MOLECULAR-DYNAMICS IN POLY(METHYLPHENYLSILOXANE) AS STUDIED BY DIELECTRIC-RELAXATION SPECTROSCOPY AND QUASI-ELASTIC LIGHT-SCATTERING
MOLECULAR-DYNAMICS IN POLY(METHYLPHENYLSILOXANE) AS STUDIED BY DIELECTRIC-RELAXATION SPECTROSCOPY AND QUASI-ELASTIC LIGHT-SCATTERING
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DOI：
10.1021/ma00202a005
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发表时间：
1989-12-01
期刊：
影响因子：
5.5
通讯作者：
FISCHER, EW
中科院分区：
文献类型：
--
作者：
BOESE, D;MOMPER, B;FISCHER, EW
研究了分子量为28 500 Da（Da= daltons）（Tg=-26 ℃）的聚甲基苯基硅氧烷。在实验上，测量的量是在接近玻璃化转变温度的熔体中通过准弹性光散射测量的介电损耗e”（α）和强度自相关函数G（2）（t）。我们用Havriliak-Negami方程拟合了各温度下的t”（a>）数据，并由此计算了偶极-偶极重取向关联函数。一个拉伸指数（Kohlrausch-Williams-Watts形式）的相关函数的拟合直接比较从光散射的结果，这通常是在这个功能的形式。当比较时间相关函数时，我们发现这两种方法之间的定量一致性。这两种方法之间的协议导致的结论是，集体动力学测量的光散射，相关的宏观力学性能的材料，和重定向偶极子的分子动力学是相同的高特性粘度的聚合物熔体。
Poly (methylphenylsiloxane) with a molecular weight of Mw= 28 500 Da (Da= daltons)(Tg=-26 C) was studied. Experimentally, the quantities measured were the dielectric loss e"(a>) and the intensity autocorrelation function G (2)(t) by quasielastic light scattering in the melt close to the glass transition temperature. We have fit the t"(a>) data at each temperature with the Havriliak-Negami equation and from that computed the dipole-dipole reorientation correlation function. A fit of a stretched exponential (Kohlrausch-Williams-Watts form) to the correlation function is directly compared with theresults from light scattering, which are usually given in this functional form. We find quantitative agreement between these two methods when comparing the time correlation functions. The agreement between both methods leads to the conclusion that the collective dynamics measured by light scattering, related to macroscopic mechanical properties of the material, and the molecular dynamics of reorienting dipoles are the same for polymeric melts of high inherent viscosity.