Preparation method of POE (polyolefin elastomer) grafted MAH (maleic anhydride) with high grafting rate and low crosslinking degree

Abstract

The invention discloses a preparation method of POE (polyolefin elastomer) grafted MAH (maleic anhydride) with high grafting rate and low crosslinking degree. The method comprises the following steps: blending a POE elastomer with MAH, an initiator and an optional auxiliary agent, and carrying out melt grafting reaction, extrusion and granulation in a screw extruder to obtain the POE grafted MAH, the POE elastomer has a relative active site content RAS of 0.15 or more and a cross-linking grafting ratio CRG of 0.06 or less at a reaction temperature T. The method provided by the invention can be used for preparing POE grafted MAH with high grafting rate and low crosslinking degree.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of modified polymer materials, and particularly relates to a preparation method of POE grafted with MAH with high grafting rate and low crosslinking degree. BACKGROUND

[0002] POE is a thermoplastic elastomer material obtained by copolymerization of ethylene and alpha-olefin, which not only has plasticity, but also has high elasticity and toughness of rubber, and is often used as a toughening modifier of rigid plastic. However, POE as a typical non-polar material has poor compatibility with polar polymer materials, and cannot provide good toughening effect. POE grafted with MAH (maleic anhydride) can effectively improve the compatibility with polar plastic, and form an "island structure" after being blended with polar plastic, so as to greatly improve the toughness of the material through the micro-silver line toughening mechanism.

[0003] Common methods for POE grafted with MAH include melt grafting method, solution method, solid phase method, radiation grafting method and suspension grafting method. Among them, the melt grafting method has the characteristics of short reaction time, simple process, low cost and continuous production, and thus becomes the most important grafting method in current application research. In the melt grafting method, POE is uniformly mixed with MAH, initiator and other additives, and then is melt mixed at high temperature through a screw extruder, and the grafted product is obtained after extrusion and granulation. When the grafted product is used for toughening modification of polar plastics such as nylon (PA), the anhydride groups of MAH react with the amino groups in PA to enhance the compatibility and interfacial interaction between the grafted product and PA, and thus the grafting rate is an important indicator of POE grafted with MAH product. The influencing factors of the grafting rate are very complex, which are related to the structures of POE and initiator, the addition amount of MAH and process parameters, etc. In the melt grafting reaction, high temperature accelerates the decomposition of the initiator to generate free radical active sites, which initiate the grafting reaction of POE and MAH. The structure of POE and initiator determines the number of active sites, and the monomer concentration and process parameters affect the reaction rate. However, in the melt grafting reaction, the existence of a large number of free radical active sites increases the collision probability between macromolecular radicals, so that POE has a strong tendency to crosslink, and thus crosslinking side reactions are often unavoidable. The crosslinking side reaction and the grafting reaction are competitive reactions, crosslinking not only causes the flowability of POE to decrease, affecting the product performance, but also consumes the active sites of the system, reducing the grafting rate of the system, affecting the compatibility and dispersion in the matrix when toughening PA material, and weakening the toughening effect on PA. Therefore, how to inhibit the crosslinking side reaction while ensuring that POE has high grafting rate and excellent performance is the research focus.

[0004] For example, invention patent application CN115073672A mixes POE, MAH, and DCP in a certain proportion, then adds a certain amount of styrene and other additives, and performs melt grafting through a twin-screw extruder. Supercritical carbon dioxide is injected during the extrusion process. The extruded material is water-cooled, pelletized, and then dried to obtain toughened and reinforced light yellow POE-grafted MAH granules with a high grafting rate. The addition of a second monomer allows for copolymerization and grafting with MAH, effectively increasing the grafting rate. Another example is invention patent application CN118684829A, which mixes POE, MAH, antioxidants, initiators, and chlorinated hydrocarbons in a certain proportion, then adds a certain amount of chlorinated hydrocarbons. The mixture is then kept at a constant temperature and pressure in supercritical carbon dioxide for a period of time before melt grafting through a twin-screw extruder. The formation of free radicals by the chlorinated hydrocarbons and initiators promotes the grafting reaction of MAH, thereby increasing the grafting rate. However, the formation of a large number of free radicals may promote cross-linking side reactions, and the use of supercritical carbon dioxide increases process costs, which is not conducive to industrial production. Summary of the Invention

