J. Compos. Sci., Volume 7, Issue 10 (October 2023) – 41 articles

In this study, we systematically study the efficient production method and electrochemical characteristics of activated carbons (AC) derived from rice husk (RH) and walnut shell (WS). In particular, the effectiveness of physical activation using carbon dioxide (CO₂) was investigated and compared with the more common chemical activation method using potassium hydroxide (KOH). The results show that the KOH–activated samples have remarkable specific capacities, reaching 157.8 F g⁻¹ for RH and 152 F g⁻¹ for WS at 1 A g⁻¹. However, the rate capability of AC obtained via KOH decreases significantly as the scanning rate increases, retaining only 51.5% and 68% of their original capacities for RH–KOH and WS–KOH, respectively, at 20 A g^–1. In contrast, CO₂–activated samples show a superior rate performance with a capacity retention of 75.6% for WS and 80% for RH at the same current density. In addition, electrochemical impedance spectroscopy (EIS) analysis shows that AC obtained via CO₂ has a lower charge transfer resistance compared to its KOH counterparts. CO₂–activated RH and WS electrodes show Rct values of 0.1 Ω and 0.24 Ω, respectively, indicating improved ion transport kinetics and surface area utilization. These results highlight the importance of activation techniques in tailoring the electrochemical behavior of biomass–derived carbon. This study not only expands the understanding of the interaction between activation, morphology, and performance but also indicates the potential of CO₂ activation as an environmentally friendly and efficient alternative. As the field of sustainable energy storage advances, this work provides valuable guidance for the development of high–performance supercapacitor electrodes with less environmental impact. Full article

Natural and synthetic fibers offer a multitude of advantages within the automotive sector, primarily due to their lightweight properties, including appealing characteristics such as adequate mechanical strength, low density, improved acoustic–thermal insulation, cost-effectiveness, and ready availability. In this study, we aimed to strengthen epoxy-based composites with natural and synthetic fibers using bamboo and glass, respectively. Additionally, the reinforcement processing of this hybrid composite material was optimized using a Taguchi L9 (nine experimental runs) orthogonal array design with linear modeling through the Design of Experiment (DoE) principles. The fibers were alkali-treated with sodium hydroxide (NaOH), and the composites were manufactured through the hand lay-up process at ambient temperature and characterized comprehensively using ASTM standard methods. The experimental results of the bamboo–glass fiber composite materials presented a significantly high tensile strength of 232.1 MPa and an optimum flexural strength of 536.33 MPa. Based on the overall Taguchi and linear modeling analysis, the NaOH treatment, fiber content, and epoxy resin concentration were optimized. These findings reveal that the ideal combination consists of 20% fiber content, 8% NaOH treatment, and 65% epoxy resin concentration. The statistical method Analysis of Variance (ANOVA) was employed to confirm the significance of these factors. The integration of the amount (%) of bamboo fiber used played a pivotal role in influencing the mechanical properties of this hybrid composite. Overall, this study demonstrates that the reinforcement of natural fiber with polymeric material composites on epoxy enhanced the composite characteristics and quality. Therefore, this bamboo–glass–epoxy-based composite can be recommended for lightweight structural applications, especially in the automotive sector, in the future. Full article

This study used finite element analysis (FEA) to model the effects of adhesive Z-connections on the thickness swelling of laminated wood composites exposed to water. We hypothesized that the area density, diameter, and spatial distribution of adhesive Z-connections will influence the ability of Z-connections to restrain thickness swelling of the composites. We tested this hypothesis by modelling a wood composite in ANSYS FEA software v. 17.0 to explore the effect of moisture on the thickness swelling of the wood composite. The results were compared with those obtained experimentally. We then examined the effect of the area density, size (diam.), and spatial distribution of the adhesive Z-connections on the thickness swelling of wood composites. Our results showed a positive correlation between the number of adhesive Z-connections in the composites and restriction of thickness swelling following 72 h of simulated moisture diffusion. Similarly, increasing the size of adhesive Z-connections also restricted thickness swelling. In contrast, different spatial distributions of Z-connections had little effect on restraining thickness swelling. Our modelling approach opens up opportunities for more complex designs of adhesive Z-connections, and also to examine the effect of wood properties, such as permeability, density, and hygroscopic swelling ratios on the thickness swelling of laminated wood composites. Full article

