Geomembrane composite edge material recycling process

Abstract

This application relates to the field of polymer material recycling technology and discloses a process for recycling and reusing edge materials of composite geomembranes, including the following steps: pulverized waste high-density polyethylene / polyester composite geomembrane is mixed with a surface swelling catalyst and kept at a constant temperature under micro-positive pressure to allow micro-alcohololysis of the polyester microfiber surface layer to construct a mesoporous swelling layer. Subsequently, in the first temperature zone of the extruder, a reverse threaded element is used to impede the melt flow, forming a sealing plug to cut off the gas path. In the second temperature zone, preheated maleic anhydride-grafted polyethylene and an antioxidant are injected under high pressure, utilizing the negative temperature difference pressing effect to wedge the grafted macromolecular chains into the mesopores and induce a semi-esterification reaction. Finally, in the third temperature zone, vacuum is used to remove volatiles, driving the semi-ester structure to dehydrate and transform into a fully ester structure, completing the interface anchoring. This invention reconstructs a compatible interface through the synergistic effect of physical topological entanglement and chemical crosslinking, effectively inhibiting matrix degradation and improving the mechanical properties of the recycled particles.

Description

Technical Field

[0001] This invention relates to the field of polymer material recycling technology, specifically to a process for recycling and reusing edge materials of composite geomembranes. Background Technology

[0002] Composite geomembranes are typically composed of a high-density polyethylene (HDPE) impermeable substrate and a polyester nonwoven fabric reinforcing layer, and are widely used in various seepage control projects. During the production and installation of composite geomembranes, a large amount of waste material is inevitably generated. Recycling and reusing this multiphase composite waste material not only conserves polymer resin resources but also meets the requirements of solid waste reduction and resource utilization.

[0003] High-density polyethylene (HDPE) and polyester face severe interfacial compatibility barriers during recycling due to significant differences in their molecular structures and surface energies. HDPE is a typical nonpolar macromolecule with a relatively low melting temperature; while polyester contains highly polar ester groups and benzene ring structures in its main chain, resulting in a higher melting temperature and greater rigidity. In conventional heated blending extrusion recycling processes, these two resins are thermodynamically completely incompatible. In the molten mixed state, strong interfacial repulsion exists between the nonpolar and polar phases, leading to severe macroscopic phase separation structures remaining inside the molded composite material. When the material is subjected to external stress, stress concentration and microcracks easily occur at the fragile phase interfaces, causing a sharp deterioration in the macroscopic mechanical properties of the recycled material, such as impact strength and elongation at break, making it difficult to meet the engineering application standards of subsequent recycled products.

[0004] To improve the compatibility of this multiphase system, existing recycling methods generally employ the direct addition of reactive compatibilizers such as maleic anhydride grafts during the blending stage. However, in conventional high-temperature blending extrusion environments, the solid-phase polyester microfiber surface exhibits a dense structure and significant steric hindrance. The active segments of macromolecular compatibilizers struggle to effectively overcome this resistance and penetrate the polyester chain, resulting in interfacial bonding remaining at a shallow, two-dimensional contact level, failing to form deep three-dimensional physical entanglement and a dense chemical cross-linking network. Simultaneously, in conventional extrusion processing lacking special pressure and vacuum field interventions, residual free moisture and small-molecule byproducts released during esterification cannot be rapidly eliminated. Under the combined effects of high temperature and the strong shear of a twin-screw extruder, these small molecules easily trigger high-temperature hydrolysis of the polyester phase and high-temperature thermo-oxidative degradation of the polyethylene matrix. Random chain scission of the macromolecular backbone leads to a significant decrease in the system's average molecular weight, macroscopically manifested as an abnormally high melt flow rate and deteriorated processing stability, ultimately resulting in further loss of the comprehensive mechanical properties of the recycled particles. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a process for recycling and reusing edge materials of composite geomembranes. This process solves the problems of macroscopic phase separation, high-temperature degradation of the matrix, and rapid deterioration of mechanical properties in recycled high-density polyethylene / polyester composite geomembranes during conventional recycling and processing, which are caused by severe thermodynamic incompatibility between the two phases and the difficulty of conventional compatibilizers to penetrate deeply into the interface.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a process for recycling and reusing edge materials of composite geomembranes, comprising the following steps: This invention provides a process for recycling and reusing edge materials of composite geomembranes, employing the following technical solution: A process for recycling and reusing edge materials of composite geomembranes includes the following steps: heating 80-120 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material to 85-95°C, uniformly spraying 0.65-1.55 parts by weight of surface swelling catalyst liquid and mixing; conveying the mixed material to an insulated homogenization silo, and maintaining a constant temperature of 110-120°C and nitrogen gas to maintain a micro-positive pressure of 0.02-0.05 MPa for 2.0-4.0 hours, so that the surface layer of polyester fibers undergoes micro-alcoholization and a mesoporous swelling layer is constructed; The material is fed into the first temperature zone of a co-rotating twin-screw extruder at 150-160℃. The reverse threaded element at the end of the first temperature zone impedes the melt flow, forming a dynamic melt seal that cuts off the gas path. The material enters the second temperature zone at 185-195℃, where 3.0-8.0 parts by weight of maleic anhydride-grafted polyethylene and 0.1-0.3 parts by weight of antioxidant, preheated to 145-155℃ in a side-feed independent barrel, are forcibly injected into the main screw channel at a pressure of 5.0-10.0 MPa using a side gear pump. The negative temperature difference impact effect forces the grafted macromolecular chains to wedge into the mesoporous swelling layer and undergo a semi-esterification reaction. The material enters the third temperature zone at 190-195℃, where volatiles are removed under a vacuum of -0.08 to -0.095 MPa. At the same time, the semi-ester structure at the phase interface is dehydrated and converted into a full ester structure to complete the interface anchoring. The material is then extruded and pelletized.

[0007] By adopting the above technical solution, the compatibility interface of multiphase composite materials is reconstructed by using multi-physics field synergistic intervention and interface stepwise chemical cross-linking mechanism, thus obtaining recyclable particles with excellent macroscopic mechanical properties.

[0008] The specific reaction process and mechanism are as follows: The first stage involves solid-phase micro-alcoholization and spatial pre-structuring. During the heat-preservation and homogenization stage, ethylene glycol in the surface-swelling catalytic solution undergoes micro-alcoholization with the ester bonds on the surface of the polyester macromolecular chains under the catalysis of tetrabutyl titanate. The high-molecular-weight polyester molecular chains break down on the surface, producing short-chain structures with terminal hydroxyl groups. This chemical depolymerization process forms a deep amorphous mesoporous swelling layer on the surface of the polyester microfibers, providing a three-dimensional physical space for the penetration of macromolecular compatibilizers.

[0009] The second stage involves the construction of a fluid flow obstruction and micro-positive pressure system. In the first temperature zone, the reverse-threaded element exerts a strong shearing and flow obstruction effect on the molten high-density polyethylene, forming a melt seal plug in this area. This sealing structure blocks the backflow channel of gas inside the extruder along the screw channel, allowing residual solvent molecules from the micro-alcoholization process and volatiles generated in subsequent reactions to remain within the reaction zone, maintaining a micro-positive pressure state in the reaction system. This localized micro-positive pressure inhibits the premature volatilization and evaporation of small molecules, preventing the physical collapse of the mesoporous structure on the polyester surface.

[0010] The third stage involves negative temperature difference pressing and semi-esterification anchoring. In the second temperature zone, maleic anhydride-grafted polyethylene is preheated to 145-155℃ via a side-feed independent feed cylinder. This temperature is lower than the main screw channel's operating temperature of 185-195℃. Due to the temperature difference, the maleic anhydride-grafted polyethylene injected into the main screw channel maintains a high melt viscosity and chain segment rigidity. Driven by a high-pressure gear pump, the high-viscosity fluid generates a pressing effect, overcoming steric hindrance and forcibly wedging into the mesopores of the polyester surface, forming mechanical topological entanglement. Simultaneously, the maleic anhydride cyclic structure on the grafted macromolecule undergoes a ring-opening reaction under the nucleophilic attack of the polyester terminal hydroxyl groups, generating a semi-ester structure containing ester bonds and free carboxyl groups.

