Viscoelastic properties of linear associating poly(n-butyl acrylate) chains
Viscoelastic properties of linear associating poly(n-butyl acrylate) chains
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DOI：
10.1122/1.4942231
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发表时间：
2016-03-01
影响因子：
3.3
通讯作者：
van Ruymbeke, E.
中科院分区：
文献类型：
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作者：
Hawke, L. G. D.;Ahmadi, M.;van Ruymbeke, E.
具有不同密度的功能部分（即丙烯酸（AA）基团）的缠结水解聚（丙烯酸正丁酯）PnBA 共聚物的线性粘弹性特性已经使用小振幅振荡剪切和改进版本的时间推进算法（TMA）进行了实验和理论研究。第二个低频平台（其水平取决于温度和 AA 基团含量）在这些共聚物的储能模量中很明显。它表明终端流动，即大长度尺度的链运动，在实验时间尺度内被高度抑制。这种缓慢的松弛过程归因于 AA 基团的长寿命聚集体（粘性连接）。在中频处，动态模量以 0.5 的斜率衰减，表明类似劳斯弛豫过程。当考虑被困在连续 AA 连接点或/和被困缠结之间的股线的约束释放劳斯运动时，模型很好地捕获了这种行为。一个新参数 p,。 TMA 中引入了单体充当粘性连接的概率，以解释功能性 AA 基团对链动力学的影响。然后通过比较实验和预测的粘弹性数据来验证这个简单模型。 (C) 2016 年流变学会。
The linear viscoelastic properties of entangled hydrolysed poly(n-butyl acrylate) PnBA copolymers, with varying density of functional moieties, i.e., acrylic acid (AA) groups, have been investigated both experimentally and theoretically using small amplitude oscillatory shear and a modified version of the time marching algorithm (TMA). A second, low frequency, plateau, the level of which depends on temperature and AA groups content, is evident in the storage modulus of these copolymers. It indicates that terminal flow, i.e., chain motion at large length scales, is highly suppressed within the experimental timescale. This slow relaxation process is attributed to long lifetime aggregates (sticky junctions) of AA groups. At intermediate frequencies, the dynamic moduli decay with a slope of 0.5 indicative of a Rouse-like relaxation process. This behavior is well captured by the model when constraint release Rouse motion of the strands that are trapped between successive AA junctions or/and trapped entanglements is considered. One new parameter, p,. the probability of a monomer to act as a sticky junction, is introduced in the TMA to account for the influence of the functional AA groups on the chain dynamics. The validation of this simple model is then achieved by comparing experimental and predicted viscoelastic data. (C) 2016 The Society of Rheology.