Effect of compatibilisers on the cure characteristics and mechanical properties of ternary rubber blend composites

Purpose This paper aims to study the effects of various compatibilisers (maleic anhydride (MAH), methyl methacrylate/butyl acrylate emulsion lattice, and adhesion system (HRH)) on properties of carbon black (CB) filled with natural rubber (NR)/styrene-butadiene rubber (SBR)/ nitrile butadiene rubber (NBR) blends). A series of NR/SBR/NBR blends at a 30/30/40 blend ratio reinforced with 45 phr of CB was prepared using the master-batch method. Design/methodology/approach The tensile properties such as the tensile strength, stress at 100, 200 and 300% elongations, and elongation at break (EB)% were studied. Additionally, the morphological properties of compatibilised and uncompatibilised composites were compared to determine the optimal compatibiliser content. Findings The influence of compatibilisers appeared on all the properties studied. The properties of the blends compatibilised with prepared emulsion are very distinct from those of blends compatibilised with MAH and adhesion systems. Research limitations/implications Interactions among the different components of blends at the interfaces have a high impact on the interfacial properties of the rubber blend. Practical implications Compatibilisers significantly improve the physicomechanical properties of the resulting composites with the loading of investigated compatibilisers because of the uniform dispersion of CB in the rubber matrix. Social implications Using blends in the rubber industry leads to high-efficiency production of low-cost products. Originality/value The rubber blending has a significant positive effect on a wide range of applications such as structural applications, aerospace, military, packaging, tires and biomedical. Hence, improving the compatibility of blends will make new materials suitable for new applications.

An investigation on the influence of sintering temperature on microstructural, physical and mechanical properties of Cu-SiC composites

Purpose The purpose of this study is to investigate the effect of the sintering temperature on the microstructural, mechanical and physical properties of Cu-SiC composites. Design/methodology/approach The powder metallurgy route was used to fabricate the samples. Cold compaction of powders was conducted at 250 MPa which was followed by sintering at 850°C–950°C at the interval of 50 °C in the open atmospheric furnace. SiC was used as a reinforcement and the volumetric fraction of the SiC was varied as 10%, 15% and 20%. The processed samples were metallurgically characterized by the scanning electron microscope (SEM). Mechanical characterization was done using tensile and Vickers’ micro-hardness testing to check the hardness and strength of the samples. Archimedes principle and Four-point collinear probe method were used to measure the density and electrical resistivity of the samples. Findings SEM micrograph reveals the uniform dispersion of the SiC particles in the Cu matrix element. The results revealed that the Hardness and tensile strength were improved due to the addition of SiC and were maximum for the samples sintered at 950 °C. The addition of SiC has also increased the electrical resistivity of the Cu-SiC composite and was lowest for Cu 100% while the relative density has shown the reverse trend. Further, it was found that the maximum hardness of 91.67 Hv and ultimate tensile strength of 312.93 MPa were found for Cu-20% SiC composite and the lowest electrical resistivity of 2.017 µ- Ω-cm was found for pure Cu sample sintered at 950 °C, and this temperature was concluded as the optimum sintering temperature. Research limitations/implications The powder metallurgy route for the fabrication of the composites is a challenging task as the trapping of oxygen cannot be controlled during the compaction process as well as during the sintering process. So, a more intensive study is required to overcome these kinds of limitations. Originality/value As of the author’s best knowledge, no work has been reported on the effect of sintering temperature on the properties of the Cu-SiC composites which has huge potential in the industries.

Robust Burst Detection Algorithm for Distributed Unique Word TDMA Signal

In recent years, distributed unique word (DUW) has been widely used in satellite single carrier TDMA signals, such as very small aperture terminal (VSAT) satellite systems. Different from the centralized structure of traditional unique word, DUW is uniformly dispersed in a burst signal, where the traditional unique word detection methods are not applicable anymore. For this, we propose a robust burst detection algorithm based on DUW. Firstly, we allocated the sliding detection windows with the same structures as DUW in order to effectively detect it. Secondly, we adopt the method of time delay conjugate multiplication to eliminate the influence of frequency offset on detection performance. Due to the uniform dispersion of DUW, it naturally has two different kinds of time delays, namely the delay within the group and the delay between the two groups. So, we divide the traditional dual correlation formula into two parts to calculate them separately and obtain a dual correlation detection algorithm, which is suitable for DUW. Simulation and experimental results demonstrate that when the distribution structure of DUW changes, detection probability of the proposed algorithm fluctuates little, and its variance is 1.56×10−5, which is 99.83% lower than the existing DUW detection algorithms. In addition, its signal to noise ratio (SNR) threshold is about 1 dB lower than the existing algorithms under the same circumstance of the missed detection probability.

