Search Results (1,750)

Lignin, an abundant and renewable biopolymer, holds significant potential for asphalt modification owing to its unique aromatic structure and reactive functional groups. This review summarizes the main lignin preparation routes and key physicochemical attributes and assesses its applicability for enhancing asphalt performance. The physical incorporation of lignin strengthens the asphalt matrix, improving its viscoelastic properties and resistance to oxidative degradation. These enhancements are mainly attributed to the cross-linking effect of lignin’s polymer chains and the antioxidant capacity of its phenolic hydroxyl groups, which act as free-radical scavengers. At the mixture level, lignin-modified asphalt (LMA) exhibits improved aggregate bonding, leading to enhanced dynamic stability, fatigue resistance, and moisture resilience. Nevertheless, excessive lignin content can have a negative impact on low-temperature ductility and fatigue resistance at intermediate temperatures. This necessitates careful dosage optimization or composite modification with softeners or flexible fibers. Mechanistically, lignin disperses within the asphalt, where its polar groups adsorb onto lighter components to boost high-temperature performance, while its strong interaction with asphaltenes alleviates water-induced damage. Furthermore, life cycle assessment (LCA) studies indicate that lignin integration can substantially reduce or even offset greenhouse gas emissions through bio-based carbon storage. However, the magnitude of the benefit is highly sensitive to lignin production routes, allocation rules, and recycling scenarios. Although the laboratory research results are encouraging, there is a lack of large-scale road tests on LMA. There is also a lack of systematic research on the specific mechanism of how it interacts with asphalt components and changes the asphalt structure at the molecular level. In the future, long-term service-road engineering tests can be designed and implemented to verify the comprehensive performance of LMA under different climates and traffic grades. By using molecular dynamics simulation technology, a complex molecular model containing the four major components of asphalt and lignin can be constructed to study their interaction mechanism at the microscopic level. Full article

Microplastics (MPs) enter terrestrial ecosystems through various pathways, including the use of plastic mulching films, treated sewage sludge, and chemical and organic fertilizers. Polypropylene (PP) and polyethylene (PE) are the dominant polymers found in both traditional and facility-based farmland soils. MPs negatively impact soil microbial communities and harm soil invertebrates such as earthworms, nematodes, and springtails. In plants, MPs can induce oxidative stress, damage cells and inhibit growth. Polystyrene (PS) is often identified as the most hazardous polymer, frequently linked to reduced plant growth, which is the most commonly reported effect of soil MP contamination. This review provides novel insights beyond those reported in the previous literature, revealing that greenhouse-based cultivation, vegetable crops, orchards, and vineyards are significant contributors to increased microplastic soil contamination. Furthermore, the findings underscore pronounced global heterogeneity in microplastic concentrations within paddy soils, with recorded levels varying widely from 16 to 10,300 items kg⁻¹. Oxidative stress and additive leaching are the dominant mechanisms driving soil microplastic toxicity across exposed organisms. Quantitative studies of fungal-mediated microplastic biodegradation report mean degradation efficiencies of ~7.5% after 50 days, with mass losses of ~23.8% after 30 days and 35–38% after 90 days. Full article

One of the most critical damage modes affecting the structural performance of traditional composite materials, and therefore their durability, is the occurrence of interlaminar cracks (delamination), which are prone to grow under different loading conditions. In this study, the feasibility of repairing carbon fiber reinforced polymer (CFRP) laminates using structural adhesives was experimentally investigated by evaluating the Mode I interlaminar fracture toughness. Two unidirectional AS4 CFRP systems were analyzed, manufactured with epoxy 8552 and epoxy 3501-6 matrix resins. Mode I delamination behavior was characterized using Double Cantilever Beam (DCB) specimens. Three commercial structural adhesives were used in the repair process: two epoxy-based systems, (Loctite^® EA 9460™, manufactured by Henkel adhesives (Düsseldorf, Germany), and Araldite^® 2015 manufactured by Huntsman Advanced Materials (The Woodlands, TX, USA) and one low-odor acrylic adhesive, 3M Scotch-Weld^® DP8810NS manufactured by 3M Company (St. Paul, MN, USA). Adhesive joints were applied to previously fractured specimens, and the results were compared with those obtained from baseline composite specimens. The results indicate that repaired joints based on the 8552 matrix exhibited higher strain energy release rate (G_Ic) values, approaching those of the original material. The 3501-6 system showed increased fiber bridging, contributing to higher apparent fracture toughness. Among the adhesives evaluated, the acrylic-based adhesive provided the highest delamination resistance for both composite systems. Full article

