Time variation of the relaxation phenomena of polymer blends during the phase separation by time resolved dielectric relaxation spectroscopy

通过时间分辨介电弛豫光谱研究聚合物共混物相分离过程中弛豫现象的时间变化

基本信息

批准号：
13650955
负责人：
URAKAWA Osamu
金额：
$ 2.37万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

In order to understand the relation between morphology and properties of binary polymer blends, we performed dielectric measurements on several systems, such as miscible blends and phase separated systems: (1) Polystyrene / Poly(vinyl methyl ether) (PS/PVME), (2) Polyisoprene / Poly(vinyl ethylene), (3) Poly(vinyl acetate) / Poly(ethylene oxide), (4) Polystyrene / 4-cyano,4'-alkyl biphenyl. The common characteristic of these blends is that there exists large difference in the component glass transition temperatures (Tg). In all the blends except for system (3), dynamical heterogeneity was observed in the dielectric relaxation behaviors.We examined the time variation of dielectric relaxation behavior for a PS/PVME blend after inducing phase separation. The result was that the peak frequency corresponding to the segmental motion of the PS component shifted to the low frequency side and the height of the peak gradually increased just after the phase separation. As for the reason of the peak shift, we think that the enrichment of PS (high Tg component) concentration due to the growth of phase structures increased the friction factor for PS segments. The reason for the increase of the peak height might be explained as follows: The fraction of the PS existing near the interface between PS-rich and PVME-rich domain will decrease while that of PS existing in the middle of the PS-rich domain will increase during the phase separation. If the observed a-peak is ascribable to the segmental motion of PS inside the PS domain, its intensity (corresponding to the peak height) will increase with time. For PS/ 4-cyano, 4'-pentylbiphenyi blend, the change of the relaxation behavior during the phase separation was investigated. In this experiment we observed new relaxation process which can not be explained in terms of the relaxations inherent to the component dynamics. We could assign this to the Maxwell-Wagner type relaxation.

In order to understand the relation between morphology and properties of binary polymer blends, we performed dielectric measurements on several systems, such as miscible blends and phase separated systems: (1) Polystyrene / Poly(vinyl methyl ether) (PS/PVME), (2) Polyisoprene / Poly(vinyl ethylene), (3) Poly(vinyl acetate) / Poly(ethylene氧化物），（4）聚苯乙烯 / 4-甲基，4'-烷基二苯基。这些混合物的共同特征是，组件玻璃过渡温度（TG）的差异很大。在除系统（3）以外的所有混合物中，在介电弛豫行为中都观察到动态异质性。我们检查了诱导相分离后PS/PVME混合物的介电弛豫行为的时间变化。结果是，与PS分量的分段运动相对应的峰频率转移到低频侧，并且峰值的高度逐渐增加。至于峰值变化的原因，我们认为由于相结构的生长，PS（高TG成分）浓度的富集增加了PS段的摩擦因子。峰高增加的原因可能解释为如下：PS富含PS富含PS和PVME的域之间存在的PS的分数将减小，而在PS富含PS的域中存在的PS的分数将在阶段分离中增加。如果观察到的a-peak可归因于PS域内PS的分段运动，则其强度（对应于峰高）将随时间增加。对于PS/ 4-Cyano，4'-二苯基苯耶尼的混合物，研究了相位分离过程中弛豫行为的变化。在本实验中，我们观察到了新的放松过程，这无法用组件动力学固有的松弛来解释。我们可以将其分配给Maxwell-Wagner类型放松。