Synergistic functionalized polyethylene/attapulgite composites with maleic anhydride and silicone by reactive extrusion for enhanced metal-plastic interfacial adhesion

Synergistic functionalized polyethylene/attapulgite composites with maleic anhydride and silicone by reactive extrusion for enhanced metal-plastic interfacial adhesion | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Synergistic functionalized polyethylene/attapulgite composites with maleic anhydride and silicone by reactive extrusion for enhanced metal-plastic interfacial adhesion Minglei Hu, Wei Zhang, Bin Hu, Fuqiang Chu, Haicun Yang, Zheng Cao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7267966/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Jan, 2026 Read the published version in Journal of Polymer Research → Version 1 posted 5 You are reading this latest preprint version Abstract To enhance both the adhesive strength and cohesion of the adhesive resin, attapulgite functionalized with peroxy groups (ATP-CPO) was prepared through surface chemical modification. Subsequently, a series of polyethylene/ATP composites (PE/ATP) functionalized with maleic anhydride and vinyl trimethoxysilane were prepared via surface-initiated graft copolymerization. The effects of ATP-CPO dosage on the mechanical, thermal, rheological, and morphological characteristics of the composites were evaluated in detail. It was found that the surface functionalization and reactive extrusion process contributed to the nano-scale dispersion of ATP in the PE matrix, forming well-compatibilized nanocomposites consisting of PE-g-(MAH-co-VTMS), ATP-g-(MAH-co-VTMS), and more complex MAH/VTMS synergistically functionalized ATP-g-PE. When the ATP-CPO content was 4%, the composite exhibited significantly enhanced tensile strength, peel strength, and shear strength, which were 1.4, 26.3, and 21.7 times higher than those of pure PE, respectively. Concurrently, the composites displayed higher melting and crystallization temperatures. However, the crystallinity decreased slightly, while the thermal stability was significantly improved. The melt exhibited more pronounced non-Newtonian behavior. Compared to the loss modulus, the storage modulus increased more significantly in the low-frequency region, and a non-terminal effect was observed, which enhanced the structural stability of the system under low-frequency shear stress. Polyethylene Attapulgite Graft copolymerization Composites Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction With the rapid development of social industry, various types of pipelines are widely used in energy and chemical fields such as liquid supply and gas transmission [ 1 – 3 ]. Steel wire-wound polyethylene composite pipes combine the advantages of high-strength steel wire reinforcement and polyethylene material. The inner layer is made of high-density polyethylene (HDPE), which offers excellent corrosion resistance and a smooth inner wall. The reinforcing layer is a net structure formed by winding high-strength steel wires, providing the mechanical strength of the pipe. The outer layer is also made of HDPE, which serves a protective and sealing role [ 4 , 5 ]. The bonding resin in steel wire-wound polyethylene composite pipes is a key material that ensures the close bonding between the steel wire and polyethylene. Polarized-modified polyethylene is a widely used bonding resin, providing bonding ability with the wire mesh while ensuring compatibility with the inner and outer HDPE layers [ 6 ]. Like most manufactured blended or composite polymer products, interfaces always exist in such pipes and dominate their service performance and life [ 7 , 8 ]. Because of their chemical inertness, low density, and low cost, olefin-based polymers are widely used in various fields, such as adhesives, adhesive layers, films, fibers, automobiles, buildings, and appliances [ 9 – 11 ]. However, the adhesive strength between olefin-based polymers and some polar substrates, such as polyester, polyamide, metal, and glass, is generally low [ 12 ]. To increase the polarity of olefin polymers, maleic anhydride (MAH)-functionalized polymers have been used as compatibilizers to improve the compatibility of polymer blends or composites, that is, to enhance the interfacial bonding strength [ 13 – 15 ]. However, the double bond in the maleic anhydride molecule is connected to a cyclic anhydride group, which creates significant steric hindrance during the polymerization process. This structure makes it difficult for maleic anhydride monomers to form stable free radical intermediates during polymerization, thus limiting their homopolymerization reaction [ 16 ]. Usually, a proper amount of styrene is added during the grafting process for copolymerization to increase the grafting rate. However, when used as an adhesive resin, the introduction of the nonpolar polystyrene (PS) segment can inevitably affect its adhesion to polar substrates [ 17 , 18 ]. For polyolefin composites, compared with functional modification of polyolefin, organic surface modification of inorganic particles by coupling agents is commonly an effective means to enhance the interfacial adhesion of composites [ 19 ]. For nonpolar polyolefin matrices, long-chain alkane silane coupling agents are often the first choice for inorganic particle modification [ 20 ]. Additionally, some reactive silane coupling agents, such as vinyl and methacryloyloxy siloxanes, can be used for surface modification with siloxane as the reaction point. These functionalized inorganic particles can then undergo grafting reactions on the polyolefin matrix in the presence of an initiator to enhance interfacial adhesion through covalent bonds [ 21 , 22 ]. In essence, these coupling agents have two types of active groups. Alkoxy groups can connect to the inorganic matrix through hydrolysis and condensation reactions, and can even form SiO₂ networks through sol-gel reactions [ 23 , 24 ]. Vinyl groups can enter the carbon chain through free radical polymerization, ultimately forming organic-inorganic hybrid materials based on covalent bonding [ 25 , 26 ]. When bonding non-powder inorganic substrates, such as metal or glass plates, and melt blending is not feasible, the sequence of the above reactions can be adjusted. For example, polyolefin grafted with vinyl silane can first be prepared by melt reaction extrusion, and then bonded to planar inorganic matrices through condensation reactions. Polyolefin elastomer (POE) grafted with silane has been widely used in photovoltaic field [ 27 ]. However, this method requires strict control of the reactive extrusion process to prevent surface cross-linking and loss of adhesion. Cohesive failure refers to the separation of the adhesive within the cured layer of the adhesive, meaning the adhesive itself is torn apart. This failure mode indicates that the adhesive's cohesive strength is lower than its bonding strength with the adherend. When peeling failure occurs within the adhesive itself, it suggests that the bonding strength between the adhesive and the adhered material is greater than that of the adhesive itself [ 28 , 29 ]. This type of failure has been observed in thermosetting adhesives and may result from the disruption of intermolecular interactions between adhesive molecules. However, in thermoplastic adhesive resins, cohesive failure is primarily due to the decreased structural stability caused by too low a matrix molecular weight and insufficient chain entanglement density. These adhesive resins are more prone to failure in practical applications, especially under high shear stress, which further affects the stability of the adhesive system. For most adhesive resins, cohesive strength can be enhanced through proper crosslinking and the addition of reinforcing fillers [ 30 , 31 ]. While crosslinking improves adhesive strength, adding reinforcing fillers is often the preferred method. Attapulgite, a natural clay mineral with a unique fibrous crystal structure, significantly boosts the cohesive strength of adhesive resins due to its high specific surface area and excellent dispersibility. Its fibrous structure forms physical cross-linking points within the resin matrix, thereby enhancing cohesive strength [ 32 , 33 ]. Additionally, attapulgite improves the thermal stability of adhesive resins, allowing the cohesive strength of nano-composite adhesive resins to be better maintained at high temperatures [ 34 ]. It also increases the crystallinity of adhesive resins, which enhances cohesive strength by increasing molecular interactions [ 35 ]. Furthermore, attapulgite acts as an anti-aging agent, protecting adhesive resins from light, heat, and oxidation, thus extending their service life [ 36 ]. However, to our knowledge, there are no research reports on polyolefin adhesive resins modified by inorganic nanoparticles. Herein, the objective was to prepare PE/ATP composites with enhanced adhesive and cohesive strength. Initially, ATP was chemically modified to introduce a cumene peroxide group as an initiator. Subsequently, PE/ATP composites were obtained through reactive extrusion, synergistically functionalized with maleic anhydride and silicone. The chemical modification mitigated ATP agglomeration, while reactive extrusion further optimized ATP dispersion and enhanced both adhesion and cohesive strength. The influence of functional ATP content on the structure and properties of the composites was investigated in detail. 2. Experimental section 2.1. Materials Polyethylene (DMDA-8008H) was purchased from PetroChina Dushanzi Petrochemical Co. Ltd. (Xinjiang, China). Vinyltrimethoxysilane (VTMS, ≥ 98%), 3-chloropropyltrimethoxysilane (CPTMS, 98%), 4-dimethylaminopyridine (DMAP, ≥ 98%), and maleic anhydride (MAH, ≥ 99%) were bought from Aladdin-reagent Co. Ltd. (Shanghai, China). Dry toluene (AR), ethanol (AR), cumyl hydroperoxide (CHPO, 80 wt% in toluene) were all obtained from Sinopharm Chemical Reagent (Shanghai, China). All reagents were used directly without purification. 2.2. Synthesis of ATP-suppported cumyl peroxide (ATP-CPO) Typically, 5 g of ATP, 10 mL of CPTMS, and 150 mL of anhydrous toluene are mixed uniformly under ultrasonication in a 250 mL round-bottomed flask. and the resulting mixture was heated to reflux for 10 h. After reaction, the solid product was separated by suction filtration, washed several times with anhydrous ethanol, and finally dried under vacuum at 50 ℃ for 24 h to obtain ATP-CPTMS. Subsequently, 5 g of the dried ATP-CPTMS was ultrasonically dispersed in 150 mL of anhydrous toluene, and 10 g of CHPO solution (0.052 mol) and 1.22 g of DMAP (0.01 mol) were added. After bubbling with N 2 for 30 min, the flask is sealed and the mixture was stirred at 40 ℃ for 24 h. After suction filtration, the solid product is repeatedly washed with anhydrous ethanol, and finally dried in a vacuum oven at room temperature for 24 h to prepare ATP-CPO. 2.3. Preparation of HDPE-g-(MAH-co-VTMS) via surface-initiated graft polymerization According to the formula in Table 1 , MAH, VTMS, and antioxidant were first dissolved in acetone, and then ultrasonicated after ATP-CPO was added to obtain a uniform dispersion. Next, the dispersion and HDPE was mixed in a high-speed mixer evenly at room temperature and then reactively blended by a twin-screw extruder to prepare the hybrid PE- g -(MAH- co -VTMS). The temperatures of screw were set at 135, 155, 180, 195, 195, 195, 190, 190, and 180 ℃, respectively, and the screw rotation speed was 180 r/min. The prepared HDPE- g -(MAH- co -VTMS) was finally injection molded into standard species for different mechanical testing at 200 ℃, and also molding compressed into rheological samples using a flat vulcanizer. Table 1 Formula of PE/ATP composites Sample PE/% ATP-CPO/% MAH/% VTMS/% Antioxidant/% PE 100 — — — — ATP-CPO 1% 96.7 1 1.5 0.5 0.3 ATP-CPO 2% 95.7 2 1.5 0.5 0.3 ATP-CPO 4% 93.7 4 1.5 0.5 0.3 ATP-CPO 8% 89.7 8 1.5 0.5 0.3 2.4. Characterization The chemical composition of modified ATP and hybrid HDPE were characterized by Nicolet IS10 Fourier transform infrared spectra (FTIR, Nicolet Instruments, Inc., USA) in the frequency range of 500–4000 cm − 1 in transmission and ATR