Search Results (314)

Nanofillers are widely used to enhance the performance of polymer composites; however, their effectiveness strongly depends on their physicochemical properties and dispersion behavior. In this study, five commercially available nanofillers, namely multi-walled carbon nanotubes (CNTs), nanoclay, halloysite, Cloisite^® 30B, and zinc oxide (ZnO), were comprehensively characterized as potential modifiers of unsaturated polyester resin. The results confirm the characteristic chemical composition and crystalline structure of all investigated nanomaterials. CNTs exhibited the highest specific surface area (213.7 m² g⁻¹) and pore volume, whereas ZnO showed the lowest median equivalent particle diameter determined by laser diffraction (D₅₀ = 2.09 μm). The clay-based fillers displayed comparable particle size distributions, with D₅₀ values ranging from 8.29 to 9.00 μm. SEM observations revealed substantial differences in morphology and agglomeration state, with CNTs forming compact entangled agglomerates, while ZnO exhibited the most homogeneous microstructure. Suspension stability analysis demonstrated that particle size alone could not explain the observed sedimentation behavior. ZnO exhibited the highest dispersion stability, whereas halloysite and Cloisite showed progressive sedimentation. Nanoclay displayed delayed destabilization associated with agglomeration processes, while CNT suspensions were governed by structural rearrangements rather than classical sedimentation. The obtained results indicate that the dispersion behavior of nanofillers in unsaturated polyester resin is associated with differences in particle size, morphology, and agglomeration tendency. The presented comparative characterization provides a basis for the rational selection of nanofillers for polyester resin-based nanocomposites. Full article

Carboxymethyl cellulose (CMC)-based solid polymer electrolytes (SPEs) have attracted significant attention as sustainable alternatives to conventional liquid electrolytes due to their biodegradability, non-toxicity, and excellent film-forming capability. However, pristine CMC suffers from inherent limitations, including low ionic conductivity, poor mechanical strength, and limited electrochemical stability. This systematic literature review comprehensively evaluates recent advances in CMC-based SPEs, focusing on the roles of lithium salts (e.g., LiCH₃COO, LiClO₄, LiI, LiBF₄, and LiNO₃) and functional additives, including plasticizers, ionic liquids, nanofillers, and cross-linking agents, in tailoring the physicochemical and electrochemical properties. The findings reveal that ionic conductivity can be significantly enhanced from ~10⁻⁷ to 10⁻² S cm⁻¹ through synergistic modifications that reduce crystallinity and promote segmental mobility. Electrochemical stability is improved by up to ~3.85 V with the incorporation of ionic liquids, while ion transference numbers approaching unity (t⁺ ≈ 0.96) indicate highly efficient Li⁺-dominated transport. Mechanical properties exhibit a trade-off between flexibility (elongation up to ~699%) and tensile strength (up to ~12.84 MPa), depending on the balance between plasticization and cross-linking. The degradation temperature is also strongly influenced by system composition, reaching ~508 °C in ionic liquid-modified systems. Overall, the performance of CMC-based SPEs is governed by the interplay between salt chemistry, polymer structure, and additive functionality. This review highlights key structure–property relationships and identifies critical research gaps, including salt-concentration optimization, long-term stability, and scalability, providing strategic insights for the rational design of high-performance, sustainable polymer electrolytes for next-generation energy storage applications. Full article

Polybenzoxazines (PBz) represent a versatile class of high-performance thermosetting polymers that have attracted significant attention for advanced composite applications due to their unique combination of properties including high glass transition temperatures, low polymerization shrinkage, excellent thermal stability, and molecular design flexibility. This comprehensive review examines the structure–property relationships governing PBz composite performance, from molecular design principles through network formation, composite reinforcement strategies, and ultimate application performance. The review systematically addresses benzoxazine monomer structure and its influence on polymer network architecture, explores the polymerization mechanism, and critically evaluates composite design strategies incorporating carbon-based nanofillers, fiber reinforcements, and hybrid filler systems. Detailed analysis of structure–property relationships reveals how molecular and composite architecture control thermal stability (glass transition temperatures exceeding 350 °C and char yields up to 92%), mechanical performance, electrical properties (dielectric constants as low as 2.67), and chemical durability. Processing techniques ranging from conventional compression molding to emerging additive manufacturing approaches are discussed in the context of morphological control and property optimization. Applications spanning aerospace structures, high-frequency electronics and protective coatings demonstrate the technological relevance of PBz composites. Critical challenges including network brittleness, high cure temperatures, and recyclability limitations are addressed alongside recent advances in dynamic covalent networks, vitrimer chemistry, and self-healing systems that promise to overcome these barriers. This review provides a comprehensive framework for understanding and engineering polybenzoxazine composites for next-generation advanced applications. Full article

