such as cracking and spalling. Thermo-oxidative aging of the asphalt binder caused by high temperature and oxygen is the main reason for the degradation of asphalt pavement performance. Epoxy asphalt is a high-performance pavement material achieved through the cross-linking reaction of epoxy resin. Under the action of a curing agent, the epoxy functional groups of the epoxy resin undergo a ring-opening reaction and form a cross-linked network structure, enabling epoxy asphalt materials to maintain excellent tensile strength and aggregate adhesion even at high temperatures. However, epoxy asphalt materials also undergo thermo-oxidative aging, meaning that their performance deteriorates under the influence of high temperature and oxygen.

[0003] Previous studies on the thermo-oxidative aging behavior of epoxy asphalt mainly focused on analyzing its behavior and aging mechanism through mechanical property characterization combined with microscopic experiments. Simulation methods have not yet been applied to this research. Molecular dynamics simulation, a molecular-level computational technique, can be used to calculate the thermodynamic behavior of asphalt, the interfacial behavior between asphalt and aggregates, the propagation of asphalt cracks, and self-healing behavior. Furthermore, molecular dynamics simulation is also used to study the aging behavior of asphalt, primarily in the simulation of asphalt aging behavior evolution, the diffusion of recycling agents, and the diffusion between new and old asphalt.

[0004] However, since epoxy asphalt contains both epoxy resin and asphalt phases, its thermo-oxidative aging mechanism is complex, making the construction of a thermo-oxidative aging molecular model for epoxy asphalt quite difficult. The breakage and generation of functional groups in the epoxy asphalt molecular model during thermo-oxidative aging require scripting. Therefore, clarifying the construction method of the thermo-oxidative aging molecular model of epoxy asphalt is of great significance for the study of its thermo-oxidative aging behavior. Summary of the Invention

[0005] In view of this, the present invention proposes a method for constructing a molecular model of thermo-oxidative aging of epoxy asphalt, which can provide efficient theoretical guidance for the study of thermo-oxidative aging performance of epoxy asphalt.

[0006] This invention provides a method for constructing a crosslinked molecular model of carboxylic acid-cured epoxy asphalt, comprising: constructing a crosslinked molecular model of epoxy asphalt using epoxy resin, curing agent, and asphalt in Materials Studio software, and a COMPASSII force field, including the following steps.

[0007] S1: Molecular Model Construction: Constructing single-molecule models of epoxy resin, curing agent, and asphalt;

[0008] S2: Constructing a stable configuration: Based on the proportions of each component of the asphalt and the percentage of epoxy resin in the epoxy asphalt, a molecular model of the epoxy asphalt is constructed, and its stable configuration is obtained through a relaxation process.

[0009] S3: Constructing a molecular model of epoxy asphalt after thermo-oxidative aging: Determine the reaction assumptions for thermo-oxidative aging, write a Perl script for thermo-oxidative aging based on the reaction mechanism of epoxy asphalt thermo-oxidative aging, realize the spontaneous reaction of epoxy asphalt thermo-oxidative aging through the script, and obtain a molecular model of epoxy asphalt after thermo-oxidative aging.

[0010] S4: Labeling of reactive molecules and reactive atoms: Label the reactive carbon atoms in the reactant molecules of asphalt, epoxy resin, and curing agent as RC and the reactive sulfur atoms as RS, respectively;

[0011] S5: Constructing an epoxy asphalt-oxygen atom hybrid model: Based on the changes in oxygen content before and after thermo-oxidative aging, determine the increase in oxygen atoms in the molecular model after aging, construct an epoxy asphalt-oxygen atom hybrid model, and name the oxygen atom RO;

[0012] S6: Parameter Determination: Determine the cutoff radius range, target crosslinking degree, and initial cutoff radius R. now The increment of the cutoff radius for each cycle;

[0013] S7: Calculation: Calculate the distances between the reaction atoms RS, RC and RO in the model, and their relationship with R. now For comparison, if the atomic distances of RS, RC, and RO are less than R... now Then, the following crosslinking reaction is completed for the reaction atoms RS, RC, and RO according to the reaction mechanism:

