聚烯烃共混物分散相尺寸梯度分布形态形成速度影响因素的研究

研究了聚烯烃高分子共混物的初始相形态及相间界面张力的改变对退火热处理条件下共混物分散相尺寸分布梯度形态形成速度的影响．通过控制共混物共混过程中Ｂｒａｂｅｎｄｅｒ转子的转速来控制共混物所受的剪切力大小，可达到控制共混物初始相形态的目的．通过ＳＥＭ电镜观察相形态，并利用计算机图象分析仪得到分散粒子的粒径及其分布数据．研究结果表明，转子转速越大，即共混物所受的剪切力越大，分散相初始粒径越小，且分散也越均匀．初始粒径较小的样品退火后形成梯度的速度相对较快．选用体系聚丙烯（ＰＰ）／乙烯 醋酸乙烯酯共聚物（ＥＶＡｃ）、聚乙烯（ＰＥ）／ＥＶＡｃ及改变ＥＶＡｃ中的醋酸乙烯酯（ＶＡｃ）含量与ＰＥ共混对比研究了不同相界面张力对梯度化速度的影响．结果表明，上述各体系退火热处理后均可形成梯度相形态，且相间界面张力越大．高分子共混物中梯度相形态形成速度也越快

STUDY ON THE FORMATION RATE OF GRADIENT PHASE MORPHOLOGY IN THE POLYMER BLENDS

The effects of the initial phase morphology and interfacial tension were investigated on the formation of gradient morphology in the polymer blends.For the same blends system, different initial phase morphology can be obtained by changing the rotating rate of the rotor during mixing. By means of scanning electron microscope(SEM), the morphologies of the polymer blends before and after annealing were examined. Computer Image Analyzer was also applied to get the information about the radius and distribution of the dispersed phase.It was found that the initial diameter of the dispersed phase particles decreased with increasing the rotating rate of the rotor. After annealing for a certain time, the blend system with smaller initial dispersed particle size shows faster speed for the formation of gradient morphology. However,if the initial particle size is too small, it could be predicted that the formation of gradient morphology is difficult during a certain period of time. So it is expected that there is an optimum initial diameter for the formation of gradient morphology.The blend systems with different interfacial tension can be got through blending PP/EVAc、PE and EVAc with various VAc contents. It was found that all the blend systems could form gradient morphology under certain annealing conditions. The larger the interfacial tension in the blends, the faster the formation speed of gradient morphology. Interfacial tension as the driving force for dispersed phase droplet coarsing plays an important role in the formation of gradient morphology.