Assessment of Graphene Oxide and Nanoclay Based Hybrid Filler in Chlorobutyl-Natural Rubber Blend for Advanced Gas Barrier Applications

Nanomaterials have engaged response from the scientific world in recent decades due to their exceptional physical and chemical properties counter to their bulk. They have been widely used in a polymer matrix to improve mechanical, thermal, barrier, electronic and chemical properties. In rubber nanocomposites, nanofillers dispersion and the interfacial adhesion between polymer and fillers influences the composites factual properties. In the present work, a comparison of the hybrid effects of carbon black with two different nanofillers (graphene oxide and nanoclay) was studied. The 70/30 composition of chlorobutyl rubber/natural rubber elastomer blend was taken as per the blend composition optimized from our previous studies. The hybrid effects of graphene oxide and nanoclay in dispersing the nanofillers were studied mainly by analyzing nanocomposite barrier properties. The results confirm that the combined effect of carbon black with graphene oxide and nanoclay could create hybrid effects in decreasing the gas permeability. The prepared nanocomposites which partially replace the expensive chlorobutyl rubber can be used for tyre inner liner application. Additionally, the reduction in the amount of carbon black in the nanocomposite can be an added advantage of considering the environmental and economic factors.

Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Organoclay nanoparticles (Cloisite^® C10A, Cloisite^® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

Comparative Study of Gold and Carbon Nanoparticles in Nucleic Acid Lateral Flow Assay

A lateral flow assay (LFA) is a paper-based, point-of-need test designed to detect a specific analyte in complex samples in low-resource settings. Although LFA has been successfully used in different applications, its use is still limited when high sensitivity is required, especially in the diagnosis of an early-stage condition. The limit of detection (LOD) is clearly related to the signal-generating system used to achieve the visual readout, in many cases involving nanoparticles coupled to a biomolecule, which, when combined, provides sensitivity and specificity, respectively. While colloidal gold is currently the most-used label, other detection systems are being developed. Carbon nanoparticles (CNPs) demonstrate outstanding features to improve the sensitivity of this technology by producing an increased contrast in the paper background. Based on the necessity of sensitivity improvement, the aim of this work is a comparative study, in terms of analytical performance, between commercial streptavidin gold nanoparticles (streptAv-AuNPs) and avidin carbon nanoparticles (Av-CNPs) in a nucleic acid lateral flow assay. The visual LOD of the method was calculated by serial dilution of the DNA template, ranging from 0.0 to 7 pg μL-1/1.5 × 104 CFU mL-1). The LFA achieved visual detection of as low as 2.2 × 10-2 pg μL-1 using Av-CNPs and 8.4 × 10-2 pg μL-1 using streptAv-AuNPs. These LODs could be obtained without the assistance of any instrumentation. The results demonstrate that CNPs showed an increased sensitivity, achieving the nanomolar range even by visual inspection. Furthermore, CNPs are the cheapest labels, and the suspensions are very stable and easy to modify.

Capacitive Humidity Sensor Based on Carbon Black/Polyimide Composites

A novel capacitive humidity sensor based on carbon black/polyimide composites is presented in this paper. The details of the fabrication, sensor characteristics, and effect of the carbon black additive are described. It was confirmed that the polyimide composite filled with a tiny amount of carbon black was suitable for a humidity sensing dielectric. The humidity sensors with three different dielectrics, which were pure polyimide, 0.01 wt% carbon black/polyimide, and 0.05 wt% carbon black/polyimide, were fabricated by a micro-electro-mechanical-system (MEMS) process. As the amount of the carbon black additive increased, the sensitivity of the humidity sensor increased. The humidity sensor with 0.05 wt% of carbon black had a much higher sensitivity of 15.21% (20–80% RH, 0.2535%/% RH) than that of the sensor with pure polyimide, which was 9.73% (0.1622%/% RH). The addition of carbon black also led to an enhancement in the hysteresis and response speed. The hysteresis of the humidity sensor decreased from 2.17 to 1.80% when increasing the amount of the carbon black additive. The response speed of the humidity sensor with 0.05 wt% of carbon black was measured to be ~10% faster than that of the sensor with pure polyimide. The long-term stability of the humidity sensors was demonstrated as well.

