Biodegradability, Compostability and Safety of Cellulose Nanofibrils (CNF) and CNF Based Products

Cellulose nanomaterials have unique properties that make them potential for numerous applications. One of their most promising applications is transparent cellulose films with excellent strength, density and smoothness. Cellulose films could be utilized as gas barriers in packaging, substrates for printed electronics, in diagnostics or even as electronic displays instead of oil-based plastic films. From the safety point of view, the advantages of cellulose nanomaterials have been argued to be their benign nature towards humans and the environment as well as their biodegradability. However, when used in products, the biodegradability of cellulose nanomaterials might differ from that of pure materials. For example, during film preparation, the hydroxyl groups in the surface of cellulose nanofibrils form strong hydrogen bonds, which upon drying of the film could make it more resistant towards degradation. Results on the biodegradability of different grades of cellulose nanofibrils (CNF) and their products, namely CNF films and papers coated with CNF are presented in this paper. In addition, results on the toxicity of cellulose nanofibrils to humans as well as ecotoxicity during biodegradation in the composting environment are reported. The results of biodegradability tests (OECD 301B) of two different grades of CNF indicate that their biodegradability is dependent on the fibrillation degree, the finer grade degrading faster than the coarser grade. The biodegradability test (EN 14046) of CNF films and papers containing CNF showed that all the CNF products tested were biodegradable according to the requirements set in the standard (EN 13432). In the composting test (EN 14045) disintegration of CNF products was observed in the composting environment with no acute ecotoxicity during biodegradation. Regarding toxicity to humans, some indication of cytotoxicity was observed for nano-scale cellulose fibrils. However, all the other toxicity tests results, including in vivo tests with Nematode, showed no sign of toxicity.