High-branching-degree polyolefin modifier, preparation method and directly-modified asphalt

Abstract

The invention discloses a high-branching-degree polyolefin modifier, a preparation method and directly-modified asphalt, and belongs to the technical field of polyolefin modified materials. The modifier comprises a main body material and a disulfide bond cross-linked network structure unit, wherein the main body material takes polyethylene as a matrix and is grafted with a maleic anhydride functionalized star-shaped skeleton and an 8-shaped topological structure, and the disulfide bond cross-linked network structure unit penetrates through the main body structure; the preparation method comprises the following steps: S1, synchronous grafting of a maleic anhydride functionalized star-shaped skeleton and long-chain 1-octene; S2, introduction of a double-end epoxy group and 8-shaped topology construction; and S3, construction of a disulfide bond cross-linked network. The preparation method of the directly-modified asphalt comprises the following steps: adding a modifier and matrix asphalt into a directly-heated asphalt production tank, stirring at a low speed, heating to 180-190 DEG C, and keeping for 60-120 minutes to finish modification; the technical problems of poor compatibility, storage segregation, contradiction between high and low temperature performance and the like of the recycled polyolefin modified asphalt are solved through a three-stage structural design; and in combination with a direct modification process, light equipment weight, instant production and cost intensification are realized.

Description

Technical Field

[0001] This invention belongs to the technical field of polyolefin modified materials, and relates to a highly branched polyolefin modifier, particularly to a highly branched polyolefin modifier, its preparation method, and its direct modification to asphalt. Background Technology

[0002] Recycled polyethylene (PE) is used as an asphalt modifier primarily through physical blending or chemical grafting to improve asphalt performance, offering both environmental and economic benefits. Its core advantages include enhanced high-temperature stability, increased asphalt hardness, ductility, and crack resistance, extended road service life, and improved storage stability. Chinese patent application number 202410409082.9, "A Special Synergistic Additive for Recycled Polyethylene Modified Asphalt Systems, Its Synthesis Method, and Its Application," designs a synergistic additive containing oleyl chloride and calcium para-aminobenzoate salt, which is used in conjunction with recycled PE in asphalt. The disclosed modified asphalt exhibits significantly optimized high-temperature stability and low-temperature ductility, incorporates sulfur / nitrogen elements to achieve flame retardant properties, and eliminates the need for pre-granulation, simplifying the direct modification process. However, this patent also has shortcomings. Although the long carbon chains and polar groups in the additive molecule simultaneously improve the compatibility between polyethylene and asphalt, the linear polyethylene chains are difficult to form a spatial network, resulting in lower low-temperature crack resistance compared to SBS-modified asphalt.

[0003] To improve the compatibility of polyethylene and asphalt, and at the same time enhance low-temperature crack resistance, it is necessary to study the preparation method of polyolefin modifiers. Summary of the Invention

[0004] The purpose of this invention is to develop a highly branched polyolefin modifier that synergistically improves the compatibility and low-temperature crack resistance of directly modified asphalt through a star-shaped skeleton, figure-eight topology, and disulfide bond crosslinking network.

[0005] The technical solution adopted in this invention is a highly branched polyolefin modifier. The key feature is that the modifier comprises a main material consisting of a star-shaped backbone and a figure-eight topology grafted with maleic anhydride onto a polyethylene matrix, and disulfide bond crosslinking network structural units running through the main structure. The maleic anhydride-functionalized star-shaped backbone uses silicomanganese slag fiber as its core, with polyethylene glycol methacrylate arm layers grafted onto its surface. The maleic anhydride functional layer is chemically grafted onto the surface of the arm layers of the star-shaped backbone. The figure-eight topology is formed by bridging adjacent polyolefin chains with a double-ended epoxy group linker and crosslinking with sorbitol to form a closed loop. The ring network, in which the polyolefin chains of the figure-eight topology are bridged with the maleic anhydride functional layer by 1-octene; the disulfide bond crosslinking network is constructed by a premixed resin of epoxy resin and terpene resin and SBR pyrolysis product in the polyethylene matrix under the action of an aldehyde crosslinking agent, forming a through-linking network; the silicomanganese slag fiber includes 38% to 41% SiO2, 25% to 27% CaO, 6.0% to 8.0% MnO, and ≤2.5% alkali metal oxides by mass; the double-terminated epoxy group linker is ethylene glycol diglycidyl ether.

[0006] Specifically, the preparation of the aforementioned star-shaped framework includes: soaking ferrosilicon manganese slag fibers in citric acid ethanol solution for 1.5h to 2.5h, then immersing them in a nano-bentonite pregel suspension, and treating them at a constant temperature of 58℃ to 62℃ for 45min to 75min to obtain a ferrosilicon manganese slag fiber core, referred to as the SMF core; activating the SMF core with triethylamine ethanol solution, then spraying it with trimethylolpropane tris(3-mercaptopropionic acid) ester or pentaerythritol tetra(3-mercaptopropionic acid) ester to form a thiolized interface; coating it with a polyethylene glycol methacrylate solution containing a photoinitiator at 365nm. The mercapto-alkene click reaction was completed by UV irradiation for 25-35 seconds to obtain the basic star-shaped framework. The basic star-shaped framework, maleic anhydride, dicumyl peroxide, and styrene were added to a torque rheometer at a mass ratio of 100:15-20:0.8-1.2:4-6. The mixture was melt-blended at 175-180℃ and 55-65 r / min for 5-10 minutes. The temperature was then raised to 184-187℃ and the rotation speed was increased to 90-95 r / min. The reaction was continued for 3-5 minutes. The grafting peak value was monitored by torque mutation to determine the reaction endpoint. The reaction was terminated by liquid nitrogen quenching. After precipitation and purification, the maleic anhydride-functionalized star-shaped framework was obtained.

[0007] More specifically, the pH of the above-mentioned citric acid ethanol solution is 4.3–4.8; the above-mentioned nano-bentonite pregel suspension is obtained by adding nano-bentonite to water at 25°C–35°C at a mass ratio of 4%–6%, dispersing at a high-speed shear rate of 1500 r / min–2000 r / min for 25 min–35 min to form a pregel suspension, and allowing it to stand for 8 h–12 h; the mass concentration of triethylamine in the above-mentioned triethylamine ethanol solution is 0.5%–1.5%, and the triethylamine ethanol solution is activated by stirring at 38°C–42°C for 8 min–12 min; the above-mentioned polyethylene glycol containing photoinitiator In the polyethylene glycol methacrylate solution, the mass concentration of the photoinitiator is 0.5% to 1.0%, and the number-average molecular weight of the polyethylene glycol methacrylate used is in the range of 650 to 1000. The photoinitiator is any one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, or 2-hydroxy-2-methyl-1-phenyl-1-propanone. The grafting peak value is monitored by torque mutation, and the standard for determining the reaction endpoint is to monitor the torque change in real time by a torque rheometer. When the torque value increases by ≥15% within 30 seconds, the reaction endpoint is determined.

[0008] Furthermore, the preparation process of the above-mentioned SBR pyrolysis product involves mixing and pyrolyzing SBR raw material with dicumyl peroxide and naphthenic oil at 180℃~200℃ for 15min~20min, with the mass ratio of SBR raw material, dicumyl peroxide and naphthenic oil being 100:1.0~1.5:5~10; after filtration through a 200-mesh sieve, it is diluted with xylene at a ratio of 1:1; the above-mentioned SBR raw material is styrene-butadiene rubber particles with a particle size ≤2mm that have been treated with NaOH solution.

