Pipe material for siphon drainage and method for producing the same

Abstract

The application relates to the field of high polymer materials, and discloses a pipe material for siphon drainage and a preparation method thereof. The pipe material is prepared by melt blending of polyolefin elastomer, polyethylene oxide, maleic anhydride grafted polyethylene compatibilizer and molecular sieve. The preparation method is characterized in that a double-screw extruder is used for stepwise feeding: the polyolefin elastomer, the compatibilizer and the molecular sieve are added from a main feeding port, and the heat-shear-sensitive polyethylene oxide is added from a lateral feeding port in the middle section of the extruder. Through the synergistic effect of the components, the inner wall of the pipe material can be restructured on contact with water, and the hydrophobicity is changed into hydrophilicity to form a hydration layer for inhibiting the adhesion of biological fouling. The pipe material has water-activated anti-fouling and anti-blocking performance, can maintain a low hydraulic friction coefficient for a long time, and through the introduction of the compatibilizer, the excellent physical and mechanical properties of the material are ensured, and the technical problem of the existing pipe material that is prone to fouling and causes the attenuation of the hydraulic performance is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a pipe material for siphon drainage and a preparation method thereof. BACKGROUND

[0002] Siphon rainwater and sewage drainage system is widely used in large buildings due to its high drainage efficiency and flexible pipeline arrangement. The system usually uses high-density polyethylene (HDPE) and other polymer pipe materials as the conveying pipeline. However, the inner wall performance of these conventional pipe materials will deteriorate during long-term operation.

[0003] The organic matter, inorganic salt and microorganism contained in the drainage provide a material basis for the formation of biofilm. The surface of conventional polyolefin pipe material is usually a non-polar hydrophobic surface, which is conducive to the initial adsorption of macromolecular organic matter such as proteins and polysaccharides, and further induces the adhesion and proliferation of microorganisms. With the passage of time, a layer of biofilm composed of microorganisms and their extracellular polymers will gradually form on the inner wall of the pipe.

[0004] The formation of biofilm significantly increases the macroscopic roughness of the pipe wall. According to the principle of fluid mechanics, the increase of pipe wall roughness will directly lead to the increase of the hydraulic friction coefficient of the pipeline. For siphon drainage system which relies on accurate hydraulic calculation, the unexpected increase of friction coefficient will destroy the negative pressure balance of the system operation, reduce the drainage capacity, and even cause system failure and pipeline blockage in severe cases. In order to maintain normal operation of the system, regular physical or chemical cleaning is required, which increases the life cycle cost of the system. Therefore, it is a technical problem to be solved in the field to develop a pipe material with inherent anti-biofouling adhesion ability and long-term low hydraulic friction performance. SUMMARY

[0005] The purpose of the present application is to provide a pipe material for siphon drainage which can resist biofilm blockage and maintain low hydraulic friction for a long time, and a preparation method thereof, to solve the technical defects of the existing pipe material that the surface is easy to be contaminated, resulting in the deterioration of hydraulic performance.

[0006] To achieve the above purpose, the present application realizes the technical scheme as follows:

[0007] In a first aspect, the present application provides a pipe material for siphon drainage, which is made of raw materials including the following weight parts: polyolefin elastomer 82-94 parts by weight, polyethylene oxide 3-10 parts by weight, maleic anhydride grafted polyethylene compatibilizer 2-5 parts by weight, and molecular sieve 0.5-2.5 parts by weight.

[0008] By adopting the above technical scheme, the pipe material of the present application realizes the water-activated surface anti-fouling adhesion function through the synergistic effect of the four components. The specific action mechanism is as follows:

[0009] 1. The structural basis of the composite system: in the composite material system, the non-polar polyethylene backbone of the maleic anhydride grafted polyethylene compatibilizer is physically compatible with the non-polar polyolefin elastomer matrix through chain entanglement; the grafted polar maleic anhydride group is combined with the strong polar polyethylene oxide through hydrogen bonding or dipole interaction. This structure makes the polyethylene oxide uniformly dispersed and stably anchored in the polyolefin elastomer matrix in the form of micron or sub-micron phase domains, forming a stable micro-phase separation structure and ensuring the integrity of the macroscopic mechanical properties of the material.

[0010] 2. Water activation process: in the dry state, the surface of the material is mainly covered by the low-surface-energy polyolefin elastomer, showing hydrophobicity. When the inner wall of the pipe comes into contact with water, the molecular sieve with a regular channel structure serves as a rapid permeation channel for water molecules, enabling them to overcome the surface energy barrier and rapidly enter the near-surface region of the material.

[0011] 3. Surface reconstruction process: the permeated water molecules undergo hydration with the polyethylene oxide segments dispersed near the surface. After hydration, the polarity of the polyethylene oxide segments is significantly enhanced, and their molecular chains undergo conformational rearrangement and migrate to and accumulate at the interface between the material and water in order to reduce the interfacial energy of the entire system.

[0012] 4. Anti-fouling attachment function realization: the polyethylene oxide segments accumulate on the inner wall surface of the pipe, forming a hydrated layer that is physically dense and dynamically combines a large number of water molecules. This hydrated layer can effectively prevent the direct contact and non-specific adsorption of protein, polysaccharide, microorganisms, and other fouling components with the pipe substrate through steric hindrance and thermodynamic repulsion. Since the initial step of biological fouling formation is inhibited, the subsequent growth and maturation of the biofilm are fundamentally prevented, allowing the inner wall of the pipe to remain smooth for a long period of time and maintaining a low hydraulic friction coefficient and stable drainage efficiency.

[0013] Preferably, the weight parts of the raw materials are as follows: polyolefin elastomer 88-91 parts by weight, polyethylene oxide 5-7 parts by weight, maleic anhydride grafted polyethylene compatibilizer 2.5-3.5 parts by weight, and molecular sieve 0.8-1.2 parts by weight.

[0014] By using the above technical solution, the ratio of each component is further optimized, enabling more efficient and stable dynamic transformation of surface wettability and anti-fouling attachment performance while ensuring the physical and mechanical properties of the material.

