挤出加工方法对制备PP/PET原位微纤共混物微观形态的影响

分别使用双螺杆挤出机、配备不同结构螺杆或强剪切机头的单螺杆挤出机对聚丙烯(PP)/聚对苯二甲酸乙二醇酯(PET)进行熔融共混挤出，并用扫描电子显微镜观察了产物的微观形态。结果表明，使用双螺杆挤出机或使用配备三段式螺杆的单螺杆挤出机挤出PP/PET，只能制备出PET以球状形态均匀分散在PP连续相中的共混物，不含有任何微纤；使用配备有头部直槽混炼件的单螺杆挤出机挤出PP/PET，部分PET会形成短而粗的微纤；采用熔融挤出热拉伸淬冷法挤出PP/PET，可生产出微纤直径约为5 μm、长径比超过20的原位微纤共混物；采用强剪切机头及头部配备有直槽混炼件螺杆的单螺杆挤出机挤出PP/PET，可生产出微纤直径约为5~7 μm、长径比超过20的原位微纤共混物，且该方法操作简单、辅助设备少、具有工业可行性。

Effect of Extrusion Processing Methods on Microfibrillar Micromorphology of PP/PET Blends

Polypropylene (PP)/poly(ethylene terephthalate) (PET) blends were prepared by a twin-screw extruder, and a single screw extruder with different screw construction and high-shearing extrusion die respectively, and effect of extrusion processing methods on their microfibrillar micromorphology was investigated by scanning electron microscopy. The results indicated that only PET particles as a dispersion phase were formed in the PP matrix when processed by the twin-screw or single screw extruder with three zone screws. When using the single-screw extruder equipped with a Maddock mixing section screw, some short and thick PET microfibrils were observed. Nevertheless, the microfibrils with a mean diameter of 5 μm and a length (L)/diameter (D) ratio over 20 could be achieved in the PP/PET blends when being melt-extruded with the single-screw extruder, followed by hot stretching and quenching. However, the equipment for this process is too complicated to realize the industrialization. Moreover, using a single-screw extruder equipped with a custom designed high-shearing extrusion die, the microfibrils with a diameter of 5~7 μm and a L/D ratio over 20 could also be generated in the matrix. This method is facile to be industrialized.