CONICET | Buscador de Institutos y Recursos Humanos

The non-biodegradability of most plastics has caused many environmental problems associated with their disposal, resulting in an increased interest in the production and use of biodegradable polymers. Starch is a natural biodegradable polymer existing in many vegetables as the main energy source. It is inexpensive, but it needs to be modified to be processed by conventional methods. The modification is carried out with the addition of a plasticizer in high temperature and shear conditions and the final product is called thermoplastic starch (TPS). TPS has been blended with PCL without much success due to poor interfacial compatibility, and the blends have shown an increased water absorption tendency due to the hydrophilic nature of starch. However, the addition of a compatibilizer, like maleic anhydride-grafted-polycaprolactone (PCL-gMA), enhances the compatibility, increasing mechanical properties and lowering the water permeability of the blends. Nevertheless, the improvement in those properties is not enough to be competitive with many traditional plastics. The addition of nanofillers to polymers has been showed to be an effective way of enhancing mechanical and barrier properties. Nanoclay has been widely studied as they are an easily-available and low-cost alternative compared to other nanofillers. In this study, Starch/nanoclay and PCL/nanoclay blends have been prepared, achieving better mechanical and barrier properties, but there are not many works that have combined the three of them. The matrix used was based on a blend of Anhydride-Functional Polycaprolactone (PCL-g-MA) and Thermoplastic Starch (TPS). The effect of the plasticizer content on the mechanical properties and water absorption of TPS and the effect of grafting maleic anhydride (MA) onto PCL at different PCL/MA proportions on the final morphology and mechanical properties were studied. Nanocomposites films based on the optimized PCL-g-MA/TPS blend reinforced with 5 wt.% of natural bentonite (Bent) and natural bentonite modified in our laboratory with tributyl hexadecyl phosphonium bromide (BentTBHP) were prepared by melt intercalation followed by compression molding. The study contemplates morphological (X-Ray Diffractometry, XRD) and thermal aspects (Differential Scanning Calorimetry, DSC, and Thermogravimetrical Analysis, TGA) and mechanical properties (tensile tests) which are important properties for packaging applications.