[0014] I. The CH bond of the reactant atom RC is broken;

[0015] II. After the bond is broken, the reacting atoms RC and RO connect to form C=O;

[0016] III. The reactant atom RS connects with RO to form S=O;

[0017] If the atomic distance between RS, RC and RO is greater than R now If so, proceed to step S8;

[0018] S8: Order Repeat step S7 until the increase in oxygen atoms in the model reaches the target value. At this point, the construction of the epoxy asphalt thermo-oxidative aging molecular model is complete. Finally, perform relaxation and output of the epoxy asphalt thermo-oxidative aging molecular model.

[0019] Preferably, the epoxy asphalt thermo-oxidative aging mechanism determined in step S3 is as follows:

[0020] (1) The first carbon atom attached to the benzene ring undergoes oxidation to form a carbonyl group;

[0021] (2) Sulfur atoms undergo oxidation to generate sulfoxide groups.

[0022] Preferably, the reaction assumptions introduced in step S3 are as follows:

[0023] (1) All reactants have the same atomic reactivity;

[0024] (2) The reaction is controlled only by the distance between the reacting atoms.

[0025] Preferably, steps S2 and S8 further include the following steps:

[0026] (1) 20,000 geometric optimization steps were performed on the constructed epoxy asphalt molecular model and epoxy asphalt thermo-oxidative aging molecular model in the COMPASSII force field.

[0027] (2) Perform dynamic calculations on the geometrically optimized molecular model under the NVT ensemble at 500 ps;

[0028] (3) Perform dynamic calculations on the obtained molecular model under the NPT ensemble at 2000ps with a pressure of one atmosphere to make the epoxy asphalt molecular model reach the true density.

[0029] (4) Perform a second 2000ps NVT ensemble dynamic calculation on the obtained molecular model to further diffuse the epoxy asphalt molecular model and obtain the trajectory file of the epoxy asphalt molecular model before and after thermo-oxidative aging with sufficient diffusion. The relaxation process temperature is set according to actual needs, and the step size is 0.1 to 1fs.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] This invention provides a method for constructing a molecular model of epoxy asphalt after thermo-oxidative aging. The constructed molecular model of epoxy asphalt after thermo-oxidative aging is consistent with the actual thermo-oxidative aging epoxy asphalt system. This model can be used to represent epoxy asphalt aged at 60-120℃ for 10 days with good accuracy. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the formation of the molecular model of epoxy asphalt after thermo-oxidative aging according to the present invention.

[0033] Figure 2 Molecular trajectories of epoxy asphalt before and after thermo-oxidative aging to ensure sufficient diffusion;

[0034] Figure 3 A diagram illustrating the mechanism for carbonyl group formation at the carbon atom attached to the benzene ring in E51;

[0035] Figure 4 This is a mechanism diagram showing the formation of carbonyl groups at carbon atoms connected to benzene rings and sulfoxide groups at sulfur atoms in asphalt molecules under the action of thermo-oxidative aging. The red circle represents the reacting carbon atom RC, and the blue circle represents the reacting sulfur atom RS.

[0036] Figure 5 To construct a mixed model of epoxy asphalt and oxygen atoms;

[0037] Figure 6 Output the results of the epoxy asphalt thermo-oxidative aging (120℃, 10 days) model;

[0038] Figure 7 Output results of the epoxy asphalt thermo-oxidative aging (60℃, 10 days) model. Detailed Implementation

[0039] Example 1

[0040] Bisphenol A type epoxy resin E51 was used as the epoxy resin component, adipic acid curing agent as the curing agent component, and AAA-1 matrix asphalt molecular model as the asphalt component. An epoxy asphalt molecular model was constructed and subjected to thermo-oxidative aging at 120℃ for 10 days.

[0041] All the following implementation processes were performed in Materials Studio software, using the COMPASSII force field.

