Metal cation complexes as dispersing agents for non-aqueous powder suspensions

Formulation of high solid load slurries is an important aspect in achieving dense, high quality ceramic green body shaping by additive manufacturing techniques. To this end, the understanding and control of interparticle interactions in non-aqueous organic slurry systems is imperative. With nanosized powders gaining increasing interest, particle stabilization by long-chain polymeric dispersants is undesirable due to the high exclusion volume associated and the subsequent decrease in the maximum solid load of the suspension. In this study, we focus on the stabilization mechanisms provided by metal cation complexes in methyl ethyl ketone and isopropanol-based spinel slurries. Special focus is given to chromium (III) 2-ethylhexanoate. Hemi-micelle formation at the powder surface in methyl ethyl ketone is suggested as a highly efficient stabilization mechanism. Complexes of metal dopant cations may open new pathways towards future advances in ceramic slurry formulation, especially in the field of additive manufacturing. Furthermore, the importance of solvation forces is discussed on the basis of the protic or aprotic character of the solvent used.     

密炼机自动混炼生产中的干扰因素

讨论了容量在270L以上的密炼机全自动控制混炼过程中的干扰因素。全自动控制混炼中仍有干扰，投料环节和混炼温度（包括混炼起始温度和环境温度）都可能对混炼产生干扰。为避免干扰，优化混炼，在原“最佳粘度”的混炼流变理论基础上提出，必须同时具有“最佳粘度”和“最佳热历程”才能保证生产品质较好且稳定均一的混炼胶。     

白炭黑分散剂HST在全钢载重子午线轮胎中的应用

试验研究白炭黑分散剂HST在全钢载重子午线轮胎中的应用,并与白炭黑分散剂ST进行对比。结果表明,在白炭黑填充胶中加入白炭黑分散剂HST,可以明显改善白炭黑的分散性,提高胶料的加工性能,对硫化胶的物理性能无不良影响,可提高胎面胶的抗湿滑性能,对成品轮胎的强度和耐久性能无影响;其应用效果与白炭黑分散剂ST基本相当。     

Electrically conductive and super-tough polyamide-based nanocomposites

Polymer nanocomposites can exhibit superior multi-functional properties if they possess phase separated morphology at the nanoscale. Despite the huge potential of these materials, there are several fundamental issues including the ultimate microstructures, which need to be resolved to tailor different physical and mechanical properties required for specific applications. A ‘ternary nanocomposites’ approach is adopted to prepare electrically conductive and super-tough¹ (in terms of notched impact energy) hybrid polymer nanocomposites (polyamide 6/carbon nanotube/elastomer) that possess better properties than either of the constituent binary polymer nanocomposites (polyamide 6/carbon nanotubes and polyamide 6/elastomer). The individual roles of the nano-fillers involved in achieving multi-functionality are emphasized. The level of property enhancements of ternary nanocomposites depends essentially on the microstructure inducing a volume exclusion effect and the capability of fillers to activate the plastic deformation mechanisms in the matrix.     

均匀剂在橡胶加工过程中的应用效果

研究了3种国外均匀剂产品40MS,60NS和M40和NR／BR及NR／BR／SBR共混体系中的应用效果。试验结果表明,均匀剂可改善胶料的加工流动性,降低胶料的门尼粘度和混炼功耗,提高混炼胶的相态均匀性,缩短炭黑的混入时间,对硫化胶的物理性能影响不大,相对而言,均匀剂M40对NR／BR和NR／BR／SBR共混体系的综合性能影响效果最好,当用量为3份时可达到加工性能和使用性能的最佳平衡。     

Interfacial chemistry using a bifunctional coupling agent for enhanced electrical properties of carbon nanotube based composites

A bifunctional coupling agent (BCA) containing one oxazoline and one benzoxazinone group was applied to promote a reaction between polyamide 12 (PA12) and multiwalled carbon nanotubes (MWCNTs) during melt mixing. With this modification, the MWCNT content needed for the electrical percolation was significantly reduced by more than a factor of three. For amino functionalized MWCNT–PA12 composites adding 1 wt.% BCA electrical percolation was reached at only 0.37 wt.% MWCNTs compared to 1.0 wt.% without BCA. With the help of a model reaction, the covalent attachment of the BCA to the MWCNTs could be shown by thermogravimetric analysis (TGA) and via fluorescence spectroscopy. Model compounds were applied containing either only the oxazoline or the benzoxazinone group to show that the better electrical properties in the PA12–MWCNT composites were a result of a covalent bond between the polymer and the nanotube which only takes place when the BCA was used. In addition, significantly higher electrical conductivity values were obtained by the addition of BCA as well with amino functionalized as with nonmodified commercial MWCNTs. This surprising result was attributed to the significant hydroxy group content on the surface of those commercial MWCNTs.     

