Compressive mechanical properties of closed-cell aluminum foam–polymer composites

The compressive mechanical properties of two kinds of closed-cell aluminum foam–polymer composites (aluminum–epoxy, aluminum–polyurethane) were studied. The nonhomogeneous deformation features of the composites are presented based on the deformation distributions measured by the digital image correlation (DIC) method. The strain fluctuations rapidly grow with an increase in the compressive load. The uneven level of the deformation for the aluminum–polyurethane composite is lower than that for the aluminum–epoxy composite. The region of the preferentially fractured aluminum cell wall can be predicted by the strain distributions in two directions. The mechanical properties of the composites are investigated and compared to those of the aluminum foams. The enhancement effect of the epoxy resin on the Young’s modulus, the Poisson’s ratio and the compressive strength of the aluminum foams is greater than that of the polyurethane resin.     

Mechanical and failure behaviour of hybrid polymer–metal staked joints

Structural applications that use multi-material structures in the transportation industry have increased in recent years. Weight reduction in order to avoid excessive emissions is the driving force of this trend. The current joining technologies for such complex structures have potential for engineering and performance improvement. This preliminary study shows an alternative joining method for hybrid structures, the so-called Injection Clinching Joining (ICJ) [Abibe et al., J Thermoplast Compos 2011;24(2): 233–49], based on the principles of staking, injection moulding, and mechanical fastening. The main objectives of the paper are to exploit the mechanical behaviour of overlap joints produced by this proposed method and assess its potential as an applicable technology. The measurements used in this research are optical and scanning electron microscopy, X-ray computer microtomography, lap-shear strength testing and in situ strain distribution. Different failure modes were found, depending on the joining conditions. Net tension failure had a brittle and catastrophic nature, while rivet pull-out presented a more desirable slow ductile failure mode. The joint strengths were good, ranging from 35.9% to 88.5% of the base material’s experimental ultimate tensile stress. Although there is a lack of studies on structural staking applications, this paper shows potential for these joining techniques and introduces ICJ as a potential focus of future research.     

Synthesis and non linear optical properties of new inorganic–organic hybrid material: 4-Benzylpiperidinium sulfate monohydrate

Single crystals of 4-benzyl-piperidine sulfate monohydrate were grown by slow evaporation method at room temperature. The synthesized compound was characterized by means of single-crystal X-ray diffraction, FT-IR and Raman spectroscopy, UV–visible and photoluminescence studies. The title compound crystallises at room temperature in the non centrosymmetric space group P2₁2₁2₁.The recorded UV–visible spectrum show good transparency in the visible region and indicates a non-zero value of the first Hyperpolarizability. Photoluminescence spectrum shows a broad and intense band at 440 nm and indicates that the crystal emits blue fluorescence. We also report DFT calculations of the electric dipole moments (μ), Polarizability (α), the static first Hyperpolarizability (β) and HOMO–LUMO analysis of the title compound was theoretically investigated by GAUSSIAN 03 package. The calculated static first Hyperpolarizability is equal to 6.4022 × 10⁻³¹ esu. The results show that 4-benzyl-piperidine sulfate monohydrate crystal might have important non linear optical behavior and can be a potential non linear optical material of interest.     

Mechanical behaviour of polymer–metal hybrid joints produced by clinching using different tools

In the present study, the mechanical behaviour of polymer–metal hybrid connections produced by clinching is investigated. Thin sheets were joined using different tools including grooved, split and flat dies as well as rectangular tools. The effect of the joining force on joinability was also analysed. Polycarbonate was used as the polymer partner because of its high strength and toughness, while aluminium alloy AA6082-T6, which is characterized by a high yield stress but low ductility, was used as the metal sheet. Mechanical characterization involved single lap shear tests and peeling tests. According to the achieved results, grooved dies are not suitable for joining polymers. Rectangular clinching tools required lower joining forces and produced the highest peeling performances; however, because of the low ductility of the aluminium alloy, the joints were partially damaged resulting in the weakest shear strength. Round clinching tools required higher joining force compared to rectangular ones. The joints produced by flat dies were characterized by higher shear strength; however, because of the small interlock produced, they were characterized by small values of peeling strength. Round split dies allowed producing the joints with the highest performances in shear and peeling tests.     

