Nonpolar Materials Research Articles

Characteristic identification of steel corrosion products based on terahertz transmission spectroscopy

Corrosion of steel materials (such as rebars and steel plates) usually occurs under coating materials. It is, with the existing non-destructive testing (NDT) technologies, difficult to accurately determine the corrosion of steel materials. The terahertz (THz) electromagnetic waves can penetrate the non-polar materials, and theoretically experience an absorption resonance with some corrosion products crystals (i.e., iron oxides). The THz spectroscopy has, therefore, a great application potential to characteristically identify the corrosion of steel materials. In the present study, the optical parameters and, especially, the positions of the characteristic absorption peaks of the corrosion products were systematically investigated and identified using the THz system. The experimental results showed that the refractive index of the different corrosion product samples was in the range of 2.7–3.4 in the effective frequency range of 0 THz - 1.2 THz, and the content of Fe3O4 had a large influence on the optical parameters in the corrosion product mixtures. To measure the characteristic absorption peaks of the corrosion products, the effective frequency range was extended to 0 THz - 10 THz by an assembled broadband THz system. Within this range, the positions of the characteristic absorption peaks were identified as 3.4 THz, 4.2 THz, 4.85 THz, and 5.8 THz for Fe2O3, and as 3.6 THz, 4.05 THz, 5 THz, and 5.45 THz for α-FeOOH. For Fe2O3 and α-FeOOH, the intensities of the absorption peaks at 4.85 THz and 3.6 THz, respectively, showed a linear relationship with the mass content. Furthermore, the THz spectroscopy could accurately identify Fe2O3 and α-FeOOH in the corrosion product mixtures by comparing with the results from IR spectroscopy and Raman spectroscopy. This means that the occurrence of steel corrosion could be detected according to the characteristic absorption peaks of Fe2O3 and α-FeOOH. The experimental results provide a basis for the application of THz spectroscopy in the NDT of the corrosion of steel materials.

Natural Rubber Latex-Modified Concrete with PET and Crumb Rubber Aggregate Replacements for Sustainable Rigid Pavements

There are ongoing research challenges for the addition of the blend of PET and crumb rubber in polymer-modified concretes, which aims to leverage the benefits of both materials. In this study, various percentage combinations of waste aggregates, such as PET and crumb rubber, were used to replace coarse and fine aggregates in natural rubber latex (NRL)-modified concrete. Engineering properties such as compressive and flexural strengths, modulus of elasticity, and toughness obtained from compressive- and flexural stress-strain curves were investigated. Scanning electron microscopy (SEM) analysis was performed to examine the microstructural properties and study the strength development of the studied concretes. The results revealed that the compressive and flexural strengths of NRL-modified concretes with PET and crumb rubber aggregate replacements decreased with increasing replacement ratios. SEM analysis indicated that PET and crumb rubber (hydrophobic and non-polar materials) can affect the microstructure of the studied concrete by creating a weak interface between the aggregate and cement pastes, leading to reduced strength development. With the addition of the NRL additive, the film formation was found to act as a bridge and improve the bond strength of aggregates and hydration products in NRL-modified concrete. Furthermore, the integration of PET and crumb rubber aggregate can enhance the ability of the concrete to absorb energy and improve ductility. It was found that 10% of PET and crumb rubber aggregate replacement can be used for NRL-modified concrete as a rigid pavement, as its mechanical strengths satisfy the requirements set by the Department of Highways (DOH) in Thailand. This research helps repurpose waste materials and reduce the environmental footprint of concrete production.

The effect of substituent group in allyl benzoxazine on the thermal, mechanical and dielectric properties of modified bismaleimide