[0042] (1) Constructing molecular models of epoxy resin E51 and adipic acid:

[0043] Based on the molecular formulas of epoxy resin E51 and adipic acid, molecular models of both are drawn in the Sketch module. The drawn molecular models are then geometrically optimized in the Forcite module, with a maximum of 5000 iterations, to obtain molecular models of epoxy resin E51 and adipic acid with stable configurations.

[0044] (2) Constructing a single-molecule model of the matrix asphalt:

[0045] The AAA-1 matrix bitumen model, commonly used in the literature, was selected. Based on the molecular formulas of the representative molecules in the AAA-1 model, molecular models of the representative molecules were drawn in the Sketch module. The drawn molecular models were then subjected to Geometry Optimization in the Forcite module, with a maximum of 10,000 iterations, to obtain representative molecular models with stable configurations.

[0046] (3) Constructing the molecular model of epoxy asphalt:

[0047] In the Amorphous Cell module, according to the actual formulation, representative molecules of AAA-1, 25 molecules of epoxy resin E51, and 120 molecules of adipic acid were placed in a container with a density of 0.1 g / cm³. 3 In the box, an initial molecular model of epoxy asphalt is formed. The relaxation process of the initial molecular model of epoxy asphalt is carried out, and the specific steps are as follows: 1) In the COMPASSII force field, 20,000 steps of geometric optimization are performed on the molecular model of epoxy asphalt constructed in (3) and (5) and the molecular model of epoxy asphalt thermo-oxidative aging; 2) The molecular model after geometric optimization is subjected to kinetic calculation under the NVT ensemble of 500ps; 3) The obtained molecular model is subjected to kinetic calculation under the NPT ensemble of 2000ps with a pressure of 0.0001GPa to make the molecular model of epoxy asphalt reach the true density; 4) The obtained molecular model is subjected to the second kinetic calculation under the NVT ensemble of 2000ps to make the molecular model of epoxy asphalt diffuse further, and the trajectory file of the molecular model of epoxy asphalt before and after thermo-oxidative aging with sufficient diffusion is obtained. The configuration of the last frame is as follows. Figure 2 As shown in the figure. The relaxation process temperature is 298.15 K, and the step size is 1 fs.

[0048] (4) Determine the thermo-oxidative aging conditions for epoxy asphalt. Based on the thermo-oxidative aging mechanism of epoxy asphalt, write a Perl script for thermo-oxidative aging. The script will be used to realize the spontaneous reaction of epoxy asphalt thermo-oxidative aging. The specific process is as follows:

[0049] 1) The thermo-oxidative aging temperature of epoxy asphalt was determined to be 120℃ and the aging time to be 10 days.

[0050] 2) Determine the thermo-oxidative aging mechanism of E51, adipic acid, and asphalt: I. Carbonyl groups are generated at the carbon atoms attached to the benzene ring in E51, such as... Figure 3 As shown; II. Adipic acid has a saturated structure, therefore it is believed that adipic acid does not undergo thermo-oxidative aging reaction; III. Under the action of thermo-oxidative aging, asphalt molecules generate carbonyl groups at the carbon atoms connected to the benzene ring and sulfoxide groups at the sulfur atoms, as shown. Figure 4 As shown.

[0051] 3) Introduce reaction assumptions: I. All reactant atoms have the same reactivity; II. The reaction is controlled only by the distance between reactant atoms.

[0052] (5) Labeling reaction atoms: The reaction carbon atoms in epoxy resin E51 molecules and asphalt molecules are labeled as RC and the reaction sulfur atoms as RS using the Edit module;

[0053] (6) The changes in oxygen content in the epoxy asphalt molecular model and the actual epoxy asphalt system before and after aging are shown in Table 1. Equation 1 determines the increase in oxygen atoms in the molecular model after aging to be 61. An epoxy asphalt-oxygen atom hybrid model is then constructed as follows: Figure 5 As shown, the oxygen atom is named RO.

[0054] Table 1. Oxygen content of epoxy asphalt

[0055]

[0056]

[0057] Wt 模型-老化后 Represents the oxygen content in the molecular model after aging; Wt 模型-未老化 The oxygen content in the unaged molecular model; Wt 实际-未老化 Wt represents the oxygen content in actual unaged epoxy asphalt; 实际-老化 This represents the oxygen atom content in epoxy asphalt after actual thermo-oxidative aging.

