A heat-conducting pressure-resistant polyolefin pipe special material and a preparation method thereof

Abstract

This application relates to a special material for thermally conductive and pressure-resistant polyolefin pipes and its preparation method. The special material comprises a polyethylene resin blend matrix, pretreated filler, maleic anhydride-grafted polyethylene, polyvinyl chloride / polyethyl methacrylate (PVC / PEMA) polymer, carbon fiber, and stabilizer. The preparation method includes adding the polyethylene resin blend matrix, PVC / PEMA polymer, maleic anhydride-grafted polyethylene, pretreated filler, carbon fiber, antioxidant, and zinc stearate into a high-speed mixer and mixing them. Then, the mixture is blended with vinyltrimethoxysilane and dicumyl peroxide using a twin-screw extruder at 195°C and 280 rpm, and granulated to obtain the special material for thermally conductive and pressure-resistant polyolefin pipes. The resulting special material has both high thermal conductivity and pressure resistance, making it suitable for manufacturing polyolefin pipes. It solves the problems of poor thermal conductivity and insufficient pressure resistance of polyolefin pipes and can be applied to geothermal, underfloor heating, and chemical fluid transportation systems.

Description

Technical Field

[0001] This application relates to the field of polymer compound technology, and in particular to a thermally conductive and pressure-resistant polyolefin pipe material and its preparation method. Background Technology

[0002] In the fields of energy transmission, underfloor heating, and industrial heat exchange pipelines, the market urgently needs polyolefin pipes that combine high thermal conductivity with long-term pressure resistance. Current technologies mainly improve thermal conductivity by filling with metals, ceramics, or carbon materials, or improve strength through fiber reinforcement and cross-linking reactions. However, these methods still have problems. While filling with large amounts of inorganic particles can increase thermal conductivity, their poor compatibility with polyolefins leads to weak interfacial bonding, stress concentration, and penetration channels, while also reducing toughness, increasing the risk of brittle fracture, and affecting processing fluidity. Although using short fiber reinforcement or chemical cross-linking can improve strength, it brings uneven thermal conductivity, decreased long-term fatigue resistance, and microscopic defects caused by cross-linking side reactions, affecting material life.

[0003] Current technologies fail to comprehensively consider the interactions between fillers, reinforcements, and the matrix. Under actual high-temperature and high-pressure conditions, the differences in thermal expansion between different materials lead to the accumulation of interfacial stress. Traditional mechanical mixing is insufficient to resolve this stress, and cross-linking structures can actually exacerbate internal stress. During long-term use, moisture or chemical media can seep in along interfacial defects, triggering hydrolysis and corrosion, forming a thermo-chemical coupling destructive cycle. This ultimately leads to filler detachment, microcrack propagation, and premature pipe failure. These problems are highly insidious and difficult to detect in short-term testing, posing a serious threat to the long-term safety of the system.

[0004] In summary, there is an urgent need in the market to develop a new type of thermally conductive and pressure-resistant polyolefin pipe material and its preparation method. Summary of the Invention

[0005] This application provides a thermally conductive and pressure-resistant polyolefin pipe material and its preparation method to solve the problems mentioned in the background art.

[0006] To address the aforementioned technical problems, this application discloses a thermally conductive and pressure-resistant polyolefin pipe material, comprising a polyethylene resin blend matrix, pretreated fillers, maleic anhydride-grafted polyethylene, PVC / PEMA polymer, carbon fibers, and stabilizers.

[0007] Furthermore, by weight, it comprises 94-110 parts of polyethylene resin blend matrix, 24.3-26.4 parts of pretreated filler, 6-9.2 parts of maleic anhydride grafted polyethylene, 12-16 parts of PVC / PEMA polymer, 10-13 parts of carbon fiber and 1.8-3 parts of stabilizer.

[0008] Furthermore, the pretreatment filler includes graphene oxide and modified silica, comprising 0.6 to 1 parts by weight of graphene oxide and 23.7 to 25.4 parts by weight of modified silica.

