A method for establishing a molecular dynamics model of a polymer grouting material after corrosion

Abstract

The present invention discloses a method for establishing a molecular dynamics model of a polymer grouting material after corrosion, comprising the following steps: determination of the molecular weight of the polymer grouting material; infrared spectrum scanning and analysis of the polymer grouting material; chemical corrosion test; infrared spectrum experiment of the material after corrosion; comparative analysis of the infrared spectrum results before and after corrosion; determination of the molecular structure change of the polymer material after corrosion; establishment of the molecular dynamics model; the present invention adopts a qualitative analysis method to study the change of the microscopic structure at the atomic level of the polymer grouting material before and after corrosion, and uses molecular dynamics modeling software to establish the molecular dynamics model of the polymer grouting material after corrosion, which helps to more deeply study the microscopic mechanism of the change of the mechanical properties of the polymer grouting material before and after chemical corrosion, and provides a theoretical basis for the application of the polymer grouting material in a corrosive environment.

Description

Technical Field

[0001] The present invention relates to the research field of the micro-mechanical properties of polymer grouting materials, and particularly relates to a method for establishing a molecular dynamics model of polymer grouting materials after corrosion. Background Art

[0002] Non-aqueous reaction type polymer grouting materials are a new type of civil engineering material with good comprehensive performance and have been widely used in the field of infrastructure engineering. When polymer grouting materials are in service in actual projects, their mechanical properties are the key to ensuring good grouting repair effects.

[0003] In actual projects, polymer grouting materials are buried in rock and soil for a long time and will inevitably encounter the erosion of corrosive media such as acids and alkalis in urban sewage, seawater, and rainwater, resulting in continuous changes in their mechanical properties. At present, there are few studies on the mechanical property evolution mechanism of polymer grouting materials in chemical corrosion environments such as acids and alkalis, especially the research on the micro-mechanical properties of polymer grouting materials after corrosion has not been carried out. The molecular dynamics simulation method is a commonly used method for studying the mechanical properties of materials at the microscale, and the premise is to establish a reasonable molecular model of polymer grouting materials.

[0004] Existing technologies for establishing molecular models, such as a method for constructing a molecular dynamics geometric model of spinodal decomposition distribution with the patent number ZL202010667817.X, include the following steps: Step 1, based on the Cahn-Hilliard model, construct a phase field model for spinodal decomposition of the system, and use MATLAB to iterate the phase field model, and finally output the target concentration data of the block in vtk format; Step 2, based on the Python environment, call the vtk format file of the block target concentration data and store it in the form of a dictionary, which is the built-in type of sequences in Python; Step 3, create a molecular dynamics geometric model data file, establish the correspondence between the atomic coordinates and the coordinates of the blocks in the dictionary, and set the concentration threshold of the blocks; and according to the concentration threshold of the blocks, organize the molecular dynamics geometric model data file and output a new molecular dynamics model data file; Step 4, input the new molecular dynamics model data file into LAMMPS for molecular dynamics simulation. The above invention can be used for molecular dynamics simulation research on porous nano-metal materials. However, it is not applicable to the establishment of the molecular dynamics model of polymer grouting materials after corrosion in this application. Summary of the Invention

[0005] The purpose of the invention is to provide a method for establishing a molecular dynamics model of polymer grouting materials after corrosion, which solves the problem of the lack of research on the corrosion resistance of existing polymer grouting materials at the micro level. It provides a reliable simulation calculation tool for better application in engineering practice.

[0006] The present invention is implemented as follows. A method for establishing a molecular dynamics model of a polymer grouting material after corrosion, the method comprising the following steps:

[0007] Step S10: Determination of the molecular weight of the polymer grouting material: Use end-group analysis to determine the molecular weight of the polymer grouting material;

[0008] Step S20: Conduct an infrared spectroscopy experiment on the polymer grouting material. Based on the measured molecular weight of the polymer grouting material and the test results of the infrared spectroscopy experiment, determine the molecular structure, functional group types, and absorption peak intensities of different functional groups of the polymer grouting material;

[0009] Step S30: Chemical corrosion test: Place the polymer grouting material in a corrosion solution, and after treatment, obtain the polymer grouting material after corrosion;

[0010] Step S40: Conduct an infrared spectroscopy experiment on the polymer grouting material after corrosion to determine the functional group types and absorption peak intensities of different functional groups of the polymer grouting material after corrosion;

[0011] Step S50: According to the infrared spectroscopy experiment results of the polymer grouting material before corrosion in step S20 and the infrared spectroscopy experiment results of the polymer grouting material after corrosion in step S40, analyze the change rules of the microscopic results at the atomic level of the polymer grouting material before and after corrosion, and determine the changes in the molecular structure and functional groups at the atomic level of the polymer grouting material after corrosion;

[0012] Step S60: Establishment of the molecular dynamics model: According to the changes in the molecular structure and functional groups at the atomic level of the polymer grouting material after corrosion, construct a molecular chain model at the atomic level of the polymer grouting material after corrosion, and then establish a molecular dynamics model of the polymer grouting material after corrosion.