Sol–gel preparation and luminescence of silica/polymer hybrid material incorporated with terbium complex

Methyl methacrylate (MMA) and ethyl methacrylate (EMA) doped with luminescent ternary europium complex (Tb(acac)₃·phen) with acetylacetone (Hacac) and 1,10-phenanthroline (phen) is incorporated into microporous silica gel, and the polymerization of MMA (and EMA), hybrid material containing Tb(acac)₃·phen has been obtained. The material exhibits good toughness and transparency. The TG-DTA curves have been determined, indicating that the hybrid matrix exhibits more thermal stability than that of the pure complex and pure polymer matrix. The luminescence spectra of all hybrid material doped with Tb(acac)₃·phen show the characteristic excitation and emission of europium ions and there exists some slight shift of maximum wavelength (about 380 nm), which implies the same energy transfer mechanism as the pure complex, and the hybrid matrix is a suitable substrate for the luminescence of europium ions. In the range of doping concentration of Tb(acac)₃·phen (0.05, 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 wt.%), emission intensities increase with the increasing of corresponding doping concentration and concentration quenching effect has not taken place. The emission spectra of terbium complex have been intensified by incorporating it into the hybrid matrix, and the specific emission intensities per complex formula unit is increased compared with that of original complex.     

Structural and optical properties of inorganic–organic hybrid material of acetanilide tetrachloromercurate(II)

The crystal growth of acetanilide tetrachloromercurate(II), an inorganic–organic hybrid derivative has been achieved by solution growth through slow cooling method. The X-ray diffraction structural analysis of the hybrid material results that the compound exist in orthorhombic space group P2₁2₁2₁ with lattice parameters; a?=?13.111(2) ?, b?=?11.311(2) ?, c?=?8.355(6) ?, α?=?β?=?γ?=?90° and unit cell volume?=?1436.24 ?³. The fourier transform infrared spectroscopy profile shows that the C–C and C–N stretching modes of acetanilide ring and the observed spectra falls in mid-infrared range υ(526–2850) cm^?1. The field emission scanning electron microscope image confirms that the hybrid material has a prismatic shape with an average granular size of ~25 nm. The energy dispersive X-ray spectroscopy analyzes the elemental proportions of the hybrid materials. Transmission electron microscopy image shows the narrow distribution of nano-spatial agglomeration of secondary interactions in inorganic–organic particles. The optical band gap (Eg?=?3.75 eV) as calculated by linear fit profile of Tauc plot for allowed transition predicts that the hybrid material has potential applications in solar cells, electronic and opto-electronic devices.     

Green-synthesized Zn-BTC metal–organic frameworks as a highly efficient material to improving electrochemical pseudocapacitance performance of P-type conductive polymer

Journal of Materials Science: Materials in Electronics - In the present study, we introduce a simple chemical method to synthesize Zn-based MOF (Zn-BTC). The structural morphology and...     

Changes to the morphology,structure and properties as a consequence of polyethylene working in a polymer–metal kinematic pair

A change is presented of the orientation of lamellar structure, degree of crystallinity, the degree of the spatial arrangement of the structure, micromechanical properties, and the surface morphology and thickness of a plastically deformed upper layer. These changes are the effect of work in a polymer–metal kinematic pair, which have occurred as a result of plastic deformation of polyethylene during its service. It has been shown that, as a result of selecting proper parameters of UHMW polyethylene via the initial draft and electron-beam irradiation, such a structure of the polymer can be obtained, which will enable the above-mentioned changes in morphology and structure to take place during service. This in turn, will allow a reduction of the susceptibility of the polymer to permanent deformation by 3–6 times, and its wear by more than 5 times, compared to the initial material.     

