Search Results (1,742)

Lightweight polymer composites with effective electromagnetic interference (EMI) shielding are of increasing interest for advanced electronic and aerospace applications; however, conventional glass fiber-reinforced polymers (GFRPs) exhibit inherently low electrical conductivity, limiting their shielding performance. In this study, a hierarchical hybrid conductive architecture was developed by integrating graphene-coated multiaxial glass fiber fabrics with carbon black (CB)-reinforced epoxy matrices to enhance EMI shielding behavior in the X-band (8–12 GHz). Graphene coatings were deposited onto glass fibers via a surfactant-assisted ultrasonic dispersion method, while carbon black (0–1 wt.%) was incorporated into the epoxy matrix using ultrasonication-assisted mixing. Multilayer composites were fabricated using a vacuum bagging process. X-ray diffraction analysis revealed that the composites retained a predominantly amorphous epoxy/glass fiber matrix while exhibiting broad carbon-related diffraction features associated with disordered graphitic domains. Electrical conductivity measurements indicated that all composites remained in the insulating regime (~10⁻⁹ S/m), suggesting that a fully interconnected conductive network was not established within the investigated filler range. Despite the absence of a continuous conductive network, measurable EMI shielding performance was achieved. The composite containing 0.25 wt.% CB exhibited the highest shielding effectiveness, reaching approximately 12 dB at ~11.2 GHz. Analysis of the shielding contributions showed that absorption contributions (SEA) were consistently higher than reflection contributions (SER) across the studied frequency range. Morphological observations revealed that well-dispersed CB at low loading facilitated the formation of localized conductive domains that may contribute to tunneling-assisted polarization and interfacial charge accumulation. At higher CB contents, particle agglomeration reduced dispersion quality and limited effective pathway formation, while dynamic mechanical analysis indicated enhanced stiffness at low CB loading. FTIR results confirmed the absence of new chemical bonding, indicating that CB acts as a physically dispersed conductive filler. Overall, the results show that effective EMI shielding can be achieved in electrically insulating composites through the combined effect of hierarchical structural design and localized conductive features. This approach provides a practical pathway for developing lightweight EMI shielding materials with controlled filler loading and preserved structural integrity for aerospace and electronic applications. Full article

Femtosecond laser surface texturing offers a promising route to tailor the functionality of bio-based wood coatings, yet the interplay between coating composition and laser processing remains poorly understood. In this study, bio-based epoxy coatings with eventual micronized wax additives were textured using a femtosecond laser to investigate the effects of laser processing parameters on pattern formation and resulting hydrophobicity. The epoxy coatings containing PE, PE/PTFE, HDPE, and rice bran waxes at 1, 5, and 7 wt.-% were characterized in terms of morphology, roughness, wettability, and chemical stability, followed by systematic variation of pulse repetition rate and laser power. The results reveal that the ablation threshold strongly depends on intrinsic coating properties. Ablation resistance increases with surface roughness and wax melting enthalpy, reflecting the role of phase transition energy in laser–matter interaction. The wax-filled coatings exhibit a transition from melting-dominated behavior at low energy input to ablation-dominated behavior at a higher energy. Laser texturing enhances hydrophobicity in parallel with theoretical values calculated from the Cassie–Baxter wetting model, with the highest hydrophobicity achieved for coatings combining intrinsic hydrophobicity and stable pattern formation. Chemical analysis confirms limited degradation of the epoxy matrix without significant carbonization, while wax additives provide partial thermal shielding. Overall, this work demonstrates clear options for tailoring surface morphology and wettability of hydrophobic polymer coatings through controlled femtosecond laser processing. Full article

