ORIGINAL ARTICLE Physicochemical Properties of Biodegradable Polyvinyl Alcohol–Agar Films from the Red Algae Hydropuntia cornea Tomás J. Madera-Santana & Daniel Robledo & Yolanda Freile-Pelegrín Received: 7 April 2010 / Accepted: 5 December 2010 # Springer Science+Business Media, LLC 2010 Abstract Agar obtained from the red alga Hydropuntia cornea was blended with polyvinyl alcohol (PVOH) in order to produce biodegradable films. In this study, we compare the properties of biopolymeric films formulated with agars extracted from H. cornea collected at different seasons (rainy and dry) in the Gulf of Mexico coast and PVOH as synthetic matrix. The films were prepared at different agar contents (0%, 25%, 50%, 75%, and 100%) and their optical, mechanical, thermal, and morphological properties analyzed. The tensile strength of PVOH–agar films increased when agar content was augmented. The formulation with 50% agar from rainy season (RS) had a significant higher tensile strength when compared to those from dry season (DS; p <0.05). Tensile modulus also displayed an increasing trend and likewise, for 50% and 75% agar blends from RS showed higher values than those from DS (p <0.05). In contrast, elongation at break decreased as the agar content increased, independently of the season. Environmental scanning electron microscopy images of PVOH–agar 75% biofilms from RS showed a homogeneous structure with good interfacial adhesion between the two components. The changes evidenced in the FTIR spectrum of this blend suggest that hydrogen bonding is taking place between the agar ether linkages (C-O-C) and the hydroxyl groups (OH) of the PVOH. Based on the above mentioned results, blends of PVOH and 75% agar from H. cornea collected in rainy season showed good properties for applications in the biodegrad- able packaging industry. Keywords Agar . Gracilaria cornea . Marine biopolymers . Polyvinyl alcohol . Biodegradable polymers . Mechanical properties Introduction Many petrol-based synthetic plastics such as polyethylene, polypropylene, or polystyrene are widely used in different day life applications (food industry, packaging, biomedical, agriculture, etc.). However, their utilization is accompanied by heavy environmental pollution when these articles or products reach their end use. Nowadays, the use of natural polymers from terrestrial or marine origin is an alternative to this problem. Natural film-forming materials are based on proteins, polysaccharides, lipids, and resins that meet a number of specific functional requirements (moisture barrier, solute and/or gas barrier, water or lipid solubility, appearance, good mechanical and rheological character- istics, and nontoxicity) more effectively than conventional synthetic materials (Tharanathan 2003). Particularly, poly- saccharides have a variety of structures and display a wide range of properties (Debeaufort et al. 2005). Among the most used polysaccharides, starch has been utilized because of its abundance, high production rate and low cost. However, when starch is used in combination with synthetic polymers, a reduction in mechanical properties T. J. Madera-Santana : D. Robledo : Y. Freile-Pelegrín (*) Department of Marine Resources, Cinvestav, Km 6 Carretera Antigua a Progreso, Cordemex, 97310, A.P. 73, Mérida, Yuc, Mexico e-mail: freile@mda.cinvestav.mx Present Address: T. J. Madera-Santana Centro de Alimentación y Desarrollo, A.C. CTAOV. Carr. a la Victoria Km. 0.6 A.P. 1735, Hermosillo, Son 83000, Mexico Mar Biotechnol DOI 10.1007/s10126-010-9341-8