J. Compos. Sci., Volume 8, Issue 7 (July 2024) – 13 articles

Researchers have extensively studied borate bioactive glass (BBG) for bone regeneration and wound healing applications. In the current study, 13-93B3 (54.6% B₂O₃, 22.1% CaO, 7.9% K₂O, 7.7% MgO, 6.0% Na₂O, and 1.7% P₂O₅) was synthesized using a sol–gel technique and doped with different molar concentrations of Cu (0.01, 0.05, and 0.25 M) into BBG for possible biomedical applications. Then, the antibacterial activity was tested against E. coli and S. aureus. The maximum zone of inhibition against S. aureus was achieved at 100 μg/mL of 0.25 M Cu-doped BBG. At 50 μg/mL of 0.25 molar copper concentration, E. coli showed a significant reduction in colony-forming units. Hydroxyl radical production, influenced by the BBG powder, was most effective against S. aureus, followed by E. coli. Protein leakage studies demonstrated significant leakage after treatment with BBG powder, demonstrating a strong effect on bacterial strains. This shows a change in protein synthesis, which is essential for central metabolism and gene transcription, affecting proteins in the periplasm and inner and outer membranes. Furthermore, carbohydrate leakage studies showed that BBG is effective against all three categories of cellular carbohydrate, namely membrane-bound, transmembrane, and intracellular carbs. This study focuses on the diverse antibacterial processes of Cu-doped BBG, which has emerged as a promising contender for biological applications that require strong antibacterial characteristics. Full article

In the present work, an innovative range of foams based on flax gum-filled epoxy resin was developed, reinforced or not by flax fibers. Foams and composites with different gum and epoxy resin contents were produced and their mechanical and thermal performances were characterized. To enhance the organic flax gum filler’s cross-linking, we exploited the oxidized components’ reactivity with the amine hardener (isophorone diamine). We compared the materials obtained with those derived from the native components. The flax gum and fibers were primarily characterized by chemical analysis, NMR, and FTIR to evaluate the mild oxidation of the native materials. The formation of chemical bonds between the oxidized polymer chains, epoxy resin, and hardener was evidenced by FTIR, and the materials were then studied by SEM and X-ray computed micro-tomography (CT) and submitted to mechanical and thermal tests. The relevance of the oxidation treatment was highlighted through a significant increase in density and mechanical performance (+36% and +81%, respectively, for the 100% flax gum material). The positive effect of the flax fibers on homogeneity evidenced through micro-CT analysis was also clearly addressed. This set of promising results paves the way for the future development of fully flax-based insulation composite materials. Full article

The emergence of 2D materials has significantly expanded the wide range of nanomaterials with diverse applications. Notably, their high conductivity, catalytic efficiency, and hydrophobicity have fueled heightened research interests for water treatment applications. This research aimed to investigate the synthesis and characterization of MXene and reduced graphene oxide (rGO) nanocomposites with silver nanoparticles (Ag) for enhanced catalytic activity in the decomposition of Direct Blue-24 dye. In this study, we employed well-established methods, previously documented in the literature, to prepare two distinct nanocomposites. Novel nanocomposites, namely reduced graphene oxide–silver nanoparticles (rGO–Ag) and MXene–silver nanoparticles (MXene–Ag), were synthesized using the hydrothermal and direct reduction method with an ammoniacal solution (aqueous solution). Comprehensive characterization using advanced tools revealed that the introduced Ag particles integrated seamlessly onto the parent nanofilms of the Carbon derivatives, forming a secondary phase with enhanced catalytic functionality. These nanocomposites demonstrated significant improvements in the catalytic decomposition reactions in simulated wastewater. Verification involved the reduction reaction of Direct Blue-24 dye at known nanocomposite concentrations. The results indicated that MXene–Ag exhibited a superior catalytic activity of 98% in 10 min compared to the rGO–Ag nanocomposite films, which achieved 96% in 35 min. The results indicated that MXene–Ag nanocomposites exhibited a 20–25% increase in catalytic efficiency compared to the rGO–Ag nanocomposites. The outcomes of this research hold promise for practical applications in textile wastewater management and various industrial sectors dealing with mutagenic and carcinogenic chemicals containing azo and/or phthalocyanine products. Full article