[0009] Furthermore, the method for preparing the polyethylene resin blend matrix includes mixing 15-20 parts by weight of linear low-density polyethylene, 30-42 parts by weight of low-density high-density polyethylene and 5-15 parts by weight of polystyrene resin at 260 rpm and 50°C for minutes to obtain the polyethylene resin blend matrix.

[0010] Furthermore, the stabilizer includes vinyltrimethoxysilane, dicumyl peroxide, antioxidant, and zinc stearate.

[0011] Furthermore, the stabilizer comprises, by weight, 1.4 to 1.8 parts of vinyltrimethoxysilane, 0.15 to 0.4 parts of dicumyl peroxide, 0.16 to 0.4 parts of antioxidant and 0.1 to 0.4 parts of zinc stearate.

[0012] Furthermore, the antioxidants include antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1.

[0013] Furthermore, the preparation method of the pretreated filler includes mixing graphene oxide and modified silica, spraying an ethanol solution containing silane coupling agent KH-550, stirring at 80°C and 600 rpm, and vacuum drying at 120°C for 4 hours.

[0014] Furthermore, the preparation method of the PVC / PEMA polymer includes dissolving polyvinyl chloride and polyethyl methacrylate in N,N-dimethylformamide solvent and stirring, adding zinc trifluoromethanesulfonate salt and stirring at room temperature, adding ionic liquid EMIMTFSI and stirring to obtain a mixture, and then nano-... The filler dispersion was dispersed in DMF and ultrasonically treated to obtain a filler dispersion. The filler dispersion was added to the mixture and stirred, and then vacuum dried to obtain PVC / PEMA polymer.

[0015] This application also discloses a method for preparing the thermally conductive and pressure-resistant polyolefin pipe material. The preparation method includes adding polyethylene resin blend matrix, PVC / PEMA polymer, maleic anhydride grafted polyethylene, pretreated filler, carbon fiber, antioxidant and zinc stearate into a high-speed mixer and mixing them. Then, the mixture is blended with vinyltrimethoxysilane and dicumyl peroxide in a twin-screw extruder at 195°C and 280 rpm, and granulated to obtain the thermally conductive and pressure-resistant polyolefin pipe material.

[0016] Furthermore, the mixing conditions are 1200 rpm for 8-10 minutes, followed by vacuum granulation at -0.08 MPa to obtain a thermally conductive and pressure-resistant polyolefin pipe material.

