Bioactivity and mechanical properties of cellulose/carbonate hydroxyapatite composites prepared in situ through mechanochemical reaction.

Organic-inorganic composites, prepared from bone-bonding bioactive ceramics and organic polymers, are useful for novel bone substitutes having mechanical properties analogous to natural bone. We synthesized composites from cellulose and carbonate hydroxyapatite (CHAp) in situ through mechanochemical reaction. They contained B-type CHAp analogous to bone apatite. They showed a bending strengths of 10-13 MPa and Young's modulus of 1.5-2.2 GPa. We predicted their microstructure by comparing the measured density with the theoretical one. Cellulose was assumed to be distributed in the pore of CHAp at low cellulose content, and in grain boundaries of CHAp at high cellulose content. The composites formed calcium phosphate on their surfaces in simulated body fluid, meaning that they have a potential to be bioactive.