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Composites are increasingly being modified with various types of fillers and nanofillers. These materials have attracted much attention due to the improvement in their properties compared to traditional composite materials. In the case of advanced technologies, adding additives to the matrix has created a number of possibilities for use in many industries, from electronics to mechanics. Mechanical recycling of composites allows them to be reused as a filler in new composite materials; however, a decrease in their strength parameters is observed, and hence, new possibilities of their use are sought. The main objective of this research was to analyze the effect of the graphite content on the tribological and structural properties of composites with polyester–glass recyclate. Composite materials with 10% polyester–glass recyclate and an additive in the form of graphite in the amounts of 0%, 2%, 5%, 10% were made using the hand lamination method and their mechanical properties were verified. Then, using a universal tribometer operating in rotational motion with friction without lubrication, the influence of nanoadditives on the change in the coefficient of friction (µ) and the change in the coefficient K (the rate of a mass wear) of the obtained composites was investigated. This study showed that adding graphite in the amount of 2%, 5%, and 10% changes the nature of tribological wear of the obtained composite material. The coefficient K (mass wear rate) also changes. The addition of 10% graphite significantly changes the coefficient of friction without lubrication in a pair with a steel counter-sample. [ABSTRACT FROM AUTHOR]

AbstractThe interface plays a crucial role in nanoparticle-reinforced composite materials. So this article presents a micromechanical model to predict the elastic and thermal properties of composites comprising nanoparticles encapsulated by an interphase. Nanoparticles are easy to agglomerate in the matrix because of their large surface area ratio. Therefore, the study focuses on the effect of nanoparticles agglomeration on the elastic modulus and thermal expansion coefficient (CTE). In the present study, the regions with concentrated particles are assumed to be spherical in shape and are considered as inclusions. The size efficiency factor is introduced to reflect the influence of the agglomerated inclusions diameter in the analysis. The effects of the volume fractions, radius, and agglomerated degree of nanoparticles, and also the thickness and properties of the interphase are studied in detail. The micromechanical method is used to predict the effective elastic and thermal properties of nanoparticles reinforced three-phase composites. Analysis shows that the agglomeration of nanoparticles has a significant effect on the elastic modulus and thermal expansion coefficient of composites. The agglomeration of nanoparticles reduces the elastic modulus of the composites, but increases the thermal expansion coefficient of the composites. Increasing the thickness of the interface enhances the elastic modulus of composites, while increasing the particle radius reduces the elastic modulus of composites. Besides, the more severe the agglomeration of particles, the larger the coefficient of thermal expansion of the composites. The present study will provide a theoretical basis for the preparation and practical application of particle reinforced composites. [ABSTRACT FROM AUTHOR]

One approach to structural health monitoring (SHM) involves embedding sensors within a composite material. However, the integration of these sensors can potentially introduce flaws that might affect the composite's mechanical properties. This research aims to explore the impact of embedding exfoliated graphite (EG)/epoxy sensors on the mechanical characteristics of composite systems through laboratory experiments and numerical simulations. Sensor strips composed of varying volume fractions of EG/epoxy were fabricated. Tensile test specimens were prepared by embedding these sensors in the epoxy matrix oriented both lengthwise and widthwise. Baseline specimens of EG/epoxy without sensors were also created for comparison. Tensile tests were performed on the samples to evaluate the effects of the embedded sensors on the composite's elastic modulus and tensile strength. The results indicated a slight improvement in both elastic modulus and tensile strength with the introduction of EG. Crucially, the orientation of the sensors within the samples had a significant impact on the composite's mechanical properties. Samples with widthwise-aligned sensors showed reduced tensile strength due to delamination along the sensor edges. Finite element simulations using a viscoelastic model based on the experimental data were conducted to analyze the effect of sensor alignment on mechanical properties. The findings revealed that a grid pattern alignment of sensors significantly enhanced mechanical performance compared to lengthwise or widthwise alignment, particularly at 0.1% and 0.3% EG volume fractions, highlighting the effectiveness of a grid pattern for embedding sensors in SHM applications. [ABSTRACT FROM AUTHOR]

Highlights Composites are undergoing extensive research and utilization due to their excellent mechanical properties, driven by human needs. Traditionally, the research methods in materials science predominantly rely on empirical theory or experimental trial and error approaches. However, the increased complexity of composite materials results in a greater intricacy in their mechanical behavior. Consequently, the utilization of traditional research methods may not achieve sufficient efficiency. Materials science is rapidly transitioning into a data‐driven era, with machine learning (ML) emerging as a potent tool to expedite materials development and enhance properties prediction. Significant advancements have been achieved in the application of ML to the study of composite mechanics. In this review article, we elucidate various ML methods employed in the construction of constitutive models for isotropic and anisotropic composites, and delve into the research on construction ML models that leverage input data derived from composite processes, structures, and environmental conditions to predict material mechanical properties. Additionally, we summarize recent noteworthy ML applications in composite design and optimization. Finally, possible prospective viewpoints are proposed for future development, with the aim of providing essential scientific guidance for advancing material science and technology through ML. Machine learning can address complexity in constitutive model of the anisotropic composites. Machine learning predicts mechanical properties of composites well by process and structure. Machine learning enhances efficiency in inverse design to optimize composites. Limitations, challenges, development trends of ML in composites. [ABSTRACT FROM AUTHOR]

