Enhanced thermal Properties and Gas Barrier Property of PMMA Nanocomposites with Layered Silicate via Soap-Free Emulsion
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0951-E12-43
Enhanced thermal Properties and Gas Barrier Property of PMMA Nanocomposites with Layered Silicate via Soap-Free Emulsion Polymerization Hsiu-Yu Cheng1, and Guang-Way William Jang2 1 Polymer Hybrid, Industrial Technology Research Institude, Rm. 554, Bldg 6, 321, Kuang Fu Rd., Sec. 2, Hsinchu, 300, Taiwan 2 Polymer Hybrid, Industrial Technology Research Institude, Rm. 534, Bldg 6, 321, Kuang Fu Rd., Sec. 2, Hsinchu, 300, Taiwan ABSTRACT Polymer/SWN nanocomposites were synthesized in the soap-free emulsion polymerization of methyl methacrylate (MMA) using 2-hydroxylethyl methacrylate (HEMA). The SWN in the polymer/SWN nanocomposites was individually dispersed in water, and these are adsorbed on the surface of monomer droplets. Polymer/SWN nanocomposites were obtained by adding an aqueous dispersion of layered silicate to the polymer emulsion. X-ray diffraction (XRD) and FT-IR spectra were utilized to characterize the structures of the nanocomposites. The degree of dispersion of these nanocomposites was investigated by transmission electron microscopy (TEM). Furthermore, the thermal and mechanical properties of polymer/SWN nanocomposites were determined using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA). The increased tanδ of the obtained nanocomposites is caused by the fine dispersion of SWN particles into the polymer matrix. 1. Introduction In recent years, much attention has been paid to polymer/silicate nanocomposites, because they are stiffer and stronger, with only a small amount of silicate, than conventional composites. They exhibit dimensional stability and flame-retarding properties 1-2. The normal characterization of the structure of a nanocomposite requires X-ray diffraction (XRD) measurements to show changes in the d spacing of the clay and transmission electron microscopy (TEM) to image the individual clay layers and thereby reveal the exact nature of clay-polymer interaction.Thermogravimetric analysis (TGA) has been employed and the onset temperature of thermal degradation exceeds that of virgin polymer in same systems 3,4,5 but other systems have displayed no difference.6 Dynamic mechanical analysis (DMA) indicates either an increase or no change in the storage modulus and the glass transition temperature, Tg.7,8 Nanocomposites that are produced in interactions between layered silicates and polymers are of two types-intercalated and exfoliated. Studies indicate that exfoliated nanocomposites have higher Youngís moduli than intercalated nanocomposites, 9 larger elongation at break, 10 and better thermal stability.11 The extent of exfoliation strongly affects the improvement of the properties. Exfoliation adsorption in an emulsion with Na+ montmorillonite, known to readily delaminate of clay in water, has been examined to improve the intercalation of water-insoluble polymers. Lee et al. indicated that only intercalated nanocomposites were obtained in systems of poly(methyl methacrylate) (PMMA),12 polystyrene (PS),13 SAN14ñ16 an
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