(134a) Melt Spun Nanocomposite Fibres of Polylactide/Bacterial Cellulose Nanofibrils; Towards Composites with Anisotropic Properties and Nanophase Alignment

Conventionally, low-cost racemic polylactide (PDLLA) has been regarded as an inferior product over its semi-crystalline PLA counterpart, however it does has the advantage of being processed at temperatures sub 150°C, which is below the degradation point of many bio-based fillers, making it attractive as a matrix in composites. In an effort to enhance the properties of PDLLA we incorporate bacterial cellulose derived nano-fibrils, which have an elastic modulus reported at 114 GPa, via a twin-screw micro extruder and melt spin nanocomposite fibres. The hot extruded material is spun into fibres using a DSM Xplore (The Netherlands) fibre-spinning rig. These fibres are compared to those we produce based on a semi-crystalline PLLA matrix, produced at elevated temperatures (185°C). We also modify bacterial cellulose nano-fibrils via organic acid esterification (hexanoic and lauric acid) in an effort to improve the interface between the nano-phase and the matrix and investigate the effect of matrix and fibril modification on fibre properties. Neat PDLLA, PLLA and composite fibres filled with up to 5 wt.% bacterial cellulose nano-fibrils have been produced and characterized in terms their mechanical, and thermal properties, and the distribution of nano-fibrils within the fibre matrix assessed. By combining semi-crystalline PLA/bacterial cellulose nanocomposite fibres with amorphous PLA (processed at lower temperatures) nano-composites with anisotropic mechanical properties can be realized.