Search Results (8,556)

Brewer’s spent grain (BSG), the main by-product of the brewing industry, is an abundant lignocellulosic residue that remains underused. In this study, antioxidant-rich extracts were obtained from BSG using pressurized liquid extraction (PLE) and subsequently incorporated into thermoplastic starch (TPS) films for sustainable food packaging applications. The phenolic profile analysis revealed 13 compounds, with caffeic acid and its hexoside as the most abundant. Extraction conditions were optimized using response surface methodology (RSM) to maximize yield and total phenolic content, showing that temperature had a significant positive effect. The selected extract had a total phenolic content of 3.19 mg/g dw and exhibited notable antioxidant activity. It was then incorporated into the polymer matrix, and the resulting films were analyzed for their structural, thermal, and antioxidant properties. The incorporation of BSG extracts improved the film antioxidant activity. Additionally, the release of phenolic compounds was evaluated and successfully described using a diffusion model based on Fick’s law, which allowed the calculation of a diffusion coefficient D = 2.63 × 10⁻⁸ cm²/s. Overall, the findings indicate that BSG-based extracts may represent promising functional additives for biodegradable polymer films, and the developed TPS films serve as proof-of-concept active packaging materials from renewable agro-industrial residues. Full article

In recent years, synergistic effects between inorganic clay minerals (e.g., montmorillonite, sepiolite, kaolinite) and bio-based flame retardants (e.g., chitosan-based, lignin-based, phytate-based) have achieved certain progress in the area of polymer flame retardancy. The effects of bio-based flame retardants are exerted through mechanisms such as catalytic char generation and vapour-phase hindrance. However, they have limitations when used alone, including insufficient thermal stability and the need for a high dosage. Inorganic clays form physical barriers through their layered or tubular structures. The high thermal stability of these structures suppresses heat and mass transfer, thereby offsetting the shortcomings of bio-based flame retardants. This synergistic combination greatly improves the flame retardancy of polymer composites, often strengthening their mechanical performance in the process. It therefore offers great potential for the design of multifunctional, eco-friendly flame-retardant polymer composites. Nevertheless, a systematic review of the synergistic mechanisms, fabrication approaches and application progress of different inorganic clay minerals when combined with various bio-based flame retardants is still lacking. Therefore, this article offers a comprehensive review of the current developments of synergistic systems that incorporate various primary clays, such as sepiolite and montmorillonite, with bio-based flame retardants for usage in polymers. Before this, the synergistic flame-retardant mechanism and the key preparation techniques of the composite system were explained in detail. Finally, this article puts forward solutions to the current challenges and sets out prospects for innovation in the designing of flame-retardant materials and the optimisation of processes. The aim is to promote the sustainable growth of efficient, eco-friendly flame-retardant materials. Full article

The rapid development of additive manufacturing has enabled the production of personalized biomedical devices, including custom orthoses that must retain their structural integrity under demanding physiological conditions. This study evaluates the performance of 3D-printed polymers—blue and white polylactic acid (PLA), Standard Blue Resin, and an ecological soy-based resin—after exposure to simplified, controlled saline environments related to sweat contact and hygiene-associated conditions. Moisture absorption and Shore A hardness were analyzed as response variables to assess material stability under different experimental conditions. A surface methodology based on a Box–Behnken design was used to quantify the effects of specimen thickness (x₁), NaCl concentration (x₂), and immersion time (x₃) on the selected dependent variables. The results indicate that Standard Blue Resin showed the greatest surface hardness stability, whereas the bio-based materials (PLA and ecological resin) were more susceptible to moisture absorption, particularly in thinner polymeric sheets. The fitted quadratic models provide a predictive framework for optimizing material selection and geometric design in biomimetic wearable devices, supporting the development of orthoses with improved durability, hygiene, and long-term functional performance. Full article

