我国新工艺湿法造粒炭黑完全取代干法造粒炭黑

近几年来,我国炭黑行业在降低原材料消耗、防治环境污染、调整产业结构、能源综合利用等方面取得了长足发展,并走在世界前列。从本期开始,我刊将开辟"环保炭黑"专题,宣传炭黑行业在节能减排、防治污染等工作中取得的成效。     

Graphene/carbon black/natural rubber composites prepared by a wet compounding and latex mixing process

The extensively used latex mixing approach to prepare graphene can improve the graphene dispersion but meets some challenges in the preparation of high content carbon black filled rubber system like a rubber tire. Owing to the high melt viscosity of the rubber/graphene masterbatch, the dispersion of carbon black is not perfect during twin-roll mixing and some aggregates will be formed. Here we proposed a wet compounding process, combined with ultrasonically assisted latex mixing, named as the WCL method to prepare reduced graphene oxide/carbon black/natural rubber (rGO/CB/NR) composites. The morphological observations confirmed that both graphene and carbon black can be evenly dispersed in the rubber composites. The incorporation of rGO also improves the hardness, thermal conductivity and anti-aging properties of the composites. The rGO/CB/NR composites prepared by the WCL method possess better mechanical properties compared to conventional latex mixing. The entanglement-bound rubber tube model was utilised to understand the reinforcing mechanism.     

干/湿相转化法制备复合型聚合物电解质的研究

采用干 /湿相转化法制备了用于锂离子电池的复合型聚合物隔膜。通过扫描电镜和吸液实验研究了添加不同无机纳米粉料对由该法制得的聚合物隔膜孔径及结构的影响。用 8种隔膜组装了电池 ,测试了其电化学性质。结果证实无机纳米材料的加入导致了隔膜形成后在孔径大小、孔径分布和孔隙率等结构参数上的差异 ,添加无机纳米材料的隔膜具有适宜的孔结构和较好的充放电性能 ,具有实际应用价值     

Silica-filled NR compounds prepared by dry and wet masterbatches with different mixing times

Silica-filled NR compounds are prepared by mixing rubber with organic-networked silica and additives such as curatives, processing and coupling agents, and stabilizer in a dried state (dry-mixed NR, DNR) and mixing a silica-NR wet masterbatch prepared in liquid phase with the additives (wet-mixed NR, WNR). The effects of mixing method and time of DNR and WNR compounds on their cure, process, tensile, and dynamic properties are investigated. The mixing of DNR crushes silica aggregates to smaller ones, but also forms occasionally large ones, while the mixing of WNR produces small aggregates without forming larger ones because silica aggregates are already covered with rubber. The high silica dispersion, suppressed silica aggregation, low Payne effect, and low-loss modulus of the WNR compounds prepared by mixing for a sufficient time result in their low viscosity, high scorch safety, and low rolling resistance without sacrificing other rubber properties.     

A temperature-responsive carbon black nanoparticle prepared by surface-induced reversible addition-fragmentation chain transfer polymerization

A reversible addition-fragmentation chain transfer (RAFT) agent, 2-{[(dodecylsulfanyl)carbonothioyl]sulfanyl}propanoic acid (DSCTSP), was immobilized on the hydroxyl-functionalized carbon black (CB) surface via a direct condensation reaction, producing CB-DSCTSP. Then, RAFT polymerizations were carried out on carbon black surface using the CB-DSCTSP as a chain transfer agent. Poly(N-isopropylacrylamide) (PNIPAAm) chains were grown from the carbon black surface by a surface-induced reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. FT-IR, ¹H NMR, TGA, TEM, and dynamic light scattering were used to characterize the carbon black grafted with poly(N-isopropylacrylamide) (CB-g-PNIPAAm). Dispersion experiment showed that CB-g-PNIPAAm had a good solubility in water. ¹H NMR, AFM and dynamic light scattering measurements showed that CB-g-PNIPAAm behaved a reversible temperature-responsive property in water.     

橡胶用炭黑及特种炭黑主要性能对比

宁波德泰化学有限公司是一家专业生产炭黑的中外合资企业。公司依托中石化华东分公司的乙烯焦油和宁钢的煤焦油等资源优势,在消化吸收国内外先进炭黑生产技术的基础上,开发国内最先进的大型五段反应器生产技术,进口了许多关键生产设备和检测设施,并在原料油预处理、DCS微机控制技术、高温空气预热器、显热回收、高效脉冲袋滤、湿法造粒、炭黑精制处理、尾气综合利用、     

Vinyl polymerization by carbon black,VI. Physico-chemical characteristics of poly(N-vinylcarbazole) prepared by modified and unmodified carbon black

The polymerization initiating activity of carbon black N220, unmodified as well as modified by pretreatment with various protonic and aprotonic acids has been examined in regards to N-vinylcarbazole polymerization. The physico-chemical characteristics of the polymer obtained by these catalyst systems have been investigated by I.R., X-ray, ¹H-NMR, ¹³C-NMR, gel permeation chromatography and thermal analysis measurements. Under certain conditions the resultant polymer shows some partial insolubility in methylethylketone. Contrary to the usual belief, this is not due to any stereochemical difference between the polymeric entities as observed by ¹³C-NMR spectrum analysis of the methylethylketone insoluble fraction of the polymer.     

