Preparation Of Composite Materials Research Articles

Optical composites based on organic polymers and semiconductor pigments

The aim of the work was the development of optical organic-inorganic composite materials with high absorption of light the visible part of the spectrum and high reflection in the near infrared region of the spectrum. Such materials are used in industry and construction as coatings. To create these optical composites, epoxy and epoxy-polyurethane polymer matrices containing inorganic semiconducting particles (CuS, PbS, Fe3O4) were used. Highly dispersive powders of inorganic pigments were used for the preparation of homogeneous composite materials. The wet precipitation method with the application of organic stabilizing additions was applied for the preparation of dispersive CuS and PbS powders. Optical microscopy and X-ray diffraction analysis helped to study the crystal structure and morphology of the obtained semiconductor pigments. PMT-3 device was applied for microhardness measurements of the prepared composite materials. Based on the data of X-ray diffraction analysis, the average crystallite size was calculated using the Scherrer formula. It was found that freshly precipitated CuS and PbS powders consist of nanocrystals with a size of 11–20 nm. Optical microscopy data indicate the formation of aggregates of semiconductor nanocrystals in powders. Experiments have shown that all synthesized composites have low light reflection coefficient (less than 0.06) in the visible part of the spectrum and an increased light reflection coefficient in the near infrared region of the spectrum (0.13–0.15 and more). The results of the study showed that the use of epoxy-polyurethane polymer matrices provides greater microhardness of composite materials, compared to the composites based on epoxy polymers. The highest microhardness values were observed in composite materials based on epoxy-polyurethane polymers containing highly dispersed Fe3O4 particles. Obtained organic-inorganic composites could be used as materials for light-absorbing coatings in different industrial applications.

Preparation and Application of Class A1 Flame Retardant Composite Material with Waterproof Properties

ABSTRACT The Class A1 flame retardant eco-material with excellent comprehensive properties is strongly needed to replace the low-level flame retardant products for potential applications in the building industry. In this work, modified titanium sol with the re-dispersible latex powder (VAE) is compounded to prepare non-combustible flame retardant composites. The optimal content of polylactic acid (PLA) is determined as 10 wt%. The results reveal that the addition of modified titanium sol has simultaneous improvements in flame resistance, water resistance, and mechanical properties of the composite material. The composites with 8 wt% modified titanium sol show low gross heat of combustion (0.646 MJ·kg−1) and low water absorption (4.26%), satisfying the enterprise standards. Besides, the flexural strength of the composites exhibited the maximum at 18.8 MPa. Structure observation discloses that the modified titanium sol promotes the formation of a three-dimensional network structure in the material and further forms a dense protective layer during combustion to inhibit burning. Overall results suggest that the composites with modified titanium sol as the Class A1 flame retardant composite will shed light on their promising applications in the construction industry.

One−Step Synthesis of Popcorn−Carbon/Co3O4 Composites as High−Performance Supercapacitor Electrodes

In this study, a novel assisted liquid−phase plasma electrolysis was developed to realize one−step synthesis of popcorn biomass−derived porous carbon/cobalt tetroxide (popcorn−carbon/Co3O4) composites, effectively improving the structural stability and conductivity of Co3O4. The phase structure, morphologies, chemical composition, and weight ratio of the as−prepared popcorn−carbon/Co3O4 composites were systematically analyzed. The results of X−ray diffraction (XRD), Raman spectrometer, Fourier infrared spectrometer (FTIR), X−ray photoelectron spectrometer (XPS), and thermogravimetry analyzer (TG) proved the synthesis of the popcorn−carbon/Co3O4 composites. Co3O4 nanoparticles were distributed relatively uniformly on the popcorn−carbon surface. The electrochemical properties of the popcorn−carbon/Co3O4 composite electrode materials were analyzed for exploring the influence of different Co/C ratios on the electrochemical properties of composites. The results showed that the popcorn−carbon/Co3O4 composite electrode materials prepared under 200:1 mass ratio of Co(NO3)2·6H2O and popcorn−carbon possessed a specific capacitance and specific capacity of almost 1264 F/g (594 C/g) at a current density of 1 A/g, exhibiting a better electrochemical property. The efficient, fast, and novel assisted liquid−phase plasma electrolysis provides a new method for the preparation of composite electrode materials on the supercapacitors.

