A method for preparing and applying functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins

Abstract

This invention provides a method for preparing and applying functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins. The method utilizes an organic catalytic system to oxidatively pyrolyze decommissioned polyolefin materials, simultaneously breaking down polymer chains and introducing valuable oxygen-containing functional groups, such as carboxyl and carbonyl groups, into the pyrolysis products. This allows for the adjustment of the molecular weight, molecular weight distribution, and oxidative functionalization of the pyrolysis products, resulting in functionalized oligomers. These functionalized oligomers can serve as crystalline hard phases and, by utilizing the reactivity of the introduced oxygen-containing groups, can undergo dynamic crosslinking reactions with amorphous epoxidized rubber to construct a high-performance elastomer material. This invention effectively solves the problems of high energy consumption, product separation, and difficulties in subsequent utilization in the recycling of decommissioned polyolefins, achieving high-value upgrading and recycling of decommissioned polyolefins and promoting the green and sustainable development of polymers and polymer engineering.

Description

Technical Field

[0001] This invention relates to the field of decommissioned polyolefin recycling, and in particular to a method for preparing and applying functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins. Background Technology

[0002] Since its invention in the early 20th century, plastic has become the most important synthetic polymer material in daily life. Its annual production has steadily increased from 2 million tons in 1950 to over 390 million tons in 2021. As of 2021, only 11% of the 8.7 billion tons of waste plastic generated globally was recycled. Based on current waste plastic management methods, it is estimated that by 2050, 12 billion tons of waste plastic will be landfilled or enter the natural environment. Improper disposal of plastic waste after it has been decommissioned has caused serious "white pollution" and "microplastic" problems.

[0003] To address the pollution problem caused by waste plastics, people often choose to incinerate or bury them. This results in serious resource waste and secondary pollution of soil, water, and air. Clearly, these two methods are undesirable in the context of a circular economy for plastics. Physical recycling of sorted waste plastics is a simple, economical, and effective method for handling large-scale waste plastics. However, it is limited by the deterioration of material properties after multiple recycling processes and cannot achieve true recycling in the sense of a circular economy. Chemical recycling, which depolymerizes waste plastics into monomers or oligomers, is an effective alternative. The obtained monomers or oligomers can be repolymerized into raw materials or new materials, thus realizing a circular economy.

[0004] In the chemical recovery of decommissioned polyolefins, besides methods such as pyrolysis, catalytic cracking, tandem hydrogenolysis aromatization, and cross-alkane metathesis, oxidative cracking is an effective alternative. Oxidative cracking can achieve chain scission of decommissioned polyolefins at low temperatures, while introducing valuable reactive groups such as hydroxyl, carbonyl, and carboxyl groups, thus realizing value-added of cracking products. Currently, various oxidative cracking systems have been developed, with commonly used oxidants including O2, NO, NO2, HNO3, and H2O2. The products are mostly mixtures of short-chain dicarboxylic acids, and the wide distribution of mixed products and low selectivity for high-value products bring difficulties to subsequent separation and utilization. Therefore, how to avoid the subsequent separation of oxidative cracking products while achieving high-value utilization of the products remains a challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying functionalized oligomers based on the oxidative cracking of decommissioned polyolefins. Carbon and oxygen free radicals are introduced into the decommissioned polyolefin chain through an aerobic oxidation organic catalyst and oxidant gas. The chain scission of decommissioned polyolefins is achieved through the β-fracture reaction of free radicals to obtain functionalized oligomers in the form of semi-crystalline polymers. Furthermore, the functionalized oligomers can be used to directly undergo dynamic crosslinking reaction with epoxy rubber to prepare elastomer materials.

[0006] To achieve the above objectives, this technical solution provides a method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins, comprising the following steps:

[0007] The aerobic oxidation catalyst and decommissioned polyolefin are dissolved in an organic solvent at a certain mass ratio and then transferred to the reactor.

[0008] An oxidant gas is introduced into the reactor until it is sealed. The reaction temperature of the reactor is adjusted to a high temperature and the reaction is stirred for a period of time to obtain precipitated material. In this process, the oxidant gas and decommissioned polyolefins undergo a free radical oxidation reaction under the action of an aerobic oxidation catalyst to generate free radicals. These free radicals are used to break down decommissioned polyolefins and introduce functional groups.

