The development and characterization of a novel chitosan/carbonised yucca (Yucca flaccida) bio-composite

The aim of the study was to fabricate a biodegradable bio-composite using only natural biological precursors for both composite components, i.e., for a support and for a filler. Bio-composites of biomorphous structure were prepared using monolithic blocks of yucca (Yucca flaccida) carbonised at 550 °C as a stiff porous skeleton, and chitosan as a filler that coated the internal surface of the skeleton by a thin film. Highly porous supports and the resultant biomorphous composites were characterized by means of TGA, SEM, low-temperature physical adsorption of nitrogen, as well as electric and ultrasonic measurements. The resultant bio-composites were found to be very light materials with density of about 0.13 g/cm³ and very porous (over 90%). They were found to be hierarchically ordered anisotropic structures with a stiff skeleton of dynamic elastic moduli up to 0.8 GPa. The specific surface area was found to be 72 m²/g giving a surface area of chitosan film equal to about 12 m² for a block sample of a volume of 2 cm³. Covering porous support by thin film of chitosan resulted in the increase of electrical conductivity of the resultant composite.