Search Results (18,384)

Municipal solid waste (MSW) recycling is constrained by contamination, heterogeneity, and infrastructure built around material-specific pathways. We introduce effectiveness-normalized greenhouse gas (GHG) emissions as a system-level metric that adjusts reported process burdens by feedstock eligibility (Effectiveness Fraction, EF) and carbon recovery efficiency (CRE) to reflect real-world MSW conditions. Using published LCA data and engineering estimates, we benchmark six pathways, mechanical recycling, PET depolymerization, enzymatic depolymerization, pyrolysis, supercritical water gasification (SCWG), and Regenerative Robust Gasification (RRG), at the scale of mixed MSW. Normalizing for EF and CRE reveals large differences between process-level and system-level performance. Mechanical recycling and PET depolymerization show low process intensities yet high normalized impacts because they can treat only a small share of plastics in MSW. SCWG performs well at broader eligibility. RRG, a plasma-assisted molten-bath approach integrated with methanol synthesis, maintains the lowest normalized impact (~1.6 t CO₂e per ton of recycled polymer) while accepting virtually all organics in MSW and vitrifying inorganics. Modeled methanol yields are ~200–300 gal·t⁻¹ without external hydrogen and up to ~800 gal·t⁻¹ with renewable methane reforming. The metric clarifies trade-offs for policy and investment by rewarding technologies that maximize diversion and carbon retention. We discuss how effectiveness-normalized results can be incorporated into LCA practice and Extended Producer Responsibility (EPR) frameworks and outline research needs in techno-economics, regional scalability, hydrogen sourcing, and uncertainty analysis. Findings support aligning infrastructure and procurement with robust, scalable routes that deliver circular manufacturing from heterogeneous MSW. Full article

Global population growth, intensifying climate change, and escalating food security demands are mounting. In response, modern agriculture must transcend the limitations of traditional experience-based cultivation models to address issues such as low resource utilization, poor environmental adaptability, and significant yield fluctuations. As the core technical support of smart agriculture, agricultural sensors have become the key to transformation. This review systematically introduces the classification and working principles of current mainstream agricultural sensors: according to the monitoring parameters, they can be divided into humidity sensors, light sensors, gas sensors, pressure sensors, nutrient sensors, etc. At the same time, breakthroughs in emerging technologies such as microneedle sensing, nanosensing, and wireless sensor networks are being explored, which are breaking the application limitations of traditional sensors in complex agricultural environments. Combined with specific cases, the practical value of sensor technology is improving in agricultural drought monitoring, soil detection, and agricultural product quality assessment. Looking ahead, if agricultural sensors can overcome existing limitations through breakthroughs in material innovation, multi-sensor unit integration, and artificial intelligence algorithm fusion, this will provide stronger technological support for the further advancement of smart agriculture. Full article

Electrospun fibrous scaffolds based on cellulose acetate (CA), polycaprolactone (PCL), and poly (L-lactic acid) (PLLA) are versatile materials with applications spanning diverse fields, but in their pristine form, they typically lack significant inherent antibacterial properties. To address this limitation and expand their utility, this study explored the incorporation of xylitol, a natural antibacterial sugar alcohol, into these polymer matrices to enhance their physicochemical and antimicrobial properties. Electrospinning was employed to fabricate pristine and xylitol-loaded scaffolds with varying xylitol concentrations. Morphological analysis revealed polymer-dependent changes in fiber diameter and porosity. Mechanical testing assessed the impact of xylitol on tensile properties, while thermal analysis investigated alterations in melting temperature and crystallinity. The antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated using WST assay and live/dead staining. Notably, xylitol significantly enhanced the antibacterial activity against both bacterial species, with a more pronounced and rapid effect observed against S. aureus. The tailored scaffold properties and imparted antimicrobial characteristics highlight the potential of these xylitol-modified electrospun materials: they are easily produced, low-cost, and appropriate for a range of applications (dental applications, filters, masks, wound dressing, and packaging) where preventing bacterial contamination is crucial. Full article