Bismuth tungstate (Bi₂WO₆) is a typical bismuth-based visible-light-responsive semiconductor photocatalyst that has attracted significant attention in the fields of environment remediation and energy conversion. In this paper, to address the issues of high photogenerated carrier recombination rate and limited visible-light-response range of Bi₂WO₆, various modification strategies are highlighted, including morphology control, element doping, heterojunction construction, carbon material compositing, and coupling with functional materials such as metal–organic frameworks (MOFs), covalent organic frameworks (COFs), or conductive polymers. Furthermore, the structure–activity relationships are discussed. On this basis, the latest application progress of Bi₂WO₆-based photocatalysts in fields such as pollutant degradation, antibacterial activity, and energy conversion and storage is summarized. Finally, prospects are put forward regarding the existing shortcomings and future development directions in the application of Bi₂WO₆-based photocatalysts, aiming to provide a systematic theoretical reference for the design and application of high-performance Bi₂WO₆-based photocatalysts. Full article

Hybrid conductive materials have attracted increasing attention due to their combined electrical conductivity, mechanical flexibility, and sustainability. In this work, new hybrid materials based on polyaniline (PANI)-wrapped multi-walled carbon nanotubes (MWCNTs) and microfibrous cellulosic substrates were developed and assessed for photocatalytic degradation of a model dye pollutant. First, in situ oxidative polymerization of aniline in formic acid (FA) was conducted in the presence of MWCNTs to afford stable dispersions of carboxylated polyaniline-wrapped carbon nanotubes (c-PANI/MWCNTs). Next, the dispersions were used for affordable impregnation of microfibrous cellulosic filter paper. The influence of the initiator type—potassium peroxodisulfate (KPS) and hydrogen peroxide—on polymer–nanotube interactions, stabilization and surface deposition was emphasized. The structural, surface, morphological and thermal properties of the obtained dispersions and cellulose nanocomposites were systematically investigated using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and thermal gravimetric analysis. The results revealed strong interfacial interactions between c-PANI and the pristine MWCNTs, resulting in improved dispersion stability and effective and even surface deposition of the conductive c-PANI/MWCNT hybrids into the cellulose fiber mesh. The photocatalytic degradation of 5 ppm methylene blue (MB) dye in the presence of the developed nanocomposite materials under UV-A illumination was studied. The results showed that the c-PANI@MWCNT-impregnated cellulose substrates exhibited enhanced photocatalytic ability (up to 83% degree of degradation of MB dye) in comparison with the pure c-PANI. 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

Driven by the growing demand for sustainable polymers, polylactic acid (PLA) has attracted increasing attention due to its renewable origin and biodegradability. Lactide, the key cyclic monomer for PLA production via ring-opening polymerization (ROP), plays a decisive role in determining the molecular weight, stereoregularity, and final performance of PLA materials. However, current lactide synthesis processes still face significant challenges, including competing side reactions under high-temperature and high-vacuum conditions, difficulties in controlling stereochemical purity, and relatively high energy consumption. In this review, recent advances in lactide synthesis are systematically analyzed by examining the two principal industrial routes: the one-step process based on the direct dehydration–cyclization of lactic acid (LA), and the two-step process involving prepolymerization of LA followed by depolymerization/cyclization of oligomeric intermediates. The reaction mechanisms, key intermediates, and major side reactions—including racemization, transesterification, and deep polycondensation—are discussed, together with the regulatory roles of catalytic systems and reaction–separation coupling strategies. Comparative analysis reveals that the one-step route offers advantages in process integration and potential energy efficiency, whereas the two-step route provides superior control over stereochemical purity and process stability. Future research directions focusing on green catalysts, process intensification, and sustainable lactide production are also highlighted. Full article

Mucoadhesive drug delivery systems have emerged as a promising strategy to enhance the therapeutic efficacy of pharmaceuticals by improving drug residence time, bioavailability, and site-specific targeting. Among various materials investigated, biopolysaccharides have gained significant attention due to their biocompatibility, biodegradability, non-toxicity, and inherent mucoadhesive properties. Natural polymers such as chitosan, alginate, pectin, hyaluronic acid, and cellulose derivatives exhibit strong interactions with mucosal surfaces through hydrogen bonding, electrostatic interactions, and polymer chain entanglement. These properties enable prolonged drug retention at mucosal sites, controlled drug release, and enhanced permeation across biological barriers. Mucoadhesive biopolysaccharides have been explored for diverse routes of administration, including oral, buccal, nasal, ocular, vaginal, and pulmonary delivery. Furthermore, chemical modification and nanostructuring of these polymers have expanded their functionality, enabling targeted delivery of small molecules, proteins, peptides, and nucleic acids. This review highlights the mechanisms of mucoadhesion, key biopolysaccharides used in drug delivery, formulation approaches, and recent advances in their application as versatile platforms for novel therapeutic delivery systems. The continued development of mucoadhesive biopolysaccharide-based carriers holds substantial potential for improving treatment outcomes and patient compliance. Full article

