Composite Materials Research Articles

COMPOSITE MATERIALS FOR STRENGTHENING OF REINFORCED CONCRETE STRUCTURES – A REVIEW

This article presents a study of the use of composite materials in strengthening building structures. Materials consisting of two or more components or phases are called composite. Now modern composite materials open up new opportunities for design in all areas of production. The construction industry is no exception. Laminates, canvases, nets, rebars and ropes made of high-strength fibers of various origins are among the most widely used in construction at the moment. The main components of any composite are high-strength fibers that absorb the load, and a stabilizing matrix that serves to transfer forces to the fibers. The following types of high-strength fibers are used in composites: glass fibers, carbon fibers, organic fibers, silicon-carbon, aluminum-silicon fibers, and others. With the help of composite reinforcement, it is possible to effectively strengthen normal and inclined sections of reinforced concrete structures.

STRENGHENING OF RC BEAMS BY FRC AND FRP SYSTEMS – A REVIEW

The article examines studies on the reinforcement of reinforced concrete elements of cement -based fibro -based fibro systems (FRC) and polymers reinforcement fibro (FRP). Nowadays, the world economy, and with it, the construction industry is developing at a rapid pace. New materials, mechanization, construction equipment are emerging on the market. Due to this, modern structures impress with their shapes, scale and complexity of structures. The state of construction production in the country can be judged on the state of the economy of this country as a whole. Now the urgent issue in the world is the use of new composite materials in the strengthening of building structures. Such materials include non -metallic fittings, laminates, nets and canvases based on high -strength fibers. In this case, the own weight of fiber materials is slightly small. Only units of the above researchers performed enhancement of experimental samples under load, so the influence of the initial stress-deformed state on the work of the structure after amplification was practically not studied.

Structural and Viscoelastic Properties of Bacterial Cellulose Composites: Implications for Prosthetics

This study investigates the morphological, mechanical, and viscoelastic properties of bacterial cellulose (BC) hydrogels synthesized by the microbial consortium Medusomyces gisevii. BC gel films were produced under static (S) or bioreactor (BioR) conditions. Additionally, an anisotropic sandwich-like composite BC film was developed and tested, consisting of a rehydrated (S-RDH) BC film synthesized under static conditions, placed between two BioR-derived BC layers. Sample characterization was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), rheometry, and uniaxial stretching tests. To our knowledge, this is the first study to combine uniaxial and rheological tests for BC gels. AFM and SEM revealed that the organization of BC fibrils (80±20 nm in diameter) was similar to that of collagen fibers (96±31 nm) found in human dura mater, suggesting potential implications for neurosurgical practice. Stretching tests demonstrated that the drying and rehydration of BC films resulted in a 2- to 8-fold increase in rigidity compared to other samples. This trend was consistent across both small and large deformations, regardless of direction. Mechanically, the composite (BioR+S-RDH) outperformed BC hydrogels synthesized under static and bioreactor conditions by approx. 26%. The composite material (BioR+S-RDH) exhibited greater anisotropy in the stretching tests compared to S-RDH, but less than the BioR-derived hydrogels, which had anisotropy coefficients ranging from 1.29 to 2.03. BioR+S-RDH also demonstrated the most consistent viscoelastic behavior, indicating its suitability for withstanding shear stress and potential use in prosthetic applications. These findings should provide opportunities for further research and medical applications.

Embedment of Molybdenum Disulfide in Electrospun Fibers as an Integrated Cathode for Lithium-Ion Batteries

As an important component of LIBs, the electrode material plays a crucial role in determining the lithium (Li) storage performance in LIBs. In this study, MoS2 nano-flowers were synthesized using a one-pot hydrothermal method. The resulting MoS2 nano-flower, along with PAN, were used as raw materials for electrospinning. After annealing treatment, MoS2/(carbon nanofibers) CNFs nano-composites coated with carbon fibers were formed. The CNFs coating exhibited electrical conductivity and enhanced structural stability of the MoS2 due to the stabilizing effect of the carbon fibers. Additionally, electrochemical tests, including CV and GCD, indicated that the optimal capacity and cycling stability were achieved when the MoS2 content was 10%. The results indicated that the charge/discharge capacity of MoS2/CNFs-10% at a current density of 100 mA/g was ~650 mAh/g. After the cycling current returned to 100 mA/g, the current recovery was ~600 mAh/g, thereby indicating outstanding cycling stability. Accordingly, our fabrication technique and new insight could both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal sulfides in next-generation high-performance lithium-ion batteries.

