Carbon Black Distribution Research Articles

Conductivity of PLA/PBAT blends with carbon black as a conductive filler

Conductive composites of PLA/PBAT/CB were prepared by melt blending. CB selectively distributes in the PBAT matrix, and at a PLA to PBAT ratio of 1:1, the composite achieves a conductivity of 1.01 × 10−6 S/m with a percolation threshold of 0.42 wt%. Compared to PLA/CB and PBAT/CB, the PLA/PBAT/CB composite has a lower percolation threshold. The E2 processing sequence most effectively enhanced conductivity by optimizing carbon black distribution in the PBAT phase, promoting a co-continuous structure and improving conductive pathways and electrical properties. Key methods used include contact angle measurements, polarized light microscopy, scanning electron microscopy, and a high-resistance meter.

Flexible and Scalable Dry Conductive Elastomeric Nanocomposites for Surface Stimulation Applications.

The study describes the development and testing of a dry surface stimulation flexible electrode (herein referred to as Flexatrode), a low-cost, flexible, and scalable elastomeric nanocomposite using carbon black (CB) and polydimethylsiloxane (PDMS). Flexatrodes composed of CB and PDMS were developed and tested for mechanical and functional stability up to 7 days. Uniform CB distribution was achieved by optimizing the dispersion process using toluene and methyl-terminated PDMS. Electromechanical testing in the through thickness directions over a long-term duration demonstrated stability of Flexatrode. Thermal stability of Flexatrode for up to a week was tested and validated, thus mitigating concerns of heat generation and deleterious skin reactions such as vasodilation or erythema. 25 wt.% CB was determined to be the optimal concentration. Electrical and thermal stability were demonstrated in the through thickness direction. Flexatrode provides stable electrical properties combined with high flexibility and elasticity. Electrotherapy treated chronic wounds were 81.9% smaller than baseline at day 10. Wounds that received an inactive device (device without any electrical stimulation) were 58.1% smaller than baseline and wounds that received standard of care treatment were 62.2% smaller than baseline. The increasing need for wearable bioelectronics requiring long-term monitoring/treatment has highlighted the limitations of sustained use of gel-based electrodes. These can include skin irritation, bacterial overgrowth at the electrode site, gel dehydration over time, and signal degradation due to eccrine sweat formation. Flexatrode provides stable performance in a nanocomposite with scalable fabrication, thus providing a promising platform technology for wearable bioelectronics.

Characterization, properties and mechanism of composite synthesized Eucommia ulmoides rubber and epoxy resin for electromagnetic interference shielding application

Synthesis of electromagnetic interference (EMI) shielding composites is the main strategy to solve the pollution of electromagnetic radiation. Herein, Mn0.6Zn0.4Fe2O4 (MZF) and carbon black (CB) were added into the emulsion made of Eucommia ulmoides rubber (EUR) and epoxy resin (EP) to prepare the MZF/CB/PEUR(EP@EUR) composites. The uniform distribution of CB created a conductive network that promoted abundant dipole polarization and conduction losses. In addition, the loading of the MZF imparted shielding mechanism of natural resonance and enhancement of conducting network for MZF/CB/PEUR composites that can optimize the complex dielectric constant, ulteriorly resulting in a high-level resonance peak (∼80.2 dB) in the 8.2–12.4 GHz frequency range. Based on the above series of filler loading experiments, the optimal loading concentration of CB (5%) and MZF (25%) was obtained. Finally, the excellent corrosion resistance of acid/alkali environments of MZF/CB/PEUR composites were further investigated. These results will provide a point of penetration for the development, application and mechanism research of EUR as a matrix for environment-friendly dielectric-magnetic EMI shielding composites.

Natural Rubber Composites Using Hydrothermally Carbonized Hardwood Waste Biomass as a Partial Reinforcing Filler- Part I: Structure, Morphology, and Rheological Effects during Vulcanization.

A new generation biomass-based filler for natural rubber, 'hydrochar' (HC), was obtained by hydrothermal carbonization of hardwood waste (sawdust). It was intended as a potential partial replacement for the traditional carbon black (CB) filler. The HC particles were found (TEM) to be much larger (and less regular) than CB: 0.5-3 µm vs. 30-60 nm, but the specific surface areas were relatively close to each other (HC: 21.4 m2/g vs. CB: 77.8 m2/g), indicating a considerable porosity of HC. The carbon content of HC was 71%, up from 46% in sawdust feed. FTIR and 13C-NMR analyses indicated that HC preserved its organic character, but it strongly differs from both lignin and cellulose. Experimental rubber nanocomposites were prepared, in which the content of the combined fillers was set at 50 phr (31 wt.%), while the HC/CB ratios were varied between 40/10 and 0/50. Morphology investigations proved a fairly even distribution of HC and CB, as well as the disappearance of bubbles after vulcanization. Vulcanization rheology tests demonstrated that the HC filler does not hinder the process, but it significantly influences vulcanization chemistry, canceling scorch time on one hand and slowing down the reaction on the other. Generally, the results suggest that rubber composites in which 10-20 phr of CB are replaced by HC might be promising materials. The use of HC in the rubber industry would represent a high-tonnage application for hardwood waste.

