Shear damping function measurements for branched polymers
Shear damping function measurements for branched polymers
复制标题
支化聚合物的剪切阻尼函数测量
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
S. Milner
中科院分区：
文献类型：
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作者：
D. A. Vega;S. Milner
我们介绍了不同结构的聚乙烯共混物的阶跃应变实验结果和由此产生的阻尼函数，包括线性、星形和梳状聚合物的溶液。值得注意的是，纠缠的梳子熔体表现出接近于纠缠的线性链的减振功能。用松弛速度更快的材料稀释梳子，可以获得更恒定的减振功能。我们发现商用低密度聚乙烯LDPE的共混物具有类似的行为。我们的结果给出了一幅简单的图景：在与典型的减振功能实验相关的时间尺度上，我们的PE梳子以及商用LDPE的流变活性部分基本上是链骨架。当强纠缠时，它们表现出Doi-Edwards衰减函数；当稀释时，衰减函数趋向于Rouse模型所描述的非纠缠链的结果--即，没有阻尼项.
We present results for step-strain experiments and the resulting damping functions of polyethylene blends of different structures, including solutions of linear, star and comb polymers. Remarkably, an entangled melt of combs exhibits a damping function close to that for entangled linear chains. Diluting the combs with faster- relaxing material leads to a more nearly constant damping function. We find similar behavior for blends of commercial low density polyethylene LDPE. Our results sug- gest a simple picture: on timescales relevant to typical damping-function experi- ments, the rheologically active portions of our PE combs as well as commercial LDPE are essentially chain backbones. When strongly entangled, these exhibit the Doi- Edwards damping function; when diluted, the damping function tends toward the result for unentangled chains described by the Rouse model - namely, no damp-