Abstract
Hydroxyapatite was crystallized in an alkaline dispersion of mechanically fibrillated cellulose to prepare their composites with hydroxyapatite contents of 26-86 wt %. The composite powder was uniaxially pressed at 120 °C and 300 MPa to obtain the compacts. Three-point bending tests revealed that the bending strengths of the compacts were 40-100 MPa, and the elastic moduli were 4-9 GPa. The composite containing 43% hydroxyapatite showed the largest bending strength and the largest work of fracture, and the composite containing 62% hydroxyapatite showed the largest elastic modulus. The composites, derived from the bioderived eco-friendly materials, showed the mechanical properties comparable to those of engineering plastics such as polyamide-6. Scanning electron microscopic observation of the fracture surface showed that the organic phase was discontinuous when the hydroxyapatite weight fraction was increased from 43% to 62%, and the compacts with a discontinuous organic phase lost toughness.