A method for explaining the strength of organic / inorganic interface based on thermodynamic law

Abstract

The application discloses a method for explaining organic / inorganic interface strength based on thermodynamic law, and relates to the technical field of coating thermodynamics. The method comprises the following steps: Step S01, preparing a composite coating; in the step of preparing the composite coating, initial wetting of fillers and a resin matrix, re-agglomeration in an unstable period and adsorption in a stable period are calculated and deduced. The method focuses on the micro-interface state of organic / inorganic and the thermodynamic law of interface bonding, and focuses on thermodynamic parameters such as surface energy, molecular diffusion energy and agglomeration potential energy of materials, analyzes atomic-level characteristics of the surface of inorganic materials and resin components, predicts the polarity and dispersion component of the surface energy of coating components through thermodynamic theory, associates the surface energy difference with the characteristics of the two-phase interface, and builds a new thermodynamic theory for explaining the interface interaction mechanism.

Description

Technical Field

[0001] This invention belongs to the field of coating thermodynamics, specifically, it relates to a method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws. Background Technology

[0002] Organic coatings are a commonly used method for protecting metals from corrosion. These coatings often incorporate inorganic fillers such as basalt flakes, glass flakes, silica, and iron oxide red to achieve a shielding effect and enhance the corrosion resistance of the composite coating. In composite coatings, the interfaces between inorganic fillers and organic resins, or between the metal substrate and organic resins, have complex structures. Molecules in the interface region are bound, reducing their mobility. The binding effect gradually weakens with increasing distance from the filler, creating a gradient at the interface. The strength of the organic / inorganic interface affects the service performance of the composite coating. Investigating the modification state of the filler surface is crucial for predicting the service performance of the coating. There are many methods to enhance the cohesion and adhesion of the composite coating by modifying the filler surface or pre-treating the metal substrate using surface activation.

[0003] Currently, the processes and equipment for developing new fillers are very mature, but there is a lack of guiding fundamental theories for the design of high-performance fillers. For example, there is a lack of basic research on the microscopic interface state of the organic resin / filler interface and the organic resin / metal substrate interface, the thermodynamic laws of interfacial bonding, and the internal stress field of the coating, which are related to the service performance of composite coatings. Furthermore, there is a lack of rational selection of preparation process parameters to achieve the theoretically optimal anti-corrosion performance of composite coatings. In addition, traditional mechanical interlocking theory, adsorption theory, chemical bonding theory, and interface enhancement theory cannot describe in detail the interaction mechanisms of all organic / inorganic interfaces, and cannot predict the interface strength and service performance of composite coatings based on the above methods.

[0004] In summary, this invention provides a method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws, in order to solve the above-mentioned problems. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws.

[0006] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0007] A method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws includes step S01: preparing a composite coating, and calculating and deriving the initial wetting of the filler and the resin matrix, the re-agglomeration during the unstable period, and the adsorption during the stable period during the preparation of the composite coating.

[0008] Step S11: During the impregnation process, the ratio of the adsorption energy between the filler and the resin to the adsorption energy between the fillers (W) is used. PF / W FF Predict the initial dispersion of fillers during the preparation of anti-corrosion coatings, calculate the contact angle between fillers and resin, and thus determine the dispersibility of fillers in resin;

[0009] Step S12: During the dispersion process, the packing material will re-agglomerate. The driving energy for re-agglomeration (ΔW) a The free energy change can be expressed as the difference between the filler / resin interface and the filler / filler interface and the coating / resin interface. The formula can be used to calculate whether the filler tends to agglomerate in the resin and whether it is conducive to dispersion.

[0010] Step S13: During the adsorption process, the activity of resin molecules at the interface is calculated using a calculation formula. The results of the activity can reflect the microscopic interface strength of the filler / resin.

[0011] Preferably, the surface change during the filler-resin interface wetting process in step S11 can be expressed by formula (1):

[0012] Formula (1)

[0013] (1) In the formula, θ is the contact angle of the resin on the filler surface, γ F For the surface energy of the filler, and These are the dispersive and polar components of the filler surface energy, respectively, with dimensions in mJ / m. 2 γ P For resin surface energy, and These are the dispersive and polar components of the resin surface energy, respectively. PF and W FF These are the adsorption energies between the filler and the resin, and the adsorption energies between the fillers, respectively. From formula (1), the following thermodynamic criterion can be obtained:

[0014]

[0015] Where, the smaller θ is, the larger cosθ is, W PF / W FF The larger the value, the better the wettability between the filler and the resin, and the easier it is for the filler to disperse.

