Carbon Black Distribution Research Articles

Effect of carbon black distribution on the properties of polyethylene pipes - Part 1: Degradation of post yield mechanical properties and fracture surface analyses

In this study, we investigated the effect of carbon black distribution on the degradation of mechanical properties of high-density polyethylene in the form of plastic pipes used in water distribution networks. Polyethylene pipes with similar carbon black concentrations but different carbon black distributions were produced with industrial scale compounding and extrusion equipment. Tensile specimens were directly prepared from extruded pipe samples and elongated to fracture at different strain rates. Carbon black distributions of bulk samples and fracture surfaces were investigated using stereo and scanning electron microscopy (SEM). It was found that the carbon black distributions, fracture surfaces and fracture modes were significantly different in these pipes. Although the yield properties were similar, the post-yield properties of samples were significantly different, dramatically decreasing with the increasing inhomogeneity of carbon black distribution. Pipes with a certain level of heterogeneity in the carbon black distribution showed ductile and brittle fractures in the same fracture plane, whereas homogenous black and natural polyethylene (without carbon black) showed ductile fractures only.

An Investigation of the Effect of Taurit Filling of Rubber Mixes for the Coating of Radial Lorry Tyre Breakers

The results of investigating the effect of the shungite analogue Taurit (grade TSD) on the properties (measured on an RPA 2000 instrument) of a breaker rubber mix and of a rubber compound based on synthetic isoprene rubber SKI-3 are set out. Different methods of introducing Taurit have been tested: 10 parts into the rubber at the stage of its production; 10 parts into the standard rubber mix at the first stage of mixing; 10 parts into the rubber subjected to preliminary mechanical plasticisation in a laboratory internal mixer at a temperature of 100°C. The introduction of Taurit into the rubber in small quantities in order to reduce the proportion of rubber constituent in the rubber mix has also been tested. The test results have been compared with results for standard rubber mixes and rubber compounds. When Taurit is introduced into rubber at the stage of its production, the cohesive strength of the rubber mix and the rate of its vulcanisation and also the dynamic modulus components G′ and G″ are increased. When Taurit is introduced into plasticised rubber, again G′ and G″ are increased, there is an increase in plasticity, and the elastic recovery of the rubber mix is reduced. The breaker rubber compound from this mix has the best adhesion to metal cord and the highest dynamic strength. Data on the Payne effect indicate a better carbon black particle distribution when Taurit is introduced into the rubber at the stage of its production. Reduction in the proportion of rubber constituent in the rubber mix leads to a deterioration in the carbon black particle distribution.

New method for binder and carbon black detection at nanometer scale in carbon electrodes for lithium ion batteries

In the current work, graphite electrodes comprising PVDF binder and carbon black are subjected to characterization. An energy selective backscatter detector is used to localize carbon black and fluorine of PVDF. Therefore, it is necessary to distinguish between graphite, amorphous carbon and fluorine rich regions. Typically, an angular selective backscatter detector is employed to obtain an image providing the material contrast of the sample. Suitable materials for that detector are e.g. alloys to observe intermetallic phases, semiconductor for “channeling contrast”, or imaging SiO2 and Au nanoparticles in biological cells. However, this detector cannot be used to distinguish between light elements with low atomic numbers, such as C to P. In addition, the contrast of fluorine rich regions and graphite is poor in normal in-lens images due to the low difference of the atomic mass between C and F. The aim of this study is to enhance the contrast of fluorine rich regions to graphite to carbon black. Therefore, the energy selective backscatter detector is used and its advantages and setup is described. Finally this technique is applied to investigate 400 μm thick cross-sections of graphite electrodes dried at different temperatures and obtain the carbon black distribution.

Improved mechanical properties of carbon fiber-reinforced epoxy composites by growing carbon black on carbon fiber surface

The interfacial properties between carbon fiber (CF) and matrix play a key role in the mechanical properties of carbon fiber composites. To improve the mechanical properties of fibers/epoxy composites without sacrificing tensile strength of base fibers, carbon black (CB) was introduced onto the surface of CFs by chemical vapour deposition (CVD). The distribution of CBs on the fiber surface and the change of the surface roughness were analyzed, using scanning electron microscopy (SEM) and atomic force microscope (AFM). Raman spectroscopy indicated that the defects of CF surface were repaired by CB. The wettability and surface energy of modified CFs increased obviously in comparison with those of the untreated CFs. Meanwhile, a significant increase of interlaminar shear strength (ILSS), interface shear strength tests (IFSS) and impact property were achieved in the 5-min-modified CFs, which was 22.0, 44.4 and 22.7%, respectively. In addition, the tensile strength (TS) of modified CFs showed a slight increase compared with that of untreated CFs.

