High modulus composite modified asphalt material based on natural asphalt and preparation method thereof

Abstract

The present invention belongs to the technical field of asphalt preparation, and provides a high-modulus composite modified asphalt material based on natural asphalt and a preparation method thereof. Natural asphalt is separated into a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment, and activated asphaltene and colloid segments are prepared by alkali treatment and spray drying; a dynamic cross-linked polymer is synthesized based on a styrene-butadiene-styrene block copolymer and a polyurethane prepolymer through steps such as hydrazide reaction, introduction of boric acid groups, and glutaraldehyde cross-linking; organically modified clay and phenylated chitosan are prepared, and a polyaniline composite material is prepared by in-situ polymerization of aniline to obtain a PANI@clay-biomass composite. The ultraviolet absorption characteristics of polyaniline synergize with the shielding effect of montmorillonite to improve the material's resistance to ultraviolet aging. The above-mentioned multiple modified materials are compounded with a natural asphalt base through multi-stage temperature-controlled dispersion to obtain a high-modulus composite modified asphalt material based on natural asphalt.

Description

Technical Field

[0001] The present invention belongs to the technical field of asphalt preparation, and relates to a high-modulus composite modified asphalt material based on natural asphalt and a preparation method thereof. Background Art

[0002] Asphalt, a core binder material in road construction, directly determines the service life and safety of pavement due to its high-temperature rutting resistance, modulus, and weather resistance. With the intensification of global warming and the increasing intensity of ultraviolet radiation, traditional asphalt pavements are prone to softening and deforming during hot seasons, forming rutting. Long-term UV aging, leading to component degradation, brittle cracking, and other problems, is becoming increasingly prominent. Existing asphalt materials are particularly vulnerable to bottlenecks such as insufficient modulus, poor high-temperature stability, and weak UV aging resistance on heavily trafficked arterials and in high-altitude areas with strong UV radiation.

[0003] Asphalt is a temperature-sensitive material, with its modulus decreasing significantly with increasing temperature. Unmodified asphalt struggles to resist the plastic deformation induced by repeated rolling by heavy vehicles above 60°C. While polymer modification can partially improve high-temperature modulus, such materials have inherent flaws: Polyethylene and asphalt have poor compatibility, leading to increased phase separation and a decrease in high-temperature modulus after long-term use. Some high-modulus modifiers (such as rock asphalt) can improve stiffness, but their increased brittleness significantly reduces low-temperature crack resistance and fatigue life, making them difficult to meet the demands of wide-temperature applications. High-modulus asphalt typically relies on high modifier dosages, leading to increased production costs. Furthermore, the saturated and aromatic components in asphalt are UV-sensitive. Under sunlight, they undergo photooxidation reactions, generating polar functional groups such as carbonyls and sulfoxides. UV aging reduces the penetration of asphalt, embrittles the material, and increases the risk of crack propagation. Polar substances generated during aging accumulate at the asphalt-aggregate interface, weakening the bond strength and increasing the debonding rate after water intrusion. Existing anti-UV modification technologies mainly rely on physical shielding agents (such as nano-TiO2, carbon black) or UV absorbers (such as benzotriazole), but their application is limited. Nanoparticles are prone to agglomeration, forming optical scattering centers, which in turn accelerate local aging; small molecule UV absorbers are prone to migration and precipitation, resulting in a decrease in long-term efficiency; anti-UV agents only delay the aging process and cannot simultaneously improve the modulus or repair micro-damage.

[0004] Natural asphalt is a natural mineral resource with widespread distribution, abundant reserves, and relatively low extraction costs. This gives it significant economic advantages, particularly in resource-rich regions, where it is highly cost-effective as a road paving and waterproofing material. Natural asphalt also exhibits excellent bonding properties, with its polar molecular structure effectively interacting with aggregate surfaces to form a strong bond. This property enables it to effectively bind aggregates together in road construction, creating asphalt mixtures with high shear strength and stability. Therefore, it is particularly important to develop a composite modified asphalt based on natural asphalt that exhibits high modulus, high-temperature stability, and UV resistance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a high modulus composite modified asphalt material based on natural asphalt and a preparation method thereof, wherein natural asphalt is separated into a high molecular weight asphaltene segment and a medium and low molecular weight colloid segment by solvent dispersion and fractionation. The high molecular weight asphaltene segment is activated by alkaline aqueous solution to improve its chemical activity and interfacial compatibility with other components, and the medium and low molecular weight colloid segment serves as a bonding matrix to enhance the internal dispersion uniformity of the composite material. At the same time, a dynamic cross-linked polymer is prepared, and the polymer is given good mechanical properties and dynamic reversible cross-linking characteristics by hydrazide treatment of block copolymers and polyurethane prepolymers, introduction of boric acid groups, and multi-step cross-linking. In addition, the present invention utilizes organic cation-modified clay and phenylated chitosan, and constructs a PANI@clay-biomass composite through in-situ polymerization of polyaniline and aluminum ion interface modification, giving the material excellent UV resistance and weather resistance. Finally, through multi-stage temperature-controlled mixing and vacuum degassing, the modified asphalt, colloid segment, dynamic cross-linked polymer and PANI@clay-biomass composite were evenly compounded to prepare a composite modified asphalt material with high modulus and excellent weather resistance, thus meeting the needs of actual production.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt, the preparation method comprising:

[0008] S1, dispersing natural asphalt powder in toluene-n-hexane to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment, dispersing the high-molecular-weight asphaltene segment in a NaOH aqueous solution to obtain activated asphaltene, and rotary evaporating the medium- and low-molecular-weight colloid segment to obtain a colloid segment;

[0009] S2, dispersing a styrene-butadiene-styrene block copolymer and a polyurethane prepolymer in anhydrous toluene, adding adipic acid dihydrazide to react to obtain a hydrazide functionalized polymer, then redispersing the hydrazide functionalized polymer in anhydrous toluene, adding 4-boric acid benzoic acid, then adding an aqueous solution of glutaraldehyde, then adding concentrated sulfuric acid to react to obtain a prepolymer, then dispersing the prepolymer in anhydrous toluene, and adding zinc acetate dihydrate to obtain a dynamically cross-linked polymer;

[0010] S3, dispersing sodium montmorillonite in deionized water, adding hexadecyltrimethylammonium bromide to obtain organically modified clay, dispersing chitosan in an acetic acid aqueous solution, adding phenyl isocyanate, and reacting to obtain phenylated chitosan;

[0011] S4, dispersing the organic modified clay and phenylated chitosan in a dodecylbenzenesulfonic acid aqueous solution, placing in an ice-water bath, adding aniline and ammonium persulfate solution to obtain a PANI@clay-biomass composite, and then dispersing the PANI@clay-biomass composite in deionized water, adding aluminum chloride to obtain a PANI@clay-biomass powder;

[0012] S5, heating the matrix asphalt, adding the colloid segment and activated asphaltene to obtain a natural asphalt base, adding the dynamic cross-linking polymer and PANI@clay-biomass powder to the natural asphalt base to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0013] The preparation method of a high modulus composite modified asphalt material based on natural asphalt specifically comprises:

[0014] S1, dispersing natural asphalt powder in toluene-n-hexane, adjusting the temperature to a first temperature, stirring, and ultrasonically treating, centrifuging after the ultrasonication to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment, dispersing the high-molecular-weight asphaltene segment in a NaOH aqueous solution, adjusting the temperature to a second temperature, stirring, centrifuging, washing, and spray-drying to obtain activated asphaltene, and rotary evaporating the medium- and low-molecular-weight colloid segment to obtain a colloid segment;

[0015] S2, in a nitrogen atmosphere, dispersing a styrene-butadiene-styrene block copolymer and a polyurethane prepolymer in anhydrous toluene and stirring, adding adipic acid dihydrazide, adjusting the temperature to the third temperature for reaction, washing, filtering, and drying after the reaction to obtain a hydrazide functionalized polymer, then redispersing the hydrazide polymer in anhydrous toluene, adding 4-boric acid benzoic acid, adjusting the temperature to the third temperature for further reaction, adding glutaraldehyde aqueous solution and adjusting the pH to 4.5 with acetic acid solution, adjusting the temperature to 60° C. for further reaction, adjusting the temperature to 40° C., adding concentrated sulfuric acid and stirring for reaction, neutralizing the pH to 7 with NaHCO3 solution after the reaction, centrifuging, washing, and drying to obtain a prepolymer, then dispersing the prepolymer in anhydrous toluene, adding zinc acetate dihydrate, adjusting the temperature to the third temperature for reaction, and spray drying after the reaction to obtain a dynamically cross-linked polymer;

[0016] S3, dispersing sodium montmorillonite in deionized water, adding cetyltrimethylammonium bromide after ultrasonic treatment, adjusting the temperature to the second temperature for stirring and reacting, centrifuging, washing and drying to obtain organically modified clay, dispersing chitosan in an acetic acid aqueous solution, adding phenyl isocyanate, nitrogen atmosphere, adjusting the temperature to the third temperature for reaction, and after the reaction, centrifuging and drying to obtain phenylated chitosan;

[0017] S4, dispersing the organically modified clay and phenylated chitosan in an aqueous solution of dodecylbenzenesulfonic acid, adding aniline and ammonium persulfate solution to react under ice-water bath conditions, adding ethanol to terminate the reaction, collecting the precipitate, washing and drying to obtain a PANI@clay-biomass composite, and then dispersing the PANI@clay-biomass composite in deionized water, adding aluminum chloride, adjusting the temperature to a second temperature, stirring the reaction, and spray drying after the reaction to obtain a PANI@clay-biomass powder;

[0018] S5, heat the base asphalt to 160℃, introduce nitrogen and maintain the temperature, then add the colloid segment, adjust the temperature to 170℃ and stir evenly, then add activated asphaltene, adjust the temperature to 180℃ and stir evenly to obtain a natural asphalt base, maintain 190℃, add dynamic cross-linking polymer to the natural asphalt base, heat it to 190℃ and stir, then cool it to 150℃, keep stirring, then heat it to 190℃ and continue stirring, cool it to 165℃, add PANI@clay-biomass powder, stir evenly, vacuum degas, adjust the temperature to 160℃, and continue stirring to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0019] Natural asphalt is a complex, multi-component, high-molecular-weight material, primarily composed of asphaltenes, resins, aromatics, and saturates. High-molecular-weight asphaltene segments, due to their high polarity and low solubility, typically serve as the performance-enhancing phase, while medium- and low-molecular-weight resin segments, due to their excellent fluidity and adhesion, serve as the flexible phase. Therefore, through separation, purification, and chemical modification, the functionalization of each component can be achieved, providing a foundation for the subsequent preparation of high-performance composite modified asphalt materials. Toluene, as a highly polar solvent, effectively dissolves the highly polar medium- and low-molecular-weight resin segments and some aromatic molecules, while n-hexane, as a non-polar solvent, dissolves the non-polar or weakly polar saturates. The combination of toluene and n-hexane allows for selective dissolution of asphalt components. This solvent system effectively distinguishes between high-molecular-weight asphaltene segments and medium- and low-molecular-weight resin segments. Due to their complex molecular structure and high polarity, high-molecular-weight asphaltene segments primarily exist as insoluble precipitates, while medium- and low-molecular-weight resin segments are completely soluble in the mixed solvent. Through the cavitation effect of ultrasound, tiny bubbles will form and collapse rapidly in the liquid environment. The local high temperature, high pressure and strong shear force generated in this process can effectively break the weak intermolecular forces between asphalt molecules, such as π-π stacking and hydrogen bond networks, thereby further promoting the dispersion and dissolution of asphalt.

[0020] Due to their large molecular weight and high density, the high-molecular-weight asphaltene segment rapidly settles under centrifugal force to form a solid phase. However, the medium- and low-molecular-weight colloidal segments, due to their small molecular weight and low density, are primarily distributed in the upper liquid phase. Chemical activation of the high-molecular-weight asphaltene segment is a key step in improving its interfacial compatibility and chemical reactivity. High-molecular-weight asphaltene naturally contains a variety of polar functional groups, including carboxyl, phenolic, thiol, and a small amount of amine. In an alkaline environment, carboxyl and phenolic groups react with hydroxide ions to form the corresponding carboxylates and phenolates. The ionization of the carboxyl groups significantly increases the surface polarity of the molecule, making it more hydrophilic and dispersible in aqueous phases. Furthermore, alkaline conditions can disrupt the intermolecular hydrogen bond network, further releasing active sites on the molecules and enhancing the interfacial activity of the high-molecular-weight asphaltene segment, enabling it to form more stable interfacial bonds in subsequent compounding with other components. In addition to the ionization of functional groups, the alkaline environment may also induce partial crosslinking between asphaltene molecules. For example, thiol groups can be oxidized to disulfide bonds under alkaline conditions. This cross-linking effect improves the structural stability of the molecule to a certain extent. The recovery of the low- and medium-molecular-weight colloidal segments is completed through rotary evaporation. Due to their low molecular weight and excellent fluidity, the colloidal segments can provide good flexibility and adhesion in subsequent compounding, balancing the rigidity and toughness of the composite material.

[0021] A blend of a polyurethane prepolymer and a styrene-butadiene-styrene block copolymer undergoes a nucleophilic addition reaction between the isocyanate groups and the amino groups of the hydrazide compound. The highly reactive isocyanate groups at the ends of the polyurethane prepolymer chains preferentially react with the primary amine groups of adipic acid dihydrazide to form carbamate bonds. This reaction not only achieves covalent grafting of the hydrazide groups but also significantly increases the polarity of the polymer through intermolecular crosslinking. The formation of carbamate bonds enhances the rigidity of the polymer segments and provides chemical sites for the subsequent introduction of dynamic bonds. Furthermore, the unreacted secondary amines in the hydrazide groups, due to their lone pair electrons, serve as coordination sites for subsequent metal ion complexation, laying the foundation for the construction of a multiscale crosslinked network. Subsequently, 4-boronic acid is introduced through a condensation reaction between the boronic acid groups and the amino groups of the hydrazide groups, forming dynamic boronate ester bonds. The formation of boronate ester bonds follows the principle of reversible covalent chemistry: under specific pH and temperature conditions, the boronic acid groups undergo a reversible transesterification reaction with vicinal diols or amino-containing compounds. The introduction of this dynamic bond imparts a unique self-healing capability to the material. When the material is subjected to stress, the borate bonds in the localized stress concentration area preferentially break and recombine, repairing microcracks through the reversible reorganization of the dynamic bond. Furthermore, the conjugated structure of the benzene ring gives this bond significant UV absorption capacity. The π-π transition of the benzene ring effectively absorbs UV light, thereby inhibiting photooxidation damage to the polymer backbone.