mode, respectively. The element composition change of ATP and HDPE was determined on an HI5000 VersaProbe IV X ray photoelectron spectroscopy (XPS, ULVAC-PHI, Inc., Japan) with a nonmonochromatic X-ray source (Al Kα radiation as the exciting source). The micromorphology of the hybrid materials were observed on a SUPPRA-55 field emission scanning electron microscope (FESEM, Carl Zeiss, Inc., Germany) and JSM-6360LA Scanning Electron microscopy (SEM, JEOL Inc., Japan). The samples were fractured in liquid nitrogen and then observed after the section was sprayed with gold. The thermal degradation behavior was evaluated by a TG209 F3 thermogravimetric analysis system (NETZSCH Premier Technologies LLC., Germany) at a heating rate of 10°C/min in the range of 30–800°C under a nitrogen atmosphere. The melting and crystallization behavior were measured on a DSC800 differential scanning calorimeter (DSC, Perkin Elmer, Inc., USA) in the temperature range of 50–180°C at a heating rate of 10°C/min. The tensile properties and peel strength of the samples were tested on a WDT-10 universal material tester (Shenzhen Kaiqiangli Testing Instrument Co. Ltd., China) at room temperature. Tensile yield strength were tested under a tensile speed of 50 mm/min according to Chinese national standards GB/T 1040–2006. Peel strength was tested according to Chinese national standards GB/T 2792 − 2014. The composite material was first molded into a 300×300 mm square piece, and then bonded to an stainless steel plate of the same size at 200 ℃. Finally, the bonded piece was cut into a 300 × 15 mm rectangular spline and tested at a separation rate of 50 mm/min. Shear strength was test according to Chinese national standards GB/T 7124 − 2008. Two stainless steel plates were bonded with composite resin using hot pressing. The thickness of the resin layer was 200 µm, the bonding length was 50 mm, and the tensile rate was 1 mm/min. The melt flow rates (MFR) were tested on an MTM1000 melt flow index machine (Shenzhen SUNS Technology Stock Co., Ltd., China) at 190°C and 2.16 kg according to Chinese national standards GB/T 3682 − 2018. The vicat softening temperature (VST) was tested on a VTM1300 microcomputer controlled Vicat softening temperature testing machine (Suns Co., Ltd, Shenzhen, China) according to China standard GB/T1633-2000, and samples with size of 10 mm × 10 mm × 4 mm were tested under 10 N at a heating rate of 120°C/h. The rheological behavior was characterized on a Discovery HR-30 rotational rheometer (TA Instruments, Inc., USA) at 170°C using a parallel plate model with a gap of 1 mm. 3. Results and discussion 3.1 Preparation of synergistic functionalized PE/ATP composites The changes in functional groups during ATP modification were characterized by FTIR, with the results shown in Fig. 1 a. In the FTIR spectrum of crude ATP, the peak at 3558 cm⁻¹ corresponds to the stretching vibration of surface hydroxyl groups. The peak at 1658 cm⁻¹ is attributed to water in the crystal structure, while the peaks at 1033 and 983 cm⁻¹ are associated with the stretching vibrations of the Si-O-Si tetrahedron. After modification with CPTMS, new peaks emerged in the ATP-CPTMS spectrum: the C-H stretching and bending vibrations appeared at approximately 2933 and 1473 cm⁻¹, respectively, and the C-Cl stretching vibration was observed at 793 cm⁻¹. These new characteristic peaks, originating from the chloropropyl groups, confirm the successful grafting of CPTMS onto the ATP surface. Upon further reaction with CHPO, the C-Cl peak at 793 cm⁻¹ disappeared. Concurrently, new peaks appeared: the C-H stretching vibration on the benzene ring at 3066 cm⁻¹, the benzene ring skeleton vibrations at 1618 and 1525 cm⁻¹, and the C-O stretching vibration at 1214 cm⁻¹. These results collectively demonstrate the successful synthesis of ATP-CPO. The elemental composition of modified ATP was determined by XPS full-scan spectrum, as shown in Fig. 1 b. The dominant signal peaks for ATP are observed at 130.1 eV (Si2p), 154.2 eV (Si2s), 285.0 eV (C1s), and 532.1 eV (O1s). The C1s peak is attributed to a small amount of organic contamination, while the other elements align with the chemical composition of ATP. After modification with CPTMS, the signal intensities of the C element and Si in ATP-CPTMS are enhanced, and a new signal peak for Cl2p appears at 200.1 eV, confirming the introduction of CPTMS. Following the grafting of CPO, the Cl2p signal peak in ATP-CPO nearly disappears, and the intensity ratio of the C1s to O1s signal peaks increases significantly. This corresponds to the grafting of the high-carbon-content CPO group through the removal of HCl. The TGA and DTG curves of ATP, ATP-CPTMS, and ATP-CPO are shown in Figs. 1 c and d . The thermal decomposition process of pure ATP comprises four stages. The weight loss before 100°C is attributed to surface-adsorbed water, which reduces its compatibility with nonpolar polymers. The subsequent weight loss with increasing temperature corresponds to the loss of bound water within the rod crystal structure, culminating in a final weight loss rate of 9%. After modification with CPTMS, the TGA curve of ATP-CPTMS shows a more pronounced weight loss before 100°C. The introduction of organic components significantly reduces the water absorption of the ATP surface. Concurrently, the intensity of the third weight loss peak at 350°C in the DTG curve is notably enhanced, corresponding to the decomposition of the surface-grafted CPTMS. This results in a final weight loss rate of 15.7%. Upon further grafting with CPO, the weight loss peak intensity at 185°C in the DTG curve of ATP-CPO increases significantly, corresponding to the decomposition of peroxy groups. With the addition of more organic components, the weight loss peak intensity at 400°C further increases, leading to a final weight loss rate of 24.7%. These changes in thermal decomposition behavior fully confirm the successful grafting of CPTMS and CPO. The PE and ATP components in the composite were dissolved and separated using xylene, and characterized by FTIR and XPS, respectively. The results are shown in Fig. 2 . In the FTIR spectrum of pure PE (Fig. 2 a), the peaks at 2915 and 2828 cm⁻¹ correspond to the antisymmetric and symmetric stretching vibrations of C-H, respectively. The peaks at 1436 and 720 cm⁻¹ are attributed to the bending and rocking vibrations of C-H, respectively. For PE extracted from the composites, the C = O stretching vibration peak corresponding to MAH appears at 1744 cm⁻¹, and the Si-O-Si stretching vibration peak appears at 963 cm⁻¹, which may correspond to the hydrolysis and condensation of some alkoxy groups reflected by a relatively weak hydroxyl characteristic peak at 3450 cm⁻¹. The Si-O-C stretching vibration peak is observed at 1090 cm⁻¹, and the C-H bending vibration peak in the range of 1300–1400 cm⁻¹ is more pronounced. These results fully confirm that the PE macromolecular chain was simultaneously grafted with MAH and VTMS copolymers. Accordingly, in the infrared spectrum of extracted ATP, in addition to the characteristic peaks of ATP itself, there are C-H stretching vibration peaks at 2917 and 2878 cm⁻¹, a C = O vibration peak at 1735 cm⁻¹, and a Si-O-C stretching vibration peak at 1118 cm⁻¹. The peaks in the range of 1300–1400 cm⁻¹ are significantly enhanced and belong to the grafted PE segments. These results indicate that the composites consist of PE-g-(MAH-co-VTMS), ATP-g-(MAH-co-VTMS), and more complex ATP-g-PE with cooperative functionalization of MAH/VTMS. Figure 2 b shows the FTIR spectrum of ash and pure SiO₂ extracted from PE after calcination. The peak at 3550 cm⁻¹ corresponds to the stretching vibration of surface hydroxyl groups, the peak at 1650 cm⁻¹ corresponds to adsorbed water, and the peak at 812 cm⁻¹ corresponds to the symmetric stretching vibration of Si-O. The positions of all characteristic peaks are almost identical to those of pure SiO₂, indicating that the calcined ash is primarily composed of SiO₂. The chemical composition of the ash was further analyzed by XPS. As shown in Fig. 2 c and d , the signals of O and Si elements are predominantly observed in the XPS full-scan spectrum, with a small amount of C element possibly representing organic impurities remaining from the calcination process. The Si2p peak in Fig. 2 d can be fitted into four peaks: O-Si-C at 101.9 eV, Si2p₁/₂ at 103.4 eV, Si2p₃/₂ at 104.1 eV, and Si-O at 105.1 eV. These analytical results further confirm the graft copolymerization of VTMS and MAH. Figure 3 illustrates the micromorphology of crude and extracted ATP. The TEM and FESEM images of crude ATP shown in Fig. 3 a and b reveal that the structural unit of pure ATP is a fibrous rod crystal with a high aspect ratio. These rod crystals with a relatively smooth surface and a diameter of 15–20 nm are aggregated into larger bundles through hydrogen bonds between hydroxyl groups on their surfaces. However, as depicted in Fig. 3 c and d , the morphology of ATP extracted from the composites has changed significantly. The size of the rod crystals has increased noticeably, and the distinct core-shell structure provides clear evidence that graft polymerization has occurred between ATP and some PE substrates, as well as MAH and VTMS. 3.2 Mechanical properties and micromorphology Figure 4 a illustrates the effect of ATP-CPO content on the tensile strength of composites. Pure PE has a tensile strength of 26.8 MPa and an elongation at break of 672.5%. With the addition of ATP-CPO, the tensile strength of the composites increases gradually. When the ATP-CPO content reaches 4%, the tensile strength peaks at 37.2 MPa, while the elongation at break decreases to 477.9%. ATP, with its high aspect ratio, significantly reinforces polymer composites. The modification with CPO groups effectively reduces the aggregation tendency of ATP. Additionally, the immobilized CPO groups can trigger the graft copolymerization of MAH, VTMS, and PE during melt extrusion. This process significantly enhances the compatibility of the system and the interfacial affinity between the PE matrix and ATP. The uniformly dispersed ATP acts as a stress concentration point. When the interface is strengthened, stress can be effectively transferred through the matrix, and a large amount of energy is dissipated through interface failure, thereby enhancing the overall strength of the system. However, the enhancement of interfacial strength and the formation of an organic-inorganic hybrid network structure restrict the relative sliding of PE macromolecular chains, leading to a decrease in elongation at break. As the ATP-CPO content increases further, the tensile strength decreases. This decline may be attributed to the agglomeration of ATP-CPO within the system, which weakens the reinforcing effect. Figure 4 b shows the peeling strength of various composite materials. Pure PE exhibits a peeling strength of only 5.2 N/cm. This low value is attributed to PE's nonpolar nature, which results in weak bonding between PE and metal. Only a small amount of PE can embed itself into the surface defects of the steel plate to achieve bonding. In contrast, the composites show a significant enhancement in peeling strength. The main components in the composites prepared by surface-initiated graft copolymerization are polar molecules, which increase their affinity with metals. Additionally, the anhydride and alkoxy groups of MAH and VTMS in the composites can react with the hydroxyl groups on the metal surface, forming covalent bonds between the composite materials and the metal, thereby further enhancing the bonding strength. With the increase of ATP-CPO content, the amount of graft copolymer in the system increases, and the peeling strength correspondingly rises. When the ATP-CPO content reaches 4%, the peeling strength is attained to 136.6 N/cm, which is 26.3 times higher than that of pure PE. Similarly, at higher ATP-CPO contents, agglomeration may bury some CPO groups, which cannot effectively initiate graft copolymerization after decomposition, leading to a decrease in peel strength. In addition, it also includes the reasons for the decrease of wettability due to the significant increase of cohesive strength. In