Quantification of fungal biomass in mycelium composites made from diverse biogenic side streams

AbstractMycelium composite materials are comprised of renewable organic substrates interconnected by fungal mycelium, allowing full biodegradability after use. Due to their promising material properties, adaptability, and sustainable nature, these biomaterials are investigated intensively. However, one crucial aspect that has hardly been covered so far is the proportion of fungal biomass in the composites, which would be necessary to assess its contribution to the material characteristics. Since a complete physical separation of mycelium and substrate is not feasible, we approached this issue by isolating the fungal DNA and relating it to the mass of mycelium with the help of quantitative PCR. Overall, 20 different combinations of fungi and biogenic side streams were evaluated for their handling stability, and growth observations were related to the quantification results. Ganoderma sessile was able to form stable composites with almost all substrates, and a positive correlation between mycelial biomass and composite stability could be found. However, the amount of mycelium required for fabricating firm materials strongly depends on the combination of substrate and fungal species used. Less than five mass percent of fungal biomass can suffice to achieve this, as for example when combining Trametes versicolor with sugar beet pulp, whereas a mass fraction of twenty percent leads to crumbly materials when using Pleurotus pulmonarius on green waste. These results indicate that the mycelial biomass is an important factor for the composite’s stability but that the properties of the fungal hyphae, as well as those of the substrate, are also relevant. The presented quantification method not only allows to estimate fungal growth during composite production but can also improve our understanding of how the mycelium influences the material.

A Semi-implicit Stochastic Multiscale Method for Radiative Heat Transfer Problem in Composite Materials

A Semi-implicit Stochastic Multiscale Method for Radiative Heat Transfer Problem in Composite Materials

Investigation of Impact Behaviour of Sisal Fiber Reinforced Phenol Formaldehyde Composites

Short Sisal fiber reinforced Phenol Formaldehyde resin composites are prepared with varied fiber lengths (5 mm and 10 mm) and for varied weight fraction (20%, 25% and 30%) of the fibers. Here in this work, Sisal fiber is used as reinforcement. Since it is abundantly available in nature and majority of it is getting wasted without being used as reinforcement in engineering applications. Over the last thirty years composite materials, plastics and ceramics have been the dominant emerging materials. The 10 mm fiber length reinforced composite shown improved mechanical properties than 5 mm fiber length reinforced composite. Increase in impact strength is seen when the fiber content in the composite is increased from 20% to 25% and 25% to 30%. The fiber strength, for different fiber lengths and fiber volume fraction, the work of fracture is proportional to the fiber length and fiber volume fraction. Although results show increment in impact strength with fiber volume fraction, proportionality is not demonstrated. This suggests that there are other mechanisms that affect the impact strength of the composites. Crack propagation is the predominant toughening mechanism in notched impact test. Improvement in impact strength characterizes that fibers as stress transferring medium are able to absorb impact energy effectively. Good interaction with crack increases the energy needed for further crack formation and propagation. The exceptional case could be due to low fiber content and relatively short fiber length so that the energy is not dissipated effectively. Weak interfacial bonding of natural fibers is mainly due to incompatibility of hydrophobic matrix and hydrophilic fiber. High moisture absorption causes dimensional changes of natural fibers as well.

A Review of Structural Health Monitoring for Flexible Composite Materials

A Review of Structural Health Monitoring for Flexible Composite Materials

Estimation of Tensile and Flexure Strength of Hybrid Composites along with Epoxy as Matrix and Jute & E-Glass as Reinforcements

The natural fibers have the good properties such as mechanical and physical than artificial fibers in a many cases during the fabrication of composite materials that are used in many engineering applications. Also hybridization of fibers leads to impotent of mechanical properties these composites used in interior of aerospace vehicles, automobiles bumpers, decorative items, window panels, interior paneling, etc. where application pf load is very less. This research work is concentrated on the evolution of hybrid composite of Jute/E-glass reinforced with matrix epoxy using Hand layup method. Laminated composites specimens are prepared by calculating the required number of fiber layers and quantity of matrix based on the different volume fraction. The testing specimens are prepared for Tensile and Bending test as per standard of ASTM. The Universal Testing Machine is used to conducted Tensile and Bending test and results are plotted the graphs.

