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Broadband dielectric study of the relaxation dynamics of amorphous and semi-crystalline polymer blends.

机译：非晶态和半晶态聚合物共混物弛豫动力学的宽带介电研究。

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摘要

In order to elucidate the complex relaxation dynamics in polymer blends containing a crystallizable component and having a large Tg difference between the components, a series of systems were investigated principally via dielectric relaxation spectroscopy, with the aid of differential scanning calorimetry, infrared spectroscopy and wide-angle X-ray diffraction experiments.;For neat semi-crystalline poly(ethylene oxide) (PEO), a dielectric relaxation (labeled as gamma') faster than the cooperative segmental relaxation is observed for the first time, and it is assigned to a segmental relaxation with reduced cooperatvity in the order-disorder interphase regions.;Poly(styrene-co-p-hydroxystyrene) (SHS) and poly(methyl methacrylate) (PMMA) were selected to investigate the dynamics of blends of crystallizable PEO with relatively high Tg components, with and without strong intercomponent interactions. For amorphous SHS/PEO blends (≥60wt% SHS), hydrogen bonding is capable of suppressing concentration fluctuations and leads to a single cooperative segmental process involving both components. In addition, a fast PEO segmental process is observed in the dielectric spectra of blends with ≥80 wt% SHS, due to reduced intermolecular hydrogen bonding and repulsion between SHS styrene units and PEO segments.;For amorphous PMMA/PEO blends, after room-temperature aging, a dielectric relaxation becomes apparent at approximately the same frequency-temperature location as that of the PEO gamma' process. It is assigned to nanoscale PEO regions possessing a degree of partial order comparable to that of an order-disorder interphase.;Thermorheological simplicity is observed for amorphous mixtures of dihydroxyl naphthalene (DHN) and poly(vinyl ethyl ether) (PVEE), where DHN is a model small molecule with two functional groups capable of forming hydrogen bonds with PVEE, a non-crystallizable analog of PEO. The absence of chain connectivity in DUN and the presence of a suitable degree of intercomponent interactions is proposed to enable DHN molecules to closely contact PVEE segments and distribute uniformly in the PVEE matrix, thereby having the same effect on all PVEE local environments.
机译：为了阐明含有可结晶成分且各成分之间的Tg差异较大的聚合物共混物的复杂弛豫动力学，主要通过介电弛豫光谱法，差示扫描量热法，红外光谱法和宽光谱法研究了一系列系统。角X射线衍射实验。对于纯净的半结晶聚环氧乙烷（PEO），首次观察到比协同节段弛豫更快的介电弛豫（标记为gamma'），并将其分配给在有序无序的相间区域中，具有降低的节段弛豫性；选择聚（苯乙烯-共-对-羟基苯乙烯）（SHS）和聚（甲基丙烯酸甲酯）（PMMA）来研究具有较高结晶度的PEO共混物的动力学Tg组件，具有和不具有强烈的组件间交互作用。对于无定形SHS / PEO共混物（≥60wt％SHS），氢键能够抑制浓度波动，并导致涉及这两种成分的单一协作分段过程。此外，由于SHS苯乙烯单元和PEO链段之间的分子间氢键键合和排斥力降低，在≥80 wt％SHS的共混物的介电谱中观察到了快速的PEO分段过程;对于无定形PMMA / PEO混合物，在室温下-在温度老化的情况下，在与PEOγ'过程大致相同的频率-温度位置处，介电弛豫变得明显。它被指定为具有与有序无序相相当的部分有序度的纳米级PEO区域;;观察到二羟基萘（DHN）和聚（乙烯基乙基醚）（PVEE）的无定形混合物的热流变简单性，其中DHN是模型小分子，带有两个能够与PVEE（PEO的非结晶类似物）形成氢键的官能团。提出在DUN中不存在链连接性，并且存在适当程度的组件间相互作用，以使DHN分子紧密接触PVEE片段并在PVEE基质中均匀分布，从而对所有PVEE局部环境产生相同的影响。

著录项

  • 作者

    Jin, Xing.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 167 p.
  • 总页数 167
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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