The rapid growth in the use of carbon fiber-reinforced polymers (CFRPs) and fused-deposition-modeled (FDM) polylactic acid (PLA) has generated substantial non-biodegradable and thermoplastic waste streams, creating urgent needs for scalable recycling and valorization strategies. This study develops and evaluates an integrated route that chemically recovers carbon fibers (CFs) from CFRP waste and converts them into high-performance reinforcements for recycled PLA matrices. CFRP fragments were pre-swollen in acetic acid (120 °C, 1 h), then depolymerized by means of oxidation with 1 M KMnO₄ (100 °C, 2 h), washed, dried (100 °C, 24 h), and size-reduced by means of cryogenic milling. Recycled CFs (treated) and untreated CFRP fragments were blended with 3D-printing PLA waste at 10, 20 and 30 wt.% via melt mixing (175 °C, 5 min, 70 rpm) and molded into ASTM D638 dog-bone specimens. Materials were characterized via XRD, FTIR, Raman, SEM and mechanical testing. XRD and Raman confirmed retention of the graphitic backbone after treatment; FTIR and Raman revealed oxygen-containing surface functionalization consistent with oxidation, while SEM showed effective removal of epoxy and improved fiber surface cleanliness. Compared with neat PLA (tensile strength 45.4 MPa; modulus 2.6 GPa; elongation 6.3%), composites reinforced with chemically recycled CFs exhibited marked mechanical enhancement: at 30 wt.% treated CF, the tensile strength increased to 102.6 MPa (+126%), elastic modulus to 11.7 GPa (+350%), and toughness to 250.3 MPa, while ductility decreased to 2.9%. Equivalent composites with untreated CFRP exhibited smaller gains (30 wt.%: tensile 87.3 MPa; modulus 10.3 GPa), highlighting the benefit of epoxy removal and surface activation for fiber–matrix adhesion. The proposed chemical recycling pathway is operationally simple and cost-effective, produces reusable CFs with preserved graphitic structure and enhanced surface chemistry, and enables the fabrication of high-performance, waste-derived PLA composites suitable for structural and engineering applications. This work demonstrates a viable waste-to-value approach that advances circularity for both CFRP and 3D-printing polymer waste streams. Full article

Background: Thymoquinone (TQ), a bioactive compound derived from Nigella sativa L., exhibits promising antioxidant, anti-inflammatory, and wound-healing properties; however, its clinical application is limited by poor solubility and instability. Methods: In this study, three electrospun nanofiber systems based on different polymeric matrices, PVP (N1), PVP/HPβCD (N2), and PVP/PCL (N3), were developed as potential wound dressing materials for controlled TQ delivery. Results: All formulations produced uniform nanofibrous structures with TQ molecularly dispersed within the polymer matrix, as confirmed by SEM, XRPD, and FTIR analyses. The composition of the nanofibers significantly influenced their physicochemical and functional properties. The N2 system, containing hydroxypropyl-β-cyclodextrin (HPβCD), exhibited the smallest fiber diameter (~208 nm), the fastest drug release, and enhanced antioxidant and anti-inflammatory activity due to improved TQ solubility. In contrast, the N3 system, incorporating polycaprolactone (PCL), formed thicker fibers (~1089 nm) and demonstrated sustained release behavior, the highest mucoadhesion, and the most pronounced wound-healing effect (90% closure after 24 h). Stability studies revealed that HPβCD significantly improved TQ resistance to thermal, humidity, and photolytic degradation, whereas the PVP-based system without stabilizers showed the lowest stability. Principal component analysis (PCA) confirmed that nanofiber performance is governed by two key factors: drug availability and sustained release combined with bioadhesion. Importantly, wound-healing efficiency correlated more strongly with the latter. Conclusions: The results demonstrate that rational design of polymer composition enables modulation of TQ delivery and biological response. Among the tested systems, PVP/PCL nanofibers appear to be the most promising candidates for wound-dressing applications due to their ability to provide sustained drug release and enhance tissue regeneration. Full article

