Thermal properties of water-resistant starch – polyvinyl alcohol films modified with cellulose nanofibers

What is it about?

Starch based materials look promising substitutes for common plastic materials in many applications provided that water resistance and thermal stability are much improved. One attempt to overcome this challenge was shown in this paper. Starch/polyvinyl alcohol films (S/PVA) modified with different amount of cellulose nanofibers (CN) were prepared using one-pot procedure and their thermal behavior and water resistance were studied in relation to morphological aspects and mechanical behavior. Strong improvement of thermal stability, with about 100 ºC, was observed in nanocomposites compared to S/PVA. Different mechanisms by which CN may influence the thermal stability were also analyzed. It was shown that CN promoted better interfacial adhesion between components in S/PVA and prevented the elimination of water and glycerol up to 200 °C. All the nanocomposites showed minor weight loss up to 200 °C. These results indicate that S/PVA/CN nanocomposites are suitable substitutes for common plastic materials in packaging industry and agriculture.

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Why is it important?

This paper is a contribution to the effort to develop new biodegradable materials for replacing petroleum-derived polymers with renewable ones and to reduce the negative environmental impact of plastic wastes. Starch has a high potential especially for packaging. Despite its low price and high availability, important drawbacks related to poor mechanical and thermal properties, brittleness and high moisture sensitivity have to be overcome to increase starch attractiveness for large-scale application. Water resistant, cross-linked starch/PVA films modified with different amount of cellulose nanofibers (CN) were prepared and their thermal behavior was studied in relation to morphological aspects and dynamic-mechanical behavior. One-pot process was used for the preparation of these starch/PVA films with CN for better reproducibility and easy scale up.