Search Results (25)

We co-modified layered double hydroxide (LDH) in water using phosphocreatine (PC) and dodecylphosphoric acid (DPA) to obtain a highly dispersible LDH. Embedding this LDH in epoxy enabled V-0 at 7 wt% and lowered HRR, THR and TSP, attributed to a dense char and PC-DPA synergy. SEM, WAXS, and TGA characterised the structure and thermal behaviour of the functionalised LDHs. These modified LDHs were then loaded into the epoxy resin (EP) to develop flame-retardant nanocomposites. Compared to unmodified LDH (NO₃-LDH) and PC-modified LDH (PC-LDH), PC-DPA-LDH showed superior dispersion and compatibility within the epoxy matrix. As a result, PC-DPA-LDH/EP achieved a UL-94 V-0 rating at only 7 wt% loading, while NO₃-LDH/EP had no rating, and PC-LDH/EP reached only V-2. Moreover, PC-DPA-LDH/EP demonstrated significant decreases in peak heat release rate (46.4%), total heat release (34.5%), and total smoke production (59.7%) compared with neat EP. These improvements were attributed to the synergistic flame-retardant effects of PC and DPA, as well as to the formation of a compact char layer that effectively insulated the underlying material and suppressed volatile emissions. This work highlights the potential of bio-based, aqueous-synthesised nanohybrids for high-efficiency, eco-friendly flame-retardant epoxy systems. Full article

The increasing demand for sustainable materials in electrical engineering has encouraged the substitution of conventional fillers in epoxy insulation with recycled industrial by-products. This study investigates the potential use of waste tire rubber particles and zinc oxide recovered from electric arc furnace dust as eco-friendly fillers for epoxy resins in high-voltage insulation applications. Four material variants were fabricated: pure epoxy, epoxy with 10 wt% ZnO (0.7 mm thickness), epoxy with 10 wt% tire rubber (0.9 mm thickness), and epoxy with 20 wt% tire rubber (0.9 mm thickness). The breakdown voltage of each composite was measured under AC voltage. Results indicate that filler type and concentration influence breakdown behavior within each thickness group. The 10 wt% ZnO-filled epoxy exhibited a moderate enhancement in breakdown voltage compared with pure epoxy of the same thickness, consistent with interfacial modifications commonly observed in oxide-filled epoxy systems. Conversely, tire rubber fillers led to reduced breakdown performance, likely due to increased dielectric heterogeneity introduced by the elastomeric phase. No direct comparison between ZnO- and rubber-filled systems was performed due to differences in manufacturable sample thickness. The findings contribute to the evaluation of recycled fillers in dielectric composite systems within a circular-economy framework. Full article

To tackle the long-standing issue of inadequate corrosion protection in waterborne coatings, this study innovatively incorporates hollow glass microspheres (HGB) into waterborne epoxy zinc-rich primers through physical blending, constructing a dual-layer synergistic anticorrosion system comprising an HGB-modified primer and a zirconium phosphate/urushiol titanium polymer (UTPCZrP)-modified waterborne epoxy topcoat. Optimal performance is achieved with 2 wt% HGB addition: the dual-layer coating retains favorable physicochemical and mechanical properties while enhancing anticorrosion performance by 1–2 orders of magnitude, boasting an impedance of 3.2 × 10⁶ Ω, a corrosion rate as low as 5.71 × 10^–6 mm/year, 99.98% protection efficiency (stable after 25-day immersion), and 720 h salt spray resistance without corrosion diffusion. This method exhibits universality in waterborne polyurethane (WPU) and polyester (WPE) systems, yielding impedance values of 3.57 × 10⁶ Ω and 2.7 × 10⁶ Ω, respectively, with over 90% improved anticorrosion performance and long-term stability. By optimizing components and synergistic system design, this work significantly enhances waterborne coatings’ anticorrosion efficiency, reduces raw material costs, and provides a scalable technical pathway for high-performance, eco-friendly anticorrosion coatings. Full article

