Microwave response self-healing polyurethane modified asphalt and preparation method thereof

Abstract

The invention relates to the technical field of road materials, in particular to microwave response self-healing polyurethane modified asphalt and a preparation method thereof. The asphalt is prepared from the following raw material components: a wave-absorbing polyurethane prepolymer, a chain extender for constructing a dynamic covalent bond and matrix asphalt, wherein the wave-absorbing polyurethane prepolymer is prepared from the following raw material components: a surface modified wave-absorbing agent, dehydrated polyol and isocyanate. The microwave-responsive self-healing polyurethane modified asphalt prepared by the invention can absorb microwaves and convert the microwaves into heat energy, and the arrangement and recombination of dynamic covalent bonds are accelerated, so that the self-healing performance of the asphalt in a microwave environment is greatly improved; the two ends of the wave-absorbing polyurethane prepolymer are still-NCO and can be bonded with an asphalt active group to form a three-dimensional network structure, so that the compatibility of the wave-absorbing agent and asphalt is enhanced; meanwhile, the PU material can reduce the glass transition temperature of the asphalt, so that the low-temperature performance of the asphalt is improved, and the adverse effect of the wave-absorbing agent on the low-temperature performance of the asphalt can be made up.

Description

Technical Field

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

[0002] Polyurethane-modified asphalt based on dynamic covalent bonds has significant self-healing advantages. Introducing microwave-absorbing materials into polyurethane-modified asphalt containing dynamic covalent bonds can endow the system with microwave response ability and achieve rapid repair in a microwave environment. However, there are interfacial compatibility defects between inorganic microwave-absorbing particles and the organic asphalt-polyurethane matrix. The untreated microwave-absorbing agent is prone to aggregation in the system, hindering the uniform absorption of microwave energy and heat conduction, reducing the self-healing efficiency, and affecting the storage stability of asphalt due to the tendency of phase separation.

[0003] In addition, the introduction of rigid microwave-absorbing agents will interfere with the microphase separation structure of the hard and soft segments of polyurethane, weaken the movement ability of flexible chain segments, and lead to increased low-temperature brittleness and decreased ductility of asphalt. The literature ("Study on the Properties and Microscopic Mechanism of TPU / Nano-ZnO Composite Modified Asphalt", 2024) prepared composite modified asphalt using nano-zinc oxide and polyurethane. The large specific surface area of nano-zinc oxide hinders the expansion of low-temperature cracks, and polyurethane can form a stable spatial network structure with nano-zinc oxide and matrix asphalt, improving the cohesion of modified asphalt and thus enhancing the low-temperature crack resistance performance, but does not mention the self-healing ability of asphalt; the literature ("Preparation and Performance Study of Graphene Oxide / Polyurethane Blended Modified Asphalt") prepared composite modified asphalt using graphene oxide and polyurethane. The functional groups of graphene oxide, chemical adsorption of the lamellae, etc. can all promote the dispersion of polymers in asphalt, better fuse with asphalt, and improve the dispersion of polymers in asphalt, but do not mention the self-healing ability of asphalt. Currently, there is no technology that can endow the asphalt system with microwave-responsive self-healing performance while ensuring the storage stability and low-temperature performance of the system.

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

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

[0006] The technical solution of the present invention is realized as follows: In a first aspect, the present invention provides a microwave-responsive self-healing polyurethane-modified asphalt, the raw material components of which include a microwave-absorbing polyurethane prepolymer, a chain extender for constructing dynamic covalent bonds, and matrix asphalt; wherein, the raw material components of the microwave-absorbing polyurethane prepolymer include a surface-modified microwave absorber, a dehydrated polyol, and an isocyanate.

[0007] Preferably, the preparation method of the surface-modified microwave absorber includes the following steps: S1. Add a surface modifier to a mixed solution of ethanol and water and stir evenly to obtain a mixed solution; S2. Add an inorganic microwave absorber to the mixed solution, stir at 60-80 °C for 1-2 h, and then place it in a vacuum drying oven at 60-80 °C for 6-9 h to obtain a surface-modified microwave absorber.

[0008] Preferably, the surface modifier includes one or a combination of several of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a polymer graft modifier, a surfactant, and an organic acid modifier.