Allyl benzoxazine resin (BOZ-A) synthesized from 2,2′-diallyl bisphenol A (DABPA), aniline and paraformaldehyde has been used to improve the mechanical and processing properties of bismaleimide resin. However, the lower heat resistance and the unsatisfactory dielectric properties cannot satisfy the requirements of high-performance composites in aerospace fields. Introducing nonpolar materials into the resin matrix effectively improves the dielectric properties. Inspired by the designability of benzoxazine, a novel allyl benzoxazine resin grafted with trifluoromethyl (BOZ-F) or methyl (BOZ-C) was synthesized and blended with BD-type bismaleimide resin (BDM-C and BDM-F) to explore the effect of substituent groups on the comprehensive performance. Due to the different electronic effects of the substituents, BDM-C possesses higher reactivity with a polymerization temperature of 212.7 °C, which is lower than that of BDM-A (217.8 °C) and BDM-F (226.6 °C). Their respective reactivity also leads to differences in rheological properties. Specifically, BDM-F exhibited the excellent thermal stability with a Tg of 308.3 °C, which is 17.2 °C higher than that of BDM-A. Furthermore, the dielectric constant (Dk) and dielectric loss (Df) of BDM-F at 10.5 GHz decreased to 3.06 and 0.0078 from 3.13 and 0.0114 when compared with BDM-A. In addition, BDM-C demonstrated the highest bending strength of 136.02 MPa. The current study delivers an effective approach to balance the performance of thermosetting resins by regulating substituents, which is valuable for potential application in wave-transparent fields.

Dopamine-Based Copolymer Bottlebrushes for Functional Adhesives: Synthesis, Characterization, and Applications in Surface Engineering of Antifouling Polyethylene.

Nonpolar materials like polyolefins are notoriously challenging substrates for surface modification. However, this challenge is not observed in nature. Barnacle shells and mussels, for example, utilize catechol-based chemistry to fasten themselves onto all kinds of materials, such as boat hulls or plastic waste. Here, a design is proposed, synthesized, and demonstrated for a class of catechol-containing copolymers (terpolymers) for surface functionalization of polyolefins. Dopamine methacrylamide (DOMA), a catechol-containing monomer, is incorporated into a polymer chain together with methyl methacrylate (MMA) and 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM). DOMA serves as adhesion points, BIEM provides functional sites for subsequent "grafting from" reactions, and MMA provides the possibility for concentration and conformation adjustment. First, the adhesive capabilities of DOMA are demonstrated by varying its content in the copolymer. Then, terpolymers are spin-coated on model Si substrates. Subsequently, the atom transfer initiator (ATRP) initiating group is used to graft a poly(methyl methacrylate) (PMMA) layer from the copolymers, with 40% DOMA content providing a coherent PMMA film. To demonstrate functionalization on a polyolefin substrate, the copolymer is spin-coated on high-density polyethylene (HDPE) substrates. A POEGMA layer is grafted from the ATRP initiator sites on the terpolymer chain on the HDPE films to provide antifouling characteristics. Static contact angle values and Fourier transform infrared (FTIR) spectra confirm the presence of POEGMA on the HDPE substrate. Finally, the anticipated antifouling functionality of grafted POEGMA is demonstrated by observing the inhibition of nonspecific adsorption of the fluorescein-modified bovine serum albumin (BSA) protein. The poly(oligoethylene glycol methacrylate) POEGMA layers grafted on 30% DOMA-containing copolymers on HDPE show optimal antifouling performance exhibiting a 95% reduction of BSA fluorescence compared to nonfunctionalized and surface-fouled polyethylene. These results demonstrate the successful utilization of catechol-based materials for functionalizing polyolefin surfaces.

Metasurface-Assisted Terahertz Sensing.

Terahertz (THz) waves, which fall between microwaves and infrared bands, possess intriguing electromagnetic properties of non-ionizing radiation, low photon energy, being highly sensitive to weak resonances, and non-polar material penetrability. Therefore, THz waves are extremely suitable for sensing and detecting chemical, pharmaceutical, and biological molecules. However, the relatively long wavelength of THz waves (30~3000 μm) compared to the size of analytes (1~100 nm for biomolecules, <10 μm for microorganisms) constrains the development of THz-based sensors. To circumvent this problem, metasurface technology, by engineering subwavelength periodic resonators, has gained a great deal of attention to enhance the resonance response of THz waves. Those metasurface-based THz sensors exhibit high sensitivity for label-free sensing, making them appealing for a variety of applications in security, medical applications, and detection. The performance of metasurface-based THz sensors is controlled by geometric structure and material parameters. The operating mechanism is divided into two main categories, passive and active. To have a profound understanding of these metasurface-assisted THz sensing technologies, we review and categorize those THz sensors, based on their operating mechanisms, including resonators for frequency shift sensing, nanogaps for enhanced field confinement, chirality for handedness detection, and active elements (such as graphene and MEMS) for advanced tunable sensing. This comprehensive review can serve as a guideline for future metasurfaces design to assist THz sensing and detection.