The growing need for self-powered Internet of Things networks has raised interest in converting abundant waste into reliable energy harvesters despite long-standing material and technology challenges. As demand for environmentally friendly self-powered IoT devices continues to rise, attention toward green waste as an eco-friendly energy source has strengthened. However, its direct utilisation in high-performance energy harvesters remains a significant challenge. Driven by the growing need for renewable sources, the triboelectric nanogenerator has emerged as an innovative technology for converting mechanical energy into electricity. In this work, the design, fabrication, and characterisation of a rotating triboelectric energy harvester as a prototype device employing date seed waste as the tribopositive layer are presented. The date seeds particles, measuring 1.2 to 2 mm, were pulverised using a grinder, mixed with epoxy resin, and subsequently applied to the grating-disc structure. The coated surface was machined on a lathe to provide a smooth surface facing. The performance of the prototype was evaluated through a series of experiments to examine the effects of rotational speed, the number of grating-disc structures, the epoxy mixing process, and the prototype’s influence on the primary system, as well as to determine the optimal power output. An increase in rotational speed (RPM) enhanced power generation. Furthermore, increasing the number of gratings and pre-mixing of epoxy with the biomaterial resulted in enhanced output power. Additionally, with 10 gratings, operating at 1500 rpm, and a 24 h pre-mixing method, the harvester achieved maximum voltage and power outputs of 129 volts and 1183 μW at 7 MΩ. Full article

Metal particles and surface charge accumulation are considered the key factors that could trigger unexpected flashovers of insulators equipped in gas-insulated switchgear (GIS). In eco-friendly gases, the flashover properties and the synergistic effect of the surface charge and the metal particle on flashover remain unclear. This study investigates the flashover properties of down-scaled 252 kV GIS basin-type epoxy insulators with metal particles in C₄F₇N/CO₂ mixtures, with and without AC pre-charging. Tests considered various particle adherence locations and a particle-free control group. The results indicated that metal particles at the high-voltage (HV) electrode or middle area reduce flashover voltage, with the HV electrode and concave surface being most critical. Surface charges, induced by pre-charging and metal particle attachment, interact synergistically with the metal particle during the flashover process, increasing the flashover voltage and redirecting arcs away from them. Such findings enhance understanding of flashover mechanisms in eco-friendly gas-insulated systems and inform insulator design. Full article

Banana fibres (BFs), derived from the pseudo-stems of Musa acuminata, represent a widely available agricultural residue with strong potential as an eco-friendly reinforcement in composite materials—particularly in bio-based epoxy or thermoplastic systems used in automotive interiors, packaging, and lightweight construction. However, their inherent variability presents challenges for consistent and reliable mechanical characterisation. This study investigates the effect of wood ash treatment, an eco-friendly alternative to conventional alkaline processing, on the tensile strength of single BFs. Fibres were treated in aqueous wood ash solutions at two pH levels (12.4 and 13.5) and soaking durations of 3 h and 24 h, and then tested according to ASTM C1557. At least 50 valid tensile tests per series were performed, and the results were analysed using a two-parameter Weibull distribution to quantify characteristic strength and variability, complemented by reliability analysis to assess survival probability. Untreated fibres exhibited low characteristic strength (396.6 MPa) and a Weibull modulus of 1.79, confirming significant scatter. Treated fibres showed marked improvements: the highest characteristic strength was achieved at pH 13.5 for 3 h (552.8 MPa, m = 3.17), while the greatest uniformity was observed at pH 13.5 for 24 h (m = 4.62). Reliability curves confirmed superior performance of treated fibres, with 75% survival strengths up to 373 MPa compared to 198 MPa for untreated. These findings demonstrate that wood ash treatment enhances both the strength and reliability of BFs for sustainable composite applications. Full article

Epoxidized soybean oil (ESO) is the oxidation product of soybean oil with hydrogen peroxide and either acetic or formic acid obtained by converting the double bonds into epoxy groups, which is non-toxic and of higher chemical reactivity. Oxidized soybean oil (ESO) has gained significant attention as a renewable and environmentally friendly alternative to petroleum-based epoxy resins. Derived from soybean oil through epoxidation of its unsaturated fatty acids, ESO offers a bio-based platform with inherent flexibility, low toxicity, and excellent chemical resistance. When used as a reactive diluent or primary component in epoxy formulations, ESO enhances the sustainability profile of coatings, adhesives, and composite materials. This study explores the mechanical properties of ESO-based epoxy systems, with particular attention to formulation strategies, crosslinking agents, and performance trade-offs compared to conventional epoxies. The incorporation of ESO not only reduces the reliance on fossil resources but also imparts tunable thermal and mechanical properties, making it suitable for a range of industrial and eco-friendly applications. The results underscore the potential of ESO as a viable component in next-generation green materials, contributing to circular economy and low-impact manufacturing. For the application of these materials in pultrusion and FW technologies, the Taguchi method is used to determine the most influential process parameters. 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