[0058] Wt after calculation 模型-老化后 The percentage was 9.700%, and the number of oxygen atoms added to the epoxy asphalt molecular model after thermo-oxidative aging was 61.

[0059] (7) Determine the maximum cutoff radius The target is to increase the number of oxygen atoms by 61, with an initial cutoff radius. The increase in the cutoff radius for each cycle is...

[0060] (8) Calculate the distances between all RC, RS, and RO atoms in the model and R. now For comparison, if the atomic distances of RC, RS, and RO are less than R... now Then, the following crosslinking reaction is completed for the reactant atoms RC, RS, and RO according to the reaction mechanism:

[0061] I. The CH bond of the reactant atom RC is broken;

[0062] II. After the bond is broken, the reacting atoms RC and RO connect to form C=O;

[0063] III. The reactant atom RS connects with RO to form S=O;

[0064] If the atomic distance between RC, RS, and RO is greater than R now If so, proceed to step (9).

[0065] (9) Let R now =R now +0.5, repeat step (8) until the target number of oxygen atoms is reached. At this point, the construction of the epoxy asphalt thermo-oxidative aging molecular model is complete. During the execution of this script, R now When the oxygen atom count reaches 15, the number of oxygen atoms increases to 61, reaching the target number of oxygen atoms, and the program stops.

[0066] (10) Relaxation of the epoxy asphalt thermo-oxidative aging molecular model. Specific steps: In the COMPASSII force field, 20,000 steps of geometric optimization were performed on the epoxy asphalt molecular model constructed in (3) and (5). Under the NVT ensemble, a 500ps dynamic calculation was performed on the geometrically optimized epoxy asphalt molecular model to obtain the trajectory file and extract the last frame of the obtained trajectory file; a 2000ps dynamic calculation was performed on the last frame file under the NPT ensemble with a pressure of 0.0001GPa to make the epoxy asphalt molecular model reach the true density and obtain the trajectory file and extract the last frame of the trajectory file; a second 2000ps dynamic calculation was performed on the last frame file under the NVT ensemble to further diffuse the epoxy asphalt molecular model and obtain a fully diffused epoxy asphalt molecular model trajectory file. The relaxation process temperature was 298.15K and the step size was 1fs.

[0067] (11) Output of the epoxy asphalt thermo-oxidative aging model, such as Figure 6 As shown.

[0068] (12) The calculated values ​​of each technical index were obtained based on the epoxy asphalt thermo-oxidative aging molecular model and compared with the measured values, as shown in Table 2. As can be seen from Table 2, the calculated value of density Tg is relatively close to the measured value, and the error is within a reasonable range. Therefore, it can be considered that the constructed epoxy asphalt thermo-oxidative aging molecular model is consistent with the actual thermo-oxidative aging epoxy asphalt system. This model can be used to represent epoxy asphalt aged at 120℃ for 10 days.

[0069] Table 2 Calculated and measured values ​​of technical indicators for thermo-oxidative aging epoxy asphalt

[0070]

[0071] Example 2

[0072] Bisphenol A type epoxy resin E51 was used as the epoxy resin component, adipic acid curing agent as the curing agent component, and AAA-1 matrix asphalt molecular model as the asphalt component. An epoxy asphalt molecular model was constructed and subjected to thermo-oxidative aging at 60℃ for 10 days.

[0073] All the following implementation processes were performed in Materials Studio software, using the COMPASSII force field.

[0074] (1) Constructing molecular models of epoxy resin E51 and adipic acid:

[0075] Based on the molecular formulas of epoxy resin E51 and adipic acid, molecular models of both are drawn in the Sketch module. The drawn molecular models are then geometrically optimized in the Forcite module, with a maximum of 5000 iterations, to obtain molecular models of epoxy resin E51 and adipic acid with stable configurations.

