气相白炭黑对尼龙6性能的影响

采用偶联剂(3-氨丙基三乙氧基硅烷)对气相白炭黑进行表面处理,利用熔融共混法制备了尼龙6/气相白炭黑复合材料,并用透射电子显微镜(TEM)观察复合材料的微观结构,研究了气相白炭黑用量对复合材料的力学性能和耐热性的影响.结果表明,硅烷偶联剂可较好提高气相白炭黑和尼龙6的相容性,随着气相白炭黑的加入,复合材料的拉伸强度、弯曲强度、冲击强度和热变形温度等都有较大的提高,即使少量气相白炭黑也对尼龙6具有明显的增强和增韧作用.     

气相白炭黑对氟橡胶／硅橡胶共混胶性能的影响

采用气相白炭黑补强氟橡胶／硅橡胶共混胶。研究了气相白炭黑的用量和比表面积对氟橡胶／硅橡胶共混胶的力学性能、耐热老化性能和耐油性能的影响,并采用SEM观察了共混硫化胶的拉伸断面形貌。研究表明,随着气相白炭黑的用量从0份增加到50份,气相白炭黑的比表面积从120m^2·g^-1增大到380m^2·g^-1,共混胶的力学性能和耐油性能提高,而耐热老化性能下降;当气相白炭黑用量为40份,且比表面积为220m^2·g^-1时,共混硫化胶具有较好的综合性能。SEM照片表明,随着气相白炭黑用量增大,其在氟橡胶／硅橡胶共混胶中的分散均匀性下降;当气相白炭黑比表面积为220m^2·g^-1时,气相白炭黑的分散性较好。     

On-Line Characterization of Morphology and Water Adsorption on Fumed Silica Nanoparticles

The first wetting layer on solid nanoparticles has direct implications on the roles these particles play in industrial processes and technological applications as well as in the atmosphere. We present a technique for online measurements of the adsorption of the first few water layers onto insoluble aerosol nanoparticles. Atomized fumed silica nanoparticles were dispersed from aqueous suspension and their hygroscopic growth factors (HGF) and number of the adsorbed water layers at subsaturated conditions were measured using a nanometer hygroscopic tandem differential mobility analyzer (HTDMA). Particle morphology was characterized by electron microscopy and particle density was determined by mobility analysis. The HGFs of the size-selected particles at mobility diameters from 10 to 50 nm at 90% relative humidity (RH) varied from 1.05 to 1.24, corresponding to 2–6 layers of adsorbed water. The morphology of the generated fumed silica nanoparticles varied from spheres at 8–10 nm to agglomerates at larger diameters with effective density from 1.7 to 0.8 g/cm³ and fractal dimension of 2.6. The smallest spheres and agglomerates had the highest HGFs. The smallest particles with diameters of 8 and 10 nm adsorbed two to three water layers in subsaturated conditions, which agreed well with the Frenkel, Halsey, and Hill (FHH) isotherm fitting. In comparison to the small spheres or large agglomerates, the compact agglomerate structure containing a few primary particles increased the number of adsorbed water layers by a factor of ～1.5. This was probably caused by the capillary effect on the small cavities between the primary particles in the agglomerate.     

改性剂种类对白炭黑补强阻尼硅橡胶性能的影响

以阻尼硅橡胶母胶、气相法白炭黑、改性剂为原料,制成了热硫化阻尼硅橡胶。研究了羟基硅油、六甲基环三硅氮烷、乙烯基三乙氧基硅烷(A-151)、γ-氨丙基三乙氧基硅烷(KH 550)、γ-环氧丙氧基丙基三甲氧基硅烷(KH 560)及其并用对阻尼硅橡胶硫化性能、分散性能、力学性能和黏弹性能的影响。结果表明,硅烷偶联剂类改性剂能显著加快混炼胶的硫化速度、缩短硫化时间;羟基硅油、六甲基环三硅氮烷和KH 560作改性剂时白炭黑的分散效果良好,而采用A 151作改性剂时白炭黑填料网络的Payne效应较明显,但在宽温域(-120~100℃)范围内具有温度稳定性;不同改性剂并用对改善白炭黑分散性没有明显的协同作用;改性剂种类对硫化胶的力学性能影响不大;六甲基环三硅氮烷与KH 560并用时,硅橡胶的阻尼性能最高。     