A comparison of the effects of traditional and wet mixing processes of rubber on metal friction and wear

Prolonged operations of mixers cause wear of mixer rotors and chamber walls and affect the clearances between the rotors and chamber walls, which reduce the mixing effect, weaken the dispersion of the packing, and affect the quality of rubber products. In this study, the effects of traditional mixing and wet mixing on the friction and wear of the chamber, and the properties of rubber were compared by using 60 phr of a silica natural rubber formulation system. The results show that a silanization reaction occurs between silica and the silane coupling agent during the mixing process and that the reaction rate is fastest when the temperature of the mixing chamber is maintained between 145 and 155°C for 1 min during the mixing process. The products of silanization reaction are ethanol and water; the water vapor that forms at high temperatures corrodes the mixing chamber of the internal mixer and aggravates wear and tear. Due to the high dispersion of silica during wet mixing, the silanization reaction is more complete and water vapor is produced at a high temperature. Hence, the rubber compound obtained by wet mixing has more significant wear on the mixing chamber.     

A comparison of dry and wet grinding of a quartzite ground in a small batch ball mill

Classical grinding models involve the selection function (S), which gives the rates of breakage of particles of each screen size fraction, and the breakage function (B), which describes the instantaneous size distributions of fragments produced when the particles of each fraction are broken. In order to investigate the differences between dry and wet grinding as far as the selection and breakage functions are concerned, batch grinding experiments were performed on both dry and wet bases, on the same material, a quartzite, in a small ball mill under similar experimental conditions.On a dry basis, the rates of breakage were found to be time invariant and independent of the size environment in the mill. It is logical to postulate a similar behavior for the breakage function. On a wet basis (65% solids), an increase of the rates of breakage was observed as grinding proceeds. This behavior is essentially due to the variation of the size environment within the mill. This increase in breakage rates was, however, less and less important as the particle size decreased and was not observed for the smallest particles tested. These points were confirmed by considering the disappearance kinetics of samples of different screen size fractions of quartzite injected in the mill during the batch grinding of a limestone. Moreover, it is not impossible that the breakage function could also vary with grinding time, giving rise to finer instantaneous size distributions of fragments as the size environment in the mill becomes finer. As an overall result, wet grinding has appeared more selective than dry grinding for coarse material, while it did not produce more schlamms.     

单体接枝改性炭黑填充NBR复合材料的研究

采用单体接枝改性法制备炭黑填充型NBR复合材料，并对其性能进行研究。结果表明，在NBR胶乳与炭黑的混合体系中加入适当的单体M[丙烯酸丁酯（BA）或甲基丙烯酸甲酯（MMA）]和引发剂，可以使单体M与NBR分子链发生接枝反应的同时也与炭黑表面的活性基团发生反应，从而制备NBR／M／炭黑复合材料；采用该方法制备的NBR／M／炭黑复合材料的炭黑分散性良好，物理性能和热稳定性优异。     

Polymer composites prepared by compression molding of a mixture of carbon black and nylon 6 powder

The results of an experimental study on the effect of processing variables and filler concentration on the electrical resistivity of conductive composites based on nylon 6 filled with carbon black are reported. A typical percolation behavior in the effect of electroconductive filler content on the resistivity was found. The electrical resistivity of the composites is > 10¹² ohm°Cm unless the carbon black content reaches the percolation threshold at ∼9 wt%, beyond which the resistivity decreases markedly by as much as twelve orders of magnitude. Two parameters of molding process—temperature and time—were shown to have a notable effect on the resistivity of composites, whereas pressure has no influence on this property in the pressure range considered. There is no sharp variation in the density due to the onset of percolation, and the hardness of samples is not influenced by the presence of the filler.     

Analyzing the quality of carbon nanotube dispersions in polymers using scanning electron microscopy

The ability to examine conducting filler particles in an insulating polymer matrix by scanning electron microscopy (SEM) was investigated. The detection of selected secondary electrons is necessary to resolve sub-micron scale filler particles, but not every SEM detector seems to be able to monitor the small changes introduced by the conducting filler particles. The influence of SEM parameters and the challenge of image interpretation in view of the apparent lack of appropriate information in literature are discussed. In accordance with other experiments on light element samples, all monitored electrons seem to be emitted within approximately 50 nm of the sample depth and no information is accessible from deeper regions even by increasing the acceleration voltage.     

