一种液晶共聚酯/粘土纳米复合材料的制备及其相转变温度

一些无机微粒被广泛用做聚合物的增强材料，其中特别引起人们注意的是一种粘土，即蒙脱土（ｍｏｎｔｍｏｒｉｌｌｏｎｉｔｅ）．蒙脱土具有层状结构，其特点一是微粒尺寸小，二是可以和多种单体发生插层聚合反应，给出聚合物／蒙脱土纳米复合材料［１～３］．纳米复合材料指的是其基质中分散相的尺寸至少有一维小于１００ｎｍ数量级的复合材料．由于其纳米尺度效应、大的比表面积以及强的界面相互作用，纳米复合材料的物理力学性能优于相同组分常规复合材料．因此，无论从基本理论研究角度还是从应用角度上看，对聚合物纳米复合材料的研究都…

STUDY ON PREPARATION AND PHASE TRANSITION TEMPERATURE OF LIQUID CRYSTAL COPOLYESTER/CLAY NANOCOMPOSITES

The liquid crystalline copolyester (LCP)/montmorillonite nanocomposites were prepared by polycondensation of terephthalic acid, p |acetoxy benzoic acid and 1,2|diacetoxy benzene,in the presence of an organically modified montmorillonite(OMt) with p |aminobenzoic acid hydrochloride.The cleavage effect of OMt and the liquid|crystalline behavior of the composites were described.;The cleavage effect of OMt was examined by X|ray diffraction (XRD) and transmission electron microscopy (TEM).Room|temperature XRD spectra were collected from 2θ=2° to 2θ=10°. The eventual disappearance of any distinct X|ray diffraction peaks for the hybrid containing 2,3,or 5wt% OMt indicated the well dispersion of its original layer structure.The TEM micrograph showed that the silicate layer spacings were greater than 3nm,even some layers dispersed in polymer matrix individually.;The glass transition temperature T -g of the LCP/OMt nanocomposites increased slightly as compared with the pure polymer,but the isotropic temperatues T i decreased more significantly as the content of OMt increased.As the clay content increased up to 3%,the decrease of T i reached 25℃.LCP chains separated in certain degree by inorganic phase decreased the ordering ability of mesogenic units.This may be the principal reason for the descent of T i.;The nematic texture of nanocomposites was observed by POM,and the schlieren texture became indistinct as the clay content increased.Although the schlieren texture in POM for the hybrid with clay content up to 5% still could be observed,the evident location of disinclination point already cant be found.Thus,the mechanism of disinclination in nematic phase for LCP hybrid with OMt is more complicated than that for pure polymer.