Estimating black carbon aging time-scales with a particle-resolved aerosol model

Understanding the aging process of aerosol particles is important for assessing their chemical reactivity, cloud condensation nuclei activity, radiative properties and health impacts. In this study we investigate the aging of black carbon containing particles in an idealized urban plume using a new approach, the particle-resolved aerosol model PartMC-MOSAIC. We present a method to estimate aging time-scales using an aging criterion based on cloud condensation nuclei activation. The results show a separation into a daytime regime where condensation dominates and a nighttime regime where coagulation dominates. There is also a strong dependence on supersaturation threshold. For the chosen urban plume scenario and supersaturations ranging from 0.1% to 1%, the aging time-scales vary between 11 and 0.068 h during the day, and between 54 and 6.4 h during the night.     

An inter-comparison of black-carbon-related instruments in a laboratory study of biomass burning aerosol

Black carbon (BC)-containing particles are the most strongly light absorbing aerosols in the atmosphere. Measurements of BC are challenging because of its semi-empirical definition based on physical properties and not chemical structure, the complex and continuously changing morphology of the corresponding particles, and the effects of other particulate components on its absorption. In this study, we compare six available commercial continuous instruments measuring BC using biomass burning aerosol. The comparison involves a Soot Particle Aerosol Mass Spectrometer (SP-AMS), a Single-Particle Soot Photometer (SP2), an aethalometer, a Multiangle Absorption Photometer (MAAP), and a blue and a green photoacoustic extinctiometer (PAX). An SP-AMS collection efficiency equal to 0.35 was measured for this aerosol system. The corrected SP-AMS BC mass measurements agreed within 6% with the SP2 refractory BC mass values. Two regimes of behavior were identified for the optical instruments corresponding to high and low organic/BC ratio. The mass absorption cross-sections (MAC) measured varied from 26% to two times the instrument default values depending on the instrument and the regime. The presence of high organic aerosol concentration in this system can lead to overestimation of the BC mass by the optical instruments by as much as a factor of 2.7. In general, the discrepancy among the BC measurements increased as the organic carbon content of the BC-containing particles increased.

© 2018 American Association for Aerosol Research     

Characterization and demonstration of a black carbon aerosol mimic for instrument evaluation

This study describes the characterization of a H₂O-dispersible, highly-absorbing carbonaceous nanomaterial that mimics the morphological and spectroscopic properties of aged black carbon aerosol (BC). When atomized from aqueous suspension, the material forms particles with a collapsed morphology resembling aged soot or BC. The material is >90 percent elemental carbon and has a mass absorption coefficient (MAC) and spectral dependence consistent with BC values published in the literature. The MAC at a wavelength of 532?nm decreased monotonically from 8.5 to 5.8?m² g^?1 for aerosol with mobility diameters between 150?nm to 500?nm. The single scatter albedo (SSA) at wavelengths of 405?nm and 660?nm was a function of both wavelength and mobility diameter and increased from 0.1 to 0.4 with mobility diameters between 150?nm to 400?nm. The Ångström absorption exponent (AAE) between λ?=?405?nm and 780?nm decreased monotonically from 1.4 to 0.6 for aerosol with mobility diameters between 150?nm to 400?nm. We demonstrate that this material can be used for fast, efficient calibration of aerosol photoacoustic spectrometers and for evaluation of spectroscopic-based measurements of aerosol mass concentration using in-situ photoacoustic spectroscopy (PAS) and filter-based light attenuation measurements for up 50?µg m^?3, enabling inter-method and inter-laboratory instrument comparison.

Copyright © 2019 American Association for Aerosol Research     

碳纳米管炭黑天然橡胶复合材料的制备与性能研究

碳纳米管以其特殊的结构与优异的性能成为橡胶补强的理想填料。本文中我们采用两种不同牌号的碳纳米管(分别为Flotube 7000、9011)与炭黑N660作为实验原料,制备了碳纳米管/炭黑/天然橡胶复合材料,并对其性能进行了探讨。结果发现：碳纳米管的加入能明显提高复合材料的定伸应力,具有一维取向排列且长径比较大的Flotube 7000(以下简称7000)对力学性能的提高程度最大。且我们将碳纳米管7000、9011分别与炭黑N660并用,对于提高复合材料的导热性能并没有如我们预期的一样存在所谓的“叠加关系”甚至是“协同效应”,而是对于提高复合材料导热有着一定的“负协同效应”。     