[0011] The fourth stage involves vacuum-driven, full esterification locking. After the material enters the third temperature zone, the system is under high vacuum. Based on Le Chatelier's equilibrium shift principle, vacuum pumping forces the removal of water molecules and residual solvent from the system. The removal of water molecules disrupts the thermodynamic equilibrium of the esterification reaction, prompting the free carboxyl groups on the hemiester structure to undergo further dehydration and ring-closure reactions with adjacent hydroxyl groups, transforming into a stable full ester cross-linked structure. This full esterification conversion eliminates the risk of reversible high-temperature dissociation of the hemiester bond, achieving permanent chemical bonding locking between the polyethylene and polyester phases.

[0012] Preferably, when adding the surface swelling catalyst, a high-speed stirrer at 500-800 rpm is started and mixed continuously for 15-20 minutes; the surface swelling catalyst is sprayed in through a high-pressure atomizing nozzle at an atomization pressure of 0.4-0.6 MPa. By adopting the above technical solution, high-pressure atomization causes the catalyst to adhere to the material surface in the form of tiny droplets, combined with high-speed mechanical shear dispersion, avoiding excessive degradation of polyester caused by local aggregation of the catalyst and ensuring uniform distribution of the mesoporous swelling layer on the surface of the waste composite membrane particles.

[0013] Preferably, the surface swelling catalyst is prepared from the following components in parts by weight: 10-30 parts ethylene glycol; 0.5-1.5 parts tetrabutyl titanate. By adopting the above technical solution, the optimal ratio of swelling agent to catalyst is defined, ensuring the reactivity on the surface of polyester fiber.

[0014] Preferably, the specific preparation method of the surface swelling catalyst is as follows: Under water-protected conditions with nitrogen purging, the required weight parts of tetrabutyl titanate are slowly added dropwise to ethylene glycol at a rate of 10-20 drops / minute. After the addition is complete, the mixture is continuously stirred and homogenized at room temperature for 30-45 minutes. By adopting the above technical solution, tetrabutyl titanate is uniformly dispersed in ethylene glycol under water-protected and constant-rate addition conditions, preventing the titanate from hydrolyzing and becoming ineffective upon contact with water. The preparation process maintains the catalytic activity of the catalyst, allowing the polyester micro-alcoholization reaction to proceed controllably within a set time.

[0015] Preferably, the side gear pump is connected to the independent side feed cylinder, and the heating temperature of the independent side feed cylinder is always 30-50°C lower than the set temperature of the second temperature zone of the extruder. By adopting the above technical solution, a temperature gradient is established between the forced injection fluid and the main screw channel environment of the extruder, preventing degradation and excessive viscosity decrease of maleic anhydride-grafted polyethylene before it enters the main screw channel, thus providing a rheological basis for the fluid dynamics wedging effect.

[0016] Preferably, the heat-insulated homogenizing silo is equipped with a stirring device, and the stirring speed is controlled at 10-30 rpm during the constant temperature residence period; the constant temperature residence time of the material in the silo is preferably 2.5-3.5 hours. By adopting the above technical solution, low-speed stirring ensures uniform heat transfer of the material in the homogenizing silo and prevents agglomeration. The set constant temperature residence time controls the alcoholysis depth of the polyester macromolecular chains, constructing channels while preserving the mechanical strength of the polyester microfiber skeleton.

[0017] Preferably, the main screw speed of the extruder is set to 150-250 rpm, and the temperature of the first temperature zone is preferably controlled at 152-158℃. By adopting the above technical solution, the temperature of the first temperature zone matches the initial melting range of waste high-density polyethylene. Combined with the set screw speed, the material forms a viscoelastic melt when it reaches the reverse thread element, which promotes the formation of a dense dynamic sealing plug.

[0018] Preferably, the amount of maleic anhydride-grafted polyethylene added is 4.5-5.5 parts by weight, and the amount of antioxidant added is 0.15-0.25 parts by weight; the injection pressure of the side gear pump is preferably 7.0-8.0 MPa. By adopting the above technical solution, the antioxidant and graft mixture is injected in a targeted manner to capture free radicals generated by shearing in the reaction core region and inhibit the thermo-oxidative degradation of the matrix macromolecules. The set injection pressure overcomes the interfacial steric hindrance and prevents melt backflow caused by excessive system back pressure.

[0019] Preferably, the temperature of the third temperature zone of the extruder is 192-195℃, and the system vacuum degree is preferably controlled between -0.088 and -0.092 MPa. By adopting the above technical solution, the thermodynamic energy required for the reaction is maintained, the high vacuum environment removes byproduct moisture and residual small molecule solvents, avoids residual gas from causing bubbles during the extrusion and shaping stage, and terminates degradation side reactions.

[0020] Preferably, the extrusion pelletizing process is as follows: the melt is extruded into strips through a multi-hole die set at a temperature of 188-192℃, cooled in a water bath, and then pelletized. The circulating water temperature in the water bath is controlled at 15-25℃. By adopting the above technical solution, the gradually decreasing die temperature stabilizes the melt flow rate, and the water bath cooling temperature ensures uniform shaping of the extruded strips, avoiding excessive internal and external temperature differences that could lead to residual stress concentration.

[0021] This invention provides a process for recycling and reusing edge materials of composite geomembranes. It has the following beneficial effects: 1. This invention improves the compatibility of the polyethylene-polyester interface and enhances the macroscopic mechanical properties of the recycled material through the synergistic effect of physical spatial penetration and chemical bonding. First, a surface swelling catalyst is used to form mesopores on the polyester surface through micro-alcoholization. Then, high-viscosity maleic anhydride-grafted polyethylene is injected under high pressure under negative temperature difference conditions. The macromolecular segments of the grafted material are pressed into the mesopores to form three-dimensional physical entanglement. At the same time, a half-esterification reaction occurs at the interface. Subsequently, vacuum dehydration promotes the transformation of the half-ester structure into a stable full-ester crosslinked network, eliminating the macroscopic phase separation structure at the two-phase interface. This allows the material to effectively transfer and dissipate stress when subjected to external impact or tension, thereby improving the elongation at break and notched impact strength of the composite material.

[0022] 2. This invention maintains the stability of the microporous structure on the surface of polyester through dynamic melt sealing and system internal pressure control, ensuring the effective progress of polymer interfacial reactions. A reverse threaded element is set at the end of the first temperature zone of the extruder to obstruct and compress the material, forming a dense melt sealing plug. This cuts off the backflow channel for internal gas to escape to the feed port, keeping the front end of the reaction zone under a special micro-positive pressure state. This limits the premature evaporation and discharge of residual solvent molecules in the pretreatment stage, and avoids the physical collapse of the newly constructed mesopores on the polyester surface in the high-temperature shear environment, providing the necessary spatial channel for the subsequent wedging of grafted macromolecules.