Fig. 4 c, the variation tendency of shear strength is similar to the previously mentioned peeling strength. The introduction of a large number of polar groups and the formation of covalent bonds between these groups and the metal surface result in a maximum shear strength of 15.2 MPa when the ATP-CPO content is 4%, indicating strong adhesion. Figure 4 d displays the melt index of different composite materials. As expected, the melt index of the composites decreases gradually with increasing ATP-CPO content. This decrease is attributed to the enhanced interfacial interactions, intermolecular forces, and the formation of an organic-inorganic hybrid network structure, which restrict the thermal movement of the macromolecular chains and reduce the system's fluidity. Although the melt index drops to 3.6 g/min at an ATP-CPO content of 4%, it still meets the fluidity requirements for adhesive resins. Figure 5 presents the cross-sectional morphology of pure PE and the composite containing 4% ATP-CPO. In Fig. 5 a, the cross-section of pure PE appears relatively smooth, with a few protrusions resulting from plastic deformation during brittle fracture. In contrast, the cross-section of the composite retains some characteristics of plastic deformation. In Fig. 5 b, most of the ATP is dispersed in the PE matrix at the nanoscale, although there are a few aggregates with sizes ranging from 200 to 400 nm. The functionalization with CPTMS and CPO mitigates the agglomeration of ATP and enhances the interfacial affinity between ATP and the matrix through surface-initiated graft copolymerization, thereby achieving true nano-composition. Figure 5 c presents a SEM image of the bonding surface after the shear strength test. The resin on the bonding surface exhibits significant plastic deformation along the direction of shear stress. This deformation is attributed to the tearing of the resin at the interface during the shear failure process, which confirms the strong bonding between the composite material and the stainless steel plate. The SEM image of the stainless steel plate interface after shear failure in Fig. 5 d shows obvious resin residue traces on the surface. Meanwhile, the C elemental mapping image of the bonding surface of the stainless steel indicates that the residual layer is composed of a large number of carbon elements. This further confirms that the residual material is adhesive resin, and there is strong adhesion between them. 3.3 Thermal properties The thermal properties of the composites were evaluated using TGA and DSC, with the results shown in Fig. 6 and the related parameters summarized in Table 2 . The TGA curves of different composites are depicted in Fig. 6 a. Pure PE has an initial decomposition temperature of approximately 430°C (T wt5% ), with a final mass residual rate of 0.9%. Upon adding ATP-CPO, the initial decomposition temperature of the composites increased to 431.9, 433.6, 444.3, and 488.2 ℃, respectively, and the final mass residual rate ( Mrr ) rose to 3.5%, 3.7%, 5.4%, and 12.4%, respectively. ATP-CPO forms an organic-inorganic hybrid network structure within the system through surface-initiated graft copolymerization. This denser microstructure restricts the thermal movement of molecular chains during heating, delaying the thermal decomposition reaction of the matrix and thus gradually increasing the initial decomposition temperature. The increase in mass residual rate is attributed to the presence of the ATP component, while the silicone component enhances the thermal stability of the char during thermal decomposition, hindering further decomposition. In the DTG curve shown in Fig. 6 b, pure PE exhibits a peak decomposition rate ( Dr max ) of 3.13%/°C at 478.2°C. In contrast, the peak decomposition rate temperature ( T dmax )of the composites rises to 496.9, 506.5, 506.9, and 507.1°C, respectively, with decomposition rates all lower than that of pure PE. This is because the dense network structure prevents the overflow of degraded small molecular products, thereby delaying the mass loss process. However, as the ATP-CPO content increases, the highest decomposition rate also rises gradually. This is due to the low specific heat capacity of ATP. The introduction of more ATP-CPO may increase the overall temperature gradient, causing the adjacent matrix to decompose at a higher stability first and then leading to internal porosity, which ultimately accelerates the decomposition process of the entire matrix. Overall, the thermal stability of the composites was enhanced after ATP-CPO initiated graft copolymerization. Figure 6 c presents the crystallization curves of various composite materials, all of which exhibit a single crystallization peak. Pure PE has a crystallization temperature of 118.2°C. As the ATP-CPO content increases, the crystallization temperatures ( T c ) of the composites rise to 119.5, 120.3, 120.8, and 121.6°C, respectively. These temperatures are higher than that of pure PE. The even dispersion of ATP within the matrix increases the number of nucleation sites during the crystallization process. On one hand, it promotes the orderly arrangement of PE macromolecular chains around ATP through heterogeneous nucleation, thereby reducing the crystallization energy barrier. On the other hand, the organic-inorganic hybrid network structure formed by graft copolymerization restricts the movement of PE macromolecular chains, enabling them to crystallize at higher temperatures. However, this structure also limits crystal growth, which affects the crystallinity of the system. Figure 6 d displays the melting curves of different composites. As the ATP-CPO content increases, the melting peak temperature ( T m ) of the composites initially decreases and then increases. When the ATP-CPO content is 1%, the melting peak temperature of the composites is slightly lower than that of pure PE. This may be due to the organic-inorganic hybrid network structure, which decreases the molecular chain migration speed and improves the perfection of the crystal region, resulting in a slight decrease in melting temperature. However, as the ATP-CPO content increases, the high-strength network structure increasingly restricts the thermal movement of the PE macromolecular chains. The stability of the crystal region formed by heterogeneous nucleation is enhanced due to the presence of embedded ATP, leading to a gradual increase in melting temperature. From the trend of crystallinity ( χ ) changes, it can be seen that the crystallinity of the composites slightly increases at low ATP-CPO content because the system is still dominated by homogeneous nucleation, with heterogeneous nucleation providing additional nucleation sites. In contrast, at high ATP-CPO content, heterogeneous nucleation plays a dominant role, but the alignment of macromolecular chains to crystalline regions is impeded, resulting in a decrease in crystallinity. Finally, the formation of physical and chemical cross-linking structures, the limitation of molecular chain movement, and the improvement of thermal stability all contribute to the gradual increase in the VST value with increasing ATP-CPO content. Table 2 Thermal properties of PE and different composites Sample T m /℃ T c /℃ χ /% T 5wt% /℃ T dmax /℃ Dr max /(%/℃) Mrr /% VST /℃ PE 131.6 118.1 74.8 430 478.2 3.13 0.9 128.6 ATP-CPO 1% 130.8 119.5 76.2 431.9 496.9 1.61 3.5 129.8 ATP-CPO 2% 131.8 120.3 74.4 433.6 506.5 1.83 3.7 131.2 ATP-CPO 4% 132.9 120.8 73.1 444.4 506.9 2.38 5.4 133.4 ATP-CPO 8% 133.7 121.5 72.3 448.2 507.1 2.62 12.4 134.6 3.4 Rheological behavior The change in the microstructure of composites can be reflected by changes in their rheological behavior, as shown in Fig. 7 . In the strain scanning curve (Fig. 7 a), the storage modulus (G’) of all composites remains relatively constant in the linear viscoelastic region. Under shear stress, the macromolecular conformation changes as molecular segments move to reach a stable state, resulting primarily in a reversible elastic response. Simultaneously, as the ATP-CPO content increases, the storage modulus in the linear viscoelastic region of the composites initially increases and then decreases under different strains, exhibiting the Payne effect. Compared with pure PE, the thermal decomposition of peroxy groups in ATP-CPO leads to the graft copolymerization of MAH and VTMS onto PE, forming an organic-inorganic hybrid network structure within the system. Grafting MAH increases the intermolecular forces between PE macromolecules. Additionally, the hydrolysis and condensation of a small amount of VTMS further enhance the mutual interactions between these macromolecules. The physical entanglement formed by ATP also restricts the movement of segments, leading to more elastic energy being stored under the same strain. As a result, the storage modulus of the system increases. When the ATP-CPO content is 4% and 8%, two plateaus appear in the strain scanning curve of the composites. This may be due to the formation of agglomerated bodies with high ATP-CPO content, leading to more metastable network structures in the system, which can be destroyed under small strain. However, the values of G’ for the two plateaus are not significantly different, indicating that these metastable networks have little effect on the overall structural strength of the composite. As the strain increases, irreversible relative slip between molecular chains begins to occur along the direction of strain increase, causing G’ to gradually decrease. With increasing ATP-CPO content, the linear viscoelastic region expands, which is different from most particle-filled systems. Under the action of peroxide groups, ATP and PE matrix molecular chains are more firmly bonded by covalent bonds, enhancing the strain stability of the melt structure of the composites. The linear viscoelastic behavior of the composites was further investigated through frequency scanning. Figure 7 b illustrates the changes in complex viscosity of the composites with shear frequency. In the low-frequency region, pure PE exhibits minimal dependence of complex viscosity on frequency, as the rate of entanglement breaking of macromolecular chains is similar to the rate of reconstruction. As the shear rate increases, it gradually exhibits shear-thinning behavior. With increasing ATP-CPO content, the dependence of complex viscosity on shear frequency in the low-frequency region becomes more pronounced, and the complex viscosity gradually increases. This increase is attributed to the growing blocking effect of the crosslinking and chain entanglement network on the movement of macromolecular chains. However, a large number of physical entanglement points are prone to disintegration under shear, leading to a significant decrease in complex viscosity. Additionally, rigid ATP particles tend to orient under shear, further disentangling the chains and making shear-thinning more pronounced. In the high-frequency region, the complex viscosity of all composites shows little difference. This is because, at high frequencies, PE macromolecular chains are primarily disentangled. Figure 7 c illustrates the variation of the storage modulus ( G ’) of the composites with shear frequency. As the shear frequency increases, the G ’ of all samples gradually rises, and the differences among them diminish. This trend is attributed to the long relaxation times of the macromolecular chains. At high frequencies, the molecular chains do not have sufficient time to rearrange in response to external forces, thus exhibiting greater rigidity. In the low-frequency region, the G ’ gap among the composites is more pronounced. With increasing shear rate, the G ’ of the composites increases, and its dependence on shear frequency decreases. The appearance of a plateau trend (non-terminal effect) indicates enhanced solidity of the composites. This enhancement is due to the formation of a network structure via surface-initiated graft copolymerization, which effectively stores elastic energy at low frequencies, thereby significantly boosting the storage modulus. Moreover, the increased entanglement density reduces the free volume of the PE macromolecular chains, significantly inhibits their long-range movement, extends the relaxation time further, and consequently raises the storage modulus in the low-frequency region. This increase is beneficial for maintaining structural stability under low-frequency stress. Figure 7 d illustrates the variation of the loss modulus ( G ’’) of the composites with shear frequency, exhibiting a trend similar to that of G ’. However, in the low-frequency region, the G ’’ of the composites increases with the addition of ATP-CPO. This increase is attributed to the heightened internal friction of molecular chain movement in the presence of ATP-CPO, which extends the relaxation time and consequently enhances the hysteresis of molecular chain movement, leading to an elevated G ’’. Despite this increase, the rise in G ’’ is notably less pronounced than that of G ’, further indicating that the incorporation of ATP-CPO more significantly enhances melt elasticity and solidity. 