The Additivity and Stability of Carbon Signatures Obtained by Evolved Gas Analysis

Evolved Gas Analysis (EGA) profiles are evaluated as a tool to classify carbonaceous aerosols for source apportionment studies. EGA is a method of characterizing carbonaceous aerosols according to their volatility. In this study the stability and additivity of EGA profiles were examined explicitly for the purpose of determining the applicability of EGA characterization to chemical mass balance techniques. Samples collected in a vehicle tunnel were subsequently exposed to particle-free (filtered) and particle-laden ambient air. The EGA profile did not change for tunnel samples exposed to filtered ambient air. By contrast, for tunnel samples exposed to particle-laden (unfiltered) ambient air, the resultant EGA profile was not the direct sum of the ambient and tunnel profiles. Specifically, the low-volatility carbon peak evolved at a lower temperature than the same peak in the unexposed tunnel samples. The change in evolution temperature was independent of carbon mass loading. Although evolution temperatures of characteristic peaks shifted, both the ambient and the tunnel profiles could be classified into three characteristic peaks, corresponding to high-, intermediate-, and low-volatility carbon. Additivity of ambient samples yielded an uncertainty of 13% within a given peak. Additivity of the tunnel samples subsequently loaded with ambient aerosol yielded an uncertainty of 19% within a given peak.     

Estimating ambient particulate organic carbon concentrations and partitioning using thermal optical measurements and the volatility basis set

We introduce a new method to estimate the mass concentration of particulate organic carbon (POC) collected on quartz filters, demonstrating it using quartz-filter samples collected in greater Pittsburgh. This method combines thermal-optical organic carbon and elemental carbon (OC/EC) analysis and the volatility basis set (VBS) to quantify the mass concentration of semi-volatile POC on the filters. The dataset includes ambient samples collected at a number of sites in both summer and winter as well as samples from a highway tunnel. As a reference we use the two-filter bare-Quartz minus Quartz-Behind-Teflon (Q-QBT) approach to estimate the adsorbed gaseous fraction of organic carbon (OC), finding a substantial fraction in both the gas and particle phases under all conditions. In the new method we use OC fractions measured during different temperature stages of the OC/EC analysis for the single bare-quartz (BQ) filter in combination with partitioning theory to predict the volatility distributions of the measured OC, which we describe with the VBS. The effective volatility bins are consistent for data from both ambient samples and primary organic aerosol (POA)-enriched tunnel samples. Consequently, with the VBS model and total OC fractions measured over different heating stages, particulate OC can be determined by using the BQ filter alone. This method can thus be applied to all quartz filter-based OC/EC analyses to estimate the POC concentration without using backup filters.

© 2016 American Association for Aerosol Research     

Distribution of carbon black in natural rubber/acrylic rubber blends

Distributions of carbon black in 30/70% (w/w) natural rubber (NR)/acrylic rubber (ACM) blends were investigated as a function of the carbon black content and type using a dynamic mechanical thermal analysis (DMTA) technique. Two different types of carbon black (N220 and N330) were used, and 10–50 phr carbon black was compounded to the rubber blends. From the DMTA thermograms of various blends, the weight fractions of carbon black in the NR and ACM phases were calculated. Carbon black was unevenly distributed in the rubber blend. It preferred to migrate into the NR phase, regardless of the amount of carbon black that was used. By increasing the carbon black content, the weight fraction of carbon black in the NR phase decreased whereas that in the ACM phase increased. A change in the type of carbon black from N220 to N330 significantly decreased the weight fraction of carbon black in the NR phase, but it was not sufficiently strong to affect the tensile properties and hardness of the rubber blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:248–256, 2006     

Oxidative degradation of carbon blacks with nitric acid: II. Formation of water-soluble polynuclear aromatic compounds