[0013] A further technical solution of the present invention is: The specific steps in step S10 are: Quantitatively analyze the number of functional groups at one or both ends of the molecular chain in the polymer grouting material by titration, and then calculate the molecular weight of the polymer.

[0014] A further technical solution of the present invention is: The specific steps in step S20 are: Mix potassium bromide powder and polymer grouting material powder and perform tablet pressing treatment, conduct an infrared spectroscopy experiment, obtain the spectrum of the infrared spectrum, and infer the chemical group information of the polymer grouting material from the positions and intensities of the infrared absorption peaks in the spectrum.

[0015] A further technical solution of the present invention is: The specific steps in step S20 are:

[0016] S21. Weigh 2 g of potassium bromide (KBr) into a 50 mL beaker, place it in an oven at 200 °C and dry for 4 - 6 hours for later use. Grind the original polymer grouting material into powder with a mortar and put it into a 1 mL small centrifuge tube for later use;

[0017] S22. Weigh 200 mg of dried KBr and 2 mg of polymer grouting material into a mortar, mix and grind until there are no KBr particles, then use a tablet pressing device for tablet pressing, press into a thin slice with a thickness of about 0.5 mm for testing, and continuously perform atmosphere compensation during the testing process;

[0018] S23. Analyze the obtained infrared spectrum, and infer the molecular structure characteristics and chemical group information such as the structural composition of the polymer grouting material through the position and intensity of the infrared absorption peaks in the spectrum.

[0019] A further technical solution of the present invention is: The specific steps in step S30 are: Place the polymer grouting material in a 10 wt% H2SO4 corrosion solution, seal it and place it in a dark place for soaking.

[0020] A further technical solution of the present invention is: The specific steps in step S30 are:

[0021] S31. Place the polymer grouting material in a plastic bucket containing 10 wt% H2SO4 solution, seal it and move it to a dark place, control the ambient temperature at about 25 °C and the humidity at about 40%, and soak for 28 days.

[0022] A further technical solution of the present invention is: The specific steps in step S40 are: After making the corroded polymer grouting material into powder, mix it with potassium bromide powder and perform tablet pressing treatment, conduct an infrared spectrum experiment, obtain the spectrum of the infrared spectrum of the corroded polymer grouting material, and infer the chemical group information of the corroded polymer grouting material through the position and intensity of the infrared absorption peaks in the spectrum.

[0023] A further technical solution of the present invention is: The specific steps in step S40 are:

[0024] S41. Carefully take out the polymer grouting material that has been corroded and soaked in the H2SO4 solution for 28 days from the solvent with tweezers, rinse it with running water for two to three minutes, and naturally dry it at room temperature before conducting an infrared spectrum experiment.

[0025] A further technical solution of the present invention is: The determination of the change in the atomic-level structure of the corroded polymer grouting material in step S50 includes the breakage of the molecular chain and the dissolution of the molecular chain after breakage.

[0026] A further technical solution of the present invention is: the step S50 determines the changes in the atomic-level microstructure of the polymer grouting material before and after corrosion based on the comparative analysis results of the spectra, including the breakage of the molecular chains and the dissolution of the molecular chains after the breakage.

[0027] A further technical solution of the present invention is: in step S60, Materials Studio modeling software is used to simulate the fracture of the atomic level structure and the change of functional groups of the polymer grouting material after corrosion, and a molecular chain model of the atomic level of the polymer grouting material after corrosion is constructed.

[0028] A further technical solution of the present invention is: in step S60, LAMMPS software is used to minimize the energy of the model based on the molecular chain model of the corroded polymer grouting material at the atomic level, and a molecular dynamics model that can accurately reflect the actual mechanical properties of the corroded polymer grouting material is established.