Design strategy for hierarchical structure of carbon black on microporous elastomer surface toward stretchable and compressive strain sensors

Flexible mechanical sensors capable of sensing both compressive and tensile strains with high sensitivity and linear piezoresistive response are of great significance for the development of wearable devices, flexible electronic skins, and robotics. However, it is still of challenge to develop simple 3-dimensional (3D) porous polymer/carbon nanomaterial composite strain sensors capable of sensing both tensile and compressive strains with reproducible electrical signals. Herein, we report a simple and scalable morphology-engineering strategy, i.e., selective location of carbon black (CB) in polyoxyethylene (PEO)/ethylene-α-octene random copolymer (ORC) blends via phase separation, to fabricate isotropic 3D continuous porous composite strain sensors. Such a composite consists of a continuous porous ORC matrix inlaid with preferable CB distribution on ORC surface after PEO removal, enabling distinguishable detection of both compressive and tensile strains with opposite resistance changes. Specifically, the as-fabricated strain sensors exhibit linear response with a sensitivity of 16 for 0–46% compressive strain, a detection limit of 0.3% strain with 16/16 ms response/recovery time. Besides, it has a large gauge factor for tensile strain of 0–300%, a detection limit strain of 0.06% with 16/47 ms response/recovery time, and low hysteresis degree. As such, it allows for full-range body motion monitoring and Morse code communication.

Controllable release fertilizer with low coating content enabled by superhydrophobic castor oil-based polyurethane nanocomposites prepared through a one-step synthetic strategy

Although the inherent degradability and sustainability of bio-based polymers make them promising coating candidates for controlled-release fertilizer (CRFs), large amounts of coating materials (coating content usually above 5%) and complex modification process are usually required to achieve controllable-release characteristics, which increases the production costs and therefore limits their application. In this study, superhydrophobic castor oil-based polyurethane/carbon black nanocomposites was developed through a one-step synthetic strategy to synthesize CRFs with low coating content by a three-layer rotating-drum coating method. The effect of the carbon black content and layer distribution on contact angles, physicochemical properties, microstructure, and release characteristics of the resulting coating material and CRFs was characterized and discussed. The contact angle of the polyurethane nanocomposites can reach up to 152.6°. In addition, the N release longevity of the coated urea fertilizer was extended to 30 days, definitely meeting the standards for CRFs using low coating content of 3 %. The coated fertilizers presented Super Case II transport mechanism. The mechanism underlying the controlled-release of this coated fertilizer was explored and discussed. The technique reported here offers a number of advantages, including low cost, easy performance, and excellent controllable-release performance, opening numerous opportunities for widely application of this environmentally-friendly, green CRF.

Carbon black distribution driven by its concentration and its effect on physico‐mechanical properties of styrene butadiene rubber and butadiene rubber miscible rubber blends

AbstractThis paper discusses the influence of partitioning of carbon black (CB) with its increasing concentration (i.e., 10, 20, 30, 40, and 50 phr) on physical and static mechanical properties of Styrene Butadiene Rubber (SBR)/Butadiene Rubber (BR) rubber–rubber blends (RRB's) in 70SBR:30BR blend ratio. Partitioning of CB towards BR in CB‐filled SBR/BR RRB's is quantitatively determined via dynamic mechanical analysis (DMA). DMA confirmed increased partitioning of CB towards BR phase with increasing CB. DMA data on the partitioning of CB towards BR were in good agreement with nuclear magnetic spectra obtained by solid‐state nuclear magnetic resonance spectroscopy (SS‐NMR spectroscopy). Curing properties, relative density, hardness, tensile test, tear test, and transmission electron microscopy (TEM) on CB filled SBR/BR RRB's were carried out to determine the effect of increasing concentration of CB on physical, mechanical, and dispersion characteristics in comparison to neat SBR/BR RRB's.

