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Graphite nanoplatelets (GNPs) are a type of graphitic nanofillers composed of stacked 2D graphene sheets, having outstanding electrical, thermal, and mechanical properties. Furthermore, owing to the abundance of naturally existing graphite as the source material for GNPs, it is considered an ideal reinforcing component to modify the properties of polymers. The 2D confinement of GNPs to the polymer matrix and the high surface area make the GNP a distinctive nanofiller, showing superiorities in modification of most properties, compared with other carbon nanofillers. This review will summarize the development of polymer/GNP nanocomposites in recent years, including the fabrication of GNPs and its nanocomposites, processing issues, viscoelastic properties, mechanical properties, electrical and dielectric properties, thermal conductivity and thermal stability. The discussion of reinforcing effect will be based on dispersion, particle geometry, concentrations, as well as the 2D structures and exfoliation of GNPs. The synergy of GNPs with other types of carbon nanofillers used as hybrid reinforcing systems shows great potential and could significantly broaden the application of GNPs. The relevant research will also be included in this review.

This study deals with the determination of new natural fibers extracted from the Corypha taliera fruit (CTF) and its characteristics were reported for the potential alternative of harmful synthetic fiber. The physical, chemical, mechanical, thermal, and morphological characteristics were investigated for CTF fibers. X-ray diffraction and chemical composition characterization ensured a higher amount of cellulose (55.1 wt%) content and crystallinity (62.5%) in the CTF fiber. The FTIR analysis ensured the different functional groups of cellulose, hemicellulose, and lignin present in the fiber. The Scherrer’s equation was used to determine crystallite size 1.45 nm. The mean diameter, specific density, and linear density of the CTF fiber were found (average) 131 μm, 0.86 g/cc, and 43 Tex, respectively. The maximum tensile strength was obtained 53.55 MPa for GL 20 mm and Young’s modulus 572.21 MPa for GL 30 mm. The required energy at break was recorded during the tensile strength experiment from the tensile strength tester and the average values for GL 20 mm and GL 30 mm are 0.05381 J and 0.08968 J, respectively. The thermal analysis ensured the thermal sustainability of CTF fiber up to 230 °C. Entirely the aforementioned outcomes ensured that the new CTF fiber is the expected reinforcement to the fiber-reinforced composite materials.

The paper presents a general approach to geometric modelling of torse surfaces in BN-calculus, based on the definition of the torse as the geometric location of tangents to its edge of return. In this paper, a method for determining the curves - edges of the return of the torse surface, using the geometric properties of the point definition of the curve in plane and spatial simplices, is proposed in general form. Examples of constructing geometric models of torse surfaces, for which algebraic and transcendental spatial curves were used as the return edge, are given.

The ultrafast reversibility of changes to the electronic structure and electric polarizability of a dielectric with the electric field of a laser pulse, demonstrated here, offers the potential for petahertz-bandwidth optical signal manipulation. Dielectrics turned conductor in a flash Two studies published in this issue highlight the potential for ultrafast signal manipulation in dielectrics using optical fields. When it comes to electrical signal processing, semiconductors have become the materials of choice. However, insulators such as dielectrics could be attractive alternatives: they have a fast response in principle, but usually have extremely low conductivity at low electric fields and break down in large fields. The electronic properties of dielectrics can be controlled with few-cycle laser pulses that permit damage-free exposure of dielectrics to high electric fields. Agustin Schiffrin et al . demonstrate that strong optical laser fields with controlled few-cycle waveforms can reversibly transform a dielectric insulator into a conductor within the optical period (within one femtosecond). Martin Schultze et al . address the crucial issue of ultrafast reversibility, demonstrating that the dielectric can be repeatedly switched 'on' and 'off' with light fields, without degradation. The control of the electric and optical properties of semiconductors with microwave fields forms the basis of modern electronics, information processing and optical communications. The extension of such control to optical frequencies calls for wideband materials such as dielectrics, which require strong electric fields to alter their physical properties 1 , 2 , 3 , 4 , 5 . Few-cycle laser pulses permit damage-free exposure of dielectrics to electric fields of several volts per ångström 6 and significant modifications in their electronic system 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 . Fields of such strength and temporal confinement can turn a dielectric from an insulating state to a conducting state within the optical period 14 . However, to extend electric signal control and processing to light frequencies depends on the feasibility of reversing these effects approximately as fast as they can be induced. Here we study the underlying electron processes with sub-femtosecond solid-state spectroscopy, which reveals the feasibility of manipulating the electronic structure and electric polarizability of a dielectric reversibly with the electric field of light. We irradiate a dielectric (fused silica) with a waveform-controlled near-infrared few-cycle light field of several volts per angström and probe changes in extreme-ultraviolet absorptivity and near-infrared reflectivity on a timescale of approximately a hundred attoseconds to a few femtoseconds. The field-induced changes follow, in a highly nonlinear fashion, the turn-on and turn-off behaviour of the driving field, in agreement with the predictions of a quantum mechanical model. The ultrafast reversibility of the effects implies that the physical properties of a dielectric can be controlled with the electric field of light, offering the potential for petahertz-bandwidth signal manipulation.