[0005] To address the above technical problems, this invention proposes a method for preparing POE-grafted MAH with high grafting rate and low crosslinking degree.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing POE-grafted MAH with high grafting rate and low crosslinking degree includes the following steps: POE elastomer is blended with MAH, initiator, and optional additives, and then subjected to a melt grafting reaction in a screw extruder. The mixture is then extruded and granulated to obtain the POE-grafted MAH. The POE elastomer has a relative active site content (RAS) of 0.15 or greater and a crosslinking grafting ratio (CRG) of 0.06 or lower at a reaction temperature T. The relative active site content (RAS) is defined by the following Equation 1: Equation 1 The cross-linking graft ratio (CRG) is defined by the following equation 2: Equation 2 In the equation, [CR], [CRR], and [CRRR] are respectively obtained through... 13 The relative content fractions of methyl, methylene, and methine in POE elastomer measured by C-NMR; E is the bond dissociation energy difference required for methylene to dissociate into methylene radical and methine to dissociate into methine radical, with a value of 8.4 kJ / mol; R is the molar gas constant, with a value of 8.314 J / (mol·K); T is the reaction temperature when POE elastomer undergoes grafting reaction.

[0007] As a preferred scheme of the present application, the POE elastomer has a relative active site content RAS greater than 0.2 and less than 0.3, and a crosslinking grafting ratio CRG greater than 0.04 and less than 0.06 at a reaction temperature T.

[0008] As a preferred scheme of the present application, in the equation, the relative content fraction of methyl represented by [CR] is 5-40%, preferably 10-25%, the relative content fraction of methylene represented by [CRR] is 20-90%, preferably 50-80%, and the relative content fraction of methine represented by [CRRR] is 5-40%, preferably 10-25%.

[0009] As a preferred scheme of the present application, the initiator is selected from one or more of low-temperature initiators having a 1 min half-life temperature between 50-160°C, preferably t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, didecanoyl peroxide, di-t-butyl peroxide, t-amyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxypivalate, dibutyl peroxydicarbonate, dibenzoyl peroxide (BPO) and di(3,3,5-trimethylacetyl) peroxide.

[0010] As a preferred scheme of the present application, the auxiliary agent includes a grafting auxiliary monomer; and / or, The auxiliary agent is one or more of methyl methacrylate, acrylic acid, styrene, α-methyl styrene, epoxy resin; and / or, The addition amount of the auxiliary agent is 0.1-5% of the mass of the POE elastomer.

[0011] As a preferred scheme of the present application, the addition amount of the MAH is 0.5-2% of the mass of the POE elastomer; Preferably, the addition amount of the initiator is 0.1-0.5% of the mass of the POE elastomer.

[0012] As a preferred scheme of the present application, the reaction temperature of the melt grafting reaction is 50-160°C, preferably 120-160°C.

[0013] In order to obtain the raw materials required by the present application, the POE elastomer can be generally selected from commercially available products, or can be synthesized according to the known preparation process of the product, and the possible reaction parameters and process conditions can be adjusted according to the professional ability of the skilled person to obtain the POE elastomer meeting the properties defined in the foregoing.

[0014] As a non-limiting preparation method of the POE elastomer in the present application, for example, the following steps are included: S1, a first polymerization reaction: ethylene and α-olefin are sent to a reactor to copolymerize in the presence of a main catalyst and a cocatalyst to obtain a prepolymer; S2, Two-stage polymerization reaction: An organonitrile catalyst is added to the reactor, and α-olefins are added to continue the reaction to obtain POE elastomer.

