Starch-based films have promising application on food packaging, because of their environmental appeal,
low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties
should be improved. The aim of this work was to enhance these properties by reinforcing the films with
cellulose fibers. Besides, the influences of both the solubility coefficient of water in the films (b) and the
diffusion coefficient of water vapor through the films (Dw) on the films’ water vapor permeability (Kw)
were investigated. Films were prepared by the so-called casting technique, from film-forming suspensions
of cassava starch, cellulose fibers (1.2 mm long and 0.1 mm of diameter), glycerol and water. The
influence of fibers addition on Kw was determined at three relative humidity gradient ranges, DRH
(2–33%, 33–64% and 64–90%). Films reinforced with cellulose fibers showed higher tensile strength and
lower deformation capacity, and presented lower Kw than films without fibers. Kw showed strong
dependency of b and Dw, presenting values up to 2–3 times greater at DRH¼ 64–90% than at
DRH¼ 33–64%, depending on the film formulation. Therefore, adding cellulose fibers to starch-based
films is a viable alternative to improve their mechanical and water barrier properties. Besides, this work
showed the importance of determining film’s water vapor permeability simulating the real environmental
conditions the film will be used.
Starch-based films have promising application on food packaging, because of their environmental appeal,low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier propertiesshould be improved. The aim of this work was to enhance these properties by reinforcing the films withcellulose fibers. Besides, the influences of both the solubility coefficient of water in the films (b) and thediffusion coefficient of water vapor through the films (Dw) on the films’ water vapor permeability (Kw)were investigated. Films were prepared by the so-called casting technique, from film-forming suspensionsof cassava starch, cellulose fibers (1.2 mm long and 0.1 mm of diameter), glycerol and water. Theinfluence of fibers addition on Kw was determined at three relative humidity gradient ranges, DRH(2–33%, 33–64% and 64–90%). Films reinforced with cellulose fibers showed higher tensile strength andlower deformation capacity, and presented lower Kw than films without fibers. Kw showed strongdependency of b and Dw, presenting values up to 2–3 times greater at DRH¼ 64–90% than atDRH¼ 33–64%, depending on the film formulation. Therefore, adding cellulose fibers to starch-basedfilms is a viable alternative to improve their mechanical and water barrier properties. Besides, this workshowed the importance of determining film’s water vapor permeability simulating the real environmentalconditions the film will be used.
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