Composite Modification Research Articles

Research Progress in Starch-based Dye Adsorbents

Abstract: Starch is a typical environment-friendly biomass material and there are considerable quantities of reactive hydroxyl groups in the starch molecule chain. Modifications could introduce a large number of functional groups, which can bind some dyeing contaminants, thereby removing the dyes. According to the different modification methods, starch-based adsorbents can be divided into three categories that are aminated-modified starch, ionic-modified starch, and composite-modified starch. The preparation method, structure properties, and adsorption capacity of modified starch dye adsorbents have been reviewed in this article. It can be concluded that the adsorption property of adsorbents depends on different adsorption conditions and modification methods. The adsorption properties of the adsorbents have been found to be influenced by temperature, initial concentration of dyes, and pH value of solution. Amination modification can introduce amino or amine groups into the starch skeleton to enhance the chelation or electrostatic effect of the adsorbents on dyes. Ion modification can improve the ion exchange and electrostatic interaction between the adsorbents and the dye. Composite modification can improve specific surface area, pore size, adsorption site, and structural stability of the adsorbents. Future studies are required to focus on producing dye adsorbents with high adsorption performance, stable structure, recyclability, and degradability.

Rheological and Aging Properties of Nano-Clay/SBS Composite-Modified Asphalt.

Nano-organic montmorillonite (OMMT) not only inhibits the harmful asphalt fume generation during the production and construction processes of asphalt mixtures but also effectively improves the performance of asphalt pavements. In order to prepare asphalt materials with smoke suppression effects and good road performance, this study selects nano-OMMT and SBS-modified asphalt for composite modification of asphalt mixtures and systematically investigates its road performance. Through the temperature sweep test, the frequency sweep test, the multiple stress creep recovery (MSCR) test, the bending beam rheometer (BBR) test, and the atomic force microscope (AFM) test, the high-temperature rheological properties, low-temperature rheological properties, high-temperature properties and aging resistance of the modified asphalt are studied. The research findings indicate that OMMT can effectively reduce the sensitivity of modified asphalt to load stress and improve its high-temperature rheological properties. SBS-modified asphalt shows increased creep stiffness and a decreased creep rate after OMMT modification, resulting in reduced flexibility and decreased low-temperature crack resistance. After short-term and long-term aging, the complex modulus aging index of OMMT/SBS composite-modified asphalt is lower than that of SBS-modified asphalt, and the phase angle aging index is higher than that of SBS-modified asphalt, demonstrating that OMMT enhances the aging resistance of SBS-modified asphalt. OMMT inhibits oxidation reactions in the asphalt matrix, reducing the formation of C=O and S=O bonds, thereby slowing down the aging process of modified asphalt and improving its aging resistance.

Enhanced Interfacial Modification by Ordered Discotic Liquid Crystals for Thermotolerance Perovskite Solar Cells.

Traditionally used phenylethylamine iodide (PEAI) and its derivatives, such as ortho-fluorine o-F-PEAI, in interfacial modification, are beneficial for perovskite solar cell (PSC) efficiency but vulnerable to heat stability above 85 °C due to ion migration. To address this issue, we propose a composite interface modification layer incorporating the discotic liquid crystal 2,3,6,7,10,11-hexa(pentoxy)triphenylene (HAT5) into o-F-PEAI. The triphenyl core in HAT5 promotes π-π stacking self-assembly and enhances its interaction with o-F-PEAI, forming an oriented columnar phase that improves hole extraction along the one-dimensional direction. HAT5 repairs structural defects in the interfacial layer and retains the layered structure to inhibit ion migration after annealing. Ultimately, our approach increases the efficiency of solar cells from 23.36% to 25.02%. The thermal stability of the devices retains 80.1% of their initial efficiency after aging at 85 °C for 1008 hours without encapsulation. Moreover, the optimized PSCs maintained their initial efficiency of 82.4% after aging under one sunlight exposure for 1008 hours. This study provides a novel strategy using composite materials for interface modification to enhance the thermal and light stability of semiconductor devices.

