A composite warm mix material based on catalytic pyrolysis products of waste polyolefins and its application

Abstract

The present invention discloses a composite warm mix material based on the catalytic cracking products of waste polyolefins and its application. The composite warm mix material is composed of cracked wax and carbon nanotube-montmorillonite hybrid material. The cracked wax is obtained by catalytic cracking of waste polyolefins, and the carbon nanotube-montmorillonite hybrid material is obtained by thermally cracking waste polyolefins as a carbon source to generate carbon nanotubes on the surface of montmorillonite. In the composite warm mix material provided by the present invention, the cracked wax has a viscosity-reducing effect on asphalt, while the carbon nanotube-montmorillonite hybrid material can construct a three-dimensional network in asphalt through the interlayer confinement effect of montmorillonite and the interconnection between carbon nanotubes, and improve the interfacial compatibility between the filler and the asphalt matrix, enhancing the low-temperature toughening performance of the warm mix asphalt composite material. At the same time, the composite warm mix material of the present invention is derived from waste polyolefins, which helps to reduce white pollution and make up for the defects such as poor low-temperature performance and insufficient high-temperature rutting resistance of warm mix asphalt materials.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer composite materials, and particularly relates to a composite warm mix material based on the catalytic cracking products of waste polyolefins and its application. Background Art

[0002] In traditional asphalt road construction, hot mix asphalt mixture (HMA) is used, which can build a road surface with stable performance. However, it needs to be constructed under high temperature conditions (about 180°C), which will release toxic gases and cause harm to construction workers, and also cause asphalt pavement oxidation and a large amount of energy consumption. The development of warm mix asphalt mixture (WMA) effectively solves these problems. By adding a warm mix additive to the asphalt composite material, it can achieve the purpose of saving energy, reducing asphalt oxidation and the emission of toxic gases during the construction process, and reducing the total cost by lowering the production temperature during mixing. The reuse of waste polyethylene has become a current hot topic, and scientists are working hard to transform waste polyethylene into high-value-added products, such as waxy warm mix additives, carbon nanotubes, light oil, etc.

[0003] However, the use of organic waxy warm mix additives will damage the low-temperature performance of the asphalt composite material, which is not conducive to the use of warm mix additives in cold regions. Therefore, in order to enhance the low-temperature performance of warm mix asphalt composite materials, some asphalt low-temperature toughening agents are usually added. Currently, commonly used ones include polyurethane, montmorillonite, rubber, and light oil, etc. Patent CN201810986175.2 "Method for preparing a low-temperature asphalt modifier and modified low-temperature asphalt" mixes naphthenic oil, cottonseed oil, dodecyl mercaptan, thermoplastic polyurethane elastomer rubber particles, and polyethylene particles evenly and then adds them to the asphalt composite material to prepare a low-temperature toughened asphalt composite material. Although this method prepares a low-temperature asphalt modifier, the preparation method is complex and not suitable for large-scale application, and the high-temperature performance of the warm mix asphalt composite material is unknown. Patent CN201710179263.7 "A low-temperature resistant asphalt waterproof coating and its preparation method" adds modified auxiliaries, modified plant ash, branched starch, sulfur powder, natural rubber, antioxidant, etc. to silicone rubber to prepare a low-temperature resistant asphalt waterproof coating material. However, the addition amount of modified plant ash in this method is very high, the preparation is complex, and only the low-temperature performance of the asphalt composite material is tested, and the high-temperature performance of the asphalt composite material is not detected. Therefore, how to ensure that the warm mix additive reduces the viscosity of the asphalt composite material while meeting its required mechanical properties and low-temperature performance, and at the same time the preparation process is simple, is of great significance for the popularization of warm mix asphalt technology and the reuse of waste polyethylene. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a composite warm mix material based on the catalytic cracking products of waste polyolefins and its application, aiming to improve the low-temperature toughening performance of warm mix asphalt composite materials.

[0005] To achieve the object, the present invention adopts the following technical solutions:

[0006] A composite warm mix material based on the catalytic cracking products of waste polyolefins, characterized in that: the composite warm mix material is composed of cracked wax and carbon nanotube-montmorillonite hybrid material; the cracked wax is obtained by catalytic cracking of waste polyolefins; the carbon nanotube-montmorillonite hybrid material is obtained by pyrolyzing waste polyolefins as a carbon source to generate carbon nanotubes on the surface of montmorillonite.