4. Conclusions In summary, this work described the preparation of PE/ATP composites synergistically functionalized with MAH and VTMS by surface-initiated graft copolymerization using ATP-CPO as the initiator. the effects of ATP-CPO content on the mechanical properties, thermal properties, and rheological behavior of the composites were systematically investigated. The functionalization of CPO groups on the surface alleviated the aggregation tendency of ATP, and surface-initiated graft copolymerization significantly enhanced the interfacial strength of the composites, achieving nano-scale dispersion of ATP, resulting in a signicant enhancement on both cohesive strength and adhesive strength. When the ATP-CPO content was 4%, the tensile strength, peeling strength, and shear strength of the composites were 1.4, 26.3, and 21.7 times higher than those of nonpolar pure PE, respectively, accompanied by enhanced thermal stability and a slight decrease in crystallinity. The complex viscosity of the composite melt in the low-frequency region was significantly increased with a more pronounced shear-thinning behavior. The storage modulus shows a more substantial increase than the loss modulus, and a non-terminal effect is observed, indicating improved structural stability of the system under low-frequency shear stress. We believe that the composites prepared in this work are expected to be used as high-performance adhesive resin for steel wire wound reinforced polyethylene composite pipes. Declarations Declaration of Competing Interest All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript. Author contribution Minglei Hu : Conceptualization, Formal analysis, Methodology, Investigation, Data curation, Writing-original draft. Investigation, Formal analysis, Validation. Wei Zhang : Resources, Funding acquisition; Bin Hu : Resources, Funding acquisition; Fuqiang Chu : Formal analysis, Validation. Haicun Yang : Writing-review & editing. Zheng cao : Project administration, Writing-review & editing. Acknowledgment No funding was received to assist with the preparation of this manuscript. 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J Alloys Compd 960: 170813. https://doi.org/10.1016/j.jallcom.2023.170813. Joshi RM (1962) The free radical polymerization of maleic anhydride. Die Makromolekulare Chemie 53: 33-45. https://doi.org/10.1002/macp.1962.020530105. Li Y, Xie X-M, Guo B-H (2001) Study on styrene-assisted melt free-radical grafting of maleic anhydride onto polypropylene. Polymer 42: 3419-3425. https://doi.org/10.1016/S0032-3861(00)00767-9. Ma P, Cai X, Lou X, Dong W, Chen M, Lemstra PJ (2014) Styrene-assisted melt free-radical grafting of maleic anhydride onto poly(β-hydroxybutyrate). Polym Degrad Stab 100: 93-100. https://doi.org/10.1016/j.polymdegradstab.2013.12.005. Zhang B, Jia L, Tian M, Ning N, Zhang L, Wang W (2021) Surface and interface modification of aramid fiber and its reinforcement for polymer composites: A review. Eur Polym J 147: 110352. https://doi.org/10.1016/j.eurpolymj.2021.110352. 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J Therm Anal Calorim 140: 2259-2265. https://doi.org/10.1007/s10973-019-09006-w. Tsuji Y (2024) Molecular Understanding of the Distinction between Adhesive Failure and Cohesive Failure in Adhesive Bonds with Epoxy Resin Adhesives. Langmuir 40: 7479-7491. https://doi.org/10.1021/acs.langmuir.3c04015. Shi C, Wang A, Zhu X, cheng F (2022) Research on cohesive failure behavior and parameter sensitivity of rubber – SET under cohesive zone model. Eng Fail Anal 140: 106492. https://doi.org/10.1016/j.engfailanal.2022.106492. Zheng X, Guo Y, Douglas JF, Xia W (2022) Competing Effects of Cohesive Energy and Cross-Link Density on the Segmental Dynamics and Mechanical Properties of Cross-Linked Polymers. Macromolecules 55: 9990-10004. https://doi.org/10.1021/acs.macromol.2c01719. Nagoshi T, Harada Y, Nakasumi S, Yamazaki N, Hasegawa K, Takagi K, Peng W, Fujii G, Ohkubo M (2022) Inherent cohesive failure of epoxy adhesive in carbon-fiber-reinforced plastic composites revealed by micro-tensile testing and finite element analysis. Compos Part B Eng 242: 110059. https://doi.org/10.1016/j.compositesb.2022.110059. Ali M, Shi H, Ahmed S, Song Y, Liu F, Han E-H, et al. (2024) A bi-functional self-healing epoxy composite coating based on coordinated functionalized attapulgite/graphene oxide. Appl Surf Sci 677: 161015. https://doi.org/10.1016/j.apsusc.2024.161015. Wang F, Wang L, Yan S, Chen D (2015) Interaction modal of polyurethane composites reinforced by the nano-attapulgite. Mater Res Innovations 19: 329-333. https://doi.org/10.1179/1432891715Z.0000000001696. Shi,JF, Li N, Zhang F, Zong Z, Li ZY, Wang YY, Yan DX (2024) Enhanced mechanical property, high-temperature oxidation and ablation resistance of carbon fiber/phenolic composites reinforced by attapulgite. 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Cite Share Download PDF Status: Published Journal Publication published 04 Jan, 2026 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 03 Sep, 2025 Reviewers invited by journal 03 Sep, 2025 Editor invited by journal 20 Aug, 2025 Editor assigned by journal 03 Aug, 2025 First submitted to journal 03 Aug, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7267966","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":509611859,"identity":"69fed287-3a2c-48b2-a1fe-fe2c2329ab5e","order_by":0,"name":"Minglei Hu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Minglei","middleName":"","lastName":"Hu","suffix":""},{"id":509611860,"identity":"0f94f409-38f8-4269-9b69-9cdc08b99dd0","order_by":1,"name":"Wei Zhang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Wei","middleName":"","lastName":"Zhang","suffix":""},{"id":509611861,"identity":"ad744ca4-23a3-485e-acfd-fe19e8e6d700","order_by":2,"name":"Bin Hu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Bin","middleName":"","lastName":"Hu","suffix":""},{"id":509611862,"identity":"ad9d8f6d-5713-4572-93dc-01bc7957409f","order_by":3,"name":"Fuqiang Chu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Fuqiang","middleName":"","lastName":"Chu","suffix":""},{"id":509611863,"identity":"dd716590-b923-46f4-ad1f-b0853438721a","order_by":4,"name":"Haicun Yang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAw0lEQVRIiWNgGAWjYDACCQY2BsYGBjkol5l4Lcaka0lsIFqLwe3mZw8+7rBJ728//kyCocI6sYH97AH8Wu4cMzeceSYtd8aZhDQJhjPpiQ08eQn4tdzIYZPmbTucu0GC4ZgEY9vhxAYJHgOitKQbANVLMP4jQUuCgQQzmwRjAxFaJG+kgf1iOONMGrNFwrF04zaeHPxa+G4kg0NMnr/9+MMbH2qsZfvZz+DXonAAmZcAxGx41QOBfAMhFaNgFIyCUTAKAK+0Q0pVyPtLAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-5222-9195","institution":"Changzhou University - Wujin Campus: Changzhou University","correspondingAuthor":true,"prefix":"","firstName":"Haicun","middleName":"","lastName":"Yang","suffix":""},{"id":509611864,"identity":"4f70c8be-cdcf-4f2f-a383-e1bfba53f0cf","order_by":5,"name":"Zheng Cao","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Zheng","middleName":"","lastName":"Cao","suffix":""}],"badges":[],"createdAt":"2025-08-01 06:25:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7267966/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7267966/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10965-025-04738-w","type":"published","date":"2026-01-04T15:58:05+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90939301,"identity":"4d6f04b1-6fcc-460b-98db-ece34c9d0b94","added_by":"auto","created_at":"2025-09-09 17:48:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":3963313,"visible":true,"origin":"","legend":"\u003cp\u003e(a) FTIR spectra, (b) XPS full-scan spectrum, (c) TGA curves, and (d) DTG curves of ATP, ATP-CPTMS, and ATP-CPO\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/c558d5fc1df946c485a850da.png"},{"id":90940260,"identity":"3b71bcd7-421a-4e9e-944a-df293355a714","added_by":"auto","created_at":"2025-09-09 17:56:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":3864456,"visible":true,"origin":"","legend":"\u003cp\u003e(a) FTIR spectra of PE, extracted PE, and extracted ATP, (b) FTIR spectra of SiO\u003csub\u003e2\u003c/sub\u003e and separated PE ash, (c) XPS full-scan and (d) Si2p core-level spectrum of separated PE ash\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/99849b36e4d5cb0aaff9b01a.png"},{"id":90939303,"identity":"503b019a-e445-4512-9291-8c0abaf8e77d","added_by":"auto","created_at":"2025-09-09 17:48:12","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2428753,"visible":true,"origin":"","legend":"\u003cp\u003eTEM and FESEM images of (a,b) ATP and (c,d) extracted ATP\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/595c7b9df5d3644bff00c932.png"},{"id":90940262,"identity":"b4313f3f-d06e-41c2-835c-fd4462913a4d","added_by":"auto","created_at":"2025-09-09 17:56:12","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":7568008,"visible":true,"origin":"","legend":"\u003cp\u003eEffects of ATP-CPO content on (a) tensile property, (b) 180° peeling strength, (c) shrear strength, and (d) MFR of different composites\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/f5d6cda752029bd95f380ca3.png"},{"id":90939312,"identity":"306937f7-c7b9-49d1-9651-de1c072ffde2","added_by":"auto","created_at":"2025-09-09 17:48:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":3072635,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM images of (a) PE and (b) PE/ATP-CPO 4% composites, SEM images of adhesive resin and (d) stainless steel plate (inset: EDS mapping of C element)\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/68fa0548a300bdd8faa999e7.png"},{"id":90939307,"identity":"857a9293-d1be-4d74-95dc-fd4ad1ca1328","added_by":"auto","created_at":"2025-09-09 17:48:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":4068859,"visible":true,"origin":"","legend":"\u003cp\u003e(a) TGA curves, (b) DTG curves, (c) cooling curve, and (d) seconed heating curves of different composites\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/b7292cc63230970d57c6949c.png"},{"id":90940264,"identity":"12c5b5ea-0d75-4e33-b926-3bd40e9afb5e","added_by":"auto","created_at":"2025-09-09 17:56:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":4003723,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Strain scanning curve, (b) complex viscosity, (c) storage modulus, and (d) loss modulus vs angular frequency of different composites\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/63e7609d1b48bf7830c110f0.png"},{"id":99545847,"identity":"b99c7708-b48c-4192-a6cc-eb9a15189856","added_by":"auto","created_at":"2026-01-05 16:09:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":29705420,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7267966/v1/d2180a42-fa27-4e74-95df-8c122a8a2ce2.pdf"}],"financialInterests":"","formattedTitle":"Synergistic functionalized polyethylene/attapulgite composites with maleic anhydride and silicone by reactive extrusion for enhanced metal-plastic interfacial adhesion","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eWith the rapid development of social industry, various types of pipelines are widely used in energy and chemical fields such as liquid supply and gas transmission [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Steel wire-wound polyethylene composite pipes combine the advantages of high-strength steel wire reinforcement and