Conductive Carbon Black Content Research Articles

Research and simulation of electromagnetic wave absorbing performance for lightweight cement-based materials containing expanded polystyrene with different particle sizes and carbon black

The electromagnetic wave (EMW) absorbing performance of cement-based materials incorporating expanded polystyrene (EPS) with varying particle sizes is comprehensively studied through a combination of experimental and simulation methods. The addition of conductive carbon black (CB) to the cement matrix significantly increases the conductivity and dielectric constant, thereby improving the loss capacity. The frequency shift behavior of single and three-layer absorbing materials adheres to the effective medium theory and interference cancellation principle. The enhancement in overall EM parameters leads to a shift of the reflection loss (RL) peak towards lower frequencies. For three-layer materials, an increase in the thickness of absorbent layer proves beneficial for enhancing absorption performance. Simulations can effectively model cement-based materials by employing uniform material settings, with the size of EPS particles serving as the primary variable. The simulation results reveal that an increase in EPS particle size, in both single-layer and multi-layer materials, causes a shift of the RL peak towards lower frequencies. Additionally, analysis of electric field mode distribution and EM power loss density distribution indicates that scattering at the curved EPS interface alters the propagation direction of EMWs, increasing opportunities for loss inside the cement-based material. Moreover, the three-layer absorbing material, with a density ranging from 850 to 900 kg/m3 and compressive strength exceeding 4 MPa, is suitable for EMW absorption in building envelope structures. In conclusion, an increase in EPS particle size and CB content leads to a low-frequency shift of the RL absorption peak. This discovery not only provides an empirical foundation for the development of absorption materials tailored to specific frequency bands but also offers an efficient approach for repurposing waste EPS of diverse sizes. Furthermore, the grading of EPS with different particle sizes has important practical significance for increasing the content of EPS and preparing lightweight cement-based materials.

Designing Biomimetic Conductive Gelatin-Chitosan-Carbon Black Nanocomposite Hydrogels for Tissue Engineering.

Conductive nanocomposites play a significant role in tissue engineering by providing a platform to support cell growth, tissue regeneration, and electrical stimulation. In the present study, a set of electroconductive nanocomposite hydrogels based on gelatin (G), chitosan (CH), and conductive carbon black (CB) was synthesized with the aim of developing novel biomaterials for tissue regeneration application. The incorporation of conductive carbon black (10, 15 and 20 wt.%) significantly improved electrical conductivity and enhanced mechanical properties with the increased CB content. We employed an oversimplified unidirectional freezing technique to impart anisotropic morphology with interconnected porous architecture. An investigation into whether any anisotropic morphology affects the mechanical properties of hydrogel was conducted by performing compression and cyclic compression tests in each direction parallel and perpendicular to macroporous channels. Interestingly, the nanocomposite with 10% CB produced both anisotropic morphology and mechanical properties, whereas anisotropic pore morphology diminished at higher CB concentrations (15 and 20%), imparting a denser texture. Collectively, the nanocomposite hydrogels showed great structural stability as well as good mechanical stability and reversibility. Under repeated compressive cyclic at 50% deformation, the nanocomposite hydrogels showed preconditioning, characteristic hysteresis, nonlinear elasticity, and toughness. Overall, the collective mechanical behavior resembled the mechanics of soft tissues. The electrical impedance associated with the hydrogels was studied in terms of the magnitude and phase angle in dry and wet conditions. The electrical properties of the nanocomposite hydrogels conducted in wet conditions, which is more physiologically relevant, showed a decreasing magnitude with increased CB concentrations, with a resistive-like behavior in the range 1 kHz-1 MHz and a capacitive-like behavior for frequencies <1 kHz and >1 MHz. Overall, the impedance of the nanocomposite hydrogels decreased with increased CB concentrations. Together, these nanocomposite hydrogels are compositionally, morphologically, mechanically, and electrically similar to native ECMs of many tissues. These gelatin-chitosan-carbon black nanocomposite hydrogels show great promise for use as conducting substrates for the growth of electro-responsive cells in tissue engineering.

