Cationic photopolymerization of epoxides containing carbon black nanoparticles

The active centers responsible for cationic photopolymerizations are essentially non-terminating, and continue to propagate after the illumination is ceased. In this contribution, the mobility of the long-lived cationic active centers is investigated for the cure of epoxides containing carbon black nanoparticles. Concentration profiles for the cationic active centers produced during illumination were coupled with an analysis of the active center reactive diffusion during the post-illumination period, revealing that migration of the active centers leads to cure beyond the illuminated depth. A kinetic analysis yielded predicted cure times for coatings of varying thickness and carbon black loading, showing good agreement with experimental results obtained for photopolymerizations of cycloaliphatic diepoxide coatings containing a monodisperse carbon black with mean hydrodynamic radius of 29.2 nm. These results indicate that the long lifetimes and reactive diffusion of cationic active centers may be used for effective curing of coatings containing carbon black nanoparticles. This comprehensive approach could be applied to other opaque nanocomposite systems.     

Novel amphiphilic carbon black composite nanoparticles from TEMPO-terminated polymer and TEMPO-terminated block copolymer grafted carbon black

The purpose of this study was to modify the surface characteristics of CB so as to prevent the aggregation of CB to provide the dispersibilities in either H₂O or organic solvent. In this study, five kinds of hydrophilic TEMPO-terminated polymer, hydrophobic TEMPO-terminated polymer and amphiphilic TEMPO-terminated block copolymer were synthesized. The five kinds of TEMPO-terminated polymers were: (1) poly(4-acetoxystyrene) (PAS-T), (2) poly(4-hydroxystyrene) (PHS-T), (3) polystyrene (PS-T), (4) poly(4-acetoxystyrene)-block-polystyrene (PAS-b-PS-T), (5) poly(4-hydroxystyrene)-block-polystyrene (PHS-b-PS-T). These TEMPO-terminated polymers with desired molecular weights and specific structures were synthesized by using the method of living radical polymerization in the presence of 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO). These TEMPO-terminated polymers and TEMPO-terminated block copolymers were grafted onto the surface of CB through a reaction of polymer radicals trapped by CB, so as to obtain the TEMPO-terminated polymer/CB and TEMPO-terminated block copolymer/CB composite nanoparticles. Various variables such as reaction time, reaction temperature, amount of TEMPO-terminated polymer, molecular weight of TEMPO-terminated polymer and amount of CB all of which influenced the grafting efficiency were investigated. Besides, the stability of the composite nanoparticles, which dispersed in H₂O or organic solvent, was investigated by laser light scattering. The amphiphilic composite nanoparticles, PHS-T/CB and PHS-b-PS-T/CB, which dispersed well in both H₂O and organic solvent, were synthesized successfully in this work.     

Phase changes in zirconia refractories used in carbon black manufacturing

Conclusions The serviceability of zirconia blocks in carbon-black production chamber linings working with gaseous fuels is some 2 1/2–3 times better than that of magnesia-chrome refractories.During use, the exposed surface of the zirconia refractory is subject to slow decomposition of zircon with formation of ZrO₂ and SiO₂.Translated from Ogneupory, No. 5, pp. 24–28, May, 1969.     

Voltage switchable surface-modified carbon black nanoparticles for dual-particle electrophoretic displays

In order to produce the black color for electrophoretic display (EPD) applications in dual-particle systems, a primary-like sized carbon black (PCB) surface modification method is developed and the electrophoretic properties of the resulting functionalized particles are reported. The PCB surface was chemically modified by hydroxylation and subsequent esterification. The final capping material of the PCB nanoparticle surface was a bulky fatty oleic acid, which was expected to improve dispersion stability and to produce electrostatic chargeability in a low dielectric medium. The zeta potential calculated from the measured electrophoretic mobility with a charge control agent was −31 mV. When the negatively chargeable oleic acid-capped PCB nanoparticles mixed with the positively chargeable polymer-coated white TiO₂ nanoparticles, the PCB nanoparticles showed electrophoretic movement at an applied bias voltage of less than 5 V, which demonstrated potential application for very low voltage operation in EPDs.     

Carbon black nanoparticle instillation induces sustained inflammation and genotoxicity in mouse lung and liver

Background

Widespread occupational exposure to carbon black nanoparticles (CBNPs) raises concerns over their safety. CBNPs are genotoxic in vitro but less is known about their genotoxicity in various organs in vivo.

Methods

We investigated inflammatory and acute phase responses, DNA strand breaks (SB) and oxidatively damaged DNA in C57BL/6 mice 1, 3 and 28 days after a single instillation of 0.018, 0.054 or 0.162 mg Printex 90 CBNPs, alongside sham controls. Bronchoalveolar lavage (BAL) fluid was analyzed for cellular composition. SB in BAL cells, whole lung and liver were assessed using the alkaline comet assay. Formamidopyrimidine DNA glycosylase (FPG) sensitive sites were assessed as an indicator of oxidatively damaged DNA. Pulmonary and hepatic acute phase response was evaluated by Saa3 mRNA real-time quantitative PCR.