Optimisation method for carbon black distribution of polypropylene‐based semi‐conductive screen materials and its effect on charge emission behaviour at screen/insulation interface

AbstractThe semi‐conductive (SC) screen materials used in polypropylene (PP)‐based cables are usually multi‐component composites. Polypropylene shows poor compatibility with carbon black (CB), and CB particles tend to disperse in the elastomer phase, which results in CB non‐uniform dispersion in screen materials. The non‐uniform distribution of CB will cause abnormal electric fields at the screen/insulation interface and affect insulation performance. This paper prepared modified PP grafted by molecule maleic anhydride, and four PP‐based SC shielding materials were blended in combination with PP, PP‐g‐MAH, and thermoplastic elastomer (POE) as matrix resin. The CB distribution, electrical conductivity, and basic physical properties of the shielding material were characterised. Different screen materials were served as electrodes to test their effects on the space charge and conductivity characteristics of insulation. The relationship between the macroscopic properties and the distribution characteristics of CB was discussed. Results show that the selective dispersion of CB in screen material was improved by PP‐g‐MAH and the surface electric potential distribution was homogenised. Charge emission at the screen/insulation interface and conductivity can be reduced by homogenising the CB distribution. CB/PP‐g‐MAH/POE prepared in this paper exhibits relatively uniform CB distribution, which can reduce the charge emission from the screen/insulation interface.

Visual, Non-Destructive, and Destructive Investigations of Polyethylene Pipes with Inhomogeneous Carbon Black Distribution for Assessing Degradation of Structural Integrity.

Carbon black (CB) is used in polyethylene (PE) pipes to protect against thermal and photooxidation. However, when CB is not properly dispersed in the PE matrix during processing, white regions having little or no CB concentration, known as “windows,” appear within the CB/PE mixed black compound. In some cases, windows can drastically affect the structural integrity of both the pipe and butt fusion joint. In this work, PE pipes with varying amounts of windows were investigated for their characteristic window patterns, as well as quantifying the area fraction of windows (% windows). Tensile test on specimens with known % windows determined a critical limit above which the fracture strain rapidly degrades. Micro-tensile and micro-indentation results showed tear initiation at the window–black PE matrix boundary; however, they did not confirm the mechanism of tear initiation. In support of this work, a method of making thin shavings of a whole pipe cross section was developed, and the best viewing windows under cross-polarized monochromatic light were identified. In addition, a phased array ultrasonic test (PAUT) and microwave imaging (MWI) were directly applied to the pipe and confirmed the presence and patterns of the windows.

Experimental Investigation on the DPF High-Temperature Filtration Performance under Different Particle Loadings and Particle Deposition Distributions

Based on DPF filtration and regeneration bench, the solid particle emission and high-temperature filtration characteristics of different carbon black particle loadings and particle deposition distributions are studied. The aerosol generator (PAlAS RGB 1000) is used to introduce carbon black particles into the inlet of a DPF, and the NanoMet3 particle meter is used to measure the solid particle concentration at the inlet and outlet of a DPF to obtain the filtration characteristics. Previous studies found that without inlet carbon black particles, there was an obvious solid particle emission peak at the outlet of the deposited DPF during the heating, and the concentration increased by 1–2 orders of magnitude. In this paper, the high-temperature filtration characteristics under steady-state temperature conditions are studied. It is found that a DPF can reduce the range of inlet fluctuating particles, and with the increase of temperature, the proportion of large solid particles in the outlet particles increases, and the size distribution range decreases. Particle loading has positive and negative effects on the DPF filtration, and the DPF has the optimal particle loading, which makes the comprehensive filtration efficiency improve the highest. The deposition transition section can make the deposition particles in the DPF uniform, but the filtration efficiency is reduced.

Modification of rubber compositions by carbon nanotubes

The description of the method developed by the authors of modification of the carbon black (CB) reinforced rubber composition by addition multiwall carbon nanotubes (CNTs) into its composition is presented. The process includes the pre-formation of a mixture of CB with CNT by their joint treatment in a liquid, which ensures deagglomeration of CNTs and uniform distribution of CNTs and CB among themselves, subsequent drying, loosening and addition into the rubber composition with stirring. The amount and composition of hybrid nanofiller (CB and CNTs), as well as the method of CNTs inclusion: CB addition, CB substitution or its partial substitution is determined by a calculation that takes into account the ratio between the specific surface of CB and CNTs and the average particle size. Comparison of the predicted values of CNTs and CB with experimental data for rubber compositions with optimal characteristics based on both natural and synthetic rubbers shows the high efficiency of the applied method.

