Properties Of New Composite Materials Research Articles

Influence of silver nanoparticles in the ion-exchange layer of photo-thermo-refractive porous glass on the spectral-luminescent properties of CsPbBr3 perovskite nanocrystals

The spectral-luminescent properties of new composite materials based on porous matrices of photo-thermo-refractive glasses with a silver ion-exchange layer and CsPbBr3 inorganic perovskite nanocrystals have been studied. Perovskite nanocrystals were introduced into a porous matrix by the method of pumping solutions through a sample under piston pressure. Two mechanisms of interaction between silver nanoparticles and perovskite nanocrystals have been revealed, such as enhancement of the local field and luminescence quenching due to the high absorption of nanoparticles. The quantum yield of the studied samples under different irradiation associated with an increase in the concentration of silver nanoparticles was 34% without irradiation, 51% with 100 j irradiation dose, and 25% with 1000 j irradiation dose. In this case, an increase in the integrated luminescence intensity was observed in glasses irradiated with 100 J by a factor of 2.97 and irradiated with 1000 J by a factor of 1.76 compared to the unirradiated sample. The average luminescence lifetime decreases from 2.19 to 1.68 ns with an increase in the concentration of nanoparticles.

Aloe vera silver nanoparticles addition in chitosan films: improvement of physicochemical properties for eco-friendly food packaging material

In recent times, the searches for alternative materials to plastic is a popular topic, due to the danger that synthetic materials cause to the environment and humans. Among the promising natural polymers, chitosan (CS) is certainly one of the most suitable since it it is edible, non-toxic and derives from crustacean waste.- However, it is necessary to improve its physical properties to be widely applied in food packaging, whose market is dominated by synthetic plastic. In this work we have synthesized silver nanoparticles (AgNPs) using hot-plate and microwaves-based techniques, using Aloe Vera leaves extracts. The synthetic process follows the principles of green chemistry, since no toxic substance is used to obtain nanomaterials. These NPs, having dimensions <20 nm, were characterized by TEM, zeta potential, UV–vis, FTIR, and then added to CS having low and medium molecular weight to develop thin films after its polymerization. These films were evaluated in terms of swelling ratio, optical properties, thermal stability, wettability, roughness, and friction coefficient, understanding that the physical properties of the films improved after the intercalation of the AgNPs, albeit differences were observed using the two NPs type. Subsequently, the release of silver ions from films using different pH as well as in vitro toxicity tests were carried out to evaluate their applicability. Largely, the excellent properties of new composite materials make them promising materials for packaging of different kinds of foods.

Properties of New Composite Materials Based on Hydroxyapatite Ceramic and Cross-Linked Gelatin for Biomedical Applications.

The main aim of the research was to develop a new biocompatible and injectable composite with the potential for application as a bone-to-implant bonding material or as a bone substitute. A composite based on hydroxyapatite, gelatin, and two various types of commercially available transglutaminase (TgBDF/TgSNF), as a cross-linking agent, was proposed. To evaluate the impacts of composite content and processing parameters on various properties of the material, the following research was performed: the morphology was examined by SEM microscopy, the chemical structure by FTIR spectroscopy, the degradation behavior was examined in simulated body fluid, the injectability test was performed using an automatic syringe pump, the mechanical properties using a nanoindentation technique, the surface wettability was examined by an optical tensiometer, and the cell viability was assayed by MTT and LDH. In all cases, a composite paste was successfully obtained. Injectability varied between 8 and 15 min. The type of transglutaminase did not significantly affect the surface topography or chemical composition. All samples demonstrated proper nanomechanical properties with Young’s modulus and the hardness close to the values of natural bone. BDF demonstrated better hydrophilic properties and structural stability over 7 days in comparison with SNF. In all cases, the transglutaminase did not lead to cell necrosis, but cellular proliferation was significantly inhibited, especially for the BDF agent.