Enhanced Interfacial Modification by Ordered Discotic Liquid Crystals for Thermotolerance Perovskite Solar Cells

Traditionally used phenylethylamine iodide (PEAI) and its derivatives, such as ortho‐fluorine o‐F‐PEAI, in interfacial modification, are beneficial for perovskite solar cell (PSC) efficiency but vulnerable to heat stability above 85 °C due to ion migration. To address this issue, we propose a composite interface modification layer incorporating the discotic liquid crystal 2,3,6,7,10,11‐hexa(pentoxy)triphenylene (HAT5) into o‐F‐PEAI. The triphenyl core in HAT5 promotes π‐π stacking self‐assembly and enhances its interaction with o‐F‐PEAI, forming an oriented columnar phase that improves hole extraction along the one‐dimensional direction. HAT5 repairs structural defects in the interfacial layer and retains the layered structure to inhibit ion migration after annealing. Ultimately, our approach increases the efficiency of solar cells from 23.36% to 25.02%. The thermal stability of the devices retains 80.1% of their initial efficiency after aging at 85 °C for 1008 hours without encapsulation. Moreover, the optimized PSCs maintained their initial efficiency of 82.4% after aging under one sunlight exposure for 1008 hours. This study provides a novel strategy using composite materials for interface modification to enhance the thermal and light stability of semiconductor devices.

The Influence of Molecular Weights on Dispersion and Thermoelectric Performance of Alkoxy Side-Chain Polythiophene/Carbon Nanotube Composite Materials.

In the development of wearable electronic devices, the composite modification of conductive polymers and single-walled carbon nanotubes (SWCNTs) has become a burgeoning research area. This study presents the synthesis of a novel polythiophene derivative, poly(3-alkoxythiophene) (P3(TEG)T), with alkoxy side chains. Different molecular weight variants of P3(TEG)T (P1-P4) were prepared and combined with SWCNTs to form composite materials. Density functional theory (DFT) calculations revealed a reduced bandgap for P3(TEG)T. Raman spectroscopy demonstrated π-π interactions between P3(TEG)T and SWCNTs, facilitating the dispersion of single-walled carbon nanotubes and the formation of a continuous conductive network. Among the composite films, P4/SWCNTs-0.9 exhibited the highest thermoelectric performance, with a power factor (PF) value of 449.50 μW m-1 K-2. The fabricated flexible thermoelectric device achieved an output power of 3976.92 nW at 50 K, with a tensile strength of 59.34 MPa for P4/SWCNTs. Our findings highlight the strong interfacial interactions between P3(TEG)T and SWCNTs in the composite material, providing an effective charge transfer pathway. Furthermore, an improvement in the tensile performance was observed with an increase in the molecular weight of the polymer used in the composite, offering a viable platform for the development of high-performance flexible organic thermoelectric materials.

Hydroxyapatite functionalized natural fiber‐reinforced composites: Interfacial modification and additive manufacturing

AbstractNatural fibers are lightweight, cost‐effective, readily available, and eco‐friendly materials. However, natural fiber‐reinforced composites are constrained by biological inconsistency and inferior fiber‐matrix interfacial properties, which restrict effective processing using advanced additive manufacturing methods. In this study, we develop a novel concept for natural fiber composite interfaces by growing hydroxyapatite (HAP) nanocrystals on jute fibers. The resulting hybrid composite is characterized using mechanical testing, nanoindentation, and modulus mapping. The interfacial region suggests a 31.4% increase in stiffness and possesses a storage modulus of up to 7.5 GPa. The tensile modulus and strength of the hybrid composite improves by 30% and 33%, respectively. Furthermore, we develop a novel process for the additive manufacturing of jute fiber thermoset composites through a direct writing (DW) process. The HAP modification increases thermal conductivity, consequently improving the curing process during DW and enhancing composite manufacturability. We demonstrate that the DW process enables the printing of intricate multilayer geometries with varying fiber content.Highlights Hydroxyapatite is used for natural fiber composite interfacial modification. Nanoindentation shows the interfacial region exhibits 31.4% higher stiffness. Modified composites possess superior mechanical performance. Jute fibers are thermally functionalized for composite additive manufacturing. A direct writing method is developed for continuous functionalized jute fiber.

