压力场中高黏聚对苯二甲酸乙二醇酯的流变行为

Rheological Behavior of High-Viscosity Polyethylene Terephthalate in Pressure Field

利用毛细管流变仪及反向压力腔组件研究了压力场下高黏聚对苯二甲酸乙二醇酯(PET)熔体的流变行为。结果表明,随着剪切速率的增加,高黏PET熔体剪切黏度逐渐降低,表现出明显的“切力变稀”行为,是一种典型的假塑性流体;随着熔体所受压力的增加,高黏PET熔体剪切黏度呈指数增长增加,变化规律符合Barus方程;随着温度的升高,高黏PET熔体的剪切黏度逐渐减小;高黏PET熔体的换算因子为3.4,压力增加与温度下降对剪切黏度的贡献是等效的。高黏PET熔体为非牛顿流体,随着温度的逐渐升高,高黏PET熔体非牛顿指数逐渐增大,高黏PET熔体的流动行为逐渐接近牛顿流体特性。高黏PET熔体的剪切黏度-温度依赖性随压力的增加逐渐增强;高黏PET熔体的剪切黏度的温度敏感性随剪切速率的增加逐渐降低。随着剪切速率增加和温度升高,高黏PET熔体剪切黏度对压力的依赖性逐渐降低。

The rheological behavior of high molecular weight polyethylene terephthalate(PET)melt under a pressure field was studied by capillary rheometry and reverse pressure chamber conditioning.The results show that with an increase in shear rate,the shear viscosity of high molecular weight PET decreases gradually,showing obvious"shear thinning"behavior,which is typical of pseudoplastic fluids.The shear viscosity of high molecular weight PET is increased exponentially with an increase in melt pressure,and the variation conforms well to the Barus equation.The shear viscosity of high molecular weight PET is decreased with the increase of temperature.The conversion factor of high molecular weight PET is 3.4,and the contribution of the pressure increase to shear viscosity is equivalent to that of the temperature decrease.High molecular weight PET is a non-Newtonian fluid,with an increase in temperature,the non-Newtonian index of high molecular weight PET is increased gradually,and the fluidity of the high molecular weight PET gradually approaches Newtonian fluid characteristics.The shear viscosity-temperature dependence of high molecular weight PET is increased with increasing pressure and the temperature sensitivity of the shear viscosity of high molecular weight PET is decreased with an increase in shear rate.With an increase of shear rate and temperature,the dependence of shear viscosity on the pressure of high molecular weight PET melt is decreased gradually.