Preparation of carbon nanotube and polyurethane‐imide hybrid composites by sol–gel reaction

Abstract

Polyurethane (PU) and carbon nanotube (CNT) hybrid composites with improved thermal stability were prepared by sol–gel reaction. Here, pyromellitic dianhydride (PMDA) and butanediol (BD) were used as two different chain extenders and the products were end‐functionalized with (3‐aminopropyl) triethoxysilane (APTES) to obtain PUI and PUBD, respectively. By incorporation of 3‐(trimethoxysilyl)propyl methacrylate (MPS)‐functionalized CNT and PU samples into the silica/siloxane network, two different hybrid composites were obtained and compared in degradation temperature and char residues. Fourier‐transform infrared (FT‐IR) spectroscopy and thermogravimetric analysis (TGA) confirmed successful modification of CNT with MPS. Absence of FT‐IR band of isocyanate groups confirms successful reaction of APTES with isocyanate groups in both PUBD and PUI. According to TGA results, the PUI hybrid composites with 4 wt% of CNTS showed char contents of 22.5%. Addition of 4 wt% of CNTS into the PUBD hybrid resulted in char residue of 21.2%. Therefore, the hybrid composites formed from PMDA showed higher degradation temperature and char residues. X‐ray diffraction showed an amorphous peak for crosslinked PU at near 2θ = 21.7°. The tubular structure of CNTS was confirmed by scanning and transmission electron microscopies. POLYM. COMPOS., 40:E1903–E1909, 2019. © 2018 Society of Plastics Engineers