硅烷交联聚乙烯管材生产过程中的化学反应及其主要影响因素

硅烷交联法是制造交联聚乙烯管材的主要方法。用该法生产交联聚乙烯管材包括熔融接枝反应和水解缩合交联反应,这两种反应直接影响交联管的性能,本文分析了影响这两种反应的主要因素。     

Silicon Particle Formation by Pyrolysis of Silane in a Hot Wall Gasphase Reactor

The formation of silicon powder by pyrolysis of silane diluted in argon at different concentrations has been studied. A hot wall gasphase reactor was used for the thermal decomposition of SiH₄ at 1000 °C and atmospheric pressure. The composition, morphology, size, and shape of the particles produced has been studied utilizing electron microscopy, X‐ray diffraction, infrared spectroscopy, and BET gas adsorption. Depending on the experimental conditions, agglomerates of polycrystalline, sintered particles have been obtained, which are composed of nanocrystallites of about 25 nm in size.     

乳液聚合粒子成核和粒子大小的影响因素

介绍了乳液聚合中胶束,均相和单体液滴三种不同的粒子成核机理。讨论了引发速率和乳化剂浓度以及不同聚合方法和各种条件对乳胶粒子大小的影响。     

Particle Size Distributions for an Office Aerosol

As attention has focused on indoor air quality, it has become important to obtain basic information on the effects of heating, ventilating, and air-conditioning system operating parameters on office aerosols. In addition, it is important to know the particle size distributions (PSDs) in a typical office environment in order to address mitigation strategies. Therefore, this study was undertaken to evaluate the effect of percent outdoor air supplied and occupation level on the PSDs and mass concentrations for a typical office building. The outdoor, return, and supply air streams, as well as hallway air, were sampled using measuring equipment covering particle diameters from below 0.1 to above 3.5 μm. The mass concentrations, when the building was occupled, increased by a factor of approximately 2 when return air was recycled over ventilating with maximum outdoor air. The concentrations when unoccupied were at least as low using minimum outdoor air as those when occupied using maximum outdoor air. As expected, the outdoor air was cleaner than the other streams. The next lowest concentrations were obtained for supply air, then return air, with hallway air showing the highest concentrations. The normalized number distributions were found to have a single mode consistently near 0.13 μm; the volumetric distributions show a peak at 0.3 μm. The influence of the damper setting and occupancy level shows up only in the magnitude of the peaks. The distributions found in the hall and for the air streams showed the same general shapes, but the differences in instrumentation preclude other conclusions.     

影响循环移动载体生物膜反应器性能的因素分析

对循环移动栽体生物膜反应器进行了研究。通过改变循环移动栽体膜生物反应器的结构尺寸，研究了反应器内氧转移系数的变化。研究结果认为在反应器的升、降流区面积之比为2／3．挡板上方液面高度和底隙高度均为250mm，填料的填充比为50％时，氧转移效率最高。     

影响光催化超滤膜反应器降解Acid Blue 7的因素研究

设计研制了一种光催化超滤膜反应器,并选用一种颗粒状纳米级TiO2作光催化剂,对染料Acid Blue 7光氧化降解进行了研究。影响染料降解的因素包括：错流速度、催化剂浓度、染料初始浓度、溶液的pH值以及曝气条件。研究结果发现,光催化超滤反应器对染料废水处理具有较高的处理效果,且颗粒状光催化剂能够实现良好分离。     

超临界CO2GAS沉析HMX制细过程的影响因素

研究了超临界CO2GAS沉析丙酮溶液中HMX的过程压力、温度、溶液初始浓度和溶液的膨胀速度及影响晶体粒度的因素。结果表明，压力增加，沉析颗粒的平均粒度减小；温度控制沉析晶体的晶型，对颗粒度的影响相对较小，温度增加，沉析平均粒度略有增加；溶液初始浓度对平均粒度的影响相对较大，膨胀速度亦是影响粒度及其分布的一个因素。快速膨胀溶液．并使过饱和度足够大，使过饱和度主要消耗在成核上，可得到颗粒小、分布窄的HMX颗粒。     

