A Novel Hydroxyapatite/Ethylene-Vinyl Acetate/Copolymer 66 Composite for Hard Tissue Regeneration

Abstract

The stiffness and bioactivity of polyamide 66 (PA66) have been previously improved by the addition of hydroxyapatite (HA); however, the toughness and processing ability of the HA/PA66 composite need further improvement. In this paper, ethylene-vinyl acetate (EVA) copolymer was used as a modifier to toughen the composite and improve the melt processability. The HA/EVA/PA66 ternary composites were prepared by a twin screw extruder and injection molding, and analyzed by XRD, DSC, SEM, and mechanical testing. The results demonstrate that EVA has good miscibility with a PA66 matrix and result in a uniform distribution of fine HA particles in the composite. With increasing EVA incorporation, the brittle fracture of PA66 and HA/PA66 gradually became ductile fracture. EVA can effectively improve the impact strength and melt processability of the composite; the increased brittleness of HA/PA66 composite by HA addition can be counteracted by incorporation of EVA modifier. The increase in impact strength of the HA/EVA/PA66 composite can be explained on the basis of better stress transfer in the presence of EVA and by finer dispersion of HA particles.

Keywords:

• composite
• ethylene-vinyl acetate copolymer
• hydroxyapatite
• mechanical property
• morphology
• polyamide 66

Acknowledgement

The authors gratefully acknowledge China 863 funds (No. 2007AA03Z328766) and China 973 funds (No.2007CB936102) for financial support.