Preparation and Properties of Waterborne Polyurethane and SBS Composite-Modified Emulsified Asphalt

To address the issue of insufficient durability of traditional modified emulsified asphalt in the application of cold mix and cold paving anti-skid wear layers, this study utilizes cationic waterborne polyurethane (PU+) for composite modification to enhance adhesion and performance across a range of temperatures. Initially, composite-modified emulsified asphalt samples were prepared with varying dosages of PU+ according to a gradient method. Routine performance tests were conducted on the evaporated residues for analysis. Advanced rheological tests, including temperature sweep (TS), frequency sweep (FS), linear amplitude sweep (LAS), and multi-stress creep recovery (MSCR) tests, were performed using a dynamic shear rheometer (DSR). Surface free energy (SFE) tests were conducted with a fully automated surface tension meter (STM). A comprehensive evaluation of the high-temperature rheological properties, fatigue properties, adhesion properties, and water damage resistance of the modified emulsified asphalt residues was carried out. Chemical changes before and after modification were characterized using Fourier transform infrared spectroscopy (FTIR), and the distribution of polymers in the evaporated residue was observed using fluorescence microscopy (FM). The results demonstrated that cationic waterborne polyurethane significantly enhanced the fatigue and adhesion properties of SBS-modified emulsified asphalt, but it also weakened the water damage resistance of asphalt. MSCR tests revealed that the addition of cationic waterborne polyurethane might reduce the elastic recovery performance of modified asphalt, thereby weakening its resistance to rutting. Among the samples, the modified asphalt with a PU+ content of 6% exhibited good high-temperature shear resistance and elastic recovery performance, demonstrating the best anti-rutting performance.

Study on the interface of high specific energy High stability

High nickel terterial oxide, with high specific capacity and low cost advantages, is the preferred positive electrode for high specific energy lithium-ion power batteries at present. However, the high nickel ternary cathode material is easy to have side reactions with the electrolyte in the high delithium state, which can not only lead to the dissolution of transition metal ions and the formation of the surface salt phase, but also cause the lattice oxygen loss and surface interface side reactions, resulting in rapid attenuation of electrode capacity. In this paper, the development history and structural characteristics of high nickel ternary cathode materials are introduced, and the surface interface problems leading to capacity attenuation and structural degradation are comprehensively analyzed. From this perspective, three effective strategies for improving electrochemical performance of high nickel ternary cathode materials are summarized. Finally, by describing the advantages and disadvantages of these layered cathode materials, the challenges faced by these layered cathode materials are discussed, and it is pointed out that in the future, composite modification strategies should be adopted to optimize their structures and improve their properties.

Reducing the moisture susceptibility of recycled hot‐mix asphalt mixture with composite modification technology

AbstractStyrene–butadiene–styrene block copolymer (SBS)‐modified asphalt is a key material for constructing recycled hot‐mix asphalt mixtures (RHMAs). However, these mixtures still risk insufficient moisture stability. To this end, this study investigates the feasibility of asphalt composite modification technology to enhance RHMA performance. SBS, high‐viscosity agent (HVA) and crumb‐rubber materials (CRM) were used to prepare SBS‐HVA‐ and SBS‐CRM‐modified asphalt, with SBS‐modified asphalt as the control group, and the adhesion properties of the asphalt were evaluated using surface free energy tests. RHMAs with 50% reclaimed asphalt pavement were then prepared with each type of modified asphalt. The moisture susceptibility of these mixtures was analyzed using moisture‐induced sensitivity, freeze–thaw splitting and immersion Marshall tests. It was found that HVA significantly enhanced the adhesion of SBS‐modified asphalt under dry conditions, while CRM had a minimal effect. Compared to RHMA with SBS‐modified asphalt, HVA and CRM additives are crucial for enhancing the moisture stability of RHMA in the immersion Marshall test. However, CRM does not improve the moisture stability of RHMA in the moisture‐induced sensitivity and freezing–thaw splitting tests. From the conducted study, it can be proposed that SBS and HVA composite‐modified asphalt can be utilized in RHMAs to achieve higher moisture stability. © 2024 Society of Chemical Industry.

Advancing Adsorption and Separation with Modified SBA-15: A Comprehensive Review and Future Perspectives.

