Interfacial and dielectric behavior of polymer nano-composites: Effects of chain stiffness and cohesive energy density
Interfacial and dielectric behavior of polymer nano-composites: Effects of chain stiffness and cohesive energy density
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DOI：
10.1016/j.polymer.2018.04.061
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发表时间：
2018-06-06
期刊：
影响因子：
4.6
通讯作者：
Razzaghi-Kashani, Mehdi
中科院分区：
文献类型：
--
作者：
Javadi, Sara;Panahi-Sarmad, Mahyar;Razzaghi-Kashani, Mehdi
这项工作讨论了纳米粒子周围界面层中聚合物链的动力学和极化率，这些链的特征是：刚性(C-无穷大)和内聚能量密度(CED)。选取了C-无穷大和CED成对不同的三种聚合物，研究了低浓度纳米二氧化钛对聚合物的玻璃化转变温度(Tg)、界面层厚度和介电行为的影响。由于在纳米二氧化钛周围形成了界面疏松层，具有高C-无穷大的聚甲基丙烯酸甲酯和CED获得了更多的链段迁移率，导致了较低的玻璃化温度和较高的介电常数。对于COO相似但CED较小的聚苯乙烯，也观察到了类似的变化，但幅度较小。然而，由于纳米二氧化钛周围的致密层被固定，低C-无穷大和CED的乙丙橡胶失去了链段迁移率，但玻璃化温度和介电常数都有所增加。宽带介电分析表明，提高链极化和介电常数需要在界面层中有一个最佳的链段迁移率。(C)2018爱思唯尔有限公司。保留所有权利。
This work discusses dynamics and polarizability of polymer chains in the interfacial layer around nanoparticles based on characteristics of the chains: stiffness (C-infinity) and cohesive energy density (CED). Three polymers differing pairwise in C-infinity and CED were selected, and effects of low concentration of nano-titania on glass transition temperature (Tg), thickness of interfacial layers, and dielectric behavior of polymers were investigated. As a result of interfacial loose layers formed around nano-titania, polymethylmethacrylate with high C-infinity and CED gained more segmental mobility, resulting in lower Tg, and higher dielectric permittivity than the neat polymer. Similar changes with less magnitude were observed for polystyrene having similar Coo but less CED. However, due to immobilized dense layers around nano-titania, ethylene propylene rubber with low C-infinity and CED lost its segmental mobility, but both Tg and permittivity of nano-composite increased. Broadband dielectric analysis showed that an optimum segmental mobility in the interfacial layer is needed for enhanced chain polarization and dielectric permittivity. (C) 2018 Elsevier Ltd. All rights reserved.