Environmental Impact of Wind Farms

The aim of this article is to analyse the global environmental impact of wind farms, i.e., the effects on human health and the local ecosystem. Compared to conventional energy sources, wind turbines emit significantly fewer greenhouse gases, which helps to mitigate global warming. During the life cycle of a wind farm, 86% of CO2 emissions are generated by the extraction of raw materials and the manufacture of wind turbine components. The water consumption of wind farms is extremely low. In the operational phase, it is 4 L/MWh, and in the life cycle, one water footprint is only 670 L/MWh. However, wind farms occupy a relatively large total area of 0.345 ± 0.224 km2/MW of installed capacity on average. For this reason, wind farms will occupy more than 10% of the land area in some EU countries by 2030. The impact of wind farms on human health is mainly reflected in noise and shadow flicker, which can cause insomnia, headaches and various other problems. Ice flying off the rotor blades is not mentioned as a problem. On a positive note, the use of wind turbines instead of conventionally operated power plants helps to reduce the emission of particulate matter 2.5 microns or less in diameter (PM 2.5), which are a major problem for human health. In addition, the non-carcinogenic toxicity potential of wind turbines for humans over the entire life cycle is one of the lowest for energy plants. Wind farms can have a relatively large impact on the ecological system and biodiversity. The destruction of animal migration routes and habitats, the death of birds and bats in collisions with wind farms and the negative effects of wind farm noise on wildlife are examples of these impacts. The installation of a wind turbine at sea generates a lot of noise, which can have a significant impact on some marine animals. For this reason, planners should include noise mitigation measures when selecting the site for the future wind farm. The end of a wind turbine’s service life is not a major environmental issue. Most components of a wind turbine can be easily recycled and the biggest challenge is the rotor blades due to the composite materials used.

Methods for Visualization and Analysis of the Microstructure of a Fibrous Composite Material

Methods for Visualization and Analysis of the Microstructure of a Fibrous Composite Material

Influence of Solid Solution Treatment on Microstructure and Mechanical Properties of 20CrNiMo/Incoloy 825 Composite Materials

The utilization of 20CrNiMo/Incoloy 825 composite materials as high-pressure pipe manifold steel can not only improve the strength and hardness of the steel, but also improve its corrosion resistance. However, research on the heat treatment of 20CrNiMo/Incoloy 825 composite materials is still scarce. Thus, the aim of this study was to investigate the influence of solid solution treatment on the microstructure and properties of 20CrNiMo/Incoloy 825 composite materials. Firstly, the composite materials were subjected to solid solution treatment at temperatures ranging from 850 to 1100 °C with varied holding times of 1 h, 4 h, and 6 h. Microstructural analysis revealed that the solid solution treatment temperature had a more pronounced effect than the treatment time on the interface decarburization layer, carburization layer, and grain size. It was observed that the carburized layer thickness decreased while the decarburized layer thickness increased with an increase in the solid solution treatment temperature, oil cooling was found to enhance the hardness of the base layer of the composite materials, and the size of the original austenite grains of 20CrNiMo steel and Incoloy 825 increased with an increase in the solid solution treatment temperature. Secondly, the tensile properties, microhardness, and fracture morphology were evaluated after the composite materials underwent solid solution treatment at temperatures between 950 °C and 1100 °C for 1 h. The results indicated that increasing the solution temperature initially led to an increase in tensile strength and elongation after fracture, followed by a decrease; furthermore, the hardness of Incoloy 825 exhibited a declining trend, while the hardness of 20CrNiMo first decreased then increased. Thirdly, the shear properties and interfacial element diffusion of the composite materials were analyzed following solid solution treatment in a temperature range of 950 °C to 1100 °C for 1 h. The findings demonstrated that higher solid solution treatment temperatures induced full diffusion of Cr, Ni, and Fe atoms at the interface and softened the matrix, leading to an increase in the thickness of the diffusion layer and toughening of the composite interface. Therefore, the shear strength increased with an increase in the solid solution treatment temperature. Finally, the optimal solid solution treatment process for 20CrNiMo/Incoloy 825 composite materials was determined to be 1050 °C/1 h oil cooling, following which the composite materials had good comprehensive mechanical properties.

