Influence of Dangling Chains on Molecular Dynamics of Polyurethanes
Influence of Dangling Chains on Molecular Dynamics of Polyurethanes
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DOI：
10.1021/ma401260d
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发表时间：
2013-09
期刊：
影响因子：
5.5
通讯作者：
Wenwen Yu;M. Du;De-zhi Zhang;Yu Lin;Q. Zheng
中科院分区：
文献类型：
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作者：
Wenwen Yu;M. Du;De-zhi Zhang;Yu Lin;Q. Zheng
研究了悬挂链对聚氨酯相分离微结构和分子动力学的影响。通过改变二元醇扩链剂的种类，制备了具有不同悬挂链长和极性基团的聚氨酯。采用动态力学分析（DMA）和宽带介电弛豫谱（BDRS）相结合的方法对分子动力学进行了研究。发现了四种弛豫过程，即二次弛豫（β）、软相链段弛豫（α）、与氢键有关的I过程和由硬/软相界面电荷积累引起的Maxwell-Wagner-Sillars（MWS）界面极化过程。I过程一般发生在低于MWS过程但高于α弛豫的温度下。β弛豫不受悬挂链长度或极性基团变化的影响。但软相的玻璃化转变温度（Tg）向低温移动，链段运动加快。
The effect of dangling chains on phase-separated microstructure and molecular dynamics for polyurethanes (PUs) was investigated. PUs with different dangling chain lengths and polar groups were prepared through changing the types of diol extender. The molecular dynamics was studied by a combination of dynamic mechanical analysis (DMA) and broadband dielectric relaxation spectroscopy (BDRS). Four relaxations (processes), namely, a secondary relaxation (β), the soft phase segmental relaxation (α), the I process associated with hydrogen bond, and Maxwell–Wagner–Sillars (MWS) interfacial polarization process caused by charge accumulation at hard/soft phase interfaces, were detected. The I process occurred in temperatures lower than that of MWS process but higher than α relaxation in general. The β relaxation remains unaffected with changing dangling chain lengths or polar groups. However, the glass transition temperature (Tg) of the soft phase shifts to lower temperature, and the segmental motion becomes faste...