Carbon Black Aggregates Research Articles

The effect of carbon black on degradation of pipe grade black polyethylene in high concentration chlorine dioxide solutions

In this research, the impact of carbon black on the accelerated degradation of pipe grade polyethylene (PE100) exposed to high levels of chlorine dioxide (150 ppm) is examined. Tensile testing reveals a faster degradation rate in black samples compared to neat samples, indicating a detrimental effect of carbon black aggregates on the polymer's aging process. Rheological analysis shows changes in molecular weight and structure due to chemical degradation and chain scission and can be a reliable method for detecting slight changes in molecular structure. Isothermal crystallization shows a slowdown in crystallization kinetics at first, explained by gel-formation due to crosslinking which hinder the crystallization, and then an increase in the kinetics as apparently the chain scission gets dominant again. Neat samples exhibit a higher density of tie molecules, indirectly revealed by much more fibrils in crack wall observed in FESEM images, suggesting better resistance to chemical degradation while the black sample shows a much less fibrillar crack wake and becomes almost completely devoid of any fibrils at later stages of aging. The fibrils, which essentially offer a load-bearing role against the widening and growth of the crack play a key role in resistance to slow crack growth (SCG). Therefore, the higher SCG resistance is expected for neat grade compared to black samples. The study proposes a dual-layer pipe design with a UV-resistant black outer layer and an oxidation-resistant neat inner layer to prolong the lifespan of PE100 pipes by protecting against UV radiation and chemical reactions. This solution offers increased durability, lower maintenance costs, and environmental sustainability benefits.

Revealing the nanoscale reinforcing mechanism: How topological structure of carbon black clusters influence the mechanics of rubber

The mechanical reinforcement of rubber by carbon black (CB) depends strongly on its the size and topography of CB clusters. However, the underlying mechanisms remain largely unexplored. This study uses atomic force microscopy (AFM) to probe interfacial properties at the nanoscale to elucidate the influence of the CB topological structure on macroscopic mechanical properties. A substantial amount of high-modulus bound rubber is found inside the CB aggregates, particularly in highly branched ones. This phenomenon plays a critical role in reinforcement, as corroborated by quantitative AFM nanomechanics, chain segment motion results and theoretical calculations. A quantitative analysis of the filler network reveals that the branched chain structure effectively reduces the packing spacing and improves the stress transfer efficiency.

On the fractal dimension of carbon black particles in pyrolysis flow reactors

This study presents a numerical approach for simulating the internal morphology of carbon black particles formed in a pyrolysis reactor. The simulation process involves a two-step approach using population balance models (PBM) and detailed population balance models (DPBM), solved via sectional and stochastic methods, to simulate the arrangement of primary particles within aggregates to allow determination of their fractal dimension (FD). The outcome is a novel introduction of simulating real flow reactors that for the first time provides the fractal dimension of particles as an output, rather than an assumed input. The results of this study have practical implications for optimizing the synthesis processes in carbon black production. The effects of various production parameters, including aggregation efficiency, temperature, pressure, and acetylene concentrations, on the fractal dimension values of carbon black particles are examined. It is observed that higher temperatures lead to the formation of larger fractal shapes with lower fractal dimensions and larger primary particle diameters. Moreover, increased reactor pressure and higher aggregation efficiency enhance the formation of carbon black aggregates, but also have a time-based effect with higher compactness at longer residence times. The time-based effect reveals the importance of sintering, where high loads of small particles enhance the overall sintering of the aggregates. These findings provide insights into the interplay between temperature, pressure, and particle morphology, highlighting the dynamic nature of carbon black nanoparticles and their response to synthesis process conditions.

