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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. [ABSTRACT FROM PUBLISHER]

This research investigated the injection-molding techniques to produce hydroxyapatite (HA)/ethylene-vinyl acetate (EVA)/polyamide 66 (PA66) composite scaffolds. The effects of HA, EVA, azodicarbonamide (AC) content and shot size on the mechanical properties, pore morphology, porosity and crystallization behavior of the composite scaffolds were analyzed by XRD, DSC, SEM and mechanical test. The compressive modulus and strength of the HA/EVA/PA66 scaffolds with a pore size of 200-600 µm are close to the cancellous bone. Compared with common methods to fabricate scaffolds, this process makes the fabrication of composite scaffolds come true in a rapid and convenient manner. [ABSTRACT FROM AUTHOR]