Search Results (563)

Plastic is a valuable material for packaging of food and pharmaceuticals, protective wrappings in construction and agriculture, and fluid storage. Flexible plastic or plastic film waste from packaging, agriculture, and construction applications grows at a rate of at least 92 million metric tons a year, is considered challenging to recycle, and is typically landfilled. In recent years, there have been great advancements in plastic recycling technology in order to deal with the global challenge of plastic waste buildup and support legislation from a local to national level to implement recycling. This work highlights the most recent advancements in plastic film recycling. Plastic films are mono- or multilayered based on what their applications will be, with multilayer multimaterial films being the more challenging feedstock for recycling. Mechanical recycling cannot easily process flexible films. Pyrolysis can use polyolefin-based film as feedstock but is not practiced at scale to match the rate of plastic film waste generation, and incineration can recover energy from film feedstock but is not recycling plastic. This has motivated the development of new recycling technologies designed around plastic films. Better characterization technologies to identify film compositions in municipal waste streams have been key to sorting out film feedstock for mechanical recycling and the baling of flexible plastic waste, but they struggle with multilayer films and black plastic. Compatibilization enables the recycling of mixed plastic waste but requires polymer compositions for selecting specific compatibilizers. Dissolution–precipitation recovers individual types of polymers from multilayer films and, at the same time, can purify polymers from additives or contaminants, but requires intense solvent processing and associated energy. Delamination of multilayer films can separate and recover solid films of polyolefins at relatively low amounts of solvent but requires quality feedstock to be efficient. Both dissolution–precipitation and delamination recycling of films recover the original polymer molecules and maintain their embodied energy, hence support circularity. In the case of PET-containing films, depolymerization to recover PET monomers offers opportunities to recycle challenging film feedstock. Full article

The artificial lighting demand of buildings is a controllable sustainability lever, whereas metalized food-packaging waste (i.e., multilayer polymer-aluminum films used for barrier protection) is difficult to recycle and routinely landfilled or incinerated, representing an underexplored circular-economy opportunity. This simulation-based feasibility study connected both objectives by investigating whether metalized snack-packaging waste can function as a daylight-redirecting surface on a faceted interior light shelf. Five configurations were simulated in VELUX Daylight Visualizer 3 using Ankara’s EnergyPlus Weather climate file (39.93° N): a no-shelf baseline (S1), white (ρ = 0.80) and metalized (ρ = 0.80–0.88) flat shelves (S2, S3), and faceted equivalents (S4, S5). None of the five scenarios met the EN 17037:2018 sufficiency threshold (DA300 ≥ 50%); the best configuration, S5 (faceted, metalized), reached DA300 = 40.23%. Within this limitation, S5 outperformed all comparators, averaging 3116 lux (9.6× baseline) and achieving a uniformity ratio of 0.823. Faceted geometry increased illuminance by 1.74–1.78× over an equivalent flat metalized shelf; metalized flat shelves outperformed the white ones by 1.44–1.54×, except in September, when high solar altitude caused a 0.83–0.89× reversal, eliminated by faceting. S5 reduced artificial lighting dependency from 78.42% to 59.77% of occupied hours (~101 kWh/yr, first-year estimate) and nearly halved critical daylighting-deficit hours (49%). However, it exceeded the 2000 lux useful-daylight ceiling in ~55% of occupied hours, indicating that glare mitigation is necessary for deployment. These preliminary results warrant further experimental and life-cycle work before the sustainability benefits of the circular economy pathway can be established. A sensitivity analysis confirms that S5’s daylighting advantage persists, though at reduced magnitude, under both a conservative reflectance assumption (ρ = 0.80) and a more energy-representative window-to-wall ratio (47.5%). Full article

