Properties Of New Composites Research Articles

Structure and properties of new composites composed of the all compound molecule cyclo[18]carbon and the polynitrogen molecule pentazole: A density functional theory study

In order to develop new composites composed of all carbon molecules and polynitrogen molecules, composites formed by a new all-carboatomic ring cyclo[18]carbon (C18) and a famous high energy molecule pentazole (N5H) with different proportions and sizes including N5H@C18, N5H@ 2 C18, 2 N5H@C18 and 2 N5H@ 2 C18 were designed. The intermolecular interactions, molecular and electronic structures, properties like conjugation effect and impact sensitivity, electrical conductivity and electrostatic sensitivity, recovery time, UV-Vis spectrum and IR spectrum were investigated theoretically. The results showed that N5H can be adsorbed inside the center of big C18 ring through the chemisorption. Intermolecular interactions in composites were mainly contributed by the dispersion interaction, but the electrostatic interaction also could not be neglected for 2 N5H@C18 and 2 N5H@ 2 C18 composites. The conjugation effect and ESP value in high positive region of N5H may be enhanced and decreased by C18, respectively, leading to better structural stability and lower impact sensitivity of composites than sole N5H. Due to the obviously decrease in energy GAP caused by C18, the electron transition ability and electrical conductivity of composites were greatly better than sole N5H, leading to lower electrostatic sensitivity and better safety performance markedly. Besides, the recovery time was very short, the difference in the UV-Vis and IR spectrum between sole N5H and composites was very obviously, showing the second function of C18 used as a new sensor for polynitrogen molecules like N5H.

Blood Coagulation Activities of Cotton-Alginate-Copper Composites.

Alginate-based materials have gained significant attention in the medical industry due to their biochemical properties. In this article, we aimed to synthesize Cotton-Alginate-Copper Composite Materials (COT-Alg(-)Cu(2+)). The main purpose of this study was to assess the biochemical properties of new composites in the area of blood plasma coagulation processes, including activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin time (TT). This study also involved in vitro antimicrobial activity evaluation of materials against representative colonies of Gram-positive and Gram-negative bacteria and antifungal susceptibility tests. The materials were prepared by immersing cotton fibers in an aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the fibers with Cu(II) ions to yield antimicrobial activity. The results showed that the obtained cotton-alginate-copper composites were promising materials to be used in biomedical applications, e.g., wound dressing.

Novel two-dimensional layered black phosphorus/nano-Si composites anode for Li-ion batteries

Silicon (Si) anodes have high theoretical capacity and two-dimensional (2D) layered black phosphorus (BP) has a special negative Poisson's ratio effect (NPR). Therefore, we combined the 2D layered BP and Si to form a black phosphorus/silicon (BP/Si) composites anode, and investigated its electrochemical and mechanical properties by first-principles calculations based on density functional theory (DFT). The computational results show that the composite anode has higher energy density and better structural stability. Such as lower migration energy barrier and higher Li storage capacity. And by calculating the stress–strain relationship of the composite, it is found that the BP/Si composites anode has better mechanical properties, which means that the composite anode can effectively suppress the volume expansion after Li-ions intercalation, thus making the structure more stable and extending the battery life cycle. This work improves the understanding of the properties of new composites and provides valuable results for the development of 2D layered anode materials and high-performance electrode materials.

Machine learning-enabled framework for the prediction of mechanical properties in new high entropy alloys

Prediction of properties of new compositions will accelerate the material design and development. The current study uses a machine learning framework to predict the microhardness of high entropy alloys. Several feature selection algorithms are used to identify the essential material descriptors. The stability selection algorithm gives optimum material descriptors for the current dataset for the microhardness prediction. Eight different machine learning algorithms are trained and tested for microhardness prediction. The accuracy of prediction improved by reducing the higher-dimensional data to lower dimensions using principal component analysis. The current study shows the testing R 2 score of more than 0.89 for XGBoost, Random forest, and Bagging regressor algorithms. Experimental data confirms the applicability of various trained algorithms for property prediction, and for the current study, ANN shows better performance for the new experimental data. • A new framework for the prediction of mechanical properties using machine learning (ML). • Several Feature section algorithms are tested and identified the optimum one for microhardness prediction in HEAs. • Several ML algorithms are trained and tested for microhardness prediction. • ANN gives better prediction in an experimental comparison.