The lightning strike protection (LSP) performance of nickel-coated carbon fiber nonwoven veils (NiCVs) with varying areal densities, integrated onto the surface of CFRP laminates, was evaluated through simulated lightning strike tests. Post-strike damage was evaluated through visual inspection, non-destructive ultrasonic testing, residual strength measurements, and microstructural examinations. Results indicated that the protection effectiveness improved with increasing NiCV areal density. The laminate with a 68 g/m² NiCV layer showed substantially reduced damage—its damage volume, damage area, and maximum damage depth decreased to 18%, 40%, and 51% of those of the control laminate—and it retained 95% of the reference compression strength, demonstrating the strong post-strike protection capability of this lightweight veil. A detailed analysis suggested that the NiCV LSP performance may arise from a mechanism involving high electrical conductivity, a thermally stable coated-fiber skeleton, as well as a distributed nonwoven network architecture. These results highlight NiCV as a promising functional approach for enhancing the lightning strike protection of CFRP aerostructures. Full article

The durability of the carbon fiber-reinforced polymer (CFRP)–concrete interface is a critical indicator for assessing the service life of composite structures in cold regions. This study systematically investigates the normal bond behavior under coupled deicing salt and freeze–thaw cycles through single-sided salt-frost tests on 126 specimens. The influence of surface roughness, number of freeze–thaw cycles, concrete strength grade, and CFRP material type was systematically evaluated. The results demonstrate that bond behavior is positively correlated with surface roughness, with the f₂ interface exhibiting optimal performance and increasing the ultimate capacity by up to 76.61% compared to the smooth interface. CFRP cloth showed superior bond retention compared to CFRP plates, which experienced a bond strength loss rate up to 26.90% higher than cloth specimens after six cycles. A critical performance threshold was identified between six and eight cycles, where the failure mode transitioned from cohesive adhesive failure to brittle interfacial debonding. Concrete matrix strength had a negligible effect compared to the dominant environmental damage. A two-parameter prediction model based on cycle count and roughness was established with high accuracy. SEM analysis confirmed that epoxy resin cracking, fiber–matrix debonding, and microcrack propagation in the concrete surface layer were the fundamental causes of macroscopic mechanical degradation. These findings provide a theoretical foundation for optimizing interface treatment and predicting the structural integrity of CFRP-strengthened systems in salt-frost regions. Full article

Hepatocellular carcinoma (HCC) represents the second leading cause of cancer mortality worldwide and is mostly caused by hepatitis B virus (HBV) infection. HBV can induce HCC by an indirect mechanism of continuous necro-inflammation, contributing to hepatocyte damage and promoting cancer, as well as by viral intrinsic factors. Among them, the major contributors to the development of HBV-related HCC are represented by (i) HBV DNA integration in genes modulating cell proliferation, (ii) HBV pro-oncogenic proteins, such as HBx and HBs, and (iii) the accumulation of viral mutations, enhancing the tumorigenic features of HBV proteins. The currently available antiviral treatments, based on the usage of Nucleos(t)ide analogs (NUCs), substantially control HBV replication. However, even a successful NUC treatment does not completely abrogate HCC risk, since it rarely allows achievement of an HBV functional cure, the therapeutic end-point associated with HBsAg loss and more favorable liver outcomes. To date, novel therapeutic strategies based on innovative direct antivirals (nucleic acid polymers, small interfering RNAs, antisense oligonucleotides, covalently closed circular DNA (cccDNA) inhibitors, and capsid assembly modulators) and immune-therapeutics (therapeutic vaccines, checkpoint inhibitors, and Toll-like receptor agonists) are under evaluation in clinical trials. These approaches are showing promising data in terms of an HBV functional cure, thus representing novel strategies that could be beneficial for reducing the burden of HBV-related HCC. Lastly, further efforts in drug development are necessary to identify new compounds that could achieve a sterilizing HBV cure, implying the complete elimination of cccDNA and integrated HBV DNA, the only end-point that completely eradicates HBV and its related oncogenic risk. Full article

The M21 epoxy matrix is a toughened material designed to enhance the fracture resistance of carbon fiber-reinforced polymers (CFRPs). This study presents an experimental characterization of the shear and interlaminar properties required for validating computational damage models of hybrid laminated composite panels manufactured with the M21 material system. In-plane shear behavior was evaluated using ±45 (PM45) tests, while interlaminar fracture properties were characterized through double cantilever beam (DCB) and end-notched flexure (ENF) tests. The results demonstrate that hybrid laminates exhibit high interfacial fracture toughness, with notably increased resistance observed in woven–woven and unidirectional–woven interface pairs. Parametric studies identified cohesive strength and fracture energy as the dominant parameters governing delamination behavior in numerical simulations. Corresponding values were extracted for each interface type, enabling accurate representation of damage initiation and propagation in finite element models. To the authors’ knowledge, this work provides the first experimental dataset for the listed M21-based hybrid unidirectional–woven and woven–woven interfaces, establishing a benchmark for future modeling and simulation of toughened composite structures. Full article