[0023] 3. This invention inhibits the thermo-oxidative degradation of the polymer matrix during processing by targeting the release of antioxidants and efficiently removing small molecules of byproducts, thus maintaining the processing stability of the material. The antioxidants are mixed with maleic anhydride-grafted polyethylene in an independent side feeder and directly injected into the second temperature zone where the reaction occurs, avoiding the premature consumption of antioxidants at the front of the extruder. This achieves in-situ capture of free radicals in the high-shear region. The high vacuum environment of the third temperature zone at the end rapidly removes water molecules and residual ethylene glycol from the reaction, blocking the high-temperature hydrolysis and alcoholysis reaction pathways of polyester and grafted macromolecular chains, preventing chain breakage and degradation of the polyethylene skeleton, and ensuring the stability of the final granular melt flow rate. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the preparation examples, examples, comparative examples, and test examples in this specification. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a method for preparing a surface-swelling catalyst solution, including the following steps: Under constant temperature conditions of 10℃ to 15℃ in a water bath, 1000g of ethylene glycol was weighed and placed in a mixing tank equipped with a high-shear disperser. The equipment was turned on to maintain the shear speed at a strong turbulent state of 1500rpm to 2000rpm. Then, 100g of tetrabutyl titanate was slowly added dropwise to the mixing tank. During the dropwise addition, tetrabutyl titanate and ethylene glycol underwent an in-situ transesterification reaction to generate nanoscale insoluble matter. After the dropwise addition was completed, the high-shear dispersion was continued at a constant temperature for 15 minutes to prepare a uniform, semi-transparent, slightly bluish nascent catalytic sol for later use. In this preparation example, the mass ratio of ethylene glycol to tetrabutyl titanate was 10:1.

[0026] Preparation Example 2: This preparation example provides a method for preparing a surface-swelling catalyst solution, including the following steps: Under constant temperature conditions of 10℃ to 15℃ in a water bath, 1500g of ethylene glycol was weighed and placed in a mixing tank equipped with a high-shear disperser. The equipment was turned on to maintain the shear speed at a strong turbulent state of 1500rpm to 2000rpm. Then, 50g of tetrabutyl titanate was slowly added dropwise to the mixing tank. During the dropwise addition, tetrabutyl titanate and ethylene glycol underwent an in-situ transesterification reaction to generate nanoscale insoluble matter. After the dropwise addition was completed, the high-shear dispersion was continued at a constant temperature for 10 minutes to prepare a uniform, semi-transparent, slightly bluish nascent catalytic sol for later use. In this preparation example, the mass ratio of ethylene glycol to tetrabutyl titanate was 30:1.

[0027] Preparation Example 3: This preparation example provides a method for preparing a surface-swelling catalyst solution, including the following steps: Under constant temperature conditions of 10℃ to 15℃ in a water bath, 500g of ethylene glycol was weighed and placed in a mixing tank equipped with a high-shear disperser. The equipment was turned on to maintain the shear speed at a super-turbulent state of 2500rpm to 3000rpm. Then, 150g of tetrabutyl titanate was slowly added dropwise to the mixing tank. During the dropwise addition, tetrabutyl titanate and ethylene glycol underwent an in-situ transesterification reaction to generate nanoscale insoluble matter. After the dropwise addition was completed, the high-shear dispersion was continued at a constant temperature for 20 minutes to prepare a uniform milky white nascent catalytic sol for later use. In this preparation example, the mass ratio of ethylene glycol to tetrabutyl titanate was 10:3.

[0028] Examples 1-5: Example 1: This example provides a process for recycling and reusing edge materials of composite geomembranes, including the following steps: (1) Pretreatment of solid phase micro-alcoholization: 100 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material was put into a high-speed mixer with jacket heating. The heating was turned on. When the material temperature reached 90°C, the high-speed stirring was turned on at 800 rpm. 1.1 parts by weight of the surface swelling catalyst obtained in Preparation Example 1 was evenly sprayed onto the material surface through a high-pressure atomizing nozzle and mixed for 15 minutes. Then the pretreated material was transported to the heat-insulated homogenizing silo. The silo temperature was set at 115°C. Nitrogen was introduced to maintain the system at a micro-positive pressure of 0.03 MPa. The material was kept at a constant temperature for 3.0 hours under low-speed stirring at 20 rpm.

[0029] (2) First stage extrusion: The material after the retention treatment is continuously fed into the first temperature zone of the co-rotating twin-screw extruder by the main feeder. The temperature of the first temperature zone is set to 155°C and the speed of the main screw is set to 200 rpm. The high-density polyethylene melt is compressed to form a dynamic melt sealing plug by using the reverse thread element set at the end of the first temperature zone.

[0030] (3) Two-stage extrusion: The material passes through the reverse thread element and enters the second temperature zone with the temperature set at 195°C. The side melt gear pump connected to the middle and rear section of the second temperature zone is started. 5.0 parts by weight of maleic anhydride grafted polyethylene and 0.2 parts by weight of antioxidant 1010 are heated to 150°C in the side feed independent material cylinder. Then the gear pump forces the high viscosity melt into the main screw groove of the extruder with an injection pressure of 7.5 MPa to mix with the main material and cause a fluid impact grafting reaction.

[0031] (4) Three-stage extrusion: The material then enters the third temperature zone where the temperature is maintained at 195°C. The vacuum desiccation and exhaust port control system is turned on to achieve a vacuum of -0.09MPa in order to continuously remove volatiles.

[0032] (5) Extrusion shaping: The melt is extruded into strips through a multi-hole die set at 190°C, cooled in a 20°C water bath and cut with an air knife, and then cut into standard cylindrical particles by a pelletizer.

[0033] Example 2: This example provides a process for recycling and reusing composite geomembrane edge materials, including the following steps: (1) Pretreatment of solid phase micro-alcoholization: 100 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material was put into a high-speed mixer with jacket heating. The heating was turned on. When the material temperature reached 85°C, high-speed stirring was turned on at a speed of 500 rpm. 1.55 parts by weight of the surface swelling catalyst obtained in Preparation Example 2 was evenly sprayed onto the material surface through a high-pressure atomizing nozzle and mixed for 20 minutes. Then the pretreated material was transported to the heat-insulating homogenizing silo. The silo temperature was set at 110°C. Nitrogen was introduced to maintain the system at a micro-positive pressure of 0.02 MPa. The material was kept at a constant temperature for 2.0 hours under low-speed stirring at 10 rpm.

[0034] (2) First stage extrusion: The material after the retention treatment is continuously fed into the first temperature zone of the co-rotating twin-screw extruder by the main feeder. The temperature of the first temperature zone is set to 150°C and the speed of the main screw is set to 150 rpm. The high-density polyethylene melt is compressed to form a dynamic melt sealing plug by using the reverse thread element set at the end of the first temperature zone.

[0035] (3) Two-stage extrusion: The material passes through the reverse thread element and enters the second temperature zone with a temperature set at 185°C. The side melt gear pump connected to the middle and rear section of the second temperature zone is started. 3.0 parts by weight of maleic anhydride grafted polyethylene and 0.1 parts by weight of antioxidant 1010 are heated to 145°C in the side feed independent material cylinder. Then the gear pump forces the high viscosity melt into the main screw groove of the extruder with an injection pressure of 5.0 MPa to mix with the main material and cause a fluid impact grafting reaction.

[0036] (4) Three-stage extrusion: The material then enters the third temperature zone where the temperature is maintained at 190°C. The vacuum desiccation and exhaust port control system is turned on to achieve a vacuum of -0.08MPa to continuously remove volatiles.

[0037] (5) Extrusion shaping: The melt is extruded into strips through a multi-hole die set at 185°C, cooled in a 15°C water bath and cut with an air knife, and then cut into standard cylindrical particles by a pelletizer.

[0038] Example 3: This example provides a process for recycling and reusing composite geomembrane edge materials, including the following steps: (1) Pretreatment of solid phase micro-alcoholization: 100 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material was put into a high-speed mixer with jacket heating. The heating was turned on. When the material temperature reached 95°C, high-speed stirring was turned on at 700 rpm. 0.65 parts by weight of the surface swelling catalyst obtained in Preparation Example 3 was evenly sprayed onto the material surface through a high-pressure atomizing nozzle and mixed for 15 minutes. Then the pretreated material was transported to the heat-insulated homogenizing silo. The silo temperature was set at 120°C. Nitrogen was introduced to maintain the system at a micro-positive pressure of 0.05 MPa. The material was kept at a constant temperature for 4.0 hours under low-speed stirring at 30 rpm.

