A kind of polyurethane modified asphalt capable of microwave response and self-healing and preparation method thereof

Abstract

The present invention relates to the technical field of road materials, and more particularly to a microwave-responsive, self-healing polyurethane-modified asphalt and a preparation method thereof. The asphalt raw material components include a microwave-absorbing polyurethane prepolymer, a chain extender for constructing dynamic covalent bonds, and a base asphalt. The raw material components of the microwave-absorbing polyurethane prepolymer include a surface-modified absorber, a dehydrated polyol, and an isocyanate. The microwave-responsive, self-healing polyurethane-modified asphalt prepared by the present invention can absorb microwaves and convert them into heat energy, accelerating the arrangement and reorganization of dynamic covalent bonds, thereby significantly improving its self-healing performance in a microwave environment. The microwave-absorbing polyurethane prepolymer still has NCO at both ends, which can bond with active groups in asphalt to form a three-dimensional network structure, enhancing the compatibility of the absorber with the asphalt. Furthermore, the PU material can lower the glass transition temperature of the asphalt, thereby improving the low-temperature performance of the asphalt and compensating for the adverse effects of the absorber on the low-temperature performance of the asphalt.

Description

Technical Field

[0001] The present invention belongs to the technical field of road materials, and in particular relates to a polyurethane-modified asphalt capable of microwave response and self-healing and a preparation method thereof. Background Art

[0002] Polyurethane-modified asphalt based on dynamic covalent bonds has significant self-healing advantages. Introducing absorbing materials into polyurethane-modified asphalt containing dynamic covalent bonds can impart microwave responsiveness to the system, enabling rapid repair in a microwave environment. However, interfacial compatibility issues exist between inorganic absorbing particles and the organic asphalt-polyurethane matrix. Absorbers without surface treatment tend to aggregate within the system, hindering uniform absorption of microwave energy and heat conduction, reducing self-healing efficiency, and affecting the storage stability of the asphalt due to phase separation tendencies.

[0003] Furthermore, the introduction of rigid absorbers disrupts the microphase separation structure of the soft and hard segments of polyurethane, weakening the mobility of the flexible segments and leading to increased low-temperature brittleness and decreased ductility in asphalt. The paper (Research on the Performance and Microscopic Mechanism of TPU / Nano-ZnO Composite Modified Asphalt, 2024) uses nano-zinc oxide and polyurethane to prepare composite modified asphalt. Nano-zinc oxide's large surface area hinders low-temperature crack propagation. Polyurethane, nano-zinc oxide, and matrix asphalt form a stable spatial network structure, enhancing the cohesion of the modified asphalt and thus improving its low-temperature crack resistance. However, the paper does not mention the asphalt's self-healing ability. The paper (Research on the Preparation and Performance of Graphene Oxide / Polyurethane Composite Modified Asphalt) uses graphene oxide and polyurethane to prepare composite modified asphalt. The functional groups and chemical adsorption of graphene oxide flakes promote the dispersion of polymers in asphalt, improving their integration with the asphalt and enhancing their dispersion. However, the paper does not mention the asphalt's self-healing ability. Currently, no technology exists to impart microwave-responsive self-healing properties to asphalt systems while ensuring storage stability and low-temperature performance.

[0004] Therefore, there is an urgent need to develop a microwave-responsive self-healing polyurethane modified asphalt to solve the technical bottlenecks of poor compatibility between the absorber and the asphalt matrix and impaired low-temperature performance of asphalt. Summary of the Invention

[0005] To achieve one of the above purposes, the present invention proposes a microwave-responsive self-healing polyurethane-modified asphalt and a preparation method thereof, which optimizes the material through the synergistic effect of dynamic covalent bonds and absorbing materials.

[0006] The technical solution of the present invention is achieved as follows:

[0007] In a first aspect, the present invention provides a microwave-responsive self-healing polyurethane-modified asphalt, the raw material components of which include an absorbing polyurethane prepolymer, a chain extender for constructing dynamic covalent bonds, and a matrix asphalt; wherein the raw material components of the absorbing polyurethane prepolymer include a surface-modified absorber, a dehydrated polyol, and an isocyanate.

[0008] Preferably, the preparation method of the surface-modified absorber comprises the following steps:

[0009] S1. Adding a surface modifier to a mixed solution of ethanol and water and stirring the mixture to obtain a mixed solution;

[0010] S2. Adding an inorganic absorber to the mixed solution, stirring at 60-80° C. for 1-2 hours, and then placing in a vacuum drying oven at 60-80° C. for 6-9 hours to obtain a surface-modified absorber.