Conductive silicone interfaces are promising polymeric materials for wearable bioelectronic systems because they combine electrical continuity with elastomeric compliance, environmental durability, and moldability. In low-voltage wearable microcurrent interfaces, however, functional performance is governed not only by intrinsic material conductivity, but also by conductive network continuity, molded geometry, interfacial contact, and transient electrical response. In this study, we developed a spike-structured conductive silicone interface using a commercially available electrically conductive two-component silicone rubber and investigated its structure–electrical property relationships as a volume-resistive polymer interface. The interface consisted of a conductive silicone body with protrusions 7 mm in height and 3.6 mm in diameter, supported by a 1 mm base layer and electrically integrated through an Ag-paste-connected upper conduction region. Using a representative electrode-level resistance of 47.08 Ω, the geometry-derived apparent interfacial resistive response was estimated as 18.0 Ω·cm for the three-spike configuration and 24.0 Ω·cm for the four-spike configuration. The corresponding effective conductive areas were 0.305 cm² and 0.407 cm², respectively, giving analytical current-density amplification factors of 9.82 and 7.37 relative to a planar 3 cm² reference interface. Positional resistance mapping yielded an overall mean resistance of 47.80 ± 4.57 Ω, indicating acceptable electrical reproducibility across the structured conductive silicone interface. In addition, oscilloscope-based transient response analysis under a 5 V, 1 kHz square-wave input showed that the conductive silicone interface maintained the overall pulse waveform while showing a modest reduction in overshoot from 3.4 ± 0.1% to 2.7 ± 0.1%, with FFT traces used as qualitative waveform-monitoring displays. Formulation-dependent comparison further showed that increasing the silicone-rich fraction increased the measured resistance from 105 Ω to 145 Ω, whereas increasing conductive carbon loading reduced resistance but aggravated surface transfer. These results show that the conductive silicone interface functions not simply as a soft conductor, but as a volume-resistive, geometry-defined current-transfer medium whose behavior is governed by the coupled effects of conductive network formation, spike architecture, electrode-level resistance, and transient pulse response. This study provides a practical materials/interface design framework for spike-structured conductive silicone electrodes in wearable bioelectronic and electroceutical devices. Full article

Existing research on the axial compressive performance and size effect of carbon fiber-reinforced polymer (CFRP)-confined recycled aggregate concrete (RAC) short columns mainly relies on macroscopic experimental analysis, lacking research methods capable of reflecting the heterogeneous characteristics of materials and mesoscopic damage evolution mechanisms. Accordingly, a three-dimensional mesoscale finite element method was adopted in this study to establish a five-phase RAC mesoscopic model, including natural aggregates, old mortar, old interfacial transition zones (ITZs), new mortar, and new interfacial transition zones. Different from existing studies, predominantly based on macroscopic experiments or empirical models, this paper focuses on revealing the coupled effects of the recycled aggregate replacement ratio, the number of CFRP confinement layers, and specimen size. A total of 48 specimens were designed, covering four specimen sizes, four recycled coarse aggregate replacement ratios, and three CFRP confinement layers. The effects of these parameters on failure modes, stress–strain relationships, and size effect were systematically analyzed. The results indicate that the peak stress decreases significantly with the increase in the recycled coarse aggregate replacement ratio; the increase in CFRP layers markedly improves both the bearing capacity and post-peak bearing capacity retention rate; the ultimate stress generally declines as the specimen size increases, which highlights the pronounced size effect of CFRP-confined RAC short columns. Based on peak parameters and normalization analysis, a simplified stress–strain model was established: the goodness of fit R² of the ascending branch is 0.98565, and the goodness of fit for the descending branch parameters are ${\mathrm{R}}_{\mathsf{\beta }}^2$= 0.9655 and ${\mathrm{R}}_{\mathsf{\gamma }}^2$= 0.9350. Compared with existing models, the proposed model achieves a low prediction error of only 1.5–6.9%, demonstrating superior prediction accuracy. It can accurately describe the complete compressive process of CFRP-confined RAC short columns and provide a mesoscopic mechanistic basis for engineering design. Full article