[0015] Preferably, the polyolefin elastomer is polyolefin elastomer (POE) or ethylene-propylene rubber (EPM); the molecular sieve is 3A type molecular sieve or 4A type molecular sieve.

[0016] By adopting the technical scheme, the POE and the EPM can provide excellent flexibility, weather resistance and impact resistance for the pipe material. The 3A type and 4A type molecular sieves have different effective pore sizes and can be used as effective permeation channels for water molecules, so that the technical scheme has good raw material selection flexibility.

[0017] Preferably, the maleic anhydride grafting rate of the maleic anhydride grafted polyethylene compatilizer is 0.8-1.5 wt%.

[0018] By adopting the technical scheme, the grafting rate in the range ensures that the compatilizer molecule has sufficient polar functional groups to form effective action with the polyethylene oxide, and meanwhile, good compatibility with the polyolefin matrix is maintained, so that the optimal interface bonding effect is achieved, and the macro mechanical properties and functional stability of the material are positively affected.

[0019] Preferably, the raw material further comprises 0.1-1.0 parts by weight of an antioxidant.

[0020] By adopting the technical scheme, the addition of the antioxidant can effectively inhibit the thermal oxidative degradation of the polymer matrix during high-temperature processing and long-term service, and improve the long-term service life and performance stability of the pipe material.

[0021] In the second aspect, the application provides a preparation method of a pipe material for siphon drainage, which adopts a double-screw extruder and comprises the following steps:

[0022] (a) adding the polyolefin elastomer, the maleic anhydride grafted polyethylene compatilizer and the molecular sieve through the main feeding port of the double-screw extruder;

[0023] (b) adding the polyethylene oxide through the lateral feeding port after the melt plasticizing section of the double-screw extruder;

[0024] (c) performing melt blending in the extruder and extruding and molding through a die.

[0025] By adopting the technical scheme, the preparation method of the application ensures the structural integrity of the functional components in the composite material through the specific process of step-by-step feeding, and the innovative principle lies in that:

[0026] The polyethylene oxide (PEO), especially the high molecular weight PEO, shows high sensitivity to high temperature and high shear stress, and the molecular chain is prone to breakage under long-term thermal mechanical action, resulting in a decrease in molecular weight and loss of function.

[0027] The matrix resin (polyolefin elastomer) with better tolerance, the compatilizer and the molecular sieve are added from the main feeding port, so that the melt and preliminary dispersion are first completed in the melt plasticizing section at the front end of the extruder, and a uniform melt matrix is formed.

[0028] The heat-shearing sensitive polyethylene oxide is added from the lateral feeding port of the middle section of the extruder. At this time, the molten matrix has been formed, and the PEO is directly added to the molten material, thereby skipping the most severe solid-state friction, melting and high-stress plasticizing stage at the front end. This significantly shortens the total residence time of the PEO in the extruder, especially the effective action time in the high-temperature and high-shear environment.

[0029] Due to the avoidance of excessive thermal mechanical degradation, the high molecular weight of the polyethylene oxide is effectively preserved. The complete molecular chain is a prerequisite for it to form an effective hydration layer on the surface of the material and realize the anti-fouling adhesion function. Therefore, the preparation method guarantees that the final pipe product can have and stably exert its designed function from the process.

[0030] Preferably, before step (a) and step (b), a step of pretreating the raw materials is further included: drying treatment is performed on the polyolefin elastomer, the polyethylene oxide and the compatilizer; and activation treatment is performed on the molecular sieve.

[0031] By adopting the technical scheme, the pretreatment step can remove the adsorbed water in the raw materials. The water will be gasified in the extrusion process to cause defects such as bubbles and cavities in the product, and may cause hydrolysis of components such as PEO. Activation of the molecular sieve can ensure that its pores can act as effective water permeation channels in subsequent use, thereby ensuring the physical quality and functional stability of the product.

[0032] Preferably, the temperature of the melt blending extruder is set to 150-215°C, and the screw rotation speed is 200-400 rpm.

[0033] By adopting the technical scheme, the process parameter window ensures that the polymer system can be completely melted and good dispersion mixing effect is obtained, while the thermal degradation and mechanical degradation of the polymer are controlled within an acceptable range, achieving the balance between the stability of the processing process and the performance of the final product.

[0034] Preferably, the maleic anhydride grafted polyethylene compatilizer is prepared by melt grafting reaction of low-density polyethylene, maleic anhydride and an initiator.

[0035] By adopting the technical scheme, the source and preparation method of the key raw material compatilizer are limited, which ensures that it has a specific molecular structure, i.e. a non-polar polyethylene main chain and grafted polar maleic anhydride side groups, which is the basis for its interface bridging between the non-polar matrix and the polar functional components.

[0036] Preferably, before the extrusion molding, a step of devolatilization treatment of the molten material through a vacuum devolatilization port is further included.

[0037] By adopting the technical scheme, residual moisture, unreacted monomers and other small molecule byproducts in the molten material can be effectively removed, the compactness and surface quality of the extruded product are improved, and the physical properties and appearance of the pipe are positively affected.

[0038] To sum up, the present application has at least one of the following beneficial technical effects:

[0039] 1. The pipe has water-activated surface anti-fouling adhesion ability, can effectively resist the formation of biofilm, and can maintain a low hydraulic friction coefficient for a long time. The effect is due to the synergistic effect of polyethylene oxide, compatibilizer and molecular sieve components. In an aqueous environment, the material surface can be changed from a hydrophobic state to a hydrophilic state, forming a dynamic hydration layer. The hydration layer inhibits the initial adhesion of biological fouling through steric hindrance and thermodynamic repulsion, thereby ensuring the efficiency and stability of the siphon drainage system during long-term operation.

[0040] 2. The pipe realizes functionalization while maintaining excellent basic physical and mechanical properties. By introducing maleic anhydride grafted polyethylene as a compatibilizer, the compatibility problem between the non-polar polyolefin matrix and the strong polar polyethylene oxide is effectively solved. The compatibilizer forms an effective bond at the interface between the two phases, ensuring effective stress transfer between different phases, avoiding performance degradation due to phase separation, and making the pipe have both functionality and mechanical reliability as an engineering material.

