界面张力在基板诱导共混物分散相粒子粗化生长加速现象中的作用

THE EFFECT OF INTERFACIAL TENSIONS ON THE ACCELERATION OF THE COARSENING IN POLYMER BLEND THIN FILM

通过相差显微镜和计算机图像处理来研究两相聚合物体系的粗化过程 .将具有不同聚比的乙烯 聚醋酸乙烯酯 (EVAc)共聚物与聚丙烯 (PP)共混 ,制备不同相界面张力的系列共混物薄膜 .观察了在玻璃基板的作用下 ,不同界面张力体系的分散相粒子粗化行为 ,发现界面张力在约 0 4 8·1 0 - 5N cm以上的体系中分散相粒子的粗化有明显的加速现象 ,粒子体积生长与时间关系的指数大于 1 0 ;而两相界面张力较低的情况下 ,选择具有不同表面极性的基板对同一体系试验 ,我们均未发现有粗化加速现象产生 ,且采用不同基板之间的试验结果差异很小 ,亦即当高分子共混物的相界面张力大于一定值时 ,仅与基板存在有关 。

The interfacial tension on coarsening process of the polymer blend thin film on substrate was studied by using a phase contrast microscope and computer image analyzer.The ethylene vinyl acetate copolymers (EVAc) with different contents of VAc were blended with polyproplyene (PP),and a series of PP/EVAc blends with differene interfacial tension was obtained.It was found that the coarsening process of the polymer blend 2D thin film on glass substrate was always accelerated when the interfacial tension is larger than a threshold value to be about 0.48·10 -5N/cm.When the interfacial tension of the blends is less than the threshold value,the coarsening process of the polymer blend thin film on glass substrate is as same as the bulk of the blend; i.e.no occurrence the phenomenon of the substrate induced coarsening process is.This result corresponds to our previous research results.Using substrates with various surface tensions,the coarsening processes of the polymer blend was found to be similar.In other words,the accelerated coarsening processes exist in all cases.The particle coarsening process only depends on the interfacial tension of the blend and the existing of the substrate,does not depend on the character of the substrate.