Elastomeric biodegradable starch/bentonite nanocomposites. Structure-thermo-mechanical correlation and degradation behavior

We developed layered silicate nanocomposite films based on corn starch (CS) and bentonite nanoclay, plasticized with glycerol. The films were elastomeric with stretchability of ca. 60–90 % and Tg = −75 to −85 °C. The nanocomposites were exfoliated if cbentonite 3 wt%. The exfoliated morphology induced thermal stability as shown by TGA. Interestingly, bentonite induced a reduction of Tg while increasing the Young's modulus E and reducing the extensibility. The fracture energy was a decreasing function of cbentonite except at 2.9 wt%, where the nanocomposite exhibited maximum Young's modulus and toughness, as demonstrated by the Ashby-style plot. The nanocomposite films were biodegradable in anaerobic and aerobic conditions, and in anaerobic conditions the intercalated nanocomposite of cbentonite = 2.9 wt% exhibited slower rate of degradation. These results provide insights into the development of bio-degradable elastomeric food packaging and coatings suitable for sub-ambient conditions. [Display omitted]