Use of Surface Penetration Technology to Fabricate Superhydrophobic Multifunctional Strain Sensors with an Ultrawide Sensing Range

Flexible sensors with wide sensing ranges require responsiveness under tiny and large strains. However, the development of strain sensors with wide detection ranges is still a great challenge due to the conflict between the tiny strain requirements of sparse conductive networks and the large strain requirement of dense conductive networks. Herein, we present a facile method for fabricating a gradient conductive network composed of sparse and dense conductive networks. The surface penetration technology in which carbon black (CB) penetrated from the natural rubber latex (NRL) glove surface to the interior was used to fabricate a gradient conductive network. The prolonged immersion time from 1 to 30 min caused the penetration depth of CB to increase from 2 to 80 μm. Moreover, CB formed hierarchical rough micro- and nanoscale structures, creating a superhydrophobic surface. The gradient conductive network of sensors produced an ultrawide detection range of strain (0.05-300%) and excellent reliability and reproducibility. The sensors can detect a wide range of human motions, from tiny (wrist pulse) to large (joint movements) motion monitoring. The flexible sensors attached to a flexible basement can be used to detect pressure in a wide detection range (1.7-2900 kPa). Pressure responsiveness was used to detect the weight, sound pressure, and dripping of tiny droplets. The sensor showed an excellent response to organic solvents, and the response intensity increased with the increasing swelling degree of the solvent for NRL.

Laser Transmission Welding of Semi-Crystalline Polymers and Their Composites: A Critical Review

The present review provides an overview of the current status and future perspectives of one of the smart manufacturing techniques of Industry 4.0, laser transmission welding (LTW) of semi-crystalline (SC) polymers and their composites. It is one of the most versatile techniques used to join polymeric components with varying thickness and configuration using a laser source. This article focuses on various parameters and phenomena such as inter-diffusion and microstructural changes that occur due to the laser interaction with SC polymers (specifically polypropylene). The effect of carbon black (size, shape, structure, thermal conductivity, dispersion, distribution, etc.) in the laser absorptive part and nucleating agent in the laser transmissive part and its processing conditions impacting the weld strength is discussed in detail. Among the laser parameters, laser power, scanning speed and clamping pressure are considered to be the most critical. This review also highlights innovative ideas such as incorporating metal as an absorber in the laser absorptive part, hybrid carbon black, dual clamping device, and an increasing number of scans and patterns. Finally, there is presented an overview of the essential characterisation techniques that help to determine the weld quality. This review demonstrates that LTW has excellent potential in polymer joining applications and the challenges including the cost-effectiveness, innovative ideas to provide state-of-the-art design and fabrication of complex products in a wide range of applications. This work will be of keen interest to other researchers and practitioners who are involved in the welding of polymers.

Electromagnetic Interference Shielding and Physical-Mechanical Characteristics of Rubber Composites Filled with Manganese-Zinc Ferrite and Carbon Black

In the present work, composite materials were prepared by incorporation of manganese-zinc ferrite, carbon black and combination of ferrite and carbon black into acrylonitrile-butadiene rubber (NBR). For cross-linking of composites, standard sulfur-based curing system was applied. The main goal was to investigate the influence of the fillers on the physical-mechanical properties of composites. Then, the electromagnetic absorption shielding ability was investigated in the frequency range 1 MHz-3 GHz. The results revealed that composites filled with ferrite provide sufficient absorption shielding performance in the tested frequency range. On the other hand, ferrite behaves as an inactive filler and deteriorates the physical-mechanical characteristics of composites. Carbon black reinforces the rubber matrix and contributes to the improvement of physical-mechanical properties. However, composites filled with carbon black are not able to absorb electromagnetic radiation in the given frequency range. Finally, the combination of carbon black and ferrite resulted in the modification of both physical-mechanical characteristics and absorption shielding ability of hybrid composites.