Mesoporous silica SBA-15 has emerged as a promising adsorbent and separation material due to its unique structural and physicochemical properties. To further enhance its performance, various surface modification strategies, including metal oxide and noble metal incorporation for improved catalytic activity and stability, organic functionalization with amino and thiol groups for enhanced adsorption capacity and selectivity, and inorganic-organic composite modification for synergistic effects, have been extensively explored. This review provides a comprehensive overview of the recent advances in the surface modification of SBA-15 for adsorption and separation applications. The synthesis methods, structural properties, and advantages of SBA-15 are discussed, followed by a detailed analysis of the different modification strategies and their structure-performance relationships. The adsorption and separation performance of functionalized SBA-15 materials in the removal of organic pollutants, heavy metal ions, gases, and biomolecules, as well as in chromatographic and solid-liquid separation, is critically evaluated. Despite the significant progress, challenges and opportunities for future research are identified, including the development of low-cost and sustainable synthesis routes, rational design of SBA-15-based materials with tailored properties, and integration into practical applications. This review aims to guide future research efforts in developing advanced SBA-15-based materials for sustainable environmental and industrial applications, with an emphasis on green and scalable modification strategies.

Performance assessment of composite modified bitumen integrated with desulfurized crumb rubber and SBS modifier as waterproofing adhesive layer

Performance of the waterproofing adhesive layer played a critical role for governing duration of bridge deck paving system due to harsh service conditions. To develop a new type of modified bitumen suitable for the layer between bridge deck and overlaid asphalt, this study investigated the performance of composite modified bitumen (CMB) integrated with desulfurized crumb rubber (DCR) and SBS modifier. The influence of DCR and SBS additive on rheological behavior, high-temperature performance, low-temperature cracking resistance, and adhesive performance of CMB was investigated by adopting various experimental tests, which including penetration, ductility, softening point, Brookfield viscosity, dynamic shear rheometer (DSR), bending beam rheometer (BBR), and bonding strength. The high-temperature stiffness and low-temperature flexibility of CMB was improved after composite modification, which in turn contributed to the shear and cracking resistance. The black diagram indicated that the formation of polymer network in the CMB improved the viscous flow resistance and maintained elastic response at high in-service temperature. The bonding strength and moisture stability of the composite bitumen-concrete interface were enhanced, with the properties exceeded the commercial SBS modified bitumen. The CMB binders R18S2 and R18S3 presented good performance and can be used for waterproofing adhesive layer as a substitute of the commercial SBS modified bitumen.

Modification of cement-based circulating fluidized bed combustion slag: Physical grinding and chemical excitation

This study investigates the effects of physical grinding (ball, impact, and jet milling) and chemical modification (using various dosages of Na2SO4, CaO, triethanolamine (TEA), and their composite modifiers) on CFBCS. The fluidity, flexural strength, compressive strength, and expansion rate of different modification methods were tested. Microstructural and phase composition analyses were conducted using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, mercury intrusion porosimetry, and thermogravimetry-differential thermogravimetry. The results indicated that impact milling improved mortar fluidity by 2.9 % compared to ball milling, while jet milling reduced it by 5.7 %. Chemical modifications decreased paste fluidity but increased mortar strength and reduced expansion rates. Impact milling and jet milling improved 28-day compressive strength by 13.76 % and 16.01 %, respectively, and reduced the 90-day expansion rate by 0.007 % and 0.012 %, respectively. Composite chemical modification (CM-C) enhanced 28-day compressive strength by 23.88 % and reduced the 90-day expansion rate by 0.019 %. Microscopic analysis shows that modification reduced the pores and pore size of the mortar while increasing the hydration products. After TEA modification, rod-shaped AFt forms a reticulated structure, with C–S–H gel and CH crystals adhering to it. The hydration products of CFBCS mortar formed a network after jet milling, and the addition of composite modifiers resulted in a layered, dense structure.

Modified Bentonite As a Dissolve-Extrusion Composite and Its Modification Mechanism.