Alkyd resins (ARs) represent a significant development in synthetic polymers, being among the oldest ones and playing a crucial role in numerous applications, especially within the coating sector. The trend is moving towards replacing non-renewable resources in the production of ARs with bio-based alternatives, with the goal of creating more sustainable binder materials as part of the transition to a bioeconomy. 2,5-Furandicarboxylic acid (FDCA) serves as a promising biomass-derived “building block” to replace non-renewable petroleum-derived aromatic diacids and anhydrides in AR synthesis. Various vegetable oils, including sunflower seed (SFO) and linseed oils (LSO), were utilized along with pentaerythritol (P) and glycerol (G) as polyols. FTIR and ¹H NMR spectroscopies were conducted for the verification of alkyd structures. The synthesized ARs were assessed for their physico-chemical properties, including acid value, hydroxyl value, color, density, and viscosity. The performance of the resulting alkyd coatings, which are crucial for their commercial applications, was examined. Key factors such as drying time, hardness, adhesion, wettability, chemical and corrosion resistance, and UV stability were analyzed. All synthesized FDCA-based alkyd coatings demonstrate outstanding adhesion, good thermal stability up to 220 °C, and barrier properties for steel with |Z|_0.02Hz ~10⁶–10⁷ Ohm cm⁻², which render them suitable for the processing requirements of indoor coating applications. The higher temperature at 50% mass loss (T₅₀) for SFO-P (397 °C) and LSO-P (413 °C) as compared to SFO-G (380 °C) and LSO-G (394 °C) indicated greater resistance to thermal breakdown when pentaerythritol was used as a polyol. Replacing glycerol with pentaerythritol in FDCA-based ARs resulted in a viscosity increase of 1.2–2.4 times and an enhancement in hardness from 2H to 3H. FDCA-based ARs exhibited decreased tack-free time, enhanced thermomechanical properties, and similar hardness as compared to phthalic anhydride-based ARs, underscoring the potential of FDCA as a sustainable alternative to phthalic anhydride in the formulation of ARs, integrating a greater proportion of renewable components for wood coating applications. Full article

The surface modification of coal fly ash (CFA) with silane coupling agents improves its compatibility with polymer matrices and supports its use as a sustainable filler in composite materials. This study examined the effects of the solvent system, reaction temperature, and pH on the grafting of 3-aminopropyltriethoxysilane (APTES) onto CFA surfaces. Functionalization was assessed by Fourier-transform infrared spectroscopy (FTIR), focusing on the CH₂ symmetric and asymmetric stretching bands of pure APTES at 2919 and 2957 cm⁻¹, noting that a slight shift in these bands can be expected following the change in the local chemical environment upon grafting. Solvent mixtures containing water (ethanol/water, acetone/water, and sulfuric acid/water) produced stronger coupling than the toluene solvent, which indicated the importance of water for APTES hydrolysis and silanol formation. Coupling efficiency increased with temperature and reached a maximum at 80 °C, where the balance between hydrolysis and condensation favored the formation of stable Si–O–Si bonds. The highest degree of functionalization was observed at pH 9, which corresponds to the point of zero charge of alumina in CFA, where neutral surface hydroxyl groups were available to react with silanols. These results define the optimal conditions for APTES grafting onto CFA and demonstrate its potential as a silane-modified filler in polymer composites. Atomic force microscopy (AFM) provided direct visual evidence of significant surface texture modifications induced by APTES treatment in the ethanol/water solvent system. Full article