Heterogenization Strategies for Nickel Catalyzed Synthesis of Polyolefins and Composites

ConspectusPolyolefin is one of the most common synthetic polymers. However, most polyolefins are nonpolar materials, which leads to poor compatibility with polar materials, thus limiting their application in some fields. Polar functionalized polyolefins can lead to significantly improved dyeability, adhesiveness and compatibility with polar fillers, and can realize customized properties of polyolefin materials. Transition-metal-catalyzed coordination copolymerization of olefin and polar functionalized comonomers represents a direct and potentially economic route to synthesize polar-functionalized polyolefin materials, which has attracted great attention in recent decades. Literally hundreds of nickel and palladium catalysts have been synthesized and investigated in olefin-polar monomer copolymerization to achieve high copolymerization efficiency by tuning the molecular structures of the catalysts. In particular, earth-abundant and low-cost nickel-based catalysts hold great potential for industrial applications. However, most research efforts focus on homogeneous copolymerization catalysts, while the industrially preferred heterogeneous systems have remained largely unexplored. With the objective of bridging this gap, our group has recently developed a series of heterogenization strategies for the synthesis of high-performance heterogeneous nickel catalysts taking advantage of hydrogen bond anchoring, ionic anchoring, coanchoring, cocatalyst, and ionic cluster formation. These strategies involve known or easily accessible catalysts, can be easily adapted to various catalytic systems, and can lead to simultaneous enhancement in all copolymerization parameters such as thermal stability, activity, comonomer incorporation ratio, and copolymer molecular weight versus the homogeneous counterparts. In addition, the performance of the catalysts can be tuned by changing the type of the support, thereby facilitating the discovery of high-performance heterogeneous nickel catalysts. Most importantly, great product morphology control can be achieved. This is desirable for industrial polymerization processes because it avoids reactor fouling and results in significant improvements in the safety and operational efficiency of the polymerization processes. Finally, these heterogenization strategies give access to high-performance polyolefin materials (polar-functionalized polyolefins, polar-functionalized polyolefin in-reactor blends and polyolefin-based functional composites) with custom-made properties. Compared with melt blending, polyolefin composites obtained by heterogeneous catalytic in situ polymerization have better material properties. By using functional fillers, customized polyolefin composites with high performance can be prepared in situ. These polyolefin-based materials have potential applications in many fields, such as electrical and thermal conductivity, photodegradation, flame retardancy, barrier, etc. It is expected that the continuous research on the copolymerization mechanism/catalysts, heterogenizatioin strategies and material properties of polar functionalized polyolefins and their composites will eventually achieve commercialization of nickel-catalyzed production of polyolefins and composites.

High‐damping ultralow−gel nonpolar elastomeric polymer through thiol−ene photo−click chemistry reaction

AbstractWith the increasing demand for high‐performance damping rubber material in various fields, improving the damping performance of existing nonpolar rubber has garnered tremendous scientific and industrial interest. However, it remains a long‐standing challenge to improve the damping properties of nonpolar rubber materials due to their low intrinsic glass transition temperature (Tg) and incompatible surface energy with high‐damping polar polymers or fillers. To solve this conundrum, ultra‐low gel multifunctional carboxy‐functional high vinyl polybutadiene HVBR (HVBR/COOH‐x%) was prepared by grafting 3‐mercaptopropionic acid (3PMA) onto HVBR via thiol−ene photo−click. The effects of reaction parameters including molecular weight, 1,2‐vinyl content, photoinitiators, reaction time, thiol and photoinitiator dosage on gel content and carboxyl grafting ratio were investigated. The HVBR/COOH‐x% demonstrate a controllable grafting ratio range from 2% to 73%. Furthermore, the increased Tg and intermolecular force resulted in excellent performance, including high‐glass transition temperature of 26.3°C, tensile strength of 15.52 MPa, and elongation at break of 396.16%. Particularly with a wide range of effective damping temperatures above 46.6°C. Meanwhile, COOH endowed the HVBR with better self‐viscosity, but also equipped it with stronger mutual viscosity. Therefore, this experiment proposes a feasible path to high damping and high adhesion in nonpolar rubber materials.