Permeation Properties in Laminated Membranes

Abstract

The response of laminated membranes to permeation was investigated using simple permeation equations. The intrinsic permeability constant of the membrane was shown to be between the maximum or minimum intrinsic permeability constant of all component membranes. Thus the separation factor of the laminated membrane for any type of permeating molecules will be between the values of maximum and minimum separation factors of the component membranes. Permeation through the laminated membrane for a given species will depend on the direction of permeation if the intrinsic permeability constant of any permeating molecule is dependent on the concentration. A simple example for the concentration dependence of permeability constant shows the limits of anisotropic flow ratio.     

气相二氧化硅对瓷器文物修复仿釉涂料性能的影响

瓷器文物修复作色上釉时使用的无色透明有机涂料称为仿釉涂料,目前常用于瓷器文物修复的仿釉涂料普遍存在着耐老化性差和硬度不足这两个问题.为了使仿釉涂料更好地满足修复需求,研究使用气相二氧化硅粉体材料,对陶瓷修复常用的三种仿釉涂料(硝基涂料、丙烯酸光油和水性聚氨酯涂料)进行改性实验,并对改性前后涂膜的硬度、光泽度、接触角、附...     

Optical and Mechanical Properties of Nanocomposite Films Based on Polymethyl Methacrylate (PMMA) and Fumed Silica Nanoparticles

Nanocomposite polymer films are prepared by using ultrasonic spray deposition (USD) technique through mixing polymethyl methacrylate as matrix and fumed silica nanoparticles as second phase in dimethyl carbonate solvent. Annealing procedure improves the film uniformity and optical transmission. The addition of fumed silica nanoparticles impedes the transmission of the electrolyte films due to agglomeration of fumed silica nanoparticles. Fortunately, adding surfactant, cetyltrimethylammonium bromide, disperses the fumed silica nanoparticles and retrieves the optical transmission of nanocomposite polymer films to around 90%. The hardness and elastic modulus of the nanocomposite polymer films are better than the commercial bulk. The USD deposited nanocomposite polymer film comprises of PMMA and fumed silica nanoparticles is a promising candidate of solid-state electrolyte for EC windows application. POLYM. ENG. SCI., 60:553–557, 2020. © 2019 Society of Plastics Engineers     

气体在均质高分子膜中渗透过程的研究

本文研究了气体在玻璃态聚合物膜中的渗透行为,提出了Langmuir环境和Henry环境的渗透分离系数的概念,推导出它们与表观分离系数间的关系,分析了压力,组成和温度及膜的玻璃化转变对选择渗透性的影响,验证了双吸着双迁移模型及其扩展形式的适用性.通过理论分析和实验证明探讨了实际中出现的“快气变慢,慢气变快”及“纯气渗透系数之比往往高于实际的混合气渗透分离系数”,指出其并非一般性结论,有时会出现与此相反的结果.     

气相法白炭黑尾气车间改造

生产气相法白炭黑的车间,经过试车及一段时间的开车运转后,研究了不同进料量下床层压降与气速的关系,得到了增产扩容后的尾气车间改造后的工艺流程及设备规格尺寸。在实验研究及科学计算的基础上,设计了气相法白炭黑设备扩产后,相应的尾气车间的改造工程,使尾气能够达标排放,同时也实现了尾气喷淋下来的白炭黑的分离及回收利用。     

气相法白炭黑生产技术的研究

本文介绍了气相法白炭黑的制备原理与生产工艺,以及在生产过程中的技术难题.     

气相法白炭黑生产技术的研究

本文介绍了气相法白炭黑的制备原理与生产工艺,以及在生产过程中的技术难题。     

气相法白炭黑尾气吸收工艺流程简介及改进措施

介绍了气相法白炭黑尾气吸收系统工艺流程简介及改进措施,通过改造洗涤分离器、酸碱吸收塔、增设除雾器、在线浓度计等措施,改进了尾气吸收的效果,提高了盐酸的浓度,减小了烧碱的用量,收到了较好的经济效益。     

Effect of Polyvinyl Alcohol Modified Silica Particles on the Physical and Gas Separation Properties of the Polyurethane Mixed Matrix Membranes

Silicon - Silicon based particles were prepared using tetraethoxysilane (TEOS) as a silica monomer, and low concentration of polyethylene oxide-polypropylene oxide block copolymer (pluronic) with...     