Carbon nanomaterials are an emerging class of nano-reinforcements to substitute for metal-based nanomaterials in polymer matrices. These metal-free nano-reinforcement materials exhibit a high surface area, thermal stability, and a sustainable nature. Compared to conventional reinforcements, nano-carbon-reinforced polymer composites provide enhanced mechanical and thermal properties. While previous reviews summarized the functionality of nanocomposites, here, we focus on the thermomechanical properties of nano-carbon-reinforced nanocomposites. The role of carbon nanomaterials, including graphene, MXenes, carbon nanotubes, carbon black, carbon quantum dots, fullerene, and metal–organic frameworks, in polymer matrices for the enhancement of thermal and mechanical properties are discussed. Different from metal-based nanomaterials, carbon nanomaterials offer high specific strength, abundance, and sustainability, which are of considerable importance for commercial-scale applications. Full article

Off-road racing vehicles require protection on the underside of their chassis in order to protect vital components from impact damage. The use of composites in thin laminate form to achieve this protection is widespread, although failure due to impact from foreign objects still occurs. The use of UHMWPE (Ultra High-Molecular Weight Polyethylene) fibres, which have superior mechanical properties to aramid fibres in vehicle belly guards, is not prevalent and, hence, could prove useful in this application. A comprehensive Finite Element Analysis (FEA) is performed in order to determine suitable laminate panel layups that can be tested, analysed, and compared to the original laminate layup, which comprises six layers of aramid and two layers of carbon fibre fabrics. This provides initial insight into the comparison of the new proposed laminates and reveals if improvements have been made. The laminates found using FEA are manufactured into panels that represent the fixture and loading cases seen in racing vehicles. Experimental testing is carried out on the various panels, and the results are compared to those of the mathematical modelling. Substituting the currently used carbon fibres with more aramid fibres increases the impact resistance of the panel. Using UHMWPE fibres greatly increases the impact resistance of the panel; however, fibre delamination becomes more prevalent. This is due to the poor fibre wettability of UHMWPE fibres and the large strain before failure of the fibres. The modelled results show good agreement with the experimental results in terms of the locations at which damage occurred. Full article

Because of the expensive nature of sensors used to detect heavy metals and the severe health risks associated with certain heavy metals, there is a pressing need to develop cost-effective materials that are highly efficient in detecting these metals. A flower-shaped WO₂I₂-Poly(1H-pyrrole) (WO₂I₂/P1HP) nanocomposite thin film is synthesized through the oxidation of 1-H pyrrole using iodine and subsequent reaction with Na₂WO₄. The nanocomposite exhibits a distinctive flower-like morphology with an average size of 20 nm. Elemental composition and chemical structure are confirmed via X-ray photoelectron spectroscopy (XPS) analyses, while X-Ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses provide further evidence of crystalline peaks and functional groups within the composite. The potential of the nanocomposite as a sensor for Cd²⁺ ions is determined using two approaches: simple potentiometric (two-electrode cell) and cyclic voltammetric (three-electrode cell) methods, over a concentration range spanning from 10⁻⁶ to 10⁻¹ M. From the simple potentiometric method, the sensor showcases strong sensing capabilities in the concentration span of 10⁻⁴ to 10⁻¹ M, displaying a Nernstian slope of 29.7 mV/decade. With a detection limit of 5 × 10⁻⁵ M, the sensor proves adept at precise and sensitive detection of low Cd²⁺ ion concentrations. While using the cyclic voltammetric method, the sensor’s selectivity for Cd²⁺ ions, demonstrated through cyclic voltammetry, reveals a sensitivity of 1.0 × 10⁻⁵ A/M and the ability to distinguish Cd²⁺ ions from other ions like Zn²⁺, Ni²⁺, Ca²⁺, K⁺, Al³⁺, and Mg²⁺. This selectivity underscores its utility in complex sample matrices and diverse environments. Furthermore, the sensor’s successful detection of Cd²⁺ ions from real samples solidifies its practical viability. Its reliable performance in real-world scenarios positions it as a valuable tool for Cd²⁺ ion detection across industries and environmental monitoring applications. These findings advocate for its utilization in commercial settings, highlighting its significance in Cd²⁺ ion detection. Full article

An estimate of the effect of initial damage, such as delamination in the area of a structural hole, on the static and fatigue strength of polymer composite material (PCM) based on computational mechanics methods is presented. Calculation for durability of structural elements made of PCM is conducted using Simcenter 3D—Samcef package and Specialist Durability module. A typical carbon fiber-reinforced plastic with the available physical and mechanical characteristics obtained from the tests was chosen as the study material. Fatigue characteristics of the typical carbon fiber-reinforced plastic were approximated for subsequent calculation on durability. In the durability calculation, the observed parameter is the degradation of the material stiffness under repeated loading of the investigated area. The convergence with the experimental results of the fatigue strength modeling for a defect-free sample, which is a strip with a hole, is estimated. The fatigue strength of a sample with a delamination-type defect is also compared with the fatigue strength of a damage-free sample. Full article

