Preparation And Properties Of Multiwalled Carbon Nanotube/Polycarbonate Composites

In this study, the MWNT/Polycarbonate(PC) composites with different filler loadings were fabricated. The effects of MWNTs on the microstructure, mechanical property and thermostability of composites were mainly investigated.Hydroxyl functionalized multiwalled carbon nanotubes(H-MWNTs) were silanized using 3-aminopropyltriethoxysilane( KH550) to improve the dispersion of MWNTs and the interfacial strength between MWNTs and PC. Fourier transform infrared spectroscopy(FTIR) and energy dispersion spectroscopy analysis(EDS)were employed to prove the presence of KH550 on the surface of silanized MWNTs(S-MWNTs). Thermogravimetric analysis(TGA) was used to evaluate the relative amount of introduced KH550. After that, the nanocomposites filled with H-MWNTs and S-MWNTs were fabricated by melt mixing. The effects of H-MWNTs and S-MWNTs on the properties of nanocomposites were investigated by tensile test and dynamic mechanical analysis(DMA). The results showed that, compared with H-MWNT/PC composites, the storage modulus, tensile strength and toughness of S-MWNT/PC composites increased, respectively. Besides, the microstructure of nanocomposites(the dispersion state of nanotubes and the PC-MWNT interface) was carefully observed by SEM. The interfacial interaction between S-MWNTs and PC was further investigated by transmission electron microscope(TEM). The SEM and TEM results showed that the silanization can improve the dispersion of MWNTs in PC matrix and the interfacial adhesion between MWNTs and PC so as to enhance the properties of MWNT/PC nanocomposites.MWNTs are easy to form agglomerations in polymer matrix due to the entanglement between the nanotubes with high aspect ratio. Therefore, we attempted to improve the dispersion by reducing the length of MWNTs. The short multiwalled carbon nanotube(s MWNT)/PC and carboxylic functionalized short multiwalled carbon nanotube(s OMWNT)/PC composites were prepared by compression molding. The thermostability and tensile properties of both composites were investigated. The results showed that, compared with pure PC, the initial degradation temperature and mechanical property of s MWNT/PC composites decreased significantly. However, the s OMWNTs could enhance the tensile properties without decreasing the initial degradation temperature. In addition, the dynamic mechanical property of s OMWNT/PC composites was also investigated. The results showed that the glass transition temperature(Tg) decreased with increasing s OMWNTs loading and the storage modulus had a maximum value at 3 wt. %.