In the geological core drilling industry, simple and low-cost drilling fluid formulations are required that are easy to apply and maintain. Currently, drilling fluid systems with simple formulations generally exhibit poor performance and do not satisfy the requirements of complex formations. The application of powder surface modification technology has been extensively investigated in several fields; however, few are the studies focusing on the modification of bentonite. Consequently, in this study, based on the surface modification technology of powders, bentonite is modified using the modifiers ZJ-1 and ZJ-2, giving it the characteristic of "one additive with multiple functions". This allows the construction of a new type of drilling fluid system with a simple formulation (water + modified bentonite), excellent performance, and easy application and maintenance. First, a new composite modification method named the dissolution and extrusion composite modification method was proposed, and the dosage of the modifier and the optimal ratio of each modifier were determined experimentally. Second, orthogonal design experiments were conducted to determine the optimal preparation conditions based on the rheological properties of the drilling fluid, dynamic plastic ratio, and filtration loss. Subsequently, the performance of the modified bentonite drilling fluid was analyzed by comparing it to that of a regular bentonite drilling fluid. Finally, the modification mechanism of bentonite was analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was revealed that a total modifier dosage of 2% and a ratio of ZJ-1 to ZJ-2 of 1.5:0.5 afforded a modified bentonite drilling fluid with significantly enhanced performance compared to a regular bentonite drilling fluid. The modified bentonite exhibited a filtration loss of 7.5 mL, funnel viscosity of 51.5 s, static shear force of 2.5 Pa, dynamic shear force of 9.198 Pa, apparent viscosity of 29 mPa·s, and plastic viscosity of 20 mPa·s. The experimental repeatability was good, and the optimal preparation conditions for modified bentonite involved a reaction time of 10 h, a reaction temperature of 100 °C, and a mechanical pressure of 0.5 MPa. Microscopic analysis showed that the modifiers were incorporated into bentonite through intercalation and surface adsorption and that the modified bentonite can form a dense filter cake. Our study provides a new drilling fluid solution for the geological core drilling industry, effectively promoting the advancement of drilling fluid technologies.

Thermally modified sepiolite integrated with aluminum chloride for phosphorus loading management of heavily polluted urban waters

Phosphorus (P) is one of the characteristic pollutants in urban heavily polluted river waters. How to control P enrichment and manage the P loading by a green and efficient adsorbent is an important challenge to control polluted waters. Modified sepiolite is often utilized for the regulation of phosphate in contaminated urban aquatic environments due to its excellent adsorption capacity. In the research, the modification of natural sepiolite with chloride at high temperature (C/Al-Sep) was conducted to enhance its P adsorption capacity and effectively manage the P loading in polluted waters. Batch adsorption experiments demonstrated that the capacity of phosphate adsorbed by C/Al-Sep was significantly improved after composite modification. Adsorption isotherm results indicated that the maximum phosphate adsorption capacity was approximately 13.75 mg/g. Furthermore, the modified sepiolite maintained a stable adsorption capacity over a wide pH range, except CO32- and HCO3-. The adsorption capacity of these common anions in water was almost unaffected. The characterization and adsorption experiments showed that the phosphate adsorption by C/Al-Sep was primarily driven by chemisorption. Additionally, the modification treatment increased the specific surface area of the sepiolite. The main mechanism of phosphate adsorption by the modified sepiolite was the formation of calcium-phosphate precipitates with the inner layer of Al-OP complexes. The results of the research indicate that the use of thermally modified sepiolite in combination with aluminum chloride provides an all-purpose, environmentally friendly material for the subsequent in-situ coverage of contaminated substrates and for the remediation of phosphates in heavily polluted urban waters.

Multiscale evaluation of aging susceptibility of asphalt binders modified with recycled rubber and plastic pyrolytic oil composites

Changes in rheological performance, migration of chemical components, and microstructure transformation are some of the processes that occur as asphalt binders age across various stages throughout their lifecycle. Aging-related changes influence pavement performance, typically increasing its susceptibility to issues like fatigue and thermal cracking. Thus, comprehending the role of aging in the performance of asphalt binders is vital for devising effective pavement design and maintenance strategies. The use of plastic pyrolysis oil and recycled non-tire automobile rubber to create oil-rubber modified asphalt binders is becoming quite popular as a sustainable and environmentally friendly method for asphalt pavements. This study aimed to assess the aging behavior of asphalt binders modified with plastic pyrolysis oil and recycled non-tire automotive rubber, both separately and in composite modification. Binders underwent testing under four aging conditions: unaged, short-term aged, long-term aged, and extended long-term aged. The study focused on a multiscale assessment of aging characteristics, encompassing macroscale, mesoscale, microscale, and nanoscale analyses. At the macroscale, the binders were tested for rheological parameters using multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and Glover-Rowe (G-R) parameter tests, while the mesoscale analysis was conducted using Fourier-transform infrared (FTIR) spectroscopy. Additionally, microstructural analysis was performed using atomic force microscopy (AFM), and nanoscale evaluation was carried out using nuclear magnetic resonance (NMR). Finally, a comprehensive assessment index that included all the parameters under study was generated using radar graph analysis. It was observed that modifying an asphalt binder with a heat-preheated composite of plastic pyrolysis oil and recycled non-tire automotive rubber showed the lowest CAI values, thus helping to mitigate the effects of aging and achieving enhanced binder performance.