上喷式环流反应器中影响整体气含率的因素探讨

基于甲苯三氧化硫磺化反应工艺的需要,设计了一种分布式多喷嘴新型结构的上喷式环流反应器。测定了表现气速,单位体积功耗、静液位和两相喷嘴结构分布等对反应器平均整体气含率的影响,在试验数据的基础上,得到了各参数间的关联式,结果表明,分布式喷嘴结构可获得较佳性能。     

Factors Affecting the Processing of Epoxy Film Adhesives II. Moisture Content

Dielectric and thermomechanical analysis, infrared spectroscopy, and mechanical testing were used to study the changes which occur in the cure behavior of a 178°C (350°F) epoxy film adhesive, Hysol EA-9649. The response of the system was compatible with the catalyst type employed. The overall effect of increasing moisture content was an increase in flow accompanied by lower T_g values in the cured film with no loss in ambient temperature tensile lap shear strength. These effects are interpreted in terms of the dicyandiamide portion of the adhesive catalyst system reacting with the absorbed moisture resulting in a cured adhesive of different structure but equivalent in bonded joint strength to those made with low moisture content adhesive.     

An Experimental Study of the Performance Factors Affecting Particle Collection Efficiency of the Electrocyclone

An electrocyclone designed with a central discharge wire was built and used to investigate the performance factors affecting its particle collection efficiency by varying the operational conditions and parameters in the particle size range of 0.5 to 10 w m. A voltage of 0 to 9 kV was applied to the discharge wire varying in terms of diameter and length. Two types of vortex finder materials, aluminum and acryl, in three lengths, 2.5, 3.5, and 4.5 cm, were employed to examine the effects of electrostatic force. An increase in applied voltage and a decrease in wire diameter were found to boost collection efficiency, particularly at low flow rates for small particles. Many small particles induced in the cyclone were collected at the bottom of the cyclone cone and in the vortex finder that was situated close to the discharge wire. It was also found that the aluminum vortex finder yields higher collection efficiency than the acryl vortex finder and that the length of vortex finder plays a more important role in particle collection efficiency of the electrocyclone than that of an ordinary cyclone.     

Factors Affecting the Processing of Epoxy Film Adhesives II. Moisture Content

Dielectric and thermomechanical analysis, infrared spectroscopy, and mechanical testing were used to study the changes which occur in the cure behavior of a 178°C (350°F) epoxy film adhesive, Hysol EA-9649. The response of the system was compatible with the catalyst type employed. The overall effect of increasing moisture content was an increase in flow accompanied by lower T_g values in the cured film with no loss in ambient temperature tensile lap shear strength. These effects are interpreted in terms of the dicyandiamide portion of the adhesive catalyst system reacting with the absorbed moisture resulting in a cured adhesive of different structure but equivalent in bonded joint strength to those made with low moisture content adhesive.     

A Fast Scanning Mobility Particle Spectrometer for Monitoring Transient Particle Size Distributions

The Scanning Mobility Particle Spectrometer (SMPS) is a key tool for measuring particle size distribution. The application of the instrument to obtain size distributions throughout a wide range of particle sizes for transient systems, such as motor vehicle emissions, has been limited by the time resolution of the SMPS. In this paper, we present a fast-SMPS (f-SMPS) that utilizes a Radial Differential Mobility Analyzer (rDMA) and a Wixing Condensation Particle Counter (mCPC). The combination of these two components allows for the acquisition of particle size distributions on the time scale of several seconds. The Instrument has an operating range of 5–98 nm and can obtain particle size distributions at rates of up to 0.4 Hz. This paper presents the initial construction and calibration of the instrument followed by its application to several sampling scenarios. Samples from the on-road testing of a heavy-duty diesel (HDD) vehicle demonstrate the utility of this instrument for momtor vehicle emissions measurements as size distributions can now be associated with discrete events taking piace during vehicle onroad operation. For instance, these data indicate the presence of a number peak at 15 nm during transient vehicle operation. Previous work indicates that these particles are associated with the loss of engine lubricating oil.     

