Polymer nanocomposites based on transition metal ion modified organoclays
Polymer nanocomposites based on transition metal ion modified organoclays
复制标题
基于过渡金属离子改性有机粘土的聚合物纳米复合材料
DOI：
10.1016/j.polymer.2006.12.005
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发表时间：
2007
期刊：
影响因子：
4.6
通讯作者：
S. Khalid
中科院分区：
文献类型：
--
作者：
Pranav Nawani;P. Desai;M. Lundwall;M. Gelfer;B. Hsiao;M. Rafailovich;A. Frenkel;A. Tsou;J. Gilman;S. Khalid
制备了一类独特的含有催化活性过渡金属离子（TMI）改性的有机粘土和乙烯-醋酸乙烯酯（伊娃）共聚物的纳米复合材料。通过热重分析（TGA）、透射电子显微镜（TEM）、扩展X射线吸收精细结构（EXAFS）谱、X射线散射/衍射和振荡剪切流变仪研究了这些纳米复合材料的形貌、热性能和流变性能。三甲基咪唑改性的有机粘土被认为具有柱撑的多价TMI在层间硅酸盐画廊，导致层间d-间距显着减少。所得的纳米复合材料表现出显著改善的热稳定性和阻燃性能，但类似的形态（即，插层-剥离结构）和流变性能与含有未改性有机粘土的伊娃纳米复合材料相当。看来，压缩的有机组分在三甲基咪唑改性的有机粘土仍然可以促进聚合物分子的插层/剥离过程，特别是在广泛的剪切条件下。在具有TMI改性的有机粘土的纳米复合材料中改进的阻燃性可归因于在燃烧期间增强的含碳焦炭形成，即，催化活性TMI的存在促进了炭化。
A unique class of nanocomposites containing organoclays modified with catalytically active transition metal ions (TMI) and ethylene vinyl acetate (EVA) copolymers was prepared. The morphology, thermal and rheological properties of these nanocomposites were studied by thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS) spectroscopy, X-ray scattering/diffraction and oscillatory shear rheometry. TMI-modified organoclays were thought to possess pillaring of multivalent TMI in the interlayer silicate gallery, leading to a notable reduction of the interlayer d-spacing. The resulting nanocomposites exhibited significantly improved thermal stability and fire retardation properties, but similar morphology (i.e., an intercalated–exfoliated structure) and rheological properties comparable with EVA nanocomposites containing unmodified organoclays. It appears that the compressed organic component in the TMI-modified organoclay can still facilitate the intercalation/exfoliation processes of polymer molecules, especially under extensive shearing conditions. The improved fire retardation in nanocomposites with TMI-modified organoclays can be attributed to enhanced carbonaceous char formation during combustion, i.e., charring promoted by the presence of catalytically active TMI.