Study On The Synthesis Of Carbon Nanotubes/Polyurethane Composites

In this paper, multi-walled carbon nano-tubes (MWNTs) were used to enhance polyurethane (PU) because of the excellent properties. First, MWNTs were acid-treated. Test means such as fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were utilized for studying the changes in the properties and morphology of acid-treated MWNTs. The results indicated that MWNTs were cut into many short carbon tubes, and arboxylic groups could be successfully introduced onto the surface of MWNTs by acid (H2SO4/HNO3= 3:1 in volume) treatment. The existence of arboxylic groups provided conditions for condensation reaction with hydroxyl groups, and improved the dispersion of MWNTs in polar compounds.The synthesis of MWNTs/PU composites of various concentrations via physical blending and in situ polymerization were done. The effects of the acid treatment to MWNTs and synthesis methods on the properties of the composites were analyzed and discussed by mechanical test, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The results showed that the addition of MWNTs improved the mechanical properties and thermodynamic performance of composites. The raw MWNTs had very poor dispersion and serious agglomeration in MWNTs/PU composites prepared via physical blending; The dispersion of acid-treated MWNTs was better than raw MWNTs, but it was still not satisfactory, agglomeration appearing. The mechanical properties, dynamic storage modulus, glass transition temperature and thermal stability of MWNTs/PU composites prepared via physical blending showed the trend of rising first, then delining with MWNTs increased. The acid-treated MWNTs could be more evenly dispersed in MWNTs/PU composites prepared via in situ polymerization. However, raw MWNTs were relatively poor dispersion and aggregation-prone. There was a rising trend in MWNTs/PU composites synthetized via in situ polymerization all the way. Compared with MWNTs/PU composites prepared via physical blending, the properties of MWNTs/PU composites prepared via in situ polymerization performed better.The dispersion of acid-treated MWNTs in MWNTs/PU composites was more uniform than raw MWNTs. The improvement of polyurethane by acid-treated MWNTs was more significant compared to raw MWNTs with the same content.