Upscaling of Copper Slag-Based Geopolymer to 3D Printing Technology

Additive manufacturing using cement has evolved rapidly in recent decades, revolutionizing the construction industry. This technology automates building structures through computer-aided design, offering benefits such as reduced material waste, optimized material distribution, and the ability to use composite materials. This paper aims to examine the potential of using copper-slag-based geopolymers in 3D printing. Geopolymers have gained popularity as an alternative and more energy-efficient material to traditional building materials, while copper slag allows for reducing and managing mining industry waste. Moreover, samples formed in molds based on the same material were produced to evaluate the method of manufacturing on the mechanical properties of geopolymers. This paper presents an evaluation of the mechanical properties including the compressive, flexural, and shear strength of the layered material. It reveals promising results, with strength development mainly observed within the first 14 days. The results show that the compressive strength after 28 days of curing is 46.4 MP and 42.1 MPa for formed and printed samples, respectively. Furthermore, the average bending strength value ranges between 7.4 MPa and 7.8 MPa, regardless of the bending direction and forming method. The obtained results show that printed geopolymers demonstrate adequate layer bonding, confirming the profitability of the 3D printing technology. This research confirms that 3D printing technology enables the use of geopolymer binder materials based on copper slag, which opens the door to sustainable alternatives in construction practices.

Dextran-Encapsulated Nanoparticles and Super-Nanoparticle Assemblies: Preparation from Quantum Dots, Fluorescent Polymers, and Magnetic Nanoparticles for Application to Cellular Immunolabeling.

Nanoparticles (NPs) continue to be developed as labels for bioanalysis and imaging due to their small size and, in many cases, emergent properties such as photoluminescence (PL) and superparamagnetism. Some applications stand to benefit from amplification of the advantageous properties of a NP, but this amplification is not a simple matter of scaling for size-dependent properties. One promising approach to amplification is, therefore, to assemble many copies of a NP into a larger but still nanoscale and colloidal entity. Here, we use multiple types of hydrophobic nanocrystal to show that amphiphilic dextran is a versatile material for the preparation and surface functionalization of such super-NP assemblies: CdSe/CdS/ZnS quantum dots (QDs), InP/ZnS QDs, and Si QDs; iron oxide magnetic NPs (MNPs); composites of QDs and MNPs; and composites of QDs and MNPs with fluorene-based and phenylenevinylene-based conjugated polymers. The amphiphilic dextran was also useful for the preparation of conjugated polymer NPs (CPNs) without the inclusion of inorganic nanocrystals. The prepared super-NPs and CPNs were characterized, physically and photophysically, at both the ensemble and the single-particle levels. Per colloidal entity, the super-QDs were orders of magnitude brighter than the individual QDs. This enhancement enabled assemblies of nominally more benign InP/ZnS and Si QDs to be competitive alternative materials to CdSe/CdS/ZnS QDs, which are normally much brighter when compared as individual nanocrystals. The dextran functionalization imparted low nonspecific binding and enabled the use of tetrameric antibody complexes (TACs) for simple and selective immunolabeling of cells with all of the prepared super-NP, CPN, and composite materials. Labeling with the super-QDs provided significantly enhanced PL signals, the super-MNPs enabled magnetic pull-down of cells, and both capabilities were concurrently available with composite assemblies. Overall, this study demonstrates that the preparatory method and functional benefits of amphiphilic dextran extend to a range of hydrophobic materials and combinations thereof. There is strong potential for assembling a diverse set of property-amplified designer labels that are ready-made for in vitro applications in bioanalysis and imaging.