Novel PEI/Zein core–shell composite as mixed-mode stationary phase for high performance liquid chromatography

Based on the adhesion of polyethyleneimine (PEI), a novel PEI/zein co-modified core-shell stationary phase (PEI/Zein@SiO2) was prepared by doping zein to form a composite modification layer. The stationary phase achieved effective separation of nucleosides, bases and antibiotics in hydrophilic interaction mode on account of the hydrophilic groups of composite coating. With the hydrophobicity of zein, the flavones could be separated in reversed-phase mode. In short, the separation and analysis of hydrophilic/hydrophobic compounds were accomplished excellently by the PEI/Zein@SiO2 column with mixed double mode. The prepared chromatographic stationary phase not only avoided the dissolution of zein, but also covered the strong adsorption of some analytes caused by silica hydroxyl groups on the surface of silica spheres. The morphological structure and specific surface area of the material were reflected by various characterization techniques. Hydrophilic/hydrophobic compounds were used as tested analytes to research separation performance and retention mechanisms of PEI/Zein@SiO2 column. The stability and reproducibility of the PEI/Zein@SiO2 stationary phase were satisfied. Therefore, the modification of zein could improve the separation selectivity of stationary phase effectively for complex samples, which had the potential to be one of the significant potential application materials in stationary phase packing.

Friction and Wear Performance of a Hydraulic Motor Roller/Piston Pair Contact lined with the Self-Lubricating Bearing Bush Modified by PEEK

Poly Ether Ether Ketone (PEEK) is a kind of special engineering plastic with excellent properties such as high-temperature resistance, self-lubrication, wear resistance, and high mechanical strength. However, its blending or composite modification applications still face numerous challenges. The primary objective of this research was to evaluate the friction and wear performance of a three-layer self-lubricating bearing bush, which was made from a modified material containing short carbon fiber and Poly Ether Ether Ketone (SCF/PEEK). The bearing bush is used as a surface contact layer on the pistons of a hydraulic motor in the interface with the cam roller. The bearing bush was processed using a 15% SCF-modified PEEK material, and the friction and wear test was conducted using a self-built friction test machine. This study aimed to assess the frictional and wear characteristics of the SCF/PEEK-modified material in the bearing bush. The results show that as the experimental pressure rises from 15 MPa to 25 MPa, the friction coefficient of the SCF-modified bearing bush experiences a significant decrease from 0.420 to 0.296. Furthermore, the stability of the frictional morphology of carbon fibers indicates its effective adaptability to low speed and high load conditions.

Effects of TLA on rheological, aging, and chemical performance of SBS modified asphalt

The durability and stability of Styrene-Butadiene-Styrene (SBS) modified asphalt in practical applications have garnered significant attention, with resistance to aging emerging as a pivotal indicator for evaluating performance. This study focuses on the composite modification of SBS-modified asphalt (SBS-MA) using Trinidad Lake asphalt (TLA), resulting in the creation of SBS-MA and three types of SBS/TLA composite modified asphalt (with TLA content at 10 %, 20 % and 30 % of the mass of SBS-MA). To assess the aging resistance, the four modified asphalts underwent prolonged aging for 10 h, 20 h, 30 h and 40 h using the Pressurized Aging Vessel (PAV) test. The macroscopic performance and microscopic characteristics of differently aged modified asphalts were then analyzed through methods such as Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR) and Fourier Transform Infrared Spectroscopy (FTIR). From the perspective of high-temperature performance, the asphalt modified with 10 % SBS exhibits optimal performance indicators during long-term aging processes, with a correlation coefficient reaching up to 99 % in relation to aging time. When the asphalt content exceeds 30 %, it adversely affects the stress sensitivity of SBS-modified asphalt. In terms of fatigue performance analysis, under a 5 % strain condition, the fatigue life of S-30 composite modified asphalt only decreases by 8 %, and TLA mitigates fatigue damage during the aging process of SBS-modified asphalt. Regarding low-temperature performance analysis, when the TLA content surpasses 20 %, it only manifests negative effects on SBS-modified asphalt. From a microscopic perspective, TLA introduces more sulfonyl and carbonyl groups, increasing by 3.6 times and 11 times respectively at a 30 % concentration, thus retarding the oxidation aging reaction of ST-CMA. In summary, this study provides valuable insights and methods for improving the aging resistance of SBS-MA, offering guidance for the application of Trinidad Lake asphalt in road engineering.