The development of novel embedded sensors for structural health monitoring (SHM) is crucial to provide real-time assessments of composite structures, ensuring safety, and prolonging their service life. Early damage diagnostics through advanced sensors can lead to timely maintenance, reducing costs and preventing potential catastrophic failures. This paper presents the synthesis, 3D printing, and characterization of novel embedded strain sensors using multi-walled carbon nanotube (MWCNT) -enhanced nanocomposites in fiberglass reinforced composites for potential damage diagnostics and SHM applications. MWCNTs are dispersed within structural epoxy for the additive manufacturing of nanocomposites with piezoresistive sensing capability. The 3D-printed nanocomposite sensors are embedded in fiberglass-reinforced composite laminates. The piezoresistive sensing capabilities of the 3D-printed sensors within composites are characterized by applying different levels of maximum loads and load rates under three-point bending loads. Additionally, the long-term reliability of the developed strain sensors is evaluated up to 1000 cycles. The recorded piezoresistive sensing signals show high sensitivity for the externally applied bending loads with advanced gauge factor up to 100, resulting in potential load sensing capability for in-situ damage diagnostics and real-time SHM for structural composites. Full article

The oxidation states of atoms in CuCr_1-xLa_xS₂ (x = 0–0.03) solid solutions were determined using the analysis of Cu2p, Cr2p, S2p, and La3d core level binding energy. The cationic substitution did not significantly affect the charge distribution on matrix elements (Cu, Cr, and S). The oxidation states of the atoms were identified as S²⁻ for sulfur, Cu⁺ for copper, and Cr³⁺ for chromium. The cationic substitution in CuCr_1-xLa_xS₂ was found to occur via the isovalent principle. The cationic substitution of CuCrS₂ matrix with lanthanum ions led to the enhancement of the Seebeck coefficient comparing CuCr_1-xLa_xS₂ to the initial matrix. The observed enhancement was attributed to the reconstruction of the valence band electronic structure after the cationic substitution. The maximum Seebeck coefficient value of 412 μV/K was measured for CuCr_0.985La_0.015S₂ at 420 K. An increase in the lanthanum concentration to x = 0.03 caused a suppression of the Seebeck coefficient. The synthetic route was found to significantly affect both the magnetic properties and charge carrier concentration. The magnetic properties of CuCr_1-xLa_xS₂ synthesized using metal sulfide reagents cannot be interpreted using the simple isovalent Cr³⁺ to La³⁺ cationic substitution model. The defectiveness of the samples and the formation of the impurity CuLaS₂ phase could be additional factors that affect the magnetic properties of CuCr_1-xLa_xS₂. Full article

UV-light-assisted additive manufacturing (AM) technologies require bio-based resins that can compete with commercial petroleum-based ones to enable a more sustainable future. This research proposes a significantly improved vegetable oil-based resin reinforced with nanofibrillated cellulose (NFC). The incorporation of ultra-low concentrations (0.1–0.5 wt%) of NFC produced disproportionate enhancements in mechanical performance. Noteworthy, a 2.3-fold increase in strain at the break and a 1.5-fold increase in impact strength were observed with only 0.1 wt% of NFC, while at 0.5 wt%, a 2.7-fold increase in tensile modulus and a 6.2-fold increase in toughness were measured. This is in spite of NFC agglomeration at even the lowest loadings, as observed via examination of fracture surfaces and dynamic mechanical analysis (DMA) Cole–Cole plot analysis. The addition of 0.1 wt% NFC also increased creep resistance by 32% and reduced residual strain by 34% following creep recovery. The Burgers model satisfactorily described the composites’ viscoelastic–viscoplastic behavior within the applied stress levels of 1–3 MPa. The successful development of novel NFC/bio-resin composites with enhanced mechanical performance and long-term stability highlights the potential of these composites to substitute petroleum-based resins in the context of AM resins. Full article

