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The aim of this research is to present a method to evaluate the X-ray attenuation coefficient of (nano)particles by uniformly dispersing them in a host polymer, polydimethylsiloxane. The method is described and applied to the case of a material of interest for medical application in X-ray shielding and imaging, namely bismuth oxychloride nanoplates (BiOCl NP). A diagnostic X-ray machine was used to perform X-ray attenuation tests. A certified copper plate was used for calibration purposes and to find the X-ray photon energy. Blank polymer and composites were investigated, and the attenuation coefficient μ and the mass attenuation coefficient μ/ρ of BiOCl NPs were found to be 45 cm−1 and 6 cm2 g−1, respectively. Based on these values, a discussion is presented in which the perspective applications of BiOCl in medicine are discussed with specific focus on (i) X-ray shielding and (ii) X-ray imaging.

The development of responsive composite materials is among the most interesting challenges in contemporary material science and technology. Nevertheless, the use of highly expensive nanostructured fillers has slowed down the spread of these smart materials in several key productive sectors. Here, we propose a new piezoresistive PVA composite containing a cheap, conductive, waste-derived, cotton biochar. We evaluated the electromagnetic properties of the composites under both AC and DC regimes and as a function of applied pressure, showing promisingly high conductivity values by using over 20 wt.% filler loading. We also measured the conductivity of the waste cotton biochar from 20 K up to 350 K observing, for the first time, hopping charge transport in biochar materials.

We report on the microwave shielding efficiency of non-structural composites, where inclusions of biochar—a cost effective and eco-friendly material—are dispersed in matrices of interest for building construction. We directly measured the complex permittivity of raw materials and composites, in the frequency range 100 MHz–8 GHz. A proper permittivity mixing formula allows obtaining other combinations, to enlarge the case studies. From complex permittivity, finally, we calculated the shielding efficiency, showing that tailoring the content of biochar allows obtaining a desired value of electromagnetic shielding, potentially useful for different applications. This approach represents a quick preliminary evaluation tool to design composites with desired shielding properties starting from physical parameters.

Olive pruning is waste from olive cultivation and is generally disposed of through incineration. Olive pruning can, however, be salvaged by pyrolysis, which also produces an interesting carbon-based material known as biochar. Biochar has been proved as a suitable filler which improves the mechanical properties of epoxy composites. Despite this, literature has few studied focused on the relationship between biochar thermal history and the properties it induces in related biochar containing composites. In this work, we report a morphological analysis of biochar produced at different pyrolytic high treatment temperatures (400℃, 600℃, 800℃, and 1000℃) using different heating rates (5℃/min, 15℃/min, and 50℃/min). We investigate the effect of different biochar morphology on the biochar epoxy-related composites, proving the tuneability of the mechanical properties of composites according to the thermal history of the biochar employed.

The global market of carbon-reinforced plastic represents one of the largest economic platforms. This sector is dominated by carbon black (CB) produced from traditional oil industry. Recently, high technological fillers such as carbon fibres or nanostructured carbon (i.e. carbon nanotubes, graphene, graphene oxide) fillers have tried to exploit their potential but without economic success. So, in this chapter we are going to analyse the use of an unconventional carbon filler called biochar. Biochar is the solid residue of pyrolysis and can be a solid and sustainable replacement for traditional and expensive fillers. In this chapter, we will provide overview of the last advancement in the use of biochar as filler for the production of reinforced plastics.

In this research work, we develop a prototype that is able to convert mechanical strain into an electrical signal. To reach this scope, we evaluated the electrical properties of a thermally anneale...

Since their discovery, carbon dots (CDs) have been a promising nanomaterial in a variety of fields including nanomedicine. Despite their potential in this area, there are many obstacles to overcome for CDs to be approved for biomedical use. One major hindrance to CDs’ approval is related to their poorly defined structure. Herein a structural study of CDs is presented in order to rectify this shortcoming. The properties of three CDs which have significant promise in biomedical applications, black CDs (B-CDs), carbon nitride dots (CNDs), and yellow CDs (Y-CDs), are compared in order to develop a coherent structural model for each nanosystem. Absorption coefficients were measured for each system and this data gave insight on the level of disorder in each system. Furthermore, extensive structural characterization has been performed in order to derive structural information for each system. This data showed that B-CDs and CNDs are functionalized to a greater degree and are also more disordered and amorphous than Y-CDs. These techniques were used to develop a structural model consistent with the obtained data and what is known for carbonic nanostructures. These models can be used to analyze CD emission properties and to better understand the structure-property relationship in CDs.