Nature of Carbon Black Reinforcement of Rubber: Perspective on the Original Polymer Nanocomposite

Adding carbon black (CB) particles to elastomeric polymers is essential to the successful industrial use of rubber in many applications, and the mechanical reinforcing effect of CB in rubber has been studied for nearly 100 years. Despite these many decades of investigations, the origin of stiffness enhancement of elastomers from incorporating nanometer-scale CB particles is still debated. It is not universally accepted whether the interactions between polymer chains and CB surfaces are purely physical adsorption or whether some polymer-particle chemical bonds are also introduced in the process of mixing and curing the CB-filled rubber compounds. We review key experimental observations of rubber reinforced with CB, including the finding that heat treatment of CB can greatly reduce the filler reinforcement effect in rubber. The details of the particle morphology and surface chemistry are described to give insights into the nature of the CB-elastomer interfaces. This is followed by a discussion of rubber processing effects, the influence of CB on crosslinking, and various chemical modification approaches that have been employed to improve polymer-filler interactions and reinforcement. Finally, we contrast various models that have been proposed for rationalizing the CB reinforcement of elastomers.

The Tensile Behaviour of Highly Filled High-Density Polyethylene Quaternary Composites: Weld-Line Effects, DIC Curiosities and Shifted Deformation Mechanisms

The interactive effects between additives and weld lines, which are frequent injection-moulding defects, were studied in high-density polyethylene (HDPE) and compared to weld-line-free reference samples. These materials were formulated around a D- and I-optimal experimental design, based on a quadratic Scheffé polynomial model, with up to 60 wt% calcium carbonate, masterbatched carbon black and a stabiliser package. Where reasonable and appropriate, the behaviours of the systems were modelled using statistical techniques, for a better understanding of the underlying trends. The characterisations were performed through the use of conventional tensile testing, digital image correlation (DIC) and scanning electron microscopy (SEM). A range of complex interactive effects were found during conventional tensile testing, with DIC used to better understand and explain these effects. SEM is used to better understand the failure mechanics of some of these systems through fractography, particularly regarding particle effects. A measure is introduced to quantify the deviation of the pre-yield deformation curve from the ideal elastic case. Novel analysis of DIC results is proposed, through the use of combined time-series plots and measures quantifying the extent and localisation of peak deformation. Through this, it could be found that strong shifts in the deformation mechanisms occur as a function of formulation and the presence/absence of weld lines. Primarily, changes are noted in the onset of continuous inter- and intralamellar slip and cavitation/fibrillation, seen through the onset of localised deformation and stress-whitening.

Terahertz Shielding Properties of Carbon Black Based Polymer Nanocomposites

The majority of industry using high-speed communication systems is shifting towards higher frequencies, namely the terahertz range, to meet demands of more effective data transfer. Due to the rising number of devices working in terahertz range, effective shielding of electromagnetic interference (EMI) is required, and thus the need for novel shielding materials to reduce the electromagnetic pollution. Here, we show a study on optical and electrical properties of a series of ethylene co-butyl acrylate/carbon black (EBA/CB) composites with various CB loading. We investigate the transmittance, reflectance, shielding efficiency, absorption coefficient, refractive index and complex dielectric permittivity of the fabricated composites. Finally, we report a material that exhibits superior shielding efficiency (SE)-80 dB at 0.9 THz (14.44 vol% CB loading, 1 mm thick)-which is one of the highest SE values among non-metallic composite materials reported in the literature thus far. Importantly, 99% of the incoming radiation is absorbed by the material, significantly increasing its applicability. The absorption coefficient (α) reaches ~100 cm-1 for the samples with highest CB loading. The EBA/CB composites can be used as lightweight and flexible shielding packaging materials for electronics, as passive terahertz absorbers or as radiation shields for stealth applications.

Enhanced Physical and Mechanical Properties of Nitrile-Butadiene Rubber Composites with N-Cetylpyridinium Bromide-Carbon Black

The physical and mechanical properties of nitrile-butadiene rubber (NBR) composites with N-cetylpyridinium bromide-carbon black (CPB-CB) were investigated. Addition of 5 parts per hundred rubber (phr) of CPB-CB into NBR improved the tensile strength by 124%, vulcanization rate by 41%, shore hardness by 15%, and decreased the volumetric wear by 7% compared to those of the base rubber-CB composite.