The optimization of Fused Filament Fabrication (FFF) process parameters is commonly performed using room-temperature mechanical properties as the main decision criteria, while the temperature-dependent thermomechanical response of printed polymers is often not explicitly considered. This limitation is relevant for functional components intended to operate above room temperature, where stiffness retention and viscoelastic behavior may strongly affect service performance. This work proposes an experimental–statistical framework for selecting FFF parameters by integrating Design of Experiments (DoE), tensile testing, dynamic mechanical analysis (DMA), Analysis of Variance (ANOVA), the Entropy Weight Method (EWM) and the VIKOR method. Two materials with contrasting thermomechanical behavior were investigated: a high-performance semicrystalline polymer, Z-PEEK, and an elastomeric thermoplastic, TPU 95A. For each material, a DoE was defined to evaluate the influence of key printing parameters, and the manufactured specimens were characterized in terms of maximum tensile force, maximum deformation and storage modulus at selected temperatures. The ANOVA results showed a material-dependent influence of the processing parameters, with thermally driven parameters being especially relevant for Z-PEEK and deposition-related parameters having a stronger influence on TPU 95A. The EWM–VIKOR analysis identified the optimal Z-PEEK configuration as 400 °C extrusion temperature, 200 °C build plate temperature and 150 °C chamber temperature, whereas the optimal TPU 95A configuration corresponded to 225 °C extrusion temperature, 0.10 mm layer height, 50 mm/s printing speed and 80 °C build plate temperature. Overall, the results demonstrate that incorporating DMA-derived thermomechanical indicators into MCDM-based optimization provides a more application-oriented basis for FFF parameter selection than approaches based only on room-temperature mechanical properties. Full article

Additively manufactured cellular architectures frequently exhibit brittle failure under impact due to layer-induced stress concentrations. Through the programming of architectural and material design, specifically combining Fused Deposition Modeling (FDM) lattice topology with hyperelastic polyurea infiltration, this study achieves active control over the macroscopic transition from catastrophic structural fragmentation to stable progressive collapse. To evaluate this, auxetic and honeycomb specimens printed with ABS and glass-fiber-reinforced polyamide (PA-GF) were evaluated in unreinforced and polyurea-infiltrated states under quasi-static compression, three-point bending, and Charpy impact loading. Results show that the compressive response depends primarily on cellular topology; the pure auxetic (A-A) configuration provided the highest stiffness and energy absorption. Polyurea infiltration did not significantly alter elastic stiffness but increased post-yield stability, leading to a 96.6% elastic recovery in PA-GF A-A structures. In flexure, the base polymer governed stiffness, with ABS structures measuring 68% stiffer than PA-GF. Unreinforced ABS achieved 34% higher specific energy absorption (SEA) than PA-GF under compression, with the A-H topology maximizing SEA. Under dynamic impact, PA-GF absorbed an average of 70% more energy than ABS, and the H-A configuration recorded the highest impact resistance. The addition of polyurea shifted the failure mode from brittle fragmentation to stable elastomeric deformation, increasing absorbed impact energy by 52% for ABS and over 30% for PA-GF, preventing catastrophic structural failure. Integrating topological sequencing with elastomeric confinement provides a direct method to control energy dissipation and damage tolerance in 3D-printed cellular composites. Full article