Cholesteric liquid crystals (CLCs) possess the unique ability to selectively reflect incident circularly polarized light, exhibiting tremendous potential in diverse optical applications. In this study, a trilayer composite architecture of polymer-stabilized cholesteric liquid crystals (PSCLCs) was successfully fabricated. Introducing poly(vinyl alcohol) (PVA) as intervening barrier layers enabled the formation of independent and mutually non-interfering broadband reflection bands within each respective layer. Initially, a single-layer system was evaluated to identify the effects of component concentrations and polymerization conditions on the reflection bandwidth. Under optimal conditions, a maximum reflection bandwidth of 890 nm was achieved. Building upon these parameters, the effective concatenation of two independent reflection bands was accomplished by precisely regulating the concentration of the chiral dopant R5011 in the adjacent layers. Subsequently, the trilayer PSCLC film was constructed, ultimately broadening the total reflection bandwidth to 1650 nm. Characterization via polarized optical microscopy (POM) confirmed that the liquid crystal molecules consistently maintained a well-defined planar texture throughout the fabrication process of the multilayer films. Additionally, the film shows good infrared shielding performance. Its ability to regulate ambient light makes it highly promising as an optical filter and thermal management component in LC smart windows and emerging displays. Full article

This study investigates the electrochemical properties of polymer-based microelectrode arrays (pMEAs) and their performance in measuring oxygen (O₂) and hydrogen peroxide (H₂O₂). Morphological characterization by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) revealed a uniform, fine-grained platinum surface with nanoscale roughness, consistent with the Ti/Pt/Au/Pt multilayer stack architecture. The electrochemical behavior of the pMEAs was assessed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which demonstrated favorable responses for both O₂ reduction and H₂O₂ oxidation, together with low impedance (41.1 kΩ at 1 kHz). For O₂ detection, amperometric measurements at −0.6 V vs. Ag/AgCl indicated a sensitivity of −0.25 ± 0.04 nA μM⁻¹ and a detection limit of 5.4 ± 1.4 nM. For H₂O₂ detection, application of +0.7 V vs. Ag/AgCl resulted in a sensitivity of 88.13 ± 7.61 nA mM⁻¹ and a detection limit of 41.9 ± 5.6 nM. Selectivity evaluation showed effective interferent exclusion following m-phenylenediamine electrodeposition, without compromising analytical performance. Overall, these findings indicate the suitability of pMEAs for real-time, in vivo monitoring of O₂ and H₂O₂ in brain tissue with high spatial and temporal resolution, supporting applications in oxidative stress research and neurometabolic sensing. Full article

Background: Chairside CAD/CAM technology has reshaped restorative dentistry by enabling single-visit indirect restorations fabricated from glass-ceramics, zirconia, polymer-infiltrated ceramic networks (PICN), and resin nanoceramics. Despite a rapidly growing body of evidence, no recent systematic synthesis has integrated mechanical, adhesive, ageing-related, and clinical outcomes within a unified framework. Methods: This systematic review was conducted and reported in accordance with PRISMA 2020. A structured electronic search was performed in the Web of Science Core Collection and MEDLINE via PubMed for studies published between January 2021 and May 2026. The search was complemented by Google Scholar and reference-list screening. Eligible primary studies were selected according to predefined PICOS criteria and synthesised qualitatively because methodological and outcome heterogeneity precluded meta-analysis. Of the 444 records initially identified, 332 were screened after duplicate removal, and 31 primary studies met all eligibility criteria and were included in the qualitative synthesis. Review-level publications were used only for reference-list screening and contextual comparison and did not contribute data to the synthesis. Results: Laboratory studies indicated favourable flexural-strength profiles for lithium disilicate, advanced lithium disilicate, and Y-TZP zirconia, while PICN blocks showed comparatively favourable resistance to thermomechanical ageing. The limited available clinical evidence reported high short-term survival for chairside CAD/CAM restorations, but did not permit definitive comparisons between material classes. Across the predominantly in vitro bonding studies, hydrofluoric-acid etching followed by silanisation produced the most consistent bond-strength results for glass-ceramics, whereas Al₂O₃ air-abrasion combined with an MDP-containing primer showed favourable bond strength to zirconia. Universal adhesives showed promising laboratory performance on hybrid blocks but did not consistently match the performance of dedicated surface-conditioning protocols for glass-ceramics and zirconia. Conclusions: Material selection in chairside dentistry should consider intrinsic material properties, surface-conditioning requirements, and the planned cementation strategy. Standardised laboratory protocols and adequately powered prospective clinical studies with longer follow-up are required before definitive material-specific clinical recommendations can be established, particularly for advanced lithium disilicate and multilayer zirconias. Full article

