Nanohybrids of novolac phenolic resin and carbon nanotube-containing silica network

Abstract

Two different methods were used for preparation of novolac phenolic resin nanohybrids containing carbon nanotube and silica/siloxane moieties. Oxidized carbon nanotube was modified with furfuryl alcohol and 3-(trimethoxysilyl)propyl methacrylate (MPS) to obtain CNTFASi. Carbon nanotube xerogel (CNTFAX) was then obtained by incorporation of CNTFASi into silica/siloxane network by using tetraethyl orthosilicate (TEOS). The first nanohybrid was prepared by addition of CNTFAX into the novolac phenolic resin matrix. Incorporation of (3-glycidyloxypropyl) trimethoxysilane-modified novolac phenolic resin, CNTFASi, and TEOS into silica/siloxane network results in the second nanohybrid. These two types of nanohybrids were compared from the viewpoint of thermal properties. Successful modification of carbon nanotube and novolac phenolic resin was proved by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis results. Molar ratios of furfuryl alcohol in CNTFA and MPS in CNTFASi are 597 and 108 μmol g−1, respectively. Formation of silica/siloxane xerogel network in CNTFAX was evaluated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that nanotubes with smooth surface are incorporated into the spongy silica/siloxane matrix. Char residue of CR is decreased from 58.2 to 50.6% by the addition of only 4 mass% of CNTFAX. Finally, char residue of 71.1% for the nanohybrid of modified novolac resin with 4 mass% of CNTFASi shows 12.8% increase in char residue with respect to the neat cured resin.