Photocatalytic dye degradation is an energy-saving, environmentally friendly and sustainable way of managing potentially toxic wastewater from the textile industry. PbTiO₃ was prepared using a solid-state reaction method, and an optimal ratio of PbTiO₃/TiO₂/g-C₃N₄ photocatalyst was synthesized using the sol-gel method to test its ability to decompose organic dyes. Methylene blue (MB) was selected as a target dye to test the photocatalytic effects. SEM results showed that the synthesis of a PbTiO₃/TiO₂/g-C₃N₄ photocatalyst yielded a unique nano structure with many surface pores. UV-Vis analysis demonstrated that the novel composite photocatalyst had higher visible light absorption, and a reduced energy gap. Experimental results showed that of the samples tested, PTO/TO/CN 1.0 showed the best photocatalytic effect on the removal of MB. Under visible light, the removal rate of MB by PTO/TO/CN 1.0 was up to 98.79%. The novel PTO/TO/CN 1.0 photocatalyst exhibited relatively high MB adsorption and had a high photocatalytic ability. Full article

Weight plays a significant role in the automotive and aerospace fields due to the demand of lightweight material structures. A lighter body in weight (BIW) and in structure can reduce fuel consumption, lessen emissions, and support the SDGs 9, 11, 12, and 13. Therefore, polyurethane (PU) foam is suitable for applications that require low weight. The characteristics of hybrid polyurethane-graphite micro were successfully evaluated in this study. Several tests have been used to characterize these structures, such as, compression, hardness, density, surface evaluation, and FTIR analysis. The results showed that the expansion and shrinkage variations lead to different shapes at specific ratios. Compression tests show that the highest value occurred at 0.84 kN, with a 4:1 ratio found in pure PU foam without any reinforcement. PU foam with 2% graphite filler showed the highest results at the 4:1 ratio with a value of 0.45 kN. Furthermore, the highest hardness test result was 37.7 SHD. Density testing indicates that the highest value is obtained from specimens with a 4:1 ratio of 0.077 g/cm³. FTIR testing reveals that adding graphite as a filler alters the chemical bonds during the formation of solid PU foam. Surface observations show that adding graphite as a filler influences the variation in material structure formation. All the evaluation has tended to conclude the present combination as suitable for lightweight structures applications. Full article

During the thermoforming of fibre-reinforced thermoplastic (FRTP) organosheets, the desire to minimise tool temperatures leads to non-isothermal temperature profiles through the laminate thickness. The aim of this study was to understand the influence of these non-isothermal conditions on FRTP intra-ply shearing. Novel non-isothermal bias extension tests were conducted, revealing that an average between the isothermal shear curves of both laminate faces approximately represented the respective non-isothermal condition. However, these findings were irrespective of FRTP thickness, and only applied to laminates that wholly remained above the crystallisation onset temperature. Upon the onset of crystallisation in a single ply, the non-isothermal shear resistance skewed heavily towards that (within 5%) of the crystallised ply and inhomogeneous shear angles were observed. Non-isothermal thermoforming validated these findings with the presence of wrinkles on non-isothermal hemispheres in which a single ply had reached crystallisation. This reaffirms the importance of accurate thermal monitoring during FRTP processing. Full article

This study investigates the impact of a binary filler on the physicomechanical and tribological properties, as well as structure, of polymeric composite materials based on ultra-high-molecular-weight polyethylene. The organic modifier—2-mercaptobenzothiazole and wollastonite particles synthesized from two different systems (modeled and derived from waste) were used as the binary filler. The synthesis of wollastonite was carried out in the complex model system (CaSO₄·2H₂O–SiO₂·nH₂O–KOH–H₂O) and from technogenic waste (borogypsum). It was demonstrated that the introduction of the binary filler made it possible to obtain an optimal combination of mechanical and tribological properties. It was found that during the wear of polymeric composite materials loaded with organic fillers, the fillers migrate to the friction surface, providing a shield against abrasive wear of the steel counterface. Due to the modification of ultra-high-molecular-weight polyethylene by 2-mercaptobenzothiazole, the interdiffusion of polymeric matrix macromolecules and interphase coupling with wollastonite particles improve. The 2-mercaptobenzothiazole organic compound used as the filler facilitates the relaxation processes within the composite under external loads. Full article

Carbon reinforcements are used to improve the mechanical properties of cement, allowing the preparation of a strengthened and toughened composite. Functionalization through a reaction with acid is necessary to guarantee both a good dispersion in water and a strong interaction with cement. Different functionalized reinforcements improve the mechanical properties of the composites in comparison with pristine cement. The use of a combination of carbon fibers, carbon nanotubes, and graphene nanoplatelets were analyzed in order to verify their synergistic effect. The use of functionalized carbon nanotubes and carbon fibers demonstrates an improvement of 71% in flexural strength and 540% in fracture energy. Full article

