Surfactant-Free Method for the Synthesis of Poly(vinyl acetate) Masterbatch Nanocomposites as a Route to Ethylene Vinyl Acetate/Silicate Nanocomposites

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• 作者：Yaru Shi ; Scott Peterson ; Dotsevi Y. Sogah
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：April 3, 2007
• 年：2007
• 卷：19
• 期：7
• 页码：1552 - 1564
• 全文大小：897K
• 年卷期：v.19,no.7(April 3, 2007)
• ISSN：1520-5002

文摘

Poly(vinyl acetate) (PVAc)/silicate nanocomposites have been prepared using a novel surfactant-freemethod comprising a copolymer of 2-(acryloxyethyl)trimethylammonium chloride (AETMC) and vinylacetate (VAc) as the modifier for layered silicates. The nanocomposites maintained the exfoliatedmorphology even at silicate contents greater than 20 wt % as evidenced by the absence of peaks in theX-ray diffraction (XRD) patterns and absence of silicate bundles in the transmission electron microscopy(TEM) images. These high silicate-containing PVAc nanocomposites served as masterbatches for thepreparation of ethylene vinyl acetate (EVA)/silicate nanocomposites by solution blending with EVA. Acombination of XRD and TEM studies confirmed mostly exfoliated morphology for the finalnanocomposites containing varying amounts of silicate. Thermogravimetric analysis (TGA) in both nitrogenand air revealed that thermal stability of the nanocomposites in air was enhanced. Dynamic mechanicalanalysis (DMA) of the EVA/silicate nanocomposites over a temperature range of -70 to 50 C showedthat the storage moduli of the nanocomposites above the glass transition temperature were higher thanthose of the pure EVA and the corresponding intercalated EVA/silicate nanocomposites. The improvementin storage modulus of the nanocomposites was attributed to the exfoliated morphology and synergisticeffect of both the PVAc copolymer and the silicate. Thus, the EVA nanocomposite containing 5 wt %silicate showed a storage modulus fourfold higher than that of pure EVA and twofold higher than thatof EVA/PVAc blend.