Fiber-reinforced polymer (FRP) composites are increasingly used in civil, marine, offshore, and energy infrastructure, where components routinely experience temperatures above ambient conditions. While the design of these components is largely driven by fiber-dominated characteristics, the deterioration of shear properties can lead to premature weakening and even failure. Thus, the performance and reliability of these systems depend intrinsically on the response of interlaminar shear characteristics, in-plane shear characteristics, and flexure-based shear characteristics to thermal loads ranging from uniform and monotonically increasing to cyclic and spike exposures. This paper presents a critical review of current knowledge of shear response in the presence of thermal exposure, with emphasis on temperature regimes that are below T_g in the vicinity of T_g and approaching T_d. Results show that thermal exposures cause matrix softening and microcracking, interphase degradation, and thermally induced residual stress redistribution that significantly reduces shear-based performance. Cyclic and short-duration spike/flash exposures result in accelerated damage through thermal fatigue; steep thermal gradients, including through the thickness; and localized interfacial failure loading to the onset of delamination or interlayer separation. Aspects such as layup/ply orientation, fiber volume fraction, degree of cure, and the availability and permeation of oxygen through the thickness can have significant effects. The review identifies key contradictions and ambiguities, pinpoints and prioritizes areas of critically needed research, and emphasizes the need for the development of true mechanistic models capable of predicting changes in shear performance characteristics over a range of thermal loading regimes. Full article

Polymers and their composites have introduced significant advancements in engineering and technology. The primary advantages of polymeric materials include their lightweight nature, ease of manufacturing, anti-corrosion properties, reduced power consumption during assembly and integration, as well as enhanced stiffness, durability, and fatigue resistance. Polymer coatings with conductive polymers allow efficient charge transfer and make electrodes more flexible, helping them better match the mechanical properties of soft tissues. In addition, polymer coatings can protect electrodes from corrosion, reduce biofouling, and provide sites for attaching biomolecules, making them essential for reliable and long-term bioelectrode and biosensor performance. Polymer coatings for electrochemical bioelectrodes play a crucial role in enhancing sensor performance and stability in biological environments as they improve the interaction between electronic devices and biological tissues. These coatings enhance biocompatibility by reducing inflammation and tissue damage while also lowering electrode impedance to improve signal quality. The present review focuses on the most recent developments in polymer coatings for electrochemical biosensors and respective applications. The manuscript provides an overview of polymer materials, emerging strategies, coating approaches, and the resulting enhancements in bioelectrochemical applications. Full article

Carbon fiber reinforced polymers (CFRPs) are widely used in aerospace and wind power applications, but the complex failure mechanisms of their connection structures pose challenges for connection design. This study aims to investigate the influence of bonding interface inclination angle and connection method on the failure mechanisms of CFRP joints under bending loads. The study investigated two design parameters: the joint geometry of the bonding interface (single-slope, transition-slope, and single-step) and the connection methods (bonding, bolting, and hybrid bonding–bolting). Finite element simulations analyzed the mechanical performance and failure modes under different design parameters. Bending tests validated the mechanical properties of the joint interface, validating the effectiveness of the numerical simulation. The study found that under bonded connections, the bending load increased with the slope of the connection interface, with improvements of 21.87% and 39.75%, respectively. The main reason is stress concentration caused by sharp geometric discontinuities. The hybrid connection had the highest peak load, with improvements of 38.38% and 43.91% compared to the other connection methods. Hybrid bonding–bolting connections further optimized structural performance and damage tolerance. This study reveals the damage mechanisms of the bonding interface and provides a reliable prediction method for aerospace and wind turbine blade applications. Full article

Artificial Intelligence (AI) is increasingly shaping materials research, particularly in the development and optimization of Glass Fibre Reinforced Polymer (GFRP) bars used as innovative alternatives to steel reinforcement. Despite this growing intersection, no prior bibliometric study has systematically mapped how AI contributes to the advancement of GFRP technologies. This paper fills this gap through a comprehensive bibliometric analysis based on 102 Scopus-indexed publications from 2015 to 2025. Following PRISMA guidelines, the study combines performance analysis and science mapping using VOSviewer to identify publication dynamics, leading journals, key contributors, and thematic clusters. The results reveal a tenfold growth in annual output (compound annual growth rate, CAGR = 10.1%) and five dominant research directions: (1) machine learning in structural analysis, (2) AI-driven composite materials modeling, (3) smart damage detection, (4) mechanical characterization, and (5) advanced deep learning frameworks. China, India, and the United States collectively account for more than half of global publications, highlighting strong international collaboration. The findings demonstrate that AI has evolved from an exploratory tool to a transformative driver of innovation in GFRP research. This study provides the first quantitative overview of this emerging field, identifies critical gaps such as sustainability integration and standardization, and proposes future directions to foster cross-disciplinary collaboration toward intelligent and sustainable composite structures. Full article