[0007] Further, the waste polyolefins are derived from one or any combination of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, polystyrene, polyethylene terephthalate, and polyvinyl chloride.

[0008] Further, the preparation method of the cracked wax is: kneading the waste polyolefins and the catalyst in a twin-screw extruder, and then crushing the extruded product with a crusher to obtain a composite of the waste polyolefins and the catalyst; putting the composite of the waste polyolefins and the catalyst into a tubular furnace and heating it in an inert gas atmosphere to obtain the cracked wax.

[0009] Preferably: the mass ratio of the catalyst to the waste polyolefins is 1:5-20; the heating temperature is 350-450 °C, the heat preservation time is 1-2 h, and the heating rate is 5-15 °C / min.

[0010] Preferably: the catalyst is at least one of molecular sieve and zeolite.

[0011] Preferably: the molecular weight of the cracked wax is 800-2200.

[0012] Further, the preparation method of the carbon nanotube-montmorillonite hybrid material is: preparing nickel / montmorillonite by cation exchange of nickel nitrate and montmorillonite; kneading the nickel / montmorillonite and the waste polyolefins in a twin-screw extruder, and then crushing the extruded product with a crusher to obtain a composite of the waste polyolefins and the nickel / montmorillonite; putting the composite of the waste polyolefins and the nickel / montmorillonite into a tubular furnace and heating it in an inert gas atmosphere to obtain the carbon nanotube-montmorillonite hybrid material.

[0013] Preferably: the mass ratio of nickel nitrate to montmorillonite is 1:1-10; the mass ratio of nickel / montmorillonite to waste polyolefins is 1:90-100; the heating temperature is 650-900 °C, the heat preservation time is 1-2 h, and the heating rate is 5-15 °C / min.

[0014] Further, the preparation of the above-mentioned cracked wax and carbon nanotube-montmorillonite hybrid material can be carried out separately, or by connecting three tubular furnaces as reaction chambers (such as Figure 1Simultaneous preparation is carried out as shown. The inert gas sequentially flows through the first reaction chamber, the second reaction chamber, and the third reaction chamber. In the first reaction chamber, a composite of waste polyolefin and a catalyst is placed for preparing cracked wax; in the second reaction chamber, a composite of waste polyolefin and nickel / montmorillonite is placed for preparing carbon nanotube-montmorillonite hybrid material; in the third reaction chamber, only nickel / montmorillonite is placed for collecting the carbon source that is not completely reacted in the first reaction chamber and the second reaction chamber (the unreacted polyolefin and its cracked products flow with the inert gas), and the carbon nanotube-montmorillonite hybrid material is obtained. This method can achieve the efficient utilization of inert gas and waste polyolefin, saving costs.

[0015] Furthermore, in the composite warm mix material, the mass ratio of cracked wax to carbon nanotube-montmorillonite hybrid material is 1:0.5 - 3.

[0016] Furthermore, when the composite warm mix material is made by mixing cracked wax and carbon nanotube-montmorillonite hybrid material, the two can be directly physically mixed evenly, or the mixture of the two can be further granulated by an extruder to fuse the two together to form a masterbatch-like composite warm mix material.

[0017] The composite warm mix material based on the catalytic cracking products of waste polyolefin prepared by the above method of the present invention can be directly used in the construction of asphalt pavements to enhance the low-temperature performance of asphalt pavements and increase the scope of warm mix asphalt pavement construction. The specific method can be: adding the composite warm mix material to asphalt through melt blending and high-speed shearing to obtain a warm mix asphalt material, and the mass ratio of the composite warm mix material to asphalt is 0.01 - 0.05:1.

[0018] Furthermore, the asphalt is one or any combination of 70#, 90#, SBS modified asphalt, and high-viscosity asphalt.

