Search Results (5,216)

Conventional lithium-ion battery separators made from petroleum-based polymers pose environmental concerns due to their non-renewable origin and energy-intensive production. Novel bio-based alternatives, such as poly(alkylene 2,5-furanoate)s (PAFs), offer improved sustainability and favorable thermomechanical properties. This work investigated electrospun mats of poly(butylene 2,5-furandicarboxylate) (PBF) and poly(pentamethylene 2,5-furandicarboxylate) (PPeF), which, despite structural similarity, exhibit distinct behaviors. PBF mats demonstrated superior performance with fiber diameters of about 1.0 µm and porosity of 53.6% with high thermal stability (T_g = 25 °C, T_m = 170 °C, 18.8% crystallinity). The semicrystalline PBF showed higher electrolyte uptake (531–658 wt%) and had a lower MacMullin number (N_M = 3–10) than commercial Celgard separators (N_M = 15), indicating enhanced ionic conductivity. Electrochemical testing revealed stability up to 5 V and successful cycling performance with specific capacity of 135 mAh/g after 100 cycles and coulombic efficiency near 100%. In contrast, PPeF’s amorphous nature (T_g = 14 °C) resulted in temperature-sensitive pore closure that enhanced safety by reducing short-circuit risk, although its solubility in carbonate electrolytes limited its application to aqueous systems. These findings highlight the potential of PAF-based separators to improve both the environmental impact and performance of batteries, supporting the development of safer and more sustainable energy storage systems. Full article

Caffeine is a natural alkaloid consumed primarily for its stimulant and metabolic effects. Some everyday products, such as coffee, tea, soft drinks, sports supplements, and even pain relievers, contain caffeine. However, excessive caffeine consumption, greater than 400 mg per day, can cause adverse effects. Therefore, this work presents an electrochemical sensor based on a molecularly imprinted polymer (MIP) electropolymerized on gold nanoparticles functionalized with p-aminothiophenol (AuNPs-pATP) for caffeine quantification. AuNPs-pATP synthesized show a spherical morphology with an average diameter of 2.54 nm. Stages of MIP formation were monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using a potassium ferrocyanide redox probe, where the following were observed: (i) an increase in conductivity upon modification of the GCE with AuNPs-pATP, (ii) the blocking of active sites during the electropolymerization step, and (iii) the release of specific cavities upon template removal, revealing consistent differences between the MIP and the control polymer (NIP). SEM images revealed three-dimensional spherical cavities on MIP surface, while the NIP showed a more compact rough surface. Caffeine quantification was performed using square wave voltammetry (SWV) with LOD of 0.195 µmol L⁻¹ and LOQ of 0.592 µmol L⁻¹. Interference studies indicated high selectivity and a high density of caffeine-specific binding sites in the MIP. Additionally, MIP sensor demonstrated reusability, good reproducibility, and stability, as well as promising results for analysis in soft drink and sports supplement samples. Full article

MXenes, an emerging class of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, have demonstrated exceptional potential in tribology: the study of friction, wear, and lubrication. Their remarkable mechanical strength, thermal stability, and tunable surface chemistry make them ideal candidates for solid lubricants, lubricant additives, and protective coatings in mechanical systems. This review comprehensively examines the tribological performance of MXenes under diverse environmental conditions, including high temperatures, vacuum, humid atmospheres, and liquid lubricants. A particular emphasis is placed on the influence of surface terminations (-OH, -O, -F) on friction reduction and wear resistance. Additionally, we discuss strategies for enhancing MXene performance through hybridization with polymers, nanoparticles, and ionic liquids, enabling superior durability in applications ranging from micro/nano-electromechanical systems (MEMS/NEMS) to aerospace and biomedical devices. We also highlight recent advances in experimental characterization techniques and computational modeling, which provide deeper insights into MXene tribomechanics. Despite their promise, key challenges such as oxidation susceptibility, high synthesis costs, and performance variability hinder large-scale commercialization. Emerging solutions, including eco-friendly synthesis methods and optimized composite designs, are explored as pathways to overcome these limitations. Overall, MXenes represent a transformative avenue for developing next-generation tribological materials that combine high efficiency, sustainability, and multifunctionality. Continued research and innovation in this field could unlock groundbreaking advancements across industrial and engineering applications. Full article

