Large Scale Production Of Water-Dispersible Carbon Nanotubes And Its Biocomposites Using Sodium Alginate

Carbon nanotubes (CNTs) have attracted a huge amount of attention in recent years because of their unique electronic, mechanical, and structural properties. However, the application of CNTs is greatly limited by their insolubility in solvents, and many attempts have been made to improve the solubility of CNTs in common solvents. Two widely used method have been attempted, which are covalent arid noncovalent modifications. In this thesis, the biomacromolecular polysaccharide sodium alginate (SA) was used to improve the dispersion of CNTs in aqueous solution by nonconvalent modification1. The dispersion and rheological behavior of CNTs in aqueous solutions of SA were investigated by TEM and rheology. TEM photos showed that MWNTs could disperse individually in dilute. aqueous solutions by wrapping of SA onto MWNTs. The rheology measurements showed that high content MWNTs also could disperse in concentrated SA aqueous solutions by Cole-Cole and Cox-Merz rule analysis. The effects of temperature and NaCl on rheology behavior of SA/MWNTs system were investigated. The results showed that the sensitivity of temperature and NaCl effects on the viscosity of SA/MWNTs solutions decreased by the presence of MWNTs, however, the rheology behavior of SA/MWNTs solutions was the same as to SA solutions basically.2. The effects of MWNTs on the degradation of SA aqueous solutions have been reported in this work by rheology. It was found that the addition of MWNTs to SA solutions could inhibit the degradation of SA because MWNT that has the ability of radical scavengers behave as antioxidants during the course of SA degradation. The results showed that the content of MWNT has an important effect on the degradation of SA, which suggested that the degradation of SA could be controlled by the content of MWNT. The UV degradation of SA was also inhibited in the presence of MWNT. It was found that MWNT dispersed in solutions of SA were stable for nearly one month by using Cole-Cole and Cox-Merz rule analysis.3. This study dealt with the development of a clean and safe process for water pollution remediation. The SA-Ca and SA/MWNTs-Ca gel beads were prepared in CaCl2 solution. Their adsorptions were investigated by measuring the removal of methyl orange (MO) of different charges from aqueous solutions. The remove rate of the beads had been compared with that of non-encapsulated MWNTs. The results showed that the remove rate of MO from aqueous solutions using SA-Ca gel beads was very low, and it could be improved sharply with the increasing of the content of MWNTs in SA/MWNTs-Ca gel beads. The amount of SA/MWNTs-Ca gel beads had significant effect on adsorption of MO. Effect of pH on adsorption of MO by using SA/MWNTs-Ca gel beads had been studied and adsorption is found to increase with decreasing pH.4. MWNTs were dispersed in water in the presence of SA and then converted into biofibers simply by adding a crosslinking agent such as CaCl2 through wet spinning. The resuts showed that the strength of SA/CNTs biofibers was improved substantially by the presence of well-dispersed MWNTs. The properties of these SA/CNTs fibers were dependent on the processing conditions, i.e., concentration of SA, ratio of SA to CNTs and the composition of the coagulation bath. Moreover, SA/MWNTs biofibers increased the anti-salt adsoption capability slightly and keep the good water-adsorption property of SA fiber.