[Effect of ERK/JNK cell signaling pathway in carbon black induced cytokine IL-6 and IL-8 expression changes]

OBJECTIVE

To investigate the roles of extracellular signal-regulated kinase(ERK)/c-Jun amino-terminal kinase(JNK) signaling pathway on the expression of interleukin-6(IL-6) and interleukin-8(IL-8) in human embryonic lung fibroblasts(HELF) induced by carbon black.

METHODS

HELFs were cultured in RPMI-1640 medium containing 0, 15, 30, 60, 120 or 240 μg/mL carbon black for 24 h, and the appropriate dose of carbon black was determined by MTT assay result HELFs were divided into three groups: HELFs, HELFs transfected with ERK dominant negative mutant plasmid(DN-ERK) and HELFs transfected with JNK dominant negative mutant plasmid(DN-JNK). 100 μg/mL carbon black was used to treat HELFs(CB), DN-ERK HELFs(CB-DN-ERK), DN-JNK HELFs(CB-DN-JNK), and HELFs without any black carbon treatment were considered as control group. At 16 h after carbon black treatment, scanning electron microscope(SEM) was used to observe HELFs morphology and whether there were carbon black particless. At 0, 1, 2, 4, 8, 12, 24 and 36 h, the enzyme linked immunosorbent assay(ELISA) was used to detect CB and control groups HELFs IL-6 and IL-8 expression levels, whereas CB-DN-ERK and CB-DN-JNK HELFs were detected only at 24 h.

RESULTS

SEM result showed no carbon black particles were observed in CB group HELFs, whereas their surface projections were increased. The CB group HELFs IL-6 expression levels at 2 h(44. 86±3. 65 ng/L) and 4 h(76. 52±3. 15 ng/L) were significantly lower than those of the control group(96. 78±2. 82 and 147. 32±3. 26 ng/L)(P<0. 05), whereas the IL-6 expression levels were significantly higher than those of the control group(105. 54±6. 10, 101. 27±5. 84 and 97. 15±5. 12 ng/L) at 16 h(202. 64±7. 20 ng/L), 24 h(200. 38±6. 20 ng/L) and 36 h(183. 54±4. 54 ng/L)(P<0. 001). At 24 h(136. 75±3. 81 ng/L) and 36 h(149. 12±2. 74 ng/L), the CB group IL-8 expression levels were significantly higher than those of the control group(75. 16±2. 84 and 73. 44±2. 15 ng/L)(P<0. 001). Compared with CB group HELFs, CB-DN-ERK and CB-DN-JNK groups HELFs had significantly lower IL-6 and IL-8 expression levels(P<0. 05).

CONCLUSION

While carbon black induced HELFs IL-6 and IL-8 expression levels changes, ERK and JNK may upregulate IL-6 and IL-8 expression levels.

Highly Sensitive Levodopa Determination by Means of Adsorptive Stripping Voltammetry on Ruthenium Dioxide-Carbon Black-Nafion Modified Glassy Carbon Electrode

A new, highly sensitive Adsorptive Stripping Voltammetric method for levodopa determination was developed. As a working electrode, the glassy carbon electrode (GCE) modified with carbon black (CB), RuO2·xH2O (RuO2) and Nafion was used (CB-RuO2-Nafion GCE). Levodopa signal obtained on the modified electrode was 12 times higher compared to GCE. During research, instrumental parameters were optimized: sampling time ts = 10 ms, waiting time tw = 10 ms, step potential Es = 5 mV and pulse amplitude ΔE = 50 mV. Preconcentration potential Eprec was equal to 0 mV. The best results were obtained in 0.025 M perchloric acid (approx. pH 1.4). Signal repeatability measured on the CB-RuO2-Nafion modified electrode for 0.2 µM of levodopa was equal to 2.1% (levodopa concentration 1 µM, n = 5). Linearity of the method was achieved in the concentration range from 1 to 8 µM. Limit of detection was equal to 17 nM. Recoveries calculated for pharmaceutical products and tap water measurements were in the range 102-105%, which confirms the accuracy of the developed. The applicability of the method was confirmed by analysis of pharmaceutical products and tap water samples. Based on obtained results, it might be concluded that the developed voltammetric method could be a useful tool in routine drug analysis.