The development of organic light-emitting diodes (OLEDs) for high-resolution, large-area displays relies on effective encapsulation technology. Accordingly, this study proposes a novel multilayer structure utilizing a cyclo-olefin polymer-based film. This solution significantly reduces process time and cost while achieving remarkable barrier performance. Optimization involved presenting various models and enhancing substrate–film adhesion via ultraviolet or plasma treatment, consequently improving water vapor transmission rate. Furthermore, the optimized structure’s feasibility as an OLED encapsulation layer was confirmed. These results promise to enhance core technological capabilities, improving production yield and minimizing costs—key factors for next-generation displays. Full article

To address the issues of traditional mooring lines, such as high self-weight, low strength, and poor durability, Carbon-Fiber-Reinforced Polymer (CFRP) was investigated as a material for mooring lines of offshore floating wind turbines, aiming to achieve high performance, lightweight design, and long service life for mooring systems. Based on a “chain–cable–chain” configuration, a CFRP mooring line design is proposed in this study. Taking a 5 MW offshore floating wind turbine as the research object, the dynamic performance of offshore floating wind turbines with steel chains, steel cables, polyester ropes, and CFRP mooring lines under combined wind, wave, and current loads was compared and analyzed to demonstrate the feasibility of applying CFRP mooring lines by combining the potential flow theory and the rigid–flexible coupling multi-body model. The research results indicate that, compared to traditional mooring systems such as steel chains, steel cables, and polyester ropes, (1) under static water, the CFRP mooring system exhibits a larger static water free decay response and longer free decay duration; (2) under operating sea conditions, the motion response and mooring tension of the offshore floating wind turbine with CFRP mooring lines are smaller than those with steel cables and steel chains but greater than those with polyester ropes; and (3) under extreme sea conditions, the motion responses of the offshore floating wind turbine with CFRP mooring lines are smaller than those with steel wire ropes and steel chains but close to the displacement responses of the polyester rope system, while the increase in mooring tension is relatively moderate and the safety factor is the highest. Full article

Self-lubricating polymer composites based on polydicyclopentadiene (PDCPD) were reinforced with carbon nanomaterials to evaluate the effect of filler type and loading on their mechanical and tribological performance. Four carbon forms were introduced: carbon nanotubes (0.3 and 0.5 wt.%), carbon fibers (5 and 10 wt.%), flake graphite (5 and 10 wt.%) and dusty graphite (5 and 10 wt.%). Tensile tests showed that carbon fibers—and graphite-filled matrices reached ~50 MPa tensile strength, while the addition of carbon nanotubes resulted in a reduction in strength by half compared to the pure resin, indicating poor compatibility of carbon nanotubes with the matrix. The highest compressive strength, ~90 MPa, was obtained for PDCPD containing 5 wt.% carbon fibers. Tribological behavior was evaluated in a pin-on-disk configuration under dry sliding. All fillers lowered the coefficient of friction; the most pronounced, three-fold reduction was achieved with both graphite variants. The combined high load-bearing capacity and greatly reduced friction of the graphite and carbon fibers modified systems highlight their potential as self-lubricating bearing materials capable of replacing conventional metal or oil-lubricated components. Full article

The article presents the results of uniaxial fatigue tests for the high-cycle regime on a polymer matrix composite material reinforced with Kevlar and carbon fibers, fabricated with material extrusion (MEX) technology. The samples were manufactured according to the ASTM D638 type-I standard, and the tests were performed under a load inversion factor of 0.1 at room temperature, measuring the number of cycles to failure. Based on previous results, in which different configurations were tested, tests were carried out on specimens subjected to loads ranging from 40% to 91% of the rupture stress for Kevlar and 25.5% to 80.7% for carbon, obtaining a maximum life of 2.5 M cycles for Kevlar and 4.06 M cycles for carbon. The observed failure modes included fiber tearing, matrix cracking, and fiber–matrix pull-out. Full article

To further investigate the bond behavior between carbon fiber-reinforced polymer (CFRP) bars and ultra-high-performance concrete (UHPC) under monotonic loading, a finite element model was established in ABAQUS based on existing experimental data. The material parameters, constitutive models, and interface contact definitions were verified through numerical simulation. Utilizing this modeling strategy, 36 center-pull finite element models with dimensions of 150 mm × 150 mm × 150 mm were analyzed. By systematically varying the geometric parameters of the CFRP bars, the effects of surface configuration, bar diameter, and rib spacing on the bond performance between CFRP bars and UHPC were analyzed. The results demonstrate that uniform-ribbed bars exhibit the highest bond performance, followed by helical-ribbed bars, whereas dented-ribbed bars show the lowest bond strength. The ultimate bond strength decreases with increasing bar diameter. For uniform-ribbed bars, the optimal rib spacing is 1.2D (where D is the bar diameter), resulting in the highest peak bond strength. Full article