This article describes the structure and properties of the developed hybrid composite Hastelloy X (NiCrFeMo)-AlMoNbTaTiZr-cBNSiCNiAlCo. The composite was obtained by the high velocity oxygen fuel spraying (HVOF) method in a protective atmosphere with a subsequent high-temperature thermomechanical treatment. In order to obtain new information about the structure, we studied the metallophysical properties of the composite using electron microscopy and X-ray diffraction analysis, as well as the mechanical properties and phase composition. We studied the influence of high-energy mechanical processing of high-entropic and ceramic materials on the structural-phase state and composite quality. We determined the optimal technological parameters of HVOF in a protective atmosphere, followed by a high-temperature thermomechanical treatment. Additionally, we optimized these parameters to form a hybrid composite providing the highest adhesion and low porosity. Moreover, we investigated the microhardness of the composite layers. On the basis of complex metallophysical studies, we examined the composite formation. In order to determine the endurance limit in comparison to various other composite materials, we carried out cyclic endurance tests of the developed materials.

Periodic boundary condition is commonly used in the FE homogenization method for predicting the thermo-mechanical properties of composites. However, its existing numerical algorithms are generally inefficient. Linear displacement boundary condition is much easier and more efficient to implement for the Representative Volume Elements (RVEs) with conformal and nonconformal surface meshes. Aiming at replacing the periodic boundary condition by the linear displacement boundary condition to easily and efficiently predict the thermo-mechanical properties of composites, this paper compares the implementation efficiency and prediction accuracy of the periodic and linear displacement boundary conditions. Regarding the prediction of the elastic properties of composites, the balance of micro-energy and macro-energy of the RVEs imposed the periodic and linear displacement boundary conditions is checked, and the results demonstrate that these two boundary conditions guarantee the Hill lemma (i.e. the balance of micro-energy and macro-energy of the RVEs). Moreover, comparing with the experimental test and the multi-step micro-mechanical method, the effectiveness of the periodic and linear displacement boundary conditions to predict the elastic properties of composites is validated. [ABSTRACT FROM AUTHOR]

In this research, the optimization of composite materials for improving their mechanical properties is investigated. It is achieved by applying different compositions of the PTLLDPE matrix, SiC nanoparticles, and carbon fibre filler. For this purpose, six composite samples are prepared using different compositions of PTLLDPE from 40% to 60%, SiC nanoparticles from 0% to 3%, and carbon fibre filler from 10% to 20%, which are mechanically tested . Results show that tensile strength increases with increasing PTLLDPE contents, Sample 6 having the highest value of 62 MPa. As the SiC nanoparticles contents increase, the flexural strength and impact resistance increases, Sample 4 having the highest flexural strength at 75 MPa and impact resistance at 200 J/m2. The hardness increases with increasing carbon fiber fillers, Sample 6 having the highest hardness value at 88 shore D. This is important in the synthesis and the optimization of composite formulations, helping various industries in in their choice and application of the composites.

Energy harvesting systems fabricated from rubber composite materials are promising due to their ability to produce green energy with no environmental pollution. Thus, the present work investigated energy harvesting through piezoelectricity using rubber composites. These composites were fabricated by mixing titanium carbide (TiC) and molybdenum disulfide (MoS2) as reinforcing and electrically conductive fillers into a silicone rubber matrix. Excellent mechanical and electromechanical properties were produced by these composites. For example, the compressive modulus was 1.55 ± 0.08 MPa (control) and increased to 1.95 ± 0.07 MPa (6 phr or per hundred parts of rubber of TiC) and 2.02 ± 0.09 MPa (6 phr of MoS2). Similarly, the stretchability was 133 ± 7% (control) and increased to 153 ± 9% (6 phr of TiC) and 165 ± 12% (6 phr of MoS2). The reinforcing efficiency (R.E.) and reinforcing factor (R.F.) were also determined theoretically. These results agree well with those of the mechanical property tests and thus validate the experimental work. Finally, the electromechanical tests showed that at 30% strain, the output voltage was 3.5 mV (6 phr of TiC) and 6.7 mV (6 phr of MoS2). Overall, the results show that TiC and MoS2 added to silicone rubber lead to robust and versatile composite materials. These composite materials can be useful in achieving higher energy generation, high stretchability, and optimum stiffness and are in line with existing theoretical models. [ABSTRACT FROM AUTHOR]

• Two unified numerical algorithms of periodic boundary condition are proposed. • The proposed algorithms predict accurate thermo-mechanical properties of composites. • The proposed algorithms are available for RVEs with periodic and nonperiodic meshes. • The proposed algorithms can be used for simple and complicated nonradial loadings. This work emphasizes on the Periodic Boundary Condition (PBC) utilized in the Finite Element Homogenization (FEH) method to numerically determine the Thermo-mechanical (T-M) properties of composites. The unified numerical implementation algorithms of the PBC used for accurately predicting the elastic properties, coefficients of thermal expansion and elasto-plastic behaviors of composites and available for representative volume elements with conformal and non-conformal surface meshes, respectively, are proposed and detailed. Regarding not only the thermo-elastic properties of composites, but also the elasto-plastic behaviors of composites under both simple uniaxial tensile, shear, uniaxial cycle loading paths and complex non-radial loading paths, the unified numerical implementation algorithms are verified to accurately predict the T-M properties of composites, through comparison with the results of the analytical models, the DIGIMAT-FE method, the experimental test and the results from the literature. The unified numerical implementation algorithms of the PBC can be extended to the predictions of other properties of various composites. This work provides a comprehensive insight into the PBC used for predicting the T-M properties of composites and benefits development of future FE codes implemented in commercial software packages. [ABSTRACT FROM AUTHOR]

