Coal-derived asphaltenes: effect of phenol content and molecular weight on viscosity of solutions

Phenol contents and molecular weights of coal-derived asphaltenes are shown to affect the viscosity of their solutions. Phenol contents were determined by non-aqueous titrimetry. Intermolecular aggregation probably involving hydrogen bonding is a prime factor in the increase in viscosity found with increased asphaltene concentration in a reference solvent system composed of an $\text{88}\text{12}$ ($\text{wt}\text{wt}$) mixture of 1-methylnaphthalene and o-cresol. Aggregation effects are greater for those asphaltenes with relatively higher phenol contents. Asphaltenes were separated into fractions of different polarity by adsorption chromatography. The more polar subfraction was found to increase viscosity in the reference solvent to a greater extent than the less polar subfraction. The logarithmic viscosity numbers of solutions of the asphaltenes and their subfractions are correlated by a linear combination of molecular weights and phenol contents. It is concluded that an effective means of reducing the viscosity of coal-derived liquids would be to reduce the phenol content of the asphaltene fraction.     

化工生产技术管理与化工安全生产的关系

研究化工生产技术管理与化工安全生产的关系.从安全生产管理、安全技术、生产技术、化工生产过程、企业安全技术措施、化工生产事故原因等多角度,强调化工安全生产管理的必要性和重要性.     

PET化学结构与热力学行为的关系

采用差热分析和红外光谱分析、粘均相对分子质量测定的方法,研究了PET的相对分子质量、端羟基和端羧基含量等化学结构与其玻璃化转变、冷结晶、热结晶行为、熔融行为的关系。结果表明:由于玻璃态中分子链段的局部有序性,PET呈现出双玻璃化转变和双冷结晶峰;随着相对分子质量减小,端羟基和端羧基含量相对增加,PET的玻璃化转变温度升高,冷结晶能力和热结晶能力增强,熔点升高,有利于形成结构完善的增强微纤。相对分子质量和端羧基、端羟基含量对热结晶行为影响的程度比对冷结晶行为的大得多,热结晶过程也由均相成核到既有异相成核,又有均相成核,到以异相成核为主。     

化工过程总体裕量与控制性能的权衡优化

化工过程的总体裕量可以用操作优化的经济效益进行评价,根据稳态优化和动态优化的经济效益可进一步划分为服务于操作控制的控制裕量和表征过程可实现经济效益的工艺裕量,二者都与化工过程的控制性能有关。针对具有一定裕量的化工过程进行多目标动态优化,优化目标分别为操作点的经济效益与动态过程中的控制性能指标,采用0-1变量描述控制结构,将控制结构和控制器参数也作为优化变量进行混合整数动态优化,采用Constrained NSGA-Ⅱ算法求解非劣解集,根据非劣解集分析总体工艺裕量、总体控制裕量与控制性能指标的关系。通过催化裂化装置的实例分析发现,对于具有一定裕量的化工过程,控制性能越高,所需的总体控制裕量越多,表征操作优化可实现经济效益的总体工艺裕量越少,只有通过对总体控制裕量和总体工艺裕量进行权衡,才能找到兼顾工艺要求和控制性能的工艺操作点和控制设计方案。     

生活污水浊度与化学需氧量的关系

试验选用三种不同的生活污水,对其浊度和CODCr进行测定及相关分析.分析结果表明:当污水浊度低时,CODCr也低;当污水浊度高时,CODCr也高,这三种污水各自的浊度和CODCr都存在较好的相关性.这样便可用易于测定的浊度来间接反映污水的CODCr和BOD5,从而判断污水的污染程度和处理效果.     

网络器结构参数与网络加工的关系

从网络器的进气孔和丝道的形状、尺寸等结构参数以及合理配置,阐述了其与网络加工的关系,可作为网络器设计的依据;同时还介绍了复式网络器的结构参数,网络器的间距对网络加工的影响,长丝加工过程中,应依照振动谐波运动规律调节网络器间距。     

The chemical nature of material released from coal-derived asphaltenes by reprecipitation and cyclohexane extraction

The yields and chemical nature of n-pentane solubles released from three coal-extract asphaltenes by reprecipitation with n-pentane and cyclohexane extraction have been investigated. With increasing concentration of n-pentane solubles in the original coal liquid, the yield of oils obtained by reprecipitation increases, as also does the tendency for their structures to resemble those of the original n-pentane solubles. No alkanes below C₄₀ were released from the asphaltenes by extraction with cyclohexane and therefore the long alkyl chains (10% of the total carbon in the lignite asphaltenes) must be bound to aromatic, carboxyl or heteroatomic groups.     