polyethylene material. The inner layer is made of high-density polyethylene (HDPE), which offers excellent corrosion resistance and a smooth inner wall. The reinforcing layer is a net structure formed by winding high-strength steel wires, providing the mechanical strength of the pipe. The outer layer is also made of HDPE, which serves a protective and sealing role [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The bonding resin in steel wire-wound polyethylene composite pipes is a key material that ensures the close bonding between the steel wire and polyethylene. Polarized-modified polyethylene is a widely used bonding resin, providing bonding ability with the wire mesh while ensuring compatibility with the inner and outer HDPE layers [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eLike most manufactured blended or composite polymer products, interfaces always exist in such pipes and dominate their service performance and life [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Because of their chemical inertness, low density, and low cost, olefin-based polymers are widely used in various fields, such as adhesives, adhesive layers, films, fibers, automobiles, buildings, and appliances [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, the adhesive strength between olefin-based polymers and some polar substrates, such as polyester, polyamide, metal, and glass, is generally low [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. To increase the polarity of olefin polymers, maleic anhydride (MAH)-functionalized polymers have been used as compatibilizers to improve the compatibility of polymer blends or composites, that is, to enhance the interfacial bonding strength [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. However, the double bond in the maleic anhydride molecule is connected to a cyclic anhydride group, which creates significant steric hindrance during the polymerization process. This structure makes it difficult for maleic anhydride monomers to form stable free radical intermediates during polymerization, thus limiting their homopolymerization reaction [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Usually, a proper amount of styrene is added during the grafting process for copolymerization to increase the grafting rate. However, when used as an adhesive resin, the introduction of the nonpolar polystyrene (PS) segment can inevitably affect its adhesion to polar substrates [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eFor polyolefin composites, compared with functional modification of polyolefin, organic surface modification of inorganic particles by coupling agents is commonly an effective means to enhance the interfacial adhesion of composites [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. For nonpolar polyolefin matrices, long-chain alkane silane coupling agents are often the first choice for inorganic particle modification [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Additionally, some reactive silane coupling agents, such as vinyl and methacryloyloxy siloxanes, can be used for surface modification with siloxane as the reaction point. These functionalized inorganic particles can then undergo grafting reactions on the polyolefin matrix in the presence of an initiator to enhance interfacial adhesion through covalent bonds [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In essence, these coupling agents have two types of active groups. Alkoxy groups can connect to the inorganic matrix through hydrolysis and condensation reactions, and can even form SiO₂ networks through sol-gel reactions [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Vinyl groups can enter the carbon chain through free radical polymerization, ultimately forming organic-inorganic hybrid materials based on covalent bonding [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. When bonding non-powder inorganic substrates, such as metal or glass plates, and melt blending is not feasible, the sequence of the above reactions can be adjusted. For example, polyolefin grafted with vinyl silane can first be prepared by melt reaction extrusion, and then bonded to planar inorganic matrices through condensation reactions. Polyolefin elastomer (POE) grafted with silane has been widely used in photovoltaic field [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, this method requires strict control of the reactive extrusion process to prevent surface cross-linking and loss of adhesion.\u003c/p\u003e\u003cp\u003eCohesive failure refers to the separation of the adhesive within the cured layer of the adhesive, meaning the adhesive itself is torn apart. This failure mode indicates that the adhesive's cohesive strength is lower than its bonding strength with the adherend. When peeling failure occurs within the adhesive itself, it suggests that the bonding strength between the adhesive and the adhered material is greater than that of the adhesive itself [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. This type of failure has been observed in thermosetting adhesives and may result from the disruption of intermolecular interactions between adhesive molecules. However, in thermoplastic adhesive resins, cohesive failure is primarily due to the decreased structural stability caused by too low a matrix molecular weight and insufficient chain entanglement density. These adhesive resins are more prone to failure in practical applications, especially under high shear stress, which further affects the stability of the adhesive system. For most adhesive resins, cohesive strength can be enhanced through proper crosslinking and the addition of reinforcing fillers [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. While crosslinking improves adhesive strength, adding reinforcing fillers is often the preferred method. Attapulgite, a natural clay mineral with a unique fibrous crystal structure, significantly boosts the cohesive strength of adhesive resins due to its high specific surface area and excellent dispersibility. Its fibrous structure forms physical cross-linking points within the resin matrix, thereby enhancing cohesive strength [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Additionally, attapulgite improves the thermal stability of adhesive resins, allowing the cohesive strength of nano-composite adhesive resins to be better maintained at high temperatures [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. It also increases the crystallinity of adhesive resins, which enhances cohesive strength by increasing molecular interactions [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Furthermore, attapulgite acts as an anti-aging agent, protecting adhesive resins from light, heat, and oxidation, thus extending their service life [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. However, to our knowledge, there are no research reports on polyolefin adhesive resins modified by inorganic nanoparticles.\u003c/p\u003e\u003cp\u003eHerein, the objective was to prepare PE/ATP composites with enhanced adhesive and cohesive strength. Initially, ATP was chemically modified to introduce a cumene peroxide group as an initiator. Subsequently, PE/ATP composites were obtained through reactive extrusion, synergistically functionalized with maleic anhydride and silicone. The chemical modification mitigated ATP agglomeration, while reactive extrusion further optimized ATP dispersion and enhanced both adhesion and cohesive strength. The influence of functional ATP content on the structure and properties of the composites was investigated in detail.\u003c/p\u003e"},{"header":"2. Experimental section","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Materials\u003c/h2\u003e\u003cp\u003ePolyethylene (DMDA-8008H) was purchased from PetroChina Dushanzi Petrochemical Co. Ltd. (Xinjiang, China). Vinyltrimethoxysilane (VTMS, \u0026ge;\u0026thinsp;98%), 3-chloropropyltrimethoxysilane (CPTMS, 98%), 4-dimethylaminopyridine (DMAP, \u0026ge;\u0026thinsp;98%), and maleic anhydride (MAH, \u0026ge;\u0026thinsp;99%) were bought from Aladdin-reagent Co. Ltd. (Shanghai, China). Dry toluene (AR), ethanol (AR), cumyl hydroperoxide (CHPO, 80 wt% in toluene) were all obtained from Sinopharm Chemical Reagent (Shanghai, China). All reagents were used directly without purification.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Synthesis of ATP-suppported cumyl peroxide (ATP-CPO)\u003c/h2\u003e\u003cp\u003eTypically, 5 g of ATP, 10 mL of CPTMS, and 150 mL of anhydrous toluene are mixed uniformly under ultrasonication in a 250 mL round-bottomed flask. and the resulting mixture was heated to reflux for 10 h. After reaction, the solid product was separated by suction filtration, washed several times with anhydrous ethanol, and finally dried under vacuum at 50 ℃ for 24 h to obtain ATP-CPTMS. Subsequently, 5 g of the dried ATP-CPTMS was ultrasonically dispersed in 150 mL of anhydrous toluene, and 10 g of CHPO solution (0.052 mol) and 1.22 g of DMAP (0.01 mol) were added. After bubbling with N\u003csub\u003e2\u003c/sub\u003e for 30 min, the flask is sealed and the mixture was stirred at 40 ℃ for 24 h. After suction filtration, the solid product is repeatedly washed with anhydrous ethanol, and finally dried in a vacuum oven at room temperature for 24 h to prepare ATP-CPO.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Preparation of HDPE-g-(MAH-co-VTMS) via surface-initiated graft polymerization\u003c/h2\u003e\u003cp\u003eAccording to the formula in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, MAH, VTMS, and antioxidant were first dissolved in acetone, and then ultrasonicated after ATP-CPO was added to obtain a uniform dispersion. Next, the dispersion and HDPE was mixed in a high-speed mixer evenly at room temperature and then reactively blended by a twin-screw extruder to prepare the hybrid PE-\u003cem\u003eg\u003c/em\u003e-(MAH-\u003cem\u003eco\u003c/em\u003e-VTMS). The temperatures of screw were set at 135, 155, 180, 195, 195, 195, 190, 190, and 180 ℃, respectively, and the screw rotation speed was 180 r/min. The prepared HDPE-\u003cem\u003eg\u003c/em\u003e-(MAH-\u003cem\u003eco\u003c/em\u003e-VTMS) was finally injection molded into standard species for different mechanical testing at 200 ℃, and also molding compressed into rheological samples using a flat vulcanizer.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFormula of PE/ATP composites\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePE/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eATP-CPO/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eMAH/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eVTMS/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAntioxidant/%\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e100\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026mdash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e96.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e95.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e93.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e89.