Steering triboelectric and mechanical properties of polymer fibers with carbon black

The development of wearable electronics has spurred an increased interest in self-powered systems and triboelectric nanogenerators (TENGs). To enhance the output performance of TENGs, researchers have dedicated significant efforts toward finding effective ways to increase triboelectric and mechanical performance. This study examined how conductive carbon black (CB) affects the mechanical and triboelectric properties of electrospun fibers made of polyurethane (PU), polystyrene (PS), and polycarbonate (PC). The addition of CB affected their mechanical properties, including increased tensile strength and decreased elongation at break. Importantly, triboelectric testing revealed that incorporating CB decreased the triboelectric output of PU and PS by over 90%, while it increased the output of PC by 260%. These findings indicate that CB's effects on triboelectric properties depend on the material and its content, underscoring the importance of selecting CB content carefully for optimal mechanical and triboelectric performance in electrospun fibers and composites. This research validates the development of advanced composite materials for electrostatic discharge protection and energy harvesting applications.

Carbon‐based conductive rubber composite for 3D printed flexible strain sensors

AbstractPolymeric‐based flexible electronic devices are in high demand due to its wide range of applications. Natural rubber (NR) shows a great potential as matrix phase for flexible conductive polymer composites with its high elasticity and fatigue resistance. In this study, a new 3D printable conductive NR (CNR) composite was developed for strain sensor applications. Different contents of conductive carbon black (CCB) were mixed with NR latex to investigate the effect of the filler content on electrical and mechanical properties of the composites. The best‐known CNR composite with the CCB content of 12 phr was selected in order to produce the feedstock for the stereolithography process (SLA). The morphological, electrical, and mechanical properties of cast and 3D‐printed samples were investigated and compared. Although the 3D‐printed CNR sample had slightly lower conductivity than the cast one, it possessed comparable tensile strength and elongation at break, with values of 12.4 MPa and 703%, respectively. In addition, electrical responses of the CNR samples were investigated to demonstrate the electromechanical property of the material as a strain sensor. The 3D‐printed CNR sample exhibited the highest electromechanical sensitivity with a gauge factor (GF) of 361.4 (ε = 210%–300%) and showed good repeatability for 500 cycles. In conclusion, the development of this 3D printable functional material with great sensing capability will pave the way for innovative designs of personalized sensing textiles and other smart wearable devices.

An electric‐driven variable stiffness morphing skin: Preparation and properties

AbstractWith variable stiffness properties, shape memory polymers (SMPs) become the most promising materials of morphing skins. In this article, based on hydro‐epoxy resin/carboxyl‐terminated butadiene acrylonitrile/maleic anhydride matrix, composite morphing skins are prepared by doping conductive carbon black (CB). By adjusting the content of CB, in‐plane and out‐of‐plane properties of skins can be adjusted. Because of the in‐plane tensile stress acting on the skin during flight, tensile test is required. The results indicate that in‐plane tensile strength of skin decreases as the CB content increases. In electrical resistivity test, the electronic resistivity of skin decreases sharply at a low‐percolation threshold (1.9 wt%) and then maintains a low and steady level. As for out‐of‐plane properties, thermo‐ and electro‐active shape memory test are studied. All of the selected typical composite skins have 100% thermo‐driven shape recovery rate. Some skins have 100% thermo‐driven shape fixity rate and fast electro‐active shape recovery speed. When the CB content is 2.6 or 3 wt%, the skin can recover its out‐of‐plane deformed shape completely at 150 V. Benefit from easy control and remote drive, the composite SMP skins are proved to be a promising candidate material for morphing skins.

