Biodegradability of commercially available cellulose-PLA based compostable food trays – Influence of usage and UV aging

Abstract

International audienceThis study aimed to assess the biodegradability and behavior of cellulose trays coated with PLA-based liners, marketed as compostable alternatives to non-biodegradable polyolefin trays. Three commercial trays were analyzed by NMR, FTIR and SEC, revealing that their liners contained two to four polymers. Furthermore, the time and temperature conditions to which the material is exposed prior to consumption may influence certain properties of these innovative cellulose-based trays, ultimately affecting their biodegradability. A usage protocol simulating real-life conditions was developed. Post-usage analysis revealed structural failures in the trays, while the relative polymer composition of the liners remained almost unchanged. In addition, the question of whether solar irradiation during time spent in the sun on the surface of various ecosystems, in the case of unintentional release, could also affect biodegradability was examined. Simulated environmental exposure by UV irradiation led to changes in the composition of some liners. Both aging processes appear to have a non significant effect on biodegradation. Interestingly, biodegradation studies indicated varying degradation level among the trays, despite their similar cellulose content. Trays biodegradation percentages ranged from 70 to just 40 % after 60 days. The biodegradation of the liners themselves was lower, ranging from 30 % to 0 %. 1H NMR analysis revealed that the biodegradation level can be correlated with the presence of specific polymers. These findings highlight concerns about the environmental impact of combined materials when one fraction, here the liner, that fails to biodegrade, even if the trays themselves pass biodegradation tests. The study underlines the importance of assessing the biodegradation of the final packaging as a whole, rather than evaluating only the raw materials