[0009] Preferably, the inorganic microwave absorber includes one of carbon nanotubes, carbon fibers, activated carbon, graphite, graphene, ferrite, magnetite, ferrosilicon, and iron oxide.

[0010] More preferably, in the raw material components of the surface-modified microwave absorber, the weight ratio of the surface modifier, ethanol, water, and inorganic microwave absorber is (3-5):(50-100):(200-300):100.

[0011] More preferably, in the raw material components of the microwave-responsive self-healing polyurethane-modified asphalt, the weight ratio of the microwave-absorbing polyurethane prepolymer, the chain extender for constructing dynamic covalent bonds, and matrix asphalt is (30-50):(3-5):1000.

[0012] More preferably, in the raw material components of the microwave-absorbing polyurethane prepolymer, the weight ratio of the surface-modified microwave absorber, the dehydrated polyol, and the isocyanate is (1-2):(15-25):10.

[0013] Preferably, the dynamic covalent bonds include Diels-Alder reaction groups, disulfide bonds, imine bonds, selenide bonds, and oxime carbamate bonds.

[0014] Preferably, the polyol includes one of polyether polyols, polyester polyols, and polycarbonate polyols.

[0015] Preferably, the isocyanate group material includes isocyanates containing multiple -NCO groups; among them, the isocyanates containing multiple -NCO groups include one or a combination of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, lysine diisocyanate.

[0016] 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: S1. Under the protection of inert gas, the polyol with adsorbed water removed and the isocyanate group material are mixed and stirred at 60-80°C for 2-6 h to obtain a reaction product; S2. A surface-modified wave-absorbing agent is added to the reaction product, and stirred at 50-80°C for 1-2 h to obtain a wave-absorbing polyurethane prepolymer; S3. The matrix asphalt is heated to 120-150°C, and the wave-absorbing polyurethane prepolymer is added at a shear rate of 3000 r / min and sheared for 20 min to form a homogeneous phase; S4. A chain extender capable of constructing dynamic covalent bonds is added to the homogeneous phase, stirred at 120-150°C for 1-2 h, and kept at 90°C for 6 h to obtain the polyurethane-modified asphalt.

[0017] Compared with the prior art, the advantages of the present invention are as follows: (1) The -NCO groups in the isocyanate group material of the present invention react with the -OH on the surface of the polyol to form stable urethane bonds. The two ends of the subsequently formed wave-absorbing polyurethane prepolymer are still -NCO, and 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 between the wave-absorbing agent and the asphalt.

[0018] (2) The introduced chain extender can extend the polymer chain and introduce dynamic covalent bonds into the polyurethane, endowing the polyurethane (PU) material with room-temperature spontaneous self-healing performance, and significantly improving the self-healing ability of the asphalt at normal temperature.

[0019] (3) Through the synergistic effect of dynamic covalent bonds and graft-modified wave-absorbing agents, the modified asphalt can efficiently absorb microwaves and convert them into heat energy, promoting the recombination of dynamic covalent bonds, significantly enhancing the self-healing performance in a microwave environment, and also compensating for the adverse effects of the wave-absorbing agent on the low-temperature performance of the asphalt. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 It is a schematic structural diagram of the microwave-responsive self-healing polyurethane-modified asphalt prepared in Embodiment 1 of the present invention. Detailed implementation manners

[0022] The following will describe in detail the embodiments of the present invention, and the examples of the embodiments are shown in the drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0023] It should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0024] In this article, the terms "containing", "comprising" or "including" are open expressions, that is, including the content specified by the present invention, but not excluding other aspects.

[0025] In this article, the terms "optionally", "optional" or "option" generally mean that the subsequent events or conditions may or may not occur, and this description includes the cases where the events or conditions occur and the cases where the events or conditions do not occur.

[0026] In view of the interfacial compatibility defects between inorganic microwave-absorbing particles and the organic asphalt-polyurethane matrix. The microwave-absorbing agent without surface treatment is prone to aggregation in the system, hindering the uniform absorption of microwave energy and heat conduction, reducing the self-healing efficiency, and affecting the storage stability of asphalt due to the phase separation tendency. The present invention proposes a microwave-responsive self-healing polyurethane-modified asphalt and its preparation method, and realizes the optimization of the material through the synergistic effect of dynamic covalent bonds and microwave-absorbing materials.