[0011] Preferably, the surface modifier includes one or a combination of silane coupling agents, titanate coupling agents, aluminate coupling agents, polymer grafting modifiers, surfactants and organic acid modifiers.

[0012] Preferably, the inorganic absorber includes one of carbon nanotubes, carbon fibers, activated carbon, graphite, graphene, ferrite, ferrosilicon, ferrous oxide, and iron oxide.

[0013] Further preferably, in the raw material components of the surface-modified absorber, the weight ratio of the surface modifier, ethanol, water and inorganic absorber is (3-5): (50-100): (200-300): 100.

[0014] Further preferably, in the raw material components of the microwave-responsive self-healing polyurethane modified asphalt, the weight ratio of the absorbing polyurethane prepolymer, the chain extender for constructing dynamic covalent bonds and the matrix asphalt is (30-50): (3-5): 1000.

[0015] Further preferably, in the raw material components of the absorbing polyurethane prepolymer, the weight ratio of the surface modified absorber, the dehydrated polyol and the isocyanate is (1-2): (15-25):10.

[0016] Preferably, the dynamic covalent bond includes a Diels-Alder reactive group, a disulfide bond, an imine bond, a selenite bond and an oxime urethane bond.

[0017] Preferably, the polyol comprises one of polyether polyol, polyester polyol and polycarbonate polyol.

[0018] Preferably, the isocyanate-based material includes an isocyanate containing multiple -NCO groups; wherein the isocyanate containing multiple -NCO groups includes one or a combination of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

[0019] In a second aspect, the present invention relates to a method for preparing the microwave-responsive self-healing polyurethane-modified asphalt, comprising the following steps:

[0020] S1. Under inert gas protection, the polyol from which adsorbed water has been removed and the isocyanate-based material are mixed and stirred at 60-80° C. for 2-6 hours to obtain a reaction product;

[0021] S2. Adding a surface-modified absorber to the reaction product, stirring at 50-80° C. for 1-2 hours to obtain an absorbing polyurethane prepolymer;

[0022] S3, heating the matrix asphalt to 120-150° C., adding the absorbing polyurethane prepolymer at a shear rate of 3000 r / min, and shearing for 20 minutes to form a uniform phase;

[0023] S4. Adding a chain extender capable of constructing dynamic covalent bonds into the homogeneous phase, stirring at 120-150° C. for 1-2 hours, and keeping warm at 90° C. for 6 hours to obtain the polyurethane modified asphalt.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] (1) The -NCO groups in the isocyanate-based material of the present invention react with the -OH groups on the surface of the polyol to form a stable urethane bond. The two ends of the subsequently generated absorbing polyurethane prepolymer still have -NCO groups. The -NCO groups can form chemical bonds with the active groups in the asphalt to form a stable three-dimensional network structure, thereby improving the compatibility of the absorber with the asphalt.

[0026] (2) The introduced chain extender can extend the polymer chain and introduce dynamic covalent bonds into the polyurethane, giving the polyurethane (PU) material spontaneous self-healing properties at room temperature, which can significantly improve the self-healing ability of asphalt at room temperature.

[0027] (3) Through the synergistic effect of dynamic covalent bonds and grafted modified absorbers, the modified asphalt can efficiently absorb microwaves and convert them into thermal energy, promote the reorganization of dynamic covalent bonds, significantly improve the self-healing performance in a microwave environment, and compensate for the adverse effects of the absorber on the low-temperature performance of asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic structural diagram of the microwave-responsive self-healing polyurethane-modified asphalt prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0031] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. Furthermore, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0032] In this document, the terms “contain”, “include” or “include” are open expressions, that is, they include the contents specified in the present invention but do not exclude other contents.

[0033] As used herein, the terms "optionally," "optional," or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0034] Given the interfacial compatibility issues between inorganic absorbing particles and the organic asphalt-polyurethane matrix, untreated absorbers tend to aggregate within the system, hindering uniform microwave energy absorption and heat conduction, reducing self-healing efficiency, and affecting the storage stability of the asphalt due to phase separation. This invention proposes a microwave-responsive, self-healing polyurethane-modified asphalt and its preparation method, achieving material optimization through the synergistic effect of dynamic covalent bonds and the absorbing material.