[0009] The preparation method of the highly branched polyolefin modifier, used to prepare the above-mentioned modifier, mainly includes: S1, simultaneous grafting of maleic anhydride-functionalized star-shaped backbone and long-chain 1-octene to obtain a polyethylene material with a star-shaped backbone; S2, introduction of bi-terminal epoxy groups and figure-eight topology to obtain a polyethylene material with a figure-eight topology; S3, construction of disulfide bond crosslinking network to obtain the above-mentioned highly branched polyolefin modifier.

[0010] Further, by mass parts, step S1 specifically involves: adding 100 parts of recycled polyethylene fragments, 12 to 18 parts of maleic anhydride-functionalized star-shaped backbone, 4 to 6 parts of 1-octene, 0.5 to 1 part of initiator, and 0.05 to 0.15 parts of antioxidant to a mixer, and grafting at 172°C to 178°C and 85 to 95 rpm for 2 to 5 minutes. After the reaction is complete, granulation is performed, followed by washing with n-hexane and drying to obtain a polyethylene material with a star-shaped backbone. The initiator is any one of dicumyl peroxide, benzoyl peroxide, or di-tert-butyl peroxide; the antioxidant is any one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, or 2,6-di-tert-butyl-p-cresol; the recovered polyethylene fragments are pretreated by melt index sorting (MFI > 10 g / 10 min) and washing with a 6%–8% phosphoric acid solution, with an impurity content < 0.3%.

[0011] Further, by mass fraction, step S2 specifically involves: adding 10-15 parts of ethylene glycol diglycidyl ether to 200-300 parts of xylene solvent, adding 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1, adding 0.3-0.5 parts of triphenylphosphine, and performing surface modification at 128-132°C for 35-45 minutes. After the reaction, the reaction solution is poured into ice-cold methanol for precipitation, filtration, and drying to obtain a polyethylene material with an initial ring and introduced double-terminal epoxy groups. The polyethylene material with the initial ring is then sprayed with a 5%-10% sorbitol ethanol solution and reacted at 148-152°C and 0.4-0.6 MPa for 25-35 minutes. After the reaction, it is extracted with ethanol and dried to obtain a polyethylene material with a figure-eight topology.

[0012] Furthermore, by mass, step S3 specifically involves: adding 100 parts of polyethylene material with a figure-eight topology, premixed resin, 0.5 to 0.8 parts of crosslinking agent, and 6 to 10 parts of SBR pyrolysis product to an internal mixer; mixing under nitrogen protection; controlling the temperature at 110°C to 115°C, the shear rate at 1400 to 1600 r / min, and the reaction time at 15 to 25 min; after the reaction, the melt is pressed into sheets, subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier; the aforementioned premixed resin is obtained by pre-dispersing 10 to 15 parts of epoxy resin and 4 to 7 parts of terpene resin at 115°C to 125°C for 10 to 15 min; the aforementioned crosslinking agent is any one of glyoxal, glutaraldehyde, or paraformaldehyde.

[0013] The key to a direct-modification asphalt process is to add the aforementioned highly branched polyolefin modifier and base asphalt to a direct-heating asphalt production tank at a mass ratio of 4-6:100, dynamically stir at a speed of 10-30 r / min, and simultaneously heat to 180-190℃ and maintain the temperature for 60-120 minutes to complete the modification reaction; the modified asphalt can then be used directly after the reaction.

[0014] Specifically, the aforementioned base asphalt includes No. 70 road petroleum asphalt or No. 90 road petroleum asphalt; during the modification reaction process, rubber powder may also be added, and the mass ratio of the rubber powder to the base asphalt is 15-25:100.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] This invention prepares a highly branched polyolefin modifier, whose tertiary branching structure synergistically enhances performance. In the modifier of this invention, a star-shaped skeleton with SiO2 / CaO / MnO precisely proportioned ferrosilicon slag fibers as the core significantly improves the molecular chain density through entanglement effect, enabling the modified asphalt to achieve a dynamic viscosity of 17000 Pa·s to 21890 Pa·s at 60℃ and a softening point of over 80℃, which is significantly improved compared to the control, effectively resisting rutting deformation. In the modifier of this invention, the figure-eight topology helps optimize low-temperature crack resistance, that is, the closed-loop network formed by the bridging of the diepoxy groups disperses stress concentration, and combined with the plasticizing effect of SBR pyrolysis products, the ductility at 5℃ reaches 36.9 cm to 47.2 cm, with an m value > 0.33, meeting the crack resistance requirements of extremely cold regions. In the modifier of this invention, self-healing is achieved through the disulfide bond network, and the dynamic disulfide bonds can reversibly break and recombine at high temperatures, dissipating stress and repairing microcracks. The segregation softening point difference is as low as 1.4℃, and the storage stability far exceeds the specification limit. Furthermore, the maleic anhydride functional layer in the modifier of the present invention forms hydrogen bonds with the asphalt components, and the flexible long chain with 1-octene bridging significantly improves the compatibility of the modifier with asphalt, reduces the penetration index by about 80% compared with the control, and greatly improves the temperature sensitivity.

[0017] The highly branched polyolefin modifier prepared using this invention enables direct modification of asphalt, meaning the modifier is directly added to the base asphalt, and modification is completed by low-speed stirring for 1-2 hours, eliminating the need for complex processes such as colloid mill shearing and multi-stage development required in traditional methods. Furthermore, the modifier of this invention is compatible with direct blending of rubber powder, supporting the simultaneous addition of up to 20% rubber powder without prior pyrolysis or activation treatment, thus simplifying the rubber powder asphalt production process.

[0018] The economic value of this invention is significant. Traditional processes use shearing equipment with a capacity of up to one million kilowatts and a total power of approximately 800 kW, while the direct-heating asphalt production tank used is a standard mixing tank with a capacity of one hundred thousand kilowatts and a total power of no more than 100 kW. This reduces equipment investment by over 70% and energy consumption by over 80%. The production cycle of the direct-heating asphalt produced by this invention is less than 2 hours, while traditional processes involve transportation and have a production cycle of approximately 8 hours, representing a speed increase of over 75%. Whether considering equipment unit price and energy consumption, or shortening the production cycle, this invention significantly reduces production costs. Furthermore, traditional production processes suffer from performance degradation due to transportation, leading to product quality fluctuations exceeding 10%. The direct-heating asphalt of this invention avoids pre-production asphalt transportation, resulting in stable product quality, a near 100% pass rate, and a 20%–30% reduction in waste. From an environmental perspective, the raw materials used in the modifier of this invention, such as ferrosilicon manganese slag fiber and recycled polyethylene, are all waste materials, contributing to the recycling and reuse of waste resources. In addition, this invention enables immediate use of production starting from 5 tons per batch, unlike traditional processes which require more than 60 tons per production run. It is suitable for both large and small batches and adaptable to various engineering scenarios.

[0019] In summary, this invention overcomes technical challenges such as poor compatibility, storage segregation, and contradictory high and low temperature performance of recycled polyolefin modified asphalt through a three-level structural design of star-shaped skeleton-figure-eight topology-disulfide bond network. Combined with direct conversion technology, it achieves a triple breakthrough in "lightweight equipment, real-time production, and cost reduction," providing a technological paradigm for the high-value utilization of solid waste and green road construction. The 2025 Serang-Baningbang toll road project in Indonesia further validates the high and low temperature performance and ease of construction of the directly converted asphalt produced by this invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the asphalt processing procedure of the direct conversion process of this invention;

[0021] Figure 2 This is a schematic diagram of the traditional asphalt processing method. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms "comprising," "including," "having," and "containing" used in this document are open-ended, meaning they include but are not limited to. Where specific conditions are not specified in the examples, they can be performed under conventional conditions. Reagents or instruments whose manufacturers are not specified are all commercially available products. The ferrosilicon manganese slag fiber and nano-bentonite were also sourced externally.