[0015] The α-olefin is a C4-C10 α-olefin, preferably one or more of 1-butene, 1-hexene, and 1-octene; The main catalyst is a single-active-center metallocene catalyst and / or a post-metallocene catalyst, preferably a metallocene catalyst and / or a post-metallocene catalyst with titanium, zirconium or hafnium as the metal active center, more preferably one or more of dimethicyl(N-tert-butylamino)(tetramethylcyclopentadienyl)titanium chloride, dimethicyl(N-tert-butylamino)(tetramethylcyclopentadienyl)dimethyltitanium, dimethicyl(N-tert-butylamino)(fluorenyl)titanium chloride, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium chloride, diphenylmethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium chloride, diphenylmethylene(cyclopentadiene)(9-fluorenyl)zirconium chloride, and dimethyldimethicylalkylbis(2-methyl-4-phenyl-1-indenyl)zirconium chloride. The cocatalyst comprises an aluminum additive and optionally an organoboron additive; wherein the aluminum additive is selected from at least one of alkylaluminum, aluminum oxanes and their modifiers, preferably one or more of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, monochloroethylaluminum, sesquiethylaluminum, and dichloroethylaluminum. The organoboron additive is selected from one or more of triphenylmethyltetra(pentafluorophenyl)borate, tri(pentafluorophenyl)borate compounds, tetra(pentafluorophenyl)borate, N,N-dimethylanilinetetra(pentafluorophenyl)borate, dioctadecylmethyltertiary aminetetra(pentafluorophenyl)borate, and dihydrotallowylmethyltertiary aminetetra(pentafluorophenyl)borate.

[0016] Preferably, the molar ratio (Al / M) of metallic aluminum in the aluminum additive to the metal element in the main catalyst can be 50-1000, more preferably 100-500; Preferably, the molar ratio (B / M) of boron in the organoboron additive to the metal element in the main catalyst can be 1-3, preferably 1.5-2.5.

[0017] Preferably, the reaction in step S1 is carried out in an organic solvent; the organic solvent is selected from aliphatic hydrocarbon solvents and / or aromatic hydrocarbon solvents; Preferably, the aliphatic hydrocarbon solvent is selected from one or more of n-butane, isobutane, n-pentane, cyclopentane, methylcyclopentane, methylenecyclopentane, n-hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, n-heptane, n-octane, n-nonane, Isopar E; and the aromatic hydrocarbon solvent is selected from one or more of benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, dichlorotoluene.

[0018] Preferably, the addition amount of the main catalyst is 0.1-1.5 μmol / L in concentration in the solvent.

[0019] In the step S1, the molar ratio of the α-olefin to ethylene is 1:(0.5-4). In the step S1, the reaction temperature is 100-200 ℃, the reaction time is 5-18 min, and the ethylene pressure is 1-6 MPa gauge pressure.

[0020] In the step S2, the molar ratio of the α-olefin to ethylene is 1:(0.5-4).

[0021] The organic nickel catalyst is selected from one or more of organic coordination compounds having at least one ligand structure of phosphine ligand, carboxylic acid ligand, nitrogen ligand, preferably selected from bis(tri-tert-butylphosphine)nickel, chloro(1-naphthyl)bis(triphenylphosphine)-nickel, (1,1'-bis(diphenylphosphino)ferrocene)nickel dichloride, tetrakis(triphenylphosphine)nickel.

[0022] Preferably, the addition amount of the organic nickel catalyst is 0.1-1.5 μmol / L in concentration in the solvent.

[0023] In the step S2, the reaction temperature is 100-240 ℃, the reaction time is 10-50 min, and the ethylene pressure is 1-6 MPa gauge pressure.

[0024] The present application has the following beneficial effects: In the deep research on the grafting rate and crosslinking degree when affecting the POE grafting MAH, it is found that when the raw material properties of the POE elastomer are optimized, and the relative active site content RAS is 0.15 or more and the crosslinking grafting ratio CRG is 0.06 or less, the grafting reaction can obtain POE grafted particles with high grafting rate and low crosslinking degree at a lower initiation temperature, and the particles have more extensive application when used as toughening aids (such as PA toughening materials). DETAILED DESCRIPTION

[0025] The present application will be further described below by specific examples, and the examples described in the present application are only used to illustrate the present application and do not limit the scope of the present application.

