Determination of Discrete-Structure Parameters of Coatings with Allowance for Residual Stresses

The authors suggest that the dimensions of a discrete section of a coating should be chosen on the basis of calculation of the critical crack spacing in cohesion cracking. This approach allows for residual stresses in the coating. The reliability of the calculation method has been verified experimentally by direct measurement of the crack spacing.     

浮体门设计的探索与实践

水电站泄水道破坏修复工程,是一项风险高、难度大、前景广阔的系统工程。刘家峡水电站泄水道2号孔破坏修复的关键,是采用人工深水软导向浮体闸门封堵孔口,形成门后洞内旱地施工条件;龚嘴水电站10号冲砂底孔破坏修复的关键,增设浮体闸门采用自动潜行式浮体闸门封堵孔口,形成门后洞内旱地施工条件;哈萨克斯坦CHARDARA水电站SYNAS项目泄水底孔修复的关键,采用分次降水安装浮体闸门侧支承的方法,挡住引水发电机组的下游尾水,在泄水道进口检修门和流道出口之间形成门旱地施工。此3项泄水道修复工程在行业内没有先例,难度很大。整体方案具有创新性,并且均已高质量竣工并投入正常运行。     

长输管道不停输防腐层大修技术

东河塘至轮南输油管道,经过12年的运行,钢管外石油沥青玻璃布防腐层已严重老化甚至剥离。在不停输的情况下,对输油管道防腐层大修,特别像东—轮线输油管道,地处沙漠边缘、戈壁地带,没有成熟的施工经验可以借鉴。文章根据东—轮线输油管道防腐层大修的施工实践,详细介绍了长输管道不停输防腐层大修的施工工艺和质量保证措施。     

薄膜包衣技术及应用

对薄膜包衣技术及其在制剂生产中应用的研究进展作一综述。     

Synthesis and Evaluation of Blends Formed by Polymeric Crown Ethers and a Fullerene-Containing Primary Ammonium Salt in Organic Thin Films

The synthesis of a series of polymers and cyclopolymers bearing crown ethers of differing structure and affinities towards primary ammonium ions is discussed. These polymers have been tested in their efficiency to form structurally homogeneous thin films when blended with an amphiphilic C₆₀ compound containing a primary ammonium ion functional group. The X-ray reflectivity characterization of the films revealed that the polymer bearing the crown ether with the least affinity for primary ammonium ions, but having the highest degree of polymerization, is the most effective in forming structurally homogeneous thin films.     

丁基橡胶及卤化丁基橡胶市场分析

根据国内外丁基橡胶和卤化丁基橡胶现状，分析了未来几年的市场需求情况，并对国内丁基橡胶工业的发展提出了建议。     

Thermal Conductivity Measurement of an Electron-Beam Physical-Vapor-Deposition Coating

An industrial ceramic thermal-barrier coating designated PWA 266, processed by electron-beam physical-vapor deposition, was measured using a steady-state thermal conductivity technique. The thermal conductivity of the mass fraction 7 % yttria-stabilized zirconia coating was measured from 100 °C to 900 °C. Measurements on three thicknesses of coatings, 170 μm, 350 μm, and 510 μm resulted in thermal conductivity in the range from 1.5 W/(m·K) to 1.7 W/(m·K) with a combined relative standard uncertainty of 20 %. The thermal conductivity is not significantly dependent on temperature.     

The flame retardant mechanism of polyolefins modified with chalk and silicone elastomer

This paper presents the current understanding of the flame retardant mechanism of Casico?. The study includes the flame retardant effect of each individual component: ethylene–acrylate copolymer, chalk and silicone elastomer, as well as the formation of an intumescent structure during heating. The flame retardant properties were investigated by cone calorimetry and oxygen index tests. To obtain insight into the flame retardant mechanism, heat treatment under different conditions has also been performed. The results indicate that the flame retardant mechanism of Casico is complex and is related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of carbon dioxide by reaction between carboxylic acid and chalk, ionomer formation and formation of an intumescent structure stabilized by a protecting char. Special emphasis is given to the formation of the intumescent structure and its molecular structure as evaluated from ¹³C MAS‐NMR and ²⁹Si MAS‐NMR, ESCA and XRD analysis. After treatment at 500°C the intumescent structure consists mainly of silicon oxides and calcium carbonate and after treatment at 1000°C the intumescent structure consists of calcium silicate, calcium oxide and calcium hydroxide. Copyright © 2003 John Wiley & Sons, Ltd.     

Ideally selective diisocyanate building blocks: New perspectives for dendrimers and coating binders

Using zirconium (IV) salts as catalyst, the reaction of a diisocyanate carrying one tertiary and one primary isocyanate group (IMCI, DIMP) with alcohols can be conducted with complete regioselectivity. This unique selectivity enables the use of a diisocyanate building block in unprecedented ways. Incomplete regioselectivity of diisocyanates, as commonly encountered in currently commercial ones like IPDI and TDI, inevitably leads to polydisperse products in reaction with polyols. The ultimate monodisperse polymer architecture, dendrimers, can now be made in a facile, straightforward manner using IMCI as the ideal diisocyanate building block. Coating applications of this unique building block are not restricted to these perfect branching polymers, but also include isocyanate-functional coating resins. Without any increase in polydispersity, a hydroxyl-functional polyester can be end-capped with the IMCI diisocyanate and subsequently serve as a crosslinker in powder coatings.