[0019] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0020] 1. The present invention first prepares low-molecular-weight cracked wax and low-cost carbon nanotubes by catalytic cracking of high-molecular-weight waste polyolefin, and the carbon nanotubes are in-situ grown on the surface of nickel-containing montmorillonite using thermally cracked waste polyolefin as the carbon source; then the carbon nanotube-montmorillonite hybrid material is mixed with cracked wax to obtain a composite warm mix material; finally, the composite warm mix material and asphalt are blended to obtain a warm mix asphalt material. The cracked wax in the composite warm mix material provided by the present invention has a viscosity-reducing effect on asphalt, while the carbon nanotube-montmorillonite hybrid material can construct a three-dimensional network in asphalt through the interlayer confinement effect of montmorillonite and the interconnection between carbon nanotubes, and improve the interfacial compatibility between the filler and the asphalt matrix, improving the low-temperature toughening performance of the warm mix asphalt composite, and can be used for the paving of asphalt pavements in cold regions. The composite warm mix material of the present invention makes up for the defects of existing warm mix asphalt materials such as poor low-temperature performance and insufficient high-temperature rutting resistance.

[0021] 2. The composite warm mix material of the present invention is derived from waste polyolefins, which helps to reduce white pollution, realizes the concept of energy conservation and environmental protection, and greatly reduces the production cost.

[0022] 3. The cracked wax of the present invention can reduce the viscosity of the asphalt composite material and increase the rutting resistance of the asphalt composite material. The carbon nanotubes of the present invention grow in-situ in montmorillonite, realizing the uniform growth of carbon nanotubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the synchronous preparation of cracked wax and carbon nanotube-montmorillonite hybrid material by connecting three tubular furnaces as reaction chambers according to the present invention.

[0024] Figure 2 It is an SEM image of the carbon nanotube-montmorillonite composite material prepared in Example 1 of the present invention, where (a) and (b) correspond to different magnifications.

[0025] Figure 3 It is a TEM image of the carbon nanotube-montmorillonite composite material prepared in Example 1 of the present invention, where (a) and (b) correspond to different magnifications.

[0026] Figure 4 It is the high-temperature performance and low-temperature performance of the asphalt composite materials obtained in Examples 1-5 and Comparative Example 1 of the present invention, where (a) and (b) are phase angle comparisons, (c) and (d) are high-temperature complex shear modulus and high-temperature rutting factor respectively, and (e) and (f) are low-temperature complex shear modulus and low-temperature rutting factor respectively.

[0027] Figure 5 It is the low-temperature performance of the asphalt composite materials obtained in Example 4 and Comparative Examples 2-4 of the present invention, where (a) and (b) are low-temperature complex shear modulus and low-temperature rutting factor respectively. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The embodiments of the present invention will be described in detail below. The embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0029] Example 1

[0030] This example provides a preparation method and application of a composite warm mix material based on the catalytic cracking product of waste polyolefins, including the following steps:

[0031] 1. Add 5 g of ZSM zeolite (Adamas-beta Chemical Reagents Co., Ltd) and 50 g of waste polyethylene (Yixian Yuexin Plastic Industry Co., Ltd) into a mixer for mixing. The rotation speed of the mixer is 40 r / min, the mixing temperature is 170 °C, and the mixing time is 10 min. Then, crush the extruded product with a crusher to obtain a composite of waste polyolefin and catalyst.

[0032] Put the composite of waste polyolefin and catalyst into a quartz boat, and then place the quartz boat into a tube furnace. First, introduce argon for 30 min to exhaust the air in the tube furnace. Heat it to 380 °C at a heating rate of 10 °C / min in an argon atmosphere and keep it for 2 h. Wait for the tube furnace to cool to room temperature, and take out the prepared cracked wax.

[0033] 2. Weigh 1 g of sodium montmorillonite (Zhejiang Fenghong New Materials Co., Ltd) and add it to 200 mL of deionized water. Stir magnetically for 1 h, and then sonicate for 4 h. Dissolve 1.05 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 10 mL of deionized water. Subsequently, pour the nickel nitrate solution into the sodium montmorillonite suspension and stir for impregnation for 24 h. After filtration at the end of impregnation, dry the solid at 100 °C, then grind the sample into powder in a mortar and pass through a 200-mesh sieve. Then, add the catalyst precursor powder into a quartz boat, and place the quartz boat into a tube furnace. First, introduce argon into the tube furnace for 30 min (to exhaust the air in the tube), then raise the calcination temperature to 500 °C at a heating rate of 5 °C / min and keep it for 3 h. Wait for the tube furnace to cool after calcination is completed, take out the quartz boat cooled to room temperature, and take out the prepared nickel / montmorillonite catalyst.