Self-Healing Materials for Electronics Applications.

Self-healing materials have been attracting the attention of the scientists over the past few decades because of their effectiveness in detecting damage and their autonomic healing response. Self-healing materials are an evolving and intriguing field of study that could lead to a substantial increase in the lifespan of materials, improve the reliability of materials, increase product safety, and lower product replacement costs. Within the past few years, various autonomic and non-autonomic self-healing systems have been developed using various approaches for a variety of applications. The inclusion of appropriate functionalities into these materials by various chemistries has enhanced their repair mechanisms activated by crack formation. This review article summarizes various self-healing techniques that are currently being explored and the associated chemistries that are involved in the preparation of self-healing composite materials. This paper further surveys the electronic applications of self-healing materials in the fields of energy harvesting devices, energy storage devices, and sensors. We expect this article to provide the reader with a far deeper understanding of self-healing materials and their healing mechanisms in various electronics applications.

Comparison of the Adsorption Ability of MgAl-HC, CaAl-HC, and ZaAl-HC Composite Materials Based on Duku Peel Hydrochar in Adsorption of Direct Green Anionic Dyes

Preparation of composite material from layered double hydroxide (LDH) with hydrochar (HC) from duku peel produces CaAl-HC, MgAl-HC, and ZnAl-HC have shown the success of the preparation process as evidenced by characterizations such as XRD and FT-IR. The XRD characterization data evidenced the typical diffraction of the hydrochar around 2θ = 20° in the composite material. FTIR analysis is a characterization that supports the success of composite materials, which showed the presence of typical vibrations of HC at 3245, 2931, and 1635 cm–1 contained in the composite spectrum. The application of MgAl-HC, CaAl-HC, and ZnAl-HC composites as adsorbents showed Qmax (adsorption ability) values of 94.340 mg/g, 128.205 mg/g, and 89.286 mg/g. Overall the adsorption process is endothermic with a positive enthalpy value, and a negative Gibbs free energy value indicates a spontaneous adsorption process. The isotherm model of MgAl-HC, CaAl-HC, and ZnAl-HC show that the Langmuir isotherm model is more dominant, as indicated by the R2 value closer to 1 which indicates that the adsorption process takes place in a monolayer.

Preparation of High-Performance Thermal Insulation Composite Material from Geopolymer, Foam, Hollow Glass Microspheres and Aerogel

Preparation of High-Performance Thermal Insulation Composite Material from Geopolymer, Foam, Hollow Glass Microspheres and Aerogel

Preparation of Phase-Change Composite Aerogel Materials and its Application in Solar Saline-Alkali Water Desalination

Preparation of Phase-Change Composite Aerogel Materials and its Application in Solar Saline-Alkali Water Desalination

Preparation and property analysis of solid carbonate-oxide composite materials for an electrolyte used in low-temperature solid oxide fuel cell

The oxide-carbonate composite electrolyte material with high ionic conductivity at low temperature has been thought that it can be used to develop LT-SOFC. However, the carbonate composite electrolyte is not easy to make it dense, especially mixing and packing oxide and carbonate to fabricate the composite electrolyte simply. In this article, rare-earth-doped CeO2 (RDC) (R = La, Sm, Gd, and Gd + Y) series samples were prepared by wet ball-milling, then sintered into fully dense and porous oxide bulk at 1500–1600 °C and 1000 °C. Melted carbonate LNCO, composed of Li2CO3 and Na2CO3 at a molar ratio of 1:1, was combined with porous oxide bulk materials using a bath method at 500 °C for 10 h to prepare a dense carbonate-oxide composite electrolyte. The dense oxide-carbonate composite electrolyte always obtains by this fabrication process. Boiling water was used to remove carbonate from these composites. Lattice parameters were obtained through Rietveld refinement, and a calculation procedure for quantifying the composite density was proposed. The quantified composite density results were verified through scanning electron microscopy microstructure observations. The Ce valence in the RDC oxides and RDC-carbonate composite was analyzed by X-ray absorption near edge structure spectroscopy to observe the effects of heat treatment temperature and carbonate on the Ce4+/Ce3+ mixed-valence state in doped CeO2.