[0041] 3. The preparation method of the present application effectively ensures the realization of the function of the final product and the stability of the performance by using a side feeding process. In view of the characteristics of polyethylene oxide being sensitive to heat and shear, it is added from the middle of the extruder, which significantly shortens its residence time in the high temperature and high shear region, thereby maximizing the avoidance of degradation of its molecular chain. This ensures the integrity of the molecular weight of polyethylene oxide, which is the basis for its surface dynamic reconstruction and anti-adhesion function, and improves the reliability of product performance and the stability of production process. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The figure is a structural function diagram of a twin-screw extruder used to prepare the pipe in the embodiments of the present application.

[0043] 1, main feeding port; 2, side feeding port; 3, vacuum devolatilization port; 4, melting and plasticizing section; 5, reaction mixing section; 6, die. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0045] The main raw materials and reagents used in the following examples and comparative examples are as follows, and the reagents not specifically described are commercially available analytical pure or higher grade products.

[0046] Polyolefin elastomer (POE), which is an ethylene-octene random copolymer. The octene content of the used grade is 25 wt%, the melt flow rate (MFR, test condition 190℃, 2.16kg) is 0.5g / 10min, and the density is 0.875g / cm 3 .

[0047] Ethylene-propylene rubber (EPM), which is a saturated ethylene-propylene binary random copolymer. The melt flow rate (MFR, test condition 230℃, 2.16kg) of the used grade is 1.8g / 10min, and the density is 0.879g / cm 3 .

[0048] Polyethylene oxide (PEO), CAS No. 25322-68-3, is a white free-flowing powder. Two grades are specifically used in the embodiments of the present application: PEO-1, with a weight average molecular weight of about 4,000,000g / mol; and PEO-2, with a weight average molecular weight of about 2,000,000g / mol.

[0049] Maleic anhydride grafted polyethylene (PE-g-MAH), which is a self-made compatibilizer, and its specific preparation method is described in the preparation example.

[0050] Molecular sieve, used as a water-activated channel component. Two types are specifically used in the embodiments of the present application: 3A type molecular sieve, which is a potassium type A zeolite with a nominal pore size of 3Å and an average particle size of 3μm; and 4A type molecular sieve, which is a sodium type A zeolite with a nominal pore size of 4Å and an average particle size of 4μm.

[0051] Compound antioxidant (AO), which is physically mixed by a main antioxidant pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (CAS No.: 6683-19-8) and an auxiliary antioxidant tris(2,4-di-tert-butylphenyl) phosphite (CAS No.: 31570-04-4) at a weight ratio of 1:1.

[0052] Preparation Example 1:

[0053] The preparation example provides a preparation method of maleic anhydride grafted polyethylene, comprising the following steps:

[0054] 100 parts by weight of low-density polyethylene (LDPE, melt flow rate of 2.5 g / 10 min), 2.5 parts by weight of maleic anhydride (MAH) and 0.2 parts by weight of initiator dicumyl peroxide (DCP) are uniformly premixed in a high-speed mixer. The mixture is added to a co-rotating twin-screw extruder with a length-diameter ratio L / D = 42 for a melt grafting reaction. The temperature of each zone of the extruder is set from the feeding port to the die as 150℃, 175℃, 190℃, 190℃, 185℃, 180℃, and the screw rotation speed is 200 rpm. The unreacted monomers and by-products are removed through a vacuum devolatilization port at the rear section of the extruder. After the extrudate is cooled in a water tank, cut by a granulator and dried, the product PE-g-MAH-1 is obtained. The maleic anhydride grafting rate of the product is 0.81wt% as determined by chemical titration.

[0055] Preparation Example 2:

[0056] The preparation example provides a preparation method of maleic anhydride grafted polyethylene, comprising the following steps:

[0057] The basic steps are the same as those in Preparation Example 1. The difference lies in that the ratio of each raw material is adjusted to 100 parts by weight of low-density polyethylene (LDPE, melt flow rate of 2.5 g / 10 min), 4.0 parts by weight of maleic anhydride (MAH) and 0.3 parts by weight of initiator dicumyl peroxide (DCP). The remaining process parameters remain unchanged. Finally, the product PE-g-MAH-2 is obtained. The maleic anhydride grafting rate of the product is 1.15wt% as determined by chemical titration.

[0058] Preparation Example 3:

[0059] The preparation example provides a preparation method of maleic anhydride grafted polyethylene, comprising the following steps:

[0060] The basic steps are the same as those in Preparation Example 1. The difference lies in that the ratio of each raw material is adjusted to 100 parts by weight of low-density polyethylene (LDPE, melt flow rate of 2.5 g / 10 min), 5.5 parts by weight of maleic anhydride (MAH) and 0.4 parts by weight of initiator dicumyl peroxide (DCP). The remaining process parameters remain unchanged. Finally, the product PE-g-MAH-3 is obtained. The maleic anhydride grafting rate of the product is 1.42wt% as determined by chemical titration.

[0061] Figure 1 The functional structure diagram of the double-screw extruder used in the embodiment of the application is shown.

[0062] As Figure 1As shown, the extruder is provided with a main feeding port 1, a lateral feeding port 2, a vacuum devolatilization port 3 and a die 6 in sequence along the material advancing direction. The entire cylinder can be divided into different regions according to functions, including a melting plasticizing section 4 and a reaction mixing section 5. During the preparation process, the base resin, the compatibilizer and the heat-resistant shear-resistant components such as molecular sieve are added through the main feeding port 1, and the melting and preliminary mixing are completed in the melting plasticizing section 4 at the front end of the extruder. Subsequently, the high molecular weight polyethylene oxide (PEO) sensitive to heat shear is added to the material in a molten state through the lateral feeding port 2 located after the melting plasticizing section 4. All the materials are fully and uniformly blended in the subsequent reaction mixing section 5. Before the material is extruded through the die 6, the small molecular volatiles in the system are removed through the vacuum devolatilization port 3.

