Search Results (1,235)

Zeolites are becoming potentially important multifunctional fillers in dentistry, providing a distinctive blend of mechanical reinforcement, remineralization, and antimicrobial properties. Their crystalline aluminosilicate frameworks offer ion-exchange capacity, the controlled release of therapeutic ions (Ag⁺, Zn²⁺, Ca²⁺, Sr²⁺, Cu²⁺), and compatibility with various dental composites. Sustainable and cost-effective zeolite production has become possible due to recent developments in synthetic strategies. These include the valorization of industrial and agricultural residues that are abundant in Si and Al. The incorporation of zeolites into dental adhesives, restorative composites, glass ionomer cements, root canal sealers, prosthetic materials, and implant coatings has been shown to improve mechanical stability and remineralization potential, and enhance antibacterial protection. The unique advantage of zeolites in integrating multifunctionality within a single system is emphasized when compared with other fillers, such as hydroxyapatite nanoparticles and bioactive glass. Nevertheless, obstacles persist with respect to clinical validation, regulatory pathways, and long-term biocompatibility. This review critically assesses the structure–function relationships, synthesis strategies, and dental applications of zeolites, while also delineating future perspectives for their translation into clinically approved, sustainable dental biomaterials. Full article

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

This study investigated Coffee arabica husk (CAH) as a reinforcing filler to create sustainable biocomposites from agro-industrial waste. The research explored the relationship between processing, structure, and properties using two matrices: polylactic acid (LA) and a bio-based epoxy resin (BER). We found that CAH incorporation increased the elastic modulus in all composites, with the stiffening effect being more significant in BER-based systems. However, filler inclusion dramatically reduced composite toughness. Our analysis showed that melt processing significantly reduced the CAH aspect ratio, with BER causing a more pronounced reduction than LA. Conversely, LA showed a greater tendency to fill the porous voids of the CAH particles. This work demonstrates the crucial interaction of filler, matrix, and processing on a composite’s final performance. These materials have shown promises for sustainable packaging and other technical applications. Full article

Octavinyl polyhedral oligomeric silsesquioxane (POSS) can be used to improve the thermal stability of silicone rubber (SR). However, POSS nanoparticles tend to agglomerate in SR matrix, negatively affecting the reinforcement role of POSS for SR, and consequently limiting the practical application of SR/POSS composite. To address the issue, multifunctional POSS (m-POSS) was synthesized via a thiol-ene click reaction and used as a novel heat-resistant filler for SR. The results demonstrate that m-POSS containing both vinyl and siloxane groups was successfully synthesized, with the main product exhibiting a molecular weight of approximately 1587 g mol⁻¹. At the POSS loading of 1.5 phr, SR/m-POSS (100/1.5) composite has much better mechanical properties and thermal stability than SR/POSS (100/1.5) composite. With increasing m-POSS loading from 1.5 to 4.5 phr, the thermal stability of SR/m-POSS becomes better, while the tensile strength decreases. SR composite filled with 1.5 phr m-POSS has an excellent balance in thermal stability and mechanical properties, with a tensile strength of 9.2 MPa and an elongation at break of 587%. To fill multifunctional polyhedral oligomeric silsesquioxane containing vinyl and siloxane groups into SR is an effective approach to producing composites with excellent properties. Full article

This study investigated sawdust-derived activated carbon (SAC) as a sustainable reinforcing filler for vulcanized rubber bushings (VRBs). Two types SAC200 (75 µm, carbonized at 200 °C) and SAC400 (38 µm, carbonized at 400 °C) were chemically activated and incorporated into natural rubber (NR) at 25–55 phr loadings, while SAC free VRBs served as controls. Fourier transform infrared (FTIR) analysis revealed that SAC400 exhibited stronger hydroxyl and carbonyl functional groups, indicating higher surface reactivity compared with SAC200. The incorporation of SAC increased cross-linking density, thereby enhancing both curing behavior and mechanical performance. VRBs reinforced with SAC400 demonstrated higher maximum torque (up to 38.07 kg·cm), shorter scorch time (5 min 58 s), and reduced cure time (11 min 05 s) relative to SAC200 and the control. Mechanical properties improved markedly, with hardness and tensile strength rising from 45 Shore A and 5.52 MPa in the control to 70 Shore A and 13.40 MPa in SAC400. Although elongation at break decreased slightly, it remained within the acceptable range for dynamic applications. Swelling resistance also increased, reaching 101.76% at 25 °C and 106.61% at 100 °C. Overall, SAC400 consistently outperformed SAC200 and the control, highlighting its potential as a renewable, biomass-derived filler for high-performance rubber bushings and promising a sustainable alternative to conventional fillers in industrial applications. Full article

