气体进入挤出机中熔体时气熔界面形态的分析

气体经单个喷嘴进入挤出机中熔体时所形成的气熔界面其形态有环状、团环状和团状三种，最常见的是团状。界面形态变化的过程分为球形膨胀、尾部颈缩和尾部收缩三个阶段。界面形态与进气压力、进气量、进气位置、流场情况有关，气泡的直径、长度和体积随进气压力的提高而增大，随螺杆转速的升高而减小。气泡脱离喷嘴的时间承受随进气压力和螺杆转速的升高而减小。实验分析表明，界面形态的变化直接影响发泡制品的质量。

Analysis of Gas-Melt Interfacial Morphology While Gas Entering Polymer Melt in Extrusion

When injecting gas into polymer melt in extrusion from a single orifice, it is indicated that gas-melt interface formed showed three kinds of shapes: ring, round-ring, and round. Of the three shapes of interfaces, round-shape bubble is generally observed. Interfacial deformation is composed of three steps of sphere expansion, tail necking and tail shrinkage. Diameter, length and volume of gas bubble increase with the gas pressure, and decrease with screw rotational speed. The time that is taken for gas separating from nozzle decreases with the gas pressure and screw rotational speed. Performance of foam products, as shown in the experimental analysis, is affected directly by interfacial morphology.