[0017] The mechanisms of action of the aforementioned raw material components are as follows: Firstly, the linear low-density polyethylene in the polyethylene resin blend matrix possesses high toughness and resistance to environmental stress cracking. Low-density high-pressure polyethylene enhances melt flowability and processability. Polystyrene resin, as a rigid support and a non-polyolefin component, improves the matrix modulus through physical blending, providing a framework for compressive strength. This blend system serves as a platform for other components during twin-screw extrusion, ensuring overall material uniformity. Secondly, the graphene oxide in the pretreated filler, as a two-dimensional nanosheet material, constructs in-plane high-speed thermal conductivity channels in the matrix due to its ultra-high specific surface area and honeycomb-like carbon atom arrangement. Its edge oxygen-containing functional groups form chemical bonds with modified silica particles through the bridging effect of the silane coupling agent KH-550. After surface hydroxylation treatment, the modified silica exhibits oleophilic properties, and its spherical geometry effectively fills the gaps between graphene oxide sheets, forming a graded thermally conductive network. This multi-scale filler combination not only reduces interfacial thermal resistance but also suppresses the propagation of microcracks caused by localized stress concentration by dispersing the stress field through rigid particles. Thirdly, maleic anhydride-grafted polyethylene acts as a key compatibility medium. During high-temperature shearing, the anhydride groups on its molecular chain undergo esterification and condensation reactions with the hydroxyl groups of the pretreated filler, forming a covalent transition layer at the inorganic / organic interface. The polyethylene structure of the grafted main chain, together with the polyethylene resin blended with the matrix resin, enhances the interfacial bonding strength. This dual anchoring effect significantly reduces the difference in expansion coefficients between the thermally conductive filler and the resin, avoiding interfacial delamination caused by thermal mismatch during thermal cycling. Fourthly, the PVC / PEMA polymer constitutes a unique stress-buffering phase. Polar chlorine atoms in the PVC segments and ester groups of polymethyl methacrylate form ionic cluster crosslinking points under the catalysis of zinc trifluoromethanesulfonate. The intervention of the ionic liquid EMIMTFSI further induces phase separation, producing a nanoscale bicontinuous structure. Nano-titanium dioxide particles are dispersed in this polymer phase, and their high modulus preferentially disperses the load when subjected to internal pressure. When the pipe is subjected to external impact or pressure fluctuations, this phase dissipates energy through reversible ionic bond breakage and recombination. Simultaneously, its hydrophobic side chains form a molecular barrier, preventing water vapor from penetrating to the interface and causing hydrolytic corrosion. Fifthly, carbon fiber, as a one-dimensional reinforcing unit, exhibits increased mechanical bonding with the resin due to the groove structure created by its surface oxidation treatment. In the high-shear flow field of the extrusion process, the fibers align oriented along the flow direction, forming an axial reinforcing skeleton that penetrates the material. This oriented structure not only significantly enhances the circumferential tensile strength to resist internal pressure expansion, but its axial carbon atom lattice arrangement also becomes a rapid channel for longitudinal heat conduction. The physical interlocking between the fiber ends and the pretreated filler further strengthens the connectivity of the three-dimensional thermal conductivity network. Antioxidant 1010 captures macromolecular free radicals to block degradation chain reactions, while antioxidant 168 decomposes hydrogen peroxide to inhibit side reactions.The metal ions of zinc stearate coordinate with the carboxyl groups of the resin to form a lubricating layer, which reduces melt viscosity to ensure the processability of the high-filler system and improves the inner wall smoothness of the extruded pipe to reduce defect sources. This multi-component synergy achieves an ideal balance between crosslinking density and melt flowability, ensuring that the material has both compressive strength and long-term thermal stability.