[0034] Weigh 0.1 g of nickel / montmorillonite catalyst and 10 g of polyethylene, mix them evenly, and then add them into a mixer for mixing. The rotation speed of the mixer is 40 r / min, the mixing temperature is 170 °C. After the mixing torque curve is flat, continue mixing for 10 min and then discharge the material. Grind the mixed product with a high-speed multi-functional grinder into powder as much as possible for later calcination to obtain a composite of waste polyolefin and nickel / montmorillonite.

[0035] Put the composite of waste polyolefin and nickel / montmorillonite into a quartz boat, and then place the quartz boat into a tube furnace. First, introduce argon for 30 min to exhaust the air in the tube furnace. Heat it to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and keep it for 2 h. Wait for the tube furnace to cool to room temperature, take out the obtained black powdery solid to get a carbon nanotube-montmorillonite hybrid material, marked as CNTs-MMT.

[0036] 3. Weigh 1.5 parts of cracked wax and 1.5 parts of carbon nanotube-montmorillonite hybrid material and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145°C, wait until the asphalt is completely melted, use a high-speed shearer to shear, the rotation speed of the shearer is 3000 rpm, and the shearing time is 30 min. After shearing, pour it into a silicone mold while it is hot to obtain the carbon nanotube-montmorillonite low-temperature toughened warm mix asphalt composite material.

[0037] Example 2

[0038] This example provides a preparation method and application of a composite warm mix material based on the catalytic cracking product of waste polyolefins, including the following steps:

[0039] 1. Add 5 g of MCM molecular sieve (Adamas-beta Chemical Reagents Co., Ltd) and 50 g of waste polyethylene (Yixian Yuexin Plastic Industry Co., Ltd) into a mixer for mixing. The rotation speed of the mixer is 40 r / min, the mixing temperature is 170°C, and the mixing time is 10 min. Then, use a crusher to crush the extruded product to obtain a composite of waste polyolefins and catalysts.

[0040] Put the composite of waste polyolefins and catalysts into a quartz boat, and then place the quartz boat into a tubular furnace. First, introduce argon for 30 min to exhaust the air in the tubular furnace. Heat it up to 380°C at a heating rate of 10°C / min in an argon atmosphere and keep it for 2 h. Wait for the tubular furnace to cool down to room temperature, and take out the prepared cracked wax.

[0041] 2. Weigh 1 g of sodium-based montmorillonite (Zhejiang Fenghong New Materials Co., Ltd) and add it to 200 mL of deionized water, stir magnetically for 1 h, and then ultrasonically for 4 h. Dissolve 1.05 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 10 mL of deionized water. Then pour the nickel nitrate solution into the sodium-based montmorillonite suspension and stir for impregnation for 24 h. After impregnation, filter, dry the solid at 100°C, then grind the sample into powder in a mortar and pass through a 200-mesh sieve. Then add the catalyst precursor powder into a quartz boat, and place the quartz boat into a tubular furnace. First, introduce argon into the tubular furnace for 30 min (to exhaust the air in the tube), then raise the calcination temperature to 500°C at a heating rate of 5°C / min, and keep it for 3 h. After calcination, wait for the tubular furnace to cool down, take out the quartz boat cooled to room temperature, and take out the prepared nickel / montmorillonite catalyst.

[0042] Weigh 0.1 g of nickel / montmorillonite catalyst and 10 g of polyethylene, mix them evenly, and then add them to a mixer for mixing. The mixer rotates at 40 r / min and the mixing temperature is 170 °C. After the mixing torque curve becomes flat, continue mixing for 10 min and then discharge the material. Grind the mixed product with a high-speed multi-functional grinder into powder as much as possible for later calcination to obtain a composite of waste polyolefin and nickel / montmorillonite.

