Search Results (283)

Tidal seashell waste represents an abundant, underutilized marine resource that poses environmental disposal challenges but offers potential as a sustainable bio-filler in epoxy composites. This study investigates its incorporation into bio-based epoxy systems to reduce reliance on non-renewable materials and promote circular economy objectives. Processed seashell powder was blended into epoxy formulations, and response surface methodology was applied to optimize filler loading and resin composition. Comprehensive characterization included tensile strength, impact resistance, hardness, density, and thermal conductivity testing, along with microscopy analysis to evaluate filler dispersion and interfacial bonding. The optimized composites demonstrated improved hardness, density, and thermal stability while maintaining acceptable tensile and impact strength. Microscopy confirmed uniform filler distribution at optimal loadings but revealed agglomeration and void formation at higher contents, which can reduce interfacial bonding efficiency. These findings highlight the feasibility of valorizing marine waste as a reinforcing filler in sustainable composite production, supporting environmental goals and offering a scalable approach for the development of durable, lightweight materials suitable for structural, coating, and industrial applications. Full article

Asphalt pavement cracking is an important factor affecting its service life. Under certain conditions, the self-healing behavior of asphalt itself can repair pavement cracks. However, the self-healing ability of asphalt itself is limited. In order to strengthen the self-healing ability of asphalt, the microcapsule wrapped with a repair agent is pre-mixed into the asphalt mixture. When the crack occurs and spreads to the surface of the microcapsule, the microcapsule ruptures and the healing agent flows out to realize the self-healing of the crack. Current microcapsules are mostly prepared with healing agents and bio-oil as core materials, and their high-temperature resistance to rutting is poor. While the epoxy resin contains a three-membered cyclic ether, it can undergo ring-opening polymerization to bond and repair the asphalt matrix. In addition, research on microcapsules mainly focuses on the self-healing properties of microcapsule-modified asphalt. In fact, before adding microcapsules to asphalt to improve its self-healing performance, it is necessary to ensure that the asphalt has a good road performance. On this basis, the self-healing performance of asphalt is improved, thereby extending the service life of asphalt pavement. Therefore, two-component epoxy self-healing microcapsules (E-mic and G-mic) were first prepared in this paper. Then, a temperature scanning test, rheological test of bending beams, and linear amplitude scanning test were, respectively, conducted for the microcapsule/asphalt to evaluate its road performance, including the high-temperature performance, low-temperature crack resistance, and fatigue performance. Finally, the self-healing performance of microcapsules/asphalt was tested. The results showed that the self-developed epoxy self-healing microcapsules were well encapsulated and presented as spherical micron-sized particles. The average particle size of the E-mic was approximately 23.582 μm, while the average particle size of the G-mic was approximately 22.440 μm, exhibiting a good normal distribution. In addition, they can remain intact and unbroken under high-temperature conditions. The results of road performance tests indicated that the microcapsule/asphalt mixture exhibits an excellent high-temperature resistance to permanent deformation, low-temperature crack resistance, and fatigue resistance. The self-healing test demonstrated that the microcapsule/asphalt exhibited an excellent self-healing performance. When the microcapsule content was 4%, the self-healing rate reached its optimal level of 67.8%, which was 149.2% higher than that of the base asphalt. Full article

This study investigates the effect of the surface functionalization of tungsten disulfide (WS₂) nanoparticles with aminoacetic acid (glycine) on the structure, curing behavior, and mechanical performance of epoxy nanocomposites. Aminoacetic acid, as a non-toxic, bio-based modifier, enables a sustainable approach to producing more efficient nanofillers. Functionalization, as confirmed by FTIR, EDS, and XRD analyses, led to elevated surface polarity and greater chemical affinity between WS₂ and the epoxy matrix, thereby promoting uniform nanoparticle dispersion. The strengthened interfacial bonding resulted in a notable decrease in the curing onset temperature—from 51 °C (for pristine WS₂) to 43 °C—accompanied by an increase in polymerization enthalpy from 566 J/g to 639 J/g, which reflects more extensive crosslinking. The SEM examination of fracture surfaces revealed tortuous crack paths and localized plastic deformation zones, indicating superior fracture resistance. Mechanical testing showed marked improvements in flexural and tensile strength, modulus, and impact toughness at the optimal WS₂ loading of 0.5 phr and a 7.5 wt% aminoacetic acid concentration. The surface-modified WS₂ nanoparticles, which perform dual functions, not only reinforce interfacial adhesion and structural uniformity but also accelerate the curing process through chemical interaction with epoxy groups. These findings support the development of high-performance, environmentally sustainable epoxy nanocomposites utilizing amino acid-modified 2D nanofillers. Full article