Effect of preparation methods and carbon black distribution on mechanical properties of short pineapple leaf fiber-carbon black reinforced natural rubber hybrid composites

The aim of this work is to improve the performance of natural rubber reinforced with a hybrid of pineapple leaf fiber with carbon black. When there are multiple components to be mixed into a rubber matrix, mixing can be carried out in more than one way. Thus, in this study, the effects of preparation method and the resulting carbon black distribution on the mechanical properties of the hybrid composite were evaluated. Pineapple leaf fiber (PALF) and carbon black contents were fixed at 10 parts (by weight) and 30 parts (by weight) per hundred parts of rubber (phr), respectively. In order to improve the dispersion, PALF with rubber was prepared as a masterbatch. Carbon black was added to the compound either as a single portion or as two separate portions, one in the PALF masterbatch and the other in the main mixing step. It was found that, despite using the same final compound formulation, the mixing scheme significantly affected the medium strain region of the vulcanizate stress-strain curve. No stress drop in this strain region was observed for the two-step mixing scheme. Models for composites with different preparation methods are proposed and discussed.

Epoxy–carbon black composite foams with tunable electrical conductivity and mechanical properties: Foaming improves the conductivity

ABSTRACTIn this study, conductive epoxy foams with different carbon black (CB) contents were fabricated with expandable microspheres as foaming agents. The effect of the CB content, microsphere concentration, precuring time, and foaming temperature on the electrical conductivity and compressive properties of the obtained foams were investigated systematically. The differential scanning calorimeter and rheological tests confirmed that the CB accelerated the curing reaction, increased the onset viscosity of the epoxy blend during foaming, and affected the foaming process. In addition, all of the parameters, including the CB content, microsphere concentration, precuring time, and foaming temperature, were confirmed to change the foam structures and further change the conductivity and mechanical properties. The electrical properties test revealed that the foaming process improved the conductivity of the composites. On the basis of the electrical properties test results and scanning electron microscope images, a flow‐induced CB aggregation mechanism is presented, in which the thermally triggered microsphere expansion pushed the resins away, squeezed the CB together, and changed the CB distribution throughout the foams. This made more conductivity paths. The obtained foam could just be used as an antistatic material, but it gave us an example for exploring lightweight and low‐cost conductive epoxy foams with other applications, for example, electromagnetic shielding. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45071.

Evaluation of carbon black distribution in different phases of compatible blend of EVA/NBR through electrical, mechanical and morphological test

The paper reveals the influence of different methods of carbon black (CB) incorporation in the compatible blend of 50/50 (wt %) Ethylene vinyl acetate (EVA) and Acrylonitrile butadiene elastomer (NBR) on different properties of vulcanized blend compounds. The partitioning of two types of CB in two different phases of the blend was estimated from dynamic mechanical analysis (DMA). The distribution of CBs due to preferential addition in different phases of the blend affects property variations in different degrees. From the analysis of SEM, TEM, AFM and electrical property measurements, it is found that mixing method significantly affects the electrical properties, morphology, and surface topography. The variation in AC conductivity and surface resistance study confirms the formation of different conductive network of CB with variation in mixing technique and it is supported by morphology analysis. The DMA have shown that CB has higher affinity towards less viscous EVA phase. This is further corroborated by the surface energy measurement, which in turn controls the electrical conductivity behaviour as well as mechanical properties of the blends.

INFLUENCE OF PHASE MORPHOLOGY AND FILLER DISTRIBUTION IN NR/BR AND NR/SBR BLENDS ON FRACTURE MECHANICAL PROPERTIES

ABSTRACTThe filler distribution and the amount of interphase are determined for carbon black (CB) filled blends of natural rubber (NR) with butadiene rubber (BR) and styrene–butadiene rubber (SBR) and compared with fatigue crack propagation rates under pulsed excitation. A viscoelastic model is used to separate the contributions of the different polymer phases and the interphase to the total dissipated energy G″ during dynamic straining. The filler amount in any phase can be calculated from the increase of the energy dissipation. For NR/SBR blends a higher filler load of the SBR phase and the interphase and a lower filling of the NR phase are identified. In contrast NR/BR blends show a very low filled BR phase and higher filling of the NR phase and the interphase. The carbon black distribution also depends on mixing procedures. Through a batch mixing procedure, in which the filler is previously mixed in the NR only and then blended with BR, the filler transfer from NR to BR increases the filling of the BR phase. The phase morphological results deliver information for a better understanding of crack propagation in CB filled NR/BR and NR/SBR blends. The fracture behavior differs significantly if NR is successively replaced by BR or SBR, respectively. A less pronounced effect is found for the variation of mixing procedure, although it seems that the more heterogeneous filler distribution with a high amount of CB in NR of the batched samples delivers slightly reduced crack propagation rates.

