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首页> 外文期刊>ACS Macro Letters >Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers
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Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

机译：接枝密度对移植聚合物线性粘弹性行为的后果

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摘要

The linear viscoelastic behavior of poly-(norbornene)-graft-poly(+/--lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0 to 100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed, while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data, demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (G(e)) scales with inverse grafting density (n(g)) as G(e) similar to n(g)(1.2) and G(e) similar to n(g)(0) in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.
机译：研究了聚 - （降冰片烯） - 吡啶 - 聚（+ / - 丙交酯）的线性粘弹性行为作为移植密度和整体摩尔质量的函数。通过活性开环复分解共聚合成八组具有从0至100％的接枝密度的聚合物。在每组内，接枝链摩尔质量和移植物之间的间隔被固定，而总主干长度变化。动态主曲线揭示了这些聚合物在零剪切粘度数据中显示唤醒和恢复动态，表明移植密度强烈影响缠结摩尔质量。术（G（e））与相似的G（e）相似的G（e），与类似于N（g）（0）的N（g）（1.2）和g（e）相似的G（e）缩放分别在高和低移植密度限制中进行缩放理论。然而，发生这些限制行为之间的急剧转变，这不符合接枝聚合物的现有理论模型。在低移植密度和高接枝密度下厚的半弯曲链基于薄的柔性链的分子解释预期限制动力学制度之间的急剧转变。

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