Shape‐memory polyurethane/multiwalled carbon nanotube fibers

Shape‐memory polyurethane/multiwalled carbon nanotube (SMP–MWNT) composites with various multiwalled carbon nanotube (MWNT) contents were synthesized, and the corresponding SMP–MWNT fibers were prepared by melt spinning. The influence of the MWNT content on the spinnability, fracture morphology, thermal and mechanical properties, and shape‐memory behavior of the shape‐memory polymer was studied. The spinning ability of SMP–MWNTs decreased significantly with increasing MWNT content. When the MWNT content reached 8.0 wt %, the fibers could not be produced because of the poor rheological properties of the composites. The melt‐blending, extrusion, and melt‐spinning processes for the shape‐memory fiber (SMF), particularly at low MWNT contents, caused the nanotubes to distribute homogeneously and preferentially align along the drawing direction of the SMF. The crystallization in the SMF was promoted at low MWNT contents because it acted as a nucleation agent. At high MWNT contents, however, the crystallization was hindered because the movement of the polyurethane chains was restricted. The homogeneously distributed and aligned MWNTs preserved the SMF with high tenacity and initial modulus. The recovery ratio and recovery force were also improved because the MWNTs helped to store the internal elastic energy during stretching and fixing. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Temperature and catalyst effects on the production of amorphous carbon nanotubes by a modified arc discharge

Large amounts of amorphous carbon nanotubes (ACNTs) were prepared with Co-Ni alloy powders as catalyst in hydrogen gas atmosphere by a modified arc discharging furnace which can control temperature during the electric arcing process. The experimental results indicate that the cooperative function of temperature and catalyst plays an important role in the soot production rate and the relative ACNT purity. When temperature increases from 25 °C to 700 °C, the soot production rate increases from around 1 g/h to 8 g/h, the best relative ACNT purity at 600 °C can reach up to 99% compared to the room temperature sample. Without catalyst, only plate graphite is formed at 25 °C and very few carbon nanotubes are found when temperature increases to 600 °C. TEM, SEM, HRTEM and XRD analysis showed that the as-prepared carbon nanotubes are almost amorphous. The soot production rate is 8 g/h and diameter range of amorphous carbon nanotubes is about 7-20 nm, respectively.     

Volatilisation and catalytic effects of alkali and alkaline earth metallic species during the pyrolysis and gasification of Victorian brown coal. Part III. The importance of the interactions between volatiles and char at high temperature

A novel two-stage fluidised-bed/fixed-bed reactor was designed to investigate the effects of volatile-char interactions on the volatilisation of alkali and alkaline earth metallic (AAEM) species during the pyrolysis of Victorian brown coal at 900 °C. With the two-stage reactor configuration, the AAEM-free volatiles generated from the pyrolysis of the H-form coal in the fluidised bed came into direct contact with the char from NaCl-loaded or Na-form coals in the fixed bed. The results indicated that the interactions between the volatiles, especially free radicals in the volatiles, and the char particles enhanced the volatilisation of Na from the char drastically. However, such radical-char interactions resulted in little volatilisation of Mg and Ca, indicating the importance of valence of the AAEM species. The degree of the volatile-char interactions was also related to the ageing of the char and the chemical form of AAEM species in the coal substrate. The volatiles interacted more strongly with the nascent char than the aged char, indicating that the AAEM species existed in the aged char in more stable forms than in the nascent char.     

信息不对称下的建设项目组织界面管理

建设项目的各参与方隶属于不同的组织体系,界面双方（多方）就会存在极度的信息不对称。以业主和施工承包商为例,分析了二者之间的信息不对称所造成的影响。最后,通过对信息不对称的产生原因分析,从组织层面上提出了一些可能的解决措施,包括：设计合理的契约、应用新的承发包模式、建立统一编码的界面管理信息系统、合理设计组织内部各职能部门界面。     

IT治理与站点内容战略控制机制研究

信息可以改变竞争环境的本质与结构,作为现代信息媒介的网站则可作为一种战略工具。会计准则制定者与监管者鼓励企业在其治理机制中植入以互联网为基础的信息披露政策,但关于站点信息披露的战略控制知识还不完善。描述了IT治理因素及其与网站信息披露相关的战略控制机制,并评估这些因素与机制之间的内在关系,给出了一个基于IT治理、战略管理与基于网站的公司报告文化的概念框架。     

社会阶层分化下高校思想政治教育的路径选择

我国社会阶层分化对高校思想政治教育产生了积极和消极的影响,在这种背景下,高校应调整思想政治教育的思路,加强情感教育、加强教育的层次性和提倡渗透式教育,切实提高思想政治教育的实效性。     

试论科技发展中的伦理向度

对于科技发展带来的一些消极影响,有人认为伦理的干预是无济于事的,甚至最终会影响科技本身的发展。但是,现实中科技与社会发展之间的密切关系表明,对科技的发展给予伦理导向是社会发展的必然走向。把科学发展观作为科技发展的伦理向度,能够实现科技发展和社会进步两者的双赢。     

语境在语言理解中的作用

语境在语言理解中起着重要作用,是语言交际的基础。结合具体例子,分析了语境在语言理解中具有消除歧义、转变语义、补充语言省略意义、帮助理解言外之意的作用。指出只有正确地把握语境,才能深入理解语言的真正含义。     

体育课中加强学生自我保护能力培养的尝试

运动性损伤是体育锻炼中难免的现象。教学实验证明,在体育教学中加强自我保护教育,提高学生自我保护意识和能力,是可以减少运动受伤几率和程度的。