Polypropylene (PP) compounds with varying amounts (0.4‐8.2 vol%) of tailored allyl‐isobutyl polyhedral oligomeric silsesquioxane (POSS) were prepared by melt‐blending. The dependence of the crystallization behavior and crystalline structure of PP on the melt‐state phase morphology of PP‐POSS materials is addressed. PP‐POSS systems were predicted to exhibit weak phase separation in both the molten and solid states based on Bagley plot using Hansen solubility parameters. Small‐amplitude shear rheometry analysis suggested that the highest loaded (8.2 vol%) PP‐POSS system behaves as a two‐liquid emulsion, whereas the low‐content POSS (0.4‐4.0 vol%) systems deviate from this model, resembling a polymer nanocomposite. Based on these findings we hypothesized the formation of a heterogeneous phase morphology in the molten state comprised of nano‐size “pseudo‐solid” POSS clusters and micrometer‐size “pseudo‐liquid” POSS droplets dispersed within the PP matrix, depending on the POSS content. Upon cooling, POSS droplets comingle, forming cube‐like micrometer‐sized crystal domains. The nonisothermal crystallization of PP is enhanced by the presence of POSS clusters. Small‐angle X‐ray scattering analysis revealed the formation of thinner and more heterogeneous folded chain PP lamellae in the PP‐POSS systems.

中文翻译：

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弱相分离PP-POSS材料的流变性质，相形态和结晶行为的调查

通过熔融共混制备各种量（0.4-8.2％（体积））量身定制的烯丙基-异丁基多面体低聚倍半硅氧烷（POSS）的聚丙烯（PP）化合物。解决了PP的结晶行为和晶体结构对PP-POSS材料的熔融态相形态的依赖性。根据使用Hansen溶解度参数的Bagley图，预测PP-POSS系统在熔融和固态状态下均表现出弱相分离。小幅度剪切流变仪分析表明，最高负载（8.2％（体积））的PP-POSS系统表现为两液乳液，而低含量POSS（0.4-4.0％（体积））的系统则偏离该模型，类似于聚合物纳米复合材料。基于这些发现，我们假设在熔融状态下形成了异相相形态，其中包括纳米级的“拟固” POSS团簇和微米级的“拟液” POSS液滴，这些液滴分散在PP基质中，具体取决于POSS内容。冷却后，POSS液滴融合在一起，形成了立方体大小的微米级晶畴。通过POSS团簇的存在可以增强PP的非等温结晶。小角度X射线散射分析表明，PP-POSS系统中形成了更薄，更不均匀的折叠链PP薄片。通过POSS团簇的存在可以增强PP的非等温结晶。小角度X射线散射分析表明，PP-POSS系统中形成了更薄，更不均匀的折叠链PP薄片。通过POSS团簇的存在可以增强PP的非等温结晶。小角度X射线散射分析表明，PP-POSS系统中形成了更薄，更不均匀的折叠链PP薄片。