The delay-and-sum total focusing method (TFM) for ultrasonic full matrix capture (FMC) depends on accurate ray path and travel time computation. In L-shaped carbon fiber-reinforced polymer (CFRP) corner parts, elastic anisotropy, multilayer stacking, and curvature-induced ray path non-uniqueness generate strong stripe-like coherent clutter (deterministic structural echoes), degrading focusing and sizing. To address this, we search multiple physically plausible candidate ray paths and propose a phase-consistency-adaptive multi-path fusion TFM (PCA-MPF-TFM) that performs pixel-wise path selection and fusion. The method is validated using pulse-echo FMC data acquired with a water-immersion linear array from a 6.4 mm-thick L-shaped CFRP specimen containing three 3 mm-diameter polytetrafluoroethylene (PTFE) inserts; the two within the concave-side inspection region were quantitatively evaluated. Compared with conventional isotropic TFM, an edge-adjacent delamination previously masked by structural noise is consistently detected with a 9.2 dB signal-to-noise ratio (SNR) and a 0.2 mm length error. For the second delamination, the SNR improves by 25 dB and the length error decreases from 0.6 mm to 0.2 mm. Experimental results demonstrate improved defect detectability and noise robustness under curved, anisotropic, and multilayer propagation while maintaining sub-millimeter sizing accuracy. Full article

Three-dimensional (3D) graphene foams are attractive as lightweight conductive scaffolds with large surface area and broadband light absorption but achieving reproducible porosity and preserving the architecture after metal-template removal remain challenging. Here we report a stepwise route to freestanding 3D multilayer graphene foams based on (i) hydrogen-bubble-assisted electrodeposition of porous Ni on Cu foils, (ii) time-controlled pre-annealing at 1000 °C to drive Cu diffusion and form porous Ni-Cu alloy templates, (iii) in situ graphene CVD at 1000 °C under fixed growth conditions, and (iv) wet etching to remove the metal scaffold without a polymer support. The influence of pre-annealing (0, 1, 3, and 7 h) on template evolution, graphene growth, and foam stability was systematically investigated via SEM, EDS, XRD and Raman studies. Before etching, Raman spectroscopy indicates low-defect graphenic coatings with locally heterogeneous few-layer-like to multilayer-like signatures. Only samples pre-annealed for at least 3 h preserved the porous 3D architecture after metal removal, indicating the formation of self-supporting graphenic networks with improved post-etch morphological stability. Raman and XRD analyses further revealed a progressive reduction in structural degradation, residual strain, and stacking disorder with increasing pre-annealing time. Among the investigated samples, the foams obtained after 3 and 7 h of template pre-annealing combined preserved 3D morphology with low sheet resistance (10–20 Ω/□), negligible optical transmittance (<5%), and strong broadband visible-light absorption (75–90%). Full article

Over the past decades, biodegradable polymer films have gained significant attention owing to their environmental friendliness and abundant raw material availability. However, the barrier properties of biodegradable polymers as packaging materials remain inferior to those of traditional petroleum-based plastic films, limiting their suitability for applications sensitive to oxygen or moisture such as food preservation, pharmaceutical packaging, and electronic device protection. In this paper, we summarize effective strategies to enhance the barrier properties of biodegradable polymer packaging films, such as surface coating, polymer blending, multilayer compounding, copolymerization and modification, nanocomposite technology, and filler reinforcement. Subsequently, we discuss the application of these strategies to biodegradable polymers, including both natural and synthetic varieties. A central focus is elucidating the relationship between the modification approaches, molecular structure, and oxygen/water barrier properties in high-barrier biodegradable polymer materials, aiming to provide valuable guidance for the development of advanced biodegradable polymer packaging materials. Finally, we present the existing challenges and future prospects for the development of high-barrier biodegradable polymer packaging materials. Full article