[0043] Add the composite of waste polyolefin and nickel / montmorillonite to a quartz boat, and then place the quartz boat into a tube furnace. First, introduce argon for 30 min to exhaust the air in the tube furnace. Heat it to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and hold for 2 h. Wait for the tube furnace to cool to room temperature, take out the obtained black powdery solid to obtain a carbon nanotube-montmorillonite hybrid material, marked as CNTs-MMT.

[0044] 3. Weigh 1.5 parts of cracked wax and 1.5 parts of carbon nanotube-montmorillonite hybrid material and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, use a high-speed shearer to shear, the shearer rotates at 3000 rpm and the shear time is 30 min. After shearing, pour it into a silicone mold while it is hot to obtain a carbon nanotube-montmorillonite low-temperature toughened warm mix asphalt composite material.

[0045] Example 3

[0046] This example provides a preparation method and application of a composite warm mix material based on the catalytic cracking product of waste polyolefin, including the following steps:

[0047] 1. Add 5 g of USY zeolite (Adamas-beta Chemical Reagents Co., Ltd) and 50 g of waste polyethylene (Yiwu Yuexin Plastic Industry Co., Ltd) to a mixer for mixing. The mixer rotates at 40 r / min and the mixing temperature is 170 °C, and the mixing time is 10 min. Then crush the extruded product with a crusher to obtain a composite of waste polyolefin and catalyst.

[0048] Add the composite of waste polyolefin and catalyst to a quartz boat, and then place the quartz boat into a tube furnace. First, introduce argon for 30 min to exhaust the air in the tube furnace. Heat it to 380 °C at a heating rate of 10 °C / min in an argon atmosphere and hold for 2 h. Wait for the tube furnace to cool to room temperature, and take out the obtained cracked wax.

[0049] 2. Weigh 1 g of sodium-based montmorillonite (Zhejiang Fenghong New Materials Co., Ltd.) and add it to 200 mL of deionized water. Stir magnetically for 1 h, and then sonicate for 4 h. Dissolve 1.05 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) in 10 mL of deionized water. Subsequently, pour the nickel nitrate solution into the sodium-based montmorillonite suspension and stir for impregnation for 24 h. After filtration at the end of impregnation, dry the solid at 100 °C, and then grind the sample into powder in a mortar and pass through a 200-mesh sieve. Then add the catalyst precursor powder into a quartz boat, and place the quartz boat into a tube furnace. First, pass argon gas through the tube furnace for 30 min (to remove the air in the tube), then raise the calcination temperature to 500 °C at a heating rate of 5 °C / min and hold for 3 h. After the calcination is completed, wait for the tube furnace to cool down, take out the quartz boat cooled to room temperature, and take out the prepared nickel / montmorillonite catalyst.

[0050] Weigh 0.1 g of nickel / montmorillonite catalyst and 10 g of polyethylene, mix the two evenly, and then add them to a mixer for mixing. The rotation speed of the mixer is 40 r / min, and the mixing temperature is 170 °C. After the mixing torque curve becomes flat, continue mixing for 10 min and then discharge the material. Grind the mixed product with a high-speed multifunctional grinder into powder as much as possible for later calcination to obtain a composite of waste polyolefin and nickel / montmorillonite.

[0051] Add the composite of waste polyolefin and nickel / montmorillonite into a quartz boat, and then place the quartz boat into a tube furnace. First, pass argon gas through for 30 min to exhaust the air in the tube furnace. Heat it to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and hold for 2 h. Wait for the tube furnace to cool down to room temperature, take out the obtained black powdery solid, and obtain a carbon nanotube-montmorillonite hybrid material, marked as CNTs-MMT.

[0052] 3. Weigh 1.5 parts of cracked wax and 1.5 parts of carbon nanotube-montmorillonite hybrid material and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, and wait until the asphalt is completely melted. Use a high-speed shearer to shear it. The rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing is completed, pour it into a silica gel mold while it is hot to obtain a carbon nanotube-montmorillonite low-temperature toughened warm mix asphalt composite material.

[0053] Example 4

[0054] This example provides a preparation method and application of a carbon nanotube-montmorillonite composite warm mix material based on the catalytic cracking of waste polyolefin:

[0055] Weigh 1 part of the cracked wax prepared in Example 1 and 2 parts of the carbon nanotube-montmorillonite hybrid material prepared in Example 1 and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, use a high-speed shearer to shear, the rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing, pour it into a silicone mold while it is hot to obtain the carbon nanotube-montmorillonite composite warm mix asphalt material.

