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Composites of polypropylene with different weight percentages of ZnO-TiO2 core-shell nanoparticles were prepared by the combination of solution and mixture melting methods. Dielectric properties of polypropylene composite films were studied at frequencies ranging from 50 Hz to 5 MHz at four different temperatures (313, 333, 353, and 373 K). It is observed that the dielectric constant reduces quickly in the low-frequency range followed by a near frequency independent behavior above 1 KHz. The dielectric properties of composites at low frequency can be explained by interfacial polarization or Maxwell-Wagner-Sillars effect. It is also observed that the dielectric constant reaches the maximum value at 3 wt% of ZnO-TiO2, which is the percolation threshold of nanocomposite. As the weight percentage of ZnO-TiO2 increases beyond the percolation threshold up to 7%, the dielectric constant of the nanocomposites decreases. The dielectric loss of the composites follows the similar trend with frequency as the dielectric constant. A sharp increase in the dielectric loss of the nanocomposite observed near the percolation threshold is due to leakage current produced by the formation of conductive network by ZnO-TiO2 core-shell nanoparticles. Further, peaks in the loss tangent observed for the nanocomposite systems indicating the appearance of a relaxation process. These relaxations peaks were shifted to higher frequencies as the particle content increased, since relaxation processes were influenced by the interfacial polarization effect which generated electric charge accumulation around the ZnO-TiO2 core-shell nanoparticles.

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.

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.

In this work, new films containing composite materials based on blends of thermoplastic polymers of the polyurethane (TPU) and polyolefin (TPO) type, in the absence and presence of BaTiO3 nanoparticles (NPs) with the size smaller 100 nm, were prepared. The vibrational properties of the free films depending on the weight ratio of the two thermoplastic polymers were studied. Our results demonstrate that these films are optically active, with strong, broad, and adjustable photoluminescence by varying the amount of TPU. The crystalline structure of BaTiO3 and the influence of thermoplastic polymers on the crystallization process of these inorganic NPs were determined by x-ray diffraction (XRD) studies. The vibrational changes induced in the thermoplastic polymer’s matrix of the BaTiO3 NPs were showcased by Raman scattering and FTIR spectroscopy. The incorporation of BaTiO3 NPs in the matrix of thermoplastic elastomers revealed the shift dependence of the photoluminescence (PL) band depending on the BaTiO3 NP concentration, which was capable of covering a wide visible spectral range. The dependencies of the dielectric relaxation phenomena with the weight of BaTiO3 NPs in thermoplastic polymers blends were also demonstrated.

The final publication is available at Springer via http://dx.doi.org/10.1007/s00158-020-02823-w The present contribution describes an optimization-based design technique of elastic isotropic periodic microarchitectures with crystal symmetries aiming at the realization of composites with extreme properties. To achieve this goal, three consecutive procedures are followed: (i) a series of inverse homogenization problems with symmetry constraints, (ii) a correlation analysis between symmetries and effective elastic properties of the attained microarchitectures, and (iii) the pattern resemblance recognition of these topologies and their redesign, by adopting microstructures with two length-scales, through optimized parametric geometries. This paper is devoted to assessing the third procedure because the first two procedures have been evaluated in previous works of the authors, and here they are only summarized. By applying the methodology, two plane group symmetries are assessed to define two families of 2D periodic parameterized microarchitecture. Once the parameters have been optimized, the resulting composites achieve elastic isotropic properties close to the whole range of the theoretically estimated bounds. Particularly, an unprecedented microstructure attaining the theoretical maximum stiffness is reported. Starting from these parameterized topologies, simple, one-length scale, and easily manufacturable geometries are defined. One of the so-designed microarchitectures has been manufactured and tested, displaying an effective Poisson’s ratio of -¿0.90 simultaneously with a high shear modulus.

Composites proton conducting material based on cesium dihydrogen phosphate (CDP) doped with zirconium oxide (1−x) CsH2PO4/x ZrO2 were synthesized with different concentration having in the range such as x = 0.1, 0.2, 0.3 and 0.4 by ball milling method. The prepared solid acid composites were dried at 150 °C for 6 h. Structural and thermal characterization of solid acid composite proton electrolytes were carried out by X-ray diffractometer, Fourier transform infrared spectroscopy, and Raman spectroscopy respectively. Phase transition of the prepared materials was carried out by using differential scanning calorimetry and conductivity was measured by LC Impedance meter in the range 1 Hz to 400 kHz. The ionic conductivity of ZrO2 doped CsH2PO4 (CDP) was increased up to 1.3 × 10–2 S cm−1 at the 280 °C under environment atmospheric humidification which showed high stability as compared to pure CsH2PO4 (CDP). This obtaining result would be useful for establishing and design the next generation fuel cell.