[0039] (2) First stage extrusion: The material after the retention treatment is continuously fed into the first temperature zone of the co-rotating twin-screw extruder by the main feeder. The temperature of the first temperature zone is set to 160°C and the speed of the main screw is set to 250 rpm. The high-density polyethylene melt is compressed to form a dynamic melt sealing plug by using the reverse thread element set at the end of the first temperature zone.

[0040] (3) Two-stage extrusion: The material passes through the reverse thread element and enters the second temperature zone with a temperature set at 195°C. The side melt gear pump connected to the middle and rear section of the second temperature zone is started. 8.0 parts by weight of maleic anhydride grafted polyethylene and 0.3 parts by weight of antioxidant 1010 are heated to 155°C in the side feed independent material cylinder. Then the gear pump injects the high viscosity melt into the main screw groove of the extruder with an injection pressure of 10.0 MPa to mix with the main material and cause a fluid impingement grafting reaction.

[0041] (4) Three-stage extrusion: The material then enters the third temperature zone where the temperature is maintained at 195°C. The vacuum degassing and exhaust port control system is turned on to achieve a vacuum of -0.095MPa to continuously remove volatiles.

[0042] (5) Extrusion shaping: The melt is extruded into strips through a multi-hole die set at 190°C, cooled in a 25°C water bath and cut with an air knife, and then cut into standard cylindrical particles by a pelletizer.

[0043] Example 4: This example provides a process for recycling and reusing composite geomembrane edge materials, including the following steps: (1) Pretreatment of solid phase micro-alcoholization: 100 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material was put into a high-speed mixer with jacket heating. The heating was turned on. When the material temperature reached 90°C, the high-speed stirring was turned on at 600 rpm. 1.1 parts by weight of the surface swelling catalyst obtained in Preparation Example 1 was evenly sprayed onto the material surface through a high-pressure atomizing nozzle and mixed for 18 minutes. Then the pretreated material was transported to the heat-insulated homogenizing silo. The silo temperature was set at 115°C. Nitrogen was introduced to maintain the system at a micro-positive pressure of 0.04 MPa. The material was kept at a constant temperature for 3.0 hours under low-speed stirring at 20 rpm.

[0044] (2) First stage extrusion: The material after the retention treatment is continuously fed into the first temperature zone of the co-rotating twin-screw extruder by the main feeder. The temperature of the first temperature zone is set to 155°C and the speed of the main screw is set to 200 rpm. The high-density polyethylene melt is compressed to form a dynamic melt sealing plug by using the reverse thread element set at the end of the first temperature zone.

[0045] (3) Two-stage extrusion: The material passes through the reverse thread element and enters the second temperature zone with a temperature set at 195°C. The side melt gear pump connected to the middle and rear section of the second temperature zone is started. 6.0 parts by weight of maleic anhydride grafted polyethylene and 0.2 parts by weight of antioxidant 1010 are heated to 145°C in the side feed independent material cylinder. Then the gear pump forces the high viscosity melt into the main screw groove of the extruder with an injection pressure of 10.0 MPa to mix with the main material and undergo a fluid impact grafting reaction.

[0046] (4) Three-stage extrusion: The material then enters the third temperature zone where the temperature is maintained at 195°C. The vacuum desiccation and exhaust port control system is turned on to achieve a vacuum of -0.09MPa in order to continuously remove volatiles.

[0047] (5) Extrusion shaping: The melt is extruded into strips through a multi-hole die set at 190°C, cooled in a 20°C water bath and cut with an air knife, and then cut into standard cylindrical particles by a pelletizer.

[0048] Example 5: This example provides a process for recycling and reusing composite geomembrane edge materials, including the following steps: (1) Pretreatment of solid phase micro-alcoholization: 100 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material was put into a high-speed mixer with jacket heating. The heating was turned on. When the material temperature reached 90°C, the high-speed stirring was turned on at 600 rpm. 1.1 parts by weight of the surface swelling catalyst obtained in Preparation Example 1 was evenly sprayed onto the material surface through a high-pressure atomizing nozzle and mixed for 18 minutes. Then the pretreated material was transported to the heat-insulated homogenizing silo. The silo temperature was set at 115°C. Nitrogen was introduced to maintain the system at a micro-positive pressure of 0.04 MPa. The material was kept at a constant temperature for 3.0 hours under low-speed stirring at 20 rpm.

[0049] (2) First stage extrusion: The material after the retention treatment is continuously fed into the first temperature zone of the co-rotating twin-screw extruder by the main feeder. The temperature of the first temperature zone is set to 155°C and the speed of the main screw is set to 200 rpm. The high-density polyethylene melt is compressed to form a dynamic melt sealing plug by using the reverse thread element set at the end of the first temperature zone.

[0050] (3) Two-stage extrusion: The material passes through the reverse thread element and enters the second temperature zone with the temperature set at 185°C. The side melt gear pump connected to the middle and rear section of the second temperature zone is started. 4.0 parts by weight of maleic anhydride grafted polyethylene and 0.2 parts by weight of antioxidant 1010 are heated to 155°C in the side feed independent material cylinder. Then the gear pump forces the high viscosity melt into the main screw groove of the extruder with an injection pressure of 5.0 MPa to mix with the main material and cause a fluid impact grafting reaction.

[0051] (4) Three-stage extrusion: The material then enters the third temperature zone where the temperature is maintained at 190°C. The vacuum desiccation and exhaust port control system is turned on to achieve a vacuum of -0.09MPa to continuously remove volatiles.

[0052] (5) Extrusion shaping: The melt is extruded into strips through a multi-hole die set at 185°C, cooled in a 20°C water bath and cut with an air knife, and then cut into standard cylindrical particles by a pelletizer.

[0053] Comparative Examples 1-5: Comparative Example 1: Compared with Example 1, the difference is that the step of conveying the pretreated material to the heat-insulated homogenizing silo for micro-pressure retention is omitted. The material after being mixed by the high-speed mixer is directly fed into the co-rotating twin-screw extruder by the main feeder. All other aspects are the same.

[0054] Comparative Example 2: Compared with Example 1, the difference is that a reverse threaded element was not used at the end of the first temperature zone, but a conventional large-lead forward delivery threaded element was used instead. The melt was not strongly compressed and sealed, and a dynamic melt sealing plug was not formed. All other aspects are the same.

[0055] Comparative Example 3: Compared with Example 1, the difference is that the heating temperature of the independent side-feeding cylinder is set to 195°C, which is completely consistent with the temperature of the main reaction system in the second temperature zone. In addition, the gear pump pressurization is cancelled and atmospheric pressure feeding is adopted, which completely eliminates the negative temperature difference fluid pressurization condition. All other aspects are the same.

[0056] Comparative Example 4: Compared with Example 1, the difference is that the vacuum devaporation exhaust port was not opened in the third temperature zone, and the entire extrusion conveying section was kept at atmospheric pressure. Everything else is the same.

[0057] Comparative Example 5: Compared with Example 1, the difference is that the pretreatment process of ethylene glycol and tetrabutyl titanate was completely removed, and the maleic anhydride grafted polyethylene and antioxidant 1010 were not injected laterally and delayed. Instead, all the original waste materials and additives were simply dry-mixed at room temperature and then uniformly added to the extruder by the main feeder for conventional co-extrusion. All other aspects were the same.

[0058] Test Examples 1-5: Test Example 1: Characterization of the Degree of Deep Solid-Phase Micro-Alcohololysis and Main Chain Integrity This test example is used to quantitatively evaluate the degree of micro-alcoholization reaction of the polyester phase and the retention state of the polymer backbone in the pretreatment stage of each example and comparative example. The experimental operation is carried out according to the following steps: Take 150g of the material discharged from the homogenization chamber in each embodiment and 150g of the mixture in the corresponding stage in the comparative example, place them in the filter paper tube of a Soxhlet extractor, add 800mL of mixed xylene solvent with a boiling point of 138℃ to 144℃, and extract continuously for 14 hours under heating and reflux conditions to completely dissolve and separate the high-density polyethylene phase. Wash the remaining polyester fibers after extraction with acetone three times and dry them in a vacuum drying oven at 85℃ for 24 hours until constant weight.

