Papers by Keyword: Composites

Abstract: WO₃-based composite photocatalysts supported on tungsten disulfide (WS₂), urea, melamine, and graphene nanoplatelets (GNPs) were synthesized and characterized. The SEM micrographs showed that the support materials had a major impact on the composites' shape. While WO₃/WS₂ created layered sheets with scattered nanoparticles, WO₃/melamine and WO₃/urea showed porous and uneven morphologies. Strong interfacial contact was demonstrated by the homogeneous distribution of tiny WO₃ particles on crumpled graphene layers in WO₃/GNPs. W and O from WO₃, as well as S, N, and C elements from the corresponding supports, were verified by EDX. Methyl orange (MO) degradation under light irradiation was used to assess photocatalytic activity. Because of its huge surface area and improved electron mobility, WO₃/GNPs showed the highest degrading efficiency. The WO₃/WS₂ also displayed encouraging activity efficient due to the interfacial charge separation. On the other hand, WO₃/urea and WO₃/melamine performed moderately, most likely as a result of agglomeration and less conductive supports. With WO₃/GNPs emerging as a promising choice for dye degradation and wastewater treatment applications, these findings emphasize the importance of support materials in enhancing WO₃-based photocatalysts.

Abstract: Industrialization has led to widespread aquatic contamination, with dyes being among the most prominent pollutants found in various water bodies. Major contributors to dye pollution include the textile, printing, leather, cosmetics, and chemical industries, with the textile industry alone being responsible for approximately 13% of the dyes released into aquatic environments. This study focuses on comparing the photocatalytic degradation performance of synthesized catalysts prepared in the presence of biopolymers. Pullulan was selected as a capping agent to aid the synthesis process and promote the formation of nanosized catalysts. Three types of catalysts, namely copper oxide, zinc oxide, and a composite of both, were synthesized, and their performance was evaluated through the photocatalytic degradation of methylene blue. Among the three, zinc oxide demonstrated the highest degradation efficiency (99%), followed by the composite (27%), while copper oxide exhibited negligible photocatalytic activity (14%). Further optimization of the best-performing catalyst (zinc oxide) was conducted by varying parameters such as catalyst dosage (0.05-0.15g) and solution pH (5-9). The results showed that zinc oxide achieved the highest degradation under acidic conditions (pH 5) with a dosage of 0.15 g, requiring only 70 minutes to reach nearly 100% degradation. Overall, this study provides valuable insights into the influence of catalyst type on the photocatalytic degradation of methylene blue.

Abstract: High-performance thermoplastic polymers paved the way for new fast manufacturing pro-cesses, including welding. In order to obtain optimal bonding of the substrates, an adhesion step isrequired, governed by two main phenomena : intimate contact and healing. While healing has beenvastly explored, theorized and starts to be understood, prediction and characterization of the degree ofintimate contact is still a challenge. After a review of squeeze flow models for intimate contact, alongwith the expressions of the analytical solutions for a Newtonian and a shear-thinning fluid modeled bypower law, a finite element model is presented in order to observe the influence of asperity geometry,fluid behavior, and other assumptions on the evolution of the degree of intimate contact.

Abstract: Rapid urbanization, economic expansion and population growth have led to a significant increase in global solid waste production, which threatens ecosystems, depletes natural resources, and negatively affects human health. Textile waste has reached 150 million tons per year and constitutes a significant portion of this growing waste stream. At this point, interest in the use of recycled materials as an alternative raw material has increased, and composite materials have emerged as a promising area for the evaluation of textile waste, offering sustainable solutions for resource recovery and waste management. In this study, hybrid composites are developed by introducing various fibrous waste groups (denim and human hair) and bio-resin (acrylated epoxidized soybean oil, AESO) to E-glass reinforced epoxy composites, and the effects of waste type and bio-resin addition on the flexural strengths of the structures are examined using a full factorial experimental design. In this regard, three different sandwich structures are designed, with the outer layers made of E-glass woven fabric and the middle layers made of either E-glass fabric for control samples or different waste groups, and the productions are carried out using the vacuum infusion method. Pure epoxy or an epoxy system with 30% AESO additive is used as matrix material. Statistical results indicate that reinforcement type has a huge effect on the flexural properties individually and in binary interactions of of other factors. The performance results show that the flexural strength is improved with addition of waste regardless of their type and the best flexural properties are seen in samples with denim waste reinforcement containing cotton fiber, while the addition of AESO appears to have a negative effect. The composite structures developed within this study have the potential to replace particle boards, thus contributing to solid waste management and producing innovative solutions to resource scarcity.

Abstract: The Philippines is facing environmental challenges due to the increasing plastic waste and crop residues. To address this issue and enhance the country's economy while ensuring sustainability, research and the effective development of waste utilization strategies are paramount. This study focuses on the fabrication, characterization, and testing of fiber-polymer composites using corn cob pith particles and recycled polypropylene. Corn cob pith particles (CCP) at varying filler loadings (5, 10, and 15 wt.%), recycled polypropylene (RPP), and maleic anhydride grafted polypropylene (MAPP) were combined using a single screw extruder. As a result, the incorporation of CCP particles demonstrated a significant increase in flexural strength, flexural modulus, and tensile modulus with highest values reaching 21.88 MPa, 437.19 MPa, and 239.61 MPa, respectively. The significant increase in flexural strength and flexural modulus was observed at 10% loading, for tensile modulus it was at 15% loading. On the other hand, tensile decreased with the lowest value of 19.24 MPa at 15% loading. Moreover, the composites exhibited better thermal stability than RPP. Furthermore, the FTIR peaks located at1033 cm⁻¹ and 3340 cm⁻¹ confirm the incorporation of CCP particles into the RPP matrix. Overall, adding CCP particles to RPP, using a compatibilizer, enhanced the stiffness and rigidity of the composite, as well as its fiber-polymer adhesion. Industries can utilize the composite in applications requiring stiffness and rigidity.

