The spray‐freeze drying (SFD) technique was applied to sonicated aqueous suspensions of spray‐dried montmorillonite clay (MMT) to produce highly porous agglomerates (SFD‐MMT). Both MMT (used as a reference) and SFD‐MMT were subsequently incorporated in polypropylene (PP) via melt compounding to produce 2 wt % nanocomposites with and without maleic anhydride grafted polypropylene (PP‐g‐MA). Polypropylene nanocomposites containing SFD‐MMT exhibited thinner silicate flake layers compared to large agglomerates in PP/MMT nanocomposites. SFD‐MMT particles became even more finer in the presence of PP‐g‐MA (i.e., in PP/PP‐g‐MA /SFD‐MMT) where it hindered PP crystallization instead of serving as nucleation sites for the PP crystallization during rapid cooling. SFD‐MMT improved the thermal stability of PP/PP‐g‐MA by 30°C compared to only 5–8°C for MMT/nanocomposites. MMT acts as a heterogeneous nucleating agent in the nucleation‐controlled PP nanocomposites, but the hindrance effect was observed for the PP/PP‐g‐MA with SFD‐MMT. PP/PP‐g‐MA/SFD‐MMT exhibited twice the edge surface energy as compared to PP/PP‐g‐MA/MMT. The incorporation of both types of MMT raised the tensile moduli of PP and PP/PP‐g‐MA, with no improvement in their tensile strength and a decrease in the elongation at break. The PP/PP‐g‐MA/SFD‐MMT showed brittle failure. POLYM. ENG. SCI., 60:168–179, 2020. © 2019 Society of Plastics Engineers

中文翻译：

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蒙脱石的喷雾冷冻干燥对聚丙烯纳米复合材料的形貌，分散性和结晶的影响

喷雾冷冻干燥（SFD）技术应用于喷雾干燥的蒙脱土（MMT）的超声水悬浮液中，以产生高度多孔的团聚体（SFD-MMT）。随后将MMT（用作参考）和SFD-MMT均通过熔融混和法掺入聚丙烯（PP）中，以生成2 wt％的纳米复合材料，有或无马来酸酐接枝聚丙烯（PP- g- MA）。与PP / MMT纳米复合材料中的大团聚物相比，含有SFD-MMT的聚丙烯纳米复合材料的硅酸盐薄片层更薄。在PP‐ g存在下，SFD‐MMT颗粒变得更细-MA（即在PP / PP-g-MA / SFD-MMT中）阻碍了PP的结晶，而不是在快速冷却过程中成为PP结晶的成核位点。与MMT /纳米复合材料的5/8°C相比，SFD-MMT将PP / PP- g- MA的热稳定性提高了30°C。MMT在成核受控的PP纳米复合材料中起着异质成核剂的作用，但是对于具有SFD-MMT的PP / PP - g -MA则观察到了阻碍作用。PP / PP - g -MA / SFD-MMT的边缘表面能是PP / PP- g- MA / MMT的两倍。两种类型的MMT的结合均提高了PP和PP / PP- g‐ MA的拉伸模量，但拉伸强度没有改善，断裂伸长率也没有降低。PP / PP-g ‐MA / SFD-MMT表现出脆性故障。POLYM。ENG。SCI。，60：168–179，2020.©2019塑料工程师协会