Structures and gas separation properties of asymmetric polysulfone membranes made by dry,wet, and dry/wet phase inversion

Integrally skinned asymmetric gas separation membranes were prepared by (i) dry, (ii) wet, and (iii) dry/wet phase inversion processes. The membranes were cast from a polysulfone/methylene chloride/1,1,2-trichloroethane/2-methyl-2-butanol casting system. Wet and dry/wet phase inversion membranes were quenched in methanol. Membranes made by dry/wet phase inversion using convective evaporation showed optimum gas separation performance. The average O₂/N₂ and He/N₂ selectivities of these membranes were within 85% of those determined for a dense, solution-cast polysulfone film, suggesting that the ultrathin skin layers were essentially defect free. The average apparent skin layer thickness of all samples tested was 270 Å. Scanning electron photomicrographs revealed that optimum membranes made by dry/wet phase inversion consist of an ultrathin skin layer, a tightly packed nodular transition layer, and an open-cell, sponge-like substructure. Dry/wet phase inversion membranes prepared by free-standing evaporation resulted either in high flux and low selectivity membranes or essentially defect-free membranes with fluxes lower than those made by convective evaporation. Dry-phase inversion membranes exhibited extremely low gas fluxes due to thick (17.5 μm) skin layers. On the other hand, wet phase inversion membranes showed O₂/N₂ selectivities < 1, indicating that gas transport was determined by pore flow through skin layer defects.     

Reversible transformation of hydrophobicity and hydrophilicity of aligned carbon nanotube arrays and buckypapers by dry processes

Dry treatment using a combination of UV and ozone can readily change the surface of vertically aligned carbon nanotubes from superhydrophobic to superhydrophilic. This treatment is also effective for buckypapers. Heating in a vacuum at an elevated temperature (650-750 °C) can reverse the surface state from superhydrophilic to superhydrophobic. The UV & ozone treatment causes the least amount of damage to the stripe-like carbon nanotube patterns. The effect of rough surface on apparent contact angles of CNT forests was discussed to explain the origin of superhydrophilicity and superhydrophobicity.     

The zeta potential arising from cationic surfactant adsorption in non-aqueous dispersions of carbon black

The effect of counterion size of the cationic surfactants CTAC, CTAB and CTAS on the sign and magnitude of the zeta potential on Austin black dispersions in n-heptane and benzene were investigated. Zeta potentials were determined using single-particle microelectrophoresis. Velocities were measured at the stationary levels; all the conditions for true electrophoresis were satisfied. The measured electrophoretic mobilities were converted to zeta potentials using the Hückel equation, corrected for relaxation effects. Results for n-heptane dispersions and a series on quaternary ammonium salts differing only in the size of the counterions, indicated a dependence on the sign and magnitude of the zeta potential on the nature of the counterion. The smallest counterion (chloride) gave negative zeta potentials, while the larger counterions yielded positive zeta potentials which increased with increasing size of the counterions. Similar trends were observed with the benzene dispersions. An ion-induced surface dipole mechanism was postulated to explain the observed phenomena.     

Electrical properties of polyethylene and carbon black particle blends prepared by gelation/crystallization from solution

Composite materials based on low molecular weight polyethylene (LMWPE), ultra-high molecular weight polyethylene (UHMWPE) and carbon black (CB) particles were prepared by gelation/crystallization from solution. The positive temperature coefficient (PTC) intensity for the 90/10 (LMWPE/UHMWPE) composition exceeded five orders of magnitude for the specimens heat-treated at a suitable temperature, which was almost equal to that observed with LMWPE-CB blends prepared by a kneading method. In comparison with LMWPE-CB blends, much promoted reproducibility of PTC effect and inhibition of the negative temperature coefficient (NTC) effect were achieved.     

湿法炭黑干燥强化和湿法脱硫技术改进

炭黑生产线由2万吨／年扩能到3万吨／年的改造中遇到的一个棘手问题,是如何提高干燥机干燥能力。在现生产线中,干燥机人口紧接造粒机出口,而干燥机出口又紧接斗式提升机。现场布置的限制,加大干燥机是不可能的。只有通过对现有干燥机进行强化改进、提高干燥机能力来解决这个生产瓶颈问题。     

Recycling of dry and wet polyamide 6

Recycling of polycondensation polymers can give rise to secondary materials with good mechanical properties only if a careful drying is carried out before the melt reprocessing operations. The presence of humidity provokes the hydrolytic chain scission of the macromolecules and the consequent decrease of molecular weight and properties. In this work, the drying step was substituted by the addition of an antioxidant that is able to protect the macromolecules because it is the autioxidant is more prone to hydrolysis, thus removing the water from the melt. The mechanical properties of polyamide 6 reprocessed more times in wet conditions and in the presence of this stabilizer are even better than those obtained reprocessing the dry polyamide. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1899–1903, 2002