The growing demand for sustainable materials has intensified research on biodegradable polymers, particularly poly(ε-caprolactone) (PCL), poly(lactic acid) (PLA), and their blends. PLA and PCL offer biocompatibility and biodegradability, making them attractive for biomedical, packaging, and agricultural applications; however, their practical utility remains limited owing to intrinsic drawbacks. PLA has low impact strength and poor thermal resistance, while PCL suffers from low tensile strength and slow degradation kinetics. Blending PLA with PCL can complement their properties, providing a tunable balance of stiffness and flexibility. Further improvements can be achieved through the incorporation of micro- and nanocellulose (NC), which act as reinforcements, nucleating agents, as well as compatibilizers. We critically examine fabrication strategies for NC-reinforced PLA, PCL, and their blends, highlighting NC extraction, surface modification, processing strategies, and dispersion techniques that prevent agglomeration and facilitate uniform distribution. Comparative insights into composite and nanocomposite systems reveal that NC incorporation significantly enhances mechanical properties, thermal resistance, crystallization, and biodegradation kinetics, particularly at low filler loadings, owing to its high surface area, specific strength, and hydrophilicity. The review underscores the potential of PLA/PCL-based nanocomposites as eco-friendly biomaterials with tunable properties tailored for diverse sustainable applications. Full article

Advances in additive manufacturing have accelerated the development of 3D-printed dental resin composites. These materials contain a higher proportion of organic matrix and less filler than light-cured representatives, which may affect their behavior in the oral environment. This study aimed to evaluate the biological and chemical properties of 3D-printed dental resin composites before and after artificial aging, and to compare them with the light-cured representative. Specimens from a light-cured composite (Omnichroma—OMCR) and two 3D-printed composites (GT Temp PRINT—GTPR; SprintRay CROWN—SPRY) were subjected to aging treatments: unaged (T0) or thermocycled for 5000 (T1) and 10,000 cycles (T2). Biological evaluation was performed using MTT assay and Live/Dead cell fluorescence microscopy using human gingival fibroblasts, whereas Raman spectroscopy analysed materials’ structural changes. Materials exhibited good biocompatibility (>70% cell viability), with OMCR displaying greater variability. OMCR was more susceptible to chemical degradation under thermal stresses than both 3D-printed materials. Tested 3D-printed composites can provide comparable or even superior biological and chemical properties compared to light-cured representative, likely due to optimized resin formulations and post-curing protocols that improve polymer network organization and reduce residual monomer release. These findings support the potential of tested 3D-printed composites for manufacturing dental restorations. Full article

This study investigates additive-free cold calendering of ELT-derived rubber powders across three particle size fractions (<0.5 mm, 0.5–0.71 mm, and 0.71–0.90 mm) using a two-roll mill without external heating or virgin polymers, aiming to obtain a cohesive material. Results demonstrate particle size effects on material properties. The finest fraction exhibited the highest crosslink density (5.30 × 10⁻⁴ mol·cm⁻³), approximately 18% greater than coarser fractions, correlating with superior hardness (≈65 ShA) and elastic modulus (≈7.5 MPa). Tensile properties ranged from 1.6–1.8 MPa stress and 60–75% elongation at break, positioning calendered sheets between low-temperature compression-molded GTR and high-pressure sintered materials reported in the literature. The cold calendering process achieves competitive mechanical performance with reduced energy consumption, simplified processing, and complete retention of recycled content. These findings support the development of regulation-compliant ELT recycling technologies, with potential applications in nonstructural construction panels, vibration-damping components, and protective barriers, advancing circular economy objectives while addressing emerging microplastic concerns. Full article

This study presents a comprehensive investigation into the large-scale production of synthetic and hybrid (nanoparticle-loaded) nanofibers using needleless electrospinning. A diverse range of polymers, including polyamide 6 (PA6) and its other polymer combinations, recycled PA6, polyamide 11 (PA11), polyamide 12 (PA12), polyvinyl butyral (PVB), polycaprolactone (PCL), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyurethane (PU), polyvinyl alcohol (PVA), and cellulose acetate (CA), were utilized to fabricate nanofibers with tailored properties such as polymer solution concentrations and various solvent systems. Furthermore, an extensive variety of nano- and micro-particles, including TiO₂, ZnO, MgO, CuO, Ag, graphene oxide, CeO₂, Er₂O₃, WO₃, MnO₂, and hyperbranched polymers, were incorporated into the polymeric systems to engineer multifunctional nanofibers with enhanced structural characteristics. The study examines the impact of polymer–nano/micro-particle interactions, fiber morphology, and the feasibility of large-scale production via needleless electrospinning. The resulting nanofibers exhibited diameters starting from 80 nm, depending on the polymer and processing conditions. The incorporation of TiO₂, CeO₂, WO₃, Ag, and ZnO nanoparticles into 15% PA6 solutions yielded well-dispersed hybrid nanofibers. By providing insights into polymer selection, nano- and micro-particle integration, and large-scale production techniques, this work establishes a versatile platform for scalable hybrid nanofiber fabrication, paving the way for innovative applications in nanotechnology and materials science. Full article