不同粒度分布高硫焦颗粒在强混燃烧器内的流动特性

利用一套新型强混燃烧器,对3种不同粒度分布的高硫焦颗粒的流动特性进行了较为详尽的考察. 反应器主要由预混段和提升段组成,两部分结构尺寸分别为f240 mm′3000 mm和f70 mm′9000 mm. 实验操作条件为：提升管表观气速8~18 m/s,颗粒循环速率60~200 kg/(m2×s). 通过对3种不同粒度分布的颗粒在强混燃烧器内颗粒固含率、颗粒速度轴径向分布的测定,发现随掺入细颗粒比例的增加,截面平均颗粒速度降低;在较粗的高硫焦颗粒中适当掺入细粉,可使床层内颗粒固含率增加,返混加剧,停留时间延长,有利于高硫焦的充分燃烧.     

预加氢反应器的制造和检验

本文介绍了预加氢反应器的典型结构,分析了制造上的难点,有针对性地提出了解决难点的特殊工艺方案,记录了实际制造经验数据,对类似设备的制造有着重要的参考价值。     

Investigation of Factors Affecting the Particle Properties of C.I. Disperse Yellow 3

The importance of particle size, shape and crystal form of pigments and disperse dyes is discussed. Methods for controlling the particle properties of insoluble azo colorants are outlined. A detailed account of the use of surface-active agents and the effects of coprecipitation of related azo compounds in controlling the particle properties of C.I. Disperse Yellow 3 is given.     

气力输送过程中炭黑粒子破碎率影响因素分析

分析气力输送过程中炭黑粒子破碎率的影响因素。炭黑品种及造粒方式、炭黑粒子压碎强度、输送距离、输送气速、输送方式、输送管道清扫对炭黑粒子破碎率的影响较大。综合考虑各方面因素,对气力输送系统优化提出建议:湿法造粒炭黑粒子破碎率明显小于干法造粒炭黑,应按造粒方式分别设定炭黑粒子破碎率指标,炭黑造粒应优选湿法造粒工艺;为了保证输送后炭黑粒子破碎率小于10%,炭黑粒子压碎强度应大于30 g,同时炭黑粒子压碎强度分布不宜过宽;在气力输送系统中采用比例调速阀,通过自动控制系统自动调节炭黑输送气速,以实现不同炭黑在最佳状态下输送;尽量减小管道清扫次数。     

The Effect of Particle Size Distributions on the Microstructural Evolution During Sintering

Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid‐state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle radii and a range of standard deviations, and log‐normal PSDs with fixed mode and a range of skewness values were studied. Densification rate and final relative density were found to be inversely proportional to initial PSD width. Grain growth was faster during the early stages of sintering for broad PSDs, but the final grain sizes were smaller. These behaviors are explained by the smallest grains in the broader PSDs being consumed very quickly by larger neighboring grains. The elimination of the small grains reduces both the total number of necks and the neck area between particles, which in turn reduces the regions where vacancies can be annihilated, leading to slower densification rates. The loss of neck area causes grain growth by surface diffusion to become the dominant microstructural evolution mechanism, leading to poor densification. Finally, pore size was shown to increase with the width of PSDs, which also contributes to the lower densification rates.     

Factors Affecting the Processing of Epoxy Film Adhesives: I. Room Temperature Aging

Differential scanning calorimetry, dielectric analysis, and infrared spectroscopy were used to study the changes which occur at room temperature in an epoxy film adhesive cured, in part, with dicyandiamide. The principal reaction involved interaction of the catalyst with the lower molecular weight resins in the formulation. The overall effect was demonstrated by an increase in resin viscosity, softening point and overall cure time, accompanied by a decrease in resin flow and ultimate bonded joint strength.