Preparation, Characterization, and Biodegradability Assessment of Maize Starch-(PVOH)/Clay Nanocomposite Films Katerina Katerinopoulou, Aris Giannakas,* Nektaria-Marianthi Barkoula, and Athanasios Ladavos This study is focused on the preparation, characterization, and biodegradabil- ity assessment of clay nanocomposite films based on plasticized maize starch, prepared via solution casting method. Intercalated nano-structure is achieved in all obtained films. Mechanical properties of the films prove to be dependent on the content of plasticizer (Glycerol) and poly-vinyl-alcohol (PVOH). Nanocomposite film with 10 wt% Glycerol and 20 wt% PVOH content possesses high stiffness and strength, but it is very brittle while nanocomposite film with 20 wt% Glycerol and 10 wt% PVOH content possesses reduced stiffness and strength but enhanced elongation at break, and film forming capability. Thermal stability of plasticized maize starch increases by 50  C after addition of both PVOH and montmorillonite while water vapor transmission rate (WVTR) is reduced by 74% in comparison to the plasticized maize starch film. The biodegradation process increases in films with high starch content, while it is slow down when PVOH is added. 1. Introduction Biodegradable polymer hybrid nanocomposite films are prom- ising alternative to classic plastics for food packaging applica- tions. [1–5] Nanosized fillers aim at improving mechanical performance and, most important, enhancing barrier properties of biodegradable polymer films against oxygen diffusion, carbon dioxide, flavor compounds, and water vapor, which are quite critical in food packaging. Due to their platelet like structure, layered silicate nanoclays such as montmorillonite (MMT) and kaolinite are the most discussed nanosized fillers for the improvement of barrier properties and potential enhancement of the mechanical performance of polymer films. [1,2] The most studied matrices for such applications are based on starch and cellulose derivatives, [3,4] polylactic acid (PLA), [6,7] polycaprolactone (PCL), [8,9] and poly-(butylene succinate) (PBS). [10,11] Starch is of great interest because it is abundant, cheap, renewable, and biode- gradable, but it lacks in strength, water resistance, processability, and thermal stability. To overcome some of these draw- backs, starch can be plasticized with water and/or polyols such as glycerol, [12,13] sorbi- tol and polyethylene glycol and blended with other biodegradable synthetic poly- mers such as poly(lactic acid) (PLA), [6] poly(caprolactone) (PCL), [14] polyvinyl alco- hol (PVOH) [15] and/or modified with nano- sized fillers. [16–21] As a water-processable or melt-process- able polymer PVOH has a high technologi- cal potential however it is relatively expensive and has low biodegradation rate and poor moisture barrier properties. To reduce cost and enhance its eco-friendliness and performance, PVOH is often blended with other polymers (such as starch) or is reinforced with nanoparticles. [22–28] A small number of studies on nano-reinforced of starch-PVOH blends have been pub- lished. [29–34] Most of these reports [29–31,33] were focused on the investigation of component interactions and their effects on thermal and mechanical properties of studied starch-PVOH- MMT nanocomposites. Only one of them [32] was focused on enzymatic biodegradation of obtained starch-PVOH-MMT nanocomposites. Moreover, barrier properties which are crucial for packaging films were not investigated in any of these reports. [29–33] In our previous publication [34] two PVOH polymers with various molecular weight were used successfully for the development of acetylated starch (ACS) – clay nano- composite films. Both PVOH polymers were added in a high: 30 wt% and low: 10 wt% content. Low PVOH content addition was combined with 20 wt% glycerol (G) addition to ACS-clay nanocomposites. Water barrier was improved with the addition of low molecular weight PVOH. Addition of 30 wt% PVOH led to huge enhancement of mechanical strength but significantly decreased elongation at break which is important for film packaging forming capability. The simultaneous addition of G and PVOH, 20 wt% and 10 wt% respectively, resulted in a pronounced deterioration of the mechanical performance of the ACS/G/PVOH/MMT systems. Dr. K. Katerinopoulou, Dr. A. Giannakas, Prof. A. Ladavos Laboratory of Food Technology Department of Business Administration of Food and Agricultural Enterprises University of Patras Agrinio 30100, Greece E-mail: agiannakas@upatras.gr Prof. N.-M. Barkoula Department of Materials Science and Engineering University of Ioannina Ioannina 45110, Greece DOI: 10.1002/star.201800076 Nanocomposite Films www.starch-journal.com RESEARCH ARTICLE Starch - Stärke 2018, 1800076 © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1800076 (1 of 8)