Incorporation of epoxy resin and carbon nanotube into silica/siloxane network for improving thermal properties

Abstract

Thermal properties of epoxy resin (E) were improved by its incorporation into silica/siloxane network in the presence of carbon nanotube (CNT). At first, CNT xerogel (CNTX)/E composite was prepared by curing E in the presence of CNTX. Then, E is modified with (3-isocyanatopropyl)triethoxysilane (IE) or tetraethyl orthosilicate (TEOS) oligomer (TE) for its incorporation into a hybrid network of CNT-containing silica/siloxane network. For this purpose, a bifunctional modifier of 1,1′-(hexane-1,6-diyl)bis(3-(3-(trimethoxysilyl)propyl)urea) (HDBTMSPU) was synthesized. CNTX was prepared by incorporation of HDBTMSPU-modified CNT (FCNT) into silica/siloxane network by using HDBTMSPU and TEOS. IE (TE), FGO, HDBTMSPU, and TEOS were also used in the preparation of hybrid products. Three types of composites were compared in their thermal degradation temperature and char content. Functionalization of CNT was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman, X-ray diffraction (XRD), and thermogravimetric analysis (TGA) results. Xerogel formation was proved by Raman, XRD, and N2 adsorption and desorption isotherms. TGA results showed that the hybrid of IE, FCNT, and silica/siloxane network shows higher thermal properties. Char residue is increased 17.54 % by only 4 wt% loading of FCNT in IE resin (IEGX1). Formation of xerogel network around CNT was observed by scanning and transmission electron microscopies.