[0022] To further enhance the stability of the cross-linked network, glutaraldehyde was introduced as a cross-linker. Under acidic conditions, the aldehyde groups of glutaraldehyde react with amino groups in the polymer chains (including secondary amines from hydrazide residues and carbamate groups in the polyurethane segments) to form dynamic imine bonds. The formation of imine bonds follows a Schiff base reaction mechanism, and their reversibility is regulated by pH. In weakly acidic environments, imine bonds tend to be stable; however, in alkaline or high-temperature conditions, these bonds can undergo hydrolytic cleavage. This pH-responsive property allows the material to reduce melt viscosity during processing (such as high-temperature shearing) by temporarily dissociating the imine bonds, allowing the cross-linked network to reform upon cooling, thereby balancing processing performance with mechanical strength of the final product. The rigid structure of the imine bonds significantly improves the material's storage modulus, and the conjugated system further enhances its anti-aging properties through ultraviolet absorption. The addition of concentrated sulfuric acid catalyzes the sulfonation of the polymer side chains. As a strong proton acid, sulfuric acid activates electron-rich structures such as benzene rings, prompting sulfonic acid groups to replace hydrogen atoms on aromatic rings. The introduction of sulfonic acid groups produces two effects: first, the strong polarity of the sulfonic acid group improves the thermal stability of the polymer, and its decomposition temperature is generally higher than 300°C, which can effectively inhibit the thermal motion of the molecular chain at high temperatures; second, the sulfonic acid group forms intramolecular hydrogen bonds with adjacent amino or hydroxyl groups. These hydrogen bonds and dynamic covalent bonds form a multi-level cross-linked network, which improves the toughness of the material.

[0023] In the final reaction stage, the introduction of zinc ions realizes the synergistic effect of metal coordination bonds and dynamic covalent bonds. 2+ The ion has an empty d orbital and can form a coordination bond with the electron-donating groups in the polymer chain (such as amino groups, sulfonic acid groups and unreacted hydroxyl groups). The coordination number of zinc ions is usually 4 or 6, so a single Zn 2+ It can connect multiple polymer segments at the same time to form a three-dimensional cross-linked node. This coordination bond has dynamic characteristics: under the action of external stress, the coordination bond breaks and dissipates energy; after the stress is released, Zn 2+ It can be re-coordinated with the donor group to restore the network integrity. The introduction of metal coordination bonds not only improves the stiffness and creep resistance of the material, but also further enhances its UV shielding effect. 2+ The dd electron transition of the polymer can absorb ultraviolet light, thereby inhibiting the photodegradation of the polymer backbone. The ultimate performance of the dynamically cross-linked polymer is derived from the synergistic effect of covalent bonds, hydrogen bonds, and coordination bonds. The borate ester bond and the imine bond achieve energy dissipation and self-repair through reversible bond breakage / recombination; the hydrogen bond formed by the sulfonic acid group provides a fast-response energy buffer; the Zn 2+ The coordination bond enhances the stability of the network. Under high temperature, the reversibility of the dynamic bond allows the network to be reconstructed, inhibiting the irreversible slip of the molecular chain, thereby maintaining the modulus stability. In addition, the multi-component UV absorbing groups (phenyl ring, boric acid group, imine bond, Zn 2+) broadens the UV absorption range and significantly delays the photooxidative aging of the polymer.

[0024] As a typical layered silicate mineral, sodium montmorillonite (MMT) has a crystal structure consisting of two silicon-oxygen tetrahedra sandwiching one aluminum-oxygen octahedron. The interlayer domains are charged by sodium ions. This unique layered structure and cation exchangeability provide a foundation for organic modification. When a quaternary ammonium surfactant (cetyltrimethylammonium bromide, CTAB) is dispersed in a MMT suspension, the cations generated by the dissociation of the CTAB molecules, due to their high charge density and hydrophobic long-chain alkyl groups, undergo ion exchange reactions with the sodium ions between the MMT interlayers. This process is driven by the principles of charge balance and entropy increase: the hydrophobic segments of the cations, upon detaching from the aqueous phase, reduce the free energy of the system, while their larger ionic radius (compared to that of sodium ions) causes the interlayer domains to expand. This expanded interlayer spacing not only weakens the interlayer van der Waals forces but also enhances the compatibility of the MMT with organic phases. The surface of the modified organic MMT is covered with long-chain alkyl groups, whose hydrophobicity enables the layered structure to be uniformly dispersed in the nonpolar asphalt matrix, avoiding interfacial defects caused by polarity mismatch. In addition, the nanoscale dispersion of montmorillonite flakes in asphalt can form a physical cross-linked network, which improves the material's deformation resistance and high-temperature stability by limiting the slippage of asphalt molecular chains.

[0025] Chitosan molecular chains are rich in hydroxyl and amino active groups. In weakly acidic aqueous solution, the amino groups of chitosan are protonated to form -NH3 + , significantly enhancing its nucleophilic reactivity. As a functionalizing reagent, phenyl isocyanate has a highly electrophilic isocyanate group that can undergo a nucleophilic addition reaction with a protonated amino group. In the early stage of the reaction, the lone pair of electrons of the amino group of chitosan attacks the carbon atom of the isocyanate group to form a tetrahedral intermediate, which then removes the proton to form a stable substituted urea bond. Since the reactivity of the amino group is higher than that of the hydroxyl group, the main product is chitosan modified with a phenyl urea bond. The introduction of the phenyl group gives chitosan a dual function: first, the hydrophobic effect of the benzene ring weakens the hydrophilicity of chitosan, allowing it to form a stronger π-π stacking effect with the non-polar components in the asphalt, reducing phase separation; second, the conjugated π system of the benzene ring can absorb ultraviolet light and absorb light energy through π-π transitions, thereby inhibiting the oxidative degradation of the polymer chain induced by ultraviolet rays.