Machine learning-enabled prediction of chemical durability of A2B2O7 pyrochlore and fluorite

Pyrochlore-structure type and its derivative in a general formula A2B2O7 (A = rare earth elements and actinides; B = Ti, Sn, Zr, Hf, Pb, Si, etc.) display excellent structural flexibility and rich crystal chemistry as promising nuclear waste form materials capable of immobilizing actinides and fission products. It is essential to understand these materials’ chemical durability and element release of radionuclides in order to evaluate their performance in near-field environment. However, it is a formidable grand technological challenge to experimentally perform durability testing across hundreds of thousands of possibilities resulting from their extreme compositional complexities due to cation substitutions at both A and B-sites. In this work, we demonstrate a machine learning approach to determine the key materials parameters and structural characteristics governing the leaching behaviors from a small set of selected compositions as model systems, enabling a science-based prediction of their chemical durability that can be extended to a wide range of chemical compositions. The combination of four key structural characteristics and materials parameters, including ionic radius size difference rA-B, ionic potential difference EB-A, electronegativity difference χB-A, and lattice parameter α, creates features an optimized prediction of the chemical durability. Two machine learning models, linear regression and Kernel ridge regression models, are trained on the randomly-split training dataset derived from the experimentally-determined elemental release rates, and subsequently tested on the testing dataset. The predicted leaching rates from both machine learning models show an excellent agreement with the experimental data, demonstrating the feasibility of rapidly evaluating the material properties of new compositions. These results highlight the immense potential of synergizing informatics through machine learning-based models and well-controlled experiments of selected model systems to accelerate materials design and discovery with optimized compositions and performance of promising materials for effective nuclear waste management.

The overview of mechanical properties of short natural fiber reinforced geopolymer composites

In the EU there is a pressing need for the change of the current economy into a so-called circular economy in recent years. The rational management of natural resources and the use of waste materials are becoming more and more important. It is also supported by the growing ecological awareness of society, including the consciousness of sustainable development. Nowadays, it is the construction industry that has the most significant impact on pollution. Therefore, numerous attempts are made to reduce energy consumption and the amount of waste generated by it. These are the main issues stimulating the research on new innovative materials such as geopolymer composites. They have a significantly lower carbon footprint than traditional construction materials. Moreover, the synthesis of geopolymers requires 2-3 times less energy than traditional Portland cement, not to mention the fact that 4-8 times less CO2 is generated. In addition, the above process has another environmental benefit i.e. the possibility of using anthropogenic raw materials (minerals) such as slags and fly ashes for the production. One of the limitations for the wide use of such materials is their relatively low brittle fracture behaviour. Nowadays, one of the most important research areas is the improvement of their mechanical properties. To improve the mechanical properties it is possible to reinforce the matrix by fibres addition, especially natural fibres that are renewable resources. The main objective of the article is to analyse the mechanical properties of new composites and assessment the possibility to replace traditional building materials within eco-friendly alternatives.

New magnetic aluminum matrix composites (Al-Zn-Si) reinforced with nano magnetic Fe3O4 for aeronautical applications

Aluminum metal matrix composites (AMMCs) are light-weight materials are widely used in structural applications due to their favorable properties such as lightweight, high specific strength and modulus, wear resistance and low coefficient of thermal expansion. Today, new developed magnetic aluminium based composites (Al-Zn-Si) became very attractive due to their improved magnetic, physical and mechanical properties. These composites, depending on final desired properties with different reinforcement types, are very suitable for electrical motors and other usage in aircraft engineering. These promising properties of AMMCs are attributed to the size and distribution of the reinforcement, as well as to the grain size of the matrix. Process that was used in this work is called ‘Sinter-Forging’ during which compacted aluminium specimens were forged just after sintering. A novel near-net shape, low-cost sinter-forging approach to processing particle-reinforced metal matrix composites allow manufacturing parts for high performance applications with short processing time and low energy consumption. The aim of this work is to briefly present the efficient ‘Sinter-Forging Process’ and to summarize properties of new composites developed for aeronautical applications.

