Deterioration of bioplastics in the soil environment: A thermoanalytical insight into the composition and degradation of commercial biodegradable polymers

Bioplastics are increasingly promoted as more sustainable alternatives to conventional plastics, yet their environmental fate and degradation pathways remain poorly understood. This study presents a comprehensive thermoanalytical investigation of commercial biodegradable plastic products aged in agricultural soil for 100 days. Polylactic acid (PLA) and starch-based bioplastics (SB) were characterized before and after soil exposure by Py-GC-MS, EGA-MS, TGA, and HS-SPME/GC-MS to assess polymer composition, thermal behavior, aging-related changes, and additive content. The analyses revealed that these materials have chemically complex formulations containing multiple polymeric components, volatile and semi-volatile degradation products, oligomeric species, and additives. Py-GC-MS and EGA-MS enabled the identification of key polymer markers and degradation signatures, whereas HS-SPME/GC-MS was particularly effective in detecting volatile compounds and formulation-related additives. The results demonstrate the chemical variability of commercial bioplastics, which may contain multiple polymeric components, copolymers, and additives capable of influencing their thermal properties and response to environmental aging. This work highlights the utility of combined thermoanalytical techniques, particularly Py-GC-MS, in providing a detailed understanding of the composition and environmental aging of bioplastics.