The influence of gamma radiation on the glass transition of hydroxyapatite/poly L-lactide composite
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Hydroxyapatite/poly L-lactide (HAp/PLLA) is a composite biomaterial which has been widely utilized for substitution and reparation of the hard bone tissue. It is well known that gamma irradiation has been successfully employed in the modification/sterilization of such porous composites and that it has advantages over other procedures. In this study, differential scanning calorimetry (DSC) measurements were made to investigate the influence of the radiation on glass transition behavior and structural relaxation, as well as to estimate the activation energy for this process. The apparent activation energy Delta H* for structural relaxation in the glass transition region was determined on the basis of the heating rate dependence of the glass transition temperature T-g. Furthermore, the results were correlated with those obtained by gel permeation chromatography (GPC). Our findings support the fact that the radiation-induced chain scission in the PLLA phase is the main reason for the decre...ase of the glass transition temperature and/or activation energy with the absorbed dose.
Keywords:apparent activation energy / gamma radiation / glass transition / hydroxyapatite/poly L-lactide
Source:Materials Science Forum, 2007, 555, 497-+
- Research Trends in Contemporary Materials Science, 8th Conference of the Yugoslav-Materials-Research-Society (Yu-MRS), Sep 04-08, 2006, Herceg Novi, Montenegro