This study focuses on the production and characterization of biocomposites based on a thermoplastic polymer (high-density polyethylene, HDPE) and a biosourced filler (buckwheat husk, BHS) to develop more sustainable composites. Compounding was performed via twin-screw extrusion with three different types of BHS. In the first series, untreated BHS was directly mixed with the polymer matrix, while the second series used mercerized BHS and the third series used pretreated BHS with a coupling agent (polyethylene grafted with maleic anhydride, MAPE) in solution. The samples were prepared at different concentrations (10, 20, 30, 40 and 50 wt.% of BHS) to compare with the neat matrix (0%). All the samples were finally produced by compression molding and then cut to get the specimens for characterization. The latter included morphological (scanning electron microscopy), physical (density and hardness) and mechanical (tension, flexural and impact strength) properties. Based on the results obtained, it was observed that most of the mechanical and physical properties were improved, especially when the BHS was pretreated in solution before its introduction into the polymer matrix. The results showed that 30 wt.% of BHS in HDPE was the optimum for most of the properties investigated. Full article

Designing asphalt mixtures for pavement construction by controlling the moisture-mediated damage remains challenging. With the progression of time, this type of damage can accelerate deterioration via fatigue cracking and rutting unless inhibited. In this study, two types of hot asphalt mixtures (HAMs) were made by incorporating recycled concrete aggregates (RCAs), which were reinforced with rock wool fibers (RWFs). The first specimen was a normal mixture with a completely virgin aggregate, and the second one was a sustainable mixture with 30% RCAs. The proposed mixes were thoroughly characterized to assess the impact of RWF incorporation at various contents (0.5, 1, 1.5, and 2%) on moisture resistance. The optimal asphalt concentration (OAC) and volumetric parameters of the mixes were determined using the Marshall technique. The moisture susceptibility of the obtained HAMs was evaluated in terms of the tensile strength ratio (TSR). The results revealed that the moisture resistance, Marshall stability, flow, and volumetric parameters of the HAMs were improved due to the reinforcement by RWFs, indicating a reduction in the moisture sensitivity and an increase in TSR%. In addition, the HAMs designed with 1.5% RWFs displayed the highest TSR% (11.37) and Marshall stability compared to the control mix. The observed improvement in the moisture resistance and Marshall attributes of the prepared HAMs was ascribed to the uniform distribution of the RWFs that caused a well-interconnected structure and tightening in the asphalt concrete matrix. It is asserted that the proposed HAMs can be nominated for the construction of durable high-performance pavements. Full article

The transferability of structure–property relationships for laser-pretreated metal adhesive joints to laser-pretreated metal–carbon-fiber-reinforced plastic (CFRP) bonds was investigated. Single-lap shear tests were performed on hybrid AW 6082-T6–CFRP specimens pretreated with the same pulsed laser surface parameter sets on the metal surface as previously tested, AW 6082-T6–E320 metal adhesive joints. The fracture surfaces were characterized to determine the type of failure and elucidate differences and commonalities in the link between surface structures and single-lap shear strengths. Digital image analyses of the hybrid specimens’ fractured surfaces were used to quantify remaining CFRP fragments on the metallic joint side. The results indicate that high surface enlargements and the presence of undercut structures lead to single-lap shear strengths exceeding 40 MPa and 35 MPa for unaged and aged hybrid specimens, respectively. Whereas for the metal–polymer joints, the trend from high strength to weakly bonded specimens is largely continuous with the degree of surface structuring, hybrid metal–CFRP joints exhibit a drastic drop in joint performance after aging if the laser-generated surface structures are less pronounced with low surface enlargements and crater depths. Surface features and hydrothermal aging determine whether the specimens fail cohesively or adhesively. Full article

Nanoparticles have attracted substantial attention for their diverse range of applications, particularly in biomedicine applications and drug delivery, owing to their unique properties. However, their tiny size facilitates easy cellular entry, which can also lead to interactions with cellular components, potentially resulting in toxicity and undesirable effects. In this study, a novel nanocomposite formulation was developed using biopolymers, specifically ethylcellulose and collagen, as capping and stabilizing agents to create bimetallic nanoparticles including TiO₂@Cr₂O₃ nanoparticles. Physicochemical and morphological analyses were carried out to validate the formulation’s structure. The obtained characteristics emphasized the presence of a nanostructure involving bimetallic nanoparticles. This formulation exhibited excellent biological activity, including high biocompatibility with Vero and WI38 cells at concentrations of 40.4 and 52 µg/mL, respectively, as well as effective anticancer activity with significant selectivity. The IC50 values were determined to be 19 and 22 µg/mL for MCF7 and A549 cells, respectively. The antimicrobial assessment revealed the highest MIC value for A. niger at 50 µg/mL, while the lowest MIC value was observed for Gram-positive bacteria at 3.12 µg/mL. Additionally, the nanocomposite demonstrated antioxidant activity at a low concentration of 1.5 µg/mL. Full article