Cytotoxicity and physical properties of new composites for pulp capping

Cytotoxicity and physical properties of new composites for pulp capping

Study of spinel-type ZnNixCo2⿿xO4 nano-particles, synthesised by thermal decomposition of ternary metal nitrate solutions

We report the structural, magnetic and electrical properties of new composition of spinel-type ZnNixCo2⿿xO4 (0.1⿤x⿤0.6) nano-particles. The X-ray diffraction and Fourier transform infrared spectroscopy studies reveal that the ZnNixCo2⿿xO4 nano-crystals show pure cubic spinal for all compositions wherein Co ions are systematically replaced by Ni ions. The electron microscopic studies reveal the nanoparticle sizes are of well-defined spherical shape and the magnetometry studies show superparamagnetic like behaviour with smaller values of coercive fields. The maximum dc conductivity at 30°C is found to be 0.03S/cm for ZnNi0.6Co1.4O4. Activation energies of dc conductivity obtained from Arrhenius plots are within the range of 0.12⿿0.35eV for extrinsic and 0.13⿿0.78eV for intrinsic regions and are affected by Ni concentration. Overall results suggest that these nano-particles are of high crystalline quality and electrical properties are dominated by holes as major charge carriers.

Polymer Composites Filled with Multiwall Carbon Nanotubes

The structural and physico-chemical characteristics of thermoplastic polymers filled with multiwall carbon nanotubes (CNTs) such as polyethylene (PE), polyamide 6 (PA 6) and layered fiberglass with PA 6 are investigated. The influence of their concentrations and homogeneity degree of nanotubes distribution is studied. The properties of new composites are compared with the well investigated polytetrafluoroethylene (PTFE)-CNTs and polypropylene (PP)-CNTs systems. It is shown that an addition of CNTs into thermoplastic polymeric materials leads to the significant changes in structural characteristics, growth of strength, electrical, thermal properties. It is coursed by the formation of CNTs continuous network in the original matrix, the crystallinity degree of the matrix depending on the concentration of CNTs. In turn, the crystallinity degree of the matrix is increased by homogeneity arising of the composite as a result of the strong interaction of the matrix with nanofiller. The changes of not only bulk but also the surface properties of the composites are observed, which explains the best biocompatibility of the nanocomposites observed in natural conditions experiments (in vivo).

Photoluminescence and thermoluminescence properties of Li₂O-Na₂O-B₂O₃ glass.

Influence of Nd(3+) concentration on the optical and thermoluminescence (TL) properties of melt-annealed synthesized 10 Na2O: 20 Li2O: (70-x) B2O3 : xNd2O3, where 0.1≤ x ≤0.7 (LNB) glasses are determined. The absence of sharp peaks in X-ray diffraction patterns confirms the amorphous nature of the prepared glasses. The photoluminescence spectra under 800 nm laser excitations at room temperature exhibit three prominent peaks centred at 538, 603 and 675 nm corresponding to the transitions of (4)G(7/2) → (4)I(9/2), [(4)G(7/2) → (4)I(11/2), (4)G(5/2) → (4)I(9/2)] and [(4)G(7/2) → (4)I(13/2), (4)G(5/2) → (4)I(11/2)], respectively. The TL glow curve exhibits a prominent peak (T(m)) at 180°C. The best performance of the prepared glass was found at 0.5 mol% of Nd2O3. We achieved a good linearity of TL response against dose between 0.5 to 4.0 Gy. The calculated value of the effective atomic number, Z(eff), is 7.55 which is nearly tissue equivalent (Z(eff) = 7.42). These promising features demonstrate the capability of the aforementioned glass to be used as a radiation dosimeter. The thermoluminescence and optical properties of new compositions of lithium sodium borate glasses doped with Nd(3+) ions were reported. Attractive features were obtained from the TL, PL and UV-Vis light analysis. Three upconversion luminescences permitting green, orange and red emissions were observed.

Структура і спектральні властивості нових композитів на основі метал-алканоатів з наночастинками золота

Структура і спектральні властивості нових композитів на основі метал-алканоатів з наночастинками золота

Characterization of severely deformed new composites fabricated by powder metallurgy including a stage of mechanical alloying

Mechanical properties of new composites having a binary matrix of Al–4Cu reinforced with TiO2 nano particles were investigated. The composites which consisted of 2wt% and 8wt% of TiO2 reinforcement particles, were fabricated using mechanical alloying and a powder metallurgy route. Morphology, phases and compounds formed during ball milling and densification of samples were studied. With increasing percentages of the reinforcement particles, mechanical properties of the composites were enhanced. Microstructural evolution and mechanical properties changes of the composites after application of twist extrusion (TE), as a severe plastic deformation (SPD) process, were also investigated. It was revealed that the more TE passes the higher hardness and yield strength obtained. In addition, increasing TE passes, led to occurrence of a more homogeneous distribution of the reinforcement particles within the structure, and development of an ultrafine-grained nano-structure. The maximum allowable number of TE passes was found to be four, above which the materials failed.

