Low-temperature-resistant high-elastic rubber powder for asphalt and preparation method thereof

Abstract

This invention discloses a low-temperature resistant high-elasticity rubber powder for asphalt and its preparation method, belonging to the technical field of rubber powder. Polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide, and sodium hypochlorite react to obtain carboxyl-terminated polyethylene glycol; the carboxyl-terminated polyethylene glycol and α-cyclodextrin are mixed and then reacted with adamantane, Carter's condensing agent, and N,N-diisopropylethylamine to obtain cyclodextrin-based polyrotaxane; the cyclodextrin-based polyrotaxane, sodium hydroxide, and 2,3-epoxypropyltrimethylammonium chloride react to obtain cationic cyclodextrin polyrotaxane; the cationic cyclodextrin polyrotaxane, lipoic acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine react to obtain disulfide-bonded polyrotaxane; the disulfide-bonded polyrotaxane is mixed and stirred with anhydrous ethanol and deionized water to obtain a modified polyrotaxane dispersion; waste rubber powder and the modified polyrotaxane dispersion are mixed and stirred to obtain high-elasticity rubber powder for asphalt.

Description

Technical Field

[0001] This invention relates to the field of rubber powder technology, specifically to a low-temperature resistant high-elasticity rubber powder for asphalt and its preparation method. Background Technology

[0002] As my country's transportation infrastructure development extends to the frigid and high-altitude regions of the north, the low-temperature crack resistance of asphalt pavements has become a core indicator determining road service life and driving safety. Waste tire rubber powder, as a green and environmentally friendly asphalt modifier, can improve asphalt pavement performance, reduce noise, and realize solid waste resource utilization, showing broad application prospects. However, traditional rubber powder has fatal flaws: its glass transition temperature is high, and at extreme low temperatures, the molecular chain segments completely freeze, losing their elastic deformation ability and failing to dissipate the internal stress of asphalt shrinkage, easily leading to pavement embrittlement and cracking; furthermore, its surface is an inert cross-linked network, which can only physically blend with asphalt, resulting in extremely low interfacial bonding strength. Under long-term load and temperature cycling, phase separation easily occurs, leading to pavement peeling and loosening.

[0003] Invention patent CN103539898B discloses a method for preparing easily emulsifiable modified asphalt powdered styrene-butadiene rubber, but it has many shortcomings. This technology relies on petrochemical raw materials such as butadiene and styrene, fails to realize the resource utilization of waste tire solid waste, and requires a three-step high-temperature and high-pressure reaction, making the process complex, energy-intensive, and costly. It relies solely on ester grafting and rubber oil filling for plasticization; the molecular chains are easily frozen at low temperatures, lacking a dynamic energy dissipation mechanism, resulting in weak resistance to low-temperature cracking. Furthermore, the blending with asphalt is merely physical; the rubber oil easily migrates and precipitates, leading to phase separation and poor long-term stability. It is only suitable for conventional road surfaces in ordinary areas and cannot meet the extreme low-temperature crack resistance requirements of frigid and high-altitude regions.

[0004] Existing modification technologies have failed to fundamentally solve the above problems and have many drawbacks. High-temperature desulfurization modification can improve the flowability of rubber powder, but it will severely damage the main chain of rubber molecules, significantly reduce tensile strength, and at the same time generate toxic gases and consume a lot of energy; SBS blending modification is widely used, but it has poor compatibility with rubber powder, is still prone to embrittlement at low temperatures, and has high cost and poor storage stability; maleic anhydride grafting modification has extremely low grafting efficiency, easily leads to rubber degradation, and the raw materials are toxic; although nanofiller modification can improve strength, it is prone to agglomeration and has a very poor toughening effect at low temperatures.

[0005] Therefore, developing novel high-elasticity rubber powders that combine excellent low-temperature elasticity with good interfacial compatibility is an important problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the problems in the prior art, this invention provides a low-temperature resistant high-elasticity rubber powder for asphalt and its preparation method. Specifically, the technical solution of this invention includes the following steps: A method for preparing low-temperature resistant high-elasticity rubber powder for asphalt, the method comprising the following steps: Polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide and sodium hypochlorite solution were mixed and stirred to obtain carboxyl-terminated polyethylene glycol; Carboxyl-terminated polyethylene glycol and α-cyclodextrin were mixed and shaken, and then freeze-dried to obtain a freeze-dried solid. The freeze-dried solid, adamantane, carter's condensing agent and N,N-diisopropylethylamine were mixed and stirred to obtain cyclodextrin-based polyrotaxane. A cationic cyclodextrin polyrotaxane was obtained by mixing and stirring a cyclodextrin-based polyrotaxane, sodium hydroxide, and an aqueous solution of 2,3-epoxypropyltrimethylammonium chloride. A cationic cyclodextrin polyrotaxane, thioctic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine were mixed and stirred to obtain a disulfide-bonded polyrotaxane; A modified polyrotaxane dispersion was obtained by placing disulfide-bonded polyrotaxane in anhydrous ethanol, adding deionized water dropwise, and then mixing and stirring. High-elasticity rubber powder for asphalt is prepared by mixing and stirring waste rubber powder and modified polyrotaxane dispersion.

[0007] Furthermore, the molecular weight of the polyethylene glycol is 2000.

[0008] Furthermore, the concentration of the sodium hypochlorite solution is 10 wt%.

[0009] Further, the weight ratio of the polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide, and sodium hypochlorite solution is 9~10:0.15~0.25:0.8~1.5:15~25.

[0010] Furthermore, the conditions for the reaction of polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide and sodium hypochlorite solution include a reaction temperature of 24-26°C, a reaction time of 20-30 min and a reaction pH of 10-11.

[0011] Furthermore, the conditions for mixing and oscillating the terminal carboxyl polyethylene glycol and α-cyclodextrin include a temperature of 24-26°C, a time of 10-20 min, and a rotation speed of 2500 r / min.

[0012] Furthermore, the conditions for the mixed and stirred reaction of the freeze-dried solid, adamantane, carter's condensing agent, and N,N-diisopropylethylamine include a reaction temperature of 3-5°C and a reaction time of 12-24 h.

[0013] Further, the weight ratio of the terminal carboxyl polyethylene glycol, α-cyclodextrin, adamantane, Carter's condensing agent, and N,N-diisopropylethylamine is 1.5~1.7:18~22:6.2~6.6:1.5~1.9:0.4~0.6; a cyclodextrin-based polyrotaxane with a stable mechanical interlocking structure is prepared, providing a basic framework with sliding ring energy dissipation function for subsequent modification; α-cyclodextrin molecules penetrate the polyethylene glycol axis to form a quasi-polyrotaxane, and then through an amidation reaction, the adamantane end-capping agent is attached to the carboxyl groups at both ends of the polyethylene glycol. The large volume steric hindrance of the adamantane prevents the α-cyclodextrin from slipping off the polyethylene glycol axis, forming a stable mechanical interlocking structure.

