Effects of injection parameters and compositions on the structures and mechanical properties of hydroxyapatite/polyamide 66 porous scaffolds

Hydroxyapatite/polyamide-66 (HA/PA66) composite porous scaffolds were prepared using injection-molding technique and analyzed by means of SEM, XRD, DSC and mechanical testing. The results demonstrate that the mechanical properties, porosity and pore size of HA/PA66 composite scaffolds can be effectively controlled by changing the molding parameters (foaming agent and shot size). HA particles increase the stiffness of HA/PA66 composite scaffolds accompanied by the reduction of pore size and porosity. The addition of ethylene-vinyl acetate copolymer (EVA) in HA/PA66 (30/70, mass ratio) scaffolds conduces to the pore growth, the formation of uniform porous structure, the improvement of the scaffolds'mechanical properties and melt processability of the composites. The injection-molding method can rapidly and conveniently fabricate the composite scaffolds. The obtained scaffolds with a pore size ranging from 200 μm to 600 μm and a porosity more than 64% can simultaneously meet the requirements of porous structure and mechanical performance. The compressive properties of the scaffolds are similar to or higher than those of trabecular bone and close to those of the cancellous bone.