The study focused on the potential use of agricultural waste (corn cob) in the manufacturing of composite materials. In the first stage, composite materials were manufactured and tested using synthetic matrices (epoxy and acrylic) and hybrid matrices based on dammar resin (50% dammar, 60% dammar, and 70% dammar). Since it was observed that the samples had low mechanical properties under tensile and bending loads, the study was expanded to the production of sandwich-type composites with silk fabric facings. It was found that, by utilizing silk fiber, both tensile and bending strength increased from a few hundred percent up to a few thousand percent, compared to the samples that are only reinforced with crushed corn cob. [ABSTRACT FROM AUTHOR]

There is a growing demand for materials for detecting ionizing radiation, which has led to the expansion of research and development of new scintillators. Typically, scintillators are synthesized by crystallizing materials at high temperatures, and their photoluminescence (PL) is difficult to tune in the visible spectral range. Therefore, composite materials based on CsPbBr3 perovskite nanocrystals (PNCs), which have a high average atomic number and a long charge-carrier diffusion length, are of particular interest and may be used for detecting ionizing radiation. Unlike bulk scintillators, PNCs are synthesized in solution at relatively low temperatures, with the PL tunable throughout the visible spectrum. The main problem limiting the widespread use of PNCs is their low stability upon contact with the environment. This study presents the results of experiments on the encapsulation of PNCs in a polystyrene matrix, the evaluation of the changes in the luminescence quantum yield (QY) over time, and the development of a technique for studying the amplitude characteristics of signals recorded during the interaction of α-particles with composite materials based on CsPbBr3 PNCs and polystyrene. The study has shown that composite samples based on PNCs and polystyrene retain a stable luminescence QY for two weeks. Using a 241Am source with a characteristic α-particle energy of about 4.6 MeV and γ-ray energy of 60 keV, the light output values were calculated for the samples studied. The maximum light output was 20% of that of the standard "fast" plastic scintillator (POPOP) at a volume fraction of PNCs in the composite of less than 1%, which indicates the prospect of PNCs as a basis for composite scintillators and their further use in X-ray diagnosis. [ABSTRACT FROM AUTHOR]

We develop a computational framework for the semi-analytic representation of the effective transport properties of two-component composite materials, in the spirit of Bergman's spectral representation. The components of the effective permittivity (or conductivity) tensor are expanded as power series in a contrast parameter between the two phases. The coefficients (the moments of a spectral measure) of these expansions are determined recursively through the numerical evaluations of integrals defined solely on the boundary between the constituent phases, and discretized by high-order (possibly exponentially converging) quadrature schemes. The high precision reached by these coefficients allows the series representation to be recast into Padé approximants (or continued fractions) to provide analytical expressions valid over large (possibly infinite) regions of the parameter complex plane. Examples, thus far limited to two-dimensional rhombic unit cells, demonstrate that the method is reliable for microgeometries and material parameters for which other methods are far less dependable. The analytical representations are particularly useful to study the optical or electrostatic resonant behaviour of some composite materials. [ABSTRACT FROM AUTHOR]

Materials made from natural fibers or waste have been studied to acquire a composite with good acoustical isolation properties, commercial materials used in this concern are polyurethane foam, fiberglass, Rockwool, and drywall. This work proposes using waste coconut and cactus (Opuntia ficus-indica) fibers to synthesize bentonite composites and study their physicochemical and acoustic properties. Physicochemical properties of precursor and composites (75% wt. fiber) were determined by XRD, FTIR, N 2 adsorption, optical, and SEM microscopies. The transmission, reflection, and absorption coefficients, 50 to 10,000 Hz, were obtained in an impedance tube and were compared with commercial materials. The composites were subjected to surface humidity and thermal (30, 50, and 70°C) tests to evaluate the stability of acoustic properties. The mechanical properties of the composites are improved with the addition of bentonite, hardness is increased by 6.7% and 0.9%, and the density is decreased by 73.6% and 45.5%, for coconut and nopal, respectively, porosity also changes. We corroborated the significant presence of montmorillonite in bentonite (XRD), while the nopal or coconut fibers are composed of hemicellulose, cellulose, and lignin (FTIR). Also, mucilage was identified in the nopal samples as adherent biopolymer that generates stability either thermally or in wetting conditions. Coconut fiber has a high absorption coefficient (similar to polyurethane), which is reduced with humidity. However, by adding bentonite, the reflection is more elevated, and transmission is lower than commercial materials. The bentonite and nopal (fiber and composite) presented stability in the acoustic coefficients as a function of humidity and temperature. [ABSTRACT FROM AUTHOR]