Results

Inflammation was strongest 1 and 3 days post-exposure, and remained elevated for the two highest doses (i.e., 0.054 and 0.162 mg) 28 days post-exposure (P < 0.001). SB were detected in lung at all doses on post-exposure day 1 (P < 0.001) and remained elevated at the two highest doses until day 28 (P < 0.05). BAL cell DNA SB were elevated relative to controls at least at the highest dose on all post-exposure days (P < 0.05). The level of FPG sensitive sites in lung was increased throughout with significant increases occurring on post-exposure days 1 and 3, in comparison to controls (P < 0.001-0.05). SB in liver were detected on post-exposure days 1 (P < 0.001) and 28 (P < 0.001). Polymorphonuclear (PMN) cell counts in BAL correlated strongly with FPG sensitive sites in lung (r = 0.88, P < 0.001), whereas no such correlation was observed with SB (r = 0.52, P = 0.08). CBNP increased the expression of Saa3 mRNA in lung tissue on day 1 (all doses), 3 (all doses) and 28 (0.054 and 0.162 mg), but not in liver.

Conclusions

Deposition of CBNPs in lung induces inflammatory and genotoxic effects in mouse lung that persist considerably after the initial exposure. Our results demonstrate that CBNPs may cause genotoxicity both in the primary exposed tissue, lung and BAL cells, and in a secondary tissue, the liver.     

Subchronic inhalation toxicity of gold nanoparticles

Risk, associated with nanomaterial use, is determined by exposure and hazard potential of these materials. Both topics cannot be evaluated absolutely independently. Realistic dose concentrations should be tested based on stringent exposure assessments for the corresponding nanomaterial taking into account also the environmental and product matrix. This review focuses on current available information from peer reviewed publications related to airborne nanomaterial exposure. Two approaches to derive realistic exposure values are differentiated and independently presented; those based on workplace measurements and the others based on simulations in laboratories. An assessment of the current available workplace measurement data using a matrix, which is related to nanomaterials and work processes, shows, that data are available on the likelihood of release and possible exposure. Laboratory studies are seen as an important complementary source of information on particle release processes and hence for possible exposure. In both cases, whether workplace measurements or laboratories studies, the issue of background particles is a major problem. From this review, major areas for future activities and focal points are identified.     

Using carbon black nanoparticles to dye the cationic‐modified cotton fabrics

Carbon black (CB) aqueous dispersion was prepared and used to dye the cationic‐modified cotton fabrics through exhaust dyeing process. The effects of CB concentration, CB nanoparticles size, dyeing bath pH, dyeing time and dyeing temperature were investigated. The color yields of dyed fabrics were evaluated on Kubelka‐Munk value K/S. The surface morphologies of cationic modified and nonmodified cotton fabrics were measured by video microscope. The fabrics presented 18.9 of the color yield with the dyeing conditions: the dyeing solution contained 2% o.w.f. CB and dyeing at 80°C for 30 min with pH 13 using a 50 : 1 liquor ratio. The images of the video microscope demonstrated a clear surface profile for the cationic‐modified cotton fabrics dyed with smaller CB particle size solutions. These results indicated that CB nanoparticles were suitable for dyeing the cotton fabrics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fluorination of carbon black

The kinetics of the fluorination of carbon black and the properties of the graphite fluoride prepared are discussed in comparison with those of graphite and petroleum coke. An appreciable weight increase is observed in the fluorination of carbon black even at room temperature because of the large surface area. The increment is approximately proportional to the surface area except for the heat-treated carbon black, and more than twice that of adsorption corresponding to the monolayer of fluorine. An iodide ion is oxidized to iodine by the adsorbed fluorine in the products. The reactivity of carbon black with fluorine decreases with increasing the crystallinity, and the product prepared from the lower crystalline carbon black is less thermostable. The reaction kinetics of carbon black with fluorine is similar to that of graphite, but the diffusion controlled regions are not present in the former. The fluorine content of the graphite fluoride prepared increases with decreasing heat-treatment temperature and with increasing reaction temperature. The crystallinity of the product increases with increasing heat-treatment temperature and with increasing reaction temperature. The heat of immersion of the product inn-butyl alcohol is equal to that of polytetrafluoroethylene.     

Reactions of carbon black. Part I. Nonthixotropic carbon black compositions

The solution polymerization of butyl acrylate in the presence of a furnace black was found to produce a stable dispersion of carbon black which showed Newtonian flow, while the mixture prepared by mixing the same carbon black into a solution of poly(butyl acrylate) homopolymer had a large degree of thixotropy. A marked change in the viscosity of the reaction mixture was also observed at an early stage of polymerization when the initial mixture which was a moist mass with no fluidity, turned to a fluid easily stirred. The change in viscosity and the transition in flow behavior were carefully followed with a rotary cylinder type viscometer. The non-Newtonian initial mixture was found to turn to a Newtonian fluid at low conversion of the monomer. Beside the adsorption of the homopolymer onto the surface of carbon black particles, which would occur also in mechanical mixing, the change in the flow behavior was estimated to be caused by the change in the shape and the size of the dispersed carbon black particles due to the change in the condition of the surface of the particles by which growing polymer radicals, as well as initiator radicals, were captured.     