[0009] Dissolve the precipitate to obtain a reaction precipitate solution, filter the reaction precipitate solution to obtain a precipitate solid, and dry the precipitate solid to obtain a functionalized oligomer.

[0010] This scheme utilizes aerobic oxidation organic catalysts and oxidant gases to introduce carbon radicals, peroxy radicals, and oxygen radicals into decommissioned polyolefin chains. Through the β-fracture reaction of free radicals, the decommissioned polyolefin chains are broken down to obtain functionalized oligomers with reduced molecular weight. At the same time, oxygen radicals can be further derived into carbonyl, carboxyl, hydroxyl, and other oxidizing groups. By precisely controlling the reaction conditions to manage the cumulative degree of β-fracture events of free radicals, the molecular weight, molecular weight distribution, and functionality of the pyrolysis products can be adjusted, thereby obtaining functionalized oligomers that meet the requirements.

[0011] Furthermore, the aerobic oxidation catalyst is selected from one or more of N-hydroxyphthalimide, N-hydroxysuccinimide, N-hydroxymaleimide, N-acetylphthalimide, 3,4,5,6-tetrachloro-N-hydroxyphthalimide, 3,4,5,6-tetrabromo-N-hydroxyphthalimide, 3,4,5,6-tetrafluoro-N-hydroxyphthalimide, 2,2,6,6-tetramethylpiperidine oxide, N,N'-dihydroxyphthalimide, N,N',N”-trihydroxyisocyanuric acid, 2-azaadamantane-N-oxygen, N-hydroxy-3,4,5,6-tetraphenylphthalimide, N,N'-dihydroxypyromellitic acid imide, and N-hydroxyquinolineimide, mixed in any proportion.

[0012] It should be noted that this aerobic oxidation catalyst accelerates the aerobic oxidation reaction between the oxidant and decommissioned polyolefins to generate a series of free radicals, including carbon free radicals, oxygen free radicals, and peroxy free radicals. Among them, the free radicals undergo β-chain scission reactions with the decommissioned polyolefins to obtain oligomers with reduced molecular weight. At the same time, the oxygen free radicals and peroxy free radicals undergo oxidation and transfer termination reactions to derive carbonyl, carboxyl, hydroxyl, and other oxidizing groups.

[0013] Furthermore, the decommissioned polyolefin is one or more of low-density polyethylene, high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, polystyrene, ethylene and α-olefin copolymers mixed in any proportion.

[0014] Furthermore, the mass ratio of the aerobic oxidation catalyst to the decommissioned polyolefin is 1–100:100–1. Generally, the content of the aerobic oxidation catalyst is inversely proportional to the molecular weight of the functionalized oligomer and directly proportional to the derivatization of functional groups. This scheme can control the molecular weight, molecular weight distribution, and functionality of the functionalized oligomer by adjusting the content of the aerobic oxidation catalyst.

[0015] Furthermore, the organic solvent is selected from any one or a mixture of two or more of the following: 1,1,2,2-tetrachloroethane, 1,2-dichloroethane, chloroform, toluene, xylene, o-dichlorobenzene, 1,2,4-trichlorobenzene, tetrahydronaphthalene, n-butyl acetate, and straight-chain alkanes, isoalkanes, and cycloalkanes with 4 to 10 carbon atoms.

[0016] Furthermore, this scheme can either mix a certain mass ratio of aerobic oxidation catalyst with decommissioned polyolefin and then transfer the mixture to the reactor before adding an organic solvent to the reactor, or directly dissolve a certain mass ratio of aerobic oxidation catalyst and decommissioned polyolefin in an organic solvent before transferring them together to the reactor.

[0017] Furthermore, the oxidant gas is one or more of air, oxygen, ozone, nitrogen dioxide, and nitric oxide, mixed in any proportion.

[0018] Furthermore, the pressure of the oxidant gas is 1–30 bar. Generally, the concentration of the oxidant gas is inversely proportional to the molecular weight of the functionalized oligomer and directly proportional to the derivatization of the functional groups. This scheme can control the molecular weight, molecular weight distribution, and functionality of the functionalized oligomer by adjusting the concentration of the oxidant gas.

[0019] Furthermore, oxidant gas is continuously introduced into the reactor until it is sealed using a method of continuous ventilation or gas replacement.