This study presents a multi-modal investigation into the wear behavior of bio-based epoxy composites reinforced with multi-walled carbon nanotubes (MWCNTs) at 0–0.75 wt%. A Taguchi L16 orthogonal array was employed to systematically assess the influence of MWCNT content, load (20–50 N), and sliding speed (1–2.5 m/s) on wear rate (WR), coefficient of friction (COF), and surface roughness (Ra). Statistical analysis revealed that MWCNT content contributed up to 85.35% to wear reduction, with 0.5 wt% identified as the optimal reinforcement level, achieving the lowest WR (3.1 mm³/N·m) and Ra (0.7 µm). Complementary morphological characterization via SEM and AFM confirmed microstructural improvements at optimal loading and identified degradation features (ploughing, agglomeration) at 0 wt% and 0.75 wt%. Regression models (R² > 0.95) effectively captured the nonlinear wear response, while a Random Forest model trained on GLCM-derived image features (e.g., correlation, entropy) yielded WR prediction accuracy of R² ≈ 0.93. Key image-based predictors were found to correlate strongly with measured tribological metrics, validating the integration of surface texture analysis into predictive modeling. This integrated framework combining experimental design, mathematical modeling, and image-based machine learning offers a robust pathway for designing high-performance, sustainable nanocomposites with data-driven diagnostics for wear prediction. Full article

The composite materials industry is increasingly seeking sustainable alternatives to mitigate the environmental impact of end-of-life materials. As a result, many sectors are transitioning toward bio-based or partially bio-based matrices (e.g., epoxy resins) to preserve material properties while improving sustainability. The transportation sector, in particular, demands materials that meet stringent mechanical and fire resistance standards. In this study, various epoxy systems with bio-based and/or recyclable content were investigated, along with renewable additives designed to enhance fire resistance through their functional groups and chemical structure. The research focused on developing formulations compatible with Sheet Moulding Compound (SMC) technology, which is widely used in transportation applications. Through extensive testing, materials with high bio-based content were successfully developed, exhibiting competitive mechanical properties and compliance with key fire safety requirements of the railway sector, as per the EN 45545-2 standard. Full article

There has been a growing interest in polymer-based materials in recent years, and current research is focused on reducing fossil-derived epoxy compounds. This review examines the potential of epoxidised vegetable oils (EVOs) as sustainable alternatives to these systems. Epoxidation processes have been systematically analysed and their influence on chemical, thermal, and mechanical properties has been assessed. Results indicate that basic, low-toxicity epoxidation methods resulted in resins with comparable performance to those obtained through more complex common/commercial procedures. In total, 5–7% oxirane oxygen content (OOC) was found to be optimal to achieve a balanced crosslink density, thus enhancing tensile strength. Furthermore, mechanical properties have been insufficiently studied, as less than half of the studies were conducted at least tensile or flexural strength. Reinforcement strategies were also explored, with nano-reinforcing carbon nanotubes (CBNTs) showing the best mechanical and thermal results. Natural fibres reported better mechanical performance when mixed with EVOs than conventional systems. On the other hand, one of the main constraints observed is the lack of consistency in reporting key chemical and mechanical parameters across studies. Environmental properties and end-of-life use are significant challenges to be addressed in future studies, as there remains a significant gap in understanding the end-of-life of these materials. Future research should focus on the exploration of eco-friendly epoxidation reagents and standardise protocols to compare and measure oil properties before and after being epoxidised. Full article

