PREPERATION, CHARACTERIZATION ANDPROPERTIES OF NOVOLAC TYPE PHENOLIC/SiO2HYBRID ORGANIC/INORGANIC NANOCOMPOSITEMATERIALS BY SOL-GEL METHOD

摘要

This article describes the preparation of novolac-type phenolic resin/silicahybrid organic-inorganic nanocomposite, using a sol-gel process. The coupling agent wasused to improve the interface between the organic and inorganic phases. The effect of thestructure of the nanocomposite on its physical and chemical properties is discussed.The coupling agent reacts with the resin to form covalent bonds. The structure of themodified hybrid nanocomposites was identified using a Fourier-transform infrared (FT-IR)spectroscope. The silica network was characterized by nuclear magnetic resonance imagingtechnique (29Si NMR). Results reveal that Q4 (tetra-substituted) and T3 (tri-substituted) are thedominant microstructures. The size of the silica in the phenolic resin was characterized usinga scanning electron microscope (SEM). The size of the particles of inorganic silica in themodified-system was less than 100 nm. The nanocomposite exhibited good transparency.Moreover, thermal and mechanical properties exhibited significant improvement. Themodified hybrid composite exhibited favorable thermal properties. The temperature at whichthe weight loss of 5% of sample(Td5)occurred increased from 281℃ to 350℃. The flexuralstrength increased by 6~30%. The limiting oxygen index (L.O.I.) of the nanocompositereached 37 and the materials were qualified by the Underwriters Laboratory (U.L.) 94V-0 test.These materials possess excellent flame-retardant properties.