Numerical–experimental assessment of roughness-induced metal–polymer interface failure

A numerical–experimental method is presented to study the initiation and growth of interface damage in polymer–steel interfaces subjected to deformation-induced steel surface roughening. The experimentally determined displacement field of an evolving steel surface is applied to a numerical model consisting of a polymer coating and interface layer. The measured displacement field is obtained with a Finite Element based Digital Image Correlation method.The resulting simulations provide novel insights into the mechanical behaviour of the polymer–steel interface during interface roughening. The appearance of local hills and valleys on the evolving steel surface results in local bands of intensified stress in the polymer layer. These localized deformation bands trigger interface damage, which grows as the surface deformation increases. Polymer ageing initially delays the initiation of interface damage. However, for increased polymer ages the average interface damage increases. Likewise, the critical strain, at which the interface integrity is locally compromised, decreases.The presented method allows for a detailed study of the interface integrity during deformation-induced steel surface roughening. With properly identified material parameters, it becomes possible to tailor the polymer–steel material properties to minimize interface damage during production and storage of cans or canisters, e.g. for food and beverages.     

Study on nonlinear optical,dielectric and pyroelectric properties of novel organic–inorganic hybrid material

A novel organic and inorganic hybrid material was prepared from a nonlinear, optically active imidazole derivative, 4-(nitrophenyl)-2,4-bis-(4,4′-[N,N-bis-(2-hydroxyethyl)aminophen-yl])imidazole (NPAH4), and metal alkoxide of Ta(V) via sol–gel process. The second-order nonlinear and pyroelectric properties of the hybrid film were investigated in terms of the second harmonic generation (SHG) and pyroelectric coefficient measurement. The SHG coefficient d₃₃ was found to be 28.6 pm/V at the fundamental wavelength of 1064 nm and the pyroelectric coefficient P was found to be 1.6×10⁻⁶ C/cm² K.     

Effects of environmental aging on the mechanical properties of bamboo–glass fiber reinforced polymer matrix hybrid composites

Short bamboo fiber reinforced polypropylene composites (BFRP) and short bamboo–glass fiber reinforced polypropylene hybrid composites (BGRP) were fabricated using a compression molding method. Maleic anhydride polypropylene (MAPP) was used as a compatibilizer to improve the adhesion between the reinforcements and the matrix material. By incorporating up to 20% (by mass) glass fiber, the tensile and flexural modulus of BGRP were increased by 12.5 and 10%, respectively; and the tensile and flexural strength were increased by 7 and 25%, respectively, compared to those of BFRP. Sorption behavior and effects of environmental aging on tensile properties of both BFRP and BGRP systems were studied by immersing samples in water for up to 1200 h at 25°C. Compared to BFRP, a 4% drop in saturated moisture level is seen in BGRP. After aging in water for 1200 h, reduction in tensile strength and modulus for BGRP is nearly two times less than that of BFRP. Use of MAPP as coupling agent in the polypropylene matrix results in decreased saturated moisture absorption level and enhanced mechanical properties for both BFRP and BGRP systems. Thus it is shown that the durability of bamboo fiber reinforced polypropylene can be enhanced by hybridization with small amount of glass fibers.     

Controlling properties of metal–polymer soft magnetic composites through microstructural deformation for power inductor applications

Journal of Materials Science: Materials in Electronics - We studied the effect of microstructural deformation on soft magnetic metal powders in a power inductor operating above 1 MHz. In...     

The influence of a metal on transverse characteristics of hybrid waves in a layered ferrite–ferroelectric structure

We present electrodynamic characteristics of a layered multiferroic structure of metal–dielectric–ferrite–dielectric–ferroelectric–dielectric–metal type calculated by the finite elements method. Properties of transverse modes of hybrid waves (dispersion characteristics, electric field distribution at different frequencies, and damping rate) as functions of the distance between the ferroelectric layer and the metal screen are analyzed for the first time.     