This article describes the structure and properties of the developed hybrid composite Hastelloy X (NiCrFeMo)-AlMoNbTaTiZr-cBNSiCNiAlCo. The composite was obtained by the high velocity oxygen fuel spraying (HVOF) method in a protective atmosphere with a subsequent high-temperature thermomechanical treatment. In order to obtain new information about the structure, we studied the metallophysical properties of the composite using electron microscopy and X-ray diffraction analysis, as well as the mechanical properties and phase composition. We studied the influence of high-energy mechanical processing of high-entropic and ceramic materials on the structural-phase state and composite quality. We determined the optimal technological parameters of HVOF in a protective atmosphere, followed by a high-temperature thermomechanical treatment. Additionally, we optimized these parameters to form a hybrid composite providing the highest adhesion and low porosity. Moreover, we investigated the microhardness of the composite layers. On the basis of complex metallophysical studies, we examined the composite formation. In order to determine the endurance limit in comparison to various other composite materials, we carried out cyclic endurance tests of the developed materials. [ABSTRACT FROM AUTHOR]

To inhibit and repair the damage to cable insulation caused by the formation of water tree structure by micro water droplets at insulation defects in low-density polyethylene (LDPE) materials under the action of an AC electric field. In this paper, using low-density polyethylene as the matrix, we investigate the effects of graft modification and nano-doping on the growth of water trees in LDPE materials and design LDPE composite insulating materials with different components. Accelerated water tree aging experiments were carried out using the water needle electrode method to analyze the repair ability of grafted monomers on the damaged area of the water tree. Through the observation of OM, SEM, and FDS of the materials before and after aging, it is shown that the LDPE composite insulating material doped with a small amount of nano-SiO 2 has a good self-repairing property of water tree. By testing the insulation and mechanical properties of the aged LDPE composite insulation material doped with a small amount of nano-SiO 2 , it was found that both could be restored to about 90 % of the pure sample, indicating that the self-healing performance of the composite material is very excellent. The research in this paper not only improves the online service life of the cable but also provides a new idea for repairing LDPE cable insulation materials, which has good research prospects in practical applications. [Display omitted] • This paper makes a new LDPE material. It lets cable self-repair after water tree damage and extends insulation life. • The composite material prepared beats the shortcomings of poor mechanical and dielectric properties of LDPE. • Grafted monomer's reaction with water-tree water and product's stability enhance material's self-healing. • Composites' mechanical and insulation properties can restore to 90 % of LDPE. It offers new ideas for LDPE insulation repair. [ABSTRACT FROM AUTHOR]

Rational compositions of a polymer composite material are proposed and technological prerequisites for manufacturing technical products for chemical engineering, based on liquid resol phenol–formaldehyde resins and dispersed fibrous filler manufactured by mechanical processing of the organic waste from fiber production in the pulp and paper industry are evaluated. Methods and parameters of technological stages, including the preparation of raw materials and their mixtures, production of a polymer dispersed filled press material, and hot molding (pressing) products, were determined and tested. Recommendations are given on the hardware and process design of the technological stages of the production of a quality polymer composite material and improvement of its properties. The regularities of changes in the physical and mechanical properties (response on compression, tension, and bending, as well as impact strength and moisture and oil absorption) of the composites with the concentration of dispersed fibrous filler at the recommended thermal pressing parameters (temperature 170 °C, specific pressure 20 MPa, exposure time 1 min/ 1 mm product thickness). Clear evidence is provided showing that the upper limit of the percentage of dispersed fibrous filler in the studied phenolic samples is 40-60%, and at higher percentages the mechanical parameters are strongly deteriorated and the moisture and oil absorptions become much higher than the limits permitted by standards for technical phenolic plastics. The results of the study make it possible to recommend the compositions based on liquid resol phenol–formaldehyde resins and modified fibrous waste from the pulp and paper industry and the hardware and process design for the production of phenolic products of chemical engineering. The developed composites allow homogeneous coloring in various colors (except for white) and imparting to their surface a smooth shiny texture. [ABSTRACT FROM AUTHOR]

As the amount of agricultural waste produced annually worldwide is very high, numerous studies have been conducted with the aim of using them in the structure of composite materials that have a minimal impact on the environment, reduced costs, and can be used in various fields of activity. In this research, four types of composite materials were cast, with a reinforcement of chopped corn cobs and with a matrix of acrylic resin, respectively, of three hybrid resins having various mass proportions, where Dammar natural resin prevailed. The chemical structure of the composites with hybrid matrix was determined using molecular spectroscopic microanalysis, and some mechanical properties of all the composites were investigated. It was found that the values of the obtained mechanical characteristics were limited. [ABSTRACT FROM AUTHOR]

Designing and fabricating microwave-absorbing materials (MAMs) with a widening effective absorption bandwidth, intense reflection loss, thin matching thickness, and lightweightness is an effective method to mitigate the drawbacks of electromagnetic (EM) radiation while enjoying its advantages for modern life. Among MAMs, composites of magnetic materials and dielectric materials could be the best candidates. CoFe 2 O 4 (CFO), with its unique crystalline structure, excellent EM properties, and environmentally friendly and low-cost production, has been extensively used as MAM. Meanwhile, carbonaceous-based materials have also been used as MAMs due to their intriguing properties, including flexibility, lightweight, and suitable dielectric properties. Therefore, composites of CFO/carbonaceous-based materials could be among the best MAMs. This review will be systematically reviewed for MAMs of CFO/carbonaceous-based materials in the form of two, three, and four components. The principal microwave loss mechanism for attenuation mechanisms will be carefully examined. This review also summarized perspectives and challenges for the future of CFO/carbonaceous-based materials for human security, interference protection, and radar signal absorption. [Display omitted] • A systematic review of MAMs of CoFe 2 O 4 /carbonaceous-based materials was conducted. • The MAMs were in the form of binary, ternary, and quaternary components. • Biomass, plants, or seeds carbon-based materials improved the MAMs' microwave absorption performance. • Ternary component composites would result in good microwave absorption performance. • Multiband MAMs of CFO/carbonaceous-based materials need further fabrication and investigation. [ABSTRACT FROM AUTHOR]