In this study, self-standing and flexible Li-ion battery negative electrodes made of interconnected two-dimensional carbonized cotton fibers are developed by using a controlled pyrolysis method, and their electrochemical performance in laboratory-scale lithium-based cells is investigated at ambient temperature. By applying this binder- and current collector-free cotton-based carbon fiber electrode, both the Li+-ion intercalation and capacity decay mechanisms are explored using conventional organic carbonate-based liquid electrolyte. The cotton-based carbon fiber electrode shows excellent cycling performance and delivers a high discharge capacity in the voltage range of 0.02 - 1.2 V. The post cycling analysis of carbon fiber using HR-TEM shows the major SEI layer components formed at the surface of the active fibers during the charge/discharge process. The same electrode is used to assemble a lab-scale Li-ion full cell with high mass loading LiFePO4-based composite electrode, which demonstrates excellent cycling stability, high Coulombic efficiency and remarkable rate capability at ambient temperature.

In this research, an innovative procedure is proposed to elaborate Raman spectra obtained from nanostructured and disordered solids. As a challenging case study, biochar, a bio-derived carbon based material, was selected. The complex structure of biochar (i.e., channeled surface, inorganic content) represents a serious challenge for Raman characterization. As widely reported, the Raman spectra are closely linked to thermal treatments of carbon material. The individual contributions to the Raman spectra are difficult to identify due to the numerous peaks that contribute to the spectra. To tackle this problem, we propose a brand new approach based on the introduction, on sound theoretical grounds, of a mixed Gaussian-&ndash, Lorentzian lineshape. As per the experimental part, biochar samples were carbonized in an inert atmosphere at various temperatures and their respective spectra were successfully decomposed using the new lineshape. The evolution of the structure with carbonization temperature was investigated by Raman and XRD analysis. The results of the two techniques fairly well agree. Compared to other approaches commonly reported in the literature this method (i) gives a sounder basis to the lineshape used in disordered materials, and (ii) appears to reduce the number of components, leading to an easier understanding of their origin.

Biochar is the solid residue that is recovered after the thermal cracking of biomasses in an oxygen-free atmosphere. Biochar has been used for many years as a soil amendment and in general soil applications. Nonetheless, biochar is far more than a mere soil amendment. In this review, we report all the non-soil applications of biochar including environmental remediation, energy storage, composites, and catalyst production. We provide a general overview of the recent uses of biochar in material science, thus presenting this cheap and waste-derived material as a high value-added and carbonaceous source.

Carbon fibers (CF) were synthesized from waste clothes and treated with oxygen plasma at 100 W and 200 W for 5 min. Surface morphology and structure of the treated CF were studied via Field Emission Scanning Electron Microscopy (FESEM) and Raman spectroscopy. The functional groups on the surface of the plasma treated CF were studied through X-Ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). BET analysis showed that surface area of the fibers increases after treatment. The plasma treated CF retained higher amount of the epoxy resin in the wettability test. Composites were fabricated from untreated and treated CF in 1% and 3% by weight with epoxy resin. Mechanical and tribology behavior of the composites showed that the plasma treated CF composites are superior to their untreated counterparts. Morphology of the mechanical and the tribology specimen was studied with FESEM.

Raman spectroscopy is a very powerful tool for material analysis, allowing for exploring the properties of a wide range of different materials. Since its discovery, Raman spectroscopy has been used to investigate several features of materials such carbonaceous and inorganic properties, providing useful information on their phases, functions, and defects. Furthermore, techniques such as surface and tip enhanced Raman spectroscopy have extended the field of application of Raman analysis to biological and analytical fields. Additionally, the robustness and versatility of Raman instrumentations represent a promising solution for performing on-field analysis for a wide range of materials. Recognizing the many hot applications of Raman spectroscopy, we herein overview the main and more recent applications for the investigation of a wide range of materials, such as carbonaceous and biological materials. We also provide a brief but exhaustive theoretical background of Raman spectroscopy, also providing deep insight into the analytical achievements.