Preparation and Characteristic of Wood-Based Inorganic Composite Phase Change Material with Effective Anisotropic Thermal Conductivity for Thermal Energy Storage

Preparation and Characteristic of Wood-Based Inorganic Composite Phase Change Material with Effective Anisotropic Thermal Conductivity for Thermal Energy Storage

Performance Evaluation of Mechanical Properties of Untreated Woven Natural and Synthetic Fibers Hybrid Epoxy Composite

Technocrats and researchers are attracted to the Polymer Matrix Composite (PMC) material due to its predominant mechanical properties. It has been observed from the literature survey that, use of any of the natural fibers alone from the available category like, Bast fibers e.g. jute, kenaf etc., Leaf fibers e.g. Sisal, Banana etc, Grass fibers e.g. Bamboo, Bagasse, Corn etc., Seed fibers e.g. cotton, Kapok etc., fruits fibers e.g. coir, palm etc. etc. as reinforced elements with matrix for composite not proven enough in strength for the proposed application due to its inbuilt characteristics. That limitation motivated me to do work on hybrid composites. Research is needed to find the better combination of the blend from the decided wt % configuration of fibers. In this paper, by taking the blend of natural fibers (Jute and kenaf) with a synthetic fiber (Glass fibers) with epoxy resin as matrix has been consider for the composite material preparation and its mechanical properties has been reveal as per American Society for Testing and Materials (ASTM) standard. The aim of the current work is to find a better wt % configuration out of the decided. Seven laminates of different configurations have been prepared by taking bidirectional woven fabric with the help of compression molding method. The tensile strength of the hybrid specimen shows maximum ultimate tensile strength 102.10 Mpa and Young’s Modulus 6706.90 MPa at maximum force of 7.70 kN.The flexural strength of the hybrid specimen composite shows maximum flexural strength 225.30 MPa. The impact strength of the hybrid material is 11.43 J/M.The hybrid composite material shows the more than 100,000 cycles. This is the highest among the seven examined configurations.

Novel Alkali-Activated Materials with Photocatalytic and Bactericidal Properties Based on Ceramic Tile Waste

Ceramics tile wastes (CWs) were mechanically conditioned for the preparation of alkali-activated hybrid-cements from CW (90 wt.%) and Portland cement (10 wt.%) mixtures using sodium silicate (SS) + NaOH as alkaline activators. Molar ratios of SiO2/Al2O3 (6.3 to 7.7) and Na2O/SiO2 (0.07 to 0.16) were used. The cements were prepared at room temperature (25 °C) and characterized by mechanical and physical properties and microstructure. The optimized cement was used for the preparation of novel photoactivated composite materials by incorporating 5 and 10 wt.% TiO2 (Ti) and ZnO (Z) nanoparticles, and its self-cleaning and bactericidal properties were evaluated by means of the degradation of rhodamine-B (Rh-B) and the growth inhibition of Klebsiella pneumoniae and Pseudomonas aeruginosa bacteria. The results of this study showed that the 100SS-5Z and 50SS:50G-10Ti cements have an effective photocatalytic activity for Rh-B degradation of 98.4% and 76.4%, respectively, after 24 h. Additionally, the 100SS-5Z and 50SS:50G-10Ti cement pastes and their respective mortars were effective in inhibiting the growth of Pseudomonas Aeruginosa and Klebsiella pneumoniae bacterial strains, evidenced by the formation of bacterial inhibition halos around the sample discs. Finally, these results are novel, and open the possibility of using constructions and demolition tile waste in high proportions for the elaboration of new rendering mortar with innovative properties.

Research on preparation and characterization of Ti-Ti5Si3 gradient composite porous material via in-situ reactive process

Gradient composite porous material can reach a high filtering accuracy with larger filtration flux, and the filter elements applied in separation equipment can enhance the filtration efficiency and reduce the energy consumption. Ti-Ti5Si3 gradient composite porous material was successfully prepared by in-situ reaction process with the raw materials of Ti powder and high purity quartz tablets. Microstructures and filtration properties prepared under different synthesized conditions have been studied, including the parameters of pressure sintering (additional loads and temperatures) and powder particle sizes. The synthesized granules on the membrane are well distributed with the size of ∼1.0 µm, and the thickness of the membrane is 3.0∼6.3 µm. The relative air permeability coefficient of porous membrane reduces raptly compared to the sample matrix due to the decrease of pore size. The all synthesized membranes show the presence of Ti and Ti5Si3 phases. There are two distinct layers observed in the membrane layers prepared by fine powder due to in-situ over-reaction.