Cleavable bio-based epoxy resin systems are emerging, eco-friendly, and promising alternatives to the common thermoset ones, providing quite comparable thermo-mechanical properties while enabling a circular and green end-of-life scenario of the composite materials. In addition to being designed to incorporate a bio-based resin greener than the conventional fully fossil-based epoxies, these formulations involve cleaving hardeners that enable, under mild thermo-chemical conditions, the total recycling of the composite material through the recovery of the fiber and matrix as a thermoplastic. This research addressed the characterization, processability, and recyclability of a new commercial cleavable bio-resin formulation (designed by the R-Concept company) that can be used in the fabrication of fully recyclable polymer composites. The resin was first studied to investigate the influence of the different post-curing regimes (room temperature, 100 °C, and 140 °C) on its thermal stability and glass transition temperature. According to the results obtained, the non-post-cured resin displayed the highest T_g (i.e., 76.6 °C). The same post-curing treatments were also probed on the composite laminates (glass and carbon) produced via a lab-scale vacuum-assisted resin transfer molding system, evaluating flexural behavior, microstructure, and dynamic-mechanical characteristics. The post-curing at 100 °C would enhance the crosslinking of polymer chains, improving the mechanical strength of composites. With respect to the non-post-cured laminates, the flexural strength improved by 3% and 12% in carbon and glass-based composites, respectively. The post-curing at 140 °C was instead detrimental to the mechanical performance. Finally, on the laminates produced, a chemical recycling procedure was implemented, demonstrating the feasibility of recovering both thermoplastic-based resin and fibers. Full article

The growing need for sustainable materials in engineering applications has led to increased interest in the use of waste-derived ceramics as reinforcing fillers in polymer composites. This study investigates the mechanical and tribological performance of epoxy composites reinforced with Yttria-Stabilized Zirconia (YSZ) waste ceramics, focusing on the effects of varying ceramic content (0–40 wt.%). The results demonstrate that while the tensile strength decreases with increasing ceramic content, the wear resistance and surface hardness improve, particularly at 20 wt.% YSZ. These findings are highly relevant for industries such as automotive, aerospace, and industrial manufacturing, where the demand for eco-friendly, high-performance materials is growing. This work aligns with the journal’s focus on sustainable engineering by offering new insights into the practical application of waste materials in high-performance composite systems. Full article

Eco-friendly waterborne coatings frequently exhibit poor corrosion resistance, high solvent content, and extended curing times, attributed to the excessive employment of hydrophilic groups and petroleum-derived polyols. In this work, aniline trimer (ACAT) and polyethylene glycol (PEG) were used as chain extenders. E-44 epoxy resin was subsequently utilized to modify the system and an aniline trimer-modified waterborne polyurethane (AT-WPU) dispersion was prepared and characterized. The chemical structure of the synthesized ACAT was characterized employing 1H NMR, ESI-MS, and FTIR spectroscopy. The structure and coating performance of the AT-WPU dispersion were investigated utilizing FTIR, particle size analysis, thermogravimetric analysis, DSC, TEM, SEM, and electrochemical corrosion testing. The results demonstrate that the aniline trimer-modified waterborne polyurethane dispersion was successfully synthesized. Additionally, the DSC analysis results and thermogravimetric graphs indicate that the glass transition temperature and thermal stability of the coatings increased with the addition of aniline trimer. As the aniline trimer content increased, the hardness and adhesion of the coatings were significantly enhanced. In the electrochemical corrosion assessment, the corrosion current density of AT-WPU-3 attained 7.245 × 10⁻⁹ A·cm⁻², and the corrosion rate was as low as 0.08 μm·Y⁻¹, indicating excellent corrosion resistance. The present study provides promising practical applications in the domain of metal material protection. Full article