The performance of dental composites is strongly dependent on the type and content of ceramic fillers incorporated into the resin matrix. In this study, the effect of nanosilica (NS) fillers on the curing kinetics, physicochemical, thermal, and mechanical properties of Bis-GMA/TEGDMA-based dental composites was systematically investigated. A series of nanocomposites containing various weight fractions of NS was prepared and evaluated. The photocuring behaviour was analysed using differential scanning calorimetry (DSC), enabling the determination of polymerisation rate coefficients (propagation k_p and bimolecular termination k_t^b) and double bond conversion. The presence of nanosilica was found to influence chain mobility, as evidenced by changes in glass transition temperature (T_g). Rheological measurements provided insight into viscosity changes induced by NS incorporation, while mechanical tests confirmed reinforcement effects. A moderate but statistically significant correlation was observed between the NS content and mechanical performance. The results obtained correlate the rheological, kinetic, thermal, and mechanical properties of multiple types of silica in a single resin system using a consistent methodology. In addition, the results highlight the role of nanosilica in the regulation of the curing dynamics and the increase in the mechanical integrity of methacrylate-based dental composites, representing a promising strategy for the development of next-generation restorative materials. Full article

This study explores the potential of a bio-based thermosetting adhesive system incorporating recycled fillers to enhance structural bonding applications while promoting sustainability. Diglycidylether of vanillyl alcohol (DGEVA) was selected as the resin matrix due to its favorable thermomechanical properties and low moisture absorption. To improve mechanical performance and support circular economy principles, recycled carbon fibers (RCFs) and mineral wool (MW) were integrated into the adhesive formulation in varying proportions (10, 30, and 50 phr). A cationic thermal initiator, ytterbium (III) trifluoromethanesulfonate (YTT), was used to permit polymerization. Comprehensive characterization was performed to assess the curing behavior, thermal stability, and mechanical performance of the adhesive. FTIR spectroscopy monitored the polymerization process, while DSC and dynamic DSC provided insights into reaction kinetics, including activation energy, and curing rates. The mechanical and thermomechanical properties were evaluated using dynamic mechanical thermal analysis (DMTA) and shear lap testing on bonded joints. Additionally, SEM imaging was employed to examine fillers’ morphology and joint interfaces. The results indicated that increasing filler content slowed polymerization and raised activation energy but still permitted high conversion rates. Both RCF- and MW-containing formulations exhibited improved stiffness and adhesion strength, particularly in CMC joints. These findings suggest that DGEVA-based adhesives reinforced with recycled fillers offer a viable and sustainable alternative for structural bonding, contributing to waste valorization and green material development in engineering applications. Full article

This study reports the development of fully biodegradable biocomposites based on polylactic acid (PLA) and polyhydroxybutyrate (PHB) reinforced with alkaline-treated hemp fibers and granules. The thermal, mechanical, dynamic mechanical, and rheological properties of the composites were investigated to assess the influence of reinforcement morphology and content. Differential scanning calorimetry (DSC) confirmed that hemp fibers acted as more effective nucleating agents than granules, increasing the degree of crystallinity of the PLA/PHB blend. Thermal conductivity analysis revealed that hemp incorporation does not systematically improve heat transfer: while long fibers slightly enhanced conductivity, several granule-based composites exhibited lower values than the neat blend. Tensile testing showed that all reinforced samples had lower tensile strength than the neat PLA/PHB matrix, although stiffness was increased, particularly for fiber-based composites. In contrast, flexural strength was maximized in granule-reinforced systems, notably PLA/PHB-2–10-G and PLA/PHB-0.5–10-G, while fibers preserved or improved ductility. Dynamic mechanical analysis confirmed the viscoelastic nature of all composites, with reduced tan δ compared to the neat blend. Rheological testing demonstrated that most composites exhibited lower G′ and complex viscosity than the neat PLA/PHB blend, except for PLA/PHB-2–10-G, which showed stronger matrix–filler interactions. Overall, the results highlight that the performance of PLA/PHB/hemp biocomposites is formulation-dependent, and the selection of hemp morphology and content is crucial for tailoring properties to specific applications. Full article