Additive manufacturing by 3D printing has emerged as a promising construction method offering numerous advantages, including reduced material usage and construction waste, faster build times, and optimized architectural forms. One area where 3D printing’s potential remains largely unexplored is in combination with lightweight materials, especially lightweight gypsum. This research paper explores the potential of combining 3D printing technology with lightweight gypsum-based composites to extend the relatively limited gypsum application possibilities in the construction industry. The study investigates the use of expanded polystyrene (EPS) beads as an aggregate in gypsum composites, focusing on the printability of the mixture and hardened state mechanical properties in various print directions. Mechanical tests reveal that 3D printing can reduce the compressive strength of the EPS–gypsum composite by between 3% and 32%, and the flexural strength by up to 22%, depending on testing direction. However, the technology opens up new production possibilities for applications where such strength can be sufficient. The study describes that a slight increase in the water-to-gypsum (W/G) ratio in 3D-printed mortars enhances homogeneity and reduces porosity, resulting in improved structural uniformity and therefore higher flexural and compressive strength values. Furthermore, the paper discusses the mechanical anisotropy observed in 3D-printed samples. The combination of 3D printing technology and lightweight gypsum offers the potential for sustainable construction practices by reusing waste materials and creating lightweight, thermally and acoustically insulative, as well as architecturally diverse building components. Full article

Six commercial, lead-free, radiation protective materials were tested for their attenuation across a range of X-ray energies used in medical diagnostic imaging and interventional radiology. While all the tested materials showed the specified attenuation at the X-ray energy claimed by their manufacturers, only two of the materials showed satisfactory attenuation in an extended range of medical X-ray energies (generated in X-ray tubes with voltages between 50 and 150 kV). The lead-free materials are lighter than the lead-containing materials, which is very important for those wearing the radiation protective garments for an extended time; however, the main focus in the promotion of radiation-shielding materials should still be on their attenuation efficacy against both the primary and the scattered X-rays present in medical environments. The end users should be informed on the material attenuation in an extended energy range, especially in the range where scatter radiation occurs, and not just about the peak material attenuation performance at energies where the X-rays are generated. Scatter radiation is the main reason for the occupational radiation exposure of medical personnel, who should have the whole picture about the shielding ability of the protective garments that they strongly rely on. Full article

Acinetobacter baumannii is a critically hard-to-treat gram-negative pathogen responsible for a range of infectious diseases. Tigecycline is a last-resort antibiotic for A. baumannii infection; however, tigecycline-resistant (TIG-R) A. baumannii has been increasingly reported. Therefore, new strategies must be developed to treat these detrimental infections. Nanoantibiotics composed of two-dimensional (2D) black phosphorus (BP) and its derived nanocomposites have emerged as excellent alternatives to current antibiotics. However, the development of unique materials to target specific pathogens is challenging. Here, we report the preparation of a BP-based ZnO-Ag (ZPBA) nanocomposite. A low-temperature solution synthesis method was used to prepare ZnO and Ag nanoparticles immobilized on BP nanosheets. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the ZPBA nanocomposite. The antibacterial activity of ZPBA nanocomposite was assessed by determining its minimum inhibitory concentration against type (ATCC 19606, ATCC 15150) and TIG-R (ATCC 19606-R) A. baumannii strains. From the assays, ZPBA showed superior activity against TIG-R A. baumannii strain with MIC of 12.5 µg·mL⁻¹ compared to all other prepared samples. Finally, the combination of bacterial membrane disruption and ROS generation was demonstrated to be a potential antibacterial mechanism of ZPBA. Our results show that ZPBA could be a potential nanoantibiotic platform for eradicating TIG-R A. baumannii. Full article