Meat and meat products are highly susceptible to microbial spoilage, lipid oxidation, moisture loss, discoloration, and sensory deterioration, creating a need for effective, safe, and sustainable packaging solutions. Although previous studies have investigated biodegradable polymers, nanomaterials, and active packaging systems separately, an integrated assessment connecting material design, preservation mechanisms, safety, sustainability, and commercial feasibility remains limited. This review addresses this gap by critically evaluating recent advances in biodegradable nanocomposite films and coatings for meat preservation. Current evidence demonstrates that the incorporation of nanoscale reinforcements and bioactive agents into biopolymer matrices can enhance their mechanical performance, gas and moisture barrier properties, antimicrobial activity, antioxidant capacity, and controlled release behavior. However, these advantages are strongly influenced by the nanofiller characteristics, concentration, dispersion, polymer-nanofiller interactions, food matrix composition, and storage conditions. Excessive nanomaterial incorporation may promote aggregation, induce structural defects, reduce flexibility, and increase migration concerns. Despite promising preservation outcomes, most available studies remain limited to laboratory-scale investigations, variable testing protocols, and insufficient validation under real commercial conditions. Key challenges hindering industrial adoption include nanoparticle migration, long-term safety assessment, regulatory uncertainty, production costs, consumer acceptance, and limited life-cycle evaluation. Future research should focus on safe-by-design formulations, standardized real-food testing, scalable manufacturing approaches, controlled-release technologies, and integrated assessments of preservation efficiency, safety, economic feasibility, and environmental sustainability. Overall, biodegradable nanocomposite packaging represents a promising approach for extending meat shelf life; however, successful commercialization requires balancing enhanced preservation performance with safety assurance and industrial practicality. Full article

Chewing gum is a frequently neglected polymer-containing consumer product that can be considered a source of microplastic exposure during chewing, and, upon disposal, a cause of surface contamination. This narrative review summarises the composition of the gum base, particle release during mastication, environmental fate, and the emergence of circular upcycling. Modern gum bases can be characterised by water-insoluble elastomeric and resinous phases designed for mechanical durability, as demonstrated by established evidence. Furthermore, a recent experiment has demonstrated the release of detectable microplastic-sized particles into the saliva after chewing. However, quantitative estimates, such as the apparent highest value of 637 MPs g⁻¹, and the observation that the majority of particles detected are released during the first 8 min, remain tentative, given the limited range of products offered and the lack of replication across different brands, formulations, chewing schedules, and analytical tools. Another proof point that samples of natural and synthetic gums have comparable particle discharge indicates that no amount of natural or plastic-free labelling should mean no particle exposure. The adhesive and hydrophobic nature of gum residues, along with observations of microbial colonisation and surface interaction, is also a key factor for their persistence post disposal. Since no standardised gum disintegration protocols exist, outdoor residence times are unknown. Other under-characterisations occur in nano- and ultra-small plastic fractions, as standard spectrometric analyses have size limits. Emerging materials engineering work indicates that sanitised, chewed gum can be reprocessed with conductive nanofillers to serve as flexible sensing agents. These circular paths are proof-of-concept paths at this point, as we must confirm oxidation stability, cleanliness, scalability, logistics, collection, and lifecycles. This study clearly distinguishes well-known polymer and litter issues from new exposure, degradation, and upcycling proposals. Full article