[0026] Unless otherwise specified, all raw materials and reagents used in the following embodiments of the present invention can be purchased commercially. The performance testing method involved in this invention is as follows: (1) Grafting rate determination Weigh 0.5 g of sample, add 200 ml of xylene, heat and stir for 1 h, cool to room temperature, then pipette 10 ml of potassium hydroxide-ethanol solution (0.05 mol / L), heat under reflux for 2 h, then add 3 drops of 1 wt% phenolphthalein ethanol solution as an indicator, and back titrate with a hydrogen chloride-isopropanol solution (0.05 mol / L). Record the volume of hydrogen chloride-isopropanol solution consumed. The grafting rate is then calculated using the following formula.

[0027] Grafting rate (GD, %) =

[0028] The volume of potassium hydroxide-ethanol solution consumed. This represents the molar concentration of the potassium hydroxide-ethanol solution. The volume of hydrogen chloride-isopropanol solution consumed. denoted as , where is the molar concentration of the hydrogen chloride-isopropanol solution, and m is the sample mass.

[0029] (2) Melt index determination The melt flow index of the sample was tested according to GB / T 3682—2000 at 190℃ and 2.16kg load. The test time interval was 30s. The test sample was granular. The sample was measured in parallel 5 times and the average value was taken.

[0030] (3) Determination of gelation rate Accurately weigh 0.4 g of the sample to be tested, and extract it by refluxing with xylene using a Soxhlet extractor for 24 hours. Then wash it several times with ethanol and filter it. Dry the solid residue in a vacuum oven at 80°C for 12 hours until the mass no longer changes. Accurately measure the weight of the residue and calculate the gel content (GC) according to the following formula:

[0031] Where m1 represents the mass of the residue and m0 represents the mass of the sample to be tested.

[0032] (4) Carbon nuclear magnetic resonance spectrum ( 13 (C NMR) Polymer structural unit content through 13C NMR tests were performed to obtain. Data were collected using a Bruker 400 MHz spectrometer equipped with a Bruker cryoprobe. Data were collected using 160 scans, a 6 second pulse repetition delay, a sample temperature of 120 °C. All measurements were made on a non-spinning sample in lock mode. The sample was allowed to thermally equilibrate for 7 minutes prior to data acquisition.

[0033] Preparation Example 1 POE elastomer A was prepared according to the following method: S1, 351 g / h of ethylene, 714 g / h of 1-octene, 2169 g / h of solvent Isopar E, 289.3 mg / h of modified methylaluminoxane (7%wt Al) were fed into a reactor preheated to 140 °C with stirring, the reaction pressure was 3 MPa. 1.105 mg / h of the main catalyst diphenylmethylenecyclopentadiene (2,7-di-tert-butyl-fluorenyl) zirconium dichloride was injected into the reactor for copolymerization reaction, the reaction time was 15 min; the prepolymer was obtained.

[0034] S2, the reactor temperature was raised to 160 °C, the reaction pressure was unchanged, and 4.494 mg / h of chloro(1-naphthalene)bis(triphenylphosphine)-nickel was added, the amount of 1-octene was adjusted to 875 g / h, and the reaction was continued for 30 min. The polymer solution obtained after the reaction was discharged from the reactor outlet into a flash tank (170 °C, 2 MPa) for 10 min, then into a primary devolatilization (210 °C, 3 bar) and secondary devolatilization (220 °C, 1 bar) system in turn, 12 mg / h of H2O was added through a static mixer, and finally extruded and pelletized through a twin-screw extruder, to obtain POE elastomer A.

[0035] The physical property parameters of POE elastomer A are shown in Table 1.