Rapid Green synthesis of Nano SiO2 using Bryophyllum pinnatum leaf and evaluation of physicochemical quality attributes

The present study focused on determining the phytochemical analysis of the possible chemical groups present in leaves extract, green synthesis, its characterization, and applications. Bryophyllum pinnatum leaf extract was used to synthesized the Silica nanoparticles. Green synthesized nanoparticles were characterized by different techniques such as UV-Visible absorbance spectroscopy, Fourier Transform Infra-Red, X-Ray Diffraction, Scanning Electron Microscope, Energy Dispersive X-Ray, Zeta Potential Analysis and Thermo-Gravimetric Analysis. A UV-Visible spectrum of silica nanoparticles displayed an absorption peak at 280 nm, and FT-IR results highlighted the key bioactive compounds that could be responsible for capping and reduction of Silica nanoparticles. The XRD pattern analysis showed its crystalline nature and an average size is 24 nm. SEM analysis revealed that synthesized nanomaterials are spherical in shape. Silica nanoparticles showed excellent stability with negative zeta potential value (− 32 mV) and uniform dispersion in aqueous media. Moreover, the seed germination assay was carried out on Vigna radiata using the biogenic silica nanoparticles. The low concentration of silica nanoparticles was enhancing the seed germination. Meanwhile, the higher concentration of the silica nanoparticles decreased seed germination and shoot and root formation. Silica nanoparticles at optimum concentration could be used in the agriculture field as nano growth promoters.

Aqueous Processed Ni-Rich Li(Ni0.8Co0.1Mn0.1)O2 Cathodes Along with Water-Based Binders and a Carbon Fabric as 3-D Conductive Host

A carbon fabric with three-dimensional carbon fiber network is proposed as a conductive framework instead of Al current collector, in order to fabricate a LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode using an environmentally friendly water-based process. Water-based NCM811 slurries prepared without binder, with poly(acrylic acid) (PAA) binder, and with poly(acrylonitrile) (PAN) binder have the equilibrium pH values of 12.4, 6.7, and 12.6, respectively. Without a binder, the cathode materials are poorly dispersed in the slurry, which hinders smooth casting on the carbon fabric. The addition of either PAA or PAN improves the uniform dispersion of particles and the loading capability of slurries, leading to a lower impedance of the cast cathodes. Compared to PAA, PAN performs better with the carbon fabric as a conductive framework, due to the better dispersion of electrode materials, lower impedance in the fabricated electrode, and good chemical stability of PAN to the electrolyte. The cell constructed with PAN-added cathode exhibits a high specific capacity of 150–160 mAh g-1 at a charge/discharge rate of 0.5C, and nearly 100% capacity retention after 100 cycles. Nevertheless, PAA is soluble in the electrolyte and has some negative effects on the capacity performance of the constructed cell.

In Situ Reduction of Silver Nanoparticles on the Plasma-Induced Chitosan Grafted Polylactic Acid Nonwoven Fabrics for Improvement of Antibacterial Activity

An eco-friendly approach for improvement of antibacterial properties of polylactic acid (PLA) nonwoven fabrics was obtained by in situ reduction of silver nanoparticles (Ag NPs) on dielectric barrier discharge (DBD) plasma-induced chitosan grafted (DBD-CS-Ag NPs) PLA nonwoven fabrics. The surface morphology, surface element composition and the chemical state of silver of the PLA surfaces after the treatment were evaluated through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The antibacterial activity of DBD-CS-Ag NPs treated PLA against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was tested. The uniform dispersion of silver nanoparticles on the DBD-CS-Ag NPs treated PLA surface were confirmed by SEM images. The results of XPS and XRD showed that the concentration of silver element on the surface of PLA nonwoven fabrics was significantly improved after DBD-CS-Ag NPs treatment. The DBD-CS-Ag NPs treated PLA nonwoven fabrics also exhibited excellent antibacterial properties.

Mechanical, morphological, and fracture-deformation behavior of MWCNTs-reinforced (Al–Cu–Mg–T351) alloy cast nanocomposites fabricated by optimized mechanical milling and powder metallurgy techniques

