摘要
采用恒速型双毛细管流变仪对比研究了PE—LLD和PE—LD熔体在高速挤出时的挤出压力振荡现象、流动曲线和挤出物外观的变化，探讨了两种PE发生挤出畸变的机理。结果表明，高速流场中PE—LLD熔体在整个毛细管上的挤出压力降发生规律性振荡，振荡幅度为1．5MP8左右，此时流动曲线发生断裂，断裂前曲线斜率为10^-1数量级，而断裂后变为10^-2数量级；而PE—LD熔体在口模入口处的压力降发生振荡，振幅为0．2MP8左右，流动曲线不发生断裂。综合分析认为，PE—LLD的挤出畸变是由于熔体／毛细管壁的边界条件变化引起的，而PE-LD的挤出畸变是由于毛细管入口处熔体的应力集中引起的。
The high-speed extrusion characters of PE-LLD and PE-LD were studied by double capillary rheometer at constant extrusion speed. The difference between the two polyethylene was investigated by analyzing pressure oscillation, flow curves and extrudate appearance. It showed that the pressure oscillation of PE-LLD occurred at the long die, while PE-LD＇ s surges at the die entrance. The flow curve of PE-LLD was not constant and the slope changed a lot while that of PE-LD was continuous. It was concluded that the extrudate distortion of PE-LLD was due to the changes of boundary condition between the melt and the capillary wall, and the extrudate fracture of PE-LD was caused by the concentration of stresses at the inlet of the die.
出处
《中国塑料》
CAS
CSCD
北大核心
2007年第5期58-62,共5页
China Plastics
基金
国家自然科学基金资助项目（50573037、50390090）
关键词
线形低密度聚乙烯
低密度聚乙烯
挤出压力振荡
挤出物
双毛细管流变仪
linear low density polyethylene
low density polyethylene
extrusion pressure oscillation
extrudate
twin capillary rheometer