[0014] Furthermore, the concentration of the aqueous solution of 2,3-epoxypropyltrimethylammonium chloride is 50 wt%.

[0015] Furthermore, the weight ratio of the cyclodextrin-based polyrotaxane, sodium hydroxide, and the aqueous solution of 2,3-epoxypropyltrimethylammonium chloride is 10:0.4~0.6:12~18.

[0016] Furthermore, the reaction conditions for the cyclodextrin-based polyrotaxane, sodium hydroxide, and 2,3-epoxypropyltrimethylammonium chloride aqueous solution include a reaction temperature of 55-65°C and a reaction time of 10-14 h; cationic modification is performed to solve the problem of poor solubility in organic solvents and asphalt, while introducing ionic groups compatible with the acidic groups of asphalt; under alkaline conditions, the epoxy groups in the 2,3-epoxypropyltrimethylammonium chloride molecule undergo a nucleophilic ring-opening reaction with the hydroxyl groups on the cyclodextrin unit, attaching the quaternary ammonium cationic groups to the cyclodextrin backbone.

[0017] Furthermore, the weight ratio of the cationic cyclodextrin polyrotaxane, thioctic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine is 10:5~7:1.4~1.8:1.5~2.5.

[0018] Furthermore, the conditions for the mixed and stirred reaction of the cationic cyclodextrin polyrotaxane, thioctic acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine include a reaction temperature of 20-30°C and a reaction time of 20-28 h; the thioctic acid molecule with dynamic disulfide bonds is covalently grafted onto the cationic cyclodextrin polyrotaxane, introducing dynamic reversible energy dissipation sites and flexible alkyl chains, thereby enhancing compatibility with rubber powder.

[0019] Furthermore, the weight ratio of the disulfide-bonded polyrotaxane, anhydrous ethanol, and deionized water is 10:100:250~350.

[0020] Furthermore, the conditions for mixing and stirring the disulfide-bonded polyrotaxane in anhydrous ethanol with deionized water include: stirring the disulfide-bonded polyrotaxane in anhydrous ethanol at 20-25°C for 1.5-2.5 hours, then adding deionized water dropwise at a rate of 0.4-0.6 mL / min while stirring, and continuing to stir for 3-5 hours after the addition is complete; utilizing the amphiphilic balance of the disulfide-bonded polyrotaxane, linear molecules are induced to self-assemble into a helical coiled fiber structure, constructing a spring-like toughening unit, further improving the material's low-temperature elasticity and energy dissipation capacity.

[0021] Furthermore, the concentration of the modified polyrotaxane dispersion is 18~22 mg / mL.

[0022] Furthermore, the weight ratio of the waste rubber powder to the modified polyrotaxane dispersion is 100:20~30.

[0023] Furthermore, the mixing and stirring conditions for the waste rubber powder and modified polyrotaxane dispersion include mixing and stirring at 110~130℃ for 10~20 min, and then heating to 180~200℃ and stirring for 2~4 h.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention uses cyclodextrin-based polyrotaxane as the core toughening unit to solve the problem that traditional toughening agents lose their toughening ability when the molecular chain freezes at low temperatures; it solves the bottleneck of poor solubility and lack of reactivity caused by excessively strong intermolecular hydrogen bonds through cationization modification, introduces dynamic disulfide bonds by grafting lipoic acid, and then induces the self-assembly of linear graft products to form helical coiled fibers, realizing multi-level toughening from molecular sliding to structural stretching; finally, it adopts high-temperature grafting combined with rapid cooling process to efficiently realize covalent bonding between the modifier and rubber powder, while avoiding the breakage of the rubber molecular main chain and the high-temperature unwinding of the helical structure.

[0025] (2) The sliding ring effect of this invention uniformly disperses stress and avoids the initiation of local cracks. The spiral structure absorbs a large amount of deformation energy through unwinding. The dynamic disulfide bond reversibly breaks to dissipate energy and repair microcracks. The three promote each other and greatly improve the low-temperature toughness and crack resistance of the rubber powder. The covalent bonding between the modified polyrotaxane and the rubber powder, the ionic bonding with the asphalt, and the synergistic effect of similar solubility strengthen the interfacial bonding, solving the problem of easy phase separation in traditional rubber asphalt. The high-elasticity rubber powder can maintain excellent elasticity in extremely low temperature environments. The low-temperature crack resistance, high-temperature stability, fatigue resistance, and water stability of the prepared asphalt mixture are comprehensively improved. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available or can be prepared by known methods.