均匀剂在橡胶加工中的应用

介绍了均匀剂的发展现状,讨论了均匀剂的应用效果和作用机理,并对橡胶共混均匀性的研究方法进行了综述。     

Co-compatibilising effect of carbon nanotubes and liquid isoprene rubber on carbon black filled natural rubber/polybutadiene rubber blend

Abstract

Bis-(triethoxysilylpropyl)-tetrasulfane functionalised carbon nanotubes (t-CNTs) were used as compatibiliser along with liquid isoprene rubber (LIR) in the natural rubber (NR)/polybutadiene rubber (BR) blend. Their reinforcing and compatibilising effects were evaluated by mechanical, fatigue crack growth resistance properties and blend homogeneity. Scanning electron microscope and transmission electron microscope showed enhanced interfacial adhesion between the binary rubber phases and improved dispersion of the minor phase in the rubber blend respectively with the co-existence of LIR and carbon nanotubes. The tensile strength of the carbon black (CB) filled NR/BR blend reached its optimum when 3 phr CB was replaced with an equal amount of t-CNTs in the presence of 7 phr LIR, while the fatigue crack growth resistance property achieved its maximum in the presence of 3 phr LIR. This interesting co-compatibilisation behaviour of t-CNTs and LIR suggests that t-CNTs have a better effect than CB with the assistance of LIR, which is an effective plasticiser in the NR/BR blend.     

掺加CD-88水泥分散剂提高水泥磨的粉磨效益

试验和生产实践证实：在粉磨系统掺加CD－88水泥分散剂要有正确的方法、步骤，才能实现提高磨机的台时产量，降低电耗，提高粉磨效率和水泥强度等目的。     

基于方差分析对橡胶开炼机智能炼胶过程的优化

本文采用青岛科技大学自行研制的XK-160E型开炼机智能炼胶实验平台。在最优的开炼机炼胶工艺参数组合(辊距0.7mm,辊速30r/min,速比1:1.1,辊筒温度71℃,混炼时间20min)下,通过SPSS统计分析软件的方差分析选取具有显著性影响的前三项,即辊距、辊速、速比来进行研究。对实验数据进行分析处理,得到工艺参数在炼胶过程中最优的变化趋势,最终实现对橡胶开炼机智能炼胶过程的优化。     

硅烷偶联剂在橡胶中的应用研究进展

介绍硅烷偶联剂在橡胶工业中的应用研究进展,展望橡胶用硅烷偶联剂的发展趋势和应用前景。硅烷偶联剂的使用大大提高了橡胶制品的综合性能,促进了无机填料在橡胶工业中的应用。目前橡胶用硅烷偶联剂主要种类为含硫烃基类、乙烯基类、甲基丙烯酰氧烷基类、氨烃基类和环氧烃基类。随着新型轮胎和橡胶制品的快速发展,市场对橡胶用硅烷偶联剂的性能和使用技术也提出更高的要求,尤其是轮胎绿色化进程的加快,对硅烷偶联剂的需求快速增长,以NXT为代表的新型硅烷偶联剂是未来橡胶用硅烷偶联剂的发展方向之一。     

软测量在橡胶混炼过程建模中的应用

介绍软测量技术在橡胶混炼过程中的应用。软测量技术的关键是建模，橡胶混炼过程建模主要有基于机理和基于数据驱动两种方法。由于混炼过程的复杂性，基于机理的建模方法在实际应用中受到限制，仅用于估算或定性分析；而基于数据驱动的建模方法对过程知识要求较低且具有自学习功能，因而得到快速发展。混炼过程模型还受辅助变量、数据预处理的影响，且模型建立后还需进行校正，目前对数据预处理和模型校正的研究还较少。     

炭黑分散剂HT-5在胎面胶中的应用

本文研究了炭黑分散剂HT-5在汽车胎面胶中的应用,试验结果表明：使用炭黑分散剂HT-5可以显著降低胶料的门尼粘度,延长焦烧时间,提高炭黑的分散性。在轮胎胎面胶配方中加入2.5份时,胶料的综合性能最好。     

