...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Physics, D. Applied Physics: A Europhysics Journal >Relaxation dynamics of glass transition in PMMA plus SWCNT composites by temperature-modulated DSC
【24h】

Relaxation dynamics of glass transition in PMMA plus SWCNT composites by temperature-modulated DSC

机译：温度调制DSC在PMMA和SWCNT复合材料中玻璃化转变的弛豫动力学

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The experimental technique offered by temperature-modulated differential scanning calorimeter (TMDSC) used to investigate the thermal relaxation dynamics through the glass transition as a function of frequency was studied for pure PMMA and PMMA-single wall carbon nanotubes (SWCNTs) composites. A strong dependence of the temperature dependence peak in the imaginary part of complex heat capacity (T-max) is found during the transition from the glass-like to the liquid-like region. The frequency dependence of T-max of the imaginary part of heat capacity (C-p) is described by Arrhenius law. The activation energy obtained from the fitting shows increases while the characteristic relaxation time decreases with increasing mass fraction (phi(m)) of SWCNTs. The dynamics of the composites during glass transition, at slow and high scan rates, are also the main focus of this experimental study. The change in enthalpy during heating and cooling is also reported as a function of scan rate and frequency of temperature modulation. The glass transition temperature (T-g) shows increases with increasing frequency of temperature modulation and phi(m) of SWCNTs inside the polymer host. Experimental results show that T-g is higher at higher scan rates but as the frequency of temperature modulation increases, the T-g values of different scan rates coincide with each other and alter the scan rate dependence. From the imaginary part of heat capacity, it is obvious that T-max is not the actual glass transition temperature of pure polymer but T-max and T-g values can be superimposed when phi(m) increases in the polymer host or when the sample undergoes a transition with a certain frequency of temperature modulation.
机译：对于纯PMMA和PMMA单壁碳纳米管（SWCNT）复合材料，研究了温度调制差示扫描量热仪（TMDSC）提供的用于研究通过玻璃化转变的热弛豫动力学随频率变化的实验技术。在从玻璃状区域过渡到液体状区域的过程中，在复热容的虚部（T-max）中发现了温度依赖性峰的强烈依赖性。热容量的虚部（C-p）的T-max的频率依赖性由阿伦尼乌斯定律描述。从拟合中获得的活化能显示出增加，而特性弛豫时间随着SWCNT的质量分数（phi（m））的增加而减少。在低和高扫描速率下玻璃化转变期间复合材料的动力学也是本实验研究的重点。还报告了加热和冷却过程中焓的变化与扫描速率和温度调制频率的关系。玻璃化转变温度（T-g）随着温度调节频率和聚合物主体内部SWCNT的phi（m）的增加而增加。实验结果表明，较高的扫描速率下T-g较高，但是随着温度调制频率的增加，不同扫描速率下的T-g值会彼此重合，从而改变扫描速率依赖性。从热容的虚部可以明显看出，T-max不是纯聚合物的实际玻璃化转变温度，但当聚合物主体中的phi（m）增大或样品经过时，T-max和Tg值可以叠加具有一定温度调制频率的过渡。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号