Progress in application of medical absorbable haemostatic materials for haemostasis in orthopaedic surgery

The application progress of medical absorbable haemostatic material (MAHM) in hemostasis during orthoapedic surgery was reviewed, in order to provide reference for clinical hemostasis program. The domestic and foreign literature on the application of MAHM for hemostasis in orthopedic surgery was extensively reviewed and summarized. According to biocompatibility, MAHM can be divided into oxidized cellulose/oxidized regenerated cellulose materials, chitosan and its derivatives materials, starch materials, collagen and gelatin materials, and fibrin glue materials, etc., which can effectively reduce blood loss when used in orthopedic surgery for hemostasis. Each hemostatic material has different coagulation mechanism and suitable population. Oxidized cellulose/oxidized regenerated cellulose, chitosan and its derivatives, starch hemostatic material mainly stops bleeding by stimulating blood vessel contraction and gathering blood cells, which is suitable for people with abnormal coagulation function. Collagen, gelatin and fibrin glue hemostatic materials mainly affect the physiological coagulation mechanism of the human body to stop bleeding, suitable for people with normal coagulation function. Reasonable selection of MAHM can effectively reduce perioperative blood loss and reduce the risk of postoperative complications, but at present, single hemostatic material can not meet clinical needs, and a new composite hemostatic material with higher hemostatic efficiency needs to be developed.

Optimizing superelastic shape-memory alloy fibers for enhancing the pullout performance in engineered cementitious composites

Abstract This study explores the effect of integrated superelastic shape-memory alloy fibers (SMAFs) on the mechanical performance of engineered cementitious composites (ECCs). Various SMAF configurations – linear-shaped SMAFs (LS-SMAFs), hook-shaped SMAFs (HS-SMAFs), and indented-shaped SMAFs (IS-SMAFs) – with diameters of 0.8 and 1.0 mm were incorporated into ECC matrices, and surface texturization was achieved through abrasive paper treatment. Their mechanical properties were assessed through single fiber pullout tests on ECC mixtures containing 1.5 and 2.0% polyvinyl alcohol (PVA), subjected to both monotonic and cyclic loading conditions. Qualitative analysis, employing scanning electron microscopy, demonstrated that the IS-SMAF configuration provided superior mechanical interlocking and fiber–matrix adhesion, with a distinct flag shape observed during tensile testing. Quantitative data indicated that IS-SMAFs significantly improved the tensile strength and pullout resistance, with slip distances of ≥5 mm and average pullout loads ranging from 263 to 403 N. LS-SMAFs demonstrated better performance compared to HS-SMAFs and LS-SMAFs in terms of tensile and pullout characteristics. Additionally, ECCs with increased PVA content exhibited enhanced withdrawal performance. Thermogravimetry analysis and X-ray diffraction provided insights into the high-temperature stability and crystalline structure of the composites. These results underscore the effectiveness of IS-SMAFs in enhancing ECC properties, offering significant implications for the development and optimization of high-performance composite materials in civil engineering applications.

Study on the impact of water absorption processes on the application of wood waste in composite material production

The issue of recycling and reusing waste from the wood processing industry has garnered significant attention from researchers, as effective solutions could yield economic benefits while mitigating environmental impacts. This article focuses on the development of artificial wood using unsaturated polyester resin combined with waste materials from carpentry workshops, specifically investigating its water absorption properties. Research findings indicate that the water absorption coefficient of the samples increased with longer immersion times, higher organic filler content, and larger particle diameters. The calculated density reveals a broad spectrum of solid industrial boards that can be produced from these compositions, suggesting that consistent forming conditions enhance economic viability. Notably, optimal results were achieved with samples made from mixed wood powder without prior sorting, which contributes to reduced production costs, aligning with the study's objectives. Furthermore, the investigation highlighted that the water absorption coefficient escalates with increased soaking time, organic filler content, and particle size, indicating that in humid environments, it is advisable to limit both filler content and particle size to maintain performance. Overall, the studies confirm the feasibility of utilizing wood powder as a filler, with varying particle diameters imparting distinct characteristics to the final product. These findings underscore the potential for innovative approaches to wood waste management in the industry.

Development of CuFe2O4 microspheres/carbon sheets composite materials as a sensitive electrochemical sensorfor determination of bisphenol A.

