多级拉伸挤出对纳米有机蒙脱土/高密度聚乙烯复合材料形态结构及性能的影响

采用多级拉伸挤出工艺和传统挤出工艺制备了纳米有机蒙脱土/高密度聚乙烯（OMMT/HDPE）复合材料，利用广角X射线衍射（WAXD）、TEM、DSC和小角X射线散射（SAXS）等手段对比研究了两种不同工艺制备OMMT/HDPE复合材料的形态结构和性能。结果表明：多级拉伸挤出作用能够细化OMMT的颗粒尺寸，促进OMMT在HDPE基体中的分散；随多级拉伸挤出次数的增加，OMMT的分散性越好，OMMT颗粒的长径比增加，从而使OMMT/HDPE复合材料的初始成核速率和结晶速率明显提高，诱导复合材料形成取向串晶（Shish-kebab）结构，显著提高OMMT/HDPE复合材料的拉伸强度；当OMMT∶HDPE分别为1∶100和5∶100时，多级拉伸挤出OMMT/HDPE复合材料的拉伸强度相对于传统挤出OMMT/HDPE复合材料的拉伸强度分别提高了50%和356%。

Effect of multistage stretching extrusion on morphology and property of organic nano montmorillonite/high density polyethylene composites

Organic nano-montmorillonite/high density polyethylene (OMMT/HDPE) composites were prepared by multistage stretching extrusion and traditional extrusion process. The morphological structure and property of the two different OMMT/HDPE composites were comparatively studied by wide-angle X-ray diffraction (WAXD), TEM, DSC, small-angle X-ray scattering (SAXS) and so on. The results indicate that multistage stretching extrusion shows great effect on refining particle size of OMMT and promoting dispersion of OMMT in HDPE matrix. With increasing of the number of layer multiplying elements (LMEs), the dispersion of OMMT is gradually improved and the length-to-diameter ratio of OMMT aggregation is also increased, leading to the enhanced initial nucleation rate and crystallization rate of OMMT/HDPE composites, inducing the formation of oriented shish-kebab structures in OMMT/HDPE composites. Accordingly, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion is greatly enhanced. When the mass ratio of OMMT:HDPE is 1:100 and 5:100, the tensile strength of OMMT/HDPE composites prepared by multistage stretching extrusion increases about 50% and 356% compared to that of OMMT/HDPE composites prepared by traditional extrusion process.