[0056] Example 5

[0057] This example provides a preparation method and application of a carbon nanotube-montmorillonite composite warm mix material based on catalytic cracking of waste polyolefins:

[0058] Weigh 2 parts of the cracked wax prepared in Example 1 and 1 part of the carbon nanotube-montmorillonite hybrid material prepared in Example 1 and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, use a high-speed shearer to shear, the rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing, pour it into a silicone mold while it is hot to obtain the carbon nanotube-montmorillonite composite warm mix asphalt material.

[0059] Comparative Example 1

[0060] Weigh 100 parts of 70# asphalt, heat it up to 145 °C, then use a high-speed shearer to shear, the shearing rate is 3000 rpm and the shearing time is 30 min. After shearing, pour it into a silicone mold while it is hot to obtain the asphalt material.

[0061] Comparative Example 2

[0062] Weigh 0.1 g of nickel nitrate catalyst and 10 g of polyethylene, mix the two evenly, and then add them to a mixer for mixing. The rotation speed of the mixer is 40 r / min and the mixing temperature is 170 °C. After the mixing torque curve is flat, continue mixing for 10 min and then discharge the material. Grind the mixed product into powder as much as possible with a high-speed multi-functional grinder for later calcination to obtain a composite of waste polyolefins and nickel nitrate.

[0063] Add the composite of waste polyolefins and nickel nitrate to a quartz boat, then place the quartz boat in a tubular furnace, first introduce argon for 30 min to exhaust the air in the tubular furnace. Heat it up to 800 °C at a heating rate of 5 °C / min in an argon atmosphere and hold for 2 h. Wait for the tubular furnace to cool to room temperature, take out the obtained black powdery solid to obtain carbon nanotubes.

[0064] Weigh 1 part of the cracked wax prepared in Example 1 and 2 parts of carbon nanotubes and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, and use a high-speed shearer to shear. The rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing is completed, pour it into a silica gel mold while it is hot to obtain a warm mix asphalt composite material.

[0065] Comparative Example 3

[0066] Weigh 1 part of the cracked wax prepared in Example 1 and 2 parts of sodium-based montmorillonite and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, and use a high-speed shearer to shear. The rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing is completed, pour it into a silica gel mold while it is hot to obtain a warm mix asphalt composite material.

[0067] Comparative Example 4

[0068] Weigh 1 part of the cracked wax prepared in Example 1, 1 part of the carbon nanotubes prepared by the method of Comparative Example 2, and 1 part of sodium-based montmorillonite and mix them to obtain a composite warm mix material. Weigh 100 parts of 70# asphalt and 3 parts of the composite warm mix material, heat it up to 145 °C, wait until the asphalt is completely melted, and use a high-speed shearer to shear. The rotation speed of the shearer is 3000 rpm and the shearing time is 30 min. After shearing is completed, pour it into a silica gel mold while it is hot to obtain a warm mix asphalt composite material.

[0069] Figure 2 It is the SEM image of the carbon nanotube-montmorillonite hybrid material prepared in Example 1. It can be seen that the carbon nanotubes and montmorillonite platelets are very obvious, and the carbon nanotubes grow out through the platelets.

[0070] Figure 3 It is the TEM image of the carbon nanotube-montmorillonite hybrid material prepared in Example 1. It can be clearly seen the carbon nanotubes on the montmorillonite.

[0071] Performance test: Conduct tests according to the AASHTO T 315-02 standard. Use the MCR 702 type advanced rheometer of Anton Paar GmbH in Austria to detect the high-temperature performance and low-temperature performance of the asphalt composite materials of Examples 1-5 and Comparative Examples 1-4. The results are as Figures 4 - 5 shown.