Polymer-based active packaging systems incorporating natural bioactive agents have attracted growing interest as eco-friendly alternatives to traditional food packaging materials. In this study, Pistacia lentiscus essential oil (PLEO) was incorporated into PCL/gelatin nanofibrous mats fabricated via solution blow spinning (SBS) to develop multifunctional and biodegradable active packaging materials. Neat PCL, gelatin-blended PCL (PCL–G) and PCL–G mats containing 5, 10 and 20 wt.% PLEO were produced and thoroughly analyzed for their morphological, chemical and functional characteristics. Morphological investigation revealed a smooth, bead-free fibrous structure in all samples. The average fiber diameter (AFD) increased from 239 nm to 320 nm with the addition of gelatin to the PCL matrix, while the incorporation of different concentrations of PLEO caused only minor changes. The results showed that as the concentration of PLEO increased, the antioxidant activity of the nanofibrous mats also increased. This enhancement is potentially linked to the rich content of bioactive molecules such as β-pinene, terpineol and verbenol. The 2,2-diphenyl-1-picrylhydrazyl scavenging activity improved from 6.4% (PCL) to 60% (PCL–G–20PLEO), and ABTS activity rose from 8.7% to 72%. In addition, antimicrobial evaluation showed inhibition zones of 12.5 mm against Escherichia coli and 14.2 mm against Staphylococcus aureus for the PCL–G–20PLEO nanofibrous mats. In 14-day storage tests on Kashar cheese, PCL–G–10PLEO and PCL–G–20PLEO mats reduced microbial counts by more than 2 log units compared with the control and effectively slowed yeast and mold growth. These findings confirm the potential of the PCL–G–PLEO nanofibrous mat as novel active packaging materials for preserving dairy products such as Kashar cheese. Full article

Polyhydroxyalkanoates (PHAs) are bio-based, biodegradable polyesters increasingly explored as sustainable biomaterials for regenerative medicine. This review summarizes recent advances in PHA-based bone substitute materials, highlighting their properties, fabrication methods, and biological performance. PHAs combine biocompatibility, tunable mechanical behavior, and degradation into non-toxic metabolites, while copolymerization and monomer selection modulate the stiffness, crystallinity, and resorption rate. Processing techniques such as solvent casting, electrospinning, and additive manufacturing allow the production of porous architectures that mimic bone extracellular matrix. Electrospinning is particularly suitable for nanoscale fibrous matrices, whereas 3D printing enables patient-specific scaffolds with controlled geometry and interconnected porosity. Scaffold performance can be further improved through the incorporation of osteoconductive fillers, including hydroxyapatite, β-tricalcium phosphate, bioactive glasses, graphene oxide, and carbon nanotubes, as well as through drug-delivery and pro-angiogenic functionalization. In vitro and in vivo studies consistently report favorable cytocompatibility, enhanced osteogenic differentiation, vascularization, and effective repair of bone defects in animal models. However, clinical translation remains limited by production costs, variability in polymer quality, thermal processing constraints, and regulatory challenges. Future progress will rely on more efficient biosynthesis, medical-grade purification, multifunctional scaffold design, and stronger collaboration between academia, industry, and clinicians to unlock the full potential of PHAs in regenerative bone therapies. Full article

The amniotic membrane is widely recognized in regenerative medicine due to its rich content of extracellular matrix proteins and growth factors that confer anti-inflammatory and pro-regenerative properties. However, its rapid degradation restricts its standalone clinical use. To overcome these limitations, we developed biofilms by incorporating decellularized human amniotic membrane matrix (dHAM) into polycaprolactone (PCL) and polyvinylpyrrolidone (PVP) matrices using spin-coating. Bone marrow-derived mesenchymal stem cells (BM-MSCs) were used to evaluate film biocompatibility through cell viability, proliferation, and wound healing migration assays. Surface characterization was performed using contact angle measurements, Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, and scanning electron microscopy. Soluble dHAM extracts (4–6 mg/mL) significantly enhanced BM-MSC proliferation at 48 h compared to controls (p ≤ 0.01 and p ≤ 0.0001). Both PCL-dHAM and PVP-dHAM biofilms exhibited high cell viability (>90%) and improved initial adhesion. Notably, dHAM incorporation significantly increased wound closure rates at 24 h, reaching 98.47% for PCL-dHAM and 93.13% for PVP-dHAM, compared to 76.56% and 64.20% for pure polymers (p = 0.0001). All scaffolds maintained hydrophilic surfaces (<90°), favorable for cell interaction. The integration of dHAM into PCL and PVP by spin-coating produces biofilms biocompatible with enhanced regenerative potential, representing promising candidates for wound healing applications. In conclusion, these coatings support BM-MSC adhesion, proliferation, and migration, while significantly accelerating wound closure, underscoring their value as advanced bioactive coatings for regenerative medicine. Full article