Mechanically strong, healable, and reprocessable conductive carbon black/silicone elastomer nanocomposites based on dynamic imine bonds and sacrificial coordination bonds

Commercial conductive polysiloxane composites are usually unrecyclable and suffer from inherent poor mechanical properties. Herein, mechanically strong, healable, and reprocessable conductive carbon black (CB)/polysiloxane nanocomposites were prepared through incorporating dual crosslinks of imine bonds and Zn(II)-amino coordination bonds in elastomer networks. Following the energy-dissipating mechanisms of sacrificial bonds, the integration of coordination bonds led to the remarkable improvement of strength, stretchability, and toughness without compromising the self-healing ability or reprocessability. Furthermore, the sacrificial and reversible manner of coordination bonds in nanocomposites was studied in detail. In addition to enhancing the electrical conductivity of nanocomposites (i.e., 6.48 S/m at CB content of 12 wt%), the incorporation of CB could promote the rupture of sacrificial bonds and improve the energy-dissipating efficiency significantly.

Dispersion kinetics of carbon black for the application in lithium-ion batteries

For production of electrodes for lithium-ion batteries, conductive carbon black (CB) has to be dispersed within the anode and cathode slurry. A sufficient dispersing degree has to be reached in order to ensure the formation of an adequate conductive network within the electrodes. As intermediate product, CB is dispersed in binder solution, prior to addition of active materials. As binder system on anode side carboxymethylcellulose in water is used, whereas on cathode side polyvinylidene fluoride in N-Methyl-2-pyrrolidone is applied. The conductive carbon slurry facilitates the characterization of the slurry properties, based on changes of CB. The structure and amount of conductive carbon black influences the slurry properties decisively. Viscosity increases with increasing CB content, which affects the shear stress within the mixing process. Rheological properties and particle size distributions are investigated over time while dispersing CB with various tip speeds in a dissolver. Dispersion kinetics are described on behalf of an existing model for tip speed variations. Based on the investigations of rheological changes due to varying amount of CB, an extended model enclosing the CB concentration as variable was developed. Using the extended model, particle sizes for new process parameters can be predicted.

Preparation and Properties of Epoxy Piezoelectric Vibration Reduction Composites

The epoxy resin (E-51) was used as polymer matrix, conductive carbon black (CB) as conductive filler, and PZT was used to prepare a composite by curing. The effects of PZT and CB content on the properties of PZT/ CB/ EP piezoelectric composite were studied. When the PZT content reaches 40 wt%, the optimized vibration attenuation properties of PZT/CB/EP materials could be achieved with a loss factor of 0.9 from room temperature to 60 °C. With the increase of PZT content, the bending strength of PZT/CB/EP piezoelectric composite vibration reduction material firstly increased from 45 MPa to 65 MPa and then decreased to 38 MPa. At room temperature, the dielectric constant increased from 7 to 50, and the dielectric loss increased from 0.1 to 0.5.

Conductive and fire-retardant wood/polyethylene composites based on a continuous honeycomb-like nanoscale carbon black network

This study prepares multi-functional wood/polyethylene composites (WPCs) by addition of a small amount of nanoscale conductive carbon black (CCB), leading to honeycomb-distributed WPC (WPCH-CCB). The conductivity, electromagnetic interference shielding (EMI SE), and flame-retardancy of WPCH-CCB were comparatively studied with the uniformly-distributed WPC (WPCU-CCB) prepared through a conventional melt-blending process. The conductivity and EMI SE of the WPCH-CCB reached up to 1.5 × 10−2S·cm−1 and 20.2 dB at 3 wt% CCB content, respectively. In comparison, the conductivity and EMI SE of the WPCU-CCB only had 8.3 × 10−14S·cm−1 and 5.0 dB. Moreover, the cone calorimetric analysis revealed that the WPCH-CCB had lower smoke production and heat release than the WPCU-CCB.

Numerical simulation of the effective permittivity of low‐density polyethylene composite filled by carbon black

The effective permittivity of low-density polyethylene with the conductive carbon black (CB) was modelled by COMSOL. The impact of CB content on the electric properties of the composites with different geometry of the inclusions was investigated. The modelling outcomes evidenced that the simulation was in good agreement with the experiment results at low-filler concentration. The effect of moisture on the effective permittivity of the composites was also investigated. A thin layer of adsorbed water on the surface of the CB particles was found to significantly increase the conductivity, which is in agreement with experimental results.

