Effect of cellulose fibers on the crystallinity and mechanical properties of starch-based films at different relative humidity values

The objective of this study was to investigate the effect of the addition of cellulose fibers on the mechanical and physicochemical properties of starch-based films plasticized with glycerol. Film samples were prepared from solutions with 3% of cassava starch, with the addition of 0, 0.10, 0.30 and 0.50 g of fibers/g of starch. The mechanical properties of samples conditioned at different relative humidity (RH) values were determined through tensile and stress relaxation tests. SEM micrographs of the films showed a homogeneous and random distribution of the cellulose fibers, without pores or cracks. Films with fibers were more crystalline and had higher tensile strength and rigidity, but lower elongation capacity. On the other hand, addition of cellulose fibers increased the stability of starch-based films subjected to RH variations, solving a classical problem encountered with this kind of film. Thus, the addition of cellulose fibers to starch-based films is an effective way to prepare stronger and more stable films.