Furnace black and acetylene black were oxidized with concentrated nitric acid at 100 °C for prolonged periods. The oxidized carbon black was dissolved/dispersed into alkaline solution and was size-fractionated into six fractions by ultrafiltration. The yields of the fractions revealed that oxidized furnace black contains oxygenated polynuclear aromatic compounds with a variety of molecular sizes, but oxidized acetylene black consists of only a great quantity of the largest size fraction, probably carbon black particles, and a scarce amount of the smallest size fraction. With oxidized furnace black, elemental compositions of all fractions except the largest molecular-size fraction were independent of the period of oxidation, suggesting that each fraction possesses a similar molecular structure. Noncarbon constituents such as oxygen and hydrogen increased with decreasing molecular size. The mean molecular weights of fractions were estimated to be in a range from ca. 400 to 1200 and more on the basis of elemental and functional group analyses. ¹³C-NMR and IR analysis showed that the molecules of fractions comprise phenolic, carboxylic, nitro, perhaps quinonic carbonyl groups, and aromatic carbons, but no aliphatic carbons. Ultraviolet and visible spectra of fractions denoted that absorption at higher wavelengths increased with increasing the molecular weights, indicating extension in the conjugated aromatic ring system. On the basis of the experimental results molecular structure models for the fractions were proposed.     

A vehicle testing programme for calibration and validation of an evaporative emissions model

A vehicle testing programme has been designed in order to calibrate and validate an empirical evaporative emissions model developed in previous work. To this aim, a large number of “targeted” tests have been performed on four vehicles covering a wide range of the model input parameters such as fuel volatility, ambient temperature, fuel tank and carbon canister size, fuel system materials. The fair agreement between modelled and measured values demonstrates that “bottom-up” modelling work and “top-down” vehicle testing may be combined to predict evaporative emissions on a vehicle level.     

Effect of carbon black structure on the effectiveness of carbon black thermal interface pastes

Thermal pastes are needed for improving thermal contacts. The structure of carbon black, as described by the DBP value, governs the effectiveness of the black as a thermally conductive solid component in a thermal paste, as shown for pastes with a polyol ester vehicle. Carbon black with a lower DBP value (i.e., a lower structure) is more effective, as shown by a higher value of the thermal contact conductance measured across copper surfaces of roughness 15 μm. This is because a carbon black with a lower structure gives a smaller bond-line thickness, which is preferably less than 3 μm. In addition, this is because a lower structure gives a lower viscosity for the paste, thereby promoting conformability. The carbon black volume fraction has an optimum value for attaining maximum thermal conductance. A lower structure results in a higher value of the optimum carbon black volume fraction, due to the viscosity effect. For the same type of carbon black, this optimum is higher when the paste is tested between rougher surfaces. By using Tokaiblack #3800 carbon black (with DBP value 60 ml/g and optimum carbon black content 15 vol.%), a thermal paste that is more effective than the previously reported paste with Vulcan XC72 carbon black (with DBP value 188 ml/g and optimum carbon black content 2.4 vol.%) has been attained.     

Influence of irradiation crosslinking on the self‐heating and conduction of an acetylene carbon black filled high‐density polyethylene composite in the electric–thermal equilibrium state

The electric self‐heating and conduction behaviors of a high‐density polyethylene/acetylene carbon black composite crosslinked with electron‐beam irradiation are studied with respect to the electric field and ambient temperature. On the basis of scaling arguments, the critical fields and current densities for the onsets of self‐heating and global electrical breakdown are discussed with respect to the intrinsic resistivity at a given ambient temperature as well as the irradiation dosage. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Evolved Gas Analysis of Secondary Organic Aerosols

Secondary organic aerosols have been characterized by evolved gas analysis (EGA). Hydrocarbons selected as aerosol precursors were representative of anthropogenic emissions (cyclohexene, cyclopentene, 1-decene and 1-dodecene, n-dodecane, o-xylene, and 1,3,5-tri-methylbenzene) and of biogenic emissions (the terpenes α-pinene, β-pinene and d-limonene and the sesquiterpene trans-caryophyllene). Also analyzed by EGA were samples of secondary, primary (highway tunnel), and ambient (urban) aerosols before and after exposure to ozone and other photochemical oxidants. The major features of the EGA thermograms (amount of CO₂ evolved as a function of temperature) are described. The usefulness and limitations of EGA data for source apportionment of atmospheric particulate carbon are briefly discussed.     

