Microbially synthesized nanocellulose, more commonly known as bacterial cellulose (BC) is a type of high-performance bio-based cellulose nanofibres with tensile moduli and strengths estimated to be 100-160 GPa and 1-6 GPa, respectively. It is also a lightweight material (~1.5 g cm-3) with low toxicity. In contrast, glass fibres possess a tensile modulus and strength of only 72 GPa and 3 GPa, respectively, with a density of 2.5 g cm-3. Therefore, BC often regarded as the prime candidate to produce high-performance materials for various advanced composite applications. Various researchers have demonstrated the ability of BC  to act as nano-reinforcement in various advanced composite settings for load-bearing applications over the last 15 years. Despite this, BC has not yet been commercialised as reinforcement for polymers. This is because the break-even price of the production of BC US$25/kg (wet, 99% water). BC is therefore an expensive reinforcement, especially when high loading fraction (&gt;30 vol.-%) is required to achieve significant tensile and flexural performance improvements.<br/> <br/>Here in this work, we describe a simple concept based on the sizing BC nanofibrils with low molecular weight poly(ethylene glycol) (PEG) to prevent interfibril hornification, thereby preserving the original toughness of the pellicle. The PEG sizing increased the tensile strain-at-failure and toughness of BC sheet by ~400% and ~900%, respectively. Fractographic analysis of the single edge notched tension fracture surface confirmed that the ductility of PEG-sized BC sheets stems from BC nanofibril slippage and/or reorientation during deformation. We further show in this presentation that PEG-sized BC can be used as two-dimensional reinforcement in a laminated composite construct to enhance the impact properties of polymeric materials even at low loading fraction (0.2 wt.-%). This is particularly practical as it keeps the overall cost of the BC composites low since the cost of BC is often cited as the bottleneck for using BC in various advanced composite applications.

Tough poly(ethylene glycol)-sized bacterial cellulose sheet for high impact strength laminated acrylic composites

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.