摘要
本文利用G(o|¨)ttfert流变仪研究一种注塑级及两种挤管级聚乙烯在挤出过程中的不稳定性,考察了上述聚乙烯熔体在整个测定过程中不同温度下的logτ-logγ关系曲线,挤出压力变化历史及挤出物外观。观察到注塑级HDPE比挤出级聚乙烯的流动性能要流畅,平稳,且规则有序。两种挤出级聚乙烯的流动曲线外形虽颇相近,但它们流动曲线的不连续性,挤出压力畸变及熔体破裂情况是不同的。从唯象观点,那些聚乙烯熔体的挤出不稳现象与从层流转化为螺旋状流动有关。
The unstabilities in extrusion of polyethylene melts including one injection grade and two pipe grades were studied by G(o|¨)ttfert Capillary Rheograph.The logτ-logγ curves at various temperatures,the pressure variation in extrusion and appearance of extrudates of abovementioned polyethylene melts in whole measuring period were investigated.We observed that flow property of HDPE injection grade are more regular, stable and smooth than extrusion grades.The discontinuity in those flow property curves,the abnormalities in extrusion pressure and melt fracture of two polyethylene extrusion grades are different from each other,though the shape of their flow property curves are rather similar.The unstabilities in extrusion of those polyethylene melts may be related to the transformation from laminar to screwy flow from phenomenological point of view.
出处
《塑料》
CAS
CSCD
1990年第4期21-27,共7页
Plastics