Two novel multi-layer three-dimensional polymers (Polymer 1 and Polymer 2) were designed and synthesized via a multi-step coupling strategy. Their photophysical properties, aggregation-induced emission (AIE) behaviors, and metal ion sensing capabilities were systematically investigated. Both polymers exhibited typical aggregation-induced emission (AIE) characteristics with significantly enhanced fluorescence upon aggregation in tetrahydrofuran (THF)/water mixtures. Polymer 1 demonstrated selective and sensitive detection of Ag⁺ ions with a detection limit of 2.14 μM, while Polymer 2 showed exceptional recognition toward Ba²⁺ ions with a detection limit of 6.42 μM. Competitive experiments confirmed their good selectivity even in the presence of interfering metal ions. The distinct sensing behaviors were attributed to the different coordination environments provided by the polymer backbones. This work expands the family of multi-layer three-dimensional AIE-active polymers and demonstrates their utility as fluorescent probes for the detection of silver and barium ions. Full article

This study presents a comprehensive analysis and predictive modeling framework for the axial compressive strength (f_cc) and ultimate axial strain (ε_cu) of concrete columns confined within fiber-reinforced polymer (FRP) systems. Large databases comprising 3312 samples for f_cc and 3319 for ε_cu were compiled from the literature, encompassing a wide range of key variables, including unconfined concrete strength from 7 MPa to 204 MPa and diverse FRP confinement configurations. The datasets were subjected to extensive statistical and multivariate analyses to identify the primary factors influencing axial behavior and guide feature selection for predictive modeling. Three groups of machine learning (ML) algorithms were subsequently considered: (i) artificial neural networks (including multilayer perceptrons with one and two hidden layers), (ii) kernel-based models (Gaussian process regression and support vector regression), and (iii) tree-based ensemble models (gradient boosting machine, eXtreme gradient boosting, and light gradient boosting machine). Hyperparameters were optimized using grid search cross-validation, while feature importance analyses were performed to quantify the contribution of each input variable. Among all ML models, eXtreme gradient boosting demonstrated superior predictive performance, effectively capturing the nonlinear and multivariate interactions governing confinement effectiveness. Comparative analysis with the top performing regression-based formulations further highlighted the accuracy, robustness, and generalization capability of the eXtreme gradient boosting model. The findings provide a data-driven and interpretable framework for the design and prediction of FRP-confined concrete columns. Full article

We have developed a quantitative method for characterizing the actual multilayer polymer material-made membranes’ architecture with a computer analysis of their scanning electron microscopy (SEM) images. The proposed approach consists of contour morphological heterogeneity function (CMHF) calculations. The approbation was carried out on polysulfone, polytetrafluoroethylene and polyimide-made membranes. The corresponding CMHF series were computed for different depths. It was possible to identify the structural zones’ location for all the considered membranes. The developed technique provides the possibility of standardizing the SEM images’ analysis and determining the thicknesses of the surface, transition and volumetric layers of filtering and separating equipment elements. The suggested algorithm can automate the membrane’s structure and architecture metrological analysis with computer vision techniques. Full article

Environmental stressors like low temperature, low relative humidity (RH), and particulate matter (PM2.5), promote tear film instability and dry eye disease. This study investigates how these conditions alter the interfacial behavior of meibomian gland secretion (MGS) films in vitro and evaluates the capacity of mucomimetic polymers (0.5% hyaluronic acid [HA], polyvinylpyrrolidone [PVP], and chondroitin sulfate [CHS]) to suppress these impacts. MGS films over polymer-containing aqueous subphases were analyzed using a Langmuir trough and Brewster angle microscopy under adverse conditions (20 °C subphase, 20% RH, PM2.5 exposure). A sophisticated analytical framework was developed to evaluate MGS duplex multilayers: (i) a Volmer equation-based 2D-VES model to probe interfacial molecular properties (limiting area, compressibility, cohesion pressure) and (ii) a combined Maxwell viscoelastic and diffusion-relaxation model to quantify the dilatational relaxation modulus. Results indicate that despite their distinct nature, environmental stressors similarly disrupt the multilayer structure, reorganization, and rheological properties of MGS layers during blink-like deformations. Polymer supplementation moderated these adverse effects, yielding partial recovery of film structure and isothermal reversibility. Distinct mechanisms of action for HA, PVP, and CHS at the film/aqueous interface are elucidated. Full article

