聚合物介电弛豫的温度特性

Thermal behaviours of dielectric relaxation of polymers

运用极限的概率模型和Ngai的耦合概念 ,导出了聚合物介电弛豫的Kohlrausch Williams Watts(KWW)方程(t)=exp[- (t τ)β],证明了弛豫的能量势垒为Ngai的活化能量E .由 β的温度关系推出了适用于聚合物的Williams Landel Ferry方程和过冷液体的Vogel Tammann Fulcher方程 ,特别是提出了由聚合物的 β(T)可导出弛豫时间的温度函数 .认为KWW行为由单个衰减单元产生 ,幂律行为由局部区域内多个衰减单元的协同衰减造成 .将活化能量E 引入热刺激电流公式 ,得到了可通过改变升温速率测量 β(T)的公式 .

Kohlrausch Williams Watts(KWW) function, (t) =exp[-( t/τ) β ] is derived by using the extreme probability model and introducing Ngai's coupling concept in dielectric relaxation of polymers. Ngai's apparent activation energy E * is also confirmed as the energy barrier in the relaxation process. Williams Landel Ferry function used for polymer and Vogel Tammann Fulcher function used for supercooled liquid are also deduced by means of β(T). The significance is that τ(T) can be obtained by β(T). The behaviours of KWW and power law come from the decay of single unit and multi unit in local zone, respectively. Finally, the improved equation of thermally stimulated currents is obtained by introducing E * , which provides the determination of β(T) from the experiment of varying heating rate.