Repeatability and reproducibility of the color contrast technique for fingermark age estimation applications

This research complements previous studies in which color contrast between ridges and furrows of latent fingermarks was investigated as a potential aging parameter. In this case, the robustness of the technique has been tested by including five female and five male donors who deposited sebaceous-rich latent fingermarks onto ceramic tile and polystyrene plastic as well as flat and rolled inked fingerprints on commercially available ten-print cards. Fresh latent fingermarks were visualized with either carbon black or titanium dioxide powder (TiO₂ ) and inked fingerprints were imprinted in succession without re-charging ink. The mean intensity (MI) and intensity amplitude (IA) metrics of the color histogram were collected from each image for statistical analyses. The goals were to detect any differences within and between the analysts' own interpretation of the protocol as well as examine how color contrast may be influenced by donor, substrate, biological sex, powder type, and the quantity of ink deposited. Results show that the color contrast metrics (MI and IA) are repeatable and reproducible and not affected significantly by donor, sex, deposition pressure, or distortion. However, the metrics were sufficiently sensitive to distinguish substrate and powder types and to detect different quantities of ink. The statistical analyses confirm and expand upon previous observations regarding the reliability of MI and IA as metrics that could eventually be used to estimate the age of a latent fingermark. At the same time, it was revealed that the technique needs further improvement and standardization by including a universal "white color standard" to conduct image comparisons.

Effect of Melt-Compounding Protocol on Self-Aggregation and Percolation in a Ternary Composite

A ternary composite of poly(lactic acid) (PLA), poly(caprolactone) (PCL), and carbon black (CB) shows the PCL-induced CB self-aggregation and percolation formation when the amount of the PCL phase as the secondary phase is as small as the amount of CB. Furthermore, when the drop size of the PCL phase becomes smaller, the ternary composite forms a percolation of high order structure, resulting in a remarkable enhancement of the electrical conductivity (~4 × 10^-2 S/m with 4 wt.% CB). To further control the percolation structure, the composite fabrication is controlled by splitting a typical single-step mixing process into two steps, focusing on the dispersion of the secondary PCL phase and the CB particles separately. Under the single-step mixing protocol, the ternary composite shows a structure with greater CB aggregation in the form of a high aspect ratio and large aggregates (aggregate perimeter~aggregate size 0.7). Meanwhile, the two-step mixing process causes the CB aggregates to expand and create a higher structure (aggregate perimeter~aggregate size 0.8). The reduced size of the secondary phase under a mixing condition with high shear force prior to the addition of CB provides a larger interfacial area for CB to diffuse into the PCL phase during the subsequent mixing step, resulting in a further expansion of CB aggregation throughout the composite. The particle percolation of such a high order structure is attributed to high storage modulus (G'), high Young's modulus, high dielectric loss (ε″), and negative-positive switching of dielectric constant at high frequency (of 103 Hz) of composite.

Enhanced Piezoelectric Properties of Poly(Vinylidenefluoride-Co-Trifluoroethylene)/Carbon-Based Nanomaterial Composite Films for Pressure Sensing Applications

