Takenaka Mikihito, Takeno Hiroyuki, Hasegawa Hirokazu, Saito Shin, Hashimoto Takeji, Nagao Michihiro
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Feb;65(2 Pt 1):021806. doi: 10.1103/PhysRevE.65.021806. Epub 2002 Jan 22.
Relaxation processes of the concentration fluctuations induced by a rapid pressure change were investigated for a dynamically asymmetric polymer blend [deuterated polybutadiene (DPB)/polyisoprene (PI)] with a composition of 50-50 by weight by using time-resolved small-angle neutron scattering. The pressure change was carried out inside the single-phase of the blend with the cell designed for polymeric systems under high pressure and temperature. Time change in the scattered intensity distribution with wave number (q) during the relaxation processes was found to be approximated by Cahn-Hilliard-Cook linearized theory. The theoretical analysis yielded the q dependence of Onsager kinetic coefficient that is characterized by the q(-2) dependence at q(xi)(ve)>1 with the characteristic length xi(ve) (with xi(ve) being the viscoelastic length) being much larger than radius of gyration of DPB or PI. The estimated xi(ve) agrees well with that calculated using the Doi and Onuki theory that takes into account the viscoelastic effects arising from the dynamical asymmetry between the component polymers in the relaxation of concentration fluctuations.
通过时间分辨小角中子散射，研究了由快速压力变化引起的浓度涨落的弛豫过程，该过程针对一种动态不对称的聚合物共混物[氘代聚丁二烯（DPB）/聚异戊二烯（PI）]，其重量组成为50-50。压力变化在共混物的单相内部进行，使用了为高压和高温下的聚合物体系设计的样品池。在弛豫过程中，发现散射强度分布随波数（q）的时间变化可以用Cahn-Hilliard-Cook线性化理论近似。理论分析得出了昂萨格动力学系数的q依赖性，其特征是在q（xi）（ve）>1时具有q（-2）依赖性，特征长度xi（ve）（其中xi（ve）是粘弹性长度）远大于DPB或PI的回转半径。估计的xi（ve）与使用Doi和Onuki理论计算的值吻合良好，该理论考虑了在浓度涨落弛豫过程中由组分聚合物之间的动态不对称引起的粘弹性效应。