[0016] Preferably, the reagglomeration energy in step S12 is calculated and expressed by formula (3):

[0017] Public Notice (3) ΔW a =W FF +W PP -W PF

[0018] (3) In the formula, ΔW a W is the driving force for reunion. FF and W PP These are the filler / filler interfacial free energy and the coating / resin interfacial free energy, respectively, W. PF Let be the free energy of the filler / resin interface. Substituting the surface energy expressions of the filler and resin into formula (3), we can obtain the following thermodynamic criterion:

[0019]

[0020] Wherein, ΔW a The larger the value, the more likely the filler is to agglomerate in the resin, which is not conducive to its dispersion.

[0021] Preferably, in step S13, the filler / resin binding energy (W) PF ) and the bonding energy of the coating / resin (W) PP The difference, i.e., the molecular diffusion energy (W) s This can be expressed by formula (5):

[0022] Formula (5)W S =W PF -W PP

[0023] Substituting the surface energy expressions for fillers and resins into formula (5) yields the following thermodynamic criterion:

[0024]

[0025] Among them, W s The larger the value, the less mobile the resin molecules are at the interface, indicating a stronger interaction between the two phases.

[0026] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all of the following advantages at the same time:

[0027] This method focuses on the microscopic interface state of organic / inorganic materials and the thermodynamic laws of interfacial bonding. It concentrates on thermodynamic parameters such as surface energy, molecular diffusion energy, and aggregation potential energy of materials, analyzes the atomic-level characteristics of inorganic material surfaces and resin components, predicts the polarity and dispersion components of the surface energy of coating components through thermodynamic theory, and correlates the surface energy difference with the interfacial characteristics of the two phases. It constructs a new thermodynamic theory to explain the interfacial interaction mechanism and the organic / inorganic interface strength, thereby predicting the mechanical properties and shielding performance of composite coatings. This invention provides theoretical guidance and technical support for the digital development of high-performance, long-life anti-corrosion fillers.

[0028] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings described below are merely some embodiments. Those skilled in the art can obtain other drawings based on these drawings without any creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram illustrating the interaction process between the spherical filler and the organic resin in one embodiment of the present invention;

[0031] Figure 2 This is a contour plot showing the characteristic "wetting-reagglomeration-adsorption" of epoxy resin E44 according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram illustrating the interaction process between the organic resin and the metal substrate according to an embodiment of the present invention;

[0033] Figure 4 This is a characteristic wetting-adsorption contour map of 316L stainless steel (polished with 2000# sandpaper + dust removal with deionized water + oil removal with ethanol) according to an embodiment of the present invention.

[0034] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0035] The invention will now be described in further detail with reference to the accompanying drawings.

[0036] Please see Figure 1-4 As shown, this embodiment provides a method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws, including the following embodiments;

[0037] Example 1: The packing material is spherical packing material;

[0038] Step S01: Prepare a composite coating. In preparing the composite coating, calculate and derive the initial wetting of the spherical filler with the resin matrix, the re-agglomeration during the unstable period, and the adsorption during the stable period. The size of the spherical filler is between 5 nm and 100 μm.

[0039] Step S11: During the impregnation process, the ratio of the adsorption energy between the spherical filler and the resin to the adsorption energy between the spherical fillers themselves (W) is used. PF / W FF The initial dispersion of spherical fillers in the preparation of anti-corrosion coatings is predicted, and the contact angle between the spherical fillers and the resin is calculated to determine the dispersibility of the spherical fillers in the resin.

[0040] Step S12: During the dispersion process, the spherical packing will re-agglomerate. The driving energy for re-agglomeration (ΔW) a The free energy change can be expressed as the difference between the spherical filler / resin interface and the coating / resin interface. The formula can be used to calculate whether the spherical filler tends to agglomerate in the resin and whether it is conducive to dispersion.

[0041] Step S13: During the adsorption process, the activity of resin molecules at the interface is calculated using a calculation formula. The results of the activity can reflect the microscopic interface strength of the spherical filler / resin.