A composite material based on CuFe-ZIF-derived CuFe2O4 nano-microspheres grown in situ and well-ordered on carbon sheets (CS) was prepared and applied for highly effective determination of bisphenol A (BPA). The composite material possessed inherently high redox activity due to the presence of both Cu and Fe ions with various oxidation states (Cu²⁺/Cu⁺ and Fe³⁺/Fe²⁺), high specific surface area, uniform distribution of Cu and Fe ions, and a robust framework imparted by its precursor CuFe-ZIF. Thisled to increased active sites for electrochemical reactions, improved electron transfer efficiency, and structural integrity during electrochemical cycling. Furthermore, combining CS with CuFe2O4 not only provided a large surface area to support well-ordered CuFe₂O₄ nano-microspheres without aggregation, but also enhanced the conductivity and mechanical stability of the CuFe₂O₄/CS composite. This results in synergistic effects that enhanced the overall performance of the composite material. In addition, both copper and iron are relatively non-toxic and abundant, making CuFe₂O₄/CS safe and cost-effective for large-scale applications. Consequently, the CuFe2O4/CS-modified electrode shows highly efficient electrochemical sensing properties with a wider detection range of 0.009-168 µM and lower detection limit of 0.0027 µM (S/N = 3) compared withmost reported BPA sensors. It also hasanoptimized current at pH 7 which is convenient for real world applications. This CuFe2O4/CS modified electrode as a highly sensitive electrochemical platform can be applied to monitor BPA concentrations in bottled water with good recovery (97.2-102.2%).

Comparative study of fibers extracted from the stems and roots of the Cameroonian pennissetum purpureum for their applications in compressed earth brick reinforcement and textile engineering

This work focuses on the extraction and experimental characterization of pennisetum purpureum fibers extracted from stems and roots, harvested in the Batié Kingdom, in the West Region of Cameroon. After extracting fibers using the boiling water technique, they are chemically treated to improve their properties and performance and to facilitate their incorporation into various composite materials. For the physical characterizations, it is measured: the absolute and apparent densities, the linear mass, the water absorption rate, and the diameter via the microscope. The mean values of the diameters and the measure of their frequency distributions are calculated, followed by the statistical analysis using the maximum entropy principle, in order to find the most probable diameter necessary for technological applications. For the mechanical properties, only the tensile tests are performed, with the determination of the young modulus of both the stems and roots. The results thus obtained showed that the fibers of the stems have an absolute density of (1.35 g/cm3), a linear mass of (54.6 tex), an apparent density of (0.45 g/cm3), a water content of (12.73%), an absorption rate of (142.46%), a porosity of (65.91%), a mean diameter of (7 mm), an elastic modulus of (3.98 GPa), a tensile strength of value of (1186.59 MPa) and an elongation of 16.17%, while the root fibers have an absolute density of (1.34 g/cm3), a linear mass (16.76 tex), an apparent density of (0.37845 g/cm3), a water content of (12.25%), an absorption rate of (193.16%), a porosity of (71.92%), a diameter of (4 mm), an elastic modulus of (1.55 GPa), a tensile strength of a value of (1960.35 MPa) and an elongation of 60.6%. Thus, the fibers of the stems have good mechanical properties, which make them an appropriate material in several applications, such as the reinforcement of composite materials.

Micro-damage instability mechanisms in composite materials: Cracking coalescence versus fibre ductility and slippage

The load-displacement softening response of quasi-brittle solids exhibits an unstable structural behavior, which is characterised by a negative slope in the post-peak regime. In severely brittle situations, the post-peak behaviour can show a virtual positive slope, the fracture propagation occurring unexpectedly with a catastrophic loss in the load-carrying capacity. In this case, if the displacement controls the loading process, the curve exhibits a discontinuity and the representative point drops to the lower branch with a negative slope. On the other hand, in order to obtain a stable crack growth, a decrease both in load and in displacement is required. In the last forty years, in-depth study of the so-called snap-back instability was conducted in relation to crack propagation phenomena in quasi-brittle materials. In the present work, the structural response of two brittle-matrix specimens is analysed: the first contains a distribution of collinear micro-cracks, whereas the second presents multiple parallel reinforcing fibres embedded in the matrix. In both cases, it is shown that the structural response presents a discrete number of snap-back instabilities with related peaks and valleys, the crack propagation occurring alternately within the matrix and through the heterogeneities. Thus, the strong analogy between weakened and strengthened zones consists in a multiple snap-back mechanical response, where descending branches of propagating cracks alternate with ascending (linear) branches of arrested cracks.