Multiscale characterisation of the electrical response of 3d printed carbon black polylactic acid

In this paper, the electrical response of a carbon black polylactic acid 3D printed polymer is characterised in detail by a combination of advanced experimental techniques at different scale lengths. The electrical properties as a function of the temperature become repeatable after the second heating cycle, exhibiting different trends as a function of the printing parameters. Joule heating and oven-heating techniques have been compared, showing the advantages of the Joule heating method to maintain electrical conductivity due to the lower thermal inertia. Small-Angle X-Ray Scattering has been employed to discern the underlying physics, showing the crucial role of crystallinity, filler dispersion and carbon black aggregates to form an effective segregated conductive network. This investigation provides guidelines to produce 3D-printed devices with a reliable electrical response and the governing equations to operate them with sufficient accuracy for engineering applications.Graphical abstract

Process design for carbon black size and morphology

The structure (size and morphology) of carbon black (CB) largely determines its performance in tires, inks, batteries etc. Here, the impact of CB process synthesis variables, i.e. temperature, T, precursor (i.e. acetylene) flow rate, Q, and volume fraction, fv, on CB structure is elucidated by discrete element modeling (DEM) and compared to experimental data in the literature. The CB structure is quantified by the mobility, dm, and spherule or primary particle, dp, diameters, effective density, ρeff, and fractal dimension, Df. Decreasing Q or T enhances the CB yield, surface growth and agglomeration. This increases the mean dm and dp, consistent with experimental data from laminar flow ethylene pyrolysis reactors. The CB made at high Q or T is less compact than that made at low Q and T, having up to 50% smaller ρeff and 30% smaller Df, in excellent agreement with experimental data also. Increasing the fv (e.g. by increasing the precursor flow rate) results in CB aggregates (covalently-bonded CB primary particles) and increases the mean dm and dp, explaining commercial furnace black data. These CB aggregates are quite compact having up to 45% larger Df and larger ρeff than those of ethylene black. So process design diagrams generated by the present DEM simulations can be used to guide design and optimization of CB for various applications from first principles.

Spray Flame Synthesis and Multiscale Characterization of Carbon Black-Silica Hetero-Aggregates.

The increasing demand for lithium-ion batteries requires constant improvements in the areas of production and recycling to reduce their environmental impact. In this context, this work presents a method for structuring carbon black aggregates by adding colloidal silica via a spray flame with the goal of opening up more choices for polymeric binders. The main focus of this research lies in the multiscale characterization of the aggregate properties via small-angle X-ray scattering, analytical disc centrifugation and electron microscopy. The results show successful formation of sinter-bridges between silica and carbon black leading to an increase in hydrodynamic aggregate diameter from 201 nm to up to 357 nm, with no significant changes in primary particle properties. However, segregation and coalescence of silica particles was identified for higher mass ratios of silica to carbon black, resulting in a reduction in the homogeneity of the hetero-aggregates. This effect was particularly evident for silica particles with larger diameters of 60 nm. Consequently, optimal conditions for hetero-aggregation were identified at mass ratios below 1 and particle sizes around 10 nm, at which homogenous distributions of silica within the carbon black structure were achieved. The results emphasise the general applicability of hetero-aggregation via spray flames with possible applications as battery materials.

Evaluation of Mechanical Properties and HPM Pulse Shielding Effectiveness of Cement-Based Composites

In today’s world, protection against electromagnetic waves, including high-power microwave (HPM) pulses, is becoming increasingly important. Hence, the aim of this research was to select an absorbing admixture, which, when used in an appropriate quantity, improves the effectiveness of shielding against electromagnetic waves and, at the same time, satisfies the requirements that are important from a construction engineering point of view. Altogether, eighteen admixtures (including two types of fibers), added in different quantities, and three types of aggregate have been tested. The compressive and flexural strength test results show that the greatest improvement in the tested mechanical properties was achieved in the case of admixtures such as steel fibers, carbon black P803, ferrite, and fly ash. Regarding the effect of the admixtures on shielding effectiveness, the best results were obtained for graphite in the form of flakes, graphite in the form of powder, carbon black N990 and P803, polypropylene and steel fibers, and hybrid admixtures, i.e., ashporite aggregate with carbon black and ashporite aggregate with graphite flakes. Regarding both mechanical properties and HPM pulse shielding effectiveness, the best effects were achieved in the case of the specimens with a high steel fiber content.