[0026] The composite system of organic modified clay and phenylated chitosan achieves functional synergy through multi-scale interactions. The layered structure of montmorillonite forms a nano-scale dispersed phase in asphalt. The long-chain alkyl groups grafted on the surface of the montmorillonite layer are tightly bound to the asphalt component through hydrophobic interactions, while the rigid aromatic rings of the phenylated chitosan are embedded between the aromatic layers of the asphaltene and the resin, forming a molecular-level interpenetrating interface. This organic-inorganic-biomass composite structure synergistically improves the material performance through the following mechanisms: (1) The montmorillonite layer acts as a physical cross-linking point to restrict the movement of the asphalt molecular chain. The van der Waals force between the alkyl chains on its surface and the asphalt component inhibits interfacial slip. The phenylated chitosan bridges the montmorillonite and the asphalt matrix through π-π stacking and hydrogen bonding, forming a three-dimensional interpenetrating network, which significantly improves the tensile strength and fatigue resistance of the composite material. (2) The physical barrier effect of the montmorillonite layer delays the diffusion of heat and oxygen, inhibiting the thermal decomposition of the asphalt component. The ultraviolet absorption ability of the phenylated chitosan and the heat reflection properties of the montmorillonite work synergistically to minimize the photoaging effect. Under high-temperature shear conditions, the montmorillonite layers align under the influence of hydrodynamic forces. The long-chain alkyl groups in the interlayer domains stretch due to enhanced thermal motion, further widening the interlayer spacing and promoting the intercalation of asphalt molecules. Simultaneously, the aromatic rings of the phenylated chitosan undergo thermally induced molecular rearrangement, forming coplanar π-π stacking with the condensed aromatics of the asphaltene. This dynamic interfacial reconstruction results in a stable multi-level cross-linked network in the composite upon cooling. The flexibility of the chitosan segments complements the rigidity of the montmorillonite, enhancing the fracture toughness of the material through interfacial slip and energy dissipation during stress transfer. Furthermore, the UV shielding function of the phenylated chitosan and the thermal stability of the montmorillonite form a positive feedback loop. Montmorillonite inhibits thermal degradation, extending the chitosan's UV absorption lifetime, while chitosan mitigates photooxidation, maintaining the structural integrity of the montmorillonite. The synergistic effect of the montmorillonite layered structure and chitosan enhances the mechanical properties, thermal stability, and aging resistance of the asphalt-based composite.

[0027] Aniline monomers undergo oxidative polymerization in an acidic medium to form a polyaniline backbone. Ammonium persulfate, acting as an oxidant, decomposes under acidic conditions to produce sulfate radicals, which trigger the gradual oxidative coupling of the aniline monomers, forming a conjugated backbone composed of alternating benzene rings and quinone-like structures. The long-chain alkyl groups of dodecylbenzenesulfonic acid (DBSA) guide the directional growth of polyaniline molecules on the surfaces of the clay sheets and chitosan fibers through hydrophobic interactions, forming a nanoscale coating structure. The alkyl chains on the montmorillonite surface adsorb the DBSA molecules through hydrophobic interactions, forming localized high-concentration reaction zones and promoting the ordered polymerization of the aniline monomers. The phenyl groups on the chitosan chains bind to the conjugated rings of the polyaniline through π-π stacking, limiting excessive entanglement of the polyaniline chains and forming a highly oriented nanofiber structure. This restricted growth mechanism allows the polyaniline chains to extend along the clay sheet surface and intertwine with the chitosan molecules to form a three-dimensional interpenetrating network, providing skeletal support for the composite. The aromatic rings of phenylated chitosan and the conjugated chains of polyaniline form interpenetration through π-π stacking, while the amino groups of chitosan and polyaniline generate electrostatic attraction, forming dynamic crosslinking points, which can effectively transfer stress and avoid early failure caused by interface debonding. The aromatic conjugated structure of polyaniline has excellent thermal stability, and its thermal decomposition temperature is much higher than the conventional use temperature of asphalt. In addition, the strong polarity of the sulfonic acid group in the doped polyaniline can inhibit chain segment slippage by enhancing the intermolecular force. Al2O3 produced by the dissociation of aluminum chloride 3+ It forms multidentate coordination bonds with the amino groups of polyaniline, the hydroxyl groups of chitosan and the sulfonic acid groups. 3+ The empty d orbitals can simultaneously connect to multiple electron-donating groups to construct a three-dimensional coordination network. This network has dynamic reversibility: at high temperatures, some coordination bonds break to dissipate energy, and when the temperature drops, they re-coordinate to restore structural integrity. The conjugated main chain of polyaniline exhibits strong absorption characteristics in the ultraviolet region. Its π-π electron transitions can effectively capture high-energy photons and dissipate the excited state energy through non-radiative transitions, inhibiting the free radical chain reaction triggered by photoinduced electron transitions. The synergistic effect of the rigid conjugated skeleton of polyaniline, the nano-enhancement effect of clay, and the interfacial functionalization of chitosan provide the asphalt matrix with a comprehensive performance improvement of high modulus, high thermal stability and resistance to ultraviolet aging.

[0028] The matrix asphalt exhibits viscoelastic fluid properties in the high-temperature molten state. The polar groups in the colloid segment and the asphaltenes in the matrix asphalt form a stable micelle structure through hydrogen bonding and π-π stacking, which reduces the free energy of the system and improves the low-temperature toughness. The addition of activated asphaltene further strengthens the rigidity of the colloidal network. The surface of the activated asphaltene after alkali treatment exposes more oxygen-containing functional groups, which produce strong polar interactions with the aromatic rings in the colloid segment and the matrix asphalt, forming three-dimensional physical cross-linking points. The dynamic cross-linked polymer penetrates into the asphalt colloidal network through chain segment movement at high temperature (190°C). The dynamic covalent bonds (boric acid ester bonds, imine bonds) and metal coordination bonds (Zn 2+) undergoes reversible fracture under thermal activation and is evenly dispersed in the asphalt matrix under shear force. As the temperature decreases, the dynamic bonds are reformed and anchored on the surface of the asphalt micelles: the borate bonds form hydrogen bonds with the polar groups in the asphaltene, and the Zn 2+ The polymer chains coordinate with the sulfonic acid groups of the activated asphaltene and the carboxyl groups of the resin segments. The polymer chains form an interpenetrating structure with the asphalt network. The rigid benzene ring backbone restricts the slippage of the asphalt molecular chains through steric hindrance, increasing the elastic modulus of the composite. The reversible breakage and recombination of the dynamic bonds imparts fatigue resistance to the material when subjected to external forces.

[0029] As a preferred technical solution of the present invention, in S1, the mass volume ratio of the natural asphalt powder to toluene-n-hexane is 1 kg:10 L.

[0030] In some optional examples, the volume ratio of toluene to n-hexane is 3:1.

[0031] In some optional embodiments, the first temperature is 40-50°C, for example, it can be 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C or 50°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In some optional embodiments, the stirring time at the first temperature is 30-40 min, for example, it can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional examples, the mass fraction of the NaOH aqueous solution is 5 wt.%.

[0034] In some optional embodiments, the second temperature is 60-70°C, for example, it can be 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C or 70°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In some optional embodiments, the stirring time at the second temperature is 1-2h, for example, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] As a preferred technical solution of the present invention, in S2, the mass ratio of the styrene-butadiene-styrene block copolymer, the polyurethane prepolymer and the adipic acid dihydrazide is 7:3:1.

[0037] In some optional embodiments, the third temperature is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In some optional embodiments, the time of the third temperature reaction is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In some optional examples, the mass volume ratio of the styrene-butadiene-styrene block copolymer, 4-boric acid benzoic acid, glutaraldehyde aqueous solution, concentrated sulfuric acid and zinc acetate dihydrate is 70g:10g:5mL:15mL:0.5g.