Efficient fire safety engineering of insulated timber modular blocks requires an integrated assessment of material behavior, compartment fire dynamics, and structural response under thermal exposure. This study presents a performance-based framework that evaluates fire risk in modular timber systems combining combustible wood elements with polymer-based insulation. Key parameters—including ignition delay, heat release rate (HRR), charring rate, and encapsulation integrity—are modeled to quantify fire growth and structural degradation. A hybrid methodology integrating material characterization, compartment fire simulation, and mitigation analysis is applied to assess system performance under varying protection strategies. The results indicate that fire behavior is strongly governed by encapsulation reliability and cavity fire propagation pathways, with unprotected insulation leading to rapid HRR escalation and early flashover conditions. Conversely, the use of multi-layer fire-resistant linings and cavity barriers significantly delays ignition and preserves structural stability. Predictive modeling demonstrates that optimized configurations can achieve fire resistance levels comparable to conventional systems while maintaining modular efficiency. The findings highlight that efficient fire safety in insulated timber modular blocks depends on the coordinated design of materials, interfaces, and protective systems, supporting the adoption of performance-based fire engineering in modern modular construction. Full article

Graphene, with excellent mechanical and self-lubricating properties for polymer modification, can be single- or multi-layered (3–10 layers). In this study, molecular dynamics simulations have been employed to qualitatively explore the relative trends and internal modification mechanism of polyimide (PI) modification by single-layer graphene and three-layer graphene with different sizes. Small-sized single-layer graphene (SSLG), small-sized multi-layer graphene (SMLG), large-sized single-layer graphene (LSLG), and large-sized multi-layer graphene (LMLG) were introduced into the PI matrix at an identical mass fraction with initially uniform dispersion during model construction. The tensile mechanical and frictional behaviors of graphene-modified PI were systematically examined. The results indicate that graphene addition effectively improves both the mechanical and tribological properties of PI. At a fixed filler mass fraction, SSLG exhibits the strongest interaction with PI, with a binding energy of 396.8 kJ/mol. The fractional free volume of SSLG-reinforced PI reaches 15.3%, which is considerably lower than the value calculated for pure PI (20.3%). The average elastic modulus of the SSLG-modified PI is 70.4% higher than that of pure PI, an increase which exceeds that of the SMLG-modified PI (45.2%), LSLG-modified PI (26.5%), and LMLG-modified PI (14.0%). In terms of tribological properties, the SMLG-modified PI exhibits optimal friction with an average friction coefficient of 0.105, which is 48.3% lower than that of pure PI and lower than the values for the SSLG (0.138), LSLG (0.156), and LMLG (0.182) systems. This work mainly draws qualitative structure-property rules and provides key theoretical fundamentals and design principles for tailoring the mechanical and tribological performance of high-performance graphene-reinforced polyimide composites. Full article

Magnesium alloys are used or considered for lightweight structures and biodegradable implants, but high electrochemical activity, limited wear resistance, and localized corrosion still limit their service reliability. Plasma electrolytic oxidation (PEO), also called micro-arc oxidation (MAO), forms an adherent ceramic scaffold. Discharge channels, interconnected pores, thermal cracks, and a mechanically weak outer layer mean that the as-formed coating is rarely a complete protective system. This review examines advanced PEO/MAO-based composite coatings through a process–structure–function lens and develops an application-oriented design framework. The discussion covers PEO/MAO process-window control, electrolyte and particle engineering, sol–gel and polymer sealing, layered double hydroxide/inhibitor systems, self-healing reservoirs, superhydrophobic and slippery interfaces, Ca-P/hydroxyapatite and polymer biofunctionalization, and duplex coatings for wear, electrical, and thermal functions. Emphasis is placed on how these modules regulate defect connectivity, mass transport, interfacial stability, damage response, tribocorrosion, and biodegradation, as well as on the evidence needed to support each claimed function. The analysis indicates that coating performance is governed not by multilayer complexity alone, but by the compatibility among the ceramic scaffold, functional module, dominant failure mode, and service-specific validation protocol. Chloride-exposed structures require durable pore sealing and active inhibition; wear-critical components require coupled corrosion–wear assessment; and biodegradable implants require a degradation window that balances corrosion moderation, cytocompatibility, biofunctionality, and residual mechanical integrity. Remaining challenges include interfacial durability, finite inhibitor reservoirs, wetting-state instability, process reproducibility, scale-up, and life-cycle impacts. The proposed process maps and validation criteria are intended to support modular, testable, and application-specific PEO/MAO surface systems for magnesium alloys. Full article