A comprehensive study on step-wise surface modification of C60: Effect of oxidation and silanization on dynamic mechanical and thermal stability of epoxy nanocomposite

Fullerenes (C-60) are regarded as exceptional reinforcing material in composites for their capability to enrich multi-functional properties. In the present work, pristine C-60 has been stepwise modified through oxidation in the presence of nitric acid and then silanized using 3-aminopropyltriethoxysilane (APTES) to generate oxygenated and siloxane functional group elements onto their surfaces. The morphological investigation of oxidized and silanized C-60 was done under FESEM and TEM. On the other hand, FTIR spectroscopy and TGA analysis confirms the attachment of oxygenated and siloxane functional groups. The increase in structural defect, creating sites for APTES grafting is evident from Raman spectroscopy. Epoxy nanocomposites were prepared by incorporating 0.5 wt% of pristine and stepwise modified C-60. The effect of surface modification of C-60 on epoxy nanocomposite is studied under DMA and TGA. The silanized Co/epoxy nanocomposite showed significant enhancement of storage modulus (similar to 491%) and enhanced intensity of tan S peak compared to the neat epoxy. This is mainly attributed to high energy absorption during viscoelastic motion. From the TGA, silanized Co/epoxy nanocomposite showed modest increment in initial decomposition temperature. This behavior is suggestive for potential espousal of silanized C-60 to enhance the stiffness and molecular relaxation of epoxy nanocomposites. (C) 2016 Elsevier B.V. All rights reserved.