The valorization of lignocellulosic residues into bioactive and biodegradable materials offers a sustainable route for functional food packaging. In this study, hazelnut shells were exploited through an integrated process enabling the integrated recovery of polyphenols and cellulose. Polyphenols were extracted via hot water, liquid–liquid partitioning, and column chromatography, yielding a purified bioactive fraction. The residual biomass after polyphenol recovery was used for cellulose extraction (approximately 23% w/w) and converted into carboxymethyl cellulose (CMC) with a degree of substitution (DS) of 0.77. Active CMC films incorporating polyphenolic extracts exhibited improved mechanical performance, reaching tensile strengths of about 78 MPa and elongation at break values above 20%, while reducing water solubility to approximately 31%. The addition of carnauba wax further enhanced water resistance while modulating flexibility and stiffness. Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) analyses confirmed the conversion of crystalline cellulose into amorphous CMC and the successful incorporation of additives within the polymer matrix. The resulting films showed tunable mechanical, optical, and barrier properties, along with UV-blocking and antioxidant activity. These findings demonstrate that hazelnut shell-derived CMC films enriched with polyphenols and carnauba wax represent promising candidates for a sustainable platform for active food packaging applications, supporting a circular waste-to-value approach. Full article

Objectives: To address the critical limitations of current formulations that fail to simultaneously resolve indomethacin’s poor water solubility, susceptibility to gastric acid hydrolysis, and difficulty in balancing rapid onset with long-term sustained release, this study prepared solid dispersions via anti-solvent freeze-drying to improve drug dissolution, constructed oral buccoadhesive bilayer controlled-release tablets using direct powder compression, and elucidated the intrinsic relationships among polymer gel properties, swelling-erosion behavior, tablet integrity maintenance, and drug release mechanisms. Methods: Solid dispersions (SDs) were prepared by anti-solvent freeze-drying. Bilayer tablets (25 mg IND/tablet, 12.5 mg/layer) were fabricated via direct powder compression after optimizing disintegrants and polymer matrices. In vitro dissolution, surface pH, adhesion time, and adhesion strength were evaluated. Results: SDs enhanced dissolution by at least 30-fold in water and 2.4-fold at pH 6.8 within 2 h versus pure drug. Optimized bilayer tablets achieved 45% drug release at 20 min and 80% sustained release over 8 h, with surface pH of 6.8 ± 0.1, adhesion time of 8.3 ± 0.1 h, and adhesion strength of 57 ± 0.13 g. Conclusions: The physicochemical properties of polymeric excipients are critical for balancing drug release and mucoadhesion in buccal tablets. To achieve ideal controlled-release effects, in addition to focusing on the swelling and erosion characteristics of matrix-based tablets, the ability to maintain tablet integrity during dynamic dissolution must be further investigated, which is an essential factor for ensuring precisely modulated drug release. Meanwhile, when employing solid dispersions as solubilizing intermediates to prepare controlled-release formulations, the gelling properties of polymers in each formulation component should be fully considered to avoid incomplete disintegration and insufficient release at the initial dissolution stage. Full article

This work aimed to develop bioactive films based on alginate and κ-carrageenan that were incorporated with different concentrations 0, 0.2, 0.4, 0.8, 1 and 2% (w/v) of cinnamon essential oil (CEO). The films were crosslinked with a solution of calcium chloride obtained from limestone sludge through acid dissolution. The films were characterised according to their physical, mechanical, optical, antioxidant and antimicrobial properties. The best film formulation consisted of 1.5% total carbohydrate concentration, 0.45% glycerol and 0.4% (w/v) of Tween 20. The Fourier transform infrared Spectroscopy analysis confirmed the crosslinking between the polysaccharides and the incorporation of the CEO into the polymer matrix. The addition of the CEO increased the film thickness, reduced moisture content and water vapour permeability, yet it increased solubility, due to matrix disruption invoked by the oil droplets. SEM analysis showed that CEO affected film microstructure, with moderate concentrations leading to more homogeneous structures. In terms of the mechanical properties, CEO incorporation reduced stiffness and yield strength whilst increasing film flexibility, showcasing a plasticising effect. The films were colourless and transparent; moreover, none of the samples exhibited absorbance in the visible region (400–800 nm); however, all films showed absorption in the UV region. The incorporation of the CEO into the films provided antioxidant activity. Particularly, the sample containing 2% CEO had the highest activity, with values of 97.5 ± 0.77% and 75.9 ± 1.82% in the ABTS and DPPH, respectively. Overall, these results suggest that the developed films have promising potential as sustainable food packaging materials with enhanced antioxidant functionality, although further optimisation is needed to improve antimicrobial performance and validate their effectiveness in real food packaging systems. Full article