Atomic force microscopy (AFM) is widely used to quantify mechanical properties, typically Young’s modulus, by fitting force–indentation data with various mathematical contact models. However, results across laboratories often diverge, and the causes remain unresolved. Here, we interrogate the methodology by which mechanical properties are defined in AFM indentation and identify key limitations of the Hertz model, the standard model for determining mechanical properties, notably that the contact radius is not directly determined, which limits the accuracy of the estimated Young’s modulus. We hypothesize that this inference systematically overestimates the true tip–sample contact, which inflates the contact area and thereby underestimates Young’s modulus. This bias is amplified under large indentation conditions, which are frequently used in soft-material studies. To isolate and clarify the issue, we focus on a well-characterized polymer, polyvinyl chloride (PVC), using it as a controlled testbed for contact radius overestimation. Our analysis is focused on the contact radius and Hertz-based extraction of Young’s modulus. We determined the contact radius and Young’s modulus using AFM with two different probes: a sphere with a 20 nm radius (SPHERE20) and a sphere with a 2 µm radius (SPHERE2000). The results were compared to macroscopic data obtained using a standard measurement (ISO 527-1:2019) of Young’s modulus. The contact was modeled using finite element analysis (FEA). The dependence of the contact radius on the indentation was compared to the Hertz model. The results from FEA fit corrected contact radius values, and it is smaller by 15.46% (SPHERE20) and 57.9% (SPHERE2000) than those calculated by the Hertz model. Full article

The growing need for effective antimicrobial polymeric materials has prompted extensive development of functional chitosan derivatives with enhanced physicochemical and biological properties. In this work, the conjugates of chitosan with 4-anisaldehyde (ChT-AA) were synthesised through Schiff base formation at various molar ratios and characterised using FT-IR, ¹H NMR, and thermal analysis techniques (TGA/DSC). The spectral data confirmed the successful formation of imine (C=N) linkages and the incorporation of aromatic anisaldehyde fragments into the chitosan structure. Thermal analysis demonstrated increased stability and a higher glass transition temperature for ChT-AA compared with native chitosan, indicating reduced polymer chain mobility and enhanced structural rigidity. Viscoelastic gels based on the synthesised ChT-AA (1:3) and methylcellulose were prepared and evaluated for their rheological properties and antimicrobial performance. Rheological studies revealed non-Newtonian shear-thinning behaviour of these gels with pronounced thixotropy, confirming reversible network recovery after shear deformation. Antimicrobial evaluation of chitosan, its 4-anisaldehyde conjugate (ChT–AA, 1:3), and free 4-anisaldehyde revealed distinct activity patterns. The gels showed no inhibition in the disk diffusion assay, likely due to limited diffusion of the active components. In liquid media, both ChT and ChT–AA exhibited identical minimum inhibitory concentrations (MICs) against E. coli (0.313 mg/mL) and C. albicans (1.250 mg/mL), whereas ChT–AA showed two-fold stronger activity against S. aureus (0.313 mg/mL vs. 0.625 mg/mL for ChT). Free 4-anisaldehyde was most active against S. aureus (MIC = 0.175 mg/mL) but less effective against the other strains, confirming its narrower spectrum. These results indicate moderate antimicrobial efficacy in solution but limited activity in gel form due to restricted diffusion. Full article

