Preparation of liquid crystal 4'-allyloxy-biphenyl-4-ol functionalized MWCNTs and their application on improving mechanical and thermal properties of silicon resin

Abstract

A liquid crystalline molecule, 4'-allyloxy-biphenyl-4-ol (AOBPO), was used to functionalize carbon nanotubers (CNTs) via physical means and chemical means, respectively. The physically functionalized CNTs (AOBPO-CNTs) and chemically functionalized CNTs (AOBPO-O-CNTs) were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), fluorescent spectroscopy, and Raman spectroscopy. The two functionalized CNTs were mixed with silicone resin as fillers to fabricate organosilicone nanocomposites. Scanning electron microscopy (SEM) images indicated that the dispersion of CNTs in silicone resin and compatibility of CNTs with silicone resin were improved effectively after functionalization with liquid crystal via physical or chemical means. The thermal and mechanical properties testing indicated that, the chemically functionalized CNTs got a better effect in improvement of mechanical properties of silicon resin than the physically functionalized CNTs, whereas the physically functionalized CNTs was more applicable to enhance the thermal conductivity of silicon resin. The tensile strength of AOBPO-O-CNTs/silicon resin increased by 37.8% over that of neat CNTs/silicon resin when the mass fraction of AOBPO-O-CNTs was 1.0%, and the elastic modulus of AOBPO-O-CNTs/silicon resin increased by 32.8% over that of CNTs/silicon resin if it came up to 2.0%. The thermal conductivity of the resin filled with AOBPO-CNTs was improved to be 1.176 W (m−1 K−1) at the mass fraction of 5.0%, which was enhanced more than 73.2% over that of CNTs/silicon resin. POLYM. ENG. SCI., 56:1118–1124, 2016. © 2016 Society of Plastics Engineers