3.2.3. Tensile properties
Tensile strength (TS) and elongation at break (%E) are the most commonly reported responses to describe mechanical properties of paper-based packaging materials. Adequate mechanical strength and flexibility are required to maintain packaging integrity during
shipping, handling, and storage. In general, the mechanical properties of the coated/laminated films in composite structure are controlled by the substrate or base film (Hong, Lee, & Son, 2005). However, tensile properties of coated papers were shown to be mainly dependent on the coating weight (Fig 3 and 4). The TS of coated papers increased with increasing coating weight from 5 to 16 g/m2. However, neither the addition of chitosan nor the coating application methods (single layer and bilayer) affected significantly (p > 0.05) the TS of coated paper (Fig 3). Conversely, Pereda et al.
(2008), who worked with chitosan/caseinate composite films, had reported that the addition of chitosan produced stronger films as compared with caseinate film. The complexation established between the two macromolecules is proposed as the reason for this improvement. A similar behavior was observed by Hosseini et al. (2013), who studied composite films made from gelatin and chitosan