In this work, polymer composite materials based on linear low-density polyethylene and nanoparticles of copper oxide were characterized in view of their physical and mechanical properties. Various concentrations of nanosized CuO filler were tested. It was found, that physical and mechanical properties of resulting composite depend on the filler concentration. Mechanical parameters were studied in static and dynamical regimes as well as temperature dependence of dynamic behavior of composite samples was examined.

This study investigated the properties and sustainability of cement-bonded composites containing industrial residues such as wood chips, tyre fibres and biomass combustion residues, i.e. bottom ash (BA) and fly ash (FA). The effect of cement-to-raw material (wood/tyre fibre) ratio (C/RM) and the aggregate content (BA and FA) on thermal and mechanical properties of the composites were investigated. Scanning electron microscopy (SEM) and life cycle analysis (LCA) were also conducted. The results revealed that as the aggregate content increased in wood composites, the mechanical properties also increased. The mean thermal conductivity and volumetric heat capacity of tyre composite samples were 0.37 W/mK and 1.2 MJ/m3K respectively, while the respective values for wood composite samples were 0.29 W/mK and 0.81 MJ/m3K. SEM analysis showed adequate bonding between wood/tyre fibres and cement matrix. LCA revealed that the materials share of the total primary energy use was about 60% for all analysed composites.

We present computational and theoretical assessments on the effective dielectric properties of the nonlinear composites comprised of ferroelectric ceramic inclusions (barium strontium titanate (BST)) and/or ferromagnetic inclusions (nickel zinc ferrite (NZF)) in a linear host to serve as materials for nonlinear transmission lines (NLTLs). We compare classical effective medium theories (EMTs) and computational models using CST Microwave Studio (CST MWS) to predict the dielectric and magnetic properties of the composites in the linear region to measurements. The composite models in CST MWS agree well with measurements and the Lichtenecker rule for NZF composites, while classical EMTs generally fail to estimate effective properties for the cases with high volume loadings and strong dielectric contrast.

Structural, thermal and mechanical properties of the compostable composites comprising a biodegradable aliphatic-aromatic copolyester (namely, the poly(butylene adipate-co-terephthalate; PBAT), and microcrystalline cellulose (MCC) derived from agricultural waste, the wheat stalk, were investigated. Purely physical interaction between the components was found to be responsible to get the MCC phase quite uniformly embedded in the PBAT matrix, the latter being the dominating component of the composites surface. There were two distinct thermally activated degradation regimes characterized by separate activation processes corresponding to the decomposition of the MCC and the PBAT phases, respectively. The physically bound and rather weak but large PBAT-MCC interfacial areas provoked more rapid thermal degradation of the composites compared to the pure components. While the PBAT acted as a highly ductile material upon tensile loading, the composites maintained high ductility only up to 20% by weight of the MCC. The drastic reduction in the ductility for higher filler loading was attributed to the possible void formation at the interfacial region followed by crack initiation and propagation leading eventually to the premature specimen fracture. The composite materials thus fabricated were hence found to suit for low-load bearing applications.

Composites of calcinated bovine bone derived hydroxyapatite (BHA) doped 1 and 2 wt% MgF2 were prepared by a sintering process. Microstructure and crystallographic analyses along with measurements of density, compression strength, and microhardness were carried out in the produced samples. The experimental results indicated a beneficial effect of MgF2 in the matrix of BHA reflected in the significant increase of compression strength and microhardness up to 143 MPa and 313 HV, respectively, achieved after sintering at 1300 0C for 2% MgF2 addition. The presence of MgF2 reduced the onset of sintering towards lower temperatures (i.e. 1100 0C) and increased the stability of hydroxyapatite towards transformation to TCP at 1300 0C. The influence of Mg2+ and F- ions in the lattice of hydroxyapatite is discussed.