[0020] Furthermore, when oxidant gas is introduced into the reactor to achieve a sealed state using gas replacement, the reactor is repeatedly evacuated and purged with nitrogen multiple times, followed by evacuation and oxidant replacement multiple times to achieve a sealed state. Preferably, the reactor can be repeatedly evacuated and purged with nitrogen five times, followed by evacuation and oxidant gas replacement three times to achieve a sealed reactor.

[0021] Furthermore, the reaction temperature in the reactor is adjusted to 90℃~130℃, and the reaction is stirred for 1h~48h. Generally speaking, the longer the reaction time, the more β-fracture events accumulate, resulting in a lower molecular weight of the functionalized oligomer; similarly, the functionality also increases with increasing reaction time. In other words, reaction temperature and reaction time are inversely proportional to the molecular weight of the functionalized oligomer and directly proportional to its functionality. This scheme can control the molecular weight, molecular weight distribution, and functionality of the functionalized oligomer by adjusting the reaction temperature and reaction time.

[0022] Furthermore, under the action of an aerobic oxidation catalyst, the oxidant gas and the decommissioned polyolefin undergo a free radical oxidation reaction to generate carbon free radicals, oxygen free radicals and peroxy free radicals. The functional groups are one or more of carboxyl, hydroxyl, carbonyl, ester bond, peroxy group, epoxy group, ether bond, peroxy acid group, nitro group and sulfonic acid group, mixed in any proportion.

[0023] Furthermore, the precipitate is dissolved in methanol to obtain a reaction precipitate solution, which is then filtered to obtain a precipitate solid. The precipitate solid is then vacuum-dried at 65°C–80°C for 10–15 hours to obtain the functionalized oligomer. Preferably, the substrate solid is vacuum-dried at 70°C for 12 hours.

[0024] Furthermore, the functionalized oligomers obtained by this method have a number average molecular weight of 1500–10000 Da, a molecular weight distribution index of 2.0–4.0, a crystallinity of 30–60%, a functionality of 0.5–6.0 mol% (relative to ethylene monomer), and a functionalization selectivity of 0–50%.

[0025] As described above, this scheme provides a method for preparing functionalized oligomers based on the oxidative cracking of decommissioned polyolefins. By precisely controlling the reaction conditions (oxidant concentration, catalyst dosage, and reaction time), the cumulative degree of β-fracture events of free radicals can be controlled, so as to achieve adjustable molecular weight, molecular weight distribution, and functionality of the cracking products. The functionalized oligomers with different functionalities and molecular weights obtained by this scheme can have different application scenarios. For example, functionalized oligomers with larger molecular weights can be used as processing aids, while functionalized oligomers with smaller molecular weights can be used to construct elastomer materials.

[0026] Specifically, since the functionalized oligomers constructed in this scheme are semi-crystalline polymers, they can be directly used to dynamically crosslink with epoxy rubber without separation, utilizing the reactivity of the oxidized groups in the functionalized oligomers to prepare elastomer materials. Correspondingly, in the second aspect, this scheme provides an application method based on the functionalized oligomers from the oxidative pyrolysis of decommissioned polyolefins, including the following steps:

[0027] An epoxidized rubber, functionalized oligomer, and catalyst are mixed in a certain mass ratio to obtain a mixture, which is then premixed in an organic solvent and stirred at high temperature for a period of time. The functionalized oligomer is prepared according to the preparation method of functionalized oligomer based on the oxidative cracking of decommissioned polyolefins in the first aspect.

[0028] The organic solvent is removed to obtain a solid mixture, which is then placed on a flat vulcanizer to undergo a vulcanization crosslinking reaction to obtain an elastomer material.

[0029] It should be noted that, due to the presence of oxide groups on functionalized oligomers, these oxide groups can react with the epoxy groups of epoxidized rubber under the action of a catalyst to generate new bonds and groups, thus creating a crosslinked network and constructing an elastomer material. The new bonds and groups in this crosslinked network are dynamic chemical crosslinking points, while the semi-crystalline sites on the functionalized oligomer are physical crosslinking points. In other words, the crosslinking reaction between the functional groups of the functionalized oligomer and the epoxy groups of the epoxidized rubber yields an elastomer material, whose crosslinked network possesses both dynamic chemical and physical crosslinking points.

