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1.
Characterization of bacterial cellulose films combined with chitosan and polyvinyl alcohol: Evaluation of mechanical and barrier properties
Patricia Cazón, Gonzalo Velazquez, Manuel Vazquez, 2019, original scientific article

Abstract: Bacterial cellulose (BC) produced by Komagataeibacter xylinus is a biomaterial with a unique three-dimensional structure. To improve the mechanical properties and reinforce the BC films, they were immersed in polyvinyl alcohol (0–4%) and chitosan (0–1%) baths. Moisture content, mechanical properties and water vapour perme- ability were measured to assess the effect of polyvinyl alcohol and chitosan. The morphology, optical, structural and thermal properties were evaluated by scanning electron microscopy, spectral analysis, thermogravimetry and differential scanning calorimetry. Results showed that moisture content was significantly affected by the chitosan presence. Tensile strength values in the 20.76–41.65 MPa range were similar to those of synthetic polymer films. Percentage of elongation ranged from 2.28 to 21.82% and Young's modulus ranged from 1043.88 to 2247.82 MPa. The water vapour permeability (1.47×10−11–3.40×10−11 g/m s Pa) decreased with the addition of polyvinyl alcohol. The developed films own UV light barrier properties and optimal visual appearance.
Keywords: Films, Bacterial cellulose, Water vapor permeability, Chitosan, Polyvinyl alcohol, UV protection
Published in RUNG: 14.12.2020; Views: 3122; Downloads: 0
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2.
Regenerated cellulose films with chitosan and polyvinyl alcohol: Effect of the moisture content on the barrier, mechanical and optical properties
Patricia Cazón, Manuel Vazquez, Gonzalo Velazquez, 2020, original scientific article

Abstract: The aim of this research was to evaluate the effect of moisture content on the mechanical, barrier and optical properties of films obtained from regenerated cellulose with chitosan and polyvinyl alcohol equilibrated at several relative humidity conditions. The experimental moisture adsorption isotherms were fitted using the Guggenheim-Anderson-DeBoer model. The adsorption isotherm showed a typical type II sigmoidal shape. The highest moisture content (27.53 %) was obtained at a water activity of 0.9. The water vapour permeability values increased up to 6.34·10−11 g/ m s Pa as the moisture content of the films increased. Tensile strength, percentage of elongation, Young’s modulus, burst strength and distance to burst showed a significant plasticizing effect of the water molecules. Results suggest that interactions between film components and water molecules decrease the transmittance in the UV region and the transparency. Consequently, water molecules improve the UV-barrier properties of the films and increasing the opacity.
Keywords: Adsorption isotherms, Plasticization, Regenerated cellulose, Chitosan, Polyvinyl alcohol, Water vapour permeability, Moisture content
Published in RUNG: 09.12.2020; Views: 3657; Downloads: 0
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