The increasing demand for high-performance and multifunctional polymer materials has driven interest in improving the mechanical properties of polymer components produced through additive manufacturing. This study aims to systematically investigate and comparatively evaluate the effects of low-content nanofiller incorporation on the structural, thermal, and mechanical performance of PLA-based materials produced via fused deposition modeling (FDM), with a focus on identifying filler-dependent behavior under different loading conditions. In this study, polylactic acid (PLA) composites reinforced with 0.5 wt.% graphene (Gr) and 0.5 wt.% silver (Ag) nanoparticles, added separately, were produced using fused deposition modeling (FDM) and comparatively investigated. Each nanofiller was incorporated individually into PLA-based filaments, and standard test specimens were fabricated via 3D printing. Structural, thermal, and mechanical properties were evaluated using tensile, compressive, and three-point bending tests, along with SEM, EDS, XRD, FTIR, DSC, and TGA analyses. The results showed that pure PLA exhibited typical brittle behavior and a single-stage thermal degradation profile. The tensile strength of pure PLA was 41.93 MPa, and the flexural strength was 70.76 MPa. The addition of 0.5 wt.% graphene led to noticeable improvements, particularly in flexural properties, while only a minimal (almost negligible) increase was observed in tensile strength, with tensile strength increasing to 42.24 MPa (+0.74%) and flexural strength increasing to 110.78 MPa (+56.6%). In contrast, 0.5 wt.% Ag exhibited mixed and load-dependent mechanical behavior, with slight improvements in flexural strength but reductions in tensile and compressive properties, where tensile strength decreased to 22.13 MPa (−47.2%) while flexural strength increased to 112.06 MPa (+58.3%). Structural and thermal analyses indicated that both nanofillers did not significantly alter the PLA matrix chemically, while contributing to controlled changes in material properties primarily through physical interactions. The novelty of this work lies in the comparative evaluation of graphene and silver nanoparticle reinforcement at a fixed low loading level within FDM-processed PLA, combined with a comprehensive and correlated analysis of mechanical, structural, and thermal behavior on the same specimen sets, enabling a clearer understanding of filler-dependent performance mechanisms in additively manufactured nanocomposites. Overall, it was concluded that low-rate nanofiller additions, when properly dispersed, may lead to selective improvements in the performance of PLA-based composites depending on filler type and loading mode, and show potential for advanced engineering applications such as lightweight structural components, functional sensors, and additive-manufactured parts requiring tailored mechanical performance and multifunctionality. Full article

Raw lacquer, a natural polymer derived from the bast of lacquer trees (Toxicodendron vernicifluum), is renowned as the “King of Coatings” due to its exceptional film-forming properties, abrasion resistance, corrosion resistance, and biocompatibility. However, its inherent limitations—including stringent drying conditions, slow curing rates, deep coloration, and difficult application—have severely restricted its modernization and widespread adoption. This review systematically summarizes recent research advances in the modification and application of raw lacquer, focusing on four major modification strategies: (1) Nanocomposite modification—incorporating functional nanofillers such as Al₂O₃, cellulose nanofibrils (CNF), polydopamine (PDA) melanin-like nanoparticles, and SiO₂ to significantly enhance film hardness, compactness, UV-aging resistance, and drying kinetics. (2) Chemical structure modification—employing molecular design strategies including aminoanthraquinone grafting, tung oil blending, water-based emulsification, and terpene/allyl group functionalization to improve hydrophobicity, flexibility, fast-drying properties, and achieve dual photo/oxygen curing. (3) Biomass synergistic composites—utilizing natural polymers such as chitosan and lignin, along with bio-inspired adhesion mechanisms (e.g., PDA), to confer advanced functionalities including antibacterial and antifouling properties. (4) Curing behavior regulation—precisely controlling drying kinetics through inorganic salt ion microenvironment engineering, nonionic surfactants, and salicylaldehyde Schiff base-based driers. Building upon these foundations, this review further expands on the emerging high-value applications of modified lacquer in preventive conservation of cultural heritage, advanced functional coatings (anti-corrosion, super-hydrophobicity, flame retardancy), biomedical materials (hemostasis, antibacterial activity, drug-controlled release, water treatment adsorption), and intelligent responsive flexible electronics. Finally, addressing challenges including weak fundamental research, bottlenecks in green industrialization, and lack of standardization, future development directions are proposed encompassing interdisciplinary innovation, sustainable modification strategies, integration of multifunctional intelligent systems, and big data-driven research paradigms, aiming to provide theoretical guidance and technical references for the high-value utilization and modernization of lacquer resources. Full article