The antimicrobial functionality of composites constituted by chitosan with silver-doped zeolites was developed and characterized. A composite with chitosan particles and silver-doped zeolites was synthesized using an ionic gelation process with sodium tripolyphosphate. The chitosan silver-doped zeolites composite obtained presented sizes up to 5 mu m, while the silver-doped zeolites had an average size between 0.5 mu m and 3.3 mu m. The synthesized chitosan silver-doped zeolites composites, as well as the silver-doped zeolites and the chitosan dissolution, were characterized through X-ray diffraction, Fourier Transform Infrared spectroscopy and scanning electron microscopy. The electro kinetic behaviour of chitosan, silver-doped zeolites and chitosan silver-doped zeolites composite was evaluated under different pH conditions. The antimicrobial activity of the composites was evaluated in terms of minimum inhibitory concentrations and minimum lethal concentrations and the results suggest that the chitosan silver-doped zeolites composites show antimicrobial activity against gram-negative and gram-positive bacteria, Escherichia coli and Staphylococcus aureus, respectively and against Candida albicans. The results here presented support the potential application of the composite of chitosan with silver-doped zeolites in the functionalization of textiles with antimicrobial properties., Fabio A. P. Scacchetti thanks to the CNPq-Brazil (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-Brasil/National Council of Scientific and Technological Development-Brazil) for the doctoral scholarship (233550/2014-3). Artur Ribeiro and Artur Cavaco-Paulo thanks to the Portuguese Foundation for Science and Technology (FCT) for the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER000004) funded by European Regional Development Fund under the scope of Norte2020-Programa Operacional Regional do Norte. This work is also financed by Project UID/CTM/00264/2019 of 2C2T-Centro de Ciencia e Tecnologia Textil, funded by National Founds through FCT/MCTES.

The sheer amount of waste being produced nowadays by the food processing industry makes it imperative to identify alternative procedures to recycle them. This paper describes an innovative use of protein waste with consumed plastic bottles within composite materials for building applications. The aim of this study was to investigate this two wastes association on the lightening of the composites. The effect of the protein waste introduction on the physical properties of the concrete manufactured with PET aggregates in the hardened state is studied: total and surface porosity, mechanical strengths, dynamic elasticity modulus and thermal conductivity. The optimal formulation of the basic composite, with PET aggregates, is: S/C = 2.8, W/C = 0.45 and a volume percentage of PET aggregates equal to 35%. The hemoglobin powder was introduced after water in the optimal PET composite. Various H/C mass ratios were used: 0.5, 1 and 2%. The influence of the mixing time after hemoglobin addition was also studied. Relative changes in composites properties due to protein introduction are experimentally investigated. For example a decrease in mechanical strengths and in thermal conductivity was observed. The results obtained allowed the elaborated composites to be functionally classified. So they show that the simultaneous valorization of two kinds of waste of the food process industry may be technically feasible and very interesting for the environment.

This paper presents a solution of the elastic fields of a half-plane composite structure containing distributed multiple circular inhomogeneities under boundary loading. The solution is obtained with a semi-analytical approach by combining the Green’s function and the equivalent inclusion method. This approach can achieve high accuracy and can be easily implemented with less computational effort compared with other numerical methods. Then, this solution is further used to explore the boundary effects on the elastic fields and effective elastic properties of the half-plane composite structure containing square periodically distributed circular inhomogeneities. Influences of the boundary and the inhomogeneity volume fraction on the elastic fields are examined in detail. Local effective elastic constants of the composite structure are predicted using the unit cells. The results show that the boundary has a significant effect on the elastic fields and elastic properties of the half-plane composite structure. The average displacement predicted with the conventional effective elastic constants of unit cells may deviate from the real value. Thus, we propose a design of a composite structure with a uniform elastic constant and develop an analytical model to calculate the average displacement.

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Technology for 3D printing allow to create parts with different shapes and directions of inner structures for example: triangles, squares or hexagons. Paper is focused on comparing mechanical properties of composite structure on Onyx base with different density and shape of fill. Specimens were created by 3D printing from composite material Onyx. At creation specimens were used different structures, which allows software of 3D printer Mark Two. Tested specimens are different in density and shape of inside structure. Aim of paper is find mechanical properties of specimens and compare this properties among each other. From results to determine the most advantageous shape and density of inside structure, which can be used in transport industry and in another sectors of industry.

The article presents data on the increase in adhesion strength at the delamination of fluorine-containing rubber and composite F4G25 based on PTFE, containing 25 mass.% fiberglass. An increase in the adhesion strength during the delamination of modified PTFE with rubber based on fluorinated rubbers with additional surface modification of the fluoroplastic composite PTFE by 3-glycidoxypropyltrimethoxylane in ethanol, previously treated with a solution of sodium naphthalene complex in tetrahydrofuran, is shown.