[0076] (2) Constructing a single-molecule model of the matrix asphalt:

[0077] The AAA-1 matrix bitumen model, commonly used in the literature, was selected. Based on the molecular formulas of the representative molecules in the AAA-1 model, molecular models of the representative molecules were drawn in the Sketch module. The drawn molecular models were then subjected to Geometry Optimization in the Forcite module, with a maximum of 10,000 iterations, to obtain representative molecular models with stable configurations.

[0078] (3) Constructing the molecular model of epoxy asphalt:

[0079] In the Amorphous Cell module, according to the actual formulation, representative molecules of AAA-1, 25 molecules of epoxy resin E51, and 120 molecules of adipic acid were placed in a container with a density of 0.1 g / cm³. 3 In the box, an initial molecular model of epoxy asphalt is formed. The relaxation process of the initial molecular model of epoxy asphalt is carried out, and the specific steps are as follows: 1) In the COMPASSII force field, 20,000 steps of geometric optimization are performed on the molecular model of epoxy asphalt constructed in (3) and (5) and the molecular model of epoxy asphalt thermo-oxidative aging; 2) The molecular model after geometric optimization is subjected to kinetic calculation under the NVT ensemble of 500ps; 3) The obtained molecular model is subjected to kinetic calculation under the NPT ensemble of 2000ps with a pressure of 0.0001GPa to make the molecular model of epoxy asphalt reach the true density; 4) The obtained molecular model is subjected to the second kinetic calculation under the NVT ensemble of 2000ps to make the molecular model of epoxy asphalt diffuse further, and the trajectory file of the molecular model of epoxy asphalt before and after thermo-oxidative aging with sufficient diffusion is obtained, such as Figure 2 As shown in the figure. The relaxation process temperature is 298.15 K, and the step size is 1 fs.

[0080] (4) Determine the thermo-oxidative aging conditions for epoxy asphalt. Based on the thermo-oxidative aging mechanism of epoxy asphalt, write a Perl script for thermo-oxidative aging. The script will be used to realize the spontaneous reaction of epoxy asphalt thermo-oxidative aging. The specific process is as follows:

[0081] 1) The thermo-oxidative aging temperature of epoxy asphalt was determined to be 60℃ and the aging time to be 10 days.

[0082] 2) Determine the thermo-oxidative aging mechanism of E51, adipic acid, and asphalt: I. Carbonyl groups are generated at the carbon atoms attached to the benzene ring in E51, such as... Figure 3 As shown; II. Adipic acid has a saturated structure, therefore it is believed that adipic acid does not undergo thermo-oxidative aging reaction; III. Under the action of thermo-oxidative aging, asphalt molecules generate carbonyl groups at the carbon atoms connected to the benzene ring and sulfoxide groups at the sulfur atoms, as shown. Figure 4 As shown.

[0083] 3) Introduce reaction assumptions: I. All reactant atoms have the same reactivity; II. The reaction is controlled only by the distance between reactant atoms.

[0084] (5) Labeling reaction atoms: The reaction carbon atoms in epoxy resin E51 molecules and asphalt molecules are labeled as RC and the reaction sulfur atoms as RS using the Edit module;

[0085] (6) The changes in oxygen content in the epoxy asphalt molecular model and the actual epoxy asphalt system before and after aging are shown in Table 2. The increase in oxygen atoms in the molecular model after aging is determined by Equation 2, and an epoxy asphalt-oxygen atom hybrid model is constructed as follows: Figure 5 As shown, the oxygen atom is named RO.

[0086] Table 2 Oxygen content of epoxy asphalt

[0087]

[0088]

[0089] Wt 模型-老化后 Represents the oxygen content in the molecular model after aging; Wt 模型-未老化 The oxygen content in the unaged molecular model; Wt 实际-未老化 Wt represents the oxygen content in actual unaged epoxy asphalt; 实际-老化 This represents the oxygen atom content in epoxy asphalt after actual thermo-oxidative aging.

[0090] Wt after calculation 模型-老化后 The percentage was 9.448%, and the number of oxygen atoms added to the epoxy asphalt molecular model after thermo-oxidative aging was 40.

