聚合物熔体流变特性及其对纺丝组件内流场的影响

测定了聚对苯二甲酸乙二醇酯(PET)、常压阳离子染料可染聚合物(ECDP)熔体的流变特性；通过计算流体力学方法对纺丝组件内的流场进行模拟，并利用粒子图像测速(PIV)实验验证了数值模拟的准确性；通过建立的数值模拟方法研究了聚合物熔体的流变特性对纺丝组件内流场的影响。结果表明：在270~290℃的温度范围内，PET和ECDP的流变指数n均随着温度的升高而增大并接近1，聚合物熔体的黏度随着剪切速率的增大而减小；流体的稠度系数K对纺丝组件内的速度场几乎无影响，但对压力分布影响较大，入口压力随着K的增大而增大；流变指数n对纺丝组件内的压力与速度分布有影响，入口压力和入口流速随着流变指数的增大而增大；流体在砂腔内的流速较小但分布较为均匀，在砂腔上游，流变指数越大，流体流速越大；聚合物熔体在喷丝板外圈的喷丝孔之间形成滞留区，并且流变指数越大，滞留区越小，喷丝孔内外圈的流量分配越均匀。

Rheological properties of polymer melts and their effects on the flow field in spinning assembly

The rheological properties of polyethylene glycol terephthalate (PET) and cationic dyeable polymer (ECDP) melts have been measured. The flow field in a spinning assembly was simulated by the computational fluid dynamics method, and the accuracy of numerical simulation was verified by particle image velocimetry (PIV) experiments. The influence of the rheological properties of a polymer melt on the flow field in the spinning assembly was studied by the established numerical simulation method. The results showed that in the temperature range 270-290℃, the rheological indexes n of PET and ECDP increased and approached 1 with the increase of temperature. The viscosity of the polymer melt decreases with increasing shear rate. The consistency coefficient K of the fluid has little effect on the velocity field in the spinning assembly but has a significant influence on the pressure distribution, and the inlet pressure increases with increasing K. The inlet pressure and inlet velocity both increase with increasing rheological index n. The flow velocity of the fluid in a sand cavity is low, but its distribution is uniform. In the upstream of the sand cavity, larger values of rheological index result in increased flow velocity. The polymer melt forms a retention zone between the spinneret holes in the outer ring of the spinneret plate. Furthermore, as the rheological index increases, the retention zone becomes smaller, and the flow distribution in the inner and outer rings of the spinneret hole becomes more uniform.