Shelled herbal foods are widely consumed. The evaluation of the shells of these foods is important due to their features such as low cost, ease of recycling and environmental friendliness. In this study, hazelnut shell (HS), pistachio shell (PS), and apricot kernel shell (AKS) were brought to powder particles by grinding to dimensions of 300–425 µm. Some of the powder particles were converted into ash at 900°C. The amounts of cellulose, ash, humidity, and metal in these particles via chemical analyses were determined, while their structural properties via X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) analyses. Composite materials were produced by adding 15 wt.% to the polyester matrix material from these powder particles and ashes. Compression strength, hardness, specific weight, and thermal conductivity of these composites were analyzed. The lowest and highest humidity, ash, cellulose, hemicellulose, and lignin ratios in powders showed differences depending on the type of powders. The amount of Sn and K in the HS, PS, and AKS powders were close to each other, while the amount of Ca, Na, Mg, Fe, Mn, Cu, Zn and Si was higher in AKS powder. The reinforcement adding to the polyester increased the compression strength, hardness, specific weight and thermal conductivity properties. [ABSTRACT FROM AUTHOR]

We study the tribological properties of the composite materials of brake pads operating under severe conditions. We analyze the materials formed by phenol formaldehyde, barite, alumina, synthetic wollastonite, lead, tin, copper, graphite, silicon oxide, and small amounts of magnesium oxide and molybdenum disulfide. It is shown that the material containing 25 wt.% of phenol formaldehyde exhibits the best friction properties in terms of the friction coefficient and thermal stability. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the strength and thermophysical properties of the composite material graphene nanoplatelets (GNP)–nitrile butadiene rubber (NBR) (GNP@NBR). High-quality GNP were massively produced by self-propagating high-temperature synthesis (SHS) method. It was found that the introduction of GNP in concentrations up to 6 wt.% leads to an increase in tensile strength up to 62%, resistance to tearing up to 64% thermal conductivity up to 2. The use of GNP allowed increasing the maximum operating temperature of the NBR to 125℃. Also, GNP@NBR composite showed an exceptional improvement in antifriction properties – it drops more than twice the coefficient of friction on steel under loads to 500 Newtons. [ABSTRACT FROM AUTHOR]

The arising trend of using natural fibres in the composite materials has stimulated the continuous exploration of their mechanical properties. The positive environmental behaviours of natural fibres are the driving factor that allows them to gain their wide acceptance in industries. However, the mechanical behaviour of natural fibre-based composites is still not fully explored. In this research study, the mechanical properties of composite materials with different types of natural fibre and various fibre compositions were investigated. The polypropylene-based composite materials were fabricated through hot press compression moulding method using a hydraulic hot press machine. The composites were then subjected to mechanical tests to study the tensile, flexural and impact properties of such materials. The results demonstrated that the tensile strength and flexural strength of pineapple leaf fibre (PALF)-based composites were 7.83% and 54.23% higher than kenaf-based composites at a fibre content of 30 wt%. Moreover, the impact strength of PALF-reinforced composites was 3.08% and 5.56% higher than kenaf fibre-reinforced composites in the flatwise and edgewise impact orientations. Overall, composites with 30 wt% evidenced the top most mechanical properties irrespective of types of plant fibre. [ABSTRACT FROM AUTHOR]

The mechanical properties of composites based on the inorganic boron oxide oligomer (BOO) and low‐density polyethylene (LDPE) produced by extrusion and injection molding have been studied in the range of volume fractions of the inorganic component from 0 to 64 vol%. An abrupt increase in the Young's modulus and ultimate tensile strength of the composites in the vicinity of 30 vol% BOO has been found. These critical properties are accompanied by a stepwise decrease in the elongation at break at the same volume fraction of the inorganic component. The mechanical properties of BOO/LDPE composites were compared with the same characteristics of composites based on LDPE and polymethyl methacrylate prepared via a similar way. The electron microscopic examination has suggested that the abnormal concentration dependences of the Young's modulus, tensile strength, and elongation at break of BOO/LDPE composites are conditioned by the formation of the unidirectional microfibers of the inorganic oligomer as soon as its volume fraction exceeds the critical threshold. POLYM. COMPOS., 40:916–923, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The work is concerned with the determination of effective conductivities and field potentials of matrix-based composites consisting of periodic arrays of cylinders which are cylindrically orthotropic and exponentially graded along the radial direction. We generalize Rayleigh’s method to account for the periodic arrangements of these cylinders. The potential field and effective conductivities of composite systems were calculated to a very high order to achieve a sufficient accuracy. We find that the cylindrical orthotropy of the inclusions has a dramatic effect on the potential field of the inclusions. In addition, we discuss the effect of the grading factor on the effective conductivity. Interestingly, we find that when the inclusions are purely cylindrically orthotropic, their effects can be fully described by homogeneous isotropic cylinders. This equivalent isotropic conductivity is simply the geometric mean of the radial and tangential conductivities of cylindrically orthotropic cylinders. [ABSTRACT FROM AUTHOR]