[0018] The mechanism of the above preparation method is as follows: The intense mechanical stirring in the high-speed mixing stage of this application generates a centrifugal vortex field, which promotes the pre-dispersion of the matrix resin and various additives. When the rotation speed reaches a specific threshold, the material forms turbulent convection in the mixing chamber, and components with large density differences, such as carbon fibers and pretreated fillers, are forced to mix by convection. This process allows maleic anhydride-grafted polyethylene to be pre-coated on the filler surface, and its anhydride groups are partially activated under the action of frictional heating, creating pre-reaction conditions for interfacial bonding in the subsequent extrusion process. The combined screw design of the twin-screw extruder forms a segmented reaction field. The conveying section achieves gentle heating and melting of the material through a deep screw groove structure, avoiding premature decomposition of heat-sensitive additives. The high-shear meshing block design of the melting section generates a tensile flow field, which promotes the high orientation of carbon fibers along the extrusion direction, while tearing the pretreated filler clusters into micro- and nano-scale dispersion units. The graphene oxide sheets undergo rotational slip under the action of shear force, and finally arrange themselves parallel to the flow direction to maximize the heat conduction path. Vinyltrimethoxysilane and dicumyl peroxide are injected into the melt homogenization section. The free radicals generated by the thermal decomposition of the peroxide abstract the methoxy group of the silane to form active siloxane free radicals. The vinyl group of the silane participates in the copolymerization reaction, introducing flexible segments into the crosslinking network. This process reaches the reaction equilibrium point at a specific temperature, avoiding both insufficient crosslinking due to low temperatures and chain breakage and degradation caused by high temperatures. The ionic liquid in the PVC / PEMA polymer undergoes a sudden viscosity change under high-temperature shear. In the initial stage, its low viscosity promotes the uniform dispersion of nano-titanium dioxide. When the temperature rises to the phase transition critical point, the Coulombic interaction between the imidazole cations and polymer anions is enhanced, and the viscosity of the system increases sharply, forming a solid-like behavior. This rheological transformation allows the phase to maintain structural integrity during blending, avoiding excessive shearing and breakage by the screw, and ensuring that it forms a continuous and penetrating reinforcing network in the matrix. The negative pressure environment of the vacuum granulation process produces a dual effect. At the macroscopic level, volatile small molecules in the melt, such as residual solvents and crosslinking byproducts, are forcibly removed, eliminating stress concentration points caused by bubbles. At the microscopic level, negative pressure causes directional relaxation of the resin molecular chains, eliminating the frozen orientation stress formed by the initial shearing. This process, combined with the rapid phase change of circulating water cooling, creates a pre-stressed compression state at the filler-resin interface, partially offsetting the tensile stress generated by thermal expansion during pipe service. The timing of the addition of modified carbon fibers is precisely designed. Adding them too early will result in excessive shearing and a loss of aspect ratio, while adding them too late will lead to uneven dispersion. In this method, the modified carbon fibers are introduced through a side feed port after the resin is completely melted. The fibers are encapsulated by the formed viscoelastic melt, and gentle dispersion is achieved through melt dragging force. Grooves on the fiber surface capture free pretreated filler particles, forming physical rivets. This in-situ composite effect creates a spatial synergistic effect between the thermally conductive and mechanically reinforcing units. The resulting special material particles have a gradient structure. The particle surface is enriched with stabilizers and zinc stearate, ensuring flowability control during remelting.The core region of the particles maintains a highly oriented carbon fiber skeleton, and this structural memory effect ensures the seamless transfer of thermal conductivity and pressure resistance during tube extrusion. This structural design minimizes performance fluctuations during repeated processing.

[0019] Compared with the prior art, this application provides a special material for thermally conductive and pressure-resistant polyolefin pipes and its preparation method, which has the following beneficial effects:

[0020] 1. This application utilizes a multiphase interfacial energy synergistic enhancement method. The PVC / PEMA polymer forms a bicontinuous phase structure through the catalytic action of the ionic liquid EMIMTFSI and zinc trifluoromethanesulfonate. This structure constructs an interpenetrating network in the polyolefin matrix, which not only improves compressive strength but also enhances the interfacial thermal conductivity pathway through the nano-dispersion, thus solving the stress concentration problem caused by traditional fillers.

[0021] 2. The polyethylene resin blend matrix involved in this application withstands internal pressure expansion force through molecular entanglement and PS rigid support. Its long branched structure delays crack propagation in long-term hydrostatic testing and contributes to high LTHS failure time. The melt flow properties of the polyethylene resin blend matrix enhance the dispersion of pretreated fillers and carbon fibers, and can also synergize with maleic anhydride-grafted polyethylene to reduce thermal expansion mismatch. Meanwhile, graphene oxide and modified silica are pretreated with silane coupling agent KH-550 to form a hierarchical thermally conductive network in the matrix: graphene oxide provides in-plane high thermal conductivity channels, and modified silica fills the gaps, making the interface tightly bonded and avoiding the initiation of microcracks.

[0022] 3. The synergistic crosslinking of vinyltrimethoxysilane (A-171) and dicumyl peroxide (Luperox 101) in this application, combined with antioxidant 1010 / 168 in a 1:1 ratio, achieves a controllable free radical reaction during extrusion at 195°C. This ensures both increased crosslinking density and improved pressure resistance, with a LTHS failure time of 8763h, while also inhibiting thermal degradation, effectively avoiding the byproduct defects of traditional crosslinking.

[0023] 4. In this application, maleic anhydride-grafted polyethylene is used as a compatibilizer. Its anhydride groups react with the hydroxyl groups of the pretreated filler, and the carbon fibers are oriented under high shear at 280 rpm, which synergistically improves axial thermal conductivity and circumferential strength.