[0091] (7) Determine the maximum cutoff radius The target is to increase the number of oxygen atoms by 40, with an initial cutoff radius. The increase in the cutoff radius for each cycle is...

[0092] (8) Calculate the distances between all RC, RS, and RO atoms in the model and R. now For comparison, if the atomic distances of RC, RS, and RO are less than R... now Then, the following crosslinking reaction is completed for the reactant atoms RC, RS, and RO according to the reaction mechanism:

[0093] I. The CH bond of the reactant atom RC is broken;

[0094] II. After the bond is broken, the reacting atoms RC and RO connect to form C=O;

[0095] III. The reactant atom RS connects with RO to form S=O;

[0096] If the atomic distance between RC, RS, and RO is greater than R now If so, proceed to step (9).

[0097] (9) Let R now =R now +0.5, repeat step (8) until the target number of oxygen atoms is reached. At this point, the construction of the epoxy asphalt thermo-oxidative aging molecular model is complete. During the execution of this script, R now When the oxygen atom count is 12, the number of oxygen atoms is increased by 40 to reach the target number of oxygen atoms, and the program stops.

[0098] (10) Relaxation of the epoxy asphalt thermo-oxidative aging molecular model. Specific steps: In the COMPASSII force field, 20,000 steps of geometric optimization were performed on the epoxy asphalt molecular model constructed in (3) and (5). Under the NVT ensemble, a 500ps dynamic calculation was performed on the geometrically optimized epoxy asphalt molecular model to obtain the trajectory file and extract the last frame of the obtained trajectory file; a 2000ps dynamic calculation was performed on the last frame file under the NPT ensemble with a pressure of 0.0001GPa to make the epoxy asphalt molecular model reach the true density and obtain the trajectory file and extract the last frame of the trajectory file; a second 2000ps dynamic calculation was performed on the last frame file under the NVT ensemble to further diffuse the epoxy asphalt molecular model and obtain a fully diffused epoxy asphalt molecular model trajectory file. The relaxation process temperature was 298.15K and the step size was 1fs.

[0099] (11) Output of the epoxy asphalt thermo-oxidative aging model, such as Figure 7 As shown.

[0100] (12) The calculated values ​​of each technical index were obtained based on the epoxy asphalt thermo-oxidative aging molecular model and compared with the measured values, as shown in Table 3. As can be seen from Table 3, the calculated value of density Tg is relatively close to the measured value, and the error is within a reasonable range. Therefore, it can be considered that the constructed epoxy asphalt thermo-oxidative aging molecular model is consistent with the actual thermo-oxidative aging epoxy asphalt system. This model can be used to represent epoxy asphalt aged at 60℃ for 10 days.

[0101] Table 3 Calculated and measured values ​​of technical indicators for thermo-oxidative aging epoxy asphalt

[0102]

[0103] Example 3

[0104] A method for constructing a molecular model of thermo-oxidative aging of epoxy asphalt, the flowchart of which is shown below. Figure 1 As shown, it includes the following steps:

[0105] (1) Draw the representative molecules of epoxy resin, curing agent and asphalt using the Sketch function of Materials Studio software;

[0106] (2) In the COMPASSII force field, the molecular model constructed in (1) is geometrically optimized to obtain epoxy resin molecules, curing agent molecules, and representative molecules of the four asphalt components with stable configurations.

[0107] (3) Based on the proportion of each component of asphalt and the proportion of epoxy resin in epoxy asphalt, construct an epoxy asphalt molecular model in the Amorphous Cell module that includes epoxy resin molecules, curing agent molecules, and asphalt four component representative molecules.

[0108] (4) and obtains its stable configuration through a relaxation process;

[0109] (5) Determine the thermo-oxidative aging conditions. Based on the thermo-oxidative aging reaction mechanism of epoxy asphalt, write a Perl script for thermo-oxidative aging. Implement the spontaneous reaction of epoxy asphalt thermo-oxidative aging through the script to obtain the molecular model of epoxy asphalt after thermo-oxidative aging. The flowchart is as follows. Figure 1 As shown, it includes the following steps:

[0110] 1) Determine the aging mechanism of the thermo-oxidative aging process of each component of epoxy asphalt;

[0111] 2) Clarify the assumptions and conditions of the thermo-oxidative aging reaction;

[0112] 3) Label the carbon atom in the reaction molecules of asphalt, epoxy resin, and curing agent as RC and the sulfur atom as RS, respectively.