In this study, heat and polarization treatments were applied to poly(vinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) films to improve their crystallinity and piezoelectric effect. Carbon-based nanomaterials (CBNs) of multiple dimensions (i.e., modified zero-dimensional (0D) carbon black (OCB), one-dimensional (1D) modified carbon nanotubes (CNT–COOH) and two-dimensional (2D) graphene oxide (GO)) were added to the copolymer to study the effects of different CBN dimensions on the crystallinity and piezoelectric effect of PVDF-TrFE films. Additionally, amphiphilic polymeric dispersants were added to improve the dispersibility of CBNs; the dispersant was synthesized by the amidation, and imidization reactions of styrene-maleic anhydride copolymer (SMAz) and polyoxyalkylene amine (M1000). Polymer solutions with different ratios of CBN to dispersant (z = 10:1, 5:1, 1:1, 1:5, 1:10) were prepared. The enhanced dispersibility enabled the fluorine atoms in the PVDF-TrFE molecular chain to more efficiently form hydrogen bonds with the –COOH group in the CBN, thereby increasing the content of the β crystal phase (the origin of the piezoelectric effect) of the film. Therefore, the resulting film exhibited a higher output voltage on the application side and better sensitivity on the sensing element. The addition of CNT–COOH and polymeric dispersants increased the β-phase content in PVDF-TrFE from 73.6% to 86.4%, which in turn raised the piezoelectric coefficient from 19.8 ± 1.0 to 26.4 ± 1.3 pC/N. The composite film-based pressure sensor also exhibited a high degree of sensitivity, which is expected to have commercial potential in the future.

Evaluation of latent fingermark color contrast as aging parameter under different environmental conditions: A preliminary study

This research expands previous studies in which color contrast between ridges and furrows of powder-enhanced latent fingermarks was explored as a possible aging parameter. The main goal is to test the sensitivity of the technique across a predetermined set of factors. In this case, experiment factors have included two donors who deposited sebaceous- and eccrine-rich fingermarks onto ceramic tile and polystyrene plastic. These were developed with either black carbon or titanium dioxide powder (TiO₂ ) over eight time periods (0-72 days) and aged under three light conditions (direct light, shade, and darkness). The mean intensity (MI) and intensity amplitude (IA) metrics of color were collected from each image for statistical analyses. Results show that color contrast is affected significantly by substrate, secretion, and powder types, with an interaction effect between the substrate and powder type on both MI and IA metrics. The degree of light exposure did not have a noticeable impact on distinguishing aging patterns of fingermarks by neither powder methods. Different aging patterns were detected between sebaceous-rich and their eccrine-rich counterparts for all light conditions using regression analysis. All eccrine-rich fingermarks exhibited little (or minimal) change in IA over time, whereas sebaceous-rich samples showed varied patterns, from significant decreases to slight increases. These findings confirm and expand previous observations on the potential use of MI and IA as metrics to study latent fingermark degradation patterns that could eventually be used to estimate the age of a fingermark.

Effect of the Topology of Carbon-Based Nanofillers on the Filler Networks and Gas Barrier Properties of Rubber Composites

The topology of nanofillers is one of the key factors affecting the gas barrier properties of rubber composites. In this research, three types of carbon-based nanofillers, including spherical carbon black (CB), fibrous carbon nanotubes (CNTs), and layered graphene (GE) were chosen to investigate the effect of the topological structures of nanofillers on the gas barrier properties of styrene-butadiene rubber (SBR) composites. Results showed that the structure and strength of the filler networks in SBR composites were closely associated with the topology of nanofillers. When filled with 35 phr CB, 8 phr CNTs, and 4 phr GE, the SBR composites had the same strength of the filler network, while the improvement in gas barrier properties were 39.2%, 12.7%, and 41.2%, respectively, compared with pure SBR composites. Among the three nanofillers, GE exhibited the most excellent enhancement with the smallest filler content, demonstrating the superiority of two-dimensional GE in improving the barrier properties of rubber composites.

Synthesis of Nylon 6/Modified Carbon Black Nanocomposites for Application in Uric Acid Adsorption

High uric acid levels cause different clinic conditions. One of them is hyperuricemia, which leads to kidney damage. A solution for eliminating uric acid in the blood is by hemodialysis, which is performed using nanocomposite membranes. In this work, Nylon 6 nanocomposites were synthesized with modified carbon black (MCB), which were considered candidate materials for hemodialysis membranes. The modification of carbon black was made with citric acid using the variable-frequency ultrasound method. The new MCB was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), and dispersion tests. Nylon 6/MCB nanocomposites were processed using the ultrasound-assisted melt-extrusion method to improve the dispersion procedure of the nanoparticles. The Nylon 6/MCB nanocomposites were characterized by FTIR, TGA, and differential scanning calorimetry (DSC). These were assessed for the absorption of toxins and hemocompatibility. MBC and nanocomposites showed excellent uric acid removal (78-82%) and hemocompatibility (1.6-1.8%). These results suggest that Nylon 6/MCB nanocomposites with low loading percentages can be used on a large scale without compatibility problems with blood.

Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors

The design of flexible sensors which can be incorporated in textile structures is of decisive importance for the future development of wearables. In addition to their technical functionality, the materials chosen to construct the sensor should be nontoxic, affordable, and compatible with future recycling. Conductive fibres were produced by incorporation of carbon black into regenerated cellulose fibres. By incorporation of 23 wt.% and 27 wt.% carbon black, the surface resistance of the fibres reduced from 1.3 × 1010 Ω·cm for standard viscose fibres to 2.7 × 103 and 475 Ω·cm, respectively. Fibre tenacity reduced to 30-50% of a standard viscose; however, it was sufficient to allow processing of the material in standard textile operations. A fibre blend of the conductive viscose fibres with polyester fibres was used to produce a needle-punched nonwoven material with piezo-electric properties, which was used as a pressure sensor in the very low pressure range of 400-1000 Pa. The durability of the sensor was demonstrated in repetitive load/relaxation cycles. As a regenerated cellulose fibre, the carbon-black-incorporated cellulose fibre is compatible with standard textile processing operations and, thus, will be of high interest as a functional element in future wearables.

Facile and Low-Cost SPE Modification Towards Ultra-Sensitive Organophosphorus and Carbamate Pesticide Detection in Olive Oil

Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organophosphorus pesticides is presented that is based on acetylcholinesterase (AChE) immobilized on commercially available screen-printed carbon electrodes (SPEs) modified with carbon black (CB), as a means to enhance their conductivity. Most interestingly, two different methodologies to deposit the enzyme onto the sensor surfaces were followed; strikingly different results were obtained depending on the family of pesticides under investigation. Furthermore, and towards the uniform application of the functionalization layer onto the SPEs’ surfaces, the laser induced forward transfer (LIFT) technique was employed in conjunction with CB functionalization, which allowed a considerable improvement of the sensor’s performance. Under the optimized conditions, the fabricated sensors can effectively detect carbofuran in a linear range from 1.1 × 10⁻⁹ to 2.3 × 10⁻⁸ mol/L, with a limit of detection equal to 0.6 × 10⁻⁹ mol/L and chlorpyrifos in a linear range from 0.7 × 10⁻⁹ up to 1.4 × 10⁻⁸ mol/L and a limit of detection 0.4 × 10⁻⁹ mol/L in buffer. The developed biosensor was also interrogated with olive oil samples, and was able to detect both pesticides at concentrations below 10 ppb, which is the maximum residue limit permitted by the European Food Safety Authority.

Synthesis of Vanadium Carbide by Mechanical Activation Assisted Carbothermic Reduction

Vanadium carbide is known, for its hardness and other unique properties, as a refractory material. The synthesis of vanadium carbide is always associated with the utilization of expensive active metals, such as aluminum, calcium and magnesium, as a reducing agent to extract the vanadium metal from its corresponding oxide, followed by carbidization. The carbidization of reduced vanadium requires a complicated process and elevated temperature. Mechanical activation to synthesize vanadium carbide from its corresponding oxide and carbon source represents a promising, straightforward and less energy-intensive route. In the present study, vanadium carbide is synthesized by the carbothermic reduction of a mechanically activated mixture of V₂O₅ and carbon black as reducing agents without any additives. The reduction process is monitored by means of thermogravimetric analysis. The reduction products are characterized by X-ray diffraction and field emission scanning electron microscope. It is found that V₈C₇ with an average crystallite size of 88 nm can be synthesized from a V₂O₅-C mixture after milling for 15 h and further heating at 1050 °C for 1 h in an inert atmosphere.

