Performance of PBS materials with degradable additives for food packaging

Abstract

This study evaluates the physicochemical, mechanical, thermal and morphological properties of PolyButylene Succinate (PBS)-based bioplastics reinforced with degradable additives for food packaging applications. Water uptake tests revealed increased hydrolytic degradation at higher temperatures, particularly in ethanol-based simulants (from D = 0.0422∙108 cm2/s at 4 °C to 3.3491∙108 cm2/s at 40 °C). Migration tests confirmed compliance with EU regulations in acetic acid but some limitations to its suitability for alcoholic solutions, due to the overcome of overall migration limits (10 mg/dm2). Specific migration of metal species was below EU limits, especially Co (<0.005 mg/kg) and Cr (0.0004 mg/kg), but is worthy of attention for packaging surface design. Mechanical analysis showed changes in the properties of the specimens after treatment, such as a slight increase in brittleness after exposure to acetic acid, coupled with a small increase in Young's modulus from 1.46 GPa to 1.65 GP, and a significant reduction in strain at break of about 37 % in ethanol-treated specimens, as also evidenced by the surface degradation shown by SEM analysis. FTIR-ATR analysis after treatments in ethanol and acetic acid solutions evidenced only few changes in main polymer chain, due to some limited hydrolysis of the PBS chain. Apparently, additives are mainly affected by the soaking in solutions, namely in the case of ethanol 50 % treatment at low temperature. DSC confirmed additive interactions and structural modifications. The results suggest that PBS-based materials are viable for food products with a pH < 4.5 under refrigerated conditions but require formulation adjustments for broader applicability.