The risk of explosive spalling in high-strength cement-based materials during fire exposure poses a significant threat to structural integrity. To help mitigate this issue, this study explores the use of expanded polystyrene (EPS) beads as both a lightweight filler and a potential spalling-reduction agent in lightweight geopolymer and conventional cementitious mortars. Two EPS-containing mortars were developed: a lightweight alkali-activated slag (LWAS) mortar and a conventional lightweight Portland cement (LWPC) mortar, both incorporating EPS beads as a 50% volumetric replacement for sand. Specimens from both mortars were subjected to elevated temperatures of 200 °C, 400 °C, and 600 °C at a heating rate of 10 °C/min to simulate a rapid-fire scenario. Following thermal exposure, two cooling regimes were employed: gradual cooling within the furnace and rapid cooling by water immersion. Mechanical performance was evaluated through compressive, splitting tensile, and impact tests at room and elevated temperatures. Microstructural analysis was also conducted to examine internal changes and heat-induced damage. The results indicated that LWAS showed remarkable resistance to spalling, remaining intact up to 600 °C due to its nanoporous geopolymer structure, which allowed controlled steam release, while LWPC failed explosively at 550 °C despite EPS pores. At 400 °C, EPS beads enhanced thermal insulation in LWAS, lowering internal temperature by over 100 °C, but increased porosity led to faster strength loss. Both mortars gained strength at 200 °C from continued curing, yet LWAS retained strength better at high temperatures than LWPC. Microscopy revealed that EPS created beneficial fine cracks in the slag matrix but harmful voids in cement. Overall, LWAS composites offer excellent spalling resistance for fire-prone environments, though reinforcement is recommended to mitigate strength loss. Full article

The widespread replacement of cellulose paper with polypropylene (PP)-based synthetic paper has been hindered by the relatively low stiffness and modulus of PP. Conventional approaches that incorporate rigid inorganic fillers can enhance the modulus but typically compromise processability and mechanical performance. In this work, we propose a dual strategy by introducing high-modulus organic hydrogenated resin fillers (C9) and applying a biaxial stretching force field. The biaxial stretching process not only promotes PP crystallization but also significantly improves the uniform dispersion of C9 fillers. As a result, a composite paper with ultrafine C9 dispersion and a crystalline self-reinforced structure was successfully fabricated. The composite exhibits a modulus that is 38% higher than that of biaxially stretched neat PP and 218% higher than that of unstretched neat PP. Furthermore, under biaxial stretching, the C9 fillers impart a toughening effect, effectively overcoming the conventional stiffness–toughness trade-off. This work therefore provides a promising strategy for the scalable fabrication of high-performance PP-based synthetic paper. Full article

High-density polyethylene (HDPE) is a valuable material, but its application under certain operational conditions is limited by oxidation resistance. To mitigate this, rice husk ash (RHA), a silica-rich (~95%) byproduct, was incorporated as a reinforcing filler. This study evaluates the effect of electron beam (EB) irradiation, at doses up to 100 kGy, on the properties of HDPE/RHA composites, focusing on mechanical performance and the polymer–filler interface. The results demonstrate that EB irradiation induces crosslinking and enhances interfacial interaction between the HDPE matrix and RHA filler. While the overall tensile strength of neat HDPE tended to decrease with irradiation dose (from 28.5 ± 1.2 MPa to 24.1 ± 1.5 MPa at 100 kGy), the optimization of dose and filler contents produced notable results: A maximum tensile strength of 29.0 ± 1.1 MPa was achieved in the composite containing 5 wt% RHA at 75 kGy. Furthermore, irradiation stabilized the material’s behavior, resolving the heterogeneous dispersion observed in non-irradiated samples with low RHA content. Regarding toughness, Izod’s impact resistance increased from 3.2 ± 0.2 kJ/m² to 3.7 ± 0.3 kJ/m² for the 10 wt% RHA composites irradiated at 50 kGy. Statistical analysis (ANOVA, p < 0.05) confirmed the significance of these changes. In conclusion, electron beam irradiation is an effective tool for optimizing the mechanical properties and performance uniformity of HDPE/RHA composites, making them promising candidates for applications requiring enhanced durability and consistency, such as food packaging. Full article