[0036] Preparation Example 2 POE elastomer B was prepared according to the following method: S1, 234 g / h of ethylene, 583 g / h of 1-butene, 2200 g / h of solvent methylcyclohexane, 10.8 mg / h of ethylaluminoxane and 3.32 mg / h of triphenylcarbenium tetra(pentafluorophenyl)borate were fed into a reactor preheated to 140 °C with stirring, the reaction pressure was 2 MPa. 1.105 mg / h of the main catalyst dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl) titanium dichloride was injected into the reactor for copolymerization reaction, the reaction time was 15 min; the prepolymer was obtained.

[0037] S2, the reactor temperature was raised to 160°C, the reaction pressure was unchanged, and 1.396 mg / h of bis(tri-tert-butylphosphine)nickel was added, and the amount of 1-butene added was adjusted to 653 g / h, and the reaction was continued for 30 min. After the reaction was completed, the polymer solution obtained from the reactor outlet entered the flash tank (170°C, 2 MPa) for 10 min, and then entered the primary devolatilization (220°C, 3 bar) and secondary devolatilization (230°C, 1 bar) systems in turn, 2.7 mg / h of H2O was added through a static mixer, and finally, it was extruded and pelletized through a twin-screw extruder to obtain POE elastomer B.

[0038] The physical property parameters of POE elastomer B are shown in Table 1.

[0039] Preparation Example 3 POE elastomer C was prepared according to the following method: S1, 351 g / h of ethylene, 583 g / h of 1-butene, 2169 g / h of solvent Isopar E, and 115.7 mg / h of modified methylaluminoxane (7%wt Al) were fed into a reactor preheated to 140°C with stirring, and the reaction pressure was 3 MPa. 1.994 mg / h of the main catalyst bis(diphenylmethylenecyclopentadiene) (2,7-di-tert-butyl-fluorenyl) zirconium dichloride was injected into the reactor for copolymerization, and the reaction time was 15 min; a prepolymer was obtained.

[0040] S2, the reactor temperature was raised to 160°C, the reaction pressure was unchanged, and 1.396 mg / h of bis(tri-tert-butylphosphine)nickel was added, and the amount of 1-butene added was adjusted to 653 g / h, and the reaction was continued for 30 min. After the reaction was completed, the polymer solution obtained from the reactor outlet entered the flash tank (170°C, 2 MPa) for 10 min, and then entered the primary devolatilization (220°C, 3 bar) and secondary devolatilization (230°C, 1 bar) systems in turn, 2.7 mg / h of H2O was added through a static mixer, and finally, it was extruded and pelletized through a twin-screw extruder to obtain POE elastomer B.

[0041] The physical property parameters of POE elastomer C are shown in Table 1.

[0042] Preparation Example 4 POE elastomer D was prepared according to the following method: S1, 351 g / h of ethylene, 583 g / h of 1-butene, 2169 g / h of solvent Isopar E, and 115.7 mg / h of modified methylaluminoxane (7%wt Al) were fed into a reactor preheated to 140°C with stirring, and the reaction pressure was 3 MPa. 1.994 mg / h of the main catalyst bis(diphenylmethylenecyclopentadiene) (2,7-di-tert-butyl-fluorenyl) zirconium dichloride was injected into the reactor for copolymerization, and the reaction time was 15 min; a prepolymer was obtained.

[0043] S2, the reactor temperature was raised to 160°C, the reaction pressure was unchanged, and 3.324 mg / h of nickel tetra(triphenylphosphine) was added, the amount of 1-butene was adjusted to 653 g / h, and the reaction was continued for 30 min. After the reaction was completed, the polymer solution obtained from the reactor outlet was flashed into a flash tank (170°C, 2 MPa) for 10 min, then sequentially entered a primary devolatilization system (210°C, 3 bar) and a secondary devolatilization system (220°C, 1 bar), 6 mg / h of H2O was added through a static mixer, and finally was extruded and pelletized through a twin-screw extruder to obtain POE elastomer D.

[0044] The physical property parameters of POE elastomer D are shown in Table 1.