[0024] 5. This application uses vacuum granulation to eliminate internal stress in air bubbles, a zinc stearate lubrication system to ensure melt flowability under high filling volume, and the hydrophobicity of the ionic liquid EMIMTFSI to inhibit water vapor penetration, thus blocking interfacial corrosion from a chemical perspective. Attached Figure Description

[0025] Figure 1 This is a SEM image of the thermally conductive and pressure-resistant polyolefin pipe material prepared in Example 1 of this application. Detailed Implementation

[0026] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0027] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and does not specifically refer to any order or sequence, nor is it intended to limit this application. They are merely used to distinguish components or operations described using the same technical terms and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions and features of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0028] Unless otherwise specified, the examples and comparative examples are parallel experiments with the same components, component content, preparation steps, and preparation parameters. The experimental methods in the following examples are conventional methods unless otherwise specified. Unless otherwise specified, the experimental materials used in the following examples are analytical reagents (AR) and were all purchased from commercial channels.

[0029] Example 1: This example discloses a thermally conductive and pressure-resistant polyolefin pipe material, which includes 100 parts by weight of polyethylene resin blend matrix, 25.8 parts by weight of pretreated filler, 8 parts by weight of maleic anhydride grafted polyethylene, 15 parts by weight of PVC / PEMA polymer, 12 parts by weight of carbon fiber and 2.1 parts by weight of stabilizer.

[0030] The pretreatment filler comprises 0.8 parts by weight of graphene oxide and 25 parts by weight of modified silica.

[0031] The stabilizer comprises, by weight, 1.5 parts vinyltrimethoxysilane, 0.2 parts dicumyl peroxide, 0.2 parts antioxidant and 0.2 parts zinc stearate.

[0032] The antioxidants comprise, by weight, 0.1 parts antioxidant 1010 and 0.1 parts antioxidant 168.

[0033] The method for preparing the polyethylene resin blend matrix includes mixing 15-20 parts by weight of linear low-density polyethylene, 30-42 parts by weight of low-density high-pressure polyethylene and 5-15 parts by weight of polystyrene resin at 260 rpm and 50°C for minutes to obtain the polyethylene resin blend matrix.

[0034] The preparation method of the pretreated filler, by weight, includes placing 0.8 parts of graphene oxide and 25 parts of modified silica in a high-speed mixer, spraying an ethanol solution containing 0.08 parts of silane coupling agent KH-550, stirring at 80°C and 600 rpm for 25 minutes, and vacuum drying at 120°C for 4 hours to obtain the pretreated filler.

[0035] The preparation method of the PVC / PEMA polymer includes dissolving 0.10 g of polyvinyl chloride (PVC) and 0.255 g of polyethyl methacrylate (PEMA) in N,N-dimethylformamide (DMF) solvent and stirring, adding 0.14 g of zinc trifluoromethanesulfonate salt and stirring at room temperature, adding 0.4 g of ionic liquid EMIMTFSI and stirring for 5 hours to obtain a mixture, and then nano-... The filler dispersion was obtained by dispersing in 5 mL of DMF and sonicating for 1 hour. The filler dispersion was then added to the mixture and stirred at room temperature for 6 hours. Finally, the mixture was vacuum dried at 60°C for 24 hours to obtain the PVC / PEMA polymer.

[0036] A method for preparing a thermally conductive and pressure-resistant polyolefin pipe material includes the following steps:

[0037] By weight, 100 parts of polyethylene resin blend matrix, 15 parts of PVC / PEMA polymer, 8 parts of maleic anhydride grafted polyethylene, 1 part of pretreated filler, 12 parts of carbon fiber, 0.2 parts of antioxidant and 0.1 parts of zinc stearate were added to a high-speed mixer and mixed at 1200 rpm for 8 minutes. The mixture was then blended with 1.5 parts of vinyltrimethoxysilane and 0.2 parts of dicumyl peroxide at 195°C and 280 rpm using a twin-screw extruder, and granulated under vacuum at -0.08 MPa to obtain a special material for thermally conductive and pressure-resistant polyolefin pipes.