[0029] A further technical solution of the present invention is: the step S60 also includes simulating the atomic level structure of the polymer grouting material before corrosion based on the molecular structure, functional group type and absorption peak intensity of different functional groups of the polymer grouting material determined in step S20 using Materials Studio modeling software, constructing a molecular chain model of the polymer grouting material at the atomic level before corrosion, using the LAMMPS software package to minimize the energy of the model, and establishing a molecular dynamics model of the polymer grouting material before corrosion.

[0030] A further technical solution of the present invention is: step S60 also includes performing compression simulation experiments on the established molecular dynamics model of the polymer grouting material before corrosion and the established molecular dynamics model of the polymer grouting material after corrosion to obtain stress-strain curves, which can accurately reflect the compressive properties of the model, compare the changes in mechanical properties, and verify the correctness of the molecular dynamics model of the polymer grouting material after corrosion.

[0031] The beneficial effects of the present invention are as follows: the present invention first uses an end group analysis method to determine the molecular weight of a polymer grouting material, then uses infrared spectroscopy scanning to adopt a qualitative analysis method to study the changes in the atomic-level microstructure of the polymer grouting material before and after corrosion, and uses molecular dynamics modeling software to establish a molecular dynamics model of the polymer grouting material after corrosion. This facilitates a more in-depth study of the microscopic mechanism of changes in the mechanical properties of the polymer grouting material before and after chemical corrosion, and provides a theoretical basis for the application of polymer grouting materials in corrosive environments.

[0032] The present invention conducts compression simulation experiments on the polymer grouting material before and after corrosion, obtains the stress-strain curve, which can accurately reflect the compressive characteristics of the model, compares the changes in mechanical properties, and finds that the compressive strength of the model after corrosion is significantly lower than that before corrosion, effectively verifying the correctness of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. is a schematic flow chart of a method for establishing a molecular dynamics model of a polymer grouting material after corrosion in Embodiment 1 provided by the present invention;

[0034] Figure 2 FIG. is a comparison chart of the stress-strain curves of the polymer grouting material models before and after corrosion provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0036] It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limited conditions under which the present invention can be implemented. Therefore, they do not have a technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size should still fall within the scope that can be covered by the technical content disclosed in the present invention without affecting the effects that the present invention can produce and the purposes that can be achieved. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of description and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationships should also be regarded as the scope within which the present invention can be implemented without substantial change in the technical content.

[0037] Embodiment 1:

[0038] Figure 1 FIG. shows a method for establishing a molecular dynamics model of a polymer grouting material after corrosion, which is characterized by including the following steps:

[0039] S10. Determination of the molecular weight of the polymer grouting material;

[0040] The specific process is as follows:

[0041] S11. Quantitatively analyze the number of functional groups at one or both ends of the molecular chain in the polymer grouting material through titration, and then calculate the molecular weight of the polymer.

[0042] S20. Infrared spectrum scanning of the polymer grouting material;

[0043] The specific process is as follows:

[0044] S21. Weigh 2 g of potassium bromide (KBr) into a 50 mL beaker, place it in an oven at 200 °C for drying for 4 - 6 hours for standby. Grind the original polymer grouting material into powder in a mortar and put it into a 1 mL centrifuge tube for standby;

[0045] S22. Weigh 200 mg of dried KBr and 2 mg of the polymer grouting material into a mortar, mix and grind until there are no KBr particles, then use a tablet pressing device for tablet pressing, press into a thin slice with a thickness of about 0.5 mm for testing, and continuously perform atmosphere compensation during the testing process;

[0046] S23. Analyze the obtained infrared spectrum diagram, and infer the molecular structure characteristics and chemical group information such as the structural composition of the polymer grouting material through the position and intensity of the infrared absorption peaks in the spectrum diagram.

[0047] S30. Chemical corrosion test;

[0048] The specific process is as follows:

[0049] S31. Place the polymer grouting material in a plastic bucket containing 10 wt% H2SO4 solution, seal it and move it to a dark place, control the ambient temperature at about 25 °C and the humidity at about 40%, and soak for 28 days.

[0050] S40. Infrared spectrum scanning of the material after corrosion;

[0051] The specific process is as follows:

[0052] S41. Carefully take out the polymer grouting material of the grouting material after being corroded and soaked in the H2SO4 solution for 28 days from the solvent with tweezers, rinse it with running water for two to three minutes, and let it dry naturally at room temperature, then perform the specific steps in S20.