Polyester coatings containing metal-organic framework (MOF) corrosion inhibitors were studied for their ability to protect carbon steel. The polyester coating was synthesized in the laboratory using microwave (MW) radiation to polycondense soy fatty acids, phthalic anhydride, and pentaerythritol-type polyols. The incorporation of these inhibitors into the polyester coating altered the behavior of the carbon steel, resulting in enhanced corrosion protection compared with uncoated carbon steel and polyester alone. Polyester with a 49% oil content, prepared using fatty acids from soybeans, phthalic anhydride, and pentaerythritol synthesized under microwave irradiation, and with a content of 3 mM Mg(GLY), exhibited a notable enhancement in the anticorrosive properties of the alkyd coating. The inhibition mechanism of corrosion was investigated through electrochemical impedance spectroscopy analysis. Full article

The paper presents a reliable technology combining sol–gel synthesis and spark plasma sintering (SPS) to obtain SrTiO₃ perovskite-type ceramics with excellent physicomechanical properties and hydrolytic stability for the long-term retention of radioactive strontium radionuclides. The Pechini sol–gel method was used to synthesize SrTiO₃ powder from Sr(NO₃)₂ and TiCl₃ (15%) precursors. Ceramic matrix samples were fabricated by SPS in the temperature range of 900–1200 °C. The perovskite structure of the synthesized initial SrTiO₃ powder was confirmed by X-ray diffraction and thermal analysis results. Scanning electron microscopy revealed agglomeration of the nanoparticles and a pronounced tendency for densification in the sintered compact with increasing sintering temperature. Chemical homogeneity of ceramics was confirmed by energy dispersive X-ray analysis. Physicochemical characteristic studies included density measurement results (3.11–4.80 g·cm⁻³), dilatometric dependencies, Vickers microhardness (20–900 HV), and hydrolytic stability (10⁻⁶–10⁻⁷ g·cm⁻²·day⁻²), exceeding GOST R 50926-96 and ISO 6961:1982 requirements for solid-state matrices. Ceramic sintered at 1200 °C demonstrated the lowest strontium leaching rate of 10⁻⁷ g/cm²·day, optimal for radioactive waste (RAW) isolation. The proposed approach can be used to fabricate mineral-like forms suitable for RAW handling. Full article

In this study, the research investigates the prediction of fatigue life for Functionally Graded Materials (FGM) specimens comprising Polylactic acid (PLA) and Thermoplastic Polyurethane (TPU). For this, Machine learning (ML) techniques, including Random Forest (RF), Support Vector Machine (SVM), and Artificial Neural Network (ANN) are utilized. A predictive in-house code is developed for each technique, thereby facilitating the fatigue performance of layered deposited specimens subjected to varying cyclic loadings. In order to verify the effectiveness of the ML technique, a comparative analysis among all is reported based on empirically determined fatigue life obtained values. RF is proven to be the most suitable technique with minimal error percentage in obtained results with optimally synchronized data sets in a minimum time frame. Subsequently, the application of ML in those predictions is reported for future aspects in augmenting the operational efficiency associated with fatigue life prediction. Full article

Water-soluble soy protein (SP), which contains many acidic amino acids in its structure, was complexed by mixing with a silane coupling agent, 3-glycidoxypropyltrimethoxysilane (GPTMS). These SP−GPTMS composite materials showed stability in water. This property is due to the cross-linking between SP and GPTMS through the ring cleavage reaction of the epoxy group in the GPTMS molecule and an encapsulation of SP into the 3D siloxane network of GPTMS. When the SP−GPTMS composite material was immersed in an aqueous Cu(II) ion solution, the composite material changed from light brown to blue green by the coordination of Cu(II) ions into the SP. Hence, we evaluated the accumulation of heavy ions, rare-earth ions, and light metal ions. The accumulating affinity of metal ions was Cd(II) << Zn(II), Cu(II), Pb(II) < La(III) < Al(III) < Nd(III), In(III) << Mg(II) < Ca(II) ions. In addition, the sorption capacities of Ca(II), Mg(II), In(III), Nd(III), Al(III), La(III), Pb(II), Cu(II), Zn(II), and Cd(II) ions were 700 nmol/mg, 660 nmol/mg, 470 nmol/mg, 470 nmol/mg, 410 nmol/mg, 380 nmol/mg, 350 nmol/mg, 350 nmol/mg, 300 nmol/mg, and 200 nmol/mg, respectively. These properties suggest that the SP−GPTMS composite material has a divalent light metal ion selectivity. Additionally, the accumulative mechanism of the light metal ions was related to the carboxylate group and the hydroxyl group in the composite material. Full article