Effect of network formation on the electrical, mechanical, and processability behaviors through the preferential distribution of carbon black in the incompatible polymer blend composite

Four different methods of preferential addition of fixed amount of HAF carbon black have been done in two phases of an immiscible blend of NBR–EPDM (50/50 wt%). However, it is found that redistribution of carbon black occurs in blend phases during mixing even after preferential addition. This is revealed from the measurement of both dynamic mechanical, and mechanical properties. Carbon black redistribution in different phases of blends also affects the electrical properties, especially the frequency dependent AC‐conductivity to a great extent. The surface tension and viscosity of two components of the blend namely NBR and EPDM play an important role in the distribution of carbon black in respective phases. Carbon black distribution also affects hysteresis behavior of the blend and can be correlated with the variation in AC conductivity. The processability behavior of black filled compound is also affected by the preferential addition of carbon black in the elastomer blend. POLYM. COMPOS., 39:2620–2633, 2018. © 2016 Society of Plastics Engineers

Thick electrodes for Li-ion batteries: A model based analysis

Abstract Li-ion batteries are commonly used in portable electronic devices due to their outstanding energy and power density. A remaining issue which hinders the breakthrough e.g. in the automotive sector is the high production cost. For low power applications, such as stationary storage, batteries with electrodes thicker than 300 μm were suggested. High energy densities can be attained with only a few electrode layers which reduces production time and cost. However, mass and charge transport limitations can be severe at already small C-rates due to long transport pathways. In this article we use a detailed 3D micro-structure resolved model to investigate limiting factors for battery performance. The model is parametrized with data from the literature and dedicated experiments and shows good qualitative agreement with experimental discharge curves of thick NMC-graphite Li-ion batteries. The model is used to assess the effect of inhomogeneities in carbon black distribution and gives answers to the possible occurrence of lithium plating during battery charge. Based on our simulations we can predict optimal operation strategies and improved design concepts for future Li-ion batteries employing thick electrodes.

Blending of NR/BR/ENR/EPDM-g-GMA by reactive processing for tire sidewall applications

Application of ethylene–propylene-diene monomer (EPDM) grafted with glycidyl methacrylate (GMA), along with epoxidized natural rubber (ENR) was investigated for tire sidewall blend. The presence of ENR and EPDM-g-GMA improved physico-mechanical properties of the blends. The best results were obtained using 5 phr EPDM-g-GMA in the blend. Tensile and tear strength of the blend with 5 phr EPDM-g-GMA were 13.7% and 46.5% higher than conventional blend of tire sidewall, respectively. Ozone resistance in dynamic condition of NR/BR/ENR with 5 phr EPDM-g-GMA were 20% and 30% superior than NR/butadiene rubber (BR)/ENR/EPDM and conventional NR/BR with N-(1,3-dimethylbutyl)- N′-phenyl- p-phenylene, respectively. Improved mechanical and ozone resistance properties are due to better homogeneity of cross-link density and carbon black distribution in the blend.

Intensive powder mixing for dry dispersing of carbon black and its relevance for lithium-ion battery cathodes

Carbon black is an important component in lithium-ion battery electrodes since it significantly improves the electric conductivity in the coating. Dependent on the carbon black structure and the homogeneity of the carbon black distribution, electrical and electrochemical electrode properties vary. The presented work reveals that the carbon black structure in lithium-ion battery electrodes can precisely be governed by careful parameter variations in an upstream dry mixing process. Significant changes in important electrode properties like mechanical, structural and electrical characteristics are achieved and can be described as functions of the process parameters “mixing time” and “mixing intensity”. The integration of an intensive dry mixing process improves the coating homogeneity and creates short-range electrical contacts on the particle surfaces, leading to enhancements in cycling stability. Long-range electrical contacts can be re-established due to a subsequent calendering step, compensating rate capability losses, which can be identified for uncalendered electrodes.

