Hydroxyapatite-polyethylene composites for bone substitution: effects of ceramic particle size and morphology.

Synthetic hydroxyapatite particles of two median sizes and different morphologies have been used to manufacture hydroxyapatite reinforced high density polyethylene composites (HAPEX) for medical applications. The effects of hydroxyapatite particle size on properties of the resultant composites were investigated using various techniques. It was found that composites with smaller hydroxyapatite particles had higher torsional modulus, tensile modulus and tensile strength, but lower strain to failure. Examination of fracture surfaces revealed that only a mechanical bond existed between the filler and the matrix. It was shown that dynamic mechanical analysis is useful in studying the viscoelastic behaviour of the composite.