[0040] In some optional embodiments, the reaction time at the third temperature is 6-7h, for example, it can be 6h, 6.1h, 6.2h, 6.3h, 6.4h, 6.5h, 6.6h, 6.7h, 6.8h, 6.9h or 7h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some optional examples, the mass fraction of the glutaraldehyde aqueous solution is 50 wt.%.

[0042] In some optional examples, the concentration of the acetic acid solution is 0.1M.

[0043] In some optional embodiments, the reaction time at 60°C is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In some optional embodiments, the time for continuing the reaction by adding concentrated sulfuric acid is 2-3 hours, for example, it can be 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In some optional embodiments, the third temperature stirring reaction time is 4-5h, for example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] As a preferred technical solution of the present invention, in S3, the mass ratio of the sodium montmorillonite to hexadecyltrimethylammonium bromide is 10:4.4.

[0047] In some optional embodiments, the ultrasonic treatment time is 30-40 min, for example, it can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] In some optional embodiments, the second temperature stirring reaction time is 6-7h, for example, it can be 6h, 6.1h, 6.2h, 6.3h, 6.4h, 6.5h, 6.6h, 6.7h, 6.8h, 6.9h or 7h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] In some optional examples, the mass volume ratio of chitosan to phenyl isocyanate is 1 g:2 mL.

[0050] In some optional examples, the mass fraction of the acetic acid aqueous solution is 2 wt.%.

[0051] In some optional embodiments, the time of the third temperature reaction is 10-12h, for example, it can be 10h, 10.2h, 10.4h, 10.6h, 10.8h, 11h, 11.2h, 11.4h, 11.6h, 11.8h or 12h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] As a preferred technical solution of the present invention, in S4, the mass volume ratio of the organically modified clay, phenylated chitosan, aniline and ammonium persulfate solution is 5g:3g:5mL:50mL.

[0053] In some optional examples, the mass volume ratio of the organically modified clay to the aqueous solution of dodecylbenzenesulfonic acid is 1 g:40 mL.

[0054] In some optional examples, the concentration of aniline is 0.1M.

[0055] In some optional examples, the mass fraction of the ammonium persulfate solution is 9 wt.%.

[0056] In some optional embodiments, the reaction time is 6-7h, for example, it can be 6h, 6.1h, 6.2h, 6.3h, 6.4h, 6.5h, 6.6h, 6.7h, 6.8h, 6.9h or 7h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] In some optional examples, the mass ratio of the organically modified clay to aluminum chloride is 5:0.3.

[0058] In some optional embodiments, the second temperature stirring reaction time is 2-3h, for example, it can be 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] As a preferred technical solution of the present invention, in S5, the mass ratio of the matrix asphalt, the colloid segment, the activated asphaltene, the dynamic cross-linked polymer and the PANI@clay-biomass powder is 100:15:12:5:4.

[0060] In some optional examples, the base asphalt is No. 90 base asphalt.

[0061] In a second aspect, the present invention provides a high modulus composite modified asphalt material based on natural asphalt prepared by the preparation method described in the first aspect.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) the borate bonds and imine bonds in the dynamically cross-linked polymer absorb energy through reversible fracture, avoiding brittle failure caused by stress concentration, and the rigid condensed ring structure of the activated asphalt and the conjugated skeleton of polyaniline form an interpenetrating network through π-π stacking to provide rigid support. The lamellar structure of the organic modified clay limits the slippage of the asphalt molecular chain, and the rigid conjugated chain of polyaniline is anchored to the asphalt network through hydrogen bonds, thereby enhancing the modulus of the asphalt; (2) the alkyl chains on the surface of the organic modified clay are combined with the asphalt through hydrophobic interaction, reducing high-temperature phase separation, and the dynamic covalent bonds in the dynamically cross-linked polymer are reversibly broken at high temperatures and prevent irreversible slippage of the molecular chain; after the temperature is lowered, the dynamic bonds are reorganized to restore the network integrity, avoiding permanent deformation caused by high-temperature softening of traditional materials, and improving the high-temperature stability of asphalt; (3) the conjugated main chain of polyaniline and the benzene ring of phenylated chitosan absorb ultraviolet light, Al 3+ With Zn 2+The coordination center captures free radicals triggered by ultraviolet rays through empty d orbitals, blocks the photooxidation chain reaction, protects the polymer and asphalt components, and improves the anti-ultraviolet performance of asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is the high modulus composite modified asphalt material based on natural asphalt provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0064] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0065] The chemical reagents used in the examples and comparative examples of the present invention are all commercially available products and have not been subjected to any further purification treatment.

[0066] Example 1

[0067] This embodiment provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt, and the preparation method specifically comprises the following steps:

[0068] S1: 1 kg of natural asphalt powder was dispersed in 10 L of toluene-n-hexane, the temperature was adjusted to 44°C, stirring was performed for 33 min, and ultrasonic treatment was performed. After the ultrasonic treatment, the mixture was centrifuged to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment. The high-molecular-weight asphaltene segment was dispersed in a 5 wt.% NaOH aqueous solution, the temperature was adjusted to 65°C, stirring was performed for 1.0 h, centrifuged, washed, and spray-dried to obtain activated asphaltene. The medium- and low-molecular-weight colloid segment was rotary evaporated to obtain a colloid segment.

[0069] S2, in a nitrogen atmosphere, 70 g of styrene-butadiene-styrene block copolymer and 30 g of polyurethane prepolymer were dispersed in 500 mL of anhydrous toluene and stirred, 10 g of adipic acid dihydrazide was added, the temperature was adjusted to 88 ° C and the reaction was carried out for 4.6 h. After the reaction was completed, the hydrazide functionalized polymer was washed, filtered and dried to obtain the hydrazide functionalized polymer. The hydrazide functionalized polymer was then redispersed in 500 mL of anhydrous toluene, 10 g of 4-boric acid benzoic acid was added, the temperature was adjusted to 80 ° C and the reaction was continued for 6.4 h, and 5 mL of 50 wt.% glutaraldehyde aqueous solution was added. The solution was adjusted to pH 4.5 using 0.1 M acetic acid solution, the temperature was adjusted to 60° C. and the reaction was continued for 2.4 h. The temperature was adjusted to 40° C., 15 mL of concentrated sulfuric acid was added and stirred for 2.2 h. After the reaction, 10 wt.% NaHCO3 solution was used to neutralize the pH to 7, centrifuged, washed and dried to obtain a prepolymer, and then the prepolymer was dispersed in 200 mL of anhydrous toluene, 0.5 g of zinc acetate dihydrate was added, the temperature was adjusted to 80° C. and stirred for 4.2 h. After the reaction, it was spray-dried to obtain a dynamically cross-linked polymer.

[0070] S3, 10g of sodium montmorillonite was dispersed in 500mL of deionized water, ultrasonically treated for 33min, and then 4.4g of hexadecyltrimethylammonium bromide was added. The temperature was adjusted to 65℃ and stirred for 6.7h. The mixture was centrifuged, washed and dried to obtain organically modified clay. 5g of chitosan was dispersed in 200mL of 2wt% acetic acid aqueous solution, and 10mL of phenyl isocyanate was added. The mixture was heated to 88℃ under nitrogen atmosphere and reacted for 11.5h. After the reaction, the mixture was centrifuged and dried to obtain phenylated chitosan.