Dry Electrode Manufacturing in a Calender: The Role of Powder Premixing for Electrode Quality and Electrochemical Performance

The dry manufacturing of battery electrodes has the potential to significantly reduce costs and the environmental impact of battery production but deteriorates the electrode quality due to drawbacks in the processability of the materials. By varying the mixing intensity of the powder mixtures, this work investigates the impact of blend homogeneity on the flow properties and the processability of the dry mixtures. Furthermore, the electrochemical performance of dry laminated electrodes made of LiNi0.6Mn0.2Co0.2O2 is investigated with respect to their initial mixture homogeneities and compared to slurry-based electrodes. An improvement of the powder flowability is observed for mixtures with a homogeneously distributed PVDF binder, which acts as a temporary lubricant in dry electrode manufacturing due to its ability to shear, resulting also in filament formation. Capacity and rate performance of electrodes made of homogeneous mixtures are the highest with 169 mAh/g at C/20 and 70 mAh/g at 3C compared to 169 and 49 mAh/g for the slurry-based electrodes, respectively. Cyclic voltammetry indicates lower overpotentials for incompletely homogenized electrodes due to the existence of carbon black aggregates that establish better long-range conductivity. Overall, electrodes from highly homogenized powders show the best electrochemical performance in terms of C-rate capability due to their favorable electrode thickness and porosity resulting from better processability in combination with a sufficiently distributed carbon binder domain.

Defossilization and decarbonization of hydrogen production using plastic waste: Temperature and feedstock effects during thermolysis stage

The replacement of natural gas with plastic-derived pyrolysis gas can defossilize H2 production, while subsequent capture, utilization and storage of carbon in a solid form can decarbonize the process. The objective of this study was to investigate H2 production from three types of plastics using a process comprising pyrolysis (600 °C) and thermolysis stages (1200–1500 °C). Depending on the plastic feedstock and thermolysis temperature, the laboratory-scale setup generated 1000–1350 mL/min product gas with H2 purity of 74.3–94.2 vol%. The recovery of 5–9 wt% molecular H2 per mass of plastics was achieved. Other products included solid residue (0.1–12 wt%) and oil (8–52 wt%) from the pyrolysis reactor, solid carbon (36–53 wt%) and gas impurities (2–16 wt%) from the thermolysis reactor. The purity of H2 gas was detrimentally influenced by polyethylene terephthalate in the feedstock due to the dilution of gas by CO. The decomposition of methane containing in the pyrolysis gas was the limiting reaction step during H2 production and improved at higher thermolysis temperature. Three solid carbon structures were formed during the thermolysis stage regardless of the plastic type: carbon black aggregates, carbon black aggregates coated with a layer of pyrolytic carbon and a carbon film on the inner reactor wall. Among the three types of carbon, the highest valorization potential was identified for carbon black aggregates. Plastic feedstock composition had little if any effect on carbon black properties, while high thermolysis temperature (1500 °C) reduced the particle sizes and increased the surface area of aggregates.

The Carbon Black Dispersion Index DICB: A Novel Approach Describing the Dispersion Progress of Carbon Black Containing Battery Slurries

The targeted adjustment of carbon black (CB) particle size in electrode slurries is a key step in battery production. Based on the energy input and dispersion device, the resulting particle structure of CB differs significantly. Most frequently, especially in more recent publications, the median particle size was used to describe changes during dispersion. However, this value does not contain enough information to describe the dispersion progress of bimodally distributed particles sufficiently. In this short communication, a novel approach describing the dispersion progress of CB containing slurries is introduced. This method was developed utilizing the hierarchical structure and fragmentation behavior of CB. The Carbon Black Dispersion Index DICB allows quick and easy assessment of the dispersion progress by isolating the CB aggregates of the bimodal distribution. This value offers major benefits with regards to quality control and production monitoring.

Damage Effect of Amorphous Carbon Black Nanoparticle Aggregates on Model Phospholipid Membranes: Surface Charge, Exposure Concentration and Time Dependence.