Heterocoagulation behavior of carbon black with surface encapsulation through emulsion polymerization

ABSTRACTNanocomposite microspheres containing styrene–acrylate resin, wax, and carbon black (CB) with desired CB dispersion were prepared through heterocoagulation. The CB surface was modified using conventional anionic emulsifier and anionic dispersants with different lengths of nonionic chains and reactivities or through polymer encapsulation via emulsion polymerization to regulate the dispersion and concentration of CB in the microspheres. Experimental results showed that anionic dispersants with long nonionic chains effectively dispersed and stabilized CB particles. Polystyrene (PS) was then encapsulated on the CB surface by using a reactive dispersant and a water‐soluble initiator of polymerization. The CB particles exhibited comparable pH stability with other heterocoagulation components. Overall, encapsulation through emulsion polymerization can be used to obtain not only high CB content but also improved CB distribution in the resulting microspheres. High coagulation efficiency can also be achieved using polystyrene‐encapsulated dispersed CB because of its high affinity to emulsifiers and reactive dispersants during dispersion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43516.

Characterizations and electrical conductivity of (poly[vinyl chloride])/(poly[ethylene oxide]) conductive films: The effect of carbon black loading and poly(ethylene glycol) diglycidyl ether

The effect of carbon black (CB) loading filled (poly[vinyl chloride])/(poly[(ethylene oxide]) (PVC/PEO) conductive films with and without poly(ethylene glycol) diglycidyl ether (PEGDE) was studied. The PVC/PEO/CB and PVC/PEO/PEGDE/CB conductive films were prepared by a solution casting method. The results indicate that the addition of PEGDE of PVC/PEO/CB/PEGDE conductive films exhibited higher tensile properties, electrical conductivity, and thermal stability compared with PVC/PEO/CB conductive films. The scanning electron microscope micrographs of PVC/PEO/PEGDE/CB conductive films showed a rough surface and a good distribution of CB on the surface of PVC/PEO/CB conductive films. Fourier‐transform infrared spectrum showed that the interaction between the PVC/PEO films and the CB‐PEGDE phase on the surface of the conductive films does not change the functional group of the PVC/PEO/PEDGE/CB conductive films. J. VINYL ADDIT. TECHNOL., 24:139–146, 2018. © 2016 Society of Plastics Engineers

Influence of temperature and pressure on carbon black size distribution during allothermal cracking of methane

abstractAllothermal cracking of methane is a suitable and eco-friendly way to simultaneously produce hydrogen and carbon black. The economic viability of the process relies on the ability to produce carbon black having well-defined characteristics, particularly concerning the particle size. A model for the study of the carbon particle size distribution during thermal cracking of methane has been developed. The model takes into account: heat transfer by conduction, convection, particle and gas radiation, homogenous and heterogenous reactions of methane dissociation, nucleation, and growth of solid carbon particle formed. The model alleges nanoparticles are in thermal equilibrium and do not impact the flow. A parametric study is made on operating pressure and temperature. As a result, the increase of the pressure and temperature increases the yield of thermal methane cracking. Moreover, results show a particle size distribution becoming narrower with increasing temperature and/or pressure. In these conditio...

Highly Dispersed Poly(vinylidene fluoride) and Carbon Black in NMC Cathodes Produced Via Non-NMP Electrovaya Superpolymer 2.0 Processing Method

The development of low cost lithium ion batteries using a non-toxic, non-NMP and low cost production process stands as one of the most promising technology breakthroughs, especially with the surging demand for cost effective solutions for energy storage and electric mobility. We demonstrate for the first time that NMP is not required for achieving a microstructure comprising carbon black and PVDF binder with substantial uniform dispersion throughout the active materials. In turn, well-dispersed conductive additive and binder in the electrode, prepared via Electrovaya’s non-aqueous SuperPolymer 2.0 processing method, is observed via performing extensive microstructure characterization using TOF-SIMS, HAADF, and SEM/EDS techniques. These techniques provide information about the carbon black and PVDF binder distribution and uniformity within the cathode material which turn out to be intimately linked to the electrochemical performance of the battery. The composite cathode NMC material when coupled with graphite in a full cell shows an excellent electrochemical performance on par with other commercial lithium ion batteries that utilize conventional toxic NMP coating methods.