Dissolving microneedles (DMN) could be considered as a minimally invasive alternative for transdermal delivery of naltrexone hydrochloride (NTX). In the present study, DMN patches with smart design were developed via a two-step micromoulding technique. The systems were composed of drug-free polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) blend microneedle tips, combined with a drug-loaded backing layer based on PVP and Poloxamer 407. The influence of polymer concentration in DMN tips and backing-layer composition on morphology, mechanical properties, drug release and permeation was evaluated. Mechanical studies revealed that intermediate polymer concentration (formulation MN-20%/2:1) provided superior structural integrity (13.57 ± 1.43% height reduction after compression) and efficient penetration up to the fourth Parafilm^® layer. Incorporation of NTX into the backing layer allowed for high drug loading, while a 2:1 PVP:P407 ratio provided higher toughness (1806 g/mm) as well as thermoresponsive and controlled drug release. In vitro permeation studies demonstrated significantly enhanced NTX delivery from DMN systems compared to simple matrix patches—an almost 4-fold increase in flux with 56% permeation of NTX up to 8 h. These findings highlight the importance of polymer composition in DMN design and demonstrate the potential of the developed systems as an effective platform for transdermal delivery of NTX. Full article

Particulate-reinforced polymer composites (PRPCs) are susceptible to cracking under tensile loading, severely limiting their service life. Here, we propose a pressure-gradient-driven infiltration method that rapidly repairs narrow (<10 μm) cracks in a highly filled PRPC (95 wt.% BaSO₄/5 wt.% fluororubber). Microstructural evidence confirms that the adhesive completely fills the tortuous crack and forms a continuous adhesive–matrix interface capable of supporting load transfer. Semi-circular bend (SCB) testing demonstrates a substantially higher peak load and increased apparent structural stiffness after repair under the present semi-circular bend configuration, indicating apparent mechanical enhancement beyond simple load-bearing recovery. Digital image correlation (DIC) and fracture morphology show that repair suppresses notch-tip strain localization, reduces the strain concentration factor, shifts the failure-controlling zone away from the original notch tip, and deflects the crack propagation path. Phase-field simulations further show that the post-repair load-bearing capacity is governed by the adhesive–matrix interfacial strength; once this strength approaches or exceeds the tensile strength of the intact PRPC (~8.3 MPa), the repaired crack path is stabilized, enabling peak-load enhancement while suppressing damage localization along the original crack path and shifting failure to adjacent weaker regions. Overall, this work establishes a promising crack repair approach for highly filled PRPCs, while the underlying interface-controlled mechanism provides guidance for adhesive selection and repair design. Full article

Multilayer packaging—engineered by integrating complementary materials such as plastics, paper, and aluminum—has become a cornerstone technology for enhancing shelf life, minimizing spoilage, and reinforcing the mechanical integrity of packaging formats including films, pouches, and bottles. In this study, a laminate was developed by thermally bonding polylactic acid (PLA) with a poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) matrix embedded with silver nanoparticles (Ag-NPs) at 0–3 wt.%. The resulting structures were systematically evaluated for their barrier performance, physicochemical characteristics, and antimicrobial functionality. Fourier-transform infrared (FTIR) spectroscopy confirmed the absence of chemical interactions between Ag-NPs and the polymer matrix, indicating physical dispersion rather than chemical bonding. However, at higher loading (3 wt.%), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) revealed notable nanoparticle aggregation. Functionally, the multilayer films demonstrated markedly improved water vapor barrier properties compared to single-layer PBAT/TPS films. Migration studies showed that silver release increased with nanoparticle concentration and was significantly enhanced under acidic conditions relative to distilled water. Importantly, Ag-NP-incorporated laminates exhibited pronounced antibacterial activity against Staphylococcus aureus. Collectively, these findings highlight the potential of Ag-NP-enriched, starch-based multilayer laminates as next-generation active packaging systems that combine with effective microbial control. Full article