Carbon fibre-reinforced polymer (CFRP) bonded steel structures are increasingly adopted in offshore floating structures, yet their interfacial performance is highly susceptible to corrosion in marine environments. Corrosion-induced degradation of the CFRP–steel interface can significantly affect load transfer mechanisms and long-term structural reliability. This paper reports an experimental study on corrosion-induced degradation mechanisms and bond–slip behaviour of CFRP–steel double-strap joints. Controlled corrosion damage was generated using an accelerated electrochemical technique calibrated to ISO 9223 corrosivity categories. Tension tests were performed to examine the effects of corrosion degree, CFRP bond length, and the inclusion of glass fibre sheets (GFS) in the adhesive layer on failure modes, ultimate load capacity, and effective bond length. Digital image correlation (DIC) was employed to obtain strain distributions along the CFRP plates and to establish a bond–slip model for corroded interfaces. The results indicate that corrosion promotes a transition from CFRP delamination to steel–adhesive interface debonding, reduces interfacial shear strength to 17.52 MPa and fracture energy to 5.49 N/mm, and increases the effective bond length to 130 mm. Incorporating GFS mitigates corrosion-induced bond degradation and enhances joint performance. The proposed bond–slip model provides a basis for more reliable durability assessment and design of bonded joints in corrosive environments. Full article

In aerospace, defense, and energy systems, ceramic matrix composites (CMCs) are smart structural materials designed to function continuously in harsh mechanical, thermal, and oxidative conditions. Using high-strength fiber reinforcements and tailored interphases that enable damage-tolerant behavior, their creation tackles the intrinsic brittleness and low fracture toughness of monolithic ceramics. With a focus on chemical vapor infiltration, polymer infiltration and pyrolysis, melt infiltration, and additive manufacturing, this paper critically analyzes current developments in microstructural design, processing technologies, and interfacial engineering. Toughening mechanisms are examined in connection to multiscale mechanical responses, including controlled debonding, fiber bridging, fracture deflection, and energy dissipation pathways. Cutting-edge environmental barrier coatings are assessed alongside environmental durability issues like oxidation, volatilization, and hot corrosion. High-performance braking, nuclear systems, hypersonic vehicles, and turbine propulsion are evaluated as emerging uses. Future directions emphasize self-healing systems, ultra-high-temperature design, and environmentally friendly production methods. Full article

To address the prediction of fatigue damage for 3D-printed Carbon Fiber Reinforced Polymer (CFRP), this study used 3D-printing technology to fabricate CFRP specimens. Through multi-stage fatigue testing, samples with varying porosity levels were obtained. Based on porosity test results and ultrasonic attenuation coefficient measurements of specimens under different fatigue cycle counts, a quantitative relationship model was established between the porosity and ultrasonic attenuation coefficient of 3D-printed CFRP. According to the porosity and fatigue-loading cycles obtained from tests, the Time-series Generative Adversarial Network (TimeGAN) algorithm was employed for data augmentation to meet the requirements for neural-network training. Subsequently, the Long Short-Term Memory (LSTM) neural network was utilized to predict the fatigue damage evolution of 3D-printed CFRP specimens. Research findings indicate that by integrating the established relationship between porosity and ultrasonic attenuation coefficient, non-destructive testing of material fatigue damage evolution based on ultrasonic attenuation coefficient can be achieved. Full article

Natural rubber biosynthesis is catalyzed by a unilamella membrane-bound heterologous complex with multiple different subunits (rubber transferase, RTase). Two substrates and divalent metal cation activators are required, and their concentrations affect biosynthetic rate and polymer molecular weight. Rate, molecular weight, and complex stability are highly sensitive to Mg²⁺ and Mn²⁺ concentration, but studies are challenging because methods to control ion concentration may dislodge the elongating rubber polymers from the RTase complexes, halting synthesis and producing low-molecular-weight polymer. Here, programmable chemical actuators (PCAs) are used to electrochemically control rubber biosynthetic rate and subsequent molecular weight in enzymatically active rubber particles purified from Ficus elastica (Indian rubber tree). RTase activity was assayed using ³H-FPP (initiator) and ¹⁴C-IPP (monomer). Since only one FPP molecular is needed to initiate a new rubber polymer, the ratio of incorporated ³H-FPP to ¹⁴C-IPP was used to calculate the mean molecular weight of newly synthesized polymers. PCAs exchange ions in solution through REDOX reactions which we show control cation concentration without dislodging the elongating rubber polymers from the RTase. PCAs demonstrated highly tunable control over monomer incorporation and molecular weight in both Mg²⁺ and Mn²⁺ cations. REDOX cycling PCAs did not irreversibly inhibit the rubber transferase complex, and no indication of enzymatic damage was observed. Precise PCA control of RTase activity may pave the way for rubber eventually to be produced in bioreactors. Full article