橡胶用炭黑物理性能检验的注意事项

讨论了影响橡胶用炭黑物理性能检验结果的主要因素及操作过程中的注意事项。试验表明，在橡胶用炭黑物理性能检验过程中，生胶塑炼及混炼的温度、时间和辊距、硫化胶的停放时间、强伸性能测试时胶样的可变形长度等均对最终的检验结果有一定程式的影响。只有熟悉标准要求，严格把握各个操作环节，才能将人为和环境因素的影响降至最低限度。     

Elucidating the interactions between carbon nanotubes and carbon black with styrene butadiene rubber

The reinforcement mechanism of carbon nanotubes (CNT) on styrene butadiene rubber is studied through dynamic and swelling tests. Compounds containing carbon black (CB) and an unfilled one were prepared for comparison purposes. The dynamic properties are interpreted through the Maier-Göritz model to distinguish the contributions of stable and unstable crosslinks to the storage modulus, finding that the unstable ones become more relevant in samples containing a CNT concentration higher than 5 phr. In addition, the crosslinks density estimated by swelling and the stable contribution obtained with dynamical properties present the same tendency with the CNT amount. The former presents lower values, which can be explained considering that only stable crosslinks remain in the equilibrium-swollen state, while in the second one both stable and unstable are considered. In addition, differences in the filler-polymer interaction mechanisms are observed according to the morphology and aspect ratio of CNT in contrast to CB.     

Interfacial and conductive properties of liquid marbles coated with carbon black

Liquid marbles coated with carbon black are reported first. Carbon black is a strongly hydrophilic material; an energetic reasoning for coating water drops with the hydrophilic powder is supplied. The shape of marbles is well-described by the oblate spheroid model. The effective surface tension of the marbles is reported. The factors exerting an influence on the effective surface tension of marbles are discussed. Scaling laws governing the marbles' shape are presented. Electrical properties of liquid marbles coated with carbon black are reported first.     

Formation and evolution of the carbon black network in polyethylene/carbon black composites: Rheology and conductivity properties

We report a detailed investigation on the effect of carbon black (CB) morphology on network formation and evolution in high‐density polyethylene/CB composites. There were three types of networks in our study, the electrical network in the solid state and the electrical and rheological networks in the melt state. The evolution of the network in the polymer melt was traced by simultaneous electrical resistivity (R) and dynamic rheology testing. An oscillation strain sweep was used to investigate the network stability with a large strain. We found that with high‐structure CB with a branched morphology, it was easier to form a filler–polymer or filler–filler network than with low‐structure CB with a spherical morphology in the composite melt. The high‐structure CB network was more stable with a large strain compared to the low‐structure one. Meanwhile, the low‐structure CB aggregates had stronger capability of movement and re‐aggregation in the polymer melt. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39953.     

Electrical properties of crosslinked polyethylene/carbon black switching composites as a function of morphology and structure of the carbon black

The electrical resistivity of a radiation-crosslinked polyethylene/carbon black switching composite was investigated as a function of carbon black content and temperature. Carbon blacks of different morphology and microstructure behaved differently regarding the electrical resistivity. A HG black, highly porous and structured, imparts high conductivity to its composite mixture at a low degree of loading, whereas nonporous acetylene EQ black of like structure requires a higher degree of loading to impart the same conductivity. The PTC (positive temperature coefficient) effect anomaly was smaller for HG black than for EQ black. It was found that the PTC anomaly was heightened when a combination of the two different carbon blacks was mixed into the composites. Suggestions as to the causes for this particular behavior are made with reference to the electron micrography and other parameters for microstructure of the two carbon blacks.     

Separation of the desired product from aerosol flows in the manufacture of carbon black (a review)

The current trends of the development of studies and technologies for the separation of a target product from aerosol flows in the manufacture of carbon black are surveyed. Studies oriented to decreasing material and power consumption in the processes of carbon black production are analyzed. An analysis of aerosol coagulation mechanisms and the dependence of the rate constant of coagulation on the physicochemical properties of dispersed carbon is given. The precipitation of the target product in a cyclone collector is considered. Studies directed toward an improvement in the quality and effectiveness of thermoresistant filtering materials and bag-type filters with their use are analyzed. Some results of the experimental studies of the filtration of a dispersed carbon aerosol in a layer of porous carbon granules are given.     