Synthesis of the SiO2@C composites with high-performance electromagnetic wave absorption

A series of core-shell SiO2@C microspheres with different size of SiO2 microspheres and thickness of conductive carbon black (CB) were prepared via carbothermal reduction method. The samples were characterized by SEM, TEM, XRD, XPS and Raman spectroscopy analyses. When the size of SiO2 microspheres or CB thickness was changed, the as-synthesized SiO2@C composites possessed diverse reflection loss (RL). Among, the electromagnetic wave (EMW) absorption performance of S-2 composite was optimal and its minimum reflection loss (RLmin) was up to −39.7 dB at the thickness of 3.8 mm and the effective bandwidth (RL ≤ −10 dB, 90% absorption) covered 1.3 GHz. Hence, it is the size of SiO2 microspheres and CB content that can tune the EMW absorption performance of the SiO2@C composites, which makes SiO2@C composites rather promising EMW absorption materials.

Electrical, dielectric, and dynamic mechanical properties of conductive carbon black/epoxidized natural rubber composites

Electrically conductive epoxidized natural rubber filled with conductive carbon black was prepared. The AC conductivity ( σAC), dielectric constant ( ɛ′), loss factor (tan δ*) and dynamic mechanical properties of the composites were studied. It was found that the epoxide groups in epoxidized natural rubber molecules positively contributed to AC conductivity, dielectric constant, and tan δ* of the composites. Especially, the composite with epoxidized natural rubber containing 50% mol epoxide (epoxidized natural rubber–50) showed better electrical and dynamic mechanical properties than the composites with epoxidized natural rubber–25 or NR. The effects of conductive carbon black loading level on electrical conductivity and dielectric constant of the epoxidized natural rubber–50/conductive carbon black composites was also studied. The percolation threshold was found at very low content of conductive carbon black at volume fraction of 0.07 with the critical exponent value 2.04. Furthermore, the glass transition temperatures of epoxidized natural rubber–50/conductive carbon black composites were higher than those of epoxidized natural rubber–25/conductive carbon black or NR/conductive carbon black composites, and increased with conductive carbon black content.

Effects of Gamma Radiation on Thermal Properties of Benzoxazine Filled with Carbon Black

In this study, the mixtures between benzoxazine monomer and electrically conductive carbon black (CB) were radiated with gamma ray at different doses, i.e. 0, 25, 50, 75, and 100 kGy before polymerization. The contents of carbon black filler were varied i.e. 0, 5, and 30wt%. The thermal properties such as curing temperatures and glass transition temperatures were determined using differential scanning calorimeter (DSC), while the decomposition temperature and char yields were analyzed using thermogravimetric analyzer (TGA).The results reveal that the radiation could decrease the curing temperature of pure polybenzoxazine. In addition, the decomposition temperature and char yield were increased with the increase of CB content. At the same CB content, the radiation dose could decrease the decomposition temperature and char yield.

Correlation between rheological and dielectric percolation of conductive carbon black-filled ethylene acrylic elastomer

Conductive rubber composites based on ethylene acrylic elastomer (AEM) and conductive carbon black (CCB) were prepared by a two-roll mixing mill. From the transmission electron microscope photomicrographs, the uniform distribution of CCB aggregates and the interconnected CCB aggregates in the AEM matrix were observed. The bound rubber content of unvulcanized rubber was found to increase significantly with increasing CCB content. The effect of CCB concentration on the dynamic viscoelastic properties of AEM matrix was determined using a Rubber Process Analyzer (RPA 2000) in terms of strain sweep and frequency sweep of both uncured and cured AEM/CCB systems. The storage modulus ( G′) increased with an increase in CCB loading. In the case of strain sweep, the G′ values decreased with strain amplitude for both the systems, but the G′ was more for cross-linked AEM/CCB systems. The strain dependency of G′ for CCB-filled AEM systems can be explained on the basis of the Payne effect. The complex viscosity ( η*) of these systems increased with CCB loading, and it decreased with strain amplitude, which is due to the shear thinning effect. The tan δ for unvulcanized and vulcanized systems increased with the strain; however, the value of tan δ was &lt;1 throughout the experimental strain range, which explains the elastic nature of the cured systems. The G′ increased with angular frequency for both the systems and the tan δ became independent upon the angular frequency after 10 Hz. The alternating current conductivity ( σAC) increased with an increase in CCB loading at all frequencies and the system achieves the percolation at 20 phr CCB loading, which is in accordance with the rheological percolation. The direct current conductivity (σDC) also increased with an increase in CCB concentration.

