Materials during conveying and plasticizing process suffered mainly extensional stress in a vane positive displacement extruder. The conveying efficiency was high. The PS/HDPE melt blending experiments were conducted with a self-made van the positive displacement extruder. Samples were obtained at five sampling locations from feed inlet to die along extrusion direction. The influence of rotating speeds and sampling locations on rheological properties and microstructure of the composites were studied. The experimental results showed that the blends exhibited Non-Newtonian features. The closer to die, the higher of the apparent viscosity of the blends was at the same rotating speed. With the increase of rotating speed, the apparent viscosity of the blend at the same sampling location increased firstly and then decreased slightly. As shown in the SEM photographs the size of the dispersed phase of PS decreased fast firstly and then slowly along extrusion direction. Compared with conventional single screw extruder, the van positive displacement extruder's mixing efficiency was higher and the thermo-mechanical history the material suffered can be greatly shortened.%叶片式正位移挤出机输送效率高,塑化输运过程中物料主要受到拉伸应力作用.利用自行研制的叶片式正位移挤出机进行PS/HDPE熔融共混实验,从加料口至口模的5个取样位置进行取样,分析了转子轴转速、取样位置对共混物的流变性能及共混物微观结构的影响规律.研究结果表明:共混物表现出非牛顿流动特性；在相同转速下,越接近口模处共混物的表观黏度越高；同一取样位置处共混物的表观黏度随转速的升高先增加然后略有下降；扫描电镜照片可以看出,沿挤出方向分散相PS的尺寸逐渐变小,在靠近加料口处分散相粒径减小的速度较快.叶片式正位移挤出机混合效率高,相比常规的单螺杆挤出机,物料所经历的热机械历程大大缩短.
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