Strength properties of chemically modified solid woods

A new composite material based on solid wood and polymer composition ‘silor’ under surface modification was obtained. A method of experimental studies of the compressed polymer composition ‘silor’ of solid hardwood by compression along the fibers has been developed. Experimental studies of such composite materials under a rigid test regime have been carried out. Complete diagrams of deformation such materials from the beginning of loading to destruction are constructed (ascending and descending branches). The main mechanical properties of new composite materials based on solid wood are determined. The method of determining the initial modulus of elasticity and modulus of deformation on the basis of graphs "E-η". It is established that the modification of the polymer composition ‘silor’ significantly improves the strength and deformability of hardwood (birch, alder, ash). With surface modification of solid hardwood, the maximum stresses increase by 12–22% in comparison with solid 60 year old wood with a moisture content of 12%. Deformability decreases within 17–25%. The initial modulus of elasticity of the studied samples is higher by 21–38%.

Electric properties of new composite materials based on RGO, nanosized ZnO and Cu nanoparticles

Graphene nanostructures combine properties that make them an attractive material for various technical applications. The objective of this study is to obtain a series composites based on Reduced graphene oxide (RGO), nano-sized ZnO and Cu nanoparticles. RGO is synthesized by a modified Hammer’s method and chemical reduction after sonication. ZnO nanoparticles are obtained by the Sol-Gel method. The composites’ phases and structures are characterized by XRD, SEM, TEM, and EDX analysis. It is shown that ZnO is monophasic with a particle size of 48 nm. A series of composite materials based on RGO, ZnO and Cu nanoparticles is obtained by ultrasonic treatment. Electrical and dielectric properties are measured by Impedance analyser and RLC bridge. For comparison, the conductivity for 100% RGO is 309.513 S/m and for 100 % Cu nanosized is 0.0056 S/m. Therefore, it should be initially concluded that increasing the RGO in the mixture will increase the conductivity, and increasing nanosized Cu will decrease it. The presence of cluster regions in the composites with different conductivity is found: 1) nano grains of conductive copper which are partially or completely surrounded by 2) low-conductivity shells of copper oxide and a minimal number of RGO sheets. The present work shows promising results for future research for the creation of new composite materials with controlled shape and size of copper oxide - RGO clusters. Dielectric measurements for RGO/ZnO composites are made in range from 5 mass% to 100 mass% content of RGO, the composites show variable conductivity. For lower concentration of RGO, selected samples are dielectrics.

The Investigation about Gel Properties of New Composite Materials with Meta-kaolin

As one of the most promising building materials, the composite materials of metakaolin have a wide range of applications and excellent performance. Owing to the lack of research on the early-high-strength characteristics of MK, this article tries to make some meaningful attempts. In terms of the characteristics of hydration calcium silicate with gelation performance, this paper studied the preparation of metakaolin, the type of hydrothermal synthesis products, and the corresponding hydration dehydration phase and its rehydration characteristics. Through the exploration and research of the metakaolin hydrothermal synthetic process, it has prepared a new type of early-high-strength concrete regulator and opened up a new way for the effective application of kaolin. The preparation process, structure, and properties of MK-based concrete performance regulators were systematically investigated by XRD and SEM analysis. The macroscopic properties of the MK-based concrete performance regulator were discussed through coagulation time, hydration heat, and compressive strength performance.

Experimental and Theoretical Investigation of the Physical Properties of new Composite Materials

The Experimental and theoretical investigation of the physical properties of new composite materials were studied by conjugating two materials. One of them is the strong virgin polymer (Commercial HDPE powder) high density polyethylene and the other is the scrap of tire tubes polyisobutylene. By application thermal insulation materials and introducing them to the building market during the last decades can give the same thermal resistance a thinner construction using. The preparation of specimens from a composite of high-density polyethylene and the scrap of tire tubes [3x5] mm with different weight ratios from 0 % to 55% were adapted. Both of mechanical and thermal conductivity to measure and estimate the modulus of elasticity, shore hardness, impact strength and thermal conductivity for the various prepared polymeric specimens. The optimum thermal insulation was obtained with 40% weight of the scrap of tire tubes and 60% HDPE, the optimum thermal conductivity showed a value of 0.078 W/m. K which is less than the other composite samples. In addition, the theoretical study by the neuro fuzzy models are developed to predict the physical properties (elastic modulus, thermal conductivity, shore hardness and impact strength) of the composite materials using fuzzy logic toolbox in the Matlab version 7.10. Different membership functions and adaptive neuro fuzzy inference systems (ANFIS) are used in these models. The selected input variables used in the proposed models include HDPE and the scrap of tire tubes. During the test of neuro fuzzy model good agreements and observed.