Functionalized polypropylenes as efficient dispersing agents for carbon nanotubes in a polypropylene matrix; application to electromagnetic interference (EMI) absorber materials

Carbon nanotubes (CNTs) have been dispersed within polypropylene with the purpose to prepare electromagnetic interference (EMI) absorbers. In order to limit the reflectivity of the electromagnetic waves at the interface of the materials while achieving good absorbing properties, the CNTs concentration must be kept low (<3 wt%) which means that a perfect dispersion must be ensured. Since CNTs do not disperse well within apolar polymer matrices such as polypropylene, two compatibilizers bearing aromatic moieties, i.e. pyrene and pyridine, able to develop π-π interactions with the CNTs have been synthesized starting from polypropylene grafted by maleic anhydride (PP-g-MA). A masterbatch is first prepared by dispersion of CNTs within the compatibilizers by melt-mixing and coprecipitation followed by further dispersion within the PP matrix. Rheological and electromagnetic characterizations of the nanocomposites have demonstrated the efficiency of these compatibilizers to promote the dispersion of CNTs in PP and the good EMI shielding effectiveness of the PP matrix at a low CNTs concentration (2 wt%).     

Thermal conductivity of carbon nanotubes and their polymer nanocomposites: A review

Thermally conductive polymer composites offer new possibilities for replacing metal parts in several applications, including power electronics, electric motors and generators, heat exchangers, etc., thanks to the polymer advantages such as light weight, corrosion resistance and ease of processing. Current interest to improve the thermal conductivity of polymers is focused on the selective addition of nanofillers with high thermal conductivity. Unusually high thermal conductivity makes carbon nanotube (CNT) the best promising candidate material for thermally conductive composites. However, the thermal conductivities of polymer/CNT nanocomposites are relatively low compared with expectations from the intrinsic thermal conductivity of CNTs. The challenge primarily comes from the large interfacial thermal resistance between the CNT and the surrounding polymer matrix, which hinders the transfer of phonon dominating heat conduction in polymer and CNT.This article reviews the status of worldwide research in the thermal conductivity of CNTs and their polymer nanocomposites. The dependence of thermal conductivity of nanotubes on the atomic structure, the tube size, the morphology, the defect and the purification is reviewed. The roles of particle/polymer and particle/particle interfaces on the thermal conductivity of polymer/CNT nanocomposites are discussed in detail, as well as the relationship between the thermal conductivity and the micro- and nano-structure of the composites.     

Morphological, mechanical, and electrical properties as a function of thermal bonding in electrospun nanocomposites

Poly lactic acid (PLA) was electrospun with various concentrations of multi-wall carbon nanotubes (MWNT) and thermal bonding was utilized as a post-processing treatment to improve the mechanical and electrical properties of the nanofibrous mats. Thermally bonded fiber-fiber junctions were observed with scanning electron microscopy. An increase in either the strength or modulus of the PLA mats both with and without MWNTs was observed; the maximum modulus and maximum strength occur at different treatment conditions. The electrical conductivity of the MWNT loaded mats showed significant improvement after treatment just below the composite melting point.     

炼胶工序设备及工装的改进

从炼胶工序生产所用设备及工装存在的问题、改造的方案、实施的效果进行了阐述。着重介绍炼胶工序设备及工装的改进所带来的效果。对同行的生产具有一定的参考价值。     

改性粘土的偶联效果检测及其作为鞋用混炼胶增强剂的应用

以１％ＷＤ－５０硅烷偶联剂于８０℃处理３０ｍｉｎ的改性粘土为增强剂,用于增强鞋用混炼胶。实验结果表明,其增强效果接近日本产０号沉淀白炭黑的水平。     

Visualization of nanomechanical mapping on polymer nanocomposites by AFM force measurement

Nanocomposite based on an elastomer, natural rubber (NR), and pristine multi-walled carbon nanotubes (MWCNT) was prepared using a two-roll mill mixer. The high shearing stress induced homogeneous dispersion of 5 phr. MWCNTs in NR matrix. A procedure based on combination of Johnson-Kendall-Robert (JKR) contact mechanics and “two-point method” together with AFM force measurements, was successfully used to visualize nanomechanical mapping on the resulting nanocomposites. Topography, elastic modulus, and adhesive energy distribution maps were obtained at the same point and at the same time in a single scan. Such maps were successfully used to identify and characterize CNTs and NR regions in nanocomposites. The intermediate modulus region formed around CNTs was investigated on the quantitative evaluation in real space and demonstrated the existence of interaction between CNTs and NR matrix.