Fluidized bed chemical vapor deposition of pyrolytic carbon-III. Relationship between microstructure and mechanical properties

Pyrolytic carbon (PyC) coatings with different densities were produced by fluidized bed chemical vapor deposition under different deposition conditions. Their Young’s modulus and hardness were measured by nano-indentation, whereas the deformation behavior was studied through analyzing the force–displacement curves of the indentations. The deformation mechanism of PyC under indentation is attributed to the slip of the graphene planes, and its reversibility is discussed in terms of the defects of the microstructure. We observed a linear relationship between the density of PyC’s and their Young’s modulus and hardness, for densities lower than 1.9 g/cm³. Above this value, the mechanical properties were controlled by the amount of interstitial defects. Samples were also heat treated at 1800 °C and 2000 °C, and their changes in microstructure, hardness and Young’s modulus are discussed as a function of density.     

Interaction between process design and process operability of chemical processes: an eigenvalue optimization approach

An increasing effort is being devoted to consider controllability issues (or in a wider sense operability issues) at the process design stage. Controllability has mainly to do with dynamics in the face of disturbances. One philosophy for the integration of design and controllability is to explicitly consider dynamic elements within the process design formulation. An outstanding feature of dynamics is stability, which is related with the spectrum (set of eigenvalues) of the dynamic system Jacobian matrix. Dynamic convergence speed may also be analyzed in terms of the eigenvalues of the matrix from a Lyapunov function related to the Jacobian of the system. It is the purpose of this contribution to formulate and solve the chemical process design problem, considering process dynamics from an eigenvalue optimization approach.     

Relationship between redox activity and chemical speciation of size-fractionated particulate matter

Background  

Although the mechanisms of airborne particulate matter (PM) related health effects remain incompletely understood, one emerging hypothesis is that these adverse effects derive from oxidative stress, initiated by the formation of reactive oxygen species (ROS) within affected cells. Typically, ROS are formed in cells through the reduction of oxygen by biological reducing agents, with the catalytic assistance of electron transfer enzymes and redox active chemical species such as redox active organic chemicals and metals. The purpose of this study was to relate the electron transfer ability, or redox activity, of the PM samples to their content in polycyclic aromatic hydrocarbons and various inorganic species. The redox activity of the samples has been shown to correlate with the induction of the stress protein, hemeoxygenase-1.     

Relationship between chemical and rheological properties of two asphalts of different origins

The chemical and rheological properties of two asphalts selected from different sources (Urals, Russia; Cold Lake, Canada) were investigated. Analyses of chemical (elemental composition, fractional composition, molecular weights) and physical properties (complex viscosity, loss tangent, shear compliance) were performed on all original and aged (rolling thin film oven test, RTFOT; pressurized aging vessel, PAV) samples. The analyses of the chemical properties of both asphalts revealed higher asphaltene content, higher heteroatom content, and lower aging susceptibility of the Cold Lake asphalt (less significant changes in group composition). Based on its chemical composition, the Cold Lake asphalt was expected to perform better in the rheological tests than the Urals asphalt. The rheological tests confirmed this hypothesis and revealed better low- and high-temperature properties of the Cold Lake asphalt and a slower deterioration of its physical properties upon oxidative aging.     

Relationship between dielectric behaviors and conversion of MMA during polymerization process

Poly(methyl methacrylate), which is prepared by polymerization of methyl methacrylate (MMA), is widely used in the fabrication of polymer optical fiber and devices. In this article, a dielectric measurement method was proposed to monitor the polymerization process. The measurement result is compared with that obtained by the traditional Abbe's refractometer method. By monitoring the dielectric behaviors of polymerization system, the correlation between dielectric properties of reacting bulk and conversion of MMA was established. The influence of reactive temperature, reactive time, conversion rate of prepolymerization, and oxygen environment was discussed. It was shown that the gel effect occurred at 2 h at the reactive temperature of 50°C when the conversion of prepolymer was about 24% with the absence of oxygen. The conversion rate obtained by Abbe's refractometer method was larger than that measured by dielectric method in the reaction metaphase. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

