Blend or mixing films

Blending of natural and S5mthetic polymers is a simple and practical way to produce new materials. The films formed by blending of two or more pol5miers usually result in modified physical and mechanical properties compared to films made with the individual 

Preparation of films can be achieved by two main processes the wet and dr) approaches. The wet process involves biopol5mier dispersion or solubilization in a film-forming solution (solutioncasting) followed by a second step, the suspension or film-forming solution is placed in a suitable mold and the solvent is evaporated under controlled conditions (Ciannamea et al., 2014 Hernandez-Izquierdo and Krochta, 2008). The result of the casting process depends mainly on the mixing conditions temperature, time, type and concentration of solvent, plasticizer and pH, and the dr nng relative humidity and temperature (Gallstedt et al., 2004). Most of the studies on polysaccharide-based films use this method because it is simple, reproducible in most laboratories, and useful as a first approximation to the formation of edible films. 

The dry process relies on the thermoplastic behavior that some proteins and polysaccharides display at low moisture levels in compression molding and extrusion (Hemandez-lzquierdo and Krochta, 2008). 

Therefore, extrusion technology has become an attractive option to produce biodegradable films due to its high productivity and minimal space requirements, especially when compared to the casting method, offering several advantages over solution-casting (Hernandez-lzquierdo and Krochta, 2008 Sothornvit et al., 2007). 

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