Dynamics of stiff polymer chains. V. Interaction between local and global modes
Dynamics of stiff polymer chains. V. Interaction between local and global modes
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刚性聚合物链的动力学。
DOI：
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发表时间：
1978
期刊：
影响因子：
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通讯作者：
G. T. Evans
中科院分区：
文献类型：
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作者：
M. Fixman;G. T. Evans
分析了具有刚性约束键长和键角的聚合物链在稀溶液中的矢量模式和张量模式弛豫谱。对具有独立键旋转势的链进行了说明性近似计算，发现约束将局部模态的松弛率降低到与某些对机械剪切响应重要的全局模态的速率谱重叠的值。我们推测局部模态和全局模态的混合发生在重叠区域，并且由于混合在弛豫速率谱中产生了间隙。在对混合进行定量研究之前，可以做出一个粗略的近似，即具有小松弛率的全局模态保留了劳斯-齐姆形式，而重叠区域的模态的速率明显高于机械剪切实验中使用的频率。这样，在计算复杂动态粘度时，就不需要计算增强速率的数值。后者是由……
Relaxation spectra are analyzed for vector and tensor modes of a polymer chain with rigidly constrained bond lengths and angles in dilute solution. Illustrative approximate calculations are made for a chain with independent bond rotational potentials, and the constraints are found to reduce the relaxation rates of local modes to values that overlap the rate spectrum of some global modes significant to mechanical shear response. We conjecture that mixing of local and global modes occurs in the region of overlap, and that as a consequence of mixing a gap develops in the spectrum of relaxation rates. Pending a quantitative study of mixing, a crude approximation is made that the global modes with small relaxation rates retain a Rouse–Zimm form, while modes in the region of overlap have rates elevated significantly above the frequencies used in mechanical shear experiments. Then numerical values of the enhanced rates are unnecessary for the calculation of the complex dynamic viscosity. The latter is given by a...