炭黑填充HDPE的力学性能和微波加热性能

为了提高HDPE（高密度聚乙烯）的微波加热性能,将炭黑和HDPE共混制备了复合试样,测试了试样的微波加热性能和机械性能,并用扫描电镜（SEM）观察了试样的断面形态。结果表明,当试样中炭黑用量超过一个临界值后,试样的升温速率随着炭黑用量的增加而显著上升。该临界值和作用微波的功率有关,当微波功率为100W时,临界炭黑的质量分数为9％,200W时为7％,400W时为3％。试样的拉伸强度和模量在炭黑的质量分数低于13％时保持不变,在超过13％后,拉伸强度和模量随着炭黑用量的增加而升高。试样的断裂伸长率在炭黑的质量分数小于7％时保持不变,在炭黑的质量分数超过7％以后下降非常快。     

Simultaneous transmission and absorption photometry of carbon-black absorption from drop-cast particle-laden filters

Simultaneous transmissivity and absorptivity measurements were carried out in the visible at a laser wavelength of 532?nm on drop-cast, carbon-black-laden filters under ambient (laboratory) conditions. The focus of this investigation was to establish the feasibility of this approach to estimate the mass absorption coefficient of the isolated particles and compare results to earlier work with the same carbon-black source. Transmissivity measurements were carried out with a laser probe beam positioned normal to the particle-laden filter surface. Absorptivity measurements were carried out using a laser-heating approach to record in time the sample temperature rise to steady-state and decay back to the ambient temperature. The sample temperature was recorded using a fine-wire thermocouple that was integrated into the transmission arrangement by placing the thermocouple flush with the filter back surface. The advantage of this approach is that the sample absorptivity can be determined directly (using laser heating) instead of resolving the difference between reflectivity (filter surface scattering) and transmissivity. The current approach also provides the filter optical characteristics, as well as an estimate of filter effects on the absorption coefficient due to particle absorption enhancement or shadowing. The approach may also be incorporated into other filter-based techniques, like the particle/soot absorption photometer, with the simple addition of a thermocouple to the commercial instrument. For this investigation, measurements were carried out with several blank uncoated quartz filters. A range of solution concentrations was prepared with a well-characterized carbon black in deionized water (i.e., a water-soluble carbonaceous material referred to as a surrogate black carbon or ‘carbon black’). The solution was then drop cast using a calibrated syringe onto blank filters to vary particle loading. After evaporation of the water, the measurements were repeated with the coated filters. The measurement repeatability (95% confidence level) was better than 0.3?K for temperature and 3?×?10^?5 mW for laser power. From the measurements with both the blank and coated filters, the absorption coefficient was determined for the isolated particles. The results were then compared with an earlier investigation by You et al. and Zangmeister and Radney, who used the same carbon-black material. The measurements were also compared with Lorenz–Mie computations for a polydispersion of spherical particles dispersed throughout a volume representative of the actual particles. The mass absorption coefficient for the polydispersion of carbon-black particles was estimated to be about 7.7?±?1.4?m² g^?1, which was consistent with the results expected for these carbon black particles.     

Electrical properties of carbon black filled polyethylene

Resistivity and dielectric constant of polyethylene/carbon black compounds were measured from room temperature to 140°C. Within the polyethylene melting region a PTC/NTC (positive followed by negative temperature coefficients) phenomenon is observed, whose intensity depends on the type of carbon black, its concentration and other parameters. Reproducibility of the PTC phenomenon in polyethylene compounds containing a single type of carbon black is rather low. However, by using mixtures of carbon blacks differing appreciably in their particle size, remarkable reproducibility improvements can be achieved. Several other aspects are also discussed in the present paper covering current-voltage relationships in these materials, comparison of PTC curves with DSC thermograms upon heating and cooling, and dielectric constant-temperature relations. The carbon black concentration giving the optimum PTC intensity can be predicted approximately from room temperature data.     