[0053] S50. Comparative analysis of the infrared spectrum results before and after corrosion: Compare the infrared spectrum diagrams of the polymer grouting material before and after being corroded by the H2SO4 solution, and compare and analyze the change rules of the microscopic structure at the atomic level of the polymer grouting material before and after corrosion through the changes in the position and intensity of the infrared absorption peaks in the spectrum diagram;

[0054] Determination of the change of the polymer material molecular structure: According to the comparison results of the spectrum diagrams in step S50, determine the changes in the molecular structure and functional groups at the atomic level of the polymer grouting material;

[0055] Specifically, for example, through 1110 cm in the spectrum diagram -1and 1210 cm -1 From the weakening of the stretching vibration peak of the ether bond (C-O-C) at [specific position], the cleavage of the ether bond can be inferred;

[0056] Through the weakening of the stretching vibration peak of C=O at 1710 cm -1 [specific position], the cleavage of the ester group is reflected;

[0057] S60, Establishment of molecular dynamics model: According to the changes in the molecular structure and functional groups of the polymer grouting material at the atomic level determined in step S50, use Materials Studio software to construct a molecular chain model of the polymer grouting material at the atomic level, and then use the LAMMPS software package to establish a molecular dynamics model of the corroded polymer grouting material.

[0058] Specifically, when using Materials Studio software to establish a single molecular chain of the corroded model, break some ester groups and ether bonds in the molecular chain, "dissolve" some short chains after cleavage, and supplement the corresponding hydrogen atoms to satisfy the charge balance;

[0059] Use Materials Studio software to assign CVFF force field parameters to the model,

[0060] Among them, the bond potential, bond angle potential and dihedral angle potential all adopt the form of simple harmonic vibration, and the non-bonded interaction potential adopts the standard 12-6 Lennard-Jones (LJ) potential style;

[0061] Use the LAMMPS software package to copy the established single molecular chain of the corrosion product into 15, and assign the NVT and NPT ensembles to the initial model. Perform a heating and cooling cycle on the unstable initial model under the ensemble to reach its most stable equilibrium state, and obtain the final model of the corroded polymer grouting material.

[0062] Example Two:

[0063] Verify the correctness of the model of the corroded polymer grouting material in Example One, including the following steps:

[0064] The first step: Establish a model of the polymer grouting material before corrosion: Step S60 also includes establishing a molecular dynamics model of the polymer grouting material before corrosion according to the molecular structure, types of functional groups and absorption peak intensities of different functional groups determined in step S20.

[0065] Step 2: Verify the correctness of the model of the polymer grouting material after corrosion: The step S60 further includes performing a compression simulation experiment on the established molecular dynamics model of the polymer grouting material before corrosion and the established molecular dynamics model of the polymer grouting material after corrosion to verify the correctness of the molecular dynamics model of the polymer grouting material after corrosion.

[0066] According to the molecular structure and functional groups of the polymer grouting material before corrosion determined in step S20, use Materials Studio software to construct a molecular chain model of the polymer grouting material at the atomic level, and then use the LAMMPS software package to establish a molecular dynamics model of the polymer grouting material before corrosion.

[0067] Specifically, when using Materials Studio software to establish a single chain of the pre-corrosion model molecule, the structural characteristics are truthfully reflected.

[0068] Use Materials Studio software to assign CVFF force field parameters to the model.

[0069] Among them, the bonding potential, bond angle potential, and dihedral angle potential all adopt the form of simple harmonic vibration, and the non-bonding interaction potential adopts the standard 12-6 Lennard-Jones (LJ) potential style.

[0070] Use the LAMMPS software package to copy the established single chain of the molecule before corrosion into 15, and assign the NVT and NPT ensembles to the initial model. Perform a heating and cooling cycle on the unstable initial model under the ensemble to reach its most stable equilibrium state, and obtain the final model of the polymer grouting material before corrosion.

[0071] In this embodiment, to ensure that the model is in an equilibrium state before the compression simulation, first use the NPT ensemble to relax the model at 300K and 1.0 ATM, and start the formal compression simulation when the energy change tends to be stable.

[0072] The uniaxial compression is along the Z-axis direction, carried out under periodic boundary conditions and the NPT ensemble, with a time step of 0.5 fs, a simulation temperature of 300K, a strain rate set to 5*1.0e8 / s, and a maximum strain of 0.5.

[0073] Output the stress-strain data obtained from the two models, and fit and draw a comparison graph of the stress-strain curves of the models before and after corrosion, as Figure 2 .