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 (φ c = 0.0018); and for a system with perlite (φ c =0.0039). The method of impedance spectroscopy (10 -2 –10 6 Hz) shows that for all investigated composites there is no dependence of electrical conductivity to frequency, but up to a value of 10 3 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.

Polymer composites were prepared from (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals grown using Bridgman–Stockbarger method. The impedance measurements were performed at room temperature in the frequency range 10 –3 –2·10 6 Hz. The frequency dependences of electrical conductivity and dielectric permittivity for composites based on (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals were obtained. The Nyquist plots for (Ag 1–x Cu x ) 7 GeS 5 I-based composite has been analyzed. The influence of cation Ag→Cu substitution on electrical conductivity of composites based on (Ag 1–x Cu x ) 7 GeS 5 I mixed crystals has been studied.

The use of fiber-reinforced composites in marine applications such as components of tidal turbines and wave energy converters is becoming attractive because of their reduced weight and improved corrosion resistance. However, when these polymer matrix composite structures are exposed to seawater environment, degradation of material properties is produced affecting reliability. A deep understating of seawater ageing effect on composite structures is essential to ensure long-term performance and durability. A systematic investigation was conducted in this work to evaluate the effect of seawater ageing on mechanical properties of five different composites manufactured with two types of fiber fabrics (unidirectional glass and carbon) and three types of resin systems (epoxy, vinylester and polyester). The behavior of samples with and without accelerated seawater ageing and subjected to tensile, compressive, flexural and shear loading was evaluated. A significant strength reduction due to seawater ageing was observed on composites with epoxy and polyester matrices. Low strength and stiffness values of composites with vinylester matrix are in general observed; however, seawater ageing makes these properties increase slightly. Fracture surface examination by scanning electron microscopy revealed delamination, fiber debonding and resin crumbling due to seawater effect.

Samples of composites based on epoxy resin and sunken-loop knit fabric with satin and lasting 1+1 interlocking are investigated. It is shown that the strength anisotropy coefficient of the composite can be counted as a double ratio of the knit fabric density along the course to the knit fabric density along the wale. The extensibility of the knit fabric does not have a significant effect on the strength of the composite reinforced by it. The maximum strength of the composite is attained when the loop modulus is above 50. In mechanical properties, composites with a knit fabric filler are close to composites with quasi-continuous reinforcement, for example, with individual unidirectional threads.

The work has evaluated the possibility of the potential reinforcing of poly(oxymethylene) (POM) by basalt fibers (BFs) and influence of BFs addition on thermal properties. Two types of composites were produced by injection molding. There were 20 and 40 wt% long BFs content with an average length of 1 mm. The samples were made without using a compatibilizer. In the experimental part, the basic mechanical properties (tensile strength, modulus of elasticity, strain at break, flexural modulus, flexural strength, and deflection at 3.5% strain) of composites based on POM were determined. Tensile properties were also evaluated at three temperatures −20°C, 20°C, and 80°C. The density and Charpy impact of the produced composites were also examined. The influence of water absorption on mechanical properties was investigated. Thermal properties were conducted by the differential scanning calorimetry, thermal gravimetric analysis, and fourier transform infrared (FTIR)-attenuation total reflection (ATR) spectroscopy analysis. In order to make reference to the effects of reinforcement and determine the structure characteristics, scanning electron microscopy images were taken. The addition of 20 and 40 wt% by weight of fibers increases the strength and the stiffness of such composites by more than 30–70% in the range scale of temperature. Manufactured composites show higher thermal and dimensional stability in relation to neat POM.

We investigated thermal properties of the epoxy-based composites with the high loading fraction-up to f ≈ 45 vol %-of the randomly oriented electrically conductive graphene fillers and electrically insulating boron nitride fillers. It was found that both types of the composites revealed a distinctive thermal percolation threshold at the loading fraction fT > 20 vol %. The graphene loading required for achieving thermal percolation, fT, was substantially higher than the loading, fE, for electrical percolation. Graphene fillers outperformed boron nitride fillers in the thermal conductivity enhancement. It was established that thermal transport in composites with high filler loadings, f ≥ fT, is dominated by heat conduction via the network of percolating fillers. Unexpectedly, we determined that the thermal transport properties of the high loading composites were influenced strongly by the cross-plane thermal conductivity of the quasi-two-dimensional fillers. The obtained results shed light on the debated mechanism of the thermal percolation, and facilitate the development of the next generation of the efficient thermal interface materials for electronic applications.