Urban sewage sludge valorization to biodiesel production: Solvent-free lipid recovery through adsorption on used 3 Ply Safety Face Masks

The use of urban sewage sludge as the feedstock of lipids to produce biodiesel is a topic of great interest and potential. However, the extractive step, conventionally operated with organic solvents, makes this use unfeasible and with a high environmental impact. In this work, for the first time, the solvent-free recovery of lipids from sewage sludge was studied through adsorption onto non-polar polymeric materials (Spunbonded nonwoven Polypropylene (s-nwPP)). After being immersed in sedimented sewage sludge (TS: 6.9 wt%), s-nwPP sheets were easily separated, dried and analyzed: sewage sludge’s lipids were preferentially adsorbed onto the polymeric surface. Free fatty acids (FFAs) were the dominant species and were recovered from s-nwPP sheets through acidic methanol in a separated reactive washing step as fatty acid methyl esters (FAMEs) A crude product was obtained through this sequence of adsorption and reactive desorption operations, with a FAMEs content of over 55 wt%. After preliminary investigations on commercial s-nwPP sheets, 3 Ply Safety Face Masks were also positively tested. pH, weight ratio polymer/wet sludge (R) and temperature were the parameters optimized: operating at 343 K under acidic conditions (pH of sludge<2), with an R equal to 6%, a total FFAs recovery yield of 70% as FAMEs was already achieved after two adsorption cycles. A preliminary evaluation of the economic feasibility demonstrated that used PP surgical facial masks allow the recovery and generation of crude biodiesel from sewage sludge at a very reasonable price with minimal environmental impacts.

A non-second-gradient model for nonlinear elastic bodies with fibre stiffness

In the past, to model fibre stiffness of finite-radius fibres, previous finite-strain (nonlinear) models were mainly based on the theory of non-linear strain-gradient (second-gradient) theory or Kirchhoff rod theory. We note that these models characterize the mechanical behaviour of polar transversely isotropic solids with infinitely many purely flexible fibres with zero radius. To introduce the effect of fibre bending stiffness on purely flexible fibres with zero radius, these models assumed the existence of couple stresses (contact torques) and non-symmetric Cauchy stresses. However, these stresses are not present on deformations of actual non-polar elastic solids reinforced by finite-radius fibres. In addition to this, the implementation of boundary conditions for second gradient models is not straightforward and discussion on the effectiveness of strain gradient elasticity models to mechanically describe continuum solids is still ongoing. In this paper, we develop a constitutive equation for a non-linear non-polar elastic solid, reinforced by embedded fibers, in which elastic resistance of the fibers to bending is modelled via the classical branches of continuum mechanics, where the development of the theory of stresses is based on non-polar materials; that is, without using the second gradient theory, which is associated with couple stresses and non-symmetric Cauchy stresses. In view of this, the proposed model is simple and somewhat more realistic compared to previous second gradient models.

Dual functional effect of oxygen vacancies and depolarity shield embedded NiCo2O4 cathode in lithium sulfur battery

Lithium–sulfur (Li–S) batteries are considered as promising candidates for next-generation energy-storage devices. However, their reaction reversibility is impacted by severe capacity fading caused by the lithium polysulfides (LiPSs) shuttle effect and consequent loss of active materials in the cathode. Typically, light-weight and nonpolar carbon materials are used as hosts of sulfur but face several issues such as short lifetime, low activity and capacity, which limit the cycling stability and volumetric energy density. Herein, fluorine-doped NiCo2O4 nanofibers with oxygen vacancies are explored as a high-performance host in Li–S batteries. By regulating the ratio of the fluoride ion, the formation of a cathode electrolyte interface (CEI) layer is suppressed during the charge/discharge cycles. Accordingly, the nanofiber electrode exhibits lower polarization and faster reaction kinetics than fluorine-doped NiCo2O4 without oxygen vacancies or NiCo2O4 with a CEI layer. The optimized fluorine-doped NiCo2O4 electrode with oxygen vacancies delivers 628 mAh g−1 at 0.3 C and a low fading rate of 0.052% per cycle over 1300 cycles at 1 C. The present strategy provides insights in the development of host materials that is based on regulating the formation of the CEI layer and the adsorption and conversion of LiPSs.