[0026] Silicomanganese slag fiber is a fibrous material formed by water quenching and rapid cooling of high-temperature slag produced during the smelting of silicomanganese alloys. After crushing, ball milling, and particle size classification, fibers and products with a particle size of ≤100μm are obtained. Its main components include SiO2 and CaO, and it also contains small amounts of Al2O3, MgO, MnO, K2O and alkali metals (Na2O and K2O). It is generally used as an industrial waste treatment product.

[0027] Nano-bentonite is a commercially available product made from natural montmorillonite as raw material, which is a clay mineral that has been purified and nano-processed, with a particle size ≤100nm. The nano-bentonite used in this invention has a particle size specification of 20nm~50nm.

[0028] Example 1

[0029] In this embodiment, the preparation of the maleic anhydride-functionalized star-shaped framework is carried out through the following process:

[0030] Step (1) 100 parts of ferrosilicon slag fiber were added to 110 parts of citric acid ethanol solution with pH 4.5 and soaked for 2.0 h. Then, it was immersed in 180 parts of nano-bentonite pregel suspension and treated at 60℃ for 60 min. After filtration and washing with deionized water 3 times, ferrosilicon slag fiber core, abbreviated as SMF core, was obtained.

[0031] The nano-bentonite pregel suspension used in this step is obtained by adding nano-bentonite at a mass ratio of 5% to water at 30°C, dispersing it at a high speed of 1750 r / min for 30 min to form a pregel suspension, and then letting it stand for 10 h.

[0032] Step (2) The obtained SMF core is added to 100 parts of a 1.0% triethylamine ethanol solution and stirred at 40°C for 10 min to activate it. Trimethylolpropane tris(3-mercaptopropionic acid) ester is sprayed to form a thiolized interface. After spraying, it is left to stand for 10 min to allow the solvent to evaporate and is ready for use. The trimethylolpropane tris(3-mercaptopropionic acid) ester used is prepared by dissolving 6 parts of trimethylolpropane tris(3-mercaptopropionic acid) ester in anhydrous ethanol to prepare a 5% ethanol solution before use.

[0033] Step (3) Coating 65 parts of a polyethylene glycol methacrylate solution containing a photoinitiator, and irradiating with 365nm UV for 30s to complete the mercapto-olefin click reaction to obtain the basic star-shaped skeleton; the photoinitiator in the polyethylene glycol methacrylate solution containing the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, the mass concentration of the photoinitiator is 0.8%, and the number average molecular weight of polyethylene glycol methacrylate is 867.2.

[0034] Step (4) The obtained basic star-shaped framework, maleic anhydride, dicumyl peroxide, and styrene were added to a torque rheometer at a mass ratio of 100:17:1.0:5. The mixture was melt-blended at 178°C and 60 r / min for 8 min. The temperature was then raised to 186°C and the rotation speed was increased to 92 r / min. The reaction was continued for 4 min. The grafting peak value was monitored by torque mutation to determine the reaction endpoint. The torque change was monitored in real time by the torque rheometer. When the torque value increased by ≥15% within 30 s, the reaction was considered to be over. The reaction was terminated by liquid nitrogen quenching. The product was dissolved with boiling xylene and precipitated with acetone. The process was repeated 3 times for purification to obtain the maleic anhydride functionalized star-shaped framework, which was designated as MAH functionalized framework sample 1.

[0035] In this embodiment, the ferrosilicon manganese slag fiber used contains 40.3% SiO2, 26.4% CaO, 6.4% MgO, 8.6% Al2O3, 7.2% MnO, 2.2% Fe2O3, 1.3% K2O, 1.1% Na2O, and 0.6% P2O5. Other impurities account for 2.9%, and the loss on ignition is 2.9%.

[0036] Example 2

[0037] In this embodiment, the preparation of the maleic anhydride-functionalized star-shaped framework is carried out through the following process:

[0038] Step (1) 100 parts of ferrosilicon slag fiber were added to 100 parts of citric acid ethanol solution with pH 4.8 and soaked for 1.5h. Then, it was immersed in 200 parts of nano-bentonite pregel suspension and treated at 62℃ for 45min. After filtration and washing with deionized water 3 times, ferrosilicon slag fiber core, abbreviated as SMF core, was obtained.

[0039] The nano-bentonite pregel suspension used in this step is obtained by adding nano-bentonite at a mass ratio of 4% to water at 25°C, dispersing it at a high speed of 2000r / min for 25min to form a pregel suspension, and then letting it stand for 8h.

[0040] Step (2) The obtained SMF core is added to 120 parts of 0.5% triethylamine ethanol solution and stirred at 42°C for 8 min for activation. Pentaerythritol tetra(3-mercaptopropionic acid) ester is sprayed to form a thiolized interface. After spraying, it is left to stand for 15 min to allow the solvent to evaporate and is ready for use. The pentaerythritol tetra(3-mercaptopropionic acid) ester used is prepared by dissolving 4 parts of pentaerythritol tetra(3-mercaptopropionic acid) ester in anhydrous ethanol to prepare an ethanol solution with a mass concentration of 5%.

[0041] Step (3) Coating 80 parts of a polyethylene glycol methacrylate solution containing a photoinitiator, and irradiating with 365nm UV for 25s to complete the mercapto-olefin click reaction to obtain the basic star-shaped skeleton; In the polyethylene glycol methacrylate solution containing a photoinitiator used, the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, the mass concentration of the photoinitiator is 0.5%, and the number average molecular weight of polyethylene glycol methacrylate is 996.7.

[0042] Step (4) The obtained basic star-shaped framework, maleic anhydride, dicumyl peroxide, and styrene were added to a torque rheometer at a mass ratio of 100:20:0.8:6. The mixture was melt-blended at 180°C and 55 r / min for 5 min. The temperature was then raised to 187°C and the rotation speed was increased to 95 r / min. The reaction was continued for 3 min. The grafting peak value was monitored by torque mutation to determine the reaction endpoint. The torque change was monitored in real time by the torque rheometer. When the torque value increased by ≥15% within 30 s, the reaction was considered to be over. The reaction was terminated by liquid nitrogen quenching. The product was dissolved with boiling xylene and precipitated with acetone. The process was repeated 3 times for purification to obtain the maleic anhydride functionalized star-shaped framework, which was designated as MAH functionalized framework sample 2.

[0043] In this embodiment, the ferrosilicon manganese slag fiber used contains 41.0% SiO2, 25.0% CaO, 8.0% MgO, 8.2% Al2O3, 7.4% MnO, 2.8% Fe2O3, 1.2% K2O, 1.3% Na2O, and 0.5% P2O5. Other impurities account for 2.2%, and the loss on ignition is 2.3%.

[0044] Example 3

[0045] In this embodiment, the preparation of the maleic anhydride-functionalized star-shaped framework is carried out through the following process:

[0046] Step (1) 100 parts of ferrosilicon slag fiber were added to 120 parts of citric acid ethanol solution with pH 4.3 and soaked for 2.5 hours. Then, it was immersed in 150 parts of nano-bentonite pregel suspension and treated at 58°C for 75 minutes. After filtration and washing with deionized water 3 times, ferrosilicon slag fiber core, abbreviated as SMF core, was obtained.

[0047] The nano-bentonite pregel suspension used in this step is obtained by adding nano-bentonite at a mass ratio of 6% to water at 35°C, dispersing it at a high speed of 1500 r / min for 35 min to form a pregel suspension, and then letting it stand for 12 h.