[0059] Accurately weigh 2.50 g of the dried polyester fiber sample and place it in a 250 mL stoppered iodine flask. Add 50 mL of a phenol-tetrachloroethane mixed solvent with a volume ratio of 1:1. Heat in a 95 °C oil bath until the sample is completely dissolved. After cooling to room temperature, accurately add 10.0 mL of anhydrous pyridine and 5.0 mL of acetic anhydride sequentially. Seal the flask, shake well, and place it in a constant temperature shaking incubator to react at room temperature for 120 minutes. After the reaction, add 25 mL of distilled water and shake vigorously to hydrolyze the unreacted acetic anhydride. Titrate with a 0.05 mol / L sodium hydroxide standard titration solution, using 1% phenolphthalein ethanol solution as an indicator. Record the volume of sodium hydroxide solution consumed at the titration endpoint. Perform a blank experiment simultaneously. Substitute the values ​​into the formula to calculate the terminal hydroxyl value of the sample, in mgKOH / g.

[0060] Accurately weigh 0.150 g of dried polyester fiber sample, add 25 mL of a phenol-tetrachloroethane mixed solvent with a mass ratio of 1:1, heat at 90 °C until completely dissolved, filter using a G3 sintered glass funnel, transfer the filtrate to an Ubbelohde viscometer, fix the viscometer vertically in a constant temperature water bath at a set temperature of 25.0 ± 0.05 °C for 15 minutes, measure the time it takes for the solution to flow through the upper and lower graduation marks, repeat the measurement 3 times and take the average value, at the same time measure the outflow time of the pure mixed solvent, calculate the relative viscosity and specific viscosity, and calculate the intrinsic viscosity of the polyester phase by extrapolation using the single-point method formula, in dL / g.

[0061] Test results: Table 1. Test data of terminal hydroxyl values ​​and intrinsic viscosity of pretreated polyester phases in each example and comparative example. Results analysis: According to the data in Table 1, the materials in Examples 1 to 5 that underwent micro-pressure retention treatment in the heat-insulating homogenization silo had terminal hydroxyl values ​​in the polyester phase ranging from 28.62 to 58.17 mgKOH / g, representing a substantial increase compared to the original baseline value of 12.45 mgKOH / g in Comparative Example 5 without chemical pretreatment. Comparative Example 1, which omitted the micro-pressure retention step, had a terminal hydroxyl value of 14.83 mgKOH / g, essentially maintaining the initial level. Meanwhile, the intrinsic viscosity data showed that the intrinsic viscosity of Examples 1 to 5 ranged from 0.623 to 0.731 dL / g, exhibiting a gradual decrease compared to the initial baseline value of 0.785 dL / g.

[0062] The exponential increase in terminal hydroxyl values ​​and the controlled decrease in intrinsic viscosity confirm the operational logic of the spatially and temporally decoupled solid-phase deep micro-alcohololysis mechanism. Under the physical field of the micro-pressure insulated silo, ethylene glycol molecules in the catalytic sol penetrate into the amorphous network of the polyester fiber surface, resulting in a solid-phase localized alcoholysis reaction. Partial breakage of the polymer chains generates aromatic terminal hydroxyl groups, transforming the originally chemically inert polyester fiber surface into a highly reactive mesoporous swollen layer. In the examples, the intrinsic viscosity did not experience a precipitous drop leading to material embrittlement, indicating that the alcoholysis of the macromolecular chains was confined to a predetermined depth from the fiber surface to the subsurface, and the internal crystalline regions and deep main chain skeleton were not damaged. Data from Comparative Example 1 confirms that the short residence time of conventional blend extrusion cannot trigger the above reaction. This test data constitutes a closed loop of underlying reaction kinetics, indicating that the pretreatment process reasonably deconstructs the spatial constraints within the extruder, providing a dense foundation of surface reaction sites for the subsequent transient pressing and chemical topological entanglement of the polyethylene graft under negative temperature difference conditions.

[0063] Test Example 2: Local Micro-Positive Pressure Monitoring and Volatile Matter Retention Rate Test This test case is used to determine the fluid dynamic blockage state inside the extruder and its effect on the retention of volatile small molecule components in the system. The experimental procedure is as follows: A high-frequency micro melt pressure sensor with a range of 0 to 5 MPa is installed on the barrel wall in the middle section of the second temperature zone of the co-rotating twin-screw extruder. After the equipment reaches the set process temperature and speed and runs continuously for 30 minutes, the pressure fluctuation data within 5 consecutive minutes is recorded and the arithmetic mean is taken as the ambient pressure of the temperature zone.

[0064] A rapid sampling bypass valve with a cooling jacket is installed at the junction of the second and third temperature zones. When the extrusion process is running stably, the bypass valve is opened to take about 50g of melt sample and immediately put it into a Dewar flask containing liquid nitrogen for quenching to terminate the vaporization and diffusion process in the system. After the sample is cooled to the liquid nitrogen temperature, it is taken out and placed in a vacuum drying oven to warm up to room temperature for later use.

[0065] Accurately weigh 15.0 mg of the quenched and reheated sample and place it in an alumina crucible. Use a thermogravimetric analyzer to perform a temperature rise test under a high-purity nitrogen atmosphere with a flow rate of 50 mL / min. The temperature rise program is set to rise from room temperature to 300℃ at a rate of 10℃ / min. Record and calculate the percentage of mass loss of the sample in the temperature range of 150℃ to 220℃. This mass loss corresponds to the content of residual ethylene glycol component in the system.

[0066] Test results: Table 2. Test data of melt pressure and residual ethylene glycol thermal weight loss rate in the second temperature zone for each embodiment and comparative example. Results analysis: According to the data in Table 2, the ambient pressure distribution in the second temperature zone of Examples 1 to 5 ranged from 0.31 to 0.53 MPa, and the corresponding thermal weight loss rate remained between 0.34% and 1.08% in the range of 150°C to 220°C. In Comparative Example 2, the ambient pressure in the second temperature zone was 0.05 MPa, close to conventional atmospheric pressure, and its thermal weight loss rate decreased to 0.07%. The difference between Examples 1 and Comparative Example 2 lies in the presence or absence of the reverse threaded element at the end of the first temperature zone. The comparison of pressure data shows that the reverse threaded element in the examples produced a rheological flow-blocking effect on the high-viscosity polyethylene melt, forming a dynamic sealing zone locally in the screw channel, blocking the gas escape channel along the screw channel inside the extruder.

[0067] When the material enters the second temperature zone, set at 185°C to 195°C, the system temperature approaches or reaches the atmospheric boiling point of ethylene glycol. In Comparative Example 2, due to the lack of a melt-sealing zone, the vaporized ethylene glycol diffuses and dissipates unrestricted upstream through the feed port, resulting in insufficient pressure accumulation and extreme ethylene glycol scarcity within the system. In this embodiment, the melt-sealing zone restricts the unidirectional flow of gas, allowing the vaporized ethylene glycol to accumulate within a limited volume and generate a micro-positive pressure. This micro-positive pressure environment alters the phase transition equilibrium of ethylene glycol, inhibiting its excessive transfer from the polymer melt to the gas phase. Weight loss data confirms that ethylene glycol is forcibly retained in the reaction system under micro-positive pressure. The remaining ethylene glycol component maintains the plasticized and open state of the mesopores on the surface of the polyester phase, preventing the porous structure from physically collapsing due to solvent evaporation under high-temperature shear. The retained mesopore structure forms the spatial basis for the forced wedging and topological entanglement of the compatibilizer melt in the subsequent extrusion zone.

