权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

为了了解二元聚合物共混物的形态与性能之间的关系，我们对几种体系进行了介电测量，例如可混溶共混物和相分离体系：（1）聚苯乙烯/聚乙烯（乙烯基甲基醚）（PS/PVME），（2）聚异戊二烯/聚（乙烯基乙烯），（3）聚（乙酸乙烯酯）/聚（环氧乙烷），（4）聚苯乙烯/ 4-氰基，4 ′-烷基联苯。这些共混物的共同特点是各组分的玻璃化转变温度（Tg）存在较大差异。除体系（3）外，所有共混物的介电弛豫行为均表现出动力学不均匀性，我们研究了PS/PVME共混物在诱导相分离后介电弛豫行为的时间变化。结果是，与PS成分的节段运动相对应的峰值频率向低频侧移动，并且峰值的高度在相分离之后逐渐增加。对于峰位移的原因，我们认为是由于相结构的生长导致PS（高Tg组分）浓度的富集，从而增加了PS链段的摩擦因子。峰高增加的原因可能是：在相分离过程中，位于富PS区和富PVME区界面附近的PS含量减少，而位于富PS区中部的PS含量增加。如果观察到的a峰归因于PS畴内PS的节段运动，则其强度（对应于峰高）将随时间增加。对于PS/ 4-氰基，4 ′-戊基联苯共混物，研究了相分离过程中松弛行为的变化。在这个实验中，我们观察到了新的弛豫过程，这不能用组分动力学固有的弛豫来解释。我们可以把它归为麦克斯韦-瓦格纳型松弛。