[0028] Example 1 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Nine parts by weight of polyethylene glycol (Mn2000) were dispersed in 100 parts by weight of deionized water. After stirring and mixing at 200 r / min for 10 min, 0.15 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxy radical, 0.8 parts by weight of sodium bromide, and 15 parts by weight of 10 wt% sodium hypochlorite solution were added. The pH was adjusted to 10, and the mixture was stirred and reacted at 24 °C for 20 min. After the reaction was completed, 200 parts by weight of anhydrous ethanol was added to quench the reaction. The pH was then adjusted to 1 with 1 mol / L hydrochloric acid solution to obtain a mixture. The mixture was extracted three times with dichloromethane. The dichloromethane extracts were combined and concentrated under reduced pressure to obtain a concentrate. The concentrate was added dropwise to cold diethyl ether, allowed to stand for 30 min, and then filtered under reduced pressure to collect the precipitate. The precipitate was dried under vacuum at 40 °C for 12 h to obtain carboxyl-terminated polyethylene glycol. 1.5 parts by weight of carboxyl-terminated polyethylene glycol and 18 parts by weight of α-cyclodextrin were dispersed in 50 parts by weight of deionized water and oscillated at 2500 r / min for 10 min using a turbine mixer at 24 °C to obtain an intermediate. The intermediate was freeze-dried at -50 °C for 48 h to obtain a lyophilized solid. The above lyophilized solid, 6.2 parts by weight of adamantaneamine, 1.5 parts by weight of Caterpillar condensing agent, and 0.4 parts by weight of N,N-diisopropylethylamine were dispersed in 50 parts by weight of anhydrous N,N-dimethylformamide and subjected to nitrogen treatment. The reaction was carried out at 3°C ​​and stirred at 200 r / min for 14 h under a protective atmosphere. After the reaction was completed, the filter cake was collected by vacuum filtration. The filter cake was washed three times with methanol and then dried under vacuum to obtain the crude product. The crude product was dissolved in 100 parts by weight of dimethyl sulfoxide and slowly added dropwise to 1000 parts by weight of boiling deionized water. After stirring and cooling, the precipitate was collected by centrifugation at 10000 r / min for 10 min. The dimethyl sulfoxide dissolution-boiling water precipitation-centrifugation steps were repeated twice. Finally, the precipitate was freeze-dried to obtain cyclodextrin-based polyrotaxane. Ten parts by weight of cyclodextrin-based polyrotaxane were dispersed in 50 parts by weight of dimethyl sulfoxide. The dispersion was stirred at 300 r / min for 1.5 h under a nitrogen atmosphere to obtain a dispersion. 0.4 parts by weight of sodium hydroxide were added to the dispersion, and the pH was adjusted to 10.0. The temperature was raised to 55 °C, and 12 parts by weight of 50 wt% 2,3-epoxypropyltrimethylammonium chloride aqueous solution were added dropwise at a rate of 0.2 mL / min. After the addition was completed, the reaction was stirred for another 10 h. After the reaction was completed, the mixture was cooled to 24 °C and poured into acetone at 5 times the volume of the reaction solution. After stirring for 20 min, the precipitate was collected by suction filtration. The precipitate was redissolved in deionized water and transferred to a dialysis bag with a molecular weight cutoff of 100 kDa for dialyzing for 48 h. The dialyzed solution was freeze-dried at -50 °C for 24 h to obtain cationic cyclodextrin-based polyrotaxane. Ten parts by weight of cationic cyclodextrin polyrotaxane were dispersed in 70 parts by weight of anhydrous tetrahydrofuran. After dispersion at 200 r / min for 2.5 h under a nitrogen atmosphere, 5 parts by weight of lipoic acid, 1.4 parts by weight of N,N'-dicyclohexylcarbodiimide and 1.5 parts by weight of 4-dimethylaminopyridine were added. The mixture was stirred at 150 r / min in the dark at 20 °C for 20 h. After the reaction was completed, the filtrate was collected by filtration and poured into 6 times the volume of anhydrous diethyl ether. The mixture was stirred for 20 min to allow the product to precipitate completely. The precipitate was collected by suction filtration and washed three times with anhydrous diethyl ether. The washed product was dried under vacuum at 40 °C for 12 h to obtain polyrotaxane containing disulfide bonds. Ten parts by weight of disulfide-bonded polyrotaxane were dispersed in 100 parts by weight of anhydrous ethanol. The mixture was stirred at 150 r / min at 20 °C for 1.5 h. Then, 250 parts by weight of deionized water were added dropwise at a rate of 0.4 mL / min while stirring. After the addition was completed, stirring was continued for 3 h to obtain a suspension. The suspension was transferred to a dialysis bag with a molecular weight cutoff of 100 kDa and dialyzed with deionized water for 20 h. The concentration was adjusted to 18 mg / mL to obtain a modified polyrotaxane dispersion. 100 parts by weight of 80-mesh waste rubber powder were added to a high-speed mixer. The mixer was started and the speed was adjusted to 600 r / min. The temperature was raised to 110°C, and a vacuum was drawn to -0.08 MPa. The vacuum was degassed for 25 min, and the vacuum was stopped. Under a nitrogen protective atmosphere, 20 parts by weight of modified polyrotaxane dispersion were added dropwise at a rate of 0.8 mL / min. After the addition was completed, the speed was increased to 1200 r / min and the mixing was continued for 10 min. The temperature was then raised to 180°C and the reaction was maintained at 800 r / min for 4 h. After the reaction was completed, cooling water was immediately introduced to rapidly cool the material in the mixer to 50°C. The product was poured into a planetary ball mill, 5 parts by weight of zirconia grinding balls were added, and the mixture was ground at 200 r / min for 5 min. The product was then passed through a 100-mesh sieve to obtain high-elastic rubber powder for asphalt.

