Molecular Rheology of Amorphous Polymers Studied with Electric Birefringence

在玻璃化转变温度附近和以上的不同温度下，在0.1 - 105 Hz的频率范围内，测量了聚苯乙烯熔体（分子量为10500和1050）在低电场下的电双折射（克尔效应）。频率-温度叠加可用于获得复合曲线。在粘弹性弛豫谱的玻璃化转变区观察到了一个弱的复克尔系数色散。发现电双折射随时间的演化与主链取向引起的“应变诱导”双折射在阶跃应变后的弛豫过程雅阁。还对具有永久性A型偶极子的聚异戊二烯进行了类似的测量。在克尔系数的终端流区域观察到由于永久偶极子引起的色散，并且可以与介电色散相关联。

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.