A Case Study of Waste Scrap Tyre-Derived Carbon Black Tested for Nitrogen, Carbon Dioxide, and Cyclohexane Adsorption

Waste scrap tyres were thermally decomposed at the temperature of 600 °C and heating rate of 10 °C·min^-1. Decomposition was followed by the TG analysis. The resulting pyrolytic carbon black was chemically activated by a KOH solution at 800 °C. Activated and non-activated carbon black were investigated using high pressure thermogravimetry, where adsorption isotherms of N₂, CO₂, and cyclohexane were determined. Isotherms were determined over a wide range of pressure, 0.03-4.5 MPa for N₂ and 0.03-2 MPa for CO₂. In non-activated carbon black, for the same pressure and temperature, a five times greater gas uptake of CO₂ than N₂ was determined. Contrary to non-activated carbon black, activated carbon black showed improved textural properties with a well-developed irregular mesoporous-macroporous structure with a significant amount of micropores. The sorption capacity of pyrolytic carbon black was also increased by activation. The uptake of CO₂ was three times and for cyclohexane ten times higher in activated carbon black than in the non-activated one. Specific surface areas evaluated from linearized forms of Langmuir isotherm and the BET isotherm revealed that for both methods, the values are comparable for non-activated carbon black measured by CO₂ and for activated carbon black measured by cyclohexane. It was found out that the N₂ sorption capacity of carbon black depends only on its specific surface area size, contrary to CO₂ sorption capacity, which is affected by both the size of specific surface area and the nature of carbon black.

Ozone Reacts With Carbon Black to Produce a Fulvic Acid-Like Substance and Increase an Inflammatory Effect

Exposure to ambient ozone has been associated with increased human mortality. Ozone exposure can introduce oxygen-containing functional groups in particulate matter (PM) effecting a greater capacity of the particle for metal complexation and inflammatory effect. We tested the postulate that (1) a fulvic acid-like substance can be produced through a reaction of a carbonaceous particle with high concentrations of ozone and (2) such a fulvic acid-like substance included in the PM can initiate inflammatory effects following exposure of respiratory epithelial (BEAS-2B) cells and an animal model (male Wistar Kyoto rats). Carbon black (CB) was exposed for 72 hours to either filtered air (CB-Air) or approximately 100 ppm ozone (CB-O₃). Carbon black exposure to high levels of ozone produced water-soluble, fluorescent organic material. Iron import by BEAS-2B cells at 4 and 24 hours was not induced by incubations with CB-Air but was increased following coexposures of CB-O₃ with ferric ammonium citrate. In contrast to CB-Air, exposure of BEAS-2B cells and rats to CB-O₃ for 24 hours increased expression of pro-inflammatory cytokines and lung injury, respectively. It is concluded that inflammatory effects of carbonaceous particles on cells can potentially result from (1) an inclusion of a fulvic acid-like substance after reaction with ozone and (2) changes in iron homeostasis following such exposure.

Quantitative measurement of carbon nanotubes in rat lung

Despite their numerous possible applications, the potential impact of carbon engineered nanomaterials (CEN) on human health, especially after inhalation exposure, is still questioned. Quantification of CEN in the respiratory system is a recurring issue and deposition and pulmonary biopersistence data are essential for toxicological evaluation. In this context, a fully validated standard method for CEN quantification in lung tissue is therefore imperative. The present method, based on the National Institute for Occupational Safety and Health 5040 method for atmospheric elemental and organic carbon analysis as well as on previous developments on biological matrices, involves a simple thermogravimetric analysis (TGA) of lyophilized samples, possibly preceded by a step of chemical digestion of the tissues depending on the nature of CEN investigated. The analytical method was validated for 4 CEN (carbon black as well as 3 long and thick or short and thin carbon nanotubes) for selectivity, linearity, detection and quantification limits, bias, and within-batch and between-batch precision. Calibration curves show linearity in the range of 1-40 mg/g lyophilized lung. Limits of detection for the different CEN range from 6 to 18 µg in 20 mg dry test sample. On average, within-batch precision was kept below 20 and 10% for analysis with or without a prior digestion step, respectively, whereas the corresponding between-batch precision levels reached almost 20 and 15%, respectively. The method was successfully applied to toxicological investigations for the quantitative analysis of CEN contents in rat lung exposed by inhalation.