This study aimed to investigate the feasibility of using geopolymer paste (GP) as an adhesive agent for (i) anchoring steel bars in concrete substrates, (ii) repairing concrete, and (iii) repairing limestone and granite masonry blocks commonly found in historic buildings. In this investigation, seven cement-free GP mixes were developed with different combinations of binder materials (slag, silica fume, and metakaolin). The mechanical properties, adhesive performance, and production cost of the developed GP mixes were compared to those of a commercially epoxy adhesive mortar (EAM). The results obtained from this study indicated that the use of GPs enhanced the bonding between steel bars and concrete substrates, achieving bonding strengths that were 19.7% to 49.2% higher than those of control specimens with steel bars directly installed during casting. In concrete repairs, the GPs were able to restore about 60.6% to 87.9% of the original capacity of the control beams. Furthermore, GPs exhibited a promising performance in repairing limestone and granite masonry blocks, highlighting their potential suitability for masonry structures. The best adhesive performance was observed when a ternary binder material system consisting of 70% slag, 20% metakaolin and 10% silica fume was used. This combination, compared to the investigated EAM, showed comparable adhesive properties at a significantly low cost, indicating the viability of GPs as a cost-effective, eco-friendly adhesive agent. Full article

Reliable ballistic armor systems are crucial to ensure the safety of humans and vehicles. Typically, these systems are constructed from various materials like fiber-reinforced polymer composites, which are utilized for a favorable weight to ballistic protection ratio. In particular, there has been a quest for eco-friendly materials that offer both strong mechanical properties and sustainable advantages. The present work conducted a ballistic analysis of epoxy matrix composites using raffia (Raphia vinifera) fibers from the Amazon region as reinforcement. The experiments investigated the limit and residual velocities of composites with 10, 20, and 30 vol% of raffia. The experimental density of the composites was lower than that of the epoxy. Fractured surfaces were examined by scanning electron microscopy (SEM) to reveal the failure mechanism. The results showed that composites with 10 vol% raffia fiber fabric had the highest ballistic energy absorption (168.91 J) and limit velocity (201.43 m/s). The ones with 30 vol% displayed a higher level of physical integrity. The SEM micrographs demonstrated the failure mechanisms were associated with delamination and fiber breakage. There was a small variation in residual velocity between the composites reinforced with 10, 20, and 30 vol% of raffia, with 826.66, 829.75, and 820.44 m/s, respectively. Full article

Fibre-reinforced polymers (FRPs) are widely used in industry due to their impressive strength-to-weight ratio, corrosion resistance and high durability. One of the primary components of FRPs is synthetic resins, specifically epoxy, which has been identified as harmful to the environment. To address this concern, an eco-friendly alternative made from basalt fibres and bio resin has the potential to reduce the environmental impact. This study investigates Basalt Fibre-Reinforced Polymer (BFRP) laminates manufactured using two bio resins, AMPRO™ BIO and Change Climate, comparing them to one conventional epoxy resin, WEST SYSTEM^®, in terms of tensile modulus, strength and fracture toughness, as well as shear properties. The results indicate that BFRP laminates made with bio resins exhibit comparable or better mechanical properties to their conventional counterparts with tensile strength being between 6 and 17% more in bio resins compared to the conventional resin, thereby paving the way for further exploration of sustainable FRP laminates in future engineering applications. Full article

In general, the majority of fiber-reinforced polymer composites (FRPs) used in structural applications comprise carbon, glass, and aramid fibers reinforced with epoxy resin, with the occasional utilization of polyester and vinyl ester resins. This study aims to assess the feasibility of utilizing recyclable and sustainable materials to create a resilient composite suitable for structural applications, particularly in scenarios involving low-velocity and high-velocity impact (LVI, HVI) loading. The paper presents a comparative analysis of the performance of E-glass, aramid, and eco-friendly basalt-reinforcing fabrics as reinforcement fibers in both thermosetting (epoxy) and recyclable thermoplastic (Elium^©) resins. Given the limited research on Elium composites, especially those incorporating basalt-reinforcing fiber, there is an urgent need to expand the databases of fundamental mechanical properties for these diverse composites. This necessity is exacerbated by the scarcity of the literature regarding their performance under low- and high-velocity impact loadings. The results of this study will demonstrate the potential of basalt-reinforced Elium composite as an effective recyclable and environmentally friendly structural material system for both static and dynamic loading conditions. Full article