Preparation, Characterization and Degradation of PS/TPS Blends Using Glycerol and Buriti oil as Plastiscizers

Polystyrene (PS) is one of the most used disposable materials in our daily life, but it does not decompose easily. The addition of cassava starch to PS can improve its degradability since starch is a biodegradable polymer. The aim of this work was to develop blends of PS and thermoplastic starch (TPS) using two different plasticizers: buriti glycerol and buriti oil, a novel and natural plasticizer for starch. PS/TPS blends were prepared in various contents with the casting technique and analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and C-13 nuclear magnetic resonance (NMR). PS/TPS blends with buriti oil presented a continuous reduction in T-g and T-a. For blends with glycerol these parameters remained practically constant. PS/TPS blends were submitted to degradation by soil burial testing and then analyzed by TG and C-13 NMR. The analysis of PS/TPS blends with buriti oil indicated an increase in weight loss in the TG curves. All NMR peaks associated with starch disappeared after the soil burying test, probably due to the consumption of starch by microorganisms. The results showed that addition of TPS produced with buriti oil to PS can probably improve its degradability.