[0048] Step (2) The obtained SMF core is added to 80 parts of a 1.5% triethylamine ethanol solution and stirred at 38°C for 12 min for activation. Trimethylolpropane tri(3-mercaptopropionic acid) ester is sprayed to form a mercapto interface. After spraying, it is left to stand for 8 min to allow the solvent to evaporate and is ready for use. The trimethylolpropane tri(3-mercaptopropionic acid) ester used is prepared by dissolving 8 parts of trimethylolpropane tri(3-mercaptopropionic acid) ester in anhydrous ethanol to prepare a 5% ethanol solution before use.

[0049] Step (3) Coating 50 parts of a polyethylene glycol methacrylate solution containing a photoinitiator, and irradiating with 365nm UV for 35s to complete the mercapto-olefin click reaction to obtain the basic star-shaped skeleton; the photoinitiator in the polyethylene glycol methacrylate solution containing the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, the mass concentration of the photoinitiator is 1.0%, and the number average molecular weight of polyethylene glycol methacrylate is 663.2.

[0050] Step (4) The obtained basic star-shaped framework, maleic anhydride, dicumyl peroxide, and styrene were added to a torque rheometer at a mass ratio of 100:15:1.2:4. The mixture was melt-blended at 175°C and 65 r / min for 10 min. The temperature was then raised to 184°C and the rotation speed was increased to 90 r / min. The reaction was continued for 5 min. The grafting peak value was monitored by torque mutation to determine the reaction endpoint. The torque change was monitored in real time by the torque rheometer. When the torque value increased by ≥15% within 30 s, the reaction was considered to be over. The reaction was terminated by liquid nitrogen quenching. The product was dissolved with boiling xylene and precipitated with acetone. The process was repeated 3 times for purification to obtain the maleic anhydride functionalized star-shaped framework, which was designated as MAH functionalized framework sample 3.

[0051] In this embodiment, the ferrosilicon manganese slag fiber used contains 38.1% SiO2, 26.9% CaO, 6.2% MgO, 8.2% Al2O3, 7.8% MnO, 3.1% Fe2O3, 1.2% K2O, 1.1% Na2O, and 1.2% P2O5 by mass, with other impurities accounting for 3.0% and loss on ignition of 3.0%.

[0052] Example 4

[0053] In this embodiment, the preparation of SBR lysates is carried out, specifically as follows:

[0054] Styrene-butadiene rubber granules with an average particle size of 1.81 mm were soaked in a 5% NaOH solution to remove surface oil, then rinsed with water until the washing solution was neutral, and vacuum dried at 60°C to a moisture content of 0.42% to obtain SBR raw material.

[0055] The SBR feedstock, dicumyl peroxide, and naphthenic oil were internally mixed and cracked at 190°C for 18 min. The mass ratio of SBR feedstock, dicumyl peroxide, and naphthenic oil was 100:1.2:7.

[0056] After filtration through a 200-mesh sieve, the SBR pyrolysis product was obtained by diluting it with xylene at a 1:1 ratio. The SBR pyrolysis product contained thiol groups and was designated as SBR pyrolysis product sample 1.

[0057] Example 5

[0058] In this embodiment, the preparation of SBR lysates is carried out, specifically as follows:

[0059] Styrene-butadiene rubber granules with an average particle size of 1.98 mm were soaked in a 5.5% NaOH solution to remove surface oil, then rinsed with water until the washing solution was neutral, and vacuum dried at 60°C until the moisture content was 0.49% to obtain SBR raw material.

[0060] The SBR feedstock, dicumyl peroxide, and naphthenic oil were internally mixed and cracked at 200℃ for 15 minutes. The mass ratio of SBR feedstock, dicumyl peroxide, and naphthenic oil was 100:1.5:10.

[0061] After filtration through a 200-mesh sieve, the SBR pyrolysis product was obtained by diluting it with xylene at a 1:1 ratio. The SBR pyrolysis product contained thiol groups and was designated as SBR pyrolysis product sample 2.

[0062] Example 6

[0063] In this embodiment, the preparation of SBR lysates is carried out, specifically as follows:

[0064] Styrene-butadiene rubber granules with an average particle size of 1.64 mm were soaked in a 4.5% NaOH solution to remove surface oil stains, then rinsed with water until the washing solution was neutral, and vacuum dried at 60°C until the moisture content was 0.37% to obtain SBR raw material.

[0065] The SBR feedstock, dicumyl peroxide, and naphthenic oil were internally mixed and pyrolyzed at 180°C for 20 min. The mass ratio of SBR feedstock, dicumyl peroxide, and naphthenic oil was 100:1.0:5.

[0066] After filtration through a 200-mesh sieve, the SBR pyrolysis product was obtained by diluting it with xylene at a 1:1 ratio. The SBR pyrolysis product contained thiol groups and was designated as SBR pyrolysis product sample 3.

[0067] Example 7

[0068] In this embodiment, a highly branched polyolefin modifier is prepared. The specific process is as follows:

[0069] Simultaneous grafting of S1, maleic anhydride-functionalized star-shaped backbone, and long-chain 1-octene yields a polyethylene material with a star-shaped backbone.

[0070] 100 parts of recycled polyethylene fragments, 15 parts of MAH functionalized skeleton sample, 5 parts of 1-octene, 0.8 parts of initiator, and 0.10 parts of antioxidant were added to a mixer and grafted at 175℃ and 90r / min for 4min. After the reaction, the mixture was granulated by a water-cooled string pelletizer, washed three times with boiling n-hexane, and vacuum dried at 60℃ to obtain a polyethylene material with a star-shaped skeleton.

[0071] The initiator is dicumyl peroxide;

[0072] The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0073] The recycled polyethylene fragments used were sorted by melt index (MFI) to obtain polyethylene fragments with a concentration of MFI > 10 g / 10 min. They were then pretreated by washing with a 7% phosphoric acid solution with an impurity content of 0.21%. The impurities included organic impurities such as label residue adhesive, oil stains, and incompletely removed additives; inorganic impurities such as metal fragments such as Fe and Al, silicate dust from the treatment of silicon manganese slag fibers, and phosphate precipitates; and mixed contaminants such as mud, gravel, and carbonized particles mixed in during transportation or storage.

[0074] The introduction of S2, dual-terminal epoxy groups, and figure-eight topology yields a polyethylene material with a figure-eight topology:

[0075] 12 parts of the linker ethylene glycol diglycidyl ether were added to 250 parts of xylene solvent, 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1 were added, and 0.4 parts of triphenylphosphine were added. The surface was modified at 130°C for 40 min. The epoxy groups of ethylene glycol diglycidyl ether reacted with the MAH groups of the star-shaped skeleton to form a bridging. After the reaction was completed, the reaction solution was poured into ice-cold methanol to precipitate, filtered, and vacuum dried at 50°C to obtain a polyethylene material with an initial ring that has introduced double-terminal epoxy groups.

[0076] A polyethylene material with an initial ring was sprayed with an 8% sorbitol ethanol solution and reacted at 150°C and 0.5 MPa for 30 min. After the reaction, the material was extracted with ethanol and dried under vacuum at 60°C to obtain a polyethylene material with an 8-shaped topology.

[0077] The construction of S3 and disulfide bond crosslinking networks yields highly branched polyolefin modifiers.

[0078] 100 parts of polyethylene material with a figure-eight topology, premixed resin, 0.6 parts of crosslinking agent, and 8 parts of SBR pyrolysis product sample 1 were added to a mixer. The mixture was then internally mixed under nitrogen protection, with the temperature controlled at 112℃, the shear rate at 1500 r / min, and the reaction time at 20 min. During the reaction, the premixed resin provided epoxy groups to react with thiols to form dynamic disulfide bonds. After the reaction, the melt was pressed into sheets (approximately 2 mm thick), subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier, denoted as modifier sample 1.