Molecular Behavior of 1K Polyurethane Adhesive at Buried Interfaces: Plasma Treatment, Annealing, and Adhesion.

One-part (1K) polyurethane (PU) adhesive has excellent bulk strength and environmental resistance. It is therefore widely used in many fields, such as construction, transportation, and flexible lamination. However, when contacting non-polar polymer materials, the poor adhesion of 1K PU adhesive may not be able to support its outdoor applications. To solve this problem, plasma treatment of the non-polar polymer surface has been utilized to improve adhesion between the polymer and 1K PU adhesive. The detailed mechanisms of adhesion enhancement of the 1K PU adhesive caused by plasma treatment on polymer substrates have not been studied extensively because adhesion is a property of buried interfaces which are difficult to probe. In this study, sum frequency generation (SFG) vibrational spectroscopy was used to investigate the buried PU/polypropylene (PP) interfaces in situ nondestructively. Fourier-transform infrared spectroscopy, the X-ray diffraction technique, and adhesion tests were used as supplemental methods to SFG in the study. The 1K PU adhesive is a moisture-curing adhesive and usually needs several days to be fully cured. Here, time-dependent SFG experiments were conducted to monitor the molecular behaviors at the buried 1K PU adhesive/PP interfaces during the curing process. It was found that the PU adhesives underwent rearrangement during the curing process with functional groups gradually becoming ordered at the interface. Stronger adhesion between the plasma-treated PP substrate and the 1K PU adhesive was observed, which was achieved by the interfacial chemical reactions and a more rigid interface. Annealing the samples increased the reaction speed and enhanced the bulk PU strength with higher crystallinity. In this research, molecular mechanisms of adhesion enhancement of the 1K PU adhesive caused by the plasma treatment on PP and by annealing the PU/PP samples were elucidated.

How a Ferroelectric Layer Can Tune a Two-Dimensional Electron Gas at the Interface of LaInO3 and BaSnO3: A First-Principles Study.

The emerging interest in two-dimensional electron gases (2DEGs), formed at interfaces between two insulating oxide perovskites, poses a crucial fundamental question in view of future electronic devices. In the framework of density-functional theory, we investigate the possibility to control the characteristics of the 2DEG formed at the LaInO3/BaSnO3 interface by including a ferroelectric layer. To do so, we consider BaTiO3 as a prototype example and examine how the orientation of the ferroelectric polarization impacts density and confinement of the 2DEG. We find that aligning the ferroelectric polarization toward (outward) the LaInO3/BaSnO3 interface leads to an accumulation (depletion) of the interfacial 2DEG. Varying its magnitude, we find a linear effect on the 2DEG charge density that is confined within the BaSnO3 side. Analysis of the optimized geometries reveals that inclusion of the ferroelectric layer makes structural distortions at the LaInO3/BaSnO3 junction less pronounced, which, in turn, enhances the 2DEG density. Thicker ferroelectric layers allow for reaching higher polarization magnitude. We discuss the mechanisms behind all these findings and rationalize how the characteristics of both 2DEGs and 2D hole gases can be controlled in the considered heterostructures. Overall, our results can be generalized to other combinations of ferroelectric, polar, and nonpolar materials.

Tuning of Polar Domain Boundaries in Nonpolar Perovskite.

Domain boundaries in ferroic materials are found to have various physical properties not observed in the surrounding domains. Such differences can be enhanced and bring promising functionalities when centrosymmetric nonpolar materials encounter polar domain boundaries. In this work, a tunable polar domain boundary is discovered in an antiferroelectric single crystal. Under a small stress or electric field, the density, volume, and polarity of the boundaries are successfully controlled.