We report on the effects of thermal treatment of biochar embedded in epoxy-based composites on their microwave electrical properties, linking such properties to the material structure investigated by Raman, X-ray photoelectron spectroscopy, and X-ray diffraction. Annealing temperatures in the range 900–1500 °C and biochar concentrations in the epoxy matrix in the range from 5 to 25 wt.% were investigated. The microwave analysis, in the range from 250 MHz to 6 GHz, allowed us to determine the complex permittivity of composites and, through a proper deconvolution technique, to determine the contribution of biochar inclusions alone. High values of real permittivity (up to 220) and conductivity (up to 17 S/m) were evaluated for the biochar particles at 5 GHz, after the 1500 °C thermal treatment. A clear correlation between electrical properties and the biochar microstructure emerged from the dataset, with real permittivity and conductivity increasing as carbon inclusions transform from amorphous to nanocrystalline graphite. Conversely, the percentage of aromatic carbon has a weaker influence on the microwave properties. This study opens to the possibility of tailoring the high-frequency properties of biochar and biochar composites through proper thermal treatments.

In this work, we reported the conversion though carbothermal process of two catalysts produced by pyrolyzing exhausted coffee and waste tires. We tailored the surface with anchored iron nanoparticles through a facile carbothermal route and tested them for catalytic oxidative desulphurization of high sulphur content oil derived from tires pyrolysis. We studied their activity in a biphasic system under different conditions reaching a desulphurization of up to of 60% by using an oil with a sulphur concentration of up to 7139 ppm. The extensive characterization proved the reliability of those materials as promising catalysts for upgrading of sulphur rich drop-in fuels.

Negative emissions technologies offer an important tool to limit the global warming to

Worldwide consumption of coffee exceeds 11 billion tons/year. Used coffee grounds end up as landfill. However, the unique structural properties of its porous surface make coffee grounds popular for the adsorption of gaseous molecules. In the present work, we demonstrate the use of coffee grounds as a potential and cheap source for biochar carbon. The produced coffee ground biochar (CGB) was investigated as a sensing material for developing humidity sensors. CGB was fully characterized by using laser granulometry, X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and the Brunnauer Emmett Teller (BET) technique in order to acquire a complete understanding of its structural and surface properties and composition. Subsequently humidity sensors were screen printed using an ink-containing CGB with polyvinyl butyral (PVB) acting as a temporary binder and ethylene glycol monobutyral ether, Emflow, as an organic vehicle so that the proper rheological characteristics were achieved. Screen-printed films were the heated at 300℃ in air. Humidity tests were performed under a flow of 1.7 L/min in the relative humidity range 0&ndash, 100% at room temperature. The initial impedance of the film was 25.2 0.15 MΩ which changes to 12.3 MΩ under 98% humidity exposure. A sensor response was observed above 20 % relative humidity (RH). Both the response and recovery times were reasonably fast (less than 2 min).

Bioderived scaffolds are largely used as template for the synthesis of drugs and materials. Among biomass sources, cellulose has been used as platform for numerous conversions and applications. In this study, we report the use of crystalline microstructured cellulose as feedstock for microstructured carbon production. Different morphologies were produced according to pyrolytic conditions ranging from sphere, needle and carbon-on-carbon-decorated surfaces. All the materials were characterized using spectroscopic techniques (i.e., Raman, FTIR), FESEM and thermogravimetric analysis. Hypothetical reaction pathways were proposed for describing materials shape and properties. In particular, for cellulose nanocrystals, the thermal treatments induced noteworthy electrical properties that could be applied for the production of conductive composites.

Production of versatile composites is a very attractive field. Carbon containing epoxy resins are one of the most relevant reinforced plastics used for a wide number of applications. In this research, we studied the influence of five different commercial biochar samples for the selective enhancement of brittleness and ductility of an epoxy based composite. We proved the relationship between biochar morphology and composites mechanical properties with the aid of FT-IR and FE-SEM analysis. We were able to improve the neat resin mechanical properties by doubling its Young&rsquo, s modulus and ultimate tensile strength using a wheat straw derived material, and to increase its elongation by 40%, we used a Miscanthus derived biochar.

A novel microstructure of graphite-Si-SiC ceramics was successfully prepared by liquid silicon infiltration of graphite-based preforms; instead of using conventional methods, the reactive infiltration process was assisted by microwaves. The effects of microwave power variation on the microstructure and the mechanical properties of infiltrated materials were studied. X-ray diffraction and Raman investigations showed the presence of both unreacted graphite and Si in addition to SiC formed at their interface. The graphitic and silicon phases were separated by a SiC network, which results more homogeneous as microwave power was increased. The amount of SiC was found to be higher in function of the growing power level; a higher conversion of graphite into SiC yielded a more dense material. The bending strength measurements confirm this, showing higher values for the samples processed using a power level of 75% of the full power compared to those obtained with 30% and 60%.