[0071] S4, 5 g of organically modified clay and 3 g of phenylated chitosan were dispersed in 200 mL of dodecylbenzenesulfonic acid aqueous solution. Under ice-water bath conditions, 5 mL of 0.1 M aniline and 50 mL of 9 wt.% ammonium persulfate solution were added and reacted for 6.3 h. Ethanol was added to terminate the reaction. The precipitate was collected and washed and dried to obtain a PANI@clay-biomass composite. The PANI@clay-biomass composite was then dispersed in 200 mL of deionized water, 0.3 g of aluminum chloride was added, the temperature was adjusted to 61 ° C, and the reaction was stirred for 2.2 h. After the reaction was completed, the PANI@clay-biomass powder was spray-dried;

[0072] S5, heat 10kg of matrix asphalt to 160℃, introduce nitrogen and maintain for 33 minutes, then add 1.5kg of colloid segment, adjust the temperature to 170℃ and stir evenly, then add 1.2kg of activated asphalt, adjust the temperature to 180℃ and stir evenly to obtain a natural asphalt base, maintain 190℃, add 500g of dynamic cross-linking polymer to the natural asphalt base, heat to 190℃ and stir for 10 minutes, then cool to 150℃, keep stirring for 10 minutes, then heat to 190℃ and continue stirring for 10 minutes, cool to 165℃, add 400g of PANI@clay-biomass powder, stir evenly, vacuum degassing and adjust the temperature to 160℃, continue stirring for 47 minutes to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0073] Figure 1 This is the high modulus composite modified asphalt material based on natural asphalt prepared in this example.

[0074] Example 2

[0075] This embodiment provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt, and the preparation method specifically comprises the following steps:

[0076] S1: 1 kg of natural asphalt powder was dispersed in 10 L of toluene-n-hexane, the temperature was adjusted to 40°C, stirring was performed for 37 min, and ultrasonic treatment was performed. After the ultrasonic treatment, the mixture was centrifuged to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment. The high-molecular-weight asphaltene segment was dispersed in a 5 wt.% NaOH aqueous solution, the temperature was adjusted to 60°C, stirring was performed for 1.7 h, centrifuged, washed, and spray-dried to obtain activated asphaltene. The medium- and low-molecular-weight colloid segment was rotary evaporated to obtain a colloid segment.

[0077] S2, in a nitrogen atmosphere, 70 g of styrene-butadiene-styrene block copolymer and 30 g of polyurethane prepolymer were dispersed in 500 mL of anhydrous toluene and stirred, 10 g of adipic acid dihydrazide was added, the temperature was adjusted to 80 ° C and the reaction was carried out for 4.0 h. After the reaction was completed, the hydrazide functionalized polymer was washed, filtered and dried to obtain the hydrazide functionalized polymer. The hydrazide functionalized polymer was then redispersed in 500 mL of anhydrous toluene, 10 g of 4-boric acid benzoic acid was added, the temperature was adjusted to 83 ° C and the reaction was continued for 6.0 h, and 5 mL of 50 wt.% glutaraldehyde aqueous solution was added. The solution was adjusted to pH 4.5 using 0.1 M acetic acid solution, the temperature was adjusted to 60° C. and the reaction was continued for 2.0 h. The temperature was adjusted to 40° C., 15 mL of concentrated sulfuric acid was added and stirred for 2.7 h. After the reaction, 10 wt.% NaHCO3 solution was used to neutralize the pH to 7, centrifuged, washed and dried to obtain a prepolymer, and then the prepolymer was dispersed in 200 mL of anhydrous toluene, 0.5 g of zinc acetate dihydrate was added, the temperature was adjusted to 83° C. and stirred for 4.8 h. After the reaction, it was spray-dried to obtain a dynamically cross-linked polymer;

[0078] S3, 10g of sodium montmorillonite was dispersed in 500mL of deionized water, ultrasonically treated for 38min, and then 4.4g of hexadecyltrimethylammonium bromide was added. The temperature was adjusted to 60℃ and stirred for 6h. The mixture was centrifuged, washed and dried to obtain organically modified clay. 5g of chitosan was dispersed in 200mL of 2wt% acetic acid aqueous solution, 10mL of phenyl isocyanate was added, and nitrogen atmosphere was adjusted to 80℃ for 10h. After the reaction, the mixture was centrifuged and dried to obtain phenylated chitosan.

[0079] S4, 5 g of organically modified clay and 3 g of phenylated chitosan were dispersed in 200 mL of dodecylbenzenesulfonic acid aqueous solution. Under ice-water bath conditions, 5 mL of 0.1 M aniline and 50 mL of 9 wt.% ammonium persulfate solution were added and reacted for 6.0 h. Ethanol was added to terminate the reaction. The precipitate was collected and washed and dried to obtain a PANI@clay-biomass composite. The PANI@clay-biomass composite was then dispersed in 200 mL of deionized water, 0.3 g of aluminum chloride was added, and the temperature was adjusted to 60 ° C and stirred for 2.0 h. After the reaction, the mixture was spray-dried to obtain a PANI@clay-biomass powder.

[0080] S5, heat 10kg of matrix asphalt to 160℃, introduce nitrogen and maintain for 37min, then add 1.5kg of colloid segment, adjust the temperature to 170℃ and stir evenly, then add 1.2kg of activated asphalt, adjust the temperature to 180℃ and stir evenly to obtain a natural asphalt base, maintain 190℃, add 500g of dynamic cross-linking polymer to the natural asphalt base, heat to 190℃ and stir for 10min, then cool to 150℃, keep stirring for 10min, then heat to 190℃ and continue stirring for 10min, cool to 165℃, add 400g of PANI@clay-biomass powder, stir evenly, vacuum degassing and adjust the temperature to 160℃, continue stirring for 40min to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0081] Example 3

[0082] This embodiment provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt, and the preparation method specifically comprises the following steps:

[0083] S1: 1 kg of natural asphalt powder was dispersed in 10 L of toluene-n-hexane, the temperature was adjusted to 50°C, stirring was performed for 40 min, and ultrasonic treatment was performed. After the ultrasonic treatment, the mixture was centrifuged to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment. The high-molecular-weight asphaltene segment was dispersed in a 5 wt.% NaOH aqueous solution, the temperature was adjusted to 70°C, stirring was performed for 2.0 h, centrifuged, washed, and spray-dried to obtain activated asphaltene. The medium- and low-molecular-weight colloid segment was rotary evaporated to obtain a colloid segment.

