title: Effect of equilibrium moisture content on barrier, mechanical and thermal properties of chitosan films.
abstract: Water molecules modify the properties of biodegradable films obtained from hydrophilic materials. Most studies dealing with thermal, mechanical and barrier properties of hydrophilic films are carried out under one relative humidity (RH) condition. The objective of this work was to evaluate the effect of the moisture content on the thermal, mechanical and barrier properties of chitosan films under several RH conditions. Microclimates, obtained with saturated salt solutions were used for conditioning samples and the properties of the films were evaluated under each RH condition. Chitosan films absorbed up to 40% of moisture at the higher RH studied. The percentage of elongation and the water vapour permeability increased while tensile strength, Young's modulus and glass transition temperature decreased, when the moisture content increased. The results suggest that the water molecules plasticized the polymer matrix, changing the properties when the films were in contact with high RH environments.
authors.affiliation: Instituto Politécnico Nacional, CICATA Unidad Querétaro, Cerro Blanco 141, Colinas del Cimatario, 76090 Querétaro, Qro, Mexico.
authors.forename: Rocío Yaneli
authors.initials: RY
authors.lastname: Aguirre-Loredo
authors.affiliation: Instituto de Ciencias Agropecuarias, Universidad Autónoma del Estado de Hidalgo, Avenida Universidad km 1, Rancho Universitario, CP. 43600 Tulancingo, Hidalgo, Mexico.
authors.forename: Adriana Inés
authors.initials: AI
authors.lastname: Rodríguez-Hernández
authors.affiliation: Instituto Politécnico Nacional, CICATA Unidad Querétaro, Cerro Blanco 141, Colinas del Cimatario, 76090 Querétaro, Qro, Mexico.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Morales-Sánchez
authors.affiliation: Centro de Investigaciones Químicas, Instituto de Ciencias Básicas e Ingeniería, Universidad Autónoma del Estado de Hidalgo, Centro Universitario, Carretera Pachuca-Tulancingo Km. 4.5, 42183 Mineral de la Reforma, Hidalgo, Mexico.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Gómez-Aldapa
authors.affiliation: Instituto Politécnico Nacional, CICATA Unidad Querétaro, Cerro Blanco 141, Colinas del Cimatario, 76090 Querétaro, Qro, Mexico. Electronic address: gvelazquezd@ipn.mx.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Velazquez
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D055119:Elastic Modulus; D057927:Hydrophobic and Hydrophilic Interactions; D010539:Permeability; D011108:Polymers / Q000737:chemistry; D013718:Tensile Strength; D044366:Transition Temperature; D014867:Water / Q000032:analysis*
chemical_list: D011108:Polymers; D014867:Water; D048271:Chitosan
keywords: Adsorption isotherm; Biodegradable film; Chitosan; Plasticization; Water vapour permeability