Mechanical properties of composites made up of high-density polyethylene (HDPE) and silanated TiO2 particles for use as a bone-repairing material were investigated in comparison with those of the composites of HDPE with unsilanized TiO2 particles. The interfacial morphology and interaction between silanated TiO2 and HDPE were analyzed by means of Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The absorption in spectral bands related to the carboxyl bond in the silane-coupling agent, the vinyl group in the HDPE, and the formation of the ether bond was studied in order to assess the influence of the silane-coupling agent. The SEM micrograph showed that the "bridging effect" between HDPE and TiO2 was brought about by the silane-coupling agent. The use of the silane-coupling agent and the increase of the hot-pressing pressure for shaping the composites facilitated the penetration of polymer into cavities between individual TiO2 particles, which increased the density of the composite. Therefore, mechanical properties such as bending yield strength and Young's modulus increased from 49 MPa and 7.5 GPa to 65 MPa and 10 GPa, respectively, after the silane-coupling treatment and increase in the hot-pressing pressure. (c) 2005 Elsevier Ltd. All rights reserved.