No abstract

Multi-walled carbon nanotubes (MWNTs) were separately modified using chitosan (CS) through covalent grafting (MWNTs-CS) and non-covalent blending (MWNTs/CS). The modified MWNTs were characterized by FTIR, SEM, XRD, thermogravimetric analysis (TGA), and UV-vis spectroscopy. Then, they were incorporated into starch to compare their effects on the structure and properties of the resulting nano-composite films. The results showed that CS and MWNTs were homogeneously mixed in MWNTs-CS, while they were self-aggregated in MWNTs/CS. Moreover, MWNTs-CS presented a better dispersion property in aqueous solution and in starch matrix, compared with MWNTs/CS. Loading of MWNTs-CS into starch not only improved the tensile strength and Young's modulus of the composite films, but also simultaneously increased the elongation at break. However, addition of MWNTs/CS just made the composite films more brittle. Furthermore, the migration rate of MWNTs-CS from films to aqueous solution was lower than that of MWNTs/CS when their composite films were immersed in water. The better performance of the composite films containing MWNTs-CS compared with those containing MWNTs/CS can be attributed to the enhanced dispersion of MWNTs-CS and improved interfacial adhesion with starch. Therefore, MWNTs-CS are regarded as promising nano-fillers to reinforce biopolymers and thus promote their applications in food packaging and biomedical areas. Starch/Stärke 2016, 68, 220-229 Comparison studies on covalently and non-covalently modified MWNTs. . .