Nonpolar and Ultra-long-chain Ligand to Modify the Perovskite Interface toward High-Efficiency and Stable Wide Bandgap Perovskite Solar Cells

Though tandem solar cells (TSCs) based on wide-bandgap perovskite solar cells (WB-PSCs) as the top sub-cells continuously gain efficiency breakthroughs, the low power conversion efficiency (PCE) of WB-PSCs caused by the defects and interface energy-level mismatch is still a vital issue limiting their performance. Moreover, the stability of the perovskite layer against the moisture and subsequent fabrication process is essential to highly stable TSCs. Herein, a nonpolar material with an ultra-long chain, didodecyldimethylammonium bromide (DDAB), was introduced to WB-PSCs as an interface material for reducing the surface defects and increasing the surface hydrophobicity of the perovskite layer. The DDAB-modified perovskite surface is much more hydrophobic, with a water contact angle of 104.9°. Systemically experimental studies reveal that apart from the passivation on the point defects, DDAB can suppress the formation of PbI2 aggregates, smoothing the perovskite surface and shifting the energy level upward. As a result, the 1.74 eV WB-PSCs with inverted structures exhibit a champion PCE of 18.74% by DDAB modification, compared to the standard device with a PCE of 16.50%. The device stability under a relative humidity of >85% is apparently enhanced by 5-fold. This work provides a concept of screening interface materials for highly efficient and stable WB-PSCs.

Solvent Effects in the Preparation of Catalysts Using Activated Carbon as a Carrier.

The role of solvents is crucial in catalyst preparation. With regard to catalysts prepared with activated carbon (AC) as the carrier, when water is used as a solvent it is difficult for the solution to infiltrate the AC. Because AC comprises a large number of C atoms and is a nonpolar material, it is more effective for the adsorption of nonpolar substances. Since the water and active ingredients are polar, they cannot easily infiltrate AC. In this study, the dispersion of the active component was significantly improved by optimizing the solvent, and the particle size of the active component was reduced from 33.08 nm to 15.30 nm. The specific surface area of the catalyst is significantly increased, by 10%, reaching 991.49 m2/g. Under the same reaction conditions, the conversion of acetic acid by the catalyst prepared with the mixed solvent was maintained at approximately 65%, which was 22% higher than that obtained using the catalyst prepared with water as the solvent.

Stereoselective Polymerization of Aromatic Vinyl Polar Monomers

AbstractPolar vinyl polymers, a class of polymers with polar groups as side chains, have significant advantages over conventional nonpolar polyolefin materials in terms of viscosity, toughness, interfacial properties (dyeability and printability), and compatibility with solvents or other polymers. Among them, aromatic polar vinyl polymers are of interest because of their good heat resistance properties. In addition, stereoselective polymerization of aromatic polar vinyl monomers has been rapidly developed because the steric structure of the polymer has a significant impact on its physical properties. In this paper, we review the research progress of stereoselective polymerization catalysts for aromatic polar vinyl monomers in recent years, discuss in detail the influence of ligand structure, electronic effect of substituents, spatial site resistance effect, central rare earth metal species and polymerization solvents on the activity and stereoselectivity of polymerization reactions, and explore the possible mechanism of polymerization reaction.

Dynamics simulation of the effect of cosolvent on the solubility and tackifying behavior of PDMS tackifier in supercritical CO2 fracturing fluid

Due to the low viscosity of supercritical carbon dioxide (SC-CO2) fracturing fluid, the method of adding tackifier is generally chosen to improve its sand carrying ability. Recently, siloxane-based tackifier has been widely utilized because of low cohesive energy and good viscosity building properties, but cosolvents are somehow needed to be added in the system to improve its solubility in SC-CO2. In this study, polydimethylsiloxane (PDMS)- a widely used siloxane polymer- was selected as the object tackifier. First, the effects of the addition of cosolvents such as ethanol, acetic acid, cyclohexane and toluene on dissolution behaviors of PDMS in SC-CO2 fracturing fluid were investigated by molecular dynamics simulation. Moreover, the solubilization effects of polar and nonpolar cosolvents on PDMS in SC-CO2 fracturing fluid were studied by comparing the binding energy, cohesive energy density and radial distribution function between solvent-solvent and between solvent-solute. The simulation results showed that cyclohexane could improve the solubility parameters of SC-CO2 the most at the same cosolvent concentration, and SC-CO2 was more uniformly distributed in the system. Meanwhile, the interactions between toluene and SC-CO2 was the strongest, and SC-CO2 was generally uniformly distributed in the system. However, ethanol and acetic acid performed poorly because they could produce hydrogen bonds with certain directionality and saturation. It was revealed that the mechanism of using cosolvents to improve the solubility of PDMS in SC-CO2 was based on the equilibrium of intermolecular forces between CO2 and PDMS, between CO2 and cosolvent, and between PDMS and cosolvent. When the siloxane-based tackifier was a nonpolar material, cyclohexane was recommended as the cosolvent. If the siloxane-based tackifier itself had some weak polarity, toluene was more suitable.

