Study on the Mechanical Properties of Three-Dimensional Directly Binding Hydroxyapatite Powder

In the three-dimensional directly fabricating hydroxyapatite composite artificial bone scaffold process, the liquid bio-binder is sprayed on the surface of bioceramics powder layer. The spraying volume and the powder size directly influence the mechanical properties of the bone scaffold and the future biodegradation performance. When the size of powder is stable, the amount of binder spraying will directly affect the mechanical strength of bone scaffold. In order to figure out the solidification mechanism of α-n-butyl cyanoacrylate (NBCA) bio-binder on the hydroxyapatite (HA) powder layer, the molecular dynamics simulation method is applied to investigate the binding energy shifts between NBCA on HA crystallographic planes. The mechanical properties can be deduced from this methodology; furthermore, the Knoop identification experiments are used to investigate the effective elastic modules of pure HA system and HA/NBCA composite model. Both the simulation and the experiments results elucidate that HA (110) has the highest binding energy with NBCA as the high planar atom density and the mechanical properties of HA/NBCA mixed system are stronger than the pure HA system on three-dimensional crystallographic; in this sense, the bone scaffolds with different strengths could be fabricated by controlling various NBCA binders liquid doses on the surface of HA powder layers during the 3D printing process.