[0084] S2, in a nitrogen atmosphere, 70 g of styrene-butadiene-styrene block copolymer and 30 g of polyurethane prepolymer were dispersed in 500 mL of anhydrous toluene and stirred, 10 g of adipic acid dihydrazide was added, the temperature was adjusted to 86 ° C and the reaction was carried out for 4.2 h. After the reaction was completed, the hydrazide functionalized polymer was washed, filtered and dried to obtain the hydrazide functionalized polymer. The hydrazide functionalized polymer was then redispersed in 500 mL of anhydrous toluene, 10 g of 4-boric acid benzoic acid was added, the temperature was adjusted to 90 ° C and the reaction was continued for 7.0 h, and 5 mL of 50 wt.% glutaraldehyde aqueous solution was added. The solution was adjusted to pH 4.5 using 0.1 M acetic acid solution, the temperature was adjusted to 60° C. and the reaction was continued for 2.8 h. The temperature was adjusted to 40° C., 15 mL of concentrated sulfuric acid was added and stirred for 3.0 h. After the reaction, 10 wt.% NaHCO3 solution was used to neutralize the pH to 7, centrifuged, washed and dried to obtain a prepolymer, and then the prepolymer was dispersed in 200 mL of anhydrous toluene, 0.5 g of zinc acetate dihydrate was added, the temperature was adjusted to 90° C. and the reaction was stirred for 4.0 h. After the reaction, spray drying was performed to obtain a dynamically cross-linked polymer.

[0085] S3, 10g of sodium montmorillonite was dispersed in 500mL of deionized water, ultrasonically treated for 30min, 4.4g of hexadecyltrimethylammonium bromide was added, the temperature was adjusted to 70℃, stirred and reacted for 7.0h, centrifuged, washed and dried to obtain organically modified clay, 5g of chitosan was dispersed in 200mL of 2wt% acetic acid aqueous solution, 10mL of phenyl isocyanate was added, nitrogen atmosphere was adjusted to 90℃ and reacted for 10.8h, after the reaction was completed, centrifuged and dried to obtain phenylated chitosan;

[0086] S4, 5 g of organically modified clay and 3 g of phenylated chitosan were dispersed in 200 mL of dodecylbenzenesulfonic acid aqueous solution. Under ice-water bath conditions, 5 mL of 0.1 M aniline and 50 mL of 9 wt.% ammonium persulfate solution were added and reacted for 6.8 h. Ethanol was added to terminate the reaction. The precipitate was collected and washed and dried to obtain a PANI@clay-biomass composite. The PANI@clay-biomass composite was then dispersed in 200 mL of deionized water, 0.3 g of aluminum chloride was added, and the temperature was adjusted to 70 ° C and stirred for 3.0 h. After the reaction, the mixture was spray-dried to obtain a PANI@clay-biomass powder.

[0087] S5, heat 10kg of matrix asphalt to 160℃, introduce nitrogen and maintain for 30min, then add 1.5kg of colloid segment, adjust the temperature to 170℃ and stir evenly, then add 1.2kg of activated asphalt, adjust the temperature to 180℃ and stir evenly to obtain a natural asphalt base, maintain 190℃, add 500g of dynamic cross-linking polymer to the natural asphalt base, heat to 190℃ and stir for 10min, then cool to 150℃, keep stirring for 10min, then heat to 190℃ and continue stirring for 10min, cool to 165℃, add 400g of PANI@clay-biomass powder, stir evenly, vacuum degassing and adjust the temperature to 160℃, continue stirring for 50min to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0088] Example 4

[0089] This embodiment provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt, and the preparation method specifically comprises the following steps:

[0090] S1: 1 kg of natural asphalt powder was dispersed in 10 L of toluene-n-hexane, the temperature was adjusted to 46°C, stirring was performed for 30 min, and ultrasonic treatment was performed. After the ultrasonic treatment, the mixture was centrifuged to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment. The high-molecular-weight asphaltene segment was dispersed in a 5 wt.% NaOH aqueous solution, the temperature was adjusted to 63°C, stirring was performed for 1.5 h, centrifuged, washed, and spray-dried to obtain activated asphaltene. The medium- and low-molecular-weight colloid segment was rotary evaporated to obtain a colloid segment.

[0091] S2, in a nitrogen atmosphere, 70 g of styrene-butadiene-styrene block copolymer and 30 g of polyurethane prepolymer were dispersed in 500 mL of anhydrous toluene and stirred, 10 g of adipic acid dihydrazide was added, the temperature was adjusted to 90 ° C and the reaction was carried out for 5.0 h. After the reaction was completed, the hydrazide functionalized polymer was washed, filtered and dried to obtain the hydrazide functionalized polymer. The hydrazide functionalized polymer was then redispersed in 500 mL of anhydrous toluene, 10 g of 4-boric acid benzoic acid was added, the temperature was adjusted to 84 ° C and the reaction was continued for 6.8 h, and 5 mL of 50 wt.% glutaraldehyde aqueous solution was added. The solution was adjusted to pH 4.5 using 0.1 M acetic acid solution, the temperature was adjusted to 60° C. and the reaction was continued for 3.0 h. The temperature was adjusted to 40° C., 15 mL of concentrated sulfuric acid was added and stirred for 2.0 h. After the reaction, 10 wt.% NaHCO3 solution was used to neutralize the pH to 7, and the mixture was centrifuged, washed, and dried to obtain a prepolymer. The prepolymer was then dispersed in 200 mL of anhydrous toluene, 0.5 g of zinc acetate dihydrate was added, the temperature was adjusted to 84° C. and stirred for 5.0 h. After the reaction, the mixture was spray-dried to obtain a dynamically cross-linked polymer.

[0092] S3, 10g of sodium montmorillonite was dispersed in 500mL of deionized water, ultrasonically treated for 40min, 4.4g of hexadecyltrimethylammonium bromide was added, the temperature was adjusted to 69°C, stirred and reacted for 6.4h, centrifuged, washed and dried to obtain organically modified clay, 5g of chitosan was dispersed in 200mL of 2wt% acetic acid aqueous solution, 10mL of phenyl isocyanate was added, nitrogen atmosphere was adjusted to 84°C and reacted for 12.0h, after the reaction was completed, centrifuged and dried to obtain phenylated chitosan;

[0093] S4, 5 g of organically modified clay and 3 g of phenylated chitosan were dispersed in 200 mL of dodecylbenzenesulfonic acid aqueous solution. Under ice-water bath conditions, 5 mL of 0.1 M aniline and 50 mL of 9 wt.% ammonium persulfate solution were added and reacted for 7.0 h. Ethanol was added to terminate the reaction. The precipitate was collected and washed and dried to obtain a PANI@clay-biomass composite. The PANI@clay-biomass composite was then dispersed in 200 mL of deionized water, 0.3 g of aluminum chloride was added, the temperature was adjusted to 66 ° C, and the reaction was stirred for 2.7 h. After the reaction was completed, the PANI@clay-biomass powder was spray-dried;

[0094] S5, heat 10kg of matrix asphalt to 160℃, introduce nitrogen and maintain for 40min, then add 1.5kg of colloid segment, adjust the temperature to 170℃ and stir evenly, then add 1.2kg of activated asphalt, adjust the temperature to 180℃ and stir evenly to obtain a natural asphalt base, maintain 190℃, add 500g of dynamic cross-linking polymer to the natural asphalt base, heat to 190℃ and stir for 10min, then cool to 150℃, keep stirring for 10min, then heat to 190℃ and continue stirring for 10min, cool to 165℃, add 400g of PANI@clay-biomass powder, stir evenly, vacuum degassing and adjust the temperature to 160℃, continue stirring for 43min to obtain a high modulus composite modified asphalt material based on natural asphalt.