Combustion of a dilute carbon black/ethanol nanofuel droplet in elevated pressure conditions

Combustion of carbon black/ethanol nanofuel droplet at elevated temperature and pressure was carried out in this study. Ethanol was designated as a base fuel, and (0.5 and 1.0) wt.% of carbon black was added to produce nanofuel. One vol.% of Triton X-100 was used as a surfactant, and the mixture was ultrasonically homogenized. The stability of nanofuel and carbon black size distribution was evaluated before the experiments. The droplet diameter of (750 ± 50) μm was suspended at the tip of a fine K-type thermocouple to measure the temporal variation of droplet temperature. Droplet image was obtained by using high-speed cameras, and the change of droplet diameter, ignition delay, and burning rate were determined by post-processing of the droplet images. The ambient temperature was set to 750 °C, while the ambient pressure was changed to (5, 10, and 15) bar. The combustion process of carbon black nanofuel droplets was divided into 3 stages of droplet heating, classical combustion, and carbon black combustion. During the classical combustion stage, stable combustion was observed. On the other hand, in the carbon black combustion stage, combustion of carbon black particle with mild puffing was shown. As the ambient pressure increased, ignition was delayed, and the burning rate rose, due to the change of droplet behavior. Rise of carbon black concentration did not significantly affect the ignition delay, but the burning rate increased, due to the effect of thermal radiation. This effect was emphasized in the higher pressure condition.

Image processing for analysis of carbon black pellet size distribution during pelletizing: Carbon black PSD (PSD: pellet size distribution) by image processing

This paper describes a method for measuring carbon black pellet size distribution (PSD). Carbon black pellet size is related to mixing efficiency, working environment, and transport. Therefore, must be managed appropriately. The standard method ASTM D1511 to measure the pellet size requires too much time for real field analysis, and thus it is impossible to check the in-line pellet size. Therefore, if a pellet size issue occurs during operation, it cannot be addressed quickly. This paper presents a method for frequent, real-time carbon black PSD measurement through image processing. The processes for pellet imaging, image processing, PSD calculation, and original image processing correction are introduced in detail. A comparison of the ASTM 1511 and image analysis results was also performed. Finally, the in-line monitoring results analyzed by the image processing method are described. This study provides a more efficient and improved method to analyze carbon black PSDs.

Modeling the Thermal Conductivity of Porous Electrodes of Li‐Ion Batteries as a Function of Microstructure Parameters

The performance and lifetime of lithium‐ion batteries are strongly influenced by the temperature distribution within the cells, as electrochemical reactions, transport properties, and aging effects are temperature dependent. However, thermal analysis and numerical simulation of the temperature inside the cells can only be as accurate as the underlying data on thermal transport properties. This contribution presents a numerical and analytical model for predicting the thermal conductivity of porous electrodes as a function of microstructure parameters. Both models account for the morphology of the electrode structures and bulk material properties of the constitutive components. Structural parameters considered in both models alike are the porosity of the electrode coatings, particle size distribution, particle shape, particle contact areas, and binder carbon black distribution. The numerical model is based on the well‐established finite volume discretization, allowing for detailed 3D analyses. The analytical model is an extension of the well‐known Zehner–Bauer–Schluender approach for solid packing and provides fast predictions of the effects of parameter variations. The results of both models have been successfully verified against each other and compared to literature data and experimental measurements.

Effect of neutralization of poly(acrylic acid) binder on the dispersion heterogeneity of Li-ion battery electrodes

A systematic study using a model negative electrode slurry with poly(acrylic acid) as a binder is conducted aiming at the control of both dispersion quality and rheology in the electrode manufacturing process. Rheological properties of the model slurries vary considerably with the neutralization degree α. Optical microscope and Turbiscan measurements show that the rheological change is accompanied by the change in particle aggregation tendency. Adsorption and zeta potential measurements reveal that α-dependent adsorption of poly(acrylic acid) is the key factor that controls the rheology of the slurries. The difference in α of the slurry results in a significant difference in the surface roughness and the carbon black particle distribution in the electrode. From this study, it is concluded that the adjustment of neutralization degree of poly(acrylic acid)-based binder critically affects the heterogeneity of the electrode, which can influence the performance as well as the rheological stability in the electrode manufacturing process.