[0079] The premixed resin used was obtained by pre-dispersing 12 parts of epoxy resin and 6 parts of terpene resin at 120℃ for 12 min; the crosslinking agent was glyoxal.

[0080] Example 8

[0081] In this embodiment, a highly branched polyolefin modifier is prepared. The specific process is as follows:

[0082] Simultaneous grafting of S1, maleic anhydride-functionalized star-shaped backbone, and long-chain 1-octene yields a polyethylene material with a star-shaped backbone.

[0083] 100 parts of recycled polyethylene fragments, 18 parts of MAH functionalized skeleton sample, 6 parts of 1-octene, 1 part of initiator, and 0.05 parts of antioxidant were added to a mixer and grafted at 172℃ and 95r / min for 5min. After the reaction, the mixture was granulated by a water-cooled string pelletizer, washed three times with boiling n-hexane, and vacuum dried at 60℃ to obtain a polyethylene material with a star-shaped skeleton.

[0084] The initiator is benzoyl peroxide;

[0085] The antioxidant is tris(2,4-di-tert-butylphenyl) phosphite;

[0086] The recycled polyethylene fragments used were sorted by melt index (MFI) to obtain polyethylene fragments with a concentration of MFI > 10 g / 10 min, and then pretreated by washing with an 8% phosphoric acid solution with an impurity content of 0.18%. The impurities here are the same as those in step S2 of Example 7.

[0087] The introduction of S2, dual-terminal epoxy groups, and figure-eight topology yields a polyethylene material with a figure-eight topology:

[0088] Ten parts of the linker ethylene glycol diglycidyl ether were added to 200 parts of xylene solvent, along with 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1, and 0.3 parts of triphenylphosphine. The surface was modified at 132°C for 35 min. The epoxy groups of ethylene glycol diglycidyl ether reacted with the MAH groups of the star-shaped skeleton to form a bridging reaction. After the reaction was completed, the reaction solution was poured into ice-cold methanol to precipitate, filtered, and dried under vacuum at 50°C to obtain a polyethylene material with an initial ring that has been introduced with double-terminated epoxy groups.

[0089] A polyethylene material with an initial ring was sprayed with a 10% sorbitol ethanol solution and reacted at 148°C and 0.6 MPa for 35 min. After the reaction, the material was extracted with ethanol and dried under vacuum at 60°C to obtain a polyethylene material with an 8-shaped topology.

[0090] The construction of S3 and disulfide bond crosslinking networks yields highly branched polyolefin modifiers.

[0091] 100 parts of polyethylene material with a figure-eight topology, premixed resin, 0.8 parts of crosslinking agent, and 10 parts of SBR pyrolysis product sample 2 were added to a mixer. The mixture was then internally mixed under nitrogen protection, with the temperature controlled at 110℃, the shear rate at 1600 r / min, and the reaction time at 25 min. During the reaction, the premixed resin provided epoxy groups to react with thiols to form dynamic disulfide bonds. After the reaction, the melt was pressed into sheets (approximately 2 mm thick), subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier, denoted as modifier sample 2.

[0092] The premixed resin used was obtained by pre-dispersing 15 parts of epoxy resin and 4 parts of terpene resin at 125℃ for 10 min; the crosslinking agent was glutaraldehyde.

[0093] Example 9

[0094] In this embodiment, a highly branched polyolefin modifier is prepared. The specific process is as follows:

[0095] Simultaneous grafting of S1, maleic anhydride-functionalized star-shaped backbone, and long-chain 1-octene yields a polyethylene material with a star-shaped backbone.

[0096] 100 parts of recycled polyethylene fragments, 12 parts of MAH functionalized skeleton sample, 3 and 4 parts of 1-octene, 0.5 parts of initiator, and 0.15 parts of antioxidant were added to a mixer and grafted at 178℃ and 85r / min for 2min. After the reaction, the mixture was granulated by a water-cooled string pelletizer, washed three times with boiling n-hexane, and vacuum dried at 60℃ to obtain a polyethylene material with a star-shaped skeleton.

[0097] The initiator is benzoyl peroxide;

[0098] The antioxidant is tris(2,4-di-tert-butylphenyl) phosphite;

[0099] The recycled polyethylene fragments used were sorted by melt index (MFI) to obtain polyethylene fragments with a concentration of MFI > 10 g / 10 min, and then pretreated by washing with a 6% phosphoric acid solution with an impurity content of 0.29%. The impurities here are the same as those in step S2 of Example 7.

[0100] The introduction of S2, dual-terminal epoxy groups, and figure-eight topology yields a polyethylene material with a figure-eight topology:

[0101] Ten parts of the linker ethylene glycol diglycidyl ether were added to 300 parts of xylene solvent, along with 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1, and 0.5 parts of triphenylphosphine. The surface was modified at 128°C for 45 min. The epoxy groups of ethylene glycol diglycidyl ether reacted with the MAH groups of the star-shaped skeleton to form a bridging reaction. After the reaction was completed, the reaction solution was poured into ice-cold methanol to precipitate, filtered, and vacuum dried at 50°C to obtain a polyethylene material with an initial ring that has been introduced with double-terminated epoxy groups.

[0102] A polyethylene material with an initial ring was sprayed with a 5% sorbitol ethanol solution and reacted at 152°C and 0.4 MPa for 25 min. During the reaction, the premixed resin provided epoxy groups to react with thiols to form dynamic disulfide bonds. After the reaction, the material was extracted with ethanol and vacuum dried at 60°C to obtain a polyethylene material with an 8-shaped topology.

[0103] The construction of S3 and disulfide bond crosslinking networks yields highly branched polyolefin modifiers.

[0104] 100 parts of polyethylene material with a figure-eight topology, premixed resin, 0.5 parts of crosslinking agent, and 6 parts of SBR pyrolysis product sample 3 were added to a mixer. The mixture was mixed under nitrogen protection, with the temperature controlled at 115℃, the shear rate at 1400 r / min, and the reaction time at 15 min. After the reaction, the melt was pressed into sheets (approximately 2 mm thick), subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier, which was designated as modifier sample 3.

[0105] The premixed resin used was obtained by pre-dispersing 10 parts of epoxy resin and 7 parts of terpene resin at 115℃ for 15 min; the crosslinking agent was paraformaldehyde.

[0106] Comparative Example 1

[0107] In this comparative example, the preparation process of the maleic anhydride-functionalized star-shaped framework was the same as in Example 1. However, the quality standard of the ferrosilicon slag fiber used was different. The ferrosilicon slag fiber used in this comparative example contained 37.2% SiO2, 23.8% CaO, 9.3% MgO, 8.8% Al2O3, 7.1% MnO, 2.3% Fe2O3, 2.5% K2O, 1.8% Na2O, and 1.2% P2O5. Other impurities accounted for 3.0%, and the loss on ignition was 2.9%. MAH functionalized framework reference 1 was thus prepared.

[0108] The specific preparation process of the modifier reference standard is the same as in Example 7, except that in step S1, instead of using MAH functionalized skeleton sample 1, an equal mass of MAH functionalized skeleton reference standard 1 is used. The subsequent process is the same as in Example 7, and modifier reference standard 1 is prepared.

[0109] Comparative Example 2

[0110] In this comparative example, the preparation of the modifier reference standard was carried out using a commercially available MAH grafted polyolefin (specifically, Ricobond 5556, from Xindian Chemical Materials (Shanghai) Co., Ltd.) as the MAH functionalized skeleton reference standard 2.