Production, Types, and Applications of Activated Carbon Derived from Waste Tyres: An Overview

Storage of waste tyres causes serious environmental pollution and health issues, especially when they are left untreated in stockpiles and landfills. Waste tyres could be subjected to pyrolysis and activation in order to produce activated carbon, which is an effective adsorbent, and can find various applications, such as for wastewater treatment, removal of metals and dyes, energy storage devices, electrode materials, etc. Activated carbon (AC) is a non-polar and non-graphite material having high porosity and excellent adsorption capabilities, making it one of the most frequently used adsorbents in various industries. It is normally produced from carbon-rich materials such as coal, coconut shells, waste tyres, biowaste, etc. The use of waste tyres for the production of AC is a sustainable alternative to conventional sources (such as coconut shells and coal) as it supports the concept of a circular economy. Since AC sourced from waste tyres is a new area, this study reviews the methods for the preparation of AC, the types of activation, the forms of activated carbon, and the factors affecting the adsorption process. This study also reviews various applications of AC derived from waste tyres, with a specific focus on the removal of different pollutants from wastewater. Activated carbon derived from the waste tyres was found to be a versatile and economically viable carbon material, which can contribute towards safeguarding the environment and human health.

High Dielectric Nonpolar Interfacial Layers Derived from Nanocellulose for Electrowetting Devices

AbstractA dielectric material is a particular type of insulator that does not conduct electricity but gets polarized when subjected to electricity, which is a crucial part of electronics such as cables, capacitors, displays, transformers, etc. Currently, synthesizing a nonpolar dielectric remains challenging. In this study, a method to make a high dielectric and nonpolar fluoropolymer and its nanocomposites based on cellulose nanocrystals (CNCs) by grafting it with nonpolar polymer 2,2,2‐trifluoroethyl methacrylate is reported. A high dielectric constant but nonpolar nanocellulose material is obtained for the first time. This material has an anisotropic arrangement of dipoles with a high polarizability effect, thereby displaying excellent dielectric properties (e.g., dielectric constant and loss: 8.59 and 0.017 at 10 kHz) and high stability (dielectric constant at 8.21 at 1 MHz). The dielectric material is miscible as an additive with other commercial fluoropolymer plastic, which demonstrates a high breakage voltage ranging from 4.6 to 9.2 kV/0.1 mm. When it is used as an interfacial layer in electrowetting display devices, it also demonstrated a low voltage driven and fast‐response effect. The excellent dielectric performances allow to develop more high‐performance dielectrics and electronics such as memories, sensors, actuators, wires, and film capacitors.

Injection-Site Sarcoma in Three Village Weaver Birds (Ploceus cucullatus) Associated with Autogenous Yersinia pseudotuberculosis Vaccination

Post-vaccinal sarcomas have been reported in cats and rarely in other domestic mammals, but not in birds. Three village weaver birds (Ploceus cucullatus) presented with poor flying ability and abnormal wing carriage attributable to large, unilateral pectoral masses. All had received at least one dose of autogenous Yersinia pseudotuberculosis vaccine into the affected pectoral muscle 74-408 days previously. Following euthanasia, gross post-mortem examination revealed locally invasive subcutaneous tumours extending through the sternum into the coelomic cavity. Cytology and histology revealed neoplasms of pleomorphic spindloid neoplastic cells with foci of coagulative necrosis and cavitation, sometimes containing faintly refractile non-polarizing granular material, both extracellularly and after phagocytosis by surrounding cells, including multinucleated giant cells. Immunohistochemistry in one bird supported a striated muscle cell origin. Findings of anaplastic sarcoma with intralesional foreign crystalline material resembled typical injection-site sarcomas in cats. This is the first report of presumptive vaccine-associated sarcoma in a non-mammalian species.