Dynamic mechanical characterization of biodegradable composites of hydroxyapatite and polylactides

The thermo-mechanical analysis of some novel, totally bioactive, three-comp onent composite systems intended for the repair and augmentation of bone ha s been performed. The composites are composed of hydroxyapatite (HA), parti culate reinforced biodegradable polylactic acid (PDLLA), with a second rein forcing phase of semi-crystalline, unidirectional fibers of polylactic acid (PLLA) homopolymer. Dynamic mechanical analysis (DMA) applied small-strain cyclic deformations to simulate physiological loading, The effect of the t wo fillers on the glass transition temperature of the matrix (T-g-PDLLA) an d on the viscoelastic parameters, storage modulus (E-I), and tan delta were analyzed. Thermal characterization with differential scanning calorimetry (DSC) was compared to the DMA data. It was established that the addition of HA and/or PLLA fibers increased E-I, both below and above T-g-PDLLA, The c ombination of both reinforcing agents was the most effective. The damping w as reduced with the addition of HA alone and in combination with PLLA fiber s. T-g-PDLLA was increased by the addition of HA, PLLA fibers, and the comb ination of the two reinforcing agents. The magnitude of the increase in T-g -PDLLA was similar for both types of reinforcement. (C) 2001 John Wiley & S ons, Inc.