Magnetic Freedericksz transition in a ferronematic liquid crystal doped with spindle magnetic particles

In this work we studied new composite ferronematic system based on the liquid crystal 4-n-hexyl-4′-cyanobiphenyl (6CB) doped with hematite spindle-like magnetic particles. We experimentally showed that magnetic moments of the elongated spindle particles are oriented perpendicularly to their main axes. It is a fundamental difference of our systems from ferronematics, which were synthesized before by many authors. For a research of magnetic and orientational properties of new composite materials, the ferronematic samples were prepared with different length of the particles and with the volume concentrations of solid impurity ϕ1=10−3, ϕ2=10−4 and ϕ3=10−5. The structural Freedericksz transition in ferronematic samples were observed by capacitance measurements in a capacitor made of ITO-coated glass electrodes. Experimental results showed a decrease of the critical field in the ferronematic samples in comparison with the pure 6CB, and an increase of the threshold shift with a growth of both the volume fraction of solid impurity and the length of particles. The response of capacitance to low external magnetic field - far below the magnetic Freedericksz transition threshold of prepared samples was also observed experimentally. For a theoretical description of this magnetically induced behavior of composite systems, the continual model of ferronematics with bistable coupling between colloidal particles and the nematic matrix was used. This theory permits the equilibrium tilted orientation of the particles with respect to the nematic director. We showed that it creates a so-called “pretilt angle effect” which explains the behavior of the ferronematic systems in a low field regime as well as decrease of the threshold field and the dependence of this field on the volume fraction of solid impurity and the length of the particles.

The plasticity of composite material based on winter rapeseed as a function of selected factors

The development of new composite materials using alternative sources of raw materials is of great importance nowadays due to the lack of raw wood material and the economic development of the market. The main objective of this article is to determine selected mechanical properties of new composite materials based on cellulose and lignin. We focused on the mechanical properties measured in the plastic range during the bending of composite materials. We monitored the effect of factors such as the method of modification (raw, boiled in water and soaked in a lye bath), and the effect of the adhesive used to bind components (polyester powder and urea formaldehyde). The monitored characteristics were the bending strength “MOR”, plastic potential “Pp” and the moduli of plasticity CHM, EE, EMV and EP. The results constitute an important basis that is inevitably necessary in the production of new types of materials with specific properties for their intended use. The output of this article forms a part of a project whose goal is to create a mathematical model that will enable us to anticipate changes in the monitored characteristics, with regard to the required modifications.

Investigation of Mechanical Properties of Polyimide- Polyethyl-eneterephthalate System

The study of the physico-mechanical properties of new composite materials based on polyimide (PI) and polyethyleneterephthalate (PET) was carried out. Dependences of σ from ɛ for different concentrations of the second component and irradiation doses were measured. The experimental data are described satisfactorily by the exponential cascade- probabilistic model.

Lithium intercalation into SiCN/disordered carbon composite. Part 1: influence of initial carbon porosity on cycling performance/capacity

Within this work, we investigate the structural and electrochemical properties of new composite materials based on disordered carbons embedded into a polymer-derived silicon carbonitride matrix. In particular, we focus on the relationship between the initial characteristic of disordered carbon, that is its microstructure and porosity with the lithium-ions storage properties of the composite. Although there is almost no difference between composites found by means of Raman spectroscopy and X-ray powder diffraction, it is demonstrated that the pore volume of the carbon is of significant importance, i.e., volume of the preceramic polymer must be matched with pore volume of the carbon in order to ensure the optimal electrochemical performance. Thus, it is possible to synthesize a composite containing only 50 % of external carbon, which recovers the capacity comparable to that of pure carbon.