Fiber-reinforced laminates with flexibility (FRLs) are becoming increasingly crucial across diverse sectors due to their adaptability and outstanding mechanical attributes. Their ability to deliver high performance relative to their weight makes them indispensable in lighter-than-air (LTA) applications, such as aerostats, inflatable antennas, surge bladders, gas storage balloons, life rafts, and other related uses. This research delved into employing woven fabrics as the reinforcement material and explored how their specific parameters, like fiber type, fabric count (warp thread density × weft thread density), fabric areal density, and fabric cover influence the bonding and mechanical properties of laminates. A thorough analysis encompassing standard T-peel (ASTM standard D1876) and a newly proposed yarn pullout in laminate test were conducted on laminates fabricated with various woven reinforcements, each with its unique specifications. The T-peel test was utilized to gauge the adhesive strength between FRL components, offering crucial insights into interfacial bonding within the laminates. Nevertheless, challenges exist with the T-peel test, including instances where the adherents lack the strength to withstand rupture, resulting in unsuccessful peel propagation and numerous outliers that necessitate costly additional trials. Thus, our research group introduced a novel yarn pullout in laminate test to accurately assess adhesion in FRLs. This study uncovered correlations between both adhesion tests (T-peel and yarn pullout in laminate), indicating that the innovative yarn pullout in laminate test could effectively substitute for characterizing adhesion in FRLs. Furthermore, the findings unveiled a complex relationship between woven fabric specifications and laminate properties. We noted that variations in fiber type, yarn linear density, and adhesive type significantly impacted adhesion strength. For instance, Kevlar exhibited markedly superior adhesion compared to Ultra-High Molecular Weight Polyethylene (UHMWPE) when paired with Thermoplastic Polyurethane (TPU) adhesive, whereas UHMWPE demonstrated better adhesion with Ethylene Vinyl Acetate (EVA). Moreover, the adhesion quality lessened as fabric count increased for the same adhesive quantity. These discoveries carry practical implications for material selection and design across industries, from automotive to aerospace, offering avenues to enhance FRL performance. Full article

Global poultry waste production is substantial, with billions of poultry raised annually for meat and egg production, resulting in significant feather waste. Conventional poultry waste disposal methods are restricted due to environmental concerns. Meanwhile, wood-composite panel industries face raw material shortages, emphasizing the need for sustainable, renewable fiber sources. In this study, in the core layer of panels, wood particles were replaced with 5 wt% clean duck feathers without pretreatment to take advantage of feather attributes like hydrophobicity, thermal insulation, and sound damping as an alternative construction material. Three adhesives—urea-formaldehyde (UF), polymeric 4,4′-diphenylmethane diisocyanate (pMDI), and polyvinyl acetate (PVAc)—were examined for resin–feather compatibility. The control panels in this study were identical but wood was not replaced with feathers. The results revealed that wood–feather particleboard with pMDI and PVAc resins meets the requirements of the relevant standard for P2 boards (where applicable) concerning their modulus of rupture (MOR: 11 N·mm⁻²), modulus of elasticity (MOE: 1600 N·mm⁻²), internal bond (IB: 0.35 N·mm⁻²), and screw withdrawal resistance (SWR). However, those produced with UF resin did not meet the standards for IB and MOE. Furthermore, the physical properties showed similar water resistance and thickness swelling to control panels with pMDI. Notably, substituting 5 wt% wood with feathers improved thermal insulation by approximately 10% for UF and pMDI resins. Additionally, particleboard with feathers demonstrated improved sound absorption at high frequencies, ranging from 2500 to 500 Hz, particularly with pMDI resin, approaching Class B classification according to EN ISO 11654:1997. This study identifies the higher compatibility of pMDI over PVAc and UF adhesives for feather-based composite materials in construction applications. Full article

