Mechanical and structural properties of native and alkali-treated bacterial cellulose produced by Gluconacetobacter xylinus strain ATCC 53524
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Mechanical properties of hydrated bacterial cellulose have been tested as a function of fermentation time and following the alkali treatment required for sterilisation prior to biomedical applications. Bacterial cellulose behaves as a viscoelastic material, with brittle failure reached at approximately 20% strain and 1.5 MPa stress under uniaxial tension. Treatment with 0.1 M NaOH resulted in minimal effects on the mechanical properties of bacterial cellulose. Fermentation time had a large effect on both bacterial numbers and cellulose yield but only minor effects on mechanical properties, showing that the fermentation system is a robust method for producing cellulose with predictable materials properties. The failure zone in uniaxial tension was shown to be associated with large-scale fibre alignment, consistent with this being the major determinant of mechanical properties. Under uniaxial tension, elastic moduli and failure stresses are an order of magnitude lower than those obtained under biaxial tension, consistent with the fibre alignment mechanism which is not available under biaxial tension.
KeywordsCellulose Gluconacetobacter xylinus Mechanical properties Scanning electron microscopy Tensile testing
This research was funded through the Australian Research Council’s Discovery scheme (DP0665467 and DP058067). The authors would like to thank Dr. Darren Martin for use of the Instron 5543 instrument. James Riesz, Dr. Grant Edwards and Dr. Polly Burey are thanked for their helpful discussions and Dr. Peter Kopittke for statistical analysis.
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