The use of dental resin composites adapted to computer-aided design/computer-aided manufacturing (CAD/CAM) processes for indirect tooth restoration has increased. A key factor for a successful tooth restoration is the bond between the CAD/CAM composite crown and abutment tooth, achieved using resin-based cement. However, the optimal pairing of the resin cement and CAD/CAM composites remains unclear. This study aimed to identify the optimal combination of a CAD/CAM composite and resin cement for bonding. A commercial methyl methacrylate (MMA)-based resin cement (Super-Bond (SB)) and four other composite-based resin cements (PANAVIA V5; PV, Multilink Automix (MA), ResiCem EX (RC), and RelyX Universal Resin Cement (RX)) were tested experimentally. For the CAD/CAM composites, a commercial polymer-infiltrated ceramic network (PICN)-based composite (VITA ENAMIC (VE)) and two dispersed filler (DF)-based composites (SHOFU BLOCK HC (SH) and CERASMART300 (CE)) were used. Each composite block underwent cutting, polishing, and alumina sandblasting. This was followed by characterization using scanning electron microscopy, inorganic content measurement, surface free energy (SFE) analysis, and shear bond strength (SBS) testing. The results demonstrated that the inorganic content and total SFE of the VE composite were the highest among the examined composites. Furthermore, it bonded highly effectively to all the resin cements. This indicated that PICN-based composites exhibit unique bonding features with resin cements. Additionally, the SBS test results indicated that MMA-based resin cement bonds effectively with both DF- and PICN-based composites. The combination of the PICN-based composite and MMA-based resin cement showed the best bonding performance. Full article

A method has been developed for producing an epoxy composition based on a low-viscosity epoxy-resorcinol resin, a phosphazene-containing curing agent, isophoronediamine, and thermally expanded graphite as a filler. The degree of cure and the absence of side reactions during the curing process were confirmed using IR spectroscopy. The influence of the content of phosphazene-containing curing agent and filler on the physico-mechanical properties of the composition, its fire resistance, and antistatic properties were studied. Using the UL-94 HB horizontal burning test, it was found that the addition of 10 and 20 wt. % phosphazene-containing curing agent (relative to isophoronediamine) reduces the burning speed by 10 times compared to a sample without phosphazene. The addition of a filler to a composition containing phosphazene reduces the burning speed by 25 times compared to a composition without phosphazene and imparts antistatic properties to the epoxy composition, as evidenced by the specific volume electrical resistance of the order of 10¹ Ohm·m. Phosphazene-containing curing agent had no statistically significant effect on specific volume electrical resistivity (p > 0.05). Tests of physico-mechanical and adhesive properties (tensile strength, compressive strength, water absorption, water solubility, abrasion resistance, and adhesive strength) of filled epoxy compositions with 10 and 20 wt. % phosphazene-containing curing agent demonstrated that these properties met the requirements for floor coverings in construction and parts of electrical devices. Full article

In the present work, para-aramid fabrics (p-AF) were physically modified via an anchoring process of 0.05 wt% MWCNT to the aramid fiber surfaces by coating the MWCNT/phenolic/methanol mixture on p-AF, and then by thermally curing phenolic resin of 0.01 wt%. Para-aramid fabric-reinforced vinyl ester (p-AF/VE) composites were fabricated using p-AF/VE prepregs by compression molding. The effect of MWCNT anchoring on the thermo-dimensional, thermal deflection resistant, dynamic mechanical, mechanical, and impact properties and the energy absorption behavior of p-AF/VE composites was extensively investigated in terms of coefficient of linear thermal expansion, heat deflection temperature, storage modulus, tan δ, tensile, flexural, and Izod impact properties and a drop-weight impact response. The results well agreed with each other, supporting the improved properties of p-AF/VE composites, which were attributed to the effect of MWCNT anchoring performed on the aramid fiber surfaces. Full article

Asphalt is widely employed in road construction due to its durability and ability to withstand heavy traffic. However, the disposal of waste polymers has emerged as a significant environmental concern. Recently, researchers have used polymer waste to modify asphalt pavements as a new approach. This approach aims to improve pavement performance and address the environmental concerns of polymer waste. Researchers have demonstrated that incorporating polymeric waste into asphalt mixtures can lead to performance improvements in asphalt pavements, particularly in mitigating common distresses including permanent deformation and thermal and fatigue cracking. The current comprehensive review aims to summarize the recent knowledge on the usage of waste polymers in asphalt mixtures, encompassing their impact on performance properties and mixture design. The review also addresses different types of waste polymers, their potential benefits, challenges, and future research directions. By analyzing various studies, this review offers insights into the feasibility, effectiveness, and limitations of incorporating waste polymers into asphalt mixtures. Ultimately, this contributes to the advancement of sustainable and environmentally friendly road construction practices. Full article