The increasing demand for sustainable materials has intensified the interest in natural fiber-reinforced composites (NFRCs) as environmentally friendly alternatives to synthetic composites. However, NFRCs often face limitations in thermal stability, restricting their use in high-temperature environments. To address this, the present study explores the hybridization of cellulosic flax fibers with protein-based wool fibers to improve thermal stability without compromising mechanical integrity. Wool–flax hybrid composites were fabricated using a bio-based epoxy resin through a resin infusion technique with different fiber proportions. The flexural properties of these composites were evaluated under varying temperature conditions to assess the influence of fiber composition and thermal conditions. This study specifically examined the impact of wool fiber content on the flexural performance of the composites under thermal conditions, including behavior near and above the matrix’s glass transition temperature. The results showed that the flexural properties of the hybrid biocomposites were significantly affected by temperature. Compared with specimens tested at room temperature, the flexural modulus of all variants decreased by 85–94%, while the flexural strength declined by 79–85% at 120 °C, depending on the variant. The composite variant with a higher wool content (variant 3W) exhibited enhanced flexural performance, demonstrating an average of 15% greater flexural strength than other variants at 60 °C and 5% higher at 120 °C. These findings suggest that incorporating wool fibers into flax-based composites can effectively improve thermal stability while maintaining flexural properties, supporting the development of sustainable biocomposites for structural applications. Full article

The dependence of conventional epoxy resins on fossil fuels and the environmental and health hazards associated with bisphenol A (BPA) demand the creation of sustainable alternatives. Because lignin is a natural resource and has an aromatic ring skeleton structure, it could be used as an alternative to fossil fuels. This study effectively resolved this challenge by utilizing a sustainable one-step epoxidation process to transform lignin into a bio-based epoxy resin. The results verified the successful synthesis of epoxidized bamboo lignin through systematic characterization employing Fourier transform infrared spectroscopy, hydrogen spectroscopy/two-dimensional heteronuclear single-quantum coherent nuclear magnetic resonance, quantitative phosphorus spectroscopy, and gel permeation chromatography. Lignin-based epoxy resins had an epoxy equivalent value of 350–400 g/mol and a weight-average molecular weight of 4853 g/mol. Studies on the curing kinetics revealed that polyetheramine (PEA-230) demonstrated the lowest apparent activation energy (46.2 kJ/mol), signifying its enhanced curing efficiency and potential for energy conservation. Mechanical testing indicated that the PEA-230 cured network demonstrated the maximum tensile strength (>25 MPa), whereas high-molecular-weight polyetheramine (PEA-2000) imparted enhanced elongation to the material. Lignin-based epoxy resins demonstrated superior heat stability. This study demonstrates the conversion of bamboo lignin into bio-based epoxy resins using a simple, environmentally friendly synthesis process, demonstrating the potential to reduce fossil resource use, efficiently use waste, develop sustainable thermosetting materials, and promote a circular bioeconomy. Full article

In the pursuit of environmental sustainability, reduced emissions, and alignment with circular economy principles, bio-epoxy resin nanocomposites have emerged as a promising alternative to traditional petroleum-based resins. This study investigates the development of novel bio-epoxy nanocomposites incorporating iron-oxide nanoparticles (Fe₂O₃, MnP) as multifunctional fillers at loadings of 0.5 wt.% and 3.0 wt.%. MnP nanoparticles were synthesized and subsequently functionalized with citric acid (MnP-CA) to enhance their surface properties. Comprehensive characterization of MnP and MnP-CA was performed using X-ray diffraction (XRD) to determine the crystalline structure, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), and zeta potential measurements to confirm surface functionalization. The bio-epoxy resins matrix (bio-EP), optimized for compatibility with MnP and MnP-CA, was thoroughly analyzed in terms of chemical structure, thermal stability, curing behavior, dynamic–mechanical properties, and surface characteristics. Non-isothermal differential scanning calorimetry (DSC) was employed to evaluate the curing kinetics of both the neat (bio-EP) and the MnP/MnP-CA-reinforced composites, offering insights into the influence of nanoparticle functionalization on the resin system. Surface zeta potential measurements further elucidated the effect of filler content on the surface charge and hydrophilicity. Magnetic characterization revealed superparamagnetic behavior in all MnP- and MnP-CA-reinforced (bio-EP) composites. This research provides a foundational framework for the design of green bio-epoxy nanocomposites, demonstrating their potential as environmentally friendly materials and representing an emerging class of sustainable alternatives. The results underscore the viability of bio-epoxy systems as a transformative solution for advancing sustainable resin technologies across eco-conscious industries. Full article