[0074] Compared with the original state model, the micro-mechanical properties of the corroded model have all decreased significantly, which is consistent with the results of the macroscopic mechanical property tests, verifying the correctness of the corroded model. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for establishing a molecular dynamics model of a corroded polymer grouting material, characterized by: The method includes the following steps: Step S10: Determination of the molecular weight of the polymer grouting material: Use the end-group analysis method to determine the molecular weight of the polymer grouting material; Step S20: Conduct an infrared spectroscopy experiment on the polymer grouting material. Based on the measured molecular weight of the polymer grouting material and the test results of the infrared spectroscopy experiment, determine the molecular structure, functional group types, and absorption peak intensities of different functional groups of the polymer grouting material; Step S30: Chemical corrosion test: Place the polymer grouting material in a corrosion solution, and obtain the polymer grouting material after corrosion after treatment; Step S40: Conduct an infrared spectroscopy experiment on the polymer grouting material after corrosion, and determine the functional group types and absorption peak intensities of different functional groups of the polymer grouting material after corrosion; Step S50: According to the infrared spectroscopy experiment results of the polymer grouting material before corrosion in Step S20 and the infrared spectroscopy experiment results of the polymer grouting material after corrosion in Step S40, analyze the change law of the microscopic results at the atomic level of the polymer grouting material before and after corrosion, and determine the changes in the molecular structure and functional groups at the atomic level of the polymer grouting material after corrosion; Step S60: Establishment of a molecular dynamics model: According to the changes in the molecular structure and functional groups at the atomic level of the polymer grouting material after corrosion, construct a molecular chain model at the atomic level of the polymer grouting material after corrosion, and then establish a molecular dynamics model of the polymer grouting material after corrosion; The determination of the change in the atomic-level structure of the polymer grouting material after corrosion in Step S50 includes the breakage of the molecular chain and the dissolution of the molecular chain after breakage.

2. The method for establishing a molecular dynamics model of a corroded polymer grouting material according to claim 1, characterized in that: The specific steps in Step S10 are: Quantitatively analyze the number of functional groups at one or both ends of the molecular chain in the polymer grouting material through titration, and then calculate the molecular weight of the polymer.

3. A method for establishing a molecular dynamics model of a polymer grouting material after corrosion according to claim 1 or 2, characterized in that The specific steps in Step S20 are: Mix potassium bromide powder and polymer grouting material powder and then perform tablet pressing treatment, conduct an infrared spectroscopy experiment, obtain the spectrum of the infrared spectrum, and infer the chemical group information of the polymer grouting material through the position and intensity of the infrared absorption peaks in the spectrum.

4. A method for establishing a molecular dynamics model of a polymer grouting material after corrosion according to claim 1 or 2, characterized in that The specific steps in Step S30 are: Place the polymer grouting material in a 10wt% H2SO4 corrosion solution, seal it, and place it in a dark place for soaking.

5. A method for establishing a molecular dynamics model of a polymer grouting material after corrosion according to claim 1 or 2, characterized in that The specific steps in Step S40 are: Make the polymer grouting material after corrosion into powder, mix it with potassium bromide powder, then perform tablet pressing treatment, conduct an infrared spectroscopy experiment, obtain the spectrum of the infrared spectrum of the polymer grouting material after corrosion, and infer the chemical group information of the polymer grouting material after corrosion through the position and intensity of the infrared absorption peaks in the spectrum.

6. The method for establishing a molecular dynamics model of a post-corrosion polymer grouting material according to claim 1 or 2, characterized in that, In Step S60, use the Materials Studio modeling software to simulate the breakage of the atomic-level structure and the changes in functional groups of the polymer grouting material after corrosion, and construct a molecular chain model at the atomic level of the polymer grouting material after corrosion.

7. The method for establishing a molecular dynamics model of a corroded polymer grouting material according to claim 1 or 2, characterized in that: In Step S60, use the LAMMPS software to minimize the energy of the model based on the molecular chain model at the atomic level of the polymer grouting material after corrosion, and establish a molecular dynamics model that can accurately reflect the mechanical properties of the polymer grouting material after actual corrosion.

8. A method for establishing a molecular dynamics model of a polymer grouting material after corrosion according to claim 1 or 2, characterized in that The step S60 further includes establishing a molecular dynamics model of the polymer grouting material before corrosion according to the molecular structure, functional group types, and the absorption peak intensity of different functional groups determined in step S20.

9. The method for establishing a molecular dynamics model of a corroded polymer grouting material according to claim 8, characterized in that: The step S60 further includes performing a compression simulation experiment on the established molecular dynamics model of the polymer grouting material before corrosion and the established molecular dynamics model of the polymer grouting material after corrosion to verify the correctness of the molecular dynamics model of the polymer grouting material after corrosion.

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