Abstract An interface model of homogenization was proposed, this model considers the influence of the inclusions size of the micrometre range on the elastic properties of composites. The appearance of surface strains and shear stresses at the interphase boundary is associated with the "sticking" of the matrix to the surface of the inclusions. The effective modulus of elasticity of a composite is the sum of two terms: a constant part in the form of a modulus of elasticity of a bulk material, and a variable part that is caused by a shift at the interphase boundary and depends on the particles size. Absolute of particles sizes were considered by introducing within the interfacial model empirical elasticity modulus of the composite with the one basic particle size. The results of the calculation are in good agreement with the experimental data for Young's modulus of polymer composites with spherical particles. [ABSTRACT FROM AUTHOR]

In this paper, a three-layer model is proposed for the composite with an ellipsoidal inclusion core surrounded successively by the interphase and matrix phase, respectively. The elastic properties of composites are investigated, and the existence of interphase between inclusion and matrix is taken into account. The overall composite materials can be treated statistically as a transversely isotropic solid for the case of aligned axisymmetric ellipsoidal inclusions. The main novelty in the present scheme resides in the consideration of the existence of interphase surrounding the multiple types of aligned ellipsoidal inclusions, and the interactions between inclusions and interphase are taken into account. The influence of some factors, such as the particle shape, the particle size and the interphase thickness, on longitudinal and transversal Young’s modulus is analyzed. The obtained solutions are shown to agree well with the theoretical ones in the existing literature. [ABSTRACT FROM AUTHOR]

With the development of modern industrial production, it is difficult for a single industrial material to meet the needs of production development. Therefore, composite materials with many excellent properties appear, but because of their excellent properties, it is difficult to adopt conventional machining methods. In this paper, single-factor variable experiments of pulse width, peak current, flushing pressure and working fluid conductivity of 10% SiC reinforced aluminium matrix composite and titanium-magnesium-aluminium alloy were carried out by electrosparking machine tool to study the electrosparking properties of SiC. The results showed that the machining efficiency was improved by increasing pulse width, peak current, flushing pressure and working fluid conductivity in a certain range, and the machining efficiency tended to be stable or even decreased if the increase exceeded a certain range; the thickness of the recast layer decreased with the increase of flushing pressure, but increased with the increase of pulse width, peak current and working liquid conductivity and tended to be stable. [ABSTRACT FROM AUTHOR]

Abstract: Common nano clay fillers have layered structure. Some nano clays like Attapulgite (AT), Sepiolite have rod like fibrous structure. Compared to layered structured clay fibrous clay AT can undergo better dispersion in polymer matrix leading to better improvement in composite properties. Chemical modifications of AT are done through amine treatment as well as by amine+silane treatment to get chemically modified fillers AAT and SAT respectively. In the present investigation, nano composites are prepared using natural rubber (NR) filled with AT, AAT and SAT. Three different loadings of each filler are used namely 2.5, 5, and 10 phr (parts per hundred of rubber). Mechanical properties like tensile strength, elongation at break increase with the increase in filler loading up to 5 phr there after these properties marginally fall when loading is increased to 10 phr due to problem of filler dispersion at higher loading. However, modulus at 300% elongation and tear strength increases with the increase in filler loading up to 10 phr. Very similar trend can also be observed for composites with chemically modified fillers, AAT and SAT. But the degree of reinforcement is higher in the case of AAT and SAT compared to that of unmodified filler AT for the same filler loading. This difference is mainly due to better polymer-filler interaction and filler dispersion in the case of chemically modified clays AAT and SAT compared to unmodified AT. Tear strength of composites increases remarkably with the addition of AT and which is further enhanced when chemically modified clays AAT and SAT are added. Dynamic-mechanical analyses of different clay composites give idea about the difference in the degree of polymer–filler interaction due to chemical treatment of filler. [Copyright &y& Elsevier]

Highlights • We proposed here a new method to make bulk composites of La-Fe-Si hydrides using sodium silicate. • This method only needs a relatively low solidification temperature and can create a homogenous microstructure. • The bulk composites possess good mechanical, thermal and magnetocaloric properties. Abstract We adopted sodium silicate to prepare composites of La(Fe, Si) 13 hydrides in this work. A homogenous and continuous matrix of sodium silicate was formed at a relatively low solidification temperature. No counter diffusion between the matrix and the grains of La(Fe, Si) 13 hydrides was observed. The magnetocaloric effect of pure La(Fe, Si) 13 hydrides is largely preserved in the composites, showing a high tolerance to sodium silicate. These composites possess high thermal conductivity and decent compressive strength compared with the epoxy resin bonded samples. These results suggest that sodium silicate is a promising binder material for producing bulk La(Fe, Si) 13 hydrides for their application in magnetic refrigeration. [ABSTRACT FROM AUTHOR]

