Montmorillonite nanoclay aggregated in a fractal structure in an acrylic‐styrene matrix, slowed the chain dynamics and increased an order of magnitude the tensile modulus

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 T_g = -75 to -85 °C. The nanocomposites were exfoliated if c_bentonite < 2 wt%, and intercalated if c_bentonite > 3 wt%. The exfoliated morphology induced thermal stability as shown by TGA. Interestingly, bentonite induced a reduction of T_g while increasing the Young's modulus E and reducing the extensibility. The fracture energy was a decreasing function of c_bentonite 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 c_bentonite = 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.