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首页> 外文学位 >Nucleating agent-assisted preparation of polypropylene (PP)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites and their characterization.
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Nucleating agent-assisted preparation of polypropylene (PP)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites and their characterization.

机译：聚丙烯（PP）/多面体低聚倍半硅氧烷（POSS）纳米复合材料的成核剂辅助制备及其表征。

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摘要

This study investigated the interactions between the molecules of polyhedral oligomeric silsesquioxane (POSS) and sorbitol-type nucleating agents in the development of self-assembled nanoparticles in polypropylene (PP). The nanocomposites thus developed were spun into fibers and the fiber mechanical properties were evaluated as function of POSS chemical structure, POSS content, and nucleating agent content. Two types of POSS were chosen—trisilanolphenyl-POSS (ph-TPOSS) and octaisobutyl-POSS (bu-MPOSS). The former was incompatible with PP but offered strong hydrogen bonding possibility with the nucleating agent. The latter did not interact with the nucleating agent but was compatible with PP. Di(benzylidene)sorbitol (DBS) was used as the nucleating agent, which formed three-dimensional fibrillar networks in PP upon cooling. The hydrogen bonding interactions with DBS improved dispersion of ph-TPOSS in PP and led to formation of POSS nanoparticles with diameter 25–200 nm. It was found that spun fibers of typical PP formulation with 0.3 wt% DBS and 10 wt% ph-TPOSS showed close to 70% reduction in diameter and offered 45% increase in modulus and 50% increase in tensile strength compared to unfilled PP. A pressure-driven flow through rectangular shear-cell yielded information on the effect of ph-TPOSS on the development of relative averaged birefringence and the formation of skin-core morphologies. It was found that ph-TPOSS nanoparticles retarded the local relaxation of oriented PP chains. Accordingly, the skin layer thickness increased compared to PP in the presence of 0.3 and 0.5 wt% ph-TPOSS. The crystallization occurred more rapidly when DBS and ph-TPOSS were present. It was found that fibrillar network formation by DBS was hindered in the presence of ph-TPOSS, which was attributed to formation of hydrogen bonding. No such hydrogen bonding occurred in the case of bu-MPOSS and accordingly, DBS fibrillation took place and crystallization occurred without interference by bu-MPOSS molecules. The study also identified that ph-TPOSS molecules can condense if the processing temperature is raised above 210°C.
机译：这项研究调查了多面体低聚倍半硅氧烷（POSS）分子与山梨糖醇型成核剂在聚丙烯（PP）自组装纳米颗粒发展中的相互作用。将由此开发的纳米复合材料纺成纤维，并根据POSS化学结构，POSS含量和成核剂含量对纤维的机械性能进行评估。选择了两种类型的POSS：三硅烷醇苯基-POSS（ph-TPOSS）和八异丁基-POSS（bu-MPOSS）。前者与PP不相容，但与成核剂有很强的氢键结合可能性。后者不与成核剂相互作用，但与PP相容。二（亚苄基）山梨醇（DBS）被用作成核剂，其在冷却时在PP中形成三维纤维状网络。与DBS的氢键相互作用改善了ph-TPOSS在PP中的分散性，并导致形成直径25-200 nm的POSS纳米颗粒。已发现，与未填充的PP相比，具有0.3 wt％的DBS和10 wt％的ph-TPOSS的典型PP配方的纺丝纤维直径减小近70％，模量增加45％，拉伸强度增加50％。压力驱动的流经矩形剪切池的流量产生了有关ph-TPOSS对相对平均双折射的发展以及皮芯形貌形成的影响的信息。发现ph-TPOSS纳米粒子阻碍了取向PP链的局部松弛。因此，与在0.3和0.5重量％的ph-TPOSS存在下的PP相比，表皮层厚度增加。当存在DBS和ph-TPOSS时，结晶发生得更快。发现在ph-TPOSS存在下，DBS阻止了原纤维网络的形成，这归因于氢键的形成。在bu-MPOSS的情况下没有发生这样的氢键，因此，发生了DBS原纤化并且发生了结晶，而没有bu-MPOSS分子的干扰。研究还发现，如果将加工温度提高到210°C以上，ph-TPOSS分子就会凝结。

著录项

  • 作者

    Lee, Byoung-Jo.;

  • 作者单位

    The University of Akron.;

  • 授予单位 The University of Akron.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 248 p.
  • 总页数 248
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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