Additive Manufacturing technology has a significant impact on the modern world because of its ability to fabricate highly complex computerized geometrics. Pure 3D-printed polymer parts have limited potential applications due to inherently inferior mechanical and anisotropic properties. For more utilization and versatility, the addition of fillers has enhanced their functionalities. 3D printing has innovative advantages including low cost, minimal wastage, customized geometry, and ease of material change. This review reveals the development of 3D printing techniques of matrix composite materials with improving properties and their applications in the fields of aerospace, automotive, biomedical, and electronics. A general introduction is given on AM techniques mainly fused deposition modeling (FDM), Powder-liquid 3D printing (PLP), selective laser sintering (SLS), stereolithography (SLA), digital light processing (DLP), and robocasting. Process methodologies and behavior of different filler additives, reinforcement fibers, nanoparticles, and ceramic polymer composites are discussed. Also, some major issues of difficulty including printing parameters, homogeneous desperation of fillers, nozzle clogging due to filler aggregation, void formation, augmented curing time, and anisotropic attributes are addressed. In the end, some capabilities and shortcomings are pointed out for further development of 3D-printing technology.

Ionic liquids are room-temperature molten salts, composed mostly of organic ions that may undergo almost unlimited structural variations. This review covers the newest aspects of ionic liquids in applications where their ion conductivity is exploited; as electrochemical solvents for metal/semiconductor electrodeposition, and as batteries and fuel cells where conventional media, organic solvents (in batteries) or water (in polymer-electrolyte-membrane fuel cells), fail. Biology and biomimetic processes in ionic liquids are also discussed. In these decidedly different materials, some enzymes show activity that is not exhibited in more traditional systems, creating huge potential for bioinspired catalysis and biofuel cells. Our goal in this review is to survey the recent key developments and issues within ionic-liquid research in these areas. As well as informing materials scientists, we hope to generate interest in the wider community and encourage others to make use of ionic liquids in tackling scientific challenges.

Cellulose is a fascinating biopolymer of almost inexhaustible quantity. While being a lightweight material, it shows outstanding values of strength and stiffness when present in its native form. Unsurprisingly, cellulose fibre has been rigorously investigated as a reinforcing component in biocomposites. In recent years, however, a new class of monocomponent composites based on cellulosic materials, so-called all-cellulose composites (ACCs) have emerged. These new materials promise to overcome the critical problem of fibre–matrix adhesion in biocomposites by using chemically similar or identical cellulosic materials for both matrix and reinforcement. A number of papers scattered throughout the polymer, composites and biomolecular science literature have been published describing non-derivatized and derivatized ACCs. Exceptional mechanical properties of ACCs have been reported that easily exceed those of traditional biocomposites. Several different processing routes have been applied to the manufacture of ACCs using a broad range of different solvent systems and raw materials. This article aims to provide a comprehensive review of the background chemistry and various cellulosic sources investigated, various synthesis routes, phase transformations of the cellulose, and mechanical, viscoelastic and optical properties of ACCs. The current difficulties and challenges of ACCs are clearly outlined, pointing the way forward for further exploration of this interesting subcategory of biocomposites.