The growing demand for sustainable materials has driven interest in natural fiber-reinforced composites as eco-friendly alternatives to synthetic materials. This research investigates the fabrication and mechanical performance of hemp and sisal fiber-reinforced composites, with a focus on improving fiber–matrix bonding through alkali and fungal treatments. Experimental results show that fungal treatment significantly improves tensile and flexural strength, while hardness slightly decreases. Water absorption tests revealed moderate reductions in hydrophilicity compared to untreated samples, although absolute water uptake remains higher than conventional glass/epoxy composites. Microscopy analysis further confirmed enhanced fiber adhesion and structural integrity in treated specimens. These findings suggest that hybrid composites reinforced with hemp and sisal, particularly with fungal treatment, hold promise for low-to-medium load sustainable applications in the automotive interiors, packaging, and construction industries, where moderate mechanical performance and partial biodegradability are acceptable. This research contributes to the advancement of bio-based composite materials while acknowledging current limitations in long-term durability and complete biodegradability. Full article

Hot-pressing densification is an effective method to enhance the mechanical properties of wood; however, excessively high pressing temperatures can cause thermal degradation of wood components, compromising these improvements. In this study, aminated lignin (AL), with improved water solubility and reactive amino groups facilitating crosslinking, was utilized as a bio-based amine curing agent for the water-soluble, low-molecular-weight epoxy compound polyethylene glycol diglycidyl ether (PEGDGE). The PEGDGE-AL modifier was applied for wood impregnation, followed by hot-pressing densification at a relatively low temperature of 120 °C, to enhance the mechanical properties of wood. The chemical composition of AL was analyzed using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and X-ray photoelectron spectroscopy (XPS). The gelation and curing behavior of the PEGDGE-AL modifier demonstrated its ability to readily form a network structure at both room temperature and elevated temperatures. The impact strength of densified wood (DW) modified with 12 wt% PEGDGE and 8 wt% AL, denoted as 12PEGDGE+8AL-DW, exhibited an impact strength of 15.2 kJ/m², representing a 72% increase compared to untreated wood (UW). The modulus of rupture (MOR) and modulus of elasticity (MOE) reached 241.1 MPa and 14.6 GPa, respectively, corresponding to 60% and 75% improvements over UW. Furthermore, the 24 h water uptake and thickness swelling of 12PEGDGE+8AL-DW were 45.2% and 24.7%, which were 11% and 43% lower than those of water-impregnated and hot-pressed densified wood (W-DW), respectively. This study provides a low-temperature route for wood densification while contributing to the valorization of lignin in high-performance material applications. Full article

The use of natural fibers in hydro turbine rotors promotes sustainability by offering biodegradable, renewable materials with a lower carbon footprint. This study compares the hydrodynamic performance of two rotors in a gravitational vortex turbine: Rotor 1, 3D-printed with polylactic acid (PLA), and Rotor 2, made from fique fiber and epoxy resin using manual molding. To compare the rotors, experimental tests were conducted on a laboratory-scale setup, where the behavior of both rotors was evaluated under different flow regimes. Rotor 1 achieved 61.01% efficiency at an angular velocity ($\omega$) 160 RPM, while Rotor 2 reached only 19.03% at $\omega$ of 165 RPM. The lower performance of Rotor 2 was due to dynamic imbalances and mechanical vibrations, leading to energy losses. These challenges highlight the limitations of manual molding in achieving precise rotor geometry and balance. To improve natural fiber rotor viability, optimizing manufacturing techniques is crucial to enhance dynamic balance and minimize vibrations. Advancements in fabrication could bridge the performance gap between natural and synthetic materials, making bio-based rotors more competitive. This study emphasizes the potential of natural fibers in sustainable energy and the need to refine production methods to maximize efficiency and reliability. Addressing these challenges will help integrate eco-friendly rotors into hydro turbine technologies. Full article

