Phase morphology development in immiscible PP/(PS/PPE) blends influence of the melt-viscosity ratio and blend composition
Phase morphology development in immiscible PP/(PS/PPE) blends influence of the melt-viscosity ratio and blend composition
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DOI：
10.1016/s0032-3861(99)00048-8
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发表时间：
1999-11-01
期刊：
影响因子：
4.6
通讯作者：
Groeninckx, G
中科院分区：
文献类型：
--
作者：
Everaert, V;Aerts, L;Groeninckx, G
在熔体中制备了等规聚丙烯（PP）与含有不同浓度聚苯乙烯（PS）和聚（2，6-二甲基-1，4-苯醚）（PPE）的可混溶非晶相的不混溶共混物，研究了共混物组成和熔体粘度比p对相形态的影响。该模型共混物系统提供了独特的机会来改变可混溶的无定形PS/PPE相的组成，而不影响全局界面张力，这是相形态发展的关键参数。所有不相容的PP/（PS/PPE）共混物在同向双螺杆微型挤出机中在恒定的加工条件下制备。相转化区的位置与粘度比密切相关。在该区域观察到复合物样形态。为了能够区分液滴破碎和聚结对粒度的影响，使用仅含有1重量%的聚结剂的共混物。在粘度比为0.05至20的范围内研究了分散相。结果表明，共混物相形态对粘度比的明显依赖性;高粘度基质（p远小于1）由于其向分散相的有效剪切应力传递和作用于其上的较高分散力而增强液滴破碎;低粘度基质（p > 1）通常用作分散相的润滑剂，减少液滴破碎。粘度比对液滴破碎的影响反映在分散相浓度高达20重量%的共混物的粒径中。在后一种情况下，与文献中的建议不同，具有低粘度比（p < 1）的共混物提供了朝向精细且稳定的相形态的最佳方法。含有较高浓度的次要相（>20重量%）的共混物在熔融混合过程中表现出强烈的聚结;粘度比对最终共混物相形态的影响变得不那么明显，并且在p = 1时观察到最细的分散体。只有其中必须分散高粘性相的较低粘性基质的共混物由于变化的总体熔体粘度的强烈影响而不遵循先前的趋势。一个静态的共混物的热处理表明，分散相的浓度是最重要的因素，确定在具有几乎相等的熔体粘度的共混物相粗化。将高粘度组分与低粘度组分共混似乎抵消静止相粗化。(C)1999 Elsevier Science Ltd.保留所有权利。
Immiscible blends of isotactic polypropylene (PP) with a miscible amorphous phase containing varying concentrations of polystyrene (PS) and poly (2,6-dimethyl-1,4-phenylene ether) (PPE) were prepared in the melt, to study the influence of the blend composition and the melt-viscosity ratio, p, on the phase morphology. This model blend system offers the unique opportunity to vary the composition of the miscible amorphous PS/PPE phase, without affecting the global interfacial tension, a crucial parameter with respect to phase morphology development. All immiscible PP/(PS/PPE) blends were prepared in a co-rotating twin-screw mini-extruder under constant processing conditions. The location of the phase inversion region was strongly related to the viscosity ratio. A composite-like morphology was observed in this region. To be able to separate the effects of droplet break-up and coalescence with respect to particle size, blends containing only 1 wt.% dispersed phase were investigated over a viscosity ratio range from 0.05 to 20. The results showed a clear dependence of the blend phase morphology on the viscosity ratio; highly viscous matrices (p much less than 1) enhance droplet break-up due to their efficient shear stress transfer towards the dispersed phase and the higher dispersive forces acting on it; low viscous matrices (p > 1) often act as a lubricant for the dispersed phase reducing droplet break-up. The influence of the viscosity ratio on droplet break-up is reflected in the particle diameter in blends with a concentration of the dispersed phase up to 20 wt.%. In the latter case, blends with a low viscosity ratio (p < 1) offer the best approach towards a fine and stable phase morphology, unlike suggestions in the literature. Blends containing higher concentrations of the minor phase (>20 wt.%) exhibit strong coalescence during melt-mixing; the influence of the viscosity ratio on the final blend phase morphology becomes less obvious, and the finest dispersion was observed at p = 1. Only blends of a lower viscous matrix in which a highly viscous phase has to be dispersed, do not follow the previous tendency as a result of the strong impact of a changing overall melt-viscosity. A quiescent thermal treatment of the blends showed that the concentration of the dispersed phase is the most important factor determining phase coarsening in blends having nearly equal melt-viscosities. Blending a highly viscous component with a low viscous component seems to counteract quiescent phase coarsening. (C) 1999 Elsevier Science Ltd. All rights reserved.