In the last five years, the number of laminated glass produced in Poland for the automotive industry has almost doubled. It is the effect of increasing requirements in the area of vehicle safety and use. This also caused the increase in the amount of waste in glass production technology. The demands of circular economy require the re-use of waste as raw materials. PVB as a structural material is characterized by good mechanical properties in a wide range of positive and negative temperatures and high sensitivity to moisture (high hygroscopy). On the basis of PVB waste from the production of glass and using recyclate of polyethylene and polyester-glass dust, new material composites were made. Taking into account the hygroscopic properties of PVB, aging tests of new materials were made after exposure to them in the HHC climate. The influence of the aging process on the tested properties was determined. The results confirmed the possibility of using composites for technical products in the automotive industry.

This study aimed at producing the biodegradable composite from lignocellulose nanofibers (LCNFs) and Pebax®thermoplastic elastomer. For this purpose, LCNFs at different levels of 0, 1, 3, and 5% were considered. The LCNFs were prepared by benzyl alcohol and then mixed with Pebax®. The liquid phase of the LCNFs and soluble polymer was prepared and then the masterbatches were mixed in an internal mixer (Model 815802, Brabender, Germany). The mixtures from the internal mixer were put into a hot press and test samples were compress-molded. The physical properties results indicated that water absorption and thickness swelling decreased by the addition of more amount of LCNF. By the addition of LCNFs to polymer, the tensile strength and modulus and impact strength were increased compared to samples without LCNF. No regular trend of enthalpy changes was observed as the content of LCNF changed. When the LCNF concentration was increased to 5%, the crystallization temperature was increased. As the LCNF concentration increased to 3%, the glass transition temperature ( Tg) was decreased, whereas by incorporating more LCNFs, the Tgwas increased. The result of the Fourier transform infrared spectra showed the peaks at 1740 cm−1which indicated the presence of polyamide bonds. Also, new peaks were observed in the range of 1400–1500 cm−1that was probably related to the presence of C−C bonds of glucose at LCNFs chains.

Copper–matrix–carbon nanotubes (Cu–CNTs) composite films were prepared in a Cu plating solution with multiwall carbon nanotubes (MWCNTs) using electrodeposition. The MWCNTs surface treatment method, electroplating solution system, electroplating conditions, heat treatment process and other parameters of this process are discussed. The results showed that MWCNTs purified by HCl treatment and dispersed by stearyltrimethylammonium bromide are more suitable as add-on materials for the preparation of the copper matrix composite films by electrodeposition. An appropriate heat treatment process was able to improve the structures and properties of the composite films. The final products showed that the MWCNTs were evenly distributed in the composite films and joined with the copper grains to form a mutually entangled mesh structure with excellent corrosion resistance (3.19 × 10−8 Ω M) and a hardness of 53.5 HV. All this was possible through extensive optimization of the electrodeposition and post-treatment parameters.

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.

This paper presents the problems associated with changes in resistance to the tribological wear of light-cured polymer matrix ceramic composites (LC PMCCs) used in conservative dentistry and in dental prosthetics (fillings of carious cavities, dental bridges, structural reinforcements of the dental arch). Wear resistance of the surface layer of PMCCs depends on the time of exposure to the conditions of the oral environment, such as alternating temperatures and the exposure to liquids. The aim of the study was to assess changes in the mechanical properties of the surface layer under thermal cycling in liquid. Indentation hardness tests and scratch tests were performed before and after conditioning. Conditioning included 10,000 cycles of step temperature changes (10–70°C). The results of the scratch tests showed that universal composites that had relatively high filler contents were more resistant to scratching than flow type composites with lower filler contents. It was found that cyclic changes in ambient temperature reduced the wear resistance of universal composites but improved the resistance of flow type composites. In addition, in the case of flow type composites, the hardness of the surface layer was also increased.

