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