Conductive carbon black-filled ethylene acrylic elastomer vulcanizates: physico-mechanical, thermal, and electrical properties

The effect of conductive carbon black (CCB) on the physico-mechanical, thermal, and electrical properties have been investigated by various characterization techniques. Physico-mechanical properties of the vulcanizates were studied with variation of filler loading, which revealed that the tensile strength increased up to 20 phr (parts per hundred rubber) CCB loading, whereas at higher filler loading it decreased marginally. Furthermore, tensile modulus, tear strength, and hardness gradually increased with increase in filler loading. The compression set and abrasion loss decreased with increasing CCB loading. The bound rubber content (Bdr) of unvulcanized rubber was found to increase significantly with increasing CCB content. The crosslink density increased, whereas the swelling decreased with CCB loading. The thermal stability of the vulcanizates evaluated by thermogravimetric analysis (TGA) showed a minor increment with increase in CCB content. It is observed from the dynamic mechanical thermal analysis (DMTA) that the storage modulus (E′), loss modulus (E″), and glass transition temperature (T g) of ethylene acrylic elastomer (AEM) matrix increased by incorporation of CCB. The dielectric relaxation characteristics of AEM vulcanizates such as dielectric permittivity (e′), electrical conductivity (σ ac), and electric moduli (M′ and M″) have been studied as a function of frequency (101 to 106 Hz) at different filler loading. The variation of e′ with frequency and filler loading was explained based on the interfacial polarization of the fillers within a heterogeneous system. The e′ increased with increasing the CCB loading and it decreased with applied frequency. The frequency dependency of σ ac was investigated using conduction path theory and percolation threshold limit. The σ ac increased with increase in both CCB concentration and applied frequency. The M′ increased with applied frequency, however, it decreased above 30 phr filler. The M″ peak shifted towards higher frequency region and above 20 phr filler loading the peaks were not observed within the tested frequency region. The electromagnetic interference shielding effectiveness (EMISE) was studied in the X-band frequency region (8–12 GHz), which significantly improved with increase in CCB loading.

Improvement of electrostrictive properties of a polyether-based polyurethane elastomer filled with conductive carbon black

The electrostrictive properties of a polyether-based polyurethane elastomer and its corresponding composites filled with conductive carbon black (CB) were studied by measuring the thickness strain S Z induced by external electric fields E. For films with thicknesses of approximately 50 μm, the apparent electrostrictive coefficient M was measured at low electric fields, E ⩽ 4 V/μm, and different CB contents (up to a volume fraction of 2%). Dielectric measurements in AC mode were performed in order to determine the percolation threshold f c , which was 1.25 v%. This optimal volume fraction yielded a remarkable threefold increase in M, associated with an increase of the dielectric constant by a factor 7, in comparison with pure PU. This enhancement of the electric field-induced strain and apparent electrostriction was mainly triggered by an increase of the dielectric constant, even if the intrinsic electrostriction coefficient Q was decreased. The nanocomposites thus seem to be very attractive for low-frequency electromechanical applications. Above f c , their conductivity was raised and their electrostrictive activity lost. Finally, there is a good agreement between the experimentally determined dependence on the CB content of the M coefficient and the theoretical estimation calculated from dielectric and mechanical measurements.