The high natural abundance of silicon, together with its excellent reliability and good efficiency in solar cells, suggest its continued use in production of solar energy, on massive scales, for the foreseeable future. Although organics, nanocrystals, nanowires and other new materials hold significant promise, many opportunities continue to exist for research into unconventional means of exploiting silicon in advanced photovoltaic systems. Here, we describe modules that use large-scale arrays of silicon solar microcells created from bulk wafers and integrated in diverse spatial layouts on foreign substrates by transfer printing. The resulting devices can offer useful features, including high degrees of mechanical flexibility, user-definable transparency and ultrathin-form-factor microconcentrator designs. Detailed studies of the processes for creating and manipulating such microcells, together with theoretical and experimental investigations of the electrical, mechanical and optical characteristics of several types of module that incorporate them, illuminate the key aspects. In a device design that brings mechanical flexibility to silicon photovoltaics, Jongseung Yoon, Alfred J. Baca and colleagues demonstrate how transfer-printing of ultrathin silicon films onto flexible substrates leads to semitransparent and large-scale arrays of integrated solar microcells with high solar-energy conversion efficiencies of 6–8%.

In this article, polythiophene (PTh) and a sequence of PTh/(1, 5, 10 wt.%) ZnO composites were prepared by in situ chemical oxidative polymerization method. The successful formation of PTh, ZnO, and interaction between PTh and ZnO were confirmed by various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry, UV–vis spectroscopy, fluorescence studies, followed by DC electrical conductivity. The XRD spectra showed crystallinity modification for PTh with ZnO wt.%, demonstrating the crystal structure of the sulfur modification. The SEM micrographs showed the existence of randomly linked ZnO nanoparticles, confirming the interaction of ZnO nanoparticles with the polymer matrix. A good agreement was observed in comparison to spectral studies. From the Tauc plot, it was found that the pure PTh bandgap was 2.0 eV and eventually decreased on decreasing the (wt.%) of doping. PTh/10(wt.%) ZnO showed enhanced conductivity (i.e., 0.00982 S cm −1 ) compared to pure PTh (0.000472 Scm −1 ). At room temperature (30 °C), the sensing performance was evaluated in terms of percent sensing and response/recovery time. It was noticed that the prepared composites were suitable for acetone sensing. Pure PTh showed 48.40% sensitivity, and sensitivity response for PTh/1(wt.%) ZnO, PTh/5(wt.%) ZnO, and PTh/10(wt.%) ZnO was 55.35%, 58.08%, and 75.11%, respectively. Sensitivity of the PTh/10(wt.%) ZnO composites–based sensors increased more than that of PTh. PTh/10(wt.%) ZnO showed a 122 s response time compared to another fabricated sensor. In reversibility test for PTh/10(wt.%) ZnO, an oscillating trend in sensitivity for four cycles was observed. The sensor’s operating stability was checked over a 16-day period and a fluctuating trend was observed in percentage sensitivity, reversibility, and response/recovery time.

Tungsten disulfide (WS2) has attracted great attention for use in optoelectronics due to its suitable bandgap and adjustable properties. However, the structure and photoelectric properties of bulk WS2 are not well understood. The first-principles method is applied herein to study the structural stability and electronic and optical properties of WS2. Two phases, viz. hexagonal and rhombohedral, are considered. The results reveal that the two bulk WS2 phases are thermodynamically and dynamically stable based on the enthalpy of formation and phonon dispersion. The structural stability of WS2 is attributed to the S–W–S sandwich structure. The calculated bandgap of hexagonal and rhombohedral WS2 is 1.552 eV and 1.488 eV, respectively, indicating that WS2 is semiconducting. The calculated optical properties show that WS2 exhibits excellent adsorption capacity for ultraviolet light, whether in the hexagonal or rhombohedral structure.