[0029] Example 2 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Nine parts by weight of polyethylene glycol (Mn2000) were dispersed in 100 parts by weight of deionized water. After stirring and mixing at 200 r / min for 10 min, 0.15 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxy radical, 0.8 parts by weight of sodium bromide, and 15 parts by weight of 10 wt% sodium hypochlorite solution were added. The pH was adjusted to 10, and the mixture was stirred and reacted at 24 °C for 20 min. After the reaction was completed, 200 parts by weight of anhydrous ethanol was added to quench the reaction. The pH was then adjusted to 1 with 1 mol / L hydrochloric acid solution to obtain a mixture. The mixture was extracted three times with dichloromethane. The dichloromethane extracts were combined and concentrated under reduced pressure to obtain a concentrate. The concentrate was added dropwise to cold diethyl ether, allowed to stand for 30 min, and then filtered under reduced pressure to collect the precipitate. The precipitate was dried under vacuum at 40 °C for 12 h to obtain carboxyl-terminated polyethylene glycol. 1.5 parts by weight of carboxyl-terminated polyethylene glycol and 18 parts by weight of α-cyclodextrin were dispersed in 50 parts by weight of deionized water and oscillated at 2500 r / min for 10 min using a turbine mixer at 24 °C to obtain an intermediate. The intermediate was freeze-dried at -50 °C for 48 h to obtain a lyophilized solid. The above lyophilized solid, 6.2 parts by weight of adamantaneamine, 1.5 parts by weight of Caterpillar condensing agent, and 0.4 parts by weight of N,N-diisopropylethylamine were dispersed in 50 parts by weight of anhydrous N,N-dimethylformamide and subjected to nitrogen treatment. The reaction was carried out at 3°C ​​and stirred at 200 r / min for 14 h under a protective atmosphere. After the reaction was completed, the filter cake was collected by vacuum filtration. The filter cake was washed three times with methanol and then dried under vacuum to obtain the crude product. The crude product was dissolved in 100 parts by weight of dimethyl sulfoxide and slowly added dropwise to 1000 parts by weight of boiling deionized water. After stirring and cooling, the precipitate was collected by centrifugation at 10000 r / min for 10 min. The dimethyl sulfoxide dissolution-boiling water precipitation-centrifugation steps were repeated twice. Finally, the precipitate was freeze-dried to obtain cyclodextrin-based polyrotaxane. Ten parts by weight of cyclodextrin-based polyrotaxane were dispersed in 50 parts by weight of dimethyl sulfoxide. The dispersion was stirred at 300 r / min for 1.5 h under a nitrogen atmosphere to obtain a dispersion. 0.4 parts by weight of sodium hydroxide were added to the dispersion, and the pH was adjusted to 10.0. The temperature was raised to 55 °C, and 12 parts by weight of 50 wt% 2,3-epoxypropyltrimethylammonium chloride aqueous solution were added dropwise at a rate of 0.2 mL / min. After the addition was completed, the reaction was stirred for another 10 h. After the reaction was completed, the mixture was cooled to 24 °C and poured into acetone at 5 times the volume of the reaction solution. After stirring for 20 min, the precipitate was collected by suction filtration. The precipitate was redissolved in deionized water and transferred to a dialysis bag with a molecular weight cutoff of 100 kDa for dialyzing for 48 h. The dialyzed solution was freeze-dried at -50 °C for 24 h to obtain cationic cyclodextrin-based polyrotaxane. Ten parts by weight of cationic cyclodextrin polyrotaxane were dispersed in 70 parts by weight of anhydrous tetrahydrofuran. After dispersion at 200 r / min for 2.5 h under a nitrogen atmosphere, 6.2 parts by weight of lipoic acid, 1.4 parts by weight of N,N'-dicyclohexylcarbodiimide and 1.5 parts by weight of 4-dimethylaminopyridine were added. The mixture was stirred at 150 r / min in the dark at 20 °C for 20 h. After the reaction was completed, the filtrate was collected by filtration and poured into 6 times the volume of anhydrous diethyl ether. The mixture was stirred for 20 min to allow the product to precipitate completely. The precipitate was collected by suction filtration and washed three times with anhydrous diethyl ether. The washed product was dried under vacuum at 40 °C for 12 h to obtain polyrotaxane containing disulfide bonds. Ten parts by weight of disulfide-bonded polyrotaxane were dispersed in 100 parts by weight of anhydrous ethanol. The mixture was stirred at 150 r / min for 1.5 h at 20 °C. Then, 250 parts by weight of deionized water were added dropwise at a rate of 0.48 mL / min while stirring. After the addition was completed, stirring was continued for 3 h to obtain a suspension. The suspension was transferred to a dialysis bag with a molecular weight cutoff of 100 kDa and dialyzed with deionized water for 20 h. The concentration was adjusted to 18 mg / mL to obtain a modified polyrotaxane dispersion. 100 parts by weight of 80-mesh waste rubber powder were added to a high-speed mixer. The mixer was started and the speed was adjusted to 600 r / min. The temperature was raised to 110℃, and a vacuum was drawn to -0.08 MPa. The vacuum was degassed for 25 min, and the vacuum was stopped. Under a nitrogen protective atmosphere, 20 parts by weight of modified polyrotaxane dispersion were added dropwise at a rate of 0.8 mL / min. After the addition was completed, the speed was increased to 1200 r / min and the mixing was continued for 10 min. The temperature was then raised to 185℃ and the reaction was maintained at 800 r / min for 3.5 h. After the reaction was completed, cooling water was immediately introduced to rapidly cool the material in the mixer to 50℃. The product was poured into a planetary ball mill, 5 parts by weight of zirconia grinding balls were added, and the mixture was ground at 200 r / min for 5 min. The product was then passed through a 100-mesh sieve to obtain high-elastic rubber powder for asphalt.

[0030] Example 3 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Nine parts by weight of polyethylene glycol (Mn2000) were dispersed in 100 parts by weight of deionized water. After stirring and mixing at 200 r / min for 10 min, 0.15 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxy radical, 0.8 parts by weight of sodium bromide, and 15 parts by weight of 10 wt% sodium hypochlorite solution were added. The pH was adjusted to 10, and the mixture was stirred and reacted at 24 °C for 20 min. After the reaction was completed, 200 parts by weight of anhydrous ethanol was added to quench the reaction. The pH was then adjusted to 1 with 1 mol / L hydrochloric acid solution to obtain a mixture. The mixture was extracted three times with dichloromethane. The dichloromethane extracts were combined and concentrated under reduced pressure to obtain a concentrate. The concentrate was added dropwise to cold diethyl ether, allowed to stand for 30 min, and then filtered under reduced pressure to collect the precipitate. The precipitate was dried under vacuum at 40 °C for 12 h to obtain carboxyl-terminated polyethylene glycol. 1.5 parts by weight of carboxyl-terminated polyethylene glycol and 18 parts by weight of α-cyclodextrin were dispersed in 50 parts by weight of deionized water and oscillated at 2500 r / min for 10 min using a turbine mixer at 24 °C to obtain an intermediate. The intermediate was freeze-dried at -50 °C for 48 h to obtain a lyophilized solid. The above lyophilized solid, 6.2 parts by weight of adamantaneamine, 1.5 parts by weight of Caterpillar condensing agent, and 0.4 parts by weight of N,N-diisopropylethylamine were dispersed in 50 parts by weight of anhydrous N,N-dimethylformamide and subjected to nitrogen treatment. The reaction was carried out at 3°C ​​and stirred at 200 r / min for 14 h under a protective atmosphere. After the reaction was completed, the filter cake was collected by vacuum filtration. The filter cake was washed three times with methanol and then dried under vacuum to obtain the crude product. The crude product was dissolved in 100 parts by weight of dimethyl sulfoxide and slowly added dropwise to 1000 parts by weight of boiling deionized water. After stirring and cooling, the precipitate was collected by centrifugation at 10000 r / min for 10 min. The dimethyl sulfoxide dissolution-boiling water precipitation-centrifugation steps were repeated twice. Finally, the precipitate was freeze-dried to obtain cyclodextrin-based polyrotaxane. Ten parts by weight of cyclodextrin-based polyrotaxane were dispersed in 50 parts by weight of dimethyl sulfoxide. The dispersion was stirred at 300 r / min for 1.5 h under a nitrogen atmosphere to obtain a dispersion. 0.4 parts by weight of sodium hydroxide were added to the dispersion, and the pH was adjusted to 10.0. The temperature was raised to 55 °C, and 12 parts by weight of 50 wt% 2,3-epoxypropyltrimethylammonium chloride aqueous solution were added dropwise at a rate of 0.2 mL / min. After the addition was completed, the reaction was stirred for another 10 h. After the reaction was completed, the mixture was cooled to 24 °C and poured into acetone at 5 times the volume of the reaction solution. After stirring for 20 min, the precipitate was collected by suction filtration. The precipitate was redissolved in deionized water and transferred to a dialysis bag with a molecular weight cutoff of 100 kDa for dialyzing for 48 h. The dialyzed solution was freeze-dried at -50 °C for 24 h to obtain cationic cyclodextrin-based polyrotaxane. Ten parts by weight of cationic cyclodextrin polyrotaxane were dispersed in 70 parts by weight of anhydrous tetrahydrofuran. After dispersion at 200 r / min for 2.5 h under a nitrogen atmosphere, 6.4 parts by weight of lipoic acid, 1.4 parts by weight of N,N'-dicyclohexylcarbodiimide and 1.5 parts by weight of 4-dimethylaminopyridine were added. The mixture was stirred at 150 r / min in the dark at 20 °C for 20 h. After the reaction was completed, the filtrate was collected by filtration and poured into 6 times the volume of anhydrous diethyl ether. The mixture was stirred for 20 min to allow the product to precipitate completely. The precipitate was collected by suction filtration and washed three times with anhydrous diethyl ether. The washed product was dried under vacuum at 40 °C for 12 h to obtain polyrotaxane containing disulfide bonds. Ten parts by weight of disulfide-bonded polyrotaxane were dispersed in 100 parts by weight of anhydrous ethanol. The mixture was stirred at 150 r / min for 1.5 h at 20 °C. Then, 250 parts by weight of deionized water were added dropwise at a rate of 0.45 mL / min while stirring. After the addition was completed, stirring was continued for 3 h to obtain a suspension. The suspension was transferred to a dialysis bag with a molecular weight cutoff of 100 kDa and dialyzed with deionized water for 20 h. The concentration was adjusted to 18 mg / mL to obtain a modified polyrotaxane dispersion. 100 parts by weight of 80-mesh waste rubber powder were added to a high-speed mixer. The mixer was started and the speed was adjusted to 600 r / min. The temperature was raised to 110℃, and a vacuum was drawn to -0.08 MPa. The vacuum was degassed for 25 min, and the vacuum was stopped. Under a nitrogen protective atmosphere, 20 parts by weight of modified polyrotaxane dispersion were added dropwise at a rate of 0.8 mL / min. After the addition was completed, the speed was increased to 1200 r / min, and the mixing was continued for 10 min. The temperature was then raised to 190℃, and the reaction was maintained at 800 r / min for 3.0 h. After the reaction was completed, cooling water was immediately introduced to rapidly cool the material in the mixer to 50℃. The product was poured into a planetary ball mill, 5 parts by weight of zirconia grinding balls were added, and the mixture was ground at 200 r / min for 5 min. The product was then passed through a 100-mesh sieve to obtain high-elastic rubber powder for asphalt.

