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Bacterial Cellulose (BC)
Composites
Cellulose from Acetobacter xylinum ( reclassified
as Gluconacetobacter xylinus ) is a thick gel of microfibrils
of joined macromolecules in an ultra fine reticulated structure. Due to
its high degree of crystallinity ( above 60% ) with cross section diameters
of few nanometres and length of hundreds micrometres, it can be used as
reinforcement material of bionanocomposites.
Materials
A strain of Acetobacter Xylinum is inoculated
into a culture medium which allows bacteria to feed and grow so
the BC film can be produced.
The process takes about three weeks until a thick
gel layer is formed. This gel can then be processed to produce a
bionanocomposite.
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Acetobacter xylinum
culture
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Processing
Techniques
In POLyCOM, BC gels have been
processed pure and blended with other materials. Sheets have been
made by compression moulding and foams by a freeze-drying technique.
Characterisation
- Thermal analysis: Differential Scanning Calorimetry
(DSC) and Thermogravimetry Analysis (TGA).
- Mechanical properties: Tensile test and Dynamic
Mechanical Analysis (DMA).
- Morphology: Scanning Electron Microscopy (SEM).
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SEM micrograph of a freezed-dried BC gel
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- Project Supervisor: F. G. Torres
- Researcher: C.
Grande
Conclusions
- Pure BC sheet has a high tensile modulus due to long
interpenetrating fibres with strong hydrogen bonding between them.
- The effectiveness of BC as a reinforcement material
habeen well established since the tensile moduli of bionanocomposites
sheets is higher as the concentration of BC increase.
Collaboration
- Queen Mary University. London (UK). Prof. T. Peijs
- Universidad Peruana Cayetano Heredia. Prof. Dora Maurtua
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