【摘要】 为研究气泡在熔体中的动力学,自行设计了圆柱形可视化流道,直接将CO2气体注入聚合物熔体中,观察CO2气泡在小孔延伸流场中不同位置区域时,其形态、大小、运动、变形等动力学现象.并从经典两相流理论的角度出发,分析了流场结构参数、加工条件对气泡在聚合物熔体中形态、分布、运动变化等的影响.实验结果表明:气相在熔体中是以泡状存在的,单一的大气泡经过延伸后,将发生破裂,成为许多细碎的小气泡,且破裂的小气泡的大小、分布、密度等与加工温度、速度、进气压力等有关;气泡经过小孔延伸后破裂,使气熔两相趋于混合,有利于CO2作为发泡剂在泡沫塑料制品生产中的应用.更多还原

【Abstract】 In order to investigate the dynamics of the bubbles in polymer melt,a self-designed columniform visible flow channel was used,and CO2 gas was directly injected into the polymer melt to observe the dynamic characteristics such as shape, size,motion and deformation of the bubbles in different locations in a smallpore enlongated flow field.Moreover,the variations of shape,distribution and motion of the bubbles with the flow-field structural parameters and the processing conditions were revealed based on the classic two-phase flow theory.Experimental results indicate that(1) the gas phase in the melt exists in the form of bubbles;(2) many small bubbles may form due to the breaking up of a large enlongated bubble,the size,distribution and density of the small bubbles being related to the precessing temperature,velocity and injection pressure;and(3) the breaking up of bubbles after the enlongation may result in the mixing of the gas and the melt,which is helpful for the application of CO2 as an foaming agent to the production of foamed plastic products.更多还原