二次生长法合成SAPO-34沸石膜及其气体渗透性能

以四乙基氢氧化铵(TEAOH)为模板剂,采用二次生长法在α-Al_2O_3多孔陶瓷管上合成了SAPO-34沸石膜.利用X射线衍射(XRD)、扫描电镜(SEM)以及气体渗透对合成的膜进行了表征.XRD结果表明合成的膜具有典型的CHA型沸石特征峰,无其它杂相存在.SEM显示膜厚大约为5 μm,膜表面晶粒交织共生完好,且连续、致密,没有发现明显的针孔和裂纹.室温下, 当膜两侧压降为0.1 MPa时,CO_2/CH_4的理想选择性和混合气体分离选择性分别为7和40.     

Synthesis of NaA and NaX Zeolite Membranes by Fumed Silica Via Clear Solution Gel

NaA zeolite membranes have been used for dehydration of organic solvents in laboratory and commercial scales. There are many synthesis methods and conditions for manufacturing the membranes. The use of lactescent and clear gel solutions are two of the most important choices for high quality hydrothermal synthesis of NaA zeolite membrane in gas separation or dehydration of organic solvents. In this article, effect of hydrothermal synthesis time was investigated using the clear gel solution (Al₂O₃:5SiO₂:50Na₂O:1000H₂O). Phase transformation from NaA to NaX was recognized as the most possible event when the clear gel solution was used. XRD spectra, SEM images, and GC analyses were used for evaluation of zeolite crystal phase, the membrane layer quality, and the contents of organic substances (ethanol or 2-propanol) in feed and permeate streams in pervaporation tests, respectively. From synthesis of zeolite membrane at different times, it was revealed that for achieving the pure NaA zeolite phase the synthesis time should not exceed 3 h at 100°C.     

气相二氧化硅的表面改性

简要介绍了气相二氧化硅的表面改性、改性原理、改性工艺、常用改性剂以及改性气相二氧化硅的应用。概述了我国气相二氧化硅工业的发展现状。     

Effect of Silica Nanoparticles on the Performance of Polysulfone Membranes for Olefin‐Paraffin Separation

The separations of ethylene/ethane and propylene/propane using polysulfone‐silica nanocomposite membranes were studied. Silica nanoparticles were prepared via sol‐gel method and the membranes by phase inversion. Characterization by Fourier transform spectroscopy and scanning electron microscopy indicated a good distribution of silica nanoparticles in the polymer matrix and also a good compatibility between the two phases. The performances of the prepared membranes in ethylene‐ethane and propylene‐propane separation were evaluated. The results showed the increments in gas permeability and selectivity by silica. Higher silica contents increased the solubility coefficient and reduced the diffusion coefficient of gases. The plasticization pressure of polysulfone was increased by incorporating the silica nanoparticles in polymer.     

Particle Sizes of Fumed Silica

Fumed silica is a synthetic amorphous silicon dioxide produced by burning silicon tetrachloride in an oxygen-hydrogen flame. Surface areas range from 50–400 m²/g. Using particle sizing techniques, fumed silica shows micron sized particles leading to surface areas markedly lower than expected. Fumed silica appears as a fluffy solid with bulk densities down to 0.03 g/cm³, being invariant over the wide range of surface areas. Attempts to relate the variation of the surface area directly to the performance of fumed silica in technical applications, such as its thickening efficiency in fluids, mainly fail and remain ambiguous.     

气相法白炭黑补强加成型RTV硅橡胶的研究

采用气相法白炭黑作补强剂填充加成型RTV硅橡胶,研究了白炭黑含量对硅橡胶黏度、力学性能、介电性能以及硫化时间的影响,并通过SEM考察了白炭黑在硅橡胶中的分散效果.结果表明,白炭黑能显著地增强硅橡胶的力学性能,当白炭黑用量为5%时,硅橡胶的拉伸强度提高了近4倍,其综合力学性能达到最佳,同时能使硅橡胶具有更低的介电常数,且介电损耗变化不大.