[0027] First, a polyurethane flexible chain interfacial layer is constructed on the surface of the microwave absorber through surface grafting modification - the polyurethane chain segments are anchored to the surface of the microwave absorber through chemical bonds, which not only reduces its surface energy, inhibits agglomeration in asphalt and improves dispersion uniformity, but also compensates for the rigid characteristics of the inorganic microwave absorber through the toughening effect of the flexible chain, significantly improving the low-temperature crack resistance of the modified asphalt; Secondly, a microwave-absorbing polyurethane containing dynamic covalent bonds is introduced into the asphalt system to construct a dual-responsive network: the microwave absorber converts microwave energy into heat energy directionally, triggering the reversible fracture-recombination of the dynamic bonds and driving the targeted repair of the damaged area, while the microwave absorber grafted with polyurethane forms a three-dimensional continuous microwave-absorbing network through chain segment interconnection, enhancing the multiple scattering and loss efficiency of electromagnetic waves. This design synchronously solves the technical bottlenecks of poor compatibility between the microwave absorber and the asphalt matrix and impaired low-temperature performance of asphalt, while endowing asphalt with efficient self-healing ability.

[0028] The following describes clearly and completely the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1 This example provides a preparation method of a polyurethane-modified asphalt that can respond to microwave and self-heal, including the following steps: (1) Add 3 g of silane coupling agent KH-550 (purchased from Shanghai Macklin Biochemical Co., Ltd.) to a mixed solution of 50 g of absolute ethanol (volume concentration 99.5%) and 200 g of water and stir evenly. Then add 100 g of ferric oxide powder (purchased from Shanghai Macklin Biochemical Co., Ltd.). After stirring at 80 °C for 2 h, place it in a vacuum drying oven at 60 °C for 8 h to obtain surface-modified ferric oxide powder; (2) First, dehydrate 15 g of polytetrahydrofuran ether glycol (purchased from Shandong Keyuan Biochemical Co., Ltd.) under vacuum at 120 °C for 2 h to remove moisture. Then add it together with 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) to a reaction kettle and mix evenly. The whole system reacts at 80 °C under a nitrogen atmosphere for 2 h. Then, add 2 g of surface-modified ferric oxide powder and stir at 60 °C for 2 h to obtain a microwave-absorbing polyurethane prepolymer; (3) First, heat the base asphalt to 140 °C, then add 30 g of the microwave-absorbing polyurethane prepolymer to 1000 g of the base asphalt. Turn on the high-speed shearer to 3000 rpm and shear for 20 min to form a homogeneous phase. Then, add 3 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) thereto, stir at 120 °C for 2 h, and keep warm at 90 °C for 6 h to obtain the polyurethane-modified asphalt capable of microwave-responsive self-healing.

[0030] Example 2 This example provides a preparation method of a polyurethane-modified asphalt capable of microwave-responsive self-healing. Compared with Example 1, it includes the following steps: (1) Add 5 g of silane coupling agent KH-550 (purchased from Shanghai Macklin Biochemical Co., Ltd.) to a mixed solution of 100 g of anhydrous ethanol (volume concentration 99.5%) and 300 g of water and stir evenly. Then, add 100 g of graphene powder (purchased from Shanghai Macklin Biochemical Co., Ltd.). After stirring at 80 °C for 2 h, place it in a vacuum drying oven at 60 °C for 8 h to obtain the surface-modified graphene powder. (2) First, dehydrate 25 g of polytetrahydrofuran ether glycol (purchased from Shandong Keyuan Biochemical Co., Ltd.) under vacuum at 120 °C for 2 h to remove moisture. Then, add it together with 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) to the reaction kettle and mix evenly. The whole system reacts at 80 °C under a nitrogen atmosphere for 2 h. Then, add 2 g of the surface-modified graphene powder and stir at 60 °C for 2 h to obtain the microwave-absorbing polyurethane prepolymer. (3) First, heat the base asphalt to 140 °C, then add 30 g of the microwave-absorbing polyurethane prepolymer to 1000 g of the base asphalt. Turn on the high-speed shearer to 3000 rpm and shear for 20 min to form a homogeneous phase. Then, add 3 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) thereto, stir at 120 °C for 2 h, and keep warm at 90 °C for 6 h to obtain the polyurethane-modified asphalt capable of microwave-responsive self-healing.