Typically, polymer composites and ceramics are used to create biosensors. Materials with properties that are ideal for biosensors and chemical sensors include AgNO₃ (silver nitrate), PVDF (polyvinylidene fluoride), and HA (hydroxyapatite). Polyvinylidene fluoride (PVDF) polymer has been widely used in several applications because of its well-known superior ferroelectric characteristics and biocompatibility. The brittleness and low bending strength of hydroxyapatite limit its applicability. Several HA and polymer composite formulations have been developed to compensate for HA’s mechanical weakness. The final product contains a significant amount of HA, making HA/polymer composites highly biocompatible. When the right amount of silver is deposited, the maximum piezoelectric activity is generated, and silver nitrate has antimicrobial properties. The non-toxic solvent DMSO (dimethyl sulfoxide) and the solvent casting method were chosen for the preparation of the film. Surface roughness was chosen to measure the Str and Sdr properties of the thin film. For liquid preparation, the multifractal spectra analysis was chosen for each sample. SEM was used to examine the samples morphologically. EDX and mapping analyses were presented for chemistry distribution in the samples. Full article

The water–gas shift (WGS) performance of 10%Ni/Al₂O₃, 20%Ni/Al₂O₃ and 10%Ni/CaO-Al₂O₃ catalysts was studied to reduce CO concentration and produce extra hydrogen. Ni was added onto the Al₂O₃ support by an impregnation method. The physicochemical properties of nickel catalysts that influence their catalytic activity were examined. The most influential factors in increasing the CO conversion for the water–gas shift reaction are Ni dispersion and surface acidity. Ni metal sites were identified as the active sites for CO adsorption. The main effect of nickel metal was reducing the adsorbed CO amount by reducing the active site concentration. The 10%Ni/Al₂O₃ catalyst was more active for the WGS reaction than other catalysts. This catalyst presents a high CO conversion rate (75% CO conversion at 800 °C), which is due to its high Ni dispersion at the surface (6.74%) and surface acidity, thereby favoring CO adsorption. A high Ni dispersion for more surface-active sites is exposed to a CO reactant. In addition, favored CO adsorption is related to the acidity on the catalyst surface because CO reactant in the WGS reaction is a weak base. The total acidity can be evaluated by integrating the NH₃-Temperature-Programmed Desorption curves. Therefore, an enhancement of surface acidity is identified as the favored CO adsorption. Full article

Concrete-filled built-up cold-formed steel (CFS) columns offer enhanced load-carrying capacity, improved strength-to-weight ratios, and delayed buckling through providing internal resistance and stiffness due to the concrete infill. Integrating sustainable alternatives like self-compacting geopolymer concrete (SCGC) with low carbon emissions is increasingly favoured for addressing environmental concerns in construction. This review aims to explore the current knowledge regarding CFS built-up composite columns and the performance of SCGC within them. While research on geopolymer concrete-filled steel tubes (GPCFSTs) under various loads has demonstrated high strength and ductility, investigations into built-up sections remain limited. The literature suggests that geopolymer concrete’s superior compressive strength, fire resistance, and minimal shrinkage render it highly compatible with steel tubular columns, providing robust load-bearing capacity and gradual post-ultimate strength, attributed to the confinement effect of the outer steel tubes, thereby preventing brittle failure. Additionally, in built-up sections, connector penetration depth and spacing, particularly at the ends, enhances structural performance through composite action in CFS structures. Consequently, understanding the importance of using a sustainable and superior infill like SCGC, the cross-sectional efficiency of CFS sections, and optimal shear connections in built-up CFS columns is crucial. Moreover, there is a potential for developing environmentally sustainable built-up CFS composite columns using SCGC cured at ambient temperatures as infill. Full article

The aim of this study is to assess the effect of shade and light-curing intensity on the heat generation and degree of conversion of bulk-fill composite. A commercially available bulk-fill composite resin was used in this study. A total of 250 cylindrical specimens of each composite shade (n = 25/group) were prepared (125 for testing heat generation and 125 for testing degree of conversion, then cured using a monowave light-curing unit (LCU) with a single light intensity of 1470 mW/cm² and a polywave LCU with three different light intensities (1200, 2000, and 3000 mW/cm²). Heat generation during polymerization was measured by five K-type thermocouples placed in each 1 mm layer from top to bottom. FTIR was used for evaluating the degree of conversion. Regarding heat generation, significant differences were seen in layers 4 and 5. Curing types and times also showed significant impacts on heat generation and the degree of conversion. Heat generation relates more to curing time than light intensity. Darker shades generate and retain more heat. Lighter shades exhibit higher degrees of conversion with longer curing. Full article