[0042] In this embodiment, the surface change during the wetting process of the spherical filler and resin interface in step S11 can be expressed by formula (1):

[0043] Formula (1)

[0044] (1) In the formula, θ is the contact angle of the resin on the surface of the spherical filler, γ F For the surface energy of spherical fillers, and These are the dispersive and polar components of the surface energy of the spherical packing, respectively, with dimensions in mJ / m. 2 γ P For resin surface energy, and These are the dispersive and polar components of the resin surface energy, respectively. PF and W FF These represent the adsorption energy between the spherical packing material and the resin, and the adsorption energy between the spherical packing materials themselves. From formula (1), the following thermodynamic criterion can be obtained:

[0045]

[0046] Where, the smaller θ is, the larger cosθ is, W PF / W FF The larger the value, the better the wettability of the spherical filler with the resin, and the easier it is for the spherical filler to disperse.

[0047] In this embodiment, the reagglomeration energy in step S12 is calculated and expressed by formula (3):

[0048] Public Notice (3) ΔW a =W FF +W PP -W PF

[0049] (3) In the formula, ΔW a W is the driving force for reunion. FF and W PP These are the interfacial free energies of the spherical filler / spherical filler and the interfacial free energies of the coating / resin, respectively.PF Let be the free energy of the spherical filler / resin interface. Substituting the surface energy expressions for the spherical filler and resin into formula (3), we can obtain the following thermodynamic criterion:

[0050]

[0051] Wherein, ΔW a The larger the value, the more likely the spherical filler is to agglomerate in the resin, which is detrimental to its dispersion.

[0052] In this embodiment, the spherical filler / resin binding energy (W) in step S13 is... PF ) and the bonding energy of the coating / resin (W) PP The difference, i.e., the molecular diffusion energy (W) s This can be expressed by formula (5):

[0053] Formula (5)W S =W PF -W PP

[0054] Substituting the surface energy expressions for fillers and resins into formula (5) yields the following thermodynamic criterion:

[0055]

[0056] Among them, W s The larger the value, the less mobile the resin molecules are at the interface, indicating a stronger interaction between the two phases.

[0057] Example 2: The packing material is fibrous packing material.

[0058] Step S01: Prepare a composite coating. In the preparation of the composite coating, calculate and deduce the initial wetting of the fibrous filler with the resin matrix, the re-agglomeration in the unstable period and the adsorption in the stable period, and the size of the fibrous filler is between 5 nm and 100 μm.

[0059] Step S11: During the impregnation process, the ratio of the adsorption energy between the fibrous filler and the resin to the adsorption energy between the fibrous fillers themselves (W) is used. PF / W FF The initial dispersion of fibrous fillers in the preparation process of anti-corrosion coatings is predicted, and the contact angle between fibrous fillers and resin is calculated to determine the dispersibility of fibrous fillers in resin.

[0060] Step S12: During the dispersion process, the fibrous packing will re-agglomerate. The driving energy for re-agglomeration (ΔW) a The free energy change can be expressed as the difference between the fibrous filler / resin interface and the coating / resin interface. The formula can be used to calculate whether the fibrous filler tends to agglomerate in the resin and whether it is conducive to dispersion.

[0061] Step S13: During the adsorption process, the activity of resin molecules at the interface is calculated using a calculation formula. The results of the activity can reflect the microscopic interface strength of the fibrous filler / resin.

[0062] In this embodiment, the surface change during the wetting process of the fibrous filler and resin interface in step S11 can be expressed by formula (1):

[0063] Formula (1)

[0064] (1) In the formula, θ is the contact angle of the resin on the surface of the fibrous filler, γ F The surface energy of fibrous fillers, and These are the dispersive and polar components of the surface energy of the fibrous filler, respectively, with dimensions in mJ / m. 2 γ P For resin surface energy, and These are the dispersive and polar components of the resin surface energy, respectively. PF and W FF These represent the adsorption energies between the fibrous filler and the resin, and the adsorption energies between the fibrous fillers themselves, respectively. From formula (1), the following thermodynamic criterion can be obtained:

[0065]

[0066] Where, the smaller θ is, the larger cosθ is, W PF / W FF The larger the value, the better the wettability of the fibrous filler with the resin, and the easier it is for the fibrous filler to disperse.

[0067] In this embodiment, the reagglomeration energy in step S12 is calculated and expressed by formula (3):

[0068] Public Notice (3) ΔW a =W FF +W PP -W PF

[0069] (3) In the formula, ΔW a W is the driving force for reunion. FF and W PP These are the interfacial free energies of the fibrous filler / fibrous filler interface and the interfacial free energy of the coating / resin interface, respectively, W. PF Let be the free energy of the fibrous filler / resin interface. Substituting the surface energy expressions for the fibrous filler and resin into formula (3), we can obtain the following thermodynamic criterion:

[0070]

[0071] Wherein, ΔW a The larger the value, the more likely the fibrous filler is to agglomerate in the resin, which is detrimental to its dispersion.