Carbon nanotubes (CNTs) demonstrate remarkable conductive behaviour, which suggests promising applications. Their outstanding properties have been used in the development of CNT–polymer composites as possible alternative materials for various applications, such as flexible electrodes, antistatic coatings and piezoresistive sensors. In our study we focused our attention on the evaluation and modelling of CNT-filled epoxy resin electrical conductivity. We discuss the results with regard to the influence of CNTs dimensions and content. Exploiting the Dijkstra algorithm, we implemented a simulation code which determines the shortest route between electrodes in the polymer. The longer the path inside the polymer, the more non-conductive the composite becomes, since polymer resistivity is orders of magnitude higher than that of CNTs. We compared these simulated results with experimental data obtained at several wt% and found a good correspondence between modelling and experimental results.

Carbon nano materials (CNMs) from waste polyethylene bags were synthesized in two different morphologies namely carbon nano beads (P1) and a mix of carbon nano tubes and carbon nano beads (P2) using chemical vapour deposition (CVD) technique. Morphology of the CNMs were studied through field emission scanning electron microscope (FESEM) and the purity through thermogravimetric analysis (TGA) and Raman spectroscopy. Epoxy composites were produced using these CNMs as filler in 1% and 3% by weight. Mechanical properties and tribological properties were compared with the composites of commercial Multi Walled Carbon Nano Tubes (MWCNT). It is observed that the in house generated CNMs composites show overall better mechanical and tribology properties compared to the blank epoxy and the commercial MWCNTs based composites. Morphology of the composites was analysed through FESEM to study the interaction of the filler with the matrix that lead to improved performances.

In recent years, low-cost carbons derived from recycled materials have been gaining attention for their potentials as filler in composites and in other applications. The electrical and mechanical properties of polymer composites can be tuned using different percentages and different kind of fillers: either low-cost (e.g., carbon black), ecofriendly (e.g., biochar), or sophisticated (e.g., carbon nanotubes). In this work, the mechanical and electrical behavior of composites with biochar and multiwall carbon nanotubes dispersed in epoxy resin are compared. Superior mechanical properties (ultimate tensile strength, strain at break) were noticed at low heat-treated biochar (concentrations 2–4 wt %). Furthermore, dielectric properties in the microwave range comparable to low carbon nanotubes loadings can be achieved by employing larger but manageable amounts of biochar (20 wt %), rending the production of composites for structural and functional application cost-effective.

Carbon nanotubes (CNTs), a rather fascinating material, are among the pillars of nanotechnology. CNTs exhibit unique electrical, mechanical, adsorption, and thermal properties with high aspect ratio, exceptional stiffness, excellent strength, and low density, which can be exploited in the manufacturing of revolutionary smart nano composite materials. The demand for lighter and stronger polymer composite material in various applications is increasing every day. Among all the possibilities to research and exploit the exceptional properties of CNTs in polymer composites we focused on the reinforcement of epoxy resin with different types of multiwalled carbon nano tubes (MWCNTs). We studied mechanical properties such as stress, strain, ultimate tensile strength, yield point, modulus and fracture toughness, and Young's modulus by plotting and calculating by means of the off-set method. The mechanical strength of epoxy composite is increased intensely with 1 and 3 wt.% of filler.

In this work we present a systematic study of the effects of high temperature treatments on the macroscopic physical and mechanical properties of millimeters thick layers of self-standing vertically aligned multi wall carbon nanotubes (MWCNTs). Annealing treatments were carried out on pristine MWCNT chunks in argon gas, in the temperature range of 1500–2200 °C. The analysis showed a change in most of the physical properties as an effect of the graphitization process. Raman results showed a monotonic increase in the crystallite size as the annealing temperature increases due to the lattice defect removal kinetic. Improvement in thermal stability exhibited by thermo-gravimetric analysis in oxidative environment witness a significant reduction in defectiveness. X-ray diffraction confirmed a higher degree of ordering after the annealing process and indicated no significant re-arrangement of the interlayer spacing between the graphene shells. Loading tests showed, beside a negligible change of maximum load, an increase in elastic modulus proportional to the annealing temperature.

