共聚焦拉曼成像技术研究PE⁃LD/EVOH共混物的三维相结构

Study on 3D phase structure in low density polyethylene/ethylene⁃vinyl alcohol copolymer(PE⁃LD/EVOH)blends through confocal Raman imaging

利用共聚焦拉曼成像技术研究了低密度聚乙烯(PE⁃LD)/乙烯⁃乙烯醇共聚物(EVOH)共混物中各相在压塑样品水平方向、深度方向和三维空间的分布情况,首次获得了PE⁃LD/EVOH共混物的三维相结构,并直观地将相区与共混物化学成分相对应。结果表明,PE⁃LD/EVOH共混物为不相容体系;当EVOH的质量分数为20%时,其作为分散相,以较规则的圆柱体形态分散于PE⁃LD基体中,圆柱直径尺寸在3~6μm范围内。加入马来酸酐接枝聚乙烯(PE⁃g⁃MAH)作为相容剂后,共混物的相态结构发生显著变化,分散相形状由规则变为不规则,截面的平均尺寸减小到约2μm,这说明PE⁃g⁃MAH可显著增强PE⁃LD与EVOH两组分间的界面相容性。

The phase structure of polymer blends directly affects the macroscopic properties of the materials;therefore,it is important to investigate the size and spatial distribution of each phase.In this work,the confocal Raman imaging tech⁃nique was adopted to study the distribution of phases of PE⁃LD/EVOH blends in the horizontal and depth directions and 3D space in the compression⁃molded specimens.The phase structure of PE⁃LD/EVOH blends in 3D space was obtained at the first time,and the phase region visually corresponded to the chemical composition of the blends.The results indi⁃cated that the PE⁃LD/EVOH blends were immiscible system.20 wt%EVOH could be dispersed in the PE⁃LD matrix in a regular cylindrical form with a diameter of the cylinder in the range of 3~6μm.The introduction of polyethylene grafted with maleic anhydride(PE⁃g⁃MAH)made the phase structure change significantly from the regular to irregular shape,and the cross⁃section size was reduced to 2μm.This indicates that PE⁃g⁃MAH can enhance the compatibility be⁃tween PE⁃LD and EVOH significantly.