This study explores the machinability of Material Extrusion (MEX) printed parts made from carbon fiber-reinforced polylactic acid (PLA). MEX-printed parts typically exhibit high surface roughness, necessitating post-processing to enhance their quality. In this work, milling was used as a post-processing method to improve the surface finish. Response surface methodology (RSM) experimental design was employed to investigate the effects of cutting velocity, feed rate, and depth of cut on the surface quality of the machined surfaces. Results showed that the as-built MEX-printed sample exhibited a high average surface roughness (Sa) of ~7.982 µm, indicating the need for post-processing. Post-processing milling considerably enhances the Sa by reducing it to ~1.621 µm under the optimal condition. Statistical findings showed that all considered factors have significant influence on the Sa, with feed rate as the most influential one, contributing to 47.63% of the total variation. The Sa values varied from 1.834 µm to 4.146 µm due to changes in the considered factors. Increasing feed rate leads to the emergence of cavities and ridges along the deposited filaments associated with brittle removal mechanism, resulting in higher surface roughness. Full article

This paper addresses the challenge of producing lightweight, low-cost, and highly functional devices and components for the electronics industry. To tackle this issue, functionally graded materials consisting of a polymer base and a metallic conductive layer were developed. Technology for producing functionally graded materials was created and optimized. To evaluate the influence of key process parameters on the functional and mechanical properties of the composites, three-dimensional models were constructed and mathematical equations were formulated. The continuity and thickness of the surface layer were examined, the dielectric properties of the polymer material were measured, the resistance of the conductive surface layer was assessed, and adhesion tests of the surface layer were performed. Full article

Minimally Invasive Surgery is often limited by the lack of tactile feedback. Indeed, surgeons have traditionally relied heavily on tactile feedback to estimate tissue stiffness - a critical factor in both diagnostics and treatment. With this in mind we present in this paper a flexible sensor foil, based on polymer optical waveguide. This sensor has been applied for real-time contact force measurement, material stiffness differentiation and surface texture reconstruction. Interrogated by a commercially available optoelectronic device, the sensor foil offers precise and reproducible feedback of contact forces up to 5 N, with a minimal detectable limit of 0.1 N. It also demonstrates distinct optical attenuation responses when indenting silicone samples of varying stiffnesses under controlled displacement. When integrated onto a 3D-printed module resembling an endoscopic camera and manipulated by a robotic arm, the sensor successfully generated spatial stiffness mapsof a phantom. Moreover, by sliding over structures with varying surface textures, the sensor foil was able to reconstruct surface profiles based on the light attenuation responses. The results demonstrate that the presented sensor foil possesses great potential for surgical applications by providing additional haptic information to surgeons. Full article

Polyvinyl chloride (PVC) is a widely used polymer in composite systems due to its versatility and processability, with growing use in advanced engineering applications. This study presents the formulation, processing optimisation, and detailed characterisation of a hot-dip PVC-based plastisol composite coating developed for electrical insulation in electric vehicle (EV) battery systems. A series of plastisol formulations with varying filler contents were prepared and applied via dip-coating at withdrawal speeds of 5, 10, and 15 mm s⁻¹. The 5 mm s⁻¹ withdrawal speed resulted in the most uniform coatings with thicknesses of 890–2100 µm. Mechanical testing showed that lower filler content significantly improved performance: Group 1 (lowest filler) exhibited the highest tensile strength (11.9 N mm⁻²), elongation at break (465%), tear strength (92 N mm⁻¹), and abrasion resistance. SEM and EDX analyses confirmed more homogeneous filler dispersion in Group 1, while FTIR spectra indicated stronger polymer–plasticiser interactions. Contact-angle measurements showed an increase of ${38}^{\circ }$ in low-filler samples, indicating enhanced surface hydrophobicity. Furthermore, Group 1 coatings demonstrated superior dielectric strength (22.1 kV mm⁻¹) and excellent corrosion resistance, maintaining integrity for over 2000 h in salt-spray testing. These findings highlight the importance of filler optimisation in balancing mechanical, electrical, and environmental performance. The proposed PVC-based composite coating offers a durable, cost-effective solution for next-generation EV battery insulation systems and has potential applicability in other high-performance engineering applications. Full article