Ceramic–metal and ceramic–polymer composites prepared by a biomimetic process

A biomimetic process was developed to prepare apatite–metal and apatite–polymer composites. A variety of metals and organic polymers incorporated surface functional groups such as Si–OH, Ti–OH or Ta–OH to induce formation of a biologically active bonelike apatite by chemical treatment or physical adsorption. Subsequent immersion in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma or 1.5 SBF led to the formation of a dense and uniform bonelike apatite layer on the surface. Apatite–metal and apatite–polymer composites prepared in this way are believed to be very useful as artificial bone substitutes.     

Tunable unidirectional light transmission in a graphene–metal hybrid metamaterial

Graphene’s unique properties, such as strong plasmonic response and electrostatic doping, enable control over the properties of light in an active way. In this paper, we propose a graphene–metal hybrid metamaterial, which exhibits tunable wideband unidirectional light transmission. The hybrid metamaterial consists of a complementary split-ring graphene and a metallic grating. Unidirectional optical transmission with a wide bandwidth of 14.8% of the central frequency at 29.3?THz and a large tuning range of 6.6?THz is found to be achievable in simulations. The light reflection and graphene absorption are shown to be the major factors limiting the efficiency of unidirectional transmission. A large electron scattering time of graphene is beneficial for improving the transmission efficiency. The graphene–metal hybrid metamaterial enables active control over the propagation of light, which could be of interest for infrared isolation, polarization transformation, etc.     

Mechanical properties of nanocomposite metal–ceramic thin films

Thin film composites consisting of metallic nanocrystals embedded in an insulating host have been synthesized using alternating-target pulsed laser deposition of Ni and Al₂O₃ on silicon (100) substrate. The evaluation of structural quality of the thin film composites using high resolution transmission electron microscopy and scanning transmission electron microscopy with atomic number contrast has revealed the formation of a biphase system with thermodynamically driven segregation of Ni and alumina during pulsed laser deposition. The best hardness values of the thin film composites, measured using nanoindentation techniques, were found to be 20–30% larger than pure alumina films fabricated under identical conditions. Fracture toughness measurements of the composite showed slight toughening due to embedding of Ni nanoparticles.     

Effects of intermediate metal layer on the properties of Ga–Al doped ZnO/metal/Ga–Al doped ZnO multilayers deposited on polymer substrate

Ga–Al doped ZnO/metal/Ga–Al doped ZnO multilayer films were deposited on polyethersulfone (PES) substrate at room temperature. The multilayer films consisted of intermediate Ag metal layers, top and bottom Ga–Al doped ZnO layer. The multilayer with PES substrate had advantages such as low sheet resistance, high optical transmittance in visible range and stable mechanical properties. From the results, sheet resistances of multilayer showed 9 Ω/sq with 12 nm of Ag metal layer thickness. Average optical transmittance of multilayer film showed 84% in visible range (380–770 nm) with 12 nm of Ag metal layer thickness. Moreover the multilayers showed stable mechanical properties than single-layered Ga–Al doped ZnO sample during the bending test due to the existence of ductile Ag metal layer.     

Synthesis and characterization of a new liquid polymer precursor for Si–B–C–N ceramics

A new liquid polyborosilazane precursor for Si–B–C–N ceramic was synthesized by co-condensation reaction of boron trichloride, organodichlorosilanes, and hexamethyldisilazane. The structure and properties of polyborosilazane were studied by means of Fourier transform-infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), rheology, and thermogravimetric analysis (TGA). The conversion of polymer to ceramic and the high-temperature behavior of the new polymer-derived ceramic were investigated by TG–MS, FT-IR, X-ray diffraction (XRD) and high-temperature TGA (HTGA). The ceramics showed good oxidative resistance and thermal stability with weight gain of 1.8 wt% at 1350 °C under air atmosphere and weight loss of 2.6% at 1900 °C under Ar atmosphere.