The Influence of the Heat Treatment Temperatures in Calcium Phosphate Synthesis

The aim of this work was to explore the use of economically viable sol-gel precursors to synthesize calcium phosphate, hydroxyapatite phase. The influence of heat treatment temperature was evaluated. The powders were calcined at different temperatures ranging from 300 to 600 degrees C. Chemical phase compositions were evaluated by X-ray diffraction (XRD), thermal analysis (TG-DTA/DSC) and diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). The hydroxyapatite phase was obtained above 500 degrees C. The morphology and particle size were analyzed by scanning electron microscopy (SEM). This work showed that hydroxyapatite (HA) can be obtained using a simple, fast and low-cost apparatus method at low temperature synthesis. It could be concluded that this method can be also applied to bioactive calcium phosphates coatings of implant surfaces.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Cellulose nanocomposites with nanofibres isolated from pineapple leaf fibers for medical applications

Nanocellulose is the crystalline domains obtained from renewable cellulosic sources, used to increase mechanical properties and biodegrability in polymer composites. This work has been to study how high pressure defibrillation and chemical purification affect the PALF fibre morphology from micro to nanoscale. Microscopy techniques and X-ray diffraction were used to study the structure and properties of the prepared nanofibers and composites. Microscopy studies showed that the used individualization processes lead to a unique morphology of interconnected web-like structure of PALF fibers. The produced nanofibers were bundles of cellulose fibers of widths ranging between 5 and 15 nm and estimated lengths of several micrometers. Percentage yield and aspect ratio of the nanofiber obtained by this technique is found to be very high in comparison with other conventional methods. The nanocomposites were prepared by means of compression moulding, by stacking the nanocellulose fibre mats between polyurethane films. The results showed that the nanofibrils reinforced the polyurethane efficiently. The addition of 5 wt% of cellulose nanofibrils to PU increased the strength nearly 300% and the stiffness by 2600%. The developed composites were utilized to fabricate various versatile medical implants. (C) 2011 Elsevier Ltd. All rights reserved