[0031] Example 4 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Nine parts by weight of polyethylene glycol (Mn2000) were dispersed in 100 parts by weight of deionized water. After stirring and mixing at 200 r / min for 10 min, 0.15 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxy radical, 0.8 parts by weight of sodium bromide, and 15 parts by weight of 10 wt% sodium hypochlorite solution were added. The pH was adjusted to 10, and the mixture was stirred and reacted at 24 °C for 20 min. After the reaction was completed, 200 parts by weight of anhydrous ethanol was added to quench the reaction. The pH was then adjusted to 1 with 1 mol / L hydrochloric acid solution to obtain a mixture. The mixture was extracted three times with dichloromethane. The dichloromethane extracts were combined and concentrated under reduced pressure to obtain a concentrate. The concentrate was added dropwise to cold diethyl ether, allowed to stand for 30 min, and then filtered under reduced pressure to collect the precipitate. The precipitate was dried under vacuum at 40 °C for 12 h to obtain carboxyl-terminated polyethylene glycol. 1.5 parts by weight of carboxyl-terminated polyethylene glycol and 18 parts by weight of α-cyclodextrin were dispersed in 50 parts by weight of deionized water and oscillated at 2500 r / min for 10 min using a turbine mixer at 24 °C to obtain an intermediate. The intermediate was freeze-dried at -50 °C for 48 h to obtain a lyophilized solid. The above lyophilized solid, 6.2 parts by weight of adamantaneamine, 1.5 parts by weight of Caterpillar condensing agent, and 0.4 parts by weight of N,N-diisopropylethylamine were dispersed in 50 parts by weight of anhydrous N,N-dimethylformamide and subjected to nitrogen treatment. The reaction was carried out at 3°C ​​and stirred at 200 r / min for 14 h under a protective atmosphere. After the reaction was completed, the filter cake was collected by vacuum filtration. The filter cake was washed three times with methanol and then dried under vacuum to obtain the crude product. The crude product was dissolved in 100 parts by weight of dimethyl sulfoxide and slowly added dropwise to 1000 parts by weight of boiling deionized water. After stirring and cooling, the precipitate was collected by centrifugation at 10000 r / min for 10 min. The dimethyl sulfoxide dissolution-boiling water precipitation-centrifugation steps were repeated twice. Finally, the precipitate was freeze-dried to obtain cyclodextrin-based polyrotaxane. Ten parts by weight of cyclodextrin-based polyrotaxane were dispersed in 50 parts by weight of dimethyl sulfoxide. The dispersion was stirred at 300 r / min for 1.5 h under a nitrogen atmosphere to obtain a dispersion. 0.4 parts by weight of sodium hydroxide were added to the dispersion, and the pH was adjusted to 10.0. The temperature was raised to 55 °C, and 12 parts by weight of 50 wt% 2,3-epoxypropyltrimethylammonium chloride aqueous solution were added dropwise at a rate of 0.2 mL / min. After the addition was completed, the reaction was stirred for another 10 h. After the reaction was completed, the mixture was cooled to 24 °C and poured into acetone at 5 times the volume of the reaction solution. After stirring for 20 min, the precipitate was collected by suction filtration. The precipitate was redissolved in deionized water and transferred to a dialysis bag with a molecular weight cutoff of 100 kDa for dialyzing for 48 h. The dialyzed solution was freeze-dried at -50 °C for 24 h to obtain cationic cyclodextrin-based polyrotaxane. Ten parts by weight of cationic cyclodextrin polyrotaxane were dispersed in 70 parts by weight of anhydrous tetrahydrofuran. After dispersion at 200 r / min for 2.5 h under a nitrogen atmosphere, 6.6 parts by weight of lipoic acid, 1.4 parts by weight of N,N'-dicyclohexylcarbodiimide and 1.5 parts by weight of 4-dimethylaminopyridine were added. The mixture was stirred at 150 r / min in the dark at 20 °C for 20 h. After the reaction was completed, the filtrate was collected by filtration and poured into 6 times the volume of anhydrous diethyl ether. The mixture was stirred for 20 min to allow the product to precipitate completely. The precipitate was collected by suction filtration and washed three times with anhydrous diethyl ether. The washed product was dried under vacuum at 40 °C for 12 h to obtain polyrotaxane containing disulfide bonds. Ten parts by weight of disulfide-bonded polyrotaxane were dispersed in 100 parts by weight of anhydrous ethanol. The mixture was stirred at 150 r / min at 20°C for 1.5 h. Then, 250 parts by weight of deionized water were added dropwise at a rate of 0.42 mL / min while stirring. After the addition was completed, stirring was continued for 3 h to obtain a suspension. The suspension was transferred to a dialysis bag with a molecular weight cutoff of 100 kDa and dialyzed with deionized water for 20 h. The concentration was adjusted to 18 mg / mL to obtain a modified polyrotaxane dispersion. 100 parts by weight of 80-mesh waste rubber powder were added to a high-speed mixer. The mixer was started and the speed was adjusted to 600 r / min. The temperature was raised to 110℃, and a vacuum was drawn to -0.08 MPa. The vacuum was degassed for 25 min, and the vacuum was stopped. Under a nitrogen protective atmosphere, 20 parts by weight of modified polyrotaxane dispersion were added dropwise at a rate of 0.8 mL / min. After the addition was completed, the speed was increased to 1200 r / min, and the mixing was continued for 10 min. The temperature was then raised to 195℃ and kept at 800 r / min for 2.5 h. After the reaction was completed, cooling water was immediately introduced to rapidly cool the material in the mixer to 50℃. The product was poured into a planetary ball mill, 5 parts by weight of zirconia grinding balls were added, and the mixture was ground at 200 r / min for 5 min. The product was then passed through a 100-mesh sieve to obtain high-elastic rubber powder for asphalt.

