Physicochemical characterization and biodegradation test of oxo-degradable linear low-density polyethylene films subjected to gamma irradiation and accelerated weathering

Abstract

LLDPE is widely used as a packaging material for different purposes, mainly in food packaging. However, the accumulation of this material in the environment contributes to plastic pollution, generates environmental problems, and has harmful effects on biodiversity. In this study, 12 types of LLDPE films were formulated with a pro-oxidant additive (PA) (0 and 1% w/w) and thermoplastic starch (TPS) (0, 10, 20, 30, 40, and 50% w/w) by blown-film extrusion process. Formulation F12 showed similar color parameters and mechanical properties to the control film (F1); it was the selected formulation (SF) to be subjected to gamma irradiation (30 kGy) and accelerated weathering (25, 50, and 100 h). The tensile strength and elongation at break decreased after gamma irradiation and 25 h of accelerated weathering. In contrast, the modulus of the irradiated SF showed a higher increase than non-irradiated after 50 and 100 h of accelerated weathering. The structural analysis indicated scission and formation of carbonyl groups in the main LLDPE chain. The results of DSC demonstrated a progressive increase in the crystallinity of the SF (higher in irradiated samples), reaching around 99% in sample SF30kGy100 h. The biodegradation test revealed that the SF and SF25h samples reached 32.7% and 39.5%, respectively, after 180 days of incubation. However, the SF30kGy25 h sample showed a level of biodegradation of 16%. The biodegradability of SF increased with 25 h of accelerated weathering, while it decreased with the combined effect of treatments.