[0035] First, a surface-grafted polyurethane flexible chain interface layer is constructed on the absorber surface. Polyurethane segments are chemically anchored to the absorber surface, reducing its surface energy, inhibiting aggregation in the asphalt and improving dispersion uniformity. The toughening effect of the flexible chains also compensates for the rigidity of the inorganic absorber, significantly improving the low-temperature crack resistance of the modified asphalt. Second, an absorbing polyurethane containing dynamic covalent bonds is introduced into the asphalt system to create a dual-responsive network. The absorber converts microwave energy into heat, triggering the reversible breakage and recombination of dynamic bonds and driving targeted repair of damaged areas. Meanwhile, the grafted polyurethane absorber forms a three-dimensional continuous absorbing network through chain interconnection, enhancing electromagnetic wave multiple scattering and loss efficiency. This design simultaneously addresses the technical bottlenecks of poor compatibility between the absorber and the asphalt matrix and impaired low-temperature performance of asphalt, while also endowing the asphalt with efficient self-healing capabilities.

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt, comprising the following steps:

[0039] (1) 3 g of silane coupling agent KH-550 (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.) was added to a mixed solution of 50 g of anhydrous ethanol (volume concentration 99.5%) and 200 g of water and stirred evenly. Then, 100 g of ferroferric oxide powder (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.) was added. After stirring at 80 ° C for 2 h, the mixture was placed in a vacuum drying oven at 60 ° C for 8 h to obtain surface-modified ferroferric oxide powder.

[0040] (2) First, 15g of polytetramethylene ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120°C for 2h to remove moisture, and then added to the reactor together with 10g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80°C under nitrogen atmosphere for 2h. Then, 2g of surface-modified ferroferric oxide powder was added and stirred at 60°C for 2h to obtain the absorbing polyurethane prepolymer.

[0041] (3) First, heat the base asphalt to 140°C, then add 30g of microwave-absorbing polyurethane prepolymer to 1000g of base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 3g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain microwave-responsive self-healing polyurethane modified asphalt.

[0042] Example 2

[0043] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt, which, compared with Example 1, comprises the following steps:

[0044] (1) 5 g of silane coupling agent KH-550 (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was added to a mixed solution of 100 g of anhydrous ethanol (volume concentration 99.5%) and 300 g of water and stirred evenly. Then, 100 g of graphene powder (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was added. After stirring at 80°C for 2 h, the mixture was placed in a vacuum drying oven at 60°C for 8 h to obtain surface-modified graphene powder.

[0045] (2) First, 25g of polytetramethylene ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120°C for 2h to remove moisture, and then added to the reactor together with 10g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80°C under nitrogen atmosphere for 2h. Then, 2g of surface-modified graphene powder was added and stirred at 60°C for 2h to obtain the absorbing polyurethane prepolymer.

[0046] (3) First, heat the base asphalt to 140°C, then add 30g of microwave-absorbing polyurethane prepolymer to 1000g of base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 3g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain microwave-responsive self-healing polyurethane modified asphalt.

[0047] Example 3

[0048] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt, which, compared with Example 1, comprises the following steps:

[0049] (1) 5 g of silane coupling agent KH-550 (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was added to a mixed solution of 100 g of anhydrous ethanol (volume concentration 99.5%) and 300 g of water and stirred evenly. Then, 100 g of activated carbon powder (purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) was added. After stirring at 80°C for 2 h, the mixture was placed in a vacuum drying oven at 60°C for 8 h to obtain surface-modified graphene powder.

[0050] (2) First, 25g of polytetramethylene ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120°C for 2h to remove moisture, and then added to the reactor together with 10g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80°C under nitrogen atmosphere for 2h. Then, 2g of surface-modified activated carbon powder was added and stirred at 60°C for 2h to obtain the absorbing polyurethane prepolymer.

[0051] (3) First, heat the base asphalt to 140°C, then add 30g of microwave-absorbing polyurethane prepolymer to 1000g of base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 3g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain microwave-responsive self-healing polyurethane modified asphalt.

[0052] Example 4

[0053] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt, which, compared with Example 1, comprises the following steps:

[0054] (1) 3 g of silane coupling agent KH-550 (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.) was added to a mixed solution of 50 g of anhydrous ethanol (volume concentration 99.5%) and 200 g of water and stirred evenly. Then, 100 g of ferroferric oxide powder (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.) was added. After stirring at 80 ° C for 2 h, the mixture was placed in a vacuum drying oven at 60 ° C for 8 h to obtain surface-modified ferroferric oxide powder.

