Preparation and investigation of a biodegradable nano-hydroxyapatite/polyester elastomer composites

Nano-hydroxyapatite(n-HA)/poly((1，2-propanediol-sebacate)-citrate) (1，2-PPSC) composites were synthesized by condensation of 1，2-propanediol，sebacic acid，citric acid and n-HA. The structure was characterized by FTIR and ¹³C NMR；the micromorphology of n-HA and the dispersion property of n-HA in n-HA/1，2-PPSC composites were characterized by SEM and TEM. The results show that the chemical reactions between n-HA and sebacic acid never occur，n-HA and 1，2-PPSC matrix do not generate obviously chemical bond，and n-HA disperses uniformly in 1，2-PPSC matrix. DMA shows that there is a good nterfacial bonding between n-HA and 1，2-PPSC matrix. DSC and DMA show that n-HA decreases the chemical cross-link density of the composites，so the T_g of the composites decreases with increasing of mass fractions of n-HA. N-HA improves the hydrophilicity，decreases water absorption and reduces the degradation rates of n-HA/1，2-PPSC composites. Compared to the matrix，the mechanical properties of the composites are improved obviously；when the mass fraction of n-HA is 20%，the modulus of n-HA/1，2-PPSC composites increases 11.4 times，the tensile strength of n-HA/1，2-PPSC composites increases 8.2 times，while the elongation at break of n-HA/1，2-PPSC composites is basically unchanged.