Hydrogen energy systems rely extensively on polymeric materials for storage, sealing, transport, and tribological applications; however, their long-term reliability is strongly influenced by hydrogen–polymer interactions. This review presents a comparative analysis of polymers with and without hydrogen bonding, focusing on how molecular architecture governs hydrogen compatibility, transport behavior, and degradation mechanisms under high-pressure environments. Hydrogen-bonded polymers, such as polyamides, polyurethanes (PU), and polyimides, exhibit high mechanical strength and thermal stability due to strong intermolecular interactions but are susceptible to hydrogen-assisted chemical degradation and embrittlement. In contrast, non-hydrogen-bonded polymers, including polyethylene, polypropylene (PP), polytetrafluoroethylene (PTFE), and Polyether ether ketone (PEEK), demonstrate excellent chemical inertness and low hydrogen reactivity, yet experience diffusion-driven damage such as blistering and fatigue softening. This study establishes a unified framework linking molecular structure, hydrogen transport, and failure mechanisms, revealing a fundamental trade-off between mechanical integrity and chemical stability. Advanced strategies, including polymer blending, nanofiller reinforcement, and multilayer composites, are proposed to optimize durability, permeability, and overall hydrogen compatibility. Full article

Conventional epoxy polymers and their composites are increasingly challenged by environmental concerns, high manufacturing costs, and limited recyclability, necessitating the exploration of sustainable alternatives. Many research groups have sought to develop alternate polymers from various renewable resources, such as lignin, polyphenols, natural resins, saccharides, and plant oils. This new type of polymer has led to the emergence of bio-based polymers, which are often used with different reinforcements as bio-based composites. In this review, the synthesis of different bio-epoxy resins is discussed in detail along with their chemical structures. Subsequently, the enhancements in the properties of these bio-composites with the addition of different nanomaterials such as carbonaceous nanofillers (carbon nanotubes, graphene nanoplatelets, graphene oxide, etc.), cellulose-based nanomaterials, inorganic nano-silica (spherical and mesoporous), and nano-clay is explained. Lastly, the properties of these bio-composites and their applications in civil engineering are highlighted. This review has provided a detailed overview of the developments in bio-composites that can be used as a guide for the development of a new class of bio-composites using other alternate resources. Full article

The escalating demand for high-performance dielectric energy storage materials in pulse-power systems and portable electronics calls for polymer film capacitors with high discharged energy density and breakdown strength. Conventional polymers, however, suffer severe performance degradation under concurrent thermal and electrical stress, and existing reinforcement strategies—involving inorganic nanofillers or chemical crosslinking—often compromise flexibility, introduce interfacial defects, or involve complex processing. Herein, we demonstrate that incorporating a rigid mechanically interlocked molecule, specifically an octacationic homo[2]catenane, into a polyimide matrix yields robust, crosslink-like networks through strong [π∙∙∙π] electrostatic interaction between electron-rich aromatic units of polyimide and electron-deficient homo[2]catenane. This supramolecular network simultaneously enhances breakdown strength via densified chain packing and suppresses conduction loss by forming deep electron traps derived from the high electron affinity of homo[2]catenane. The optimized PI–HC⁸⁺ composite achieves a high discharged energy density of 7.86 J/cm³ with an efficiency > 80% and sustains stable performance over 10⁵ charge–discharge cycles at 150 °C. This research establishes mechanically interlocked molecules as a new class of functional fillers for high-performance polymer dielectrics, opening an unexplored avenue in the design of next-generation capacitive energy-storage materials. Full article