A novel three-dimensional composite of reduced graphene oxide sheets and porous LiFe5O8 microspheres was fabricated via a facile, green, and highly tunable strategy, and the microstructure, composition, and microwave-absorbing performances of the rGO/porous LiFe5O8 composite were characterized and investigated. The experimental results indicate that the porous LiFe5O8 microspheres are dispersed on the thin rGO sheets uniformly. Compared with the pure LiFe5O8 particles and porous LiFe5O8 microspheres, the as-prepared rGO/porous LiFe5O8 composites exhibit outstanding microwave-absorbing performances including efficient bandwidth and reflection loss. The rGO/porous LiFe5O8 composite (S-50) displays a maximum reflection loss of −53.4 dB at 12.2 GHz with a coating layer thickness of 2.2 mm and a broad effective bandwidth of 3.5 GHz (from 10.4 to 13.9 GHz). The outstanding microwave-absorbing performances are assigned to employing magnetic microflowers with multi-interfaces to improve impedance matching, which ...

The paper describes the results of a study of composites with bentonite fillers and their dielectric properties as a function of the percentage of the dispersant and the alternating electric field frequency. It has been found that the pronounced dispersion of the dielectric parameters of the composites is caused by charge migration and localization at intrinsic point defects and at the interfaces with the sublattice of the dispersant.

In order to enhance the microwave-absorbing and shielding properties of the composites, the flaky FeSiAl particles embedded in an epoxy polymer were aligned with a two-dimensional rotating magnetic field. The morphologies, electromagnetic (EM) characteristics, and microwave-absorbing and shielding properties of the unaligned and aligned FeSiAl/epoxy composites were investigated. The results showed that after alignment treatment, the flaky FeSiAl particles tend to orient uniformly in the rotating magnetic field, and the permittivity and permeability of the aligned composites were increased in the frequency range of 1–18 GHz compared with that of randomly distributed composites. The calculated microwave-absorbing properties indicated that the peak value of the return loss (RL) of the aligned composites can reach 8.8 dB, compared with 5.8 dB of the unaligned composites of 2.5 mm in thickness (60 wt%); and the bandwidth with RL value more than 6 dB is in a wider frequency range from 1 to 2.8 GHz. And the calculated shielding effectiveness (SE) of the aligned composites is 1.1–3 times higher than that of unaligned one in every thickness, and the maximum SE of the aligned one is 31.8 dB at 18 GHz with a thickness of 2.5 mm.

Research on three-dimensional, randomly distributed BFRC in China is analyzed and summarized in relative depth in this study. The results indicate that the effect of the fiber component and alkali corrosion temperature on the alkali resistance of BF is significant; the BF has little effect on the compressive strength of the concrete; the tensile and flexural strengths of the composites significantly increase compared with plain concrete, and the fiber content has a significant effect on the strength. In light of some problems in the current research, six possible research topics are suggested: (1) investigating the alkali resistance of the BF under dynamic temperatures, lower alkali concentrations, and longer alkali corrosion times; (2) improving the alkali resistance of the BF by increasing its hydrophobicity; (3) determining the optimal fiber distribution orientation of the BF with various characteristic parameters; (4) establishing the calculation formulas for the critical content and critical aspect ratio of various types of BF; (5) determining the optimal mixture ratio of two or more fibers in the FRC while studying the complementary mechanisms between each other; and (6) improving the dispersion of the BF and the BF/matrix interfacial properties.

The Fe–Ni–O system designed for producing bimetal-containing composite anodes of solid oxide fuel cells (SOFCs) was studied. The solubility of nickel in the structure of spinel (Fe,Ni)3O4 ± δ at atmospheric oxygen pressure is ~1/3. Moderate reduction at 1023 K and p(O2) ≈ 10–20 atm leads to partial decomposition of spinels, forming an electron-conducting phase (Fe,Ni)1–yO and submicron bimetallic Fe–Ni particles on the oxide surface, which have potentially high catalytic activity. The electron conductivity has a thermally activated character and increases substantially during the reduction. In the anode conditions of SOFCs, the electric conductivity reaches 30–100 S/cm, while the thermal expansion coefficients are ~12 × 10–6 K–1, which ensures compatibility with solid electrolytes. At the same time, significant volume changes during the redox cycling (up to ~1% on the linear scale) necessitate the introduction of additional components such as yttria-stabilized zirconia (YSZ). The polarization resistance of the model composite anode of reduced Fe2NiO4 ± δ and YSZ deposited on the YSZ solid electrolyte membrane was ~1.8 Ohm cm2 at 923 K in a 4% H2–Ar–H2O atmosphere.