Additive manufacturing via selective laser sintering (SLS) enables the rapid production of geometrically complex polyamide 12 (PA12) components. However, conventional pointwise analysis techniques often overlook the full depth of continuous experimental datasets, thus limiting the interpretation of structure–function relationships that are essential to high-performance design. This study employs functional data analysis (FDA) to elucidate the microstructural, chemical, thermal, and mechanical behaviours of SLS-fabricated PA12, focusing on the effects of build orientation (horizontal, transverse, vertical) and wall thickness (2.0–3.0 mm). The samples were produced via a commercial SLS platform and characterised via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and tensile testing. The FDA was applied to raw, normalised, and first derivative datasets via Python’s Scikit-FDA package, increasing the sensitivity to latent material variations. The findings demonstrate that the build orientation has a marked influence on the crystallinity and mechanical performance: horizontal builds yield narrower gamma-phase XRD peaks, greater structural order, and enhanced tensile properties, whereas vertical builds exhibit broader peak dispersion and greater thermal sensitivity. The wall thickness effects were minor, with only isolated flux-related anomalies. The FTIR spectra confirmed the consistent chemical stability across all the conditions. The FDA successfully identified subtle transitions and anisotropies that eluded traditional methods, underscoring its methodological strength for advanced polymer characterisation. These insights offer practical guidance for refining SLS process parameters and improving predictive design strategies in polymer-based additive manufacturing. Full article

The low aqueous solubility of many new drug candidates, a key challenge in oral drug development, has been effectively addressed by liquid self-emulsifying drug delivery systems (SEDDS). However, the inherent instability and manufacturing limitations of liquid formulations have prompted significant research into solid SEDDS. This review provides a comprehensive analysis of the recent advancements in solid SEDDS, focusing on the pivotal roles of solid carriers and solidification techniques. We examine a wide range of carrier materials, including mesoporous silica, polymers, mesoporous carbon, porous carbonate salts, and clay-based materials, highlighting how their physicochemical properties can be leveraged to control drug loading, release kinetics, and in vivo performance. We also detail the various solidification methods, such as spray drying, hot melt extrusion, adsorption, and 3D printing, and their impact on the final product’s quality and scalability. Furthermore, this review explores applications of solid SEDDS, including controlled release, mucoadhesive technology, and targeted drug delivery, as well as the key commercial challenges and future perspectives. By synthesizing these diverse aspects, this paper serves as a valuable resource for designing high-performance solid SEDDS with enhanced stability, bioavailability, and functional versatility. Full article

In recent years, natural polymers have gained significant attention due to their abundance, biodegradability and versatility, offering a promising alternative to conventional synthetic polymers. Among natural polymers, cellulose and hemicellulose hold a special place, being the most abundant plant polysaccharides in nature, which serve as key structural materials in the synthesis of hydrogels. Cellulose has attracted significant attention in the development of hydrogels due to the fact that it confers desirable mechanical properties, high water absorption and biocompatibility. Hemicellulose, although with a more amorphous structure than cellulose, contains various functional groups that facilitate its chemical modification. With an environmentally friendly nature and low cost, these polysaccharides have gained major interest and are highly appreciated by both the academic and industrial communities. This review comprehensively presents recent advances in the design and development of hydrogels made from renewable biopolymers—cellulose and hemicellulose—providing an in-depth exploration of the information recorded over the past five years. The latest strategies for the synthesis of hydrogels, their formation mechanisms and their most important properties are analyzed and summarized in detail from the perspective of physical and chemical crosslinking. A comparative analysis is performed between these hydrogels, highlighting not only the advantages and disadvantages of each type of hydrogel but also the main challenges associated with the balance between mechanical strength, swelling capacity, biodegradability and cost-effectiveness. Finally, the advanced biomedical applications of these hydrogels in areas such as drug delivery, wound dressings and tissue engineering are presented in detail. Full article

