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

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. Both optical transmittance and AFM nano-level investigation revealed a homogeneous dispersion of CN regardless of their concentration. Tremendous improvement of thermal stability, with about 100 °C, was observed in nanocomposites compared to S/PVA. Different mechanisms by which CN may influence the thermal stability were also analyzed. TGA results correlated with PF QNM mapping have shown that CN promoted better interfacial adhesion between components in S/PVA and prevented the elimination of water and glycerol up to 200 °C. S/PVA/CN nanocomposites with more than 4 wt% CN were not damaged by hot water for more than five hours and 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.