[0031] Example 3 This example provides a preparation method of a polyurethane-modified asphalt capable of microwave-responsive self-healing. Compared with Example 1, it includes the following steps: (1) Add 5 g of silane coupling agent KH-550 (purchased from Shanghai Macklin Biochemical Co., Ltd.) to a mixed solution of 100 g of anhydrous ethanol (volume concentration 99.5%) and 300 g of water and stir evenly. Then, add 100 g of activated carbon powder (purchased from Shanghai Macklin Biochemical Co., Ltd.). After stirring at 80 °C for 2 h, place it in a vacuum drying oven at 60 °C for 8 h to obtain the surface-modified graphene powder. (2) First, 25 g of polytetrahydrofuran ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120 °C for 2 h to remove moisture, and then 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) was added to the reaction kettle. After mixing evenly, the whole system was reacted at 80 °C under a nitrogen atmosphere for 2 h. Then, 2 g of surface-modified activated carbon powder was added and stirred at 60 °C for 2 h to obtain a wave-absorbing polyurethane prepolymer.

[0032] (3) First, the matrix asphalt was heated to 140 °C, and then 30 g of the wave-absorbing polyurethane prepolymer was added to 1000 g of the matrix asphalt. The high-speed shearer was turned on to 3000 rpm and sheared for 20 min to form a homogeneous phase. Then, 3 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) was added, stirred at 120 °C for 2 h, and kept at 90 °C for 6 h to obtain the polyurethane-modified asphalt with microwave-responsive self-healing properties.

[0033] Example 4 This example provides a preparation method of polyurethane-modified asphalt with microwave-responsive self-healing properties. Compared with Example 1, it includes the following steps: (1) 3 g of silane coupling agent KH-550 (purchased from Shanghai Macklin Biochemical Co., Ltd.) was added to a mixed solution of 50 g of absolute ethanol (volume concentration 99.5%) and 200 g of water and stirred evenly. Then, 100 g of ferroferric oxide powder (purchased from Shanghai Macklin Biochemical Co., Ltd.) was added. After stirring at 80 °C for 2 h, it was placed in a vacuum drying oven at 60 °C for 8 h to obtain surface-modified ferroferric oxide powder. (2) First, 15 g of polytetrahydrofuran ether diol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was vacuum dehydrated at 120 °C for 2 h to remove moisture, and then 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) was added to the reaction kettle. After mixing evenly, the whole system was reacted at 80 °C under a nitrogen atmosphere for 2 h. Then, 2 g of surface-modified ferroferric oxide powder was added and stirred at 60 °C for 2 h to obtain a wave-absorbing polyurethane prepolymer.

[0034] (3) First, the matrix asphalt was heated to 140 °C, and then 50 g of the wave-absorbing polyurethane prepolymer was added to 1000 g of the matrix asphalt. The high-speed shearer was turned on to 3000 rpm and sheared for 20 min to form a homogeneous phase. Then, 5 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) was added, stirred at 120 °C for 2 h, and kept at 90 °C for 6 h to obtain the polyurethane-modified asphalt with microwave-responsive self-healing properties.

[0035] Example 5 This example provides a preparation method of microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 1 g of surface-modified iron oxide powder is added, and the rest is the same as in Example 1.

[0036] Example 6 This example provides a preparation method of microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 1.5 g of surface-modified iron oxide powder is added, and the rest is the same as in Example 1.

[0037] Example 7 This example provides a preparation method of microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 0.5 g of surface-modified iron oxide powder is added, and the rest is the same as in Example 1.

[0038] Example 8 This example provides a preparation method of microwave-responsive self-healing polyurethane-modified asphalt. Compared with Example 1, the difference is that 3 g of surface-modified iron oxide powder is added, and the rest is the same as in Example 1.

[0039] Comparative Example 1 This comparative example provides a preparation method of ordinary microwave-responsive asphalt, including the following steps: (1) Heat the base asphalt to 140 °C, add 3 g of iron oxide powder to 100 g of base asphalt, turn on the high-speed shearer to 3000 rpm, and shear for 2 h to form a homogeneous phase, thus obtaining ordinary microwave-responsive asphalt.

