Nano-HA Preparation and its Effects on Mechanical Properties of nHA/PLLA/PES Composite Biomaterials

Nanocrystals hydroxyapatite (nHA) was synthesized and modified chemically, and nanocrystals hydroxyapatite / poly(L-lactide)/poly(ethylene succinate)(nHA/PLLA/PES) composite was prepared by melt-blending using nHA, PLLA and PES as reactants in a stainless steel chamber. The obtained nHA was of high purity and high crystallinity as well, its mean sizes measured from TEM observations were 65±35nm (long axis) and 40±10nm (short axis), and are close to the endosteal needle hydroxyapatite crystals size ((15 ~ 20) nm×60 nm) in the human body. The mechanical properties of nHA/ PLLA/PES blends were determined by bending and tensile tests and the effects of nHA content on the mechanical properties of nHA/PLLA/PES blends were investigated. The blending modulus and tensile modulus increase with the nHA (0,5,10,15and 20 wt.%) content increase, while blending strength increases up to HA mass fraction of 10% and after that decreases. SEM images revealed that the surface changed from rough to smooth with increasing nHA content, especially with nHA content higher than 20%, which implied the failure mechanism of the material changes from ductile to brittle.