[0111] The specific preparation process of the modifier reference standard is the same as in Example 7, except that in step S1, instead of using MAH functionalized skeleton sample 1, an equal mass of MAH functionalized skeleton reference standard 2 is used. The subsequent process is the same as in Example 7, and modifier reference standard 2 is prepared.

[0112] Comparative Example 3

[0113] The preparation process of the modifier reference standard in this comparative example is as follows:

[0114] S1. Grafting of maleic anhydride-functionalized star-shaped backbone yields a polyethylene material with a star-shaped backbone:

[0115] 100 parts of recycled polyethylene fragments, 15 parts of MAH functionalized skeleton sample 1, 0.8 parts of initiator, and 0.10 parts of antioxidant were added to a mixer and grafted at 175℃ and 90r / min for 4min. After the reaction, the mixture was granulated by a water-cooled strip pelletizer, washed three times with boiling n-hexane, and vacuum dried at 60℃ to obtain a polyethylene material with a star-shaped skeleton.

[0116] The initiator is dicumyl peroxide;

[0117] The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate];

[0118] The recycled polyethylene fragments used are the same as those in step S1 of Example 7.

[0119] S2, the introduction of dual-terminal epoxy groups and figure-eight topology, yields a polyethylene material with a figure-eight topology: same as step S2 in Example 7.

[0120] S3. Construction of disulfide bond crosslinking network to obtain highly branched polyolefin modifier: Same as step S3 in Example 7, to prepare modifier control 3.

[0121] Comparative Example 4

[0122] The preparation process of the modifier reference standard in this comparative example is as follows:

[0123] S1. Simultaneous grafting of maleic anhydride-functionalized star-shaped backbone and long-chain 1-octene to obtain polyethylene material with star-shaped backbone: same as step S1 in Example 7.

[0124] S2, the introduction of di-terminal epoxy groups, yields a polyethylene material with an initial ring:

[0125] 12 parts of ethylene glycol diglycidyl ether were added to 250 parts of xylene solvent, 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1 were added, and 0.4 parts of triphenylphosphine were added. The surface was modified at 130°C for 40 min. After the reaction was completed, the reaction solution was poured into ice-cold methanol to precipitate, filtered, and dried under vacuum at 50°C to obtain a polyethylene material with an initial ring and introduced with double-terminated epoxy groups.

[0126] The construction of S3 and disulfide bond crosslinking networks yields highly branched polyolefin modifiers.

[0127] 100 parts of polyethylene material with initial rings, premixed resin, 0.6 parts of crosslinking agent, and 8 parts of SBR pyrolysis product sample 1 were added to a mixer. The mixture was stirred under nitrogen protection, with the temperature controlled at 112℃, the shear rate at 1500 r / min, and the reaction time at 20 min. After the reaction, the melt was pressed into tablets (approximately 2 mm thick), subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier, which was designated as modifier reference standard 4.

[0128] The premixed resin used was obtained by pre-dispersing 12 parts of epoxy resin and 6 parts of terpene resin at 120℃ for 12 min; the crosslinking agent was glyoxal.

[0129] Comparative Example 5

[0130] The preparation process of the modifier reference standard in this comparative example is as follows:

[0131] S1. Simultaneous grafting of maleic anhydride-functionalized star-shaped backbone and long-chain 1-octene to obtain polyethylene material with star-shaped backbone: same as step S1 in Example 7.

[0132] S2, the introduction of dual-terminal epoxy groups and figure-eight topology, yields a polyethylene material with a figure-eight topology: same as step S2 in Example 7.

[0133] The construction of S3 and disulfide bond crosslinking networks yields the highly branched polyolefin modifier:

[0134] 100 parts of polyethylene material with a figure-eight topology, 0.6 parts of crosslinking agent, and 8 parts of SBR raw material were added to a mixer and mixed under nitrogen protection. The temperature was controlled at 112℃, the shear rate at 1500 r / min, and the reaction time at 20 min. After the reaction, the melt was pressed into sheets (about 2 mm thick), subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier, which was designated as modifier reference standard 5.

[0135] The SBR raw material used is obtained by soaking styrene-butadiene rubber particles with an average particle size of 1.81 mm in a 5% NaOH solution to remove surface oil, rinsing with water until the washing solution is neutral, and then vacuum drying at 60°C to a moisture content of 0.42%.

[0136] Analysis and Testing

[0137] I. Molecular weight determination

[0138] The molecular weights of modifier samples 1–3 and modifier reference standards 1–3 were determined using a gel permeation chromatography-multi-angle laser light scattering system. Each sample was tested three times, and outliers were removed before the mean was taken. The results are shown in Table 1.

[0139] Table 1: Molecular weight test results

[0140]

[0141]

[0142] As shown in Table 1, the molecular weight distribution of the modifier samples 1-3 of the present invention is greater than 3.5, which is significantly higher than that of all reference samples, directly verifying the tertiary branched structure of the star-shaped framework, figure-eight topology and disulfide bond network of the present invention; the branching factor g' of the modifier samples of the present invention is less than 0.6, further verifying that the samples of the present invention have a highly branched / hyperbranched molecular chain topology.

[0143] II. Performance Verification of Modifiers

[0144] The rheological behavior of modifier samples 1-3 and modifier control samples 1-3 was determined using a dynamic shear rheometer. The tests were conducted according to the asphalt rheological test specifications in GB / T 33528-2017 "Specification for Rheological Performance Testing of Modified Asphalt for Highway". The results are shown in Table 2.

[0145] Table 2: Performance Test Results of Modifier

[0146] Sample number to be tested Complex viscosity (Pa·s) Elastic modulus (unit: kPa) Shear thinning index Modifier Sample 1 15968 126.3 0.38 Modifier Sample 2 15436 123.4 0.42 Modifier Sample 3 15236 121.6 0.45 Modifier Reference Standard 1 1202 58.7 0.61 Modifier Reference Standard 2 853 42.5 0.65 Modifier reference standard 3 9874 89.6 0.55 Modifier Reference Standard 4 3245 75.2 0.58 Modifier reference standard 5 2106 48.6 0.75

[0147] As shown in Table 2, the modifier samples 1-3 of this invention have a complex viscosity > 10 at a low shear rate (0.1 rad / s). 4Pa·s, elastic modulus >10 2 kPa, while the complex viscosity of the reference standard is <10 kPa. 3 Pa·s and elastic modulus <90kPa are characteristics that originate from the entanglement enhancement effect of the star-shaped skeleton and the dynamic cross-linking network of disulfide bonds. Furthermore, because the sample of this invention has highly branched characteristics and a shear thinning index <0.5, it exhibits melt processability and shear sensitivity.

[0148] Application Examples

[0149] I. Application Examples of Direct Conversion Technology

[0150] In this embodiment, according to Table 3, modifier samples 1-3 and modifier reference standard 1 are used in combination with No. 70 road petroleum asphalt (hereinafter referred to as No. 70) and No. 90 road petroleum asphalt (hereinafter referred to as No. 90), respectively. A schematic diagram of the asphalt processing procedure for the direct modification process can be found here. Figure 1 The specific usage method is as follows:

[0151] The base asphalt in the base asphalt storage tank is transferred to the base asphalt heating tank for preheating;

[0152] By mass fraction, modifier samples 1-3, modifier reference 1, and 100 parts of preheated base asphalt were added to the direct-heating asphalt production tank according to the mass ratio. Dynamic stirring and heating were carried out according to the rotation speed in Table 3, and the reaction was maintained for a certain period of time. Since no high-speed shearing was performed and no other additives were required during use, the modified asphalt obtained can be called direct-heating modified asphalt. Specific sample names are shown in Table 3.

