上海交通大学学报

上海交通大学学报（自然版）

• 物理学 • 上一篇    下一篇

聚醋酸乙烯酯熔体的力学谱

吴学邦，朱震刚，周学懋，刘长松   

  1. (中国科学院 固体物理研究所材料物理重点实验室， 合肥 230031)
  • 收稿日期:2009-05-01 修回日期:1900-01-01 出版日期:2010-05-31 发布日期:2010-05-31

Mechanical Spectroscopy Investigation of Poly(vinyl acetate) Melt

WU Xuebang,ZHU Zhengang,ZHOU Xuemao,LIU Changsong   

  1. (Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, China)
  • Received:2009-05-01 Revised:1900-01-01 Online:2010-05-31 Published:2010-05-31

摘要： 利用液态内耗仪研究了聚醋酸乙烯酯(PVAc)在其玻璃化转变温度（Tg）及其以上温度区域的力学弛豫行为.结果表明：PVAc内耗与温度的关系曲线上存在α和α′ 2个弛豫型内耗峰，α峰与PVAc的玻璃化转变有关，α′峰则对应于一种液/液转变，且两者的弛豫时间均满足VogelFulcherTamman关系；在PVAc熔体内耗与频率的关系曲线上，交叉温度TB≈387 K处的α′峰的弛豫时间、弛豫强度和分布参数均出现了一个转折，这是由于降温过程中TB至Tg之间分子耦合作用显著增强的结果.

关键词: 聚合物熔体, 弛豫, 内耗

Abstract: The molecular relaxation dynamics in poly(vinyl acetate) (PVAc) was studied by mechanical spectroscopy above the glass transition temperature (Tg). The temperaturedependent mechanical spectra reveal the existence of two relaxation modes: α, ascribed to the glass transition, and α′, which might be related to the liquidliquid transition. The relaxation time follows VogelFulcherTamman law for both of the relaxation modes. A detailed analysis of the frequencydomain spectra above Tg shows a dynamic crossover at temperature TB ≈387 K through the temperature dependence of relaxation time, relaxation strength, and shape parameter. According to the phenomenological coupling model, the crossover is suggested to be caused by the strong increase of intermolecular cooperativity below TB with decreasing temperature.

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