Properties of hydric and biodegradability of cassava starch-based bioplastics reinforced with thermally modified kaolin

In this study, hydric and biodegradability properties of cassava starch-based bioplastics reinforced with crude kaolin or treated kaolinitic clay at 700 degrees C called metakaolin were investigated using water adsorption and microbiological tests. Non-reinforced bioplastics (BP) and those containing 5 wt.% crude kaolin (BPKB) or metakaolin (BPMKB) were manufactured using the casting/evaporation method. Results obtained showed a decrease in the solubility and in the water diffusion and permeability of clay-reinforced bioplastics with respect to the ones without reinforcement. This improvement of the hydric properties has been attributed to the reduction in the free volumes existing between the starch macromolecules due to their interactions with clay platelets. These interactions might favor a more homogeneous and compact microstructure. The biodegradability of the clay reinforced bioplastics was significantly improved due to the bacterial proliferation. The thermal treatment of kaolinitic clay further improved the hydric and biodegradability properties of starch-based bioplastics.

Automated summary

The study found that the addition of clay reinforcement can improve the hydric properties and biodegradability of cassava starch-based bioplastics, mainly due to the reduction in the free volumes between starch macromolecules, leading to a more homogeneous and compact microstructure.