Abstract The gradual replacement of conventional materials by composite materials becomes reality when specific properties cannot be achieved by the former. Also, the search for new composites that use natural fibers or a mixture of natural fibers with synthetic fibers as reinforcement is being carried out. Thus, a research was made on the development of two composite laminates, one based on piassava fiber fabric and the other a hybrid composite based on piassava fiber and glass-E fabrics, in order to compare the mechanical behavior of both. The laminate plates were prepared and were processed for specimen manufacture in accordance with the specifications of ASTM D3039 - Uniaxial Tensile Test, and ASTM D790 - Three-point Bending Test standards. Scanning Electron Microscopy (SEM) was also performed to analyze the mechanisms of damage of the specimens. The analysis of the results of the tested specimens show they are satisfactory, as they are very akin to the results of other materials already researched by academy. [ABSTRACT FROM AUTHOR]

Antibacterial polymer was grafted onto silica nanoparticle and the surface properties of various composites filled with the silica were investigated. The grafting of antibacterial polymer, poly(vinylbenzyltributylphosphonium chloride) (poly(St-CH2P+(Bu)3Cl-)), onto silica surface was achieved by two methods: one is treatment of poly(vinylbenzylchloride) (poly(St-CH2Cl))-grafted silica with tributylphosphine and the other is direct grafting of poly(St-CH2P+(Bu)3Cl-) by radical graft polymerization of the corresponding monomer. The grafting of poly(St-CH2Cl) and poly(St-CH2P+(Bu)3Cl-) onto silica surface were initiated by the system consisting of trichloroacetyl groups on the silica surface and Mo(CO)6. Trichloroacetyl groups were introduced onto the silica surface by the reaction of amino groups on the silica surface with trichloroacetyl isocyanate. The percentage of poly(St-CH2Cl) grafting during the graft polymerization initiated by the system increased with progress of the polymerization reached 116%. The grafting of poly(St-CH2P+(Bu)3Cl-) onto silica surfaces was confirmed by FT-IR spectra, thermal decomposition gas chromatograms and mass spectra (GC-MS), and 13C-CP/MAS NMR. The surfaces of silicone rubber, polystyrene film, and paints filled with the poly(St-CH2P+(Bu)3Cl-)-grafted silica shows strong antibacterial activity. These composites retained the antibacterial activity even after the boiling in water for 24 h. [ABSTRACT FROM AUTHOR]

The localized stress and strain field simulation results are critical for understanding the mechanical properties of materials, such as strength and toughness. However, applying off-the-shelf machine learning or deep learning methods to a digitized microstructure restricts the image samples to be of a fixed size and also lacks interpretability. Additionally, existing methods that utilize deep learning models to solve boundary value problems require retraining the model for each set of boundary conditions. To address these limitations, we propose a customized Pixel-Wise Convolutional Neural Network (PWCNN) to make fast predictions of stress and strain fields pixel-by-pixel under different loading conditions and for a wide range of composite microstructures of any size (e.g., much larger or smaller than the sample on which the PWCNN is trained). Through numerical experiments, we show that our PWCNN model serves as an alternative approach to numerical solution methods, such as finite element analysis, but is computationally more efficient, and the prediction errors on the test microstructure are around 5%. Moreover, we also propose an interpretable machine learning framework to facilitate the scientific discovery of why certain microstructures have better or worse performance than others, which has important implications in the design of composite microstructures in advanced manufacturing. [ABSTRACT FROM AUTHOR]

In this study, the mechanical properties of composites will be examined which were made from Kenaf and hybrid fabric with a simple structure that was coated with epoxy resin and nano silica particles. This fabric cotton has a different situation in terms of yarn score and the type of fiber that is used in textiles. Nano silica particles of 200 nm, polyethylene glycol with 200 molecular weights and ethanol with mechanical weight molecular with ratio of 6:1 will be mixed. Suspension of 60% was chosen according to the silica particles. The D6264 standard test for concentrated force was carried out through the cone edge to determine the strength of each of the samples. Increasing of resistance against penetration in the Kenaf samples from the raw until impregnated with the shear thickening fluid is less than the hybrid samples. Slippage of the fibers with the change of round edge indenter to cone edge indenter has changed. Penetration by cone edge to the cloth is done with lower force and it shows the effect of slippage of fibers on the resistance of the penetration. Samples impregnated with the shear thickening fluid in comparison with epoxy resin have lower resistance. Slippage of natural fibers in comparison with synthetic fibers is lower and on the other hand the average of friction between fibers in the natural fibers is more than synthetic fibers. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new systematic procedure of estimating elastic properties of composites constituted of two phases, matrix and inclusions. A class of integral equations based on eigenstrain (or eigenstress) with the matrix as reference material is constructed with an explicit form in Fourier space. Each integral equation belonging to this class can yield estimates of the overall elastic tensor via Neumann series expansion. The best estimates and series are selected based on the convergence rate criteria of the series, i.e the spectral radius must be minimized. The optimized series is convergent for any finite contrast between inclusions and matrix. Applying the optimized series and the associated estimates to different microstructures yields very satisfying results when compared with the related full solution. For the case of a random distribution of spherical inclusions, exact relations between the elastic tensor and n th order structure factors are demonstrated. [ABSTRACT FROM AUTHOR]