[0030] Furthermore, the epoxidized rubber is one or more of the following: epoxidized cis-butadiene rubber, epoxidized natural rubber, epoxidized polyisoprene rubber, epoxidized styrene-butadiene rubber, epoxidized butyl rubber, epoxidized chloroprene rubber, epoxidized ethylene propylene diene monomer (EPDM) rubber, and epoxidized styrene-butadiene-styrene block copolymer, mixed in any proportion.

[0031] Furthermore, epoxidized rubber has an epoxy content of 1% to 50%.

[0032] Furthermore, the catalyst is an esterification catalyst or an ester exchange catalyst, selected from one or more of the following: zinc acetate, zinc acetylacetonate, tin 2-ethylhexanoate, dibutyltin dilaurate, dibutyltin diacetate, diacetylacetonate dibutyltin, 1,2-dimethylimidazole, 1-methylimidazole, 2-ethyl-4-methylimidazole, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane, triphenylphosphine, triethanolamine, and benzyl dimethylamine, mixed in any proportion.

[0033] Furthermore, the mass ratio of epoxidized rubber, functionalized oligomer, and catalyst is 1:0.02:0.03 to 1:1:0.03. The advantage of this control is that the content of crystalline phase in the elastomer material can be controlled by adjusting the amount of functionalized oligomer, thereby achieving a balance between the elasticity of the amorphous material and the strength of the crystalline phase.

[0034] Furthermore, the organic solvent is any one or a mixture of two or more of the following: 1,1,2,2-tetrachloroethane, 1,2-dichloroethane, chloroform, toluene, xylene, o-dichlorobenzene, 1,2,4-trichlorobenzene, tetrahydronaphthalene, n-butyl acetate, and straight-chain alkanes, isoalkanes, and cycloalkanes with 4 to 10 carbon atoms.

[0035] Further, the mixture is premixed in an organic solvent and stirred at 85°C–100°C for 10–30 minutes, wherein the stirring speed is 400–600 rpm. Preferably, the mixture is premixed in an organic solvent and stirred at 90°C for 15 minutes, wherein the stirring speed is 500 rpm.

[0036] Furthermore, the solid mixture is placed on a flat vulcanizing apparatus to undergo a vulcanization crosslinking reaction to obtain an elastomer material. The vulcanization reaction conditions are: vulcanization temperature of 130℃~160℃, vulcanization pressure of 8~12MPa, and vulcanization time of 25~40min. Preferably, the vulcanization reaction conditions are: vulcanization temperature of 150℃, vulcanization pressure of 10MPa, and vulcanization time of 30min.

[0037] Furthermore, the crosslinked network of the elastomer material prepared by this method has dynamic chemical crosslinking points and physical crosslinking points. The dynamic chemical crosslinking points are provided by new bonds and new groups generated by the reaction of the oxidizing groups of the functionalized oligomers with the epoxy groups in the epoxidized rubber, while the physical crosslinking points are provided by the semi-crystalline regions of the functionalized oligomers.

[0038] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects:

[0039] This method provides a technique for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins. A large number of free radicals are generated through a free radical oxidation reaction. Some of these free radicals break down the polyolefin chains, yielding pyrolysis products of varying molecular weights. Simultaneously, the free radicals oxidize to form functional groups, including oxide groups. By controlling the cumulative degree of β-fracture events of the free radicals, the molecular weight, molecular weight distribution, and functionality of the pyrolysis products can be adjusted, resulting in functionalized oligomers with controllable molecular weight and functionality. Since the functionalized oligomers produced in this method are semi-crystalline polymers, they can be directly used to dynamically crosslink with epoxy rubber without separation, thus preparing elastomer materials.

[0040] In other words, this scheme proposes for the first time a method for the preparation and application of functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins. By utilizing an aerobic oxidative organic catalyst, the low-temperature controllable oxidative pyrolysis of decommissioned polyolefins is achieved, and the molecular weight, molecular weight distribution, and degree of functionalization of the pyrolysis products can be adjusted. Subsequently, without separation, the reaction characteristics of the products can be directly used to construct an elastomer material with excellent mechanical and thermomechanical properties, avoiding the difficulties in the separation and reuse of oxidative pyrolysis products in the past. This scheme proposes a new, simple, and effective high-value recycling route for decommissioned polyolefins, which has guiding significance for subsequent research and is conducive to the green and sustainable development of polymer engineering. Attached Figure Description

[0041] Figure 1 This is a reaction equation for the preparation of functionalized oligomers according to an embodiment of the present invention.

