The influence of extensional strain and strain rate on dispersed phase size during blending of a dilute mixture of vinyl polymers, high-density polyethylene in polystyrene, was examined; the viscosity ratio was substantially larger than four so that shearing was not expected to contribute to drop breakup. Coarse blends were formulated by employing an internal mixer, and these blends were processed through different converging dies attached to the outlet of a capillary viscometer. Variables included the die geometry and the volumetric flow rate. Average dispersed phase sizes were determined by analyzing scanning electron micrographs of sections of strands leaving the viscometer, and it was found that extensional flow was very effective in reducing the dispersed phase size. Coarse blends were also formulated by separately incorporating nanoparticles of hydrophobic fumed silica as well as hydrophilic fumed silica in the blends at a 4 wt% nanofiller level. This resulted in a significant reduction in drop size compared to the previous value; this was likely the result of lowered drop coalescence. These nanoparticle-containing blends were also subjected to extensional flow, and this resulted in a further reduction in the average dispersed phase size. However, the final result was only slightly better than that obtained previously with the help of extensional flow alone. This suggests the use of nanoparticle incorporation along with employing extensional flow when the presence of nanoparticles provides multifunctionality to the resulting blend.

中文翻译：

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拉伸流动和纳米填料掺入对高粘度比不混溶乙烯基聚合物共混中分散相尺寸的影响

研究了在混合乙烯基聚合物、高密度聚乙烯和聚苯乙烯的稀混合物时拉伸应变和应变速率对分散相尺寸的影响；粘度比明显大于四，因此预计剪切不会导致液滴破裂。通过使用密炼机配制粗混合物，并且这些混合物通过连接到毛细管粘度计出口的不同会聚模具进行加工。变量包括模具几何形状和体积流量。平均分散相尺寸是通过分析离开粘度计的线材截面的扫描电子显微照片来确定的，并且发现拉伸流动在减小分散相尺寸方面非常有效。粗共混物还通过在共混物中以 4 wt% 的纳米填料水平分别掺入疏水性气相二氧化硅和亲水性气相二氧化硅的纳米颗粒来配制。与之前的值相比，这导致液滴尺寸显着减小；这可能是液滴聚结降低的结果。这些含有纳米颗粒的共混物也经受拉伸流动，这导致平均分散相尺寸进一步减小。然而，最终结果仅比之前仅借助拉伸流获得的结果略好。这表明当纳米颗粒的存在为所得混合物提供多功能性时，使用纳米颗粒掺入以及使用拉伸流动。