NBR对白炭黑-炭黑填充补强SSBR性能的影响

研究了不同用量的丁腈橡胶(NBR)对白炭黑-炭黑填充溶聚丁苯橡胶(SSBR)性能的影响。研究证明：随着NBR用量的增加,混炼胶硫化速度加快,正硫化时间呈减小趋势,压缩生热和永久变形率缓慢增大,拉伸强度略有下降,但是可以提高耐磨耗性能;当加入NBR的量为4份时可以同时优化胶料湿滑性能和滚动阻力。     

Effect of chemical interaction between surface oxidized carbon black and carboxylated nitrile rubber on dynamic properties

Monsanto rheometric, dynamic mechanical, and solvent swelling studies indicate that functional groups of oxidized carbon black chemically react with carboxylated nitrile rubber (XNBR) when heated at high temperature for prolonged time. The reinforcing ability of the surface oxidized carbon black, measured by failure and hysteresis properties, is higher than the nonoxidized counterpart. © 1995 John Wiley & Sons, Inc.     

A thorough study on the relationships between dispersion quality and viscoelastic properties in carbon black filled SBR compounds

A series of carbon black filled SBR 1500 compounds (without curatives) were prepared in carefully controlled lab‐mixing conditions so that filler content ranged from 0 to 50 phr, with the usual compounding ingredients. Carbon Black agglomeration and dispersion quality were assessed through an advanced microscopic technique with automated data treatment. Linear and nonlinear viscoelastic properties were evaluated using a closed cavity torsional rheometer, equipped for Fourier Transform rheometry experiments. In the linear viscoelastic regime, dynamic moduli mastercurves were derived from experiments in the 60−160°C temperature range. In the nonlinear viscoelastic regime, complex modulus and torque harmonics variation with strain amplitude were investigated at 100°C and frequency 0.5 and 1.0 Hz. Relationships between dispersion quality, carbon black loading and mixing parameters were investigated so that dispersion appears better when the filler loading is above a critical level that to some extent (but not exactly) corresponds to the theoretical percolation threshold (around 13%). Linear and nonlinear viscoelastic measurements demonstrate and quantify the role played by plasticizing compounding ingredients, that is, processing oil, stearic acid and other chemicals, with nearly no significant effect of mixing energy. At least 10−15 phr carbon black are necessary to recover the modulus loss associated with this plasticizing effect. Nonlinear results and particularly the torque harmonics reveal a number of details as to how the compounding ingredients do affect the viscoelastic behavior, with expectedly the carbon black playing the major role. By fitting results with mathematically simple models, all of the observed effects can be summarized in a rather limited number of parameters so that the effects of compounding ingredients can be studied in details. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

N234/N660炭黑并用对炭黑在SBR1712橡胶中分散及物理性能影响

通过不同比例的N234/N660炭黑在SBR1712橡胶中的分散状态及物理性能分析,发现N234/N660以不同比例并用时分散度均较其加权平均值明显提高,扫描电镜观察胶料的脆断面发现炭黑结团数目降低,说明N234/N660炭黑的并用能促进炭黑在胶料中的分散。同时炭黑并用混炼胶的各项物理性能高于其加权平均值,说明炭黑分散度的提高对于胶料的各项物理性能的提高有明显效果。不同比例的N234/N660炭黑并用时均产生了协同效应。     

不同门尼黏度反式-1，4-聚异戊二烯与炭黑的相互作用及其对硫化胶性能的影响

研究了不同门尼黏度反式-1,4-聚异戊二烯(TPI)与炭黑N 330的相互作用及其对TPI硫化胶物理机械性能和疲劳性能的影响.结果表明,随TPI生胶门尼黏度增大,炭黑结合胶含量减少,炭黑分散性变差,增强作用减弱.未填充炭黑TPI硫化胶的100%定伸应力和拉伸强度随TPI门尼黏度的增大而显著提高;用炭黑增强后,不同门尼黏度TPI硫化胶的100%定伸应力和拉伸强度差别不大.不同门尼黏度TPI硫化胶的压缩生热和压缩永久变形在填充炭黑后均增大,其中低门尼黏度的增加幅度显著大于高门尼黏度者;不同门尼黏度TPI硫化胶压缩生热的变化主要由炭黑与橡胶之间的作用引起.生胶门尼黏度为50～80的TPI硫化胶的动态疲劳性能较好.     

