高相对分子质量聚乙烯/石蜡油体系加工过程压力变化

Pressure Change During the Processing of High Molecular Weight Polyethylene/Paraffin Oil System

采用恒速型高压毛细管流变仪测试高相对分子质量聚乙烯/石蜡油(PE/LP)共混体系的流变性能,以相对分子质量、LP含量、温度等为变量,分析共混体系在加工过程中的压力变化。结果表明,相对分子质量越大,对应临界剪切速率变小,挤出压力震荡频率和振幅增大;LP含量越少,相同剪切速率下挤出压力越大,在油含量30%时,出现挤出压力稳定现象,即随剪切速率的变化,挤出压力震荡现象消失;温度越高,对应的挤出压力减小,压力震荡现象减弱,震荡的频率和振幅减小。

Rheological behavier of high molecular weight polyethylene/paraffin oil blends was studied by a constant speed high pressure capillary rheometer.The influence of molecular weight,paraffin oil content,and temperature on the pressure was analyzed.It was observed that the higher the molecular weight,the lower the critical shear rate,and the higher the extrusion pressure oscillation frequency and amplitude.The lower the paraffin oil content,the higher the extrusion pressure at a same shear rate.When the oil content was 30 %,the extrusion pressure became stable,i.e.,the extrusion pressure oscillation disappeared when the shear rate changed.With increasing extrusion temperature,the extrusion pressure decreased,the frequency and amplitude of pressure oscillation also decreased.