The Effects of Dynamic Load on the Damping Performance of Piezoelectric Ceramic/Conductive Carbon/Epoxy Resin Composites

The 0–3 piezoelectric ceramic PMN (lead magnesium niobate-lead zirconate-lead titanate)/conductive carbon black (CB)/epoxy resin (EP) and PMN/carbon nanofibers (CNFs)/EP composites were prepared by the resin casting method. DMA curves showed that tan δ of PMN/CB/EP composite increased and reached to a maximum value at a certain stress and then dropped with the rising of dynamic stress, but tan δ of PMN/CNFs/EP composite showed opposite trends compared to PMN/CB/EP composite. The loss factor of PMN/CB/EP and PMN/CNFs/EP composites increased with the increase of loading frequency. When CB content is 6% and CNFs content is 0.6% weight of epoxy resin the PMN/CB/EP and PMN/CNFs/EP composites showed the best damping performance, moreover PMN/CNFs/EP composite performed better damping properties than PMN/CB/EP composite.

Chemical sensing materials. I. Electrically conductive SEBS copolymer systems

AbstractChemical sensing materials based on conductive carbon black (CB) filled [styrene‐ethylene butylene‐styrene] triblock‐copolymers (SEBS) were investigated. Several types of SEBS copolymers were studied, differing in composition and melt viscosity. The sensing is based on electrical conductivity changes upon solvent sorption/desorption. Compression molding SEBS composites containing various amounts of CB were prepared. Their electrical conductivity was measured and samples containing CB, preferentially located in the continuous ethylene/butylene (EB) phase, at a level near the corresponding percolation threshold were used for the sensing experiments. The conductivity was measured during several exposure/drying cycles. Structure characterization included scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), and calorimetry (DSC). The SEBS composites exhibit large reversible changes in conductivity upon exposure to a limited number of solvents, e.g., acetone, n‐heptane, and air drying cycles. This behavior was related to the sorption kinetics, affected by the solvent characteristics (solubility parameter, polarity, molecular volume and vapor pressure). The samples' resistance tended to return to their initial value upon short drying of acetone, and longer drying of other studied solvents. The nature of the SEBS, the CB content, and mixing temperature are all significant parameters, determining the sample's structure and the resultant sensing property. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Resistivity and thermal reproducibility of carbon black and metallic powder filled silicone rubber heaters

AbstractFlexible heaters were prepared by extruding platinum‐catalyzed silicone rubber composites with conductive carbon black (CB) and metallic fillers. The conductor resistivity of the extruded heaters decreased in order of conductive titanium dioxide (TiO2) &gt; aluminum powder ≈ zinc powder &gt; copper powder. Thermoelectric switching phenomena were investigated for the silicone rubber/CB/metallic powder systems. The positive temperature coefficient effect was dependent mainly on the CB content rather than on the content of the metallic powders. Resistivity and thermal reproducibility of the extruded heaters were also investigated by periodically applying AC voltage of 110 V. The heaters containing copper and TiO2 powders exhibited excellent electrical reproducibility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1122–1128, 2005

Sensing of liquids by electrically conductive immiscible polypropylene/thermoplastic polyurethane blends containing carbon black

AbstractImmiscible polymer blends based on polypropylene/thermoplastic polyurethane (PP/TPU) are interesting host multiphase systems for the incorporation of low concentrations of conductive carbon black (CB) particles. The enhancement of conductivity (and the lower critical CB content for percolation) in the PP/TPU blend is achieved via double percolation, that is, structural and electrical. The CB particles form chainlike network structures within the TPU phase, which exhibit phase continuity of elongated particles within the PP matrix. Moreover, scanning electron microscopy and dynamic mechanical thermal analysis studies indicated that the incorporation of CB particles into the PP/TPU blend has a “compatibilizing” effect, resulting in an enhanced interaction between the two polymers. Extruded PP/TPU/CB filaments produced by a capillary rheometer process at various shear rates were examined as sensing materials for a homologous series of alcohols, that is, methanol, ethanol, and 1‐propanol. All filaments displayed increasing resistance upon exposure to the various alcohols combined with excellent reproducibility and recovery behavior. An attempt is made to identify the dominant mechanisms controlling the sensing process in a CB‐containing immiscible polymer blend characterized by a double‐continuity structure. The interphase region, its quantity, and continuity played a significant role in the liquid‐transport process. Blend composition, filaments' extrusion temperature, and production shear rate level were considered as significant parameters determining the structure and the resultant sensing properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1428–1440, 2003