Soil Biodegradation of a Blend of Cassava Starch and Polylactic Acid

This study evaluated bio-based blended films produced from polylactic acid (PLA) and thermoplastic starch (TPS) under soil conditions for four weeks (W). The degradation of the film was evaluated in addition to thermal, structural, and morphological changes on the surface of the material. There were evident structural changes; the TPS present in the film degraded from weeks 0 to 4, exhibiting a loss of mass between 350 and 365 °C in the TGA test. This behavior was attributed to the condensation of hydroxyl groups of the cassava starch as well as to a loss of mass corresponding to the degradation of PLA between 340 and 350 °C. The addition of TPS in the PLA-containing matrix resulted in a decrease in the Tg of the PLA/TPS blends. The increase in crystallinity improved the water vapor permeability in the structure. Consequently, the incorporation of starch in these blends not only reduces the cost of the material, but it also contributes to its rapid biodegradation (68%). These results contribute and offer new alternatives to accelerate the biodegradation process of biomaterials.