The present research article deals with the thermal degradation study of epoxy resins filled with hybrid nanostructured forms of carbon under oxidative conditions. In particular, the formulated polymer composites (denoted as HYB_0.1%_CNTs:GNs and HYB_0.5%_CNTs:GNs, respectively) consist of two kinds of fillers, namely multi-walled carbon nanotubes (CNTs) and graphene nanosheets (GNs), mixed together with two different total mass amounts: 0.1 and 0.5%. In both kinds of nanocomposites, three different CNT:GN mixing ratios were considered (5:1, 1:1, and 1:5, respectively), thus providing a total of six hybrid samples. The thermal behavior of these samples was studied by simultaneous thermogravimetry and differential thermal analysis (TG/DTA) under flowing air, and two processes took place in distinct temperature ranges. In each step, about 50% of mass loss is detected with an exothermic effect in the corresponding DTA curve, with the second one accompanied by an intense heat release. The kinetic analysis of the two-stage oxidative thermal degradation was investigated using a model-free isoconversional approach. A non-Arrhenian behavior of the temperature function k(T) was assumed, and lifetime prediction was estimated at temperatures close to those of the possible applications. Isoconversional analysis shows nearly constant activation energies for all composites except HYB_0.1%_5:1 (from 142 to 96 kJ·mol⁻¹), while lifetime predictions indicate that thermal stability increases with graphene content at 0.1% loading (HYB_0.1%_1:5) and with CNT content at 0.5% loading (HYB_0.5%_5:1), with uncertainties below 7%. Finally, because of the π–π bond interactions between the CNTs and the GNs dispersed in the epoxy resin matrix, an effective and remarkable electrical performance was found and a correlation with both electrical and morphological properties was established. In this regard, Tunneling Atomic Force Microscopy (TUNA) proved to be particularly powerful in allowing the simultaneous mapping of topography and localized conductive networks with exceptional sensitivity to nanofiller dispersion, such as CNTs and GNs. DC conductivity increased by up to nine orders of magnitude at 0.1 wt% hybrid loading (up to 3.73 × 10⁻⁴ S/m vs. 1.06 × 10⁻¹³ S/m for CNT-only), with nanoscale TUNA currents (−1.9 to 4.5 pA) mirroring macroscopic trends, while at 0.5 wt% all hybrids reached 10⁻² S/m, indicating reduced synergy once a fully developed conductive network is established. Full article

In this work, we demonstrate that both carbon nanotubes (CNT) and graphene nanosheets (G) were successfully modified by π-stacking interactions with a pyrene derivative (PY), yielding the functionalized nanofillers CNT-PY and G-PY, which were subsequently dispersed within an aeronautical epoxy matrix. This functionalization is highly effective in preserving the remarkable electronic properties of carbon nanotubes and graphene nanosheets. At the same time, the non-covalent functionalization reduces the resin viscosity, enabling a more effective dispersion of the nanofillers. This results in improved rheological behavior and an overall enhancement of the structural performance of the nanocomposites compared to the resin containing unfunctionalized carbon nanofillers (CNT and G). Additional improvements are also observed in electrical properties, self-healing efficiency, and thermal stability. In particular, the samples containing functionalized carbon nanotubes (TBD + 1%CNT-PY) and functionalized graphene nanosheets (TBD + 1%G-PY) exhibit higher conductivities—0.391 S/m and 0.1 S/m, respectively—than the samples loaded with unfunctionalized carbon nanotubes (TBD + 1%CNT) and unfunctionalized graphene nanosheets (TBD + 1%G), which show conductivity values of 0.292 S/m and 4.82 × 10⁻³ S/m, respectively. The functionalized graphene nanosheets (G-PY) display significantly greater thermal stability, with degradation temperatures reaching 670 °C, compared to 310 °C for unfunctionalized ones (G). The functionalized carbon nanotubes (CNT-PY) show a 10% weight loss at 520 °C due to the degradation of the pyrene groups. Significant improvements in the final properties can be achieved when carbon-based nanofillers are homogeneously dispersed in the matrix and the external load is efficiently transferred through strong filler–polymer interfacial interactions, leading to composites with superior characteristics suitable for advanced applications. Tunneling Atomic Force Microscopy (TUNA) highlights the morphological features of the two types of carbon nanofillers, their dispersion within the polymer matrix and the effect of the functionalization on the electrical pathways and conductivity of the samples at both the micro- and nanometer-scale. The measured electrical conductivities are consistent with the electric currents detected at the micro/nanoscale. Full article