[0045] Preparation Example 5 POE elastomer E was prepared according to the following method: S1, 468 g / h of ethylene, 512 g / h of 1-butene, 2000 g / h of solvent n-hexane, 32.9 mg / h of triisobutylaluminum, and 4.43 mg / h of triscarbenium tetra(pentafluorophenyl)borate were transported into a reactor preheated to 140°C with stirring, and the reaction pressure was 4 MPa. 1.105 mg / h of the main catalyst diphenylmethylenecyclopentadiene (2,7-di-tert-butyl-fluorenyl) zirconium dichloride was injected into the reactor for copolymerization reaction, and the reaction time was 15 min; a prepolymer was obtained.

[0046] S2, the reactor temperature was raised to 160°C, the reaction pressure was unchanged, and 3.324 mg / h of nickel tetra(triphenylphosphine) was added, the amount of 1-butene was adjusted to 653 g / h, and the reaction was continued for 30 min. After the reaction was completed, the polymer solution obtained from the reactor outlet was flashed into a flash tank (170°C, 2 MPa) for 10 min, then sequentially entered a primary devolatilization system (210°C, 3 bar) and a secondary devolatilization system (220°C, 1 bar), 6 mg / h of H2O was added through a static mixer, and finally was extruded and pelletized through a twin-screw extruder to obtain POE elastomer D.

[0047] The physical property parameters of POE elastomer E are shown in Table 1.

[0048] Preparation Example 6 POE elastomer F was prepared according to the following method: S1, 234 g / h of ethylene, 583 g / h of 1-octene, 2169 g / h of solvent Isopar E, 115.7 mg / h of modified methylaluminoxane (7%wt Al) were fed into a reactor preheated to 140°C with stirring, the reaction pressure was 2 MPa. 1.105 mg / h of the main catalyst dimethylsilyl(N-tert-butylamino)(tetramethylcyclopentadienyl) titanium dichloride was injected into the reactor for copolymerization reaction, the reaction time was 15 min; the prepolymer was obtained.

[0049] S2, the reactor temperature was increased to 160°C, the reaction pressure was unchanged, and 2.247 mg / h of chloro(1-naphthyl)bis(triphenylphosphine)-nickel was added, the amount of 1-octene was adjusted to 653 g / h, and the reaction was continued for 30 min. The polymer solution obtained after the reaction was discharged from the reactor outlet into a flash tank (170°C, 2 MPa) for 10 min, then into a primary devolatilization (210°C, 3 bar) and secondary devolatilization (220°C, 1 bar) system in turn, 6 mg / h of H2O was added through a static mixer, and finally extruded and pelletized through a twin-screw extruder to obtain POE elastomer F.

[0050] The physical property parameters of POE elastomer F are shown in Table 1.

[0051] Comparative Preparation Example 1 ENGAGETM 8100 purchased from Dow Chemical was used as POE elastomer G.

[0052] Comparative Preparation Example 2 WANSUPER® 5007 purchased from Wanhua Chemical was used as POE elastomer H.

[0053] Table 1, Physical property parameters of POE elastomers

[0054] Examples 1-6 The POE elastomer, MAH, initiator, and auxiliary grafting monomer were mixed uniformly by a high-speed mixer. The reaction temperature in the twin-screw extruder was set to 120-160°C (the maximum temperature in the barrel was recorded as T), the screw rotation speed was 200 r / min, the mixed raw materials were added for melt grafting, and the extruded material was water-cooled and pelletized, and after sufficient drying, the POE grafted MAH was obtained. The raw material usage (mass parts) and reaction temperature and other process conditions in each example are shown in Table 2.

[0055] Table 2

[0056] The POE grafting MAH prepared in each example and comparative example was tested for grafting rate, melt index, and gel rate, and the results are shown in Table 3.

