加工参数及配方对PP/LLDPE共混物泡孔形态的影响

Effects of Processing Parameters and Formulations on Cell Morphology of PP/LLDPE Blends

采用高压毛细管流变仪对不同含量碳酸钙(CaCO3)的聚丙烯/线型低密度聚乙烯(PP/LLDPE)共混物的流变性能进行了表征;并利用自制的实验装置,在不同发泡温度和饱和压力下,对共混物进行了超临界CO2模拟挤出发泡实验研究。结果表明:使用高熔体强度聚丙(烯HMSPP)发泡可以获得较好的泡孔形态;添加成核剂CaCO3可以使发泡试样的泡孔结构更加规则,泡孔分布更加均匀;随着CaCO3含量的增加,共混物的稠度上升,非牛顿指数降低,当CaCO3含量为3%时,共混物的发泡效果较好;130℃为最佳发泡温度,此时发泡试样的结构完整尺,寸均匀;随着饱和压力的增加发,泡试样的泡孔密度也有所提高。

A high pressure capillary rheometer was used to characterize the rheological properties of PP/ LLDPE blends with different content of CaCO3.The extrusion foam experiments were carried out by using a self-designed supercritical CO2 dynamic simulation foaming device.Different proportions of PP/ LLDPE foams were prepared under various foaming temperature and saturation pressure.The results show that it could get better cell morphology by using high melt strength polypropylene（HMSPP） compared with ordinary PP;the additon of necleating agent CaCO3 makes the cell structure of the foamed samples more regular,and the cell distribution more uniform;with the increase of CaCO3 content,the consistency of the blends increases, while the non-Newtonian index decreases;when CaCO3 content is 3%,the microstructure of the foaming blend is improved remarkably;the optimum foaming temperature is 130 ℃;the cell density increases with the increase of saturation pressure.