Browsing by Author "Yei, Ding-Ru"

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Effect of an organically modified nanoclay on low-surface-energy materials of polybenzoxazine
(2008-07-16)
Fu, Huei-Kuan
;
Huang, Chih-Feng
;
Kuo, Shiao-Wei
;
Lin, Han-Ching
;
Yei, Ding-Ru
Novel low surface free energy materials of polybenzoxazine/organically modified silicate nanocomposites have been prepared and characterized. The CPC (cetylpyridinium chloride)/ claylo%/poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PP-a) material possesses an extremely low surface free energy (12.7 Mj. M-2) after 4 h curing at 200'C, which is even lower than that of poly(tetrafluoroethylene) (22.0 Mj. M-2) calculated on the basis of the threeliquid geometric method. X-Ray photoelectron spectroscopy (XPS) shows a higher silicon content on the surface of the nanocomposites than for an average composition, which implies that the clay is more preferentially enriched on the outermost layer. In addition, the glass transition temperature (Tg) of the polybenzoxazine (PP-a) in the nanocomposite is 22.6'C higher and its thermal decomposition temperature is also 31.5'C higher than the pure PP-a. This finding provides a simple way to prepare low surface energy and high thermal stability materials.
Thermal properties of polystyrene nanocomposites formed from rigid intercalation agent-treated montmorillonite
(2007-07-15)
Yei, Ding-Ru
;
Fu, Hue-Kuan
;
Chang, Yu-Hsin
;
Kuo, Shiao-Wei
;
Huang, Jieh-Ming
Polystyrene (PS)/clay nanocomposites were prepared with two different new intercalation organophilic clays, the phosphonium salt (APP) and the ammonium 4-(4-adamantylphenoxy)-1-butanamine (APB) salts, by emulsion polymerization technique. X-ray diffraction and transmission electron microscopy were performed to characterize the layered structures of APB- and APP-treated polymer-clay nanocomposites, and both resulted in exfoliated structures. Molecular weights of PS obtained from these nanocomposites are slightly lower than the virgin PS formed under similar polymerization conditions. Coefficient of thermal expansion showed approximately a 44-55% decrease for APB- and APP-intercalated clay nanocomposites relative to the pure PS. Both T-g and thermal decomposition temperature of the PS component in the nanocomposite are higher than the virgin PS, implying that the presence of clay is able to enhance thermal stabilities of the PS. (c) 2007 Wiley Periodicals, Inc.