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Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites / Shanmugam Nagendiran in Acta materialia, Vol. 58 N° 9 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3345–3356 Titre : Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites : Characterization of thermal, dielectric and morphological properties Type de document : texte imprimé Auteurs : Shanmugam Nagendiran, Auteur ; Muthukaruppan Alagar, Auteur ; Ian Hamerton, Auteur Année de publication : 2011 Article en page(s) : pp. 3345–3356 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : DGEBA  and  TGDDM  epoxy  resins  POSS  Nanocomposites  Thermal  and  dielectric  properties Résumé : Epoxy resin nanocomposites, based on the diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM), are prepared via in situ co-polymerization with 4,4′-diaminodiphenylsulfone (DDS) in the presence of octa-aminophenyl silsesquioxane (OAPS) at levels of up to 20 wt.% of the latter. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS (⩽3 wt.%). Thermogravimetric analysis indicates that the POSS–epoxy nanocomposites display high ceramic yields, suggesting improved flame retardancy. The increasing concentration of OAPS into epoxy–amine networks exhibits a decreasing trend in the values of dielectric constant compared with those values obtained from neat epoxy systems. The higher epoxy functionality present in TGDDM leads to nanocomposites which possess enhanced thermal stability and higher dielectric constants than the DGEBA-based nanocomposites. X-ray diffraction analysis reveals that the molecular level reinforcement of POSS cages occurs in both the cases of DGEBA- and TGDDM-based hybrid epoxy nanocomposites. Furthermore, homogeneous dispersion of POSS cages in the epoxy matrices is evidenced by scanning electron microscopy, which further confirms that the POSS molecule has become an integral part of the organic–inorganic inter-cross-linked network systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000947 [article] Octasilsesquioxane-reinforced DGEBA and TGDDM epoxy nanocomposites : Characterization of thermal, dielectric and morphological properties [texte imprimé] / Shanmugam Nagendiran, Auteur ; Muthukaruppan Alagar, Auteur ; Ian Hamerton, Auteur . - 2011 . - pp. 3345–3356. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 9 (Mai 2010) . - pp. 3345–3356 Mots-clés : DGEBA  and  TGDDM  epoxy  resins  POSS  Nanocomposites  Thermal  and  dielectric  properties Résumé : Epoxy resin nanocomposites, based on the diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamino diphenyl methane (TGDDM), are prepared via in situ co-polymerization with 4,4′-diaminodiphenylsulfone (DDS) in the presence of octa-aminophenyl silsesquioxane (OAPS) at levels of up to 20 wt.% of the latter. The curing reaction involving epoxy, DDS and OAPS is investigated using Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry and dynamic mechanical analysis show that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing nanocomposites are higher than the corresponding neat epoxy systems at lower concentrations of POSS (⩽3 wt.%). Thermogravimetric analysis indicates that the POSS–epoxy nanocomposites display high ceramic yields, suggesting improved flame retardancy. The increasing concentration of OAPS into epoxy–amine networks exhibits a decreasing trend in the values of dielectric constant compared with those values obtained from neat epoxy systems. The higher epoxy functionality present in TGDDM leads to nanocomposites which possess enhanced thermal stability and higher dielectric constants than the DGEBA-based nanocomposites. X-ray diffraction analysis reveals that the molecular level reinforcement of POSS cages occurs in both the cases of DGEBA- and TGDDM-based hybrid epoxy nanocomposites. Furthermore, homogeneous dispersion of POSS cages in the epoxy matrices is evidenced by scanning electron microscopy, which further confirms that the POSS molecule has become an integral part of the organic–inorganic inter-cross-linked network systems. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000947