[0068] Test Example 3: Quantitative Testing of Interfacial Topological Entanglement and Chemical Bonding This test example is used to quantitatively evaluate the degree of physical entanglement and chemical bonding between the compatibilizer macromolecular chains and the polyester fiber backbone in each example and comparative example. The experimental procedure is as follows: Accurately weigh 10.0 g of the final particle sample obtained from each example and comparative example, place it in a filter cartridge covered with a 120-mesh stainless steel wire mesh, place it in a Soxhlet extractor, use 500 mL of xylene as solvent, and continuously reflux extract for 24 hours under oil bath heating at 140°C to 145°C to completely dissolve the free high-density polyethylene in the matrix and the maleic anhydride grafted polyethylene that has not been chemically bonded to the polyester.

[0069] After extraction, the metal mesh containing insoluble matter was removed, rinsed three times with hot xylene, then washed twice with anhydrous ethanol, and placed in a vacuum drying oven at 80°C for 24 hours until a constant mass was achieved. The mass of the insoluble matter was weighed, and the percentage of the insoluble matter mass relative to the theoretically added polyester mass in the original particles was calculated as the apparent bound gel rate.

[0070] The dried insoluble fiber samples were subjected to transmission scanning on a Fourier transform infrared spectrometer using the KBr pellet method. The spectral acquisition range was 4000 to 400 cm⁻¹, the resolution was set to 4 cm⁻¹, and 32 scans were performed. Baseline correction and peak area integration were performed on the spectra. The absorbance of the asymmetric stretching vibration peak of the aliphatic CH ring (2920 cm⁻¹) representing the polyethylene chain segment and the vibration peak of the para-disubstituted benzene ring (1505 cm⁻¹) representing the polyester skeleton were extracted. The absorbance ratio A2920 / A1505 was calculated to quantitatively characterize the compatibilizer grafting density on the surface of the polyester skeleton.

[0071] Test results: Table 3. Test data of apparent binding gelation rate and infrared characteristic absorbance ratio of insoluble matter extracted from composite materials in each example and comparative example. Results analysis: According to the data in Table 3, after deep extraction with xylene, the apparent bound gel rates of the composite materials in Examples 1 to 5 ranged from 109.18% to 126.73%, and the absorbance ratios A2920 / A1505 were between 0.382 and 0.541. Continuous reflux extraction with xylene removed free polymer chains that had not undergone physical entanglement or chemical bonding within the system. The significant increase in the apparent bound gel rate (exceeding 100%) and the jump in the ratio of infrared characteristic peaks indicate that the maleic anhydride-grafted polyethylene macromolecule was successfully anchored to the surface of the polyester backbone, forming a cross-linked network that cannot be stripped by strong solvents.

[0072] Comparative Example 3 eliminated the negative thermoelectric pressure process, resulting in an apparent gelation rate of only 102.31% and an absorbance ratio of just 0.084. Without a melt viscosity gradient created by a thermoelectric difference and under high-pressure injection by a gear pump, maleic anhydride-grafted polyethylene fluid could not generate a hydrodynamic pressure effect. At atmospheric pressure and isothermal conditions, the polymer chains possess significant steric hindrance, preventing them from overcoming this resistance and wedging into the mesoporous channels formed by micro-alcoholization on the polyester surface. The two-phase interface only exhibits a shallow macroscopic contact, lacking the mechanical locking effect of physical topological entanglement, leading to limited contact area, low conversion rates in subsequent chemical reactions, and easy solvent damage to the interface during extraction. These data confirm the decisive role of transient negative thermoelectric pressure in forcibly overcoming the steric hindrance of macromolecules and forming deep physical entanglement.

[0073] Comparative Example 4, without opening the third temperature zone vacuum devouring exhaust port, had an apparent gelation rate of 106.85% and an absorbance ratio of 0.162, indicating an interfacial binding amount far below the baseline level of the examples. In the normal pressure extrusion environment, the half-ester structure formed by the ring-opening of the polyester terminal hydroxyl group and maleic anhydride is in a thermodynamically reversible equilibrium state. Without the total system pressure difference provided by the high vacuum, the water molecules generated in the reaction cannot be effectively removed and accumulate inside the melt. The half-ester structure, constrained by the reaction barrier, cannot continue to transform into a full-ester structure, leading to the reverse breakage of some of the formed chemical bonds under subsequent high-temperature shearing. The high vacuum environment applied in the examples altered the reaction process according to Le Chatelier's principle, forcibly driving the dehydration and ring closure of the half-ester molecules by removing byproducts, thus achieving irreversible chemical locking of the macromolecular phase interface. Combined with the 100.54% baseline gelation rate obtained by Comparative Example 5, which completely lacked pretreatment and interfacial control, the above macroscopic quality and microscopic spectral data confirm the effectiveness of the dual interfacial mechanism of physical topological entanglement and chemical dehydration locking.

[0074] Test Example 4: Evaluation of Macroscopic Mechanical Properties This test example is used to determine the macroscopic tensile and impact toughness of the composite materials prepared in each embodiment and comparative example, and to evaluate the actual transmission effect of microscopic physical topological entanglement and chemical bonding network on the macroscopic mechanical characteristics of the materials. The experimental operation is carried out according to the following steps: The cylindrical particles prepared in each embodiment and comparative example were placed in an 80°C forced-air drying oven for 4 hours to remove adsorbed moisture from the material surface. The dried particles were then added to the hopper of a standard injection molding machine. The temperature gradients of each section of the barrel were set to 175°C, 185°C, 190°C, and 190°C, the mold temperature was set to 40°C, the injection pressure to 60 MPa, and the holding time to 15 seconds. The injection molded specimens were dumbbell-shaped tensile test specimens and rectangular impact test specimens conforming to the test standard dimensions. After removing flash, the specimens were placed in a standard environment at 23±2°C and 50±5% relative humidity for 24 hours for conditioning.

[0075] The tensile properties of dumbbell-shaped specimens were tested using a computer-controlled electronic universal testing machine. The tensile speed was set to 50 mm / min, and the gauge length was set to 50 mm. The tensile yield stress and elongation at break of each group of specimens were recorded during the tensile process. Five parallel specimens from each group were tested, and the arithmetic mean was calculated after removing abnormally damaged specimens. The tensile yield stress is expressed in MPa, and the elongation at break is expressed in %.

[0076] Rectangular specimens were subjected to notched impact strength testing using a cantilever beam impact testing machine. Before testing, a V-shaped notch was milled in the middle of the rectangular specimen using a fully automated notching machine. The notch depth was controlled to be 2.0 mm, and the bottom arc radius was 0.25 mm. The pendulum impact energy was set to 2.7 J. The cantilever beam notched impact strength of each group of specimens was tested. Five parallel specimens from each group were measured, and the arithmetic mean was calculated. The unit is kJ / m³. 2 .

[0077] Test results: Table 4. Test data of macroscopic mechanical properties of composite materials in each embodiment and comparative example Results analysis: According to the data in Table 4, the tensile yield stress of the composite materials prepared in Examples 1 to 5 ranged from 23.8 to 25.1 MPa, the elongation at break ranged from 312% to 415%, and the notched impact strength of the cantilever beam remained between 15.6 and 20.4 kJ / m. 2 Compared with the benchmark test data of the direct extrusion of dry-mixed material at room temperature in Comparative Example 5, the material in the Example showed an order-of-magnitude increase in elongation at break and notched impact strength while maintaining high yield stress, and the material's failure mode changed from brittle fracture to ductile fracture.

[0078] Comparative Example 1 omitted the solid-phase deep micro-alcoholization pretreatment process, resulting in a reduced elongation at break of 54% and an impact strength of only 6.3 kJ / m. 2 The polyester fiber surface did not undergo mesoporous swelling, maintaining a dense physical structure and chemical inert surface. Within the polyethylene matrix, the untreated polyester microfibers acted as numerous microscopic defects and stress concentration points. When the matrix was subjected to tensile or impact forces, rapid debonding and slippage occurred at the two-phase interface, leading to macroscopic brittle fracture. The mechanical properties of the examples demonstrate that the pre-construction of the mesoporous swelling layer provides the necessary three-dimensional physical space for polymer chain penetration and anchoring.

