【作者】 李昕；

【导师】 王利民；

【作者基本信息】 燕山大学 ， 材料学， 2014， 硕士

【摘要】 尽管针对德拜弛豫的研究已经开展了数十年，氢键液体中德拜弛豫存在与否的动力学深层次原因至今仍不清晰。水，作为地球上存在最为丰富的一种物质，其中是否也存在引起德拜弛豫的相应结构这一问题十分值得人们深思。水易晶化的特点使得对水的动力学的研究存在困难，因此选用N-乙基乙酰胺这种玻璃形成能力强且易与水混合的德拜液体，通过研究水与N-乙基乙酰胺混合物的介电弛豫的方法达到探索水本身是否存在德拜弛豫的目的。本文通过宽频介电谱技术，差式扫描量热方法深入研究了水与N-乙基乙酰胺混合液体在玻璃转变温度附近的弛豫行为，主要从混合物介电主弛豫的介电强度，弛豫峰离散情况和形状因子等方面进行了对比与分析，发现混合物的介电谱中的主弛豫与单羟基醇等德拜液体的弛豫即使水的摩尔分数在混合液体中高达70%之多时在动力学特征方面仍然非常相似。水和N-乙基乙酰胺的混合物的热力学方法测得的Tg cal高于动力学测得的T100s，这非常符合单羟基醇等德拜液体的特征和规律。文中进行了N-乙基乙酰胺与一种德拜液体2-乙基-1-丁醇的混合物的介电弛豫的研究，又进行了N-乙基乙酰胺与一种非德拜液体1,2-丙二胺的混合物的介电弛豫的研究，以此两者与水和N-乙基乙酰胺的混合物进行对比。水与单羟基醇的介电动力学相似性意味着水中可能存在着链状结构。水中德拜弛豫的研究不仅推进了对德拜弛豫物理起源的探索，也启发了人们对水本身微结构的进一步思考。更多还原

【Abstract】 An explicit picture of dynamics about the presence or absence of the Debyerelaxation in H-bonded liquids is still unaccessible, though the Debye relaxation hasalready been studied for decades, apperantly associating closely with thehydrogen-bonding (HB), however, water, as the most widespread substance on earth,whether such arrangements are present in water to arise the Debye relaxation remainsunknown. Crystallization is the main obstacle in the studying of water, and the dielectricrelaxation of aqueous mixtures with a Debye liquid is studied in the highly viscousregimes near the glass transition in order to get insight into the dynamics in water.N-ethylacetamide is chosen in view of the presence of the Debye-type relaxation,excellent glass forming ability and miscibility with water.The relaxation of mixtures of N-ethylacetamide (NEA) and water is studied in thehighly viscous regime near the glass transition with dielectric and enthalpy relaxationtechniques applied.The main relaxation dynamics in the dielectric spectra of the mixturesis found to reproduce the typical dynamic characters of the Debye relaxation observed inmonoalcohols as the mole fraction of water reaches up to70%, as the relaxation strength,dispersion and time are scrutinized. Also, the kinetic glass transition temperatures definedfrom the specific dielectric relaxation time are generally greater than the calorimetric ones,likewise in other Debye liquids. The dielectric relaxation of the mixtures ofN-ethylacetamide and1,2-propanediamine (a non-Debye liquid) and2-ethyl-1-butanol (aDebye liquid) is detected as a contrast experiment. The similarity of the dielectricdynamics in water and monoalcohols implies the possibility of the presence of chain-likeassociation in water. The observation of the Debye relaxation in water in our study canpromote not only the investigation in the nature of the Debye relaxation, but also the fieldof molecular behavior of water.更多还原