The carbon nanotube (CNT) is becoming more popular due to their low-density, high-strength etc. Among CNTs, multi-walled carbon nanotubes (MWCNTs) are gaining more importance due to their enhanced thermal and electrical conductivity. The present research is exploring the applicability of MWCNTs reinforced with AA2024-T351 alloys for electromechanical applications. This study is currently undertaken for using MWCNTs as a reinforcing particulate for the purpose to enhance the characteristics including low density, high strength, and hardness together with excellent thermal and electrical conductivity of the aluminum alloy matrices. Therefore, this article provides a state-of-the-art experimental approach to fabricate and furthermore, to evaluate the mechanical characteristics, microstructural analysis, and fatigue behavior of Al–Cu–Mg–T351/MWCNT composites under both the mechanical and thermal loading by utilizing powder technology processing route. The uniform dispersion of CNTs has been exposed using ball milling process. Results revealed that the MWCNTs provide extraordinary synergistic strength, enhances fatigue resistance, creep resistance, ductility, and other mechanical characteristics of the aluminum-based composites. The mechanical loading of the composite exhibited increased properties as compared to thermal-loaded aluminum-MWCNT composites. Findings conclude that the maximum hardness of 35Hv obtained for sintered AA2024-T351 and 45Hv for 0.5% MWCNT heat-treated samples indicate that the addition of MWCNT enhances the hardness which may be because CNT is evenly dispersed at the interfacial space. Maximum UTS of 105.21 MPa was obtained with 0.5% MWCNT for sintered composites. Microstructural analysis of the Al–Cu–Mg–T351/MWCNTs composite exhibits reasonably uniform distribution, void formation, and good interfacial bonding. X-ray Diffraction method patterns of fabricated composite shows that the CNT is present at 2β = 23.6 and 44.6°, whereas high peaks of aluminum are present at uniform dispersed positions. Transmission electron magnifying instrument study further substantiates the above research. Fracture micrographs of the Al–Cu–Mg–T351/MWCNTs composite portray the resistant nature of the nanotubes due to the presence of CNTs, Al–Cu, and aluminum carbide elements in the alloy and the reactions that happened during heat treatment. This significant improvement was attributed to the shear interactions among the constituents and high load carrying capacity of the CNT, uniform dispersion, and interface bond strength among the matrix and constituents. The findings in the study will undoubtedly be beneficial for the development of high-strength, MWCNTs/Al–Cu–Mg–T351, matrix composites in future for multifunctional applications on broader spectrum.

Fabrication techniques of polymeric nanocomposites: A comprehensive review

Nanotechnology is the key solution for many human problems such as energy conversion, water treatment, and material science. In composite materials, nanoparticles are dispersed in a matrix material such as metals, ceramics, or polymers to enhance their mechanical and thermophysical properties. Polymer nanocomposite materials found their applications in vital fields such as the automotive and aircraft industries. There are many techniques adopted to produce polymer nanocomposites, and they are summarized and discussed according to our best known in this paper. All techniques aim to produce nanocomposite materials with uniform dispersion and without aggregations. Melt-mixing, mixing, in-situ polymerization, electrospinning, and selective laser sintering techniques are the most commonly used techniques to produce polymer nanocomposite. The utilization of water, atomic layer deposition, and plasma-assisted mechanochemistry are found to eradicate the issue of nanoparticles aggregation for melt-mixing technique. Also, sonication with high frequencies plays the same role for mixing techniques. In-situ polymerization provides fabrication of nanocomposites that are thermodynamically stable. Electrospinning represents an effective method which is suitable for producing porous structures. In addition, fabrication of nanocomposites via selective laser sintering has obvious benefits to overcome the problem of aggregation. The working principles of each technique, including the advantages and disadvantages, are discussed.

Structural and Infrared Spectroscopy of Polyvinylpyrrolidone/Multi-walled Carbon Nanotubes Nanocomposite

In this work, polyvinylpyrrolidone (PVP)/ Multi-walled carbon nanotubes (MWCNTs) nanocomposites were prepared with two concentrations of MWCNTs by casting method. Morphological, structural characteristics and electrical properties were investigated. The state of MWCNTs dispersion in a PVP matrix was indicated by Field Effect-Scanning Electron Microscopy (FESEM) which showed a uniform dispersion of MWCNTs within the PVP matrix. X-ray Diffraction (XRD) indicate strong bonding of carbonyl groups of PVP composite chains with MWCNTs. Fourier transfer infrared (FTIR) studies shows characteristics of various stretching and bending vibration bands, as well as shifts in some band locations and intensity changes in others. Hall effect was studied to test the type of charge carriers which was shown to be P-type. The electrical conductivity was shown increased for the pure PVP and pure MWCNT from (2.047×10-5) (Ω.cm)-1 and (3.683×101) (Ω.cm)-1 to (2.51×102 and 2.36×102) (Ω.cm)-1for both concentrations of nanocomposites, which indicate the conductivity was enhancement by using the carbon nanotubes.

Synthesis of Mg-Al Hydrotalcite Clay with High Adsorption Capacity

A novel Mg-Al metal oxide has been successfully synthesized by the calcination of hierarchical porous Mg-Al hydrotalcite clay obtained by using filter paper as a template under hydrothermal conditions. Various characterizations of the obtained nanoscale oxide particles verified the uniform dispersion of Mg-Al metal oxides on the filter paper fiber, which had a size of 2–20 nm and a highest specific surface area (SSA) of 178.84 m2/g. Structural characterization revealed that the as-prepared Mg-Al metal oxides preserved the tubular morphology of the filter paper fibers. Further experiments showed that the as-synthesized Mg-Al metal oxides, present at concentrations of 0.3 g/L, could efficiently remove sulfonated lignite from oilfield wastewater (initial concentration of 200 mg/L) in a neutral environment (pH = 7) at a temperature of 298 K. An investigation of the reaction kinetics found that the adsorption process of sulfonated lignite (SL) on biomorphic Mg-Al metal oxides fits a Langmuir adsorption model and pseudo-second-order rate equation. Thermodynamic calculations propose that the adsorption of sulfonated lignite was spontaneous, endothermic, and a thermodynamically feasible process.