[0055] (2) First, 15g of polytetramethylene ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120°C for 2h to remove moisture, and then added to the reactor together with 10g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80°C under nitrogen atmosphere for 2h. Then, 2g of surface-modified ferroferric oxide powder was added and stirred at 60°C for 2h to obtain the absorbing polyurethane prepolymer.

[0056] (3) First, heat the base asphalt to 140°C, then add 50g of the microwave-absorbing polyurethane prepolymer to 1000g of the base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 5g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain a microwave-responsive self-healing polyurethane modified asphalt.

[0057] Example 5

[0058] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 1 g of surface-modified ferrosoferric oxide powder is added, and the rest is the same as Example 1.

[0059] Example 6

[0060] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 1.5 g of surface-modified ferrosoferric oxide powder is added, and the rest is the same as Example 1.

[0061] Example 7

[0062] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 0.5 g of surface-modified ferrosoferric oxide powder is added, and the rest is the same as Example 1.

[0063] Example 8

[0064] This embodiment provides a method for preparing microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 3g of surface-modified ferrosoferric oxide powder is added, and the rest is the same as Example 1.

[0065] Comparative Example 1

[0066] This comparative example provides a method for preparing a common microwave-responsive asphalt, comprising the following steps:

[0067] (1) Heat the matrix asphalt to 140°C, take 3g of ferroferric oxide powder and add it to 100g of matrix asphalt, turn on the high-speed shear instrument to 3000rpm, and shear for 2h to form a uniform phase, thus obtaining ordinary microwave-responsive asphalt.

[0068] Comparative Example 2

[0069] This comparative example provides a method for preparing a common self-healing polyurethane asphalt, comprising the following steps:

[0070] (1) First, 20 g of polytetramethylene ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120 ° C for 2 h to remove moisture, and then added to the reactor together with 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80 ° C under nitrogen atmosphere for 2 h to obtain a polyurethane prepolymer.

[0071] (2) First, heat the base asphalt to 140°C, then add 30g of polyurethane prepolymer to 1000g of base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 3g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain ordinary self-healing polyurethane modified asphalt.

[0072] Comparative Example 3

[0073] This comparative example provides a method for preparing microwave-responsive self-healing polyurethane asphalt, which is different from Example 1 in that the inorganic absorber is not surface-modified, and comprises the following steps:

[0074] (1) First, 20g of polytetrahydrofuran ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120℃ for 2h to remove moisture, and then added to the reactor together with 10g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and mixed evenly. The whole system was reacted at 80℃ under nitrogen atmosphere for 2h. Then, 2g of ferrosoferric oxide powder was added and stirred at 60℃ for 2h to obtain the absorbing polyurethane prepolymer.

[0075] (2) First, heat the base asphalt to 140°C, then add 30g of absorbing polyurethane prepolymer to 1000g of base asphalt, turn on the high-speed shear instrument to 3000rpm, shear for 20min to form a uniform phase, then add 3g of diacetyl oxime (purchased from Shanghai MacLean Biochemical Technology Co., Ltd.), stir at 120°C for 2h, and keep warm at 90°C for 6h to obtain microwave-responsive self-healing polyurethane asphalt.

[0076] The inventors prepared asphalt mixtures using the asphalts of the above examples and comparative examples. Asphalt mixture beam specimens measuring 100 mm × 45 mm × 50 mm were then fabricated. All beam specimens were subjected to three-point bending fracture tests using a universal mechanical testing machine to determine their initial fracture strength. All beam specimens were then subjected to 1000 W microwave irradiation for 30 seconds according to the literature (Dual responsive self-healing system based on calcium alginate / Fe₃O₄ capsules for asphalt mixtures). Finally, the healed beam specimens were subjected to three-point bending fracture tests to determine their fracture strengths, and the strength recovery rates were calculated. The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] It can be seen that the strength recovery rate of the beam specimens prepared from the asphalt in Example 1 after microwave treatment is higher than that of the beams prepared from the asphalt in Examples 2 and 3, and far higher than that of the beam prepared from the asphalt in Comparative Example 3. The results indicate that the addition of a surface modifier constructs a flexible polyurethane chain interface layer on the absorber surface. The polyurethane segments are chemically anchored to the absorber surface, and the polyurethane-grafted absorber forms a three-dimensional continuous absorbing network through segment interconnection. This effectively enhances electromagnetic wave multiple scattering and loss efficiency, thereby improving the strength recovery rate of the asphalt-prepared beams. The best effect was achieved when the absorber was modified ferrosoferric oxide, and a dosage of 1-2g of the surface-modified absorber significantly improved the strength recovery rate of the asphalt-prepared beams. The optimal dosage of the surface-modified absorber is 1-2g.