[0063] This step-by-step feeding layout, especially the addition of polyethylene oxide (PEO) through the lateral feeding port 2, can significantly shorten the residence time of PEO in a high-temperature and high-shear environment, effectively avoid the excessive degradation of the molecular chain of PEO, and thus maximize the retention of the functionality of PEO.

[0064] Example 1:

[0065] The present embodiment provides a preparation method of a pipe material for siphon drainage, comprising the following steps:

[0066] (1) 89.5 parts by weight of polyolefin elastomer (POE), 3 parts by weight of maleic anhydride grafted polyethylene (PE-g-MAH-2, prepared in Preparation Example 2) and 0.5 parts by weight of a compounded antioxidant (AO) are dried in a blast drying oven at 85°C for 4 hours; 6 parts by weight of polyethylene oxide (PEO-1) is dried in a vacuum drying oven at 65°C for 8 hours; and 1 part by weight of 3A type molecular sieve is activated and treated in a muffle furnace at 220°C for 3 hours.

[0067] (2) The dried POE, PE-g-MAH-2, AO and activated 3A type molecular sieve in step (1) are added into a co-rotating twin-screw extruder with a length-diameter ratio L / D = 44 through the main feeding port.

[0068] (3) The dried PEO-1 in step (1) is added into the extruder through the lateral feeding port located in the middle section of the extruder.

[0069] (4) The temperature of each zone of the extruder is set to be 160°C, 180°C, 195°C, 200°C, 205°C, 205°C, 200°C from the feeding port to the die in sequence, and the screw rotation speed is 300 rpm, and the extrusion melt is obtained.

[0070] (5) The extrudate is vacuum sized, water tank cooled, pulled and cut to obtain a pipe material sample S1.

[0071] Example 2:

[0072] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the base resin in step (1) is replaced by 89.5 parts by weight of ethylene-propylene rubber (EPM). The final pipe material sample S2 is obtained.

[0073] Example 3:

[0074] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the functional additive in step (1) is replaced by 6 parts by weight of polyethylene oxide (PEO-2). The final pipe material sample S3 is obtained.

[0075] Example 4:

[0076] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the water-activated channel component in step (1) is replaced by 1 part by weight of 4A molecular sieve. The final pipe material sample S4 is obtained.

[0077] Example 5:

[0078] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the component ratio in step (1) is adjusted to 94 parts by weight of POE, 3 parts by weight of PEO-1, 2 parts by weight of PE-g-MAH-1 (obtained from Preparation Example 1), 0.5 parts by weight of 3A molecular sieve, and 0.5 parts by weight of AO. The final pipe material sample S5 is obtained.

[0079] Example 6:

[0080] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the component ratio in step (1) is adjusted to 82 parts by weight of POE, 10 parts by weight of PEO-1, 5 parts by weight of PE-g-MAH-3 (obtained from Preparation Example 3), 2.5 parts by weight of 3A molecular sieve, and 0.5 parts by weight of AO. The final pipe material sample S6 is obtained.

[0081] Example 7:

[0082] The present example provides a method for preparing a pipe material for siphon drainage, the steps of which are substantially the same as those of Example 1, except that the temperature of each zone of the extruder in step (4) is set to 150℃, 170℃, 185℃, 190℃, 195℃, 195℃, 190℃ from the feeding port to the die, and the screw rotation speed is adjusted to 200 rpm. The final pipe material sample S7 is obtained.

[0083] Example 8:

[0084] This example provides a method for preparing a pipe material for siphonic drainage. The steps are substantially the same as Example 1, except that the temperature of each zone of the extruder in step (4) is set to 170℃, 190℃, 205℃, 210℃, 215℃, 215℃, 210℃ from the feeding port to the die, and the screw speed is adjusted to 400 rpm. Finally, pipe material sample S8 is obtained.

[0085] Comparative Example 1:

[0086] This comparative example provides a method for preparing a conventional siphonic drainage pipe material. The formula only contains 99.5 parts by weight of high-density polyethylene (HDPE) and 0.5 parts by weight of a compounded antioxidant (AO), and is prepared into a pipe material by a conventional single-screw extruder. Finally, comparative pipe material sample DS1 is obtained.

[0087] Comparative Example 2:

[0088] Compared with Example 1, the difference is that the functional additives polyethylene oxide (PEO-1) and water-activated channel component 3A type molecular sieve are not added in the formula. In order to make the total weight parts 100, the amount of polyolefin elastomer (POE) is increased to 96.5 parts by weight. The remaining components and preparation steps are the same. Finally, comparative pipe material sample DS2 is obtained.

[0089] Comparative Example 3:

[0090] Compared with Example 1, the difference is that the compatibilizer maleic anhydride grafted polyethylene (PE-g-MAH-2) is not added in the formula. In order to make the total weight parts 100, the amount of polyolefin elastomer (POE) is increased to 92.5 parts by weight. The remaining components and preparation steps are the same. Finally, comparative pipe material sample DS3 is obtained.

[0091] Comparative Example 4:

[0092] Compared with Example 1, the difference is that the water-activated channel component 3A type molecular sieve is not added in the formula. In order to make the total weight parts 100, the amount of polyolefin elastomer (POE) is increased to 90.5 parts by weight. The remaining components and preparation steps are the same. Finally, comparative pipe material sample DS4 is obtained.

[0093] Comparative Example 5:

[0094] Compared with Example 1, the difference is the preparation process: all raw materials, including polyethylene oxide (PEO-1), are added to the extruder through the main feeding port, without using side feeding. The component ratio and process parameters of the remaining components are the same. Finally, comparative pipe material sample DS5 is obtained.

[0095] Comparative Example 6:

[0096] The difference compared with Example 1 is that the functional additive polyethylene oxide (PEO-1) and water-activated channel component 3A-type molecular sieve are not added in the formulation, but are replaced by 1 part by weight of silver-based inorganic antibacterial agent. In order to make the total weight parts 100, the amount of polyolefin elastomer (POE) is adjusted to 95.5 parts by weight. The remaining components and preparation steps are the same. Finally, the comparative pipe sample DS6 is obtained.