We report about the electron paramagnetic resonance and nuclear magnetic resonance signals in bulk and thin film-type ultrananocrystalline diamond with and without nitrogen. The localization and nature of defects for powder and compact film samples were analyzed. From the analysis of spin–lattice and spin–spin relaxation times, we have found that spin states sit in sp2 enriched region belonging to the grain boundaries.

The vast majority of stent thrombosis occurs in the acute and sub-acute phases and is more common in patients with acute coronary syndromes, due to the thrombotic milieu where stent struts are positioned. Stent thrombosis is likely due to incomplete tissue coverage of metallic stents as the contact between metallic stents and blood elements may lead to platelet adhesion and trigger vessel thrombosis. If a stent is covered after 7 days, the risk that it will be found uncovered at later stages is very low (

We report a study on a thermal chemical vapor deposition (CVD) system optimized for the growth of well-packed and almost vertically aligned carbon nanotubes (CNTs) on uncoated silicon substrates. The process involves the thermal cracking in inert atmosphere of a reagent vapor previously produced by co-evaporation of a solid mixture composed by a carbon source (camphor) and a catalyst precursor (ferrocene). Besides the formation of CNTs and depending on the deposition parameters and in particular on the temperature, other carbon nanostructures such as nanographite can be deposited. We have investigated the correlation between growth rate of the carbon material and the development of secondary transversal vortex flows caused by the effects of temperature gradient inside the deposition system. The production of porous carbonaceous crust rich in iron particles on the top of very thick CNT mats is explained by the irregular co-evaporation of the two reagents correlated with the difference of vapor pressure of camphor and ferrocene.

We report a study of hydrogen adsorption experiment on SWNT samples deposited by chemical vapor deposition (CVD) and investigated with Electron Spin Resonance spectroscopy (ESR) before and after hydrogen treatment. The ESR investigation was performed at room and low temperature (4–30 K). We found that ESR technique is very useful to investigate paramagnetic centers and their interaction with hydrogen. The morphology and structure of the samples were characterized by Micro-Raman spectroscopy. Subsequently the thermal stability was investigated by thermogravimetric analysis (TGA) testing. Brunauer Emmett Teller (BET) analysis was used to calculate the specific surface area and porosity of the as grown samples. All characterizations showed a small presence of residual Fe impurity (3.3 wt.%).

We report a study on a thermal chemical vapor deposition (CVD) system optimized for the growth of well packed and vertically aligned carbon nanotubes (CNTs) on uncoated silicon substrates. The process of synthesis involves the co-evaporation of a carbon precursor and a metal catalyst in a nitrogen atmosphere inside a high temperature furnace. Beside the formation of CNTs, depending in particular on the deposition temperature, other carbon structures can be deposited, such as nanographite. We show the growth results analyzed by different characterization techniques (electron microscopy, porosity and thermal stability investigations, micro-Raman spectroscopy). In addition, we report an investigation on the development of secondary transversal vortex flows caused by the effects of distribution of temperatures inside the growth system, in order to correlate them with the growth results.Copyright © 2006 by ASME

During Carbon Fibre Reinforced Polymers (CFRPs) manufacturing, large quantities of scrap are being produced and usually disposed to landfill or incinerated, resulting in a high environmental impact. Furthermore, CFRP parts that have been damaged or reached their end-of-life, follow the same disposal route and because of this, not only the environment is affected, but also high added-value materials, such as carbon fibres (CFs) are lost without further valorisation. Several recycling technologies have been suggested, such as pyrolysis, to retrieve the CF reinforcement from the CFRPs. However, pyrolysis produces CFs that have residual resin and pyrolytic carbon at their surface. In order to retrieve clean long fibres, oxidation treatment in high temperatures is required. The oxidation treatment, however, has a high impact on the mechanical properties of the reclaimed CFs; therefore, an optimised pyrolysis procedure of CFRPs and post-pyrolysis treatment of reclaimed fibres (rCFs) is required. In this study, CFRPs have been subjected to pyrolysis to investigate the reclamation of CF fabrics in their primal form. The temperature of 550 °C was selected as the optimum processing temperature for the investigated composites. A parametric study on the post-pyrolysis treatment was performed in order to remove the residues from the fabrics and at the same time to investigate the CFs reusability, in terms of their mechanical and surface properties.