Commercial nano-scale carbon blacks (CB) are being harnessed widely and may impose potentially hazardous effects because of their unique properties, especially if they have been modified to grow reactive functional groups on their surface. Cytotoxicity of CB has been well studied but the membrane damage mechanisms and role of surface modification are still open to debate. Negatively and positively charged giant unilamellar vesicles (GUVs) were prepared using three lipids as model cell membranes to examine the mechanistic damage of CB and MCB (modified by acidic potassium permanganate) aggregates. Optical images showed that both anionic CB and MCB disrupted the positively charged but not the negatively charged GUVs. This disruption deteriorated with the rise and extension of exposure concentration and time. Lipids extraction caused by CBNs (CB and MCB together are called CBNs) was found. MCB caused more severe disruption than CB. MCB was enveloped into vesicles through an endocytosis-like process at 120 mg/L. MCB mediated the gelation of GUVs, perhaps through C-O-P bonding bridges. The lower hydrodynamic diameter and more negative charges may have been responsible for the distinction effect of MCB over CB. The adhesion and bonding of CBNs to the membrane were favored by electrostatic interaction and the practical application of CBNs warrants more attention.

Mechanism and factor analysis of welding PC and PASF using magnesium zinc alloy particles as laser-absorbent

Effectively joining dissimilar transparent thermoplastics plays an important role in lightweight design in vehicles and automotive industry. However, their different physical–chemical properties hamper the welding of thermoplastics directly with diode laser. In this study, magnesium zinc alloy particles (MZAP) are chosen as laser-absorbent to join polycarbonate (PC) and polyarylsulfone (PASF) specimens. First, the comparison of PC/PASF weldments with different laser-absorbents was performed, including adding carbon black (CB) as laser-absorbents. The morphology and mechani-cal properties show the weldments prepared with MZAP have advantages of cleaner appearance and stronger shear strength. Furthermore, the fracture surface and joint microstructure reveal that the mechanical riveting structure, composed of defused MZAP and filled thermoplastics in the gaps between adjacent MZAP, forms when the MZAP was used as laser-absorbent. Comparing with CB aggregates, the fused MZAP has a stronger ability to resist external force and leads to a higher shear strength. Finally, the analysis of factors of MZAP feature reveals that the mechanical riveting structure contributes to improving the shear strength, the defects, such as creaks, holes and bubbles should be eliminated in the welding. The results of analysis of variance illustrated the particle size and the standoff distance are statistically significant for the shear strength. This study provides a potential avenue to effective weld dissimilar thermoplastics.

Microstructural Modeling and Simulation of a Carbon Black-Based Conductive Polymer-A Template for the Virtual Design of a Composite Material.

Carbon black is the most frequently applied conductive additive in rubber and polymer composites. In this work, we show how a carbon black microstructure in a polymer matrix can be conclusively modeled based on carbon black aggregation as well as an agglomeration mechanism using a state-of-the-art mathematical model. This novel and flexible microstructural modeling method enables us to virtually investigate the morphology of conductive additives within a polymer matrix and can be adapted to many conductive polymer combinations used for different applications. Furthermore, we calculate the electrical conductivity of the composite using a finite volume-based as well as a discrete element-based simulation technique and validate the results with experimental data. Utilizing a novel discrete element method (DEM) modeling technique, we were able to improve calculation times by a factor of 12.2 compared to finite volume method (FVM) simulations while maintaining high accuracy. Using this approach, we are able to predict the required carbon black content and minimize the amount of additive to create a polymer composite with a designated target conductivity.

Strain-induced irreversible change of the conductive network in a rubber/carbon-black composite revealed by polarization-resolved terahertz dielectric spectroscopy

The dielectric response during the deformation of a rubber composite filled with carbon black (CB) was studied by polarization-resolved terahertz spectroscopy, because the characterization of such responses can be used to reveal strain-induced irreversible changes in the electrical properties of a CB-filled rubber. During the first stretching-and-relaxation cycle, two characteristic behaviors were observed: strain-induced anisotropy and an irreversible reduction of the dielectric constants in the measured frequency range. To understand the origin of this result, we tried to reproduce the strain dependence of the dielectric function with a modified effective medium theory that accounts for the orientational distribution of the CB aggregates. From the dependence of the fitting parameters on the deformation condition, it was found that the reduction of the dielectric constants in the terahertz frequency range is mainly caused by the breakdown of the CB-based conductive network due to a dissociation of CB agglomerates. This finding indicates that polarization-resolved terahertz spectroscopy is a promising technique for the assessment of changes in the internal structure of CB fillers on the nanometer scale.