石灰石-石膏法脱硫过程中浆液雾化夹带与细颗粒排放的关系

脱硫浆液的雾化夹带是导致石灰石-石膏法脱硫过程中细颗粒物排放特征发生显著变化的主要原因。利用相位多普勒粒度分析仪（PDA）、电称低压冲击器（ELPI⁺）在线测试分析了脱硫浆液雾化、夹带特性及其与细颗粒物排放的关系。结果表明,石灰石-石膏法烟气脱硫过程中浆液雾化夹带可导致脱硫净烟气中含大量细小雾滴及亚微米级细颗粒,脱硫净烟气中雾滴粒径与喷嘴的雾化效果有关,主要集中在20 μm以下,雾滴含固量为脱硫浆液的20%～40%。脱硫操作参数如空塔气速、液气比和浆液浓度对脱硫净烟气中的雾滴夹带量存在显著影响,适当降低空塔气速、液气比及浆液浓度,优化喷淋工艺如增加喷淋层、合理布置脱硫喷嘴,能够有效抑制浆液夹带作用,进而降低脱硫净烟气中细颗粒物的排放浓度。     

Relationship between electron sensitivity and chemical structure of polymers as EB resists. I. Electron sensitivity of various polyamides

Polyamides containing double bonds or epoxy groups were synthesized and evaluated as electron beam (EB) resists, in order to find the relationship between electron beam sensitivity and chemical structure of the polyamides. It was found that polyamides containing double bonds, which have good solubility, are easily crosslinked by the electron beam exposure. The sensitivity of a polyamide with 70 mol% of the repeat units containing double bonds was equivalent to that of a 100% unsaturated polyamide which contained double bonds of 100% molar ratios, and thus it is not necessary that the polyamide be a homopolymer of unsaturated repeating units. The polyamides have good physical properties, and are adaptable to dry etching processes.     

Correlations between diamagnetic properties and structural characters of asphaltenes and other heavy petroleum products

Magnetic susceptibility measurements are made at room temperature on heavy petroleum products. They provide characteristic values of the diamagnetism of such organic compounds with high molecular masses. By the use of the Pascal's rules the average number of condensed aromatic rings, in asphaltenes and other heavy petroleum fractions, must be small and undoubtedly less than in the well-known Yen's model.     

Relationship between chemical structure and secondary quinoline insoluble formation in electrode binder pitches

The relationship between the rate of secondary quinoline insoluble (QI) formation in coal-tar pitches and variations in their chemical composition is examined. Production of significant concentrations of secondary QI is shown to be accompanied by mesophase formation, the significance of which is discussed in terms of electrode binder performance.     

Relationship between processing history and rheological properties during postprocessing annealing for anomalous polyethylene blends

The effect of applied processing history and postprocessing annealing treatment on the rheological properties has been studied for a binary blend composed of linear low‐density polyethylene (LLDPE) and low‐density polyethylene produced by radical polymerization (LDPE). It has been found that intensive processing in an internal mixer depresses oscillatory modulus, especially storage modulus, at lower frequency region for LDPE and the blends with LLDPE, whereas the rheological properties of LLDPE are independent of both processing and annealing procedures. Further, the depression of the modulus is found to be more prominent for the blends with 20–40 wt % of LLDPE than that for the pure LDPE, although the phenomenon is ascribed to conformation change of long‐chain branches. Moreover, the blends show slower recovery of the modulus during the postprocessing annealing than do LDPE. The results demonstrate that processing and mixing conditions have to be considered seriously for LDPE/LLDPE blends showing enhanced melt elasticity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1078–1083, 2006     

Relationship between the process parameters and the saturation point in electrophoretic deposition

We used the electrophoretic deposition (EPD) process to fabricate a composite with glass frit and investigated the EPD parameters to find the optimum deposition time by understanding the relationship between the process parameters of zeta potential (ZP), pH, deposition yield and saturation point in a slurry. A binder and a dispersing agent were mixed properly with glass frit (0.2–25 μm, d₅₀ = 8.77 μm) in an ethyl alcohol medium for the preparation of the slurry. The pH and ZP were in an inverse relationship to each other due to the generation of H₃O⁺ ions with the addition of the dispersing agent in the slurry. The acidic nature of the slurry resulted in a decrease of the pH and an increase of the ZP. Otherwise, the pH increased with the addition of the glass frit in the slurry because H₃O⁺ ions were absorbed on the glass frit. Therefore, the OH^? ions correspondingly increased. The saturation point of EPD was strongly correlated with the variation of the pH in the slurry; this is caused by a chemical reaction between the ethyl alcohol and the ions that make up the glass frit. An adjustment of the pH variation and the saturation point in the slurry can be established with respect to the optimum deposition time in the slurry.