[0042] Figure 2 This is a molecular weight distribution diagram of a functionalized oligomer according to an embodiment of the present invention.

[0043] Figure 3 It is a stress-strain curve diagram of an elastomer material.

[0044] Figure 4 It is a curve showing how the energy storage modulus changes with temperature. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0046] This invention provides a method for preparing and applying functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins. To make the objectives, technical solutions, and effects of this invention clearer, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0047] I. Performance Testing Instructions:

[0048] The molecular weight of the polymer (M) w and M n ) and its distribution index High-temperature gel permeation chromatography (PL-GPC220) was used for determination. Polymer solutions of 0.1–0.3 wt.% were prepared at 150 °C using 1,2,4-trichlorobenzene as solvent. Narrow molecular weight distribution polystyrene was used as a standard, and the determination was performed at 150 °C with a solvent flow rate of 1.0 mL / min. The parameter k = 5.91 × 10⁻⁶ was used for all PS standards. -4 , α=0.69.

[0049] The melting point (Tm) and glass transition temperature (Tg) of the functionalized oligomers were determined using a TA Instruments Q2500. 5.0–8.0 mg of polymer sample was heated to 190 °C at a rate of 30 °C / min, held at that temperature for 5 min to eliminate thermal history, then cooled to -120 °C at a rate of 10 °C / min, held at that temperature for 3 min, and then heated to 190 °C at a rate of 10 °C / min. The melting point and glass transition temperature of the polymer were obtained from the second heating curve.

[0050] The functionality and relative content of each oxide group in the functionalized oligomers were determined using high-temperature 1H NMR spectroscopy. 1 The H NMR was measured at 130 °C using a Bruker AC 400 instrument. A 10% (w / w) solution of deuterated o-dichlorobenzene was prepared at 150 °C and pre-dissolved for 3-4 h to ensure homogeneity of the sample solution.

[0051] Mechanical property testing was conducted using an Instron 3345 universal testing machine according to ASTM-D412 standards. This machine was equipped with a 500 N electronic pressure gauge and mechanical clamps. The test temperature was 25°C, and the upper beam travel speed was 50 mm / min. The reprocessing procedure involved cutting the material into pieces of approximately 0.5 cm and then hot-pressing them at 160°C for 1 hour. The reprocessing efficiency was defined as (tensile toughness after reprocessing / tensile toughness before reprocessing) × 100%.

[0052] The gel content was determined by Soxhlet extraction. The material was extracted in toluene at 120℃ for 8 h and then vacuum dried. The gel content was defined as (weight of sample after extraction / weight of sample before extraction) × 100%.

[0053] Thermomechanical property tests were conducted using rectangular specimens (20 mm × 5 mm × 0.3 mm) on a TA Q800 dynamic mechanical analyzer. The heating range was -120 to 180 °C, the heating rate was 3 °C / min, the constant force was 0.01 N, and the frequency was 1 Hz.

[0054] II. Implementation Plan Design:

[0055] Example 1

[0056] In this embodiment, the decommissioned polyolefin is selected as high-density polyethylene (Mw = 18.6 kDa). The aerobic oxidation organic catalyst used was N-hydroxyphthalimide, the solvent was 1,1,2,2-tetrachloroethane, and the oxidant gas was oxygen. The oxidant gas injection method was gas replacement. Before the experiment, high-density polyethylene and N-hydroxyphthalimide were mixed in a 10:2 ratio and placed in a reactor. 1,1,2,2-tetrachloroethane was added to the reactor to maintain an overall concentration of 0.1 g / ml. The reactor was repeatedly evacuated and purged with nitrogen five times, followed by evacuation and oxygen purging three times to ensure a complete seal. The reactor temperature was raised to 110°C, and stirring was started at 300 rpm. The reaction was stopped after 1 hour. The precipitate was placed in a large amount of methanol, stirred overnight, and then filtered to obtain a solid. This solid was then vacuum-dried at 70°C for at least 12 hours to obtain the functionalized oligomer. All materials used in the experiment were used directly without any treatment. The reaction equation for Example 1 is as follows: Figure 1 As shown.

