Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Study on Preparation, Structure and Properties of EVOH/Montmorillonite Nanocomposites

Author XueQiong
Tutor LiuYueJun;XiangXianWei
School Hunan University
Course Materials Science
Keywords EVOH nanocomposite montmorillonite properties fusing-intercalation
CLC TB383.1
Type Master's thesis
Year 2009
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Polymer/Layered Silicate (PLS) nanocomposites is a new type of composites based on polymers that filled with silicate layers in nanoscale dispersion. PLS nanocomposites have been widely studied in recent years because of its amazing performances in mechanical, thermal, optical and physical-chemical properties compared to the pure polymers or cinventional composites.In this paper, the preparation, characterization and properties of ethylene-vinyl alcohol (EVOH/MMT) nanocomposites were studied. The main contents summarized as follows:Firstly, the montmorillonite was treated by different surfactants. The modified MMT was analyzed by FT-IR, XRD and SEM, and its compatibility with the polymer was researched. The results indicated: double octadecyl dimethyl ammonium chloride was best among cationic modifier. The layer distance of montmorillonite was increased from 1.42nm to 3.5nm. the compatibility of montmorillonite clay and the polymer was best when the amount of silicon hydride resin acceptor KH550 was 5% (quality score).Secondly, EVOH/OMMT nanocomposites were prepared by solution-intercalation and fusing-intercalation. And the nanocomposites was treated by UV-irradiation. The result showed that fusing-intercalation was better than solution-intercalation; the mechanical properties and barrier Performance of EVOH/montmorillonite nanocomposites were improved greatly after UV treatment for 8h.Finally, the crystallization, rheology, mechanical properties, optical property and barrier properties of EVOH/montmorillonite nanocomposites were researched which was prepared by fusing-intercalation and treated by UV. It was indicated that the montmorillonite clay had inserted to the EVOH polymer evenly, the layer distance was increased furtherly, and some exfoliated and intercalated nanocomposites were produced analyzed by FT-IR, XRD and SEM. It was showed that few montmorillonite clay have the heterogeneous nucleation action and can enhance the crystallinity of the polymer. The data also showed that the melt of EVOH/montmorillonite nanocomposite was a type of non-Newtonian fluid, and the viscosity decreases with the increase of the shear rate. That means a shear-thinning phenomenon; The viscosity was enhanced with the increase of montmorillonite. The Tensile strength, oxygen permeability of nanocomposite with 5% OMMT was increased 26% and 21% respectively. But the tear strength and water vapor permeability of nanocomposite with 3% OMMT was increased 20% and 38% respectively. However, the impact strength of nanocomposite with 1% OMMT was increased 29%. The optical property was not distinct with the change of nanocomposite.

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