烧成温度对高铬砖显微结构的影响

利用扫描电子显微镜分析了 170 0℃、174 0℃、1780℃、182 0℃和 186 0℃烧成后高铬砖的显微结构。结果表明 :高铬砖的烧成温度不是越高越好 ,而是有一个合适的烧成温度 174 0℃。在该烧成温度下制得的高铬砖 ,其基质中的Cr2 O3晶粒尺寸适中 ,基质组织结构致密 ,基质和颗粒结合紧密 ,无裂纹 ,并且其力学性能最佳。     

基于改进自由体积和无规因子贡献的聚合物热力学模型

给出了一个基于改进的自由体积和无规因子的聚合物溶液热力学模型，其无规因子项(NRF)用来描述聚合物溶液中聚合物与溶剂的局部交互作用对剩余Gibbs自由能的贡献，改进的自由体积项(Entropic-FV)用来描述聚合物溶液的混合效应对剩余Gibbs自由能的贡献。文中对45组二元聚合物与溶剂体系进行了关联计算，并与Zafarani-Moattar模型，Flory-Huggins模型和UNIFAC-FV模型的计算结果进行了比较，其平均绝对误差分别为1．910％，2．465％，3．738％和10．149％。     

Viscosity of bulk free radical polymerizing systems under near-isothermal and non-isothermal conditions

A viscometer-reactor assembly is used to generate data on the viscosity, η(t), of an example polymerizing system exhibiting the Trommsdorff effect, namely, the bulk free radical polymerization of methyl methacrylate (MMA), at different temperature conditions [near-isothermal and non-isothermal (near-step increase and near-step decrease in temperature)] and at two different initiator, 2,2′-azoisobutyronitrile (AIBN), concentrations. Two types of cup and bob assemblies, viz., the Haake^® SV-2 and the Haake^® HV-DIN, have been used to measure η(t) of the reaction mass, until reasonably high values of viscosity, well into the gel effect region. Only three sets of experimental data on x_m(t), M_w(t) and η(t) under near-isothermal conditions, are used to develop general correlations for the viscosity. These tuned correlations predict the values of the viscosity for a whole variety of other experimental conditions, including non-isothermal cases, reflecting that the physics of the system is well represented by them. Hence, these correlations can be used for other systems after tuning their parameters. The feasibility of on-line soft sensing is demonstrated for a few cases.     

A Solder Alloy Filled Z-Axis Conductive Epoxy Adhesive

Epoxy adhesives filled with four different volume fractions of eutectic tin-bismuth solder alloy were prepared and the effect of filler content on the electrical and mechanical properties of these anisotropic electrically conductive adhesives was investigated. The results show that the adhesive containing the lowest amount of the filler alloy had the best combination of conductivity, insulation resistance and shear strength. The DSC-measurements suggested that the filler melts before the cure of the resin begins which allows the filler to wet and bond well to the conductors. This was verified by SEM/EPMA examinations. A temperature cycling test and high humidity, high temperature treatment were conducted on the best composite adhesive. The temperature variation had no effect on conductivity of the joints while humid and hot environment decreased the conductivity.     

Lewis酸存在下的自由基共聚合——Ⅰ.GeCl_4与BCl_3存在下的乙酸乙烯酯与丙烯酸交替共聚

乙酸乙烯酯(VAc)与丙烯酸(AA)在GeCl_4及BCl_3存在下通过自由基聚合可得到交替共聚物。对GeCl_4体系,聚合反应速率正比于[引发剂]~(0.5)。当VAc/AA=1:1(mol比)时有最大反应速率。CCl_4对本聚合反应无链转移作用。通过紫外光谱分析可证实VAc及AA均与GeC\(?)生成络合物;ESR分析表明,络合AA自由基较未络合AA有较强的阳离子特性,交替共聚的原因可能与络合AA自由基及活化单体络合物二者有关。     

Preparation and thermal property of hybrid nanocomposites by free radical copolymerization of styrene with octavinyl polyhedral oligomeric silsesquioxane

The poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PS–POSS) organic–inorganic hybrid nanocomposites containing various percent of POSS were prepared via one‐step free radical polymerization and characterized by FTIR, high‐resolution ¹H NMR, ²⁹Si NMR, GPC, DSC, and TGA technologies. The POSS contents in these nanocomposites were determined using FTIR calibration curve. The result shows that the POSS contents in nanocomposites can be tailored by varying the POSS feed ratios. On the basis of the POSS contents in the nanocomposites and the ¹H NMR spectra, the number of reacted vinyl groups of each octavinyl‐POSS macromonomer were calculated to be 6–8. DSC and TGA measurements indicate that the incorporation of POSS into PS homopolymer can apparently improve the thermal properties of the polymeric materials. The dramatic T_g and T_dec increases are mainly due to the formation of star and low cross‐linking structure of the nanocomposites, where POSS cores behave as the joint points and hinder the motion and degradation of the polymeric chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dynamics of fluid circulation in coupled free and heterogeneous porous domains

Fluid flow in coupled free and porous domain, particularly when the porous medium is heterogeneous, is encountered in many hydro-environmental conditions, e.g., leakage from underground pipe, combined groundwater lake-subsurface interactions. One of the most difficult problems in the study of coupled flow behaviour has been the development of a universally applicable modelling scheme for combining the flow regimes. This is because the free/porous interfacial properties (e.g., shear-stress; velocity slip) that govern the coupled flow behaviour are difficult to determine experimentally under hydro-environmental conditions. On the other hand, the implications of various forms of heterogeneity in the porous media properties can be very different on the fluid-flow behaviour. Difficulties may also arise in direct coupling of the model equations that govern the fluid flow in the individual regions (e.g., Navier-Stokes for free-flow region and the Darcy's equation for the porous flow region). Consequently, models of coupled free and porous flow for hydro-environmental conditions are not very well developed at the moment. While there are some indications that fluids in coupled free and porous domains may circulate (i.e., development of flow cells), there is a lack of appropriate 3D analysis on how heterogeneities in porous media may affect such flow patterns. In this paper, we aim to analyse how porous media heterogeneity affects the dynamics of flow circulation in the porous side of a coupled free and porous domain. For this purpose, we analyse flow patterns in several model domains made up of two porous layers with differing permeabilities. The governing model equations are discretised and solved using the standard finite volume method on a staggered cell-centred mesh. The temporal discretisation is done using the explicit method. An in-house graphical user interface (GUI) has been created specifically to aid in the visualisation of otherwise complex flow patterns. The GUI contains many post-processing options and provides a comprehensive tool for the analysis of hydrodynamics and contaminant motion (not discussed in this paper) in coupled free and porous flow domains. This GUI is described in this paper briefly. The effects of altering the aspect ratio (i.e., multi-scale) of the domain on the coupled flow pattern have also been discussed.     

聚氨酯涂料中游离甲苯二异氰酸酯(TDI)单体的测定方法

研究了在GB/T18446-2001方法基础上改变内标物(使用无毒性记录的十二烷代替毒性大的1,2,4-三氯代苯)测定样品中游离TDI的方法。该方法简捷、快速、准确度高、精确度高、更环保。本方法的适用范围同GB/T18446-2001。     

两种聚氨酯防水涂料的比较

对焦油型和非焦油水固化型聚氨酯防水涂料B组分的生产工艺、配方特点，施工操作工艺、固化时间、涂膜性能等方面进行了比较，指出新开发的非焦油型聚氨酯涂料生产周期短、能耗少、气味小，是环保型聚氨酯防水涂料。     

一次风机节能改造

为解决一次风机出口风压低、火焰无力度、系统功耗高等问题,采用空气悬浮风机对其进行节能改造。拆除原有的一次风机备用风机,在原有底座上安装空气悬浮风机,整体设计安装悬浮风机出口管道。改造后,一次风机出口风压明显增大,煤粉燃烧充分,火焰调整灵活,每小时可节电30kWh,两处对空排放管道加装消声器,降噪效果显著。