[0038] Application Example 1

[0039] The thermally conductive and pressure-resistant polyolefin pipe material is extruded through a rotating mandrel die. The mandrel and die rotate in opposite directions at 12 rpm, and the material is melt-extruded at 205°C. After vacuum shaping and water cooling at 15°C, the thermally conductive and pressure-resistant polyolefin pipe is obtained.

[0040] Specifically, the mandrel diameter of the rotating mandrel die is 30 mm, the die gap is 2.5 mm, the extruder temperature is 170℃ in zone 1, 180℃ in zone 2, 195℃ in zone 3, 200℃ in zone 4, and 205℃ at the die, the melt pressure is 28 MPa, the traction speed is 1.8 m / min, the vacuum setting pressure is -0.1 MPa, and the cooling water temperature is 15℃.

[0041] The thermally conductive and pressure-resistant polyolefin pipe material prepared in Example 1 was scanned using a scanning electron microscope, and the results are as follows: Figure 1As shown in the figure, the graphene oxide sheets are arranged in a parallel stacked orientation, and the modified silica particles uniformly fill the gaps between the sheets. There are no visible gaps at the interface between the carbon fiber and the matrix, which confirms the precise control of the microstructure by the mixing process. The image shows the dispersion state of the filler: the graphene oxide (sheet-like) and the modified silica (spherical) are uniformly distributed in the matrix, with no visible agglomerates. The pretreatment process effectively improves compatibility. The quality of the interface bonding can also be seen: there are no gaps or debonding phenomena between the filler and the resin matrix. The compatibility of maleic anhydride-grafted polyethylene and the twin-screw high-shear process achieve impregnation.

[0042] Example 2: This example discloses a special material for thermally conductive and pressure-resistant polyolefin pipes, comprising, by weight, 94 parts of polyethylene resin blend matrix, 24.3 parts of pretreated filler, 6 parts of maleic anhydride grafted polyethylene, 12 parts of PVC / PEMA polymer, 10 parts of carbon fiber, and 1.8 parts of stabilizer. The pretreated filler comprises, by weight, 0.6 parts of graphene oxide and 23.7 parts of modified silica. The stabilizer comprises, by weight, 1.4 parts of vinyltrimethoxysilane, 0.15 parts of dicumyl peroxide, 0.16 parts of antioxidant, and 0.1 parts of zinc stearate. The antioxidant comprises, by weight, 0.8 parts of antioxidant 1010 and 0.8 parts of antioxidant 168. Other contents are the same as in Example 1.

[0043] Example 3: This example discloses a special material for thermally conductive and pressure-resistant polyolefin pipes, comprising, by weight, 110 parts of polyethylene resin blend matrix, 26.4 parts of pretreated filler, 9.2 parts of maleic anhydride grafted polyethylene, 16 parts of PVC / PEMA polymer, 13 parts of carbon fiber, and 3 parts of stabilizer. The pretreated filler comprises, by weight, 1 part of graphene oxide and 25.4 parts of modified silica. The stabilizer comprises, by weight, 1.8 parts of vinyltrimethoxysilane, 0.4 parts of dicumyl peroxide, 0.4 parts of antioxidant, and 0.4 parts of zinc stearate. The antioxidant comprises, by weight, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168. Other contents are the same as in Example 1.

[0044] Comparative Example 1

[0045] The difference from Example 1 is the absence of an equal part by weight of PVC / PEMA polymer; otherwise, they are the same.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that the pretreated packing material in equal parts by weight is replaced with untreated packing material, otherwise the same.