[0057] Application Example The POE grafting MAH prepared above was blended with PA6 at an addition amount of 10% of PA6, extruded and granulated through a twin-screw extruder, and injection molded to obtain a corresponding toughened nylon standard sample (80mm*10mm*4mm). The twin-screw extrusion temperature was 200℃, 220℃, 240℃, 240℃, 240℃, 240℃, 240℃, 240℃, 240℃, 240℃, 240℃, and 240℃, respectively; the twin-screw feeding was 10kg / h; the twin-screw rotation speed was 200rpm; the injection molding pressure during injection molding was 65Bar for the first stage, 65Bar for the second stage, and 20Bar for the third stage; and the injection molding speed was 35% for the first stage, 35% for the second stage, and 20% for the third stage.

[0058] The toughened nylon standard sample prepared in each application example was tested for notched impact strength, and the results are shown in Table 3.

[0059] Table 3

[0060] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the method of the present application, several improvements and supplements can also be made, which should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a high grafting rate and low crosslinking degree POE grafted MAH, characterized in that, The process comprises the following steps: POE elastomer is blended with MAH, initiator, optional auxiliary, and a melt grafting reaction is carried out in a screw extruder, and then extruded and granulated to obtain the POE grafted with MAH; The POE elastomer has a relative active site content RAS of 0.15 or more and a crosslinking grafting ratio CRG of 0.06 or less at a reaction temperature T; The relative active site content RAS is defined by the following equation 1: Equation 1 The crosslinking grafting ratio CRG is defined by the following equation 2: Equation 2 In the equations, [CR], [CRR] and [CRRR] are the relative content fractions of methyl, methylene and methine groups, respectively, as measured by 13 C-NMR measured relative content fractions of methyl, methylene, and methine groups in the POE elastomer; E is the bond dissociation energy difference required for methylene to dissociate into a methylene radical and for a methine radical to dissociate into a methine radical, with a value of 8.4 kJ / mol; R is the molar gas constant, with a value of 8.314 J / (mol·K); and T is the reaction temperature of the POE elastomer during the grafting reaction.

2. The method of claim 1, wherein the POE grafted MAH has a high grafting rate and a low crosslinking degree. The POE elastomer has a relative active site content RAS of greater than 0.2 and less than 0.3 and a crosslinking grafting ratio CRG of greater than 0.04 and less than 0.06 at a reaction temperature T.

3. The method of claim 1, wherein the POE grafted MAH has a high grafting rate and a low crosslinking degree. In the equation, the relative content fraction of [CR] is 5-40%, the relative content fraction of [CRR] is 20-90%, and the relative content fraction of [CRRR] is 5-40%; or, In the equation, the relative content fraction of [CR] is 10-25%, the relative content fraction of [CRR] is 50-80%, and the relative content fraction of [CRRR] is 10-25%.

4. The method of claim 1-3, wherein the method is characterized by, The initiator is selected from low-temperature initiators with a 1 min half-life temperature between 50-160°C; or The initiator is selected from one or more of t-butyl peroxy-2-ethylhexanoate, t-butyl peroxypivalate, didecanoyl peroxide, di-t-butyl peroxide, t-amyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxypivalate, dibutyl peroxydicarbonate, dibenzoyl peroxide, and di(3,3,5-trimethylacetyl) peroxide.

5. The method of claim 1-3, wherein the method is characterized by, The auxiliary includes a grafting monomer; and / or The auxiliary is one or more of methyl methacrylate, acrylic acid, styrene, alpha-methyl styrene, and epoxy resin; and / or The auxiliary is added in an amount of 0.1-5% of the mass of the POE elastomer.

6. The method of claim 1-3, wherein the method of preparing a high grafting rate and low crosslinking degree POE grafted MAH is characterized in that, The MAH is added in an amount of 0.5-2% of the mass of the POE elastomer; and / or The initiator is added in an amount of 0.1-0.5% of the mass of the POE elastomer.

7. The process for preparing a high grafting rate and low crosslinking degree POE grafted MAH according to any one of claims 1-3, characterized in that, The reaction temperature of the melt grafting reaction is 50-160°C; or The reaction temperature of the melt grafting reaction is 120-160°C.

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