Bio-based, biodegradable, and renewable polymers offer a promising alternative to traditional synthetic polymers derived from petroleum or other non-renewable resources. However, their use is limited by suboptimal properties and high costs. Incorporating sustainable reinforcements into the polymer matrix significantly improves biopolymer performance while preserving key properties, sustainability, and cost-effectiveness. Bio-based polymeric composites have emerged as a crucial category of biopolymers, playing a key role in advancing a sustainable, circular economy. This review provides an updated overview of bio-based polymer composites and nanocomposites, focusing on reinforcement strategies using natural nanofillers and engineered nanoparticles. We summarize key synthesis and processing methods, discuss structure–property relationships, and highlight recent advances in applications such as food packaging, biomedical devices, energy systems, environmental remediation, 3D printing, and supercapacitors. Polymer nanocomposites are versatile, with their performance depending on the type, size, and interactions between the fillers and the polymer matrix. Progress in metallic, ceramic, carbon-based, natural, and hybrid fillers has improved their properties. Using bio-based polymers and renewable fillers supports sustainability. Natural nanofillers derived from renewable sources and industrial byproducts offer a sustainable approach to developing high-performance, biodegradable nanocomposites. Smart nanocomposites can react to external stimuli by integrating specialized fillers that enhance their mechanical and mobility properties. Shape memory nanocomposites can be remotely activated—using heat, electricity, magnets, or light—enabling advanced applications. Finally, we address major challenges and outline future directions for scalable, circular-material solutions, drawing on perspectives from the circular economy and life cycle assessment (LCA). Full article

Advanced thermal management applications, including electronics cooling, battery systems, and micro heat exchangers, are increasingly requiring thermally conductive yet flexible polymer composites. Composite films containing total nanofiller loadings of 2.5, 5, 7.5, and 10 wt.% were systematically characterized using SEM, TGA, DSC, TT, and SSTM following ASTM C177-19. SEM analysis confirmed uniform dispersion and effective network formation of MWCNTs and GNPs within the TPU matrix at higher filler loadings. Thermal stability improved significantly, with the degradation onset temperature increasing from 319.2 °C for pure TPU to 369 °C for the TPU/MWCNT/GNP (90/5/5 wt.%) composite. DSC results revealed enhanced glass transition and melting temperatures, indicating improved thermal resistance and crystallinity. Mechanical testing showed a substantial increase in Young’s modulus, reaching 72.5 MPa for the 90/5/5 wt.% composite, corresponding to a 286.66% improvement over pure TPU. Most notably, steady-state thermal conductivity increased dramatically from 0.20 W/mK for pure TPU to 1.533 W/mK for the 90/5/5 wt.% composite, representing a 666.50% enhancement. The experimental results closely aligned with percolation-based theoretical models at higher filler concentrations. Overall, the developed hybrid nanofiller TPU composites demonstrate a synergistic improvement in thermal conductivity, mechanical strength, and thermal stability, making them promising candidates for flexible thermal management components in electronics, automotive, renewable energy, and biomedical applications. Full article

Polymer nanocomposites offer significant potential for improving the strength-to-weight ratio and dynamic behavior of drone blades. This study examines the vibration characteristics of tapered aramid (Kevlar)/epoxy composite blades reinforced with nanocarbon fillers—graphene (2D), multi-walled carbon nanotubes (MWCNTs, 1D), and fullerene (0D)—to determine the most effective filler for enhancing stiffness and operational stability. The laminated blades (300 mm length, 200 mm width, root thickness 13 mm, tip thickness 8 mm) incorporate ply drop-offs and a central honeycomb core. Modeling was performed using classical laminate plate theory integrated with the finite element method (FEM) in MATLAB (R2016a). Under clamped–free–free–free boundary conditions, the study considered rotational speeds of 750–2250 rpm, setting angles of 30–60°, various fiber orientations, and nanofiller contents of 0–10 wt.%. The results indicate that while the setting angle minimally affects natural frequency, it significantly influences damping in modes (1,2) and (2,1). Increasing nanofiller content improves stiffness, with optimal performance observed near 5 wt.%. At 1500 rpm in mode (1,1), MWCNTs provided the greatest enhancement. Overall, MWCNTs exhibited superior stiffness improvement and rotational stability compared to other fillers. Full article