[0113] 4) Based on the changes in oxygen content before and after thermo-oxidative aging, determine the increase in oxygen atoms in the molecular model after aging, construct an epoxy asphalt-oxygen atom hybrid model, and name the oxygen atom RO.

[0114] 5) Determine the cutoff radius range, target crosslinking degree, and initial cutoff radius R. now The increment of the cutoff radius for each cycle.

[0115] 6) Calculate the distances between the reaction atoms RS, RC, and RO in the model, and compare them with R. now For comparison, if the atomic distances of RS, RC, and RO are less than R... now Then, the following crosslinking reaction is completed for the reaction atoms RS, RC, and RO according to the reaction mechanism:

[0116] I. The CH bond of the reactant atom RC is broken;

[0117] II. After the bond is broken, the reacting atoms RC and RO connect to form C=O;

[0118] III. The reactant atom RS connects with RO to form S=O;

[0119] If the atomic distance between RS, RC and RO is greater than R now Then proceed to step 7).

[0120] 7) Let R now =R now +0.5, repeat step 6) until the increase in oxygen atoms in the model reaches the target value, at which point the construction of the epoxy asphalt thermo-oxidative aging molecular model is completed.

[0121] (6) Relaxation of the molecular model of thermo-oxidative aging of epoxy asphalt.

[0122] (7) Output of the molecular model of thermo-oxidative aging of epoxy asphalt.

[0123] Preferably, the thermo-oxidative aging mechanism of epoxy asphalt determined in step 1) is as follows:

[0124] (1) The first carbon atom attached to the benzene ring undergoes oxidation to form a carbonyl group;

[0125] (2) Sulfur atoms undergo oxidation to generate sulfoxide groups.

[0126] Preferably, the reaction assumptions introduced in step 2) are as follows:

[0127] (1) All reactants have the same atomic reactivity;

[0128] (2) The reaction is controlled only by the distance between the reacting atoms.

[0129] Preferably, steps (4) and (6) are as follows:

[0130] (1) In the COMPASSII force field, 20,000 steps of geometric optimization were performed on the epoxy asphalt molecular model and epoxy asphalt thermo-oxidative aging molecular model constructed in (3) and (5);

[0131] (2) Perform dynamic calculations on the geometrically optimized molecular model under the NVT ensemble at 500 ps;

[0132] (3) Perform dynamic calculations on the obtained molecular model under the NPT ensemble at 2000ps and the pressure is 0.0001GPa to make the epoxy asphalt molecular model reach the true density.

[0133] (4) Perform a second 2000ps NVT ensemble kinetic calculation on the obtained molecular model to further diffuse the epoxy asphalt molecular model and obtain the trajectory files of the epoxy asphalt molecular model before and after thermo-oxidative aging with sufficient diffusion. The relaxation process temperature is set according to actual needs, and the step size is 0.1 to 1 fs.

[0134] This invention provides a method for constructing a molecular model of thermo-oxidative aging of epoxy asphalt, comprising the following steps:

[0135] (1) Construct an unaged molecular model of epoxy asphalt and relax the model; (2) Construct a hybrid model of oxygen atoms and unaged epoxy asphalt; (3) Write a Perl script and implement the spontaneous reaction of the hybrid model of oxygen atoms and epoxy asphalt through the Perl script; (4) Stop the program after reaching the target number of oxygen atoms and output the thermo-oxidative aging molecular model of epoxy asphalt. This invention realizes the thermo-oxidative aging process of epoxy asphalt through a script, determines the number of oxygen atoms added during the thermo-oxidative aging process based on the change in oxygen content, and the modeling idea is consistent with the actual thermo-oxidative aging mechanism, thus obtaining the thermo-oxidative aging molecular model of epoxy asphalt.