Thermoplastic fiber metal laminates (TFMLs) are lightweight hybrid materials combining metallic layers with fiber-reinforced thermoplastic composites, offering a high strength-to-weight ratio. Existing studies indicate a limited range of polymer matrices used in such structures, most commonly polyamide 6 (PA6). In this work, polybutylene terephthalate (PBT) was selected as a potential alternative matrix because literature data indicate its lower moisture absorption and good dimensional stability compared with PA6. A comparative analysis of TFMLs based on aluminum and carbon fabric-reinforced composites with PA6 and PBT matrices was conducted. Static tensile tests were performed on base materials, composites, and laminates, supported by analytical modeling using the superposition method and fractographic analysis. The results showed that fiber orientation and polymer content significantly affect stiffness, strength, and damage evolution. Fiber orientation remains the governing factor, controlling load transfer and damage initiation. Laminates with 0/90° fibers exhibited the highest strength, while ±45° configurations showed reduced performance due to shear-dominated deformation. The polymer primarily acts as a matrix, ensuring structural integrity, with comparable mechanical properties for both systems. Delamination at the metal–composite interface was identified as the dominant failure mechanism. Full article

The development of multifunctional biomaterials for bone repair requires precursors that combine bioactivity, moderate antimicrobial growth-inhibitory effect, and imaging. This study demonstrates the multifunctional versatility of a single family of rare-earth-doped β-tricalcium phosphates (β-TCPs), Ca₉Eu(PO₄)₇ and Ca₉Dy(PO₄)₇, across three distinct formats: bioactive thin films (for implant coatings), brushite cements (for injectable bone fillers), and radiopaque PMMA bone composites (for load-bearing applications). This work serves as a proof-of-concept that the same doped phosphate precursors can address different clinical needs while retaining bioactivity, antimicrobial properties, and radiopacity. The phosphate precursors were synthesized via solid-state reaction. Pulsed laser deposition (PLD) was used to form amorphous, dense, and crack-free coatings, which exhibited excellent in vitro bioactivity through the rapid dissolution–reprecipitation of a carbonated apatite layer in simulated body fluid. The brushite-based bone cements were produced from doped β-TCPs. These cements demonstrated high cytocompatibility with mesenchymal stromal cells (>89% viability) and significantly enhanced osteogenic differentiation with antimicrobial activity against common pathogens (S. aureus, E. coli, P. aeruginosa). Furthermore, incorporation of these phosphates as fillers into PMMA bone cement resulted in a homogeneous particle distribution with reduced agglomeration compared to undoped β-TCPs, achieving clinically relevant radiopacity values (913 ± 22.4 HU for Dy-doped sample). Post-mortem studies by the CT method were performed on the vertebrae with PMMA–phosphate composites and brushite cements. It was shown that brushite cement in ovine lumbar vertebrae defects exhibited the highest radiopacity (1450–1550 ± 25 HU). The findings establish rare-earth-doped β-TCP as a unified multifunctional precursor that imparts bioactivity, the ability to support in vitro mineralization, antimicrobial properties, and enhanced radiopacity to thin films, phosphate cements, and polymer composite materials. Full article

Designing lightweight composite sandwich structures is challenging due to the conflicting objectives of minimizing structural weight and cost while satisfying strength and stiffness requirements. The optimization procedure becomes more complex when multiple discrete design variables and nonlinear material behavior are involved. This study presents a newly developed optimization methodology for a sandwich structure composed of Fiber Reinforced Polymer (FRP) laminated facesheets and an aluminum honeycomb core. To reduce the computational cost associated with repeated high-fidelity Finite Element (FE) analyses, a surrogate modeling strategy based on Artificial Neural Networks (ANNs) is employed to approximate the structural response. The applied dataset is generated using Monte Carlo simulation in which combinations of design variables are used as inputs, and the corresponding structural responses obtained from the analytical formulation are used as outputs for training the ANN surrogate model. The trained ANN model is integrated with a Multi-Objective Niching Memetic Particle Swarm Optimization (MO-NMPSO) algorithm to simultaneously minimize structural weight and material cost while satisfying constraints on facesheet strength, wrinkling, intra-cell buckling, deflection, core shear failure and structural thickness. The resulting Pareto-optimal solutions are validated through detailed FE simulations, demonstrating the reliability of the newly elaborated optimization framework. The results of the newly developed computationally efficient optimization procedure provide a diverse set of optimal design solutions for the investigated sandwich structure. Full article