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4. Characterization\u003c/h2\u003e\u003cp\u003eThe chemical composition of modified ATP and hybrid HDPE were characterized by Nicolet IS10 Fourier transform infrared spectra (FTIR, Nicolet Instruments, Inc., USA) in the frequency range of 500\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in transmission and ATR mode, respectively. The element composition change of ATP and HDPE was determined on an HI5000 VersaProbe IV X ray photoelectron spectroscopy (XPS, ULVAC-PHI, Inc., Japan) with a nonmonochromatic X-ray source (Al Kα radiation as the exciting source). The micromorphology of the hybrid materials were observed on a SUPPRA-55 field emission scanning electron microscope (FESEM, Carl Zeiss, Inc., Germany) and JSM-6360LA Scanning Electron microscopy (SEM, JEOL Inc., Japan). The samples were fractured in liquid nitrogen and then observed after the section was sprayed with gold. The thermal degradation behavior was evaluated by a TG209 F3 thermogravimetric analysis system (NETZSCH Premier Technologies LLC., Germany) at a heating rate of 10\u0026deg;C/min in the range of 30\u0026ndash;800\u0026deg;C under a nitrogen atmosphere. The melting and crystallization behavior were measured on a DSC800 differential scanning calorimeter (DSC, Perkin Elmer, Inc., USA) in the temperature range of 50\u0026ndash;180\u0026deg;C at a heating rate of 10\u0026deg;C/min. The tensile properties and peel strength of the samples were tested on a WDT-10 universal material tester (Shenzhen Kaiqiangli Testing Instrument Co. Ltd., China) at room temperature. Tensile yield strength were tested under a tensile speed of 50 mm/min according to Chinese national standards GB/T 1040\u0026ndash;2006. Peel strength was tested according to Chinese national standards GB/T 2792\u0026thinsp;\u0026minus;\u0026thinsp;2014. The composite material was first molded into a 300\u0026times;300 mm square piece, and then bonded to an stainless steel plate of the same size at 200 ℃. Finally, the bonded piece was cut into a 300 \u0026times; 15 mm rectangular spline and tested at a separation rate of 50 mm/min. Shear strength was test according to Chinese national standards GB/T 7124\u0026thinsp;\u0026minus;\u0026thinsp;2008. Two stainless steel plates were bonded with composite resin using hot pressing. The thickness of the resin layer was 200 \u0026micro;m, the bonding length was 50 mm, and the tensile rate was 1 mm/min. The melt flow rates (MFR) were tested on an MTM1000 melt flow index machine (Shenzhen SUNS Technology Stock Co., Ltd., China) at 190\u0026deg;C and 2.16 kg according to Chinese national standards GB/T 3682\u0026thinsp;\u0026minus;\u0026thinsp;2018. The vicat softening temperature (VST) was tested on a VTM1300 microcomputer controlled Vicat softening temperature testing machine (Suns Co., Ltd, Shenzhen, China) according to China standard GB/T1633-2000, and samples with size of 10 mm \u0026times; 10 mm \u0026times; 4 mm were tested under 10 N at a heating rate of 120\u0026deg;C/h. The rheological behavior was characterized on a Discovery HR-30 rotational rheometer (TA Instruments, Inc., USA) at 170\u0026deg;C using a parallel plate model with a gap of 1 mm.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Preparation of synergistic functionalized PE/ATP composites\u003c/h2\u003e\u003cp\u003eThe changes in functional groups during ATP modification were characterized by FTIR, with the results shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea. In the FTIR spectrum of crude ATP, the peak at 3558 cm⁻\u0026sup1; corresponds to the stretching vibration of surface hydroxyl groups. The peak at 1658 cm⁻\u0026sup1; is attributed to water in the crystal structure, while the peaks at 1033 and 983 cm⁻\u0026sup1; are associated with the stretching vibrations of the Si-O-Si tetrahedron. After modification with CPTMS, new peaks emerged in the ATP-CPTMS spectrum: the C-H stretching and bending vibrations appeared at approximately 2933 and 1473 cm⁻\u0026sup1;, respectively, and the C-Cl stretching vibration was observed at 793 cm⁻\u0026sup1;. These new characteristic peaks, originating from the chloropropyl groups, confirm the successful grafting of CPTMS onto the ATP surface. Upon further reaction with CHPO, the C-Cl peak at 793 cm⁻\u0026sup1; disappeared. Concurrently, new peaks appeared: the C-H stretching vibration on the benzene ring at 3066 cm⁻\u0026sup1;, the benzene ring skeleton vibrations at 1618 and 1525 cm⁻\u0026sup1;, and the C-O stretching vibration at 1214 cm⁻\u0026sup1;. These results collectively demonstrate the successful synthesis of ATP-CPO.\u003c/p\u003e\u003cp\u003eThe elemental composition of modified ATP was determined by XPS full-scan spectrum, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb. The dominant signal peaks for ATP are observed at 130.1 eV (Si2p), 154.2 eV (Si2s), 285.0 eV (C1s), and 532.1 eV (O1s). The C1s peak is attributed to a small amount of organic contamination, while the other elements align with the chemical composition of ATP. After modification with CPTMS, the signal intensities of the C element and Si in ATP-CPTMS are enhanced, and a new signal peak for Cl2p appears at 200.1 eV, confirming the introduction of CPTMS. Following the grafting of CPO, the Cl2p signal peak in ATP-CPO nearly disappears, and the intensity ratio of the C1s to O1s signal peaks increases significantly. This corresponds to the grafting of the high-carbon-content CPO group through the removal of HCl.\u003c/p\u003e\u003cp\u003eThe TGA and DTG curves of ATP, ATP-CPTMS, and ATP-CPO are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec and \u003cb\u003ed\u003c/b\u003e. The thermal decomposition process of pure ATP comprises four stages. The weight loss before 100\u0026deg;C is attributed to surface-adsorbed water, which reduces its compatibility with nonpolar polymers. The subsequent weight loss with increasing temperature corresponds to the loss of bound water within the rod crystal structure, culminating in a final weight loss rate of 9%. After modification with CPTMS, the TGA curve of ATP-CPTMS shows a more pronounced weight loss before 100\u0026deg;C. The introduction of organic components significantly reduces the water absorption of the ATP surface. Concurrently, the intensity of the third weight loss peak at 350\u0026deg;C in the DTG curve is notably enhanced, corresponding to the decomposition of the surface-grafted CPTMS. This results in a final weight loss rate of 15.7%. Upon further grafting with CPO, the weight loss peak intensity at 185\u0026deg;C in the DTG curve of ATP-CPO increases significantly, corresponding to the decomposition of peroxy groups. With the addition of more organic components, the weight loss peak intensity at 400\u0026deg;C further increases, leading to a final weight loss rate of 24.7%. These changes in thermal decomposition behavior fully confirm the successful grafting of CPTMS and CPO.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe PE and ATP components in the composite were dissolved and separated using xylene, and characterized by FTIR and XPS, respectively. The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. In the FTIR spectrum of pure PE (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea), the peaks at 2915 and 2828 cm⁻\u0026sup1; correspond to the antisymmetric and symmetric stretching vibrations of C-H, respectively. The peaks at 1436 and 720 cm⁻\u0026sup1; are attributed to the bending and rocking vibrations of C-H, respectively. For PE extracted from the composites, the C\u0026thinsp;=\u0026thinsp;O stretching vibration peak corresponding to MAH appears at 1744 cm⁻\u0026sup1;, and the Si-O-Si stretching vibration peak appears at 963 cm⁻\u0026sup1;, which may correspond to the hydrolysis and condensation of some alkoxy groups reflected by a relatively weak hydroxyl characteristic peak at 3450 cm⁻\u0026sup1;. The Si-O-C stretching vibration peak is observed at 1090 cm⁻\u0026sup1;, and the C-H bending vibration peak in the range of 1300\u0026ndash;1400 cm⁻\u0026sup1; is more pronounced. These results fully confirm that the PE macromolecular chain was simultaneously grafted with MAH and VTMS copolymers. Accordingly, in the infrared spectrum of extracted ATP, in addition to the characteristic peaks of ATP itself, there are C-H stretching vibration peaks at 2917 and 2878 cm⁻\u0026sup1;, a C\u0026thinsp;=\u0026thinsp;O vibration peak at 1735 cm⁻\u0026sup1;, and a Si-O-C stretching vibration peak at 1118 cm⁻\u0026sup1;. The peaks in the range of 1300\u0026ndash;1400 cm⁻\u0026sup1; are significantly enhanced and belong to the grafted PE segments. These results indicate that the composites consist of PE-g-(MAH-co-VTMS), ATP-g-(MAH-co-VTMS), and more complex ATP-g-PE with cooperative functionalization of MAH/VTMS. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb shows the FTIR spectrum of ash and pure SiO₂ extracted from PE after calcination. The peak at 3550 cm⁻\u0026sup1; corresponds to the stretching vibration of surface hydroxyl groups, the peak at 1650 cm⁻\u0026sup1; corresponds to adsorbed water, and the peak at 812 cm⁻\u0026sup1; corresponds to the symmetric stretching vibration of Si-O. The positions of all characteristic peaks are almost identical to those of pure SiO₂, indicating that the calcined ash is primarily composed of SiO₂. The chemical composition of the ash was further analyzed by XPS. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ec and \u003cb\u003ed\u003c/b\u003e, the signals of O and Si elements are predominantly observed in the XPS full-scan spectrum, with a small amount of C element possibly representing organic impurities remaining from the calcination process. The Si2p peak in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ed can be fitted into four peaks: O-Si-C at 101.9 eV, Si2p₁/₂ at 103.4 eV, Si2p₃/₂ at 104.1 eV, and Si-O at 105.1 eV. These analytical results further confirm the graft copolymerization of VTMS and MAH.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates the micromorphology of crude and extracted ATP. The TEM and FESEM images of crude ATP shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea and \u003cb\u003eb\u003c/b\u003e reveal that the structural unit of pure ATP is a fibrous rod crystal with a high aspect ratio. These rod crystals with a relatively smooth surface and a diameter of 15\u0026ndash;20 nm are aggregated into larger bundles through hydrogen bonds between hydroxyl groups on their surfaces. However, as depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec and \u003cb\u003ed\u003c/b\u003e, the morphology of ATP extracted from the composites has changed significantly. The size of the rod crystals has increased noticeably, and the distinct core-shell structure provides clear evidence that graft polymerization has occurred between ATP and some PE substrates, as well as MAH and VTMS.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Mechanical properties and micromorphology\u003c/h2\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea illustrates the effect of ATP-CPO content on the tensile strength of composites. Pure PE has a tensile strength of 26.8 MPa and an elongation at break of 672.5%. With the addition of ATP-CPO, the tensile strength of the composites increases gradually. When the ATP-CPO content reaches 4%, the tensile strength peaks at 37.2 MPa, while the elongation at break decreases to 477.9%. ATP, with its high aspect ratio, significantly reinforces polymer composites. The modification with CPO groups effectively reduces the aggregation tendency of ATP. Additionally, the immobilized CPO groups can trigger the graft copolymerization of MAH, VTMS, and PE during melt extrusion. This process significantly enhances the compatibility of the system and the interfacial affinity between the PE matrix and ATP. The uniformly dispersed ATP acts as a stress concentration point. When the interface is strengthened, stress can be effectively transferred through the matrix, and a large amount of energy is dissipated through interface failure, thereby enhancing the overall strength of the system. However, the enhancement of interfacial strength and the formation of an organic-inorganic hybrid network structure restrict the relative sliding of PE macromolecular chains, leading to a decrease in elongation at break. As the ATP-CPO content increases further, the tensile strength decreases. This decline may be attributed to the agglomeration of ATP-CPO within the system, which weakens the reinforcing effect. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb shows the peeling strength of various composite materials. Pure PE exhibits a peeling strength of only 5.2 N/cm. This low value is attributed to PE's nonpolar nature, which results in weak bonding between PE and metal. Only a small amount of PE can embed itself into the surface defects of the steel plate to achieve bonding. In contrast, the composites show a significant enhancement in peeling strength. The main components in the composites prepared by surface-initiated graft copolymerization are polar molecules, which increase their affinity with metals. Additionally, the anhydride and alkoxy groups of MAH and VTMS in the composites can react with the hydroxyl groups on the metal surface, forming covalent bonds between the composite materials and the metal, thereby further enhancing the bonding strength. With the increase of ATP-CPO content, the amount of graft copolymer in the system increases, and the peeling strength correspondingly rises. When the ATP-CPO content reaches 4%, the peeling strength is attained to 136.6 N/cm, which is 26.3 times higher than that of pure PE. Similarly, at higher ATP-CPO contents, agglomeration may bury some CPO groups, which cannot effectively initiate graft copolymerization after decomposition, leading to a decrease in peel strength. In addition, it also includes the reasons for the decrease of wettability due to the significant increase of cohesive strength.