The sustainable recovery of high-value metals from wastewater has garnered significant attention in light of the circular economy and environmental preservation. Because of its appealing characteristics, membrane separation technology is essential for the sustainable and effective recovery of valuable metals from wastewater, in contrast to conventional methods, which are chemical- or energy-intensive. In this study, a rational design approach was utilized to synthesize a metal–organic framework (MOF) using a deep eutectic solvent (DES) as a mediating medium to control the reaction of framework formation and particle properties. While DESs have been widely used for the physical modification of materials, their role as a chemically modifying medium during MOF synthesis for structural tailoring remains less explored. This synthesized MOF (DM-Zn-PDC@MOF) was further introduced as filler in polysulfone (PSf)-based mixed matrix membranes (MMMs). The performance of DM-Zn-PDC@MOF within the polymer matrix was examined. Several characterization techniques were used to thoroughly analyze the morphological, chemical, and physical characteristics of the MMMs and DM-Zn-PDC@MOF. The addition of the filler material significantly enhanced the membrane characteristics, including pure water flux, hydrophilicity, porosity, surface roughness, pore size, and heavy metal resource recovery in comparison with the pristine membrane. Stable incorporation of the filler within the membrane matrix was indicated by much less filler leaching (<5%) at all concentrations. With DM-Zn-PDC@MOF loading, the pure water flux increasedmore than nine times from 102.8 L/m²h (M-0) to 971.5 L/m²h (M-4). The functionalized membranes showed better flux retention in high-value heavy metal resource recovery using simulated wastewater: 871.8 L/m²h when filtering a Pb(II) ion solution (compared to M-0 with flux 120.6 L/m²h) and 526.8 L/m²h when filtering a Cr(III) ion solution (compared to M-0 with flux 97.1 L/m²h). These values represented approximately 7-fold and 5-fold improvements, respectively. Overall, Pb⁺² > Cr⁺³, but the rejection of Cr(III) ions was also improved, when compared with M-0. The high flux of the membrane makes it easier to process large volumes and concentrate metals in the retentate, turning diluted contaminated streams into a concentrated feedstock for subsequent recovery procedures. Full article

Fibre-reinforced polymer composites incorporating synthetic reinforcements such as glass and carbon fibres are widely used due to their superior mechanical performance. However, their energy-intensive production and end-of-life disposal contribute to an increased carbon footprint and significant environmental burden. Natural fibre-reinforced composites have emerged as promising low impact alternatives, but variability in their mechanical performance and the lack of controlled comparative studies limit their structural application. This study presents a controlled experimental comparison of alkaline-treated unidirectional flax/epoxy and hemp/epoxy composites fabricated using the vacuum-assisted resin infusion moulding (VARIM) process. Alkali treatment was employed to enhance the fibre–matrix interfacial bonding. Mechanical characterization was conducted through tensile, flexural, impact, interlaminar shear strength (ILSS), and Vickers microhardness testing in accordance with relevant ASTM and ISO standards. The flax/epoxy composites exhibited superior in-plane mechanical performance including, 9.1% higher tensile modulus, 13.8% higher flexural strength and 20.5% higher flexural modulus compared to hemp/epoxy composites. A significant improvement was observed in impact performance, with hemp composites showing 87.4% higher impact strength, indicating enhanced resistance to dynamic loading. Conversely, hemp/epoxy composites demonstrated a 10.6% higher ILSS, suggesting improved interfacial shear resistance and fibre interlocking. These findings confirm that the fibre type significantly influences composite performance, with flax fibres providing superior stiffness and strength, while hemp fibres offer better interlaminar shear behaviour and impact strength. Scanning Electron Microscopy (SEM) fractographic analysis was additionally conducted on fracture surfaces to characterize failure mechanisms and fibre–matrix interfacial morphology. The present study provides a reliable comparative framework for material selection and demonstrates the potential of flax- and hemp-based composites as sustainable alternatives for lightweight structural applications. This study supports the development of sustainable composite materials and contributes to the United Nations Sustainable Development Goals (SDGs), particularly SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 11 (Sustainable Cities and Communities). Full article