[0079] Comparative Example 3 eliminated the transient negative temperature difference fluid stamping process conditions, and the notched impact strength of the material plummeted to 7.5 kJ / m. 2 The elongation at break dropped to 88%. Under isothermal and atmospheric pressure side-feeding conditions, the compatibilizer molecular chains lost their high-rigidity fluid characteristics, failing to generate a hydrodynamic wedging effect and thus failing to overcome steric hindrance to penetrate the mesopores of the polyester surface. There was a lack of deep physical topological entanglement between the two phases, and the interfacial bonding force relied solely on shallow, limited chemical bonding and intermolecular forces. Under high-speed impact loads, the fragile interface could not effectively transfer and dissipate the stress energy that damaged the matrix, leading to unimpeded crack propagation at the phase interface. The high impact toughness maintained in the examples demonstrates that the synergistic mechanism of mechanical locking effect and interfacial chemical crosslinking effectively delayed the crack initiation and propagation path.

[0080] The test data for Comparative Examples 2 and 4 fall within the intermediate transition zone between the examples and the baseline comparative examples. In Comparative Example 2, the lack of local micro-positive pressure led to premature escape of ethylene glycol volatiles, thermal collapse of the mesopores on the polyester surface, and a significant loss of physical anchoring sites, resulting in a decrease in compressive strength. In Comparative Example 4, the lack of high-vacuum dehydration resulted in the interfacial half-ester structure being limited by thermodynamic reversible dissociation, and the failure of the full-ester chemical locking led to a decrease in interfacial bond strength. The gradual decline in various mechanical properties matches the aforementioned physicochemical failure process of the microscopic mechanism. The overall test results of the macroscopic mechanical characteristics confirm the fundamental reshaping of the interfacial properties of the polymer alloy composite structure by the synergistic intervention of multiple physics fields.

[0081] Test Example 5: Evaluation of matrix thermo-oxidative degradation and processing stability This test example is used to determine the melt flow rate of the composite materials of each example and comparative example, and to evaluate the degree of degradation and molecular weight retention of the high-density polyethylene matrix during processing under high shear, thermal-oxidative, and small molecule environments. The experimental procedure is as follows: Take about 50g of the final composite material particles obtained from each example and comparative example, place them in a vacuum drying oven, and dry them for 6 hours at 85℃ and a vacuum degree of -0.09MPa to remove trace amounts of free moisture adsorbed on the surface and shallow layer of the particles.

[0082] Turn on the melt flow indexer and set the barrel temperature to 190.0 ± 0.2℃ and maintain this temperature for 30 minutes. Accurately weigh 5.0 g of the dried granular sample and add it to the instrument barrel in three portions. After each addition, use the pressure rod to compact the sample and remove air bubbles. The feeding process should be completed within 1 minute. After feeding is complete, place the standard piston into the barrel and preheat at 190℃ for 4 minutes.

[0083] After preheating, a standard weight of 2.16 kg is smoothly loaded onto the top of the piston, causing the molten material to be extruded from a standard die (inner diameter 2.095±0.005 mm, length 8.000±0.025 mm) under a specified load. Extrudates containing air bubbles or with unstable flow rates are discarded. Once the extrusion rate stabilizes, the automatic cutting device is activated, cutting the extruded sample every 10 seconds, and five air-free samples are collected consecutively.

[0084] The collected cut samples were cooled to room temperature and their masses were accurately weighed using an analytical balance. The arithmetic mean of the masses of the five samples was taken and substituted into the melt flow rate calculation formula to obtain the melt flow rate (MFR) of the sample, in g / 10min.

[0085] Test results: Table 5. Test data of melt flow rate of composite materials in each embodiment and comparative example. Results analysis: According to the data in Table 5, the melt flow rates of the composite materials prepared in Examples 1 to 5 ranged from 1.86 to 2.43 g / 10 min, which is highly consistent with the initial rheological parameter range of the matrix high-density polyethylene. In Comparative Example 5, under room temperature dry mixing and conventional blending extrusion conditions, the melt flow rate increased to 4.82 g / 10 min, indicating that in a physical processing environment lacking process protection, the matrix resin underwent a baseline degree of high-temperature thermo-oxidative degradation, resulting in random chain breakage of macromolecules, leading to a decrease in melt viscosity and an increase in fluidity.

[0086] In Comparative Example 4, the melt flow rate abnormally increased to 6.75 g / 10 min when the third-zone vacuum devouring vent was not opened. Under normal pressure, the catalyst solvent ethylene glycol introduced during the pretreatment stage, as well as the trace water molecules released during the interfacial half-esterification to full-esterification conversion, could not be removed in time. These polar small molecules, under the high temperature (190℃ to 195℃) and strong shear environment of the twin-screw extruder, not only exhibited a small-molecule plasticizing effect, reducing the frictional resistance between macromolecular chains, but also initiated high-temperature hydrolysis and alcoholysis reactions between the polyester phase and the polyethylene graft phase. Chain scission degradation of the polymer backbone led to a sharp decrease in the average molecular weight of the system, and a deterioration in macroscopic rheological properties. This data confirms the necessity of the third-zone high-vacuum devouring process in terminating side reactions and maintaining the thermodynamic stability of the polymer backbone.

[0087] In the examples, the melt flow rate remained stable at a low level, confirming the effective operation of the anti-degradation synergistic mechanism in the process. On one hand, the side-feed independent feeder mixes maleic anhydride-grafted polyethylene with antioxidant 1010 and melts it in a low-temperature zone (145°C to 155°C), avoiding prolonged high-temperature dissipation of the antioxidant in the first temperature zone. A high-pressure gear pump forces this mixed melt into the second temperature zone, achieving in-situ targeted release of the antioxidant in the high-shear reaction region, effectively capturing free radicals generated by the polyethylene matrix under strong shear. On the other hand, the combination of micro-positive pressure solid-liquid sealing reaction and negative temperature difference fluid impingement shortens the effective residence time of the material in a high-temperature environment. The above rheological characterization data eliminates the risk of degradation and thinning of the composite material's macromolecular chains, indicating that by intervening in the thermodynamic path through an external physical field, the molecular weight and processing stability of the matrix polymer material are fully preserved while achieving chemical locking of the heterogeneous interface.

[0088] Test Example 6: Thermodynamic Characterization of Macroscopic Compatibility of Multiphase Systems This test example is used to determine the dynamic thermomechanical properties of the composite materials prepared in each embodiment and comparative example. By analyzing the shift in the glass transition temperature of the two phases, the degree of intervention of interfacial physical topological entanglement and chemical locking on the macroscopic compatibility of the multiphase system is evaluated. The experimental operation is carried out according to the following steps: Rectangular impact specimens prepared using standard injection molding processes in each embodiment and comparative example were cut into standard dynamic mechanical test strips with dimensions of 35.0 mm × 10.0 mm × 4.0 mm using a precision engraving machine. During processing, cutting fluid was used for constant-temperature cooling to avoid localized overheating that could alter the material's thermal history and phase structure. After processing, the strips were cleaned with anhydrous ethanol and vacuum-dried at room temperature for 12 hours.

[0089] The standard specimens were tested using a Dynamic Mechanical Thermal Analyzer (DMA). A double cantilever beam test fixture was selected, and the test mode was set to temperature step scan. The test frequency was set to 1 Hz, and the dynamic strain amplitude was controlled at 0.05% to ensure that the test was conducted in the linear viscoelastic region. The test environment was a high-purity nitrogen atmosphere, and the temperature scan range was set to -140℃ to 120℃, with a heating rate controlled at 3℃ / min.

