Characterisation of biocomposite film made of kefiran and carboxymethyl cellulose (CMC)

This study was carried out to characterize the physical, mechanical and barrier properties of kefiran-carboxy methyl cellulose (CMC) biocomposite films in function with CMC content. Films were prepared by combining these two biopolymers and adding glycerol as plasticizer. Film-forming solutions of different ratios of kefiran to CMC were cast at room temperature. Increasing CMC content from 0 to 50 % (v/v) increased the tensile strength and extensibility of the composite films; however, with further CMC addition these mechanical properties decreased. The water-vapor permeability (WVP) of the films first decreased and then increased with CMC addition. The microstructure of the films was observed by scanning electron microscopy and atomic-force microscopy. The morphology study of the films showed rougher surfaces with increasing CMC amounts. Dynamic mechanical thermal analysis (DMTA) curves showed a single Tg, and addition of CMC at all levels increased the glass-transition temperature of films. These results indicated that these two film-forming components were compatible, and that an interaction existed between them.