[0032] Example 5 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Nine parts by weight of polyethylene glycol (Mn2000) were dispersed in 100 parts by weight of deionized water. After stirring and mixing at 200 r / min for 10 min, 0.15 parts by weight of 2,2,6,6-tetramethylpiperidine-1-oxy radical, 0.8 parts by weight of sodium bromide, and 15 parts by weight of 10 wt% sodium hypochlorite solution were added. The pH was adjusted to 10, and the mixture was stirred and reacted at 24 °C for 20 min. After the reaction was completed, 200 parts by weight of anhydrous ethanol was added to quench the reaction. The pH was then adjusted to 1 with 1 mol / L hydrochloric acid solution to obtain a mixture. The mixture was extracted three times with dichloromethane. The dichloromethane extracts were combined and concentrated under reduced pressure to obtain a concentrate. The concentrate was added dropwise to cold diethyl ether, allowed to stand for 30 min, and then filtered under reduced pressure to collect the precipitate. The precipitate was dried under vacuum at 40 °C for 12 h to obtain carboxyl-terminated polyethylene glycol. 1.5 parts by weight of carboxyl-terminated polyethylene glycol and 18 parts by weight of α-cyclodextrin were dispersed in 50 parts by weight of deionized water and oscillated at 2500 r / min for 10 min using a turbine mixer at 24 °C to obtain an intermediate. The intermediate was freeze-dried at -50 °C for 48 h to obtain a lyophilized solid. The above lyophilized solid, 6.2 parts by weight of adamantaneamine, 1.5 parts by weight of Caterpillar condensing agent, and 0.4 parts by weight of N,N-diisopropylethylamine were dispersed in 50 parts by weight of anhydrous N,N-dimethylformamide and subjected to nitrogen treatment. The reaction was carried out at 3°C ​​and stirred at 200 r / min for 14 h under a protective atmosphere. After the reaction was completed, the filter cake was collected by vacuum filtration. The filter cake was washed three times with methanol and then dried under vacuum to obtain the crude product. The crude product was dissolved in 100 parts by weight of dimethyl sulfoxide and slowly added dropwise to 1000 parts by weight of boiling deionized water. After stirring and cooling, the precipitate was collected by centrifugation at 10000 r / min for 10 min. The dimethyl sulfoxide dissolution-boiling water precipitation-centrifugation steps were repeated twice. Finally, the precipitate was freeze-dried to obtain cyclodextrin-based polyrotaxane. Ten parts by weight of cyclodextrin-based polyrotaxane were dispersed in 50 parts by weight of dimethyl sulfoxide. The dispersion was stirred at 300 r / min for 1.5 h under a nitrogen atmosphere to obtain a dispersion. 0.4 parts by weight of sodium hydroxide were added to the dispersion, and the pH was adjusted to 10.0. The temperature was raised to 55 °C, and 12 parts by weight of 50 wt% 2,3-epoxypropyltrimethylammonium chloride aqueous solution were added dropwise at a rate of 0.2 mL / min. After the addition was completed, the reaction was stirred for another 10 h. After the reaction was completed, the mixture was cooled to 24 °C and poured into acetone at 5 times the volume of the reaction solution. After stirring for 20 min, the precipitate was collected by suction filtration. The precipitate was redissolved in deionized water and transferred to a dialysis bag with a molecular weight cutoff of 100 kDa for dialyzing for 48 h. The dialyzed solution was freeze-dried at -50 °C for 24 h to obtain cationic cyclodextrin-based polyrotaxane. Ten parts by weight of cationic cyclodextrin polyrotaxane were dispersed in 70 parts by weight of anhydrous tetrahydrofuran. After dispersion at 200 r / min for 2.5 h under a nitrogen atmosphere, 6.8 parts by weight of lipoic acid, 1.4 parts by weight of N,N'-dicyclohexylcarbodiimide and 1.5 parts by weight of 4-dimethylaminopyridine were added. The mixture was stirred at 150 r / min in the dark at 20 °C for 20 h. After the reaction was completed, the filtrate was collected by filtration and poured into 6 times the volume of anhydrous diethyl ether. The mixture was stirred for 20 min to allow the product to precipitate completely. The precipitate was collected by suction filtration and washed three times with anhydrous diethyl ether. The washed product was dried under vacuum at 40 °C for 12 h to obtain polyrotaxane containing disulfide bonds. Ten parts by weight of disulfide-bonded polyrotaxane were dispersed in 100 parts by weight of anhydrous ethanol. The mixture was stirred at 150 r / min at 20 °C for 1.5 h. Then, 250 parts by weight of deionized water were added dropwise at a rate of 0.4 mL / min while stirring. After the addition was completed, stirring was continued for 3 h to obtain a suspension. The suspension was transferred to a dialysis bag with a molecular weight cutoff of 100 kDa and dialyzed with deionized water for 20 h. The concentration was adjusted to 18 mg / mL to obtain a modified polyrotaxane dispersion. 100 parts by weight of 80-mesh waste rubber powder were added to a high-speed mixer. The mixer was started and the speed was adjusted to 600 r / min. The temperature was raised to 110℃, and a vacuum was drawn to -0.08 MPa. The vacuum was degassed for 25 min, and the vacuum was stopped. Under a nitrogen protective atmosphere, 20 parts by weight of modified polyrotaxane dispersion were added dropwise at a rate of 0.8 mL / min. After the addition was completed, the speed was increased to 1200 r / min and the mixing was continued for 10 min. The temperature was then raised to 200℃ and the reaction was maintained at 800 r / min for 2.0 h. After the reaction was completed, cooling water was immediately introduced to rapidly cool the material in the mixer to 50℃. The product was poured into a planetary ball mill, 5 parts by weight of zirconia grinding balls were added, and the mixture was ground at 200 r / min for 5 min. The product was then passed through a 100-mesh sieve to obtain high-elastic rubber powder for asphalt.

