Influence of ethyl methacrylate content on the volume‐phase transition of temperature‐sensitive poly[(N‐isopropylacrylamide)‐co‐(ethyl methacrylate)] microgels

A novel series of temperature‐sensitive poly[(N‐isopropylacrylamide)‐co‐(ethyl methacrylate)] (p(NIPAM‐co‐EMA)) microgels was prepared by the surfactant‐free radical polymerization of N‐isopropylacrylamide (NIPAM) with ethyl methacrylate (EMA). The shape, size dispersity and volume‐phase transition behavior of the microgels were investigated by transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis) spectroscopy, dynamic light scattering (DLS) and differential scanning calorimetry (DSC). The transmission electron micrographs and DLS results showed that microgels with narrow distributions were prepared. It was shown from UV–Vis, DLS and DSC measurements that the volume‐phase transition temperature (VPTT) of the p(NIPAM‐co‐EMA) microgels decreased with increasing incorporation of EMA, but the temperature‐sensitivity was impaired when more EMA was incorporated, causing the volume‐phase transition of the microgels to become more continuous. It is noteworthy that incorporation of moderate amounts of EMA could not only lower the VPTT but also enhance the temperature‐sensitivity of the microgels. The reason for this phenomenon could be attributed to changes in the complicated interactions between the various molecules. Copyright © 2004 Society of Chemical Industry     

浸胶工艺对Nomex蜂窝性能的影响

本文研究了浸胶工艺对Ｎｏｍｅｘ蜂窝性能的影响，分析探讨了提高Ｎｏｍｅｘ蜂窝性能及外观质量的途径。研究结果表明：采取新的浸胶工艺制作的Ｎｏｍｅｘ蜂窝，各项性能全面达到法国宇航材料标准。     

Dissipative Particle Dynamics Simulation: A Review on Investigating Mesoscale Properties of Polymer Systems

Polymer systems have typical multiscale characteristics, both in space and time. The mesoscopic properties of polymers are difficult to describe through traditional experimental approaches. Dissipative particle dynamics (DPD) is a simulation method used for solving mesoscale problems of complex fluids and soft matter. The mesoscopic properties of polymer systems, such as conformation, dynamics, and transport properties, have been studied extensively using DPD. This paper briefly summarizes the application of DPD to research involving microchannel flow, electrospinning, free-radical polymerization, polymer self-assembly processes, polymer electrolyte fuel cells, and biomedical materials. The main features and possible development avenues of DPD are described as well.     

Raman spectroscopic study of conformational changes in the amorphous phase of poly(lactic acid) during deformation

The conformational distribution change of amorphous poly(lactic acid) (PLA) induced by deformation has been studied using Raman spectroscopy. Spectroscopic features associated with the rotational isomeric states (ttt, ttg′, tg′t, tg′g′) have been established experimentally and supported by normal coordinate analysis. Deformation induced a significant increase in the most favorable tg′t conformation. Based on the relative intensities of Raman-active skeletal modes, a quantitative method has been developed that can be used to elucidate structural changes in a variety of deformed polymer samples. For biaxially oriented PLA films, the overall tg′t conformation increased from the 76% in undeformed sample to a value as high as 92%. The change in conformational distribution in the amorphous phase follows a different trend (76-88%) as compared to the increase in sample crystallinity (0-43%). A large change in amorphous chain conformation occurred at relatively low draw ratios. In contrast, the large change in the degree of crystallinity occurred at higher draw ratios.     

陶瓷坯体增强剂聚丙烯酸钠在艺术瓷成形过程的应用

本文合成了一系列不同相对分子质量的聚丙烯酸钠,应用于艺术瓷的坯体中,研究了聚丙烯酸钠对艺术瓷坯体强度、变形率的影响,并对聚丙烯酸钠增强机理进行了探讨。结果表明:聚丙烯酸钠可有效地提高艺术瓷坯体的成形强度,减少了坯体的变形率,当增强剂c加入的质量分数为0.6%时,坯体的干燥强度增加率达167.5%,坯体的变形率从50%降低到10%。     

建筑陶瓷生产用印膏的研制

利用羧甲基纤维素钠（Na—CMC）、甘油、乙二醇和纯净水等为主要原料制备建筑陶瓷生产装饰用印膏，实验研究了工艺因素对印膏粘度和印刷性能的影响，优化出适合生产使用的印膏配方。结果表明：当Na-CMC的加入量在1．75g～2．25g之间，甘油15g，乙二醇20g，纯净水65g所制备的印膏具合适粘度和良好的印刷性能。     

基于WSN的电力信息机房监测系统的设计

文章针对无线传感器网络技术在环境监测中的应用,研究并开发了基于无线传感器网络的电力信息机房监测系统,系统采用CC2530芯片及温度、湿度、烟雾、漏水传感器、UPS监控设备等,基于ZigBee网络,实现了机房中重要环境参数的采集,并通过服务器端的B/S系统将数据分析与存储,便于用户在远程查看,实现了机房的远程监测。     

基于虚拟仿真的动车组转向架检修支持系统开发

CRH380BL高速动车组转向架技术含量高,结构复杂,需要高效率、高质量的检修与维护手段。文章综合应用虚拟现实、多媒体和仿真技术,设计开发了动车组转向架检修虚拟仿真支持系统。它提供一个可视化的多媒体信息平台,可支持新的培训模式,使培训人员在虚拟环境中快速掌握检修技能,以交互方式浏览转向架各组成部件的三维模型,了解转向架的技术信息、结构特点、模块配置、各级修程信息及产品装配过程。该文介绍了转向架结构特点,详细描述了系统的结构、功能以及关键技术。     

Roof pre-blasting to prevent support crushing and water inrush accidents

Support crushing and water inrush when mining under an unconsolidated confined aquifer in the Qidong Coal Mine was prevented by roof pre-blasting. The mechanism and applicable conditions for this method have been studied. The results show that when an overburden structure that may cause support crushing and a water inrush accident exists the weakening of the primary key stratum, which thereby reduces its weighting step, roof pre-blasting is both feasible and effective. If the position of the primary key stratum can be moved upward to exceed 10 times the mining height the possibility of support crushing and water inrush disaster caused by key stratum compound breakage will be lowered. The overburden structure of the number 7121 working face was considered during the design of a technical proposal involving roof pre-blasting. After comprehensively analyzing the applicability of roof pre-blasting the resulting design prevented support crushing and water inrush disasters from happening at the number 7121 working face and laid a solid foundation for mining safely.     

碳对铁及其合金超细微粒氧化特征的影响

采用ＣＯ２激光诱导Ｆｅ（ＣＯ）５－Ｃ２Ｈ４－ＮＨ３的气相分解反应制备了Ｆｅ、Ｆｅ－Ｎ和Ｆｅ－Ｃ－Ｎ超细微粒（微粒直径小于１００ｎｍ）,用透射电子显微镜、Ｘ光衍射、Ｏ／Ｎ和Ｃ／Ｓ测试仪及振动样品磁强计等研究了微粒的结构、表面形态、表面氧的状态及磁性能等;探讨了碳对微粒的氧化特征,特别是对微粒表面氧的形态及其磁性能的影响。结果表明,微粒表面氧的状态可分为吸附态和化合态,并且二者的含量随着微粒的种类不同而变化,碳对微粒表面氧的存在状态、微粒的氧化状况及磁性能具有决定性的影响