OBTAINING AND PROPERTIES OF NANOSCALE SOLID-STATE HEAT STORAGE WITH CARNAUBA WAX

Latent thermal energy storage using phase change materials has attracted interest in the use of solar and other types of energy due to their ability to provide high density lateral energy storage. Materials with a latent heat of storage have become attractive for their use in many branches of human activity. However, the materials use is often limited by problems of low thermal conductivity, the transition from a solid to a molten state causes difficulties in storing materials in a container, and special heat exchangers are needed to increase the energy cost. The solution to the above problems may be to create solid-state, form-stable heat storage elements. In this work, a number of shape-stable materials with a phase transition were obtained from melts by mixing halloysite nanotubes with carnauba wax in order to improve the heat accumulation characteristics. Halloysite nanotubes were mixed at elevated temperatures with carnauba melted wax and rapidly cooled to prevent the nanotubes sedimentation. As a result, a series of solid wax/nanotube samples were prepared with weight ratios of 70/30, 60/40 and 50/50. Pure wax showed a accumulation heat of the solid-to-liquid phase transition of 189.09 J/g. Carnauba wax has a latent heat greater by about 25 % compared to paraffin. Composite materials had significantly lower latent heat, respectively, 99.39 J/g for 70/30, 90.25 J/g for 60/40, and 81.26 J/g for 50/50 samples. Elemental mapping of the nanomaterial revealed a nanotubes uniform distribution in the wax. According to the data of X-ray analysis, as a result of the composite materials preparation, the components did not form new crystalline phases, but they were physical mixtures. When heated, the components did not chemically interact with each other, which is useful for the accumulation of thermal energy by materials. Analysis of the IR spectra of the samples confirmed the change in the absorption bands of functional hydroxyl groups at 3696 sm–1 (Al–O–H) and 3621 sm–1 (Si–O–H). In primary nanotubes, the intensities ratio of silanol to aluminol groups is greater than unity, while in the composite it is already less than this value. This manifestation can be explained by the fact that, during the wax melting, the interaction of wax molecules on the outer surface of the nanotubes occurs. Bibl. 16, Fig. 5.

Preparation and electrochemical performances of ZnMoO4-ZnFe2O4 composite electrode materials

Preparation and electrochemical performances of ZnMoO4-ZnFe2O4 composite electrode materials

Green Building Materials Based on Waste Filler and Binder

Abstract This study is aimed at the application of alternative binder (AB) into bio-aggregate-based composite. The technically important parameters (density, thermal conductivity, water absorption and compressive strength) of 28, 60 and 90 days hardened green composites containing chemically and physico-chemically modified hemp hurds (HH) with AB compared to the Portland cement (PC) are presented. Testing of two reference bio-composites with original HH confirmed higher values of compressive strength and thermal conductivity unlike water absorption for all hardened specimens based on alternative binder (MgO-cement) compared to conventional PC. Changes in the final properties of hardened bio-composites were affected by treatment process of organic filler and alkaline nature of MgO-cement. The combination of purified HH by ultrasound treatment and AB appears to be promising for preparation of bio-based composite material with better properties compared to PC. In this paper, other option of the preparation of bio-composite system based on original (non-treated) filler and binder consisting of optimal activated MgO and silica fume is presented.

Preparation and Properties of Magnetic Carbon Fiber Composite Wave-Absorbing Materials Modified by Carbon/Magnetic Heterogeneous Coating

Preparation and Properties of Magnetic Carbon Fiber Composite Wave-Absorbing Materials Modified by Carbon/Magnetic Heterogeneous Coating

Preparation and Properties of a Sulphoaluminate Magnesium-Potassium Phosphate Green Cementitious Composite Material from Industrial Solid Wastes.

