Morphology and mechanical properties of biodegradable nanocomposites based on polycaprolactone/thermoplastic-starch blend reinforced with natural and modified bentonite

MARÍA PAULA GUARÁS; SILVANA ECHEVERRÍA; LEANDRO LUDUEÑA; VERA ALVAREZ

Puerto Iguazú

Congreso; 13º Congreso Binacional de Metalurgia y Materiales (SAM-CONAMET 2013); 2013

This work was design as a possible response to growing pollution caused by plastics derived from petroleum with long degradation times. The use of polymers capable of being degraded by the action of microorganisms and/or enzymes which have no harmful effect is a strategy that has introduced a new concept in waste management. One of the cheapest environmental friendly and efficient options to improve the performance of these biodegradable polymers is to incorporate nanofillers, such us clays, to produce nanocomposites. These hybrid materials can exhibit high improvements on the mechanical, barrier and thermal properties, and some others such as the flammability, water adsorption and creep resistance with the incorporation of small amounts of filler (usually less than 10 wt.%). In this work, biodegradable polymer/clay nanocomposites were prepared and characterized. The matrix used was based on a blend of anhydride-functional polycaprolactone (PCL-g-MA) and thermoplastic starch (TPS). This system was optimized in a previous work. The effect of the plasticizer content on the mechanical properties and water absorption of TPS prepared by high shear melt mixing was analyzed. The effect of grafting maleic anhydride (MA) onto PCL at different PCL/MA proportions on the final morphology and mechanical properties of the PCL-g-MA/TPS blends prepared in a similar method was also studied. It was proved that grafting MA onto PCL improves the compatibility of the components in the PCL/TPS blends. Nanocomposites films based on the optimized PCL-g-MA/TPS blend reinforced with 5 wt.% of natural bentonite (Bent) and 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.