[0153] Table 3: Comparison of the combined use of different modifiers and different base asphalts

[0154]

[0155] II. Examples of Traditional Process Application

[0156] Because modifier reference standards 2-5 cannot directly modify asphalt, different additives and stabilizers need to be added based on the structural characteristics of the modifier, following the traditional asphalt production process. (See the schematic diagram of the traditional asphalt processing process.) Figure 2 The specific process is as follows:

[0157] 1) Premixed modification:

[0158] According to Table 4, 30 parts of base asphalt were gradually heated through a zero-level tank and a heat exchanger, then entered an additive premixing tank, where additive A was added and mixed. The mixture was then entered a stabilizer premixing tank and mixed with the stabilizer, before entering the asphalt production tank to obtain the corresponding pre-modified asphalt.

[0159] Table 4: Traditional Asphalt Production Process Parameters and Materials Used (Premixing and Modification Steps)

[0160]

[0161] 2) Main reaction stage:

[0162] According to Table 5, 70 parts of base asphalt, the pre-modified asphalt obtained in step 1), 5 parts of modifier (the modifier numbers are shown in Table 5), and rubber powder and additive B, with or without addition according to Table 5, are sequentially added to the asphalt production tank. After stirring, developing, and reacting according to the parameters recorded in Table 6, the stabilizer premixed asphalt is added again, and the mixture is stirred evenly to obtain the semi-finished asphalt. The rubber powder used in this invention is 20-mesh tire rubber powder, which is treated with NaOH solution before use.

[0163] Table 5: Traditional Asphalt Production Process Parameters and Materials Used (Main Reaction Stage, Part 1)

[0164]

[0165] Table 6: Traditional Asphalt Production Process Parameters and Materials Used (Main Reaction Stage, Part 2)

[0166]

[0167] 3) Initial cutting:

[0168] According to the process parameters recorded in Table 7, the initial shearing is carried out, and the semi-finished asphalt is transported to the asphalt turnover tank for temporary storage after initial shearing by shearing machine A.

[0169] 4) Secondary fine shearing and secondary development:

[0170] According to the process parameters recorded in Table 7, the asphalt reference sample was prepared by performing a second fine shearing in shearing machine B and then transferring it to a development tank for a second development.

[0171] Table 7: Traditional Asphalt Production Process Parameters and Materials Used (Primary Shearing Step and Secondary Fine Shearing and Secondary Development Step)

[0172]

[0173] The asphalt samples 1-8 and asphalt reference standards 1-15 prepared above were subjected to asphalt performance tests, specifically including:

[0174] (I) High-temperature stability test

[0175] The softening point was determined according to standard GB / T 4507 "Determination of softening point of asphalt (ring and ball method)"; the dynamic viscosity at 60℃ was determined according to the test method of asphalt rotational viscosity test T0625-2011 in standard JT / T2012 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering". The results are shown in Table 8.

[0176] (II) Low-temperature crack resistance test

[0177] The ductility at 5℃ was determined according to standard GB / T 4508 "Determination of Ductility of Asphalt"; according to standard

[0178] JT / T 2012 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" specifies T0627-2011 Asphalt Flexural Creep Stiffness Test to determine flexural creep stiffness (abbreviated as BBR). After recording the creep deformation curve within 60s, the slope of the logarithmic time axis of the creep curve is calculated, i.e., the m value. The results are shown in Table 8.

[0179] (III) Storage Stability Test

[0180] According to standard JT / T 2012 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering"

[0181] T0661-2011 Polymer-modified asphalt segregation test, measuring the difference in segregation softening point (48h, 163℃), the results are shown in Table 8.

[0182] (iv) Temperature sensitivity evaluation

[0183] The penetration was determined according to the standard GB / T 4509 "Test Method for Asphalt Penetration" (25℃) and the penetration index was calculated according to the requirements of T0604-2011 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" JT / T 2012. The results are shown in Table 8.

[0184] Table 8: Summary of Test Results of Asphalt Samples and Asphalt Reference Standards

[0185]

[0186]

[0187] As shown in Table 8, the softening point and dynamic viscosity at 60℃ of the asphalt samples 1-8 prepared by this invention are significantly higher than those of all control samples, indicating that the asphalt samples prepared by this invention have excellent high-temperature deformation resistance. This is closely related to the star-shaped skeleton entanglement enhancement effect and the dynamic cross-linking network of disulfide bonds of the modifier of this invention. That is, the star-shaped skeleton can increase the molecular chain entanglement density, and the disulfide bonds can reversibly break / reorganize at high temperatures to dissipate stress, thus synergistically inhibiting asphalt flow.

[0188] The 5°C ductility and BBR m value of the asphalt samples 1-8 of this invention are significantly better than all control samples, indicating that the asphalt samples prepared by this invention exhibit outstanding low-temperature flexibility and stress relaxation ability. This should be attributed to the figure-eight topology and plasticizing effect of the SBR pyrolysis products of this invention. The figure-eight topology disperses local stress through cyclic crosslinking points, while the flexible segments in the SBR pyrolysis products enhance molecular chain mobility, resulting in an m value > 0.33, which meets the requirement of ≥ 0.3 for Superior Performing Asphalt Pavements.

[0189] The segregation softening point difference and penetration index (PI) of the asphalt samples 1-8 of this invention are superior to all control samples, indicating that the asphalt samples of this invention have better compatibility and lower temperature sensitivity. This should be attributed to the enhanced interfacial bonding between the maleic anhydride polar groups and the asphalt components, the star-shaped figure-eight topological inhibitory phase formation, which makes the segregation softening point difference <2.5℃ (JTG F40-2004 "Technical Specification for Construction of Highway Asphalt Pavement" requires ≤2.5℃), and the weakening of temperature dependence by the topological cross-linking network.

[0190] In summary, the modifier prepared by this invention utilizes a three-tiered structural design—a star-shaped skeleton providing rigid support, a figure-eight topology for stress dispersion, and a disulfide bond network for dynamic healing—to not only solve the technical challenges of high and low temperature performance contradictions and storage segregation in traditional recycled polyethylene modified asphalt, but also achieves asphalt with comprehensive performance surpassing that of SBS modified asphalt. Furthermore, it simultaneously enables direct asphalt modification, producing a product through mixed modification. This process exhibits good compatibility with conventional base asphalt and a simple formulation, eliminating the need for pre-preparation and long-distance transportation. It boasts engineering advantages such as extremely simple process flow, zero storage and transportation costs, flexible additive formulation, and optimized full-cycle costs.

[0191] Furthermore, the asphalt sample 3 in this invention, as a type of direct-modified rubber powder asphalt, was successfully applied in June 2025 to the China Construction Road & Bridge Group's Selangor-Baningbang Toll Road Project Section 3 in Indonesia. The application effect was good, verifying the advanced nature and practicality of the high-branched polyolefin modifier and the corresponding direct-modified rubber powder asphalt technology prepared in this invention.

[0192] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A highly branched polyolefin modifier, characterized in that, The modifier comprises a main material consisting of a maleic anhydride-functionalized star-shaped framework and a figure-eight topology grafted onto a polyethylene matrix, and disulfide bond crosslinking network structural units running through the main structure. The maleic anhydride-functionalized star-shaped framework uses silicomanganese slag fiber as its core, with polyethylene glycol methacrylate arm layers grafted onto its surface. The maleic anhydride functional layer is chemically grafted onto the arm layer surface of the star-shaped framework. The figure-eight topology bridges adjacent polyolefin chains with a dual-terminal epoxy group linker and forms a closed-loop network through sorbitol crosslinking. The polyolefin chain and the maleic anhydride functional layer are bridged by 1-octene; the disulfide crosslinking network is a crosslinking network constructed in the polyethylene matrix by a premixed resin of epoxy resin and terpene resin and SBR pyrolysis product under the action of an aldehyde crosslinking agent; the silicomanganese slag fiber includes 38% to 41% SiO2, 25% to 27% CaO, 6.0% to 8.0% MnO, and ≤2.5% alkali metal oxides by mass; the double-terminated epoxy group linker is ethylene glycol diglycidyl ether.