[0080] In accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the asphalt prepared in Examples 1 and 4 and Comparative Examples 1 and 3 was subjected to a segregation test. The experimental results are shown in Table 2.

[0081] Table 2

[0082]

[0083] The softening point difference of the asphalt prepared in Examples 1 and 4 is significantly lower than that of the asphalt prepared in Comparative Example 3, indicating that the addition of a surface modifier can improve the compatibility of the absorber with the asphalt, and the obtained microwave-responsive self-healing polyurethane-modified asphalt has better storage stability.

[0084] Similarly, according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), the asphalts prepared in Examples 1 and 4 and Comparative Examples 1 and 3 were subjected to low-temperature bending beam creep tests at -12°C, -18°C, and -24°C, respectively. The test results are shown in Table 3.

[0085] Table 3

[0086]

[0087] The inventors found that the stiffness modulus of the asphalt prepared in Examples 1 and 4 at -12°C, -18°C, and -24°C was lower than that of the asphalt prepared in Comparative Example 3, indicating that the addition of surface modification can reduce the surface energy of the absorber, inhibit asphalt agglomeration, and improve dispersion uniformity. The toughening effect of the flexible chain also compensates for the rigidity of the inorganic absorber, significantly improving the low-temperature crack resistance of the modified asphalt. Therefore, the microwave-responsive and self-healing polyurethane modified asphalt prepared in Examples 1 and 4 has better low-temperature performance.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing microwave-responsive self-healing polyurethane-modified asphalt, characterized in that: The following steps are involved: S1. Under inert gas protection, the polyol from which adsorbed water has been removed and the isocyanate-based material are mixed and stirred to obtain a reaction product; S2, adding a surface-modified absorber to the reaction product and stirring to obtain an absorbing polyurethane prepolymer; the absorbing polyurethane prepolymer has -NCO at both ends; S3, heating the matrix asphalt, adding the wave-absorbing polyurethane prepolymer to the matrix asphalt, and shearing to form a uniform phase; S4, adding a chain extender capable of constructing dynamic covalent bonds to the homogeneous phase, stirring and heat-insulating to obtain the polyurethane-modified asphalt; in, The isocyanate-based material in step S1 includes an isocyanate containing multiple -NCO groups; The preparation method of the surface-modified absorber in step S2 comprises: S2-1, adding a surface modifier to a mixed solution of ethanol and water and stirring uniformly to obtain a mixed solution; S2-2, adding an inorganic absorber to the mixed solution, stirring and then vacuum drying to obtain a surface-modified absorber; The surface modifier in step S2-1 includes one or a combination of silane coupling agents, titanate coupling agents, and aluminate coupling agents; The inorganic absorber in step S2-2 includes one of carbon nanotubes, carbon fibers, activated carbon, graphite, graphene, ferrite, ferrosilicon, ferric oxide, and iron oxide.

2. The method for preparing microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that: In the steps S2-1 to S2-2, the weight ratio of the surface modifier, ethanol, water and inorganic absorber is (3-5): (50-100): (200-300):

100.

3. The method for preparing microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that: In the steps S3-S4, the weight ratio of the wave-absorbing polyurethane prepolymer, the chain extender for constructing dynamic covalent bonds, and the matrix asphalt is (30-50): (3-5): 1000.

4. The method for preparing microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that: In the steps S1 to S2, the weight ratio of the surface-modified absorber, the polyol from which adsorbed water is removed, and the isocyanate-based material is (1-2): (15-25):

10.

5. The method for preparing microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that: The dynamic covalent bonds in step S4 include Diels-Alder reactive groups, disulfide bonds, imine bonds, selenium bonds and oxime urethane bonds.

6. The method for preparing microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that: The isocyanate containing multiple -NCO groups includes one or a combination of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

7. A microwave-responsive self-healing polyurethane-modified asphalt obtained by the preparation method according to any one of claims 1 to 6.

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