THE CHEMICAL MASS BALANCE METHOD FOR ESTIMATING ATMOSPHERIC PARTICLE SOURCES IN SOUTHERN CALIFORNIA

The greater Los Angeles metropolitan area (the South Coast Air Basin) historically has had a severe air pollution problem whose visible symptom is a dense smoke-like haze mixed with fog (smog). More than 25 years ago, Friedlander and his associates began attempts to characterize the detailed chemistry of smog particles, and to interpret these results in terms of source emissions. Source apportionment was formalized using a “model”, called the chemical mass balance (CMB). The method has been applied periodically since 1968, with major attempts reported in 1975 and 1994, based on large field studies. Despite improvements in particulate sampling and chemical characterization, data availability and major emissions changes, the CMB results qualitatively remain similar. Only broad source categories are identifiable, but they generally make up more than 75% of the total mass concentration. These include primary motor vehicle emissions, suspended (earth) crustal material, and secondary species of ammonium nitrate and sulfate salts. The decoupling of source components in the ambient aerosols suggests that extreme PM events are significantly influenced by factors other than simple mixing and dispersion. Carbonaceous material from combustion emissions and secondary atmospheric production also represent a significant fraction of southern California airborne particles. The carbon fraction includes a complex mixture of soot or black carbon, oxygenated compounds, as well as traces of polycyclic aroma tics. The last group has been of particular interest because of its apparent common origins and its carcinogenic activity. The major contributor to primary carbonaceous material is motor vehicles, The observations also indicate that a significant fraction of carbon derives from contemporary sources such as vegetation or cooking of meat. The CMB has been used to guide regulatory strategies for particulate emissions management. The method could be improved substantially with more extensive source profile development, as well as improved knowledge about the origins of the organic fraction.     

Vergleich von Milchfetten aus der Kristallisationsfraktionierung und einem kontinuierlichen Fraktionierungsverfahren mittels überkritischem Kohlendioxid

Comparison of Milk Fat Fractions Obtained by Crystallization with those Obtained in a Continuous Fractionation Process Using Supercritical Carbon Dioxide Several milk fat fractions obtained by crystallization from molten fat as well as milk fat fractions obtained in a new continuous fractionation process using supercritical carbon dioxide have been investigated by GC, HPLC und DSC. The influence of its fatty acid and triglyceride compositions on the crystallization and melting behaviour is discussed. The milk fat fractions obtained by crystallisation tend to crystallize in two distinct main triglyceride group. A separation even into three fractions is shown in the melting thermograms. The milk fat fractions obtained by the fractionation using supercritical carbon dioxide have much less tendency to separate into triglyceride groups. Obviously, this continuous fractionation process using supercritical carbon dioxide can be improved. Therefore, it seems to be possible to obtain milk fat fractions with different triglyceride compositions and better physical properties.     

Ionothermal carbonization of sugars in a protic ionic liquid under ambient conditions

A mesoporous carbon has been synthesized by an ionothermal carbonization of glucose or fructose at low temperature under ambient pressure. The success of this ionothermal approach was based on the suppressed solvent volatility and latent acidity of a protic ionic liquid. The carbonaceous material obtained can be applied to conformal carbon coatings and carbon composite fabrications.     

相对分子质量分布对双峰聚乙烯薄膜树脂等温结晶动力学的影响

研究了2种双峰聚乙烯薄膜树脂（9455F1 W和9455F1 100）的等温结晶动力学行为,并讨论了相对分子质量分布的双峰相对含量对结晶过程的影响。结果表明,2种样品都呈现双峰分布的特征,且其相对分子质量相差不大,但高/低相对分子质量级分含量不同;其中,9455F1 W样品的高相对分子质量级分的相对含量大,9455F1 100样品的低相对分子质量级分的相对含量大;随低相对分子质量级分含量的增加,样品的结晶速率常数增大,半结晶时间减小,结晶速率增大。     