Abstract This research stems from the idea of introducing a fibre-network structure into composites aiming to enhance the stiffness and strength of the composites. A novel new type of composites reinforced by a tranversely isotropic fibre-network in which the fibres are devided into continuous segments and randomly distributed has been proposed and found to have improved elastic properties compared to other conventional fibre or particle composites mainly due to the introduction of cross-linkers among the fibres. Combining with the effects of Poisson's ratio of the constituent materials, the fibre network composite can exhibit extraordinary stiffness. A simplified analytical model has also been proposed for comparison with the numerical results, showing close prediction of the stiffness of the fibre-network composites. Moreover, as a plate structure, the thickness of the fibre network composite is adjustable and can be tailored according to the dimensions and mechanical properties as demanded in industry. [ABSTRACT FROM AUTHOR]

The composites of epoxy resin-expanded graphite(EG)-vermiculite and epoxy resin-expanded graphite-perlite were obtained and their electrophysical properties were analysed at low frequencies and in the microwave range. High values (> 30) of real and imaginary components of the complex permittivity for both systems were achieved with a content of EG of less than 2 wt. %. The values of the percolation threshold and critical index of systems were defined: for a system with vermiculite the percolation transition (φc = 0.0018); and for a system with perlite (φc =0.0039). The method of impedance spectroscopy (10-2–106 Hz) shows that for all investigated composites there is no dependence of electrical conductivity to frequency, but up to a value of 103 Hz, indicating a low level of ionic conductivity. It was found that the difference in electrophysical characteristics of two systems with the same content of the expanded graphite arises due to the nature of the surface of the dielectric components. The best indicators, namely, the lower percolation threshold and the achievement of maximum electrical conductivity values at lower EG, are in the system with vermiculite. It is due to the hydrophobic properties of the surface the filler particles, as well as the effect of the flow of a dielectric particle of vermiculite by a suspension of an epoxy resin-EG, while the particles perlite is impregnated with it. Changing the content of such dielectric ingredients allows us to expand the functionality of composites when used for shielding from electromagnetic fields. [ABSTRACT FROM AUTHOR]

Interest in particle extraction through liquid-liquid interface (PELLI) technology is motivated by the need to transfer particles directly from the synthesis medium to the device processing medium. This method avoids the difficulty encountered by conventional re-dispersion methods where particles agglomerate during the drying stage. We develop PELLI strategies to transfer MnO 2 , ZnO and CeO 2 particles that are synthesized in aqueous media into 1-butanol using extractors containing phosphonate and carboxylic groups. We demonstrate that, in addition to head-tail (HT) surfactants, molecules containing two hydrophilic end groups (HTH) can also be employed as extractors, a finding that opens new PELLI applications. We demonstrate this new approach using multifunctional HTH molecules as both PELLI extractors, and charged dispersing agents for the electrophoretic deposition (EPD) of particles that are transferred to an EPD processing medium. Using the HTH extractors for PELLI, we fabricate MnO 2 -based bulk electrodes for electrochemical supercapacitors (ES) that exhibit superior electrochemical performance. These high active mass loading ES electrodes have a capacitance of 5.7 F cm −2 (157 F g −1 ) and 2.5 F cm −2 (67 F g −1 ) at 2 and 100 mV s −1 scan rates, respectively, with low impedance. In another strategy, the use of HTH extractor for particle transfer to screen printing processing medium facilitates the fabrication of efficient thin film SC electrodes. Measurements provide insight into the influence of anchoring groups and extractor molecule structure on the extraction efficiency and electrochemical performance. [ABSTRACT FROM AUTHOR]

Non-covalent functionalization of Multi Wall Carbon Nanotubes (MWCNTs) could provide a solution for preserving their electronic structure facilitating the nanocomposite process preparation. Functionalization of MWCNTs by π-stacking interaction between nanofiller and a pyrene derivative has been explored. The rheological properties of filled epoxy resins highlight very interesting benefits from this kind of functionalization. Besides its peculiar capability for preventing agglomeration in the nanofiller dispersion step, it also efficiently contributes to a decrease in the viscosity of the nanocomposites; hence contrasting one of the most relevant drawback related to the manufacturing processes of the nanocomposites at MWCNTs loading rates beyond the Electrical Percolation Threshold (EPT). Because no damage of MWCNTs occurs, sp 2 hybridization of carbon atoms is preserved together with the π-electron delocalization typical of polynuclear aromatic rings. Consequently, no deterioration in the electrical properties are detected; the measured EPT values are typical of nanocomposites containing embedded unfunctionalized MWCNTs (lower than 0.28 wt%), whereas for the electrical conductivity beyond the EPT, an enhancement is observed. [ABSTRACT FROM AUTHOR]

This study investigated the effect of milk packet waste (Tetra Pak™) and maleic anhydride–grafted polyethylene (MAPE) on the physical and mechanical properties of wood–plastic composites. Tetra Pak was used in four levels (0, 10, 20, and 30%) and MAPE was applied in two levels (0 and 3%). The morphology of the samples was characterized using the scanning electron microscope technique. The results showed that adding Tetra Pak and MAPE to samples increased the flexural strength and modulus of elasticity and reduced 24-h water absorption and thickness swelling. The results were also confirmed by electron microscopy images. [ABSTRACT FROM AUTHOR]