Damping Behavior of Entangled Comb Polymers: Experiment
Damping Behavior of Entangled Comb Polymers: Experiment
复制标题
DOI：
10.1021/ma8022662
复制
发表时间：
2009-02-24
期刊：
影响因子：
5.5
通讯作者：
Lohse, David J.
中科院分区：
文献类型：
--
作者：
Lee, Jung Hun;Driva, Paraskevi;Lohse, David J.
研究了聚异戊二烯梳状聚合物在非线性阶跃变形下的应力松弛动力学，以确定梳状结构的阻尼机理特征。两种不同的梳状聚合物在所有应变下均表现出较低的应变软化（B型），且分支长度分别为2和4。随着观测时间的增加，相应的阻尼函数逐渐趋近于通用的Doi-Edwards阻尼函数。所观察到的B型行为明显不同于h型/多支和枝状星型聚合物，表现出从B型到通用的Doi-Edwards阻尼函数（即分支点撤回运动）的新型阻尼转变。这些结果支持了梳子的阻尼机制是由于沿梳子主干的多个分支点上的分支引起的逐渐拉伸和收缩运动。
The stress relaxation dynamics of entangled polyisoprene comb polymers were investigated, specifically under nonlinear step deformations, in order to identify the damping mechanism characteristic of comb topology. The damping behavior of two different comb polymers with branches of two and four entanglement lengths clearly exhibited less strain softening (type B) above the universal Doi-Edwards damping function at all strains. However, the corresponding damping functions gradually approached the universal Doi-Edwards damping function with increasing observation time. The observed type B behavior was clearly different from that of H-shaped/multibranch and dendritic star polymers exhibiting a novel damping transition from type B toward the universal Doi-Edwards damping function (i.e., the branch-point withdrawal motion). These results support the proposal that the damping mechanism for combs is due to the gradual stretching and retracting motions caused by branches at the multiple branch points along the comb backbone.