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.     

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。     

江苏省外资进入的新特点与发展分析

从外商在江苏投资的资金数量的变化、资金进入的行业和区域等方面,分析了最近几年外资进入江苏的一些新的特点。认为江苏在引进和利用外资方面存在重数量轻质量、重引进轻利用和招商引资恶性竞争、产业同构现象严重等问题。江苏应立足地区优势,合理确定产业发展规划,并发挥政府宏观指导与微观引导的作用,积极引导外资流向,注重提高利用外资的质量,以促进产业结构调整与升级,推进经济增长方式的转变。     

浅议大学生非正式体育群体的重要性

大学生非正式体育群体是高校中以健身娱乐为主要目的组成的一类特殊群体,在高校学生管理工作中,非正式体育群体在完善人文关怀、排解学生心理压力、缓和学校管理矛盾等方面具有重要的作用,高校学生管理部门应该利用非正式体育群体的作用为高校学生管理工作服务.