[0048] Performance testing

[0049] Performance tests were conducted on the examples and comparative examples. Thermal conductivity was tested according to ASTM E1461. The special material was pressed into discs with a diameter of 12.7 mm and a thickness of 1 mm, and the thermal conductivity at 25 °C was tested. Burst pressure (short-term pressure resistance) was tested according to ISO 1167. The special material was extruded into pipes with an outer diameter of 32 mm and a wall thickness of 3 mm. The pipes were pressurized at a rate of 0.5 MPa / s under water pressure until they ruptured, and the peak pressure was recorded. Long-term hydrostatic strength was tested according to ISO 9080. A ring stress of 4.0 MPa was applied in a 95 °C water bath, and the pipe failure time was recorded. Melt flow rate was tested according to ISO 1133 (190 °C, 2.16 kg load, unit: g / 10 min). The results are shown in Table 1.

[0050] Table 1

[0051]

[0052] As can be seen from Table 1, Example 1 has the best overall performance. The PVC / PEMA polymer reduces the thermal conductivity and shortens the LTHS failure time. It can significantly improve the interfacial bonding force and long-term pressure resistance through the ion cross-linking network. The untreated filler causes the thermal conductive network to be discontinuous, which reduces the thermal conductivity.

[0053] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. If such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A special material for thermally conductive and pressure-resistant polyolefin pipes, characterized in that, By weight, it comprises 94-110 parts of polyethylene resin blend matrix, 24.3-26.4 parts of pretreated filler, 6-9.2 parts of maleic anhydride grafted polyethylene, 12-16 parts of PVC / PEMA polymer, 10-13 parts of carbon fiber and 1.8-3 parts of stabilizer; The pretreatment filler includes graphene oxide and modified silica, comprising 0.6 to 1 parts by weight of graphene oxide and 23.7 to 25.4 parts by weight of modified silica; The method for preparing the polyethylene resin blend matrix includes mixing 15-20 parts by weight of linear low-density polyethylene, 30-42 parts by weight of low-density high-pressure polyethylene and 5-15 parts by weight of polystyrene resin at 50°C and 260 rpm for minutes to obtain the polyethylene resin blend matrix. The stabilizer comprises vinyltrimethoxysilane, dicumyl peroxide, an antioxidant, and zinc stearate; the stabilizer comprises, by weight, 1.4 to 1.8 parts vinyltrimethoxysilane, 0.15 to 0.4 parts dicumyl peroxide, 0.16 to 0.4 parts antioxidant, and 0.1 to 0.4 parts zinc stearate; The antioxidants include antioxidant 1010 and antioxidant 168 in a weight ratio of 1:1; The preparation method of the pretreated filler includes mixing graphene oxide and silicon dioxide, spraying an ethanol solution containing silane coupling agent KH-550, stirring at 80°C and 600 rpm, and vacuum drying at 120°C for 4 hours. The preparation method of the PVC / PEMA polymer includes dissolving polyvinyl chloride and polyethyl methacrylate in N,N-dimethylformamide (DMF) solvent and stirring, adding zinc trifluoromethanesulfonate salt and stirring at room temperature, adding ionic liquid EMIMTFSI and stirring to obtain a mixture, dispersing nano-titanium dioxide in DMF, ultrasonically treating to obtain a filler dispersion, adding the filler dispersion to the mixture and stirring, and vacuum drying to obtain the PVC / PEMA polymer.

2. A method for preparing a thermally conductive and pressure-resistant polyolefin pipe material as described in claim 1, characterized in that, The preparation method includes adding polyethylene resin blend matrix, PVC / PEMA polymer, maleic anhydride grafted polyethylene, pretreated filler, carbon fiber, antioxidant and zinc stearate into a high-speed mixer and mixing them. Then, the mixture is blended with vinyltrimethoxysilane and dicumyl peroxide in a twin-screw extruder at 195°C and 280 rpm, and granulated to obtain a thermally conductive and pressure-resistant polyolefin pipe material.

3. The preparation method according to claim 2, characterized in that, The mixing conditions are 1200 rpm for 8-10 minutes, followed by vacuum granulation at -0.08 MPa to obtain a thermally conductive and pressure-resistant polyolefin pipe material.

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