2. The modifier according to claim 1, characterized in that, The preparation of the star-shaped framework includes: soaking ferrosilicon manganese slag fibers in citric acid ethanol solution for 1.5h to 2.5h, then immersing them in a nano-bentonite pregel suspension, and treating them at a constant temperature of 58℃ to 62℃ for 45min to 75min to obtain a ferrosilicon manganese slag fiber core, referred to as the SMF core; activating the SMF core with triethylamine ethanol solution, then spraying it with trimethylolpropane tris(3-mercaptopropionic acid) ester or pentaerythritol tetra(3-mercaptopropionic acid) ester to form a thiolized interface; coating it with a polyethylene glycol methacrylate solution containing a photoinitiator at 365nm. The mercapto-alkene click reaction was completed by UV irradiation for 25-35 seconds to obtain the basic star-shaped framework. The basic star-shaped framework, maleic anhydride, dicumyl peroxide, and styrene were added to a torque rheometer at a mass ratio of 100:15-20:0.8-1.2:4-6. The mixture was melt-blended at 175-180℃ and 55-65 r / min for 5-10 minutes. The temperature was then raised to 184-187℃ and the rotation speed was increased to 90-95 r / min. The reaction was continued for 3-5 minutes. The grafting peak value was monitored by torque mutation to determine the reaction endpoint. The reaction was terminated by liquid nitrogen quenching. After precipitation and purification, the maleic anhydride-functionalized star-shaped framework was obtained.

3. The modifier according to claim 2, characterized in that, The pH of the citric acid ethanol solution is 4.3–4.8; the nano-bentonite pregel suspension is obtained by adding nano-bentonite to water at 25°C–35°C at a mass ratio of 4%–6%, dispersing at a high-speed shear rate of 1500–2000 r / min for 25–35 min, and allowing it to stand for 8–12 h; the triethylamine ethanol solution has a triethylamine mass concentration of 0.5%–1.5%, and the triethylamine ethanol solution is activated by stirring at 38°C–42°C for 8–12 min; the polyethylene glycol containing the photoinitiator… In the methacrylate solution, the mass concentration of the photoinitiator is 0.5% to 1.0%, and the number-average molecular weight of the polyethylene glycol methacrylate used is in the range of 650 to 1000. The photoinitiator is any one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, or 2-hydroxy-2-methyl-1-phenyl-1-propanone. The grafting peak value is monitored by torque mutation, and the standard for determining the reaction endpoint is to monitor the torque change in real time by a torque rheometer. When the torque value increases by ≥15% within 30 seconds, the reaction endpoint is determined.

4. The modifier according to claim 1, characterized in that, The preparation process of the SBR pyrolysis product involves mixing and pyrolyzing SBR raw material with dicumyl peroxide and naphthenic oil at 180℃~200℃ for 15min~20min, with the mass ratio of SBR raw material, dicumyl peroxide and naphthenic oil being 100:1.0~1.5:5~10; after filtration through a 200-mesh sieve, it is diluted with xylene at a ratio of 1:1; the SBR raw material is styrene-butadiene rubber particles with a particle size ≤2mm that have been treated with NaOH solution.

5. A method for preparing a highly branched polyolefin modifier, used to prepare the modifier as described in any one of claims 1-4, characterized in that, Specifically, it includes: Simultaneous grafting of S1, maleic anhydride-functionalized star-shaped backbone and long-chain 1-octene yields a polyethylene material with a star-shaped backbone. The introduction of S2, dual-terminal epoxy groups, and figure-eight topology yields a polyethylene material with a figure-eight topology; the construction of S3, a disulfide crosslinking network, yields the highly branched polyolefin modifier.

6. The preparation method according to claim 5, characterized in that, By mass, step S1 specifically involves: adding 100 parts of recycled polyethylene fragments, 12-18 parts of maleic anhydride-functionalized star-shaped backbone, 4-6 parts of 1-octene, 0.5-1 parts of initiator, and 0.05-0.15 parts of antioxidant to a mixer; grafting is performed at 172-178°C and 85-95 r / min for 2-5 minutes; after the reaction, granulation is carried out; and the product is washed with n-hexane and dried to obtain a polyethylene material with a star-shaped backbone. The initiator is any one of dicumyl peroxide, benzoyl peroxide, or di-tert-butyl peroxide; the antioxidant is any one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl) phosphite, or 2,6-di-tert-butyl-p-cresol; the recovered polyethylene fragments are pretreated by melt index sorting (MFI > 10 g / 10 min) and washing with a 6%–8% phosphoric acid solution, with an impurity content < 0.3%.

7. The preparation method according to claim 5, characterized in that, The S2 step, by mass fraction, is as follows: 10-15 parts of ethylene glycol diglycidyl ether are added to 200-300 parts of xylene solvent, along with 10 parts of the polyethylene material with a star-shaped skeleton obtained in step S1, and 0.3-0.5 parts of triphenylphosphine. Surface modification is carried out at 128-132°C for 35-45 minutes. After the reaction, the reaction solution is poured into ice-cold methanol for precipitation, filtration, and drying to obtain a polyethylene material with an initial ring and introduced double-terminal epoxy groups. The polyethylene material with the initial ring is then sprayed with a 5%-10% sorbitol ethanol solution and reacted at 148-152°C and 0.4-0.6 MPa for 25-35 minutes. After the reaction, it is extracted with ethanol and dried to obtain a polyethylene material with a figure-eight topology.

8. The preparation method according to claim 5, characterized in that, By mass, step S3 specifically involves: adding 100 parts of polyethylene material with a figure-eight topology, premixed resin, 0.5 to 0.8 parts of crosslinking agent, and 6 to 10 parts of SBR pyrolysis product to an internal mixer; mixing under nitrogen protection; controlling the temperature at 110°C to 115°C, the shear rate at 1400 r / min to 1600 r / min, and the reaction time at 15 to 25 minutes; after the reaction, the melt is pressed into sheets, subjected to liquid nitrogen brittle fracture, and pulverized through an 80-mesh sieve to obtain a highly branched polyolefin modifier; the premixed resin is obtained by pre-dispersing 10 to 15 parts of epoxy resin and 4 to 7 parts of terpene resin at 115°C to 125°C for 10 to 15 minutes; the crosslinking agent is any one of glyoxal, glutaraldehyde, or paraformaldehyde.

9. A direct-to-asphalt conversion method, characterized in that, The highly branched polyolefin modifier as described in claim 1 and the base asphalt are added to a direct-heating asphalt production tank at a mass ratio of 4-6:

100. The mixture is dynamically stirred at a speed of 10-30 r / min and simultaneously heated to 180-190°C. The temperature is then maintained at this temperature for 60-120 minutes to complete the modification reaction. The mixture can be used directly after the reaction.

10. The direct-to-asphalt conversion according to claim 9, characterized in that, The base asphalt includes No. 70 road petroleum asphalt or No. 90 road petroleum asphalt; during the modification reaction process, rubber powder may also be added, and the mass ratio of the rubber powder to the base asphalt is 15-25:100.

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