[0097] Test Example 1:

[0098] The experimental steps are as follows:

[0099] (1) Sample preparation: about 15 g of the pipe S1 prepared in Example 1 and the pipe DS5 prepared in Comparative Example 5 were respectively pulverized into powder under liquid nitrogen freezing condition using a pulverizer. Another raw material of polyethylene oxide PEO-1 without processing was taken as a control.

[0100] (2) Soxhlet extraction: about 10 g of the powder samples of S1 and DS5 were respectively placed in filter paper cylinders. The filter paper cylinders were placed in a Soxhlet extractor, 250 mL of tetrahydrofuran (THF) was added as an extraction solvent, the water bath temperature was set to 75°C (to ensure that THF refluxes), and continuous extraction was carried out for 24 hours.

[0101] (3) Separation and purification: the THF solution after extraction was transferred to a rotary evaporator, and the THF solvent was evaporated under the condition of a 40°C water bath and a vacuum degree of -0.08 MPa to obtain a viscous residue. The residue was transferred to a vacuum drying oven and dried at 60°C and a vacuum degree of -0.095 MPa for 12 hours to constant weight to obtain purified PEO.

[0102] (4) Solution preparation: 0.1 g of the purified PEO (and the PEO-1 raw material) was dissolved in a small amount of deionized water, then transferred to a 20 mL volumetric flask, and diluted to the mark line with deionized water, and shaken well. This step prepared a test solution with a concentration of 0.5 g / dL.

[0103] (5) Viscosity determination: the test solution and pure solvent (deionized water) were filtered through a 0.45 μm filter membrane and then injected into a pre-cleaned and dried Ubbelohde viscometer. The viscometer was placed in a constant temperature water bath at 25.0±0.1°C and kept at constant temperature for 15 minutes. According to the standard GB / T 12005.1-1989, the outflow time of the pure solvent and each sample solution was measured, and each sample was measured three times to calculate the intrinsic viscosity [η].

[0104] The experimental results are shown in Table 1.

[0105] Table 1 Effect of different processing methods on the intrinsic viscosity of PEO-1:

[0106] ;

[0107] The test data of Table 1 shows that different processing methods have a decisive influence on the molecular weight integrity of high molecular weight polyethylene oxide (PEO-1). The PEO-1 raw material without processing has the highest intrinsic viscosity value of 18.52 dL / g. The PEO intrinsic viscosity of the S1 sample prepared by the lateral feeding process of the application is 14.27 dL / g, and the viscosity retention rate reaches 77.1% compared with the raw material. In contrast, the PEO intrinsic viscosity of the DS5 sample prepared by the traditional main port co-feeding method decreases sharply to 6.84 dL / g, and the viscosity retention rate is only 36.9%.

[0108] The significant decrease of PEO intrinsic viscosity in the DS5 sample proves that when high molecular weight PEO is added together with other materials from the main feeding port, it undergoes long time high temperature and high mechanical shear throughout the length of the extruder, resulting in serious random chain scission of its molecular chain. This degradation is irreversible and will directly damage the functionality of PEO.

[0109] The lateral feeding process designed by the application is centered on introducing the PEO-1 component sensitive to thermal shear into the melt after the base resin (POE) has completed melting and plasticization. This process greatly shortens the residence time of PEO-1 in the extruder and avoids the most severe solid friction, compaction and melting shear zone at the front end of the screw. The high retention rate of PEO intrinsic viscosity in the S1 sample confirms that this process can effectively slow down the chain scission of PEO, thereby maintaining the relatively complete molecular structure of PEO in the final composite material.

[0110] The function of PEO in forming a low-friction hydrated layer on the inner wall of the pipe directly depends on its sufficiently long molecular chain structure, and a serious decrease in molecular weight will result in its inability to effectively function. Therefore, the results of this test example not only prove that the lateral feeding adopted by the application is a necessary feature to achieve the expected technical effect, but also is not a simple process adjustment.

[0111] Test Example 2:

[0112] The experimental steps are as follows:

[0113] (1) Sample pretreatment: The pipe prepared in Examples 1-8 and Comparative Examples 1-6 is cut into a sheet shape by mechanical processing. The sheet-shaped material is placed in a flat vulcanizing machine and hot-pressed into a uniform plate with a thickness of 2 mm at 190℃ and 15 MPa, and then cooled and shaped.

[0114] (2) Tensile property test: According to GB / T 1040.2-2006 standard, standard tensile samples were punched from the plate prepared in step (1) using a dumbbell-shaped sample puncher. The samples were clamped on a universal material testing machine, and the test environment was set to a temperature of 23±2°C and a relative humidity of 50±10%. The tensile rate was set to 100 mm / min, and the tensile strength and elongation at break were recorded. Five effective data were tested for each group of samples, and the arithmetic mean value was taken.

[0115] (3) Density test: Irregular small pieces of about 2 g were cut from the plate. According to the A method (immersion method) in GB / T 1033.1-2008, an electronic analytical balance (precision 0.1 mg) equipped with a density measurement assembly was used for testing, deionized water was used as the immersion liquid, and the density value of the sample was recorded.

[0116] (4) Hardness test: The plate was placed flat on the test platform. According to GB / T 2411-2008 standard, a Shore D hardness tester was used for testing. The pressure needle was vertically pressed on the sample surface, and enough pressure was applied to make the pressure foot completely contact the sample surface, and the reading was taken within 1 second. Five points were measured at different positions on the sample, and the arithmetic mean value was taken.

[0117] The experimental results are shown in Table 2.

[0118] Table 2: Basic physical and mechanical property test results of each sample

[0119] ;

[0120] The data results in Table 2 show that the pipe prepared by the present application maintains excellent physical and mechanical properties while introducing the water-activated self-cleaning function, which can meet the application requirements as a pipe material.

