Rheological properties of thermoplastic starch/clay nanocomposites

MARÍA PAULA GUARÁS; LEANDRO LUDUEÑA; VERA ALVAREZ

Cancún

Conferencia; 33rd Annual Meeting of the Polymer Processing Society (PPS33); 2017

The use of conventional polymers in the past decades grew inordinately, and represents a wide field of oil consumption. These materials are not biodegradable, which causes a serious problem regarding the disposal of waste. Plastic packaging materials are also often contaminated by food products and biological substances, so many times; the recycling of these materials is impractical and economically not convenient. In the last decade, the use of biodegradable polymers had a growing interest. Thermoplastic starch (TPS) is one of the candidates for the manufacture of biodegradable polymer products for packaging applications. Native starch (NS) is the term used to refer to starch found in plants. Under these conditions NS is in the form of granules composed of amylose and amylopectin in different quantities depending on the source from which it comes. The main advantages of NS include its abundance, low cost, renewability and biodegradability. Compared to synthetic polymers, NS has two main disadvantages: A) contains hydroxyl groups which impart hydrophilic properties. So, NS disintegrates in water and loses its properties when exposed to moisture. B) The structure of NS must be modified, since starch degradation starts at a temperature lower than its melting point. Modification is done by the breakdown of the NS granule when it is processed in the presence of a specific amount of plasticizer, at a given extrusion conditions, obtaining TPS. TPS is a material that generally has low stability at high humidity conditions and fragile nature. The aim of this work was to prepare cost-effective, biodegradable nanocomposites based on chemically modified TPS reinforced with nanoclays prepared by reactive extrusion and to evaluate their rheological behavior using capillary rheometry. Rheological characterization in the processing shear rate range gives an initial screening about the adaptability of the TPS formulation to different polymer processing techniques