Modeling Approaches for the Description of the Carbon Black Particle Size in Batch and Continuous Dispersion Processes for Lithium-Ion Battery Slurries

Energy storage is a key technology for alternative power trains like electric and hybrid electric vehicles. Lithium-ion batteries (LIB) are widely used for this purpose due to their high energy density and elaborated developmental state. Also, the increasing usage of electrified transportation leads to ever-increasing demands on LIBs in terms of fast charging ability and power density. The fragmentation of carbon black (CB) aggregates and agglomerates, respectively, has high impact on the resulting microstructure and mechanical integrity as well as conductivity of electrodes and furthermore, the electrochemical performance of LIBs [1]. To achieve optimized cell performances and to reduce the process times or increase throughputs while conserving the slurry quality, a method to predict the CB particle sizes based on simulations and experiments has been developed.This work demonstrates how the dispersion process can be modelled, thus laying the foundation for an optimized microstructure of the electrode right at the beginning of the process chain. For this purpose, a high-intensity batch process in a planetary mixer is investigated and modelled for the description of the CB fragmentation, and the approach is then applied to a continuous twin-screw extruder. Through the use of computational fluid dynamics, theoretical equations and considerations, and experimentally obtained data, the models are parametrized and can be used to predict the result of the dispersion process in form of the CB particle size. The critical values here are the shear rate in the laminar flow and the viscosity of the slurry, which determine the transferred energy onto the particles during the process. By appropriately modelling these characteristic values, it is possible to transfer the models to machines of different types and designs.Furthermore, it is shown how the predicted particle size of CB affects the microstructure of the electrodes. For this purpose, an innovative structural parameter is calculated from mercury intrusion measurements of manufactured electrodes, which expresses the internal porosity of the CB particles, or of the conductive microstructure, respectively. Based on the modelled CB particle size, this parameter can already be used to estimate the developing microstructure of the electrodes depending on the selected process parameters during dispersion. Such an approach is the basis for further work in order to holistically depict and digitalize the entire process chain of the LIB production and its counteracting influences.The experimental process data (power uptake of dispersion machines, viscosities, CB particle sizes), electrode structures, electrode properties (adhesive tensile strengths, spec. resistances) and cell performance data are shown to illustrate the approaches and the value of the created models. All LIB cathodes investigated consist of industrially relevant formulations (> 95 wt% active material NMC622, < 2.5 wt% CB). Reference s : [1] Mayer, J. , Almar, L., Asylbekov, E., Haselrieder, W., Kwade, A., Weber, A. and Nirschl, H., Influence of the Carbon Black Dispersing Process on the Microstructure and Performance of Li‐ion Battery Cathodes, Energy Technol. (2019)

Durable Pneumatic Artificial Muscles with Electric Conductivity for Reliable Physical Reservoir Computing

A McKibben-type pneumatic artificial muscle (PAM) is a soft actuator that is widely used in soft robotics, and it generally exhibits complex material dynamics with nonlinearity and hysteresis. In this letter, we propose an extremely durable PAM containing carbon black aggregates and show that its dynamics can be used as a computational resource based on the framework of physical reservoir computing (PRC). By monitoring the information processing capacity of our PAM, we verified that its computational performance will not degrade even if it is randomly actuated more than one million times, which indicates extreme durability. Furthermore, we demonstrate that the sensing function can be outsourced to the soft material dynamics itself without external sensors based on the framework of PRC. Our study paves the way toward reliable information processing powered by soft material dynamics.