炭黑分散度检测标准GB/T 18251应用过程中遇到的问题浅析

主要对GB/T 18251—2019《聚烯烃管材、管件和混合料中颜料或炭黑分散度的测定》标准中给出的炭黑分散度检测过程中试样厚度范围、厚度测量方法及切片法中试样形状、试样幅宽、试样制备过程中遇到的问题做了讨论研究。试样厚度是制备试样的一个重要参数,标准中未给出具体测量方法,应予以补充,建议采用显微镜测量法。标准中给出的炭黑分散度试样厚度范围（20±10）μm不合适,实际检测过程中发现能用于试验的试样厚度小于10μm。标准中未给出切片法制备试样的形状和幅宽,建议使用正方形试样,幅宽4 mm,切片过程中可能会遇到无法切到指定厚度范围的试样,可以采用低温冷冻后再切样的办法解决。     

Non-isothermal programmed pyrolysis studies of oil sand bitumens and bitumen fractions: 1. Athabasca asphaltene

Characteristic pyrolysis thermograms for 12 gases have been obtained for Athabasca asphaltene, using a combination of non-isothermal, programmed pyrolysis (ambient to 1200 K at 3 K min^?1) and gas chromatography. Such thermograms provide information for the characterization of asphaltenes in the form of gas yields, specific rates and Arrhenius kinetic parameters. All thermograms comprised more than one peak. These peaks lie in distinct temperature zones and are associated with primary and secondary cracking and coking reactions. Useful insights into the structure of Athabasca asphaltene and, indirectly, the composition of its pyrolytic cokes have been obtained. The present results provide a body of useful reference material which may be useful for monitoring processes, which may chemically modify the asphaltene fraction of bitumens and heavy oils, and for comparative studies of asphaltenes from a variety of sources.     

BaTiO3／环氧树脂／玻璃纤维复合材料介电性能研究

本文运用热压工艺制备了BaTiO3（BT）／环氧树脂／玻璃纤维和BaTiO3／炭黑／环氧树脂／玻璃纤维复合材料,研究了温度、填料含量和交流频率对复合材料的介电性能的影响。结果表明,复合材料的介电常数（εr）和介电损耗（tanδ）随肌体积分数的增加而升高。当肌体积分数为17％时,复合材料在1MHz下的εr和tanδ分别为7.88和0.027。当炭黑的含量为1.0％时,明含量为17％的复合材料εr和tanδ分别为11.0和0.035。随着频率的升高,复合材料的εr降低,而介电损耗升高。复合材料的εr随温度升高而增加。     

不同粒径胶粉的成分分析及在胎面胶中的应用

通过热重法和红外光谱分析及测定硫含量和粒径分布等方式对用超低温粉碎法制备的不同粒径胶粉的成分进行了分析,并开展了其在商用车轮胎胎面胶中的加工应用研究.结果表明,4种不同胶粉中的挥发分、有机物、炭黑和灰分含量均差别较小,其中有机物质量分数在61％～65％之间,炭黑质量分数在28％～30％之间,含硫质量分数在2％左右,粒径...     

Evidence in biomass burning smoke for a light-absorbing aerosol with properties intermediate between brown and black carbon

Biomass combustion produces black carbon (BC) and brown carbon (BrC) aerosols that contribute substantially to warming the Earth’s atmosphere. Accurate knowledge of their emissions and absorption per unit mass (mass absorption cross-section; MAC) can be used to quantify the radiative impact of these combustion products. We isolated particles generated from laboratory biomass burning fires by morphology and found that some particles from biomass burning do not correspond to either BC or BrC according to common operational definitions. Unlike BrC, these particles strongly absorb red light, with a MAC and spectral dependence of absorption between that of BrC and BC. They also have intermediate volatility: they survive thermodenuding at 250?°C but do not heat to incandescence in a single particle soot photometer (SP2) instrument. We also found evidence for intermediate properties in ambient wildfire smoke from the 2013 Rim Fire in California. More work is needed to understand how much this intermediate material contributes to atmospheric light absorption from typical combustion, whether or not it corresponds to “tar balls,” and how it may affect previous MAC measurements that were attributed to enhanced absorption by transparent coatings.

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