A preliminary study on the development and characterisation of enzymatically grafted P(3HB)-ethyl cellulose based novel composites

In the present study, a novel enzyme-based grafting of poly(3-hydroxybutyrate) [P(3HB)] onto the ethyl cellulose (EC) as a backbone polymer was developed under a mild and ecofriendly environment and laccase was used as a grafting tool. The resulting composites were characterised using various instrumental and imaging techniques. The high intensity of the 3,358 cm−1 band in the FTIR spectra showed an increase of hydrogen–bonding interactions between P(3HB) and EC at that distinct wavelength region. The morphology was examined by scanning electron microscopy, which showed the well dispersed P(3HB) in the backbone polymer of EC. X-ray diffraction pattern for P(3HB) showed distinct peaks at 2-theta values of 28°, 32°, 34°, 39°, 46°, 57°, 64°, 78° and 84°. In comparison with those of neat P(3HB), the degree of crystallinity for P(3HB)-g-EC decreased. The tensile strength, elongations at break and Young’s modulus of P(3HB)-g-EC reached the highest levels in comparison to the film prepared with pure P(3HB) only, which was too brittle to measure any of the above said characteristics. Results obtained in the present study suggest P(3HB)-g-EC as a potential candidate for various biotechnological applications, such as tissue engineering and packaging

Mechanical and structural properties of native and alkali-treated bacterial cellulose produced by Gluconacetobacter xylinus strain ATCC53524

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