Electrical and thermal properties of composite of liquid crystalline polymer filled with carbon black

The electrical resistivity and thermal conductivity of a liquid crystalline polymer (LCP) filled with a commercial carbon black (CB) of various volume fractions (?) is investigated. The percolation threshold (?_c) is found at about 3%, and the resistivity (ρ) as a function of (? ? ?_c) satisfies the exponential function. Although the pure LCP is highly anisotropic in thermal and mechanical properties after processing, the composite samples exhibit no preferential direction for electrical conduction. Samples of ? below ?_c exhibit a negative temperature coefficient of resistivity while those above ?_c show almost no temperature dependence from room temperature to 200°C. In addition, the samples at lower ? have higher thermal conductivity in the LCP flow direction than those measured in the transverse and thickness directions, and they approach the same value at higher ?. This result indicates that preferential molecular alignment of the matrix LCP is responsible for the behavior of the thermal conductivity of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1549–1555, 2001     

聚苯胺/乙炔炭黑多孔类棒状复合材料的制备及电化学性质

以纳米乙炔炭黑在盐酸掺杂的反应体系中的聚集体为硬模板,原位吸附化学氧化法制备了聚苯胺/炭黑复合材料。实验结果显示,聚苯胺复合物为表面附着大量纳米颗粒的类棒状结构,且棒与棒间富有孔隙。复合材料分解温度在350℃左右。循环伏安曲线表现出该复合材料法拉第准(赝)电容有良好的电极可逆性,在5,10 mA/cm2电流密度下,单电极比电容高达376 F/g和311 F/g。     

炭黑填充溶聚丁苯橡胶的动态黏弹性能和流变性能

采用橡胶加工分析仪和恒速型双筒毛细管流变仪研究了炭黑填充不同牌号溶聚丁苯橡胶(SSBR)的动态黏弹性能和流变性能。结果表明,当炭黑用量增加至20份时,SSBR-T 2003混炼胶出现炭黑网络结构,当炭黑用量增加至25份时,SSBR-2305混炼胶出现炭黑网络结构;随着炭黑用量的增加,SSBR-T 2003混炼胶的储能模量(G’)和损耗模量(G″)增大,Payne效应越明显,而SSBR-2305混炼胶的G’和G″也均增大,但未发生突增,Payne效应的变化微弱;不同用量炭黑填充的SSBR混炼胶均呈现假塑性流体的特性,且SSBR-T 2003混炼胶的非牛顿性较显著;SSBR-T 2003混炼胶的流动界面状态基本稳定,而SSBR-2305混炼胶的流动在高剪切速率下发生黏/滑的转变。     

Dielectric properties of SBR vulcanizates loaded with HAF carbon black and BaTiO3 ceramics

The influence of HAF carbon black and BaTiO₃ ceramic powder contents in SBR vulcanizates on the dielectric constant (ε′) at different frequencies and at fixed temperature of 303 K is studied well in this article. The temperature dependence of the ac conductivity (σ_ac) was also studied. ε′ appreciably decreases as frequency increased for both filled and unfilled SBR vulcanizates. At each frequency, ε′ gradually decreased with BaTiO₃ loading, but its change at any fixed frequency with BaTiO₃ filler loading is not uniform. For HAF group ε′ (at loading ≥ 40 phr), drops rapidly with frequency. Meanwhile, it increased appreciably beyond a certain HAF filler loading (≈ 20 phr). Experimental values of the dielectric constant of both BaTiO₃ and HAF contents were compared with those calculated by using Tsangaris, Clausius and Bruggman models. Tsangaris model with simple modifications was applied and a fairly good agreement was obtained. The HAF particles or aggregates was found to take the shape of oblate ellipsoids with the minor axes parallel to the applied frequency as detected from the decreasing behavior of the depolarizing factor (Y) with HAF contents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2227–2234, 2007     

Evidence for electro-chemical interactions between multi-walled carbon nanotubes and human macrophages

Carbon multi-walled nanotubes (MWCNTs) may have several dangerous effects on different cell systems, but the mechanisms responsible for their cytotoxicity are not well known yet. At present, very little is known about the electrical interactions between nanomaterials and cells. We aimed to verify whether MWCNT electrical properties could affect the so called “charge-sensitive” cell parameters, interacting with cellular electrical activity. Human macrophages were challenged with two fully characterised MWCNT samples, one tested as-prepared (MWCNT), the other one purified (by annealing at 2400 °C) and better electro-conductive (a-MWCNT). Our findings show that a-MWCNTs are less cytotoxic but possess a higher inflammatory potential, as compared to MWCNTs. Moreover, only annealed and better conductive MWCNTs affect significantly the mitochondrial membrane polarity, the intracellular pH and the reorganisation of cytoskeleton actin filaments, cell functions strictly dependent on electro-chemical mechanisms. Based on our results, there is evidence for electro-chemical interactions taking place between cell membranes and electro-conductive MWCNTs. Such a specific behaviour could have wide-range applications in the biomedical field, not only concerning those cellular systems (neuronal and bone cells) sensitive to electrical stimuli, but also other cell systems.