Claims

1. A method for constructing a crosslinked molecular model of carboxylic acid-cured epoxy asphalt, characterized in that: A crosslinked molecular model of epoxy asphalt was constructed in Materials Studio software using epoxy resin, curing agent, and asphalt, along with a COMPASSII force field. The process included the following steps: S1: Molecular Model Construction: Constructing single-molecule models of epoxy resin, curing agent, and asphalt; S2: Constructing a stable configuration: Based on the proportions of each component of the asphalt and the percentage of epoxy resin in the epoxy asphalt, a molecular model of the epoxy asphalt is constructed, and its stable configuration is obtained through a relaxation process. S3: Constructing a molecular model of epoxy asphalt after thermo-oxidative aging: Determine the reaction assumptions for thermo-oxidative aging, write a Perl script for thermo-oxidative aging based on the reaction mechanism of epoxy asphalt thermo-oxidative aging, realize the spontaneous reaction of epoxy asphalt thermo-oxidative aging through the script, and obtain a molecular model of epoxy asphalt after thermo-oxidative aging. S4: Labeling of reactive molecules and reactive atoms: Label the reactive carbon atoms in the reactant molecules of asphalt, epoxy resin, and curing agent as RC and the reactive sulfur atoms as RS, respectively; S5: Constructing an epoxy asphalt-oxygen atom hybrid model: Based on the changes in oxygen content before and after thermo-oxidative aging, determine the increase in oxygen atoms in the molecular model after aging, construct an epoxy asphalt-oxygen atom hybrid model, and name the oxygen atom RO; S6: Parameter Determination: Determine the cutoff radius range, target crosslinking degree, and initial cutoff radius R. now The increment of the cutoff radius for each cycle; S7: Calculation: Calculate the distances between the reaction atoms RS, RC and RO in the model, and their relationship with R. now For comparison, if the atomic distances of RS, RC, and RO are less than R... now Then, the following crosslinking reaction is completed for the reaction atoms RS, RC, and RO according to the reaction mechanism: I. The CH bond of the reactant atom RC is broken; II. After the bond is broken, the reacting atoms RC and RO connect to form C=O; The reactant atom RS connects with RO to form S=O; If the atomic distance between RS, RC and RO is greater than R now If so, proceed to step S8; S8: Let R now =R now +R Δ， R Δ= 0.5 Å, repeat step S7 until the increase in oxygen atoms in the model reaches the target value. At this point, the construction of the epoxy asphalt thermo-oxidative aging molecular model is completed. Finally, relax and output the epoxy asphalt thermo-oxidative aging molecular model.

2. The method according to claim 1, characterized in that, The thermo-oxidative aging mechanism of epoxy asphalt determined in step S3 is as follows: (1) The first carbon atom attached to the benzene ring undergoes oxidation to form a carbonyl group; (2) Sulfur atoms undergo oxidation to generate sulfoxide groups.

3. The method according to claim 1, characterized in that, The reaction assumptions introduced in step S3 are as follows: (1) All reactants have the same atomic reactivity; (2) The reaction is controlled only by the distance between the reacting atoms.

4. The method according to claim 1, characterized in that: Steps S2 and S8 also include the following steps: (1) 20,000 geometric optimization steps were performed on the constructed epoxy asphalt molecular model and epoxy asphalt thermo-oxidative aging molecular model in the COMPASSII force field; (2) Perform dynamic calculations on the geometrically optimized molecular model under the NVT ensemble at 500 ps; (3) Perform dynamic calculations on the obtained molecular model under the NPT ensemble at 2000 ps with a pressure of one atmosphere to make the epoxy asphalt molecular model reach the true density. (4) Perform a second 2000ps NVT ensemble dynamic calculation on the obtained molecular model to further diffuse the epoxy asphalt molecular model and obtain the trajectory file of the epoxy asphalt molecular model before and after thermo-oxidative aging with sufficient diffusion. The relaxation process temperature is set according to actual needs, and the step size is 0.1 to 1fs.

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