[0057] This functionalized oligomer has a number-average molecular weight of 5.5 kDa, a molecular weight distribution of 3.33, a functionality of 0.66 mol%, a carboxyl content of 43.8%, a carbonyl content of 56.2%, a hydroxyl content of 0%, a melting point of 122.5 °C, and a crystallinity of 51.3%.

[0058] Example 2

[0059] The experimental conditions were as follows: reaction time was 2 hours, and other experimental conditions were the same as in Example 1. The number-average molecular weight was 3.4 kDa, the molecular weight distribution was 2.91, the functionality was 3.29 mol%, the carboxyl content was 34.4%, the carbonyl content was 45.9%, the hydroxyl content was 19.7%, the melting point was 118.0 °C, and the crystallinity was 51.4%.

[0060] Example 3

[0061] The experimental conditions were as follows: reaction time was 6 hours, and other experimental conditions were the same as in Example 1. The number-average molecular weight was 1.5 kDa, the molecular weight distribution was 3.23, the functionality was 4.80 mol%, the carboxyl content was 35.3%, the carbonyl content was 47.4%, the hydroxyl content was 17.3%, the melting point was 106.5 °C, and the crystallinity was 49.0%.

[0062] Example 4

[0063] The experimental conditions were as follows: reaction time was 12 hours, and other experimental conditions were the same as in Example 1. The number-average molecular weight was 1.5 kDa, the molecular weight distribution was 3.25, the functionality was 5.50 mol%, the carboxyl content was 40.4%, the carbonyl content was 47.8%, the hydroxyl content was 11.8%, the melting point was 104.5 °C, and the crystallinity was 50.2%.

[0064] The functionalized oligomers prepared in Examples 1-4 above were characterized, and the characterization results are shown in Table 1. Using the oxidative pyrolysis technology proposed in this invention, the molecular weight and molecular weight distribution of the pyrolysis products can be adjusted. Figure 2 This is a schematic diagram of the mass fraction of the functionalized oligomers in Examples 1-4. It can be seen that the reaction time can affect the molecular weight of the functionalized oligomers. The longer the reaction time, the more β-cleavage events accumulate, resulting in a lower molecular weight of the product. At the same time, oxygen-containing groups, such as carboxyl, carbonyl, and hydroxyl groups, can be introduced at the same time as the decommissioned polyolefin chain breaks, thus successfully preparing functionalized oligomers.

[0065] Table 1: Characterization results of functionalized oligomers

[0066]

[0067] Example 5

[0068] In this embodiment, the functionalized oligomer was selected from the one obtained in Example 4, the epoxidized rubber was epoxidized cis-butadiene rubber, the epoxy content was 8 mol%, the catalyst was 1,2-dimethylimidazole, and the solvent was toluene. Before the experiment, the epoxidized cis-butadiene rubber, the functionalized oligomer obtained in Example 4, and 1,2-dimethylimidazole were mixed in a ratio of 1:0.09:0.03 and placed in a glass container. Toluene was added to the glass container to maintain an overall concentration of 0.05 g / ml. The glass container was heated to 90°C, and stirring was started at 500 rpm for 15 minutes until homogeneous. The solid mixture after removing the toluene solvent was placed on a flat vulcanizing apparatus for crosslinking reaction. The vulcanization temperature was 150°C, the vulcanization pressure was 10 MPa, and the vulcanization time was 30 minutes. After crosslinking, the elastomer material of this invention was obtained, exhibiting excellent mechanical and thermomechanical properties.

[0069] Example 6

[0070] The experimental conditions were as follows: the ratio of experimental materials was changed to 1:0.23:0.03, and other experimental conditions were the same as in Example 5. The resulting elastomer material exhibited excellent mechanical and thermomechanical properties.

[0071] Example 7

[0072] The experimental conditions were as follows: the ratio of experimental materials was changed to 1:0.33:0.03, and other experimental conditions were the same as in Example 5. The resulting elastomer material exhibited excellent mechanical and thermomechanical properties.

[0073] Example 8

[0074] The experimental conditions were as follows: the ratio of experimental materials was changed to 1:0.5:0.03, and other experimental conditions were the same as in Example 5. The resulting elastomer material exhibited excellent mechanical and thermomechanical properties.