In the field of water treatment, the development of efficient and environmentally friendly antibacterial materials to combat pathogenic contamination is of great significance. This work aimed to synthesize copper nanoparticles (CuNPs) using Rosa roxburghii extract (RRT) and Trichoderma harzianum mycelia-free cell filtrate (MFCF) as reducing agents. It was found that RRT-CuNPs had higher antibacterial ability than MFCF-CuNPs. Therefore, RRT-CuNPs were selected for further study. Through a functionalization modification strategy, polyvinyl alcohol (PVA) and chitosan (CTS) served as carrier matrices, with RRT-CuNPs as the highly efficient antibacterial active component and montmorillonite (MMT) as a reinforcing filler. The CTS/PVA/MMT/RRT-CuNPs composite gel beads were successfully fabricated via a cross-linking and blending method. For RRT-CuNPs-based gel beads, Fourier transform infrared spectroscopy (FTIR) displays that the composite hydrogel particles contain characteristic peaks of PVA, CTS, and MMT. By comparison, it is confirmed that MMT acts as both a reinforcing agent and a molecular structure regulator through interfacial interactions. X-ray diffraction (XRD) shows that MMT and CuNPs are dispersed in the particles. The study illustrates that the optimal initial concentrations of MMT, CTS, and CuNPs added to RRT-CuNPs-based composite gel beads were 4, 30, and 0.5 g/L, respectively. The prepared composite gel beads exhibited significant inhibitory activity towards Gram–positive bacteria (S. aureus) and Gram–negative bacteria (P. aeruginosa and E. coli), acquiring inhibition zone diameters of nearly 21 mm. As the dose of gel beads was 0.3 g/L and the action time was four h, the inhibition rate reached 100% through the plate counting method analysis. In conclusion, RRT-CuNPs-based composite gel beads have excellent antimicrobial activity, showing high potential application in the fields of water treatment. Full article

In this work, polylactic acid (PLA)/poly(butylene adipate-coterephthalate) (PBAT) composites containing nanomagnetite particles were developed for electromagnetic shielding. The nanomagnetite particles acted not only as a conductive filler but also as a reinforced agent and compatibilizer for PLA/PBAT blends. The effect of surface treatments by the silicon coupling agent (SCA) under different pH conditions and with other substances (silica and dopamine (DA)) were investigated in particular. The composites were prepared by thermal mixing and characterized by Fourier-transform infrared spectroscopy (FTRI), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transparency electron microscopy (TEM) and tensile testing. The results show that the interface between the PBAT spheres and the PLA matrix was improved after the addition of magnetite particles treated with SCA or PDA. It is interesting to find that under acidic conditions, SCA acted more efficiently due to the chemical reaction of SCA with the hydroxyl groups on the surface of the magnetite particles, which resulted in chemical improvement. Tensile strength increased about 20%, while elongation also increased about 15%. The fracture surface under SEM clearly showed plastic deformation, which contributed to an improvement in mechanical properties, especially toughness. Full article

Natural fibers have been widely used for reinforcing polymers, attributed to their sustainable nature, light weight, biodegradability, and low cost compared with synthetic fibers, for example, carbon or glass fibers. The objective of this research was to promote the use of natural resource-blended polypropylene (PP) to reduce greenhouse gas emissions and to explore the potential of using grain by-products, such as coconut shell (CS), as fillers for thermoplastic materials. CS (30 wt%) is embedded in the PP matrix of the composite. Thereafter, CS/PP composites were produced utilizing a hot press compounding machine to produce the specimens and a high-speed mixer set at 3000 rpm for five minutes. The impact of coconut shell content on the mechanical and thermal properties of CS/PP composites was examined. The results show the CS/PP composite’s tensile strength and tensile modulus improved by 36% and 30%, respectively. In the meantime, the CS/PP composite’s flexural strength and flexural modulus increased by 16% and 13%, respectively. At a maximum temperature of 260 °C, the CS/PP composite demonstrated thermal stability. Due to the unprocessed particles, the coconut fiber appeared on the surface as homogenous particles. Researchers and industry professionals can use these results to help create new products. Full article

Fiber-reinforced polymer composites (FRPCs) have gained increasing attention as lightweight structural materials with tailored mechanical, thermal, and functional properties for diverse engineering applications. However, achieving optimal performance requires overcoming challenges such as poor interfacial bonding, high density of conventional fillers, and limitations in multifunctionality. Hollow Glass Microspheres (HGMs), owing to their unique spherical morphology, low density, high strength-to-weight ratio, and tunable physical–chemical characteristics, have emerged as promising functional fillers for FRPCs. This review provides a comprehensive overview of the structural features, chemical composition, and synthesis techniques of HGMs, followed by an outline of FRPCs systems with emphasis on matrix and fiber types, their functional requirements, and the critical role of fillers. The discussion highlights how HGMs influence the mechanical (tensile, flexural and compression strength) properties, thermal (conductivity and insulation) properties, acoustic (sound absorption and transmission) properties, and dielectric performance of FRPCs, enabling weight reduction, improved insulation, and multifunctional capabilities. Reported studies demonstrate that when properly dispersed with an optimal amount, HGMs significantly enhance mechanical properties, thermal stability, and acoustic damping, while maintaining processability. Despite these advantages, challenges remain regarding interfacial adhesion (agglomeration) and filler dispersion. The review concludes by emphasizing the need for advanced surface modification strategies, hybrid filler systems, and sustainable processing methods to fully exploit HGMs in next-generation high-performance FRPCs. Full article