High-Density Polyethylene Pipe Butt-Fusion Joint Detection via Total Focusing Method and Spatiotemporal Singular Value Decomposition

High-density polyethylene (HDPE) pipes are widely used for urban natural gas transportation. Pipes are usually welded using the technique of thermal butt fusion, which is prone to manufacturing defects that are detrimental to safe operation. This paper proposes a spatiotemporal singular value decomposition preprocessing improved total focusing method (STSVD-ITFM) imaging algorithm combined with ultrasonic phased array technology for non-destructive testing. That is, the ultrasonic real-value signal data are first processed using STSVD filtering, enhancing the spatiotemporal singular values corresponding to the defective signal components. The TFM algorithm is then improved by establishing a composite modification factor based on the directivity function and the corrected energy attenuation factor by adding angle variable. Finally, the filtered signal data are utilized for imaging. Experiments are conducted by examining specimen blocks of HDPE materials with through-hole defects. The results show the following: the STSVD-ITFM algorithm proposed in this paper can better suppress static clutter in the near-field region, and the average signal-to-noise ratios are all higher than the TFM algorithm. Moreover, the STSVD-ITFM algorithm has the smallest average error among all defect depth quantification results.

Ultrasonic peening-waterjet composite surface modification of 7075-T6 aluminum alloy for residual stress release and transformation mechanism

The release and transformation mechanism of residual stress contributes to the improvement of metal materials' processing and performance, enhancing their structural stability, surface integrity, and fracture resistance. This paper focuses on the Ultrasonic Impact Treatment-Solid Particle Entrainment by Waterjet (UIT-SPEWJ) composite surface modification of 7075-T6 aluminum alloy, investigating the effects of UIT-SPEWJ process parameters (jet pressure and target distance) on the alloy's surface quality, roughness, microhardness, residual stress, and the evolution mechanism of microstructure. The results indicate that the 7075-T6 aluminum alloy modified by UIT-SPEWJ mainly exhibits a "meteorite crater" effect, accompanied by significant smearing and ploughing phenomena. Surface roughness shows a trend of first decreasing and then increasing with the rise of jet pressure and target distance. The minimum surface roughness, 0.852 μm, is achieved at a jet pressure of 25 MPa and a target distance of 7.5 mm. The microhardness of the samples modified by UIT-SPEWJ gradually decreases from the surface to the substrate with increasing depth. The hardened layer depths of the samples UIT-SPEWJ-1–6 after modification are approximately 174 μm, 226 μm, 200 μm, 196 μm, 176 μm, and 172 μm, respectively. After UIT, SPEWJ, and UIT-SPEWJ surface modifications, the surface of 7075-T6 aluminum alloy mainly exhibits compressive residual stress (CRS). The surface residual stress σ_srs of samples modified by UIT and SPEWJ are approximately 195.161 and 215.752 MPa, respectively. The surface residual stresses of UIT-SPEWJ-1–6 samples are significantly improved to 277.089, 529.499, 393.615, 459.261, 368.084, and 220.635 MPa, respectively, with UIT-SPEWJ-2 sample having the highest surface residual stress, which is 2.7 and 2.4 times that of UIT and SPEWJ modified surfaces. Samples modified by UIT-SPEWJ present significant dislocation phenomena, and the precipitated phases mainly include the needle-like metastable phase η', as well as the equilibrium phase η (MgZn2) with a rod-like structure. At lower jet pressures and larger target distances, the 7075-T6 aluminum alloy exhibits a continuous PFZ with a size of approximately 12–23 nm. As jet pressure increases and target distance decreases, discontinuous grain boundary precipitate bands appear, sized around 8–17 nm. Moreover, when the jet pressure is 25 MPa and the target distance is 7.5 mm, the grain boundary precipitated phases are more dispersed.