Effect of morphological features and surface area of hydroxyapatite on the fatigue behavior of hydroxyapatite-polyethylene composites.

The effect of surface area and morphological features of filler particles on the fatigue behavior of hydroxyapatite-filled high-density polyethylene composites was studied. Composites containing 40 vol % filler were injection-molded into tensile bars, gamma-irradiated, and subjected to sinusoidal tensile fatigue at a frequency of 2 Hz. To simulate the physiological environment, the tests were conducted at 37 degrees C in saline. Results showed that properties such as secant modulus, cyclic energy dissipation, dynamic creep strain, hysteresis loops, and even fracture surfaces differ depending on the morphology and surface area of the fillers used.