Development of three-dimensional (3D) weaving technology introduced new and enhanced features to the 2D weaving technology. 3D Orthogonal Woven (3DOW) preforms have a through-thickness yarn component that significantly enhances the out-of-plane properties and delamination resistance. In this study, a range of 3DOW E-glass preforms were woven using 3D weaving technology and then converted into composites, using vacuum assisted resin transfer molding technology. The composite samples had varying Z to Y-yarn/ layer ratio, the objective is to study the effect of changing the Z to Y-yarn/ layer ratio on the in-plane and out-of-plane mechanical properties. The study concludes that changing the amount of Z-yarn in the structure has negligible effect on the tensile (in-plane), yet, it has a significant effect on the drop weight impact properties (out-of-plane). Moreover, it had a strong effect on the failure mechanisms, and as the amount of Z-yarn is reduced, delamination became more significant.

Magnetoactive elastomers (MAE) made from composites of five thermoplastic elastomers (TPE) of different stiffness with carbonyl iron powder (CIP) as magnetic component were investigated. The composites were produced by melt blending of the magnetic particles with the TPEs in a twin-screw extruder. The resulting materials were characterized by ac permeability testing, stress–strain measurements with and without external magnetic field and magnetically controlled bending of long cylindrical rods in a homogenous magnetic field. The magnetic field necessary for deflection of the rods decreases with decreasing modulus and increasing iron particle content. This effect can be used e.g. for magnetically controlled actuation. Some highly filled MAE show a magnetic field induced increase of Young’s modulus. Filaments could be spun from some of the composites.

In this paper, we report structural and magnetic properties of BaSnO3(BSO)(1−x)–CoFe2O4 (CFO)(x) composite (with x = 0%, 1% (C1), 2% (C2) and 5% (C3) in molar ratio) synthesized using nitrate precursor method. The X-ray diffraction (XRD) pattern of the composite powder confirmed presence of both BaSnO3 with the cubic perovskite structure and CoFe2O4 with the cubic spinel structure. No signature of any other phases in pure BaSnO3, CoFe2O4 and composites have been detected either in XRD or energy dispersive X-ray (EDS) analysis. The temperature dependent zero field cooled (ZFC) & field cooled (FC) magnetization and magnetic field dependence magnetization measurements have been carried at room temperature of the pure BaSnO3. We observe a weak ferromagnetic (FM) behavior at room temperature in pure BaSnO3 even though it is non-magnetic in nature. The room temperature Raman spectroscopy and electron spin resonance measurements of the sample confirm the presence of oxygen vacancy and formation of F-center, which is responsible for the FM behavior. The oxidation state and elemental analysis have been carried out using X-ray photoelectron spectroscopy (XPS). The magnetic field dependence of magnetization of the composite samples reveal increase of saturation magnetization (Ms), remanence magnetization (Mr) and coercivity (Hc) with increase in ferrite content in the composite. Significant enhancement in FM components is observed with lowering of temperature.

The eff ect of Taunit grade carbon nanotubes on the kinetic parameters of block radical copolymerization of acrylonitrile and methacrylic acid in the presence of foaming agents (tert-butyl alcohol – N-methylformamide system) was studied. Thermoimidization and foaming of acrylonitrile and methacrylic acid copolymers produced foamed nanocomposites based on polymethacrylimides, carbon nanotubes and finely dispersed silicon oxide. It is shown that the dependences of the density of composites and their strength characteristics on the content of carbon nanotubes pass through a maximum.

The aim of this paper is to evaluate the effective properties of composite materials with periodic random packing of ellipsoids of different volume fractions and aspect ratios. Therefore, we employ computational homogenization. A very efficient MD-based method is applied to generate the periodic random packing of the ellipsoids. The method is applicable even for extremely high volume fractions up to 60%. The influences of the volume fraction and aspect ratio on the effective properties of the composite materials are studied in several numerical examples. NSFC/51474157 National Basic Research Program of China/973 Shanghai Qimingxing Program/16QA1404000 State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining & Technology Key/SKLGDUEK1526

In this study, 0.5 wt% Ni-P@GNF/ Ti-6Al-4V composites with different particle sizes (0–25, 15–53 and 53–150 μm) were fabricated via chemical nickel plating and speak plasma sintering. The plasma sintering temperature and the sintering pressure were 900 °C and 50 MPa, respectively. The microstructure and mechanical properties of the three composites were investigated via optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and compression experiments. The results showed that the microstructures of the composites were refined, and the compressive strength of the Ti-6Al-4V incorporated with graphene nanosheets was higher than that of the pure Ti-6Al-4V. Herein, with 0–25 μm Ti-6Al-4V powder, the compressive strength of 0.5 wt% Ni-P@GNFs/TC4 composite reaches 1339 MPa, which was an increase of 37.91% versus Ti-6Al-4V alloy (970 MPa). Moreover, with increasing spherical powder particle size, the size of the reinforcing phase of the network structure was coarser, and the plasticity was improved.

