Degradation of supposedly biodegradable polymers in a real estuarine environment

Aiming to mitigate the impacts of global plastic pollution, several strategies have been adopted, such as replacing conventional plastics with compostable and biodegradable polymers. However, the effectiveness of these polymers in real-world environments has been questioned due to low degradation rates. Therefore, the present study experimentally assessed, in a real estuarine environment, degradation of bags made of PLA + PBAT + starch, PLA + PBAT, polyethylene (PE) with an oxo-biodegradable additive and solely PE. During an 180-day exposure period, morphological, chemical and structural analyses including SEM, FTIR, TGA and DSC were carried out. The results showed that bags made of PLA + PBAT + starch presented more consistent degradation evidence, in estuarine environments, than those without starch addition (PLA + PBAT). However, after 45 days of exposure, such blends have undergone fragmentation, probably forming microplastics (MPs). While samples composed by PLA + PBAT + starch significative differed in macroscopic and microscopic structure, condition indexes and thermal properties from ordinary PE, no significative differences were seen for samples made of PLA + PBAT and oxo-biodegradable plastics. Despite degradation performance of bags PLA + PBAT + starch based, assessments with regard microplastic formation and ecotoxicity must be performed in aquatic scenarios.