[0072] In this embodiment, the fibrous filler / resin binding energy (W) in step S13 is... PF ) and the bonding energy of the coating / resin (W) PP The difference, i.e., the molecular diffusion energy (W) s This can be expressed by formula (5):

[0073] Formula (5)W S =W PF -W PP

[0074] Substituting the surface energy expressions for fillers and resins into formula (5) yields the following thermodynamic criterion:

[0075]

[0076] Among them, W s The larger the value, the less mobile the resin molecules are at the interface, indicating a stronger interaction between the two phases.

[0077] Example 3: The packing material is a sheet packing material.

[0078] Step S01: Prepare a composite coating. In the preparation of the composite coating, calculate and derive the initial wetting of the sheet filler with the resin matrix, the re-agglomeration in the unstable period and the adsorption in the stable period, and the size of the sheet filler is between 5 nm and 100 μm.

[0079] Step S11: During the impregnation process, the ratio of the adsorption energy between the sheet filler and the resin to the adsorption energy between the sheet fillers themselves (W) PF / W FF The initial dispersion of sheet fillers in the anti-corrosion coating preparation process is predicted, and the contact angle between sheet fillers and resin is calculated to determine the dispersibility of sheet fillers in resin.

[0080] Step S12: During the dispersion process, the sheet-like packing will re-agglomerate. The driving energy for re-agglomeration (ΔW) a The free energy change can be expressed as the difference between the change of the sheet filler / resin interface and the coating / resin interface. The formula can be used to calculate whether the sheet filler tends to agglomerate in the resin and whether it is conducive to dispersion.

[0081] Step S13: During the adsorption process, the activity of resin molecules at the interface is calculated using a calculation formula. The results of the activity can reflect the microscopic interface strength of the sheet filler / resin.

[0082] In this embodiment, the surface change during the wetting process of the sheet filler and resin interface in step S11 can be expressed by formula (1):

[0083] Formula (1)

[0084] (1) In the formula, θ is the contact angle of the resin on the surface of the sheet filler, and γF is the surface energy of the sheet filler. and These are the dispersive and polar components of the surface energy of the sheet-like filler, respectively, with dimensions in mJ / m. 2 γ P For resin surface energy, and These are the dispersive and polar components of the resin surface energy, respectively. PF and W FF These represent the adsorption energies between the sheet-like filler and the resin, and the adsorption energies between the sheet-like fillers themselves, respectively. From formula (1), the following thermodynamic criterion can be derived:

[0085]

[0086] Where, the smaller θ is, the larger cosθ is, W PF / W FF The larger the value, the better the wettability of the sheet filler with the resin, and the easier it is for the sheet filler to disperse.

[0087] In this embodiment, the reagglomeration energy in step S12 is calculated and expressed by formula (3):

[0088] Public Notice (3) ΔW a =W FF +W PP -W PF

[0089] (3) In the formula, ΔW a W is the driving force for reunion. FF and W PP These are the interfacial free energies of sheet filler / sheet filler and coating / resin, respectively, W. PF Let be the free energy of the sheet filler / resin interface. Substituting the surface energy expressions for the sheet filler and resin into formula (3), we can obtain the following thermodynamic criterion:

[0090]

[0091] Wherein, ΔW a The larger the value, the more likely the sheet filler is to agglomerate in the resin, which is detrimental to its dispersion.

[0092] In this embodiment, the bonding energy (W) of the sheet filler / resin in step S13 is... PF ) and the bonding energy of the coating / resin (W)PP The difference, i.e., the molecular diffusion energy (W) s This can be expressed by formula (5):

[0093] Formula (5)W s =W PF -W PP

[0094] Substituting the surface energy expressions for fillers and resins into formula (5) yields the following thermodynamic criterion:

[0095]

[0096] Among them, W s The larger the value, the less mobile the resin molecules are at the interface, indicating a stronger interaction between the two phases.

[0097] Example 4: The above formula can be used to calculate the interfacial strength of organic resin / metal substrate;

[0098] The wetting-adsorption process can be calculated during the calculation of the interfacial strength of the organic resin / metal substrate. The corresponding thermodynamic criteria are derived using formulas (1) and (5) in Example 1. At this time, the interfacial interaction process is divided into wetting-adsorption, such as... Figure 3 As shown; the "wetting-adsorption" curve of the action process is as follows: Figure 4 As shown.