[0095] Comparative Example 1

[0096] This comparative example provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt. The difference between it and Example 1 is that the mass of the dynamically cross-linked polymer in S5 is 200g, which is 300g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0097] Comparative Example 2

[0098] This comparative example provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt. The difference between it and Example 1 is that the mass of the dynamically cross-linked polymer in S5 is 800g, which is 300g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0099] Comparative Example 3

[0100] This comparative example provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt. The difference between it and Example 1 is that the mass of PANI@clay-biomass powder in S5 is 100 g, which is 300 g less than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0101] Comparative Example 4

[0102] This comparative example provides a method for preparing a high modulus composite modified asphalt material based on natural asphalt. The difference between it and Example 1 is that the mass of PANI@clay-biomass powder in S5 is 700 g, which is 300 g more than that in Example 1. The other process parameters and operating conditions are exactly the same as those in Example 1.

[0103] The prepared high-modulus composite modified asphalt material was tested. Three specimens of each type were prepared and the average values ​​were calculated. Ductility testing was performed according to T0605, elastic recovery testing was performed according to T0662, dynamic modulus testing was performed according to T0738, and 60°C dynamic stability testing was performed according to T0719. UV aging testing involved aging the test specimens in a UV aging chamber for 1000 hours. The dynamic stability of the specimens was then measured and the average values ​​were calculated. The post-aging test was performed according to T0719. The climate zone was designated as a cold winter zone. The test results are shown in Table 1.

[0104] Table 1 Test results of high modulus composite modified asphalt materials based on natural asphalt in Examples 1-4 and Comparative Examples 1-4

[0105]

[0106] As shown in Table 1, compared to Example 1, Comparative Example 1 exhibits increased ductility, while its elastic recovery, dynamic modulus, 60°C dynamic stability, and 60°C dynamic stability after UV aging all decrease. Comparative Example 2 exhibits decreased ductility and elastic recovery, while its dynamic modulus, 60°C dynamic stability, and 60°C dynamic stability after UV aging increase. This is due to insufficient dynamic crosslinking polymer in Comparative Example 1, resulting in a low crosslinking network density. While ductility exhibits good performance at low crosslinking density, reversible breakage of dynamic bonds is the source of elastic recovery. Insufficient amounts reduce elastic recovery, dynamic modulus, and 60°C dynamic stability. The crosslinking network in the dynamic crosslinking polymer effectively mitigates the effects of aging, but when insufficient amounts are added, this protective effect is limited, leading to a further decrease in the dynamic stability after aging. The excessive amount of dynamic crosslinking polymer in Comparative Example 2 increases the crosslinking density of the composite material, enhancing its rigidity and, consequently, decreasing ductility and elastic recovery. The high crosslinking density of the dynamic network gives the composite material greater resistance to deformation under high-frequency loads, while also improving its resistance to UV aging.

[0107] As shown in Table 1, compared to Example 1, Comparative Example 3 exhibits increased ductility, while its elastic recovery, dynamic modulus, 60°C dynamic stability, and 60°C dynamic stability after UV aging all decrease. Comparative Example 4 exhibits decreased ductility and elastic recovery, while its dynamic modulus, 60°C dynamic stability, and 60°C dynamic stability after UV aging all increase. This is due to insufficient PANI@clay-biomass powder in Comparative Example 3. The rigid conjugated skeleton of PANI and the montmorillonite flakes enhance the dynamic modulus, but this enhancement is limited when insufficient. Furthermore, the UV shielding capabilities of polyaniline and phenylated chitosan are weakened. In Comparative Example 4, excessive PANI@clay-biomass powder reduces the toughness of the material, while increasing its dynamic modulus and 60°C dynamic stability and its UV resistance.

[0108] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a high modulus composite modified asphalt material based on natural asphalt, characterized in that: The preparation method comprises: S1, dispersing natural asphalt powder in toluene-n-hexane to obtain a high-molecular-weight asphaltene segment and a medium- and low-molecular-weight colloid segment, dispersing the high-molecular-weight asphaltene segment in a NaOH aqueous solution to obtain activated asphaltene, and rotary evaporating the medium- and low-molecular-weight colloid segment to obtain a colloid segment; S2, dispersing a styrene-butadiene-styrene block copolymer and a polyurethane prepolymer in anhydrous toluene, adding adipic acid dihydrazide to react to obtain a hydrazide functionalized polymer, then redispersing the hydrazide functionalized polymer in anhydrous toluene, adding 4-boric acid benzoic acid, then adding an aqueous solution of glutaraldehyde, then adding concentrated sulfuric acid to react to obtain a prepolymer, then dispersing the prepolymer in anhydrous toluene, and adding zinc acetate dihydrate to obtain a dynamically cross-linked polymer; S3, dispersing sodium montmorillonite in deionized water, adding hexadecyltrimethylammonium bromide to obtain organically modified clay, dispersing chitosan in an acetic acid aqueous solution, adding phenyl isocyanate, and reacting to obtain phenylated chitosan; S4, dispersing the organic modified clay and phenylated chitosan in a dodecylbenzenesulfonic acid aqueous solution, placing in an ice-water bath, adding aniline and ammonium persulfate solution to obtain a PANI@clay-biomass composite, and then dispersing the PANI@clay-biomass composite in deionized water, adding aluminum chloride to obtain a PANI@clay-biomass powder; S5, heating the base asphalt, adding the colloid segment and activated asphaltene to obtain a natural asphalt base, adding the dynamic cross-linking polymer and PANI@clay-biomass powder to the natural asphalt base to obtain a high modulus composite modified asphalt material based on natural asphalt; The mass ratio of the matrix asphalt, the colloid segment, the activated asphaltene, the dynamic cross-linked polymer and the PANI@clay-biomass powder is 100:15:12:5:

4.

2. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S1, The mass volume ratio of the natural asphalt powder to toluene-n-hexane is 1 kg:10 L.

3. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S2, The mass ratio of the styrene-butadiene-styrene block copolymer, the polyurethane prepolymer and the adipic acid dihydrazide is 7:3:

1.

4. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S2, The mass volume ratio of the styrene-butadiene-styrene block copolymer, 4-boric acid benzoic acid, glutaraldehyde aqueous solution, concentrated sulfuric acid and zinc acetate dihydrate is 70g:10g:5mL:15mL:0.5g.

5. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S3, The mass ratio of the sodium montmorillonite to hexadecyltrimethylammonium bromide is 10:4.

4.

6. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S3, The mass volume ratio of the chitosan to phenyl isocyanate is 1 g:2 mL.

7. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S4, The mass volume ratio of the organic modified clay, phenylated chitosan, aniline and ammonium persulfate solution is 5g:3g:5mL:50mL.

8. The method for preparing a high modulus composite modified asphalt material based on natural asphalt according to claim 1, characterized in that: In S4, The mass ratio of the organic modified clay to aluminum chloride is 5:0.

3.

9. A high modulus composite modified asphalt material based on natural asphalt is obtained according to the preparation method according to any one of claims 1 to 8.

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