International Journal of the Physical Sciences Vol. 6(29), pp. 6681-6691, 16 November, 2011 Available online at http://www.academicjournals.org/IJPS DOI: 10.5897/IJPS11.769 ISSN 1992 - 1950 ©2011 Academic Journals Full Length Research Paper Study of bioactivity, biodegradability and mechanical properties of polyurethane/nano-hydroxyapatite hybrid composites A. B. Martínez-Valencia 1,2 , G. Carbajal-De la Torre 2 , A. Duarte Moller 1 , H. E. Esparza-Ponce 1 * and M. A. Espinosa-Medina 2 1 Centro de Investigación en Materiales Avanzados CIMAV, Ave. Miguel de Cervantes 120 C.P. 31109, Complejo Industrial Chihuahua, Chihuahua, México. 2 Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo UMSNH, Santiago Tapia 403. Centro C.P. 58000. Morelia, Michoacán, Mexico. Accepted 11 October, 2011 The present research is focused on the study of a series of polyurethane/nano-hydroxyapatite composites with different nano-hydroxyapatite (nHA) compositions (0, 10, 20, 30 and 40 %wt). Mechanical, biodegradability and bioactivity properties of composites were evaluated. Tensile tests were performed using a dynamic mechanical analyzer (DMA). Biodegradability and bioactivity studies were done by immersion into phosphate buffered saline (PBS) and simulated body fluid (SBF) solutions respectively. Both biodegradability and bioactivity behavior of specimens were monitored by gravimetric method and morphologically characterized by Scanning Electron Microscopy (SEM). Mechanical test results showed that both pure polyurethane and the 10 wt% nHA composite presented similar Young’s modulus of 4.4 and 4.7 MPa, respectively. On the other hand, at higher nHA contents, the composites became relatively brittle showing Young’s modulus from 6.6 to 8. 3 MPa values. The biodegradation rate increased as a function of nHA contents. In that way, polyurethane and composite containing 10 and 40 wt% nano-hydroxyapatite lost weight about 3 and 4wt%, respectively during 56 days of immersion. Study of bioactivity revealed that the composites exhibits advantages compared with polyurethane. The formation of bone-like apatite microstructure was corroborated by X-Ray Diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) coupled energy dispersive X-ray (EDS) analysis. Key words: Polyurethane, nano-hydroxyapatite, biodegradability, bioactivity, mechanical properties. INTRODUCTION During the last two decades, polymer/bioactive ceramic composite materials have been extensively developed for tissue engineering applications such as bone tissue regeneration (Ramakrishna et al., 2001). Different polymer/calcium phosphate composites for bone replace- ment and tissue regeneration applications were studied, trying to improve their mechanical properties in addition to their bioactivity, biodegradability and biocompatibility *Corresponding author. E-mail: hilda.esparza@cimav.edu.mx, georginacar@gmail.com. Tel: +52(614)4391103. Fax: +52(614)4391130. properties (Thein-Han et al., 2009; Liu et al., 2009; Biossard et al., 2009; Laschke et al., 2010; Jayabalan et al., 2010). In this sense, Ren et al. (2007) studied some poly (D,L-lactide)/ nano-hydroxyapatite (nHA) composites produced by in-situ polymerization of nHA and lactide monomer (2 and 4 wt.%); those composites presented high porosity but better hydrophilic capacity, mechanical properties improvement and excellent biocompatibility. Zhao et al. (2008) reported a highly porous hydroxiapatite (HA)/polycaprolactone composite scaffold with inter- connected porosity, superior mechanical and bioactive properties became a bone substitute option for clinical applications. Dong et al. (2009) reported that (30 wt%) nHA/PU composites scaffold presented good biocompati-