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eIn Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ec, the variation tendency of shear strength is similar to the previously mentioned peeling strength. The introduction of a large number of polar groups and the formation of covalent bonds between these groups and the metal surface result in a maximum shear strength of 15.2 MPa when the ATP-CPO content is 4%, indicating strong adhesion. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ed displays the melt index of different composite materials. As expected, the melt index of the composites decreases gradually with increasing ATP-CPO content. This decrease is attributed to the enhanced interfacial interactions, intermolecular forces, and the formation of an organic-inorganic hybrid network structure, which restrict the thermal movement of the macromolecular chains and reduce the system's fluidity. Although the melt index drops to 3.6 g/min at an ATP-CPO content of 4%, it still meets the fluidity requirements for adhesive resins.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the cross-sectional morphology of pure PE and the composite containing 4% ATP-CPO. In Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the cross-section of pure PE appears relatively smooth, with a few protrusions resulting from plastic deformation during brittle fracture. In contrast, the cross-section of the composite retains some characteristics of plastic deformation. In Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb, most of the ATP is dispersed in the PE matrix at the nanoscale, although there are a few aggregates with sizes ranging from 200 to 400 nm. The functionalization with CPTMS and CPO mitigates the agglomeration of ATP and enhances the interfacial affinity between ATP and the matrix through surface-initiated graft copolymerization, thereby achieving true nano-composition. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec presents a SEM image of the bonding surface after the shear strength test. The resin on the bonding surface exhibits significant plastic deformation along the direction of shear stress. This deformation is attributed to the tearing of the resin at the interface during the shear failure process, which confirms the strong bonding between the composite material and the stainless steel plate. The SEM image of the stainless steel plate interface after shear failure in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ed shows obvious resin residue traces on the surface. Meanwhile, the C elemental mapping image of the bonding surface of the stainless steel indicates that the residual layer is composed of a large number of carbon elements. This further confirms that the residual material is adhesive resin, and there is strong adhesion between them.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Thermal properties\u003c/h2\u003e\u003cp\u003eThe thermal properties of the composites were evaluated using TGA and DSC, with the results shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e and the related parameters summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The TGA curves of different composites are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea. Pure PE has an initial decomposition temperature of approximately 430\u0026deg;C (T\u003csub\u003ewt5%\u003c/sub\u003e), with a final mass residual rate of 0.9%. Upon adding ATP-CPO, the initial decomposition temperature of the composites increased to 431.9, 433.6, 444.3, and 488.2 ℃, respectively, and the final mass residual rate (\u003cem\u003eMrr\u003c/em\u003e) rose to 3.5%, 3.7%, 5.4%, and 12.4%, respectively. ATP-CPO forms an organic-inorganic hybrid network structure within the system through surface-initiated graft copolymerization. This denser microstructure restricts the thermal movement of molecular chains during heating, delaying the thermal decomposition reaction of the matrix and thus gradually increasing the initial decomposition temperature. The increase in mass residual rate is attributed to the presence of the ATP component, while the silicone component enhances the thermal stability of the char during thermal decomposition, hindering further decomposition.\u003c/p\u003e\u003cp\u003eIn the DTG curve shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb, pure PE exhibits a peak decomposition rate (\u003cem\u003eDr\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e) of 3.13%/\u0026deg;C at 478.2\u0026deg;C. In contrast, the peak decomposition rate temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003edmax\u003c/sub\u003e)of the composites rises to 496.9, 506.5, 506.9, and 507.1\u0026deg;C, respectively, with decomposition rates all lower than that of pure PE. This is because the dense network structure prevents the overflow of degraded small molecular products, thereby delaying the mass loss process. However, as the ATP-CPO content increases, the highest decomposition rate also rises gradually. This is due to the low specific heat capacity of ATP. The introduction of more ATP-CPO may increase the overall temperature gradient, causing the adjacent matrix to decompose at a higher stability first and then leading to internal porosity, which ultimately accelerates the decomposition process of the entire matrix. Overall, the thermal stability of the composites was enhanced after ATP-CPO initiated graft copolymerization.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ec presents the crystallization curves of various composite materials, all of which exhibit a single crystallization peak. Pure PE has a crystallization temperature of 118.2\u0026deg;C. As the ATP-CPO content increases, the crystallization temperatures (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e) of the composites rise to 119.5, 120.3, 120.8, and 121.6\u0026deg;C, respectively. These temperatures are higher than that of pure PE. The even dispersion of ATP within the matrix increases the number of nucleation sites during the crystallization process. On one hand, it promotes the orderly arrangement of PE macromolecular chains around ATP through heterogeneous nucleation, thereby reducing the crystallization energy barrier. On the other hand, the organic-inorganic hybrid network structure formed by graft copolymerization restricts the movement of PE macromolecular chains, enabling them to crystallize at higher temperatures. However, this structure also limits crystal growth, which affects the crystallinity of the system.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ed displays the melting curves of different composites. As the ATP-CPO content increases, the melting peak temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e) of the composites initially decreases and then increases. When the ATP-CPO content is 1%, the melting peak temperature of the composites is slightly lower than that of pure PE. This may be due to the organic-inorganic hybrid network structure, which decreases the molecular chain migration speed and improves the perfection of the crystal region, resulting in a slight decrease in melting temperature. However, as the ATP-CPO content increases, the high-strength network structure increasingly restricts the thermal movement of the PE macromolecular chains. The stability of the crystal region formed by heterogeneous nucleation is enhanced due to the presence of embedded ATP, leading to a gradual increase in melting temperature. From the trend of crystallinity (\u003cem\u003eχ\u003c/em\u003e) changes, it can be seen that the crystallinity of the composites slightly increases at low ATP-CPO content because the system is still dominated by homogeneous nucleation, with heterogeneous nucleation providing additional nucleation sites. In contrast, at high ATP-CPO content, heterogeneous nucleation plays a dominant role, but the alignment of macromolecular chains to crystalline regions is impeded, resulting in a decrease in crystallinity. Finally, the formation of physical and chemical cross-linking structures, the limitation of molecular chain movement, and the improvement of thermal stability all contribute to the gradual increase in the VST value with increasing ATP-CPO content.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThermal properties of PE and different composites\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"9\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e /℃\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e /℃\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u003cem\u003eχ\u003c/em\u003e /%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003e5wt%\u003c/sub\u003e /℃\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003csub\u003edmax\u003c/sub\u003e /℃\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u003cem\u003eDr\u003c/em\u003e\u003csub\u003emax\u003c/sub\u003e/(%/℃)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u003cem\u003eMrr\u003c/em\u003e/%\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u003cem\u003eVST\u003c/em\u003e/℃\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePE\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e131.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e118.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e74.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e430\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e478.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3.13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e128.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 1%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e130.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e119.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e76.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e431.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e496.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e129.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 2%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e131.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e120.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e74.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e433.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e506.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e3.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e131.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 4%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e132.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e120.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e73.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e444.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e506.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e5.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e133.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eATP-CPO 8%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e133.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e121.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e72.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e448.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e507.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.62\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e12.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e134.