One-Pot Hybridization\nof Microfibrillated Cellulose\nand Hydroxyapatite as a Versatile Route to Eco-Friendly Mechanical\nMaterials

Hydroxyapatite was crystallized in an alkaline dispersion\nof mechanically\nfibrillated cellulose to prepare their composites with hydroxyapatite\ncontents of 26–86 wt %. The composite powder was uniaxially\npressed at 120 °C and 300 MPa to obtain the compacts. Three-point\nbending tests revealed that the bending strengths of the compacts\nwere 40–100 MPa, and the elastic moduli were 4–9 GPa.\nThe composite containing 43% hydroxyapatite showed the largest bending\nstrength and the largest work of fracture, and the composite containing\n62% hydroxyapatite showed the largest elastic modulus. The composites,\nderived from the bioderived eco-friendly materials, showed the mechanical\nproperties comparable to those of engineering plastics such as polyamide-6.\nScanning electron microscopic observation of the fracture surface\nshowed that the organic phase was discontinuous when the hydroxyapatite\nweight fraction was increased from 43% to 62%, and the compacts with\na discontinuous organic phase lost toughness.