[0033] Comparative Example 1 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: The α-cyclodextrin in Example 5 was removed, and the carboxyl-terminated polyethylene glycol was directly reacted with adamantane. Other operations were the same as in Example 5.

[0034] Comparative Example 2 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: In Example 5, lipoic acid was replaced with an equimolar amount of hexanoic acid, while other operations remained the same as in Example 5.

[0035] Comparative Example 3 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Remove the 50wt% aqueous solution of 2,3-epoxypropyltrimethylammonium chloride from Example 5, and keep all other operations consistent with Example 5.

[0036] Comparative Example 4 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: The preparation of modified polyrotaxane in Example 5 was omitted. Instead, the modified polyrotaxane dispersion was directly replaced with an equal amount of commercially available liquid nitrile rubber. All other operations remained the same as in Example 5.

[0037] Comparative Example 5 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: Equal weights of polyethylene glycol (Mn 2000), α-cyclodextrin, adamantane, and thioctic acid were mechanically mixed and added to the rubber powder as a modifier. Other operations were the same as in Example 5.

[0038] Comparative Example 6 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: The self-assembly step in Example 5 is omitted. Instead, polyrotaxane containing disulfide bonds is directly reacted with waste rubber powder. Other operations are consistent with those in Example 5.

[0039] Comparative Example 7 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: The high-temperature grafting temperature in Example 5 was reduced to 80°C, the reaction time was 12 hours, and other operations remained the same as in Example 5.

[0040] Comparative Example 8 A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt includes the following steps: The operation of adding the modified polyrotaxane dispersion in Example 5 was replaced by a one-time rapid pour, while other operations remained the same as in Example 5.

[0041] Performance testing The high-elastic rubber powders for asphalt prepared in Examples 1-5 and Comparative Examples 1-7 were subjected to various performance tests, and the test methods are as follows: Embrittlement temperature test: Press the rubber powder into a rectangular sample of 40mm×6mm×2mm, cool it in a cold bath to 5℃ below the expected embrittlement temperature and keep it at a constant temperature; after clamping the sample, impact it with an impact head; if it breaks, raise the temperature by 2℃, if it does not break, lower the temperature by 2℃, and repeat the test; take the average of the adjacent temperatures of the broken and unbroken samples. -40℃ Elastic Recovery Rate Test: Rubber powder is pressed into a 2mm thick sheet, punched into a type I dumbbell specimen, and cooled to -40℃ in an environmental chamber; the specimen is stretched to 200% elongation and held for 10 minutes, unloaded and left to stand for 30 minutes; the residual gauge length is measured and the elastic recovery rate is calculated. Elongation at break test: Rubber powder is pressed into a 2mm thick sheet, punched into a type I dumbbell specimen, and tested at room temperature (23±2℃) and relative humidity 50±5%. The specimen is stretched at a speed of 500mm / min until it breaks, the gauge length at break is recorded, and the elongation at break is calculated. Asphalt bond strength test: Rubber powder and 70# asphalt melted at 160℃ were stirred at a mass ratio of 1:9 for 30 minutes to make a slurry; the slurry was poured into a preheated figure-eight mold, cooled at room temperature for 24 hours and demolded, and tested at room temperature (23±2℃) and relative humidity of 50±5%. The sample was stretched at a speed of 50mm / min until it broke, the maximum load was recorded, and the bond strength was calculated. Freeze-thaw splitting strength ratio test: Asphalt mixture containing 10% rubber powder was prepared according to AC-13 gradation and compacted into Marshall specimens. The specimens were divided into a control group and a freeze-thaw group. The splitting strength of the control group was tested after being kept in a water bath at 25℃. The splitting strength of the freeze-thaw group was tested in the same way after being vacuum saturated with water, frozen at -18℃ for 16h, and then in a water bath at 60℃ for 24h. The strength ratio between the two groups was calculated. The test results are shown in Table 1.

[0042] Table 1. Performance Test Results Embrittlement temperature (°C) Elastic recovery rate at -40℃ (%) Elongation at break (%) Asphalt bond strength (MPa) Freeze-thaw splitting strength ratio (%) Example 1 -56.2 86.5 355 1.62 89.5 Example 2 -57.5 88.7 370 1.71 91.8 Example 3 -58.8 90.2 385 1.83 93.5 Example 4 -60.1 91.5 402 1.92 94.9 Example 5 -61.3 92.8 415 2.05 96.2 Comparative Example 1 -58.5 32.4 255 1.15 82.5 Comparative Example 2 -60.5 38.6 275 1.28 85.2 Comparative Example 3 -56.2 28.5 240 1.02 78.5 Comparative Example 4 -58.8 35.2 298 1.18 84.8 Comparative Example 5 -55 25.8 230 0.85 76.2 Comparative Example 6 -61.5 43.5 315 1.45 88.5 Comparative Example 7 -59.8 39.2 285 1.22 85.8 Comparative Example 8 -60.5 41.5 295 1.32 86.5 The test results in Table 1 show that Examples 1-5 exhibit excellent performance, verifying the stability and reliability of the technical solution of this invention. This invention achieves a synergistic effect of multiple mechanisms through the sliding ring effect of cyclodextrin-based polyrotaxane, the dynamic disulfide bonds of lipoic acid, the structural toughening of helical coiled nanofibers, and the interfacial strengthening through high-temperature catalytic covalent grafting. This effectively solves the problems of poor low-temperature elasticity and weak compatibility with asphalt in traditional rubber powders. The prepared high-elasticity rubber powder can maintain good toughness and interfacial bonding performance even under extreme low-temperature environments.

[0043] The performance degradation in Comparative Example 1 may be due to the absence of α-cyclodextrin, which prevents the construction of the inclusion-sliding structure of polyrotaxane. The lack of a cyclodextrin unit sliding energy dissipation mechanism along the polyethylene glycol backbone leads to stress concentration in the molecular chain at low temperatures, preventing energy dissipation through internal friction, resulting in prominent brittleness and reduced elastic recovery.

[0044] The performance degradation in Comparative Example 2 may be due to the replacement of lipoic acid with hexanoic acid, which completely removes the dynamic disulfide bonds. Without the key energy dissipation pathway of reversible disulfide bond breakage and recombination, the material relies solely on main chain sliding for energy dissipation, resulting in increased permanent deformation at low temperatures and significantly weakened elastic recovery and crack resistance.

