LLDPE熔体短口型挤出中胀大行为的研究

应用毛细管流变仪 ,考察了线性低密度聚乙烯 (LLDPE)熔体于短口型挤出中的胀大现象及其影响因素。结果显示 ,挤出胀大比 (B)与入口压力降 (ΔΡen)之间关系服从指数律 ;B与壁面剪切应力 (τw)之间近乎线性关系 ;B对温度的依赖性不太明显。在相同条件下 ,口型入口角为 12 0°的B值低于 90°时的B值

STUDY ON THE EXTRUDATE SWELL BEHAVIOUR DURING SHORT DIE EXTRUSION OF LLDPE MELT

The extrudate swell behaviour and the factors affecting it during short die extrusion of linear low density polyethylene (LLDPE) melt have been investigated by using a rheometer. The results show that the relationship between die-swell ratio (B) and the entry pressure drop obeys the exponential law; the B increases linearly with the wall shear stress; the dependence of the B on temperature is not too obvious. In addition,the B values with die angle of 120 degress is smaller than that with die angle of 90 degrees at the same test conditions.