Quantitative characterization of interfacial properties of carbon black/elastomer nanocomposites and mechanism exploration on their interfacial interaction

Carbon black (CB) is widely used as a good reinforcing filler in rubber industry. Due to the complex cluster structure of CB aggregate, it is difficult to clearly visualize its topological morphology and interfacial properties at nanoscale of CB/rubber composites. Thus, the good reinforcing mechanism of CB on rubber is still not fully understood. In this study, the surface topography structure of CB with different specific surface area (SSA) were characterized and their surface roughness were quantified using atomic force microscope (AFM). By using low content of CB and applying strong shear force to minimize the size of CB aggregate, the clear visualization of the bound rubber around CB aggregate was obtained using Quantitative Nanomechanical Mapping (QNM) technique of AFM (AFM-QNM). For the first time, the quantitative characterization of interfacial thickness and nano-mechanical modulus of CB/rubber composites were realized by AFM-QNM. Results show that the higher SSA of CB is mainly attributed to the higher surface roughness caused by the more complex topological structure of CB. And the higher surface roughness results in the higher interfacial thickness and Young's modulus at the nanoscale. Why CB with slightly smaller diameter shows largely increased reinforcing effect on rubber matrix is well explained.

Self-assembled 3D-microstructured dual carbon black filled polymer nanocomposite-coated fabric for tunable electromagnetic interference shielding

Dual carbon black (CB) was used to create self-assembled three-dimensional (3D)-microstructured polymer nanocomposite by a simple solution mixing process. A mechanical stirrer was employed for uniform dispersion and minimizing CB aggregates sizes in the viscous blended medium of hydrolyzed polyvinyl alcohol (PVA) and natural rubber latex (NRL). A stable 3D-microstructural architecture was obtained when an extremely high volume fraction (0.54) of dual CB was used. 3D-microstructured polymer nanocomposite was then applied on the cotton fabric and characterized for the final performance of electromagnetic interference (EMI) shielding effectiveness. The morphological and microstructural analysis revealed that dual CB at a particular ratio of 10:90 (smaller:larger) could provide excellent electrical conductivity (>1.5 S/cm) as well as EMI shielding when assessed against a frequency range of 8.2–12.4 GHz. A durable ultra-thin layer (100 µm) of nanocomposite was sufficient to achieve tunable >31 dB shielding effectiveness.

Research progress of modified carbon black used in rubber properties improvement

Rubber is widely used as a common elastomeric material in various fields. However, the poor physical properties of rubber without filler reinforcement could not satisfy the needs in the practical applications. Consequently, various fillers were developed and used to enhance the mechanical properties of rubber. Carbon black, the most common reinforcing agent, can reinforce rubber through the uniform distribution of carbon black particles. However, it is prone to agglomerate due to the interaction between the carbon black aggregate in the actual production. Therefore, the modification of carbon black is required to achieve the optimum distribution. To deal with these problems, several modification methods have been investigated. In this review, the existing modification methods were sorted into four different types: graft modification, surface coating modification, oxidation modification, and surface adsorption modification. Furthermore, a comprehensive evaluation of these methods and the prospects of carbon black material modification were presented.

An investigation into the preparation of carbon black by partial oxidation of spent tyre pyrolysis oil.

To promote the use of recycled waste materials as an industrial feedstock, this study examined the preparation of carbon black (CB) by partial oxidation of a spent tyre pyrolysis oil using a drop tube furnace. The effect of reaction temperature, the residence time of gas in the reactor and inlet gas oxygen concentration on the yield and properties of the CB were evaluated. The surface chemistry, chemical composition, morphological and thermal properties of the CB samples were characterised using XPS, EA, TEM, BET, and TGA, respectively. The CB yield increased with increasing reaction temperature but decreased as the residence time or oxygen concentration increases. The CB primarily consisted of C (90.5-98.6%) and O (0.9-7.4%), with small traces of S (<1%), Si (<1%) and H (<2%). Hydroxyl, carbonyl, and carboxyl are the key functional groups found on the CB surface, with the hydroxyl groups being dominant. The CB were highly graphitic with a lattice spacing in the range of 0.338-0.350nm and had BET surface areas of 4-22 m2g-1. The mean primary particle size ranged from 92 to 176nm and decreased with increasing reaction temperature and oxygen concentration. The CB aggregate configuration became more complex with increasing reaction temperature, residence time and oxygen concentration. The results were not only comparable with commercial CB products from fossil fuel feedstocks but are expected to provide the needed motivation to move towards circular economy strategies, which have positive impacts from a sustainability perspective.