Molecular Rheology of Amorphous Polymers Studied with Electric Birefringence

测量了聚苯乙烯熔体(相对分子质量10500和1050)在低电场作用下的双折射(克尔效应)，其温度在玻璃化转变温度附近和以上。频率-温度叠加法适用于获得复合曲线。在粘弹性弛豫谱的玻璃化转变区观察到复克尔系数的弱色散。电双折射随时间的变化与阶跃应变后主链取向引起的应变诱导双折射的驰豫一致。对具有永久性A型偶极的聚异戊二烯也进行了类似的测量。在克尔系数的末端流动区域观察到了由于永久偶极子引起的色散，并与介电色散相关联。

Electric birefringence (Kerr effect) of polystyrene melts (molecular weight 10500 and 1050) was measured under low electric field in the frequency range of 0.1 - 105 Hz at various temperatures near and above the glass transition temperature. Frequency-temperature superposition was applicable to obtain a composite curve. A weak dispersion of the complex Kerr coefficient was observed in the glass transition zone of the viscoelastic relaxation spectrum. The time evolution of the electric birefringence was found to be in accord with the relaxation of the "strain-induced" birefringence originated by main chain orientation after step strain. Similar measurement were also performed on polyisoprene having permanent type-A dipole. A dispersion due to the permanent dipole was observed in the terminal flow region of the Kerr coefficient and could be correlated the dielectic dispersion.