[0121] Firstly, compared with the comparative example DS1 (HDPE) as a conventional siphon drainage pipe material, all the examples (S1-S8) of the present application exhibit significantly different material properties. DS1 exhibits typical semi-rigid material characteristics: high tensile strength (28.3 MPa), high hardness (62 D), and moderate elongation at break (550%). The elongation at break of the examples of the present application is generally more than 800%, and the Shore D hardness is between 34 and 38, which indicates that the material has excellent flexibility and impact resistance, which is beneficial to the installation and construction of the pipeline and the reliability of long-term service.

[0122] DS3 lacks compatibilizer (PE-g-MAH) in the formulation, and its tensile strength (5.1 MPa) and elongation at break (210%) decrease compared with S1. The internal reason for this phenomenon is that polyethylene oxide (PEO) is a strong polar polymer, and the base resin polyolefin elastomer (POE) is a non-polar polymer, and there is inherent thermodynamic incompatibility between the two. Without a compatibilizer, the two components cannot form effective interfacial bonding during melt blending, resulting in macroscopic phase separation. After the material is solidified, the coarse phase and the fragile phase interface become stress concentration points and are easily damaged under external force, resulting in deterioration of the overall mechanical properties of the material. The embodiment of the present application introduces maleic anhydride grafted polyethylene as a compatibilizer, and the grafted polar group (maleic anhydride) forms hydrogen bonds or dipole interactions with PEO, while the non-polar polyethylene backbone is physically compatible with the POE matrix through chain entanglement. The compatibilizer plays a "bridge" role at the interface of the two phases, significantly improving the interfacial compatibility, allowing stress to be effectively transmitted between the continuous and dispersed phases, thereby ensuring the integrity of the mechanical properties of the composite material.

[0123] In addition, as can be seen from the comparison of S1 with S3, S4, S5, S6, S7 and S8, changing the molecular weight of PEO, the type of molecular sieve, the content ratio of each component and the processing parameters, the basic physical and mechanical properties of the material do not deteriorate and remain within the scope of high-performance elastomer pipes, proving that the technical solution has good stability and process tolerance.

[0124] In summary, the data of the test example confirm that the technical solution of the present application, while achieving functionalization, avoids the loss of mechanical properties of the composite material through key compatibility design, and the prepared pipe material has the basic physical and mechanical properties required as a high-performance flexible pipe material.

[0125] Test Example 3:

[0126] The experimental steps are as follows:

[0127] (1) Sample preparation and cleaning: The pipe materials prepared in Examples 1-8 and Comparative Examples 1-6 are processed into flat samples with a size of 2 cm x 5 cm. The samples are sequentially ultrasonically cleaned in acetone and deionized water for 15 minutes each to remove surface oil and impurities. Then the samples are placed in a 60°C air-drying oven for 4 hours for standby.

[0128] (2) Initial contact angle measurement: An optical contact angle measuring instrument is used to test in an environment with a temperature of 23±2°C and a relative humidity of 50±10%. A 3μL deionized water droplet is added to the surface of the sample by a microsyringe. The image is collected within 3 seconds after the water droplet stabilizes, and the tangent method is used to calculate the static water contact angle (θ 初始). Each sample was measured at 5 different locations and the arithmetic mean was taken.

[0129] (3) Water immersion activation: after the initial measurement, the sample was completely immersed in a beaker containing deionized water, and was placed at room temperature (23±2°C) for 30 minutes.

[0130] (4) Contact angle measurement after immersion: the sample was taken out of the water and immediately blown dry with a high-purity nitrogen stream. Within 1 minute after the surface was dried, the sample was placed back on the sample stage of the contact angle measurement instrument, 3 μL of deionized water was added again at a location close to the initial measurement, and the static water contact angle (θ 浸水后 ).

[0131] (5) Data analysis: the change in contact angle of each sample before and after immersion was calculated: Δθ = θ 初始 - θ 浸水后 .

[0132] The experimental results are shown in Table 3.

[0133] Table 3 Change in surface static water contact angle of each sample before and after water immersion

[0134] ;

[0135] The data results of Table 3 reveal the dynamic response characteristics of the wettability of the material surface of the present application. After contact with water, the surface of all the example samples (S1-S8) changed from a hydrophobic state (initial water contact angle > 95°) to a hydrophilic state (water contact angle after immersion < 50°), and the contact angle change value Δθ was greater than 45°. In contrast, the contact angle change value Δθ of all the comparative example samples (DS1-DS6) was significantly smaller, and did not exhibit effective dynamic transition of wettability.

[0136] The internal mechanism of this phenomenon is as follows: the composite material of the present application is rich in a non-polar polyolefin matrix (POE or EPM) on the surface in the dry state, and tends to form a low-energy interface with air in thermodynamics, thus exhibiting hydrophobicity in the macroscopic world. When the material surface is in contact with water, the molecular sieve as a water activation channel allows multiple water molecules to quickly penetrate into the near-surface region of the material. These water molecules undergo hydration with the strong polar polyethylene oxide (PEO) segments anchored in the matrix by the compatibilizer. The PEO segments after hydration will undergo conformational rearrangement and migrate to the interface between the material and water in order to reduce the interfacial energy of the entire system, thereby forming a PEO-rich hydration layer on the surface. This hydration layer changes the material surface to hydrophilic properties.

[0137] The results of the comparative examples inversely verify the necessary conditions of this mechanism:

[0138] DS1, DS2 and DS6 have permanent hydrophobic polyolefin surface due to the absence of core functional component PEO in the formulation, so the contact angle is basically unchanged before and after immersion.

[0139] DS3 lacks a compatibilizer, and PEO has poor compatibility with the matrix, and cannot form a uniformly dispersed microstructure. Even if PEO is present, it cannot effectively migrate to the surface or form a stable hydration layer on the surface, so the Δθ value is very small.

[0140] DS4 lacks molecular sieves. Although PEO and compatibilizers are present in the formulation, there is a lack of channels for water molecules to quickly penetrate. The process of water molecules entering the interior of the material becomes extremely slow, relying only on diffusion in the polymer matrix. Within the 30-minute test time, it is not sufficient to activate a sufficient amount of PEO to rearrange the surface, so its Δθ value (16.5°) is much lower than that of the examples.