Abstract: Steel is the most used material for concrete reinforcement; however, it performs poorly in aggressive environments (e.g. coastal areas) owing to corrosion (moisture and chlorides). This study aims to analyse the tensile strength of steel and glass fibre-reinforced polymer (GFRP) bars through laboratory testing to assess their feasibility and application in construction. Steel bars were tested by ASTM E8/E8M–22, obtaining values of 606.61 MPa (Ecuador) and 676.46 MPa (Peru), whereas GFRP bars were tested following ASTM D7205/D7205M–21 (1,000 MPa). The analysis indicated that GFRP bars offer structural advantages (suitable for elements in coastal zones with low to moderate seismic activity), environmental benefits (lower CO₂ emissions during production), and enhanced durability (corrosion resistance).

Abstract: The choice of materials for mechanical or civil engineering applications depends on both structural and mechanical characteristics. The latter is more important as the material is intended to support loads that force it to undergo both transverse and longitudinal deformations. The aim of this study is to analyze the three-point bending behavior in the specimen condition of virgin or recycled polyethylene/eucalyptus fiber composites. However, two types of composites were formulated, and bending tests were carried out to determine the deformation characteristics following an applied stress. The elastic modulus E, which characterizes the stiffness or flexibility of the material, was discussed and the results compared between virgin and recycled LDPE matrix composites. Virgin low-density polyethylene (LDPE_V) matrix composites showed better flexural strength than recycled matrix (LDPE_R) composites. On the other hand, Charpy impact strength showed that recycled low-density polyethylene (LDPE_R) matrix composites had better impact strength than virgin low-density polyethylene (LDPE_V) matrix composites.

Abstract: Flax fibre–reinforced polymers (FFRPs) are attractive for lightweight structures due to their low density, favourable specific stiffness and partially bio-based origin. However, their performance is strongly affected by manufacturing route, porosity and moisture uptake, which are typically more critical than for conventional glass or carbon fibre composites. This study compares flax, glass, carbon and carbon–flax hybrid epoxy laminates produced by vacuum infusion, hand lay-up and autoclave prepreg processing. Fibre volume fraction and void content are determined from density measurements, optical microscopy and X-ray computed tomography. Tensile and flexural properties are measured according to EN ISO 527-4 and EN ISO 14125 in the dry state and after accelerated conditioning at 35 ± 2 °C and 100 % relative humidity. Infused unidirectional flax laminates reach a tensile strength of about 259 MPa and a specific tensile strength of approximately 0.21 MPa·m³·kg⁻¹, comparable to glass laminates. Moisture exposure increases thickness by 11.8–13.9 % for infused flax laminates and about 2.3 % for an infused carbon–flax hybrid laminate and leads to strength reductions up to roughly 30 % in flax-rich laminates, while autoclave-processed laminates show only minor losses. The results provide process-dependent design guidelines for FFRPs in moisture-exposed, weight-sensitive components.

Abstract: The research is concerned with obtaining basic knowledge in the field of machining biocomposite materials with hemp fibers and a matrix in the form of a mixture of polyester and methyl methacrylate resin in a secret ratio. The research was focused on milling technology, or rather side milling. For the needs of the research, 3 milling tools were selected with which experimental measurements were performed. Each tool was different in its type of sharpened geometry, both standard and specialized, including one coated. The experimental measurements focused on the size and course of wear of the cutting edge of the tools, the roughness value of the machined surface and the size and type of delamination of the upper and lower layers of the biocomposite material under investigation. The obtained results helped to evaluate the machinability of the selected hemp biocomposite and at the same time determined the future direction of research with regard to the design of a suitable cutting geometry of the tool and the overall optimization of the machining process during side milling.

Abstract: The purpose of this study is to compare the impact strength of epoxy composites made of basalt fiber reinforced polymer (BFRP) with those that have nanoclay filler. The matrix materials were Epoxy resin (LY556) and Hardener (HY951), the reinforcing material was basalt fiber, and the filler was warmed montmorillonite nanoclay with a volume percentage of 4%. nanoclay was preheated to 45°C for 40 minutes. The fiber of basalt The control group is epoxy composite (N=20). An experimental group (N=20) of epoxy composite reinforced with basalt fiber and 4% nanoclay filler is created using the hand layup technique. The two groups samples are tested. Results are analyzed using the SPSS-V26 statistical tool, the basalt fiber with 4% volume fraction of warmed nanoclay filler epoxy composite shows the better impact strength, the mean significant difference is p<0.048. The impact strength of BFRP composites containing 4% volume fraction of nanoclay is 9.14% higher than that of BFRP composites without filler, according to the study's limitations.