Influence of the fluxes properties on quality and the microstructure of lead-free solder joints executed by selective soldering

Purpose – The purpose of this paper is to investigate the influence of the properties of new compositions of fluxes for selective soldering on lead-free solder joints quality and microstructures as well as showing which flux properties are the most important. Design/methodology/approach – The three different types of fluxes were tested, which differed in composition, solids content, amount and type of activators added. The selective soldering process was done with the use of lead-free solder SAC 305. The test boards had two coatings SnCu (HASL) or Au/Ni. Basic chemical and physical properties of fluxes were examined according to the relevant standards. Different types of components from the bulky ones, demanding more heat, to the smaller ones were used during the assembly process. AOI and X-ray analyses as well as cross-sections and SEM analyses were utilized to deeply assess the quality and microstructure of the investigated solder joints. Findings – The results showed that information about density or static activity of flux is not enough for correct flux assessment. The dynamic activity of flux measured by wetting balance method is the best for this, especially in the case when there is short soldering time and heat transfer is hindered. The quality and the microstructure of lead-free solder joints are related not only with wetting properties of the flux used for soldering but also with other properties like solids content in a flux. Research limitations/implications – It is suggested that further studies are necessary for the confirmation of the practical application, especially of the reliability properties of the joints obtained with the use of the elaborated fluxes. Originality/value – The results showed that type of flux (ORL or ROL) as well as minor changes in their dynamic activity and solids content might have significant influence on quality of solder joints and their microstructure. It was noted that selective soldering is demanding technique and optimization of soldering process for different type of components and fluxes is important.

Optical properties of polyvinyl alcohol doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) composites

Polyvinyl alcohol (PVA) doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) thin films were prepared by the spin-coating technique on a quartz substrate. The optical parameters of PVA-doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) composites at the same chalcogen concentration (S0 = 0.1 mg ml−1) and PVA/(Se80Te20)96Ag4 composites at three different chalcogen concentrations viz. S1 = 0.3 mg ml−1, S2 = 0.6 mg ml−1 and S3 = 1 mg ml−1 have been studied. The semi-crystalline nature of the as-deposited thin filmsisdetermined by X-ray diffraction. The transmission and reflection spectra of PVA-doped Se–Te–Ag thin films were obtained in a 350–650 nm spectral region. The optical-band gap has been calculated from the transmission and reflection data. The refractive index has been calculated by the measured reflection data. It has been found that the optical-band gap increases, but the refractive index, extinction coefficient, and the real and imaginary parts of the dielectric constant decrease, with increase in Agcontent in PVA-doped (Se80Te20)100–xAgx (0 ≤ x ≤ 4) thin films. Such type of behavior is explained on the basis of decrease in density of the defect states. However, the optical-band gap has been found to be decreased and all other optical parameters show increase in their values with increase in concentration of (Se80Te20)96Ag4 glass in PVA-doped composites. The results have been explained on the basis of cluster-size formation at the time of dissolution. This study shows that the optical properties of new composites are affected by the change in silver and chalcogen concentration.

Polymer Based Composite and Hybrid Materials for Wind Power Generation

In recent years considerable attention has been dedicated to renewal power sources, such as wind power. This work was carried out in order to develop a small wind turbine of 1-10kW power generation capability. This wind turbine is designed to be energetically more efficient by 30-50% and having a lesser specific cost (by 25-30%). This work focused on the development of composite materials for application on the blades in the wind generator. In this paper we present the results of the research work done on the development of flexible technology for the fabrication matrix-epoxy resin based hybrid composites, reinforced with carbon, basalt and glass fibers. These new composite and hybrid materials were fabricated using epoxy matrixes. These matrices were reinforced with basalt and carbon fibers of different content and strengthened by mullite-like crystals. The basalt fibers for composite reinforcing were prepared from raw materials, with chemical composition: SiO2-15.3%; CaO-10.8%; Na2O-4.2%; MgO-8.8%; Fe2O3-12.1%; MnO-0.7%; TiO2-0.7%. The properties of new composites developed depend on the content and architecture of reinforcing components and are: tensile strength-(0.012-1.590)GPa; compression strength-(0.078-0.656)GPa; modulus of elasticity-(8.4-162.9)GPa; Poisson ratio-(0.015-0.559). The variation of strength and elastic characteristics under tension and compression of the new composites are presented.

