CONICET | Buscador de Institutos y Recursos Humanos

In the last decades the production of biodegradable polymers has attracted increasing attention owing to the environmental problems induced by the accumulation of plastic waste (Lepoittevin, B. et al. 2002). Several options appear to be attractive for replacing non-degradable plastics in many applications like the packaging industry. The main sources being explored are biomass and oil-derived biodegradable polymers. Among the first source, starch come into view as an attractive solution. It is one of the most economical biodegradable materials currently available in the global market. It is a very versatile biopolymer with great potential for applications in non-food industries. Starch can also be modeled by conventional processing techniques; however its high hydrophilicity and poor mechanical properties restrict its use for many applications. Within the second source, poly-caprolactone (PCL) appears as an attractive option. It is a biodegradable and biocompatible polyester that can be processed using conventional plastics machinery (Ludueña, L.N. et al. 2007) and its properties make it suitable for a number of potential applications from agricultural usage to biomedical devices. However, the relative high price and some inferior properties of the PCL have limited its large-scale production as a substitute of traditional polymers in packaging applications (Kim, E.G. et al. 2007). The incorporation of natural fibers as a reinforcing agent for both, starch and PCL is a good approach for improving their properties while still preserving the biodegradability. In the case of PCL, a significant price reduction is also achieved by the introduction of a low cost filling material. The main advantages of such fibers are their good mechanical performance, low cost, renewability and biodegradability (El-Tayeb, N.S.M. 2009). Plant fibers are mainly composed of cellulose, hemicellulose and lignin. Cellulose, which awards the mechanical properties of the complete natural fiber, is ordered in micro-fibrils enclosed by the other two main components: hemicellulose and lignin. Cellulose micro-fibrils can be found as intertwined micro-fibrils in the cell wall (2-20 um diameters depending on its source). They are conformed by nano-crystalline domains (width 5-30 nm, length of 20-60 nm) and amorphous regions. A controlled acid hydrolysis can separate both regions driving to crystalline domains with an elastic modulus of 150 GPa. In this contribution, two agricultural sources are used for cellulose extraction: sisal and cotton fibers. The main objective of this study is to understand the role of matrix type and fiber source in the final properties of biodegradable nanocomposites.

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