[0045] The performance degradation in Comparative Example 3 may be due to the omission of the cationization step and the failure to introduce quaternary ammonium cation groups. The lack of an antifreeze ion pair structure formed by the cation and residual carboxyl groups results in insufficient chain segment flexibility of the modifier at low temperatures; at the same time, the electrostatic adsorption effect is weakened, which reduces the anchoring efficiency of the modifier on the rubber powder surface and the subsequent interfacial bonding strength.

[0046] The performance degradation in Comparative Example 4 may be due to the replacement with traditional liquid nitrile rubber, which lacks sliding rings, dynamic disulfide bonds, and nanofiber topology. At extremely low temperatures, the nitrile rubber molecular chains freeze into a glassy state, losing their toughening ability and becoming defects; it only has physical adsorption with rubber powder and cannot form a stable chemical interface.

[0047] The performance degradation in Comparative Example 5 may be due to the simple physical blending of the components without chemical grafting and self-assembly. Each component exists independently and cannot form a polyrotaxane matrix structure, relying only on weak physical interactions to bond with the rubber powder. Low-molecular-weight components are prone to migration and leaching, leading to a rapid decline in material properties over service life.

[0048] The performance degradation in Comparative Example 6 may be due to the elimination of the induced self-assembly step, which failed to form helical coiled nanofibers. The modifier exists in the form of random coils with a small specific surface area, resulting in uneven coverage of the rubber powder surface and a narrow interfacial transition zone, which significantly reduces stress transfer and energy dissipation efficiency.

[0049] The performance degradation in Comparative Example 7 may be due to the change from high-temperature grafting to a low-temperature, long-time reaction, which failed to overcome the reaction energy barrier. Covalent grafting was inefficient, with most of the modifier only physically adhering and easily detaching during subsequent processing. The interfacial bonding was loose, failing to effectively exert its toughening and reinforcing effects.

[0050] The performance degradation of Comparative Example 8 may be due to rapid pouring instead of slow dropwise addition, leading to excessively high local concentrations and uncontrolled reaction rates. Uneven cation grafting density resulted in disordered precipitation during self-assembly, leading to poor product structural uniformity. This heterogeneous microstructure became a stress concentration source under stress, causing performance fluctuations and an overall decline in performance.

[0051] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt, characterized in that, The preparation method includes the following steps: Polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide and sodium hypochlorite solution were mixed and stirred to obtain carboxyl-terminated polyethylene glycol; Carboxyl-terminated polyethylene glycol and α-cyclodextrin were mixed and shaken, and then freeze-dried to obtain a freeze-dried solid. The freeze-dried solid, adamantane, carter's condensing agent and N,N-diisopropylethylamine were mixed and stirred to obtain cyclodextrin-based polyrotaxane. A cationic cyclodextrin polyrotaxane was obtained by mixing and stirring a cyclodextrin-based polyrotaxane, sodium hydroxide, and an aqueous solution of 2,3-epoxypropyltrimethylammonium chloride. A cationic cyclodextrin polyrotaxane, thioctic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine were mixed and stirred to obtain a disulfide-bonded polyrotaxane; A modified polyrotaxane dispersion was obtained by placing disulfide-bonded polyrotaxane in anhydrous ethanol, adding deionized water dropwise, and then mixing and stirring. High-elasticity rubber powder for asphalt is prepared by mixing and stirring waste rubber powder and modified polyrotaxane dispersion.

2. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The polyethylene glycol has a molecular weight of 2000; the sodium hypochlorite solution has a concentration of 10 wt%; the weight ratio of polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide, and sodium hypochlorite solution is 9~10:0.15~0.25:0.8~1.5:15~25; the reaction conditions for mixing and stirring the polyethylene glycol, 2,2,6,6-tetramethylpiperidine-1-oxy radical, sodium bromide, and sodium hypochlorite solution include a reaction temperature of 24~26℃, a reaction time of 20~30 min, and a reaction pH of 10~11.

3. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The conditions for mixing and shaking the terminal carboxyl-terminated polyethylene glycol and α-cyclodextrin include a temperature of 24-26°C, a time of 10-20 min, and a rotation speed of 2500 r / min; the conditions for mixing and stirring the lyophilized solid, adamantane, Carter's condensing agent, and N,N-diisopropylethylamine include a reaction temperature of 3-5°C and a reaction time of 12-24 h; the weight ratio of the terminal carboxyl-terminated polyethylene glycol, α-cyclodextrin, adamantane, Carter's condensing agent, and N,N-diisopropylethylamine is 1.5-1.7:18-22: The concentration of the 2,3-epoxypropyltrimethylammonium chloride aqueous solution is 50 wt%; the weight ratio of the cyclodextrin-based polyrotaxane, sodium hydroxide, and the 2,3-epoxypropyltrimethylammonium chloride aqueous solution is 10:0.4~0.6:12~18; the mixing and stirring reaction conditions of the cyclodextrin-based polyrotaxane, sodium hydroxide, and the 2,3-epoxypropyltrimethylammonium chloride aqueous solution include a reaction temperature of 55~65℃ and a reaction time of 10~14h.

4. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The weight ratio of the cationic cyclodextrin polyrotaxane, lipoic acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 10:5~7:1.4~1.8:1.5~2.5; the reaction conditions for the cationic cyclodextrin polyrotaxane, lipoic acid, N,N'-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine include a reaction temperature of 20~30℃ and a reaction time of 20~28h.

5. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The weight ratio of the disulfide-bonded polyrotaxane, anhydrous ethanol, and deionized water is 10:100:250~350.

6. The method for preparing a low-temperature resistant high-elastic rubber powder for asphalt as described in claim 1, characterized in that, The conditions for mixing and stirring the disulfide-bonded polyrotaxane in anhydrous ethanol and then adding deionized water include: stirring the disulfide-bonded polyrotaxane in anhydrous ethanol at 20-25°C for 1.5-2.5 hours, then adding deionized water dropwise at a rate of 0.4-0.6 mL / min while stirring, and continuing to stir for 3-5 hours after the addition is complete.

7. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The concentration of the modified polyrotaxane dispersion is 18~22 mg / mL.

8. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The weight ratio of the waste rubber powder to the modified polyrotaxane dispersion is 100:20~30.

9. The method for preparing a low-temperature resistant high-elasticity rubber powder for asphalt as described in claim 1, characterized in that, The mixing conditions for the waste rubber powder and modified polyrotaxane dispersion include mixing and stirring at 110~130℃ for 10~20 min, and then heating to 180~200℃ and stirring for 2~4 h.

10. A low-temperature resistant high-elasticity rubber powder for asphalt, characterized in that, It is prepared by the method for preparing a low-temperature resistant asphalt high-elastic rubber powder according to any one of claims 1 to 9.