Physicochemical, Water Vapor Barrier and Mechanical Properties of Corn Starch and Chitosan Composite Films

Abstract

Biodegradable flexible films were developed from corn starch (CS) and chitosan (CH); their microstructure, mechanical and barrier properties were evaluated. Chitosan and starch blend filmogenic suspensions showed a pseudoplastic behavior, similar to that of chitosan solutions. Smooth surfaces, homogeneous and compact film structures were observed from microstructure studies using scanning electron microscopy (SEM). The addition of glycerol reduced film opacity and increased film solubility of both CS and composite CS-CH films. Water vapor permeability values of composite CS-CH films plasticized with glycerol ranged between 3.76 and 4.54× 10−11 g s−1 m−1 Pa−1, lower than those of the single component films. CS-CH films were resistant and their flexibility increased with glycerol addition. Tensile strength values of CS-CH films were comparable to those of low-density and high-density polyethylenes but lower than that obtained for cellophane, however, composite biodegradable films showed lower elongation at break values than the synthetic commercial ones. In conclusion, CS-CH films can be described as biofilms with a homogeneous matrix, stable structure and interesting water barrier and mechanical properties, with great possibilities of utilization, and with the advantage of biodegradability.