This study investigated the influence of fiber loading and maleated polyethylene (MAPE) coupling agent on the structural, thermal, mechanical, morphological properties, and torque rheology of high-density polyethylene (HDPE) reinforced with Posidonia oceanica fiber (POF) composites. HDPE/POF composites, both with and without MAPE, were manufactured using a two-step process: composite pellets extrusion, followed by test samples injection molding with various POF loadings (0, 20, 30, and 40 wt%). HDPE/POF composites reinforced with higher loading of POF (40 wt%) exhibit superior stiffness, better crystallinity, and higher stabilized torque and mechanical energy (E_m) compared to other composite formulations. Therefore, varying the POF loading leads to extrusion and injection processing variations. Furthermore, the coupling agent significantly enhances the tensile strength, ductility, impact strength, crystallinity, stabilized torque, and E_m of the HDPE/POF composite. This improvement is due to the enhanced interfacial adhesion between the POF and the HDPE matrix with the addition of the MAPE, as supported by the Scanning Electron Microscopy (SEM) micrographs. Full article

In the study, based on the model of acoustic emission during the destruction of a composite material by shear force according to the Von Mises criterion, the effect of non-uniformity of the destruction process on the generated acoustic emission signal is simulated. The study under the accepted modeling conditions allows us to determine the patterns of changes in the amplitude envelope of acoustic emission signals at various stages of developing processes. In theoretical and experimental studies of acoustic emission signals when searching for patterns in their parameter changes and developing methods for monitoring or diagnosing the state of composite materials, the problem lies in the interpretation of recorded information. This issue arises from the complexity and diversity of processes occurring in the material structure at micro and macro levels, and the high sensitivity of the acoustic emission method to these processes, wherein structural changes lead to observable alterations in the characteristics of acoustic emissions. Solving this problem requires both theoretical and experimental studies to understand the influence of various factors on the characteristics of the generated acoustic emission. The results of the presented study can be used to assess the condition of composite materials and structures, such as bridges, e.g., in terms of defectiveness, property dispersion, damage during operation, and other characteristics. Full article

Industrialization and globalization have caused severe environmental problems, such as contaminating water bodies by toxic agents from various industries, generating a significant loss of biodiversity and health risks. Globally, approximately 80% of wastewater is discharged without treatment, worsening the situation. However, in Colombia, initiatives have been taken to improve wastewater management, with ambitious investments and targets to improve treatment infrastructure. Recently, advanced technologies have been developed to treat wastewater, including more efficient and sustainable biological methods, such as using coconut-derived adsorbent biomaterials, rich in useful properties for the adsorption of pollutants in solutions. This research focuses on developing a composite biomaterial using cellulose acetate (CA) extracted from coconut mesocarp and polyhydroxy butyrate (PHB), by the casting method, to treat wastewater. Adsorption tests with the tracer methylene blue (MB) were carried out in the Energy and Environment laboratory of the University of Cartagena. For this, MB solutions were prepared with 5 to 50 ppm concentrations. The analyses showed that the composite biomaterial is thermally stable and has good homogeneity and porosity. At a concentration of 40 ppm and a dosage of 10 mg of adsorbent, the adsorption efficiency was 89%, with an adsorption capacity of 35.98 mg/g. The above indicates that the composite biomaterial is presented as a sustainable, improved, and efficient solution to remove contaminants from wastewater, benefiting the environment and human health. Full article

The conventional manufacturing chain for technical ceramics is too expensive for the production of small series or unique parts with complex designs. Hybrid machines that combine additive and subtractive processes can be an interesting solution to overcome this technology lock-in. However, despite the great interest in hybrid machines for metallic parts, there is a lack of data in the literature when it comes to ceramics. The purpose of this paper is to contribute to closing this gap. It is the first to evaluate the achievable geometrical tolerances according to ISO 2768-2 as well as the surface textures of composite zirconia parts shaped sequentially by pellet additive manufacturing (PAM, from ceramic injection molding feedstock) and finish milling. The green parts were then debinded and sintered to analyze the influence of these steps. Compared to the initial green parts, the sintered parts exhibited shiny and smooth surfaces with sharp edges. Flatness, parallelism and perpendicularity all achieved an H (fine) class, while the surface textures were significantly improved, resulting in arithmetic roughness (Ra) below 1.6 µm. Full article