Production and Properties of New Composite Materials Based on Acetylated Wood and Aluminium Compounds

Production and Properties of New Composite Materials Based on Acetylated Wood and Aluminium Compounds

EMC Impact of Advanced Carbon Fiber/Carbon Nanotube Reinforced Composites for Next-Generation Aerospace Applications

This paper presents a comparative analysis of the electromagnetic properties of new composite materials that are of interest to future aircraft/aerospace structures. The fabrication process of single-phase and new multiphase micro/nanocomposites is described. Carbon black, carbon fibers, and multiwall carbon nanotubes are randomly mixed into an epoxy resin matrix at various weight fractions and compositions. The experimental characterization in the frequency range 8-18 GHz shows that the dispersion characteristics of short-carbon-fiber-reinforced composites can be properly controlled by the addition of nanopowders and nanotubes into the mixture. Numerical simulations demonstrate the feasibility of the fabricated materials for the design of new electromagnetic micro/nanostructured shields and radar-absorbing laminates. Thin dielectric Salisbury screens are especially designed to exhibit minimum reflection coefficient at 15 GHz. It shows that the total thickness of the screen can be reduced below 2 mm by using a lossy sheet made of three-phase composites.

Measurement of the third order nonlinear properties of conjugated polymers embedded in porous silicon and silica

Third order nonlinear properties of new composite materials obtained by embedding conjugate polymers in porous silicon and silica matrices are measured in near infrared. A new technique so-called “I-scan” was used as alternative to the classical z-scan, since better adapted to the particular form of samples. The picoseconds measurements show a significant increase of the nonlinear refractive index not only with respect to the standard optical materials but also to the bulk conjugated polymers. Embedding of PTS, PT12, and PPV in nanopores enhances considerably their already very large nonlinear refraction index and lower their overall absorption due to a negative nonlinear absorption. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

New low thermal expansion ceramics: Sintering and thermal behavior of Ln1/3Zr2(PO4)3-based composites

Materials with the general formula MxZr2(PO4)3 are known to possess low coefficients of thermal expansion (CTE). The present work investigates the thermal properties of new composite materials issued from the decomposition at high temperature of Ln1/3Zr2(PO4)3 (Ln=La, Gd). The decomposition process was studied and showed that the resulting powder was a LnPO4, Zr2P2O9 and ZrO2 mixture. Composite materials made of that mixture were sintered and characterized. The effect of sintering aids such as ZnO was considered. Final densities of the composites were about 90% of theoretical density and these materials presented low CTE in the 10−6°C−1 range.

Recent Applications of Coherent Optics in Aerospace Research

The Royal Aircraft Establishment has an extensive programme of work on the application of coherent optical methods to problems arising in aerospace research. In addition to the use of both real-time and double-pulse holographic interferometry in the non-destructive testing of experimental aircraft components, techniques have been developed for the investigation of the mechanical properties of new composite materials and for studies of the behaviour of these and of more conventional materials under stress. Results obtained using a moire-type method for the determination of in-plane strain are presented; and an interferometric system is described which, incorporates an image-converter camera for study ing the surface deformation of a metal bar during the passage of a shockwave front. A simple interferometric method is being applied to the measurement of vibration amplitudes in the subnanometer range; some typical results showing the behaviour of a piezo-electric transducer at frequencies up to 1 megahertz are given. Current work in connection with aerial photography is described, including the incorporation of holographic optical elements into a very large Fizeau interferoscope being constructed for the examination of aircraft camera window. Laser anemometry techniques for supersonic wind tunnel applications using an argon laser and a photon-correlator have been developed. Results obtained in laminar and turbulent air flows at transonic and higher Mach numbers are discussed.