Study on properties of natural rubber reinforced by poly(sodium‐4‐styrenesulfonate)‐decorated carbon black with a latex compounding technique

ABSTRACTNatural rubber filled with poly(sodium‐4‐styrenesulfonate) (PSS)‐decorated carbon black (CB) by employing a latex compounding technique was prepared. The result of scanning electron microscope demonstrated that CB was uniformly dispersed in the matrix. Comparing to traditional dry compounding, an improvement in physical and mechanical properties was observed in the composites attributed to the homogeneous distribution of CB in matrix and an augment of bound rubber. Owing to the changes of the physical properties of CB surface, vulcanizate filled with oxidized CB via latex way exhibited higher mechanical properties. The resulting vulcanizates displayed a diminished interaction between fillers based on the consequence of strain dependence of storage modulus. Furthermore, a splendid wet‐skid resistance was obtained in vulcanizates fabricated by latex compounding technique in comparison with vulcanizates prepared by traditional dry compounding. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42346.

Distribution ratio of carbon black in polyisobutyrene/polyisoprene rubber blends using high-resolution solid-state 13C NMR

We establish the 13C nuclear magnetic resonance (NMR) method as the best available method for the evaluation of carbon black (CB) distribution in rubber blend. We find that the line widths of NMR peaks increase as CB contents increase. Using this phenomenon it is found that, in polyisobutyrene rubber (IIR)/polyisoprene rubber (IR)/CB composites, CB more easily distributes in IR than in IIR. And we can estimate that more than 70% of CB is distributed in to the IR phase, irrespective of CB content.

Numerical Simulation and Analysis of Carbon Black in Pneumatic Conveying Pipe

Based on establishment of the mathematical model about the carbon black dense phase pneumatic conveying, using computational fluid dynamics ( referred to as CFD) methods, this paper stimulated the carbon black flow state inside the bent pipe. Through simulation and analysis, the carbon black particles' flow condition along the bent pipe, the carbon black particles' distribution variation at the bent pipe cross-section, the bent pipe part where worn most easily, the fluid pressure cloud and the optimum R/D have been gotten. All these provide basis for the research and design of carbon black dense phase pneumatic conveying system.

Formulation of Industry-Relevant Silicon Negative Composite Electrodes for Lithium Ion-Cells

Compared with graphite, silicon is a favourable alternative candidate due to a high specific capacity (3572 vs. 372 mAh g-1) and specific volumetric capacity (2081 vs. 779 mAh cm-3). However, large capacity fading and low cyclability of Si electrodes is a major issue. Several strategies have been undertaken to overcome these problems. One way is optimising the binder in order to cope at the molecular scale with the expansion and contraction of Si upon alloying and dealloying with Li. Since early works on CMC, several other works proposed alternative binders to CMC, most of them being polysaccharides and/or bearing COOH functional groups. Another way to improve the cycle life is using electrolytes containing a film-forming agent such as VC and/or FEC. Besides, electro-conductive additives also display an important influence for the performance of nano Si-based electrodes with high active mass loadings of about 2.5-3.3 mAh per cm². We found a significant improvement of the electrochemical performance (2000 mAh g -1 after 100 cycles for 2.5 mg of Si cm -2) by using reduced graphene oxide (rGO) or exfoliated graphite nanoplatelets instead of carbon black as the conductive additive [1,2]. The influence of electro-conductive additives is not only to play on the electronic conductivity but also on the micromechanics (stress distribution) of the composite films.In a further work, we aimed to design the formulation of these nano Si-based electrodes with high active mass loadings to wind some cylindrical cells. This way, Poly (acrylic-co-maleic) acid (PAMA) is used as a dispersant to improve the stability of electrodes slurries. Sedimentation test, electrical measurement, SEM-EDX observations as well as rheological measurements show that a more homogeneity distribution of carbon black (CB) inside the stack of Si particles is reached with presence of PAMA. However, there is an optimal amount of PAMA due to the competition in the adsorption of PAMA and Carboxylmethyl cellulose (CMC) at the surface of the CB particles. Upon cycling with capacity limitation (1200 mAh per g of Si), the optimized electrode formulation at lab scale could achieve more than 400 cycles with surface capacity ~2.5-3.3 mAh cm-2. At the pilot scale, the improvement of adhesion of the tape to the current collector by using Styrene-co-Butadiene rubber copolymer latex (SB) helps to maintain long cycle life while by calendaring is detrimental to electrochemical properties. [3] On the whole, the pilot-made electrodes show a lower cycle life than the labe-made electrode as a consequence of poorer CB distribution, likely due to the larger volume and longer processing time involved. Acknowledgements Financial support provided by the European Commission (EC), through the project EuroLiion (NMP3-SL-2010-265368) is gratefully acknowledged.