[0090] The instrument automatically records the curves showing the changes in the material's storage modulus and loss tangent with temperature during the test. Two characteristic relaxation peaks are extracted from the loss tangent curve. The relaxation peak in the low-temperature region corresponds to the glass transition temperature (Tg1) of the high-density polyethylene phase, and the relaxation peak in the high-temperature region corresponds to the glass transition temperature (Tg2) of the polyester phase. The center temperatures corresponding to the two peaks are recorded respectively, and the temperature difference between the two phase peaks (ΔTg) is calculated.

[0091] Test results: Table 6. Dynamic mechanical glass transition temperature test data of composite materials in each embodiment and comparative example Results analysis: According to the data in Table 6, Comparative Example 5, which uses room temperature dry blending and conventional co-extrusion, has a low-temperature region Tg1 of -119.1℃ and a high-temperature region Tg2 of 79.4℃, with a peak temperature difference of 198.5℃ between the two phases. This baseline data exhibits typical characteristics of a polymer incompatible system, where the two macromolecular chain segments are thermodynamically completely independent, and the system contains high interfacial tension and severe macroscopic phase separation.

[0092] In Examples 1 to 5, the Tg1 of the polyethylene phase shifted towards higher temperatures to the range of -108.7℃ to -104.1℃, while the Tg2 of the polyester phase shifted towards lower temperatures to the range of 61.5℃ to 68.1℃, reducing the peak temperature difference between the two phases to 165.6℃ to 176.8℃. The shift of Tg1 towards higher temperatures indicates that the low-temperature free volume expansion of the polyethylene macromolecular chains is suppressed. This is because the compatibilizer segments are forcibly pressed into the polyester mesopores and form chemical anchors, while the rigid polyester skeleton restricts the movement of the matrix polymer segments through the interfacial crosslinking network. The shift of Tg2 towards lower temperatures indicates that the flexible grafted polyethylene macromolecular chains successfully penetrated into the interior of the polyester amorphous region, playing an internal plasticizing role and increasing the local free volume of the polyester segments. The convergence of the bidirectional temperature shifts constitutes classical thermodynamic characterization data for a strongly compatible system, confirming the objective existence of deep physical topological entanglement.

[0093] Comparative Example 3 eliminated the transient negative temperature difference fluid impingement condition, and its peak temperature difference between the two phases was 190.5℃, which is very close to the extremely incompatible state of Comparative Example 5. This data proves that under isothermal and atmospheric pressure mixing conditions, the compatibilizer fluid cannot overcome the steric hindrance to wed into the mesopores. Without the impingement effect of the high-viscosity fluid, the two-phase interface degenerates into a shallow two-dimensional contact, and the polymer chain segments cannot form three-dimensional topological entanglements. This results in the chain segments on both sides of the interface maintaining high independence, and the thermodynamic compatibility is not substantially improved.

[0094] Comparative Example 4, without opening the third temperature zone vacuum devouring exhaust port, exhibited a peak temperature difference of 183.2°C between the two phases, a significantly lower deviation than the Example. Under normal pressure, the hemiester structure at the interface could not remove water molecules to achieve full esterification locking. Residual small water molecules caused the chemical reaction to proceed in the reverse dissociation direction. Due to the lack of irreversible covalent bond anchoring, the topological entanglement previously formed through physical pressing partially slipped and disintegrated during high-temperature shearing and subsequent thermodynamic relaxation. The weakening of the interfacial constraint force led to a certain degree of independent motion capability regained by the two-phase macromolecular chain segments, resulting in a degradation of the system's thermodynamic compatibility. The thermodynamic analysis data of the test example corresponded to the aforementioned microscopic interfacial reaction mechanism, confirming the decisive role of the synergistic intervention of multiple fields—space, fluid dynamics, and thermodynamics—in the reshaping of macromolecular interfaces.

Claims

1. A process for recycling and reusing edge materials of a composite geomembrane, characterized in that, Includes the following steps: Heat 80-120 parts by weight of waste high-density polyethylene / polyester composite geomembrane pulverized material to 85-95℃, and evenly spray 0.65-1.55 parts by weight of surface swelling catalyst liquid and mix. The mixed material is transported to an insulated homogenization silo and kept at a constant temperature of 110-120℃ for 2.0-4.0 hours under nitrogen gas and a slight positive pressure of 0.02-0.05MPa, so that the surface of the polyester fiber is slightly alcoholyzed and a mesoporous swelling layer is formed. The material is added to the first temperature zone of the co-rotating twin-screw extruder at a temperature of 150-160℃. The reverse thread element at the end of the first temperature zone is used to block the melt flow and form a dynamic melt sealing plug that cuts off the gas path. The material enters the second temperature zone at 185-195℃. 3.0-8.0 parts by weight of maleic anhydride grafted polyethylene and 0.1-0.3 parts by weight of antioxidant, preheated to 145-155℃ in the side-feeding independent material cylinder, are forcibly injected into the main screw channel at a pressure of 5.0-10.0MPa using a side gear pump. The negative temperature difference pressing effect forces the grafted macromolecular chains to wedge into the mesoporous swelling layer and undergo a semi-esterification reaction. The material enters the third temperature zone with a temperature of 190-195℃, and the volatiles are removed under a vacuum of -0.08 to -0.095MPa. At the same time, the half-ester structure at the phase interface is dehydrated and converted into a full-ester structure to complete the interface anchoring, and then it is extruded and pelletized.

2. The waste material recycling and reuse process according to claim 1, characterized in that, When adding the surface swelling catalyst, turn on the high-speed stirring at 500-800 rpm and continue mixing for 15-20 minutes; The surface swelling catalyst is injected through a high-pressure atomizing nozzle at a pressure of 0.4-0.6 MPa.

3. The waste material recycling and reuse process according to claim 1, characterized in that, The surface swelling catalyst solution is made from the following components in parts by weight: 10-30 parts of ethylene glycol; Tetrabutyl titanate 0.5-1.5 parts.

4. The edge material recycling and reuse process according to claim 3, characterized in that, The specific preparation method of the surface swelling catalyst liquid is as follows: Under nitrogen-protected, water-free conditions, the required amount of tetrabutyl titanate by weight is slowly added to ethylene glycol at a rate of 10-20 drops / minute. After the addition is complete, the mixture is stirred and homogenized at room temperature for 30-45 minutes.

5. The waste material recycling and reuse process according to claim 1, characterized in that, The side gear pump is connected to the side feed independent cylinder, and the heating temperature of the side feed independent cylinder is always 30-50°C lower than the set temperature of the second temperature zone of the extruder.

6. The waste material recycling and reuse process according to claim 1, characterized in that, The heat-insulating homogenizing silo is equipped with a stirring device, and the stirring speed is controlled at 10-30 rpm during the constant temperature residence period. The preferred constant temperature residence time of the material in the silo is 2.5-3.5 hours.

7. The waste material recycling and reuse process according to claim 1, characterized in that, The main screw speed of the extruder is set to 150-250 rpm, and the temperature of the first temperature zone is preferably controlled at 152-158℃.

8. The waste material recycling and reuse process according to claim 1, characterized in that, The preferred amount of maleic anhydride-grafted polyethylene is 4.5-5.5 parts by weight, and the preferred amount of antioxidant is 0.15-0.25 parts by weight. The injection pressure of the lateral gear pump is preferably 7.0-8.0 MPa.

9. The waste material recycling and reuse process according to claim 1, characterized in that, The temperature of the third temperature zone of the extruder is preferably 192-195℃, and the system vacuum degree is preferably controlled between -0.088 and -0.092MPa.

10. The waste material recycling and reuse process according to claim 1, characterized in that, The extrusion pelletizing process is as follows: The melt is extruded into strips through a multi-hole die set at a temperature of 188-192℃, cooled in a water tank, and then cut into pellets. The temperature of the circulating water in the water tank is controlled at 15-25℃.

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