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.4 Rheological behavior\u003c/h2\u003e\u003cp\u003eThe change in the microstructure of composites can be reflected by changes in their rheological behavior, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. In the strain scanning curve (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea), the storage modulus (G\u0026rsquo;) of all composites remains relatively constant in the linear viscoelastic region. Under shear stress, the macromolecular conformation changes as molecular segments move to reach a stable state, resulting primarily in a reversible elastic response. Simultaneously, as the ATP-CPO content increases, the storage modulus in the linear viscoelastic region of the composites initially increases and then decreases under different strains, exhibiting the Payne effect. Compared with pure PE, the thermal decomposition of peroxy groups in ATP-CPO leads to the graft copolymerization of MAH and VTMS onto PE, forming an organic-inorganic hybrid network structure within the system. Grafting MAH increases the intermolecular forces between PE macromolecules. Additionally, the hydrolysis and condensation of a small amount of VTMS further enhance the mutual interactions between these macromolecules. The physical entanglement formed by ATP also restricts the movement of segments, leading to more elastic energy being stored under the same strain. As a result, the storage modulus of the system increases. When the ATP-CPO content is 4% and 8%, two plateaus appear in the strain scanning curve of the composites. This may be due to the formation of agglomerated bodies with high ATP-CPO content, leading to more metastable network structures in the system, which can be destroyed under small strain. However, the values of G\u0026rsquo; for the two plateaus are not significantly different, indicating that these metastable networks have little effect on the overall structural strength of the composite. As the strain increases, irreversible relative slip between molecular chains begins to occur along the direction of strain increase, causing G\u0026rsquo; to gradually decrease. With increasing ATP-CPO content, the linear viscoelastic region expands, which is different from most particle-filled systems. Under the action of peroxide groups, ATP and PE matrix molecular chains are more firmly bonded by covalent bonds, enhancing the strain stability of the melt structure of the composites.\u003c/p\u003e\u003cp\u003eThe linear viscoelastic behavior of the composites was further investigated through frequency scanning. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eb illustrates the changes in complex viscosity of the composites with shear frequency. In the low-frequency region, pure PE exhibits minimal dependence of complex viscosity on frequency, as the rate of entanglement breaking of macromolecular chains is similar to the rate of reconstruction. As the shear rate increases, it gradually exhibits shear-thinning behavior. With increasing ATP-CPO content, the dependence of complex viscosity on shear frequency in the low-frequency region becomes more pronounced, and the complex viscosity gradually increases. This increase is attributed to the growing blocking effect of the crosslinking and chain entanglement network on the movement of macromolecular chains. However, a large number of physical entanglement points are prone to disintegration under shear, leading to a significant decrease in complex viscosity. Additionally, rigid ATP particles tend to orient under shear, further disentangling the chains and making shear-thinning more pronounced. In the high-frequency region, the complex viscosity of all composites shows little difference. This is because, at high frequencies, PE macromolecular chains are primarily disentangled.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec illustrates the variation of the storage modulus (\u003cem\u003eG\u003c/em\u003e\u0026rsquo;) of the composites with shear frequency. As the shear frequency increases, the \u003cem\u003eG\u003c/em\u003e\u0026rsquo; of all samples gradually rises, and the differences among them diminish. This trend is attributed to the long relaxation times of the macromolecular chains. At high frequencies, the molecular chains do not have sufficient time to rearrange in response to external forces, thus exhibiting greater rigidity. In the low-frequency region, the \u003cem\u003eG\u003c/em\u003e\u0026rsquo; gap among the composites is more pronounced. With increasing shear rate, the \u003cem\u003eG\u003c/em\u003e\u0026rsquo; of the composites increases, and its dependence on shear frequency decreases. The appearance of a plateau trend (non-terminal effect) indicates enhanced solidity of the composites. This enhancement is due to the formation of a network structure via surface-initiated graft copolymerization, which effectively stores elastic energy at low frequencies, thereby significantly boosting the storage modulus. Moreover, the increased entanglement density reduces the free volume of the PE macromolecular chains, significantly inhibits their long-range movement, extends the relaxation time further, and consequently raises the storage modulus in the low-frequency region. This increase is beneficial for maintaining structural stability under low-frequency stress.\u003c/p\u003e\u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ed illustrates the variation of the loss modulus (\u003cem\u003eG\u003c/em\u003e\u0026rsquo;\u0026rsquo;) of the composites with shear frequency, exhibiting a trend similar to that of \u003cem\u003eG\u003c/em\u003e\u0026rsquo;. However, in the low-frequency region, the \u003cem\u003eG\u003c/em\u003e\u0026rsquo;\u0026rsquo; of the composites increases with the addition of ATP-CPO. This increase is attributed to the heightened internal friction of molecular chain movement in the presence of ATP-CPO, which extends the relaxation time and consequently enhances the hysteresis of molecular chain movement, leading to an elevated \u003cem\u003eG\u003c/em\u003e\u0026rsquo;\u0026rsquo;. Despite this increase, the rise in \u003cem\u003eG\u003c/em\u003e\u0026rsquo;\u0026rsquo; is notably less pronounced than that of \u003cem\u003eG\u003c/em\u003e\u0026rsquo;, further indicating that the incorporation of ATP-CPO more significantly enhances melt elasticity and solidity.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eIn summary, this work described the preparation of PE/ATP composites synergistically functionalized with MAH and VTMS by surface-initiated graft copolymerization using ATP-CPO as the initiator. the effects of ATP-CPO content on the mechanical properties, thermal properties, and rheological behavior of the composites were systematically investigated. The functionalization of CPO groups on the surface alleviated the aggregation tendency of ATP, and surface-initiated graft copolymerization significantly enhanced the interfacial strength of the composites, achieving nano-scale dispersion of ATP, resulting in a signicant enhancement on both cohesive strength and adhesive strength. When the ATP-CPO content was 4%, the tensile strength, peeling strength, and shear strength of the composites were 1.4, 26.3, and 21.7 times higher than those of nonpolar pure PE, respectively, accompanied by enhanced thermal stability and a slight decrease in crystallinity. The complex viscosity of the composite melt in the low-frequency region was significantly increased with a more pronounced shear-thinning behavior. The storage modulus shows a more substantial increase than the loss modulus, and a non-terminal effect is observed, indicating improved structural stability of the system under low-frequency shear stress. We believe that the composites prepared in this work are expected to be used as high-performance adhesive resin for steel wire wound reinforced polyethylene composite pipes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eDeclaration of Competing Interest\u003c/h2\u003e\u003cp\u003eAll authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eAuthor contribution\u003c/h2\u003e\u003cp\u003e\u003cb\u003eMinglei Hu\u003c/b\u003e: Conceptualization, Formal analysis, Methodology, Investigation, Data curation, Writing-original draft. Investigation, Formal analysis, Validation. \u003cb\u003eWei Zhang\u003c/b\u003e: Resources, Funding acquisition; \u003cb\u003eBin Hu\u003c/b\u003e: Resources, Funding acquisition; \u003cb\u003eFuqiang Chu\u003c/b\u003e: Formal analysis, Validation. \u003cb\u003eHaicun Yang\u003c/b\u003e: Writing-review \u0026amp; editing. \u003cb\u003eZheng cao\u003c/b\u003e: Project administration, Writing-review \u0026amp; editing.\u003c/p\u003e\u003ch2\u003eAcknowledgment\u003c/h2\u003e\u003cp\u003eNo funding was received to assist with the preparation of this manuscript.\u003c/p\u003e\u003ch2\u003eData availability\u003c/h2\u003e\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eGowid S, Mahdi E, Youssef SS, Moustafa E, Mosleh A, Shokry A (2021) Experimental investigation of the dynamic characteristics of wrapped and wound fiber and metal/fiber reinforced composite pipes. 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International Journal of Pavement Engineering 25: 2301456. https://doi.org/10.1080/10298436.2023.2301456.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Polyethylene, Attapulgite, Graft copolymerization, Composites","lastPublishedDoi":"10.21203/rs.3.rs-7267966/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7267966/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo enhance both the adhesive strength and cohesion of the adhesive resin, attapulgite functionalized with peroxy groups (ATP-CPO) was prepared through surface chemical modification. Subsequently, a series of polyethylene/ATP composites (PE/ATP) functionalized with maleic anhydride and vinyl trimethoxysilane were prepared via surface-initiated graft copolymerization. The effects of ATP-CPO dosage on the mechanical, thermal, rheological, and morphological characteristics of the composites were evaluated in detail. It was found that the surface functionalization and reactive extrusion process contributed to the nano-scale dispersion of ATP in the PE matrix, forming well-compatibilized nanocomposites consisting of PE-g-(MAH-co-VTMS), ATP-g-(MAH-co-VTMS), and more complex MAH/VTMS synergistically functionalized ATP-g-PE. When the ATP-CPO content was 4%, the composite exhibited significantly enhanced tensile strength, peel strength, and shear strength, which were 1.4, 26.3, and 21.7 times higher than those of pure PE, respectively. Concurrently, the composites displayed higher melting and crystallization temperatures. However, the crystallinity decreased slightly, while the thermal stability was significantly improved. The melt exhibited more pronounced non-Newtonian behavior. Compared to the loss modulus, the storage modulus increased more significantly in the low-frequency region, and a non-terminal effect was observed, which enhanced the structural stability of the system under low-frequency shear stress.\u003c/p\u003e","manuscriptTitle":"Synergistic functionalized polyethylene/attapulgite composites with maleic anhydride and silicone by reactive extrusion for enhanced metal-plastic interfacial adhesion","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 17:48:08","doi":"10.21203/rs.3.rs-7267966/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-09-03T18:36:39+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-03T10:19:25+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2025-08-20T21:37:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-04T03:20:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2025-08-03T04:18:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"e830471b-eb0f-4491-8659-1d1d03c99666","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-05T16:07:36+00:00","versionOfRecord":{"articleIdentity":"rs-7267966","link":"https://doi.org/10.1007/s10965-025-04738-w","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2026-01-04 15:58:05","publishedOnDateReadable":"January 4th, 2026"},"versionCreatedAt":"2025-09-09 17:48:08","video":"","vorDoi":"10.1007/s10965-025-04738-w","vorDoiUrl":"https://doi.org/10.1007/s10965-025-04738-w","workflowStages":[]},"version":"v1","identity":"rs-7267966","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7267966","identity":"rs-7267966","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}