[0040] Comparative Example 2 This comparative example provides a preparation method of ordinary self-healing polyurethane asphalt, including the following steps: (1) First, vacuum dehydrate 20 g of polytetrahydrofuran ether glycol (purchased from Shandong Keyuan Biochemical Co., Ltd.) at 120 °C for 2 h to remove moisture, then add it to a reaction kettle together with 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.), and after mixing evenly, react the whole system at 80 °C under a nitrogen atmosphere for 2 h to obtain a polyurethane prepolymer.

[0041] (2) First, heat the base asphalt to 140 °C, then add 30 g of polyurethane prepolymer to 1000 g of base asphalt, turn on the high-speed shearer to 3000 rpm, shear for 20 min to form a homogeneous phase, then add 3 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) thereto, stir at 120 °C for 2 h, and keep it warm at 90 °C for 6 h to obtain ordinary self-healing polyurethane-modified asphalt.

[0042] Comparative Example 3 This comparative example provides a method for preparing microwave-responsive self-healing polyurethane asphalt. Compared with Example 1, the difference is that the inorganic wave absorber is not surface-modified, and the method includes the following steps: (1) First, 20 g of polytetrahydrofuran ether glycol (purchased from Shandong Keyuan Biochemical Co., Ltd.) was dehydrated under vacuum at 120 °C for 2 h to remove moisture, and then 10 g of diphenylmethane diisocyanate (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) was added to the reaction kettle. After mixing evenly, the whole system was reacted at 80 °C under a nitrogen atmosphere for 2 h. Then, 2 g of iron oxide powder was added and stirred at 60 °C for 2 h to obtain a wave-absorbing polyurethane prepolymer.

[0043] (2) First, the matrix asphalt was heated to 140 °C, and then 30 g of the wave-absorbing polyurethane prepolymer was added to 1000 g of the matrix asphalt. The high-speed shearer was turned on to 3000 rpm and sheared for 20 min to form a homogeneous phase. Then, 3 g of dimethylglyoxime (purchased from Shanghai Macklin Biochemical Co., Ltd.) was added, stirred at 120 °C for 2 h, and kept at 90 °C for 6 h to prepare the microwave-responsive self-healing polyurethane asphalt.

[0044] The inventor prepared asphalt mixtures from the above-mentioned asphalt in the example and the comparative example respectively, and made beam specimens of asphalt mixtures with dimensions of 100 mm × 45 mm × 50 mm. The three-point bending fracture of all beam specimens was carried out using a universal mechanical testing machine to obtain the initial fracture strength of the beams. Then, all beam specimens were irradiated with 1000 W microwave for 30 s according to the literature (Dual responsive self-healing system based on calcium alginate / Fe3O4 capsules for asphalt mixtures). Finally, the three-point bending fracture of the repaired beam specimens was carried out to obtain the fracture strength, and the strength recovery rate was calculated. The results are shown in Table 1.

[0045] Table 1

[0046] It can be seen that the strength recovery rate of the trabecular specimens prepared from the asphalt in Example 1 after microwave treatment is higher than that of the trabecular specimens prepared from the asphalt in Examples 2 and 3, and much higher than that of the trabecular specimens prepared from the asphalt in Comparative Example 3. The results show that adding a surface modifier constructs a polyurethane flexible chain interfacial layer on the surface of the wave-absorbing agent. The polyurethane segments are anchored on the surface of the wave-absorbing agent through chemical bonds. The wave-absorbing agent grafted with polyurethane forms a three-dimensional continuous wave-absorbing network through segment interconnection, which can effectively enhance the multiple scattering and loss efficiency of electromagnetic waves, thereby improving the strength recovery rate of the trabecular specimens prepared from asphalt. When the wave-absorbing agent is modified Fe₃O₄, the effect is the best. And when the dosage of the surface-modified wave-absorbing agent is 1-2 g, it has a good improvement effect on the strength recovery rate of the trabecular specimens prepared from asphalt, that is, the optimal dosage range of the surface-modified wave-absorbing agent is 1-2 g.

[0047] Also in accordance with the "Test Regulations for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20-2011), segregation experiments were carried out on the bitumens prepared in the above Examples 1 and 4 and Comparative Examples 1 and 3, and the experimental results are shown in Table 2.