[0099] In all of the above embodiments 1, 2, and 3, epoxy resin E44 was used, and epoxy resin E44 (surface energy value before curing) and Approximately 32 and 5 mJ / m respectively 2 Taking as an example, its "infiltration-reagglomeration-adsorption" contour map is as follows: Figure 2 As shown in the figure, IsoCA lines and Iso ΔW a lines and Iso W s The lines represent the thermodynamic criterion contour lines for the wetting, re-agglomeration, and adsorption processes, respectively. The Completewetting region in the figure represents the complete wetting of the filler in the resin; the Optimal region represents the optimal dispersion state of the filler in the resin, with a small tendency for re-agglomeration and a strong stable adsorption interface.

[0100] Specifically, this invention predicts the interfacial strength of composite coatings based on thermodynamic laws. It is aimed at composite coatings with only a single morphology and size of inorganic filler. When the filler inside the coating has multiple morphologies and sizes, its interfacial strength and even service performance cannot be predicted by this method alone.

[0101] This method analyzes the interaction process of organic / inorganic interfaces, deduces the thermodynamic evolution of the interaction process, determines the thermodynamic criteria of the interaction process, and judges the interface strength based on the quantitative difference of thermodynamic parameters.

[0102] Specifically, the sizes of spherical packing, fibrous packing, and sheet packing can all be between 5 nm and 100 μm.

[0103] This invention is not limited to the embodiments described above. Anyone should understand that structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention. Technical aspects, shapes, and structures not described in detail in this invention are all publicly known technologies.

Claims

1. A method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws, characterized in that, Includes the following steps; Step S01: Prepare the composite coating. In the preparation of the composite coating, calculate and deduce the initial wetting of the filler and the resin matrix, the re-agglomeration during the unstable period, and the adsorption during the stable period. Step S11: During the impregnation process, the ratio of the adsorption energy between the filler and the resin to the adsorption energy between the fillers (W) is used. PF / W FF Predict the initial dispersion of fillers during the preparation of anti-corrosion coatings, calculate the contact angle between fillers and resin, and thus determine the dispersibility of fillers in resin; Step S12: During the dispersion process, the packing material will re-agglomerate. The driving energy for re-agglomeration (ΔW) a The free energy change can be expressed as the difference between the filler / resin interface and the filler / filler interface and the coating / resin interface. The formula can be used to calculate whether the filler tends to agglomerate in the resin and whether it is conducive to dispersion. Step S13: During the adsorption process, the activity of resin molecules at the interface is calculated using a calculation formula. The results of the activity can reflect the microscopic interface strength of the filler / resin.

2. The method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws according to claim 1, characterized in that, The surface changes during the filler-resin interface wetting process in step S11 can be expressed by formula (1): Formula (1) (1) In the formula, θ is the contact angle of the resin on the filler surface, γ F For the surface energy of the filler, and These are the dispersive and polar components of the filler surface energy, respectively, with dimensions in mJ / m. 2 γ P For resin surface energy, and These are the dispersive and polar components of the resin surface energy, respectively. PF and W FF These are the adsorption energies between the filler and the resin, and the adsorption energies between the fillers, respectively. From formula (1), the following thermodynamic criterion can be obtained: Where, the smaller θ is, the larger cosθ is, W PF / W FF The larger the value, the better the wettability between the filler and the resin, and the easier it is for the filler to disperse.

3. The method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws according to claim 1, characterized in that, The reagglomeration energy in step S12 is calculated and expressed by formula (3): 公示(3)ΔW a =W FF +W PP -W PF (3) In the formula, ΔW a W is the driving force for reunion. FF and W PP These are the filler / filler interfacial free energy and the coating / resin interfacial free energy, respectively, W. PF Let be the free energy of the filler / resin interface. Substituting the surface energy expressions of the filler and resin into formula (3), we can obtain the following thermodynamic criterion: Wherein, ΔW a The larger the value, the more likely the filler is to agglomerate in the resin, which is not conducive to its dispersion.

4. The method for explaining the strength of organic / inorganic interfaces based on thermodynamic laws according to claim 1, characterized in that, In step S13, the filler / resin binding energy (W) PF ) and the bonding energy of the coating / resin (W) PP The difference, i.e., the molecular diffusion energy (W) s This can be expressed by formula (5): Official (5) W S =W PF -W PP Substituting the surface energy expressions for fillers and resins into formula (5), we obtain the following thermodynamic criterion: Among them, W s The larger the value, the less mobile the resin molecules are at the interface, indicating a stronger interaction between the two phases.

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