Enhancement of Percolation Threshold by Controlling the Structure of Composites Based on Nanostructured Carbon Filler

The effect of a multicomponent polymer binder composition on the electrical conductivity of composites filled with carbon black (CB) is reported. Composites based on a mixture of polypropylene and styrene-ethylene-butylene-styrene (SEBS), plasticized with industrial oil, and filled with electrically conductive CB, were prepared using a twin-roller mixer. The presence of various regions in the volume of the binder and the distributions of CB in binder regions was investigated by scanning electron microscopy. The formation of a special conductive network of CB is observed in the investigated composite. The electrical characteristics of the composites were investigated by means of impedance spectroscopy. On the basis of Raman spectroscopy, it was found that CB is predominantly located in the elastomer (in SEBS plasticized with industrial oil), which forms a continuous phase. It has been shown that the spatial distribution of CB (under constant loading of the filler) can change the conductivity of composites by as much as 5 orders of magnitude, and provides a low percolation threshold.

Effect of carbon black distribution on the properties of polyethylene pipes part 2: Degradation of butt fusion joint integrity

As a continuation of the previous work (Deveci, Antony, & Eryigit, 2018), we investigated the effect of carbon black distribution on the degradation of mechanical properties of butt-fusion joints and overall mechanical integrity of high-density polyethylene pipelines. Polyethylene pipes with similar carbon black concentrations but different distributions were produced with industrial scale compounding and extrusion equipment. Waisted tensile specimens were milled directly from the butt-fused pipe samples and elongated to fracture. Carbon black distributions at the butt fusion interphase, both in axial and radial directions, were investigated using stereo and scanning electron microscopy. A significant decrease in joint integrity, measured as work of fracture, was observed for the welds made with high-density polyethylene pipes with inhomogeneous carbon black distributions. It was found that the width of areas that do not contain carbon black (windows) can significantly enlarge at the butt fusion interphase due to shearing, resulting in brittle failures at the butt fusion interphase with a magnitude related to the level of inhomogeneity.

Electrophoretically Deposited ZnFe2O4-Carbon Black Porous Film as a Superior Negative Electrode for Lithium-Ion Battery

This article reports ZnFe2O4 (ZFO) based negative electrodes for a lithium-ion battery, which is synthesized using a simple autocombustion technique and coated onto copper current collectors using the electrophoretic deposition technique. The use of electrophoretic deposition to manufacture the electrodes results in the significant improvement of electrochemical properties of ZFO, which is achieved without the use of any complex processing steps or costly additives like graphene, CNT, etc. The electrophoretically fabricated electrodes possess a porous microstructure with uniform carbon black distribution. Such a microstructure and carbon black distribution successfully tackles the issues related to the low electronic conductivity and volumetric fluctuation based delamination. These electrodes deliver a stable reversible specific capacity of 560 mAh g–1 at a specific current rate of 0.5 A g–1, which is retained for 100 cycles. The electrodes also exhibit a specific capacity of 330 mAh g–1 at a high specifi...

Determination of phase specific localization of carbon black in ternary rubber blends: A macroscopic approach by fourier transform infrared spectroscopy (FTIR)

The phase specific localization of the reinforcing fillers like carbon black (CB), which has been known to influence the physical and mechanical performance of the rubber blends, can be determined by different characterization techniques, however, only for binary rubber blends. They have been failed so far when applied for more complicated systems like filled ternary rubber blends. In the present work we introduced a new technique using the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with germanium crystal for characterization of the specific localization of CB in a ternary blend of solution styrene butadiene rubber (SBR), butadiene rubber (BR) and natural rubber (NR). It is the first time we could follow the change of the amount of CB localized in each phase of this blend along the mixing time. CB firstly is incorporated into the NR phase and then it obviously migrates from the NR phase to the SBR phase as a function of mixing time that corresponds very well with the theoretical prediction based on the Z-model using the surface tension values of the filler and rubber blend components. The interaction between CB and rubber components can be qualitatively proved by the shift of the FTIR peak. Thermogravimetric analysis (TGA) was used to support the results obtained by the FTIR method. The study was further extended to follow the CB distribution in multi-step mixing.

Superior electromagnetic interference shielding effectiveness and low percolation threshold through the preferential distribution of carbon black in the highly flexible polymer blend composites

Carbon black distribution in different phases of blends affects the percolation threshold and electrical properties and electromagnetic interferences (EMIs) shielding effectiveness to a great extent. We addressed the challenge of developing a light weight and highly flexible superior EMI shielding material by combining ethylene methyl acrylate (EMA) and ethylene octane copolymer (EOC) with conductive carbon black. The selective distribution of filler particle in the EMA phase facilitates the way for double percolation phenomenon which signifies higher electrical conductivity properties. This percolated filler network development is revealed from the field emission scanning electron microscopy and TEM analysis. This newly developed conductive blend demonstrates superior EMI shielding efficiency of −31.4 dB together with promising mechanical and thermal properties. POLYM. COMPOS., 40:1404–1418, 2019. © 2018 Society of Plastics Engineers