[0072] From Figure 4 (a) and (b) in it, it can be seen that the warm mix asphalt material prepared using the ZSM catalyst has the lowest phase angle, indicating that its viscosity reduction effect is the best. From Figure 4As can be seen from (c) and (d) therein, the high-temperature complex shear modulus and high-temperature rutting factor of the warm mix asphalt composite using the composite warm mix material are greater than those of Comparative Example 1, indicating that its high-temperature performance is superior to that of the comparative example. From Figure 4 As can be seen from (e) and (f) therein, the low-temperature complex shear modulus and low-temperature rutting factor of the warm mix asphalt composite using the composite warm mix material are greater than those of Comparative Example 1, indicating that its low-temperature performance is superior to that of Comparative Example 1. At the same time, when the dosage ratio of cracked wax to carbon nanotube-montmorillonite hybrid material is 1:2 (Example 4), the warm mix asphalt material of the present invention has the most excellent high and low temperature performance.

[0073] From Figure 5 As can be seen from (a) and (b) therein, the low-temperature complex shear modulus and low-temperature rutting factor of the warm mix asphalt composite using the composite warm mix material are greater than those of Comparative Examples 2, 3, and 4, indicating that its low-temperature performance is superior to that of Comparative Examples 2, 3, and 4, and the hybridized carbon nanotube-montmorillonite composite has a better improvement on the low-temperature performance of the warm mix asphalt composite.

[0074] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and does not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A composite warm mix material based on the catalytic cracking products of waste polyolefins, characterized in that: The composite warm mix material is composed of cracked wax and carbon nanotube-montmorillonite hybrid material; The cracked wax is obtained by catalytic cracking of waste polyolefins; The carbon nanotube-montmorillonite hybrid material is obtained by pyrolyzing waste polyolefins as a carbon source to form carbon nanotubes on the surface of montmorillonite. The preparation method is as follows: nickel nitrate and montmorillonite are subjected to cation exchange to obtain nickel / montmorillonite; nickel / montmorillonite and waste polyolefins are kneaded in a twin-screw extruder, and then the extruded product is crushed by a crusher to obtain a composite of waste polyolefins and nickel / montmorillonite; the composite of waste polyolefins and nickel / montmorillonite is placed in a tubular furnace and heated under an inert gas atmosphere to obtain the carbon nanotube-montmorillonite hybrid material.

2. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 1, wherein The preparation method of the cracked wax is as follows: waste polyolefins and a catalyst are kneaded in a twin-screw extruder, and then the extruded product is crushed by a crusher to obtain a composite of waste polyolefins and the catalyst; the composite of waste polyolefins and the catalyst is placed in a tubular furnace and heated under an inert gas atmosphere to obtain the cracked wax.

3. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 2, characterized in that: The mass ratio of the catalyst to the waste polyolefins is 1:5 - 20, the heating temperature is 350 - 450 °C, and the heat preservation time is 1 - 2 h.

4. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 2, wherein: The catalyst is at least one of molecular sieve and zeolite.

5. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 2, characterized in that: The molecular weight of the cracked wax is 800 - 2200.

6. The composite warm mix material based on the catalytic cracking product of waste polyolefins according to claim 1, characterized in that: The mass ratio of nickel nitrate to montmorillonite is 1:1 - 10; the mass ratio of nickel / montmorillonite to waste polyolefins is 1:90 - 100; the heating temperature is 650 - 900 °C, and the heat preservation time is 1 - 2 h.

7. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 1, characterized in that: In the composite warm mix material, the mass ratio of the cracked wax to the carbon nanotube-montmorillonite hybrid material is 1:0.5 - 3.

8. The composite warm mix material based on the catalytic cracking products of waste polyolefins according to claim 1, characterized in that: The cracked wax and the carbon nanotube-montmorillonite hybrid material can be prepared simultaneously by connecting three tubular furnaces as reaction chambers, and the inert gas flows through the first reaction chamber, the second reaction chamber, and the third reaction chamber in sequence; In the first reaction chamber, a composite of waste polyolefins and a catalyst is placed for preparing the cracked wax; in the second reaction chamber, a composite of waste polyolefins and nickel / montmorillonite is placed for preparing the carbon nanotube-montmorillonite hybrid material; only nickel / montmorillonite is placed in the third reaction chamber for collecting the unreacted carbon source in the first reaction chamber and the second reaction chamber to obtain the carbon nanotube-montmorillonite hybrid material.

9. Application of the composite warm mix material according to any one of claims 1 - 8 in asphalt.

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