The preparation of high-performance green cementitious material from industrial solid waste is a feasible large-scale utilization approach for industrial solid waste. This work investigates the feasibility of using industrial solid wastes in a sulphoaluminate–magnesium–potassium–phosphate cementitious composite material (SAC-MKPC) clinker preparation and the influence of the calcination temperature and clinker ingredients on the hydration behavior and mechanisms of the SAC-MKPC with a Mg/P ratio of 5. The results show that the novel SAC-MKPC that was prepared from aluminum slag, carbide slag, coal gangue, and magnesium desulfurization slag was composed mainly of mineral MgO, , and C2S and the calcination temperature of the main mineral phases was 1250–1350 °C. The solid-waste-based SAC-MKPC had better mechanical properties and excellent water resistance compared with the MKPC. The optimal compressive strength reached 35.2, 70.9, 84.1, 87.7, and 101.6 MPa at 2 h, 1 d, 3 d, 7 d, and 28 d of hydration, respectively. The X-ray diffraction spectra and scanning electron micrographs of the hydration products of the SAC-MKPC clinker showed that AFt and K-struvite crystals coexisted and adhered to form a dense structure. This work provides an innovative idea to produce green cementitious material using industrial solid wastes and may promote the sustainable development of the power and mining industries.

“Powder electrodeposition” synthesis of NiO-Ni/CNTs composites with high performances of lithium storage battery

The combination of active materials and carbon nanotubes (CNTs) provides an effective way to enhance battery capacity and optimize cycle performance. In the present study, the powder electrodeposition technology is employed to synthesize the NiO-Ni/CNTs composite for the first time. This technique contains the following steps. The CNTs are negatively charged by pre-discharge in lithium-ion batteries. Then, the negatived CNTs are uniformly dispersed in the NiCl2 plating solution by electrostatic repulsion, and the Ni ions are in situ reduced and deposited onto the CNTs. The close combination of CNTs and NiO-Ni improves the overall conductivity and structural stability. As electrode of lithium-ion battery, the reversible capacity is improved due to the coordination of the Ni metal in the mixture of the composite electrode. Besides, the reversible capacity of the composite electrode is 851 mA h g−1 at 50 mA g−1 after 50 cycles. The “Powder electrodeposition” method in the current work provides a new way for the preparation of other similar powder composite materials. Furthermore, the problem that the traditional electrodeposition process is difficult to apply in the powder materials will be solved.

Si@Cu composite anode material prepared by magnetron sputtering for high-capacity lithium-ion batteries

In this study, Si@Cu composite anode material is prepared by magnetron sputtering method and applied for lithium-ion batteries. The Cu component with higher intrinsic conductivity can help to improve the conductivity of the Si particles effectively. The irregularly shaped micro-sized Si particles have reduced agglomeration effect compared with nano-sized particles. In order to further relieve the volume effect of the Si particles during charging and discharging processes, carbon layer is further introduced, which will further boost the conductivity and the cyclic performance. The Si@Cu@C composite electrode exhibits a remarkably improved electrochemical performance with reversible capacity of 1130 mAhg−1 after 100 cycles with coulombic efficiency of 99.3%. The methods used for the preparation of the Si@Cu and Si@Cu@C composite materials are both mass-productive, which is benefit for their practical applications. Moreover, magnetron sputtering method used for composite power preparation has broad application prospects in micro-sized composite material preparation.

RNA-DNA Hybrid Nanoshape Synthesis by Facile Module Exchange.

The preparation of nucleic acid nanostructures has relied predominantly on procedures of additive fabrication in which complex architectures are assembled by concerted self-assembly and sequential addition of building blocks. We had previously established RNA-DNA hybrid nanoshapes with modular architectures that enable multistep synthetic approaches inspired by organic molecular synthesis where additive and transformative steps are used to prepare complex molecular architectures. We report the establishment of module replacement and strand exchange as synthetic transformations in nucleic acid hybrid nanoshapes, which are enabled by minimally destabilizing sequence elements such as a single unpaired overhang nucleotide or a mismatch base pair. Module exchange facilitated by thermodynamic lability triggers adds a powerful transformative approach to the repertoire of additive and transformative synthetic methods for the preparation of complex composite materials.