[0075] The elastomers prepared in Examples 5-8 above were tested, and the test results are shown in Table 2. The functionalized oligomers prepared using the oxidative pyrolysis technology of this invention can further undergo dynamic crosslinking reactions with epoxidized rubber to synergistically construct elastomer materials. These materials possess both physical and dynamic crosslinking points, resulting in excellent mechanical and thermomechanical properties. Figure 3 These are stress-strain diagrams from Examples 5 to 8, showing that the content of functionalized oligomers affects the mechanical properties of the elastomer material. Figure 4 The graphs show the changes in storage modulus with temperature for Examples 5-8, demonstrating that the content of functionalized oligomers affects the thermomechanical properties of the elastomer material.

[0076] Meanwhile, the dynamic cross-linking points endow the elastomer material with the characteristic of being reprocessable.

[0077] Table 2: Performance Results of Elastomer Materials

[0078]

[0079]

[0080] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins, characterized in that, Includes the following steps: An aerobic oxidation catalyst and decommissioned polyolefin are dissolved in an organic solvent at a certain mass ratio and transferred to a reactor. The aerobic oxidation catalyst is selected from one or more of the following: N-hydroxyphthalimide, N-hydroxysuccinimide, N-hydroxymaleimide, N-acetylphthalimide, 3,4,5,6-tetrachloro-N-hydroxyphthalimide, 3,4,5,6-tetrabromo-N-hydroxyphthalimide, 3,4,5,6-tetrafluoro-N-hydroxyphthalimide, 2,2,6,6-tetramethylpiperidine oxide, N,N'-dihydroxyphthalimide, N,N',N''-trihydroxyisocyanuric acid, 2-azaadamantane-N-oxygen, N-hydroxy-3,4,5,6-tetraphenylphthalimide, N,N'-dihydroxypyromellitic acid imide, and N-hydroxyquinolineimide, and mixed in any proportion. An oxidant gas is introduced into the reactor until it is sealed. The reaction temperature of the reactor is adjusted to a high temperature and the reaction is stirred for a period of time to obtain precipitated material. In this process, the oxidant gas and decommissioned polyolefins undergo a free radical oxidation reaction under the action of an aerobic oxidation catalyst to generate free radicals. These free radicals are used to break down decommissioned polyolefins and introduce functional groups. Dissolve the precipitate to obtain a reaction precipitate solution, filter the reaction precipitate solution to obtain a precipitate solid, and dry the precipitate solid to obtain a functionalized oligomer.

2. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The retired polyolefin is one or more of low-density polyethylene, high-density polyethylene, linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, polystyrene, ethylene and α-olefin copolymers mixed in any proportion.

3. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The oxidizing gas is one or more of air, oxygen, ozone, nitrogen dioxide, and nitric oxide, mixed in any proportion.

4. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The mass ratio of aerobic oxidation catalyst to decommissioned polyolefin is 1~100: 100~1.

5. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The pressure of the oxidant gas is 1 to 30 bar.

6. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The reaction temperature of the reactor is adjusted to 90°C to 130°C, and the reaction is stirred for 1 to 48 hours to obtain precipitated material.

7. The method for preparing functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 1, characterized in that, The functionalized oligomers have a number average molecular weight of 1,500–10,000 Da, a molecular weight distribution index of 2.0–4.0, a crystallinity of 30–60%, and a functionality of 0.5–6.0 mol compared to ethylene monomers.

8. An application method for functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins, characterized in that, Includes the following steps: An epoxidized rubber, functionalized oligomer, and catalyst are mixed in a certain mass ratio to obtain a mixture, and the mixture is premixed in an organic solvent and stirred at high temperature for a period of time. The functionalized oligomer is prepared according to any one of claims 1 to 7 based on the oxidative cracking of decommissioned polyolefins. The organic solvent is removed to obtain a solid mixture, which is then placed on a flat vulcanizer to undergo a vulcanization crosslinking reaction to obtain an elastomer material.

9. The application method of functionalized oligomers based on the oxidative pyrolysis of decommissioned polyolefins according to claim 8, characterized in that, The crosslinked network of the elastomer material has dynamic chemical crosslinking points and physical crosslinking points. The dynamic chemical crosslinking points are provided by new bonds and new groups formed between the oxidizing groups of the functionalized oligomers and the epoxy groups in the epoxidized rubber, while the physical crosslinking points are provided by the semi-crystalline regions of the functionalized oligomers.

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