Surface modification of carbon black nanoparticles by dodecylamine: Thermal stability and phase transfer in brine medium

Stable aqueous dispersions of carbon black (CB) nanoparticles were prepared by developing a generic bilayer approach to the CB phase-transfer method using commercial Avanel as a surfactant. CB was oxidized using ammonium persulfate, and dodecylamine (DDA) was grafted onto this carbon core using N,N-dicyclohexylcarbodiimide as a coupling agent. The covalent bond between CB and DDA was confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and thermogravimetric analysis. The average diameter of the primary carbon nanoparticles after chemical modification increased from 15 to 20 nm, as determined by high-resolution transmission electron microscopy. Dispersions of the modified CB was stable in organic solvents and were thermally stable in saline water when Avanel was used as a surfactant. The Avanel coating on the CB particles enabled the design of carbon materials with high colloidal stability, as evidenced by dynamic light scattering measurements and the breakthrough characteristics of the coated material in sandstone rocks.     

Distribution of carbon black in SBR

The distribution of HAF carbon black in SBR was studied with the electron microscope and Fraunhofer diffraction. The interparticle distance between black aggregates is 8000 Å at 20 phr and 7000 Å at 40 phr, but above 60 phr it spreads broadly in the vicinity of 4000 Å. The size of black aggregates at 20 phr extends from 300 Å to 3000 Å, and the average diameter is 1200 Å. At 40 phr and 60 phr, black trends to aggregate more than at 20 phr and the average diameter is about 1500–1600 Å; the maximum diameter exceeds 5000 Å. In a black aggregate, there are about 40 spherical particles independently of filler concentration. From the relation between the size and interparticle distance, the connection of black aggregates initiates at 40 phr level and affects the physical properties of filled rubber.     

废轮胎热解炭黑与工业炭黑的粒径及化学组成

用激光粒度分析仪测定了废轮胎热解炭黑的粒径分布,用扫描电子显微镜、X-射线衍射法及X-射线光电子能谱法分析了热解炭黑和工业炭黑的形态、表面化学组成以及表面碳元素的结合状况。结果表明,热解炭黑的粒径分布是添加在轮胎中各种型号工业炭黑粒径分布的叠加。热解炭黑表面形态和组成接近于工业炭黑N660;热解炭黑的表面附着更多的有机物以及ZnO、ZnS等无机物,且随着热解温度的升高,附着的有机物含量减小,无机物中ZnO含量减小,ZnS含量增多。     

Structural transformations in carbon nanoparticles

The structure of icosahedral carbon (diamond and onion-like) nanoparticles is discussed. It is shown that, in carbon nanoparticles, the reversible structural transformations of icosahedral particles into particles with a shell structure can occur without breaking of bonds or disturbance of their topological integrity. New structural models are proposed and analyzed for carbon nanoparticles. The diffusionless mechanism of reversible transformations between diamond-like and onion-like particles is proposed for the first time.     

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.     

白炭黑/炭黑配比对天然橡胶基复合材料性能的影响

以硅烷偶联剂作为白炭黑(SiO_2)的表面改性剂,以改性SiO_2/炭黑作为天然橡胶(NR)的混合填料,采用半有效硫化体系制备了NR基复合材料。研究结果表明:当m(SiO_2)∶m(炭黑)=20∶40时,硫化胶中混合填料分散均匀,并且硫化胶的撕裂强度(62 k N/m)相对最高、交联密度相对最大且佩恩效应相对较弱。     

Surface modification of carbon black to facilitate suspension polymerization of styrene and carbon black

To carry out suspension polymerization of styrene in the presence of carbon black, an effective method was introduced to modify carbon black using nitric acid for oxygen treatment. The surface modification of carbon black with oxidation was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy (SEM), which demonstrated that the chemical structure of carbon black has clearly changed. Compared with pristine carbon black (CB), SEM illustrates that the aggregation phenomenon of modified carbon black (MCB) was clearly weakened. After modification, the aggregation and inhibition effects of MCB on the polymerization of polystyrene/modified CB (PS/MCB) composite particles are obviously weakened. The lipophilicity of CB after modification was also increased during the synthesis of PS/MCB. The oxidized CB was successfully dispersed by polystyrene using in situ suspension polymerization. The dispersion and dosage of MCB in PS/MCB composite particles was greatly improved over that of CB in PS/CB composite particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46387.     

Electrochemical characterization of carbon black

Electrochemical characterization of carbon black suspensions enabled us to distinguish the presence of phenolic, quinone, carboxylic and lactone groups. In addition, we were able to determine the position of the Fermi level for several carbon blacks, which was found to depend on their acidity.The intensity of each characteristic electrochemical wave gives the concentration of these functional group at the surface of the carbon, while the potential at which the redox process occurs, reflect the energy state of these functional groups.The results of polarographic and voltammetric determination of the functional properties of the surface of eight samples of carbon blacks are given. Chemical modification of the samples changes electrochemical properties of their surface.