[0048] Table 2

[0049] The difference in softening point of the bitumens prepared in Examples 1 and 4 is significantly lower than that of the bitumen prepared in Comparative Example 3, indicating that adding a surface modifier can improve the compatibility between the wave-absorbing agent and the bitumen, and the prepared polyurethane-modified bitumen with microwave-responsive self-healing has better storage stability.

[0050] Similarly, in accordance with the "Test Regulations for Bitumen and Bituminous Mixtures for Highway Engineering" (JTG E20-2011), the bitumens prepared in the above Examples 1 and 4 and Comparative Examples 1 and 3 were respectively subjected to a low-temperature bending beam creep test at -12 °C, -18 °C, and -24 °C, and the experimental results are shown in Table 3.

[0051] Table 3

[0052] The inventors found that the stiffness moduli of the bitumens prepared in Examples 1 and 4 at -12 °C, -18 °C, and -24 °C are lower than those of the bitumen prepared in Comparative Example 3, indicating that adding surface modification can reduce the surface energy of the wave-absorbing agent, inhibit bitumen agglomeration and improve dispersion uniformity, and also compensate for the rigid characteristics of the inorganic wave-absorbing agent through the toughening effect of the flexible chain, significantly improving the low-temperature crack resistance of the modified bitumen. Therefore, the polyurethane-modified bitumen with microwave-responsive self-healing prepared in Examples 1 and 4 has better low-temperature performance.

[0053] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A microwave-responsive self-healing polyurethane-modified asphalt, characterized in that, Its raw material components include a wave-absorbing polyurethane prepolymer, a chain extender for constructing dynamic covalent bonds, and matrix asphalt; Among them, the raw material components of the wave-absorbing polyurethane prepolymer include a surface-modified wave absorber, a dehydrated polyol, and an isocyanate.

2. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, wherein The preparation method of the surface-modified wave absorber includes the following steps: S1. Add a surface modifier to a mixed solution of ethanol and water and stir evenly to obtain a mixed solution; S2. Add an inorganic wave absorber to the mixed solution, stir and then dry under vacuum to obtain a surface-modified wave absorber.

3. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 2, characterized in that, The surface modifier includes one or a combination of several of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a polymer graft modifier, a surfactant, and an organic acid modifier.

4. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 2, wherein The inorganic wave absorber includes one of carbon nanotubes, carbon fibers, activated carbon, graphite, graphene, ferrite, iron tetroxide, ferrosilicon, and iron oxide.

5. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 2, wherein In the raw material components of the surface-modified wave absorber, the weight ratio of the surface modifier, ethanol, water, and inorganic wave absorber is (3-5):(50-100):(200-300):

100.

6. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, wherein In the raw material components, the weight ratio of the wave-absorbing polyurethane prepolymer, the chain extender for constructing dynamic covalent bonds, and matrix asphalt is (30-50):(3-5):1000.

7. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, characterized in that, In the raw material components of the wave-absorbing polyurethane prepolymer, the weight ratio of the surface-modified wave absorber, the dehydrated polyol, and the isocyanate is (1-2):(15-25):

10.

8. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, wherein The dynamic covalent bonds include Diels-Alder reaction groups, disulfide bonds, imine bonds, selenide bonds, and oxime carbamate bonds.

9. The microwave-responsive self-healing polyurethane-modified asphalt according to claim 1, wherein The isocyanate-based material includes an isocyanate containing multiple -NCO groups; Among them, the isocyanate containing multiple -NCO groups includes one or a combination of several of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

10. A method for preparing a microwave-responsive self-healing polyurethane-modified asphalt as described in any one of claims 1-9, characterized in that, It includes the following steps: S1. Under the protection of an inert gas, mix and stir the dehydrated polyol and the isocyanate-based material to obtain a reaction product; S2. Add the surface-modified wave absorber to the reaction product and stir to obtain a wave-absorbing polyurethane prepolymer; S3. Heat the matrix asphalt, add the wave-absorbing polyurethane prepolymer to the matrix asphalt, and shear to form a homogeneous phase; S4. Add a chain extender capable of constructing dynamic covalent bonds to the homogeneous phase, stir and keep warm to obtain the polyurethane-modified asphalt.

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