Thermal properties of new composites based on nanoclay, polyethylene and polypropylene

Abstract The results presented by a number of researchers indicate that the introduction of montmorillonite into polymer matrix results in an increase of thermal stability of polymer nanocomposites. The main purpose of this study was to evaluate the effect of the organoclay on the thermal degradation of polyolefins (polyethylene and polypropylene). Polyolefin-clay nanocomposites were prepared by melt compounding of polyolefins and montmorillonite clay organically modified with 4,4′-methylenebisaniline (MBA) (from 1.5 to 5 wt%). Changes in the surface of montmorillonite and the dispersion of organoclay in the polymer matrix were evaluated using X-ray diffraction (XRD) and elemental analysis. The thermal stability of the clay and nanocomposites were analysed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). The XRD results show that almost complete exfoliation of the silicate layers took place and nanocomposite structure was obtained for all new materials. The thermal stabilit...

친수성, 통기성 및 항균성이 향상된 고분자-세라믹 복합소재의 제조 및 물성

일반적으로 고분자 재질은 표면이 수분을 배척하는 소수성이며 또한 통기성이 좋지 못하다. 이러한 물성을 개질하기 위하여 고분자 플라스틱에 기능성 충전제로 친수성인 세라믹 입자와 항균입자를 혼합하여 친수성, 통기성 및 항균성이 향상 된 복합재료를 제조하였으며 표면 접촉각 측정, 공기투과시간 측정, 항균효과 관찰을 통해 물성을 확인하였다. 이러한 복합 재료는 건강관련 제품에 널리 이용될 수 있다. Generally, polymer materials are not air-permeable and hydrophilic. In addition, they do not possess anti-fungal property. Hydrophilicity, air-permeability, and anti-fungal properties of new composites consisting of polymer, ceramic nanoparticles, and silver ion were investigated by contact angle measurements, air permeation time, and cell culture. The hydrophilic, air-permeable, and anti-fungal composites can be used in health care industry.

Compósitos de HDPE com resíduos de fibras têxteis. Parte I: caracterização mecânica

Neste trabalho são apresentados e discutidos os resultados das propriedades mecânicas de novos materiais compósitos preparados com resíduos de fibras têxteis poliméricas e de polímeros commodities. As fibras naturais oferecem vantagens sobre as sintéticas, em termos de propriedades mecânicas e térmicas. Os compósitos foram preparados a partir da mistura de polietileno de alta densidade (HDPE) e resíduos de fibras têxteis (50% algodão /50% acrílico) em teores crescentes de 10 a 40%, em um misturador de alta velocidade, utilizando Surlyn 2601, Polybond 3009 e Polybond 1009 como agentes compatibilizantes. Corpos-de-prova para ensaios de tração, flexão e impacto foram produzidos a partir de chapas obtidas em uma prensa hidráulica. Os compósitos que utilizaram agentes compatibilizantes apresentaram os melhores resultados de resistência à tração e à flexão, principalmente com 5% do agente Polybond 3009 e 20 a 40% de resíduos de fibras têxteis.

Physical and mechanical properties of an experimental dental composite based on a new monomer

Objective. The purpose of this study was to investigate the physical and mechanical properties of a dental composite based on BTDMA, a new dimethacrylate monomer based on BTDA (3,3′,4,4′-benzophenone tetracarboxylic dianhydride), and to compare these with the properties of a composite based on commonly used Bis-GMA monomer. Methods. Experimental composites were prepared by mixing the silane-treated filler with the monomers. The prepared pastes were inserted into the test molds and heat-cured. Light-cured composites were also prepared using camphorquinone and amine as photoinitiator system. Degree of conversion of the light-cured and heat-cured composites was measured using FTIR spectroscopy. The flexural strength, flexural modulus, diametral tensile strength (DTS), water sorption, water contact angle, microhardness and thermal expansion coefficient of the prepared composites were measured and compared. Water uptake of the monomers was also measured. Results. The results showed that the mechanical properties of the new composite are comparable with the properties of the Bis-GMA-based composite but its water sorption is higher. BTDMA as a monomer containing aromatic rings and carboxylic acid groups in its structure gives a composite with good mechanical properties. There is a close relation between the contact angle, water sorption of the cured composite and water uptake of their monomers. Significance. Finding new monomers as alternatives for Bis-GMA have been a challenge in the field of dental materials and any investigation into the properties of new composites would be beneficial in the development of dental materials.