Comparison studies on covalently and non‐covalently modified MWNTs using chitosan and their starch nanocomposites
2016
Gou, Zhenqiong | Xu, Dan | Dong, Quan | Wu, Xiyu
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.
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