A series of telechelic silicon-containing hybrid polymers with reactive ethynylphenyl terminals were synthesized using the Grignard reagent method. The structure, processability, curing behavior, thermal stability and dielectric properties of the polymers, as well as the mechanical properties of carbon fiber reinforced composites at room temperature and high temperature, were well characterized. The results indicate that the ethynylphenyl-terminated poly(silylene acetylene)s (EPTSAs) have wide processing window and stable viscosity for 6 h at 70 °C. The cured EPTSAs exhibit excellent thermooxidative stabilities with temperatures of 5% weight loss (Td5) and the residues at 800 °C (Yr800). The thermal stability of the cured EPTSAs can increase markedly with incorporation of Si-H groups. The Td5 and Yr800 of the cured EPTSAs could reach to 601 °C and 52% in air, respectively. The pyrolysis behavior of cured EPTSAs elucidates the cure reactions and cross-linked networks. The cured resins show excellent dielectric properties in the frequency range of 10–106 Hz. Furthermore, the glass transition temperature the cured EPTSAs do not arise before 500 °C. The flexural strength and modulus of the carbon fiber cloth (T300CF) reinforced EPTSAs composites could reach 252 MPa, and 42 GPa. The retention of mechanical properties of the composite at 300 °C can reach to 89%.

The structural, magnetic and electrophysical properties of composites based on nanosized magnetite chemically modified of copper iodide and polychlortrifluoroethylene have been studied at temperatures 298 – 450 K and CuI concentrations of from 0 to 0,58 volume. It has been found the optimal volume content of copper iodide ( 0,4) in the composites CuI/Fe3O4, when the interfacial interaction shows most intensively and maximum values electrical parameters take place. The value of the coercive force of nanocomposites CuI/Fe3O4 increases with increasing content copper iodide. It was shown that polymer composites containing CuI/Fe3O4, have higher values of real and imaginary components of complex permittivity and conductivity compared with a system that contains only copper iodide. Keywords: magnetite, copper iodide, nanocomposites, specific magnetization, interfacial interaction.

In this paper, a standardization modelling method of composites micro-scale simulation is proposed, in which the random distribution of fiber, hydrostatic pressure sensitivity yield behavior of polymer matrix and friction effect in fiber/matrix interface are considered. After the detailed introduction of the constitutive models of polymer matrix and interface, the methods to determine the input data of polymer, fiber and interface are provided. Then the stress-strain curves of composites under uniaxial loads were simulated and compared with experiment, which proving the accuracy of the micro-scale model. Besides, the comparison of failure envelopes under transverse stress and longitudinal shear stress of simulation and experiment further verified the validity of the model. Finally, the influence of the geometry, friction coefficient and interface properties on the mechanical properties of composites were discussed. The proposed modelling method provides a standardization means to establish micro-scale model, thus easy to be reproduced by other researchers.

The effect of compounding method is studied with respect to the rheological behavior and mechanical properties of composites made of wood flour and a blend of two main components of plastics waste in municipal solid waste, low-density polyethylene (LDPE) and high-density polyethylene (HDPE). The effects of recycling process on the rheological behavior of LDPE and HDPE blends were investigated. Initially, samples of virgin LDPE and HDPE were thermo-mechanically degraded twice under controlled conditions in an extruder. The recycled materials and wood flour were then compounded by two different mixing methods: simultaneous mixing of all components and pre-mixing, including the blending of polymers in molten state, grinding and subsequent compounding with wood flour. The rheological and mechanical properties of the LDPE/HDPE blend and resultant composites were determined. The results showed that recycling increased the complex viscosity of the LDPE/HDPE blend and it exhibited miscible behavior in a molten state. Rheological testing indicated that the complex viscosity and storage modulus of the composites made by pre-mixing method were higher than that made by the simultaneous method. The results also showed that melt pre-mixing of the polymeric matrix (recycled LDPE and HDPE) improved the mechanical properties of the wood–plastic composites.