The present research aims to investigate the impact of various mixing techniques (centrifugal planetary mixing, ultrasonication, and high-temperature magnetic stirring) on the properties of nanocomposite epoxy resins using expanded graphite particles. Differential scanning calorimetry reveals that the curing behavior and glass transition temperature are influenced by the selected method, indicating that a suitable choice allows increasing curing degree (C.D.) and glass transition temperature up to 10% and 12%, respectively. Morphological analysis performed via Scanning Electron Microscopy and Tunneling Atomic Force Microscopy offers detailed insights into the dispersion characteristics of fillers within polymer matrices, which sensitively affect the properties of the materials. The electrical conductivity values vary by more than five orders of magnitude among the various mixing methods. Centrifugal mixing leads to a decrease in the equilibrium concentration of water (C_eq) by up to 23% compared to that of the unfilled matrix, thanks to the chemical interactions that occur between the graphitic particles and the epoxy matrix (detectable via Fourier Transform Infrared Spectroscopy). Such a reduction is strongly desired in strategic fields such as the transport sector. The analysis of the obtained results suggests choosing the dispersion method of the filler in the matrix by considering the required performance for the specific planned application. Full article

This study investigates the mechanical, thermal, electrical, and microstructural properties of polyamide 66 (PA66) composites reinforced with waste-derived micro–nano NiCr (80/20) powders. Composites containing 2, 5, and 8 wt% NiCr were prepared using thermokinetic mixing and compression molding, followed by characterization via tensile testing, Shore D hardness, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), and thermal/electrical conductivity measurements. Results showed a progressive increase in tensile modulus, tensile strength, hardness, and thermal conductivity with increasing NiCr content, reaching maximum values at 8 wt% filler. However, elongation at break decreased, indicating reduced ductility due to restricted polymer chain mobility. DSC and FTIR analyses revealed that low NiCr loadings promoted nucleation and crystallinity, while higher contents disrupted crystalline domains. Electrical conductivity exhibited a slight upward trend, remaining sub-percolative up to 8 wt% NiCr; conductivity modulation is modest at high filler loadings. SEM–EDS confirmed uniform dispersion at low–moderate contents and agglomeration at higher levels. The use of industrial waste NiCr powder not only enhanced material performance but also contributed to sustainable materials engineering by valorizing by-products from the coatings industry. These findings suggest that NiCr/PA66 composites have potential applications in automotive, electronics, and thermal management systems requiring improved mechanical rigidity and heat dissipation. Full article

Additive manufacturing via fused deposition modeling (FDM) offers a versatile method for fabricating complex polymer parts; however, enhancing their mechanical properties remains a significant challenge, particularly for biopolymers such as polylactic acid (PLA). PLA is widely used in 3D printing due to its biodegradability and ease of processing, but its relatively low mechanical strength and impact resistance limit its broader applications. This study explores the reinforcement of PLA with boron nitride nanoplatelets (BNNPs) to improve its mechanical properties. This study also aims to optimize key FDM process parameters, such as reinforcement content, nozzle temperature, printing speed, layer thickness, and sample orientation, using a Taguchi L27 design. Results show that the addition of 0.04 wt.% BNNP significantly improves the mechanical properties of PLA, enhancing tensile strength by 44.2%, Young’s modulus by 45.5%, and impact strength by over 500% compared to pure PLA. Statistical analysis (ANOVA) reveals that printing speed and nozzle temperature are the primary factors affecting tensile strength and Young’s modulus, while impact strength is primarily influenced by nozzle temperature and reinforcement content. Machine learning models, such as CatBoost and Gaussian process regression, predict mechanical properties with high accuracy (R² > 0.98), providing valuable insights for tailoring PLA/BNNP composites and optimizing FDM process parameters. This integrated approach presents a promising path for developing high-performance, sustainable nanocomposites for advanced additive manufacturing applications. Full article

In this study, the oxidative upgrading of heavy oil residues using polymer-containing waste for the sustainable production of bitumen was investigated. Oxidation was performed at temperatures of 250–270 °C for 3–4 h with the addition of 2–3 wt.% polyethylene-based waste, under an air flow of 7 L/min. The physical and mechanical characterization of the resulting bitumen demonstrated compliance with oxidized modified bitumen grades OMB 100/130 and OMB 70/100. FTIR spectroscopy revealed the formation of carbonyl and sulfoxide functional groups, indicating the effective oxidative transformation of the bitumen matrix and partial incorporation of polyethylene fragments. NMR spectroscopy confirmed increased aromaticity and carbonyl content, while also detecting polyethylene-derived signals, suggesting compatibility and integration of the polymer waste into the oxidized structure. The thermal and rheological results showed that the optimal conditions for producing high-quality oxidized bitumen involved the use of 2% polymer waste at 270 °C for 4 h, yielding enhanced physical properties and chemical stability. These findings support the feasibility of using polymer-containing waste for bitumen upgrading, offering both environmental and technical advantages. The method not only improves the quality of bitumen but also contributes to waste valorization and circular economy practices in the road construction industry. Full article