[0141] The PEO molecular weight in DS5 is severely reduced due to improper processing (see Test Example 1), and even if the short-chain PEO migrates to the surface, it is difficult to form an effective and dense hydration layer, and its hydrophilization effect is greatly reduced, and the Δθ value is also very small.

[0142] In summary, the data of Test Example 3 confirms that only by reasonably compounding the core functional component (PEO), the water-activated channel component (molecular sieve), and the compatibilizer, and maintaining the integrity of the PEO molecular weight through a specific side feeding process, can the dynamic reversible change of the material surface from hydrophobic to hydrophilic be achieved. This unique surface property is the basis for the water-activated self-cleaning function of the material.

[0143] Test Example 4:

[0144] The experimental steps are as follows:

[0145] (1) Sample preparation and treatment: The pipe materials prepared in Examples 1-8 and Comparative Examples 1-6 are processed into square pieces with a size of 1 cm x 1 cm. The actual size of each piece is measured using a vernier caliper, and its surface area is calculated (note: including both front and back surfaces). The sample pieces are sequentially cleaned in 75% ethanol solution and deionized water for 15 minutes each, and then dried in a 60°C air-drying oven for 4 hours for standby.

[0146] (2) Standard curve preparation: The bovine serum albumin (BSA) standard was prepared into a series of standard solutions with concentrations of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 mg / mL using phosphate buffer solution (PBS, pH = 7.4).

[0147] (3) Adsorption experiment: The dry and clean sample pieces were respectively placed in the holes of 24-hole cell culture plates, 1.0 mL of BSA solution with a concentration of 1.0 mg / mL was added to each hole to ensure that the sample pieces were completely immersed. Meanwhile, blank control holes without sample pieces were set. The culture plates were placed in a constant temperature shaking incubator at 37°C and 60 rpm for 2 hours.

[0148] (4) Concentration determination: After incubation, the supernatant in each hole was carefully aspirated. According to the operation instruction of the BCA protein concentration determination kit: 20 μL of supernatant or standard solution was mixed with 200 μL of BCA working solution, and incubated at 37°C for 30 minutes in the dark. The absorbance value of each hole was determined at 562 nm wavelength using an enzyme-labeled instrument.

[0149] (5) Data calculation: The standard curve was plotted according to the absorbance value of the standard solution. The final concentration C of BSA in the supernatant after incubation of each sample hole was calculated by using the standard curve. f The protein adsorption amount per unit area was calculated according to the following formula:

[0150] BSA adsorption amount (μg / cm 2 ) = [(C0-C f ) × V] / A;

[0151] Wherein, C0 is the initial BSA concentration (1.0 mg / mL), V is the solution volume (1.0 mL), and A is the total surface area of the sample piece (cm 2 ).

[0152] The experimental results are shown in Table 4.

[0153] Table 4: Bovine serum albumin (BSA) adsorption amount on the surface of each sample:

[0154] ;

[0155] The data in Table 4 proves that the surface of the material of the present application has a significant anti-protein adsorption capacity. The BSA adsorption amount of all example samples (S1-S8) is less than 0.2 μg / cm 2 , which is at a very low level. On the contrary, the BSA adsorption amount of all comparative example samples (DS1-DS6) exceeds 1.4 μg / cm 2 , showing a significant protein affinity.

[0156] According to the theory of colloid and interface science, the non-specific adsorption of protein on the surface of material is mainly driven by hydrophobic interaction, electrostatic interaction and van der Waals force. In the technical solution of the present application, when the material is placed in an aqueous environment (such as a BSA buffer solution), the PEO chain segments on the surface of the material are activated and form a dense hydration layer, as shown in Test Example 3. This hydration layer physically constitutes a steric hindrance and simultaneously forms an energy repulsion field. Protein molecules attempting to approach the surface must first destroy the stable water molecules that are tightly bound to the PEO chain segments, which is a high-energy barrier process in thermodynamics. Therefore, the hydration layer can effectively prevent the direct contact and adsorption of proteins on the material matrix, thereby endowing the material surface with excellent anti-biofouling adhesion performance.

[0157] The results of the comparative examples confirm the integrity of the above-mentioned mechanism from different angles:

[0158] The matrices of DS1, DS2 and DS6 are typical hydrophobic polymers, and their surfaces will strongly adsorb proteins in a water environment through hydrophobic effect to reduce the interfacial energy of the entire system, which explains the extremely high protein adsorption amount.

[0159] Although DS3, DS4 and DS5 contain PEO in the formulation, due to the lack of a compatibilizing agent, a water-activated channel or PEO with a complete molecular chain, respectively, their surfaces cannot form an effective hydration layer under experimental conditions. Therefore, the surfaces of these samples still expose a large number of hydrophobic regions in nature, leading to a large amount of protein adsorption, and the results are similar to those of pure hydrophobic polymer surfaces.

[0160] In summary, the data of Test Example 4 prove the actual effect of the technical solution of the present application, and confirm that the water-activated surface constructed by specific component compounding and process control can fundamentally inhibit the initial adhesion of biological macromolecules, which has decisive significance for preventing the formation and development of biofilm on the inner wall of siphon drainage pipes.

[0161] Test Example 5:

[0162] The experimental steps are as follows:

[0163] (1) Circulation system setup: A closed-loop circulation system composed of a 30L water storage tank, a centrifugal pump, an electromagnetic flowmeter (accuracy ±0.5%), a differential pressure transmitter (range 0-50kPa, accuracy ±0.1% FS) and a test pipe section is set up. The pipe material prepared by Examples 1-8 and Comparative Examples 1-6 with an inner diameter D=50mm and a pressure measurement point spacing L=2.0m is connected horizontally into the system as the test pipe section.

[0164] (2) Initial friction factor measurement: The system was filled with deionized water, and the centrifugal pump was started and the valve was adjusted so that the electromagnetic flowmeter reading was stable at a value corresponding to a pipe flow velocity v = 4.0 m / s (Reynolds number Re > 200,000, belonging to the fully turbulent flow region). After the differential pressure transmitter reading ΔP initial was stable, the value was recorded. The initial friction factor f initial was calculated according to the Darcy-Weisbach formula.

