Harvesting fibrils from bacterial cellulose pellicles and subsequent formation of biodegradable poly-3-hydroxybutyrate nanocomposites

Bacterial cellulose has the potential to be used as a biodegradable, reinforcing component in composites due to its high strength and crystallinity. However it is often problematic to use in this context as it is difficult to separate its extensively bonded fibril network. This means it can be difficult for it to be incorporated as a fine dispersion into a composite and for the true benefits of the nanofibres to be realised in terms of physical property improvement in a conventional polymer format such as injection moulding. The method of sonication (using a range of experimental conditions) was utilised to harvest fibrils from the interwoven mesh of the cellulose pellicle, and then disperse them in different solvents to allow blending and subsequent casting. The novel step identified in this process was the sonication harvesting of the nanofibres undertaken on the highly hydrated as-received pellicle fresh from the reaction media (not the dried pellicle which could not be easily separated in the selected solvent). This unique step of harvesting directly from the fresh pellicle together with conventional sonication for dispersion in chloroform produced a bacterial cellulose/poly-3-hydroxybutyrate nanocomposite which showed excellent nanofibre dispersion and significant improvement in mechanical properties.