This paper presents an experimental investigation of six different types of composite sandwich panels manufactured from waste-based materials, which are comprised of two different types of skins (made from hemp and recycled PET (Polyethylene terephthalate) fabrics with bio-epoxy resin) and three different cores (composite wood, recycled plastic, and styrofoam) materials. The skins of these sandwich panels were investigated under five different environmental conditions (normal air, water, hygrothermal, saline solution, and 80 °C elevated temperature) over seven months to evaluate their durability performance. In addition, the tensile and dynamic mechanical properties of those sandwich panels were studied. The bending behavior of cores and sandwich panels was also investigated and compared. The results indicated that elevated temperatures are 30% more detrimental to fiber composite laminates than normal water. Composite laminates made of hemp are more sensitive to environmental conditions than composite laminates made of recycled PET. A higher-density core makes panels more rigid and less susceptible to indentation failure. The flexible plastic cores are found to be up to 25% more effective at increasing the strength of sandwich panels than brittle wood cores. Full article

The algae-derived bio-binder (ADBB) from hydrothermal liquefaction has been reported to be an effective and sustainable new alternative to petroleum-based curing agents for epoxy resin. However, there is still room for the epoxy/ADBB system to attain the comprehensive mechanical performance of conventional epoxy-based nanocomposites, typically reinforced with surface-functionalized nanofillers (e.g., glass nanoparticles (GNPs)) by petroleum-based silane coupling agents. Herein, we explored the use of ADBB as an innovative surface-modifying agent to functionalize GNPs and evaluated the potential of ADBB surface-functionalized GNPs (ADBB-GNPs) as a reinforcing agent in the epoxy/ADBB matrix nanocomposite by comparing them to pristine GNPs and (3-aminopropyl) triethoxysilane (APTES) (a popular silane coupling agent) surface-modified GNPs (APTES-GNPs). The surface functionalization of GNPs with ADBB was carried out and characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FTIR). Material performance including tensile, flexural, and Izod impact properties and thermal properties of the resulting epoxy/ADBB nanocomposites were investigated by corresponding ASTM mechanical test standards and thermogravimetric analysis (TGA). Our results revealed that the ADBB is a sustainable and effective surface-modifying agent that can functionalize GNPs. The obtained ADBB-GNPs significantly improved the mechanical performance of the epoxy/ADBB system at ultra-low loading (0.5 wt.%) by up to 42% and the maximum decomposition rate temperature increased from 419 °C to 422 °C, both of which outperformed APTES-GNPs. This research sheds light on developing sustainable surface-modifying agents for nanofillers to create high-performance sustainable polymer composite materials. Full article

Background: The primary objective of this study was to evaluate the cytotoxic and genotoxic effects of calcium silicate-based sealers (BioRoot RCS and MTA Fillapex) compared to an epoxy-based sealer (AH Plus). Materials and methods: The study was conducted in vitro with the cell lines HepG2 and V79 to evaluate cytotoxicity and genotoxicity using the comet and micronucleus assays. Eluates of the materials were tested at two different concentrations (3 cm²/mL and 0.5 cm²/mL) after an exposure time of 72 h. Data were analyzed using the Mann–Whitney and Kruskal–Wallis tests (p < 0.05). Results: At lower concentrations in both cell lines, MTA Fillapex showed no significant difference in the measured comet assay parameters compared to the negative control (p > 0.05). In addition, it showed significantly lower genotoxic effects compared to AH Plus for all comet assay parameters, concentrations, and cell lines (p ≤ 0.001). BioRoot RCS showed lower primary DNA damage (p ≤ 0.001) than AH Plus, only at higher concentrations and in the HepG2 cell line. Concerning the two tested bioceramic sealers, BioRoot RCS showed higher tail intensity values compared to MTA Fillapex (p < 0.05). In contrast to the results of the comet assay, BioRoot RCS significantly reduced the number of nuclear buds and nucleoplasmic bridges in the HepG2 cell line compared to MTA Fillapex, whereas reduction in the V79 cell line was only observed for nuclear buds (p < 0.05). Both materials increased the number of apoptotic cells compared to the negative control (p < 0.05). In comparison to AH Plus, BioRoot RCS and MTA Fillapex significantly reduced the number of cells with micronuclei and increased the number of cells with undamaged chromatin (p < 0.05). Conclusions: The findings suggest that MTA Fillapex and BioRoot RCS exhibit superior biocompatibility over AH Plus, as evidenced by their lower cytotoxic and genotoxic effects in vitro. These results support the use of calcium silicate-based sealers in clinical practice, highlighting the need for further studies to evaluate their performance in vivo and their implications for patient safety. Full article