Understanding the Biological Degradation of Home Compostable Multilayer Packaging

09 Jun 2022

A systematic approach using rounds of respirometry and disintegration testing was used to design for industrially compostable and home compostable multilayer packaging (MLP). The study incorporated two rounds of thermophilic composting (58°C) examining various film chemistries, thicknesses, adhesives, inks, and metallization variables. Respirometry and disintegration photography data from thermophilic composting revealed 12 monolayer films and MLP structures with greater than 90% carbon mineralization within 90 days, half the time allotted for certification under ASTM D6400 and D5338. These data also provided insights for MLP structure design for materials tested under mesophilic (35°C) and psychrotrophic (20°C) home composting conditions, demonstrating one structure achieving >97% carbon mineralization in 6 months of composting at 20°C. Thermal properties of the MLP structures have been studied using TGA and DSC, and water vapor transmission rates have been determined for both industrially and home compostable monomaterial films and MLP with many examples yielding <1 g/m2·24h. At 20°C home composting conditions, the laminations of regenerated cellulose with either poly(hydroxy alkanoates) or poly(butylene succinate-co-adipate) yielded faster carbon mineralization and disintegration than either regenerated cellulose or the polyester monomaterial films alone, illustrating an acceleration in degradation outcomes with complex MLP structures when compared to monomaterials.

Evan White, Research Scientist, New Materials Institute - University of Georgia