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 interfacial 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.