[0165] f = (ΔP x D) / (L x p x v 2 / 2);

[0166] where p is the density of water at the experimental temperature.

[0167] (3) Accelerated fouling cultivation: The deionized water in the system was emptied and replaced with 30 L of pre-prepared and sterilized nutrient solution (beef extract 3 g / L, protein peptone 5 g / L). 1.5 L (5% v / v) of activated sludge obtained from a municipal sewage treatment plant was inoculated into the nutrient solution. The system flow rate was adjusted to a low-speed laminar flow state of about 0.3 m / s, and continuously circulated at 25°C for 14 days.

[0168] (4) Fouling post-friction factor measurement: After 14 days, the circulation was stopped. The nutrient solution was emptied and the system was flushed with deionized water at low speed for 5 minutes to remove suspended solids and loose attachments. Subsequently, the system was filled with deionized water again, and the flow rate was stabilized at v = 4.0 m / s, and the differential pressure transmitter reading ΔP fouled was stable, the value was recorded, and the fouling post-friction factor f fouled was calculated.

[0169] (5) Performance evaluation: The increase rate of friction factor Δf% was calculated by the following formula.

[0170] Δf% = [(f fouled -f initial ) / f initial ] x 100%;

[0171] The experimental results are shown in Table 5.

[0172] Table 5 Increase rate of friction factor of each pipe material sample before and after accelerated fouling test:

[0173] ;

[0174] The data in Table 5 reflect the ability of each pipe material to resist biofilm fouling under simulated long-term service conditions. The increase in the hydraulic friction factor of all example samples (S1-S8) was controlled to within 10% after 14 days of accelerated biofilm cultivation. The increase in the friction factor of all comparative sample (DS1-DS6) was more than 65%, and the increase in the friction factor of DS1, DS2, and DS6 was more than 90%, indicating that a biofilm layer had formed on the pipe wall, which severely affected the hydraulic performance.

[0175] The difference in macroscopic engineering performance is rooted in the microcosmic surface properties of the material. The hydration layer formed on the surface of the material of the present application in an aqueous environment (as shown in Test Examples 3 and 4) inhibits the initial adhesion and proliferation of microorganisms and extracellular polymeric substances (EPS) on the pipe wall through steric hindrance and thermodynamic repulsion. During the high flow rate flushing phase after the test, the hydration layer further reduces the binding force between the small amount of adhered biofilm and the pipe wall, making it easier for the fouling to be removed by the water flow. Therefore, the inner wall of the pipe material of the examples of the present application can remain relatively smooth for a long period of time, and the hydraulic performance decay is very small.

[0176] The results of the comparative examples demonstrate the necessity of the elements of the technical solution of the present application:

[0177] The surfaces of DS1, DS2, and DS6 are permanent hydrophobic surfaces, which are conducive to the initial adhesion of microorganisms, leading to rapid growth and maturation of the biofilm, a sharp increase in the roughness of the pipe wall, and a substantial increase in the friction factor.

[0178] DS3, DS4, and DS5 contain functional components, but due to the lack of key technical elements, they cannot form an effective anti-fouling surface. DS3 lacks a compatibilizer, resulting in interface failure; DS4 lacks a water-activated channel, resulting in a sluggish surface response; and the functional components in DS5 have degraded, losing their activity. These samples ultimately exhibit similar severe fouling consequences as ordinary hydrophobic materials.

[0179] The data of the present test example show that the technical solution proposed in the present application converts material design into a persistent and effective anti-fouling function, which can ensure that the siphon drainage system maintains its designed hydraulic conveying efficiency during long-term operation and reduces the maintenance requirements.

[0180] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pipe for siphon drainage, characterized in that The raw materials are made of the following components by weight: Polyolefin elastomer: 82-94 parts by weight; Polyethylene oxide: 3-10 parts by weight; Maleic anhydride grafted polyethylene compatibilizer: 2-5 parts by weight; Molecular sieve: 0.5-2.5 parts by weight; The pipe material for siphon drainage is prepared by the following steps: (a) adding polyolefin elastomer, maleic anhydride grafted polyethylene compatibilizer and molecular sieve through the main feeding port of the twin-screw extruder; (b) adding polyethylene oxide through the lateral feeding port after the melt plasticizing section of the twin-screw extruder; (c) melt blending in the extruder and extruding through a die.

2. The pipe for siphonic drainage according to claim 1, characterized in that, The parts by weight of the raw materials are: Polyolefin elastomer: 88-91 parts by weight; Polyethylene oxide: 5-7 parts by weight; Maleic anhydride grafted polyethylene compatibilizer: 2.5-3.5 parts by weight; Molecular sieve: 0.8-1.2 parts by weight.

3. The pipe for siphonic drainage according to claim 1, characterized in that, The polyolefin elastomer is ethylene-octene random copolymer or ethylene-propylene rubber; the molecular sieve is 3A type molecular sieve or 4A type molecular sieve.

4. The pipe for siphonic drainage according to claim 1, characterized by, The maleic anhydride grafting rate of the maleic anhydride grafted polyethylene compatibilizer is 0.8-1.5 wt%.

5. The pipe for siphonic drainage according to claim 1, wherein The raw materials further include 0.1-1.0 parts by weight of antioxidant.

6. The pipe for siphonic drainage according to claim 1, wherein Before step (a) and step (b), a step of pretreating the raw materials is further included: Drying treatment is performed on the polyolefin elastomer, polyethylene oxide and compatibilizer; activation treatment is performed on the molecular sieve.

7. The pipe for siphonic drainage according to claim 1, wherein The temperature of the extruder for melt blending is set to 150-215℃, and the screw rotation speed is 200-400 rpm.

8. The pipe for siphonic drainage according to claim 1, characterized by, The maleic anhydride grafted polyethylene compatibilizer is prepared by melt grafting reaction of low-density polyethylene, maleic anhydride and initiator.

9. The pipe for siphonic drainage according to claim 1, characterized in that, Before extruding, a step of devolatilization treatment of the melt material through a vacuum devolatilization port is further included.

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